Version 2.8.0-dev.7.0

Merge commit '5f5e1db141e529a89973e6dfab95da5cb1f6a4d5' into dev
diff --git a/.packages b/.packages
index cdbd2cd..b6c666c 100644
--- a/.packages
+++ b/.packages
@@ -7,6 +7,7 @@
 # Please update this file if you add a package to DEPS or /pkg
 #
 _fe_analyzer_shared:pkg/_fe_analyzer_shared/lib
+_js_interop_checks:pkg/_js_interop_checks/lib
 analysis_server:pkg/analysis_server/lib
 analysis_server_client:pkg/analysis_server_client/lib
 analysis_tool:pkg/analysis_tool/lib
@@ -93,6 +94,7 @@
 source_maps:third_party/pkg/source_maps/lib
 source_span:third_party/pkg/source_span/lib
 stack_trace:third_party/pkg/stack_trace/lib
+stagehand:third_party/pkg/stagehand/lib
 status_file:pkg/status_file/lib
 stream_channel:third_party/pkg/stream_channel/lib
 string_scanner:third_party/pkg/string_scanner/lib
diff --git a/CHANGELOG.md b/CHANGELOG.md
index b4164fb..44cdce0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -36,17 +36,29 @@
   `package:js` interop specification must now be wrapped with a call to
   `allowInterop`. This behavior was always enforced by `dart2js`, but was not
   enforced consistently in `ddc`. It will now be enforced in both.
+* JS interop classes with an index operator are now static errors.
 
  [announcement]: https://github.com/dart-lang/sdk/issues/38994
 
+#### Dart2JS
+
+* JS interop classes with an index operator are now static errors instead of
+  causing invalid code in dart2js.
+* **Breaking Change**: The subtyping rule for generic functions is now more
+  forgiving. Corresponding type parameter bounds now only need to be mutual
+  subtypes rather than structurally equal up to renaming of bound type variables
+  and equating all top types.
+
 #### Linter
 
-The Linter was updated to `0.1.109`, which includes:
+The Linter was updated to `0.1.110`, which includes:
 
-* an improved `prefer_single_quotes` lint message
-* `unnecessary_finals` fixed to not flag fields
-* `unnecessary_lambdas` fixed to work with type arguments
-* (internal) migration to use analyzer `LinterContext.resolveNameInScope()` API
+* fixed flutter web plugin detection in `avoid_web_libraries_in_flutter`
+* new lint: `unnecessary_string_interpolations`
+* new lint: `missing_whitespace_between_adjacent_strings`
+* `avoid_unused_constructor_parameters` updated to ignore deprecated parameters
+* new lint: `no_runtimeType_toString`
+* miscellaneous doc fixes
 
 #### Pub
 
diff --git a/DEPS b/DEPS
index 48b36f5..d261291 100644
--- a/DEPS
+++ b/DEPS
@@ -39,7 +39,7 @@
   # co19 is a cipd package. Use update.sh in tests/co19[_2] to update these
   # hashes. It requires access to the dart-build-access group, which EngProd
   # has.
-  "co19_rev": "6d84d8db719f2076e0c2bbc41db9297e803ab445",
+  "co19_rev": "5a3388d1f79cc3c61f9cdc1b3eaaa405bd62c882",
   "co19_2_rev": "368bfa9e877a2df003547f64bb17e30596af10c7",
 
   # As Flutter does, we use Fuchsia's GN and Clang toolchain. These revision
@@ -102,7 +102,7 @@
   "intl_tag": "0.15.7",
   "jinja2_rev": "2222b31554f03e62600cd7e383376a7c187967a1",
   "json_rpc_2_tag": "2.0.9",
-  "linter_tag": "0.1.109",
+  "linter_tag": "0.1.110",
   "logging_tag": "0.11.3+2",
   "markupsafe_rev": "8f45f5cfa0009d2a70589bcda0349b8cb2b72783",
   "markdown_tag": "2.1.1",
@@ -134,6 +134,7 @@
   "source_maps_tag": "8af7cc1a1c3a193c1fba5993ce22a546a319c40e",
   "source_span_tag": "1.5.5",
   "stack_trace_tag": "1.9.3",
+  "stagehand_tag": "v3.3.6",
   "stream_channel_tag": "2.0.0",
   "string_scanner_tag": "1.0.3",
   "test_descriptor_tag": "1.1.1",
@@ -380,6 +381,8 @@
       "@" + Var("source_map_stack_trace_tag"),
   Var("dart_root") + "/third_party/pkg/stack_trace":
       Var("dart_git") + "stack_trace.git" + "@" + Var("stack_trace_tag"),
+  Var("dart_root") + "/third_party/pkg/stagehand":
+      Var("dart_git") + "stagehand.git" + "@" + Var("stagehand_tag"),
   Var("dart_root") + "/third_party/pkg/stream_channel":
       Var("dart_git") + "stream_channel.git" +
       "@" + Var("stream_channel_tag"),
@@ -476,7 +479,7 @@
     "packages": [
       {
         "package": "dart/cfe/dart2js_dills",
-        "version": "binary_version:29_37",
+        "version": "binary_version:38",
       }
     ],
     "dep_type": "cipd",
diff --git a/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart b/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
index eab740f..a762485 100644
--- a/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
+++ b/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
@@ -5230,6 +5230,17 @@
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeJsInteropIndexNotSupported =
+    messageJsInteropIndexNotSupported;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageJsInteropIndexNotSupported = const MessageCode(
+    "JsInteropIndexNotSupported",
+    message:
+        r"""JS interop classes do not support [] and []= operator methods.""",
+    tip: r"""Try replacing with a normal method.""");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<
     Message Function(String name)> templateLabelNotFound = const Template<
         Message Function(String name)>(
@@ -6408,6 +6419,53 @@
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(String name)> templateNullableTearoffError =
+    const Template<Message Function(String name)>(
+        messageTemplate:
+            r"""Can't tear off method '#name' from a potentially null value.""",
+        withArguments: _withArgumentsNullableTearoffError);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String name)> codeNullableTearoffError =
+    const Code<Message Function(String name)>(
+  "NullableTearoffError",
+  templateNullableTearoffError,
+);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsNullableTearoffError(String name) {
+  if (name.isEmpty) throw 'No name provided';
+  name = demangleMixinApplicationName(name);
+  return new Message(codeNullableTearoffError,
+      message:
+          """Can't tear off method '${name}' from a potentially null value.""",
+      arguments: {'name': name});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(String name)> templateNullableTearoffWarning =
+    const Template<Message Function(String name)>(
+        messageTemplate:
+            r"""Tearing off method '#name' from a potentially null value.""",
+        withArguments: _withArgumentsNullableTearoffWarning);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String name)> codeNullableTearoffWarning =
+    const Code<Message Function(String name)>(
+        "NullableTearoffWarning", templateNullableTearoffWarning,
+        severity: Severity.warning);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsNullableTearoffWarning(String name) {
+  if (name.isEmpty) throw 'No name provided';
+  name = demangleMixinApplicationName(name);
+  return new Message(codeNullableTearoffWarning,
+      message:
+          """Tearing off method '${name}' from a potentially null value.""",
+      arguments: {'name': name});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeObjectExtends = messageObjectExtends;
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
@@ -6548,6 +6606,17 @@
     message: r"""An operator can't have optional parameters.""");
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeOperatorWithTypeParameters =
+    messageOperatorWithTypeParameters;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageOperatorWithTypeParameters = const MessageCode(
+    "OperatorWithTypeParameters",
+    analyzerCodes: <String>["TYPE_PARAMETER_ON_OPERATOR"],
+    message: r"""Types parameters aren't allowed when defining an operator.""",
+    tip: r"""Try removing the type parameters.""");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<Message Function(String name)> templateOverriddenMethodCause =
     const Template<Message Function(String name)>(
         messageTemplate: r"""This is the overridden method ('#name').""",
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_in_from_mixed/main.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_in_from_mixed/main.dart
new file mode 100644
index 0000000..07fa2ca
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_in_from_mixed/main.dart
@@ -0,0 +1,31 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=true*/
+
+import 'opt_out.dart';
+
+/*class: Nnbd:Nnbd,Object*/
+abstract class Nnbd {
+  /*member: Nnbd.mandatory:void Function(int!)!*/
+  void mandatory(int param);
+  /*member: Nnbd.optional:void Function(int?)!*/
+  void optional(int? param);
+}
+
+/*class: Both1:Both1,Legacy,Nnbd,Object*/
+class Both1 implements Legacy, Nnbd {
+  /*member: Both1.mandatory:void Function(int!)!*/
+  void mandatory(param) {}
+  /*member: Both1.optional:void Function(int?)!*/
+  void optional(param) {}
+}
+
+/*class: Both2:Both2,Legacy,Nnbd,Object*/
+class Both2 implements Nnbd, Legacy {
+  /*member: Both2.mandatory:void Function(int!)!*/
+  void mandatory(param) {}
+  /*member: Both2.optional:void Function(int?)!*/
+  void optional(param) {}
+}
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_in_from_mixed/opt_out.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_in_from_mixed/opt_out.dart
new file mode 100644
index 0000000..26a4379
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_in_from_mixed/opt_out.dart
@@ -0,0 +1,15 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=false*/
+
+// @dart = 2.5
+
+/*class: Legacy:Legacy,Object*/
+abstract class Legacy {
+  /*member: Legacy.mandatory:void Function(int*)**/
+  void mandatory(int param);
+  /*member: Legacy.optional:void Function(int*)**/
+  void optional(int param);
+}
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_out_from_mixed/main.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_out_from_mixed/main.dart
new file mode 100644
index 0000000..4a40b97
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_out_from_mixed/main.dart
@@ -0,0 +1,32 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=false*/
+
+// @dart = 2.5
+import 'opt_in.dart';
+
+/*class: Legacy:Legacy,Object*/
+abstract class Legacy {
+  /*member: Legacy.mandatory:void Function(int*)**/
+  void mandatory(int param);
+  /*member: Legacy.optional:void Function(int*)**/
+  void optional(int param);
+}
+
+/*class: Both1:Both1,Legacy,Nnbd,Object*/
+class Both1 implements Legacy, Nnbd {
+  /*member: Both1.mandatory:void Function(int*)**/
+  void mandatory(param) {}
+  /*member: Both1.optional:void Function(int*)**/
+  void optional(param) {}
+}
+
+/*class: Both2:Both2,Legacy,Nnbd,Object*/
+class Both2 implements Nnbd, Legacy {
+  /*member: Both2.mandatory:void Function(int*)**/
+  void mandatory(param) {}
+  /*member: Both2.optional:void Function(int*)**/
+  void optional(param) {}
+}
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_out_from_mixed/opt_in.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_out_from_mixed/opt_in.dart
new file mode 100644
index 0000000..9e428bb
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/infer_opt_out_from_mixed/opt_in.dart
@@ -0,0 +1,13 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=true*/
+
+/*class: Nnbd:Nnbd,Object*/
+abstract class Nnbd {
+  /*member: Nnbd.mandatory:void Function(int!)!*/
+  void mandatory(int param);
+  /*member: Nnbd.optional:void Function(int?)!*/
+  void optional(int? param);
+}
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/_internal.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/_internal.dart
new file mode 100644
index 0000000..5e321c6
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/_internal.dart
@@ -0,0 +1,11 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=true*/
+
+import 'dart:core' as core;
+
+/*cfe.class: Symbol:Object,Symbol,Symbol*/
+/*cfe:builder.class: Symbol:Object,Symbol*/
+class Symbol extends core.Symbol {}
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/async.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/async.dart
new file mode 100644
index 0000000..bb4fee5
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/async.dart
@@ -0,0 +1,11 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=true*/
+
+/*class: Future:Future<T>,Object*/
+class Future<T> {}
+
+/*class: FutureOr:FutureOr<T>,Object*/
+class FutureOr<T> {}
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/collection.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/collection.dart
new file mode 100644
index 0000000..c346cae
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/collection.dart
@@ -0,0 +1,5 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=true*/
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/core.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/core.dart
new file mode 100644
index 0000000..38f91c1
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/core.dart
@@ -0,0 +1,63 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=true*/
+
+import 'dart:async';
+import 'dart:_internal';
+
+export 'dart:async' show Future;
+
+/*class: Object:Object*/
+class Object {
+  const Object();
+
+  bool operator ==(Object other) => true;
+}
+
+/*class: Null:Null,Object*/
+class Null {
+  factory Null._uninstantiable() {
+    throw 'class Null cannot be instantiated';
+  }
+}
+
+/*class: bool:Object,bool*/
+class bool {}
+
+/*class: num:Object,num*/
+class num {}
+
+/*class: int:Object,int,num*/
+class int extends num {}
+
+/*class: double:Object,double,num*/
+class double extends num {}
+
+/*class: String:Object,String*/
+class String {}
+
+/*class: Iterable:Iterable<E>,Object*/
+class Iterable<E> {}
+
+/*class: List:Iterable<E>,List<E>,Object*/
+class List<E> implements Iterable<E> {}
+
+/*class: Set:Iterable<E>,Object,Set<E>*/
+class Set<E> implements Iterable<E> {}
+
+/*class: Map:Map<K,V>,Object*/
+class Map<K, V> {}
+
+/*class: Stream:Object,Stream<E>*/
+class Stream<E> {}
+
+/*class: Function:Function,Object*/
+class Function {}
+
+/*class: Symbol:Object,Symbol*/
+class Symbol {}
+
+/*class: Type:Object,Type*/
+class Type {}
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/libraries.json b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/libraries.json
new file mode 100644
index 0000000..98467d2
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/libraries.json
@@ -0,0 +1,18 @@
+{
+  "none": {
+    "libraries": {
+      "async": {
+        "uri": "async.dart"
+      },
+      "core": {
+        "uri": "core.dart"
+      },
+      "collection": {
+        "uri": "collection.dart"
+      },
+      "_internal": {
+        "uri": "_internal.dart"
+      }
+    }
+  }
+}
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/main.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/main.dart
new file mode 100644
index 0000000..31806e7
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/main.dart
@@ -0,0 +1,8 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=true*/
+
+import 'opt_in.dart';
+import 'opt_out.dart';
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/opt_in.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/opt_in.dart
new file mode 100644
index 0000000..fa55142
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/opt_in.dart
@@ -0,0 +1,11 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=true*/
+
+/*class: Class:Class,Object*/
+class Class {
+  /*member: Class.==:bool! Function(Object!)!*/
+  operator ==(other) => true;
+}
diff --git a/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/opt_out.dart b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/opt_out.dart
new file mode 100644
index 0000000..1d7d8a1
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/object_equals/opt_out.dart
@@ -0,0 +1,45 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*library: nnbd=false*/
+
+// @dart=2.6
+
+/*class: Class1:Class1,Object*/
+class Class1 {
+  /*member: Class1.==:bool! Function(dynamic)**/
+  operator ==(other) => true;
+}
+
+/*class: Class2a:Class2a,Object*/
+abstract class Class2a {
+  /*member: Class2a.==:bool* Function(Object*)**/
+  bool operator ==(Object other);
+}
+
+/*class: Class2b:Class2a,Class2b,Object*/
+class Class2b extends Class2a {
+  /*member: Class2b.==:bool* Function(Object*)**/
+}
+
+/*class: Class3a:Class3a,Object*/
+class Class3a {
+  /*member: Class3a.==:bool* Function(Object*)**/
+}
+
+/*class: Class3b:Class3a,Class3b,Object*/
+abstract class Class3b extends Class3a {
+  /*member: Class3b.==:bool* Function(Object*)**/
+  bool operator ==(Object other);
+}
+
+/*class: Class3c:Class3a,Class3b,Class3c,Object*/
+class Class3c extends Class3b {
+  /*member: Class3c.==:bool* Function(Object*)**/
+}
+
+/*class: Foo:Foo,Object*/
+class Foo extends /*error: TypeNotFound*/ Unresolved {
+  /*member: Foo.==:bool* Function(Object*)**/
+}
diff --git a/pkg/_js_interop_checks/README.md b/pkg/_js_interop_checks/README.md
new file mode 100644
index 0000000..f811587
--- /dev/null
+++ b/pkg/_js_interop_checks/README.md
@@ -0,0 +1 @@
+Shared kernel visitors checking for incorrect usage of `@JS()` style interop.
diff --git a/pkg/_js_interop_checks/lib/js_interop_checks.dart b/pkg/_js_interop_checks/lib/js_interop_checks.dart
new file mode 100644
index 0000000..045c0d5
--- /dev/null
+++ b/pkg/_js_interop_checks/lib/js_interop_checks.dart
@@ -0,0 +1,34 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:kernel/kernel.dart';
+import 'package:kernel/target/targets.dart';
+import 'package:_fe_analyzer_shared/src/messages/codes.dart'
+    show Message, LocatedMessage, messageJsInteropIndexNotSupported;
+
+import 'src/js_interop.dart';
+
+class JsInteropChecks extends RecursiveVisitor<void> {
+  final DiagnosticReporter<Message, LocatedMessage> _diagnosticsReporter;
+
+  JsInteropChecks(this._diagnosticsReporter);
+
+  @override
+  void visitClass(Class c) {
+    if (!hasJSInteropAnnotation(c)) return;
+    super.visitClass(c);
+  }
+
+  @override
+  void visitProcedure(Procedure procedure) {
+    if (procedure.isStatic) return;
+    if (procedure.name.name == '[]=' || procedure.name.name == '[]') {
+      _diagnosticsReporter.report(
+          messageJsInteropIndexNotSupported,
+          procedure.fileOffset,
+          procedure.name.name.length,
+          procedure.location.file);
+    }
+  }
+}
diff --git a/pkg/_js_interop_checks/lib/src/js_interop.dart b/pkg/_js_interop_checks/lib/src/js_interop.dart
new file mode 100644
index 0000000..eb5c9f5
--- /dev/null
+++ b/pkg/_js_interop_checks/lib/src/js_interop.dart
@@ -0,0 +1,41 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:kernel/kernel.dart';
+
+/// Returns true iff the class has an `@JS(...)` annotation from `package:js`.
+bool hasJSInteropAnnotation(Class c) =>
+    c.annotations.any(_isPublicJSAnnotation);
+
+final _packageJs = Uri.parse('package:js/js.dart');
+
+/// Returns [true] if [e] is the `JS` annotation from `package:js`.
+bool _isPublicJSAnnotation(Expression value) {
+  var c = _annotationClass(value);
+  return c != null &&
+      c.name == 'JS' &&
+      c.enclosingLibrary.importUri == _packageJs;
+}
+
+/// Returns the class of the instance referred to by metadata annotation [node].
+///
+/// For example:
+///
+/// - `@JS()` would return the "JS" class in "package:js".
+/// - `@anonymous` would return the "_Anonymous" class in "package:js".
+///
+/// This function works regardless of whether the CFE is evaluating constants,
+/// or whether the constant is a field reference (such as "anonymous" above).
+Class _annotationClass(Expression node) {
+  if (node is ConstantExpression) {
+    var constant = node.constant;
+    if (constant is InstanceConstant) return constant.classNode;
+  } else if (node is ConstructorInvocation) {
+    return node.target.enclosingClass;
+  } else if (node is StaticGet) {
+    var type = node.target.getterType;
+    if (type is InterfaceType) return type.classNode;
+  }
+  return null;
+}
diff --git a/pkg/_js_interop_checks/pubspec.yaml b/pkg/_js_interop_checks/pubspec.yaml
new file mode 100644
index 0000000..abca579
--- /dev/null
+++ b/pkg/_js_interop_checks/pubspec.yaml
@@ -0,0 +1,5 @@
+name: _js_interop_checks
+publish_to: none
+
+environment:
+  sdk: '>=2.7.0 <3.0.0'
diff --git a/pkg/analysis_server/analysis_options.yaml b/pkg/analysis_server/analysis_options.yaml
index 44d21e8..44b31e6 100644
--- a/pkg/analysis_server/analysis_options.yaml
+++ b/pkg/analysis_server/analysis_options.yaml
@@ -9,11 +9,6 @@
   errors:
     # Increase the severity of the unused_import hint.
     unused_import: warning
-    # Ignoring "style" lint rules from pedantic for now. There are pre-existing
-    # violations that need to be cleaned up. Each one can be cleaned up and
-    # enabled according to the value provided.
-    avoid_return_types_on_setters: ignore
-    empty_catches: ignore
     prefer_contains: ignore
     # TODO(srawlins): At the time of writing, 2400 violations in lib/. The fix
     # is mechanical, via `dartfmt --fix-doc-comments`, but not worth the churn
@@ -30,7 +25,7 @@
     #
     # Delta from pedantic 1.8.0 to 1.9.0
     #
-    #- always_declare_return_types # 5645
+    - always_declare_return_types
     - always_require_non_null_named_parameters
     - annotate_overrides
     - avoid_null_checks_in_equality_operators
diff --git a/pkg/analysis_server/benchmark/integration/input_converter.dart b/pkg/analysis_server/benchmark/integration/input_converter.dart
index 0368037..c4ca71e 100644
--- a/pkg/analysis_server/benchmark/integration/input_converter.dart
+++ b/pkg/analysis_server/benchmark/integration/input_converter.dart
@@ -244,7 +244,7 @@
    * the temporary source used during performance measurement rather than
    * the original source when the instrumentation or log file was generated.
    */
-  translateSrcPaths(json) {
+  dynamic translateSrcPaths(json) {
     if (json is String) {
       return srcPathMap.translate(json);
     }
diff --git a/pkg/analysis_server/benchmark/integration/local_runner.dart b/pkg/analysis_server/benchmark/integration/local_runner.dart
index 7bfcbeb..a3d8253 100644
--- a/pkg/analysis_server/benchmark/integration/local_runner.dart
+++ b/pkg/analysis_server/benchmark/integration/local_runner.dart
@@ -10,7 +10,7 @@
 
 // Local driver for performance measurement
 
-main(List<String> args) {
+void main(List<String> args) {
   /*
    * Parse arguments
    */
diff --git a/pkg/analysis_server/benchmark/integration/main.dart b/pkg/analysis_server/benchmark/integration/main.dart
index acec9c4..9b6436f 100644
--- a/pkg/analysis_server/benchmark/integration/main.dart
+++ b/pkg/analysis_server/benchmark/integration/main.dart
@@ -17,7 +17,7 @@
 /**
  * Launch and interact with the analysis server.
  */
-main(List<String> rawArgs) {
+void main(List<String> rawArgs) {
   Logger logger = Logger('Performance Measurement Client');
   logger.onRecord.listen((LogRecord rec) {
     print(rec.message);
diff --git a/pkg/analysis_server/lib/lsp_protocol/protocol_generated.dart b/pkg/analysis_server/lib/lsp_protocol/protocol_generated.dart
index 062b70d..ddad80b 100644
--- a/pkg/analysis_server/lib/lsp_protocol/protocol_generated.dart
+++ b/pkg/analysis_server/lib/lsp_protocol/protocol_generated.dart
@@ -713,7 +713,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is CodeActionKind && o._value == _value;
 }
@@ -2561,7 +2561,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is CompletionItemKind && o._value == _value;
 }
@@ -3074,7 +3074,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) =>
       o is CompletionTriggerKind && o._value == _value;
@@ -3941,7 +3941,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is DiagnosticSeverity && o._value == _value;
 }
@@ -4910,7 +4910,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) =>
       o is DocumentHighlightKind && o._value == _value;
@@ -6090,7 +6090,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is ErrorCodes && o._value == _value;
 }
@@ -6378,7 +6378,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is FailureHandlingKind && o._value == _value;
 }
@@ -6409,7 +6409,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is FileChangeType && o._value == _value;
 }
@@ -6796,7 +6796,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is FoldingRangeKind && o._value == _value;
 }
@@ -7463,7 +7463,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is InsertTextFormat && o._value == _value;
 }
@@ -7965,7 +7965,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is MarkupKind && o._value == _value;
 }
@@ -8142,7 +8142,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is MessageType && o._value == _value;
 }
@@ -8320,7 +8320,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is Method && o._value == _value;
 }
@@ -10006,7 +10006,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) =>
       o is ResourceOperationKind && o._value == _value;
@@ -12010,7 +12010,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is SymbolKind && o._value == _value;
 }
@@ -15752,7 +15752,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) =>
       o is TextDocumentSaveReason && o._value == _value;
@@ -15876,7 +15876,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is TextDocumentSyncKind && o._value == _value;
 }
@@ -16415,7 +16415,7 @@
   String toString() => _value.toString();
 
   @override
-  get hashCode => _value.hashCode;
+  int get hashCode => _value.hashCode;
 
   bool operator ==(Object o) => o is WatchKind && o._value == _value;
 }
diff --git a/pkg/analysis_server/lib/lsp_protocol/protocol_special.dart b/pkg/analysis_server/lib/lsp_protocol/protocol_special.dart
index 7b82969..aa3d457 100644
--- a/pkg/analysis_server/lib/lsp_protocol/protocol_special.dart
+++ b/pkg/analysis_server/lib/lsp_protocol/protocol_special.dart
@@ -46,7 +46,7 @@
         _which = 2;
 
   @override
-  get hashCode => map((t) => t.hashCode, (t) => t.hashCode);
+  int get hashCode => map((t) => t.hashCode, (t) => t.hashCode);
 
   @override
   bool operator ==(o) => o is Either2<T1, T2> && o._t1 == _t1 && o._t2 == _t2;
@@ -84,7 +84,8 @@
         _which = 3;
 
   @override
-  get hashCode => map((t) => t.hashCode, (t) => t.hashCode, (t) => t.hashCode);
+  int get hashCode =>
+      map((t) => t.hashCode, (t) => t.hashCode, (t) => t.hashCode);
 
   @override
   bool operator ==(o) =>
@@ -145,8 +146,8 @@
         _which = 4;
 
   @override
-  get hashCode => map((t) => t.hashCode, (t) => t.hashCode, (t) => t.hashCode,
-      (t) => t.hashCode);
+  int get hashCode => map((t) => t.hashCode, (t) => t.hashCode,
+      (t) => t.hashCode, (t) => t.hashCode);
 
   @override
   bool operator ==(o) =>
diff --git a/pkg/analysis_server/lib/src/computer/computer_folding.dart b/pkg/analysis_server/lib/src/computer/computer_folding.dart
index 800827a..79c629a 100644
--- a/pkg/analysis_server/lib/src/computer/computer_folding.dart
+++ b/pkg/analysis_server/lib/src/computer/computer_folding.dart
@@ -62,7 +62,7 @@
       final hasBlankLine =
           _hasBlankLineBetween(lastComment, lastComment.next ?? firstToken);
 
-      // Also considerd non-single-line-comments as the end
+      // Also considered non-single-line-comments as the end
       final nextCommentIsDifferentType = lastComment.next != null &&
           lastComment.next.type != TokenType.SINGLE_LINE_COMMENT;
 
@@ -73,7 +73,7 @@
     }
   }
 
-  _addRegion(int startOffset, int endOffset, FoldingKind kind) {
+  void _addRegion(int startOffset, int endOffset, FoldingKind kind) {
     final CharacterLocation start = _lineInfo.getLocation(startOffset);
     final CharacterLocation end = _lineInfo.getLocation(endOffset);
 
@@ -83,7 +83,7 @@
     }
   }
 
-  _addRegionForAnnotations(List<Annotation> annotations) {
+  void _addRegionForAnnotations(List<Annotation> annotations) {
     if (annotations.isNotEmpty) {
       _addRegion(annotations.first.name.end, annotations.last.end,
           FoldingKind.ANNOTATIONS);
@@ -96,7 +96,7 @@
     return secondLoc.lineNumber - firstLoc.lineNumber > 1;
   }
 
-  _recordDirective(Directive node) {
+  void _recordDirective(Directive node) {
     _firstDirective ??= node;
     _lastDirective = node;
   }
diff --git a/pkg/analysis_server/lib/src/computer/computer_outline.dart b/pkg/analysis_server/lib/src/computer/computer_outline.dart
index a752c8a..bb273a2 100644
--- a/pkg/analysis_server/lib/src/computer/computer_outline.dart
+++ b/pkg/analysis_server/lib/src/computer/computer_outline.dart
@@ -411,7 +411,7 @@
 /**
  * A visitor for building local function outlines.
  */
-class _FunctionBodyOutlinesVisitor extends RecursiveAstVisitor {
+class _FunctionBodyOutlinesVisitor extends RecursiveAstVisitor<void> {
   final DartUnitOutlineComputer outlineComputer;
   final List<Outline> contents;
 
@@ -444,12 +444,12 @@
   }
 
   @override
-  visitFunctionDeclaration(FunctionDeclaration node) {
+  void visitFunctionDeclaration(FunctionDeclaration node) {
     contents.add(outlineComputer._newFunctionOutline(node, false));
   }
 
   @override
-  visitInstanceCreationExpression(InstanceCreationExpression node) {
+  void visitInstanceCreationExpression(InstanceCreationExpression node) {
     if (outlineComputer.withBasicFlutter &&
         outlineComputer.flutter.isWidgetCreation(node)) {
       List<Outline> children = <Outline>[];
@@ -469,7 +469,7 @@
   }
 
   @override
-  visitMethodInvocation(MethodInvocation node) {
+  void visitMethodInvocation(MethodInvocation node) {
     SimpleIdentifier nameNode = node.methodName;
 
     engine.Element nameElement = nameNode.staticElement;
diff --git a/pkg/analysis_server/lib/src/context_manager.dart b/pkg/analysis_server/lib/src/context_manager.dart
index 7e27b6b..41a62f9 100644
--- a/pkg/analysis_server/lib/src/context_manager.dart
+++ b/pkg/analysis_server/lib/src/context_manager.dart
@@ -265,7 +265,7 @@
   /**
    * Set the callback interface used to create, destroy, and update contexts.
    */
-  void set callbacks(ContextManagerCallbacks value);
+  set callbacks(ContextManagerCallbacks value);
 
   /**
    * A table mapping [Folder]s to the [AnalysisDriver]s associated with them.
diff --git a/pkg/analysis_server/lib/src/domains/analysis/implemented_dart.dart b/pkg/analysis_server/lib/src/domains/analysis/implemented_dart.dart
index f26f5c4..038755f 100644
--- a/pkg/analysis_server/lib/src/domains/analysis/implemented_dart.dart
+++ b/pkg/analysis_server/lib/src/domains/analysis/implemented_dart.dart
@@ -17,7 +17,7 @@
 
   ImplementedComputer(this.searchEngine, this.unitElement);
 
-  compute() async {
+  Future<void> compute() async {
     for (var element in unitElement.mixins) {
       await _computeForClassElement(element);
     }
diff --git a/pkg/analysis_server/lib/src/domains/analysis/navigation_dart.dart b/pkg/analysis_server/lib/src/domains/analysis/navigation_dart.dart
index aedfefc..ec3a02c 100644
--- a/pkg/analysis_server/lib/src/domains/analysis/navigation_dart.dart
+++ b/pkg/analysis_server/lib/src/domains/analysis/navigation_dart.dart
@@ -90,14 +90,14 @@
   }
 }
 
-class _DartNavigationComputerVisitor extends RecursiveAstVisitor {
+class _DartNavigationComputerVisitor extends RecursiveAstVisitor<void> {
   final ResourceProvider resourceProvider;
   final _DartNavigationCollector computer;
 
   _DartNavigationComputerVisitor(this.resourceProvider, this.computer);
 
   @override
-  visitAnnotation(Annotation node) {
+  void visitAnnotation(Annotation node) {
     Element element = node.element;
     if (element is ConstructorElement && element.isSynthetic) {
       element = element.enclosingElement;
@@ -121,21 +121,21 @@
   }
 
   @override
-  visitAssignmentExpression(AssignmentExpression node) {
+  void visitAssignmentExpression(AssignmentExpression node) {
     node.leftHandSide?.accept(this);
     computer._addRegionForToken(node.operator, node.staticElement);
     node.rightHandSide?.accept(this);
   }
 
   @override
-  visitBinaryExpression(BinaryExpression node) {
+  void visitBinaryExpression(BinaryExpression node) {
     node.leftOperand?.accept(this);
     computer._addRegionForToken(node.operator, node.staticElement);
     node.rightOperand?.accept(this);
   }
 
   @override
-  visitCompilationUnit(CompilationUnit unit) {
+  void visitCompilationUnit(CompilationUnit unit) {
     // prepare top-level nodes sorted by their offsets
     List<AstNode> nodes = <AstNode>[];
     nodes.addAll(unit.directives);
@@ -150,7 +150,7 @@
   }
 
   @override
-  visitConstructorDeclaration(ConstructorDeclaration node) {
+  void visitConstructorDeclaration(ConstructorDeclaration node) {
     // associate constructor with "T" or "T.name"
     {
       AstNode firstNode = node.returnType;
@@ -165,7 +165,7 @@
   }
 
   @override
-  visitConstructorName(ConstructorName node) {
+  void visitConstructorName(ConstructorName node) {
     AstNode parent = node.parent;
     if (parent is InstanceCreationExpression &&
         parent.constructorName == node) {
@@ -177,7 +177,7 @@
   }
 
   @override
-  visitDeclaredIdentifier(DeclaredIdentifier node) {
+  void visitDeclaredIdentifier(DeclaredIdentifier node) {
     if (node.type == null) {
       Token token = node.keyword;
       if (token?.keyword == Keyword.VAR) {
@@ -192,7 +192,7 @@
   }
 
   @override
-  visitExportDirective(ExportDirective node) {
+  void visitExportDirective(ExportDirective node) {
     ExportElement exportElement = node.element;
     if (exportElement != null) {
       Element libraryElement = exportElement.exportedLibrary;
@@ -202,7 +202,7 @@
   }
 
   @override
-  visitImportDirective(ImportDirective node) {
+  void visitImportDirective(ImportDirective node) {
     ImportElement importElement = node.element;
     if (importElement != null) {
       Element libraryElement = importElement.importedLibrary;
@@ -212,7 +212,7 @@
   }
 
   @override
-  visitIndexExpression(IndexExpression node) {
+  void visitIndexExpression(IndexExpression node) {
     super.visitIndexExpression(node);
     MethodElement element = node.staticElement;
     computer._addRegionForToken(node.leftBracket, element);
@@ -220,36 +220,37 @@
   }
 
   @override
-  visitLibraryDirective(LibraryDirective node) {
+  void visitLibraryDirective(LibraryDirective node) {
     computer._addRegionForNode(node.name, node.element);
   }
 
   @override
-  visitPartDirective(PartDirective node) {
+  void visitPartDirective(PartDirective node) {
     _addUriDirectiveRegion(node, node.element);
     super.visitPartDirective(node);
   }
 
   @override
-  visitPartOfDirective(PartOfDirective node) {
+  void visitPartOfDirective(PartOfDirective node) {
     computer._addRegionForNode(node.libraryName, node.element);
     super.visitPartOfDirective(node);
   }
 
   @override
-  visitPostfixExpression(PostfixExpression node) {
+  void visitPostfixExpression(PostfixExpression node) {
     super.visitPostfixExpression(node);
     computer._addRegionForToken(node.operator, node.staticElement);
   }
 
   @override
-  visitPrefixExpression(PrefixExpression node) {
+  void visitPrefixExpression(PrefixExpression node) {
     computer._addRegionForToken(node.operator, node.staticElement);
     super.visitPrefixExpression(node);
   }
 
   @override
-  visitRedirectingConstructorInvocation(RedirectingConstructorInvocation node) {
+  void visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) {
     Element element = node.staticElement;
     if (element != null && element.isSynthetic) {
       element = element.enclosingElement;
@@ -262,7 +263,7 @@
   }
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     if (node.parent is ConstructorDeclaration) {
       return;
     }
@@ -271,7 +272,7 @@
   }
 
   @override
-  visitSuperConstructorInvocation(SuperConstructorInvocation node) {
+  void visitSuperConstructorInvocation(SuperConstructorInvocation node) {
     Element element = node.staticElement;
     if (element != null && element.isSynthetic) {
       element = element.enclosingElement;
@@ -284,7 +285,7 @@
   }
 
   @override
-  visitVariableDeclarationList(VariableDeclarationList node) {
+  void visitVariableDeclarationList(VariableDeclarationList node) {
     /**
      * Return the element for the type inferred for each of the variables in the
      * given list of [variables], or `null` if not all variable have the same
diff --git a/pkg/analysis_server/lib/src/domains/analysis/occurrences_dart.dart b/pkg/analysis_server/lib/src/domains/analysis/occurrences_dart.dart
index 8882f6d..5bed880 100644
--- a/pkg/analysis_server/lib/src/domains/analysis/occurrences_dart.dart
+++ b/pkg/analysis_server/lib/src/domains/analysis/occurrences_dart.dart
@@ -22,11 +22,11 @@
   });
 }
 
-class _DartUnitOccurrencesComputerVisitor extends RecursiveAstVisitor {
+class _DartUnitOccurrencesComputerVisitor extends RecursiveAstVisitor<void> {
   final Map<Element, List<int>> elementsOffsets = <Element, List<int>>{};
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     Element element = node.staticElement;
     if (element != null) {
       _addOccurrence(element, node.offset);
diff --git a/pkg/analysis_server/lib/src/edit/fix/non_nullable_fix.dart b/pkg/analysis_server/lib/src/edit/fix/non_nullable_fix.dart
index 55bd4d3..23f5f5d 100644
--- a/pkg/analysis_server/lib/src/edit/fix/non_nullable_fix.dart
+++ b/pkg/analysis_server/lib/src/edit/fix/non_nullable_fix.dart
@@ -12,13 +12,11 @@
 import 'package:analyzer/dart/analysis/results.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/file_system/file_system.dart';
-import 'package:analyzer/file_system/overlay_file_system.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/task/options.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:nnbd_migration/nnbd_migration.dart';
-import 'package:path/path.dart' as path;
 import 'package:source_span/source_span.dart';
 import 'package:yaml/yaml.dart';
 
@@ -228,8 +226,8 @@
   /// Get the "root" of all [included] paths. See [includedRoot] for its
   /// definition.
   static String _getIncludedRoot(
-      List<String> included, OverlayResourceProvider provider) {
-    path.Context context = provider.pathContext;
+      List<String> included, ResourceProvider provider) {
+    var context = provider.pathContext;
     // This step looks like it may be expensive (`getResource`, splitting up
     // all of the paths, comparing parts, joining one path back together). In
     // practice, this should be cheap because typically only one path is given
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/highlight_css.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/highlight_css.dart
deleted file mode 100644
index 064be3c..0000000
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/highlight_css.dart
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-/* To regenerate this file:
-
-1. Build and download highlight.zip for Dart [1].
-2. Extract highlight.zip, and find styles/androidstudio.css.
-3. Run:
-
-       sed -i -e '/^const _highlightCss =/{
-       r'<(echo 'const _highlightCss = "'"$(base64 < styles/androidstudio.css)"'";')'
-       d
-       }' highlight_css.dart
-
-[1] https://highlightjs.org/download/
-*/
-
-import 'dart:convert';
-
-const _highlightCss =
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diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/highlight_js.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/highlight_js.dart
deleted file mode 100644
index 26b67ee..0000000
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/highlight_js.dart
+++ /dev/null
@@ -1,24 +0,0 @@
-// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-/* To regenerate this file:
-
-1. Build and download highlight.zip for Dart [1].
-2. Extract highlight.zip, and find highlight.pack.js.
-3. Run:
-
-       sed -i -e '/^const _highlightJs =/{
-       r'<(echo 'const _highlightJs = "'"$(base64 < highlight.pack.js)"'";')'
-       d
-       }' highlightjs.dart
-
-[1] https://highlightjs.org/download/
-*/
-
-import 'dart:convert';
-
-const _highlightJs =
-    '/*! highlight.js v9.15.10 | BSD3 License | git.io/hljslicense */
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diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/info_builder.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/info_builder.dart
index cd994aa..4a2b560f 100644
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/info_builder.dart
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/info_builder.dart
@@ -116,6 +116,9 @@
 
   /// Return detail text for a fix built from an edge with origin info [origin]
   /// and [fixKind].
+  ///
+  /// Text is meant to be used as the beginning of a sentence. It is written in
+  /// present tense, beginning with a capital letter, not ending in a period.
   String _baseDescriptionForOrigin(
       EdgeOriginInfo origin, NullabilityFixKind fixKind) {
     AstNode node = origin.node;
@@ -162,8 +165,8 @@
     }
 
     if (origin.kind == EdgeOriginKind.listLengthConstructor) {
-      return 'List value type must be nullable because a length is specified,'
-          ' and the list items are initialized as null.';
+      return 'A length is specified in the "List()" constructor and the list '
+          'items are initialized to null';
     }
 
     CompilationUnit unit = node.thisOrAncestorOfType<CompilationUnit>();
@@ -173,10 +176,6 @@
       return 'Used on line $lineNumber, when it is possibly uninitialized';
     }
 
-    if (parent is ArgumentList) {
-      return capitalize('$nullableValue is passed as an argument');
-    }
-
     /// If the [node] is inside the return expression for a function body,
     /// return the function body. Otherwise return `null`.
     FunctionBody findFunctionBody() {
@@ -226,7 +225,9 @@
       }
     } else if (node is InvocationExpression &&
         origin.kind == EdgeOriginKind.namedParameterNotSupplied) {
-      return 'This named parameter was omitted in a call to this function';
+      return 'This named parameter is omitted in a call to this function';
+    } else if (parent is ArgumentList) {
+      return capitalize('$nullableValue is passed as an argument');
     } else if (parent is VariableDeclaration) {
       AstNode grandparent = parent.parent?.parent;
       if (grandparent is FieldDeclaration) {
@@ -271,6 +272,28 @@
       EdgeOriginInfo origin, EdgeInfo edge, NullabilityFixKind fixKind) {
     AstNode node = origin.node;
     NavigationTarget target;
+    TypeAnnotation type = info.typeAnnotationForNode(edge.sourceNode);
+    AstNode typeParent = type?.parent;
+
+    if (typeParent is GenericFunctionType && type == typeParent.returnType) {
+      var description =
+          'A function-typed value with a nullable return type is assigned';
+      target = _proximateTargetForNode(origin.source.fullName, node);
+      return RegionDetail(description, target);
+    }
+    if (typeParent is FormalParameter) {
+      FormalParameterList parameterList =
+          typeParent.parent is DefaultFormalParameter
+              ? typeParent.parent.parent
+              : typeParent.parent;
+      if (parameterList.parent is GenericFunctionType) {
+        var description =
+            'The function-typed element in which this parameter is declared is '
+            'assigned to a function whose matching parameter is nullable';
+        target = _proximateTargetForNode(origin.source.fullName, node);
+        return RegionDetail(description, target);
+      }
+    }
 
     // Some nodes don't need a target; default formal parameters
     // without explicit default values, for example.
@@ -283,7 +306,6 @@
         // link to the either the corresponding parameter in the declaration in
         // the superclass, or the return type in the declaration in that
         // subclass.
-        TypeAnnotation type = info.typeAnnotationForNode(edge.sourceNode);
         if (type != null) {
           CompilationUnit unit = type.thisOrAncestorOfType<CompilationUnit>();
           target = _proximateTargetForNode(
@@ -518,7 +540,7 @@
         if (details.isNotEmpty) {
           TypeAnnotation node = nonNullableType.key;
           regions.add(RegionInfo(
-              RegionType.nonNullableType,
+              RegionType.unchanged,
               mapper.map(node.offset),
               node.length,
               lineInfo.getLocation(node.offset).lineNumber,
@@ -566,18 +588,17 @@
             info != null ? _computeEdits(info, sourceOffset) : [];
         List<RegionDetail> details = _computeDetails(edit);
         var lineNumber = lineInfo.getLocation(sourceOffset).lineNumber;
-        if (length > 0) {
-          if (explanation != null) {
-            regions.add(RegionInfo(RegionType.fix, offset, length, lineNumber,
-                explanation, details,
+        if (explanation != null) {
+          if (length > 0) {
+            regions.add(RegionInfo(RegionType.remove, offset, length,
+                lineNumber, explanation, details,
+                edits: edits));
+          } else {
+            regions.add(RegionInfo(RegionType.add, offset, replacement.length,
+                lineNumber, explanation, details,
                 edits: edits));
           }
         }
-        if (explanation != null) {
-          regions.add(RegionInfo(RegionType.fix, offset, replacement.length,
-              lineNumber, explanation, details,
-              edits: edits));
-        }
         offset += replacement.length;
       }
     }
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_information.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_information.dart
index bcc2979..fe1c5da 100644
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_information.dart
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_information.dart
@@ -23,11 +23,6 @@
   /// A map associating [NodeInformation] with [NullabilityNodeInfo] objects.
   Map<NullabilityNodeInfo, NodeInformation> nodeInformation = {};
 
-  /// A list of the steps in the propagation of nullability information through
-  /// the nullability graph, to report details of the step that was performed
-  /// and why it was performed.
-  final List<PropagationInfo> propagationSteps = [];
-
   /// The instrumentation information that is specific to a single source.
   final Map<Source, SourceInformation> sourceInformation = {};
 
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_listener.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_listener.dart
index 22fd567..8bdc0b8 100644
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_listener.dart
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_listener.dart
@@ -81,12 +81,6 @@
     for (var source in data.sourceInformation.keys) {
       _sourceInfo(source).changes = null;
     }
-    data.propagationSteps.clear();
-  }
-
-  @override
-  void propagationStep(PropagationInfo info) {
-    data.propagationSteps.add(info);
   }
 
   String _filePathForSource(Source source) {
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_renderer.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_renderer.dart
index 75d7725..5386501 100644
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_renderer.dart
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/instrumentation_renderer.dart
@@ -2,11 +2,10 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:analysis_server/src/edit/nnbd_migration/dart_page_script.dart';
-import 'package:analysis_server/src/edit/nnbd_migration/dart_page_style.dart';
 import 'package:analysis_server/src/edit/nnbd_migration/migration_info.dart';
 import 'package:analysis_server/src/edit/nnbd_migration/path_mapper.dart';
-import 'package:analysis_server/src/edit/nnbd_migration/unit_link.dart';
+import 'package:analysis_server/src/edit/nnbd_migration/resources/resources.g.dart'
+    as resources;
 import 'package:mustache/mustache.dart' as mustache;
 import 'package:path/path.dart' as path;
 
@@ -30,7 +29,7 @@
       <div class="nav-inner">
         <p class="panel-heading">Navigation</p>
         <p class="root">{{{ root }}}</p>
-{{{ links }}}
+        <div class="nav-tree"></div>
       </div><!-- /nav-inner -->
     </div><!-- /nav -->
     '''
@@ -92,62 +91,12 @@
   String render() {
     Map<String, dynamic> mustacheContext = {
       'root': migrationInfo.includedRoot,
-      'dartPageScript': dartPageScript,
-      'dartPageStyle': dartPageStyle,
-      'links': _renderNavigation(),
+      'dartPageScript': resources.migration_js,
+      'dartPageStyle': resources.migration_css,
       'highlightJsPath': migrationInfo.highlightJsPath,
       'highlightStylePath': migrationInfo.highlightStylePath,
       'generationDate': migrationInfo.migrationDate,
     };
     return _template.renderString(mustacheContext);
   }
-
-  /// Renders the navigation link tree.
-  String _renderNavigation() {
-    var linkData = migrationInfo.unitLinks();
-    var buffer = StringBuffer();
-    _renderNavigationSubtree(linkData, 0, buffer);
-    return buffer.toString();
-  }
-
-  /// Renders the navigation link subtree at [depth].
-  void _renderNavigationSubtree(
-      List<UnitLink> links, int depth, StringBuffer buffer) {
-    var linksGroupedByDirectory = _groupBy(
-        links.where((link) => link.depth > depth),
-        (UnitLink link) => link.pathParts[depth]);
-    // Each subtree is indented four spaces more than its parent: two for the
-    // parent <ul> and two for the parent <li>.
-    var indent = '    ' * depth;
-    buffer.writeln('$indent<ul>');
-    linksGroupedByDirectory
-        .forEach((String directoryName, Iterable<UnitLink> groupedLinks) {
-      buffer.write('$indent  <li class="dir">');
-      buffer.writeln(
-          '<span class="arrow">&#x25BC;</span>&#x1F4C1;$directoryName');
-      _renderNavigationSubtree(groupedLinks, depth + 1, buffer);
-      buffer.writeln('$indent  </li>');
-    });
-    for (var link in links.where((link) => link.depth == depth)) {
-      var modifications =
-          link.modificationCount == 1 ? 'modification' : 'modifications';
-      buffer.writeln('$indent  <li>'
-          '&#x1F4C4;<a href="${link.url}" class="nav-link" data-name="${link.relativePath}">'
-          '${link.fileName}</a> (${link.modificationCount} $modifications)'
-          '</li>');
-    }
-    buffer.writeln('$indent</ul>');
-  }
-}
-
-/// Groups the items in [iterable] by the result of applying [groupFn] to each
-/// item.
-Map<K, List<T>> _groupBy<K, T>(
-    Iterable<T> iterable, K Function(T item) groupFn) {
-  var result = <K, List<T>>{};
-  for (var item in iterable) {
-    var key = groupFn(item);
-    result.putIfAbsent(key, () => <T>[]).add(item);
-  }
-  return result;
 }
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/migration_info.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/migration_info.dart
index 1007031..528e6bd 100644
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/migration_info.dart
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/migration_info.dart
@@ -52,11 +52,11 @@
   MigrationInfo(this.units, this.unitMap, this.pathContext, this.includedRoot)
       : migrationDate = DateTime.now().toString();
 
-  /// The path to the highlight.js script, relative to [unitInfo].
-  String get highlightJsPath => PreviewSite.highlightJSPagePath;
+  /// The path to the highlight.pack.js script, relative to [unitInfo].
+  String get highlightJsPath => PreviewSite.highlightJsPath;
 
-  /// The path to the highlight.js stylesheet, relative to [unitInfo].
-  String get highlightStylePath => PreviewSite.highlightCssPagePath;
+  /// The path to the highlight.pack.js stylesheet, relative to [unitInfo].
+  String get highlightStylePath => PreviewSite.highlightCssPath;
 
   /// Return the path to [unit] from [includedRoot], to be used as a display
   /// name for a library.
@@ -68,8 +68,8 @@
     List<UnitLink> links = [];
     for (UnitInfo unit in units) {
       int count = unit.fixRegions.length;
-      links.add(
-          UnitLink(_pathTo(target: unit), computeName(unit).split('/'), count));
+      links.add(UnitLink(
+          _pathTo(target: unit), path.split(computeName(unit)), count));
     }
     return links;
   }
@@ -174,14 +174,15 @@
 
 /// Different types of regions that are called out.
 enum RegionType {
-  // TODO(brianwilkerson) 'fix' indicates whether the code was modified, while
-  //  'nonNullableType' indicates why the code wasn't modified. It would be good
-  //  to be consistent between the "whether" and "why" descriptions.
-  /// This is a region of code that was fixed (changed) in migration.
-  fix,
+  /// This is a region of code that was added in migration.
+  add,
 
-  /// This is a type that was declared non-nullable in migration.
-  nonNullableType,
+  /// This is a region of code that was removed in migration.
+  remove,
+
+  /// This is a region of code that was unchanged in migration; likely a type
+  /// that was declared non-nullable in migration.
+  unchanged,
 }
 
 /// The migration information associated with a single compilation unit.
@@ -212,13 +213,13 @@
   UnitInfo(this.path);
 
   /// Returns the [regions] that represent a fixed (changed) region of code.
-  List<RegionInfo> get fixRegions =>
-      List.of(regions.where((region) => region.regionType == RegionType.fix));
+  List<RegionInfo> get fixRegions => List.of(
+      regions.where((region) => region.regionType != RegionType.unchanged));
 
   /// Returns the [regions] that represent an unchanged type which was
   /// determined to be non-null.
-  List<RegionInfo> get nonNullableTypeRegions => List.of(regions
-      .where((region) => region.regionType == RegionType.nonNullableType));
+  List<RegionInfo> get nonNullableTypeRegions => List.of(
+      regions.where((region) => region.regionType == RegionType.unchanged));
 
   /// Returns the [RegionInfo] at offset [offset].
   // TODO(srawlins): This is O(n), used each time the user clicks on a region.
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/navigation_tree_renderer.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/navigation_tree_renderer.dart
new file mode 100644
index 0000000..8b3464b
--- /dev/null
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/navigation_tree_renderer.dart
@@ -0,0 +1,68 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:convert' show jsonEncode;
+
+import 'package:analysis_server/src/edit/nnbd_migration/migration_info.dart';
+import 'package:analysis_server/src/edit/nnbd_migration/path_mapper.dart';
+import 'package:analysis_server/src/edit/nnbd_migration/unit_link.dart';
+import 'package:path/path.dart' as path;
+
+/// The HTML that is displayed for a region of code.
+class NavigationTreeRenderer {
+  final MigrationInfo migrationInfo;
+
+  /// An object used to map the file paths of analyzed files to the file paths
+  /// of the HTML files used to view the content of those files.
+  final PathMapper pathMapper;
+
+  /// Initializes a newly created region page within the given [site]. The
+  /// [unitInfo] provides the information needed to render the page.
+  NavigationTreeRenderer(this.migrationInfo, this.pathMapper);
+
+  /// Returns the path context used to manipulate paths.
+  path.Context get pathContext => migrationInfo.pathContext;
+
+  /// Renders the navigation link tree.
+  String render() {
+    var linkData = migrationInfo.unitLinks();
+    var tree = _renderNavigationSubtree(linkData, 0);
+    return jsonEncode(tree);
+  }
+
+  /// Renders the navigation link subtree at [depth].
+  List<Object> _renderNavigationSubtree(List<UnitLink> links, int depth) {
+    var linksGroupedByDirectory = _groupBy(
+        links.where((link) => link.depth > depth),
+        (UnitLink link) => link.pathParts[depth]);
+    return [
+      for (var entry in linksGroupedByDirectory.entries)
+        {
+          'type': 'directory',
+          'name': entry.key,
+          'subtree': _renderNavigationSubtree(entry.value, depth + 1),
+        },
+      for (var link in links.where((link) => link.depth == depth))
+        {
+          'type': 'file',
+          'name': link.fileName,
+          'path': link.relativePath,
+          'href': link.url,
+          'editCount': link.editCount,
+        },
+    ];
+  }
+}
+
+/// Groups the items in [iterable] by the result of applying [groupFn] to each
+/// item.
+Map<K, List<T>> _groupBy<K, T>(
+    Iterable<T> iterable, K Function(T item) groupFn) {
+  var result = <K, List<T>>{};
+  for (var item in iterable) {
+    var key = groupFn(item);
+    result.putIfAbsent(key, () => <T>[]).add(item);
+  }
+  return result;
+}
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/highlight.css b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/highlight.css
new file mode 100644
index 0000000..bc8e473
--- /dev/null
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/highlight.css
@@ -0,0 +1,66 @@
+/*
+Date: 24 Fev 2015
+Author: Pedro Oliveira <kanytu@gmail . com>
+*/
+
+.hljs {
+  color: #a9b7c6;
+  background: #282b2e;
+  display: block;
+  overflow-x: auto;
+  padding: 0.5em;
+}
+
+.hljs-number,
+.hljs-literal,
+.hljs-symbol,
+.hljs-bullet {
+  color: #6897BB;
+}
+
+.hljs-keyword,
+.hljs-selector-tag,
+.hljs-deletion {
+  color: #cc7832;
+}
+
+.hljs-variable,
+.hljs-template-variable,
+.hljs-link {
+  color: #629755;
+}
+
+.hljs-comment,
+.hljs-quote {
+  color: #808080;
+}
+
+.hljs-meta {
+  color: #bbb529;
+}
+
+.hljs-string,
+.hljs-attribute,
+.hljs-addition {
+  color: #6A8759;
+}
+
+.hljs-section,
+.hljs-title,
+.hljs-type {
+  color: #ffc66d;
+}
+
+.hljs-name,
+.hljs-selector-id,
+.hljs-selector-class {
+  color: #e8bf6a;
+}
+
+.hljs-emphasis {
+  font-style: italic;
+}
+
+.hljs-strong {
+  font-weight: bold;
+}
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/highlight.md b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/highlight.md
new file mode 100644
index 0000000..d23468a
--- /dev/null
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/highlight.md
@@ -0,0 +1,6 @@
+1. Build and download highlight.zip for Dart. [1]
+2. Extract highlight.zip
+3. find highlight.pack.js and copy into this directory
+4. find styles/androidstudio.css and copy into the directory as highlight.css
+
+[1] https://highlightjs.org/download/
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/highlight.pack.js b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/highlight.pack.js
new file mode 100644
index 0000000..dbe773f
--- /dev/null
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/highlight.pack.js
@@ -0,0 +1,2 @@
+/*! highlight.js v9.15.10 | BSD3 License | git.io/hljslicense */
+!function(e){var n="object"==typeof window&&window||"object"==typeof self&&self;"undefined"==typeof exports||exports.nodeType?n&&(n.hljs=e({}),"function"==typeof define&&define.amd&&define([],function(){return n.hljs})):e(exports)}(function(a){var f=[],u=Object.keys,N={},c={},n=/^(no-?highlight|plain|text)$/i,s=/\blang(?:uage)?-([\w-]+)\b/i,t=/((^(<[^>]+>|\t|)+|(?:\n)))/gm,r={case_insensitive:"cI",lexemes:"l",contains:"c",keywords:"k",subLanguage:"sL",className:"cN",begin:"b",beginKeywords:"bK",end:"e",endsWithParent:"eW",illegal:"i",excludeBegin:"eB",excludeEnd:"eE",returnBegin:"rB",returnEnd:"rE",relevance:"r",variants:"v",IDENT_RE:"IR",UNDERSCORE_IDENT_RE:"UIR",NUMBER_RE:"NR",C_NUMBER_RE:"CNR",BINARY_NUMBER_RE:"BNR",RE_STARTERS_RE:"RSR",BACKSLASH_ESCAPE:"BE",APOS_STRING_MODE:"ASM",QUOTE_STRING_MODE:"QSM",PHRASAL_WORDS_MODE:"PWM",C_LINE_COMMENT_MODE:"CLCM",C_BLOCK_COMMENT_MODE:"CBCM",HASH_COMMENT_MODE:"HCM",NUMBER_MODE:"NM",C_NUMBER_MODE:"CNM",BINARY_NUMBER_MODE:"BNM",CSS_NUMBER_MODE:"CSSNM",REGEXP_MODE:"RM",TITLE_MODE:"TM",UNDERSCORE_TITLE_MODE:"UTM",COMMENT:"C",beginRe:"bR",endRe:"eR",illegalRe:"iR",lexemesRe:"lR",terminators:"t",terminator_end:"tE"},b="</span>",h={classPrefix:"hljs-",tabReplace:null,useBR:!1,languages:void 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diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/dart_page_style.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/migration.css
similarity index 85%
rename from pkg/analysis_server/lib/src/edit/nnbd_migration/dart_page_style.dart
rename to pkg/analysis_server/lib/src/edit/nnbd_migration/resources/migration.css
index c9feedb..3963f24 100644
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/dart_page_style.dart
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/migration.css
@@ -1,8 +1,7 @@
-// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
+/* Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file  */
+/* for details. All rights reserved. Use of this source code is governed by a */
+/* BSD-style license that can be found in the LICENSE file.                   */
 
-const dartPageStyle = r'''
 body {
   background-color: black;
   color: white;
@@ -82,6 +81,7 @@
 
 .nav-inner li:not(.dir) {
   margin-left: 20px;
+  margin-bottom: 3px;
 }
 
 .nav-inner li.dir .arrow {
@@ -117,6 +117,19 @@
   text-decoration: none;
 }
 
+.edit-count {
+  background-color: #cccc00;
+  border-radius: 15px;
+  color: #000000;
+  display: inline-block;
+  font-size: 11px;
+  font-weight: 600;
+  margin-left: 5px;
+  min-width: 25px;
+  padding: 5px 0;
+  text-align: center;
+}
+
 .content {
   flex: 0 1 auto;
   font-family: monospace;
@@ -193,7 +206,7 @@
 }
 
 .regions tr.highlight td:last-child {
-  background-color: rgba(0, 0, 128, 0.5);
+  background-color: #444444;
 }
 
 .regions td.line-no {
@@ -207,7 +220,7 @@
 }
 
 .regions tr.highlight td.line-no {
-  border-right: solid #0000ff 2px;
+  border-right: solid #cccccc 2px;
 }
 
 .region {
@@ -217,13 +230,17 @@
   z-index: 200;
 }
 
-.region.fix-region {
-  /* Green means this region was added. */
+.region.added-region {
   background-color: #ccffcc;
   color: #003300;
 }
 
-.region.non-nullable-type-region {
+.region.removed-region {
+  background-color: #ff6666;
+  color: #001100;
+}
+
+.region.unchanged-region {
   background-color: rgba(0, 0, 0, 0.3);
   border-bottom: solid 2px #cccccc;
   /* Invisible text; use underlying highlighting. */
@@ -232,14 +249,6 @@
   line-height: 1;
 }
 
-/**
-  * TODO(srawlins): Stop shipping tooltips as hidden DOM. Instead, request them
-  * on each click.
-  */
-.region .tooltip {
-  display: none;
-}
-
 .target {
   background-color: #FFFF99;
   color: black;
@@ -297,7 +306,10 @@
   text-indent: -21px;
 }
 
+.edit-list .edit-link {
+  cursor: pointer;
+}
+
 .footer {
   padding: 8px 8px 100px 8px;
 }
-''';
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/dart_page_script.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/migration.js
similarity index 60%
rename from pkg/analysis_server/lib/src/edit/nnbd_migration/dart_page_script.dart
rename to pkg/analysis_server/lib/src/edit/nnbd_migration/resources/migration.js
index f123079..a2c3c85 100644
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/dart_page_script.dart
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/migration.js
@@ -2,7 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-const dartPageScript = r'''
 function getOffset(location) {
   const root = document.querySelector(".root").textContent;
   return new URL(location, "file://" + root + "/dummy.txt")
@@ -16,13 +15,19 @@
 }
 
 // Remove highlighting from [offset].
-function removeHighlight(offset) {
+function removeHighlight(offset, lineNumber) {
   if (offset != null) {
     const anchor = document.getElementById("o" + offset);
     if (anchor != null) {
       anchor.classList.remove("target");
     }
   }
+  if (lineNumber != null) {
+    const line = document.querySelector(".line-" + lineNumber);
+    if (line != null) {
+      line.parentNode.classList.remove("highlight");
+    }
+  }
 }
 
 // Return the absolute path of [path], assuming [path] is relative to [root].
@@ -46,14 +51,54 @@
   }
 }
 
+// Write the contents of the Edit List, from JSON data [editListData].
+function writeEditList(editListData) {
+  const editList = document.querySelector(".edit-list .panel-content");
+  editList.innerHTML = "";
+  const p = editList.appendChild(document.createElement("p"));
+  const countElement = p.appendChild(document.createElement("strong"));
+  const editCount = editListData["editCount"];
+  countElement.appendChild(document.createTextNode(editCount));
+  if (editCount == 1) {
+    p.appendChild(document.createTextNode(
+        " edit was made to this file. Click the edit's checkbox to toggle " +
+        "its reviewed state."));
+  } else {
+    p.appendChild(document.createTextNode(
+        " edits were made to this file. Click an edit's checkbox to toggle " +
+        "its reviewed state."));
+  }
+  for (const edit of editListData["edits"]) {
+    const editP = editList.appendChild(document.createElement("p"));
+    editP.classList.add("edit");
+    const checkbox = editP.appendChild(document.createElement("input"));
+    checkbox.setAttribute("type", "checkbox");
+    checkbox.setAttribute("title", "Click to mark reviewed");
+    checkbox.setAttribute("disabled", "disabled");
+    editP.appendChild(document.createTextNode(
+        `line ${edit["line"]}: ${edit["explanation"]}. `));
+    const a = editP.appendChild(document.createElement("a"));
+    a.classList.add("edit-link");
+    const offset = edit["offset"];
+    a.dataset.offset = offset;
+    const line = edit["line"];
+    a.dataset.line = line;
+    a.appendChild(document.createTextNode("[view]"));
+    a.onclick = (event) => {
+      navigate(window.location.pathname, offset, line,
+          () => { pushState(window.location.pathname, offset, line) });
+      loadRegionExplanation(a);
+    };
+  }
+}
+
 // Load data from [data] into the .code and the .regions divs.
 function writeCodeAndRegions(data) {
   const regions = document.querySelector(".regions");
   const code = document.querySelector(".code");
-  const editList = document.querySelector(".edit-list .panel-content");
   regions.innerHTML = data["regions"];
   code.innerHTML = data["navContent"];
-  editList.innerHTML = data["editList"];
+  writeEditList(data["editList"]);
   highlightAllCode();
   addClickHandlers(".code");
   addClickHandlers(".regions");
@@ -64,46 +109,60 @@
 // If [callback] is present, it will be called after the server response has
 // been processed, and the content has been updated on the page.
 function navigate(path, offset, lineNumber, callback) {
-  removeHighlight(offset);
+  const currentOffset = getOffset(window.location.href);
+  const currentLineNumber = getLine(window.location.href);
+  removeHighlight(currentOffset, currentLineNumber);
   if (path == window.location.pathname) {
     // Navigating to same file; just scroll into view.
-    maybeScrollIntoView(offset, lineNumber);
+    maybeScrollToAndHighlight(offset, lineNumber);
+    if (callback !== undefined) {
+      callback();
+    }
   } else {
     loadFile(path, offset, lineNumber, callback);
   }
 }
 
+function maybeScrollIntoView(element) {
+  const rect = element.getBoundingClientRect();
+  // TODO(srawlins): Only scroll smoothly when on the same page.
+  if (rect.bottom > window.innerHeight) {
+    element.scrollIntoView({behavior: "smooth", block: "end"});
+  }
+  if (rect.top < 0) {
+    element.scrollIntoView({behavior: "smooth"});
+  }
+}
+
 // Scroll target with id [offset] into view if it is not currently in view.
 //
 // If [offset] is null, instead scroll the "unit-name" header, at the top of the
 // page, into view.
 //
-// Also add the "target" class, highlighting the target.
-function maybeScrollIntoView(offset, lineNumber) {
+// Also add the "target" class, highlighting the target. Also add the
+// "highlight" class to the entire line on which the target lies.
+function maybeScrollToAndHighlight(offset, lineNumber) {
   var target;
+  var line;
   if (offset !== null) {
     target = document.getElementById("o" + offset);
+    line = document.querySelector(".line-" + lineNumber);
+    if (target !== null) {
+      maybeScrollIntoView(target);
+      target.classList.add("target");
+    } else if (line != null) {
+      // If the target doesn't exist, but the line does, scroll that into view
+      // instead.
+      maybeScrollIntoView(line);
+    }
+    if (line != null) {
+      line.parentNode.classList.add("highlight");
+    }
   } else {
     // If no offset is given, this is likely a navigation link, and we need to
     // scroll back to the top of the page.
     target = document.getElementById("unit-name");
-  }
-  if (target != null) {
-    const rect = target.getBoundingClientRect();
-    // TODO(srawlins): Only scroll smoothly when on the same page.
-    if (rect.bottom > window.innerHeight) {
-      target.scrollIntoView({behavior: "smooth", block: "end"});
-    }
-    if (rect.top < 0) {
-      target.scrollIntoView({behavior: "smooth"});
-    }
-    if (target !== document.getElementById("unit-name")) {
-      target.classList.add("target");
-      if (lineNumber != null) {
-        const line = document.querySelector(".line-" + lineNumber);
-        line.parentNode.classList.add("highlight");
-      }
-    }
+    maybeScrollIntoView(target);
   }
 }
 
@@ -118,7 +177,7 @@
     if (xhr.status === 200) {
       const response = JSON.parse(xhr.responseText);
       writeCodeAndRegions(response);
-      maybeScrollIntoView(offset, lineNumber);
+      maybeScrollToAndHighlight(offset, lineNumber);
       updatePage(path, offset);
       if (callback !== undefined) {
         callback();
@@ -169,71 +228,135 @@
   });
 }
 
+function addArrowClickHandler(arrow) {
+  const childList = arrow.parentNode.querySelector(":scope > ul");
+  // Animating height from "auto" to "0" is not supported by CSS [1], so all we
+  // have are hacks. The `* 2` allows for events in which the list grows in
+  // height when resized, with additional text wrapping.
+  // [1] https://css-tricks.com/using-css-transitions-auto-dimensions/
+  childList.style.maxHeight = childList.offsetHeight * 2 + "px";
+  arrow.onclick = (event) => {
+    if (!childList.classList.contains("collapsed")) {
+      childList.classList.add("collapsed");
+      arrow.classList.add("collapsed");
+    } else {
+      childList.classList.remove("collapsed");
+      arrow.classList.remove("collapsed");
+    }
+  };
+}
+
+function handleNavLinkClick(event) {
+  const path = absolutePath(event.currentTarget.getAttribute("href"));
+  const offset = getOffset(event.currentTarget.getAttribute("href"));
+  const lineNumber = getLine(event.currentTarget.getAttribute("href"));
+  if (offset !== null) {
+    navigate(path, offset, lineNumber,
+        () => { pushState(path, offset, lineNumber) });
+  } else {
+    navigate(path, null, null, () => { pushState(path, null, null) });
+  }
+  event.preventDefault();
+}
+
+function handlePostLinkClick(event) {
+  // Directing the server to produce an edit; request it, then do work with
+  // the response.
+  const path = absolutePath(event.currentTarget.getAttribute("href"));
+  const xhr = new XMLHttpRequest();
+  xhr.open("POST", path);
+  xhr.setRequestHeader("Content-Type", "application/json");
+  xhr.onload = function() {
+    if (xhr.status === 200) {
+      // Likely request new navigation and file content.
+    } else {
+      alert("Request failed; status of " + xhr.status);
+    }
+  };
+  xhr.onerror = function(e) {
+    alert(`Could not load ${path}; preview server might be disconnected.`);
+  };
+  xhr.send();
+}
+
 function addClickHandlers(parentSelector) {
   const parentElement = document.querySelector(parentSelector);
+
   const navLinks = parentElement.querySelectorAll(".nav-link");
   navLinks.forEach((link) => {
-    link.onclick = (event) => {
-      const path = absolutePath(event.currentTarget.getAttribute("href"));
-      const offset = getOffset(event.currentTarget.getAttribute("href"));
-      const lineNumber = getLine(event.currentTarget.getAttribute("href"));
-      if (offset !== null) {
-        navigate(path, offset, lineNumber,
-            () => { pushState(path, offset, lineNumber) });
-      } else {
-        navigate(path, null, null, () => { pushState(path, null, null) });
-      }
-      event.preventDefault();
-    };
+    link.onclick = handleNavLinkClick;
   });
+
   const regions = parentElement.querySelectorAll(".region");
   regions.forEach((region) => {
     region.onclick = (event) => {
       loadRegionExplanation(region);
     };
   });
-  const navArrows = parentElement.querySelectorAll(".arrow");
-  navArrows.forEach((arrow) => {
-    const childList = arrow.parentNode.querySelector(":scope > ul");
-    // Animating height from "auto" to "0" is not supported by CSS [1], so all
-    // we have are hacks. The `* 2` allows for events in which the list grows in
-    // height when resized, with additional text wrapping.
-    // [1] https://css-tricks.com/using-css-transitions-auto-dimensions/
-    childList.style.maxHeight = childList.offsetHeight * 2 + "px";
-    arrow.onclick = (event) => {
-      if (!childList.classList.contains("collapsed")) {
-        childList.classList.add("collapsed");
-        arrow.classList.add("collapsed");
-      } else {
-        childList.classList.remove("collapsed");
-        arrow.classList.remove("collapsed");
-      }
-    };
-  });
+
   const postLinks = parentElement.querySelectorAll(".post-link");
   postLinks.forEach((link) => {
-    link.onclick = (event) => {
-      // Directing the server to produce an edit; request it, then do work with
-      // the response.
-      const path = absolutePath(event.currentTarget.getAttribute("href"));
-      const xhr = new XMLHttpRequest();
-      xhr.open("POST", path);
-      xhr.setRequestHeader("Content-Type", "application/json");
-      xhr.onload = function() {
-        if (xhr.status === 200) {
-          // Likely request new navigation and file content.
-        } else {
-          alert("Request failed; status of " + xhr.status);
-        }
-      };
-      xhr.onerror = function(e) {
-        alert(`Could not load ${path}; preview server might be disconnected.`);
-      };
-      xhr.send();
-    };
+    link.onclick = handlePostLinkClick;
   });
 }
 
+function writeNavigationSubtree(parentElement, tree) {
+  const ul = parentElement.appendChild(document.createElement('ul'));
+  for (const entity of tree) {
+    const li = ul.appendChild(document.createElement('li'));
+    if (entity["type"] == "directory") {
+      li.classList.add("dir");
+      const arrow = li.appendChild(document.createElement('span'));
+      arrow.classList.add("arrow");
+      arrow.innerHTML = "&#x25BC;";
+      const icon = li.appendChild(document.createElement('span'));
+      icon.innerHTML = "&#x1F4C1;";
+      li.appendChild(document.createTextNode(entity["name"]));
+      writeNavigationSubtree(li, entity["subtree"]);
+      addArrowClickHandler(arrow);
+    } else {
+      li.innerHTML = "&#x1F4C4;";
+      const a = li.appendChild(document.createElement("a"));
+      a.classList.add("nav-link");
+      a.dataset.name = entity["path"];
+      a.setAttribute("href", entity["href"]);
+      a.appendChild(document.createTextNode(entity["name"]));
+      a.onclick = handleNavLinkClick;
+      const editCount = entity["editCount"];
+      if (editCount > 0) {
+        const editsBadge = li.appendChild(document.createElement("span"));
+        editsBadge.classList.add("edit-count");
+        const edits = editCount == 1 ? 'edit' : 'edits';
+        editsBadge.setAttribute("title", `${editCount} ${edits}`);
+        editsBadge.appendChild(document.createTextNode(editCount));
+      }
+    }
+  }
+}
+
+// Load the navigation tree into the ".nav-tree" div.
+function loadNavigationTree(region) {
+  // Request the navigation tree, then do work with the response.
+  const xhr = new XMLHttpRequest();
+  const path = "/_preview/navigationTree.json";
+  xhr.open("GET", path);
+  xhr.setRequestHeader("Content-Type", "application/json");
+  xhr.onload = function() {
+    if (xhr.status === 200) {
+      const response = JSON.parse(xhr.responseText);
+      const navTree = document.querySelector(".nav-tree");
+      navTree.innerHTML = "";
+      writeNavigationSubtree(navTree, response);
+    } else {
+      alert(`Request failed; status of ${xhr.status}`);
+    }
+  };
+  xhr.onerror = function(e) {
+    alert(`Could not load ${path}; preview server might be disconnected.`);
+  };
+  xhr.send();
+}
+
 function writeRegionExplanation(response) {
   const editPanel = document.querySelector(".edit-panel .panel-content");
   editPanel.innerHTML = "";
@@ -267,7 +390,7 @@
         const a = detailItem.appendChild(document.createElement("a"));
         a.appendChild(document.createTextNode(detail["link"]["text"]));
         a.setAttribute("href", detail["link"]["href"]);
-        a.classList.add("post-link");
+        a.classList.add("nav-link");
         detailItem.appendChild(document.createTextNode(")"));
       }
     }
@@ -339,13 +462,13 @@
   const offset = getOffset(window.location.href);
   const lineNumber = getLine(window.location.href);
   const root = document.querySelector(".root").textContent;
+  loadNavigationTree();
   if (path !== "/" && path !== root) {
     // TODO(srawlins): replaceState?
     loadFile(path, offset, lineNumber,
         () => { pushState(path, offset, lineNumber) });
   }
   resizePanels();
-  addClickHandlers(".nav-panel");
 });
 
 window.addEventListener("popstate", (event) => {
@@ -401,4 +524,3 @@
   }
   debounce(resizePanels, 200)();
 });
-''';
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/resources.g.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/resources.g.dart
new file mode 100644
index 0000000..86112bf
--- /dev/null
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/resources/resources.g.dart
@@ -0,0 +1,675 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// This file is generated; don't edit it directly.
+//
+// See pkg/analysis_server/tool/nnbd_migration/generate_resources.dart for how
+// to edit the source content and for re-generation instructions.
+
+import 'dart:convert' as convert;
+
+String get highlight_css {
+  return _highlight_css ??= _decode(_highlight_css_base64);
+}
+
+String get highlight_pack_js {
+  return _highlight_pack_js ??= _decode(_highlight_pack_js_base64);
+}
+
+String get migration_js {
+  return _migration_js ??= _decode(_migration_js_base64);
+}
+
+String get migration_css {
+  return _migration_css ??= _decode(_migration_css_base64);
+}
+
+String _decode(String data) {
+  data = data.replaceAll('\n', '').trim();
+  return String.fromCharCodes(convert.base64Decode(data));
+}
+
+String _highlight_css;
+String _highlight_css_base64 = '''
+LyoKRGF0ZTogMjQgRmV2IDIwMTUKQXV0aG9yOiBQZWRybyBPbGl2ZWlyYSA8a2FueXR1QGdtYWlsIC4g
+Y29tPgoqLwoKLmhsanMgewogIGNvbG9yOiAjYTliN2M2OwogIGJhY2tncm91bmQ6ICMyODJiMmU7CiAg
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+eWxlOiBpdGFsaWM7Cn0KCi5obGpzLXN0cm9uZyB7CiAgZm9udC13ZWlnaHQ6IGJvbGQ7Cn0K
+''';
+
+String _highlight_pack_js;
+String _highlight_pack_js_base64 = '''
+LyohIGhpZ2hsaWdodC5qcyB2OS4xNS4xMCB8IEJTRDMgTGljZW5zZSB8IGdpdC5pby9obGpzbGljZW5z
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+''';
+
+String _migration_js;
+String _migration_js_base64 = '''
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+''';
+
+String _migration_css;
+String _migration_css_base64 = '''
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+YXk6IGlubGluZS1ibG9jazsKICBwb3NpdGlvbjogcmVsYXRpdmU7CiAgdmlzaWJpbGl0eTogdmlzaWJs
+ZTsKICB6LWluZGV4OiAyMDA7Cn0KCi5yZWdpb24uYWRkZWQtcmVnaW9uIHsKICBiYWNrZ3JvdW5kLWNv
+bG9yOiAjY2NmZmNjOwogIGNvbG9yOiAjMDAzMzAwOwp9CgoucmVnaW9uLnJlbW92ZWQtcmVnaW9uIHsK
+ICBiYWNrZ3JvdW5kLWNvbG9yOiAjZmY2NjY2OwogIGNvbG9yOiAjMDAxMTAwOwp9CgoucmVnaW9uLnVu
+Y2hhbmdlZC1yZWdpb24gewogIGJhY2tncm91bmQtY29sb3I6IHJnYmEoMCwgMCwgMCwgMC4zKTsKICBi
+b3JkZXItYm90dG9tOiBzb2xpZCAycHggI2NjY2NjYzsKICAvKiBJbnZpc2libGUgdGV4dDsgdXNlIHVu
+ZGVybHlpbmcgaGlnaGxpZ2h0aW5nLiAqLwogIGNvbG9yOiByZ2JhKDAsIDAsIDAsIDApOwogIC8qIFJl
+ZHVjZSBsaW5lIGhlaWdodCB0byBtYWtlIHJvb20gZm9yIGJvcmRlci4gKi8KICBsaW5lLWhlaWdodDog
+MTsKfQoKLnRhcmdldCB7CiAgYmFja2dyb3VuZC1jb2xvcjogI0ZGRkY5OTsKICBjb2xvcjogYmxhY2s7
+CiAgcG9zaXRpb246IHJlbGF0aXZlOwogIHZpc2liaWxpdHk6IHZpc2libGU7Cn0KCi5pbmZvLXBhbmVs
+IHsKICBmbGV4OiAxIDEgMjcwcHg7CiAgZm9udC1zaXplOiAxNHB4OwogIG1hcmdpbjogMTBweCAwOwp9
+CgouaW5mby1wYW5lbCAuZWRpdC1wYW5lbCB7CiAgYmFja2dyb3VuZC1jb2xvcjogIzI4MmIyZTsKICBv
+dmVyZmxvdzogYXV0bzsKfQoKLmluZm8tcGFuZWwgLnBhbmVsLWNvbnRlbnQgewogIGZvbnQtc2l6ZTog
+MTNweDsKICBwYWRkaW5nOiA3cHg7Cn0KCi5pbmZvLXBhbmVsIC5wYW5lbC1jb250ZW50ID4gOmZpcnN0
+LWNoaWxkIHsKICBtYXJnaW4tdG9wOiAwOwp9CgouaW5mby1wYW5lbCAucmVnaW9uLWxvY2F0aW9uIHsK
+ICBwYWRkaW5nLWxlZnQ6IDEycHg7CiAgdGV4dC1pbmRlbnQ6IC0xMnB4Owp9CgouaW5mby1wYW5lbCAu
+bm93cmFwIHsKICB3aGl0ZS1zcGFjZTogbm93cmFwOwp9CgouaW5mby1wYW5lbCB1bCwKLmluZm8tcGFu
+ZWwgb2wgewogIHBhZGRpbmctbGVmdDogMjBweDsKfQoKLmluZm8tcGFuZWwgYSB7CiAgY29sb3I6ICMz
+M2NjZmY7Cn0KCi5pbmZvLXBhbmVsIC5lZGl0LWxpc3QgewogIGJhY2tncm91bmQtY29sb3I6ICMyODJi
+MmU7CiAgbWFyZ2luLXRvcDogMTJweDsKICBvdmVyZmxvdzogYXV0bzsKfQoKLmVkaXQtbGlzdCAuZWRp
+dCB7CiAgbWFyZ2luOiAzcHggMDsKICBwYWRkaW5nLWxlZnQ6IDIxcHg7CiAgdGV4dC1pbmRlbnQ6IC0y
+MXB4Owp9CgouZWRpdC1saXN0IC5lZGl0LWxpbmsgewogIGN1cnNvcjogcG9pbnRlcjsKfQoKLmZvb3Rl
+ciB7CiAgcGFkZGluZzogOHB4IDhweCAxMDBweCA4cHg7Cn0K
+''';
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/unit_link.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/unit_link.dart
index 4a82dc2..342e125 100644
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/unit_link.dart
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/unit_link.dart
@@ -9,14 +9,14 @@
   /// The relative URL of this compilation unit on the preview server.
   final String url;
   final List<String> pathParts;
-  final int modificationCount;
+  final int editCount;
 
   /// The number of directories deep in which this compilation unit is found.
   ///
   /// A compilation unit in the root has a depth of 0.
   final int depth;
 
-  UnitLink(this.url, this.pathParts, this.modificationCount)
+  UnitLink(this.url, this.pathParts, this.editCount)
       : depth = pathParts.length - 1;
 
   String get relativePath => path.joinAll(pathParts);
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/unit_renderer.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/unit_renderer.dart
index fa26c56b..fd4e92e 100644
--- a/pkg/analysis_server/lib/src/edit/nnbd_migration/unit_renderer.dart
+++ b/pkg/analysis_server/lib/src/edit/nnbd_migration/unit_renderer.dart
@@ -34,7 +34,7 @@
   /// Return the path context used to manipulate paths.
   path.Context get pathContext => migrationInfo.pathContext;
 
-  /// Builds an HTML view of the instrumentation information in [unitInfo].
+  /// Builds a JSON view of the instrumentation information in [unitInfo].
   String render() {
     Map<String, dynamic> response = {
       'thisUnit': migrationInfo.computeName(unitInfo),
@@ -45,33 +45,23 @@
     return jsonEncode(response);
   }
 
-  String _computeEditList() {
-    var content = StringBuffer();
-    var editCount = unitInfo.fixRegions.length;
-    // TODO(srawlins): Change the edit count to be badge-like (number in a
-    //  circle).
-    if (editCount == 1) {
-      content
-          .write('<p><strong>$editCount</strong> edit was made to this file. '
-              "Click the edit's checkbox to toggle its reviewed state.</p>");
-    } else {
-      content
-          .write('<p><strong>$editCount</strong> edits were made to this file. '
-              "Click an edit's checkbox to toggle its reviewed state.</p>");
-    }
-    for (var region in unitInfo.fixRegions) {
-      content.write('<p class="edit">');
-      // TODO(srawlins): Make checkboxes functional.
-      content.write('<input type="checkbox" title="Click to mark reviewed" '
-          'disabled="disabled"> ');
-      content.write('line ${region.lineNumber}: ');
-      content.write(_htmlEscape.convert(region.explanation));
-      content.write('.</p>');
-    }
-    return content.toString();
+  /// Returns the list of edits, as JSON.
+  Map<String, Object> _computeEditList() {
+    var response = <String, Object>{
+      'editCount': unitInfo.fixRegions.length,
+      'edits': [
+        for (var region in unitInfo.fixRegions)
+          {
+            'line': region.lineNumber,
+            'explanation': region.explanation,
+            'offset': region.offset,
+          },
+      ],
+    };
+    return response;
   }
 
-  /// Return the content of the file with navigation links and anchors added.
+  /// Returns the content of the file with navigation links and anchors added.
   ///
   /// The content of the file (not including added links and anchors) will be
   /// HTML-escaped.
@@ -145,19 +135,25 @@
     return navContent2.toString();
   }
 
-  /// Return the content of regions, based on the [unitInfo] for both
+  /// Returns the content of regions, based on the [unitInfo] for both
   /// unmodified and modified regions.
+  ///
+  /// The content of the file (not including added links and anchors) will be
+  /// HTML-escaped.
   String _computeRegionContent() {
     String content = unitInfo.content;
     StringBuffer regions = StringBuffer();
     int lineNumber = 1;
 
-    void writeSplitLines(String lines) {
+    void writeSplitLines(String lines,
+        {String perLineOpeningTag = '', String perLineClosingTag = ''}) {
       Iterator<String> lineIterator = LineSplitter.split(lines).iterator;
       lineIterator.moveNext();
 
       while (true) {
+        regions.write(perLineOpeningTag);
         regions.write(_htmlEscape.convert(lineIterator.current));
+        regions.write(perLineClosingTag);
         if (lineIterator.moveNext()) {
           // If we're not on the last element, end this table row, and start a
           // new table row.
@@ -169,6 +165,26 @@
           break;
         }
       }
+      if (lines.endsWith('\n')) {
+        lineNumber++;
+        regions.write('</td></tr>'
+            '<tr><td class="line-no">$lineNumber</td>'
+            '<td class="line-$lineNumber">');
+      }
+    }
+
+    /// Returns the CSS class for a region with a given [RegionType].
+    String classForRegion(RegionType type) {
+      switch (type) {
+        case RegionType.add:
+          return 'added-region';
+        case RegionType.remove:
+          return 'removed-region';
+        case RegionType.unchanged:
+          return 'unchanged-region';
+        default:
+          return null;
+      }
     }
 
     int previousOffset = 0;
@@ -181,14 +197,11 @@
         writeSplitLines(content.substring(previousOffset, offset));
         previousOffset = offset + length;
       }
-      String regionClass = region.regionType == RegionType.fix
-          ? 'fix-region'
-          : 'non-nullable-type-region';
-      regions.write('<span class="region $regionClass" ');
-      regions.write('data-offset="$offset" data-line="$lineNumber">');
-      regions.write(
-          _htmlEscape.convert(content.substring(offset, offset + length)));
-      regions.write('</span>');
+      String regionClass = classForRegion(region.regionType);
+      String regionSpanTag = '<span class="region $regionClass" '
+          'data-offset="$offset" data-line="$lineNumber">';
+      writeSplitLines(content.substring(offset, offset + length),
+          perLineOpeningTag: regionSpanTag, perLineClosingTag: '</span>');
     }
     if (previousOffset < content.length) {
       // Last region of unmodified content.
@@ -198,8 +211,8 @@
     return regions.toString();
   }
 
-  /// Return the URL that will navigate to the given [target] in the file at the
-  /// given [relativePath].
+  /// Returns the URL that will navigate to the given [target] in the file at
+  /// the given [relativePath].
   String _uriForRelativePath(String relativePath, NavigationTarget target) {
     var queryParams = {
       'offset': target.offset,
diff --git a/pkg/analysis_server/lib/src/edit/preview/exception_page.dart b/pkg/analysis_server/lib/src/edit/preview/exception_page.dart
index ae7c30b..1a03854 100644
--- a/pkg/analysis_server/lib/src/edit/preview/exception_page.dart
+++ b/pkg/analysis_server/lib/src/edit/preview/exception_page.dart
@@ -27,8 +27,9 @@
 <h1>500 Exception in preview</h1>
 <p>
 We're sorry, but you've encountered a bug in the preview tool. Please visit
-<a href='https://github.com/dart-lang/sdk/issues/new'></a> to report the issue
-and include the stack trace below.
+<a href='https://github.com/dart-lang/sdk/issues/new'>
+github.com/dart-lang/sdk/issues/new</a> to report the issue and include the
+stack trace below.
 </p>
 <h2>$message</h2>
 <p style="white-space: pre">
diff --git a/pkg/analysis_server/lib/src/edit/preview/highlight_css_page.dart b/pkg/analysis_server/lib/src/edit/preview/highlight_css_page.dart
index fd1570c..4cb330d 100644
--- a/pkg/analysis_server/lib/src/edit/preview/highlight_css_page.dart
+++ b/pkg/analysis_server/lib/src/edit/preview/highlight_css_page.dart
@@ -4,7 +4,8 @@
 
 import 'dart:async';
 
-import 'package:analysis_server/src/edit/nnbd_migration/highlight_css.dart';
+import 'package:analysis_server/src/edit/nnbd_migration/resources/resources.g.dart'
+    as resources;
 import 'package:analysis_server/src/edit/preview/preview_page.dart';
 import 'package:analysis_server/src/edit/preview/preview_site.dart';
 
@@ -17,7 +18,7 @@
 
   /// Initialize a newly created CSS page within the given [site].
   HighlightCssPage(PreviewSite site)
-      : super(site, PreviewSite.highlightCssPagePath.substring(1));
+      : super(site, PreviewSite.highlightCssPath.substring(1));
 
   @override
   void generateBody(Map<String, String> params) {
@@ -29,9 +30,8 @@
     buf.write(pageContent());
   }
 
-  /// Return the content of the page, decoding it if it hasn't been decoded
-  /// before.
+  /// Return the content of the page.
   String pageContent() {
-    return _pageContent ??= decodeHighlightCss();
+    return _pageContent ??= resources.highlight_css;
   }
 }
diff --git a/pkg/analysis_server/lib/src/edit/preview/highlight_js_page.dart b/pkg/analysis_server/lib/src/edit/preview/highlight_js_page.dart
index d89042c..a024eca 100644
--- a/pkg/analysis_server/lib/src/edit/preview/highlight_js_page.dart
+++ b/pkg/analysis_server/lib/src/edit/preview/highlight_js_page.dart
@@ -4,7 +4,8 @@
 
 import 'dart:async';
 
-import 'package:analysis_server/src/edit/nnbd_migration/highlight_js.dart';
+import 'package:analysis_server/src/edit/nnbd_migration/resources/resources.g.dart'
+    as resources;
 import 'package:analysis_server/src/edit/preview/preview_page.dart';
 import 'package:analysis_server/src/edit/preview/preview_site.dart';
 
@@ -17,7 +18,7 @@
 
   /// Initialize a newly created JS page within the given [site].
   HighlightJSPage(PreviewSite site)
-      : super(site, PreviewSite.highlightJSPagePath.substring(1));
+      : super(site, PreviewSite.highlightJsPath.substring(1));
 
   @override
   void generateBody(Map<String, String> params) {
@@ -29,9 +30,8 @@
     buf.write(pageContent());
   }
 
-  /// Return the content of the page, decoding it if it hasn't been decoded
-  /// before.
+  /// Return the content of the page.
   String pageContent() {
-    return _pageContent ??= decodeHighlightJs();
+    return _pageContent ??= resources.highlight_pack_js;
   }
 }
diff --git a/pkg/analysis_server/lib/src/edit/preview/navigation_tree_page.dart b/pkg/analysis_server/lib/src/edit/preview/navigation_tree_page.dart
new file mode 100644
index 0000000..e4c025f
--- /dev/null
+++ b/pkg/analysis_server/lib/src/edit/preview/navigation_tree_page.dart
@@ -0,0 +1,27 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analysis_server/src/edit/nnbd_migration/navigation_tree_renderer.dart';
+import 'package:analysis_server/src/edit/preview/preview_page.dart';
+import 'package:analysis_server/src/edit/preview/preview_site.dart';
+
+/// The JSON that is displayed for the navigation tree.
+class NavigationTreePage extends PreviewPage {
+  /// Initialize a newly created navigation tree page within the given [site].
+  NavigationTreePage(PreviewSite site)
+      : super(site, site.migrationInfo.includedRoot);
+
+  @override
+  // TODO(srawlins): Refactor JSON-returning pages like this to not inherit all
+  //  of the HTML logic from  [PreviewPage].
+  void generateBody(Map<String, String> params) {
+    throw UnsupportedError('generateBody');
+  }
+
+  @override
+  Future<void> generatePage(Map<String, String> params) async {
+    var renderer = NavigationTreeRenderer(site.migrationInfo, site.pathMapper);
+    buf.write(renderer.render());
+  }
+}
diff --git a/pkg/analysis_server/lib/src/edit/preview/preview_site.dart b/pkg/analysis_server/lib/src/edit/preview/preview_site.dart
index 4b229ea..bce1e06 100644
--- a/pkg/analysis_server/lib/src/edit/preview/preview_site.dart
+++ b/pkg/analysis_server/lib/src/edit/preview/preview_site.dart
@@ -14,6 +14,7 @@
 import 'package:analysis_server/src/edit/preview/highlight_js_page.dart';
 import 'package:analysis_server/src/edit/preview/http_preview_server.dart';
 import 'package:analysis_server/src/edit/preview/index_file_page.dart';
+import 'package:analysis_server/src/edit/preview/navigation_tree_page.dart';
 import 'package:analysis_server/src/edit/preview/not_found_page.dart';
 import 'package:analysis_server/src/edit/preview/region_page.dart';
 import 'package:analysis_server/src/status/pages.dart';
@@ -23,10 +24,12 @@
 class PreviewSite extends Site implements AbstractGetHandler {
   /// The path of the CSS page used to style the semantic highlighting within a
   /// Dart file.
-  static const highlightCssPagePath = '/css/androidstudio.css';
+  static const highlightCssPath = '/highlight.css';
 
   /// The path of the JS page used to associate highlighting within a Dart file.
-  static const highlightJSPagePath = '/js/highlight.pack.js';
+  static const highlightJsPath = '/highlight.pack.js';
+
+  static const navigationTreePath = '/_preview/navigationTree.json';
 
   /// The state of the migration being previewed.
   final MigrationState migrationState;
@@ -94,14 +97,18 @@
     }
     String path = uri.path;
     try {
-      if (path == highlightCssPagePath) {
+      if (path == highlightCssPath) {
         // Note: `return await` needed due to
         // https://github.com/dart-lang/language/issues/791
         return await respond(request, HighlightCssPage(this));
-      } else if (path == highlightJSPagePath) {
+      } else if (path == highlightJsPath) {
         // Note: `return await` needed due to
         // https://github.com/dart-lang/language/issues/791
         return await respond(request, HighlightJSPage(this));
+      } else if (path == navigationTreePath) {
+        // Note: `return await` needed due to
+        // https://github.com/dart-lang/language/issues/791
+        return await respond(request, NavigationTreePage(this));
       } else if (path == '/' || path == migrationInfo.includedRoot) {
         // Note: `return await` needed due to
         // https://github.com/dart-lang/language/issues/791
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_code_actions.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_code_actions.dart
index 1ee19e8..004e3e8 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_code_actions.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_code_actions.dart
@@ -247,7 +247,7 @@
 
     /// Helper to create refactors that execute commands provided with
     /// the current file, location and document version.
-    createRefactor(
+    Either2<Command, CodeAction> createRefactor(
       CodeActionKind actionKind,
       String name,
       RefactoringKind refactorKind, [
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_document_symbols.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_document_symbols.dart
index 018e384..79aa29b 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_document_symbols.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_document_symbols.dart
@@ -147,7 +147,7 @@
 
       // Adds a symbol and it's children recursively, supplying the parent
       // name as required by SymbolInformation.
-      addSymbol(Outline outline, {String parentName}) {
+      void addSymbol(Outline outline, {String parentName}) {
         allSymbols.add(_asSymbolInformation(
           parentName,
           clientSupportedSymbolKinds,
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handlers.dart b/pkg/analysis_server/lib/src/lsp/handlers/handlers.dart
index 116a5ae..b25a5d8 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handlers.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handlers.dart
@@ -159,7 +159,7 @@
         : error(ErrorCodes.MethodNotFound, 'Unknown method ${message.method}');
   }
 
-  registerHandler(MessageHandler handler) {
+  void registerHandler(MessageHandler handler) {
     assert(
         handler.handlesMessage != null,
         'Unable to register handler ${handler.runtimeType} because it does '
@@ -168,7 +168,7 @@
     _messageHandlers[handler.handlesMessage] = handler;
   }
 
-  reject(Method method, ErrorCodes code, String message) {
+  void reject(Method method, ErrorCodes code, String message) {
     registerHandler(RejectMessageHandler(server, method, code, message));
   }
 
diff --git a/pkg/analysis_server/lib/src/lsp/lsp_analysis_server.dart b/pkg/analysis_server/lib/src/lsp/lsp_analysis_server.dart
index eaa0423..12787be 100644
--- a/pkg/analysis_server/lib/src/lsp/lsp_analysis_server.dart
+++ b/pkg/analysis_server/lib/src/lsp/lsp_analysis_server.dart
@@ -192,7 +192,7 @@
   RefactoringWorkspace get refactoringWorkspace => _refactoringWorkspace ??=
       RefactoringWorkspace(driverMap.values, searchEngine);
 
-  addPriorityFile(String path) {
+  void addPriorityFile(String path) {
     final didAdd = priorityFiles.add(path);
     assert(didAdd);
     if (didAdd) {
@@ -381,7 +381,7 @@
     sendNotification(message);
   }
 
-  removePriorityFile(String path) {
+  void removePriorityFile(String path) {
     final didRemove = priorityFiles.remove(path);
     assert(didRemove);
     if (didRemove) {
@@ -569,7 +569,7 @@
     notifyDeclarationsTracker(path);
   }
 
-  _updateDriversPriorityFiles() {
+  void _updateDriversPriorityFiles() {
     driverMap.values.forEach((driver) {
       driver.priorityFiles = priorityFiles.toList();
     });
@@ -754,5 +754,5 @@
 
 class NullNotificationManager implements NotificationManager {
   @override
-  noSuchMethod(Invocation invocation) {}
+  dynamic noSuchMethod(Invocation invocation) {}
 }
diff --git a/pkg/analysis_server/lib/src/lsp/mapping.dart b/pkg/analysis_server/lib/src/lsp/mapping.dart
index 40e2bae..100a4f5 100644
--- a/pkg/analysis_server/lib/src/lsp/mapping.dart
+++ b/pkg/analysis_server/lib/src/lsp/mapping.dart
@@ -753,6 +753,39 @@
       element.returnType,
     );
 
+lsp.FlutterOutline toFlutterOutline(
+        server.LineInfo lineInfo, server.FlutterOutline outline) =>
+    lsp.FlutterOutline(
+      outline.kind.name,
+      outline.label,
+      outline.className,
+      outline.variableName,
+      outline.attributes != null
+          ? outline.attributes
+              .map(
+                  (attribute) => toFlutterOutlineAttribute(lineInfo, attribute))
+              .toList()
+          : null,
+      outline.dartElement != null
+          ? toElement(lineInfo, outline.dartElement)
+          : null,
+      toRange(lineInfo, outline.offset, outline.length),
+      toRange(lineInfo, outline.codeOffset, outline.codeLength),
+      outline.children != null
+          ? outline.children.map((c) => toFlutterOutline(lineInfo, c)).toList()
+          : null,
+    );
+
+lsp.FlutterOutlineAttribute toFlutterOutlineAttribute(
+        server.LineInfo lineInfo, server.FlutterOutlineAttribute attribute) =>
+    lsp.FlutterOutlineAttribute(
+        attribute.name,
+        attribute.label,
+        attribute.valueLocation != null
+            ? toRange(lineInfo, attribute.valueLocation.offset,
+                attribute.valueLocation.length)
+            : null);
+
 lsp.FoldingRange toFoldingRange(
     server.LineInfo lineInfo, server.FoldingRegion region) {
   final range = toRange(lineInfo, region.offset, region.length);
@@ -823,39 +856,6 @@
           : null,
     );
 
-lsp.FlutterOutline toFlutterOutline(
-        server.LineInfo lineInfo, server.FlutterOutline outline) =>
-    lsp.FlutterOutline(
-      outline.kind.name,
-      outline.label,
-      outline.className,
-      outline.variableName,
-      outline.attributes != null
-          ? outline.attributes
-              .map(
-                  (attribute) => toFlutterOutlineAttribute(lineInfo, attribute))
-              .toList()
-          : null,
-      outline.dartElement != null
-          ? toElement(lineInfo, outline.dartElement)
-          : null,
-      toRange(lineInfo, outline.offset, outline.length),
-      toRange(lineInfo, outline.codeOffset, outline.codeLength),
-      outline.children != null
-          ? outline.children.map((c) => toFlutterOutline(lineInfo, c)).toList()
-          : null,
-    );
-
-lsp.FlutterOutlineAttribute toFlutterOutlineAttribute(
-        server.LineInfo lineInfo, server.FlutterOutlineAttribute attribute) =>
-    lsp.FlutterOutlineAttribute(
-        attribute.name,
-        attribute.label,
-        attribute.valueLocation != null
-            ? toRange(lineInfo, attribute.valueLocation.offset,
-                attribute.valueLocation.length)
-            : null);
-
 lsp.Position toPosition(server.CharacterLocation location) {
   // LSP is zero-based, but analysis server is 1-based.
   return lsp.Position(location.lineNumber - 1, location.columnNumber - 1);
@@ -977,7 +977,7 @@
 
 Map<String, List<lsp.TextEdit>> toWorkspaceEditChanges(
     List<FileEditInformation> edits) {
-  createEdit(FileEditInformation file) {
+  MapEntry<String, List<lsp.TextEdit>> createEdit(FileEditInformation file) {
     final edits =
         file.edits.map((edit) => toTextEdit(file.lineInfo, edit)).toList();
     return MapEntry(file.doc.uri, edits);
diff --git a/pkg/analysis_server/lib/src/protocol_server.dart b/pkg/analysis_server/lib/src/protocol_server.dart
index caf804c..e5b3c4d 100644
--- a/pkg/analysis_server/lib/src/protocol_server.dart
+++ b/pkg/analysis_server/lib/src/protocol_server.dart
@@ -325,7 +325,10 @@
       startLine = offsetLocation.lineNumber;
       startColumn = offsetLocation.columnNumber;
     }
-  } on AnalysisException {}
+  } on AnalysisException {
+    // TODO(brianwilkerson) It doesn't look like the code in the try block
+    //  should be able to throw an exception. Try removing the try statement.
+  }
   return Location(unitElement.source.fullName, range.offset, range.length,
       startLine, startColumn);
 }
diff --git a/pkg/analysis_server/lib/src/search/workspace_symbols.dart b/pkg/analysis_server/lib/src/search/workspace_symbols.dart
index b28cb6a..63adfd4 100644
--- a/pkg/analysis_server/lib/src/search/workspace_symbols.dart
+++ b/pkg/analysis_server/lib/src/search/workspace_symbols.dart
@@ -138,7 +138,10 @@
       for (var library in libraries) {
         library.declarations.forEach(addDeclaration);
       }
-    } on _MaxNumberOfDeclarationsError {}
+    } on _MaxNumberOfDeclarationsError {
+      // Uses an exception to short circuit the recursion when there are too
+      // many declarations.
+    }
 
     return declarations;
   }
diff --git a/pkg/analysis_server/lib/src/server/driver.dart b/pkg/analysis_server/lib/src/server/driver.dart
index def78bb..b0b94d2 100644
--- a/pkg/analysis_server/lib/src/server/driver.dart
+++ b/pkg/analysis_server/lib/src/server/driver.dart
@@ -901,7 +901,10 @@
       try {
         String oldPath = i == 0 ? path : '$path.$i';
         File(oldPath).renameSync('$path.${i + 1}');
-      } catch (e) {}
+      } catch (e) {
+        // If a file can't be renamed, then leave it and attempt to rename the
+        // remaining files.
+      }
     }
   }
 }
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/inherited_reference_contributor.dart b/pkg/analysis_server/lib/src/services/completion/dart/inherited_reference_contributor.dart
index e1c138d..eebf652 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/inherited_reference_contributor.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/inherited_reference_contributor.dart
@@ -74,7 +74,7 @@
     return const <CompletionSuggestion>[];
   }
 
-  _addSuggestionsForType(InterfaceType type, DartCompletionRequest request,
+  void _addSuggestionsForType(InterfaceType type, DartCompletionRequest request,
       {bool isFunctionalArgument = false}) {
     OpType opType = request.opType;
     if (!isFunctionalArgument) {
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/keyword_contributor.dart b/pkg/analysis_server/lib/src/services/completion/dart/keyword_contributor.dart
index 7193ac6..7c84590 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/keyword_contributor.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/keyword_contributor.dart
@@ -48,7 +48,7 @@
 /**
  * A visitor for generating keyword suggestions.
  */
-class _KeywordVisitor extends GeneralizingAstVisitor {
+class _KeywordVisitor extends GeneralizingAstVisitor<void> {
   final DartCompletionRequest request;
   final Object entity;
   final List<CompletionSuggestion> suggestions;
@@ -64,7 +64,7 @@
       (body is BlockFunctionBody && body.beginToken.isSynthetic);
 
   @override
-  visitArgumentList(ArgumentList node) {
+  void visitArgumentList(ArgumentList node) {
     if (request is DartCompletionRequestImpl) {
       //TODO(danrubel) consider adding opType to the API then remove this cast
       OpType opType = (request as DartCompletionRequestImpl).opType;
@@ -102,7 +102,7 @@
   }
 
   @override
-  visitAsExpression(AsExpression node) {
+  void visitAsExpression(AsExpression node) {
     if (identical(entity, node.asOperator) &&
         node.expression is ParenthesizedExpression) {
       _addSuggestion(Keyword.ASYNC, DART_RELEVANCE_HIGH);
@@ -112,7 +112,7 @@
   }
 
   @override
-  visitBlock(Block node) {
+  void visitBlock(Block node) {
     Statement prevStmt = OpType.getPreviousStatement(node, entity);
     if (prevStmt is TryStatement) {
       if (prevStmt.finallyBlock == null) {
@@ -154,7 +154,7 @@
   }
 
   @override
-  visitClassDeclaration(ClassDeclaration node) {
+  void visitClassDeclaration(ClassDeclaration node) {
     // Don't suggest class name
     if (entity == node.name) {
       return;
@@ -176,7 +176,7 @@
   }
 
   @override
-  visitCompilationUnit(CompilationUnit node) {
+  void visitCompilationUnit(CompilationUnit node) {
     var previousMember;
     for (var member in node.childEntities) {
       if (entity == member) {
@@ -245,7 +245,7 @@
   }
 
   @override
-  visitConstructorDeclaration(ConstructorDeclaration node) {
+  void visitConstructorDeclaration(ConstructorDeclaration node) {
     if (node.initializers.isNotEmpty) {
       if (entity is ConstructorInitializer) {
         _addSuggestion(Keyword.ASSERT);
@@ -272,26 +272,26 @@
   }
 
   @override
-  visitDefaultFormalParameter(DefaultFormalParameter node) {
+  void visitDefaultFormalParameter(DefaultFormalParameter node) {
     if (entity == node.defaultValue) {
       _addExpressionKeywords(node);
     }
   }
 
   @override
-  visitExpression(Expression node) {
+  void visitExpression(Expression node) {
     _addExpressionKeywords(node);
   }
 
   @override
-  visitExpressionFunctionBody(ExpressionFunctionBody node) {
+  void visitExpressionFunctionBody(ExpressionFunctionBody node) {
     if (entity == node.expression) {
       _addExpressionKeywords(node);
     }
   }
 
   @override
-  visitExtensionDeclaration(ExtensionDeclaration node) {
+  void visitExtensionDeclaration(ExtensionDeclaration node) {
     // Don't suggest extension name
     if (entity == node.name) {
       return;
@@ -306,7 +306,7 @@
   }
 
   @override
-  visitFieldDeclaration(FieldDeclaration node) {
+  void visitFieldDeclaration(FieldDeclaration node) {
     VariableDeclarationList fields = node.fields;
     if (entity != fields) {
       return;
@@ -334,7 +334,7 @@
   }
 
   @override
-  visitForEachParts(ForEachParts node) {
+  void visitForEachParts(ForEachParts node) {
     if (entity == node.inKeyword) {
       Token previous = node.findPrevious(node.inKeyword);
       if (previous is SyntheticStringToken && previous.lexeme == 'in') {
@@ -350,14 +350,14 @@
   }
 
   @override
-  visitForElement(ForElement node) {
+  void visitForElement(ForElement node) {
     _addCollectionElementKeywords();
     _addExpressionKeywords(node);
     return super.visitForElement(node);
   }
 
   @override
-  visitFormalParameterList(FormalParameterList node) {
+  void visitFormalParameterList(FormalParameterList node) {
     AstNode constructorDeclaration =
         node.thisOrAncestorOfType<ConstructorDeclaration>();
     if (constructorDeclaration != null) {
@@ -380,7 +380,7 @@
   }
 
   @override
-  visitForParts(ForParts node) {
+  void visitForParts(ForParts node) {
     // Actual: for (int x i^)
     // Parsed: for (int x; i^;)
     // Handle the degenerate case while typing - for (int x i^)
@@ -395,7 +395,7 @@
   }
 
   @override
-  visitForStatement(ForStatement node) {
+  void visitForStatement(ForStatement node) {
     // Actual: for (va^)
     // Parsed: for (va^; ;)
     if (node.forLoopParts == entity) {
@@ -404,7 +404,7 @@
   }
 
   @override
-  visitFunctionExpression(FunctionExpression node) {
+  void visitFunctionExpression(FunctionExpression node) {
     if (entity == node.body) {
       FunctionBody body = node.body;
       if (!body.isAsynchronous) {
@@ -423,14 +423,14 @@
   }
 
   @override
-  visitIfElement(IfElement node) {
+  void visitIfElement(IfElement node) {
     _addCollectionElementKeywords();
     _addExpressionKeywords(node);
     return super.visitIfElement(node);
   }
 
   @override
-  visitIfStatement(IfStatement node) {
+  void visitIfStatement(IfStatement node) {
     if (_isPreviousTokenSynthetic(entity, TokenType.CLOSE_PAREN)) {
       // analyzer parser
       // Actual: if (x i^)
@@ -452,7 +452,7 @@
   }
 
   @override
-  visitImportDirective(ImportDirective node) {
+  void visitImportDirective(ImportDirective node) {
     if (entity == node.asKeyword) {
       if (node.deferredKeyword == null) {
         _addSuggestion(Keyword.DEFERRED, DART_RELEVANCE_HIGH);
@@ -469,7 +469,7 @@
   }
 
   @override
-  visitInstanceCreationExpression(InstanceCreationExpression node) {
+  void visitInstanceCreationExpression(InstanceCreationExpression node) {
     if (entity == node.constructorName) {
       // no keywords in 'new ^' expression
     } else {
@@ -478,7 +478,7 @@
   }
 
   @override
-  visitIsExpression(IsExpression node) {
+  void visitIsExpression(IsExpression node) {
     if (entity == node.isOperator) {
       _addSuggestion(Keyword.IS, DART_RELEVANCE_HIGH);
     } else {
@@ -487,18 +487,18 @@
   }
 
   @override
-  visitLibraryIdentifier(LibraryIdentifier node) {
+  void visitLibraryIdentifier(LibraryIdentifier node) {
     // no suggestions
   }
 
   @override
-  visitListLiteral(ListLiteral node) {
+  void visitListLiteral(ListLiteral node) {
     _addCollectionElementKeywords();
     super.visitListLiteral(node);
   }
 
   @override
-  visitMethodDeclaration(MethodDeclaration node) {
+  void visitMethodDeclaration(MethodDeclaration node) {
     if (entity == node.body) {
       if (isEmptyBody(node.body)) {
         _addClassBodyKeywords();
@@ -516,7 +516,7 @@
   }
 
   @override
-  visitMethodInvocation(MethodInvocation node) {
+  void visitMethodInvocation(MethodInvocation node) {
     if (entity == node.methodName || entity == node.argumentList) {
       // no keywords in '.' expressions or type argument lists
       // Note that we're checking the argumentList rather than the typeArgumentList
@@ -529,7 +529,7 @@
   }
 
   @override
-  visitMixinDeclaration(MixinDeclaration node) {
+  void visitMixinDeclaration(MixinDeclaration node) {
     // Don't suggest mixin name
     if (entity == node.name) {
       return;
@@ -551,19 +551,19 @@
   }
 
   @override
-  visitNamedExpression(NamedExpression node) {
+  void visitNamedExpression(NamedExpression node) {
     if (entity is SimpleIdentifier && entity == node.expression) {
       _addExpressionKeywords(node);
     }
   }
 
   @override
-  visitNode(AstNode node) {
+  void visitNode(AstNode node) {
     // ignored
   }
 
   @override
-  visitParenthesizedExpression(ParenthesizedExpression node) {
+  void visitParenthesizedExpression(ParenthesizedExpression node) {
     Expression expression = node.expression;
     if (expression is Identifier || expression is PropertyAccess) {
       if (entity == node.rightParenthesis) {
@@ -580,14 +580,14 @@
   }
 
   @override
-  visitPrefixedIdentifier(PrefixedIdentifier node) {
+  void visitPrefixedIdentifier(PrefixedIdentifier node) {
     if (entity != node.identifier) {
       _addExpressionKeywords(node);
     }
   }
 
   @override
-  visitPropertyAccess(PropertyAccess node) {
+  void visitPropertyAccess(PropertyAccess node) {
     // suggestions before '.' but not after
     if (entity != node.propertyName) {
       super.visitPropertyAccess(node);
@@ -595,37 +595,37 @@
   }
 
   @override
-  visitReturnStatement(ReturnStatement node) {
+  void visitReturnStatement(ReturnStatement node) {
     if (entity == node.expression) {
       _addExpressionKeywords(node);
     }
   }
 
   @override
-  visitSetOrMapLiteral(SetOrMapLiteral node) {
+  void visitSetOrMapLiteral(SetOrMapLiteral node) {
     _addCollectionElementKeywords();
     super.visitSetOrMapLiteral(node);
   }
 
   @override
-  visitSpreadElement(SpreadElement node) {
+  void visitSpreadElement(SpreadElement node) {
     _addExpressionKeywords(node);
     return super.visitSpreadElement(node);
   }
 
   @override
-  visitStringLiteral(StringLiteral node) {
+  void visitStringLiteral(StringLiteral node) {
     // ignored
   }
 
   @override
-  visitSwitchCase(SwitchCase node) {
+  void visitSwitchCase(SwitchCase node) {
     _addStatementKeywords(node);
     return super.visitSwitchCase(node);
   }
 
   @override
-  visitSwitchStatement(SwitchStatement node) {
+  void visitSwitchStatement(SwitchStatement node) {
     if (entity == node.expression) {
       _addExpressionKeywords(node);
     } else if (entity == node.rightBracket) {
@@ -651,7 +651,7 @@
   }
 
   @override
-  visitTryStatement(TryStatement node) {
+  void visitTryStatement(TryStatement node) {
     var obj = entity;
     if (obj is CatchClause ||
         (obj is KeywordToken && obj.value() == Keyword.FINALLY)) {
@@ -663,7 +663,7 @@
   }
 
   @override
-  visitVariableDeclaration(VariableDeclaration node) {
+  void visitVariableDeclaration(VariableDeclaration node) {
     if (entity == node.initializer) {
       _addExpressionKeywords(node);
     }
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/static_member_contributor.dart b/pkg/analysis_server/lib/src/services/completion/dart/static_member_contributor.dart
index 6b1bb3f..403338c 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/static_member_contributor.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/static_member_contributor.dart
@@ -46,7 +46,7 @@
  * This class visits elements in a class and provides suggestions based upon
  * the visible static members in that class.
  */
-class _SuggestionBuilder extends GeneralizingElementVisitor {
+class _SuggestionBuilder extends GeneralizingElementVisitor<void> {
   /**
    * The library containing the unit in which the completion is requested.
    */
@@ -60,41 +60,41 @@
   _SuggestionBuilder(this.containingLibrary);
 
   @override
-  visitClassElement(ClassElement element) {
+  void visitClassElement(ClassElement element) {
     element.visitChildren(this);
   }
 
   @override
-  visitConstructorElement(ConstructorElement element) {
+  void visitConstructorElement(ConstructorElement element) {
     _addSuggestion(element);
   }
 
   @override
-  visitElement(Element element) {
+  void visitElement(Element element) {
     // ignored
   }
 
   @override
-  visitExtensionElement(ExtensionElement element) {
+  void visitExtensionElement(ExtensionElement element) {
     element.visitChildren(this);
   }
 
   @override
-  visitFieldElement(FieldElement element) {
+  void visitFieldElement(FieldElement element) {
     if (element.isStatic) {
       _addSuggestion(element);
     }
   }
 
   @override
-  visitMethodElement(MethodElement element) {
+  void visitMethodElement(MethodElement element) {
     if (element.isStatic && !element.isOperator) {
       _addSuggestion(element);
     }
   }
 
   @override
-  visitPropertyAccessorElement(PropertyAccessorElement element) {
+  void visitPropertyAccessorElement(PropertyAccessorElement element) {
     if (element.isStatic) {
       _addSuggestion(element);
     }
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/suggestion_builder.dart b/pkg/analysis_server/lib/src/services/completion/dart/suggestion_builder.dart
index a41beec..cd9e001 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/suggestion_builder.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/suggestion_builder.dart
@@ -182,7 +182,7 @@
 /**
  * This class creates suggestions based upon top-level elements.
  */
-class LibraryElementSuggestionBuilder extends SimpleElementVisitor
+class LibraryElementSuggestionBuilder extends SimpleElementVisitor<void>
     with ElementSuggestionBuilder {
   @override
   final LibraryElement containingLibrary;
@@ -195,7 +195,7 @@
       this.containingLibrary, this.kind, this.typesOnly, this.instCreation);
 
   @override
-  visitClassElement(ClassElement element) {
+  void visitClassElement(ClassElement element) {
     if (instCreation) {
       element.visitChildren(this);
     } else {
@@ -204,7 +204,7 @@
   }
 
   @override
-  visitConstructorElement(ConstructorElement element) {
+  void visitConstructorElement(ConstructorElement element) {
     if (instCreation) {
       ClassElement classElem = element.enclosingElement;
       if (classElem != null) {
@@ -217,14 +217,14 @@
   }
 
   @override
-  visitExtensionElement(ExtensionElement element) {
+  void visitExtensionElement(ExtensionElement element) {
     if (!instCreation) {
       addSuggestion(element);
     }
   }
 
   @override
-  visitFunctionElement(FunctionElement element) {
+  void visitFunctionElement(FunctionElement element) {
     if (!typesOnly) {
       int relevance = element.library == containingLibrary
           ? DART_RELEVANCE_LOCAL_FUNCTION
@@ -234,14 +234,14 @@
   }
 
   @override
-  visitFunctionTypeAliasElement(FunctionTypeAliasElement element) {
+  void visitFunctionTypeAliasElement(FunctionTypeAliasElement element) {
     if (!instCreation) {
       addSuggestion(element);
     }
   }
 
   @override
-  visitPropertyAccessorElement(PropertyAccessorElement element) {
+  void visitPropertyAccessorElement(PropertyAccessorElement element) {
     if (!typesOnly) {
       PropertyInducingElement variable = element.variable;
       int relevance = variable.library == containingLibrary
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/type_member_contributor.dart b/pkg/analysis_server/lib/src/services/completion/dart/type_member_contributor.dart
index 930181e..81e642d 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/type_member_contributor.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/type_member_contributor.dart
@@ -109,6 +109,10 @@
           mixins: mixins, superclassConstraints: superclassConstraints);
       return builder.suggestions.toList();
     }
+    if (type is FunctionType) {
+      return [_SuggestionBuilder._createFunctionCallSuggestion()];
+    }
+
     return const <CompletionSuggestion>[];
   }
 }
@@ -291,33 +295,11 @@
         }
       }
       if (targetType.isDartCoreFunction) {
-        _addFunctionCallSuggestion();
+        addCompletionSuggestion(_createFunctionCallSuggestion());
       }
     }
   }
 
-  void _addFunctionCallSuggestion() {
-    const callString = 'call()';
-    final element = protocol.Element(
-        protocol.ElementKind.METHOD, callString, protocol.Element.makeFlags(),
-        location: null,
-        typeParameters: null,
-        parameters: null,
-        returnType: 'void');
-    addCompletionSuggestion(CompletionSuggestion(
-      CompletionSuggestionKind.INVOCATION,
-      DART_RELEVANCE_HIGH,
-      callString,
-      callString.length,
-      0,
-      false,
-      false,
-      displayText: callString,
-      element: element,
-      returnType: 'void',
-    ));
-  }
-
   /**
    * Get a list of [InterfaceType]s that should be searched to find the
    * possible completions for an object having type [type].
@@ -355,4 +337,26 @@
     }
     return result;
   }
+
+  static CompletionSuggestion _createFunctionCallSuggestion() {
+    const callString = 'call()';
+    final element = protocol.Element(
+        protocol.ElementKind.METHOD, callString, protocol.Element.makeFlags(),
+        location: null,
+        typeParameters: null,
+        parameters: null,
+        returnType: 'void');
+    return CompletionSuggestion(
+      CompletionSuggestionKind.INVOCATION,
+      DART_RELEVANCE_HIGH,
+      callString,
+      callString.length,
+      0,
+      false,
+      false,
+      displayText: callString,
+      element: element,
+      returnType: 'void',
+    );
+  }
 }
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/uri_contributor.dart b/pkg/analysis_server/lib/src/services/completion/dart/uri_contributor.dart
index 4d966a0..4d1e6da 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/uri_contributor.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/uri_contributor.dart
@@ -42,23 +42,23 @@
   }
 }
 
-class _UriSuggestionBuilder extends SimpleAstVisitor {
+class _UriSuggestionBuilder extends SimpleAstVisitor<void> {
   final DartCompletionRequest request;
   final List<CompletionSuggestion> suggestions = <CompletionSuggestion>[];
 
   _UriSuggestionBuilder(this.request);
 
   @override
-  visitExportDirective(ExportDirective node) {
+  void visitExportDirective(ExportDirective node) {
     visitNamespaceDirective(node);
   }
 
   @override
-  visitImportDirective(ImportDirective node) {
+  void visitImportDirective(ImportDirective node) {
     visitNamespaceDirective(node);
   }
 
-  visitNamespaceDirective(NamespaceDirective node) {
+  void visitNamespaceDirective(NamespaceDirective node) {
     StringLiteral uri = node.uri;
     if (uri is SimpleStringLiteral) {
       int offset = request.offset;
@@ -99,7 +99,7 @@
   }
 
   @override
-  visitSimpleStringLiteral(SimpleStringLiteral node) {
+  void visitSimpleStringLiteral(SimpleStringLiteral node) {
     AstNode parent = node.parent;
     if (parent is NamespaceDirective && parent.uri == node) {
       String partialUri = _extractPartialUri(node);
diff --git a/pkg/analysis_server/lib/src/services/correction/assist_internal.dart b/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
index 25823b5..8c2f968 100644
--- a/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
@@ -2703,10 +2703,12 @@
     var changeBuilder = _newDartChangeBuilder();
     await changeBuilder.addFileEdit(file, (builder) {
       if (variableList.type == null) {
-        builder.addReplacement(range.token(variableList.keyword), (builder) {
-          var type = variable.declaredElement.type;
-          builder.writeType(type);
-        });
+        final type = variable.declaredElement.type;
+        if (!type.isDynamic) {
+          builder.addReplacement(range.token(variableList.keyword), (builder) {
+            builder.writeType(type);
+          });
+        }
       }
 
       var indent = utils.getNodePrefix(statement);
@@ -3000,7 +3002,7 @@
     int listLoc = childArg.offset;
     String childArgSrc = getNodeText(childArg);
     if (!childArgSrc.contains(eol)) {
-      builder.addSimpleInsertion(listLoc, '<Widget>[');
+      builder.addSimpleInsertion(listLoc, '[');
       builder.addSimpleInsertion(listLoc + childArg.length, ']');
     } else {
       int newlineLoc = childArgSrc.lastIndexOf(eol);
@@ -3014,13 +3016,12 @@
           getText(namedExp.offset, childArg.offset - namedExp.offset);
       String prefix = separator.contains(eol) ? '' : '$eol$indentNew';
       if (prefix.isEmpty) {
-        builder.addSimpleInsertion(
-            namedExp.offset + 'child:'.length, ' <Widget>[');
+        builder.addSimpleInsertion(namedExp.offset + 'child:'.length, ' [');
         int argOffset = childArg.offset;
         builder
             .addDeletion(range.startOffsetEndOffset(argOffset - 2, argOffset));
       } else {
-        builder.addSimpleInsertion(listLoc, '<Widget>[');
+        builder.addSimpleInsertion(listLoc, '[');
       }
       String newChildArgSrc =
           _replaceSourceIndent(childArgSrc, indentOld, indentNew);
@@ -3160,13 +3161,13 @@
   }
 }
 
-class _SimpleIdentifierRecursiveAstVisitor extends RecursiveAstVisitor {
+class _SimpleIdentifierRecursiveAstVisitor extends RecursiveAstVisitor<void> {
   final _SimpleIdentifierVisitor visitor;
 
   _SimpleIdentifierRecursiveAstVisitor(this.visitor);
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     visitor(node);
   }
 }
@@ -3175,13 +3176,13 @@
  * A visitor used to find all of the classes that define members referenced via
  * `super`.
  */
-class _SuperclassReferenceFinder extends RecursiveAstVisitor {
+class _SuperclassReferenceFinder extends RecursiveAstVisitor<void> {
   final List<ClassElement> referencedClasses = <ClassElement>[];
 
   _SuperclassReferenceFinder();
 
   @override
-  visitSuperExpression(SuperExpression node) {
+  void visitSuperExpression(SuperExpression node) {
     AstNode parent = node.parent;
     if (parent is BinaryExpression) {
       _addElement(parent.staticElement);
diff --git a/pkg/analysis_server/lib/src/services/correction/base_processor.dart b/pkg/analysis_server/lib/src/services/correction/base_processor.dart
index c8eb22c..bdf20ee 100644
--- a/pkg/analysis_server/lib/src/services/correction/base_processor.dart
+++ b/pkg/analysis_server/lib/src/services/correction/base_processor.dart
@@ -1623,7 +1623,7 @@
 /// Copied from lib/src/services/correction/base_processor.dart, but [hasReturn]
 /// was added.
 // TODO(brianwilkerson) Decide whether to unify the two classes.
-class _ReturnTypeComputer extends RecursiveAstVisitor {
+class _ReturnTypeComputer extends RecursiveAstVisitor<void> {
   final TypeSystem typeSystem;
 
   DartType returnType;
@@ -1634,10 +1634,10 @@
   _ReturnTypeComputer(this.typeSystem);
 
   @override
-  visitBlockFunctionBody(BlockFunctionBody node) {}
+  void visitBlockFunctionBody(BlockFunctionBody node) {}
 
   @override
-  visitReturnStatement(ReturnStatement node) {
+  void visitReturnStatement(ReturnStatement node) {
     hasReturn = true;
     // prepare expression
     Expression expression = node.expression;
diff --git a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
index 597ba77..cba9fee 100644
--- a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
@@ -1489,9 +1489,6 @@
       var changeBuilder = _newDartChangeBuilder();
       await changeBuilder.addFileEdit(file, (DartFileEditBuilder builder) {
         builder.addSimpleReplacement(range.node(named.name), 'children:');
-        if (expression.typeArguments == null) {
-          builder.addSimpleInsertion(expression.offset, '<Widget>');
-        }
       });
       _addFixFromBuilder(changeBuilder, DartFixKind.CONVERT_FLUTTER_CHILD);
     }
@@ -3412,9 +3409,15 @@
   }
 
   Future<void> _addFix_removeEmptyCatch() async {
+    var catchClause = node.parent as CatchClause;
+    var tryStatement = catchClause.parent as TryStatement;
+    if (tryStatement.catchClauses.length == 1 &&
+        tryStatement.finallyBlock == null) {
+      return;
+    }
     var changeBuilder = _newDartChangeBuilder();
     await changeBuilder.addFileEdit(file, (DartFileEditBuilder builder) {
-      builder.addDeletion(utils.getLinesRange(range.node(node.parent)));
+      builder.addDeletion(utils.getLinesRange(range.node(catchClause)));
     });
     _addFixFromBuilder(changeBuilder, DartFixKind.REMOVE_EMPTY_CATCH);
   }
diff --git a/pkg/analysis_server/lib/src/services/correction/util.dart b/pkg/analysis_server/lib/src/services/correction/util.dart
index fd6cd4f..4a4aa85 100644
--- a/pkg/analysis_server/lib/src/services/correction/util.dart
+++ b/pkg/analysis_server/lib/src/services/correction/util.dart
@@ -1503,11 +1503,11 @@
 /**
  * Visitor that collects defined [LocalElement]s.
  */
-class _LocalElementsCollector extends RecursiveAstVisitor {
+class _LocalElementsCollector extends RecursiveAstVisitor<void> {
   final elements = <LocalElement>[];
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     if (node.inDeclarationContext()) {
       Element element = node.staticElement;
       if (element is LocalElement) {
diff --git a/pkg/analysis_server/lib/src/services/kythe/kythe_visitors.dart b/pkg/analysis_server/lib/src/services/kythe/kythe_visitors.dart
index b3a757e..be5ac64 100644
--- a/pkg/analysis_server/lib/src/services/kythe/kythe_visitors.dart
+++ b/pkg/analysis_server/lib/src/services/kythe/kythe_visitors.dart
@@ -82,16 +82,10 @@
   return '$nodeKind:${element.accept(SignatureElementVisitor.instance)}';
 }
 
-class CodedBufferWriter {
-  CodedBufferWriter(var v);
-
-  toBuffer() {}
-}
-
 /// This visitor writes out Kythe facts and edges as specified by the Kythe
 /// Schema here https://kythe.io/docs/schema/.  This visitor handles all nodes,
 /// facts and edges.
-class KytheDartVisitor extends GeneralizingAstVisitor with OutputUtils {
+class KytheDartVisitor extends GeneralizingAstVisitor<void> with OutputUtils {
   @override
   final ResourceProvider resourceProvider;
   @override
@@ -117,7 +111,7 @@
   String get enclosingFilePath => _enclosingFilePath;
 
   @override
-  visitAnnotation(Annotation node) {
+  void visitAnnotation(Annotation node) {
     // TODO(jwren) To get the full set of cross refs correct, additional ref
     // edges are needed, example: from "A" in "A.namedConstructor()"
 
@@ -164,7 +158,7 @@
   }
 
   @override
-  visitAssignmentExpression(AssignmentExpression node) {
+  void visitAssignmentExpression(AssignmentExpression node) {
     //
     // operator
     // NOTE: usage node only written out if assignment is not the '=' operator,
@@ -188,7 +182,7 @@
   }
 
   @override
-  visitBinaryExpression(BinaryExpression node) {
+  void visitBinaryExpression(BinaryExpression node) {
     //
     // operators such as +, -, *, /
     //
@@ -209,7 +203,7 @@
   }
 
   @override
-  visitClassDeclaration(ClassDeclaration node) {
+  void visitClassDeclaration(ClassDeclaration node) {
     return _withEnclosingElement(node.declaredElement, () {
       // record/ class node
       addNodeAndFacts(schema.RECORD_KIND,
@@ -279,7 +273,7 @@
   }
 
   @override
-  visitClassTypeAlias(ClassTypeAlias node) {
+  void visitClassTypeAlias(ClassTypeAlias node) {
     return _withEnclosingElement(node.declaredElement, () {
       // record/ class node
       addNodeAndFacts(schema.RECORD_KIND,
@@ -344,7 +338,7 @@
   }
 
   @override
-  visitCompilationUnit(CompilationUnit node) {
+  void visitCompilationUnit(CompilationUnit node) {
     _enclosingFilePath = _getPath(resourceProvider, node.declaredElement);
     _enclosingUnitFeatureSet = node.featureSet;
     return _withEnclosingElement(node.declaredElement, () {
@@ -397,7 +391,7 @@
   }
 
   @override
-  visitConstructorDeclaration(ConstructorDeclaration node) {
+  void visitConstructorDeclaration(ConstructorDeclaration node) {
     return _withEnclosingElement(node.declaredElement, () {
       // function/ constructor node
       var constructorVName = addNodeAndFacts(schema.FUNCTION_KIND,
@@ -437,7 +431,7 @@
   }
 
   @override
-  visitDeclaredIdentifier(DeclaredIdentifier node) {
+  void visitDeclaredIdentifier(DeclaredIdentifier node) {
     _handleVariableDeclaration(node.declaredElement, node.identifier,
         subKind: schema.LOCAL_SUBKIND, type: node.declaredElement.type);
 
@@ -445,7 +439,7 @@
   }
 
   @override
-  visitEnumConstantDeclaration(EnumConstantDeclaration node) {
+  void visitEnumConstantDeclaration(EnumConstantDeclaration node) {
     // constant node
     var constDeclVName =
         addNodeAndFacts(schema.CONSTANT_KIND, element: node.declaredElement);
@@ -464,7 +458,7 @@
   }
 
   @override
-  visitEnumDeclaration(EnumDeclaration node) {
+  void visitEnumDeclaration(EnumDeclaration node) {
     return _withEnclosingElement(node.declaredElement, () {
       // record/ enum node
       addNodeAndFacts(schema.RECORD_KIND,
@@ -495,7 +489,7 @@
   }
 
   @override
-  visitFieldFormalParameter(FieldFormalParameter node) {
+  void visitFieldFormalParameter(FieldFormalParameter node) {
     // identifier
     // Specified as Element, not var, so that the type can be changed in the
     // if-block.
@@ -518,7 +512,7 @@
   }
 
   @override
-  visitFunctionDeclaration(FunctionDeclaration node) {
+  void visitFunctionDeclaration(FunctionDeclaration node) {
     return _withEnclosingElement(node.declaredElement, () {
       // function node
       var functionVName = addNodeAndFacts(schema.FUNCTION_KIND,
@@ -554,13 +548,13 @@
   }
 
   @override
-  visitFunctionExpression(FunctionExpression node) {
+  void visitFunctionExpression(FunctionExpression node) {
     return _withEnclosingElement(
         node.declaredElement, () => super.visitFunctionExpression(node));
   }
 
   @override
-  visitFunctionTypeAlias(FunctionTypeAlias node) {
+  void visitFunctionTypeAlias(FunctionTypeAlias node) {
     //
     // return type
     //
@@ -587,7 +581,7 @@
   }
 
   @override
-  visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
+  void visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
     // TODO(jwren) Missing graph coverage on FunctionTypedFormalParameters
     // visit children
     _safelyVisit(node.documentationComment);
@@ -598,7 +592,7 @@
   }
 
   @override
-  visitImportDirective(ImportDirective node) {
+  void visitImportDirective(ImportDirective node) {
     // uri
     _handleUriReference(node.uri, node.uriElement);
 
@@ -620,7 +614,7 @@
   }
 
   @override
-  visitIndexExpression(IndexExpression node) {
+  void visitIndexExpression(IndexExpression node) {
     //
     // index method ref/call
     //
@@ -638,7 +632,7 @@
   }
 
   @override
-  visitInstanceCreationExpression(InstanceCreationExpression node) {
+  void visitInstanceCreationExpression(InstanceCreationExpression node) {
     //
     // constructorName
     //
@@ -671,7 +665,7 @@
   }
 
   @override
-  visitMethodDeclaration(MethodDeclaration node) {
+  void visitMethodDeclaration(MethodDeclaration node) {
     return _withEnclosingElement(node.declaredElement, () {
       // function node
       var methodVName = addNodeAndFacts(schema.FUNCTION_KIND,
@@ -725,7 +719,7 @@
   }
 
   @override
-  visitMethodInvocation(MethodInvocation node) {
+  void visitMethodInvocation(MethodInvocation node) {
     var element = node.methodName?.staticElement;
 
     // anchor- ref/call
@@ -738,7 +732,7 @@
   }
 
   @override
-  visitSimpleFormalParameter(SimpleFormalParameter node) {
+  void visitSimpleFormalParameter(SimpleFormalParameter node) {
     // parameter node
     var paramVName = addNodeAndFacts(schema.VARIABLE_KIND,
         element: node.declaredElement,
@@ -800,7 +794,7 @@
   }
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     // Most simple identifiers are "ref" edges.  In cases some cases, there may
     // be other ref/* edges.
 
@@ -827,17 +821,17 @@
   }
 
   @override
-  visitSuperExpression(SuperExpression node) {
+  void visitSuperExpression(SuperExpression node) {
     _handleThisOrSuper(node);
   }
 
   @override
-  visitThisExpression(ThisExpression node) {
+  void visitThisExpression(ThisExpression node) {
     _handleThisOrSuper(node);
   }
 
   @override
-  visitUriBasedDirective(UriBasedDirective node) {
+  void visitUriBasedDirective(UriBasedDirective node) {
     _handleUriReference(node.uri, node.uriElement);
 
     // visit children
@@ -845,7 +839,7 @@
   }
 
   @override
-  visitVariableDeclaration(VariableDeclaration node) {
+  void visitVariableDeclaration(VariableDeclaration node) {
     var isLocal = _enclosingVName != _enclosingClassVName &&
         _enclosingVName != _enclosingFileVName;
 
@@ -893,7 +887,7 @@
     return null;
   }
 
-  _handleRefCallEdge(
+  void _handleRefCallEdge(
     Element element, {
     SyntacticEntity syntacticEntity,
     int start = _notFound,
@@ -1046,7 +1040,7 @@
     }
   }
 
-  _handleVariableDeclarationListAnnotations(
+  void _handleVariableDeclarationListAnnotations(
       VariableDeclarationList variableDeclarationList, KytheVName refVName) {
     assert(refVName != null);
     for (var varDecl in variableDeclarationList.variables) {
@@ -1075,7 +1069,7 @@
     }
   }
 
-  _withEnclosingElement(Element element, Function() f) {
+  void _withEnclosingElement(Element element, Function() f) {
     Element outerEnclosingElement = _enclosingElement;
     Element outerEnclosingClassElement = _enclosingClassElement;
     var outerEnclosingVName = _enclosingVName;
diff --git a/pkg/analysis_server/lib/src/services/refactoring/extract_local.dart b/pkg/analysis_server/lib/src/services/refactoring/extract_local.dart
index 17b436a..767eaa3 100644
--- a/pkg/analysis_server/lib/src/services/refactoring/extract_local.dart
+++ b/pkg/analysis_server/lib/src/services/refactoring/extract_local.dart
@@ -587,13 +587,13 @@
   }
 }
 
-class _TokenLocalElementVisitor extends RecursiveAstVisitor {
+class _TokenLocalElementVisitor extends RecursiveAstVisitor<void> {
   final Map<Token, Element> map;
 
   _TokenLocalElementVisitor(this.map);
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     Element element = node.staticElement;
     if (element is LocalVariableElement) {
       map[node.token] = element;
diff --git a/pkg/analysis_server/lib/src/services/refactoring/extract_method.dart b/pkg/analysis_server/lib/src/services/refactoring/extract_method.dart
index c58b0a3..012cef0 100644
--- a/pkg/analysis_server/lib/src/services/refactoring/extract_method.dart
+++ b/pkg/analysis_server/lib/src/services/refactoring/extract_method.dart
@@ -140,7 +140,7 @@
   List<RefactoringMethodParameter> get parameters => _parameters;
 
   @override
-  void set parameters(List<RefactoringMethodParameter> parameters) {
+  set parameters(List<RefactoringMethodParameter> parameters) {
     _parameters = parameters.toList();
   }
 
@@ -1076,7 +1076,7 @@
   bool _isFirstSelectedNode(AstNode node) => identical(firstSelectedNode, node);
 }
 
-class _GetSourcePatternVisitor extends GeneralizingAstVisitor {
+class _GetSourcePatternVisitor extends GeneralizingAstVisitor<void> {
   final SourceRange partRange;
   final _SourcePattern pattern;
   final List<SourceEdit> replaceEdits;
@@ -1084,7 +1084,7 @@
   _GetSourcePatternVisitor(this.partRange, this.pattern, this.replaceEdits);
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     SourceRange nodeRange = range.node(node);
     if (partRange.covers(nodeRange)) {
       Element element = _getLocalElement(node);
@@ -1119,16 +1119,16 @@
   }
 }
 
-class _HasAwaitVisitor extends GeneralizingAstVisitor {
+class _HasAwaitVisitor extends GeneralizingAstVisitor<void> {
   bool result = false;
 
   @override
-  visitAwaitExpression(AwaitExpression node) {
+  void visitAwaitExpression(AwaitExpression node) {
     result = true;
   }
 
   @override
-  visitForStatement(ForStatement node) {
+  void visitForStatement(ForStatement node) {
     if (node.awaitKeyword != null) {
       result = true;
     }
@@ -1136,14 +1136,14 @@
   }
 }
 
-class _HasReturnStatementVisitor extends RecursiveAstVisitor {
+class _HasReturnStatementVisitor extends RecursiveAstVisitor<void> {
   bool hasReturn = false;
 
   @override
-  visitBlockFunctionBody(BlockFunctionBody node) {}
+  void visitBlockFunctionBody(BlockFunctionBody node) {}
 
   @override
-  visitReturnStatement(ReturnStatement node) {
+  void visitReturnStatement(ReturnStatement node) {
     hasReturn = true;
   }
 }
@@ -1318,7 +1318,7 @@
   }
 }
 
-class _IsUsedAfterSelectionVisitor extends GeneralizingAstVisitor {
+class _IsUsedAfterSelectionVisitor extends GeneralizingAstVisitor<void> {
   final ExtractMethodRefactoringImpl ref;
   final Element element;
   bool result = false;
@@ -1326,7 +1326,7 @@
   _IsUsedAfterSelectionVisitor(this.ref, this.element);
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     Element nodeElement = node.staticElement;
     if (identical(nodeElement, element)) {
       int nodeOffset = node.offset;
@@ -1350,7 +1350,7 @@
   _Occurrence(this.range, this.isSelection);
 }
 
-class _ReturnTypeComputer extends RecursiveAstVisitor {
+class _ReturnTypeComputer extends RecursiveAstVisitor<void> {
   final TypeSystem typeSystem;
 
   DartType returnType;
@@ -1358,10 +1358,10 @@
   _ReturnTypeComputer(this.typeSystem);
 
   @override
-  visitBlockFunctionBody(BlockFunctionBody node) {}
+  void visitBlockFunctionBody(BlockFunctionBody node) {}
 
   @override
-  visitReturnStatement(ReturnStatement node) {
+  void visitReturnStatement(ReturnStatement node) {
     // prepare expression
     Expression expression = node.expression;
     if (expression == null) {
diff --git a/pkg/analysis_server/lib/src/services/refactoring/inline_method.dart b/pkg/analysis_server/lib/src/services/refactoring/inline_method.dart
index 3ace708..98f64e3 100644
--- a/pkg/analysis_server/lib/src/services/refactoring/inline_method.dart
+++ b/pkg/analysis_server/lib/src/services/refactoring/inline_method.dart
@@ -660,14 +660,14 @@
   }
 }
 
-class _ReturnsValidatorVisitor extends RecursiveAstVisitor {
+class _ReturnsValidatorVisitor extends RecursiveAstVisitor<void> {
   final RefactoringStatus result;
   int _numReturns = 0;
 
   _ReturnsValidatorVisitor(this.result);
 
   @override
-  visitReturnStatement(ReturnStatement node) {
+  void visitReturnStatement(ReturnStatement node) {
     _numReturns++;
     if (_numReturns == 2) {
       result.addError('Ambiguous return value.', newLocation_fromNode(node));
@@ -765,7 +765,7 @@
 /**
  * A visitor that fills [_SourcePart] with fields, parameters and variables.
  */
-class _VariablesVisitor extends GeneralizingAstVisitor {
+class _VariablesVisitor extends GeneralizingAstVisitor<void> {
   /**
    * The [ExecutableElement] being inlined.
    */
@@ -786,7 +786,7 @@
   _VariablesVisitor(this.methodElement, this.bodyRange, this.result);
 
   @override
-  visitNode(AstNode node) {
+  void visitNode(AstNode node) {
     SourceRange nodeRange = range.node(node);
     if (!bodyRange.intersects(nodeRange)) {
       return null;
@@ -795,7 +795,7 @@
   }
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     SourceRange nodeRange = range.node(node);
     if (bodyRange.covers(nodeRange)) {
       _addMemberQualifier(node);
@@ -805,7 +805,7 @@
   }
 
   @override
-  visitThisExpression(ThisExpression node) {
+  void visitThisExpression(ThisExpression node) {
     int offset = node.offset;
     if (bodyRange.contains(offset)) {
       result.addExplicitThisOffset(offset);
diff --git a/pkg/analysis_server/lib/src/services/refactoring/refactoring.dart b/pkg/analysis_server/lib/src/services/refactoring/refactoring.dart
index 1e016e3eb..ab909d8 100644
--- a/pkg/analysis_server/lib/src/services/refactoring/refactoring.dart
+++ b/pkg/analysis_server/lib/src/services/refactoring/refactoring.dart
@@ -87,7 +87,7 @@
    * variable. The expression used to initiate the refactoring will always be
    * replaced.
    */
-  void set extractAll(bool extractAll);
+  set extractAll(bool extractAll);
 
   /**
    * The lengths of the expressions that would be replaced by a reference to the
@@ -100,7 +100,7 @@
   /**
    * The name that the local variable should be given.
    */
-  void set name(String name);
+  set name(String name);
 
   /**
    * The proposed names for the local variable.
@@ -157,14 +157,14 @@
   /**
    * True if a getter should be created rather than a method.
    */
-  void set createGetter(bool createGetter);
+  set createGetter(bool createGetter);
 
   /**
    * True if all occurrences of the expression or statements should be replaced
    * by an invocation of the method. The expression or statements used to
    * initiate the refactoring will always be replaced.
    */
-  void set extractAll(bool extractAll);
+  set extractAll(bool extractAll);
 
   /**
    * The lengths of the expressions or statements that would be replaced by an
@@ -178,7 +178,7 @@
   /**
    * The name that the method should be given.
    */
-  void set name(String name);
+  set name(String name);
 
   /**
    * The proposed names for the method.
@@ -201,7 +201,7 @@
   /**
    * The parameters that should be defined for the method.
    */
-  void set parameters(List<RefactoringMethodParameter> parameters);
+  set parameters(List<RefactoringMethodParameter> parameters);
 
   /**
    * The proposed return type for the method.
@@ -211,7 +211,7 @@
   /**
    * The return type that should be defined for the method.
    */
-  void set returnType(String returnType);
+  set returnType(String returnType);
 
   /**
    * Validates that the [name] is a valid identifier and is appropriate for a
@@ -248,7 +248,7 @@
   /**
    * The name that the class should be given.
    */
-  void set name(String name);
+  set name(String name);
 
   /**
    * Validates that the [name] is a valid identifier and is appropriate for a
@@ -313,13 +313,13 @@
    * True if the method being inlined should be removed.
    * It is an error if this field is `true` and [inlineAll] is `false`.
    */
-  void set deleteSource(bool deleteSource);
+  set deleteSource(bool deleteSource);
 
   /**
    * True if all invocations of the method should be inlined, or false if only
    * the invocation site used to create this refactoring should be inlined.
    */
-  void set inlineAll(bool inlineAll);
+  set inlineAll(bool inlineAll);
 
   /**
    * True if the declaration of the method is selected.
@@ -352,7 +352,7 @@
   /**
    * The new file path to which the given file is being moved.
    */
-  void set newFile(String newName);
+  set newFile(String newName);
 }
 
 /**
@@ -436,14 +436,6 @@
   }
 }
 
-class RenameRefactoringElement {
-  final Element element;
-  final int offset;
-  final int length;
-
-  RenameRefactoringElement(this.element, this.offset, this.length);
-}
-
 /**
  * Abstract [Refactoring] for renaming some [Element].
  */
@@ -489,6 +481,33 @@
     return null;
   }
 
+  /**
+   * Returns the human-readable description of the kind of element being renamed
+   * (such as “class” or “function type alias”).
+   */
+  String get elementKindName;
+
+  /**
+   * Sets the new name for the [Element].
+   */
+  set newName(String newName);
+
+  /**
+   * Returns the old name of the [Element] being renamed.
+   */
+  String get oldName;
+
+  /**
+   * Validates that the [newName] is a valid identifier and is appropriate for
+   * the type of the [Element] being renamed.
+   *
+   * It does not perform all the checks (such as checking for conflicts with any
+   * existing names in any of the scopes containing the current name), as many
+   * of these checks require search engine. Use [checkFinalConditions] for this
+   * level of checking.
+   */
+  RefactoringStatus checkNewName();
+
   /// Given a node/element, finds the best element to rename (for example
   /// the class when on the `new` keyword).
   static RenameRefactoringElement getElementToRename(
@@ -523,31 +542,12 @@
 
     return RenameRefactoringElement(element, offset, length);
   }
+}
 
-  /**
-   * Returns the human-readable description of the kind of element being renamed
-   * (such as “class” or “function type alias”).
-   */
-  String get elementKindName;
+class RenameRefactoringElement {
+  final Element element;
+  final int offset;
+  final int length;
 
-  /**
-   * Sets the new name for the [Element].
-   */
-  void set newName(String newName);
-
-  /**
-   * Returns the old name of the [Element] being renamed.
-   */
-  String get oldName;
-
-  /**
-   * Validates that the [newName] is a valid identifier and is appropriate for
-   * the type of the [Element] being renamed.
-   *
-   * It does not perform all the checks (such as checking for conflicts with any
-   * existing names in any of the scopes containing the current name), as many
-   * of these checks require search engine. Use [checkFinalConditions] for this
-   * level of checking.
-   */
-  RefactoringStatus checkNewName();
+  RenameRefactoringElement(this.element, this.offset, this.length);
 }
diff --git a/pkg/analysis_server/lib/src/services/refactoring/rename_class_member.dart b/pkg/analysis_server/lib/src/services/refactoring/rename_class_member.dart
index 2ccb2d1..405acd4 100644
--- a/pkg/analysis_server/lib/src/services/refactoring/rename_class_member.dart
+++ b/pkg/analysis_server/lib/src/services/refactoring/rename_class_member.dart
@@ -356,7 +356,7 @@
   _LocalElementsCollector(this.name);
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     Element element = node.staticElement;
     if (element is LocalElement && element.name == name) {
       elements.add(element);
diff --git a/pkg/analysis_server/lib/src/services/refactoring/rename_extension_member.dart b/pkg/analysis_server/lib/src/services/refactoring/rename_extension_member.dart
index 93a587d..ffa3029 100644
--- a/pkg/analysis_server/lib/src/services/refactoring/rename_extension_member.dart
+++ b/pkg/analysis_server/lib/src/services/refactoring/rename_extension_member.dart
@@ -212,7 +212,7 @@
   _LocalElementsCollector(this.name);
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     Element element = node.staticElement;
     if (element is LocalElement && element.name == name) {
       elements.add(element);
diff --git a/pkg/analysis_server/lib/src/services/refactoring/rename_local.dart b/pkg/analysis_server/lib/src/services/refactoring/rename_local.dart
index 2646ae3..e11f8cc 100644
--- a/pkg/analysis_server/lib/src/services/refactoring/rename_local.dart
+++ b/pkg/analysis_server/lib/src/services/refactoring/rename_local.dart
@@ -107,7 +107,7 @@
   }
 }
 
-class _ConflictValidatorVisitor extends RecursiveAstVisitor {
+class _ConflictValidatorVisitor extends RecursiveAstVisitor<void> {
   final RefactoringStatus result;
   final String newName;
   final LocalElement target;
@@ -122,7 +122,7 @@
   );
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     Element nodeElement = node.staticElement;
     if (nodeElement != null && nodeElement.name == newName) {
       // Duplicate declaration.
diff --git a/pkg/analysis_server/lib/src/services/search/element_visitors.dart b/pkg/analysis_server/lib/src/services/search/element_visitors.dart
index fdb3beb..668bd2d 100644
--- a/pkg/analysis_server/lib/src/services/search/element_visitors.dart
+++ b/pkg/analysis_server/lib/src/services/search/element_visitors.dart
@@ -52,13 +52,13 @@
 /**
  * A visitor that finds the deep-most [Element] that contains the [nameOffset].
  */
-class _ElementByNameOffsetVisitor extends GeneralizingElementVisitor {
+class _ElementByNameOffsetVisitor extends GeneralizingElementVisitor<void> {
   final int nameOffset;
 
   _ElementByNameOffsetVisitor(this.nameOffset);
 
   @override
-  visitElement(Element element) {
+  void visitElement(Element element) {
     if (element.nameOffset != -1 &&
         !element.isSynthetic &&
         element.nameOffset == nameOffset) {
@@ -71,7 +71,7 @@
 /**
  * A [GeneralizingElementVisitor] adapter for [ElementProcessor].
  */
-class _ElementVisitorAdapter extends GeneralizingElementVisitor {
+class _ElementVisitorAdapter extends GeneralizingElementVisitor<void> {
   final BoolElementProcessor processor;
 
   _ElementVisitorAdapter(this.processor);
@@ -88,7 +88,7 @@
 /**
  * A [GeneralizingElementVisitor] for visiting top-level elements.
  */
-class _TopLevelElementsVisitor extends GeneralizingElementVisitor {
+class _TopLevelElementsVisitor extends GeneralizingElementVisitor<void> {
   final VoidElementProcessor processor;
 
   _TopLevelElementsVisitor(this.processor);
diff --git a/pkg/analysis_server/lib/src/utilities/flutter.dart b/pkg/analysis_server/lib/src/utilities/flutter.dart
index bbac385..fd77f0e 100644
--- a/pkg/analysis_server/lib/src/utilities/flutter.dart
+++ b/pkg/analysis_server/lib/src/utilities/flutter.dart
@@ -116,7 +116,7 @@
     int listLoc = childArg.offset;
     String childArgSrc = getNodeText(childArg);
     if (!childArgSrc.contains(eol)) {
-      _addInsertEdit(listLoc, '<Widget>[');
+      _addInsertEdit(listLoc, '[');
       _addInsertEdit(listLoc + childArg.length, ']');
     } else {
       int newlineLoc = childArgSrc.lastIndexOf(eol);
@@ -130,10 +130,10 @@
           getText(namedExp.offset, childArg.offset - namedExp.offset);
       String prefix = separator.contains(eol) ? '' : '$eol$indentNew';
       if (prefix.isEmpty) {
-        _addInsertEdit(namedExp.offset + 'child:'.length, ' <Widget>[');
+        _addInsertEdit(namedExp.offset + 'child:'.length, ' [');
         _addRemoveEdit(SourceRange(childArg.offset - 2, 2));
       } else {
-        _addInsertEdit(listLoc, '<Widget>[');
+        _addInsertEdit(listLoc, '[');
       }
       String newChildArgSrc = childArgSrc.replaceAll(
           RegExp('^$indentOld', multiLine: true), '$indentNew');
@@ -157,7 +157,7 @@
     int listLoc = childArg.offset;
     String childArgSrc = getNodeText(childArg);
     if (!childArgSrc.contains(eol)) {
-      builder.addSimpleInsertion(listLoc, '<Widget>[');
+      builder.addSimpleInsertion(listLoc, '[');
       builder.addSimpleInsertion(listLoc + childArg.length, ']');
     } else {
       int newlineLoc = childArgSrc.lastIndexOf(eol);
@@ -171,11 +171,10 @@
           getText(namedExp.offset, childArg.offset - namedExp.offset);
       String prefix = separator.contains(eol) ? '' : '$eol$indentNew';
       if (prefix.isEmpty) {
-        builder.addSimpleInsertion(
-            namedExp.offset + 'child:'.length, ' <Widget>[');
+        builder.addSimpleInsertion(namedExp.offset + 'child:'.length, ' [');
         builder.addDeletion(SourceRange(childArg.offset - 2, 2));
       } else {
-        builder.addSimpleInsertion(listLoc, '<Widget>[');
+        builder.addSimpleInsertion(listLoc, '[');
       }
       String newChildArgSrc = childArgSrc.replaceAll(
           RegExp('^$indentOld', multiLine: true), '$indentNew');
diff --git a/pkg/analysis_server/lib/starter.dart b/pkg/analysis_server/lib/starter.dart
index f6c8dd0..b4dd93b 100644
--- a/pkg/analysis_server/lib/starter.dart
+++ b/pkg/analysis_server/lib/starter.dart
@@ -22,12 +22,12 @@
    * An optional manager to handle file systems which may not always be
    * available.
    */
-  void set detachableFileSystemManager(DetachableFileSystemManager manager);
+  set detachableFileSystemManager(DetachableFileSystemManager manager);
 
   /**
    * Set the instrumentation [service] that is to be used by the analysis server.
    */
-  void set instrumentationService(InstrumentationService service);
+  set instrumentationService(InstrumentationService service);
 
   /**
    * Use the given command-line [arguments] to start this server.
diff --git a/pkg/analysis_server/pubspec.yaml b/pkg/analysis_server/pubspec.yaml
index 31b2358..c36ecd8 100644
--- a/pkg/analysis_server/pubspec.yaml
+++ b/pkg/analysis_server/pubspec.yaml
@@ -2,7 +2,7 @@
 publish_to: none
 
 environment:
-  sdk: '>=2.2.2 <3.0.0'
+  sdk: '>=2.6.0 <3.0.0'
 
 dependencies:
   analyzer: any
diff --git a/pkg/analysis_server/test/abstract_context.dart b/pkg/analysis_server/test/abstract_context.dart
index 4b10bed..8b08981 100644
--- a/pkg/analysis_server/test/abstract_context.dart
+++ b/pkg/analysis_server/test/abstract_context.dart
@@ -217,11 +217,12 @@
  * Wraps the given [_ElementVisitorFunction] into an instance of
  * [engine.GeneralizingElementVisitor].
  */
-class _ElementVisitorFunctionWrapper extends GeneralizingElementVisitor {
+class _ElementVisitorFunctionWrapper extends GeneralizingElementVisitor<void> {
   final _ElementVisitorFunction function;
   _ElementVisitorFunctionWrapper(this.function);
+
   @override
-  visitElement(Element element) {
+  void visitElement(Element element) {
     function(element);
     super.visitElement(element);
   }
diff --git a/pkg/analysis_server/test/abstract_single_unit.dart b/pkg/analysis_server/test/abstract_single_unit.dart
index df6ef6c..28ea93d 100644
--- a/pkg/analysis_server/test/abstract_single_unit.dart
+++ b/pkg/analysis_server/test/abstract_single_unit.dart
@@ -10,11 +10,11 @@
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/src/dart/ast/element_locator.dart';
-import 'package:analyzer/src/test_utilities/find_node.dart';
 import 'package:analyzer/src/dart/ast/utilities.dart';
 import 'package:analyzer/src/dart/error/hint_codes.dart';
 import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer/src/test_utilities/find_node.dart';
 import 'package:test/test.dart';
 
 import 'abstract_context.dart';
@@ -144,7 +144,7 @@
   _ElementsByNameFinder(this.name);
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     if (node.name == name && node.inDeclarationContext()) {
       elements.add(node.staticElement);
     }
diff --git a/pkg/analysis_server/test/analysis/get_errors_test.dart b/pkg/analysis_server/test/analysis/get_errors_test.dart
index a319a18..afe13b2 100644
--- a/pkg/analysis_server/test/analysis/get_errors_test.dart
+++ b/pkg/analysis_server/test/analysis/get_errors_test.dart
@@ -14,7 +14,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetErrorsTest);
   });
@@ -33,7 +33,7 @@
     createProject();
   }
 
-  test_afterAnalysisComplete() async {
+  Future<void> test_afterAnalysisComplete() async {
     addTestFile('''
 main() {
   print(42)
@@ -44,7 +44,7 @@
     expect(errors, hasLength(1));
   }
 
-  test_errorInPart() async {
+  Future<void> test_errorInPart() async {
     String libPath = join(testFolder, 'main.dart');
     String partPath = join(testFolder, 'main_part.dart');
     newFile(libPath, content: r'''
@@ -68,7 +68,7 @@
   }
 
   @failingTest
-  test_fileWithoutContext() {
+  Future<void> test_fileWithoutContext() async {
     // Broken under the new driver.
     String file = convertPath('/outside.dart');
     newFile(file, content: '''
@@ -76,10 +76,10 @@
   print(42);
 }
 ''');
-    return _checkInvalid(file);
+    await _checkInvalid(file);
   }
 
-  test_hasErrors() async {
+  Future<void> test_hasErrors() async {
     addTestFile('''
 main() {
   print(42)
@@ -96,7 +96,7 @@
     }
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = _createGetErrorsRequest('test.dart');
     var response = await waitResponse(request);
     expect(
@@ -105,7 +105,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request = _createGetErrorsRequest(convertPath('/foo/../bar/test.dart'));
     var response = await waitResponse(request);
     expect(
@@ -114,7 +114,7 @@
     );
   }
 
-  test_noErrors() async {
+  Future<void> test_noErrors() async {
     addTestFile('''
 main() {
   print(42);
@@ -124,7 +124,7 @@
     expect(errors, isEmpty);
   }
 
-  Future _checkInvalid(String file) async {
+  Future<void> _checkInvalid(String file) async {
     Request request = _createGetErrorsRequest(file);
     Response response = await serverChannel.sendRequest(request);
     expect(response.error, isNotNull);
diff --git a/pkg/analysis_server/test/analysis/get_hover_test.dart b/pkg/analysis_server/test/analysis/get_hover_test.dart
index b5319f5..619e0eb 100644
--- a/pkg/analysis_server/test/analysis/get_hover_test.dart
+++ b/pkg/analysis_server/test/analysis/get_hover_test.dart
@@ -12,7 +12,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisHoverTest);
   });
@@ -40,7 +40,7 @@
     createProject();
   }
 
-  test_class_declaration() async {
+  Future<void> test_class_declaration() async {
     addTestFile('''
 class A<E> {}
 class I1<K, V> {}
@@ -58,7 +58,7 @@
     expect(hover.propagatedType, isNull);
   }
 
-  test_class_declaration_abstract() async {
+  Future<void> test_class_declaration_abstract() async {
     addTestFile('''
 class A {}
 abstract class B extends A {}
@@ -69,7 +69,7 @@
     expect(hover.propagatedType, isNull);
   }
 
-  test_constructor_named() async {
+  Future<void> test_constructor_named() async {
     addTestFile('''
 library my.library;
 class A {
@@ -100,7 +100,7 @@
     }
   }
 
-  test_constructor_noKeyword_const() async {
+  Future<void> test_constructor_noKeyword_const() async {
     addTestFile('''
 library my.library;
 class A {
@@ -127,7 +127,7 @@
     expect(hover.parameter, isNull);
   }
 
-  test_constructor_noKeyword_new() async {
+  Future<void> test_constructor_noKeyword_new() async {
     addTestFile('''
 library my.library;
 class A {}
@@ -152,7 +152,7 @@
     expect(hover.parameter, isNull);
   }
 
-  test_constructor_synthetic() async {
+  Future<void> test_constructor_synthetic() async {
     addTestFile('''
 library my.library;
 class A {
@@ -178,7 +178,7 @@
     expect(hover.parameter, isNull);
   }
 
-  test_constructor_synthetic_withTypeArgument() async {
+  Future<void> test_constructor_synthetic_withTypeArgument() async {
     addTestFile('''
 library my.library;
 class A<T> {}
@@ -220,7 +220,7 @@
     }
   }
 
-  test_dartdoc_block() async {
+  Future<void> test_dartdoc_block() async {
     addTestFile('''
 /**
  * doc aaa
@@ -233,7 +233,7 @@
     expect(hover.dartdoc, '''doc aaa\ndoc bbb''');
   }
 
-  test_dartdoc_inherited_fromInterface() async {
+  Future<void> test_dartdoc_inherited_fromInterface() async {
     addTestFile('''
 class A {
   /// my doc
@@ -248,7 +248,7 @@
     expect(hover.dartdoc, '''my doc\n\nCopied from `A`.''');
   }
 
-  test_dartdoc_inherited_fromSuper_direct() async {
+  Future<void> test_dartdoc_inherited_fromSuper_direct() async {
     addTestFile('''
 class A {
   /// my doc
@@ -263,7 +263,7 @@
     expect(hover.dartdoc, '''my doc\n\nCopied from `A`.''');
   }
 
-  test_dartdoc_inherited_fromSuper_indirect() async {
+  Future<void> test_dartdoc_inherited_fromSuper_indirect() async {
     addTestFile('''
 class A {
   /// my doc
@@ -279,7 +279,7 @@
     expect(hover.dartdoc, '''my doc\n\nCopied from `A`.''');
   }
 
-  test_dartdoc_inherited_preferSuper() async {
+  Future<void> test_dartdoc_inherited_preferSuper() async {
     addTestFile('''
 class A {
   /// my doc
@@ -298,7 +298,7 @@
     expect(hover.dartdoc, '''my doc\n\nCopied from `A`.''');
   }
 
-  test_dartdoc_line() async {
+  Future<void> test_dartdoc_line() async {
     addTestFile('''
 /// doc aaa
 /// doc bbb
@@ -309,7 +309,7 @@
     expect(hover.dartdoc, '''doc aaa\ndoc bbb''');
   }
 
-  test_enum_declaration() async {
+  Future<void> test_enum_declaration() async {
     addTestFile('''
 enum MyEnum {AAA, BBB, CCC}
 ''');
@@ -319,7 +319,7 @@
     expect(hover.propagatedType, isNull);
   }
 
-  test_extensionDeclaration() async {
+  Future<void> test_extensionDeclaration() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     addTestFile('''
 class A {}
@@ -333,7 +333,7 @@
     expect(hover.propagatedType, isNull);
   }
 
-  test_function_topLevel_declaration() async {
+  Future<void> test_function_topLevel_declaration() async {
     addTestFile('''
 library my.library;
 /// doc aaa
@@ -356,7 +356,7 @@
     expect(hover.parameter, isNull);
   }
 
-  test_getter_synthetic() async {
+  Future<void> test_getter_synthetic() async {
     addTestFile('''
 library my.library;
 class A {
@@ -381,7 +381,7 @@
     expect(hover.propagatedType, isNull);
   }
 
-  test_integerLiteral() async {
+  Future<void> test_integerLiteral() async {
     addTestFile('''
 main() {
   foo(123);
@@ -406,7 +406,7 @@
     expect(hover.parameter, 'Object myParameter');
   }
 
-  test_integerLiteral_promoted() async {
+  Future<void> test_integerLiteral_promoted() async {
     addTestFile('''
 main() {
   foo(123);
@@ -431,7 +431,7 @@
     expect(hover.parameter, 'double myParameter');
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = AnalysisGetHoverParams('test.dart', 0).toRequest('0');
     var response = await waitResponse(request);
     expect(
@@ -440,7 +440,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request =
         AnalysisGetHoverParams(convertPath('/foo/../bar/test.dart'), 0)
             .toRequest('0');
@@ -451,7 +451,7 @@
     );
   }
 
-  test_localVariable_declaration() async {
+  Future<void> test_localVariable_declaration() async {
     addTestFile('''
 library my.library;
 class A {
@@ -475,7 +475,7 @@
     expect(hover.parameter, isNull);
   }
 
-  test_localVariable_reference_withPropagatedType() async {
+  Future<void> test_localVariable_reference_withPropagatedType() async {
     addTestFile('''
 library my.library;
 main() {
@@ -496,7 +496,7 @@
     expect(hover.propagatedType, null);
   }
 
-  test_method_declaration() async {
+  Future<void> test_method_declaration() async {
     addTestFile('''
 library my.library;
 class A {
@@ -521,7 +521,7 @@
     expect(hover.parameter, isNull);
   }
 
-  test_method_reference() async {
+  Future<void> test_method_reference() async {
     addTestFile('''
 library my.library;
 class A {
@@ -549,7 +549,7 @@
     expect(hover.parameter, isNull);
   }
 
-  test_method_reference_deprecated() async {
+  Future<void> test_method_reference_deprecated() async {
     addTestFile('''
 class A {
   @deprecated
@@ -567,7 +567,7 @@
     expect(hover.isDeprecated, isTrue);
   }
 
-  test_method_reference_genericMethod() async {
+  Future<void> test_method_reference_genericMethod() async {
     addTestFile('''
 library my.library;
 
@@ -599,7 +599,7 @@
     expect(hover.parameter, isNull);
   }
 
-  test_mixin_declaration() async {
+  Future<void> test_mixin_declaration() async {
     addTestFile('''
 mixin A on B, C implements D, E {}
 class B {}
@@ -614,7 +614,7 @@
   }
 
   @failingTest
-  test_mixin_reference() async {
+  Future<void> test_mixin_reference() async {
     addTestFile('''
 mixin A {}
 abstract class B {}
@@ -626,7 +626,7 @@
     expect(hover.propagatedType, isNull);
   }
 
-  test_noHoverInfo() async {
+  Future<void> test_noHoverInfo() async {
     addTestFile('''
 library my.library;
 main() {
@@ -637,7 +637,7 @@
     expect(hover, isNull);
   }
 
-  test_nonNullable() async {
+  Future<void> test_nonNullable() async {
     createAnalysisOptionsFile(experiments: ['non-nullable']);
     addTestFile('''
 int? f(double? a) => null;
@@ -651,7 +651,7 @@
     expect(hover.staticType, 'int? Function(double?)');
   }
 
-  test_parameter_declaration_fieldFormal() async {
+  Future<void> test_parameter_declaration_fieldFormal() async {
     addTestFile('''
 class A {
   /// The field documentation.
@@ -672,7 +672,7 @@
     expect(hover.staticType, 'int');
   }
 
-  test_parameter_declaration_required() async {
+  Future<void> test_parameter_declaration_required() async {
     addTestFile('''
 library my.library;
 class A {
@@ -696,7 +696,7 @@
     expect(hover.parameter, isNull);
   }
 
-  test_parameter_reference_fieldFormal() async {
+  Future<void> test_parameter_reference_fieldFormal() async {
     addTestFile('''
 class A {
   /// The field documentation.
diff --git a/pkg/analysis_server/test/analysis/get_navigation_test.dart b/pkg/analysis_server/test/analysis/get_navigation_test.dart
index 186b5cf..4454b8a 100644
--- a/pkg/analysis_server/test/analysis/get_navigation_test.dart
+++ b/pkg/analysis_server/test/analysis/get_navigation_test.dart
@@ -12,7 +12,7 @@
 import '../mocks.dart';
 import 'notification_navigation_test.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetNavigationTest);
   });
@@ -32,7 +32,7 @@
     createProject();
   }
 
-  test_beforeAnalysisComplete() async {
+  Future<void> test_beforeAnalysisComplete() async {
     addTestFile('''
 main() {
   var test = 0;
@@ -44,7 +44,7 @@
     assertHasTarget('test = 0');
   }
 
-  test_fieldType() async {
+  Future<void> test_fieldType() async {
     // This test mirrors test_navigation() from
     // test/integration/analysis/get_navigation_test.dart
     String text = r'''
@@ -65,7 +65,7 @@
     expect(target.startColumn, 7);
   }
 
-  test_fileDoesNotExist() async {
+  Future<void> test_fileDoesNotExist() async {
     String file = convertPath('$projectPath/doesNotExist.dart');
     Request request = _createGetNavigationRequest(file, 0, 100);
     Response response = await serverChannel.sendRequest(request);
@@ -75,7 +75,7 @@
     expect(response.result['regions'], isEmpty);
   }
 
-  test_fileOutsideOfRoot() async {
+  Future<void> test_fileOutsideOfRoot() async {
     testFile = convertPath('/outside.dart');
     addTestFile('''
 main() {
@@ -88,7 +88,7 @@
     assertHasTarget('test = 0');
   }
 
-  test_importDirective() async {
+  Future<void> test_importDirective() async {
     addTestFile('''
 import 'dart:math';
 
@@ -102,7 +102,7 @@
     expect(testTargets[0].kind, ElementKind.LIBRARY);
   }
 
-  test_importKeyword() async {
+  Future<void> test_importKeyword() async {
     addTestFile('''
 import 'dart:math';
 
@@ -116,7 +116,7 @@
     expect(testTargets[0].kind, ElementKind.LIBRARY);
   }
 
-  test_importUri() async {
+  Future<void> test_importUri() async {
     addTestFile('''
 import 'dart:math';
 
@@ -130,7 +130,7 @@
     expect(testTargets[0].kind, ElementKind.LIBRARY);
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = _createGetNavigationRequest('test.dart', 0, 0);
     var response = await waitResponse(request);
     expect(
@@ -139,7 +139,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request =
         _createGetNavigationRequest(convertPath('/foo/../bar/test.dart'), 0, 0);
     var response = await waitResponse(request);
@@ -149,7 +149,7 @@
     );
   }
 
-  test_multipleRegions() async {
+  Future<void> test_multipleRegions() async {
     addTestFile('''
 main() {
   var aaa = 1;
@@ -179,7 +179,7 @@
     assertNoRegionAt('ddd)');
   }
 
-  test_operator_index() async {
+  Future<void> test_operator_index() async {
     addTestFile('''
 class A {
   A operator [](index) => null;
@@ -225,7 +225,7 @@
     }
   }
 
-  test_zeroLength_end() async {
+  Future<void> test_zeroLength_end() async {
     addTestFile('''
 main() {
   var test = 0;
@@ -238,7 +238,7 @@
     assertHasTarget('test = 0');
   }
 
-  test_zeroLength_start() async {
+  Future<void> test_zeroLength_start() async {
     addTestFile('''
 main() {
   var test = 0;
@@ -256,7 +256,7 @@
         .toRequest(requestId);
   }
 
-  _getNavigation(String file, int offset, int length) async {
+  Future<void> _getNavigation(String file, int offset, int length) async {
     Request request = _createGetNavigationRequest(file, offset, length);
     Response response = await serverChannel.sendRequest(request);
     AnalysisGetNavigationResult result =
diff --git a/pkg/analysis_server/test/analysis/get_signature_test.dart b/pkg/analysis_server/test/analysis/get_signature_test.dart
index b990b53..c8b33f2 100644
--- a/pkg/analysis_server/test/analysis/get_signature_test.dart
+++ b/pkg/analysis_server/test/analysis/get_signature_test.dart
@@ -13,7 +13,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisSignatureTest);
   });
@@ -50,7 +50,7 @@
     createProject();
   }
 
-  test_constructor() async {
+  Future<void> test_constructor() async {
     addTestFile('''
 /// MyClass doc
 class MyClass {
@@ -71,7 +71,7 @@
         equals(ParameterInfo(ParameterKind.NAMED, 'length', 'int')));
   }
 
-  test_constructor_factory() async {
+  Future<void> test_constructor_factory() async {
     addTestFile('''
 /// MyClass doc
 class MyClass {
@@ -96,7 +96,7 @@
         equals(ParameterInfo(ParameterKind.NAMED, 'length', 'int')));
   }
 
-  test_constructor_named() async {
+  Future<void> test_constructor_named() async {
     addTestFile('''
 /// MyClass doc
 class MyClass {
@@ -117,7 +117,7 @@
         equals(ParameterInfo(ParameterKind.NAMED, 'length', 'int')));
   }
 
-  test_does_not_walk_up_over_closure() async {
+  Future<void> test_does_not_walk_up_over_closure() async {
     addTestFile('''
 one(String name, int length) {}
 main() {
@@ -132,7 +132,7 @@
         equals(RequestErrorCode.GET_SIGNATURE_UNKNOWN_FUNCTION));
   }
 
-  test_error_file_not_analyzed() async {
+  Future<void> test_error_file_not_analyzed() async {
     var result = await prepareRawSignatureAt(0,
         file: convertPath('/not/in/project.dart'));
     expect(result.error, isNotNull);
@@ -140,7 +140,7 @@
         result.error.code, equals(RequestErrorCode.GET_SIGNATURE_INVALID_FILE));
   }
 
-  test_error_function_unknown() async {
+  Future<void> test_error_function_unknown() async {
     addTestFile('''
 someFunc(/*^*/);
 ''');
@@ -150,7 +150,7 @@
         equals(RequestErrorCode.GET_SIGNATURE_UNKNOWN_FUNCTION));
   }
 
-  test_error_offset_invalid() async {
+  Future<void> test_error_offset_invalid() async {
     addTestFile('''
 a() {}
 ''');
@@ -160,7 +160,7 @@
         equals(RequestErrorCode.GET_SIGNATURE_INVALID_OFFSET));
   }
 
-  test_function_expression() async {
+  Future<void> test_function_expression() async {
     addTestFile('''
 /// f doc
 int Function(String) f(String s) => (int i) => int.parse(s) + i;
@@ -176,7 +176,7 @@
         equals(ParameterInfo(ParameterKind.REQUIRED, 's', 'String')));
   }
 
-  test_function_from_other_file() async {
+  Future<void> test_function_from_other_file() async {
     newFile('/project/bin/other.dart', content: '''
 /// one doc
 one(String name, int length) {}
@@ -200,7 +200,7 @@
         equals(ParameterInfo(ParameterKind.REQUIRED, 'length', 'int')));
   }
 
-  test_function_irrelevant_parens() async {
+  Future<void> test_function_irrelevant_parens() async {
     addTestFile('''
 /// one doc
 one(String name, int length) {}
@@ -218,7 +218,7 @@
         equals(ParameterInfo(ParameterKind.REQUIRED, 'length', 'int')));
   }
 
-  test_function_named() async {
+  Future<void> test_function_named() async {
     addTestFile('''
 /// one doc
 one(String name, {int length}) {}
@@ -236,7 +236,7 @@
         equals(ParameterInfo(ParameterKind.NAMED, 'length', 'int')));
   }
 
-  test_function_named_with_default_int() async {
+  Future<void> test_function_named_with_default_int() async {
     addTestFile('''
 /// one doc
 one(String name, {int length = 1}) {}
@@ -256,7 +256,7 @@
             defaultValue: '1')));
   }
 
-  test_function_named_with_default_string() async {
+  Future<void> test_function_named_with_default_string() async {
     addTestFile('''
 /// one doc
 one(String name, {String email = "a@b.c"}) {}
@@ -276,7 +276,7 @@
             defaultValue: '"a@b.c"')));
   }
 
-  test_function_nested_call_inner() async {
+  Future<void> test_function_nested_call_inner() async {
     // eg. foo(bar(1, 2));
     addTestFile('''
 /// one doc
@@ -295,7 +295,7 @@
         equals(ParameterInfo(ParameterKind.REQUIRED, 'two', 'String')));
   }
 
-  test_function_nested_call_outer() async {
+  Future<void> test_function_nested_call_outer() async {
     // eg. foo(bar(1, 2));
     addTestFile('''
 /// one doc
@@ -314,7 +314,7 @@
         equals(ParameterInfo(ParameterKind.REQUIRED, 'one', 'String')));
   }
 
-  test_function_no_dart_doc() async {
+  Future<void> test_function_no_dart_doc() async {
     addTestFile('''
 one(String name, int length) {}
 main() {
@@ -331,7 +331,7 @@
         equals(ParameterInfo(ParameterKind.REQUIRED, 'length', 'int')));
   }
 
-  test_function_optional() async {
+  Future<void> test_function_optional() async {
     addTestFile('''
 /// one doc
 one(String name, [int length]) {}
@@ -349,7 +349,7 @@
         equals(ParameterInfo(ParameterKind.OPTIONAL, 'length', 'int')));
   }
 
-  test_function_optional_with_default() async {
+  Future<void> test_function_optional_with_default() async {
     addTestFile('''
 /// one doc
 one(String name, [int length = 11]) {}
@@ -369,7 +369,7 @@
             defaultValue: '11')));
   }
 
-  test_function_required() async {
+  Future<void> test_function_required() async {
     addTestFile('''
 /// one doc
 one(String name, int length) {}
@@ -387,7 +387,7 @@
         equals(ParameterInfo(ParameterKind.REQUIRED, 'length', 'int')));
   }
 
-  test_function_zero_arguments() async {
+  Future<void> test_function_zero_arguments() async {
     addTestFile('''
 /// one doc
 one() {}
@@ -401,7 +401,7 @@
     expect(result.parameters, hasLength(0));
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = AnalysisGetSignatureParams('test.dart', 0).toRequest('0');
     var response = await waitResponse(request);
     expect(
@@ -410,7 +410,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request =
         AnalysisGetSignatureParams(convertPath('/foo/../bar/test.dart'), 0)
             .toRequest('0');
@@ -421,7 +421,7 @@
     );
   }
 
-  test_method_instance() async {
+  Future<void> test_method_instance() async {
     addTestFile('''
 /// MyClass doc
 class MyClass {
@@ -445,7 +445,7 @@
         equals(ParameterInfo(ParameterKind.NAMED, 'length', 'int')));
   }
 
-  test_method_static() async {
+  Future<void> test_method_static() async {
     addTestFile('''
 /// MyClass doc
 class MyClass {
diff --git a/pkg/analysis_server/test/analysis/notification_analysis_options_test.dart b/pkg/analysis_server/test/analysis/notification_analysis_options_test.dart
index cd24ef5..194e306 100644
--- a/pkg/analysis_server/test/analysis/notification_analysis_options_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_analysis_options_test.dart
@@ -15,7 +15,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(NewAnalysisOptionsFileNotificationTest);
     defineReflectiveTests(OldAnalysisOptionsFileNotificationTest);
@@ -74,7 +74,7 @@
     super.tearDown();
   }
 
-  test_error_filter() async {
+  Future<void> test_error_filter() async {
     addOptionsFile('''
 analyzer:
   errors:
@@ -101,7 +101,7 @@
     expect(testFileErrors, isEmpty);
   }
 
-  test_error_filter_removed() async {
+  Future<void> test_error_filter_removed() async {
     addOptionsFile('''
 analyzer:
   errors:
@@ -144,7 +144,7 @@
     expect(testFileErrors, hasLength(1));
   }
 
-  test_lint_options_changes() async {
+  Future<void> test_lint_options_changes() async {
     addOptionsFile('''
 linter:
   rules:
@@ -171,7 +171,7 @@
     verifyLintsEnabled(['camel_case_types']);
   }
 
-  test_lint_options_unsupported() async {
+  Future<void> test_lint_options_unsupported() async {
     addOptionsFile('''
 linter:
   rules:
@@ -189,7 +189,7 @@
 //    expect(optionsFileErrors.first.type, AnalysisErrorType.STATIC_WARNING);
   }
 
-  test_options_file_added() async {
+  Future<void> test_options_file_added() async {
     addTestFile(testSource);
     setAnalysisRoot();
 
@@ -214,7 +214,7 @@
     verifyLintsEnabled(['camel_case_types']);
   }
 
-  test_options_file_parse_error() async {
+  Future<void> test_options_file_parse_error() async {
     addOptionsFile('''
 ; #bang
 ''');
@@ -228,7 +228,7 @@
 //    expect(optionsFileErrors.first.type, AnalysisErrorType.COMPILE_TIME_ERROR);
   }
 
-  test_options_file_removed() async {
+  Future<void> test_options_file_removed() async {
     addOptionsFile('''
 linter:
   rules:
diff --git a/pkg/analysis_server/test/analysis/notification_analyzed_files_test.dart b/pkg/analysis_server/test/analysis/notification_analyzed_files_test.dart
index 7d27ab9..f8427e9 100644
--- a/pkg/analysis_server/test/analysis/notification_analyzed_files_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_analyzed_files_test.dart
@@ -13,7 +13,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationAnalyzedFilesTest);
   });
@@ -56,7 +56,7 @@
     createProject();
   }
 
-  test_afterAnalysis() async {
+  Future<void> test_afterAnalysis() async {
     addTestFile('''
 class A {}
 ''');
@@ -65,7 +65,7 @@
     assertHasFile(testFile);
   }
 
-  test_beforeAnalysis() async {
+  Future<void> test_beforeAnalysis() async {
     addTestFile('''
 class A {}
 ''');
@@ -73,7 +73,7 @@
     assertHasFile(testFile);
   }
 
-  test_beforeAnalysis_excludeYamlFiles() async {
+  Future<void> test_beforeAnalysis_excludeYamlFiles() async {
     File yamlFile = getFolder(projectPath).getChildAssumingFile('sample.yaml');
     yamlFile.writeAsStringSync('');
     addTestFile('''
@@ -84,7 +84,7 @@
     assertHasNoFile(yamlFile.path);
   }
 
-  test_insignificant_change() async {
+  Future<void> test_insignificant_change() async {
     // Making a change that doesn't affect the set of reachable files should
     // not trigger the notification to be re-sent.
     addTestFile('class A {}');
@@ -97,7 +97,7 @@
     expect(analyzedFilesReceived, isFalse);
   }
 
-  test_resubscribe_no_changes() async {
+  Future<void> test_resubscribe_no_changes() async {
     // Unsubscribing and resubscribing should cause the notification to be
     // re-sent, even if nothing has changed.
     addTestFile('class A {}');
@@ -112,7 +112,7 @@
     assertHasFile(testFile);
   }
 
-  test_significant_change() async {
+  Future<void> test_significant_change() async {
     // Making a change that *does* affect the set of reachable files should
     // trigger the notification to be re-sent.
     addTestFile('class A {}');
diff --git a/pkg/analysis_server/test/analysis/notification_closing_labels_test.dart b/pkg/analysis_server/test/analysis/notification_closing_labels_test.dart
index f234b5b..e3873d3 100644
--- a/pkg/analysis_server/test/analysis/notification_closing_labels_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_closing_labels_test.dart
@@ -12,7 +12,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationClosingLabelsTest);
   });
@@ -64,7 +64,7 @@
     addAnalysisSubscription(AnalysisService.CLOSING_LABELS, testFile);
   }
 
-  test_afterAnalysis() async {
+  Future<void> test_afterAnalysis() async {
     addTestFile(sampleCode);
     await waitForTasksFinished();
     expect(lastLabels, isNull);
@@ -74,7 +74,7 @@
     expect(lastLabels, expectedResults);
   }
 
-  test_afterUpdate() async {
+  Future<void> test_afterUpdate() async {
     addTestFile('');
     // Currently required to get notifications on updates
     setPriorityFiles([testFile]);
diff --git a/pkg/analysis_server/test/analysis/notification_errors_test.dart b/pkg/analysis_server/test/analysis/notification_errors_test.dart
index 1b4af4a..425090c 100644
--- a/pkg/analysis_server/test/analysis/notification_errors_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_errors_test.dart
@@ -15,7 +15,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(NotificationErrorsTest);
   });
@@ -48,7 +48,7 @@
     ];
   }
 
-  test_analysisOptionsFile() async {
+  Future<void> test_analysisOptionsFile() async {
     String filePath = join(projectPath, 'analysis_options.yaml');
     String analysisOptionsFile = newFile(filePath, content: '''
 linter:
@@ -72,7 +72,7 @@
     expect(error.type, AnalysisErrorType.STATIC_WARNING);
   }
 
-  test_androidManifestFile() async {
+  Future<void> test_androidManifestFile() async {
     String filePath = join(projectPath, 'android', 'AndroidManifest.xml');
     String manifestFile = newFile(filePath, content: '''
 <manifest
@@ -103,7 +103,7 @@
     expect(error.type, AnalysisErrorType.STATIC_WARNING);
   }
 
-  test_androidManifestFile_dotDirectoryIgnored() async {
+  Future<void> test_androidManifestFile_dotDirectoryIgnored() async {
     String filePath =
         join(projectPath, 'ios', '.symlinks', 'AndroidManifest.xml');
     String manifestFile = newFile(filePath, content: '''
@@ -131,7 +131,7 @@
     expect(errors, isNull);
   }
 
-  test_dotFolder_priority() async {
+  Future<void> test_dotFolder_priority() async {
     // Files inside dotFolders should not generate error notifications even
     // if they are added to priority (priority affects only priority, not what
     // is analyzed).
@@ -155,7 +155,7 @@
     expect(filesErrors[brokenFile], isNull);
   }
 
-  test_dotFolder_unopenedFile() async {
+  Future<void> test_dotFolder_unopenedFile() async {
     // Files inside dotFolders are not analyzed. Sending requests that cause
     // them to be opened (such as hovers) should not result in error notifications
     // because there is no event that would flush them and they'd remain in the
@@ -179,7 +179,7 @@
     expect(filesErrors[brokenFile], isNull);
   }
 
-  test_importError() async {
+  Future<void> test_importError() async {
     createProject();
 
     addTestFile('''
@@ -197,7 +197,7 @@
     expect(error.message, startsWith("Target of URI doesn't exist"));
   }
 
-  test_lintError() async {
+  Future<void> test_lintError() async {
     var camelCaseTypesLintName = 'camel_case_types';
 
     newFile(join(projectPath, '.analysis_options'), content: '''
@@ -232,7 +232,7 @@
     expect(error.message, lint.description);
   }
 
-  test_notInAnalysisRoot() async {
+  Future<void> test_notInAnalysisRoot() async {
     createProject();
     String otherFile = newFile('/other.dart', content: 'UnknownType V;').path;
     addTestFile('''
@@ -245,7 +245,7 @@
     expect(filesErrors[otherFile], isNull);
   }
 
-  test_overlay_dotFolder() async {
+  Future<void> test_overlay_dotFolder() async {
     // Files inside dotFolders should not generate error notifications even
     // if they have overlays added.
     createProject();
@@ -272,7 +272,7 @@
     expect(filesErrors[brokenFile], isNull);
   }
 
-  test_overlay_newFile() async {
+  Future<void> test_overlay_newFile() async {
     // Overlays added for files that don't exist on disk should still generate
     // error notifications. Removing the overlay if the file is not on disk
     // should clear the errors.
@@ -307,7 +307,7 @@
     expect(filesErrors[brokenFile], isEmpty);
   }
 
-  test_overlay_newFileSavedBeforeRemoving() async {
+  Future<void> test_overlay_newFileSavedBeforeRemoving() async {
     // Overlays added for files that don't exist on disk should still generate
     // error notifications. If the file is subsequently saved to disk before the
     // overlay is removed, the errors should not be flushed when the overlay is
@@ -347,7 +347,7 @@
     expect(filesErrors[brokenFile], hasLength(greaterThan(0)));
   }
 
-  test_ParserError() async {
+  Future<void> test_ParserError() async {
     createProject();
     addTestFile('library lib');
     await waitForTasksFinished();
@@ -363,7 +363,7 @@
     expect(error.message, isNotNull);
   }
 
-  test_pubspecFile() async {
+  Future<void> test_pubspecFile() async {
     String filePath = join(projectPath, 'pubspec.yaml');
     String pubspecFile = newFile(filePath, content: '''
 version: 1.3.2
@@ -397,7 +397,7 @@
     expect(errors, hasLength(0));
   }
 
-  test_StaticWarning() async {
+  Future<void> test_StaticWarning() async {
     createProject();
     addTestFile('''
 main() {
diff --git a/pkg/analysis_server/test/analysis/notification_folding_test.dart b/pkg/analysis_server/test/analysis/notification_folding_test.dart
index 5fe6591..892e2af 100644
--- a/pkg/analysis_server/test/analysis/notification_folding_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_folding_test.dart
@@ -13,7 +13,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationFoldingTest);
   });
@@ -62,7 +62,7 @@
     addAnalysisSubscription(AnalysisService.FOLDING, testFile);
   }
 
-  test_afterAnalysis() async {
+  Future<void> test_afterAnalysis() async {
     addTestFile(sampleCode);
     await waitForTasksFinished();
     expect(lastRegions, isNull);
@@ -72,7 +72,7 @@
     expect(lastRegions, expectedResults);
   }
 
-  test_afterUpdate() async {
+  Future<void> test_afterUpdate() async {
     addTestFile('');
     // Currently required to get notifications on updates
     setPriorityFiles([testFile]);
diff --git a/pkg/analysis_server/test/analysis/notification_highlights2_test.dart b/pkg/analysis_server/test/analysis/notification_highlights2_test.dart
index d11be59..3e2f9f8 100644
--- a/pkg/analysis_server/test/analysis/notification_highlights2_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_highlights2_test.dart
@@ -13,7 +13,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationHighlightsTest);
     defineReflectiveTests(HighlightsWithControlFlowCollectionsTest);
@@ -24,7 +24,7 @@
 
 @reflectiveTest
 class AnalysisNotificationHighlightsTest extends HighlightsTestSupport {
-  test_ANNOTATION_hasArguments() async {
+  Future<void> test_ANNOTATION_hasArguments() async {
     addTestFile('''
 class AAA {
   const AAA(a, b, c);
@@ -36,7 +36,7 @@
     assertHasRegion(HighlightRegionType.ANNOTATION, ') main', ')'.length);
   }
 
-  test_ANNOTATION_noArguments() async {
+  Future<void> test_ANNOTATION_noArguments() async {
     addTestFile('''
 const AAA = 42;
 @AAA main() {}
@@ -45,7 +45,7 @@
     assertHasRegion(HighlightRegionType.ANNOTATION, '@AAA');
   }
 
-  test_BUILT_IN_abstract() async {
+  Future<void> test_BUILT_IN_abstract() async {
     addTestFile('''
 abstract class A {};
 abstract class B = Object with A;
@@ -58,7 +58,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'abstract = 42');
   }
 
-  test_BUILT_IN_as() async {
+  Future<void> test_BUILT_IN_as() async {
     addTestFile('''
 import 'dart:math' as math;
 main() {
@@ -71,7 +71,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'as = 42');
   }
 
-  test_BUILT_IN_async() async {
+  Future<void> test_BUILT_IN_async() async {
     addTestFile('''
 fa() async {}
 fb() async* {}
@@ -85,7 +85,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'async = false');
   }
 
-  test_BUILT_IN_await() async {
+  Future<void> test_BUILT_IN_await() async {
     addTestFile('''
 main() async {
   await 42;
@@ -99,7 +99,7 @@
     assertHasRegion(HighlightRegionType.BUILT_IN, 'await for');
   }
 
-  test_BUILT_IN_deferred() async {
+  Future<void> test_BUILT_IN_deferred() async {
     addTestFile('''
 import 'dart:math' deferred as math;
 main() {
@@ -110,7 +110,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'deferred = 42');
   }
 
-  test_BUILT_IN_export() async {
+  Future<void> test_BUILT_IN_export() async {
     addTestFile('''
 export "dart:math";
 main() {
@@ -121,7 +121,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'export = 42');
   }
 
-  test_BUILT_IN_external() async {
+  Future<void> test_BUILT_IN_external() async {
     addTestFile('''
 class A {
   external A();
@@ -137,7 +137,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'external = 42');
   }
 
-  test_BUILT_IN_factory() async {
+  Future<void> test_BUILT_IN_factory() async {
     addTestFile('''
 class A {
   factory A() => null;
@@ -150,7 +150,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'factory = 42');
   }
 
-  test_BUILT_IN_get() async {
+  Future<void> test_BUILT_IN_get() async {
     addTestFile('''
 get aaa => 1;
 class A {
@@ -176,7 +176,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'hide = 42');
   }
 
-  test_BUILT_IN_implements() async {
+  Future<void> test_BUILT_IN_implements() async {
     addTestFile('''
 class A {}
 class B implements A {}
@@ -199,7 +199,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'import = 42');
   }
 
-  test_BUILT_IN_library() async {
+  Future<void> test_BUILT_IN_library() async {
     addTestFile('''
 library lib;
 main() {
@@ -225,7 +225,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'native = 42');
   }
 
-  test_BUILT_IN_on_inMixin() async {
+  Future<void> test_BUILT_IN_on_inMixin() async {
     addTestFile('''
 mixin M on N {}
 class N {}
@@ -234,7 +234,7 @@
     assertHasRegion(HighlightRegionType.BUILT_IN, 'on N');
   }
 
-  test_BUILT_IN_on_inTry() async {
+  Future<void> test_BUILT_IN_on_inTry() async {
     addTestFile('''
 main() {
   try {
@@ -247,7 +247,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'on = 42');
   }
 
-  test_BUILT_IN_operator() async {
+  Future<void> test_BUILT_IN_operator() async {
     addTestFile('''
 class A {
   operator +(x) => null;
@@ -260,7 +260,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'operator = 42');
   }
 
-  test_BUILT_IN_part() async {
+  Future<void> test_BUILT_IN_part() async {
     addTestFile('''
 part "my_part.dart";
 main() {
@@ -272,7 +272,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'part = 42');
   }
 
-  test_BUILT_IN_partOf() async {
+  Future<void> test_BUILT_IN_partOf() async {
     addTestFile('''
 part of lib;
 main() {
@@ -286,7 +286,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'of = 2');
   }
 
-  test_BUILT_IN_set() async {
+  Future<void> test_BUILT_IN_set() async {
     addTestFile('''
 set aaa(x) {}
 class A
@@ -312,7 +312,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'show = 42');
   }
 
-  test_BUILT_IN_static() async {
+  Future<void> test_BUILT_IN_static() async {
     addTestFile('''
 class A {
   static aaa;
@@ -327,7 +327,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'static = 42');
   }
 
-  test_BUILT_IN_sync() async {
+  Future<void> test_BUILT_IN_sync() async {
     addTestFile('''
 fa() sync {}
 fb() sync* {}
@@ -341,7 +341,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'sync = false');
   }
 
-  test_BUILT_IN_typedef() async {
+  Future<void> test_BUILT_IN_typedef() async {
     addTestFile('''
 typedef A();
 main() {
@@ -352,7 +352,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'typedef = 42');
   }
 
-  test_BUILT_IN_yield() async {
+  Future<void> test_BUILT_IN_yield() async {
     addTestFile('''
 main() async* {
   yield 42;
@@ -362,7 +362,7 @@
     assertHasRegion(HighlightRegionType.BUILT_IN, 'yield 42');
   }
 
-  test_BUILT_IN_yieldStar() async {
+  Future<void> test_BUILT_IN_yieldStar() async {
     addTestFile('''
 main() async* {
   yield* [];
@@ -372,7 +372,7 @@
     assertHasStringRegion(HighlightRegionType.BUILT_IN, 'yield*');
   }
 
-  test_CLASS() async {
+  Future<void> test_CLASS() async {
     addTestFile('''
 class AAA {}
 AAA aaa;
@@ -382,7 +382,7 @@
     assertHasRegion(HighlightRegionType.CLASS, 'AAA aaa');
   }
 
-  test_CLASS_notDynamic() async {
+  Future<void> test_CLASS_notDynamic() async {
     addTestFile('''
 dynamic f() {}
 ''');
@@ -390,7 +390,7 @@
     assertNoRegion(HighlightRegionType.CLASS, 'dynamic f()');
   }
 
-  test_CLASS_notVoid() async {
+  Future<void> test_CLASS_notVoid() async {
     addTestFile('''
 void f() {}
 ''');
@@ -398,7 +398,7 @@
     assertNoRegion(HighlightRegionType.CLASS, 'void f()');
   }
 
-  test_COMMENT() async {
+  Future<void> test_COMMENT() async {
     addTestFile('''
 /**
  * documentation comment
@@ -418,7 +418,7 @@
     assertHasRegion(HighlightRegionType.COMMENT_BLOCK, '/* b', 19);
   }
 
-  test_CONSTRUCTOR_explicitNew() async {
+  Future<void> test_CONSTRUCTOR_explicitNew() async {
     addTestFile('''
 class AAA<T> {
   AAA() {}
@@ -438,7 +438,7 @@
     assertHasRegion(HighlightRegionType.CONSTRUCTOR, 'name(42)');
   }
 
-  test_CONSTRUCTOR_implicitNew() async {
+  Future<void> test_CONSTRUCTOR_implicitNew() async {
     addTestFile('''
 class AAA<T> {
   AAA() {}
@@ -472,7 +472,7 @@
     assertHasStringRegion(HighlightRegionType.DIRECTIVE, "part 'part.dart';");
   }
 
-  test_DIRECTIVE_partOf() async {
+  Future<void> test_DIRECTIVE_partOf() async {
     addTestFile('''
 part of lib;
 ''');
@@ -481,7 +481,7 @@
     assertHasStringRegion(HighlightRegionType.DIRECTIVE, 'part of lib;');
   }
 
-  test_DYNAMIC_LOCAL_VARIABLE() async {
+  Future<void> test_DYNAMIC_LOCAL_VARIABLE() async {
     addTestFile('''
 f() {}
 main(p) {
@@ -495,7 +495,7 @@
     assertHasRegion(HighlightRegionType.DYNAMIC_LOCAL_VARIABLE_REFERENCE, 'v;');
   }
 
-  test_DYNAMIC_PARAMETER() async {
+  Future<void> test_DYNAMIC_PARAMETER() async {
     addTestFile('''
 main(p) {
   print(p);
@@ -506,7 +506,7 @@
     assertHasRegion(HighlightRegionType.DYNAMIC_PARAMETER_REFERENCE, 'p);');
   }
 
-  test_DYNAMIC_VARIABLE_field() async {
+  Future<void> test_DYNAMIC_VARIABLE_field() async {
     addTestFile('''
 class A {
   var f;
@@ -520,7 +520,7 @@
     assertHasRegion(HighlightRegionType.INSTANCE_SETTER_REFERENCE, 'f = 1');
   }
 
-  test_ENUM() async {
+  Future<void> test_ENUM() async {
     addTestFile('''
 enum MyEnum {A, B, C}
 MyEnum value;
@@ -530,7 +530,7 @@
     assertHasRegion(HighlightRegionType.ENUM, 'MyEnum value;');
   }
 
-  test_ENUM_CONSTANT() async {
+  Future<void> test_ENUM_CONSTANT() async {
     addTestFile('''
 enum MyEnum {AAA, BBB}
 main() {
@@ -545,7 +545,7 @@
     assertHasRegion(HighlightRegionType.ENUM_CONSTANT, 'BBB);');
   }
 
-  test_FUNCTION_TYPE_ALIAS() async {
+  Future<void> test_FUNCTION_TYPE_ALIAS() async {
     addTestFile('''
 typedef FFF(p);
 main(FFF fff) {
@@ -556,7 +556,7 @@
     assertHasRegion(HighlightRegionType.FUNCTION_TYPE_ALIAS, 'FFF fff)');
   }
 
-  test_GETTER() async {
+  Future<void> test_GETTER() async {
     addTestFile('''
 get aaa => null;
 class A {
@@ -581,7 +581,7 @@
     assertHasRegion(HighlightRegionType.STATIC_GETTER_REFERENCE, 'ccc;');
   }
 
-  test_IDENTIFIER_DEFAULT() async {
+  Future<void> test_IDENTIFIER_DEFAULT() async {
     addTestFile('''
 main() {
   aaa = 42;
@@ -595,7 +595,7 @@
     assertHasRegion(HighlightRegionType.IDENTIFIER_DEFAULT, 'CCC ccc');
   }
 
-  test_IMPORT_PREFIX() async {
+  Future<void> test_IMPORT_PREFIX() async {
     addTestFile('''
 import 'dart:math' as ma;
 main() {
@@ -607,7 +607,7 @@
     assertHasRegion(HighlightRegionType.IMPORT_PREFIX, 'ma.max');
   }
 
-  test_INSTANCE_FIELD() async {
+  Future<void> test_INSTANCE_FIELD() async {
     addTestFile('''
 class A {
   int aaa = 1;
@@ -627,7 +627,7 @@
     assertHasRegion(HighlightRegionType.INSTANCE_SETTER_REFERENCE, 'bbb = 5');
   }
 
-  test_INSTANCE_FIELD_dynamic() async {
+  Future<void> test_INSTANCE_FIELD_dynamic() async {
     addTestFile('''
 class A {
   var f;
@@ -639,7 +639,7 @@
     assertHasRegion(HighlightRegionType.INSTANCE_FIELD_REFERENCE, 'f);');
   }
 
-  test_KEYWORD() async {
+  Future<void> test_KEYWORD() async {
     addTestFile('''
 main() {
   assert(true);
@@ -703,7 +703,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'with A;');
   }
 
-  test_KEYWORD_ifElse_statement() async {
+  Future<void> test_KEYWORD_ifElse_statement() async {
     addTestFile('''
 f(a, b) {
   if (a < b) {} else {}
@@ -714,7 +714,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'else');
   }
 
-  test_KEYWORD_mixin() async {
+  Future<void> test_KEYWORD_mixin() async {
     addTestFile('''
 mixin M {}
 ''');
@@ -722,7 +722,7 @@
     assertHasRegion(HighlightRegionType.BUILT_IN, 'mixin');
   }
 
-  test_KEYWORD_void() async {
+  Future<void> test_KEYWORD_void() async {
     addTestFile('''
 void main() {
 }
@@ -731,7 +731,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'void main()');
   }
 
-  test_LABEL() async {
+  Future<void> test_LABEL() async {
     addTestFile('''
 main() {
 myLabel:
@@ -745,7 +745,7 @@
     assertHasRegion(HighlightRegionType.LABEL, 'myLabel;');
   }
 
-  test_LIBRARY_NAME_libraryDirective() async {
+  Future<void> test_LIBRARY_NAME_libraryDirective() async {
     addTestFile('''
 library my.lib.name;
 ''');
@@ -753,7 +753,7 @@
     assertHasStringRegion(HighlightRegionType.LIBRARY_NAME, 'my.lib.name');
   }
 
-  test_LIBRARY_NAME_partOfDirective() async {
+  Future<void> test_LIBRARY_NAME_partOfDirective() async {
     _addLibraryForTestPart();
     addTestFile('''
 part of my.lib.name;
@@ -762,45 +762,45 @@
     assertHasStringRegion(HighlightRegionType.LIBRARY_NAME, 'my.lib.name');
   }
 
-  test_LITERAL_BOOLEAN() async {
+  Future<void> test_LITERAL_BOOLEAN() async {
     addTestFile('var V = true;');
     await prepareHighlights();
     assertHasRegion(HighlightRegionType.LITERAL_BOOLEAN, 'true;');
   }
 
-  test_LITERAL_DOUBLE() async {
+  Future<void> test_LITERAL_DOUBLE() async {
     addTestFile('var V = 4.2;');
     await prepareHighlights();
     assertHasRegion(HighlightRegionType.LITERAL_DOUBLE, '4.2;', '4.2'.length);
   }
 
-  test_LITERAL_INTEGER() async {
+  Future<void> test_LITERAL_INTEGER() async {
     addTestFile('var V = 42;');
     await prepareHighlights();
     assertHasRegion(HighlightRegionType.LITERAL_INTEGER, '42;');
   }
 
-  test_LITERAL_LIST() async {
+  Future<void> test_LITERAL_LIST() async {
     addTestFile('var V = <int>[1, 2, 3];');
     await prepareHighlights();
     assertHasStringRegion(HighlightRegionType.LITERAL_LIST, '<int>[1, 2, 3]');
   }
 
-  test_LITERAL_MAP() async {
+  Future<void> test_LITERAL_MAP() async {
     addTestFile("var V = const <int, String>{1: 'a', 2: 'b', 3: 'c'};");
     await prepareHighlights();
     assertHasStringRegion(HighlightRegionType.LITERAL_MAP,
         "const <int, String>{1: 'a', 2: 'b', 3: 'c'}");
   }
 
-  test_LITERAL_STRING() async {
+  Future<void> test_LITERAL_STRING() async {
     addTestFile('var V = "abc";');
     await prepareHighlights();
     assertHasRegion(
         HighlightRegionType.LITERAL_STRING, '"abc";', '"abc"'.length);
   }
 
-  test_LOCAL_FUNCTION() async {
+  Future<void> test_LOCAL_FUNCTION() async {
     addTestFile('''
 main() {
   fff() {}
@@ -814,7 +814,7 @@
     assertHasRegion(HighlightRegionType.LOCAL_FUNCTION_REFERENCE, 'fff;');
   }
 
-  test_LOCAL_VARIABLE() async {
+  Future<void> test_LOCAL_VARIABLE() async {
     addTestFile('''
 main() {
   int vvv = 0;
@@ -828,7 +828,7 @@
     assertHasRegion(HighlightRegionType.LOCAL_VARIABLE_REFERENCE, 'vvv = 1;');
   }
 
-  test_METHOD() async {
+  Future<void> test_METHOD() async {
     addTestFile('''
 class A {
   aaa() {}
@@ -851,7 +851,7 @@
     assertHasRegion(HighlightRegionType.STATIC_METHOD_REFERENCE, 'bbb;');
   }
 
-  test_METHOD_bestType() async {
+  Future<void> test_METHOD_bestType() async {
     addTestFile('''
 main(p) {
   if (p is List) {
@@ -863,7 +863,7 @@
     assertHasRegion(HighlightRegionType.INSTANCE_METHOD_REFERENCE, 'add(null)');
   }
 
-  test_PARAMETER() async {
+  Future<void> test_PARAMETER() async {
     addTestFile('''
 main(int p) {
   p;
@@ -876,7 +876,7 @@
     assertHasRegion(HighlightRegionType.PARAMETER_REFERENCE, 'p = 42');
   }
 
-  test_PARAMETER_named() async {
+  Future<void> test_PARAMETER_named() async {
     addTestFile('''
 class C {
   final int aaa;
@@ -893,7 +893,7 @@
     assertHasRegion(HighlightRegionType.PARAMETER_REFERENCE, 'bbb: 2');
   }
 
-  test_SETTER_DECLARATION() async {
+  Future<void> test_SETTER_DECLARATION() async {
     addTestFile('''
 set aaa(x) {}
 class A {
@@ -915,7 +915,7 @@
     assertHasRegion(HighlightRegionType.STATIC_SETTER_REFERENCE, 'ccc = 3');
   }
 
-  test_STATIC_FIELD() async {
+  Future<void> test_STATIC_FIELD() async {
     addTestFile('''
 class A {
   static aaa = 1;
@@ -935,7 +935,7 @@
     assertHasRegion(HighlightRegionType.STATIC_SETTER_REFERENCE, 'ccc = 3');
   }
 
-  test_TOP_LEVEL_FUNCTION() async {
+  Future<void> test_TOP_LEVEL_FUNCTION() async {
     addTestFile('''
 fff(p) {}
 main() {
@@ -982,7 +982,7 @@
     assertNoRegion(HighlightRegionType.TYPE_NAME_DYNAMIC, 'dynamic = 42');
   }
 
-  test_TYPE_PARAMETER() async {
+  Future<void> test_TYPE_PARAMETER() async {
     addTestFile('''
 class A<T> {
   T fff;
@@ -996,7 +996,8 @@
     assertHasRegion(HighlightRegionType.TYPE_PARAMETER, 'T p)');
   }
 
-  test_UNRESOLVED_INSTANCE_MEMBER_REFERENCE_dynamicVarTarget() async {
+  Future<void>
+      test_UNRESOLVED_INSTANCE_MEMBER_REFERENCE_dynamicVarTarget() async {
     addTestFile('''
 main(p) {
   p.aaa;
@@ -1020,7 +1021,8 @@
     assertHasRegion(type, 'ddd()');
   }
 
-  test_UNRESOLVED_INSTANCE_MEMBER_REFERENCE_nonDynamicTarget() async {
+  Future<void>
+      test_UNRESOLVED_INSTANCE_MEMBER_REFERENCE_nonDynamicTarget() async {
     addTestFile('''
 import 'dart:math' as math;
 main(String str) {
@@ -1165,7 +1167,7 @@
   }
 
   @failingTest
-  test_KEYWORD_awaitForIn_list() async {
+  Future<void> test_KEYWORD_awaitForIn_list() async {
     addTestFile('''
 f(a) async {
   return [await for(var b in a) b];
@@ -1178,7 +1180,7 @@
   }
 
   @failingTest
-  test_KEYWORD_awaitForIn_map() async {
+  Future<void> test_KEYWORD_awaitForIn_map() async {
     addTestFile('''
 f(a) async {
   return {await for(var b in a) b : 0};
@@ -1191,7 +1193,7 @@
   }
 
   @failingTest
-  test_KEYWORD_awaitForIn_set() async {
+  Future<void> test_KEYWORD_awaitForIn_set() async {
     addTestFile('''
 f(a) async {
   return {await for(var b in a) b};
@@ -1203,7 +1205,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'in');
   }
 
-  test_KEYWORD_const_list() async {
+  Future<void> test_KEYWORD_const_list() async {
     addTestFile('''
 var v = const [];
 ''');
@@ -1211,7 +1213,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'const');
   }
 
-  test_KEYWORD_const_map() async {
+  Future<void> test_KEYWORD_const_map() async {
     addTestFile('''
 var v = const {0 : 1};
 ''');
@@ -1219,7 +1221,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'const');
   }
 
-  test_KEYWORD_const_set() async {
+  Future<void> test_KEYWORD_const_set() async {
     addTestFile('''
 var v = const {0};
 ''');
@@ -1227,7 +1229,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'const');
   }
 
-  test_KEYWORD_if_list() async {
+  Future<void> test_KEYWORD_if_list() async {
     addTestFile('''
 f(a, b) {
   return [if (a < b) 'a'];
@@ -1237,7 +1239,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'if');
   }
 
-  test_KEYWORD_if_map() async {
+  Future<void> test_KEYWORD_if_map() async {
     addTestFile('''
 f(a, b) {
   return {if (a < b) 'a' : 1};
@@ -1247,7 +1249,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'if');
   }
 
-  test_KEYWORD_if_set() async {
+  Future<void> test_KEYWORD_if_set() async {
     addTestFile('''
 f(a, b) {
   return {if (a < b) 'a'};
@@ -1257,7 +1259,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'if');
   }
 
-  test_KEYWORD_ifElse_list() async {
+  Future<void> test_KEYWORD_ifElse_list() async {
     addTestFile('''
 f(a, b) {
   return [if (a < b) 'a' else 'b'];
@@ -1268,7 +1270,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'else');
   }
 
-  test_KEYWORD_ifElse_map() async {
+  Future<void> test_KEYWORD_ifElse_map() async {
     addTestFile('''
 f(a, b) {
   return {if (a < b) 'a' : 1 else 'b' : 2};
@@ -1279,7 +1281,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'else');
   }
 
-  test_KEYWORD_ifElse_set() async {
+  Future<void> test_KEYWORD_ifElse_set() async {
     addTestFile('''
 f(a, b) {
   return {if (a < b) 'a' else 'b'};
@@ -1290,13 +1292,13 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'else');
   }
 
-  test_LITERAL_LIST() async {
+  Future<void> test_LITERAL_LIST() async {
     addTestFile('var V = <int>[1, 2, 3];');
     await prepareHighlights();
     assertHasStringRegion(HighlightRegionType.LITERAL_LIST, '<int>[1, 2, 3]');
   }
 
-  test_LITERAL_MAP() async {
+  Future<void> test_LITERAL_MAP() async {
     addTestFile("var V = const <int, String>{1: 'a', 2: 'b', 3: 'c'};");
     await prepareHighlights();
     assertHasStringRegion(HighlightRegionType.LITERAL_MAP,
@@ -1316,7 +1318,7 @@
     super.createProject(packageRoots: packageRoots);
   }
 
-  test_KEYWORD_late() async {
+  Future<void> test_KEYWORD_late() async {
     addTestFile('''
 class C {
   late int x;
@@ -1326,7 +1328,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'late');
   }
 
-  test_KEYWORD_required() async {
+  Future<void> test_KEYWORD_required() async {
     addTestFile('''
 void f({required int x}) {}
 ''');
diff --git a/pkg/analysis_server/test/analysis/notification_highlights_test.dart b/pkg/analysis_server/test/analysis/notification_highlights_test.dart
index 46dc6f6..0009354 100644
--- a/pkg/analysis_server/test/analysis/notification_highlights_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_highlights_test.dart
@@ -13,7 +13,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationHighlightsTest);
     defineReflectiveTests(HighlightsWithControlFlowCollectionsTest);
@@ -24,7 +24,7 @@
 
 @reflectiveTest
 class AnalysisNotificationHighlightsTest extends HighlightsTestSupport {
-  test_ANNOTATION_hasArguments() async {
+  Future<void> test_ANNOTATION_hasArguments() async {
     addTestFile('''
 class AAA {
   const AAA(a, b, c);
@@ -36,7 +36,7 @@
     assertHasRegion(HighlightRegionType.ANNOTATION, ') main', ')'.length);
   }
 
-  test_ANNOTATION_noArguments() async {
+  Future<void> test_ANNOTATION_noArguments() async {
     addTestFile('''
 const AAA = 42;
 @AAA main() {}
@@ -45,7 +45,7 @@
     assertHasRegion(HighlightRegionType.ANNOTATION, '@AAA');
   }
 
-  test_BUILT_IN_abstract() async {
+  Future<void> test_BUILT_IN_abstract() async {
     addTestFile('''
 abstract class A {};
 abstract class B = Object with A;
@@ -58,7 +58,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'abstract = 42');
   }
 
-  test_BUILT_IN_as() async {
+  Future<void> test_BUILT_IN_as() async {
     addTestFile('''
 import 'dart:math' as math;
 main() {
@@ -71,7 +71,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'as = 42');
   }
 
-  test_BUILT_IN_async() async {
+  Future<void> test_BUILT_IN_async() async {
     addTestFile('''
 fa() async {}
 fb() async* {}
@@ -85,7 +85,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'async = false');
   }
 
-  test_BUILT_IN_await() async {
+  Future<void> test_BUILT_IN_await() async {
     addTestFile('''
 main() async {
   await 42;
@@ -99,7 +99,7 @@
     assertHasRegion(HighlightRegionType.BUILT_IN, 'await for');
   }
 
-  test_BUILT_IN_deferred() async {
+  Future<void> test_BUILT_IN_deferred() async {
     addTestFile('''
 import 'dart:math' deferred as math;
 main() {
@@ -110,7 +110,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'deferred = 42');
   }
 
-  test_BUILT_IN_export() async {
+  Future<void> test_BUILT_IN_export() async {
     addTestFile('''
 export "dart:math";
 main() {
@@ -121,7 +121,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'export = 42');
   }
 
-  test_BUILT_IN_external() async {
+  Future<void> test_BUILT_IN_external() async {
     addTestFile('''
 class A {
   external A();
@@ -137,7 +137,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'external = 42');
   }
 
-  test_BUILT_IN_factory() async {
+  Future<void> test_BUILT_IN_factory() async {
     addTestFile('''
 class A {
   factory A() => null;
@@ -150,7 +150,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'factory = 42');
   }
 
-  test_BUILT_IN_get() async {
+  Future<void> test_BUILT_IN_get() async {
     addTestFile('''
 get aaa => 1;
 class A {
@@ -176,7 +176,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'hide = 42');
   }
 
-  test_BUILT_IN_implements() async {
+  Future<void> test_BUILT_IN_implements() async {
     addTestFile('''
 class A {}
 class B implements A {}
@@ -199,7 +199,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'import = 42');
   }
 
-  test_BUILT_IN_library() async {
+  Future<void> test_BUILT_IN_library() async {
     addTestFile('''
 library lib;
 main() {
@@ -225,7 +225,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'native = 42');
   }
 
-  test_BUILT_IN_on_inMixin() async {
+  Future<void> test_BUILT_IN_on_inMixin() async {
     addTestFile('''
 mixin M on N {}
 class N {}
@@ -234,7 +234,7 @@
     assertHasRegion(HighlightRegionType.BUILT_IN, 'on N');
   }
 
-  test_BUILT_IN_on_inTry() async {
+  Future<void> test_BUILT_IN_on_inTry() async {
     addTestFile('''
 main() {
   try {
@@ -247,7 +247,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'on = 42');
   }
 
-  test_BUILT_IN_operator() async {
+  Future<void> test_BUILT_IN_operator() async {
     addTestFile('''
 class A {
   operator +(x) => null;
@@ -260,7 +260,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'operator = 42');
   }
 
-  test_BUILT_IN_part() async {
+  Future<void> test_BUILT_IN_part() async {
     addTestFile('''
 part "my_part.dart";
 main() {
@@ -272,7 +272,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'part = 42');
   }
 
-  test_BUILT_IN_partOf() async {
+  Future<void> test_BUILT_IN_partOf() async {
     addTestFile('''
 part of lib;
 main() {
@@ -286,7 +286,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'of = 2');
   }
 
-  test_BUILT_IN_set() async {
+  Future<void> test_BUILT_IN_set() async {
     addTestFile('''
 set aaa(x) {}
 class A
@@ -312,7 +312,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'show = 42');
   }
 
-  test_BUILT_IN_static() async {
+  Future<void> test_BUILT_IN_static() async {
     addTestFile('''
 class A {
   static aaa;
@@ -327,7 +327,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'static = 42');
   }
 
-  test_BUILT_IN_sync() async {
+  Future<void> test_BUILT_IN_sync() async {
     addTestFile('''
 fa() sync {}
 fb() sync* {}
@@ -341,7 +341,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'sync = false');
   }
 
-  test_BUILT_IN_typedef() async {
+  Future<void> test_BUILT_IN_typedef() async {
     addTestFile('''
 typedef A();
 main() {
@@ -352,7 +352,7 @@
     assertNoRegion(HighlightRegionType.BUILT_IN, 'typedef = 42');
   }
 
-  test_BUILT_IN_yield() async {
+  Future<void> test_BUILT_IN_yield() async {
     addTestFile('''
 main() async* {
   yield 42;
@@ -362,7 +362,7 @@
     assertHasRegion(HighlightRegionType.BUILT_IN, 'yield 42');
   }
 
-  test_BUILT_IN_yieldStar() async {
+  Future<void> test_BUILT_IN_yieldStar() async {
     addTestFile('''
 main() async* {
   yield* [];
@@ -372,7 +372,7 @@
     assertHasStringRegion(HighlightRegionType.BUILT_IN, 'yield*');
   }
 
-  test_CLASS() async {
+  Future<void> test_CLASS() async {
     addTestFile('''
 class AAA {}
 AAA aaa;
@@ -382,7 +382,7 @@
     assertHasRegion(HighlightRegionType.CLASS, 'AAA aaa');
   }
 
-  test_CLASS_notDynamic() async {
+  Future<void> test_CLASS_notDynamic() async {
     addTestFile('''
 dynamic f() {}
 ''');
@@ -390,7 +390,7 @@
     assertNoRegion(HighlightRegionType.CLASS, 'dynamic f()');
   }
 
-  test_CLASS_notVoid() async {
+  Future<void> test_CLASS_notVoid() async {
     addTestFile('''
 void f() {}
 ''');
@@ -398,7 +398,7 @@
     assertNoRegion(HighlightRegionType.CLASS, 'void f()');
   }
 
-  test_COMMENT() async {
+  Future<void> test_COMMENT() async {
     addTestFile('''
 /**
  * documentation comment
@@ -418,7 +418,7 @@
     assertHasRegion(HighlightRegionType.COMMENT_BLOCK, '/* b', 19);
   }
 
-  test_CONSTRUCTOR_explicitNew() async {
+  Future<void> test_CONSTRUCTOR_explicitNew() async {
     addTestFile('''
 class AAA<T> {
   AAA() {}
@@ -438,7 +438,7 @@
     assertHasRegion(HighlightRegionType.CONSTRUCTOR, 'name(42)');
   }
 
-  test_CONSTRUCTOR_implicitNew() async {
+  Future<void> test_CONSTRUCTOR_implicitNew() async {
     addTestFile('''
 class AAA<T> {
   AAA() {}
@@ -472,7 +472,7 @@
     assertHasStringRegion(HighlightRegionType.DIRECTIVE, "part 'part.dart';");
   }
 
-  test_DIRECTIVE_partOf() async {
+  Future<void> test_DIRECTIVE_partOf() async {
     addTestFile('''
 part of lib;
 ''');
@@ -481,7 +481,7 @@
     assertHasStringRegion(HighlightRegionType.DIRECTIVE, 'part of lib;');
   }
 
-  test_DYNAMIC_TYPE() async {
+  Future<void> test_DYNAMIC_TYPE() async {
     addTestFile('''
 f() {}
 main(p) {
@@ -498,7 +498,7 @@
     assertNoRegion(HighlightRegionType.DYNAMIC_TYPE, 'v3 =');
   }
 
-  test_ENUM() async {
+  Future<void> test_ENUM() async {
     addTestFile('''
 enum MyEnum {A, B, C}
 MyEnum value;
@@ -508,7 +508,7 @@
     assertHasRegion(HighlightRegionType.ENUM, 'MyEnum value;');
   }
 
-  test_ENUM_CONSTANT() async {
+  Future<void> test_ENUM_CONSTANT() async {
     addTestFile('''
 enum MyEnum {AAA, BBB}
 main() {
@@ -523,7 +523,7 @@
     assertHasRegion(HighlightRegionType.ENUM_CONSTANT, 'BBB);');
   }
 
-  test_FIELD() async {
+  Future<void> test_FIELD() async {
     addTestFile('''
 class A {
   int aaa = 1;
@@ -543,7 +543,7 @@
     assertHasRegion(HighlightRegionType.FIELD, 'bbb = 5');
   }
 
-  test_FIELD_STATIC() async {
+  Future<void> test_FIELD_STATIC() async {
     addTestFile('''
 class A {
   static aaa = 1;
@@ -563,7 +563,7 @@
     assertHasRegion(HighlightRegionType.FIELD_STATIC, 'ccc = 3');
   }
 
-  test_FUNCTION() async {
+  Future<void> test_FUNCTION() async {
     addTestFile('''
 fff(p) {}
 main() {
@@ -575,7 +575,7 @@
     assertHasRegion(HighlightRegionType.FUNCTION, 'fff(42)');
   }
 
-  test_FUNCTION_TYPE_ALIAS() async {
+  Future<void> test_FUNCTION_TYPE_ALIAS() async {
     addTestFile('''
 typedef FFF(p);
 main(FFF fff) {
@@ -586,7 +586,7 @@
     assertHasRegion(HighlightRegionType.FUNCTION_TYPE_ALIAS, 'FFF fff)');
   }
 
-  test_GETTER_DECLARATION() async {
+  Future<void> test_GETTER_DECLARATION() async {
     addTestFile('''
 get aaa => null;
 class A {
@@ -604,7 +604,7 @@
     assertHasRegion(HighlightRegionType.FIELD, 'bbb;');
   }
 
-  test_IDENTIFIER_DEFAULT() async {
+  Future<void> test_IDENTIFIER_DEFAULT() async {
     addTestFile('''
 main() {
   aaa = 42;
@@ -618,7 +618,7 @@
     assertHasRegion(HighlightRegionType.IDENTIFIER_DEFAULT, 'CCC ccc');
   }
 
-  test_IMPORT_PREFIX() async {
+  Future<void> test_IMPORT_PREFIX() async {
     addTestFile('''
 import 'dart:math' as ma;
 main() {
@@ -630,7 +630,7 @@
     assertHasRegion(HighlightRegionType.IMPORT_PREFIX, 'ma.max');
   }
 
-  test_KEYWORD() async {
+  Future<void> test_KEYWORD() async {
     addTestFile('''
 main() {
   assert(true);
@@ -694,7 +694,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'with A;');
   }
 
-  test_KEYWORD_ifElse_statement() async {
+  Future<void> test_KEYWORD_ifElse_statement() async {
     addTestFile('''
 f(a, b) {
   if (a < b) {} else {}
@@ -705,7 +705,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'else');
   }
 
-  test_KEYWORD_mixin() async {
+  Future<void> test_KEYWORD_mixin() async {
     addTestFile('''
 mixin M {}
 ''');
@@ -713,7 +713,7 @@
     assertHasRegion(HighlightRegionType.BUILT_IN, 'mixin');
   }
 
-  test_KEYWORD_void() async {
+  Future<void> test_KEYWORD_void() async {
     addTestFile('''
 void main() {
 }
@@ -722,7 +722,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'void main()');
   }
 
-  test_LABEL() async {
+  Future<void> test_LABEL() async {
     addTestFile('''
 main() {
 myLabel:
@@ -736,45 +736,45 @@
     assertHasRegion(HighlightRegionType.LABEL, 'myLabel;');
   }
 
-  test_LITERAL_BOOLEAN() async {
+  Future<void> test_LITERAL_BOOLEAN() async {
     addTestFile('var V = true;');
     await prepareHighlights();
     assertHasRegion(HighlightRegionType.LITERAL_BOOLEAN, 'true;');
   }
 
-  test_LITERAL_DOUBLE() async {
+  Future<void> test_LITERAL_DOUBLE() async {
     addTestFile('var V = 4.2;');
     await prepareHighlights();
     assertHasRegion(HighlightRegionType.LITERAL_DOUBLE, '4.2;', '4.2'.length);
   }
 
-  test_LITERAL_INTEGER() async {
+  Future<void> test_LITERAL_INTEGER() async {
     addTestFile('var V = 42;');
     await prepareHighlights();
     assertHasRegion(HighlightRegionType.LITERAL_INTEGER, '42;');
   }
 
-  test_LITERAL_LIST() async {
+  Future<void> test_LITERAL_LIST() async {
     addTestFile('var V = <int>[1, 2, 3];');
     await prepareHighlights();
     assertHasStringRegion(HighlightRegionType.LITERAL_LIST, '<int>[1, 2, 3]');
   }
 
-  test_LITERAL_MAP() async {
+  Future<void> test_LITERAL_MAP() async {
     addTestFile("var V = const <int, String>{1: 'a', 2: 'b', 3: 'c'};");
     await prepareHighlights();
     assertHasStringRegion(HighlightRegionType.LITERAL_MAP,
         "const <int, String>{1: 'a', 2: 'b', 3: 'c'}");
   }
 
-  test_LITERAL_STRING() async {
+  Future<void> test_LITERAL_STRING() async {
     addTestFile('var V = "abc";');
     await prepareHighlights();
     assertHasRegion(
         HighlightRegionType.LITERAL_STRING, '"abc";', '"abc"'.length);
   }
 
-  test_LOCAL_VARIABLE() async {
+  Future<void> test_LOCAL_VARIABLE() async {
     addTestFile('''
 main() {
   int vvv = 0;
@@ -788,7 +788,7 @@
     assertHasRegion(HighlightRegionType.LOCAL_VARIABLE, 'vvv = 1;');
   }
 
-  test_METHOD() async {
+  Future<void> test_METHOD() async {
     addTestFile('''
 class A {
   aaa() {}
@@ -810,7 +810,7 @@
     assertHasRegion(HighlightRegionType.METHOD_STATIC, 'bbb;');
   }
 
-  test_METHOD_bestType() async {
+  Future<void> test_METHOD_bestType() async {
     addTestFile('''
 main(p) {
   if (p is List) {
@@ -822,7 +822,7 @@
     assertHasRegion(HighlightRegionType.METHOD, 'add(null)');
   }
 
-  test_PARAMETER() async {
+  Future<void> test_PARAMETER() async {
     addTestFile('''
 main(int p) {
   p;
@@ -835,7 +835,7 @@
     assertHasRegion(HighlightRegionType.PARAMETER, 'p = 42');
   }
 
-  test_SETTER_DECLARATION() async {
+  Future<void> test_SETTER_DECLARATION() async {
     addTestFile('''
 set aaa(x) {}
 class A {
@@ -882,7 +882,7 @@
     assertNoRegion(HighlightRegionType.TYPE_NAME_DYNAMIC, 'dynamic = 42');
   }
 
-  test_TYPE_PARAMETER() async {
+  Future<void> test_TYPE_PARAMETER() async {
     addTestFile('''
 class A<T> {
   T fff;
@@ -1014,7 +1014,7 @@
   }
 
   @failingTest
-  test_KEYWORD_awaitForIn_list() async {
+  Future<void> test_KEYWORD_awaitForIn_list() async {
     addTestFile('''
 f(a) async {
   return [await for(var b in a) b];
@@ -1027,7 +1027,7 @@
   }
 
   @failingTest
-  test_KEYWORD_awaitForIn_map() async {
+  Future<void> test_KEYWORD_awaitForIn_map() async {
     addTestFile('''
 f(a) async {
   return {await for(var b in a) b : 0};
@@ -1040,7 +1040,7 @@
   }
 
   @failingTest
-  test_KEYWORD_awaitForIn_set() async {
+  Future<void> test_KEYWORD_awaitForIn_set() async {
     addTestFile('''
 f(a) async {
   return {await for(var b in a) b};
@@ -1052,7 +1052,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'in');
   }
 
-  test_KEYWORD_const_list() async {
+  Future<void> test_KEYWORD_const_list() async {
     addTestFile('''
 var v = const [];
 ''');
@@ -1060,7 +1060,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'const');
   }
 
-  test_KEYWORD_const_map() async {
+  Future<void> test_KEYWORD_const_map() async {
     addTestFile('''
 var v = const {0 : 1};
 ''');
@@ -1068,7 +1068,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'const');
   }
 
-  test_KEYWORD_const_set() async {
+  Future<void> test_KEYWORD_const_set() async {
     addTestFile('''
 var v = const {0};
 ''');
@@ -1076,7 +1076,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'const');
   }
 
-  test_KEYWORD_if_list() async {
+  Future<void> test_KEYWORD_if_list() async {
     addTestFile('''
 f(a, b) {
   return [if (a < b) 'a'];
@@ -1086,7 +1086,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'if');
   }
 
-  test_KEYWORD_if_map() async {
+  Future<void> test_KEYWORD_if_map() async {
     addTestFile('''
 f(a, b) {
   return {if (a < b) 'a' : 1};
@@ -1096,7 +1096,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'if');
   }
 
-  test_KEYWORD_if_set() async {
+  Future<void> test_KEYWORD_if_set() async {
     addTestFile('''
 f(a, b) {
   return {if (a < b) 'a'};
@@ -1106,7 +1106,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'if');
   }
 
-  test_KEYWORD_ifElse_list() async {
+  Future<void> test_KEYWORD_ifElse_list() async {
     addTestFile('''
 f(a, b) {
   return [if (a < b) 'a' else 'b'];
@@ -1117,7 +1117,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'else');
   }
 
-  test_KEYWORD_ifElse_map() async {
+  Future<void> test_KEYWORD_ifElse_map() async {
     addTestFile('''
 f(a, b) {
   return {if (a < b) 'a' : 1 else 'b' : 2};
@@ -1128,7 +1128,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'else');
   }
 
-  test_KEYWORD_ifElse_set() async {
+  Future<void> test_KEYWORD_ifElse_set() async {
     addTestFile('''
 f(a, b) {
   return {if (a < b) 'a' else 'b'};
@@ -1139,13 +1139,13 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'else');
   }
 
-  test_LITERAL_LIST_withControlFlow() async {
+  Future<void> test_LITERAL_LIST_withControlFlow() async {
     addTestFile('var V = <int>[1, 2, 3];');
     await prepareHighlights();
     assertHasStringRegion(HighlightRegionType.LITERAL_LIST, '<int>[1, 2, 3]');
   }
 
-  test_LITERAL_MAP_withControlFlow() async {
+  Future<void> test_LITERAL_MAP_withControlFlow() async {
     addTestFile("var V = const <int, String>{1: 'a', 2: 'b', 3: 'c'};");
     await prepareHighlights();
     assertHasStringRegion(HighlightRegionType.LITERAL_MAP,
@@ -1165,7 +1165,7 @@
     super.createProject(packageRoots: packageRoots);
   }
 
-  test_KEYWORD_late() async {
+  Future<void> test_KEYWORD_late() async {
     addTestFile('''
 class C {
   late int x;
@@ -1175,7 +1175,7 @@
     assertHasRegion(HighlightRegionType.KEYWORD, 'late');
   }
 
-  test_KEYWORD_required() async {
+  Future<void> test_KEYWORD_required() async {
     addTestFile('''
 void f({required int x}) {}
 ''');
diff --git a/pkg/analysis_server/test/analysis/notification_implemented_test.dart b/pkg/analysis_server/test/analysis/notification_implemented_test.dart
index 7b50e07..fb1b6c5 100644
--- a/pkg/analysis_server/test/analysis/notification_implemented_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_implemented_test.dart
@@ -13,7 +13,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationImplementedTest);
   });
@@ -122,7 +122,7 @@
     addAnalysisSubscription(AnalysisService.IMPLEMENTED, testFile);
   }
 
-  test_afterAnalysis() async {
+  Future<void> test_afterAnalysis() async {
     addTestFile('''
 class A {}
 class B extends A {}
@@ -132,7 +132,7 @@
     assertHasImplementedClass('A {');
   }
 
-  test_afterIncrementalResolution() async {
+  Future<void> test_afterIncrementalResolution() async {
     subscribeForImplemented();
     addTestFile('''
 class A {}
@@ -151,7 +151,7 @@
     assertHasImplementedClass('A  {');
   }
 
-  test_class_extended() async {
+  Future<void> test_class_extended() async {
     addTestFile('''
 class A {}
 class B extends A {}
@@ -160,7 +160,7 @@
     assertHasImplementedClass('A {');
   }
 
-  test_class_implemented() async {
+  Future<void> test_class_implemented() async {
     addTestFile('''
 class A {}
 class B implements A {}
@@ -169,7 +169,7 @@
     assertHasImplementedClass('A {');
   }
 
-  test_class_inMixin() async {
+  Future<void> test_class_inMixin() async {
     addTestFile('''
 class A {} // ref
 class B {} // ref
@@ -184,7 +184,7 @@
     assertHasImplementedClass('D {} // ref');
   }
 
-  test_class_mixed() async {
+  Future<void> test_class_mixed() async {
     addTestFile('''
 class A {}
 class B = Object with A;
@@ -193,7 +193,7 @@
     assertHasImplementedClass('A {');
   }
 
-  test_field_withField() async {
+  Future<void> test_field_withField() async {
     addTestFile('''
 class A {
   int f; // A
@@ -206,7 +206,7 @@
     assertHasImplementedMember('f; // A');
   }
 
-  test_field_withGetter() async {
+  Future<void> test_field_withGetter() async {
     addTestFile('''
 class A {
   int f; // A
@@ -219,7 +219,7 @@
     assertHasImplementedMember('f; // A');
   }
 
-  test_field_withSetter() async {
+  Future<void> test_field_withSetter() async {
     addTestFile('''
 class A {
   int f; // A
@@ -232,7 +232,7 @@
     assertHasImplementedMember('f; // A');
   }
 
-  test_getter_withField() async {
+  Future<void> test_getter_withField() async {
     addTestFile('''
 class A {
   get f => null; // A
@@ -245,7 +245,7 @@
     assertHasImplementedMember('f => null; // A');
   }
 
-  test_getter_withGetter() async {
+  Future<void> test_getter_withGetter() async {
     addTestFile('''
 class A {
   get f => null; // A
@@ -258,7 +258,7 @@
     assertHasImplementedMember('f => null; // A');
   }
 
-  test_method_withMethod() async {
+  Future<void> test_method_withMethod() async {
     addTestFile('''
 class A {
   m() {} // A
@@ -272,7 +272,7 @@
     assertNoImplementedMember('m() {} // B');
   }
 
-  test_method_withMethod_indirectSubclass() async {
+  Future<void> test_method_withMethod_indirectSubclass() async {
     addTestFile('''
 class A {
   m() {} // A
@@ -287,7 +287,7 @@
     assertHasImplementedMember('m() {} // A');
   }
 
-  test_method_withMethod_private_differentLib() async {
+  Future<void> test_method_withMethod_private_differentLib() async {
     newFile(join(testFolder, 'lib.dart'), content: r'''
 import 'test.dart';
 class B extends A {
@@ -303,7 +303,7 @@
     assertNoImplementedMember('_m() {} // A');
   }
 
-  test_method_withMethod_private_sameLibrary() async {
+  Future<void> test_method_withMethod_private_sameLibrary() async {
     addTestFile('''
 class A {
   _m() {} // A
@@ -317,7 +317,7 @@
     assertNoImplementedMember('_m() {} // B');
   }
 
-  test_method_withMethod_wasAbstract() async {
+  Future<void> test_method_withMethod_wasAbstract() async {
     addTestFile('''
 abstract class A {
   m(); // A
@@ -330,7 +330,7 @@
     assertHasImplementedMember('m(); // A');
   }
 
-  test_mixin_implemented() async {
+  Future<void> test_mixin_implemented() async {
     addTestFile('''
 mixin M { // ref
   void foo() {} // ref
@@ -347,7 +347,7 @@
     assertNoImplementedMember('bar() {} // ref');
   }
 
-  test_mixin_mixed() async {
+  Future<void> test_mixin_mixed() async {
     addTestFile('''
 mixin M { // ref
   void foo() {} // ref
@@ -364,7 +364,7 @@
     assertNoImplementedMember('bar() {} // ref');
   }
 
-  test_setter_withField() async {
+  Future<void> test_setter_withField() async {
     addTestFile('''
 class A {
   set f(_) {} // A
@@ -377,7 +377,7 @@
     assertHasImplementedMember('f(_) {} // A');
   }
 
-  test_setter_withSetter() async {
+  Future<void> test_setter_withSetter() async {
     addTestFile('''
 class A {
   set f(_) {} // A
@@ -390,7 +390,7 @@
     assertHasImplementedMember('f(_) {} // A');
   }
 
-  test_static_field_instanceStatic() async {
+  Future<void> test_static_field_instanceStatic() async {
     addTestFile('''
 class A {
   int F = 0;
@@ -403,7 +403,7 @@
     assertNoImplementedMember('F = 0');
   }
 
-  test_static_field_staticInstance() async {
+  Future<void> test_static_field_staticInstance() async {
     addTestFile('''
 class A {
   static int F = 0;
@@ -416,7 +416,7 @@
     assertNoImplementedMember('F = 0');
   }
 
-  test_static_field_staticStatic() async {
+  Future<void> test_static_field_staticStatic() async {
     addTestFile('''
 class A {
   static int F = 0;
@@ -429,7 +429,7 @@
     assertNoImplementedMember('F = 0');
   }
 
-  test_static_method_instanceStatic() async {
+  Future<void> test_static_method_instanceStatic() async {
     addTestFile('''
 class A {
   int m() => 0;
@@ -442,7 +442,7 @@
     assertNoImplementedMember('m() => 0');
   }
 
-  test_static_method_staticInstance() async {
+  Future<void> test_static_method_staticInstance() async {
     addTestFile('''
 class A {
   static int m() => 0;
@@ -455,7 +455,7 @@
     assertNoImplementedMember('m() => 0');
   }
 
-  test_static_method_staticStatic() async {
+  Future<void> test_static_method_staticStatic() async {
     addTestFile('''
 class A {
   static int m() => 0;
diff --git a/pkg/analysis_server/test/analysis/notification_navigation_test.dart b/pkg/analysis_server/test/analysis/notification_navigation_test.dart
index 6ddeec3..a76f198 100644
--- a/pkg/analysis_server/test/analysis/notification_navigation_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_navigation_test.dart
@@ -13,7 +13,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationNavigationTest);
   });
@@ -206,7 +206,7 @@
     createProject();
   }
 
-  test_afterAnalysis() async {
+  Future<void> test_afterAnalysis() async {
     addTestFile('''
 class AAA {}
 AAA aaa;
@@ -216,7 +216,7 @@
     assertHasRegionTarget('AAA aaa;', 'AAA {}');
   }
 
-  test_annotationConstructor_implicit() async {
+  Future<void> test_annotationConstructor_implicit() async {
     addTestFile('''
 class A {
 }
@@ -229,7 +229,7 @@
     assertHasTarget('A {');
   }
 
-  test_annotationConstructor_importPrefix() async {
+  Future<void> test_annotationConstructor_importPrefix() async {
     newFile(join(testFolder, 'my_annotation.dart'), content: r'''
 library an;
 class MyAnnotation {
@@ -258,7 +258,7 @@
     }
   }
 
-  test_annotationConstructor_named() async {
+  Future<void> test_annotationConstructor_named() async {
     addTestFile('''
 class A {
   const A.named(p);
@@ -278,7 +278,7 @@
     }
   }
 
-  test_annotationConstructor_unnamed() async {
+  Future<void> test_annotationConstructor_unnamed() async {
     addTestFile('''
 class A {
   const A();
@@ -292,7 +292,7 @@
     assertHasTarget('A();', 0);
   }
 
-  test_annotationField() async {
+  Future<void> test_annotationField() async {
     addTestFile('''
 const myan = new Object();
 @myan // ref
@@ -304,7 +304,7 @@
     assertHasTarget('myan = new Object();');
   }
 
-  test_annotationField_importPrefix() async {
+  Future<void> test_annotationField_importPrefix() async {
     newFile(join(testFolder, 'mayn.dart'), content: r'''
 library an;
 const myan = new Object();
@@ -319,7 +319,7 @@
     assertHasRegion('myan // ref');
   }
 
-  test_class_fromSDK() async {
+  Future<void> test_class_fromSDK() async {
     addTestFile('''
 int V = 42;
 ''');
@@ -331,7 +331,7 @@
     expect(target.startColumn, greaterThan(0));
   }
 
-  test_constructor_named() async {
+  Future<void> test_constructor_named() async {
     addTestFile('''
 class A {
   A.named(BBB p) {}
@@ -349,7 +349,7 @@
     assertHasRegionTarget('BBB p', 'BBB {}');
   }
 
-  test_constructor_unnamed() async {
+  Future<void> test_constructor_unnamed() async {
     addTestFile('''
 class A {
   A(BBB p) {}
@@ -364,7 +364,7 @@
     assertHasRegionTarget('BBB p', 'BBB {}');
   }
 
-  test_extension_on() async {
+  Future<void> test_extension_on() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     addTestFile('''
 class C //1
@@ -377,7 +377,7 @@
     assertHasTarget('C //1');
   }
 
-  test_factoryRedirectingConstructor_implicit() async {
+  Future<void> test_factoryRedirectingConstructor_implicit() async {
     addTestFile('''
 class A {
   factory A() = B;
@@ -390,7 +390,8 @@
     assertHasTarget('B {');
   }
 
-  test_factoryRedirectingConstructor_implicit_withTypeArgument() async {
+  Future<void>
+      test_factoryRedirectingConstructor_implicit_withTypeArgument() async {
     addTestFile('''
 class A {}
 class B {
@@ -409,7 +410,7 @@
     }
   }
 
-  test_factoryRedirectingConstructor_named() async {
+  Future<void> test_factoryRedirectingConstructor_named() async {
     addTestFile('''
 class A {
   factory A() = B.named;
@@ -429,7 +430,8 @@
     }
   }
 
-  test_factoryRedirectingConstructor_named_withTypeArgument() async {
+  Future<void>
+      test_factoryRedirectingConstructor_named_withTypeArgument() async {
     addTestFile('''
 class A {}
 class B {
@@ -454,7 +456,7 @@
     }
   }
 
-  test_factoryRedirectingConstructor_unnamed() async {
+  Future<void> test_factoryRedirectingConstructor_unnamed() async {
     addTestFile('''
 class A {
   factory A() = B;
@@ -468,7 +470,8 @@
     assertHasTarget('B() {}', 0);
   }
 
-  test_factoryRedirectingConstructor_unnamed_withTypeArgument() async {
+  Future<void>
+      test_factoryRedirectingConstructor_unnamed_withTypeArgument() async {
     addTestFile('''
 class A {}
 class B {
@@ -489,7 +492,7 @@
     }
   }
 
-  test_factoryRedirectingConstructor_unresolved() async {
+  Future<void> test_factoryRedirectingConstructor_unresolved() async {
     addTestFile('''
 class A {
   factory A() = B;
@@ -499,7 +502,7 @@
     // don't check regions, but there should be no exceptions
   }
 
-  test_fieldFormalParameter() async {
+  Future<void> test_fieldFormalParameter() async {
     addTestFile('''
 class AAA {
   int fff = 123;
@@ -510,7 +513,7 @@
     assertHasRegionTarget('fff);', 'fff = 123');
   }
 
-  test_fieldFormalParameter_unresolved() async {
+  Future<void> test_fieldFormalParameter_unresolved() async {
     addTestFile('''
 class AAA {
   AAA(this.fff);
@@ -520,7 +523,7 @@
     assertNoRegion('fff);', 3);
   }
 
-  test_identifier_resolved() async {
+  Future<void> test_identifier_resolved() async {
     addTestFile('''
 class AAA {}
 main() {
@@ -534,7 +537,7 @@
     assertHasRegionTarget('main() {', 'main() {');
   }
 
-  test_identifier_unresolved() async {
+  Future<void> test_identifier_unresolved() async {
     addTestFile('''
 main() {
   print(vvv);
@@ -544,7 +547,7 @@
     assertNoRegionString('vvv');
   }
 
-  test_identifier_whenStrayImportDirective() async {
+  Future<void> test_identifier_whenStrayImportDirective() async {
     addTestFile('''
 main() {
   int aaa = 42;
@@ -556,7 +559,7 @@
     assertHasRegionTarget('aaa);', 'aaa = 42');
   }
 
-  test_inComment() async {
+  Future<void> test_inComment() async {
     addTestFile('''
 class FirstClass {}
 class SecondClass {
@@ -573,7 +576,7 @@
     assertHasRegionTarget('FirstClass(', 'FirstClass {');
   }
 
-  test_instanceCreation_implicit() async {
+  Future<void> test_instanceCreation_implicit() async {
     addTestFile('''
 class A {
 }
@@ -586,7 +589,7 @@
     assertHasTarget('A {');
   }
 
-  test_instanceCreation_implicit_withTypeArgument() async {
+  Future<void> test_instanceCreation_implicit_withTypeArgument() async {
     addTestFile('''
 class A {}
 class B<T> {}
@@ -605,7 +608,7 @@
     }
   }
 
-  test_instanceCreation_named() async {
+  Future<void> test_instanceCreation_named() async {
     addTestFile('''
 class A {
   A.named() {}
@@ -625,7 +628,7 @@
     }
   }
 
-  test_instanceCreation_named_withTypeArgument() async {
+  Future<void> test_instanceCreation_named_withTypeArgument() async {
     addTestFile('''
 class A {}
 class B<T> {
@@ -650,7 +653,7 @@
     }
   }
 
-  test_instanceCreation_unnamed() async {
+  Future<void> test_instanceCreation_unnamed() async {
     addTestFile('''
 class A {
   A() {}
@@ -664,7 +667,7 @@
     assertHasTarget('A() {}', 0);
   }
 
-  test_instanceCreation_unnamed_withTypeArgument() async {
+  Future<void> test_instanceCreation_unnamed_withTypeArgument() async {
     addTestFile('''
 class A {}
 class B<T> {
@@ -685,7 +688,7 @@
     }
   }
 
-  test_instanceCreation_withImportPrefix_named() async {
+  Future<void> test_instanceCreation_withImportPrefix_named() async {
     addTestFile('''
 import 'dart:async' as ppp;
 main() {
@@ -701,7 +704,7 @@
     assertHasRegion('value(42)');
   }
 
-  test_library() async {
+  Future<void> test_library() async {
     addTestFile('''
 library my.lib;
 ''');
@@ -724,7 +727,7 @@
     assertNoRegionAt('TEST');
   }
 
-  test_operator_arithmetic() async {
+  Future<void> test_operator_arithmetic() async {
     addTestFile('''
 class A {
   A operator +(other) => null;
@@ -762,7 +765,7 @@
     assertHasOperatorRegion('/= 6', 2, '/(other) => null', 1);
   }
 
-  test_operator_index() async {
+  Future<void> test_operator_index() async {
     addTestFile('''
 class A {
   A operator +(other) => null;
@@ -788,7 +791,7 @@
     assertHasOperatorRegion('+= 2;', 2, '+(other)', 1);
   }
 
-  test_partOf() async {
+  Future<void> test_partOf() async {
     var libCode = 'library lib; part "test.dart";';
     var libFile = newFile('$projectPath/bin/lib.dart', content: libCode).path;
     addTestFile('part of lib;');
@@ -797,7 +800,7 @@
     assertHasFileTarget(libFile, libCode.indexOf('lib;'), 'lib'.length);
   }
 
-  test_redirectingConstructorInvocation() async {
+  Future<void> test_redirectingConstructorInvocation() async {
     addTestFile('''
 class A {
   A() {}
@@ -820,7 +823,7 @@
     }
   }
 
-  test_string_export() async {
+  Future<void> test_string_export() async {
     var libCode = 'library lib;';
     var libFile = newFile('$projectPath/bin/lib.dart', content: libCode).path;
     addTestFile('export "lib.dart";');
@@ -835,7 +838,7 @@
     assertNoRegionString('"no.dart"');
   }
 
-  test_string_import() async {
+  Future<void> test_string_import() async {
     var libCode = 'library lib;';
     var libFile = newFile('$projectPath/bin/lib.dart', content: libCode).path;
     addTestFile('import "lib.dart";');
@@ -844,7 +847,7 @@
     assertHasFileTarget(libFile, libCode.indexOf('lib;'), 'lib'.length);
   }
 
-  test_string_import_noUri() async {
+  Future<void> test_string_import_noUri() async {
     addTestFile('import ;');
     await prepareNavigation();
     assertNoRegionAt('import ;');
@@ -856,7 +859,7 @@
     assertNoRegionString('"no.dart"');
   }
 
-  test_string_part() async {
+  Future<void> test_string_part() async {
     var unitCode = 'part of lib;  f() {}';
     var unitFile =
         newFile('$projectPath/bin/test_unit.dart', content: unitCode).path;
@@ -869,7 +872,7 @@
     assertHasFileTarget(unitFile, 0, 0);
   }
 
-  test_string_part_invalidUri() async {
+  Future<void> test_string_part_invalidUri() async {
     addTestFile('''
 part ":[invalid]";
 ''');
@@ -886,7 +889,7 @@
     assertNoRegionString('"test_unit.dart"');
   }
 
-  test_superConstructorInvocation() async {
+  Future<void> test_superConstructorInvocation() async {
     addTestFile('''
 class A {
   A() {}
@@ -912,7 +915,7 @@
     }
   }
 
-  test_superConstructorInvocation_synthetic() async {
+  Future<void> test_superConstructorInvocation_synthetic() async {
     addTestFile('''
 class A {
 }
@@ -925,7 +928,7 @@
     assertHasTarget('A {');
   }
 
-  test_targetElement() async {
+  Future<void> test_targetElement() async {
     addTestFile('''
 class AAA {}
 main() {
@@ -937,7 +940,7 @@
     expect(testTarget.kind, ElementKind.CLASS);
   }
 
-  test_type_dynamic() async {
+  Future<void> test_type_dynamic() async {
     addTestFile('''
 main() {
   dynamic v = null;
@@ -947,7 +950,7 @@
     assertNoRegionAt('dynamic');
   }
 
-  test_type_void() async {
+  Future<void> test_type_void() async {
     addTestFile('''
 void main() {
 }
@@ -956,7 +959,7 @@
     assertNoRegionAt('void');
   }
 
-  test_var_declaredVariable() async {
+  Future<void> test_var_declaredVariable() async {
     addTestFile('''
 class C {}
 f(List<C> items) {
@@ -968,7 +971,7 @@
     expect(testTarget.kind, ElementKind.CLASS);
   }
 
-  test_var_localVariable_multiple_inferred_different() async {
+  Future<void> test_var_localVariable_multiple_inferred_different() async {
     addTestFile('''
 class A {}
 class B {}
@@ -980,7 +983,7 @@
     assertNoRegionAt('var');
   }
 
-  test_var_localVariable_multiple_inferred_same() async {
+  Future<void> test_var_localVariable_multiple_inferred_same() async {
     addTestFile('''
 class C {}
 void f() {
@@ -992,7 +995,7 @@
     expect(testTarget.kind, ElementKind.CLASS);
   }
 
-  test_var_localVariable_single_inferred() async {
+  Future<void> test_var_localVariable_single_inferred() async {
     addTestFile('''
 class C {}
 f() {
@@ -1004,7 +1007,7 @@
     expect(testTarget.kind, ElementKind.CLASS);
   }
 
-  test_var_localVariable_single_notInferred() async {
+  Future<void> test_var_localVariable_single_notInferred() async {
     addTestFile('''
 f() {
   var x;
@@ -1014,7 +1017,7 @@
     assertNoRegionAt('var');
   }
 
-  test_var_topLevelVariable_multiple_inferred_different() async {
+  Future<void> test_var_topLevelVariable_multiple_inferred_different() async {
     addTestFile('''
 class A {}
 class B {}
@@ -1024,7 +1027,7 @@
     assertNoRegionAt('var');
   }
 
-  test_var_topLevelVariable_multiple_inferred_same() async {
+  Future<void> test_var_topLevelVariable_multiple_inferred_same() async {
     addTestFile('''
 class C {}
 var a = new C(), b = new C();
@@ -1034,7 +1037,7 @@
     expect(testTarget.kind, ElementKind.CLASS);
   }
 
-  test_var_topLevelVariable_single_inferred() async {
+  Future<void> test_var_topLevelVariable_single_inferred() async {
     addTestFile('''
 class C {}
 var c = new C();
@@ -1044,7 +1047,7 @@
     expect(testTarget.kind, ElementKind.CLASS);
   }
 
-  test_var_topLevelVariable_single_notInferred() async {
+  Future<void> test_var_topLevelVariable_single_notInferred() async {
     addTestFile('''
 var x;
 ''');
diff --git a/pkg/analysis_server/test/analysis/notification_occurrences_test.dart b/pkg/analysis_server/test/analysis/notification_occurrences_test.dart
index c47b466..ffa0f8b 100644
--- a/pkg/analysis_server/test/analysis/notification_occurrences_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_occurrences_test.dart
@@ -13,7 +13,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationOccurrencesTest);
   });
@@ -99,7 +99,7 @@
     createProject();
   }
 
-  test_afterAnalysis() async {
+  Future<void> test_afterAnalysis() async {
     addTestFile('''
 main() {
   var vvv = 42;
@@ -115,7 +115,7 @@
     assertHasOffset('vvv);');
   }
 
-  test_field() async {
+  Future<void> test_field() async {
     addTestFile('''
 class A {
   int fff;
@@ -134,7 +134,7 @@
     assertHasOffset('fff); // print');
   }
 
-  test_field_unresolved() async {
+  Future<void> test_field_unresolved() async {
     addTestFile('''
 class A {
   A(this.noSuchField);
@@ -144,7 +144,7 @@
     await prepareOccurrences();
   }
 
-  test_localVariable() async {
+  Future<void> test_localVariable() async {
     addTestFile('''
 main() {
   var vvv = 42;
@@ -161,7 +161,7 @@
     assertHasOffset('vvv);');
   }
 
-  test_memberField() async {
+  Future<void> test_memberField() async {
     addTestFile('''
 class A<T> {
   T fff;
@@ -180,7 +180,7 @@
     assertHasOffset('fff = 2;');
   }
 
-  test_memberMethod() async {
+  Future<void> test_memberMethod() async {
     addTestFile('''
 class A<T> {
   T mmm() {}
@@ -199,7 +199,7 @@
     assertHasOffset('mmm(); // b');
   }
 
-  test_topLevelVariable() async {
+  Future<void> test_topLevelVariable() async {
     addTestFile('''
 var VVV = 1;
 main() {
@@ -214,7 +214,7 @@
     assertHasOffset('VVV);');
   }
 
-  test_type_class() async {
+  Future<void> test_type_class() async {
     addTestFile('''
 main() {
   int a = 1;
@@ -233,7 +233,7 @@
     assertHasOffset('int VVV');
   }
 
-  test_type_dynamic() async {
+  Future<void> test_type_dynamic() async {
     addTestFile('''
 main() {
   dynamic a = 1;
@@ -246,7 +246,7 @@
     findRegion(offset, 'dynamic'.length, false);
   }
 
-  test_type_void() async {
+  Future<void> test_type_void() async {
     addTestFile('''
 void main() {
 }
diff --git a/pkg/analysis_server/test/analysis/notification_outline_test.dart b/pkg/analysis_server/test/analysis/notification_outline_test.dart
index 3886d4d..35df343 100644
--- a/pkg/analysis_server/test/analysis/notification_outline_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_outline_test.dart
@@ -13,7 +13,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationOutlineTest);
   });
@@ -59,7 +59,7 @@
     createProject();
   }
 
-  test_afterAnalysis() async {
+  Future<void> test_afterAnalysis() async {
     addTestFile('''
 class AAA {
 }
@@ -74,7 +74,7 @@
     expect(outlines, hasLength(2));
   }
 
-  test_libraryName_hasLibraryDirective() async {
+  Future<void> test_libraryName_hasLibraryDirective() async {
     addTestFile('''
 library my.lib;
 ''');
@@ -104,7 +104,7 @@
     expect(libraryName, 'my.lib');
   }
 
-  test_libraryName_noDirectives() async {
+  Future<void> test_libraryName_noDirectives() async {
     addTestFile('''
 class A {}
 ''');
@@ -113,7 +113,7 @@
     expect(libraryName, isNull);
   }
 
-  test_subscribeWhenCachedResultIsAvailable() async {
+  Future<void> test_subscribeWhenCachedResultIsAvailable() async {
     // https://github.com/dart-lang/sdk/issues/30238
     // We need to get notifications for new subscriptions even when the
     // file is a priority file, and there is a cached result available.
diff --git a/pkg/analysis_server/test/analysis/notification_overrides_test.dart b/pkg/analysis_server/test/analysis/notification_overrides_test.dart
index 0f276c5..29e5b5f 100644
--- a/pkg/analysis_server/test/analysis/notification_overrides_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_overrides_test.dart
@@ -12,7 +12,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationOverridesTest);
   });
@@ -139,7 +139,7 @@
     createProject();
   }
 
-  test_afterAnalysis() async {
+  Future<void> test_afterAnalysis() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -155,7 +155,7 @@
     assertHasInterfaceMember('m() {} // in A');
   }
 
-  test_BAD_fieldByMethod() async {
+  Future<void> test_BAD_fieldByMethod() async {
     addTestFile('''
 class A {
   int fff; // in A
@@ -168,7 +168,7 @@
     assertNoOverride('fff() {} // in B');
   }
 
-  test_BAD_getterByMethod() async {
+  Future<void> test_BAD_getterByMethod() async {
     addTestFile('''
 class A {
   get fff => null;
@@ -181,7 +181,7 @@
     assertNoOverride('fff() {}');
   }
 
-  test_BAD_getterBySetter() async {
+  Future<void> test_BAD_getterBySetter() async {
     addTestFile('''
 class A {
   get fff => null;
@@ -194,7 +194,7 @@
     assertNoOverride('fff(x) {}');
   }
 
-  test_BAD_methodByField() async {
+  Future<void> test_BAD_methodByField() async {
     addTestFile('''
 class A {
   fff() {} // in A
@@ -207,7 +207,7 @@
     assertNoOverride('fff; // in B');
   }
 
-  test_BAD_methodByGetter() async {
+  Future<void> test_BAD_methodByGetter() async {
     addTestFile('''
 class A {
   fff() {}
@@ -220,7 +220,7 @@
     assertNoOverride('fff => null');
   }
 
-  test_BAD_methodBySetter() async {
+  Future<void> test_BAD_methodBySetter() async {
     addTestFile('''
 class A {
   fff(x) {} // A
@@ -233,7 +233,7 @@
     assertNoOverride('fff(x) {} // B');
   }
 
-  test_BAD_privateByPrivate_inDifferentLib() async {
+  Future<void> test_BAD_privateByPrivate_inDifferentLib() async {
     newFile(join(testFolder, 'lib.dart'), content: r'''
 class A {
   void _m() {}
@@ -249,7 +249,7 @@
     assertNoOverride('_m() {} // in B');
   }
 
-  test_BAD_setterByGetter() async {
+  Future<void> test_BAD_setterByGetter() async {
     addTestFile('''
 class A {
   set fff(x) {}
@@ -262,7 +262,7 @@
     assertNoOverride('fff => null;');
   }
 
-  test_BAD_setterByMethod() async {
+  Future<void> test_BAD_setterByMethod() async {
     addTestFile('''
 class A {
   set fff(x) {} // A
@@ -275,7 +275,7 @@
     assertNoOverride('fff(x) {} // B');
   }
 
-  test_definedInInterface_ofInterface() async {
+  Future<void> test_definedInInterface_ofInterface() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -291,7 +291,7 @@
     assertHasInterfaceMember('m() {} // in A');
   }
 
-  test_definedInInterface_ofSuper() async {
+  Future<void> test_definedInInterface_ofSuper() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -307,7 +307,7 @@
     assertHasInterfaceMember('m() {} // in A');
   }
 
-  test_inMixin_interface_method_direct_single() async {
+  Future<void> test_inMixin_interface_method_direct_single() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -323,7 +323,7 @@
     assertHasInterfaceMember('m() {} // in A');
   }
 
-  test_inMixin_superclassConstraint_method_direct() async {
+  Future<void> test_inMixin_superclassConstraint_method_direct() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -339,7 +339,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_interface_method_direct_multiple() async {
+  Future<void> test_interface_method_direct_multiple() async {
     addTestFile('''
 class IA {
   m() {} // in IA
@@ -358,7 +358,7 @@
     assertHasInterfaceMember('m() {} // in IB');
   }
 
-  test_interface_method_direct_single() async {
+  Future<void> test_interface_method_direct_single() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -373,7 +373,7 @@
     assertHasInterfaceMember('m() {} // in A');
   }
 
-  test_interface_method_indirect_single() async {
+  Future<void> test_interface_method_indirect_single() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -390,7 +390,7 @@
     assertHasInterfaceMember('m() {} // in A');
   }
 
-  test_interface_stopWhenFound() async {
+  Future<void> test_interface_stopWhenFound() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -408,7 +408,7 @@
     assertHasInterfaceMember('m() {} // in B');
   }
 
-  test_mix_sameMethod() async {
+  Future<void> test_mix_sameMethod() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -425,7 +425,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_mix_sameMethod_Object_hashCode() async {
+  Future<void> test_mix_sameMethod_Object_hashCode() async {
     addTestFile('''
 class A {}
 abstract class B {}
@@ -439,7 +439,7 @@
     expect(overrideObject.interfaceMembers, isNull);
   }
 
-  test_mixin_method_direct() async {
+  Future<void> test_mixin_method_direct() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -454,7 +454,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_mixin_method_indirect() async {
+  Future<void> test_mixin_method_indirect() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -471,7 +471,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_mixin_method_indirect2() async {
+  Future<void> test_mixin_method_indirect2() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -488,7 +488,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_staticMembers() async {
+  Future<void> test_staticMembers() async {
     addTestFile('''
 class A {
   static int F = 0;
@@ -507,7 +507,7 @@
     expect(overridesList, isEmpty);
   }
 
-  test_super_fieldByField() async {
+  Future<void> test_super_fieldByField() async {
     addTestFile('''
 class A {
   int fff; // in A
@@ -522,7 +522,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_super_fieldByGetter() async {
+  Future<void> test_super_fieldByGetter() async {
     addTestFile('''
 class A {
   int fff; // in A
@@ -537,7 +537,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_super_fieldBySetter() async {
+  Future<void> test_super_fieldBySetter() async {
     addTestFile('''
 class A {
   int fff; // in A
@@ -552,7 +552,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_super_getterByField() async {
+  Future<void> test_super_getterByField() async {
     addTestFile('''
 class A {
   get fff => 0; // in A
@@ -568,7 +568,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_super_getterByGetter() async {
+  Future<void> test_super_getterByGetter() async {
     addTestFile('''
 class A {
   get fff => 0; // in A
@@ -583,7 +583,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_super_method_direct() async {
+  Future<void> test_super_method_direct() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -598,7 +598,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_super_method_indirect() async {
+  Future<void> test_super_method_indirect() async {
     addTestFile('''
 class A {
   m() {} // in A
@@ -615,7 +615,7 @@
     assertNoInterfaceMembers();
   }
 
-  test_super_method_privateByPrivate() async {
+  Future<void> test_super_method_privateByPrivate() async {
     addTestFile('''
 class A {
   _m() {} // in A
@@ -643,7 +643,7 @@
     // must finish
   }
 
-  test_super_setterBySetter() async {
+  Future<void> test_super_setterBySetter() async {
     addTestFile('''
 class A {
   set fff(x) {} // in A
diff --git a/pkg/analysis_server/test/analysis/reanalyze_test.dart b/pkg/analysis_server/test/analysis/reanalyze_test.dart
index 356a623..a5c4aff 100644
--- a/pkg/analysis_server/test/analysis/reanalyze_test.dart
+++ b/pkg/analysis_server/test/analysis/reanalyze_test.dart
@@ -11,7 +11,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReanalyzeTest);
   });
@@ -29,7 +29,7 @@
     }
   }
 
-  test_reanalyze() async {
+  Future<void> test_reanalyze() async {
     var b = convertPath('/other/b.dart');
 
     newFile(testFile, content: r'''
diff --git a/pkg/analysis_server/test/analysis/set_priority_files_test.dart b/pkg/analysis_server/test/analysis/set_priority_files_test.dart
index 62a3fcd..5c6df7dc 100644
--- a/pkg/analysis_server/test/analysis/set_priority_files_test.dart
+++ b/pkg/analysis_server/test/analysis/set_priority_files_test.dart
@@ -13,7 +13,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SetPriorityFilesTest);
   });
@@ -30,13 +30,13 @@
     createProject();
   }
 
-  test_fileDoesNotExist() async {
+  Future<void> test_fileDoesNotExist() async {
     String file = convertPath('$projectPath/doesNotExist.dart');
     Response response = await _setPriorityFile(file);
     expect(response, isResponseSuccess('0'));
   }
 
-  test_fileInAnalysisRoot() async {
+  Future<void> test_fileInAnalysisRoot() async {
     addTestFile('');
     // set priority files
     Response response = await _setPriorityFile(testFile);
@@ -45,7 +45,7 @@
     _verifyPriorityFiles(testFile);
   }
 
-  test_fileInSdk() async {
+  Future<void> test_fileInSdk() async {
     addTestFile('');
     // set priority files
     String filePath = convertPath('/lib/convert/convert.dart');
@@ -55,14 +55,14 @@
     _verifyPriorityFiles(filePath);
   }
 
-  test_fileNotInAnalysisRoot() async {
+  Future<void> test_fileNotInAnalysisRoot() async {
     String path = convertPath('/other/file.dart');
     newFile(path);
     await _setPriorityFile(path);
     _verifyPriorityFiles(path);
   }
 
-  test_ignoredInAnalysisOptions() async {
+  Future<void> test_ignoredInAnalysisOptions() async {
     String sampleFile = convertPath('$projectPath/samples/sample.dart');
     newFile('$projectPath/.analysis_options', content: r'''
 analyzer:
@@ -75,7 +75,7 @@
     _verifyPriorityFiles(sampleFile);
   }
 
-  test_ignoredInAnalysisOptions_inChildContext() async {
+  Future<void> test_ignoredInAnalysisOptions_inChildContext() async {
     newFile('$projectPath/.packages');
     newFile('$projectPath/child/.packages');
     String sampleFile = convertPath('$projectPath/child/samples/sample.dart');
@@ -90,7 +90,7 @@
     _verifyPriorityFiles(sampleFile);
   }
 
-  test_ignoredInAnalysisOptions_inRootContext() async {
+  Future<void> test_ignoredInAnalysisOptions_inRootContext() async {
     newFile('$projectPath/.packages');
     newFile('$projectPath/child/.packages');
     String sampleFile = convertPath('$projectPath/child/samples/sample.dart');
@@ -105,7 +105,7 @@
     _verifyPriorityFiles(sampleFile);
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = AnalysisSetPriorityFilesParams(['test.dart']).toRequest('0');
     var response = await waitResponse(request);
     expect(
@@ -114,7 +114,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request =
         AnalysisSetPriorityFilesParams([convertPath('/foo/../bar/test.dart')])
             .toRequest('0');
@@ -125,7 +125,7 @@
     );
   }
 
-  test_sentToPlugins() async {
+  Future<void> test_sentToPlugins() async {
     addTestFile('');
     // set priority files
     Response response = await _setPriorityFile(testFile);
@@ -137,7 +137,7 @@
     expect(params.files, <String>[testFile]);
   }
 
-  _setPriorityFile(String file) async {
+  Future<Response> _setPriorityFile(String file) async {
     Request request =
         AnalysisSetPriorityFilesParams(<String>[file]).toRequest('0');
     return await serverChannel.sendRequest(request);
diff --git a/pkg/analysis_server/test/analysis/test_all.dart b/pkg/analysis_server/test/analysis/test_all.dart
index bd8d396..702a96c 100644
--- a/pkg/analysis_server/test/analysis/test_all.dart
+++ b/pkg/analysis_server/test/analysis/test_all.dart
@@ -25,7 +25,7 @@
 import 'set_priority_files_test.dart' as set_priority_files;
 import 'update_content_test.dart' as update_content;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     get_errors.main();
     get_hover.main();
diff --git a/pkg/analysis_server/test/analysis/update_content_test.dart b/pkg/analysis_server/test/analysis/update_content_test.dart
index 832daf8..ddfe39d 100644
--- a/pkg/analysis_server/test/analysis/update_content_test.dart
+++ b/pkg/analysis_server/test/analysis/update_content_test.dart
@@ -16,7 +16,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UpdateContentTest);
   });
@@ -44,7 +44,7 @@
     }
   }
 
-  test_illegal_ChangeContentOverlay() {
+  void test_illegal_ChangeContentOverlay() {
     // It should be illegal to send a ChangeContentOverlay for a file that
     // doesn't have an overlay yet.
     createProject();
@@ -61,7 +61,7 @@
     }
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = AnalysisUpdateContentParams(
       {'test.dart': AddContentOverlay('')},
     ).toRequest('0');
@@ -72,7 +72,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request = AnalysisUpdateContentParams(
       {convertPath('/foo/../bar/test.dart'): AddContentOverlay('')},
     ).toRequest('0');
@@ -83,7 +83,7 @@
     );
   }
 
-  test_multiple_contexts() async {
+  Future<void> test_multiple_contexts() async {
     String project1path = convertPath('/project1');
     String project2path = convertPath('/project2');
     String fooPath = newFile('/project1/foo.dart', content: '''
@@ -126,7 +126,7 @@
   }
 
   @failingTest
-  test_overlay_addPreviouslyImported() async {
+  Future<void> test_overlay_addPreviouslyImported() async {
     // The list of errors doesn't include errors for '/project/target.dart'.
     Folder project = newFolder('/project');
     handleSuccessfulRequest(
@@ -150,7 +150,7 @@
     });
   }
 
-  test_overlayOnly() async {
+  Future<void> test_overlayOnly() async {
     var filePath1 = convertPath('/User/project1/test.dart');
     var filePath2 = convertPath('/User/project2/test.dart');
     var folderPath1 = newFolder('/User/project1').path;
@@ -184,7 +184,7 @@
   }
 
   @failingTest
-  test_sendNoticesAfterNopChange() async {
+  Future<void> test_sendNoticesAfterNopChange() async {
     // The errors are empty on the last line.
     createProject();
     addTestFile('');
@@ -204,7 +204,7 @@
   }
 
   @failingTest
-  test_sendNoticesAfterNopChange_flushedUnit() async {
+  Future<void> test_sendNoticesAfterNopChange_flushedUnit() async {
     // The list of errors is empty on the last line.
     createProject();
     addTestFile('');
@@ -223,7 +223,7 @@
     expect(filesErrors, isNotEmpty);
   }
 
-  test_sentToPlugins() {
+  void test_sentToPlugins() {
     String filePath = convertPath('/project/target.dart');
     String fileContent = 'import "none.dart";';
     //
diff --git a/pkg/analysis_server/test/analysis_server_test.dart b/pkg/analysis_server/test/analysis_server_test.dart
index 56bba4d..e984cce 100644
--- a/pkg/analysis_server/test/analysis_server_test.dart
+++ b/pkg/analysis_server/test/analysis_server_test.dart
@@ -19,7 +19,7 @@
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisServerTest);
   });
@@ -129,7 +129,8 @@
     });
   }
 
-  test_setAnalysisSubscriptions_fileInIgnoredFolder_newOptions() async {
+  Future<void>
+      test_setAnalysisSubscriptions_fileInIgnoredFolder_newOptions() async {
     String path = convertPath('/project/samples/sample.dart');
     newFile(path);
     newFile('/project/analysis_options.yaml', content: r'''
@@ -149,7 +150,8 @@
     }), isTrue);
   }
 
-  test_setAnalysisSubscriptions_fileInIgnoredFolder_oldOptions() async {
+  Future<void>
+      test_setAnalysisSubscriptions_fileInIgnoredFolder_oldOptions() async {
     String path = convertPath('/project/samples/sample.dart');
     newFile(path);
     newFile('/project/.analysis_options', content: r'''
diff --git a/pkg/analysis_server/test/channel/byte_stream_channel_test.dart b/pkg/analysis_server/test/channel/byte_stream_channel_test.dart
index 1f181bc..ee38485 100644
--- a/pkg/analysis_server/test/channel/byte_stream_channel_test.dart
+++ b/pkg/analysis_server/test/channel/byte_stream_channel_test.dart
@@ -12,7 +12,7 @@
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ByteStreamClientChannelTest);
     defineReflectiveTests(ByteStreamServerChannelTest);
@@ -50,7 +50,7 @@
     channel = ByteStreamClientChannel(inputStream.stream, outputSink);
   }
 
-  test_close() {
+  Future<void> test_close() {
     bool doneCalled = false;
     bool closeCalled = false;
     // add listener so that outputSink will trigger done/close futures
@@ -67,7 +67,7 @@
     });
   }
 
-  test_listen_notification() {
+  Future<void> test_listen_notification() {
     List<Notification> notifications = [];
     channel.notificationStream.forEach((n) => notifications.add(n));
     inputSink.writeln('{"event":"server.connected"}');
@@ -77,7 +77,7 @@
     });
   }
 
-  test_listen_response() {
+  Future<void> test_listen_response() {
     List<Response> responses = [];
     channel.responseStream.forEach((n) => responses.add(n));
     inputSink.writeln('{"id":"72"}');
@@ -87,7 +87,7 @@
     });
   }
 
-  test_sendRequest() {
+  Future<void> test_sendRequest() {
     int assertCount = 0;
     Request request = Request('72', 'foo.bar');
     outputLineStream.first.then((line) => json.decode(line)).then((json) {
@@ -161,13 +161,13 @@
     });
   }
 
-  test_closed() {
+  Future<void> test_closed() {
     return inputSink
         .close()
         .then((_) => channel.closed.timeout(Duration(seconds: 1)));
   }
 
-  test_listen_invalidJson() {
+  Future<void> test_listen_invalidJson() {
     inputSink.writeln('{"id":');
     return inputSink
         .flush()
@@ -180,7 +180,7 @@
     });
   }
 
-  test_listen_invalidRequest() {
+  Future<void> test_listen_invalidRequest() {
     inputSink.writeln('{"id":"0"}');
     return inputSink
         .flush()
@@ -193,13 +193,13 @@
     });
   }
 
-  test_listen_streamDone() {
+  Future<void> test_listen_streamDone() {
     return inputSink
         .close()
         .then((_) => doneFuture.timeout(Duration(seconds: 1)));
   }
 
-  test_listen_streamError() {
+  Future<void> test_listen_streamError() {
     var error = Error();
     inputSink.addError(error);
     return inputSink
@@ -210,7 +210,7 @@
     });
   }
 
-  test_listen_wellFormedRequest() {
+  Future<void> test_listen_wellFormedRequest() {
     inputSink.writeln('{"id":"0","method":"server.version"}');
     return inputSink
         .flush()
@@ -221,7 +221,7 @@
     });
   }
 
-  test_sendNotification() {
+  Future<void> test_sendNotification() {
     channel.sendNotification(Notification('foo'));
     return outputLineStream.first
         .timeout(Duration(seconds: 1))
@@ -233,7 +233,7 @@
     });
   }
 
-  test_sendNotification_exceptionInSink() async {
+  Future<void> test_sendNotification_exceptionInSink() async {
     // This IOSink asynchronously throws an exception on any writeln().
     var outputSink = _IOSinkMock();
 
@@ -247,7 +247,7 @@
     await channel.closed;
   }
 
-  test_sendResponse() {
+  Future<void> test_sendResponse() {
     channel.sendResponse(Response('foo'));
     return outputLineStream.first
         .timeout(Duration(seconds: 1))
diff --git a/pkg/analysis_server/test/channel/test_all.dart b/pkg/analysis_server/test/channel/test_all.dart
index 3edd228..b712e00 100644
--- a/pkg/analysis_server/test/channel/test_all.dart
+++ b/pkg/analysis_server/test/channel/test_all.dart
@@ -6,10 +6,7 @@
 
 import 'byte_stream_channel_test.dart' as byte_stream_channel_test;
 
-/**
- * Utility for manually running all tests.
- */
-main() {
+void main() {
   group('computer', () {
     byte_stream_channel_test.main();
   });
diff --git a/pkg/analysis_server/test/completion_test.dart b/pkg/analysis_server/test/completion_test.dart
index ec85f5e..add1c6d 100644
--- a/pkg/analysis_server/test/completion_test.dart
+++ b/pkg/analysis_server/test/completion_test.dart
@@ -9,7 +9,7 @@
 
 import 'completion_test_support.dart';
 
-main() {
+void main() {
   CompletionTestBuilder builder = CompletionTestBuilder();
   builder.buildAll();
 }
diff --git a/pkg/analysis_server/test/completion_test_support.dart b/pkg/analysis_server/test/completion_test_support.dart
index f4e49b7..09eb049 100644
--- a/pkg/analysis_server/test/completion_test_support.dart
+++ b/pkg/analysis_server/test/completion_test_support.dart
@@ -77,7 +77,7 @@
         .toList();
   }
 
-  runTest(LocationSpec spec, [Map<String, String> extraFiles]) {
+  Future runTest(LocationSpec spec, [Map<String, String> extraFiles]) {
     super.setUp();
     return Future(() {
       String content = spec.source;
diff --git a/pkg/analysis_server/test/context_manager_test.dart b/pkg/analysis_server/test/context_manager_test.dart
index bf3f07d..b9a8244 100644
--- a/pkg/analysis_server/test/context_manager_test.dart
+++ b/pkg/analysis_server/test/context_manager_test.dart
@@ -40,7 +40,7 @@
 
 import 'src/plugin/plugin_manager_test.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AbstractContextManagerTest);
     defineReflectiveTests(ContextManagerWithNewOptionsTest);
@@ -87,7 +87,7 @@
   }
 
   @failingTest
-  test_embedder_added() async {
+  Future<void> test_embedder_added() async {
     // NoSuchMethodError: The getter 'apiSignature' was called on null.
     // Receiver: null
     // Tried calling: apiSignature
@@ -144,7 +144,7 @@
     expect(sourceFactory.forUri('dart:typed_data'), isNotNull);
   }
 
-  test_embedder_packagespec() async {
+  Future<void> test_embedder_packagespec() async {
     // Create files.
     String libPath = '$projPath/${ContextManagerTest.LIB_NAME}';
     newFile('$libPath/main.dart');
@@ -220,7 +220,7 @@
     expect(manager.isInAnalysisRoot('/test.dart'), isFalse);
   }
 
-  test_packagesFolder_areAnalyzed() {
+  Future<void> test_packagesFolder_areAnalyzed() {
     // create a context with a pubspec.yaml file
     String pubspecPath = join(projPath, 'pubspec.yaml');
     resourceProvider.newFile(pubspecPath, 'pubspec');
@@ -237,7 +237,7 @@
     });
   }
 
-  test_path_filter() async {
+  Future<void> test_path_filter() async {
     // Setup context.
     Folder root = resourceProvider.newFolder(projPath);
     manager.setRoots(<String>[projPath], <String>[], <String, String>{});
@@ -263,7 +263,7 @@
     expect(filePaths, contains(convertPath('/my/proj/lib/main.dart')));
   }
 
-  test_refresh_folder_with_packagespec() {
+  Future<void> test_refresh_folder_with_packagespec() {
     // create a context with a .packages file
     String packagespecFile = join(projPath, '.packages');
     resourceProvider.newFile(packagespecFile, '');
@@ -282,7 +282,7 @@
   // TODO(paulberry): This test only tests PackagesFileDisposition.
   // Once http://dartbug.com/23909 is fixed, add a test for sdk extensions
   // and PackageMapDisposition.
-  test_refresh_folder_with_packagespec_subfolders() {
+  Future<void> test_refresh_folder_with_packagespec_subfolders() {
     // Create a folder with no .packages file, containing two subfolders with
     // .packages files.
     String subdir1Path = join(projPath, 'subdir1');
@@ -307,7 +307,7 @@
     });
   }
 
-  test_refresh_folder_with_pubspec() {
+  Future<void> test_refresh_folder_with_pubspec() {
     // create a context with a pubspec.yaml file
     String pubspecPath = join(projPath, 'pubspec.yaml');
     resourceProvider.newFile(pubspecPath, 'pubspec');
@@ -323,7 +323,7 @@
     });
   }
 
-  test_refresh_folder_with_pubspec_subfolders() {
+  Future<void> test_refresh_folder_with_pubspec_subfolders() {
     // Create a folder with no pubspec.yaml, containing two subfolders with
     // pubspec.yaml files.
     String subdir1Path = join(projPath, 'subdir1');
@@ -348,7 +348,7 @@
     });
   }
 
-  test_refresh_oneContext() {
+  Future<void> test_refresh_oneContext() {
     // create two contexts with pubspec.yaml files
     String pubspecPath = join(projPath, 'pubspec.yaml');
     resourceProvider.newFile(pubspecPath, 'pubspec1');
@@ -1085,7 +1085,7 @@
     callbacks.assertContextFiles(project, [fileA]);
   }
 
-  test_watch_addDummyLink() {
+  Future<void> test_watch_addDummyLink() {
     manager.setRoots(<String>[projPath], <String>[], <String, String>{});
     // empty folder initially
     expect(callbacks.currentFilePaths, isEmpty);
@@ -1098,7 +1098,7 @@
     });
   }
 
-  test_watch_addFile() {
+  Future<void> test_watch_addFile() {
     manager.setRoots(<String>[projPath], <String>[], <String, String>{});
     // empty folder initially
     expect(callbacks.currentFilePaths, hasLength(0));
@@ -1113,7 +1113,7 @@
     });
   }
 
-  test_watch_addFile_excluded() {
+  Future<void> test_watch_addFile_excluded() {
     // prepare paths
     String project = convertPath('/project');
     String folderA = convertPath('$project/aaa');
@@ -1134,7 +1134,7 @@
     });
   }
 
-  test_watch_addFile_inDocFolder_inner() {
+  Future<void> test_watch_addFile_inDocFolder_inner() {
     // prepare paths
     String project = convertPath('/project');
     String fileA = convertPath('$project/a.dart');
@@ -1153,7 +1153,7 @@
     });
   }
 
-  test_watch_addFile_inDocFolder_topLevel() {
+  Future<void> test_watch_addFile_inDocFolder_topLevel() {
     // prepare paths
     String project = convertPath('/project');
     String fileA = convertPath('$project/a.dart');
@@ -1172,7 +1172,7 @@
     });
   }
 
-  test_watch_addFile_pathContainsDotFile() async {
+  Future<void> test_watch_addFile_pathContainsDotFile() async {
     // If a file is added and the path to it (relative to the context root)
     // contains a folder whose name begins with '.', then the file is ignored.
     String project = convertPath('/project');
@@ -1188,7 +1188,7 @@
     callbacks.assertContextFiles(project, [fileA]);
   }
 
-  test_watch_addFile_rootPathContainsDotFile() async {
+  Future<void> test_watch_addFile_rootPathContainsDotFile() async {
     // If a file is added and the path to the context contains a folder whose
     // name begins with '.', then the file is not ignored.
     String project = convertPath('/.pub/project');
@@ -1204,7 +1204,7 @@
     callbacks.assertContextFiles(project, [fileA, fileB]);
   }
 
-  test_watch_addFileInSubfolder() {
+  Future<void> test_watch_addFileInSubfolder() {
     manager.setRoots(<String>[projPath], <String>[], <String, String>{});
     // empty folder initially
     expect(callbacks.currentFilePaths, hasLength(0));
@@ -1219,7 +1219,7 @@
     });
   }
 
-  test_watch_addPackagespec_toRoot() {
+  Future<void> test_watch_addPackagespec_toRoot() {
     // prepare paths
     String root = convertPath('/root');
     String rootFile = convertPath('$root/root.dart');
@@ -1241,7 +1241,7 @@
     });
   }
 
-  test_watch_addPackagespec_toSubFolder() {
+  Future<void> test_watch_addPackagespec_toSubFolder() {
     // prepare paths
     String root = convertPath('/root');
     String rootFile = convertPath('$root/root.dart');
@@ -1265,7 +1265,7 @@
     });
   }
 
-  test_watch_addPackagespec_toSubFolder_ofSubFolder() {
+  Future<void> test_watch_addPackagespec_toSubFolder_ofSubFolder() {
     // prepare paths
     String root = convertPath('/root');
     String rootFile = convertPath('$root/root.dart');
@@ -1291,7 +1291,7 @@
     });
   }
 
-  test_watch_addPackagespec_toSubFolder_withPubspec() {
+  Future<void> test_watch_addPackagespec_toSubFolder_withPubspec() {
     // prepare paths
     String root = convertPath('/root');
     String rootFile = convertPath('$root/root.dart');
@@ -1320,7 +1320,7 @@
     });
   }
 
-  test_watch_addPubspec_toRoot() {
+  Future<void> test_watch_addPubspec_toRoot() {
     // prepare paths
     String root = convertPath('/root');
     String rootFile = convertPath('$root/root.dart');
@@ -1340,7 +1340,7 @@
     });
   }
 
-  test_watch_addPubspec_toSubFolder() {
+  Future<void> test_watch_addPubspec_toSubFolder() {
     // prepare paths
     String root = convertPath('/root');
     String rootFile = convertPath('$root/root.dart');
@@ -1364,7 +1364,7 @@
     });
   }
 
-  test_watch_addPubspec_toSubFolder_ofSubFolder() {
+  Future<void> test_watch_addPubspec_toSubFolder_ofSubFolder() {
     // prepare paths
     String root = convertPath('/root');
     String rootFile = convertPath('$root/root.dart');
@@ -1390,7 +1390,7 @@
     });
   }
 
-  test_watch_deleteFile() {
+  Future<void> test_watch_deleteFile() {
     String filePath = join(projPath, 'foo.dart');
     // add root with a file
     File file = resourceProvider.newFile(filePath, 'contents');
@@ -1411,7 +1411,7 @@
     });
   }
 
-  test_watch_deleteFolder() {
+  Future<void> test_watch_deleteFolder() {
     String filePath = join(projPath, 'foo.dart');
     // add root with a file
     File file = resourceProvider.newFile(filePath, 'contents');
@@ -1432,7 +1432,7 @@
     });
   }
 
-  test_watch_deletePackagespec_fromRoot() {
+  Future<void> test_watch_deletePackagespec_fromRoot() {
     // prepare paths
     String root = convertPath('/root');
     String rootPubspec = convertPath('$root/.packages');
@@ -1452,7 +1452,7 @@
     });
   }
 
-  test_watch_deletePackagespec_fromSubFolder() {
+  Future<void> test_watch_deletePackagespec_fromSubFolder() {
     // prepare paths
     String root = convertPath('/root');
     String rootFile = convertPath('$root/root.dart');
@@ -1477,7 +1477,7 @@
     });
   }
 
-  test_watch_deletePackagespec_fromSubFolder_withPubspec() {
+  Future<void> test_watch_deletePackagespec_fromSubFolder_withPubspec() {
     // prepare paths:
     //
     // root
@@ -1515,7 +1515,7 @@
     });
   }
 
-  test_watch_deletePubspec_fromRoot() {
+  Future<void> test_watch_deletePubspec_fromRoot() {
     // prepare paths
     String root = convertPath('/root');
     String rootPubspec = convertPath('$root/pubspec.yaml');
@@ -1535,7 +1535,7 @@
     });
   }
 
-  test_watch_deletePubspec_fromSubFolder() {
+  Future<void> test_watch_deletePubspec_fromSubFolder() {
     // prepare paths
     String root = convertPath('/root');
     String rootFile = convertPath('$root/root.dart');
@@ -1560,7 +1560,7 @@
     });
   }
 
-  test_watch_modifyFile() {
+  Future<void> test_watch_modifyFile() {
     String filePath = join(projPath, 'foo.dart');
     // add root with a file
     resourceProvider.newFile(filePath, 'contents');
@@ -1578,7 +1578,7 @@
     });
   }
 
-  test_watch_modifyPackagespec() {
+  Future<void> test_watch_modifyPackagespec() {
     String packagesPath = convertPath('$projPath/.packages');
     String filePath = convertPath('$projPath/bin/main.dart');
 
@@ -1732,7 +1732,7 @@
 
   @override
   @failingTest
-  test_analysis_options_parse_failure() async {
+  Future<void> test_analysis_options_parse_failure() async {
     // We have lost the ability to detect errors of this form.
     return super.test_analysis_options_parse_failure();
   }
@@ -1751,7 +1751,7 @@
     deleteFile('$projPath/$optionsFileName');
   }
 
-  test_analysis_options_file_delete() async {
+  Future<void> test_analysis_options_file_delete() async {
     // Setup analysis options
     newFile('$projPath/$optionsFileName', content: r'''
 embedded_libs:
@@ -1782,7 +1782,7 @@
   }
 
   @failingTest
-  test_analysis_options_file_delete_with_embedder() async {
+  Future<void> test_analysis_options_file_delete_with_embedder() async {
     // This fails because the ContextBuilder doesn't pick up the strongMode
     // flag from the embedder.yaml file.
     // Setup _embedder.yaml.
@@ -1831,7 +1831,7 @@
     expect(getProcessor(missing_return).severity, isNull);
   }
 
-  test_analysis_options_include() async {
+  Future<void> test_analysis_options_include() async {
     // Create files.
     String libPath = '$projPath/${ContextManagerTest.LIB_NAME}';
     newFile('$libPath/main.dart');
@@ -1860,7 +1860,7 @@
     expect(lints[0].name, 'camel_case_types');
   }
 
-  test_analysis_options_include_package() async {
+  Future<void> test_analysis_options_include_package() async {
     // Create files.
     String libPath = '$projPath/${ContextManagerTest.LIB_NAME}';
     newFile('$libPath/main.dart');
@@ -1893,7 +1893,7 @@
     expect(lints[0].name, 'camel_case_types');
   }
 
-  test_analysis_options_parse_failure() async {
+  Future<void> test_analysis_options_parse_failure() async {
     // Create files.
     String libPath = '$projPath/${ContextManagerTest.LIB_NAME}';
     newFile('$libPath/main.dart');
@@ -1915,7 +1915,7 @@
     expect(errors[errors.keys.first][optionsFilePath], hasLength(1));
   }
 
-  test_deleteRoot_hasAnalysisOptions() async {
+  Future<void> test_deleteRoot_hasAnalysisOptions() async {
     newFile('$projPath/$optionsFileName');
 
     // Add the root.
@@ -1929,7 +1929,7 @@
   }
 
   @failingTest
-  test_embedder_options() async {
+  Future<void> test_embedder_options() async {
     // This fails because the ContextBuilder doesn't pick up the strongMode
     // flag from the embedder.yaml file.
     // Create files.
@@ -2015,7 +2015,7 @@
     expect(source.fullName, '/my/proj/sdk_ext/entry.dart');
   }
 
-  test_error_filter_analysis_option() async {
+  Future<void> test_error_filter_analysis_option() async {
     // Create files.
     newFile('$projPath/$optionsFileName', content: r'''
 analyzer:
@@ -2030,7 +2030,7 @@
     expect(getProcessor(unused_local_variable).severity, isNull);
   }
 
-  test_error_filter_analysis_option_multiple_filters() async {
+  Future<void> test_error_filter_analysis_option_multiple_filters() async {
     // Create files.
     newFile('$projPath/$optionsFileName', content: r'''
 analyzer:
@@ -2048,7 +2048,7 @@
     expect(getProcessor(unused_local_variable).severity, ErrorSeverity.ERROR);
   }
 
-  test_error_filter_analysis_option_synonyms() async {
+  Future<void> test_error_filter_analysis_option_synonyms() async {
     // Create files.
     newFile('$projPath/$optionsFileName', content: r'''
 analyzer:
@@ -2064,7 +2064,7 @@
     expect(errorProcessors, hasLength(2));
   }
 
-  test_error_filter_analysis_option_unpsecified() async {
+  Future<void> test_error_filter_analysis_option_unpsecified() async {
     // Create files.
     newFile('$projPath/$optionsFileName', content: r'''
 analyzer:
@@ -2078,7 +2078,7 @@
     expect(errorProcessors, isEmpty);
   }
 
-  test_non_analyzable_files_not_considered() async {
+  Future<void> test_non_analyzable_files_not_considered() async {
     // Set up project and get a reference to the driver.
     manager.setRoots(<String>[projPath], <String>[], <String, String>{});
     Folder projectFolder = resourceProvider.newFolder(projPath);
@@ -2100,7 +2100,7 @@
   }
 
   @failingTest
-  test_optionsFile_update_strongMode() async {
+  Future<void> test_optionsFile_update_strongMode() async {
     // It appears that this fails because we are not correctly updating the
     // analysis options in the driver when the file is modified.
     //return super.test_optionsFile_update_strongMode();
@@ -2154,7 +2154,7 @@
   }
 
   @failingTest
-  test_path_filter_analysis_option() async {
+  Future<void> test_path_filter_analysis_option() async {
     // This fails because we're not analyzing the analysis options file.
     // Create files.
     String libPath = '$projPath/${ContextManagerTest.LIB_NAME}';
@@ -2185,7 +2185,7 @@
             ['/my/proj/lib/main.dart', '/my/proj/$optionsFileName']));
   }
 
-  test_path_filter_child_contexts_option() async {
+  Future<void> test_path_filter_child_contexts_option() async {
     // Create files.
     String libPath = '$projPath/${ContextManagerTest.LIB_NAME}';
     newFile('$libPath/main.dart');
@@ -2215,7 +2215,8 @@
     expect(drivers[1].name, equals(convertPath('/my/proj/lib')));
   }
 
-  test_path_filter_recursive_wildcard_child_contexts_option() async {
+  Future<void>
+      test_path_filter_recursive_wildcard_child_contexts_option() async {
     // Create files.
     String libPath = '$projPath/${ContextManagerTest.LIB_NAME}';
     newFile('$libPath/main.dart');
@@ -2246,7 +2247,7 @@
     expect(drivers[1].name, equals(convertPath('/my/proj/lib')));
   }
 
-  test_path_filter_wildcard_child_contexts_option() async {
+  Future<void> test_path_filter_wildcard_child_contexts_option() async {
     // Create files.
     String libPath = '$projPath/${ContextManagerTest.LIB_NAME}';
     newFile('$libPath/main.dart');
@@ -2342,7 +2343,7 @@
     expect(callbacks.currentContextRoots, unorderedEquals([a, c]));
   }
 
-  test_watchEvents() async {
+  Future<void> test_watchEvents() async {
     String libPath = newFolder('$projPath/${ContextManagerTest.LIB_NAME}').path;
     manager.setRoots(<String>[projPath], <String>[], <String, String>{});
     newFile('$libPath/main.dart');
diff --git a/pkg/analysis_server/test/domain_analysis_test.dart b/pkg/analysis_server/test/domain_analysis_test.dart
index a3b10b3..a958b00 100644
--- a/pkg/analysis_server/test/domain_analysis_test.dart
+++ b/pkg/analysis_server/test/domain_analysis_test.dart
@@ -22,7 +22,7 @@
 import 'analysis_abstract.dart';
 import 'mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisDomainTest);
     defineReflectiveTests(AnalysisDomainHandlerTest);
@@ -32,7 +32,7 @@
 
 @reflectiveTest
 class AnalysisDomainHandlerTest extends AbstractAnalysisTest {
-  Future outOfRangeTest(SourceEdit edit) async {
+  Future<void> outOfRangeTest(SourceEdit edit) async {
     AnalysisTestHelper helper = AnalysisTestHelper();
     helper.createSingleFileProject('library A;');
     await helper.onAnalysisComplete;
@@ -47,7 +47,7 @@
         isResponseFailure('0', RequestErrorCode.INVALID_OVERLAY_CHANGE));
   }
 
-  test_setAnalysisRoots_excludedFolder() async {
+  Future<void> test_setAnalysisRoots_excludedFolder() async {
     newFile('/project/aaa/a.dart', content: '// a');
     newFile('/project/bbb/b.dart', content: '// b');
     var excludedPath = join(projectPath, 'bbb');
@@ -55,7 +55,7 @@
     expect(response, isResponseSuccess('0'));
   }
 
-  test_setAnalysisRoots_included_newFolder() async {
+  Future<void> test_setAnalysisRoots_included_newFolder() async {
     newFile('/project/pubspec.yaml', content: 'name: project');
     String file = newFile('/project/bin/test.dart', content: 'main() {}').path;
     var response = testSetAnalysisRoots([projectPath], []);
@@ -67,7 +67,7 @@
     expect(resolvedUnit, isNotNull);
   }
 
-  test_setAnalysisRoots_included_nonexistentFolder() async {
+  Future<void> test_setAnalysisRoots_included_nonexistentFolder() async {
     String projectA = convertPath('/project_a');
     String projectB = convertPath('/project_b');
     String fileB = newFile('/project_b/b.dart', content: '// b').path;
@@ -81,31 +81,31 @@
     expect(resolvedUnit, isNotNull);
   }
 
-  test_setAnalysisRoots_included_notAbsolute() async {
+  Future<void> test_setAnalysisRoots_included_notAbsolute() async {
     var response = testSetAnalysisRoots(['foo/bar'], []);
     expect(response,
         isResponseFailure('0', RequestErrorCode.INVALID_FILE_PATH_FORMAT));
   }
 
-  test_setAnalysisRoots_included_notNormalized() async {
+  Future<void> test_setAnalysisRoots_included_notNormalized() async {
     var response = testSetAnalysisRoots(['/foo/../bar'], []);
     expect(response,
         isResponseFailure('0', RequestErrorCode.INVALID_FILE_PATH_FORMAT));
   }
 
-  test_setAnalysisRoots_notAbsolute() async {
+  Future<void> test_setAnalysisRoots_notAbsolute() async {
     var response = testSetAnalysisRoots([], ['foo/bar']);
     expect(response,
         isResponseFailure('0', RequestErrorCode.INVALID_FILE_PATH_FORMAT));
   }
 
-  test_setAnalysisRoots_notNormalized() async {
+  Future<void> test_setAnalysisRoots_notNormalized() async {
     var response = testSetAnalysisRoots([], ['/foo/../bar']);
     expect(response,
         isResponseFailure('0', RequestErrorCode.INVALID_FILE_PATH_FORMAT));
   }
 
-  test_setPriorityFiles_invalid() {
+  void test_setPriorityFiles_invalid() {
     var request = AnalysisSetPriorityFilesParams(
       [convertPath('/project/lib.dart')],
     ).toRequest('0');
@@ -113,7 +113,7 @@
     expect(response, isResponseSuccess('0'));
   }
 
-  test_setPriorityFiles_valid() {
+  void test_setPriorityFiles_valid() {
     var p1 = convertPath('/p1');
     var p2 = convertPath('/p2');
     var aPath = convertPath('/p1/a.dart');
@@ -142,7 +142,7 @@
     setPriorityFiles([]);
   }
 
-  test_updateContent_badType() async {
+  Future<void> test_updateContent_badType() async {
     AnalysisTestHelper helper = AnalysisTestHelper();
     helper.createSingleFileProject('// empty');
     await helper.onAnalysisComplete;
@@ -157,7 +157,7 @@
     expect(response, isResponseFailure('0'));
   }
 
-  test_updateContent_changeOnDisk_duringOverride() async {
+  Future<void> test_updateContent_changeOnDisk_duringOverride() async {
     AnalysisTestHelper helper = AnalysisTestHelper();
     helper.createSingleFileProject('library A;');
     await helper.onAnalysisComplete;
@@ -179,7 +179,7 @@
     expect(helper.getTestErrors(), hasLength(1));
   }
 
-  test_updateContent_changeOnDisk_normal() async {
+  Future<void> test_updateContent_changeOnDisk_normal() async {
     AnalysisTestHelper helper = AnalysisTestHelper();
     helper.createSingleFileProject('library A;');
     await helper.onAnalysisComplete;
@@ -193,7 +193,7 @@
     expect(helper.getTestErrors(), hasLength(1));
   }
 
-  test_updateContent_fullContent() async {
+  Future<void> test_updateContent_fullContent() async {
     AnalysisTestHelper helper = AnalysisTestHelper();
     helper.createSingleFileProject('// empty');
     await helper.onAnalysisComplete;
@@ -208,7 +208,7 @@
     expect(errors, hasLength(1));
   }
 
-  test_updateContent_incremental() async {
+  Future<void> test_updateContent_incremental() async {
     AnalysisTestHelper helper = AnalysisTestHelper();
     String initialContent = 'library A;';
     helper.createSingleFileProject(initialContent);
@@ -227,19 +227,19 @@
     expect(errors, hasLength(1));
   }
 
-  test_updateContent_outOfRange_beyondEnd() {
+  Future<void> test_updateContent_outOfRange_beyondEnd() {
     return outOfRangeTest(SourceEdit(6, 6, 'foo'));
   }
 
-  test_updateContent_outOfRange_negativeLength() {
+  Future<void> test_updateContent_outOfRange_negativeLength() {
     return outOfRangeTest(SourceEdit(3, -1, 'foo'));
   }
 
-  test_updateContent_outOfRange_negativeOffset() {
+  Future<void> test_updateContent_outOfRange_negativeOffset() {
     return outOfRangeTest(SourceEdit(-1, 3, 'foo'));
   }
 
-  test_updateOptions_invalid() {
+  void test_updateOptions_invalid() {
     var request = Request('0', ANALYSIS_REQUEST_UPDATE_OPTIONS, {
       ANALYSIS_REQUEST_UPDATE_OPTIONS_OPTIONS: {'not-an-option': true}
     });
@@ -248,7 +248,7 @@
     expect(response, isResponseSuccess('0'));
   }
 
-  test_updateOptions_null() {
+  void test_updateOptions_null() {
     // null is allowed as a synonym for {}.
     var request = Request('0', ANALYSIS_REQUEST_UPDATE_OPTIONS,
         {ANALYSIS_REQUEST_UPDATE_OPTIONS_OPTIONS: null});
@@ -262,7 +262,7 @@
     return handler.handleRequest(request);
   }
 
-  xtest_getReachableSources_invalidSource() async {
+  Future<void> xtest_getReachableSources_invalidSource() async {
     // TODO(brianwilkerson) Re-enable this test if we re-enable the
     // analysis.getReachableSources request.
     newFile('/project/a.dart', content: 'import "b.dart";');
@@ -278,7 +278,7 @@
         RequestErrorCode.GET_REACHABLE_SOURCES_INVALID_FILE);
   }
 
-  xtest_getReachableSources_validSources() async {
+  Future<void> xtest_getReachableSources_validSources() async {
     // TODO(brianwilkerson) Re-enable this test if we re-enable the
     // analysis.getReachableSources request.
     String fileA = newFile('/project/a.dart', content: 'import "b.dart";').path;
@@ -313,7 +313,7 @@
     }
   }
 
-  test_setRoots_packages() {
+  Future<void> test_setRoots_packages() {
     // prepare package
     String pkgFile = newFile('/packages/pkgA/libA.dart', content: '''
 library lib_a;
@@ -556,7 +556,7 @@
     }
   }
 
-  test_afterAnalysis() async {
+  Future<void> test_afterAnalysis() async {
     addTestFile('int V = 42;');
     createProject();
     // wait for analysis, no results initially
@@ -583,7 +583,7 @@
     expect(filesHighlights[file], isEmpty);
   }
 
-  test_afterAnalysis_packageFile_external() async {
+  Future<void> test_afterAnalysis_packageFile_external() async {
     String pkgFile = newFile('/packages/pkgA/lib/libA.dart', content: '''
 library lib_a;
 class A {}
@@ -607,7 +607,7 @@
     expect(filesHighlights[pkgFile], isNotEmpty);
   }
 
-  test_afterAnalysis_packageFile_inRoot() async {
+  Future<void> test_afterAnalysis_packageFile_inRoot() async {
     String pkgA = convertPath('/pkgA');
     String pkgB = convertPath('/pkgA');
     String pkgFileA = newFile('$pkgA/lib/libA.dart', content: '''
@@ -634,7 +634,7 @@
     expect(filesHighlights[pkgFileA], isNotEmpty);
   }
 
-  test_afterAnalysis_packageFile_notUsed() async {
+  Future<void> test_afterAnalysis_packageFile_notUsed() async {
     String pkgFile = newFile('/packages/pkgA/lib/libA.dart', content: '''
 library lib_a;
 class A {}
@@ -655,7 +655,7 @@
     expect(filesHighlights[pkgFile], isNotEmpty);
   }
 
-  test_afterAnalysis_sdkFile() async {
+  Future<void> test_afterAnalysis_sdkFile() async {
     String file = convertPath('/sdk/lib/core/core.dart');
     addTestFile('// no matter');
     createProject();
@@ -669,7 +669,7 @@
     expect(filesHighlights[file], isNotEmpty);
   }
 
-  test_beforeAnalysis() async {
+  Future<void> test_beforeAnalysis() async {
     addTestFile('int V = 42;');
     createProject();
     // subscribe
@@ -679,7 +679,7 @@
     expect(filesHighlights[testFile], isNotEmpty);
   }
 
-  test_sentToPlugins() async {
+  Future<void> test_sentToPlugins() async {
     addTestFile('int V = 42;');
     createProject();
     // subscribe
diff --git a/pkg/analysis_server/test/domain_completion_test.dart b/pkg/analysis_server/test/domain_completion_test.dart
index 02c722e..531eedb 100644
--- a/pkg/analysis_server/test/domain_completion_test.dart
+++ b/pkg/analysis_server/test/domain_completion_test.dart
@@ -21,7 +21,7 @@
 import 'domain_completion_util.dart';
 import 'mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CompletionDomainHandlerGetSuggestionsTest);
     defineReflectiveTests(CompletionDomainHandlerListTokenDetailsTest);
@@ -31,7 +31,7 @@
 @reflectiveTest
 class CompletionDomainHandlerGetSuggestionsTest
     extends AbstractCompletionDomainTest {
-  test_ArgumentList_constructor_named_fieldFormalParam() async {
+  Future<void> test_ArgumentList_constructor_named_fieldFormalParam() async {
     // https://github.com/dart-lang/sdk/issues/31023
     addTestFile('''
 main() { new A(field: ^);}
@@ -42,7 +42,7 @@
     await getSuggestions();
   }
 
-  test_ArgumentList_constructor_named_param_label() async {
+  Future<void> test_ArgumentList_constructor_named_param_label() async {
     addTestFile('main() { new A(^);}'
         'class A { A({one, two}) {} }');
     await getSuggestions();
@@ -53,7 +53,7 @@
     expect(suggestions, hasLength(2));
   }
 
-  test_ArgumentList_factory_named_param_label() async {
+  Future<void> test_ArgumentList_factory_named_param_label() async {
     addTestFile('main() { new A(^);}'
         'class A { factory A({one, two}) => null; }');
     await getSuggestions();
@@ -64,7 +64,7 @@
     expect(suggestions, hasLength(2));
   }
 
-  test_ArgumentList_imported_function_named_param() async {
+  Future<void> test_ArgumentList_imported_function_named_param() async {
     addTestFile('main() { int.parse("16", ^);}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.NAMED_ARGUMENT, 'radix: ',
@@ -74,7 +74,7 @@
     expect(suggestions, hasLength(2));
   }
 
-  test_ArgumentList_imported_function_named_param1() async {
+  Future<void> test_ArgumentList_imported_function_named_param1() async {
     addTestFile('main() { foo(o^);} foo({one, two}) {}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.NAMED_ARGUMENT, 'one: ',
@@ -84,7 +84,7 @@
     expect(suggestions, hasLength(2));
   }
 
-  test_ArgumentList_imported_function_named_param2() async {
+  Future<void> test_ArgumentList_imported_function_named_param2() async {
     addTestFile('mainx() {A a = new A(); a.foo(one: 7, ^);}'
         'class A { foo({one, two}) {} }');
     await getSuggestions();
@@ -93,7 +93,7 @@
     expect(suggestions, hasLength(1));
   }
 
-  test_ArgumentList_imported_function_named_param_label1() async {
+  Future<void> test_ArgumentList_imported_function_named_param_label1() async {
     addTestFile('main() { int.parse("16", r^: 16);}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.NAMED_ARGUMENT, 'radix',
@@ -103,7 +103,7 @@
     expect(suggestions, hasLength(2));
   }
 
-  test_ArgumentList_imported_function_named_param_label3() async {
+  Future<void> test_ArgumentList_imported_function_named_param_label3() async {
     addTestFile('main() { int.parse("16", ^: 16);}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.NAMED_ARGUMENT, 'radix: ',
@@ -113,7 +113,7 @@
     expect(suggestions, hasLength(2));
   }
 
-  test_catch() async {
+  Future<void> test_catch() async {
     addTestFile('main() {try {} ^}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.KEYWORD, 'on',
@@ -125,7 +125,7 @@
     expect(suggestions, hasLength(3));
   }
 
-  test_catch2() async {
+  Future<void> test_catch2() async {
     addTestFile('main() {try {} on Foo {} ^}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.KEYWORD, 'on',
@@ -143,7 +143,7 @@
     });
   }
 
-  test_catch3() async {
+  Future<void> test_catch3() async {
     addTestFile('main() {try {} catch (e) {} finally {} ^}');
     await getSuggestions();
     assertNoResult('on');
@@ -158,7 +158,7 @@
     });
   }
 
-  test_catch4() async {
+  Future<void> test_catch4() async {
     addTestFile('main() {try {} finally {} ^}');
     await getSuggestions();
     assertNoResult('on');
@@ -173,7 +173,7 @@
     });
   }
 
-  test_catch5() async {
+  Future<void> test_catch5() async {
     addTestFile('main() {try {} ^ finally {}}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.KEYWORD, 'on',
@@ -183,7 +183,7 @@
     expect(suggestions, hasLength(2));
   }
 
-  test_constructor() async {
+  Future<void> test_constructor() async {
     addTestFile('class A {bool foo; A() : ^;}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.KEYWORD, 'super',
@@ -192,7 +192,7 @@
         relevance: DART_RELEVANCE_LOCAL_FIELD);
   }
 
-  test_constructor2() async {
+  Future<void> test_constructor2() async {
     addTestFile('class A {bool foo; A() : s^;}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.KEYWORD, 'super',
@@ -201,7 +201,7 @@
         relevance: DART_RELEVANCE_LOCAL_FIELD);
   }
 
-  test_constructor3() async {
+  Future<void> test_constructor3() async {
     addTestFile('class A {bool foo; A() : a=7,^;}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.KEYWORD, 'super',
@@ -210,7 +210,7 @@
         relevance: DART_RELEVANCE_LOCAL_FIELD);
   }
 
-  test_constructor4() async {
+  Future<void> test_constructor4() async {
     addTestFile('class A {bool foo; A() : a=7,s^;}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.KEYWORD, 'super',
@@ -219,7 +219,7 @@
         relevance: DART_RELEVANCE_LOCAL_FIELD);
   }
 
-  test_constructor5() async {
+  Future<void> test_constructor5() async {
     addTestFile('class A {bool foo; A() : a=7,s^}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.KEYWORD, 'super',
@@ -228,7 +228,7 @@
         relevance: DART_RELEVANCE_LOCAL_FIELD);
   }
 
-  test_constructor6() async {
+  Future<void> test_constructor6() async {
     addTestFile('class A {bool foo; A() : a=7,^ void bar() {}}');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.KEYWORD, 'super',
@@ -237,7 +237,7 @@
         relevance: DART_RELEVANCE_LOCAL_FIELD);
   }
 
-  test_html() {
+  Future<void> test_html() {
     //
     // We no longer support the analysis of non-dart files.
     //
@@ -252,7 +252,7 @@
     });
   }
 
-  test_import_uri_with_trailing() {
+  Future<void> test_import_uri_with_trailing() {
     final filePath = '/project/bin/testA.dart';
     final incompleteImportText = toUriStr('/project/bin/t');
     newFile(filePath, content: 'library libA;');
@@ -268,7 +268,7 @@
     });
   }
 
-  test_imports() {
+  Future<void> test_imports() {
     addTestFile('''
       import 'dart:html';
       main() {^}
@@ -284,7 +284,7 @@
     });
   }
 
-  test_imports_aborted_new_request() async {
+  Future<void> test_imports_aborted_new_request() async {
     addTestFile('''
         class foo { }
         c^''');
@@ -325,7 +325,7 @@
   }
 
   @failingTest
-  test_imports_aborted_source_changed() async {
+  Future<void> test_imports_aborted_source_changed() async {
     // TODO(brianwilkerson) Figure out whether this test makes sense when
     // running the new driver. It waits for an initial empty notification then
     // waits for a new notification. But I think that under the driver we only
@@ -359,7 +359,7 @@
     expect(suggestions, hasLength(0));
   }
 
-  test_imports_incremental() async {
+  Future<void> test_imports_incremental() async {
     addTestFile('''library foo;
       e^
       import "dart:async";
@@ -382,7 +382,7 @@
     assertNoResult('library');
   }
 
-  test_imports_partial() async {
+  Future<void> test_imports_partial() async {
     addTestFile('''^
       import "package:foo/foo.dart";
       import "package:bar/bar.dart";
@@ -423,7 +423,7 @@
     assertNoResult('extends');
   }
 
-  test_imports_prefixed() {
+  Future<void> test_imports_prefixed() {
     addTestFile('''
       import 'dart:html' as foo;
       main() {^}
@@ -439,7 +439,7 @@
     });
   }
 
-  test_imports_prefixed2() {
+  Future<void> test_imports_prefixed2() {
     addTestFile('''
       import 'dart:html' as foo;
       main() {foo.^}
@@ -452,7 +452,7 @@
     });
   }
 
-  test_inComment_block_beforeNode() async {
+  Future<void> test_inComment_block_beforeNode() async {
     addTestFile('''
   main(aaa, bbb) {
     /* text ^ */
@@ -463,7 +463,7 @@
     expect(suggestions, isEmpty);
   }
 
-  test_inComment_endOfLine_beforeNode() async {
+  Future<void> test_inComment_endOfLine_beforeNode() async {
     addTestFile('''
   main(aaa, bbb) {
     // text ^
@@ -474,7 +474,7 @@
     expect(suggestions, isEmpty);
   }
 
-  test_inComment_endOfLine_beforeToken() async {
+  Future<void> test_inComment_endOfLine_beforeToken() async {
     addTestFile('''
   main(aaa, bbb) {
     // text ^
@@ -484,7 +484,7 @@
     expect(suggestions, isEmpty);
   }
 
-  test_inDartDoc1() async {
+  Future<void> test_inDartDoc1() async {
     addTestFile('''
   /// ^
   main(aaa, bbb) {}
@@ -493,7 +493,7 @@
     expect(suggestions, isEmpty);
   }
 
-  test_inDartDoc2() async {
+  Future<void> test_inDartDoc2() async {
     addTestFile('''
   /// Some text^
   main(aaa, bbb) {}
@@ -502,7 +502,7 @@
     expect(suggestions, isEmpty);
   }
 
-  test_inDartDoc_reference1() async {
+  Future<void> test_inDartDoc_reference1() async {
     newFile('/testA.dart', content: '''
   part of libA;
   foo(bar) => 0;''');
@@ -521,7 +521,7 @@
     assertHasResult(CompletionSuggestionKind.IDENTIFIER, 'min');
   }
 
-  test_inDartDoc_reference2() async {
+  Future<void> test_inDartDoc_reference2() async {
     addTestFile('''
   /// The [m^]
   main(aaa, bbb) {}
@@ -531,7 +531,7 @@
         relevance: DART_RELEVANCE_LOCAL_FUNCTION);
   }
 
-  test_inherited() {
+  Future<void> test_inherited() {
     addTestFile('''
 class A {
   m() {}
@@ -547,7 +547,7 @@
     });
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = CompletionGetSuggestionsParams('test.dart', 0).toRequest('0');
     var response = await waitResponse(request);
     expect(
@@ -556,7 +556,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request =
         CompletionGetSuggestionsParams(convertPath('/foo/../bar/test.dart'), 0)
             .toRequest('0');
@@ -567,7 +567,7 @@
     );
   }
 
-  test_invocation() {
+  Future<void> test_invocation() {
     addTestFile('class A {b() {}} main() {A a; a.^}');
     return getSuggestions().then((_) {
       expect(replacementOffset, equals(completionOffset));
@@ -576,7 +576,7 @@
     });
   }
 
-  test_invocation_sdk_relevancy_off() {
+  Future<void> test_invocation_sdk_relevancy_off() {
     var originalSorter = DartCompletionManager.contributionSorter;
     var mockSorter = MockRelevancySorter();
     DartCompletionManager.contributionSorter = mockSorter;
@@ -590,7 +590,7 @@
     });
   }
 
-  test_invocation_sdk_relevancy_on() {
+  Future<void> test_invocation_sdk_relevancy_on() {
     addTestFile('main() {Map m; m.^}');
     return getSuggestions().then((_) {
       // Assert that the CommonUsageComputer is working
@@ -599,7 +599,7 @@
     });
   }
 
-  test_invocation_withTrailingStmt() {
+  Future<void> test_invocation_withTrailingStmt() {
     addTestFile('class A {b() {}} main() {A a; a.^ int x = 7;}');
     return getSuggestions().then((_) {
       expect(replacementOffset, equals(completionOffset));
@@ -608,7 +608,7 @@
     });
   }
 
-  test_is_asPrefixedIdentifierStart() async {
+  Future<void> test_is_asPrefixedIdentifierStart() async {
     addTestFile('''
 class A { var isVisible;}
 main(A p) { var v1 = p.is^; }''');
@@ -617,7 +617,7 @@
         relevance: DART_RELEVANCE_DEFAULT);
   }
 
-  test_keyword() {
+  Future<void> test_keyword() {
     addTestFile('library A; cl^');
     return getSuggestions().then((_) {
       expect(replacementOffset, equals(completionOffset - 2));
@@ -629,7 +629,7 @@
     });
   }
 
-  test_local_implicitCreation() async {
+  Future<void> test_local_implicitCreation() async {
     addTestFile('''
 class A {
   A();
@@ -655,7 +655,7 @@
         elementKind: ElementKind.CONSTRUCTOR);
   }
 
-  test_local_named_constructor() {
+  Future<void> test_local_named_constructor() {
     addTestFile('class A {A.c(); x() {new A.^}}');
     return getSuggestions().then((_) {
       expect(replacementOffset, equals(completionOffset));
@@ -665,7 +665,7 @@
     });
   }
 
-  test_local_override() {
+  Future<void> test_local_override() {
     newFile('/project/bin/a.dart', content: 'class A {m() {}}');
     addTestFile('''
 import 'a.dart';
@@ -682,7 +682,7 @@
     });
   }
 
-  test_local_shadowClass() async {
+  Future<void> test_local_shadowClass() async {
     addTestFile('''
 class A {
   A();
@@ -708,7 +708,7 @@
     assertNoResult('A.named', elementKind: ElementKind.CONSTRUCTOR);
   }
 
-  test_locals() {
+  Future<void> test_locals() {
     addTestFile('class A {var a; x() {var b;^}} class DateTime { }');
     return getSuggestions().then((_) {
       expect(replacementOffset, equals(completionOffset));
@@ -726,7 +726,7 @@
     });
   }
 
-  test_offset_past_eof() async {
+  Future<void> test_offset_past_eof() async {
     addTestFile('main() { }', offset: 300);
     Request request = CompletionGetSuggestionsParams(testFile, completionOffset)
         .toRequest('0');
@@ -735,7 +735,7 @@
     expect(response.error.code, RequestErrorCode.INVALID_PARAMETER);
   }
 
-  test_overrides() {
+  Future<void> test_overrides() {
     newFile('/project/bin/a.dart', content: 'class A {m() {}}');
     addTestFile('''
 import 'a.dart';
@@ -749,7 +749,7 @@
     });
   }
 
-  test_partFile() {
+  Future<void> test_partFile() {
     newFile('/project/bin/a.dart', content: '''
       library libA;
       import 'dart:html';
@@ -772,7 +772,7 @@
     });
   }
 
-  test_partFile2() {
+  Future<void> test_partFile2() {
     newFile('/project/bin/a.dart', content: '''
       part of libA;
       class A { }''');
@@ -795,7 +795,7 @@
     });
   }
 
-  test_sentToPlugins() async {
+  Future<void> test_sentToPlugins() async {
     addTestFile('''
       void main() {
         ^
@@ -816,7 +816,7 @@
         selectionOffset: 3);
   }
 
-  test_simple() {
+  Future<void> test_simple() {
     addTestFile('''
       void main() {
         ^
@@ -832,7 +832,7 @@
     });
   }
 
-  test_static() {
+  Future<void> test_static() {
     addTestFile('class A {static b() {} c() {}} main() {A.^}');
     return getSuggestions().then((_) {
       expect(replacementOffset, equals(completionOffset));
@@ -842,7 +842,7 @@
     });
   }
 
-  test_topLevel() {
+  Future<void> test_topLevel() {
     addTestFile('''
       typedef foo();
       var test = '';
@@ -879,7 +879,7 @@
     testFileUri = toUriStr(testFile);
   }
 
-  test_classDeclaration() async {
+  Future<void> test_classDeclaration() async {
     await expectTokens('''
 class A {}
 class B extends A {}
@@ -921,7 +921,7 @@
     ]);
   }
 
-  test_genericType() async {
+  Future<void> test_genericType() async {
     await expectTokens('''
 List<int> x = null;
 ''', [
@@ -941,7 +941,7 @@
     ]);
   }
 
-  test_getterInvocation() async {
+  Future<void> test_getterInvocation() async {
     await expectTokens('''
 var x = 'a'.length;
 ''', [
@@ -958,7 +958,7 @@
     ]);
   }
 
-  test_literal_bool() async {
+  Future<void> test_literal_bool() async {
     await expectTokens('''
 var x = true;
 ''', [
@@ -972,7 +972,7 @@
     ]);
   }
 
-  test_literal_double() async {
+  Future<void> test_literal_double() async {
     await expectTokens('''
 var x = 3.4;
 ''', [
@@ -987,7 +987,7 @@
     ]);
   }
 
-  test_literal_int() async {
+  Future<void> test_literal_int() async {
     await expectTokens('''
 var x = 7;
 ''', [
@@ -1000,7 +1000,7 @@
     ]);
   }
 
-  test_literal_list() async {
+  Future<void> test_literal_list() async {
     await expectTokens('''
 var x = <int>[];
 ''', [
@@ -1019,7 +1019,7 @@
     ]);
   }
 
-  test_literal_map() async {
+  Future<void> test_literal_map() async {
     await expectTokens('''
 var x = <int, int>{};
 ''', [
@@ -1042,7 +1042,7 @@
     ]);
   }
 
-  test_literal_null() async {
+  Future<void> test_literal_null() async {
     await expectTokens('''
 var x = null;
 ''', [
@@ -1054,7 +1054,7 @@
     ]);
   }
 
-  test_literal_set() async {
+  Future<void> test_literal_set() async {
     await expectTokens('''
 var x = <int>{};
 ''', [
@@ -1073,7 +1073,7 @@
     ]);
   }
 
-  test_literal_string() async {
+  Future<void> test_literal_string() async {
     await expectTokens('''
 var x = 'a';
 ''', [
@@ -1088,7 +1088,7 @@
     ]);
   }
 
-  test_methodDeclaration() async {
+  Future<void> test_methodDeclaration() async {
     await expectTokens('''
 class A {
   String c(int x, int y) {}
@@ -1123,7 +1123,7 @@
     ]);
   }
 
-  test_methodInvocation() async {
+  Future<void> test_methodInvocation() async {
     await expectTokens('''
 var x = 'radar'.indexOf('r', 1);
 ''', [
@@ -1147,7 +1147,7 @@
     ]);
   }
 
-  test_mixinDeclaration() async {
+  Future<void> test_mixinDeclaration() async {
     await expectTokens('''
 class A {}
 class B {}
@@ -1179,7 +1179,7 @@
     ]);
   }
 
-  test_parameterReference() async {
+  Future<void> test_parameterReference() async {
     await expectTokens('''
 int f(int p) {
   return p;
@@ -1207,7 +1207,7 @@
     ]);
   }
 
-  test_topLevelVariable_withDocComment() async {
+  Future<void> test_topLevelVariable_withDocComment() async {
     await expectTokens('''
 /// Doc comment [x] with reference.
 int x;
diff --git a/pkg/analysis_server/test/domain_completion_util.dart b/pkg/analysis_server/test/domain_completion_util.dart
index d281fcb..c6f4ef4 100644
--- a/pkg/analysis_server/test/domain_completion_util.dart
+++ b/pkg/analysis_server/test/domain_completion_util.dart
@@ -104,7 +104,7 @@
   }
 
   @override
-  processNotification(Notification notification) async {
+  Future<void> processNotification(Notification notification) async {
     if (notification.event == COMPLETION_RESULTS) {
       var params = CompletionResultsParams.fromNotification(notification);
       String id = params.id;
diff --git a/pkg/analysis_server/test/domain_diagnostic_test.dart b/pkg/analysis_server/test/domain_diagnostic_test.dart
index 149cee9..41135d6 100644
--- a/pkg/analysis_server/test/domain_diagnostic_test.dart
+++ b/pkg/analysis_server/test/domain_diagnostic_test.dart
@@ -9,7 +9,7 @@
 
 import 'analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DiagnosticDomainTest);
   });
@@ -25,7 +25,7 @@
     server.handlers = [handler];
   }
 
-  test_getDiagnostics() async {
+  Future<void> test_getDiagnostics() async {
     newFile('/project/pubspec.yaml', content: 'name: project');
     newFile('/project/bin/test.dart', content: 'main() {}');
 
@@ -48,7 +48,7 @@
     expect(context.workItemQueueLength, isNotNull);
   }
 
-  test_getDiagnostics_noRoot() async {
+  Future<void> test_getDiagnostics_noRoot() async {
     var request = DiagnosticGetDiagnosticsParams().toRequest('0');
     var response = handler.handleRequest(request);
     var result = DiagnosticGetDiagnosticsResult.fromResponse(response);
diff --git a/pkg/analysis_server/test/domain_edit_dartfix_test.dart b/pkg/analysis_server/test/domain_edit_dartfix_test.dart
index 7a71894..c4f1364 100644
--- a/pkg/analysis_server/test/domain_edit_dartfix_test.dart
+++ b/pkg/analysis_server/test/domain_edit_dartfix_test.dart
@@ -12,7 +12,7 @@
 
 import 'analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(EditDartfixDomainHandlerTest);
   });
@@ -80,7 +80,7 @@
     testFile = resourceProvider.convertPath('/project/lib/fileToBeFixed.dart');
   }
 
-  test_collection_if_elements() async {
+  Future<void> test_collection_if_elements() async {
     addTestFile('''
 f(bool b) {
   return ['a', b ? 'c' : 'd', 'e'];
@@ -98,7 +98,7 @@
 ''');
   }
 
-  test_excludedFix_invalid() async {
+  Future<void> test_excludedFix_invalid() async {
     addTestFile('''
 const double myDouble = 42.0;
     ''');
@@ -108,7 +108,7 @@
     expect(result.error, isNotNull);
   }
 
-  test_excludedSource() async {
+  Future<void> test_excludedSource() async {
     // Add analysis options to exclude the lib directory then reanalyze
     newFile('/project/analysis_options.yaml', content: '''
 analyzer:
@@ -127,7 +127,7 @@
     expect(result.edits, hasLength(0));
   }
 
-  test_fixNamedConstructorTypeArgs() async {
+  Future<void> test_fixNamedConstructorTypeArgs() async {
     addTestFile('''
 class A<T> {
   A.from(Object obj);
@@ -151,7 +151,7 @@
     ''');
   }
 
-  test_includedFix_invalid() async {
+  Future<void> test_includedFix_invalid() async {
     addTestFile('''
 const double myDouble = 42.0;
     ''');
@@ -161,7 +161,7 @@
     expect(result.error, isNotNull);
   }
 
-  test_nonNullable() async {
+  Future<void> test_nonNullable() async {
     createAnalysisOptionsFile(experiments: ['non-nullable']);
     addTestFile('''
 int f(int i) => 0;
@@ -184,7 +184,7 @@
 ''');
   }
 
-  test_nonNullable_analysisOptions_created() async {
+  Future<void> test_nonNullable_analysisOptions_created() async {
     // Add pubspec for nnbd migration to detect
     newFile('/project/pubspec.yaml', content: '''
 name: testnnbd
@@ -203,7 +203,7 @@
 ''');
   }
 
-  test_nonNullable_analysisOptions_experimentsAdded() async {
+  Future<void> test_nonNullable_analysisOptions_experimentsAdded() async {
     String originalOptions = '''
 analyzer:
   something:
@@ -231,7 +231,7 @@
 ''');
   }
 
-  test_nonNullable_analysisOptions_nnbdAdded() async {
+  Future<void> test_nonNullable_analysisOptions_nnbdAdded() async {
     String originalOptions = '''
 analyzer:
   enable-experiment:
@@ -256,7 +256,7 @@
 ''');
   }
 
-  test_partFile() async {
+  Future<void> test_partFile() async {
     newFile('/project/lib/lib.dart', content: '''
 library lib2;
 part 'fileToBeFixed.dart';
@@ -278,7 +278,7 @@
     ''');
   }
 
-  test_partFile_loose() async {
+  Future<void> test_partFile_loose() async {
     addTestFile('''
 part of lib2;
 const double myDouble = 42.0;
@@ -296,7 +296,7 @@
     ''');
   }
 
-  test_pedantic() async {
+  Future<void> test_pedantic() async {
     addTestFile('main(List args) { if (args.length == 0) { } }');
     createProject();
     EditDartfixResult result = await performFix(pedantic: true);
@@ -306,7 +306,7 @@
     expectEdits(result.edits, 'main(List args) { if (args.isEmpty) { } }');
   }
 
-  test_preferEqualForDefaultValues() async {
+  Future<void> test_preferEqualForDefaultValues() async {
     // Add analysis options to enable ui as code
     addTestFile('f({a: 1}) { }');
     createProject();
@@ -318,7 +318,7 @@
     expectEdits(result.edits, 'f({a = 1}) { }');
   }
 
-  test_preferForElementsToMapFromIterable() async {
+  Future<void> test_preferForElementsToMapFromIterable() async {
     addTestFile('''
 var m =
   Map<int, int>.fromIterable([1, 2, 3], key: (i) => i, value: (i) => i * 2);
@@ -335,7 +335,7 @@
     ''');
   }
 
-  test_preferIfElementsToConditionalExpressions() async {
+  Future<void> test_preferIfElementsToConditionalExpressions() async {
     addTestFile('''
 f(bool b) => ['a', b ? 'c' : 'd', 'e'];
     ''');
@@ -350,7 +350,7 @@
     ''');
   }
 
-  test_preferIntLiterals() async {
+  Future<void> test_preferIntLiterals() async {
     addTestFile('''
 const double myDouble = 42.0;
     ''');
@@ -364,7 +364,7 @@
     ''');
   }
 
-  test_preferIsEmpty() async {
+  Future<void> test_preferIsEmpty() async {
     addTestFile('main(List<String> args) { if (args.length == 0) { } }');
     createProject();
     EditDartfixResult result =
@@ -376,7 +376,7 @@
         result.edits, 'main(List<String> args) { if (args.isEmpty) { } }');
   }
 
-  test_preferMixin() async {
+  Future<void> test_preferMixin() async {
     addTestFile('''
 class A {}
 class B extends A {}
@@ -394,7 +394,7 @@
     ''');
   }
 
-  test_preferSingleQuotes() async {
+  Future<void> test_preferSingleQuotes() async {
     addTestFile('''
 var l = [
   "abc",
@@ -424,7 +424,7 @@
 ''');
   }
 
-  test_preferSpreadCollections() async {
+  Future<void> test_preferSpreadCollections() async {
     addTestFile('''
 var l1 = ['b'];
 var l2 = ['a']..addAll(l1);
diff --git a/pkg/analysis_server/test/domain_execution_test.dart b/pkg/analysis_server/test/domain_execution_test.dart
index b98ed4f..eeb47aa 100644
--- a/pkg/analysis_server/test/domain_execution_test.dart
+++ b/pkg/analysis_server/test/domain_execution_test.dart
@@ -17,7 +17,7 @@
 import 'analysis_abstract.dart';
 import 'mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ExecutionDomainTest);
   });
@@ -176,7 +176,7 @@
     super.tearDown();
   }
 
-  test_getSuggestions() async {
+  Future<void> test_getSuggestions() async {
     var code = r'''
 class A {
   int foo;
diff --git a/pkg/analysis_server/test/domain_server_test.dart b/pkg/analysis_server/test/domain_server_test.dart
index ab39270..012fb35 100644
--- a/pkg/analysis_server/test/domain_server_test.dart
+++ b/pkg/analysis_server/test/domain_server_test.dart
@@ -16,7 +16,7 @@
 import 'constants.dart';
 import 'mocks.dart';
 
-main() {
+void main() {
   AnalysisServer server;
   ServerDomainHandler handler;
   MockServerChannel serverChannel;
diff --git a/pkg/analysis_server/test/edit/assists_test.dart b/pkg/analysis_server/test/edit/assists_test.dart
index 7f61e9c..aec8477 100644
--- a/pkg/analysis_server/test/edit/assists_test.dart
+++ b/pkg/analysis_server/test/edit/assists_test.dart
@@ -18,7 +18,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AssistsTest);
   });
@@ -28,12 +28,12 @@
 class AssistsTest extends AbstractAnalysisTest {
   List<SourceChange> changes;
 
-  prepareAssists(String search, [int length = 0]) async {
+  Future<void> prepareAssists(String search, [int length = 0]) async {
     int offset = findOffset(search);
     await prepareAssistsAt(offset, length);
   }
 
-  prepareAssistsAt(int offset, int length) async {
+  Future<void> prepareAssistsAt(int offset, int length) async {
     Request request =
         EditGetAssistsParams(testFile, offset, length).toRequest('0');
     Response response = await waitResponse(request);
@@ -48,7 +48,7 @@
     handler = EditDomainHandler(server);
   }
 
-  test_fromPlugins() async {
+  Future<void> test_fromPlugins() async {
     PluginInfo info = DiscoveredPluginInfo('a', 'b', 'c', null, null);
     String message = 'From a plugin';
     plugin.PrioritizedSourceChange change = plugin.PrioritizedSourceChange(
@@ -68,7 +68,7 @@
     _assertHasChange(message, 'xmain() {}');
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = EditGetAssistsParams('test.dart', 0, 0).toRequest('0');
     var response = await waitResponse(request);
     expect(
@@ -77,7 +77,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request =
         EditGetAssistsParams(convertPath('/foo/../bar/test.dart'), 0, 0)
             .toRequest('0');
@@ -88,7 +88,7 @@
     );
   }
 
-  test_removeTypeAnnotation() async {
+  Future<void> test_removeTypeAnnotation() async {
     addTestFile('''
 main() {
   int v = 1;
@@ -103,7 +103,7 @@
 ''');
   }
 
-  test_splitVariableDeclaration() async {
+  Future<void> test_splitVariableDeclaration() async {
     addTestFile('''
 main() {
   int v = 1;
@@ -119,7 +119,7 @@
 ''');
   }
 
-  test_surroundWithIf() async {
+  Future<void> test_surroundWithIf() async {
     addTestFile('''
 main() {
   print(1);
diff --git a/pkg/analysis_server/test/edit/fixes_test.dart b/pkg/analysis_server/test/edit/fixes_test.dart
index e53025e..cf10976 100644
--- a/pkg/analysis_server/test/edit/fixes_test.dart
+++ b/pkg/analysis_server/test/edit/fixes_test.dart
@@ -18,7 +18,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FixesTest);
   });
@@ -32,7 +32,7 @@
     handler = EditDomainHandler(server);
   }
 
-  test_fixUndefinedClass() async {
+  Future<void> test_fixUndefinedClass() async {
     createProject();
     addTestFile('''
 main() {
@@ -52,7 +52,7 @@
     expect(fixes[2].message, matches('Create mixin'));
   }
 
-  test_fromPlugins() async {
+  Future<void> test_fromPlugins() async {
     PluginInfo info = DiscoveredPluginInfo('a', 'b', 'c', null, null);
     plugin.AnalysisErrorFixes fixes = plugin.AnalysisErrorFixes(AnalysisError(
         AnalysisErrorSeverity.ERROR,
@@ -73,7 +73,7 @@
     expect(errorFixes, hasLength(1));
   }
 
-  test_hasFixes() async {
+  Future<void> test_hasFixes() async {
     createProject();
     addTestFile('''
 foo() {
@@ -99,7 +99,7 @@
     }
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = EditGetFixesParams('test.dart', 0).toRequest('0');
     var response = await waitResponse(request);
     expect(
@@ -108,7 +108,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request = EditGetFixesParams(convertPath('/foo/../bar/test.dart'), 0)
         .toRequest('0');
     var response = await waitResponse(request);
@@ -118,7 +118,7 @@
     );
   }
 
-  test_overlayOnlyFile() async {
+  Future<void> test_overlayOnlyFile() async {
     createProject();
     testCode = '''
 main() {
@@ -133,7 +133,7 @@
     _isSyntacticErrorWithSingleFix(errorFixes[0]);
   }
 
-  test_suggestImportFromDifferentAnalysisRoot() async {
+  Future<void> test_suggestImportFromDifferentAnalysisRoot() async {
     newFolder('/aaa');
     newFile('/aaa/.packages', content: '''
 aaa:${toUri('/aaa/lib')}
diff --git a/pkg/analysis_server/test/edit/format_test.dart b/pkg/analysis_server/test/edit/format_test.dart
index aa3c259..82fccdc 100644
--- a/pkg/analysis_server/test/edit/format_test.dart
+++ b/pkg/analysis_server/test/edit/format_test.dart
@@ -14,7 +14,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FormatTest);
   });
diff --git a/pkg/analysis_server/test/edit/organize_directives_test.dart b/pkg/analysis_server/test/edit/organize_directives_test.dart
index cd8803f..f565197 100644
--- a/pkg/analysis_server/test/edit/organize_directives_test.dart
+++ b/pkg/analysis_server/test/edit/organize_directives_test.dart
@@ -14,7 +14,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(OrganizeDirectivesTest);
   });
@@ -63,7 +63,7 @@
         response, isResponseFailure('0', RequestErrorCode.FILE_NOT_ANALYZED));
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = EditOrganizeDirectivesParams('test.dart').toRequest('0');
     var response = await waitResponse(request);
     expect(
@@ -72,7 +72,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request =
         EditOrganizeDirectivesParams(convertPath('/foo/../bar/test.dart'))
             .toRequest('0');
diff --git a/pkg/analysis_server/test/edit/postfix_completion_test.dart b/pkg/analysis_server/test/edit/postfix_completion_test.dart
index e270972..21bafc6 100644
--- a/pkg/analysis_server/test/edit/postfix_completion_test.dart
+++ b/pkg/analysis_server/test/edit/postfix_completion_test.dart
@@ -12,7 +12,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(PostfixCompletionTest);
   });
@@ -29,7 +29,7 @@
     handler = EditDomainHandler(server);
   }
 
-  test_for() async {
+  Future<void> test_for() async {
     addTestFile('''
 main() {
   [].for
@@ -46,7 +46,7 @@
 ''');
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request =
         EditGetPostfixCompletionParams('test.dart', '.for', 0).toRequest('0');
     var response = await waitResponse(request);
@@ -56,7 +56,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request = EditGetPostfixCompletionParams(
             convertPath('/foo/../bar/test.dart'), '.for', 0)
         .toRequest('0');
@@ -88,7 +88,7 @@
     fail('Expected to find |$message| but got: ' + change.message);
   }
 
-  _prepareCompletion(String key,
+  Future<void> _prepareCompletion(String key,
       {bool atStart = false, bool atEnd = false, int delta = 0}) async {
     int offset = findOffset(key);
     String src = testCode.replaceFirst(key, '', offset);
@@ -96,7 +96,7 @@
     await _prepareCompletionAt(offset, key);
   }
 
-  _prepareCompletionAt(int offset, String key) async {
+  Future<void> _prepareCompletionAt(int offset, String key) async {
     var params = EditGetPostfixCompletionParams(testFile, key, offset);
     var request =
         Request('0', 'edit.isPostfixCompletionApplicable', params.toJson());
diff --git a/pkg/analysis_server/test/edit/refactoring_test.dart b/pkg/analysis_server/test/edit/refactoring_test.dart
index dc2284b..60d3d2c 100644
--- a/pkg/analysis_server/test/edit/refactoring_test.dart
+++ b/pkg/analysis_server/test/edit/refactoring_test.dart
@@ -15,7 +15,7 @@
 import '../mocks.dart';
 import '../src/utilities/mock_packages.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertGetterMethodToMethodTest);
     defineReflectiveTests(ConvertMethodToGetterTest);
@@ -40,7 +40,7 @@
 
 @reflectiveTest
 class ConvertGetterMethodToMethodTest extends _AbstractGetRefactoring_Test {
-  test_function() {
+  Future<void> test_function() {
     addTestFile('''
 int get test => 42;
 main() {
@@ -59,7 +59,7 @@
 ''');
   }
 
-  test_init_fatalError_notExplicit() {
+  Future<void> test_init_fatalError_notExplicit() {
     addTestFile('''
 int test = 42;
 main() {
@@ -76,7 +76,7 @@
     });
   }
 
-  test_method() {
+  Future<void> test_method() {
     addTestFile('''
 class A {
   int get test => 1;
@@ -135,7 +135,7 @@
 
 @reflectiveTest
 class ConvertMethodToGetterTest extends _AbstractGetRefactoring_Test {
-  test_function() {
+  Future<void> test_function() {
     addTestFile('''
 int test() => 42;
 main() {
@@ -154,7 +154,7 @@
 ''');
   }
 
-  test_init_fatalError_hasParameters() {
+  Future<void> test_init_fatalError_hasParameters() {
     addTestFile('''
 int test(p) => p + 1;
 main() {
@@ -171,7 +171,7 @@
     });
   }
 
-  test_init_fatalError_notExecutableElement() {
+  Future<void> test_init_fatalError_notExecutableElement() {
     addTestFile('''
 main() {
   int abc = 1;
@@ -188,7 +188,7 @@
     });
   }
 
-  test_method() {
+  Future<void> test_method() {
     addTestFile('''
 class A {
   int test() => 1;
@@ -277,7 +277,7 @@
     super.tearDown();
   }
 
-  test_analysis_onlyOneFile() async {
+  Future<void> test_analysis_onlyOneFile() async {
     shouldWaitForFullAnalysis = false;
     newFile(join(testFolder, 'other.dart'), content: r'''
 foo(int myName) {}
@@ -297,7 +297,7 @@
     expect(feedback.names, contains('myName'));
   }
 
-  test_coveringExpressions() {
+  Future<void> test_coveringExpressions() {
     addTestFile('''
 main() {
   var v = 111 + 222 + 333;
@@ -317,7 +317,7 @@
     });
   }
 
-  test_extractAll() {
+  Future<void> test_extractAll() {
     addTestFile('''
 main() {
   print(1 + 2);
@@ -335,7 +335,7 @@
 ''');
   }
 
-  test_extractOne() {
+  Future<void> test_extractOne() {
     addTestFile('''
 main() {
   print(1 + 2);
@@ -353,7 +353,7 @@
 ''');
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = EditGetRefactoringParams(
             RefactoringKind.EXTRACT_LOCAL_VARIABLE, 'test.dart', 0, 0, true)
         .toRequest('0');
@@ -364,7 +364,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request = EditGetRefactoringParams(
             RefactoringKind.EXTRACT_LOCAL_VARIABLE,
             convertPath('/foo/../bar/test.dart'),
@@ -379,7 +379,7 @@
     );
   }
 
-  test_names() async {
+  Future<void> test_names() async {
     addTestFile('''
 class TreeItem {}
 TreeItem getSelectedItem() => null;
@@ -396,7 +396,7 @@
     expect(result.change, isNull);
   }
 
-  test_nameWarning() async {
+  Future<void> test_nameWarning() async {
     addTestFile('''
 main() {
   print(1 + 2);
@@ -416,7 +416,7 @@
 ''');
   }
 
-  test_offsetsLengths() {
+  Future<void> test_offsetsLengths() {
     addTestFile('''
 main() {
   print(1 + 2);
@@ -432,7 +432,7 @@
     });
   }
 
-  test_resetOnAnalysisSetChanged_overlay() async {
+  Future<void> test_resetOnAnalysisSetChanged_overlay() async {
     addTestFile('''
 main() {
   print(1 + 2); // 0
@@ -476,7 +476,7 @@
     });
   }
 
-  test_resetOnAnalysisSetChanged_watch_otherFile() async {
+  Future<void> test_resetOnAnalysisSetChanged_watch_otherFile() async {
     String otherFile = join(testFolder, 'other.dart');
     newFile(otherFile, content: '// other 1');
     addTestFile('''
@@ -503,7 +503,7 @@
     expect(test_resetCount, initialResetCount + 1);
   }
 
-  test_resetOnAnalysisSetChanged_watch_thisFile() async {
+  Future<void> test_resetOnAnalysisSetChanged_watch_thisFile() async {
     addTestFile('''
 main() {
   foo(1 + 2);
@@ -540,7 +540,7 @@
     }
   }
 
-  test_serverError_change() {
+  Future<void> test_serverError_change() {
     test_simulateRefactoringException_change = true;
     addTestFile('''
 main() {
@@ -555,7 +555,7 @@
     });
   }
 
-  test_serverError_final() {
+  Future<void> test_serverError_final() {
     test_simulateRefactoringException_final = true;
     addTestFile('''
 main() {
@@ -570,7 +570,7 @@
     });
   }
 
-  test_serverError_init() {
+  Future<void> test_serverError_init() {
     test_simulateRefactoringException_init = true;
     addTestFile('''
 main() {
@@ -593,7 +593,7 @@
   String name = 'res';
   ExtractMethodOptions options;
 
-  test_expression() {
+  Future<void> test_expression() {
     addTestFile('''
 main() {
   print(1 + 2);
@@ -611,7 +611,7 @@
 ''');
   }
 
-  test_expression_hasParameters() {
+  Future<void> test_expression_hasParameters() {
     addTestFile('''
 main() {
   int a = 1;
@@ -633,7 +633,7 @@
 ''');
   }
 
-  test_expression_updateParameters() {
+  Future<void> test_expression_updateParameters() {
     addTestFile('''
 main() {
   int a = 1;
@@ -664,7 +664,7 @@
     });
   }
 
-  test_init_fatalError_invalidStatement() {
+  Future<void> test_init_fatalError_invalidStatement() {
     addTestFile('''
 main(bool b) {
 // start
@@ -686,7 +686,7 @@
     });
   }
 
-  test_long_expression() {
+  Future<void> test_long_expression() {
     addTestFile('''
 main() {
   print(1 +
@@ -706,7 +706,7 @@
 ''');
   }
 
-  test_names() {
+  Future<void> test_names() {
     addTestFile('''
 class TreeItem {}
 TreeItem getSelectedItem() => null;
@@ -722,7 +722,7 @@
     });
   }
 
-  test_offsetsLengths() {
+  Future<void> test_offsetsLengths() {
     addTestFile('''
 class TreeItem {}
 TreeItem getSelectedItem() => null;
@@ -738,7 +738,7 @@
     });
   }
 
-  test_statements() {
+  Future<void> test_statements() {
     addTestFile('''
 main() {
   int a = 1;
@@ -928,7 +928,7 @@
     expect(kinds, contains(RefactoringKind.EXTRACT_WIDGET));
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request =
         EditGetAvailableRefactoringsParams('test.dart', 0, 0).toRequest('0');
     var response = await waitResponse(request);
@@ -938,7 +938,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request = EditGetAvailableRefactoringsParams(
             convertPath('/foo/../bar/test.dart'), 0, 0)
         .toRequest('0');
@@ -1068,7 +1068,7 @@
 
 @reflectiveTest
 class InlineLocalTest extends _AbstractGetRefactoring_Test {
-  test_analysis_onlyOneFile() async {
+  Future<void> test_analysis_onlyOneFile() async {
     shouldWaitForFullAnalysis = false;
     String otherFile = join(testFolder, 'other.dart');
     newFile(otherFile, content: r'''
@@ -1091,7 +1091,7 @@
     expect(feedback.occurrences, 2);
   }
 
-  test_feedback() {
+  Future<void> test_feedback() {
     addTestFile('''
 main() {
   int test = 42;
@@ -1108,7 +1108,7 @@
     });
   }
 
-  test_init_fatalError_notVariable() {
+  Future<void> test_init_fatalError_notVariable() {
     addTestFile('main() {}');
     return getRefactoringResult(() {
       return _sendInlineRequest('main() {}');
@@ -1120,7 +1120,7 @@
     });
   }
 
-  test_OK() {
+  Future<void> test_OK() {
     addTestFile('''
 main() {
   int test = 42;
@@ -1138,7 +1138,7 @@
 ''');
   }
 
-  test_resetOnAnalysisSetChanged() async {
+  Future<void> test_resetOnAnalysisSetChanged() async {
     newFile(join(testFolder, 'other.dart'), content: '// other 1');
     addTestFile('''
 main() {
@@ -1178,7 +1178,7 @@
 class InlineMethodTest extends _AbstractGetRefactoring_Test {
   InlineMethodOptions options = InlineMethodOptions(true, true);
 
-  test_feedback() {
+  Future<void> test_feedback() {
     addTestFile('''
 class A {
   int f;
@@ -1200,7 +1200,7 @@
     });
   }
 
-  test_init_fatalError_noMethod() {
+  Future<void> test_init_fatalError_noMethod() {
     addTestFile('// nothing to inline');
     return getRefactoringResult(() {
       return _sendInlineRequest('// nothing');
@@ -1212,7 +1212,7 @@
     });
   }
 
-  test_method() {
+  Future<void> test_method() {
     addTestFile('''
 class A {
   int f;
@@ -1242,7 +1242,7 @@
 ''');
   }
 
-  test_topLevelFunction() {
+  Future<void> test_topLevelFunction() {
     addTestFile('''
 test(a, b) {
   print(a + b);
@@ -1262,7 +1262,7 @@
 ''');
   }
 
-  test_topLevelFunction_oneInvocation() {
+  Future<void> test_topLevelFunction_oneInvocation() {
     addTestFile('''
 test(a, b) {
   print(a + b);
@@ -1301,7 +1301,7 @@
   MoveFileOptions options;
 
   @failingTest
-  test_OK() {
+  Future<void> test_OK() {
     _fail('The move file refactoring is not supported under the new driver');
     newFile('/project/bin/lib.dart');
     addTestFile('''
@@ -1350,7 +1350,7 @@
     super.tearDown();
   }
 
-  test_cancelPendingRequest() async {
+  Future<void> test_cancelPendingRequest() async {
     addTestFile('''
 main() {
   int test = 0;
@@ -1370,7 +1370,7 @@
     expect(responseB, isResponseSuccess('2'));
   }
 
-  test_class() {
+  Future<void> test_class() {
     addTestFile('''
 class Test {
   Test() {}
@@ -1397,7 +1397,7 @@
 ''');
   }
 
-  test_class_fromFactoryRedirectingConstructor() {
+  Future<void> test_class_fromFactoryRedirectingConstructor() {
     addTestFile('''
 class A {
   A() = Test.named;
@@ -1426,7 +1426,7 @@
     );
   }
 
-  test_class_fromInstanceCreation() {
+  Future<void> test_class_fromInstanceCreation() {
     addTestFile('''
 class Test {
   Test() {}
@@ -1455,7 +1455,7 @@
     );
   }
 
-  test_class_fromInstanceCreation_namedConstructor() {
+  Future<void> test_class_fromInstanceCreation_namedConstructor() {
     addTestFile('''
 class Test {
   Test.named() {}
@@ -1484,7 +1484,7 @@
     );
   }
 
-  test_class_fromInstanceCreation_onNew() {
+  Future<void> test_class_fromInstanceCreation_onNew() {
     addTestFile('''
 class Test {
   Test() {}
@@ -1513,7 +1513,7 @@
     );
   }
 
-  test_class_fromInstanceCreation_onNew_namedConstructor() {
+  Future<void> test_class_fromInstanceCreation_onNew_namedConstructor() {
     addTestFile('''
 class Test {
   Test.named() {}
@@ -1542,7 +1542,7 @@
     );
   }
 
-  test_class_options_fatalError() {
+  Future<void> test_class_options_fatalError() {
     addTestFile('''
 class Test {}
 main() {
@@ -1559,7 +1559,7 @@
     });
   }
 
-  test_class_validateOnly() {
+  Future<void> test_class_validateOnly() {
     addTestFile('''
 class Test {}
 main() {
@@ -1577,7 +1577,7 @@
     });
   }
 
-  test_class_warning() {
+  Future<void> test_class_warning() {
     addTestFile('''
 class Test {}
 main() {
@@ -1613,7 +1613,7 @@
     });
   }
 
-  test_classMember_field() {
+  Future<void> test_classMember_field() {
     addTestFile('''
 class A {
   var test = 0;
@@ -1636,7 +1636,7 @@
 ''');
   }
 
-  test_classMember_field_onFieldFormalParameter() {
+  Future<void> test_classMember_field_onFieldFormalParameter() {
     addTestFile('''
 class A {
   var test = 0;
@@ -1659,7 +1659,7 @@
 ''');
   }
 
-  test_classMember_field_onFieldFormalParameter_named() {
+  Future<void> test_classMember_field_onFieldFormalParameter_named() {
     addTestFile('''
 class A {
   final int test;
@@ -1682,7 +1682,7 @@
 ''');
   }
 
-  test_classMember_getter() {
+  Future<void> test_classMember_getter() {
     addTestFile('''
 class A {
   get test => 0;
@@ -1703,7 +1703,7 @@
 ''');
   }
 
-  test_classMember_method() {
+  Future<void> test_classMember_method() {
     addTestFile('''
 class A {
   test() {}
@@ -1730,7 +1730,7 @@
 ''');
   }
 
-  test_classMember_method_potential() {
+  Future<void> test_classMember_method_potential() {
     addTestFile('''
 class A {
   test() {}
@@ -1757,7 +1757,7 @@
     });
   }
 
-  test_classMember_setter() {
+  Future<void> test_classMember_setter() {
     addTestFile('''
 class A {
   set test(x) {}
@@ -1778,7 +1778,7 @@
 ''');
   }
 
-  test_constructor_fromFactoryRedirectingConstructor() {
+  Future<void> test_constructor_fromFactoryRedirectingConstructor() {
     addTestFile('''
 class A {
   A() = B.test;
@@ -1807,7 +1807,7 @@
     );
   }
 
-  test_constructor_fromInstanceCreation() {
+  Future<void> test_constructor_fromInstanceCreation() {
     addTestFile('''
 class A {
   A.test() {}
@@ -1836,7 +1836,7 @@
     );
   }
 
-  test_feedback() {
+  Future<void> test_feedback() {
     addTestFile('''
 class Test {}
 main() {
@@ -1853,7 +1853,7 @@
     });
   }
 
-  test_function() {
+  Future<void> test_function() {
     addTestFile('''
 test() {}
 main() {
@@ -1872,7 +1872,7 @@
 ''');
   }
 
-  test_importPrefix_add() {
+  Future<void> test_importPrefix_add() {
     addTestFile('''
 import 'dart:math';
 import 'dart:async';
@@ -1900,7 +1900,7 @@
         });
   }
 
-  test_importPrefix_remove() {
+  Future<void> test_importPrefix_remove() {
     addTestFile('''
 import 'dart:math' as test;
 import 'dart:async' as test;
@@ -1928,7 +1928,7 @@
         });
   }
 
-  test_init_fatalError_noElement() {
+  Future<void> test_init_fatalError_noElement() {
     addTestFile('// nothing to rename');
     return getRefactoringResult(() {
       return sendRenameRequest('// nothing', null);
@@ -1940,7 +1940,7 @@
     });
   }
 
-  test_library_libraryDirective() {
+  Future<void> test_library_libraryDirective() {
     addTestFile('''
 library aaa.bbb.ccc;
 ''');
@@ -1951,7 +1951,7 @@
 ''');
   }
 
-  test_library_libraryDirective_name() {
+  Future<void> test_library_libraryDirective_name() {
     addTestFile('''
 library aaa.bbb.ccc;
 ''');
@@ -1962,7 +1962,7 @@
 ''');
   }
 
-  test_library_libraryDirective_nameDot() {
+  Future<void> test_library_libraryDirective_nameDot() {
     addTestFile('''
 library aaa.bbb.ccc;
 ''');
@@ -1973,7 +1973,7 @@
 ''');
   }
 
-  test_library_partOfDirective() {
+  Future<void> test_library_partOfDirective() {
     newFile(join(testFolder, 'my_lib.dart'), content: '''
 library aaa.bbb.ccc;
 part 'test.dart';
@@ -1988,7 +1988,7 @@
 ''');
   }
 
-  test_localVariable() {
+  Future<void> test_localVariable() {
     addTestFile('''
 main() {
   int test = 0;
@@ -2009,7 +2009,7 @@
 ''');
   }
 
-  test_localVariable_finalCheck_shadowError() {
+  Future<void> test_localVariable_finalCheck_shadowError() {
     addTestFile('''
 main() {
   var newName;
@@ -2027,7 +2027,7 @@
     });
   }
 
-  test_reset_afterCreateChange() {
+  Future<void> test_reset_afterCreateChange() {
     test_simulateRefactoringReset_afterCreateChange = true;
     addTestFile('''
 test() {}
@@ -2042,7 +2042,7 @@
     });
   }
 
-  test_reset_afterFinalConditions() {
+  Future<void> test_reset_afterFinalConditions() {
     test_simulateRefactoringReset_afterFinalConditions = true;
     addTestFile('''
 test() {}
@@ -2057,7 +2057,7 @@
     });
   }
 
-  test_reset_afterInitialConditions() {
+  Future<void> test_reset_afterInitialConditions() {
     test_simulateRefactoringReset_afterInitialConditions = true;
     addTestFile('''
 test() {}
@@ -2072,7 +2072,7 @@
     });
   }
 
-  test_resetOnAnalysis() async {
+  Future<void> test_resetOnAnalysis() async {
     addTestFile('''
 main() {
   int initialName = 0;
diff --git a/pkg/analysis_server/test/edit/sort_members_test.dart b/pkg/analysis_server/test/edit/sort_members_test.dart
index d0b10ad..3eeaf6a 100644
--- a/pkg/analysis_server/test/edit/sort_members_test.dart
+++ b/pkg/analysis_server/test/edit/sort_members_test.dart
@@ -14,7 +14,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SortMembersTest);
   });
@@ -32,7 +32,7 @@
   }
 
   @failingTest
-  test_BAD_doesNotExist() async {
+  Future<void> test_BAD_doesNotExist() async {
     // The analysis driver fails to return an error
     Request request =
         EditSortMembersParams(convertPath('/no/such/file.dart')).toRequest('0');
@@ -41,7 +41,7 @@
         isResponseFailure('0', RequestErrorCode.SORT_MEMBERS_INVALID_FILE));
   }
 
-  test_BAD_hasParseError() async {
+  Future<void> test_BAD_hasParseError() async {
     addTestFile('''
 main() {
   print()
@@ -53,7 +53,7 @@
         isResponseFailure('0', RequestErrorCode.SORT_MEMBERS_PARSE_ERRORS));
   }
 
-  test_BAD_notDartFile() async {
+  Future<void> test_BAD_notDartFile() async {
     Request request = EditSortMembersParams(
       convertPath('/not-a-Dart-file.txt'),
     ).toRequest('0');
@@ -62,7 +62,7 @@
         isResponseFailure('0', RequestErrorCode.SORT_MEMBERS_INVALID_FILE));
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request = EditSortMembersParams('test.dart').toRequest('0');
     var response = await waitResponse(request);
     expect(
@@ -71,7 +71,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request = EditSortMembersParams(convertPath('/foo/../bar/test.dart'))
         .toRequest('0');
     var response = await waitResponse(request);
@@ -81,7 +81,7 @@
     );
   }
 
-  test_OK_afterWaitForAnalysis() async {
+  Future<void> test_OK_afterWaitForAnalysis() async {
     addTestFile('''
 class C {}
 class A {}
@@ -95,7 +95,7 @@
 ''');
   }
 
-  test_OK_classMembers_method() async {
+  Future<void> test_OK_classMembers_method() async {
     addTestFile('''
 class A {
   c() {}
@@ -112,7 +112,7 @@
 ''');
   }
 
-  test_OK_directives() async {
+  Future<void> test_OK_directives() async {
     addTestFile('''
 library lib;
 
@@ -163,7 +163,7 @@
 ''');
   }
 
-  test_OK_directives_withAnnotation() async {
+  Future<void> test_OK_directives_withAnnotation() async {
     addTestFile('''
 library lib;
 
@@ -197,7 +197,7 @@
 ''');
   }
 
-  test_OK_genericFunctionType() async {
+  Future<void> test_OK_genericFunctionType() async {
     newFile('$projectPath/analysis_options.yaml', content: '''
 analyzer:
   strong-mode: true
@@ -248,7 +248,7 @@
 ''');
   }
 
-  test_OK_unitMembers_class() async {
+  Future<void> test_OK_unitMembers_class() async {
     addTestFile('''
 class C {}
 class A {}
diff --git a/pkg/analysis_server/test/edit/statement_completion_test.dart b/pkg/analysis_server/test/edit/statement_completion_test.dart
index 1c0d1da..4bcd67f 100644
--- a/pkg/analysis_server/test/edit/statement_completion_test.dart
+++ b/pkg/analysis_server/test/edit/statement_completion_test.dart
@@ -12,7 +12,7 @@
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(StatementCompletionTest);
   });
@@ -29,7 +29,7 @@
     handler = EditDomainHandler(server);
   }
 
-  test_invalidFilePathFormat_notAbsolute() async {
+  Future<void> test_invalidFilePathFormat_notAbsolute() async {
     var request =
         EditGetStatementCompletionParams('test.dart', 0).toRequest('0');
     var response = await waitResponse(request);
@@ -39,7 +39,7 @@
     );
   }
 
-  test_invalidFilePathFormat_notNormalized() async {
+  Future<void> test_invalidFilePathFormat_notNormalized() async {
     var request = EditGetStatementCompletionParams(
             convertPath('/foo/../bar/test.dart'), 0)
         .toRequest('0');
@@ -50,7 +50,7 @@
     );
   }
 
-  test_plainEnterFromStart() async {
+  Future<void> test_plainEnterFromStart() async {
     addTestFile('''
 main() {
   int v = 1;
@@ -66,7 +66,7 @@
 ''');
   }
 
-  test_plainOleEnter() async {
+  Future<void> test_plainOleEnter() async {
     addTestFile('''
 main() {
   int v = 1;
@@ -82,7 +82,7 @@
 ''');
   }
 
-  test_plainOleEnterWithError() async {
+  Future<void> test_plainOleEnterWithError() async {
     addTestFile('''
 main() {
   int v =
@@ -123,7 +123,7 @@
     fail('Expected to find |$message| but got: ' + change.message);
   }
 
-  _prepareCompletion(String search,
+  Future<void> _prepareCompletion(String search,
       {bool atStart = false, bool atEnd = false, int delta = 0}) async {
     int offset = findOffset(search);
     if (atStart) {
@@ -134,7 +134,7 @@
     await _prepareCompletionAt(offset + delta);
   }
 
-  _prepareCompletionAt(int offset) async {
+  Future<void> _prepareCompletionAt(int offset) async {
     Request request =
         EditGetStatementCompletionParams(testFile, offset).toRequest('0');
     Response response = await waitResponse(request);
diff --git a/pkg/analysis_server/test/edit/test_all.dart b/pkg/analysis_server/test/edit/test_all.dart
index 62595d3..4f7fa7d 100644
--- a/pkg/analysis_server/test/edit/test_all.dart
+++ b/pkg/analysis_server/test/edit/test_all.dart
@@ -14,7 +14,7 @@
 import 'statement_completion_test.dart' as statement_completion;
 import 'token_details_test.dart' as token_details;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     assists.main();
     fixes.main();
diff --git a/pkg/analysis_server/test/edit/token_details_test.dart b/pkg/analysis_server/test/edit/token_details_test.dart
index d528814..f45edeb 100644
--- a/pkg/analysis_server/test/edit/token_details_test.dart
+++ b/pkg/analysis_server/test/edit/token_details_test.dart
@@ -10,7 +10,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CompletionListTokenDetailsTest);
   });
@@ -34,7 +34,7 @@
     completionHandler = CompletionDomainHandler(server);
   }
 
-  test_packageUri() async {
+  Future<void> test_packageUri() async {
     newFile('/project/.packages', content: '''
 project:lib/
 ''');
diff --git a/pkg/analysis_server/test/integration/analysis/analysis_options_test.dart b/pkg/analysis_server/test/integration/analysis/analysis_options_test.dart
index 31073f1..1a31955 100644
--- a/pkg/analysis_server/test/integration/analysis/analysis_options_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/analysis_options_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(OptionsIntegrationTest);
   });
@@ -23,7 +23,7 @@
     standardAnalysisSetup();
   }
 
-  test_option_warning_newOptionFile() async {
+  Future<void> test_option_warning_newOptionFile() async {
     String options = sourcePath(AnalysisEngine.ANALYSIS_OPTIONS_YAML_FILE);
     writeFile(options, '''
 linter:
@@ -48,7 +48,7 @@
     expect(error.location.startColumn, 7);
   }
 
-  test_option_warning_oldOptionFile() async {
+  Future<void> test_option_warning_oldOptionFile() async {
     String options = sourcePath(AnalysisEngine.ANALYSIS_OPTIONS_FILE);
     writeFile(options, '''
 linter:
diff --git a/pkg/analysis_server/test/integration/analysis/error_test.dart b/pkg/analysis_server/test/integration/analysis/error_test.dart
index 3b215e1..55d0fa2 100644
--- a/pkg/analysis_server/test/integration/analysis/error_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/error_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisErrorIntegrationTest);
   });
@@ -18,7 +18,7 @@
 @reflectiveTest
 class AnalysisErrorIntegrationTest
     extends AbstractAnalysisServerIntegrationTest {
-  test_analysisRootDoesNotExist() async {
+  Future<void> test_analysisRootDoesNotExist() async {
     String packagePath = sourcePath('package');
     String filePath = sourcePath('package/lib/test.dart');
     String content = '''
@@ -36,7 +36,7 @@
     expect(errors[0].location.file, equals(filePath));
   }
 
-  test_detect_simple_error() {
+  Future<void> test_detect_simple_error() {
     String pathname = sourcePath('test.dart');
     writeFile(pathname, '''
 main() {
@@ -51,7 +51,7 @@
     });
   }
 
-  test_super_mixins_disabled() async {
+  Future<void> test_super_mixins_disabled() async {
     String pathname = sourcePath('test.dart');
     writeFile(pathname, '''
 class Test extends Object with C {
@@ -84,7 +84,7 @@
   }
 
   @failingTest
-  test_super_mixins_enabled() async {
+  Future<void> test_super_mixins_enabled() async {
     // We see errors here with the new driver (#28870).
     //  Expected: empty
     //    Actual: [
diff --git a/pkg/analysis_server/test/integration/analysis/get_errors_non_standard_sdk_test.dart b/pkg/analysis_server/test/integration/analysis/get_errors_non_standard_sdk_test.dart
index 8abfd1d..c1d728b 100644
--- a/pkg/analysis_server/test/integration/analysis/get_errors_non_standard_sdk_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/get_errors_non_standard_sdk_test.dart
@@ -12,7 +12,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisDomainGetErrorsTest);
   });
diff --git a/pkg/analysis_server/test/integration/analysis/get_errors_test.dart b/pkg/analysis_server/test/integration/analysis/get_errors_test.dart
index f9e0c95..76563d4 100644
--- a/pkg/analysis_server/test/integration/analysis/get_errors_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/get_errors_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetErrorsTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class GetErrorsTest extends AbstractAnalysisServerIntegrationTest {
-  test_getErrors() async {
+  Future<void> test_getErrors() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 main() {
diff --git a/pkg/analysis_server/test/integration/analysis/get_hover_test.dart b/pkg/analysis_server/test/integration/analysis/get_hover_test.dart
index f665ff1..56d7cb3 100644
--- a/pkg/analysis_server/test/integration/analysis/get_hover_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/get_hover_test.dart
@@ -11,7 +11,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisGetHoverIntegrationTest);
   });
@@ -135,13 +135,13 @@
   }
 
   @override
-  setUp() {
+  Future<void> setUp() {
     return super.setUp().then((_) {
       pathname = sourcePath('test.dart');
     });
   }
 
-  test_getHover() {
+  Future<void> test_getHover() {
     writeFile(pathname, text);
     standardAnalysisSetup();
 
diff --git a/pkg/analysis_server/test/integration/analysis/get_imported_elements_test.dart b/pkg/analysis_server/test/integration/analysis/get_imported_elements_test.dart
index e5c62b4..64a83e2 100644
--- a/pkg/analysis_server/test/integration/analysis/get_imported_elements_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/get_imported_elements_test.dart
@@ -12,7 +12,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisGetImportedElementsIntegrationTest);
   });
@@ -36,7 +36,8 @@
    * with the first character that matches [target] and having the given
    * [length] matches the given list of [expected] imported elements.
    */
-  checkElements(String target, List<ImportedElements> expected) async {
+  Future<void> checkElements(
+      String target, List<ImportedElements> expected) async {
     bool equals(
         ImportedElements actualElements, ImportedElements expectedElements) {
       if (actualElements.path.endsWith(expectedElements.path) &&
@@ -93,13 +94,13 @@
   }
 
   @override
-  setUp() {
+  Future<void> setUp() {
     return super.setUp().then((_) {
       pathname = sourcePath('test.dart');
     });
   }
 
-  test_getImportedElements_none() async {
+  Future<void> test_getImportedElements_none() async {
     text = r'''
 main() {}
 ''';
@@ -110,7 +111,7 @@
     await checkNoElements('main() {}');
   }
 
-  test_getImportedElements_some() async {
+  Future<void> test_getImportedElements_some() async {
     String selection = r'''
 main() {
   Random r = new Random();
diff --git a/pkg/analysis_server/test/integration/analysis/get_library_dependencies_test.dart b/pkg/analysis_server/test/integration/analysis/get_library_dependencies_test.dart
index 7f30150..8ba8b93 100644
--- a/pkg/analysis_server/test/integration/analysis/get_library_dependencies_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/get_library_dependencies_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetLibraryDependenciesTest);
   });
@@ -17,7 +17,7 @@
 @reflectiveTest
 class GetLibraryDependenciesTest extends AbstractAnalysisServerIntegrationTest {
   @failingTest
-  test_libraryDeps() async {
+  Future<void> test_libraryDeps() async {
     // This fails with the new analysis driver ('Bad state: Should not be used
     // with the new analysis driver') - #29310.
     String pathname = sourcePath('test.dart');
diff --git a/pkg/analysis_server/test/integration/analysis/get_navigation_test.dart b/pkg/analysis_server/test/integration/analysis/get_navigation_test.dart
index b3943bc..a51347d 100644
--- a/pkg/analysis_server/test/integration/analysis/get_navigation_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/get_navigation_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetNavigationTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class GetNavigationTest extends AbstractAnalysisServerIntegrationTest {
-  test_navigation() async {
+  Future<void> test_navigation() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 class Foo {}
@@ -43,7 +43,7 @@
   }
 
   @failingTest
-  test_navigation_no_result() async {
+  Future<void> test_navigation_no_result() async {
     // This fails - it returns navigation results for a whitespace area (#28799).
     String pathname = sourcePath('test.dart');
     String text = r'''
diff --git a/pkg/analysis_server/test/integration/analysis/get_reachable_sources_test.dart b/pkg/analysis_server/test/integration/analysis/get_reachable_sources_test.dart
index 294502a..1ba0993 100644
--- a/pkg/analysis_server/test/integration/analysis/get_reachable_sources_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/get_reachable_sources_test.dart
@@ -10,7 +10,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetReachableSourcesTest);
   });
@@ -19,7 +19,7 @@
 @reflectiveTest
 class GetReachableSourcesTest extends AbstractAnalysisServerIntegrationTest {
   @failingTest
-  test_reachable() async {
+  Future<void> test_reachable() async {
     // This fails with the new analysis driver ('Bad state: Should not be used
     // with the new analysis driver') - #29311.
     String pathname = sourcePath('test.dart');
diff --git a/pkg/analysis_server/test/integration/analysis/highlights2_test.dart b/pkg/analysis_server/test/integration/analysis/highlights2_test.dart
index 9967f27..fee617f 100644
--- a/pkg/analysis_server/test/integration/analysis/highlights2_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/highlights2_test.dart
@@ -11,7 +11,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisHighlightsTest);
   });
@@ -26,7 +26,7 @@
     highlights.remove(type);
   }
 
-  computeHighlights(String pathname, String text) async {
+  Future<void> computeHighlights(String pathname, String text) async {
     writeFile(pathname, text);
     standardAnalysisSetup();
     sendAnalysisSetSubscriptions({
@@ -61,7 +61,7 @@
         useAnalysisHighlight2: true);
   }
 
-  test_highlights() async {
+  Future<void> test_highlights() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 import 'dart:async' as async;
@@ -165,7 +165,7 @@
     expect(highlights, isEmpty);
   }
 
-  test_highlights_mixin() async {
+  Future<void> test_highlights_mixin() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 mixin M on A implements B {}
diff --git a/pkg/analysis_server/test/integration/analysis/highlights_test.dart b/pkg/analysis_server/test/integration/analysis/highlights_test.dart
index 375cf79..1ad5fe2 100644
--- a/pkg/analysis_server/test/integration/analysis/highlights_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/highlights_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisHighlightsTest);
   });
@@ -24,7 +24,7 @@
     highlights.remove(type);
   }
 
-  computeHighlights(String pathname, String text) async {
+  Future<void> computeHighlights(String pathname, String text) async {
     writeFile(pathname, text);
     standardAnalysisSetup();
     sendAnalysisSetSubscriptions({
@@ -48,7 +48,7 @@
     await analysisFinished;
   }
 
-  test_highlights() async {
+  Future<void> test_highlights() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 import 'dart:async' as async;
@@ -148,7 +148,7 @@
     expect(highlights, isEmpty);
   }
 
-  test_highlights_mixin() async {
+  Future<void> test_highlights_mixin() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 mixin M on A implements B {}
diff --git a/pkg/analysis_server/test/integration/analysis/hint_sdk_version_async_exported_from_core_test.dart b/pkg/analysis_server/test/integration/analysis/hint_sdk_version_async_exported_from_core_test.dart
index 585120f..38428ff 100644
--- a/pkg/analysis_server/test/integration/analysis/hint_sdk_version_async_exported_from_core_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/hint_sdk_version_async_exported_from_core_test.dart
@@ -7,7 +7,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SdkVersionAsyncExportedFromCoreIntegrationTest);
   });
@@ -16,7 +16,7 @@
 @reflectiveTest
 class SdkVersionAsyncExportedFromCoreIntegrationTest
     extends AbstractAnalysisServerIntegrationTest {
-  test_update_pubspec() async {
+  Future<void> test_update_pubspec() async {
     var pubspecPath = sourcePath('pubspec.yaml');
     writeFile(pubspecPath, r'''
 name: test
diff --git a/pkg/analysis_server/test/integration/analysis/lint_test.dart b/pkg/analysis_server/test/integration/analysis/lint_test.dart
index ebe8986..faa2467 100644
--- a/pkg/analysis_server/test/integration/analysis/lint_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/lint_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LintIntegrationTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class LintIntegrationTest extends AbstractAnalysisServerIntegrationTest {
-  test_no_lints_when_not_specified() async {
+  Future<void> test_no_lints_when_not_specified() async {
     String source = sourcePath('test.dart');
     writeFile(source, '''
 class abc { // lint: not CamelCase (should get ignored though)
@@ -31,7 +31,7 @@
     expect(errors, hasLength(0));
   }
 
-  test_simple_lint_newOptionsFile() async {
+  Future<void> test_simple_lint_newOptionsFile() async {
     writeFile(sourcePath(AnalysisEngine.ANALYSIS_OPTIONS_YAML_FILE), '''
 linter:
   rules:
@@ -56,7 +56,7 @@
     expect(error.type, AnalysisErrorType.LINT);
   }
 
-  test_simple_lint_oldOptionsFile() async {
+  Future<void> test_simple_lint_oldOptionsFile() async {
     writeFile(sourcePath(AnalysisEngine.ANALYSIS_OPTIONS_FILE), '''
 linter:
   rules:
diff --git a/pkg/analysis_server/test/integration/analysis/navigation_test.dart b/pkg/analysis_server/test/integration/analysis/navigation_test.dart
index 61c3f86..46181e3 100644
--- a/pkg/analysis_server/test/integration/analysis/navigation_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/navigation_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNavigationTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class AnalysisNavigationTest extends AbstractAnalysisServerIntegrationTest {
-  test_navigation() async {
+  Future<void> test_navigation() async {
     String pathname1 = sourcePath('test1.dart');
     String text1 = r'''
 library foo;
diff --git a/pkg/analysis_server/test/integration/analysis/occurrences_test.dart b/pkg/analysis_server/test/integration/analysis/occurrences_test.dart
index 787aa63..8ecd96e 100644
--- a/pkg/analysis_server/test/integration/analysis/occurrences_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/occurrences_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(OccurrencesTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class OccurrencesTest extends AbstractAnalysisServerIntegrationTest {
-  test_occurrences() {
+  Future<void> test_occurrences() {
     String pathname = sourcePath('test.dart');
     String text = r'''
 main() {
diff --git a/pkg/analysis_server/test/integration/analysis/outline_test.dart b/pkg/analysis_server/test/integration/analysis/outline_test.dart
index 41ec2b9..8b87756 100644
--- a/pkg/analysis_server/test/integration/analysis/outline_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/outline_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(OutlineTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class OutlineTest extends AbstractAnalysisServerIntegrationTest {
-  test_outline() {
+  Future<void> test_outline() {
     String pathname = sourcePath('test.dart');
     String text = r'''
 class Class1 {
diff --git a/pkg/analysis_server/test/integration/analysis/overrides_test.dart b/pkg/analysis_server/test/integration/analysis/overrides_test.dart
index 9505e02b..58a4f75 100644
--- a/pkg/analysis_server/test/integration/analysis/overrides_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/overrides_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(OverridesTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class OverridesTest extends AbstractAnalysisServerIntegrationTest {
-  test_overrides() {
+  Future<void> test_overrides() {
     String pathname = sourcePath('test.dart');
     String text = r'''
 abstract class Interface1 {
diff --git a/pkg/analysis_server/test/integration/analysis/package_root_test.dart b/pkg/analysis_server/test/integration/analysis/package_root_test.dart
index 46f961c..55f0d19 100644
--- a/pkg/analysis_server/test/integration/analysis/package_root_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/package_root_test.dart
@@ -12,7 +12,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SetAnalysisRootsTest);
   });
@@ -20,7 +20,7 @@
 
 @reflectiveTest
 class SetAnalysisRootsTest extends AbstractAnalysisServerIntegrationTest {
-  xtest_package_root() async {
+  Future<void> xtest_package_root() async {
     // TODO(devoncarew): This test fails intermittently on the bots; #33879.
     String projPath = sourcePath('project');
     String mainPath = path.join(projPath, 'main.dart');
diff --git a/pkg/analysis_server/test/integration/analysis/reanalyze_concurrent_test.dart b/pkg/analysis_server/test/integration/analysis/reanalyze_concurrent_test.dart
index 4985965..cc38da9 100644
--- a/pkg/analysis_server/test/integration/analysis/reanalyze_concurrent_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/reanalyze_concurrent_test.dart
@@ -15,7 +15,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReanalyzeTest);
   });
@@ -24,7 +24,7 @@
 @reflectiveTest
 class ReanalyzeTest extends AbstractAnalysisServerIntegrationTest {
   @TestTimeout(Timeout.factor(2))
-  test_reanalyze_concurrent() {
+  Future<void> test_reanalyze_concurrent() {
     String pathname = sourcePath('test.dart');
     String text = '''
 // Do a bunch of imports so that analysis has some work to do.
diff --git a/pkg/analysis_server/test/integration/analysis/reanalyze_test.dart b/pkg/analysis_server/test/integration/analysis/reanalyze_test.dart
index 60fe554..153eed1 100644
--- a/pkg/analysis_server/test/integration/analysis/reanalyze_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/reanalyze_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReanalyzeTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class ReanalyzeTest extends AbstractAnalysisServerIntegrationTest {
-  test_reanalyze() {
+  Future<void> test_reanalyze() {
     String pathname = sourcePath('test.dart');
     String text = 'main() {}';
     writeFile(pathname, text);
diff --git a/pkg/analysis_server/test/integration/analysis/set_analysis_roots_test.dart b/pkg/analysis_server/test/integration/analysis/set_analysis_roots_test.dart
index c0aa33e..18be9fa 100644
--- a/pkg/analysis_server/test/integration/analysis/set_analysis_roots_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/set_analysis_roots_test.dart
@@ -7,7 +7,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SetAnalysisRootsTest);
   });
@@ -15,7 +15,7 @@
 
 @reflectiveTest
 class SetAnalysisRootsTest extends AbstractAnalysisServerIntegrationTest {
-  test_options() async {
+  Future<void> test_options() async {
     String pathname = sourcePath('test.dart');
     writeFile(pathname, '''
 class Foo {
diff --git a/pkg/analysis_server/test/integration/analysis/set_general_subscriptions_test.dart b/pkg/analysis_server/test/integration/analysis/set_general_subscriptions_test.dart
index eeef19e..a8a7489 100644
--- a/pkg/analysis_server/test/integration/analysis/set_general_subscriptions_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/set_general_subscriptions_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SetGeneralSubscriptionsTest);
   });
@@ -18,7 +18,7 @@
 @reflectiveTest
 class SetGeneralSubscriptionsTest
     extends AbstractAnalysisServerIntegrationTest {
-  test_options() async {
+  Future<void> test_options() async {
     String pathname = sourcePath('test.dart');
     writeFile(pathname, '''
 class Foo {
diff --git a/pkg/analysis_server/test/integration/analysis/set_priority_files_test.dart b/pkg/analysis_server/test/integration/analysis/set_priority_files_test.dart
index e1ef4cf..cd1e3bd 100644
--- a/pkg/analysis_server/test/integration/analysis/set_priority_files_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/set_priority_files_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SetPriorityFilesTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class SetPriorityFilesTest extends AbstractAnalysisServerIntegrationTest {
-  test_options() async {
+  Future<void> test_options() async {
     String pathname = sourcePath('foo.dart');
     writeFile(pathname, 'class Foo { void baz() {} }');
     writeFile(sourcePath('bar.dart'), 'class Bar { void baz() {} }');
diff --git a/pkg/analysis_server/test/integration/analysis/set_subscriptions_test.dart b/pkg/analysis_server/test/integration/analysis/set_subscriptions_test.dart
index b5d60d4..79c0461 100644
--- a/pkg/analysis_server/test/integration/analysis/set_subscriptions_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/set_subscriptions_test.dart
@@ -7,7 +7,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SetSubscriptionsTest);
   });
@@ -15,7 +15,7 @@
 
 @reflectiveTest
 class SetSubscriptionsTest extends AbstractAnalysisServerIntegrationTest {
-  test_subscriptions() async {
+  Future<void> test_subscriptions() async {
     String pathname = sourcePath('test.dart');
     writeFile(pathname, '''
 class Foo {
diff --git a/pkg/analysis_server/test/integration/analysis/test_all.dart b/pkg/analysis_server/test/integration/analysis/test_all.dart
index ea09692..2a760bf 100644
--- a/pkg/analysis_server/test/integration/analysis/test_all.dart
+++ b/pkg/analysis_server/test/integration/analysis/test_all.dart
@@ -33,10 +33,7 @@
 import 'update_content_test.dart' as update_content_test;
 import 'update_options_test.dart' as update_options_test;
 
-/**
- * Utility for manually running all integration tests.
- */
-main() {
+void main() {
   defineReflectiveSuite(() {
     analysis_options_test.main();
     error_test.main();
diff --git a/pkg/analysis_server/test/integration/analysis/update_content_list_test.dart b/pkg/analysis_server/test/integration/analysis/update_content_list_test.dart
index f3a775a..a235d37 100644
--- a/pkg/analysis_server/test/integration/analysis/update_content_list_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/update_content_list_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UpdateContentTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class UpdateContentTest extends AbstractAnalysisServerIntegrationTest {
-  test_updateContent_list() {
+  Future<void> test_updateContent_list() {
     String pathname = sourcePath('test.dart');
     String goodText = r'''
 main() {
diff --git a/pkg/analysis_server/test/integration/analysis/update_content_test.dart b/pkg/analysis_server/test/integration/analysis/update_content_test.dart
index eb646fe..c2c8ce0 100644
--- a/pkg/analysis_server/test/integration/analysis/update_content_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/update_content_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UpdateContentTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class UpdateContentTest extends AbstractAnalysisServerIntegrationTest {
-  test_updateContent() async {
+  Future<void> test_updateContent() async {
     String path = sourcePath('test.dart');
     String goodText = r'''
 main() {
@@ -58,7 +58,7 @@
     expect(currentAnalysisErrors[path], isNotEmpty);
   }
 
-  test_updateContent_multipleAdds() async {
+  Future<void> test_updateContent_multipleAdds() async {
     String pathname = sourcePath('test.dart');
     writeFile(pathname, r'''
 class Person {
diff --git a/pkg/analysis_server/test/integration/analysis/update_options_test.dart b/pkg/analysis_server/test/integration/analysis/update_options_test.dart
index d3b167d..d61bcde 100644
--- a/pkg/analysis_server/test/integration/analysis/update_options_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/update_options_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UpdateOptionsTest);
   });
@@ -17,7 +17,7 @@
 @reflectiveTest
 class UpdateOptionsTest extends AbstractAnalysisServerIntegrationTest {
   @failingTest
-  test_options() async {
+  Future<void> test_options() async {
     // We fail after the first analysis.updateOptions - we should not see a hint
     // for the unused import (#28800).
     String pathname = sourcePath('test.dart');
diff --git a/pkg/analysis_server/test/integration/analytics/enable_test.dart b/pkg/analysis_server/test/integration/analytics/enable_test.dart
index 19296ee..a6d0138 100644
--- a/pkg/analysis_server/test/integration/analytics/enable_test.dart
+++ b/pkg/analysis_server/test/integration/analytics/enable_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(EnableTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class EnableTest extends AbstractAnalysisServerIntegrationTest {
-  test_call_enable() async {
+  Future<void> test_call_enable() async {
     standardAnalysisSetup();
 
     // Toggle the value twice; do light verification of the changes, as the
diff --git a/pkg/analysis_server/test/integration/analytics/is_enabled_test.dart b/pkg/analysis_server/test/integration/analytics/is_enabled_test.dart
index 15b5cf8..a38ec1f 100644
--- a/pkg/analysis_server/test/integration/analytics/is_enabled_test.dart
+++ b/pkg/analysis_server/test/integration/analytics/is_enabled_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(IsEnabledTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class IsEnabledTest extends AbstractAnalysisServerIntegrationTest {
-  test_isEnabled() async {
+  Future<void> test_isEnabled() async {
     standardAnalysisSetup();
 
     AnalyticsIsEnabledResult result = await sendAnalyticsIsEnabled();
diff --git a/pkg/analysis_server/test/integration/analytics/send_event_test.dart b/pkg/analysis_server/test/integration/analytics/send_event_test.dart
index 5a0b09e..d23b104 100644
--- a/pkg/analysis_server/test/integration/analytics/send_event_test.dart
+++ b/pkg/analysis_server/test/integration/analytics/send_event_test.dart
@@ -7,7 +7,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SendEventTest);
   });
@@ -15,7 +15,7 @@
 
 @reflectiveTest
 class SendEventTest extends AbstractAnalysisServerIntegrationTest {
-  test_send_event() async {
+  Future<void> test_send_event() async {
     standardAnalysisSetup();
 
     // Disable analytics.
diff --git a/pkg/analysis_server/test/integration/analytics/send_timing_test.dart b/pkg/analysis_server/test/integration/analytics/send_timing_test.dart
index 141e3b7..3d7854f 100644
--- a/pkg/analysis_server/test/integration/analytics/send_timing_test.dart
+++ b/pkg/analysis_server/test/integration/analytics/send_timing_test.dart
@@ -7,7 +7,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SendTimingTest);
   });
@@ -15,7 +15,7 @@
 
 @reflectiveTest
 class SendTimingTest extends AbstractAnalysisServerIntegrationTest {
-  test_send_timing() async {
+  Future<void> test_send_timing() async {
     standardAnalysisSetup();
 
     // Disable analytics.
diff --git a/pkg/analysis_server/test/integration/analytics/test_all.dart b/pkg/analysis_server/test/integration/analytics/test_all.dart
index f9e7963..4781bad 100644
--- a/pkg/analysis_server/test/integration/analytics/test_all.dart
+++ b/pkg/analysis_server/test/integration/analytics/test_all.dart
@@ -9,7 +9,7 @@
 import 'send_event_test.dart' as send_event_test;
 import 'send_timing_test.dart' as send_timing_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     enable_test.main();
     is_enabled_test.main();
diff --git a/pkg/analysis_server/test/integration/completion/get_suggestions_test.dart b/pkg/analysis_server/test/integration/completion/get_suggestions_test.dart
index 443c24c..6848ce3 100644
--- a/pkg/analysis_server/test/integration/completion/get_suggestions_test.dart
+++ b/pkg/analysis_server/test/integration/completion/get_suggestions_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetSuggestionsTest);
   });
@@ -32,7 +32,7 @@
         content.substring(completionOffset + 1);
   }
 
-  test_getSuggestions() async {
+  Future<void> test_getSuggestions() async {
     setTestSource('test.dart', r'''
 String test = '';
 main() {
@@ -54,7 +54,7 @@
         (CompletionSuggestion suggestion) => suggestion.completion == 'length');
   }
 
-  test_getSuggestions_onlyOverlay() async {
+  Future<void> test_getSuggestions_onlyOverlay() async {
     setTestSource('test.dart', r'''
 String test = '';
 main() {
@@ -78,7 +78,7 @@
         (CompletionSuggestion suggestion) => suggestion.completion == 'length');
   }
 
-  test_getSuggestions_onlyOverlay_noWait() async {
+  Future<void> test_getSuggestions_onlyOverlay_noWait() async {
     setTestSource('test.dart', r'''
 String test = '';
 main() {
@@ -99,7 +99,7 @@
         (CompletionSuggestion suggestion) => suggestion.completion == 'length');
   }
 
-  test_getSuggestions_sourceMissing_noWait() {
+  Future<void> test_getSuggestions_sourceMissing_noWait() {
     path = sourcePath('does_not_exist.dart');
     // Do not write the file to "disk"
     //   writeFile(pathname, text);
diff --git a/pkg/analysis_server/test/integration/completion/list_token_details_test.dart b/pkg/analysis_server/test/integration/completion/list_token_details_test.dart
index c49b7fb..f649dc9 100644
--- a/pkg/analysis_server/test/integration/completion/list_token_details_test.dart
+++ b/pkg/analysis_server/test/integration/completion/list_token_details_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ListTokenDetailsTest);
   });
@@ -35,7 +35,7 @@
     return Future.wait(futures);
   }
 
-  test_getSuggestions() async {
+  Future<void> test_getSuggestions() async {
     String aPath = path.join(sourceDirectory.path, 'a');
     String aLibPath = path.join(aPath, 'lib');
     writeFile(path.join(aLibPath, 'a.dart'), '''
diff --git a/pkg/analysis_server/test/integration/completion/test_all.dart b/pkg/analysis_server/test/integration/completion/test_all.dart
index 11ed77f..0462e31 100644
--- a/pkg/analysis_server/test/integration/completion/test_all.dart
+++ b/pkg/analysis_server/test/integration/completion/test_all.dart
@@ -7,7 +7,7 @@
 import 'get_suggestions_test.dart' as get_suggestions;
 import 'list_token_details_test.dart' as list_token_details;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     get_suggestions.main();
     list_token_details.main();
diff --git a/pkg/analysis_server/test/integration/coverage_test.dart b/pkg/analysis_server/test/integration/coverage_test.dart
index 7960fed..3941a75 100644
--- a/pkg/analysis_server/test/integration/coverage_test.dart
+++ b/pkg/analysis_server/test/integration/coverage_test.dart
@@ -12,7 +12,7 @@
 import '../../tool/spec/from_html.dart';
 
 /// Define tests to fail if there's no mention in the coverage file.
-main() {
+void main() {
   Api api;
   File coverageFile;
   String pathPrefix;
diff --git a/pkg/analysis_server/test/integration/diagnostic/get_diagnostics_test.dart b/pkg/analysis_server/test/integration/diagnostic/get_diagnostics_test.dart
index 1eb2a17..bbd1211 100644
--- a/pkg/analysis_server/test/integration/diagnostic/get_diagnostics_test.dart
+++ b/pkg/analysis_server/test/integration/diagnostic/get_diagnostics_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetDiagnosticsTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class GetDiagnosticsTest extends AbstractAnalysisServerIntegrationTest {
-  test_getDiagnostics() async {
+  Future<void> test_getDiagnostics() async {
     standardAnalysisSetup();
 
     DiagnosticGetDiagnosticsResult result =
diff --git a/pkg/analysis_server/test/integration/diagnostic/get_server_port_test.dart b/pkg/analysis_server/test/integration/diagnostic/get_server_port_test.dart
index c202660..8ac45b1 100644
--- a/pkg/analysis_server/test/integration/diagnostic/get_server_port_test.dart
+++ b/pkg/analysis_server/test/integration/diagnostic/get_server_port_test.dart
@@ -11,7 +11,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetServerPortTest);
   });
@@ -19,7 +19,7 @@
 
 @reflectiveTest
 class GetServerPortTest extends AbstractAnalysisServerIntegrationTest {
-  test_connect() async {
+  Future<void> test_connect() async {
     standardAnalysisSetup();
 
     DiagnosticGetServerPortResult result = await sendDiagnosticGetServerPort();
diff --git a/pkg/analysis_server/test/integration/diagnostic/test_all.dart b/pkg/analysis_server/test/integration/diagnostic/test_all.dart
index 5265193..50293e2 100644
--- a/pkg/analysis_server/test/integration/diagnostic/test_all.dart
+++ b/pkg/analysis_server/test/integration/diagnostic/test_all.dart
@@ -7,7 +7,7 @@
 import 'get_diagnostics_test.dart' as get_diagnostics_test;
 import 'get_server_port_test.dart' as get_server_port_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     get_diagnostics_test.main();
     get_server_port_test.main();
diff --git a/pkg/analysis_server/test/integration/edit/dartfix_test.dart b/pkg/analysis_server/test/integration/edit/dartfix_test.dart
index 31942a9..f99498e 100644
--- a/pkg/analysis_server/test/integration/edit/dartfix_test.dart
+++ b/pkg/analysis_server/test/integration/edit/dartfix_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DartfixTest);
   });
@@ -25,7 +25,7 @@
     standardAnalysisSetup();
   }
 
-  test_dartfix_exclude() async {
+  Future<void> test_dartfix_exclude() async {
     setupTarget();
     EditDartfixResult result = await sendEditDartfix([(sourceDirectory.path)],
         excludedFixes: ['convert_class_to_mixin']);
@@ -34,7 +34,7 @@
     expect(result.edits.length, 0);
   }
 
-  test_dartfix_include() async {
+  Future<void> test_dartfix_include() async {
     setupTarget();
     EditDartfixResult result = await sendEditDartfix([(sourceDirectory.path)],
         includedFixes: ['convert_class_to_mixin']);
@@ -43,7 +43,7 @@
     expect(result.edits.length, greaterThanOrEqualTo(1));
   }
 
-  test_dartfix_include_other() async {
+  Future<void> test_dartfix_include_other() async {
     setupTarget();
     EditDartfixResult result = await sendEditDartfix([(sourceDirectory.path)],
         includedFixes: ['prefer_int_literals']);
diff --git a/pkg/analysis_server/test/integration/edit/format_test.dart b/pkg/analysis_server/test/integration/edit/format_test.dart
index 4f62ef2..530d73a 100644
--- a/pkg/analysis_server/test/integration/edit/format_test.dart
+++ b/pkg/analysis_server/test/integration/edit/format_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FormatTest);
   });
@@ -46,7 +46,7 @@
     return pathname;
   }
 
-  test_format() async {
+  Future<void> test_format() async {
     String pathname = formatTestSetup();
 
     EditFormatResult result = await sendEditFormat(pathname, 0, 0);
@@ -55,7 +55,7 @@
     expect(result.selectionLength, 0);
   }
 
-  test_format_preserve_selection() async {
+  Future<void> test_format_preserve_selection() async {
     String pathname = formatTestSetup();
 
     // format with 'bar' selected
@@ -67,7 +67,7 @@
     expect(result.selectionLength, 'bar'.length);
   }
 
-  test_format_with_errors() async {
+  Future<void> test_format_with_errors() async {
     String pathname = formatTestSetup(withErrors: true);
 
     try {
diff --git a/pkg/analysis_server/test/integration/edit/get_assists_test.dart b/pkg/analysis_server/test/integration/edit/get_assists_test.dart
index f2b57dc..a5fff4f 100644
--- a/pkg/analysis_server/test/integration/edit/get_assists_test.dart
+++ b/pkg/analysis_server/test/integration/edit/get_assists_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetAssistsTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class GetAssistsTest extends AbstractAnalysisServerIntegrationTest {
-  test_has_assists() async {
+  Future<void> test_has_assists() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 import 'dart:async';
diff --git a/pkg/analysis_server/test/integration/edit/get_available_refactorings_test.dart b/pkg/analysis_server/test/integration/edit/get_available_refactorings_test.dart
index ddbcfe6..7b11a6e 100644
--- a/pkg/analysis_server/test/integration/edit/get_available_refactorings_test.dart
+++ b/pkg/analysis_server/test/integration/edit/get_available_refactorings_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetAvailableRefactoringsTest);
   });
@@ -17,7 +17,7 @@
 @reflectiveTest
 class GetAvailableRefactoringsTest
     extends AbstractAnalysisServerIntegrationTest {
-  test_has_refactorings() async {
+  Future<void> test_has_refactorings() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 void foo() { }
diff --git a/pkg/analysis_server/test/integration/edit/get_dartfix_info_test.dart b/pkg/analysis_server/test/integration/edit/get_dartfix_info_test.dart
index b62ed77..3d445e0 100644
--- a/pkg/analysis_server/test/integration/edit/get_dartfix_info_test.dart
+++ b/pkg/analysis_server/test/integration/edit/get_dartfix_info_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetDartfixInfoTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class GetDartfixInfoTest extends AbstractAnalysisServerIntegrationTest {
-  test_getDartfixInfo() async {
+  Future<void> test_getDartfixInfo() async {
     standardAnalysisSetup();
     EditGetDartfixInfoResult info = await sendEditGetDartfixInfo();
     expect(info.fixes.length, greaterThanOrEqualTo(3));
diff --git a/pkg/analysis_server/test/integration/edit/get_fixes_test.dart b/pkg/analysis_server/test/integration/edit/get_fixes_test.dart
index 81af6dea..23e238a 100644
--- a/pkg/analysis_server/test/integration/edit/get_fixes_test.dart
+++ b/pkg/analysis_server/test/integration/edit/get_fixes_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetFixesTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class GetFixesTest extends AbstractAnalysisServerIntegrationTest {
-  test_has_fixes() async {
+  Future<void> test_has_fixes() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 FutureOr f;
@@ -44,7 +44,7 @@
     expect(change.edits.first.edits, hasLength(1));
   }
 
-  test_no_fixes() async {
+  Future<void> test_no_fixes() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 import 'dart:async';
diff --git a/pkg/analysis_server/test/integration/edit/get_postfix_completion_test.dart b/pkg/analysis_server/test/integration/edit/get_postfix_completion_test.dart
index b880bf3..61b0d99 100644
--- a/pkg/analysis_server/test/integration/edit/get_postfix_completion_test.dart
+++ b/pkg/analysis_server/test/integration/edit/get_postfix_completion_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetPostfixCompletionTest);
   });
@@ -18,7 +18,7 @@
 @reflectiveTest
 class GetPostfixCompletionTest extends AbstractAnalysisServerIntegrationTest {
   @TestTimeout(Timeout.factor(2))
-  test_postfix_completion() async {
+  Future<void> test_postfix_completion() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 void bar() {
diff --git a/pkg/analysis_server/test/integration/edit/get_refactoring_test.dart b/pkg/analysis_server/test/integration/edit/get_refactoring_test.dart
index a82f80f..bb0d602 100644
--- a/pkg/analysis_server/test/integration/edit/get_refactoring_test.dart
+++ b/pkg/analysis_server/test/integration/edit/get_refactoring_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetRefactoringTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class GetRefactoringTest extends AbstractAnalysisServerIntegrationTest {
-  test_rename() async {
+  Future<void> test_rename() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 void foo() { }
diff --git a/pkg/analysis_server/test/integration/edit/get_statement_completion_test.dart b/pkg/analysis_server/test/integration/edit/get_statement_completion_test.dart
index bd1322a..5b12cc8 100644
--- a/pkg/analysis_server/test/integration/edit/get_statement_completion_test.dart
+++ b/pkg/analysis_server/test/integration/edit/get_statement_completion_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetStatementCompletionTest);
   });
@@ -18,7 +18,7 @@
 @reflectiveTest
 class GetStatementCompletionTest extends AbstractAnalysisServerIntegrationTest {
   @TestTimeout(Timeout.factor(2))
-  test_statement_completion() async {
+  Future<void> test_statement_completion() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 void bar() { foo() } // missing semi-colon
diff --git a/pkg/analysis_server/test/integration/edit/import_elements_test.dart b/pkg/analysis_server/test/integration/edit/import_elements_test.dart
index e940211..15c6cda 100644
--- a/pkg/analysis_server/test/integration/edit/import_elements_test.dart
+++ b/pkg/analysis_server/test/integration/edit/import_elements_test.dart
@@ -13,7 +13,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisGetImportElementsIntegrationTest);
   });
@@ -31,7 +31,8 @@
    * Check that an edit.importElements request with the given list of [elements]
    * produces the [expected] list of edits.
    */
-  checkEdits(List<ImportedElements> elements, List<SourceEdit> expected,
+  Future<void> checkEdits(
+      List<ImportedElements> elements, List<SourceEdit> expected,
       {String expectedFile}) async {
     bool equals(SourceEdit actualEdit, SourceEdit expectedEdit) {
       return actualEdit.offset == expectedEdit.offset &&
@@ -87,7 +88,7 @@
     pathname = sourcePath('test.dart');
   }
 
-  test_importElements_definingUnit() async {
+  Future<void> test_importElements_definingUnit() async {
     writeFile(pathname, 'main() {}');
     standardAnalysisSetup();
     await analysisFinished;
@@ -103,7 +104,7 @@
     ]);
   }
 
-  test_importElements_noEdits() async {
+  Future<void> test_importElements_noEdits() async {
     writeFile(pathname, '');
     standardAnalysisSetup();
     await analysisFinished;
@@ -111,7 +112,7 @@
     await checkNoEdits(<ImportedElements>[]);
   }
 
-  test_importElements_part() async {
+  Future<void> test_importElements_part() async {
     String libName = sourcePath('lib.dart');
     writeFile(libName, '''
 part 'test.dart';
diff --git a/pkg/analysis_server/test/integration/edit/is_postfix_completion_applicable_test.dart b/pkg/analysis_server/test/integration/edit/is_postfix_completion_applicable_test.dart
index 7c65699..712a698 100644
--- a/pkg/analysis_server/test/integration/edit/is_postfix_completion_applicable_test.dart
+++ b/pkg/analysis_server/test/integration/edit/is_postfix_completion_applicable_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(IsPostfixCompletionApplicableTest);
   });
@@ -17,7 +17,7 @@
 @reflectiveTest
 class IsPostfixCompletionApplicableTest
     extends AbstractAnalysisServerIntegrationTest {
-  test_is_postfix_completion_applicable() async {
+  Future<void> test_is_postfix_completion_applicable() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 void bar() {
diff --git a/pkg/analysis_server/test/integration/edit/list_postfix_completion_templates_test.dart b/pkg/analysis_server/test/integration/edit/list_postfix_completion_templates_test.dart
index 63f13e4..4c96713 100644
--- a/pkg/analysis_server/test/integration/edit/list_postfix_completion_templates_test.dart
+++ b/pkg/analysis_server/test/integration/edit/list_postfix_completion_templates_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ListPostfixCompletionTemplatesTest);
   });
@@ -17,7 +17,7 @@
 @reflectiveTest
 class ListPostfixCompletionTemplatesTest
     extends AbstractAnalysisServerIntegrationTest {
-  test_list_postfix_completion_templates() async {
+  Future<void> test_list_postfix_completion_templates() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 void bar() {
diff --git a/pkg/analysis_server/test/integration/edit/organize_directives_test.dart b/pkg/analysis_server/test/integration/edit/organize_directives_test.dart
index e5b0a46..410df1b 100644
--- a/pkg/analysis_server/test/integration/edit/organize_directives_test.dart
+++ b/pkg/analysis_server/test/integration/edit/organize_directives_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(OrganizeDirectivesTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class OrganizeDirectivesTest extends AbstractAnalysisServerIntegrationTest {
-  test_organize_directives() async {
+  Future<void> test_organize_directives() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 import 'dart:math';
@@ -37,7 +37,7 @@
         "import 'dart:async';\nimport 'dart:math");
   }
 
-  test_organize_directives_no_changes() async {
+  Future<void> test_organize_directives_no_changes() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 import 'dart:async';
@@ -55,7 +55,7 @@
     expect(edit.edits, isEmpty);
   }
 
-  test_organize_directives_with_errors() async {
+  Future<void> test_organize_directives_with_errors() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 import 'dart:async'
diff --git a/pkg/analysis_server/test/integration/edit/sort_members_test.dart b/pkg/analysis_server/test/integration/edit/sort_members_test.dart
index b928b6f..607e05a 100644
--- a/pkg/analysis_server/test/integration/edit/sort_members_test.dart
+++ b/pkg/analysis_server/test/integration/edit/sort_members_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SortMembersTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class SortMembersTest extends AbstractAnalysisServerIntegrationTest {
-  test_sort() async {
+  Future<void> test_sort() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 int foo;
@@ -32,7 +32,7 @@
     expect(edit.edits.first.replacement, 'bar;\nint foo');
   }
 
-  test_sort_no_changes() async {
+  Future<void> test_sort_no_changes() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 int bar;
@@ -46,7 +46,7 @@
     expect(edit.edits, isEmpty);
   }
 
-  test_sort_with_errors() async {
+  Future<void> test_sort_with_errors() async {
     String pathname = sourcePath('test.dart');
     String text = r'''
 int foo
diff --git a/pkg/analysis_server/test/integration/edit/test_all.dart b/pkg/analysis_server/test/integration/edit/test_all.dart
index 3a71a95..3ac606c 100644
--- a/pkg/analysis_server/test/integration/edit/test_all.dart
+++ b/pkg/analysis_server/test/integration/edit/test_all.dart
@@ -22,7 +22,7 @@
 import 'organize_directives_test.dart' as organize_directives_test;
 import 'sort_members_test.dart' as sort_members_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     dartfix_test.main();
     format_test.main();
diff --git a/pkg/analysis_server/test/integration/execution/create_context_test.dart b/pkg/analysis_server/test/integration/execution/create_context_test.dart
index f73fe9a..3c05f33 100644
--- a/pkg/analysis_server/test/integration/execution/create_context_test.dart
+++ b/pkg/analysis_server/test/integration/execution/create_context_test.dart
@@ -7,7 +7,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateContextTest);
   });
@@ -15,7 +15,7 @@
 
 @reflectiveTest
 class CreateContextTest extends AbstractAnalysisServerIntegrationTest {
-  test_create() async {
+  Future<void> test_create() async {
     standardAnalysisSetup();
     String contextId =
         (await sendExecutionCreateContext(sourceDirectory.path)).id;
diff --git a/pkg/analysis_server/test/integration/execution/delete_context_test.dart b/pkg/analysis_server/test/integration/execution/delete_context_test.dart
index a22a9e8..05b2db7 100644
--- a/pkg/analysis_server/test/integration/execution/delete_context_test.dart
+++ b/pkg/analysis_server/test/integration/execution/delete_context_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DeleteContextTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class DeleteContextTest extends AbstractAnalysisServerIntegrationTest {
-  test_delete() async {
+  Future<void> test_delete() async {
     String pathname = sourcePath('lib/main.dart');
     writeFile(pathname, '// dummy');
     writeFile(sourcePath('.packages'), 'foo:lib/');
diff --git a/pkg/analysis_server/test/integration/execution/map_uri_test.dart b/pkg/analysis_server/test/integration/execution/map_uri_test.dart
index 8038545..384cc6d 100644
--- a/pkg/analysis_server/test/integration/execution/map_uri_test.dart
+++ b/pkg/analysis_server/test/integration/execution/map_uri_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MapUriTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class MapUriTest extends AbstractAnalysisServerIntegrationTest {
-  test_mapUri() async {
+  Future<void> test_mapUri() async {
     String pathname = sourcePath('lib/main.dart');
     writeFile(pathname, '// dummy');
     writeFile(sourcePath('.packages'), 'foo:lib/');
diff --git a/pkg/analysis_server/test/integration/execution/set_subscriptions_test.dart b/pkg/analysis_server/test/integration/execution/set_subscriptions_test.dart
index 82c3739..340ded4 100644
--- a/pkg/analysis_server/test/integration/execution/set_subscriptions_test.dart
+++ b/pkg/analysis_server/test/integration/execution/set_subscriptions_test.dart
@@ -7,7 +7,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SetSubscriptionsTest);
   });
@@ -15,7 +15,7 @@
 
 @reflectiveTest
 class SetSubscriptionsTest extends AbstractAnalysisServerIntegrationTest {
-  test_subscribe() async {
+  Future<void> test_subscribe() async {
     standardAnalysisSetup();
     // ignore: deprecated_member_use_from_same_package
     await sendExecutionSetSubscriptions([ExecutionService.LAUNCH_DATA]);
diff --git a/pkg/analysis_server/test/integration/execution/test_all.dart b/pkg/analysis_server/test/integration/execution/test_all.dart
index 4f6af5d..76aa11d 100644
--- a/pkg/analysis_server/test/integration/execution/test_all.dart
+++ b/pkg/analysis_server/test/integration/execution/test_all.dart
@@ -9,7 +9,7 @@
 import 'map_uri_test.dart' as map_uri_test;
 import 'set_subscriptions_test.dart' as set_subscription_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     create_context_test.main();
     delete_context_test.main();
diff --git a/pkg/analysis_server/test/integration/kythe/get_kythe_entries_test.dart b/pkg/analysis_server/test/integration/kythe/get_kythe_entries_test.dart
index 0d823a9..7646865 100644
--- a/pkg/analysis_server/test/integration/kythe/get_kythe_entries_test.dart
+++ b/pkg/analysis_server/test/integration/kythe/get_kythe_entries_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetKytheEntriesTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class GetKytheEntriesTest extends AbstractAnalysisServerIntegrationTest {
-  test_getKytheEntries() async {
+  Future<void> test_getKytheEntries() async {
     writeFile(sourcePath('WORKSPACE'), '');
     String pathname = sourcePath('pkg/test.dart');
     String text = r'''
diff --git a/pkg/analysis_server/test/integration/kythe/test_all.dart b/pkg/analysis_server/test/integration/kythe/test_all.dart
index 0573a6c..c50b940 100644
--- a/pkg/analysis_server/test/integration/kythe/test_all.dart
+++ b/pkg/analysis_server/test/integration/kythe/test_all.dart
@@ -6,7 +6,7 @@
 
 import 'get_kythe_entries_test.dart' as get_kythe_entries_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     get_kythe_entries_test.main();
   }, name: 'kythe');
diff --git a/pkg/analysis_server/test/integration/linter/lint_names_test.dart b/pkg/analysis_server/test/integration/linter/lint_names_test.dart
index ab0166f..17f8287 100644
--- a/pkg/analysis_server/test/integration/linter/lint_names_test.dart
+++ b/pkg/analysis_server/test/integration/linter/lint_names_test.dart
@@ -20,7 +20,7 @@
 import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 
-main() {
+void main() {
   // Set prefix for local or bot execution.
   final pathPrefix =
       FileSystemEntity.isDirectorySync(path.join('test', 'integration'))
diff --git a/pkg/analysis_server/test/integration/linter/test_all.dart b/pkg/analysis_server/test/integration/linter/test_all.dart
index 079a94c..addcf98 100644
--- a/pkg/analysis_server/test/integration/linter/test_all.dart
+++ b/pkg/analysis_server/test/integration/linter/test_all.dart
@@ -6,7 +6,7 @@
 
 import 'lint_names_test.dart' as lint_names;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     lint_names.main();
   }, name: 'linter');
diff --git a/pkg/analysis_server/test/integration/lsp_server/analyzer_status_test.dart b/pkg/analysis_server/test/integration/lsp_server/analyzer_status_test.dart
index d597d84..0184100 100644
--- a/pkg/analysis_server/test/integration/lsp_server/analyzer_status_test.dart
+++ b/pkg/analysis_server/test/integration/lsp_server/analyzer_status_test.dart
@@ -7,7 +7,7 @@
 
 import 'integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalyzerStatusTest);
   });
@@ -15,27 +15,7 @@
 
 @reflectiveTest
 class AnalyzerStatusTest extends AbstractLspAnalysisServerIntegrationTest {
-  test_afterInitialize() async {
-    const initialContents = 'int a = 1;';
-    newFile(mainFilePath, content: initialContents);
-
-    // To avoid races, set up listeners for the notifications before we initialise
-    // and track which event came first to ensure they arrived in the expected
-    // order.
-    bool firstNotificationWasAnalyzing;
-    final startNotification = waitForAnalysisStart()
-        .then((_) => firstNotificationWasAnalyzing ??= true);
-    final completeNotification = waitForAnalysisComplete()
-        .then((_) => firstNotificationWasAnalyzing ??= false);
-
-    await initialize();
-    await startNotification;
-    await completeNotification;
-
-    expect(firstNotificationWasAnalyzing, isTrue);
-  }
-
-  test_afterDocumentEdits() async {
+  Future<void> test_afterDocumentEdits() async {
     const initialContents = 'int a = 1;';
     newFile(mainFilePath, content: initialContents);
 
@@ -56,4 +36,24 @@
     await startNotification;
     await completeNotification;
   }
+
+  Future<void> test_afterInitialize() async {
+    const initialContents = 'int a = 1;';
+    newFile(mainFilePath, content: initialContents);
+
+    // To avoid races, set up listeners for the notifications before we initialise
+    // and track which event came first to ensure they arrived in the expected
+    // order.
+    bool firstNotificationWasAnalyzing;
+    final startNotification = waitForAnalysisStart()
+        .then((_) => firstNotificationWasAnalyzing ??= true);
+    final completeNotification = waitForAnalysisComplete()
+        .then((_) => firstNotificationWasAnalyzing ??= false);
+
+    await initialize();
+    await startNotification;
+    await completeNotification;
+
+    expect(firstNotificationWasAnalyzing, isTrue);
+  }
 }
diff --git a/pkg/analysis_server/test/integration/lsp_server/diagnostic_test.dart b/pkg/analysis_server/test/integration/lsp_server/diagnostic_test.dart
index 40e2ff6..0763cda 100644
--- a/pkg/analysis_server/test/integration/lsp_server/diagnostic_test.dart
+++ b/pkg/analysis_server/test/integration/lsp_server/diagnostic_test.dart
@@ -7,7 +7,7 @@
 
 import 'integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DiagnosticTest);
   });
@@ -15,7 +15,7 @@
 
 @reflectiveTest
 class DiagnosticTest extends AbstractLspAnalysisServerIntegrationTest {
-  test_initialAnalysis() async {
+  Future<void> test_initialAnalysis() async {
     newFile(mainFilePath, content: 'String a = 1;');
 
     final diagnosticsUpdate = waitForDiagnostics(mainFileUri);
@@ -30,7 +30,7 @@
     expect(diagnostic.range.end.character, equals(12));
   }
 
-  test_lints() async {
+  Future<void> test_lints() async {
     newFile(mainFilePath, content: '''main() async => await 1;''');
     newFile(analysisOptionsPath, content: '''
 linter:
diff --git a/pkg/analysis_server/test/integration/lsp_server/initialization_test.dart b/pkg/analysis_server/test/integration/lsp_server/initialization_test.dart
index f38c3dd..7a23822 100644
--- a/pkg/analysis_server/test/integration/lsp_server/initialization_test.dart
+++ b/pkg/analysis_server/test/integration/lsp_server/initialization_test.dart
@@ -9,7 +9,7 @@
 
 import 'integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InitializationTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class InitializationTest extends AbstractLspAnalysisServerIntegrationTest {
-  test_initialize_invalidParams() async {
+  Future<void> test_initialize_invalidParams() async {
     final params = {'processId': 'invalid'};
     final request = RequestMessage(
       Either2<num, String>.t1(1),
diff --git a/pkg/analysis_server/test/integration/lsp_server/integration_tests.dart b/pkg/analysis_server/test/integration/lsp_server/integration_tests.dart
index 6329c7a..5cd0e8d 100644
--- a/pkg/analysis_server/test/integration/lsp_server/integration_tests.dart
+++ b/pkg/analysis_server/test/integration/lsp_server/integration_tests.dart
@@ -46,10 +46,10 @@
     }
   }
 
-  newFile(String path, {String content}) =>
+  void newFile(String path, {String content}) =>
       File(path).writeAsStringSync(content ?? '');
 
-  newFolder(String path) => Directory(path).createSync(recursive: true);
+  void newFolder(String path) => Directory(path).createSync(recursive: true);
 
   @override
   void sendNotificationToServer(NotificationMessage notification) =>
@@ -102,7 +102,7 @@
     });
   }
 
-  tearDown() {
+  void tearDown() {
     // TODO(dantup): Graceful shutdown?
     client.close();
   }
diff --git a/pkg/analysis_server/test/integration/lsp_server/server_test.dart b/pkg/analysis_server/test/integration/lsp_server/server_test.dart
index 8ce240a..12b3f00 100644
--- a/pkg/analysis_server/test/integration/lsp_server/server_test.dart
+++ b/pkg/analysis_server/test/integration/lsp_server/server_test.dart
@@ -10,7 +10,7 @@
 
 import 'integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ServerTest);
   });
@@ -18,7 +18,7 @@
 
 @reflectiveTest
 class ServerTest extends AbstractLspAnalysisServerIntegrationTest {
-  test_diagnosticServer() async {
+  Future<void> test_diagnosticServer() async {
     await initialize();
 
     // Send the custom request to the LSP server to get the Dart diagnostic
@@ -38,7 +38,7 @@
     expect(responseBody, contains('<title>Analysis Server</title>'));
   }
 
-  test_exit_inintializedWithShutdown() async {
+  Future<void> test_exit_inintializedWithShutdown() async {
     await initialize();
     await sendShutdown();
     sendExit();
@@ -53,7 +53,7 @@
     expect(exitCode, equals(0));
   }
 
-  test_exit_initializedWithoutShutdown() async {
+  Future<void> test_exit_initializedWithoutShutdown() async {
     // Send a request that we can wait for, to ensure the server is fully ready
     // before we send exit. Otherwise the exit notification won't be handled for
     // a long time (while the server starts up) and will exceed the 10s timeout.
@@ -70,7 +70,7 @@
     expect(exitCode, equals(1));
   }
 
-  test_exit_uninintializedWithShutdown() async {
+  Future<void> test_exit_uninintializedWithShutdown() async {
     await sendShutdown();
     sendExit();
 
@@ -84,7 +84,7 @@
     expect(exitCode, equals(0));
   }
 
-  test_exit_uninitializedWithoutShutdown() async {
+  Future<void> test_exit_uninitializedWithoutShutdown() async {
     // This tests the same as test_exit_withoutShutdown but without sending
     // initialize. It can't be as strict with the timeout as the server may take
     // time to start up (we can't tell when it's ready without sending a request).
diff --git a/pkg/analysis_server/test/integration/lsp_server/test_all.dart b/pkg/analysis_server/test/integration/lsp_server/test_all.dart
index b171d0a..3c85a81 100644
--- a/pkg/analysis_server/test/integration/lsp_server/test_all.dart
+++ b/pkg/analysis_server/test/integration/lsp_server/test_all.dart
@@ -9,7 +9,7 @@
 import 'initialization_test.dart' as initialization_test;
 import 'server_test.dart' as server_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     analyzer_status.main();
     diagnostic_test.main();
diff --git a/pkg/analysis_server/test/integration/search/find_element_references_test.dart b/pkg/analysis_server/test/integration/search/find_element_references_test.dart
index eac13f5..fa9d879 100644
--- a/pkg/analysis_server/test/integration/search/find_element_references_test.dart
+++ b/pkg/analysis_server/test/integration/search/find_element_references_test.dart
@@ -10,7 +10,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FindElementReferencesTest);
   });
@@ -20,7 +20,7 @@
 class FindElementReferencesTest extends AbstractAnalysisServerIntegrationTest {
   String pathname;
 
-  test_badTarget() async {
+  Future<void> test_badTarget() async {
     String text = r'''
 main() {
   if /* target */ (true) {
@@ -38,7 +38,7 @@
     expect(results, isNull);
   }
 
-  test_findReferences() async {
+  Future<void> test_findReferences() async {
     String text = r'''
 main() {
   foo /* target */ ('Hello');
diff --git a/pkg/analysis_server/test/integration/search/find_member_declarations_test.dart b/pkg/analysis_server/test/integration/search/find_member_declarations_test.dart
index f91ba02..57eb550 100644
--- a/pkg/analysis_server/test/integration/search/find_member_declarations_test.dart
+++ b/pkg/analysis_server/test/integration/search/find_member_declarations_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FindMemberDeclarationsTest);
   });
@@ -18,7 +18,7 @@
 class FindMemberDeclarationsTest extends AbstractAnalysisServerIntegrationTest {
   String pathname;
 
-  test_findMemberDeclarations() async {
+  Future<void> test_findMemberDeclarations() async {
     String text = r'''
 String qux() => 'qux';
 
diff --git a/pkg/analysis_server/test/integration/search/find_member_references_test.dart b/pkg/analysis_server/test/integration/search/find_member_references_test.dart
index 9ffc95f..bb88f5f 100644
--- a/pkg/analysis_server/test/integration/search/find_member_references_test.dart
+++ b/pkg/analysis_server/test/integration/search/find_member_references_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FindMemberReferencesTest);
   });
@@ -18,7 +18,7 @@
 class FindMemberReferencesTest extends AbstractAnalysisServerIntegrationTest {
   String pathname;
 
-  test_findMemberReferences() async {
+  Future<void> test_findMemberReferences() async {
     String text = r'''
 String qux() => 'qux';
 
diff --git a/pkg/analysis_server/test/integration/search/find_top_level_declarations_test.dart b/pkg/analysis_server/test/integration/search/find_top_level_declarations_test.dart
index 4d37e1e..231edca 100644
--- a/pkg/analysis_server/test/integration/search/find_top_level_declarations_test.dart
+++ b/pkg/analysis_server/test/integration/search/find_top_level_declarations_test.dart
@@ -8,7 +8,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FindTopLevelDeclarationsTest);
   });
@@ -19,7 +19,7 @@
     extends AbstractAnalysisServerIntegrationTest {
   String pathname;
 
-  test_findTopLevelDeclarations() async {
+  Future<void> test_findTopLevelDeclarations() async {
     String text = r'''
 String qux() => 'qux';
 
diff --git a/pkg/analysis_server/test/integration/search/get_type_hierarchy_test.dart b/pkg/analysis_server/test/integration/search/get_type_hierarchy_test.dart
index 2924c17..bb662b7 100644
--- a/pkg/analysis_server/test/integration/search/get_type_hierarchy_test.dart
+++ b/pkg/analysis_server/test/integration/search/get_type_hierarchy_test.dart
@@ -11,7 +11,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetTypeHierarchyTest);
   });
diff --git a/pkg/analysis_server/test/integration/search/test_all.dart b/pkg/analysis_server/test/integration/search/test_all.dart
index c7cc8b8..b39f490 100644
--- a/pkg/analysis_server/test/integration/search/test_all.dart
+++ b/pkg/analysis_server/test/integration/search/test_all.dart
@@ -11,10 +11,7 @@
     as find_top_level_declarations_test;
 import 'get_type_hierarchy_test.dart' as get_type_hierarchy_test;
 
-/**
- * Utility for manually running all integration tests.
- */
-main() {
+void main() {
   defineReflectiveSuite(() {
     find_element_references_test.main();
     find_member_declarations_test.main();
diff --git a/pkg/analysis_server/test/integration/server/get_version_test.dart b/pkg/analysis_server/test/integration/server/get_version_test.dart
index 7fca35a..a82ea75 100644
--- a/pkg/analysis_server/test/integration/server/get_version_test.dart
+++ b/pkg/analysis_server/test/integration/server/get_version_test.dart
@@ -6,7 +6,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetVersionTest);
   });
@@ -14,7 +14,7 @@
 
 @reflectiveTest
 class GetVersionTest extends AbstractAnalysisServerIntegrationTest {
-  test_getVersion() {
+  Future<void> test_getVersion() {
     return sendServerGetVersion();
   }
 }
diff --git a/pkg/analysis_server/test/integration/server/set_subscriptions_invalid_service_test.dart b/pkg/analysis_server/test/integration/server/set_subscriptions_invalid_service_test.dart
index 51dc047..afb3195 100644
--- a/pkg/analysis_server/test/integration/server/set_subscriptions_invalid_service_test.dart
+++ b/pkg/analysis_server/test/integration/server/set_subscriptions_invalid_service_test.dart
@@ -7,7 +7,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SetSubscriptionsInvalidTest);
   });
@@ -16,7 +16,7 @@
 @reflectiveTest
 class SetSubscriptionsInvalidTest
     extends AbstractAnalysisServerIntegrationTest {
-  test_setSubscriptions_invalidService() {
+  Future<void> test_setSubscriptions_invalidService() {
     // TODO(paulberry): verify that if an invalid service is specified, the
     // current subscriptions are unchanged.
     return server.send('server.setSubscriptions', {
diff --git a/pkg/analysis_server/test/integration/server/set_subscriptions_test.dart b/pkg/analysis_server/test/integration/server/set_subscriptions_test.dart
index c8538f8..7388d13 100644
--- a/pkg/analysis_server/test/integration/server/set_subscriptions_test.dart
+++ b/pkg/analysis_server/test/integration/server/set_subscriptions_test.dart
@@ -10,7 +10,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SetSubscriptionsTest);
   });
@@ -28,7 +28,7 @@
 @reflectiveTest
 class SetSubscriptionsTest extends AbstractAnalysisServerIntegrationTest {
   @failingTest
-  test_setSubscriptions() {
+  Future<void> test_setSubscriptions() {
     // This test times out on the bots and has been disabled to keep them green.
     // We need to discover the cause and re-enable it.
 
diff --git a/pkg/analysis_server/test/integration/server/shutdown_test.dart b/pkg/analysis_server/test/integration/server/shutdown_test.dart
index 5574266..e43a0b0 100644
--- a/pkg/analysis_server/test/integration/server/shutdown_test.dart
+++ b/pkg/analysis_server/test/integration/server/shutdown_test.dart
@@ -9,7 +9,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ShutdownTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class ShutdownTest extends AbstractAnalysisServerIntegrationTest {
-  test_shutdown() {
+  Future<void> test_shutdown() {
     return sendServerShutdown().then((_) {
       return Future.delayed(Duration(seconds: 1)).then((_) {
         sendServerGetVersion().then((_) {
diff --git a/pkg/analysis_server/test/integration/server/status_test.dart b/pkg/analysis_server/test/integration/server/status_test.dart
index b2c16cb..93126a6 100644
--- a/pkg/analysis_server/test/integration/server/status_test.dart
+++ b/pkg/analysis_server/test/integration/server/status_test.dart
@@ -10,7 +10,7 @@
 
 import '../support/integration_tests.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(StatusTest);
   });
@@ -18,7 +18,7 @@
 
 @reflectiveTest
 class StatusTest extends AbstractAnalysisServerIntegrationTest {
-  test_status() {
+  Future<void> test_status() {
     // After we kick off analysis, we should get one server.status message with
     // analyzing=true, and another server.status message after that with
     // analyzing=false.
diff --git a/pkg/analysis_server/test/integration/server/test_all.dart b/pkg/analysis_server/test/integration/server/test_all.dart
index 2ef3625..0a23427 100644
--- a/pkg/analysis_server/test/integration/server/test_all.dart
+++ b/pkg/analysis_server/test/integration/server/test_all.dart
@@ -11,10 +11,7 @@
 import 'shutdown_test.dart' as shutdown_test;
 import 'status_test.dart' as status_test;
 
-/**
- * Utility for manually running all integration tests.
- */
-main() {
+void main() {
   defineReflectiveSuite(() {
     get_version_test.main();
     set_subscriptions_test.main();
diff --git a/pkg/analysis_server/test/integration/support/integration_tests.dart b/pkg/analysis_server/test/integration/support/integration_tests.dart
index 812fe9d..60ce27b 100644
--- a/pkg/analysis_server/test/integration/support/integration_tests.dart
+++ b/pkg/analysis_server/test/integration/support/integration_tests.dart
@@ -938,7 +938,10 @@
    * the mismatch.  [describeSubstructure] is used to describe which
    * substructure did not match.
    */
-  checkSubstructure(item, Matcher matcher, List<MismatchDescriber> mismatches,
+  void checkSubstructure(
+      item,
+      Matcher matcher,
+      List<MismatchDescriber> mismatches,
       Description Function(Description) describeSubstructure) {
     Map subState = {};
     if (!matcher.matches(item, subState)) {
diff --git a/pkg/analysis_server/test/integration/test_all.dart b/pkg/analysis_server/test/integration/test_all.dart
index 3c601b3..9ef661b 100644
--- a/pkg/analysis_server/test/integration/test_all.dart
+++ b/pkg/analysis_server/test/integration/test_all.dart
@@ -17,7 +17,7 @@
 import 'search/test_all.dart' as search;
 import 'server/test_all.dart' as server;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     analysis.main();
     analytics.main();
diff --git a/pkg/analysis_server/test/lsp/analyzer_status_test.dart b/pkg/analysis_server/test/lsp/analyzer_status_test.dart
index 4ddd08f..dec6895 100644
--- a/pkg/analysis_server/test/lsp/analyzer_status_test.dart
+++ b/pkg/analysis_server/test/lsp/analyzer_status_test.dart
@@ -7,7 +7,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalyzerStatusTest);
   });
@@ -15,27 +15,7 @@
 
 @reflectiveTest
 class AnalyzerStatusTest extends AbstractLspAnalysisServerTest {
-  test_afterInitialize() async {
-    const initialContents = 'int a = 1;';
-    newFile(mainFilePath, content: initialContents);
-
-    // To avoid races, set up listeners for the notifications before we initialise
-    // and track which event came first to ensure they arrived in the expected
-    // order.
-    bool firstNotificationWasAnalyzing;
-    final startNotification = waitForAnalysisStart()
-        .then((_) => firstNotificationWasAnalyzing ??= true);
-    final completeNotification = waitForAnalysisComplete()
-        .then((_) => firstNotificationWasAnalyzing ??= false);
-
-    await initialize();
-    await startNotification;
-    await completeNotification;
-
-    expect(firstNotificationWasAnalyzing, isTrue);
-  }
-
-  test_afterDocumentEdits() async {
+  Future<void> test_afterDocumentEdits() async {
     const initialContents = 'int a = 1;';
     newFile(mainFilePath, content: initialContents);
 
@@ -56,4 +36,24 @@
     await startNotification;
     await completeNotification;
   }
+
+  Future<void> test_afterInitialize() async {
+    const initialContents = 'int a = 1;';
+    newFile(mainFilePath, content: initialContents);
+
+    // To avoid races, set up listeners for the notifications before we initialise
+    // and track which event came first to ensure they arrived in the expected
+    // order.
+    bool firstNotificationWasAnalyzing;
+    final startNotification = waitForAnalysisStart()
+        .then((_) => firstNotificationWasAnalyzing ??= true);
+    final completeNotification = waitForAnalysisComplete()
+        .then((_) => firstNotificationWasAnalyzing ??= false);
+
+    await initialize();
+    await startNotification;
+    await completeNotification;
+
+    expect(firstNotificationWasAnalyzing, isTrue);
+  }
 }
diff --git a/pkg/analysis_server/test/lsp/cancel_request_test.dart b/pkg/analysis_server/test/lsp/cancel_request_test.dart
index ce460a6..6e065b9 100644
--- a/pkg/analysis_server/test/lsp/cancel_request_test.dart
+++ b/pkg/analysis_server/test/lsp/cancel_request_test.dart
@@ -9,7 +9,7 @@
 import '../tool/lsp_spec/matchers.dart';
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CancelRequestTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class CancelRequestTest extends AbstractLspAnalysisServerTest {
-  test_cancel() async {
+  Future<void> test_cancel() async {
     final content = '''
 main() {
   InOtherF^
diff --git a/pkg/analysis_server/test/lsp/change_workspace_folders_test.dart b/pkg/analysis_server/test/lsp/change_workspace_folders_test.dart
index fd0e3c0..ef38052 100644
--- a/pkg/analysis_server/test/lsp/change_workspace_folders_test.dart
+++ b/pkg/analysis_server/test/lsp/change_workspace_folders_test.dart
@@ -7,7 +7,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ChangeWorkspaceFoldersTest);
   });
@@ -29,7 +29,7 @@
     workspaceFolder3Uri = Uri.file(workspaceFolder3Path);
   }
 
-  test_changeWorkspaceFolders_add() async {
+  Future<void> test_changeWorkspaceFolders_add() async {
     await initialize(rootUri: workspaceFolder1Uri);
     await changeWorkspaceFolders(
         add: [workspaceFolder2Uri, workspaceFolder3Uri]);
@@ -44,7 +44,7 @@
     );
   }
 
-  test_changeWorkspaceFolders_addAndRemove() async {
+  Future<void> test_changeWorkspaceFolders_addAndRemove() async {
     await initialize(
       workspaceFolders: [workspaceFolder1Uri, workspaceFolder2Uri],
     );
@@ -59,7 +59,7 @@
     );
   }
 
-  test_changeWorkspaceFolders_remove() async {
+  Future<void> test_changeWorkspaceFolders_remove() async {
     await initialize(
       workspaceFolders: [workspaceFolder1Uri, workspaceFolder2Uri],
     );
@@ -73,7 +73,7 @@
     );
   }
 
-  test_changeWorkspaceFolders_removeFlushesDiagnostics() async {
+  Future<void> test_changeWorkspaceFolders_removeFlushesDiagnostics() async {
     // Add our standard test project as well as a dummy project.
     await initialize(workspaceFolders: [projectFolderUri, workspaceFolder1Uri]);
 
diff --git a/pkg/analysis_server/test/lsp/closing_labels_test.dart b/pkg/analysis_server/test/lsp/closing_labels_test.dart
index 0732276..4a671a6 100644
--- a/pkg/analysis_server/test/lsp/closing_labels_test.dart
+++ b/pkg/analysis_server/test/lsp/closing_labels_test.dart
@@ -7,7 +7,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ClosingLabelsTest);
   });
@@ -15,7 +15,7 @@
 
 @reflectiveTest
 class ClosingLabelsTest extends AbstractLspAnalysisServerTest {
-  test_afterChange() async {
+  Future<void> test_afterChange() async {
     final initialContent = 'main() {}';
     final updatedContent = '''
 Widget build(BuildContext context) {
@@ -56,7 +56,7 @@
     expect(second.range.end.character, equals(5));
   }
 
-  test_initial() async {
+  Future<void> test_initial() async {
     final content = '''
 Widget build(BuildContext context) {
   return new Row(         // Row       1:9
diff --git a/pkg/analysis_server/test/lsp/code_actions_assists_test.dart b/pkg/analysis_server/test/lsp/code_actions_assists_test.dart
index 7c37bec..88ab0fd 100644
--- a/pkg/analysis_server/test/lsp/code_actions_assists_test.dart
+++ b/pkg/analysis_server/test/lsp/code_actions_assists_test.dart
@@ -8,7 +8,7 @@
 
 import 'code_actions_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AssistsCodeActionsTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class AssistsCodeActionsTest extends AbstractCodeActionsTest {
-  test_appliesCorrectEdits_withDocumentChangesSupport() async {
+  Future<void> test_appliesCorrectEdits_withDocumentChangesSupport() async {
     // This code should get an assist to add a show combinator.
     const content = '''
     import '[[dart:async]]';
@@ -55,7 +55,7 @@
     expect(contents[mainFilePath], equals(expectedContent));
   }
 
-  test_appliesCorrectEdits_withoutDocumentChangesSupport() async {
+  Future<void> test_appliesCorrectEdits_withoutDocumentChangesSupport() async {
     // This code should get an assist to add a show combinator.
     const content = '''
     import '[[dart:async]]';
@@ -92,7 +92,7 @@
     expect(contents[mainFilePath], equals(expectedContent));
   }
 
-  test_nonDartFile() async {
+  Future<void> test_nonDartFile() async {
     await newFile(pubspecFilePath, content: simplePubspecContent);
     await initialize(
       textDocumentCapabilities: withCodeActionKinds(
diff --git a/pkg/analysis_server/test/lsp/code_actions_fixes_test.dart b/pkg/analysis_server/test/lsp/code_actions_fixes_test.dart
index daadf31..fa93a77 100644
--- a/pkg/analysis_server/test/lsp/code_actions_fixes_test.dart
+++ b/pkg/analysis_server/test/lsp/code_actions_fixes_test.dart
@@ -8,7 +8,7 @@
 
 import 'code_actions_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FixesCodeActionsTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class FixesCodeActionsTest extends AbstractCodeActionsTest {
-  test_appliesCorrectEdits_withDocumentChangesSupport() async {
+  Future<void> test_appliesCorrectEdits_withDocumentChangesSupport() async {
     // This code should get a fix to remove the unused import.
     const content = '''
     import 'dart:async';
@@ -56,7 +56,7 @@
     expect(contents[mainFilePath], equals(expectedContent));
   }
 
-  test_appliesCorrectEdits_withoutDocumentChangesSupport() async {
+  Future<void> test_appliesCorrectEdits_withoutDocumentChangesSupport() async {
     // This code should get a fix to remove the unused import.
     const content = '''
     import 'dart:async';
@@ -94,7 +94,7 @@
     expect(contents[mainFilePath], equals(expectedContent));
   }
 
-  test_nonDartFile() async {
+  Future<void> test_nonDartFile() async {
     await newFile(pubspecFilePath, content: simplePubspecContent);
     await initialize(
       textDocumentCapabilities: withCodeActionKinds(
diff --git a/pkg/analysis_server/test/lsp/code_actions_refactor_test.dart b/pkg/analysis_server/test/lsp/code_actions_refactor_test.dart
index 6a1cd63..b733be9 100644
--- a/pkg/analysis_server/test/lsp/code_actions_refactor_test.dart
+++ b/pkg/analysis_server/test/lsp/code_actions_refactor_test.dart
@@ -9,7 +9,7 @@
 import '../src/utilities/mock_packages.dart';
 import 'code_actions_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ExtractMethodRefactorCodeActionsTest);
     defineReflectiveTests(ExtractWidgetRefactorCodeActionsTest);
@@ -19,7 +19,7 @@
 @reflectiveTest
 class ExtractMethodRefactorCodeActionsTest extends AbstractCodeActionsTest {
   final extractMethodTitle = 'Extract Method';
-  test_appliesCorrectEdits() async {
+  Future<void> test_appliesCorrectEdits() async {
     const content = '''
 main() {
   print('Test!');
@@ -49,7 +49,7 @@
         codeAction, withoutMarkers(content), expectedContent);
   }
 
-  test_invalidLocation() async {
+  Future<void> test_invalidLocation() async {
     const content = '''
 import 'dart:convert';
 ^
@@ -82,7 +82,7 @@
 ''');
   }
 
-  test_appliesCorrectEdits() async {
+  Future<void> test_appliesCorrectEdits() async {
     const content = '''
 import 'package:flutter/material.dart';
 
@@ -149,7 +149,7 @@
         codeAction, withoutMarkers(content), expectedContent);
   }
 
-  test_invalidLocation() async {
+  Future<void> test_invalidLocation() async {
     const content = '''
 import 'dart:convert';
 ^
diff --git a/pkg/analysis_server/test/lsp/code_actions_source_test.dart b/pkg/analysis_server/test/lsp/code_actions_source_test.dart
index 57726d2..676c9ba 100644
--- a/pkg/analysis_server/test/lsp/code_actions_source_test.dart
+++ b/pkg/analysis_server/test/lsp/code_actions_source_test.dart
@@ -10,7 +10,7 @@
 import '../tool/lsp_spec/matchers.dart';
 import 'code_actions_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SortMembersSourceCodeActionsTest);
     defineReflectiveTests(OrganizeImportsSourceCodeActionsTest);
@@ -19,7 +19,7 @@
 
 @reflectiveTest
 class OrganizeImportsSourceCodeActionsTest extends AbstractCodeActionsTest {
-  test_appliesCorrectEdits_withDocumentChangesSupport() async {
+  Future<void> test_appliesCorrectEdits_withDocumentChangesSupport() async {
     const content = '''
 import 'dart:math';
 import 'dart:async';
@@ -48,7 +48,7 @@
         expectDocumentChanges: true);
   }
 
-  test_appliesCorrectEdits_withoutDocumentChangesSupport() async {
+  Future<void> test_appliesCorrectEdits_withoutDocumentChangesSupport() async {
     const content = '''
 import 'dart:math';
 import 'dart:async';
@@ -76,7 +76,7 @@
     await verifyCodeActionEdits(codeAction, content, expectedContent);
   }
 
-  test_availableAsCodeActionLiteral() async {
+  Future<void> test_availableAsCodeActionLiteral() async {
     await newFile(mainFilePath);
     await initialize(
         textDocumentCapabilities: withCodeActionKinds(
@@ -92,7 +92,7 @@
     );
   }
 
-  test_availableAsCommand() async {
+  Future<void> test_availableAsCommand() async {
     await newFile(mainFilePath);
     await initialize(
         workspaceCapabilities:
@@ -106,7 +106,7 @@
     );
   }
 
-  test_failsIfFileHasErrors() async {
+  Future<void> test_failsIfFileHasErrors() async {
     final content = 'invalid dart code';
     await newFile(mainFilePath, content: content);
     await initialize(
@@ -128,7 +128,7 @@
         throwsA(isResponseError(ServerErrorCodes.FileHasErrors)));
   }
 
-  test_noEdits() async {
+  Future<void> test_noEdits() async {
     const content = '''
 import 'dart:async';
 import 'dart:math';
@@ -157,7 +157,7 @@
     expect(commandResponse, isNull);
   }
 
-  test_unavailableWhenNotRequested() async {
+  Future<void> test_unavailableWhenNotRequested() async {
     await newFile(mainFilePath);
     await initialize(
         textDocumentCapabilities: withCodeActionKinds(
@@ -170,7 +170,7 @@
     expect(codeAction, isNull);
   }
 
-  test_unavailableWithoutApplyEditSupport() async {
+  Future<void> test_unavailableWithoutApplyEditSupport() async {
     await newFile(mainFilePath);
     await initialize();
 
@@ -182,7 +182,7 @@
 
 @reflectiveTest
 class SortMembersSourceCodeActionsTest extends AbstractCodeActionsTest {
-  test_appliesCorrectEdits_withDocumentChangesSupport() async {
+  Future<void> test_appliesCorrectEdits_withDocumentChangesSupport() async {
     const content = '''
     String b;
     String a;
@@ -204,7 +204,7 @@
         expectDocumentChanges: true);
   }
 
-  test_appliesCorrectEdits_withoutDocumentChangesSupport() async {
+  Future<void> test_appliesCorrectEdits_withoutDocumentChangesSupport() async {
     const content = '''
     String b;
     String a;
@@ -225,7 +225,7 @@
     await verifyCodeActionEdits(codeAction, content, expectedContent);
   }
 
-  test_availableAsCodeActionLiteral() async {
+  Future<void> test_availableAsCodeActionLiteral() async {
     await newFile(mainFilePath);
     await initialize(
         textDocumentCapabilities: withCodeActionKinds(
@@ -241,7 +241,7 @@
     );
   }
 
-  test_availableAsCommand() async {
+  Future<void> test_availableAsCommand() async {
     await newFile(mainFilePath);
     await initialize(
         workspaceCapabilities:
@@ -255,7 +255,7 @@
     );
   }
 
-  test_failsIfClientDoesntApplyEdits() async {
+  Future<void> test_failsIfClientDoesntApplyEdits() async {
     const content = '''
     String b;
     String a;
@@ -290,7 +290,7 @@
         throwsA(isResponseError(ServerErrorCodes.ClientFailedToApplyEdit)));
   }
 
-  test_failsIfFileHasErrors() async {
+  Future<void> test_failsIfFileHasErrors() async {
     final content = 'invalid dart code';
     await newFile(mainFilePath, content: content);
     await initialize(
@@ -312,7 +312,7 @@
         throwsA(isResponseError(ServerErrorCodes.FileHasErrors)));
   }
 
-  test_nonDartFile() async {
+  Future<void> test_nonDartFile() async {
     await newFile(pubspecFilePath, content: simplePubspecContent);
     await initialize(
         textDocumentCapabilities: withCodeActionKinds(
@@ -325,7 +325,7 @@
     expect(codeActions, isEmpty);
   }
 
-  test_unavailableWhenNotRequested() async {
+  Future<void> test_unavailableWhenNotRequested() async {
     await newFile(mainFilePath);
     await initialize(
         textDocumentCapabilities: withCodeActionKinds(
@@ -338,7 +338,7 @@
     expect(codeAction, isNull);
   }
 
-  test_unavailableWithoutApplyEditSupport() async {
+  Future<void> test_unavailableWithoutApplyEditSupport() async {
     await newFile(mainFilePath);
     await initialize();
 
diff --git a/pkg/analysis_server/test/lsp/completion_test.dart b/pkg/analysis_server/test/lsp/completion_test.dart
index 24fb0d2..e0e4f19 100644
--- a/pkg/analysis_server/test/lsp/completion_test.dart
+++ b/pkg/analysis_server/test/lsp/completion_test.dart
@@ -9,7 +9,7 @@
 import '../tool/lsp_spec/matchers.dart';
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CompletionTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class CompletionTest extends AbstractLspAnalysisServerTest {
-  expectAutoImportCompletion(List<CompletionItem> items, String file) {
+  void expectAutoImportCompletion(List<CompletionItem> items, String file) {
     expect(
       items.singleWhere(
         (c) => c.detail?.contains("Auto import from '$file'") ?? false,
@@ -27,7 +27,7 @@
     );
   }
 
-  test_completionKinds_default() async {
+  Future<void> test_completionKinds_default() async {
     newFile(join(projectFolderPath, 'file.dart'));
     newFolder(join(projectFolderPath, 'folder'));
 
@@ -47,7 +47,7 @@
     expect(builtin.kind, equals(CompletionItemKind.Module));
   }
 
-  test_completionKinds_imports() async {
+  Future<void> test_completionKinds_imports() async {
     final content = "import '^';";
 
     // Tell the server we support some specific CompletionItemKinds.
@@ -72,7 +72,7 @@
     expect(builtin.kind, equals(CompletionItemKind.Module));
   }
 
-  test_completionKinds_supportedSubset() async {
+  Future<void> test_completionKinds_supportedSubset() async {
     final content = '''
     class MyClass {
       String abcdefghij;
@@ -100,7 +100,7 @@
     );
   }
 
-  test_completionTriggerKinds_invalidParams() async {
+  Future<void> test_completionTriggerKinds_invalidParams() async {
     await initialize();
 
     final invalidTriggerKind = CompletionTriggerKind.fromJson(-1);
@@ -114,7 +114,7 @@
         request, throwsA(isResponseError(ErrorCodes.InvalidParams)));
   }
 
-  test_gettersAndSetters() async {
+  Future<void> test_gettersAndSetters() async {
     final content = '''
     class MyClass {
       String get justGetter => '';
@@ -143,7 +143,7 @@
     });
   }
 
-  test_insideString() async {
+  Future<void> test_insideString() async {
     final content = '''
     var a = "This is ^a test"
     ''';
@@ -154,7 +154,7 @@
     expect(res, isEmpty);
   }
 
-  test_isDeprecated_notSupported() async {
+  Future<void> test_isDeprecated_notSupported() async {
     final content = '''
     class MyClass {
       @deprecated
@@ -177,7 +177,7 @@
     expect(item.detail.toLowerCase(), contains('deprecated'));
   }
 
-  test_isDeprecated_supported() async {
+  Future<void> test_isDeprecated_supported() async {
     final content = '''
     class MyClass {
       @deprecated
@@ -202,7 +202,7 @@
     expect(item.detail, isNot(contains('deprecated')));
   }
 
-  test_namedArg_plainText() async {
+  Future<void> test_namedArg_plainText() async {
     final content = '''
     class A { const A({int one}); }
     @A(^)
@@ -221,7 +221,7 @@
     expect(updated, contains('one: '));
   }
 
-  test_namedArg_snippetStringSelection() async {
+  Future<void> test_namedArg_snippetStringSelection() async {
     final content = '''
     class A { const A({int one}); }
     @A(^)
@@ -246,7 +246,7 @@
     );
   }
 
-  test_nonDartFile() async {
+  Future<void> test_nonDartFile() async {
     newFile(pubspecFilePath, content: simplePubspecContent);
     await initialize();
 
@@ -254,7 +254,25 @@
     expect(res, isEmpty);
   }
 
-  test_plainText() async {
+  Future<void> test_parensNotInFilterTextInsertText() async {
+    final content = '''
+    class MyClass {}
+
+    main() {
+      MyClass a = new MyCla^
+    }
+    ''';
+
+    await initialize();
+    await openFile(mainFileUri, withoutMarkers(content));
+    final res = await getCompletion(mainFileUri, positionFromMarker(content));
+    expect(res.any((c) => c.label == 'MyClass()'), isTrue);
+    final item = res.singleWhere((c) => c.label == 'MyClass()');
+    expect(item.filterText, equals('MyClass'));
+    expect(item.insertText, equals('MyClass'));
+  }
+
+  Future<void> test_plainText() async {
     final content = '''
     class MyClass {
       String abcdefghij;
@@ -278,25 +296,7 @@
     expect(updated, contains('a.abcdefghij'));
   }
 
-  test_parensNotInFilterTextInsertText() async {
-    final content = '''
-    class MyClass {}
-
-    main() {
-      MyClass a = new MyCla^
-    }
-    ''';
-
-    await initialize();
-    await openFile(mainFileUri, withoutMarkers(content));
-    final res = await getCompletion(mainFileUri, positionFromMarker(content));
-    expect(res.any((c) => c.label == 'MyClass()'), isTrue);
-    final item = res.singleWhere((c) => c.label == 'MyClass()');
-    expect(item.filterText, equals('MyClass'));
-    expect(item.insertText, equals('MyClass'));
-  }
-
-  test_suggestionSets() async {
+  Future<void> test_suggestionSets() async {
     newFile(
       join(projectFolderPath, 'other_file.dart'),
       content: '''
@@ -367,7 +367,7 @@
     '''));
   }
 
-  test_suggestionSets_doesNotFilterSymbolsWithSameName() async {
+  Future<void> test_suggestionSets_doesNotFilterSymbolsWithSameName() async {
     // Classes here are not re-exports, so should not be filtered out.
     newFile(
       join(projectFolderPath, 'source_file1.dart'),
@@ -409,7 +409,7 @@
     expectAutoImportCompletion(resolvedCompletions, '../source_file3.dart');
   }
 
-  test_suggestionSets_enumValues() async {
+  Future<void> test_suggestionSets_enumValues() async {
     newFile(
       join(projectFolderPath, 'source_file.dart'),
       content: '''
@@ -471,7 +471,7 @@
     '''));
   }
 
-  test_suggestionSets_enumValuesAlreadyImported() async {
+  Future<void> test_suggestionSets_enumValuesAlreadyImported() async {
     newFile(
       join(projectFolderPath, 'source_file.dart'),
       content: '''
@@ -515,7 +515,7 @@
     expect(resolved.detail, isNull);
   }
 
-  test_suggestionSets_filtersOutAlreadyImportedSymbols() async {
+  Future<void> test_suggestionSets_filtersOutAlreadyImportedSymbols() async {
     newFile(
       join(projectFolderPath, 'source_file.dart'),
       content: '''
@@ -558,64 +558,8 @@
     expect(resolved.detail, isNull);
   }
 
-  test_suggestionSets_namedConstructors() async {
-    newFile(
-      join(projectFolderPath, 'other_file.dart'),
-      content: '''
-      /// This class is in another file.
-      class InOtherFile {
-        InOtherFile.fromJson() {}
-      }
-      ''',
-    );
-
-    final content = '''
-main() {
-  var a = InOtherF^
-}
-    ''';
-
-    final initialAnalysis = waitForAnalysisComplete();
-    await initialize(
-        workspaceCapabilities:
-            withApplyEditSupport(emptyWorkspaceClientCapabilities));
-    await openFile(mainFileUri, withoutMarkers(content));
-    await initialAnalysis;
-    final res = await getCompletion(mainFileUri, positionFromMarker(content));
-
-    // Find the completion for the class in the other file.
-    final completion =
-        res.singleWhere((c) => c.label == 'InOtherFile.fromJson()');
-    expect(completion, isNotNull);
-
-    // Expect no docs or text edit, since these are added during resolve.
-    expect(completion.documentation, isNull);
-    expect(completion.textEdit, isNull);
-
-    // Resolve the completion item (via server) to get its edits. This is the
-    // LSP's equiv of getSuggestionDetails() and is invoked by LSP clients to
-    // populate additional info (in our case, the additional edits for inserting
-    // the import).
-    final resolved = await resolveCompletion(completion);
-    expect(resolved, isNotNull);
-
-    // Apply both the main completion edit and the additionalTextEdits atomically.
-    final newContent = applyTextEdits(
-      withoutMarkers(content),
-      [resolved.textEdit].followedBy(resolved.additionalTextEdits).toList(),
-    );
-
-    // Ensure both edits were made - the completion, and the inserted import.
-    expect(newContent, equals('''
-import '../other_file.dart';
-
-main() {
-  var a = InOtherFile.fromJson
-}
-    '''));
-  }
-
-  test_suggestionSets_includesReexportedSymbolsForEachFile() async {
+  Future<void>
+      test_suggestionSets_includesReexportedSymbolsForEachFile() async {
     newFile(
       join(projectFolderPath, 'source_file.dart'),
       content: '''
@@ -661,7 +605,7 @@
     expectAutoImportCompletion(resolvedCompletions, '../reexport2.dart');
   }
 
-  test_suggestionSets_insertsIntoPartFiles() async {
+  Future<void> test_suggestionSets_insertsIntoPartFiles() async {
     // File we'll be adding an import for.
     newFile(
       join(projectFolderPath, 'other_file.dart'),
@@ -749,7 +693,64 @@
 part 'main.dart';'''));
   }
 
-  test_suggestionSets_unavailableIfDisabled() async {
+  Future<void> test_suggestionSets_namedConstructors() async {
+    newFile(
+      join(projectFolderPath, 'other_file.dart'),
+      content: '''
+      /// This class is in another file.
+      class InOtherFile {
+        InOtherFile.fromJson() {}
+      }
+      ''',
+    );
+
+    final content = '''
+main() {
+  var a = InOtherF^
+}
+    ''';
+
+    final initialAnalysis = waitForAnalysisComplete();
+    await initialize(
+        workspaceCapabilities:
+            withApplyEditSupport(emptyWorkspaceClientCapabilities));
+    await openFile(mainFileUri, withoutMarkers(content));
+    await initialAnalysis;
+    final res = await getCompletion(mainFileUri, positionFromMarker(content));
+
+    // Find the completion for the class in the other file.
+    final completion =
+        res.singleWhere((c) => c.label == 'InOtherFile.fromJson()');
+    expect(completion, isNotNull);
+
+    // Expect no docs or text edit, since these are added during resolve.
+    expect(completion.documentation, isNull);
+    expect(completion.textEdit, isNull);
+
+    // Resolve the completion item (via server) to get its edits. This is the
+    // LSP's equiv of getSuggestionDetails() and is invoked by LSP clients to
+    // populate additional info (in our case, the additional edits for inserting
+    // the import).
+    final resolved = await resolveCompletion(completion);
+    expect(resolved, isNotNull);
+
+    // Apply both the main completion edit and the additionalTextEdits atomically.
+    final newContent = applyTextEdits(
+      withoutMarkers(content),
+      [resolved.textEdit].followedBy(resolved.additionalTextEdits).toList(),
+    );
+
+    // Ensure both edits were made - the completion, and the inserted import.
+    expect(newContent, equals('''
+import '../other_file.dart';
+
+main() {
+  var a = InOtherFile.fromJson
+}
+    '''));
+  }
+
+  Future<void> test_suggestionSets_unavailableIfDisabled() async {
     newFile(
       join(projectFolderPath, 'other_file.dart'),
       content: 'class InOtherFile {}',
@@ -781,7 +782,7 @@
     expect(completion, isNull);
   }
 
-  test_suggestionSets_unavailableWithoutApplyEdit() async {
+  Future<void> test_suggestionSets_unavailableWithoutApplyEdit() async {
     // If client doesn't advertise support for workspace/applyEdit, we won't
     // include suggestion sets.
     newFile(
@@ -810,7 +811,7 @@
     expect(completion, isNull);
   }
 
-  test_unopenFile() async {
+  Future<void> test_unopenFile() async {
     final content = '''
     class MyClass {
       String abcdefghij;
diff --git a/pkg/analysis_server/test/lsp/definition_test.dart b/pkg/analysis_server/test/lsp/definition_test.dart
index a7df3fe..25680ff 100644
--- a/pkg/analysis_server/test/lsp/definition_test.dart
+++ b/pkg/analysis_server/test/lsp/definition_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DefinitionTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class DefinitionTest extends AbstractLspAnalysisServerTest {
-  test_acrossFiles() async {
+  Future<void> test_acrossFiles() async {
     final mainContents = '''
     import 'referenced.dart';
 
@@ -53,7 +53,7 @@
     expect(loc.uri, equals(referencedFileUri.toString()));
   }
 
-  test_nonDartFile() async {
+  Future<void> test_nonDartFile() async {
     newFile(pubspecFilePath, content: simplePubspecContent);
     await initialize();
 
@@ -61,7 +61,7 @@
     expect(res, isEmpty);
   }
 
-  test_singleFile() async {
+  Future<void> test_singleFile() async {
     final contents = '''
     [[foo]]() {
       fo^o();
@@ -78,7 +78,7 @@
     expect(loc.uri, equals(mainFileUri.toString()));
   }
 
-  test_unopenFile() async {
+  Future<void> test_unopenFile() async {
     final contents = '''
     [[foo]]() {
       fo^o();
diff --git a/pkg/analysis_server/test/lsp/diagnostic_test.dart b/pkg/analysis_server/test/lsp/diagnostic_test.dart
index 8ff865f..123a064 100644
--- a/pkg/analysis_server/test/lsp/diagnostic_test.dart
+++ b/pkg/analysis_server/test/lsp/diagnostic_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DiagnosticTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class DiagnosticTest extends AbstractLspAnalysisServerTest {
-  test_afterDocumentEdits() async {
+  Future<void> test_afterDocumentEdits() async {
     const initialContents = 'int a = 1;';
     newFile(mainFilePath, content: initialContents);
 
@@ -33,7 +33,7 @@
     expect(updatedDiagnostics, hasLength(1));
   }
 
-  test_contextMessage() async {
+  Future<void> test_contextMessage() async {
     newFile(mainFilePath, content: '''
 void f() {
   x = 0;
@@ -50,7 +50,7 @@
     expect(diagnostic.relatedInformation, hasLength(1));
   }
 
-  test_correction() async {
+  Future<void> test_correction() async {
     newFile(mainFilePath, content: '''
 void f() {
   x = 0;
@@ -65,7 +65,7 @@
     expect(diagnostic.message, contains('\nTry'));
   }
 
-  test_deletedFile() async {
+  Future<void> test_deletedFile() async {
     newFile(mainFilePath, content: 'String a = 1;');
 
     final firstDiagnosticsUpdate = waitForDiagnostics(mainFileUri);
@@ -80,7 +80,7 @@
     expect(updatedDiagnostics, hasLength(0));
   }
 
-  test_dotFilesExcluded() async {
+  Future<void> test_dotFilesExcluded() async {
     var dotFolderFilePath =
         join(projectFolderPath, '.dart_tool', 'tool_file.dart');
     var dotFolderFileUri = Uri.file(dotFolderFilePath);
@@ -99,7 +99,7 @@
     expect(diagnostics, isNull);
   }
 
-  test_initialAnalysis() async {
+  Future<void> test_initialAnalysis() async {
     newFile(mainFilePath, content: 'String a = 1;');
 
     final diagnosticsUpdate = waitForDiagnostics(mainFileUri);
@@ -114,7 +114,7 @@
     expect(diagnostic.range.end.character, equals(12));
   }
 
-  test_todos() async {
+  Future<void> test_todos() async {
     // TODOs only show up if there's also some code in the file.
     const initialContents = '''
     // TODO: This
diff --git a/pkg/analysis_server/test/lsp/document_highlights_test.dart b/pkg/analysis_server/test/lsp/document_highlights_test.dart
index 374dd1d..aba5b75 100644
--- a/pkg/analysis_server/test/lsp/document_highlights_test.dart
+++ b/pkg/analysis_server/test/lsp/document_highlights_test.dart
@@ -7,7 +7,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DocumentHighlightsTest);
   });
@@ -15,13 +15,13 @@
 
 @reflectiveTest
 class DocumentHighlightsTest extends AbstractLspAnalysisServerTest {
-  test_functions() => _testMarkedContent('''
+  Future<void> test_functions() => _testMarkedContent('''
     [[main]]() {
       [[mai^n]]();
     }
     ''');
 
-  test_localVariable() => _testMarkedContent('''
+  Future<void> test_localVariable() => _testMarkedContent('''
     main() {
       var [[f^oo]] = 1;
       print([[foo]]);
@@ -29,7 +29,7 @@
     }
     ''');
 
-  test_nonDartFile() async {
+  Future<void> test_nonDartFile() async {
     await initialize();
     await openFile(pubspecFileUri, simplePubspecContent);
 
@@ -40,19 +40,19 @@
     expect(highlights, isEmpty);
   }
 
-  test_noResult() => _testMarkedContent('''
+  Future<void> test_noResult() => _testMarkedContent('''
     main() {
       // This one is in a ^ comment!
     }
     ''');
 
-  test_onlySelf() => _testMarkedContent('''
+  Future<void> test_onlySelf() => _testMarkedContent('''
     main() {
       [[prin^t]]();
     }
     ''');
 
-  test_shadow_inner() => _testMarkedContent('''
+  Future<void> test_shadow_inner() => _testMarkedContent('''
     main() {
       var foo = 1;
       func() {
@@ -62,7 +62,7 @@
     }
     ''');
 
-  test_shadow_outer() => _testMarkedContent('''
+  Future<void> test_shadow_outer() => _testMarkedContent('''
     main() {
       var [[foo]] = 1;
       func() {
@@ -73,7 +73,7 @@
     }
     ''');
 
-  test_topLevelVariable() => _testMarkedContent('''
+  Future<void> test_topLevelVariable() => _testMarkedContent('''
     String [[foo]] = 'bar';
     main() {
       print([[foo]]);
@@ -87,7 +87,7 @@
   /// be highlighted (eg. all references to the symbol under ^).
   /// If the content does not include any `[[double brackets]]` then the response
   /// is expected to be `null`.
-  _testMarkedContent(String content) async {
+  Future<void> _testMarkedContent(String content) async {
     final expectedRanges = rangesFromMarkers(content);
 
     await initialize();
diff --git a/pkg/analysis_server/test/lsp/document_symbols_test.dart b/pkg/analysis_server/test/lsp/document_symbols_test.dart
index 6d56201..05c01fc 100644
--- a/pkg/analysis_server/test/lsp/document_symbols_test.dart
+++ b/pkg/analysis_server/test/lsp/document_symbols_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DocumentSymbolsTest);
   });
@@ -16,51 +16,7 @@
 
 @reflectiveTest
 class DocumentSymbolsTest extends AbstractLspAnalysisServerTest {
-  test_hierarchical() async {
-    const content = '''
-    String topLevel = '';
-    class MyClass {
-      int myField;
-      MyClass(this.myField);
-      myMethod() {}
-    }
-    ''';
-    newFile(mainFilePath, content: content);
-    await initialize(
-        textDocumentCapabilities: withHierarchicalDocumentSymbolSupport(
-            emptyTextDocumentClientCapabilities));
-
-    final result = await getDocumentSymbols(mainFileUri.toString());
-    final symbols = result.map(
-      (docsymbols) => docsymbols,
-      (symbolInfos) => throw 'Expected DocumentSymbols, got SymbolInformations',
-    );
-
-    expect(symbols, hasLength(2));
-
-    final topLevel = symbols[0];
-    expect(topLevel.name, equals('topLevel'));
-    expect(topLevel.kind, equals(SymbolKind.Variable));
-
-    final myClass = symbols[1];
-    expect(myClass.name, equals('MyClass'));
-    expect(myClass.kind, equals(SymbolKind.Class));
-    expect(myClass.children, hasLength(3));
-
-    final field = myClass.children[0];
-    expect(field.name, equals('myField'));
-    expect(field.kind, equals(SymbolKind.Field));
-
-    final constructor = myClass.children[1];
-    expect(constructor.name, equals('MyClass'));
-    expect(constructor.kind, equals(SymbolKind.Constructor));
-
-    final method = myClass.children[2];
-    expect(method.name, equals('myMethod'));
-    expect(method.kind, equals(SymbolKind.Method));
-  }
-
-  test_flat() async {
+  Future<void> test_flat() async {
     const content = '''
     String topLevel = '';
     class MyClass {
@@ -105,7 +61,51 @@
     expect(method.containerName, equals(myClass.name));
   }
 
-  test_nonDartFile() async {
+  Future<void> test_hierarchical() async {
+    const content = '''
+    String topLevel = '';
+    class MyClass {
+      int myField;
+      MyClass(this.myField);
+      myMethod() {}
+    }
+    ''';
+    newFile(mainFilePath, content: content);
+    await initialize(
+        textDocumentCapabilities: withHierarchicalDocumentSymbolSupport(
+            emptyTextDocumentClientCapabilities));
+
+    final result = await getDocumentSymbols(mainFileUri.toString());
+    final symbols = result.map(
+      (docsymbols) => docsymbols,
+      (symbolInfos) => throw 'Expected DocumentSymbols, got SymbolInformations',
+    );
+
+    expect(symbols, hasLength(2));
+
+    final topLevel = symbols[0];
+    expect(topLevel.name, equals('topLevel'));
+    expect(topLevel.kind, equals(SymbolKind.Variable));
+
+    final myClass = symbols[1];
+    expect(myClass.name, equals('MyClass'));
+    expect(myClass.kind, equals(SymbolKind.Class));
+    expect(myClass.children, hasLength(3));
+
+    final field = myClass.children[0];
+    expect(field.name, equals('myField'));
+    expect(field.kind, equals(SymbolKind.Field));
+
+    final constructor = myClass.children[1];
+    expect(constructor.name, equals('MyClass'));
+    expect(constructor.kind, equals(SymbolKind.Constructor));
+
+    final method = myClass.children[2];
+    expect(method.name, equals('myMethod'));
+    expect(method.kind, equals(SymbolKind.Method));
+  }
+
+  Future<void> test_nonDartFile() async {
     newFile(pubspecFilePath, content: simplePubspecContent);
     await initialize();
 
diff --git a/pkg/analysis_server/test/lsp/file_modification_test.dart b/pkg/analysis_server/test/lsp/file_modification_test.dart
index 6c4dca6..6063bfd 100644
--- a/pkg/analysis_server/test/lsp/file_modification_test.dart
+++ b/pkg/analysis_server/test/lsp/file_modification_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FileModificationTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class FileModificationTest extends AbstractLspAnalysisServerTest {
-  test_change_badPosition() async {
+  Future<void> test_change_badPosition() async {
     final contents = '';
     await initialize();
     await openFile(mainFileUri, contents);
@@ -37,7 +37,7 @@
     expect(error.message, contains('Invalid line'));
   }
 
-  test_change_fullContents() async {
+  Future<void> test_change_fullContents() async {
     final initialContent = 'int a = 1;';
     final updatedContent = 'int a = 2;';
 
@@ -50,7 +50,7 @@
     expect(documentVersion.version, equals(222));
   }
 
-  test_change_incremental() async {
+  Future<void> test_change_incremental() async {
     final initialContent = '0123456789\n0123456789';
     final expectedUpdatedContent = '0123456789\n01234   89';
 
@@ -70,7 +70,7 @@
     expect(documentVersion.version, equals(222));
   }
 
-  test_change_unopenedFile() async {
+  Future<void> test_change_unopenedFile() async {
     // It's not valid for a client to send a request to modify a file that it
     // has not opened, but Visual Studio has done it in the past so we should
     // ensure it generates an obvious error that the user can understand.
@@ -93,7 +93,7 @@
     );
   }
 
-  test_close() async {
+  Future<void> test_close() async {
     final initialContent = 'int a = 1;';
     final updatedContent = 'int a = 2;';
 
@@ -109,7 +109,7 @@
     expect(documentVersion.version, isNull);
   }
 
-  test_open() async {
+  Future<void> test_open() async {
     const testContent = 'CONTENT';
 
     await initialize();
@@ -123,7 +123,7 @@
     expect(documentVersion.version, 2);
   }
 
-  test_open_invalidPath() async {
+  Future<void> test_open_invalidPath() async {
     await initialize();
 
     final notificationParams = await expectErrorNotification<ShowMessageParams>(
diff --git a/pkg/analysis_server/test/lsp/flutter_outline_test.dart b/pkg/analysis_server/test/lsp/flutter_outline_test.dart
index b34a46b..f79de6c 100644
--- a/pkg/analysis_server/test/lsp/flutter_outline_test.dart
+++ b/pkg/analysis_server/test/lsp/flutter_outline_test.dart
@@ -9,7 +9,7 @@
 import '../src/utilities/mock_packages.dart';
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterOutlineTest);
   });
@@ -28,7 +28,7 @@
 ''');
   }
 
-  test_afterChange() async {
+  Future<void> test_afterChange() async {
     final initialContent = '''
 import 'package:flutter/material.dart';
 
@@ -61,7 +61,7 @@
         outlineAfterChange.children[0].children[0].className, equals('Icon'));
   }
 
-  test_initial() async {
+  Future<void> test_initial() async {
     final content = '''
 import 'package:flutter/material.dart';
 
diff --git a/pkg/analysis_server/test/lsp/folding_test.dart b/pkg/analysis_server/test/lsp/folding_test.dart
index 7c5333b..b27ea0b 100644
--- a/pkg/analysis_server/test/lsp/folding_test.dart
+++ b/pkg/analysis_server/test/lsp/folding_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FoldingTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class FoldingTest extends AbstractLspAnalysisServerTest {
-  test_class() async {
+  Future<void> test_class() async {
     final content = '''
     class MyClass2 {[[
       // Class content
@@ -41,7 +41,7 @@
     expect(regions, unorderedEquals(expectedRegions));
   }
 
-  test_comments() async {
+  Future<void> test_comments() async {
     final content = '''
     [[/// This is a comment
     /// that spans many lines]]
@@ -66,15 +66,7 @@
     expect(regions, unorderedEquals(expectedRegions));
   }
 
-  test_nonDartFile() async {
-    await initialize();
-    await openFile(pubspecFileUri, simplePubspecContent);
-
-    final regions = await getFoldingRegions(pubspecFileUri);
-    expect(regions, isEmpty);
-  }
-
-  test_headersImportsComments() async {
+  Future<void> test_headersImportsComments() async {
     // TODO(dantup): Review why the file header and the method comment ranges
     // are different... one spans only the range to collapse, but the other
     // just starts at the logical block.
@@ -109,6 +101,14 @@
     expect(regions, unorderedEquals(expectedRegions));
   }
 
+  Future<void> test_nonDartFile() async {
+    await initialize();
+    await openFile(pubspecFileUri, simplePubspecContent);
+
+    final regions = await getFoldingRegions(pubspecFileUri);
+    expect(regions, isEmpty);
+  }
+
   FoldingRange _toFoldingRange(Range range, FoldingRangeKind kind) {
     return FoldingRange(
       range.start.line,
diff --git a/pkg/analysis_server/test/lsp/format_test.dart b/pkg/analysis_server/test/lsp/format_test.dart
index cb79973..5653d51 100644
--- a/pkg/analysis_server/test/lsp/format_test.dart
+++ b/pkg/analysis_server/test/lsp/format_test.dart
@@ -9,7 +9,7 @@
 import '../tool/lsp_spec/matchers.dart';
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FormatTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class FormatTest extends AbstractLspAnalysisServerTest {
-  test_alreadyFormatted() async {
+  Future<void> test_alreadyFormatted() async {
     const contents = '''main() {
   print('test');
 }
@@ -29,7 +29,7 @@
     expect(formatEdits, isNull);
   }
 
-  test_formatOnType_simple() async {
+  Future<void> test_formatOnType_simple() async {
     const contents = '''
     main  ()
     {
@@ -51,7 +51,7 @@
     expect(formattedContents, equals(expected));
   }
 
-  test_invalidSyntax() async {
+  Future<void> test_invalidSyntax() async {
     const contents = '''main(((( {
   print('test');
 }
@@ -63,7 +63,7 @@
     expect(formatEdits, isNull);
   }
 
-  test_nonDartFile() async {
+  Future<void> test_nonDartFile() async {
     await initialize();
     await openFile(pubspecFileUri, simplePubspecContent);
 
@@ -72,7 +72,7 @@
     expect(formatEdits, isNull);
   }
 
-  test_path_doesNotExist() async {
+  Future<void> test_path_doesNotExist() async {
     await initialize();
 
     await expectLater(
@@ -82,7 +82,7 @@
     );
   }
 
-  test_path_invalidFormat() async {
+  Future<void> test_path_invalidFormat() async {
     await initialize();
 
     await expectLater(
@@ -92,7 +92,7 @@
     );
   }
 
-  test_path_notFileScheme() async {
+  Future<void> test_path_notFileScheme() async {
     await initialize();
 
     await expectLater(
@@ -101,7 +101,7 @@
     );
   }
 
-  test_simple() async {
+  Future<void> test_simple() async {
     const contents = '''
     main  ()
     {
@@ -122,7 +122,7 @@
     expect(formattedContents, equals(expected));
   }
 
-  test_unopenFile() async {
+  Future<void> test_unopenFile() async {
     const contents = '''
     main  ()
     {
diff --git a/pkg/analysis_server/test/lsp/hover_test.dart b/pkg/analysis_server/test/lsp/hover_test.dart
index 859e858..a20279e 100644
--- a/pkg/analysis_server/test/lsp/hover_test.dart
+++ b/pkg/analysis_server/test/lsp/hover_test.dart
@@ -10,7 +10,7 @@
 import '../tool/lsp_spec/matchers.dart';
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(HoverTest);
   });
@@ -18,7 +18,7 @@
 
 @reflectiveTest
 class HoverTest extends AbstractLspAnalysisServerTest {
-  test_dartDoc_macros() async {
+  Future<void> test_dartDoc_macros() async {
     final content = '''
     /// {@template template_name}
     /// This is shared content.
@@ -39,7 +39,7 @@
     expect(_getStringContents(hover), endsWith('This is shared content.'));
   }
 
-  test_hover_bad_position() async {
+  Future<void> test_hover_bad_position() async {
     await initialize();
     await openFile(mainFileUri, '');
     await expectLater(
@@ -48,7 +48,7 @@
     );
   }
 
-  test_markdown_isFormattedForDisplay() async {
+  Future<void> test_markdown_isFormattedForDisplay() async {
     final content = '''
     /// This is a string.
     ///
@@ -94,7 +94,7 @@
     expect(markup.value, equals(expectedHoverContent));
   }
 
-  test_markdown_simple() async {
+  Future<void> test_markdown_simple() async {
     final content = '''
     /// This is a string.
     String [[a^bc]];
@@ -113,22 +113,7 @@
     expect(markup.value, contains('This is a string.'));
   }
 
-  test_range_multiLineConstructorCall() async {
-    final content = '''
-    final a = new [[Str^ing.fromCharCodes]]([
-      1,
-      2,
-    ]);
-    ''';
-
-    await initialize();
-    await openFile(mainFileUri, withoutMarkers(content));
-    final hover = await getHover(mainFileUri, positionFromMarker(content));
-    expect(hover, isNotNull);
-    expect(hover.range, equals(rangeFromMarkers(content)));
-  }
-
-  test_noElement() async {
+  Future<void> test_noElement() async {
     final content = '''
     String abc;
 
@@ -145,14 +130,14 @@
     expect(hover, isNull);
   }
 
-  test_nonDartFile() async {
+  Future<void> test_nonDartFile() async {
     await initialize();
     await openFile(pubspecFileUri, simplePubspecContent);
     final hover = await getHover(pubspecFileUri, startOfDocPos);
     expect(hover, isNull);
   }
 
-  test_plainText_simple() async {
+  Future<void> test_plainText_simple() async {
     final content = '''
     /// This is a string.
     String [[a^bc]];
@@ -173,7 +158,22 @@
     expect(markup.value, contains('This is a string.'));
   }
 
-  test_string_noDocComment() async {
+  Future<void> test_range_multiLineConstructorCall() async {
+    final content = '''
+    final a = new [[Str^ing.fromCharCodes]]([
+      1,
+      2,
+    ]);
+    ''';
+
+    await initialize();
+    await openFile(mainFileUri, withoutMarkers(content));
+    final hover = await getHover(mainFileUri, positionFromMarker(content));
+    expect(hover, isNotNull);
+    expect(hover.range, equals(rangeFromMarkers(content)));
+  }
+
+  Future<void> test_string_noDocComment() async {
     final content = '''
     String [[a^bc]];
     ''';
@@ -195,7 +195,7 @@
     expect(_getStringContents(hover), equals(expectedHoverContent));
   }
 
-  test_string_reflectsLatestEdits() async {
+  Future<void> test_string_reflectsLatestEdits() async {
     final original = '''
     /// Original string.
     String [[a^bc]];
@@ -217,7 +217,7 @@
     expect(contents, contains('Updated'));
   }
 
-  test_string_simple() async {
+  Future<void> test_string_simple() async {
     final content = '''
     /// This is a string.
     String [[a^bc]];
@@ -233,7 +233,7 @@
     expect(contents, contains('This is a string.'));
   }
 
-  test_unopenFile() async {
+  Future<void> test_unopenFile() async {
     final content = '''
     /// This is a string.
     String [[a^bc]];
diff --git a/pkg/analysis_server/test/lsp/implementation_test.dart b/pkg/analysis_server/test/lsp/implementation_test.dart
index bde558e..ff4a3c8 100644
--- a/pkg/analysis_server/test/lsp/implementation_test.dart
+++ b/pkg/analysis_server/test/lsp/implementation_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ImplementationTest);
   });
@@ -16,25 +16,25 @@
 
 @reflectiveTest
 class ImplementationTest extends AbstractLspAnalysisServerTest {
-  test_class_excludesSelf() => _testMarkedContent('''
+  Future<void> test_class_excludesSelf() => _testMarkedContent('''
       abstract class ^[[A]] {}
       class B extends A {}
       class C extends A {}
     ''', shouldMatch: false);
 
-  test_class_excludesSuper() => _testMarkedContent('''
+  Future<void> test_class_excludesSuper() => _testMarkedContent('''
       abstract class [[A]] {}
       class ^B extends A {}
       class C extends A {}
     ''', shouldMatch: false);
 
-  test_class_sub() => _testMarkedContent('''
+  Future<void> test_class_sub() => _testMarkedContent('''
       abstract class ^A {}
       class [[B]] extends A {}
       class [[C]] extends A {}
     ''');
 
-  test_class_subSub() => _testMarkedContent('''
+  Future<void> test_class_subSub() => _testMarkedContent('''
       abstract class ^A {}
       class [[B]] extends A {}
       class [[C]] extends A {}
@@ -43,7 +43,7 @@
       class [[F]] extends E {}
     ''');
 
-  test_emptyResults() async {
+  Future<void> test_emptyResults() async {
     final content = '';
 
     await initialize();
@@ -56,7 +56,8 @@
     expect(res, isEmpty);
   }
 
-  test_method_excludesClassesWithoutImplementations() => _testMarkedContent('''
+  Future<void> test_method_excludesClassesWithoutImplementations() =>
+      _testMarkedContent('''
       abstract class A {
         void ^b();
       }
@@ -66,7 +67,7 @@
       class [[E]] extends B {}
     ''', shouldMatch: false);
 
-  test_method_excludesSelf() => _testMarkedContent('''
+  Future<void> test_method_excludesSelf() => _testMarkedContent('''
       abstract class A {
         void ^[[b]]();
       }
@@ -76,7 +77,7 @@
       }
     ''', shouldMatch: false);
 
-  test_method_excludesSuper() => _testMarkedContent('''
+  Future<void> test_method_excludesSuper() => _testMarkedContent('''
       abstract class A {
         void [[b]]();
       }
@@ -86,7 +87,7 @@
       }
     ''', shouldMatch: false);
 
-  test_method_fromCallSite() => _testMarkedContent('''
+  Future<void> test_method_fromCallSite() => _testMarkedContent('''
       abstract class A {
         void b();
       }
@@ -115,7 +116,7 @@
       }
     ''');
 
-  test_method_sub() => _testMarkedContent('''
+  Future<void> test_method_sub() => _testMarkedContent('''
       abstract class A {
         void ^b();
       }
@@ -129,7 +130,7 @@
       }
     ''');
 
-  test_method_subSub() => _testMarkedContent('''
+  Future<void> test_method_subSub() => _testMarkedContent('''
       abstract class A {
         void ^b();
       }
@@ -149,7 +150,7 @@
       }
     ''');
 
-  test_nonDartFile() async {
+  Future<void> test_nonDartFile() async {
     newFile(pubspecFilePath, content: simplePubspecContent);
     await initialize();
 
diff --git a/pkg/analysis_server/test/lsp/initialization_test.dart b/pkg/analysis_server/test/lsp/initialization_test.dart
index 4068327..dae70ae 100644
--- a/pkg/analysis_server/test/lsp/initialization_test.dart
+++ b/pkg/analysis_server/test/lsp/initialization_test.dart
@@ -11,7 +11,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InitializationTest);
   });
@@ -19,289 +19,16 @@
 
 @reflectiveTest
 class InitializationTest extends AbstractLspAnalysisServerTest {
-  test_initialize() async {
-    final response = await initialize();
-    expect(response, isNotNull);
-    expect(response.error, isNull);
-    expect(response.result, isNotNull);
-    expect(response.result, TypeMatcher<InitializeResult>());
-    InitializeResult result = response.result;
-    expect(result.capabilities, isNotNull);
-    // Check some basic capabilities that are unlikely to change.
-    expect(result.capabilities.textDocumentSync, isNotNull);
-    result.capabilities.textDocumentSync.map(
-      (options) {
-        // We'll always request open/closed notifications and incremental updates.
-        expect(options.openClose, isTrue);
-        expect(options.change, equals(TextDocumentSyncKind.Incremental));
-      },
-      (_) =>
-          throw 'Expected textDocumentSync capabilities to be a $TextDocumentSyncOptions',
-    );
+  TextDocumentRegistrationOptions registrationOptionsFor(
+    List<Registration> registrations,
+    Method method,
+  ) {
+    return registrations
+        .singleWhere((r) => r.method == method.toJson(), orElse: () => null)
+        ?.registerOptions;
   }
 
-  test_initialize_invalidParams() async {
-    final params = {'processId': 'invalid'};
-    final request = RequestMessage(
-      Either2<num, String>.t1(1),
-      Method.initialize,
-      params,
-      jsonRpcVersion,
-    );
-    final response = await sendRequestToServer(request);
-    expect(response.id, equals(request.id));
-    expect(response.error, isNotNull);
-    expect(response.error.code, equals(ErrorCodes.InvalidParams));
-    expect(response.result, isNull);
-  }
-
-  test_initialize_onlyAllowedOnce() async {
-    await initialize();
-    final response = await initialize(throwOnFailure: false);
-    expect(response, isNotNull);
-    expect(response.result, isNull);
-    expect(response.error, isNotNull);
-    expect(
-        response.error.code, equals(ServerErrorCodes.ServerAlreadyInitialized));
-  }
-
-  test_initialize_rootPath() async {
-    await initialize(rootPath: projectFolderPath);
-    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
-  }
-
-  test_initialize_rootUri() async {
-    await initialize(rootUri: projectFolderUri);
-    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
-  }
-
-  test_onlyAnalyzeProjectsWithOpenFiles_withPubpsec() async {
-    final nestedFilePath = join(
-        projectFolderPath, 'nested', 'deeply', 'in', 'folders', 'test.dart');
-    final nestedFileUri = Uri.file(nestedFilePath);
-    await newFile(nestedFilePath);
-    final pubspecPath = join(projectFolderPath, 'pubspec.yaml');
-    await newFile(pubspecPath);
-
-    // The project folder shouldn't be added to start with.
-    await initialize(
-      rootUri: projectFolderUri,
-      initializationOptions: {'onlyAnalyzeProjectsWithOpenFiles': true},
-    );
-    expect(server.contextManager.includedPaths, equals([]));
-
-    // Opening a file nested within the project should add the project folder.
-    await openFile(nestedFileUri, '');
-    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
-
-    // Ensure the file was cached in each driver. This happens as a result of
-    // adding to priority files, but if that's done before the file is in an
-    // analysis root it will not occur.
-    // https://github.com/dart-lang/sdk/issues/37338
-    server.driverMap.values.forEach((driver) {
-      expect(driver.getCachedResult(nestedFilePath), isNotNull);
-    });
-
-    // Closing the file should remove it.
-    await closeFile(nestedFileUri);
-    expect(server.contextManager.includedPaths, equals([]));
-  }
-
-  test_onlyAnalyzeProjectsWithOpenFiles_multipleFiles() async {
-    final file1 = join(projectFolderPath, 'file1.dart');
-    final file1Uri = Uri.file(file1);
-    await newFile(file1);
-    final file2 = join(projectFolderPath, 'file2.dart');
-    final file2Uri = Uri.file(file2);
-    await newFile(file2);
-    final pubspecPath = join(projectFolderPath, 'pubspec.yaml');
-    await newFile(pubspecPath);
-
-    await initialize(
-      rootUri: projectFolderUri,
-      initializationOptions: {'onlyAnalyzeProjectsWithOpenFiles': true},
-    );
-
-    // Opening both files should only add the project folder once.
-    await openFile(file1Uri, '');
-    await openFile(file2Uri, '');
-    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
-
-    // Closing only one of the files should not remove the project folder
-    // since there are still open files.
-    await closeFile(file1Uri);
-    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
-
-    // Closing the last file should remove the project folder.
-    await closeFile(file2Uri);
-    expect(server.contextManager.includedPaths, equals([]));
-  }
-
-  test_onlyAnalyzeProjectsWithOpenFiles_withoutPubpsec() async {
-    final nestedFilePath = join(
-        projectFolderPath, 'nested', 'deeply', 'in', 'folders', 'test.dart');
-    final nestedFileUri = Uri.file(nestedFilePath);
-    await newFile(nestedFilePath);
-
-    // The project folder shouldn't be added to start with.
-    await initialize(
-      rootUri: projectFolderUri,
-      initializationOptions: {'onlyAnalyzeProjectsWithOpenFiles': true},
-    );
-    expect(server.contextManager.includedPaths, equals([]));
-
-    // Opening a file nested within the project will still not add the project
-    // folder because there was no pubspec.
-    final messageFromServer = await expectNotification<ShowMessageParams>(
-      (notification) => notification.method == Method.window_showMessage,
-      () => openFile(nestedFileUri, ''),
-    );
-    expect(server.contextManager.includedPaths, equals([]));
-    expect(messageFromServer.type, MessageType.Warning);
-    expect(messageFromServer.message,
-        contains('using onlyAnalyzeProjectsWithOpenFiles'));
-  }
-
-  test_initialize_workspaceFolders() async {
-    await initialize(workspaceFolders: [projectFolderUri]);
-    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
-  }
-
-  test_uninitialized_dropsNotifications() async {
-    final notification =
-        makeNotification(Method.fromJson('randomNotification'), null);
-    final nextNotification = errorNotificationsFromServer.first;
-    channel.sendNotificationToServer(notification);
-
-    // Wait up to 1sec to ensure no error/log notifications were sent back.
-    var didTimeout = false;
-    final notificationFromServer = await nextNotification.timeout(
-      const Duration(seconds: 1),
-      onTimeout: () {
-        didTimeout = true;
-        return null;
-      },
-    );
-
-    expect(notificationFromServer, isNull);
-    expect(didTimeout, isTrue);
-  }
-
-  test_uninitialized_rejectsRequests() async {
-    final request = makeRequest(Method.fromJson('randomRequest'), null);
-    final response = await channel.sendRequestToServer(request);
-    expect(response.id, equals(request.id));
-    expect(response.result, isNull);
-    expect(response.error, isNotNull);
-    expect(response.error.code, ErrorCodes.ServerNotInitialized);
-  }
-
-  test_dynamicRegistration_notSupportedByClient() async {
-    // If the client doesn't send any dynamicRegistration settings then there
-    // should be no `client/registerCapability` calls.
-
-    // Set a flag if any registerCapability request comes through.
-    bool didGetRegisterCapabilityRequest = false;
-    requestsFromServer
-        .firstWhere((n) => n.method == Method.client_registerCapability)
-        .then((params) {
-      didGetRegisterCapabilityRequest = true;
-    });
-
-    // Initialize with no dynamic registrations advertised.
-    final initResponse = await initialize();
-    await pumpEventQueue();
-
-    InitializeResult initResult = initResponse.result;
-    expect(initResult.capabilities, isNotNull);
-    // When dynamic registration is not supported, we will always statically
-    // request text document open/close and incremental updates.
-    expect(initResult.capabilities.textDocumentSync, isNotNull);
-    initResult.capabilities.textDocumentSync.map(
-      (options) {
-        expect(options.openClose, isTrue);
-        expect(options.change, equals(TextDocumentSyncKind.Incremental));
-      },
-      (_) =>
-          throw 'Expected textDocumentSync capabilities to be a $TextDocumentSyncOptions',
-    );
-    expect(initResult.capabilities.completionProvider, isNotNull);
-    expect(initResult.capabilities.hoverProvider, isNotNull);
-    expect(initResult.capabilities.signatureHelpProvider, isNotNull);
-    expect(initResult.capabilities.referencesProvider, isNotNull);
-    expect(initResult.capabilities.documentHighlightProvider, isNotNull);
-    expect(initResult.capabilities.documentFormattingProvider, isNotNull);
-    expect(initResult.capabilities.documentOnTypeFormattingProvider, isNotNull);
-    expect(initResult.capabilities.definitionProvider, isNotNull);
-    expect(initResult.capabilities.codeActionProvider, isNotNull);
-    expect(initResult.capabilities.renameProvider, isNotNull);
-    expect(initResult.capabilities.foldingRangeProvider, isNotNull);
-
-    expect(didGetRegisterCapabilityRequest, isFalse);
-  }
-
-  test_dynamicRegistration_suppressesStaticRegistration() async {
-    // If the client sends dynamicRegistration settings then there
-    // should not be static registrations for the same capabilities.
-
-    List<Registration> registrations;
-    final initResponse =
-        await handleExpectedRequest<ResponseMessage, RegistrationParams, void>(
-      Method.client_registerCapability,
-      () => initialize(
-          // Support dynamic registration for everything we support.
-          textDocumentCapabilities: withAllSupportedDynamicRegistrations(
-              emptyTextDocumentClientCapabilities)),
-      handler: (registrationParams) =>
-          registrations = registrationParams.registrations,
-    );
-
-    InitializeResult initResult = initResponse.result;
-    expect(initResult.capabilities, isNotNull);
-
-    // Ensure no static registrations. This list should include all server equivilents
-    // of the dynamic registrations listed in `ClientDynamicRegistrations.supported`.
-    expect(initResult.capabilities.textDocumentSync, isNull);
-    expect(initResult.capabilities.completionProvider, isNull);
-    expect(initResult.capabilities.hoverProvider, isNull);
-    expect(initResult.capabilities.signatureHelpProvider, isNull);
-    expect(initResult.capabilities.referencesProvider, isNull);
-    expect(initResult.capabilities.documentHighlightProvider, isNull);
-    expect(initResult.capabilities.documentFormattingProvider, isNull);
-    expect(initResult.capabilities.documentOnTypeFormattingProvider, isNull);
-    expect(initResult.capabilities.definitionProvider, isNull);
-    expect(initResult.capabilities.codeActionProvider, isNull);
-    expect(initResult.capabilities.renameProvider, isNull);
-    expect(initResult.capabilities.foldingRangeProvider, isNull);
-
-    // Ensure all expected dynamic registrations.
-    for (final expectedRegistration in ClientDynamicRegistrations.supported) {
-      final registration =
-          registrationOptionsFor(registrations, expectedRegistration);
-      expect(registration, isNotNull,
-          reason: 'Missing dynamic registration for $expectedRegistration');
-    }
-  }
-
-  test_dynamicRegistration_onlyForClientSupportedMethods() async {
-    // Check that when the server calls client/registerCapability it only includes
-    // the items we advertised dynamic registration support for.
-    List<Registration> registrations;
-    await handleExpectedRequest<void, RegistrationParams, void>(
-      Method.client_registerCapability,
-      () => initialize(
-          textDocumentCapabilities: withHoverDynamicRegistration(
-              emptyTextDocumentClientCapabilities)),
-      handler: (registrationParams) =>
-          registrations = registrationParams.registrations,
-    );
-
-    expect(registrations, hasLength(1));
-    expect(registrations.single.method,
-        equals(Method.textDocument_hover.toJson()));
-  }
-
-  test_dynamicRegistration_containsAppropriateSettings() async {
+  Future<void> test_dynamicRegistration_containsAppropriateSettings() async {
     // Basic check that the server responds with the capabilities we'd expect,
     // for ex including analysis_options.yaml in text synchronization but not
     // for hovers.
@@ -353,12 +80,285 @@
         isTrue);
   }
 
-  TextDocumentRegistrationOptions registrationOptionsFor(
-    List<Registration> registrations,
-    Method method,
-  ) {
-    return registrations
-        .singleWhere((r) => r.method == method.toJson(), orElse: () => null)
-        ?.registerOptions;
+  Future<void> test_dynamicRegistration_notSupportedByClient() async {
+    // If the client doesn't send any dynamicRegistration settings then there
+    // should be no `client/registerCapability` calls.
+
+    // Set a flag if any registerCapability request comes through.
+    bool didGetRegisterCapabilityRequest = false;
+    requestsFromServer
+        .firstWhere((n) => n.method == Method.client_registerCapability)
+        .then((params) {
+      didGetRegisterCapabilityRequest = true;
+    });
+
+    // Initialize with no dynamic registrations advertised.
+    final initResponse = await initialize();
+    await pumpEventQueue();
+
+    InitializeResult initResult = initResponse.result;
+    expect(initResult.capabilities, isNotNull);
+    // When dynamic registration is not supported, we will always statically
+    // request text document open/close and incremental updates.
+    expect(initResult.capabilities.textDocumentSync, isNotNull);
+    initResult.capabilities.textDocumentSync.map(
+      (options) {
+        expect(options.openClose, isTrue);
+        expect(options.change, equals(TextDocumentSyncKind.Incremental));
+      },
+      (_) =>
+          throw 'Expected textDocumentSync capabilities to be a $TextDocumentSyncOptions',
+    );
+    expect(initResult.capabilities.completionProvider, isNotNull);
+    expect(initResult.capabilities.hoverProvider, isNotNull);
+    expect(initResult.capabilities.signatureHelpProvider, isNotNull);
+    expect(initResult.capabilities.referencesProvider, isNotNull);
+    expect(initResult.capabilities.documentHighlightProvider, isNotNull);
+    expect(initResult.capabilities.documentFormattingProvider, isNotNull);
+    expect(initResult.capabilities.documentOnTypeFormattingProvider, isNotNull);
+    expect(initResult.capabilities.definitionProvider, isNotNull);
+    expect(initResult.capabilities.codeActionProvider, isNotNull);
+    expect(initResult.capabilities.renameProvider, isNotNull);
+    expect(initResult.capabilities.foldingRangeProvider, isNotNull);
+
+    expect(didGetRegisterCapabilityRequest, isFalse);
+  }
+
+  Future<void> test_dynamicRegistration_onlyForClientSupportedMethods() async {
+    // Check that when the server calls client/registerCapability it only includes
+    // the items we advertised dynamic registration support for.
+    List<Registration> registrations;
+    await handleExpectedRequest<void, RegistrationParams, void>(
+      Method.client_registerCapability,
+      () => initialize(
+          textDocumentCapabilities: withHoverDynamicRegistration(
+              emptyTextDocumentClientCapabilities)),
+      handler: (registrationParams) =>
+          registrations = registrationParams.registrations,
+    );
+
+    expect(registrations, hasLength(1));
+    expect(registrations.single.method,
+        equals(Method.textDocument_hover.toJson()));
+  }
+
+  Future<void> test_dynamicRegistration_suppressesStaticRegistration() async {
+    // If the client sends dynamicRegistration settings then there
+    // should not be static registrations for the same capabilities.
+
+    List<Registration> registrations;
+    final initResponse =
+        await handleExpectedRequest<ResponseMessage, RegistrationParams, void>(
+      Method.client_registerCapability,
+      () => initialize(
+          // Support dynamic registration for everything we support.
+          textDocumentCapabilities: withAllSupportedDynamicRegistrations(
+              emptyTextDocumentClientCapabilities)),
+      handler: (registrationParams) =>
+          registrations = registrationParams.registrations,
+    );
+
+    InitializeResult initResult = initResponse.result;
+    expect(initResult.capabilities, isNotNull);
+
+    // Ensure no static registrations. This list should include all server equivilents
+    // of the dynamic registrations listed in `ClientDynamicRegistrations.supported`.
+    expect(initResult.capabilities.textDocumentSync, isNull);
+    expect(initResult.capabilities.completionProvider, isNull);
+    expect(initResult.capabilities.hoverProvider, isNull);
+    expect(initResult.capabilities.signatureHelpProvider, isNull);
+    expect(initResult.capabilities.referencesProvider, isNull);
+    expect(initResult.capabilities.documentHighlightProvider, isNull);
+    expect(initResult.capabilities.documentFormattingProvider, isNull);
+    expect(initResult.capabilities.documentOnTypeFormattingProvider, isNull);
+    expect(initResult.capabilities.definitionProvider, isNull);
+    expect(initResult.capabilities.codeActionProvider, isNull);
+    expect(initResult.capabilities.renameProvider, isNull);
+    expect(initResult.capabilities.foldingRangeProvider, isNull);
+
+    // Ensure all expected dynamic registrations.
+    for (final expectedRegistration in ClientDynamicRegistrations.supported) {
+      final registration =
+          registrationOptionsFor(registrations, expectedRegistration);
+      expect(registration, isNotNull,
+          reason: 'Missing dynamic registration for $expectedRegistration');
+    }
+  }
+
+  Future<void> test_initialize() async {
+    final response = await initialize();
+    expect(response, isNotNull);
+    expect(response.error, isNull);
+    expect(response.result, isNotNull);
+    expect(response.result, TypeMatcher<InitializeResult>());
+    InitializeResult result = response.result;
+    expect(result.capabilities, isNotNull);
+    // Check some basic capabilities that are unlikely to change.
+    expect(result.capabilities.textDocumentSync, isNotNull);
+    result.capabilities.textDocumentSync.map(
+      (options) {
+        // We'll always request open/closed notifications and incremental updates.
+        expect(options.openClose, isTrue);
+        expect(options.change, equals(TextDocumentSyncKind.Incremental));
+      },
+      (_) =>
+          throw 'Expected textDocumentSync capabilities to be a $TextDocumentSyncOptions',
+    );
+  }
+
+  Future<void> test_initialize_invalidParams() async {
+    final params = {'processId': 'invalid'};
+    final request = RequestMessage(
+      Either2<num, String>.t1(1),
+      Method.initialize,
+      params,
+      jsonRpcVersion,
+    );
+    final response = await sendRequestToServer(request);
+    expect(response.id, equals(request.id));
+    expect(response.error, isNotNull);
+    expect(response.error.code, equals(ErrorCodes.InvalidParams));
+    expect(response.result, isNull);
+  }
+
+  Future<void> test_initialize_onlyAllowedOnce() async {
+    await initialize();
+    final response = await initialize(throwOnFailure: false);
+    expect(response, isNotNull);
+    expect(response.result, isNull);
+    expect(response.error, isNotNull);
+    expect(
+        response.error.code, equals(ServerErrorCodes.ServerAlreadyInitialized));
+  }
+
+  Future<void> test_initialize_rootPath() async {
+    await initialize(rootPath: projectFolderPath);
+    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
+  }
+
+  Future<void> test_initialize_rootUri() async {
+    await initialize(rootUri: projectFolderUri);
+    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
+  }
+
+  Future<void> test_initialize_workspaceFolders() async {
+    await initialize(workspaceFolders: [projectFolderUri]);
+    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
+  }
+
+  Future<void> test_onlyAnalyzeProjectsWithOpenFiles_multipleFiles() async {
+    final file1 = join(projectFolderPath, 'file1.dart');
+    final file1Uri = Uri.file(file1);
+    await newFile(file1);
+    final file2 = join(projectFolderPath, 'file2.dart');
+    final file2Uri = Uri.file(file2);
+    await newFile(file2);
+    final pubspecPath = join(projectFolderPath, 'pubspec.yaml');
+    await newFile(pubspecPath);
+
+    await initialize(
+      rootUri: projectFolderUri,
+      initializationOptions: {'onlyAnalyzeProjectsWithOpenFiles': true},
+    );
+
+    // Opening both files should only add the project folder once.
+    await openFile(file1Uri, '');
+    await openFile(file2Uri, '');
+    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
+
+    // Closing only one of the files should not remove the project folder
+    // since there are still open files.
+    await closeFile(file1Uri);
+    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
+
+    // Closing the last file should remove the project folder.
+    await closeFile(file2Uri);
+    expect(server.contextManager.includedPaths, equals([]));
+  }
+
+  Future<void> test_onlyAnalyzeProjectsWithOpenFiles_withoutPubpsec() async {
+    final nestedFilePath = join(
+        projectFolderPath, 'nested', 'deeply', 'in', 'folders', 'test.dart');
+    final nestedFileUri = Uri.file(nestedFilePath);
+    await newFile(nestedFilePath);
+
+    // The project folder shouldn't be added to start with.
+    await initialize(
+      rootUri: projectFolderUri,
+      initializationOptions: {'onlyAnalyzeProjectsWithOpenFiles': true},
+    );
+    expect(server.contextManager.includedPaths, equals([]));
+
+    // Opening a file nested within the project will still not add the project
+    // folder because there was no pubspec.
+    final messageFromServer = await expectNotification<ShowMessageParams>(
+      (notification) => notification.method == Method.window_showMessage,
+      () => openFile(nestedFileUri, ''),
+    );
+    expect(server.contextManager.includedPaths, equals([]));
+    expect(messageFromServer.type, MessageType.Warning);
+    expect(messageFromServer.message,
+        contains('using onlyAnalyzeProjectsWithOpenFiles'));
+  }
+
+  Future<void> test_onlyAnalyzeProjectsWithOpenFiles_withPubpsec() async {
+    final nestedFilePath = join(
+        projectFolderPath, 'nested', 'deeply', 'in', 'folders', 'test.dart');
+    final nestedFileUri = Uri.file(nestedFilePath);
+    await newFile(nestedFilePath);
+    final pubspecPath = join(projectFolderPath, 'pubspec.yaml');
+    await newFile(pubspecPath);
+
+    // The project folder shouldn't be added to start with.
+    await initialize(
+      rootUri: projectFolderUri,
+      initializationOptions: {'onlyAnalyzeProjectsWithOpenFiles': true},
+    );
+    expect(server.contextManager.includedPaths, equals([]));
+
+    // Opening a file nested within the project should add the project folder.
+    await openFile(nestedFileUri, '');
+    expect(server.contextManager.includedPaths, equals([projectFolderPath]));
+
+    // Ensure the file was cached in each driver. This happens as a result of
+    // adding to priority files, but if that's done before the file is in an
+    // analysis root it will not occur.
+    // https://github.com/dart-lang/sdk/issues/37338
+    server.driverMap.values.forEach((driver) {
+      expect(driver.getCachedResult(nestedFilePath), isNotNull);
+    });
+
+    // Closing the file should remove it.
+    await closeFile(nestedFileUri);
+    expect(server.contextManager.includedPaths, equals([]));
+  }
+
+  Future<void> test_uninitialized_dropsNotifications() async {
+    final notification =
+        makeNotification(Method.fromJson('randomNotification'), null);
+    final nextNotification = errorNotificationsFromServer.first;
+    channel.sendNotificationToServer(notification);
+
+    // Wait up to 1sec to ensure no error/log notifications were sent back.
+    var didTimeout = false;
+    final notificationFromServer = await nextNotification.timeout(
+      const Duration(seconds: 1),
+      onTimeout: () {
+        didTimeout = true;
+        return null;
+      },
+    );
+
+    expect(notificationFromServer, isNull);
+    expect(didTimeout, isTrue);
+  }
+
+  Future<void> test_uninitialized_rejectsRequests() async {
+    final request = makeRequest(Method.fromJson('randomRequest'), null);
+    final response = await channel.sendRequestToServer(request);
+    expect(response.id, equals(request.id));
+    expect(response.result, isNull);
+    expect(response.error, isNotNull);
+    expect(response.error.code, ErrorCodes.ServerNotInitialized);
   }
 }
diff --git a/pkg/analysis_server/test/lsp/mapping_test.dart b/pkg/analysis_server/test/lsp/mapping_test.dart
index 3a53179..2ae7ac1 100644
--- a/pkg/analysis_server/test/lsp/mapping_test.dart
+++ b/pkg/analysis_server/test/lsp/mapping_test.dart
@@ -12,7 +12,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MappingTest);
   });
@@ -20,7 +20,7 @@
 
 @reflectiveTest
 class MappingTest extends AbstractLspAnalysisServerTest {
-  test_completionItemKind_firstNotSupported() async {
+  Future<void> test_completionItemKind_firstNotSupported() async {
     // TYPE_PARAMETER maps to TypeParameter first, but since originally LSP
     // did not support it, it'll map to Variable if the client doesn't support
     // that.
@@ -35,7 +35,7 @@
     expect(result, equals(lsp.CompletionItemKind.TypeParameter));
   }
 
-  test_completionItemKind_firstSupported() async {
+  Future<void> test_completionItemKind_firstSupported() async {
     // TYPE_PARAMETER maps to TypeParameter first, but since originally LSP
     // did not support it, it'll map to Variable if the client doesn't support
     // that.
@@ -47,7 +47,7 @@
     expect(result, equals(lsp.CompletionItemKind.Variable));
   }
 
-  test_completionItemKind_knownMapping() async {
+  Future<void> test_completionItemKind_knownMapping() async {
     final supportedKinds = HashSet.of([lsp.CompletionItemKind.Class]);
     final result = lsp.elementKindToCompletionItemKind(
       supportedKinds,
@@ -56,7 +56,7 @@
     expect(result, equals(lsp.CompletionItemKind.Class));
   }
 
-  test_completionItemKind_notMapped() async {
+  Future<void> test_completionItemKind_notMapped() async {
     var supportedKinds = HashSet<lsp.CompletionItemKind>();
     var result = lsp.elementKindToCompletionItemKind(
       supportedKinds,
@@ -65,7 +65,7 @@
     expect(result, isNull);
   }
 
-  test_completionItemKind_notSupported() async {
+  Future<void> test_completionItemKind_notSupported() async {
     var supportedKinds = HashSet<lsp.CompletionItemKind>();
     var result = lsp.elementKindToCompletionItemKind(
       supportedKinds,
@@ -74,17 +74,17 @@
     expect(result, isNull);
   }
 
-  test_selectionsInSnippets_empty() async {
+  Future<void> test_selectionsInSnippets_empty() async {
     var result = lsp.buildSnippetStringWithSelection('teststring', 4, 0);
     expect(result, equals(r'test${1:}string'));
   }
 
-  test_selectionsInSnippets_escaping() async {
+  Future<void> test_selectionsInSnippets_escaping() async {
     var result = lsp.buildSnippetStringWithSelection(r'te$tstri}ng', 4, 3);
     expect(result, equals(r'te\$t${1:str}i\}ng'));
   }
 
-  test_selectionsInSnippets_selection() async {
+  Future<void> test_selectionsInSnippets_selection() async {
     var result = lsp.buildSnippetStringWithSelection('teststring', 4, 3);
     expect(result, equals(r'test${1:str}ing'));
   }
diff --git a/pkg/analysis_server/test/lsp/outline_test.dart b/pkg/analysis_server/test/lsp/outline_test.dart
index 5b554eb..0d5bf89 100644
--- a/pkg/analysis_server/test/lsp/outline_test.dart
+++ b/pkg/analysis_server/test/lsp/outline_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(OutlineTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class OutlineTest extends AbstractLspAnalysisServerTest {
-  test_afterChange() async {
+  Future<void> test_afterChange() async {
     final initialContent = 'class A {}';
     final updatedContent = 'class B {}';
     await initialize(initializationOptions: {'outline': true});
@@ -38,7 +38,7 @@
     expect(outlineAfterChange.children[0].element.name, equals('B'));
   }
 
-  test_initial() async {
+  Future<void> test_initial() async {
     final content = '''
 /// a
 class A {
diff --git a/pkg/analysis_server/test/lsp/priority_files_test.dart b/pkg/analysis_server/test/lsp/priority_files_test.dart
index 7a7b330..028f903 100644
--- a/pkg/analysis_server/test/lsp/priority_files_test.dart
+++ b/pkg/analysis_server/test/lsp/priority_files_test.dart
@@ -7,7 +7,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(PriorityFilesTest);
   });
@@ -15,7 +15,7 @@
 
 @reflectiveTest
 class PriorityFilesTest extends AbstractLspAnalysisServerTest {
-  test_close() async {
+  Future<void> test_close() async {
     await initialize();
     await openFile(mainFileUri, '');
     await closeFile(mainFileUri);
@@ -26,7 +26,7 @@
     });
   }
 
-  test_open() async {
+  Future<void> test_open() async {
     await initialize();
     await openFile(mainFileUri, '');
 
diff --git a/pkg/analysis_server/test/lsp/references_test.dart b/pkg/analysis_server/test/lsp/references_test.dart
index 5520ffc..738a752 100644
--- a/pkg/analysis_server/test/lsp/references_test.dart
+++ b/pkg/analysis_server/test/lsp/references_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReferencesTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class ReferencesTest extends AbstractLspAnalysisServerTest {
-  test_acrossFiles_includeDeclaration() async {
+  Future<void> test_acrossFiles_includeDeclaration() async {
     final mainContents = '''
     import 'referenced.dart';
 
@@ -62,7 +62,7 @@
             rangeFromMarkers(referencedContents))));
   }
 
-  test_acrossFiles_withoutDeclaration() async {
+  Future<void> test_acrossFiles_withoutDeclaration() async {
     final mainContents = '''
     import 'referenced.dart';
 
@@ -99,7 +99,7 @@
     expect(loc.uri, equals(mainFileUri.toString()));
   }
 
-  test_nonDartFile() async {
+  Future<void> test_nonDartFile() async {
     newFile(pubspecFilePath, content: simplePubspecContent);
     await initialize();
 
@@ -107,7 +107,7 @@
     expect(res, isEmpty);
   }
 
-  test_singleFile_withoutDeclaration() async {
+  Future<void> test_singleFile_withoutDeclaration() async {
     final contents = '''
     f^oo() {
       [[foo]]();
@@ -127,7 +127,7 @@
     );
   }
 
-  test_unopenFile() async {
+  Future<void> test_unopenFile() async {
     final contents = '''
     f^oo() {
       [[foo]]();
diff --git a/pkg/analysis_server/test/lsp/rename_test.dart b/pkg/analysis_server/test/lsp/rename_test.dart
index e55fbe3..54a4f45 100644
--- a/pkg/analysis_server/test/lsp/rename_test.dart
+++ b/pkg/analysis_server/test/lsp/rename_test.dart
@@ -9,7 +9,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RenameTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class RenameTest extends AbstractLspAnalysisServerTest {
-  test_prepare_class() {
+  Future<void> test_prepare_class() {
     const content = '''
     class MyClass {}
     final a = new [[My^Class]]();
@@ -26,7 +26,7 @@
     return _test_prepare(content, 'MyClass');
   }
 
-  test_prepare_classNewKeyword() async {
+  Future<void> test_prepare_classNewKeyword() async {
     const content = '''
     class MyClass {}
     final a = n^ew [[MyClass]]();
@@ -35,7 +35,7 @@
     return _test_prepare(content, 'MyClass');
   }
 
-  test_prepare_importPrefix() async {
+  Future<void> test_prepare_importPrefix() async {
     const content = '''
     import 'dart:async' as [[myPr^efix]];
     ''';
@@ -43,7 +43,7 @@
     return _test_prepare(content, 'myPrefix');
   }
 
-  test_prepare_importWithoutPrefix() async {
+  Future<void> test_prepare_importWithoutPrefix() async {
     const content = '''
     imp[[^]]ort 'dart:async';
     ''';
@@ -51,7 +51,7 @@
     return _test_prepare(content, '');
   }
 
-  test_prepare_importWithPrefix() async {
+  Future<void> test_prepare_importWithPrefix() async {
     const content = '''
     imp^ort 'dart:async' as [[myPrefix]];
     ''';
@@ -59,7 +59,7 @@
     return _test_prepare(content, 'myPrefix');
   }
 
-  test_prepare_invalidRenameLocation() async {
+  Future<void> test_prepare_invalidRenameLocation() async {
     const content = '''
     main() {
       // comm^ent
@@ -69,7 +69,7 @@
     return _test_prepare(content, null);
   }
 
-  test_prepare_sdkClass() async {
+  Future<void> test_prepare_sdkClass() async {
     const content = '''
     final a = new [[Ob^ject]]();
     ''';
@@ -93,7 +93,7 @@
     expect(response.error.message, contains('is defined in the SDK'));
   }
 
-  test_prepare_variable() async {
+  Future<void> test_prepare_variable() async {
     const content = '''
     main() {
       var variable = 0;
@@ -104,7 +104,7 @@
     return _test_prepare(content, 'variable');
   }
 
-  test_rename_class() {
+  Future<void> test_rename_class() {
     const content = '''
     class MyClass {}
     final a = new [[My^Class]]();
@@ -117,24 +117,7 @@
         content, 'MyNewClass', expectedContent);
   }
 
-  test_rename_withoutVersionedIdentifier() {
-    // Without sending a document version, the rename should still work because
-    // the server should use the version it had at the start of the rename
-    // operation.
-    const content = '''
-    class MyClass {}
-    final a = new [[My^Class]]();
-    ''';
-    const expectedContent = '''
-    class MyNewClass {}
-    final a = new MyNewClass();
-    ''';
-    return _test_rename_withDocumentChanges(
-        content, 'MyNewClass', expectedContent,
-        sendRenameVersion: false);
-  }
-
-  test_rename_classNewKeyword() async {
+  Future<void> test_rename_classNewKeyword() async {
     const content = '''
     class MyClass {}
     final a = n^ew MyClass();
@@ -147,7 +130,7 @@
         content, 'MyNewClass', expectedContent);
   }
 
-  test_rename_importPrefix() {
+  Future<void> test_rename_importPrefix() {
     const content = '''
     import 'dart:async' as myPr^efix;
     ''';
@@ -158,7 +141,7 @@
         content, 'myNewPrefix', expectedContent);
   }
 
-  test_rename_importWithoutPrefix() {
+  Future<void> test_rename_importWithoutPrefix() {
     const content = '''
     imp^ort 'dart:async';
     ''';
@@ -169,7 +152,7 @@
         content, 'myAddedPrefix', expectedContent);
   }
 
-  test_rename_importWithPrefix() {
+  Future<void> test_rename_importWithPrefix() {
     const content = '''
     imp^ort 'dart:async' as myPrefix;
     ''';
@@ -180,7 +163,7 @@
         content, 'myNewPrefix', expectedContent);
   }
 
-  test_rename_invalidRenameLocation() {
+  Future<void> test_rename_invalidRenameLocation() {
     const content = '''
     main() {
       // comm^ent
@@ -189,192 +172,7 @@
     return _test_rename_withDocumentChanges(content, 'MyNewClass', null);
   }
 
-  test_rename_rejectedForBadName() async {
-    const content = '''
-    class MyClass {}
-    final a = n^ew MyClass();
-    ''';
-    final error = await _test_rename_failure(content, 'not a valid class name');
-    expect(error.code, equals(ServerErrorCodes.RenameNotValid));
-    expect(error.message, contains('name must not contain'));
-  }
-
-  test_rename_rejectedForDuplicateName() async {
-    const content = '''
-    class MyOtherClass {}
-    class MyClass {}
-    final a = n^ew MyClass();
-    ''';
-    final error = await _test_rename_failure(content, 'MyOtherClass');
-    expect(error.code, equals(ServerErrorCodes.RenameNotValid));
-    expect(error.message, contains('already declares class with name'));
-  }
-
-  test_rename_rejectedForStaleDocument() async {
-    const content = '''
-    class MyClass {}
-    final a = n^ew MyClass();
-    ''';
-    final error =
-        await _test_rename_failure(content, 'MyNewClass', openFileVersion: 111);
-    expect(error.code, equals(ErrorCodes.ContentModified));
-    expect(error.message, contains('Document was modified'));
-  }
-
-  test_rename_sdkClass() async {
-    const content = '''
-    final a = new [[Ob^ject]]();
-    ''';
-
-    await newFile(mainFilePath, content: withoutMarkers(content));
-    await initialize();
-
-    final request = makeRequest(
-      Method.textDocument_rename,
-      RenameParams(
-        TextDocumentIdentifier(mainFileUri.toString()),
-        positionFromMarker(content),
-        'Object2',
-      ),
-    );
-    final response = await channel.sendRequestToServer(request);
-
-    expect(response.id, equals(request.id));
-    expect(response.result, isNull);
-    expect(response.error, isNotNull);
-    expect(response.error.code, ServerErrorCodes.RenameNotValid);
-    expect(response.error.message, contains('is defined in the SDK'));
-  }
-
-  test_rename_usingLegacyChangeInterface() async {
-    // This test initializes without support for DocumentChanges (versioning)
-    // whereas the other tests all use DocumentChanges support (preferred).
-    const content = '''
-    class MyClass {}
-    final a = new My^Class();
-    ''';
-    const expectedContent = '''
-    class MyNewClass {}
-    final a = new MyNewClass();
-    ''';
-
-    await initialize();
-    await openFile(mainFileUri, withoutMarkers(content), version: 222);
-
-    final result = await rename(
-      mainFileUri,
-      222,
-      positionFromMarker(content),
-      'MyNewClass',
-    );
-
-    // Ensure applying the changes will give us the expected content.
-    final contents = {
-      mainFilePath: withoutMarkers(content),
-    };
-    applyChanges(contents, result.changes);
-    expect(contents[mainFilePath], equals(expectedContent));
-  }
-
-  test_rename_variable() {
-    const content = '''
-    main() {
-      var variable = 0;
-      print([[vari^able]]);
-    }
-    ''';
-    const expectedContent = '''
-    main() {
-      var foo = 0;
-      print(foo);
-    }
-    ''';
-    return _test_rename_withDocumentChanges(content, 'foo', expectedContent);
-  }
-
-  _test_prepare(String content, String expectedPlaceholder) async {
-    await initialize();
-    await openFile(mainFileUri, withoutMarkers(content));
-
-    final result =
-        await prepareRename(mainFileUri, positionFromMarker(content));
-
-    if (expectedPlaceholder == null) {
-      expect(result, isNull);
-    } else {
-      expect(result.range, equals(rangeFromMarkers(content)));
-      expect(result.placeholder, equals(expectedPlaceholder));
-    }
-  }
-
-  Future<ResponseError> _test_rename_failure(
-    String content,
-    String newName, {
-    int openFileVersion = 222,
-    int renameRequestFileVersion = 222,
-  }) async {
-    await initialize(
-      workspaceCapabilities:
-          withDocumentChangesSupport(emptyWorkspaceClientCapabilities),
-    );
-    await openFile(mainFileUri, withoutMarkers(content),
-        version: openFileVersion);
-
-    final result = await renameRaw(
-      mainFileUri,
-      renameRequestFileVersion,
-      positionFromMarker(content),
-      newName,
-    );
-
-    expect(result.result, isNull);
-    expect(result.error, isNotNull);
-    return result.error;
-  }
-
-  _test_rename_withDocumentChanges(
-    String content,
-    String newName,
-    String expectedContent, {
-    sendDocumentVersion = true,
-    sendRenameVersion = true,
-  }) async {
-    // The specific number doesn't matter here, it's just a placeholder to confirm
-    // the values match.
-    final documentVersion = 222;
-    await initialize(
-      workspaceCapabilities:
-          withDocumentChangesSupport(emptyWorkspaceClientCapabilities),
-    );
-    await openFile(mainFileUri, withoutMarkers(content),
-        version: sendDocumentVersion ? documentVersion : null);
-
-    final result = await rename(
-      mainFileUri,
-      sendRenameVersion ? documentVersion : null,
-      positionFromMarker(content),
-      newName,
-    );
-    if (expectedContent == null) {
-      expect(result, isNull);
-    } else {
-      // Ensure applying the changes will give us the expected content.
-      final contents = {
-        mainFilePath: withoutMarkers(content),
-      };
-      final documentVersions = {
-        mainFilePath: documentVersion,
-      };
-      applyDocumentChanges(
-        contents,
-        result.documentChanges,
-        expectedVersions: documentVersions,
-      );
-      expect(contents[mainFilePath], equals(expectedContent));
-    }
-  }
-
-  test_rename_multipleFiles() async {
+  Future<void> test_rename_multipleFiles() async {
     final referencedFilePath =
         join(projectFolderPath, 'lib', 'referenced.dart');
     final referencedFileUri = Uri.file(referencedFilePath);
@@ -428,4 +226,206 @@
     expect(contents[mainFilePath], equals(expectedMainContent));
     expect(contents[referencedFilePath], equals(expectedReferencedContent));
   }
+
+  Future<void> test_rename_rejectedForBadName() async {
+    const content = '''
+    class MyClass {}
+    final a = n^ew MyClass();
+    ''';
+    final error = await _test_rename_failure(content, 'not a valid class name');
+    expect(error.code, equals(ServerErrorCodes.RenameNotValid));
+    expect(error.message, contains('name must not contain'));
+  }
+
+  Future<void> test_rename_rejectedForDuplicateName() async {
+    const content = '''
+    class MyOtherClass {}
+    class MyClass {}
+    final a = n^ew MyClass();
+    ''';
+    final error = await _test_rename_failure(content, 'MyOtherClass');
+    expect(error.code, equals(ServerErrorCodes.RenameNotValid));
+    expect(error.message, contains('already declares class with name'));
+  }
+
+  Future<void> test_rename_rejectedForStaleDocument() async {
+    const content = '''
+    class MyClass {}
+    final a = n^ew MyClass();
+    ''';
+    final error =
+        await _test_rename_failure(content, 'MyNewClass', openFileVersion: 111);
+    expect(error.code, equals(ErrorCodes.ContentModified));
+    expect(error.message, contains('Document was modified'));
+  }
+
+  Future<void> test_rename_sdkClass() async {
+    const content = '''
+    final a = new [[Ob^ject]]();
+    ''';
+
+    await newFile(mainFilePath, content: withoutMarkers(content));
+    await initialize();
+
+    final request = makeRequest(
+      Method.textDocument_rename,
+      RenameParams(
+        TextDocumentIdentifier(mainFileUri.toString()),
+        positionFromMarker(content),
+        'Object2',
+      ),
+    );
+    final response = await channel.sendRequestToServer(request);
+
+    expect(response.id, equals(request.id));
+    expect(response.result, isNull);
+    expect(response.error, isNotNull);
+    expect(response.error.code, ServerErrorCodes.RenameNotValid);
+    expect(response.error.message, contains('is defined in the SDK'));
+  }
+
+  Future<void> test_rename_usingLegacyChangeInterface() async {
+    // This test initializes without support for DocumentChanges (versioning)
+    // whereas the other tests all use DocumentChanges support (preferred).
+    const content = '''
+    class MyClass {}
+    final a = new My^Class();
+    ''';
+    const expectedContent = '''
+    class MyNewClass {}
+    final a = new MyNewClass();
+    ''';
+
+    await initialize();
+    await openFile(mainFileUri, withoutMarkers(content), version: 222);
+
+    final result = await rename(
+      mainFileUri,
+      222,
+      positionFromMarker(content),
+      'MyNewClass',
+    );
+
+    // Ensure applying the changes will give us the expected content.
+    final contents = {
+      mainFilePath: withoutMarkers(content),
+    };
+    applyChanges(contents, result.changes);
+    expect(contents[mainFilePath], equals(expectedContent));
+  }
+
+  Future<void> test_rename_variable() {
+    const content = '''
+    main() {
+      var variable = 0;
+      print([[vari^able]]);
+    }
+    ''';
+    const expectedContent = '''
+    main() {
+      var foo = 0;
+      print(foo);
+    }
+    ''';
+    return _test_rename_withDocumentChanges(content, 'foo', expectedContent);
+  }
+
+  Future<void> test_rename_withoutVersionedIdentifier() {
+    // Without sending a document version, the rename should still work because
+    // the server should use the version it had at the start of the rename
+    // operation.
+    const content = '''
+    class MyClass {}
+    final a = new [[My^Class]]();
+    ''';
+    const expectedContent = '''
+    class MyNewClass {}
+    final a = new MyNewClass();
+    ''';
+    return _test_rename_withDocumentChanges(
+        content, 'MyNewClass', expectedContent,
+        sendRenameVersion: false);
+  }
+
+  Future<void> _test_prepare(String content, String expectedPlaceholder) async {
+    await initialize();
+    await openFile(mainFileUri, withoutMarkers(content));
+
+    final result =
+        await prepareRename(mainFileUri, positionFromMarker(content));
+
+    if (expectedPlaceholder == null) {
+      expect(result, isNull);
+    } else {
+      expect(result.range, equals(rangeFromMarkers(content)));
+      expect(result.placeholder, equals(expectedPlaceholder));
+    }
+  }
+
+  Future<ResponseError> _test_rename_failure(
+    String content,
+    String newName, {
+    int openFileVersion = 222,
+    int renameRequestFileVersion = 222,
+  }) async {
+    await initialize(
+      workspaceCapabilities:
+          withDocumentChangesSupport(emptyWorkspaceClientCapabilities),
+    );
+    await openFile(mainFileUri, withoutMarkers(content),
+        version: openFileVersion);
+
+    final result = await renameRaw(
+      mainFileUri,
+      renameRequestFileVersion,
+      positionFromMarker(content),
+      newName,
+    );
+
+    expect(result.result, isNull);
+    expect(result.error, isNotNull);
+    return result.error;
+  }
+
+  Future<void> _test_rename_withDocumentChanges(
+    String content,
+    String newName,
+    String expectedContent, {
+    sendDocumentVersion = true,
+    sendRenameVersion = true,
+  }) async {
+    // The specific number doesn't matter here, it's just a placeholder to confirm
+    // the values match.
+    final documentVersion = 222;
+    await initialize(
+      workspaceCapabilities:
+          withDocumentChangesSupport(emptyWorkspaceClientCapabilities),
+    );
+    await openFile(mainFileUri, withoutMarkers(content),
+        version: sendDocumentVersion ? documentVersion : null);
+
+    final result = await rename(
+      mainFileUri,
+      sendRenameVersion ? documentVersion : null,
+      positionFromMarker(content),
+      newName,
+    );
+    if (expectedContent == null) {
+      expect(result, isNull);
+    } else {
+      // Ensure applying the changes will give us the expected content.
+      final contents = {
+        mainFilePath: withoutMarkers(content),
+      };
+      final documentVersions = {
+        mainFilePath: documentVersion,
+      };
+      applyDocumentChanges(
+        contents,
+        result.documentChanges,
+        expectedVersions: documentVersions,
+      );
+      expect(contents[mainFilePath], equals(expectedContent));
+    }
+  }
 }
diff --git a/pkg/analysis_server/test/lsp/server_test.dart b/pkg/analysis_server/test/lsp/server_test.dart
index fb582d0..adca252 100644
--- a/pkg/analysis_server/test/lsp/server_test.dart
+++ b/pkg/analysis_server/test/lsp/server_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ServerTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class ServerTest extends AbstractLspAnalysisServerTest {
-  test_inconsistentStateError() async {
+  Future<void> test_inconsistentStateError() async {
     await initialize();
     await openFile(mainFileUri, '');
     // Attempt to make an illegal modification to the file. This indicates the
@@ -35,18 +35,18 @@
     await server.exited.timeout(const Duration(seconds: 10));
   }
 
-  test_shutdown_initialized() async {
+  Future<void> test_shutdown_initialized() async {
     await initialize();
     final response = await sendShutdown();
     expect(response, isNull);
   }
 
-  test_shutdown_uninitialized() async {
+  Future<void> test_shutdown_uninitialized() async {
     final response = await sendShutdown();
     expect(response, isNull);
   }
 
-  test_unknownNotifications_logError() async {
+  Future<void> test_unknownNotifications_logError() async {
     await initialize();
 
     final notification =
@@ -62,7 +62,7 @@
     );
   }
 
-  test_unknownOptionalNotifications_silentlyDropped() async {
+  Future<void> test_unknownOptionalNotifications_silentlyDropped() async {
     await initialize();
     final notification =
         makeNotification(Method.fromJson(r'$/randomNotification'), null);
@@ -83,9 +83,9 @@
     expect(didTimeout, isTrue);
   }
 
-  test_unknownRequest_rejected() async {
+  Future<void> test_unknownOptionalRequest_rejected() async {
     await initialize();
-    final request = makeRequest(Method.fromJson('randomRequest'), null);
+    final request = makeRequest(Method.fromJson(r'$/randomRequest'), null);
     final response = await channel.sendRequestToServer(request);
     expect(response.id, equals(request.id));
     expect(response.error, isNotNull);
@@ -93,9 +93,9 @@
     expect(response.result, isNull);
   }
 
-  test_unknownOptionalRequest_rejected() async {
+  Future<void> test_unknownRequest_rejected() async {
     await initialize();
-    final request = makeRequest(Method.fromJson(r'$/randomRequest'), null);
+    final request = makeRequest(Method.fromJson('randomRequest'), null);
     final response = await channel.sendRequestToServer(request);
     expect(response.id, equals(request.id));
     expect(response.error, isNotNull);
diff --git a/pkg/analysis_server/test/lsp/signature_help_test.dart b/pkg/analysis_server/test/lsp/signature_help_test.dart
index 3668966..c5ef295 100644
--- a/pkg/analysis_server/test/lsp/signature_help_test.dart
+++ b/pkg/analysis_server/test/lsp/signature_help_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SignatureHelpTest);
   });
@@ -16,253 +16,7 @@
 
 @reflectiveTest
 class SignatureHelpTest extends AbstractLspAnalysisServerTest {
-  test_formats_markdown() async {
-    final content = '''
-    /// Does foo.
-    foo(String s, int i) {
-      foo(^);
-    }
-    ''';
-    final expectedLabel = 'foo(String s, int i)';
-    final expectedDoc = 'Does foo.';
-
-    await initialize(
-        textDocumentCapabilities: withSignatureHelpContentFormat(
-            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
-    await openFile(mainFileUri, withoutMarkers(content));
-    await testSignature(
-      content,
-      expectedLabel,
-      expectedDoc,
-      [
-        ParameterInformation('String s', null),
-        ParameterInformation('int i', null),
-      ],
-      expectedFormat: MarkupKind.Markdown,
-    );
-  }
-
-  test_formats_notSupported() async {
-    final content = '''
-    /// Does foo.
-    foo(String s, int i) {
-      foo(^);
-    }
-    ''';
-    final expectedLabel = 'foo(String s, int i)';
-    final expectedDoc = 'Does foo.';
-
-    await initialize();
-    await openFile(mainFileUri, withoutMarkers(content));
-    await testSignature(
-      content,
-      expectedLabel,
-      expectedDoc,
-      [
-        ParameterInformation('String s', null),
-        ParameterInformation('int i', null),
-      ],
-      expectedFormat: null,
-    );
-  }
-
-  test_formats_plainTextOnly() async {
-    final content = '''
-    /// Does foo.
-    foo(String s, int i) {
-      foo(^);
-    }
-    ''';
-    final expectedLabel = 'foo(String s, int i)';
-    final expectedDoc = 'Does foo.';
-
-    await initialize(
-        textDocumentCapabilities: withSignatureHelpContentFormat(
-            emptyTextDocumentClientCapabilities, [MarkupKind.PlainText]));
-    await openFile(mainFileUri, withoutMarkers(content));
-    await testSignature(
-      content,
-      expectedLabel,
-      expectedDoc,
-      [
-        ParameterInformation('String s', null),
-        ParameterInformation('int i', null),
-      ],
-      expectedFormat: MarkupKind.PlainText,
-    );
-  }
-
-  test_formats_plainTextPreferred() async {
-    final content = '''
-    /// Does foo.
-    foo(String s, int i) {
-      foo(^);
-    }
-    ''';
-    final expectedLabel = 'foo(String s, int i)';
-    final expectedDoc = 'Does foo.';
-
-    // We say we prefer PlainText as a client, but since we only really
-    // support Markdown and the client supports it, we expect the server
-    // to provide Markdown.
-    await initialize(
-        textDocumentCapabilities: withSignatureHelpContentFormat(
-            emptyTextDocumentClientCapabilities,
-            [MarkupKind.PlainText, MarkupKind.Markdown]));
-    await openFile(mainFileUri, withoutMarkers(content));
-    await testSignature(
-      content,
-      expectedLabel,
-      expectedDoc,
-      [
-        ParameterInformation('String s', null),
-        ParameterInformation('int i', null),
-      ],
-      expectedFormat: MarkupKind.Markdown,
-    );
-  }
-
-  test_nonDartFile() async {
-    await initialize(
-        textDocumentCapabilities: withSignatureHelpContentFormat(
-            emptyTextDocumentClientCapabilities, [MarkupKind.PlainText]));
-    await openFile(pubspecFileUri, simplePubspecContent);
-    final res = await getSignatureHelp(pubspecFileUri, startOfDocPos);
-    expect(res, isNull);
-  }
-
-  test_params_multipleNamed() async {
-    final content = '''
-    /// Does foo.
-    foo(String s, {bool b = true, bool a}) {
-      foo(^);
-    }
-    ''';
-
-    final expectedLabel = 'foo(String s, {bool b = true, bool a})';
-    final expectedDoc = 'Does foo.';
-
-    await initialize(
-        textDocumentCapabilities: withSignatureHelpContentFormat(
-            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
-    await openFile(mainFileUri, withoutMarkers(content));
-    await testSignature(
-      content,
-      expectedLabel,
-      expectedDoc,
-      [
-        ParameterInformation('String s', null),
-        ParameterInformation('bool b = true', null),
-        ParameterInformation('bool a', null),
-      ],
-    );
-  }
-
-  test_params_multipleOptional() async {
-    final content = '''
-    /// Does foo.
-    foo(String s, [bool b = true, bool a]) {
-      foo(^);
-    }
-    ''';
-
-    final expectedLabel = 'foo(String s, [bool b = true, bool a])';
-    final expectedDoc = 'Does foo.';
-
-    await initialize(
-        textDocumentCapabilities: withSignatureHelpContentFormat(
-            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
-    await openFile(mainFileUri, withoutMarkers(content));
-    await testSignature(
-      content,
-      expectedLabel,
-      expectedDoc,
-      [
-        ParameterInformation('String s', null),
-        ParameterInformation('bool b = true', null),
-        ParameterInformation('bool a', null),
-      ],
-    );
-  }
-
-  test_params_named() async {
-    final content = '''
-    /// Does foo.
-    foo(String s, {bool b = true}) {
-      foo(^);
-    }
-    ''';
-
-    final expectedLabel = 'foo(String s, {bool b = true})';
-    final expectedDoc = 'Does foo.';
-
-    await initialize(
-        textDocumentCapabilities: withSignatureHelpContentFormat(
-            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
-    await openFile(mainFileUri, withoutMarkers(content));
-    await testSignature(
-      content,
-      expectedLabel,
-      expectedDoc,
-      [
-        ParameterInformation('String s', null),
-        ParameterInformation('bool b = true', null),
-      ],
-    );
-  }
-
-  test_params_optional() async {
-    final content = '''
-    /// Does foo.
-    foo(String s, [bool b = true]) {
-      foo(^);
-    }
-    ''';
-
-    final expectedLabel = 'foo(String s, [bool b = true])';
-    final expectedDoc = 'Does foo.';
-
-    await initialize(
-        textDocumentCapabilities: withSignatureHelpContentFormat(
-            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
-    await openFile(mainFileUri, withoutMarkers(content));
-    await testSignature(
-      content,
-      expectedLabel,
-      expectedDoc,
-      [
-        ParameterInformation('String s', null),
-        ParameterInformation('bool b = true', null),
-      ],
-    );
-  }
-
-  test_simple() async {
-    final content = '''
-    /// Does foo.
-    foo(String s, int i) {
-      foo(^);
-    }
-    ''';
-    final expectedLabel = 'foo(String s, int i)';
-    final expectedDoc = 'Does foo.';
-
-    await initialize(
-        textDocumentCapabilities: withSignatureHelpContentFormat(
-            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
-    await openFile(mainFileUri, withoutMarkers(content));
-    await testSignature(
-      content,
-      expectedLabel,
-      expectedDoc,
-      [
-        ParameterInformation('String s', null),
-        ParameterInformation('int i', null),
-      ],
-    );
-  }
-
-  test_dartDocMacro() async {
+  Future<void> test_dartDocMacro() async {
     final content = '''
     /// {@template template_name}
     /// This is shared content.
@@ -293,7 +47,253 @@
     );
   }
 
-  test_unopenFile() async {
+  Future<void> test_formats_markdown() async {
+    final content = '''
+    /// Does foo.
+    foo(String s, int i) {
+      foo(^);
+    }
+    ''';
+    final expectedLabel = 'foo(String s, int i)';
+    final expectedDoc = 'Does foo.';
+
+    await initialize(
+        textDocumentCapabilities: withSignatureHelpContentFormat(
+            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
+    await openFile(mainFileUri, withoutMarkers(content));
+    await testSignature(
+      content,
+      expectedLabel,
+      expectedDoc,
+      [
+        ParameterInformation('String s', null),
+        ParameterInformation('int i', null),
+      ],
+      expectedFormat: MarkupKind.Markdown,
+    );
+  }
+
+  Future<void> test_formats_notSupported() async {
+    final content = '''
+    /// Does foo.
+    foo(String s, int i) {
+      foo(^);
+    }
+    ''';
+    final expectedLabel = 'foo(String s, int i)';
+    final expectedDoc = 'Does foo.';
+
+    await initialize();
+    await openFile(mainFileUri, withoutMarkers(content));
+    await testSignature(
+      content,
+      expectedLabel,
+      expectedDoc,
+      [
+        ParameterInformation('String s', null),
+        ParameterInformation('int i', null),
+      ],
+      expectedFormat: null,
+    );
+  }
+
+  Future<void> test_formats_plainTextOnly() async {
+    final content = '''
+    /// Does foo.
+    foo(String s, int i) {
+      foo(^);
+    }
+    ''';
+    final expectedLabel = 'foo(String s, int i)';
+    final expectedDoc = 'Does foo.';
+
+    await initialize(
+        textDocumentCapabilities: withSignatureHelpContentFormat(
+            emptyTextDocumentClientCapabilities, [MarkupKind.PlainText]));
+    await openFile(mainFileUri, withoutMarkers(content));
+    await testSignature(
+      content,
+      expectedLabel,
+      expectedDoc,
+      [
+        ParameterInformation('String s', null),
+        ParameterInformation('int i', null),
+      ],
+      expectedFormat: MarkupKind.PlainText,
+    );
+  }
+
+  Future<void> test_formats_plainTextPreferred() async {
+    final content = '''
+    /// Does foo.
+    foo(String s, int i) {
+      foo(^);
+    }
+    ''';
+    final expectedLabel = 'foo(String s, int i)';
+    final expectedDoc = 'Does foo.';
+
+    // We say we prefer PlainText as a client, but since we only really
+    // support Markdown and the client supports it, we expect the server
+    // to provide Markdown.
+    await initialize(
+        textDocumentCapabilities: withSignatureHelpContentFormat(
+            emptyTextDocumentClientCapabilities,
+            [MarkupKind.PlainText, MarkupKind.Markdown]));
+    await openFile(mainFileUri, withoutMarkers(content));
+    await testSignature(
+      content,
+      expectedLabel,
+      expectedDoc,
+      [
+        ParameterInformation('String s', null),
+        ParameterInformation('int i', null),
+      ],
+      expectedFormat: MarkupKind.Markdown,
+    );
+  }
+
+  Future<void> test_nonDartFile() async {
+    await initialize(
+        textDocumentCapabilities: withSignatureHelpContentFormat(
+            emptyTextDocumentClientCapabilities, [MarkupKind.PlainText]));
+    await openFile(pubspecFileUri, simplePubspecContent);
+    final res = await getSignatureHelp(pubspecFileUri, startOfDocPos);
+    expect(res, isNull);
+  }
+
+  Future<void> test_params_multipleNamed() async {
+    final content = '''
+    /// Does foo.
+    foo(String s, {bool b = true, bool a}) {
+      foo(^);
+    }
+    ''';
+
+    final expectedLabel = 'foo(String s, {bool b = true, bool a})';
+    final expectedDoc = 'Does foo.';
+
+    await initialize(
+        textDocumentCapabilities: withSignatureHelpContentFormat(
+            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
+    await openFile(mainFileUri, withoutMarkers(content));
+    await testSignature(
+      content,
+      expectedLabel,
+      expectedDoc,
+      [
+        ParameterInformation('String s', null),
+        ParameterInformation('bool b = true', null),
+        ParameterInformation('bool a', null),
+      ],
+    );
+  }
+
+  Future<void> test_params_multipleOptional() async {
+    final content = '''
+    /// Does foo.
+    foo(String s, [bool b = true, bool a]) {
+      foo(^);
+    }
+    ''';
+
+    final expectedLabel = 'foo(String s, [bool b = true, bool a])';
+    final expectedDoc = 'Does foo.';
+
+    await initialize(
+        textDocumentCapabilities: withSignatureHelpContentFormat(
+            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
+    await openFile(mainFileUri, withoutMarkers(content));
+    await testSignature(
+      content,
+      expectedLabel,
+      expectedDoc,
+      [
+        ParameterInformation('String s', null),
+        ParameterInformation('bool b = true', null),
+        ParameterInformation('bool a', null),
+      ],
+    );
+  }
+
+  Future<void> test_params_named() async {
+    final content = '''
+    /// Does foo.
+    foo(String s, {bool b = true}) {
+      foo(^);
+    }
+    ''';
+
+    final expectedLabel = 'foo(String s, {bool b = true})';
+    final expectedDoc = 'Does foo.';
+
+    await initialize(
+        textDocumentCapabilities: withSignatureHelpContentFormat(
+            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
+    await openFile(mainFileUri, withoutMarkers(content));
+    await testSignature(
+      content,
+      expectedLabel,
+      expectedDoc,
+      [
+        ParameterInformation('String s', null),
+        ParameterInformation('bool b = true', null),
+      ],
+    );
+  }
+
+  Future<void> test_params_optional() async {
+    final content = '''
+    /// Does foo.
+    foo(String s, [bool b = true]) {
+      foo(^);
+    }
+    ''';
+
+    final expectedLabel = 'foo(String s, [bool b = true])';
+    final expectedDoc = 'Does foo.';
+
+    await initialize(
+        textDocumentCapabilities: withSignatureHelpContentFormat(
+            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
+    await openFile(mainFileUri, withoutMarkers(content));
+    await testSignature(
+      content,
+      expectedLabel,
+      expectedDoc,
+      [
+        ParameterInformation('String s', null),
+        ParameterInformation('bool b = true', null),
+      ],
+    );
+  }
+
+  Future<void> test_simple() async {
+    final content = '''
+    /// Does foo.
+    foo(String s, int i) {
+      foo(^);
+    }
+    ''';
+    final expectedLabel = 'foo(String s, int i)';
+    final expectedDoc = 'Does foo.';
+
+    await initialize(
+        textDocumentCapabilities: withSignatureHelpContentFormat(
+            emptyTextDocumentClientCapabilities, [MarkupKind.Markdown]));
+    await openFile(mainFileUri, withoutMarkers(content));
+    await testSignature(
+      content,
+      expectedLabel,
+      expectedDoc,
+      [
+        ParameterInformation('String s', null),
+        ParameterInformation('int i', null),
+      ],
+    );
+  }
+
+  Future<void> test_unopenFile() async {
     final content = '''
     /// Does foo.
     foo(String s, int i) {
diff --git a/pkg/analysis_server/test/lsp/super_test.dart b/pkg/analysis_server/test/lsp/super_test.dart
index 32f79df..0b81f12 100644
--- a/pkg/analysis_server/test/lsp/super_test.dart
+++ b/pkg/analysis_server/test/lsp/super_test.dart
@@ -8,7 +8,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SuperTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class SuperTest extends AbstractLspAnalysisServerTest {
-  test_className() async {
+  Future<void> test_className() async {
     final content = '''
 class A {}
 
@@ -35,7 +35,7 @@
         equals(Location(mainFileUri.toString(), rangeFromMarkers(content))));
   }
 
-  test_insideClass() async {
+  Future<void> test_insideClass() async {
     final content = '''
 class A {}
 
@@ -56,7 +56,7 @@
         equals(Location(mainFileUri.toString(), rangeFromMarkers(content))));
   }
 
-  test_insideMethod() async {
+  Future<void> test_insideMethod() async {
     final content = '''
 class A {
   void [[foo]]() {}
@@ -82,7 +82,7 @@
         equals(Location(mainFileUri.toString(), rangeFromMarkers(content))));
   }
 
-  test_methodName() async {
+  Future<void> test_methodName() async {
     final content = '''
 class A {
   void [[foo]]() {}
@@ -108,7 +108,7 @@
         equals(Location(mainFileUri.toString(), rangeFromMarkers(content))));
   }
 
-  test_methodReturnType() async {
+  Future<void> test_methodReturnType() async {
     final content = '''
 class A {
   void [[foo]]() {}
diff --git a/pkg/analysis_server/test/lsp/test_all.dart b/pkg/analysis_server/test/lsp/test_all.dart
index 5b93e41..6ed924f 100644
--- a/pkg/analysis_server/test/lsp/test_all.dart
+++ b/pkg/analysis_server/test/lsp/test_all.dart
@@ -35,7 +35,7 @@
 import 'super_test.dart' as get_super;
 import 'workspace_symbols_test.dart' as workspace_symbols;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     analyzer_status.main();
     cancel_request.main();
diff --git a/pkg/analysis_server/test/lsp/workspace_symbols_test.dart b/pkg/analysis_server/test/lsp/workspace_symbols_test.dart
index 20de6a0..3558555 100644
--- a/pkg/analysis_server/test/lsp/workspace_symbols_test.dart
+++ b/pkg/analysis_server/test/lsp/workspace_symbols_test.dart
@@ -9,7 +9,7 @@
 
 import 'server_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(WorkspaceSymbolsTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class WorkspaceSymbolsTest extends AbstractLspAnalysisServerTest {
-  test_fullMatch() async {
+  Future<void> test_fullMatch() async {
     const content = '''
     [[String topLevel = '']];
     class MyClass {
@@ -42,7 +42,7 @@
     expect(symbols.any((s) => s.name.contains('myMethod')), isFalse);
   }
 
-  test_fuzzyMatch() async {
+  Future<void> test_fuzzyMatch() async {
     const content = '''
     String topLevel = '';
     class MyClass {
@@ -68,7 +68,7 @@
     expect(symbols.any((s) => s.name.contains('myMethod')), isFalse);
   }
 
-  test_invalidParams() async {
+  Future<void> test_invalidParams() async {
     await initialize();
 
     // Create a request that doesn't supply the query param.
@@ -89,7 +89,7 @@
     );
   }
 
-  test_partialMatch() async {
+  Future<void> test_partialMatch() async {
     const content = '''
     String topLevel = '';
     class MyClass {
diff --git a/pkg/analysis_server/test/plugin/protocol_dart_test.dart b/pkg/analysis_server/test/plugin/protocol_dart_test.dart
index 9c85aaa..7927686 100644
--- a/pkg/analysis_server/test/plugin/protocol_dart_test.dart
+++ b/pkg/analysis_server/test/plugin/protocol_dart_test.dart
@@ -19,7 +19,7 @@
 
 import '../abstract_context.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ElementTest);
     defineReflectiveTests(ElementKindTest);
@@ -104,7 +104,7 @@
         .single;
   }
 
-  test_fromElement_CLASS() async {
+  Future<void> test_fromElement_CLASS() async {
     engine.Source source = addSource('/test.dart', '''
 @deprecated
 abstract class _A {}
@@ -143,7 +143,7 @@
     }
   }
 
-  test_fromElement_CONSTRUCTOR() async {
+  Future<void> test_fromElement_CONSTRUCTOR() async {
     engine.Source source = addSource('/test.dart', '''
 class A {
   const A.myConstructor(int a, [String b]);
@@ -169,7 +169,7 @@
     expect(element.flags, Element.FLAG_CONST);
   }
 
-  test_fromElement_CONSTRUCTOR_required_parameters_1() async {
+  Future<void> test_fromElement_CONSTRUCTOR_required_parameters_1() async {
     addMetaPackage();
     engine.Source source = addSource('/test.dart', '''
 import 'package:meta/meta.dart';    
@@ -186,7 +186,7 @@
   }
 
   /// Verify parameter re-ordering for required params
-  test_fromElement_CONSTRUCTOR_required_parameters_2() async {
+  Future<void> test_fromElement_CONSTRUCTOR_required_parameters_2() async {
     addMetaPackage();
     engine.Source source = addSource('/test.dart', '''
 import 'package:meta/meta.dart';    
@@ -204,7 +204,7 @@
   }
 
   /// Verify parameter re-ordering for required params
-  test_fromElement_CONSTRUCTOR_required_parameters_3() async {
+  Future<void> test_fromElement_CONSTRUCTOR_required_parameters_3() async {
     addMetaPackage();
     engine.Source source = addSource('/test.dart', '''
 import 'package:meta/meta.dart';    
@@ -233,7 +233,7 @@
     expect(element.flags, 0);
   }
 
-  test_fromElement_ENUM() async {
+  Future<void> test_fromElement_ENUM() async {
     engine.Source source = addSource('/test.dart', '''
 @deprecated
 enum _E1 { one, two }
@@ -272,7 +272,7 @@
     }
   }
 
-  test_fromElement_ENUM_CONSTANT() async {
+  Future<void> test_fromElement_ENUM_CONSTANT() async {
     engine.Source source = addSource('/test.dart', '''
 @deprecated
 enum _E1 { one, two }
@@ -360,7 +360,7 @@
     }
   }
 
-  test_fromElement_FIELD() async {
+  Future<void> test_fromElement_FIELD() async {
     engine.Source source = addSource('/test.dart', '''
 class A {
   static const myField = 42;
@@ -384,7 +384,7 @@
     expect(element.flags, Element.FLAG_CONST | Element.FLAG_STATIC);
   }
 
-  test_fromElement_FUNCTION_TYPE_ALIAS() async {
+  Future<void> test_fromElement_FUNCTION_TYPE_ALIAS() async {
     engine.Source source = addSource('/test.dart', '''
 typedef int F<T>(String x);
 ''');
@@ -409,7 +409,7 @@
     expect(element.flags, 0);
   }
 
-  test_fromElement_FUNCTION_TYPE_ALIAS_genericTypeAlias() async {
+  Future<void> test_fromElement_FUNCTION_TYPE_ALIAS_genericTypeAlias() async {
     engine.Source source = addSource('/test.dart', '''
 typedef F<T> = int Function(String x);
 ''');
@@ -433,7 +433,7 @@
     expect(element.flags, 0);
   }
 
-  test_fromElement_GETTER() async {
+  Future<void> test_fromElement_GETTER() async {
     engine.Source source = addSource('/test.dart', '''
 class A {
   String get myGetter => 42;
@@ -458,7 +458,7 @@
     expect(element.flags, 0);
   }
 
-  test_fromElement_LABEL() async {
+  Future<void> test_fromElement_LABEL() async {
     engine.Source source = addSource('/test.dart', '''
 main() {
 myLabel:
@@ -485,7 +485,7 @@
     expect(element.flags, 0);
   }
 
-  test_fromElement_METHOD() async {
+  Future<void> test_fromElement_METHOD() async {
     engine.Source source = addSource('/test.dart', '''
 class A {
   static List<String> myMethod(int a, {String b, int c}) {
@@ -511,7 +511,7 @@
     expect(element.flags, Element.FLAG_STATIC);
   }
 
-  test_fromElement_MIXIN() async {
+  Future<void> test_fromElement_MIXIN() async {
     engine.Source source = addSource('/test.dart', '''
 mixin A {}
 ''');
@@ -536,7 +536,7 @@
     }
   }
 
-  test_fromElement_SETTER() async {
+  Future<void> test_fromElement_SETTER() async {
     engine.Source source = addSource('/test.dart', '''
 class A {
   set mySetter(String x) {}
diff --git a/pkg/analysis_server/test/plugin/test_all.dart b/pkg/analysis_server/test/plugin/test_all.dart
index 284a4a3..4822d24 100644
--- a/pkg/analysis_server/test/plugin/test_all.dart
+++ b/pkg/analysis_server/test/plugin/test_all.dart
@@ -9,7 +9,7 @@
 /**
  * Utility for manually running all tests.
  */
-main() {
+void main() {
   defineReflectiveSuite(() {
     protocol_dart_test.main();
   }, name: 'plugin');
diff --git a/pkg/analysis_server/test/protocol_server_test.dart b/pkg/analysis_server/test/protocol_server_test.dart
index f4e6b3d..bfd8810 100644
--- a/pkg/analysis_server/test/protocol_server_test.dart
+++ b/pkg/analysis_server/test/protocol_server_test.dart
@@ -25,7 +25,7 @@
 import 'constants.dart';
 import 'mocks.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisErrorTest);
     defineReflectiveTests(EnumTest);
@@ -334,7 +334,7 @@
   FileResult getFile(String path) => fileResults[path];
 
   @override
-  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
 
 class MockErrorCode implements engine.ErrorCode {
diff --git a/pkg/analysis_server/test/protocol_test.dart b/pkg/analysis_server/test/protocol_test.dart
index 7844b03..e6dbec1 100644
--- a/pkg/analysis_server/test/protocol_test.dart
+++ b/pkg/analysis_server/test/protocol_test.dart
@@ -12,7 +12,7 @@
 
 import 'constants.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(NotificationTest);
     defineReflectiveTests(RequestTest);
diff --git a/pkg/analysis_server/test/search/declarations_test.dart b/pkg/analysis_server/test/search/declarations_test.dart
index 1df1d4f..f283321 100644
--- a/pkg/analysis_server/test/search/declarations_test.dart
+++ b/pkg/analysis_server/test/search/declarations_test.dart
@@ -12,7 +12,7 @@
 
 import 'abstract_search_domain.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DeclarationsTest);
   });
@@ -40,7 +40,7 @@
             d.name == name))));
   }
 
-  test_class() async {
+  Future<void> test_class() async {
     addTestFile(r'''
 class C {
   int f;
@@ -71,7 +71,7 @@
     }
   }
 
-  test_enum() async {
+  Future<void> test_enum() async {
     addTestFile(r'''
 enum E {
   a, b, c
@@ -85,7 +85,7 @@
     assertHas('c', ElementKind.ENUM_CONSTANT);
   }
 
-  test_maxResults() async {
+  Future<void> test_maxResults() async {
     newFile(join(testFolder, 'a.dart'), content: r'''
 class A {}
 class B {}
@@ -108,7 +108,7 @@
     expect(declarationsResult.declarations, hasLength(4));
   }
 
-  test_mixin() async {
+  Future<void> test_mixin() async {
     addTestFile(r'''
 mixin M {
   int f;
@@ -126,7 +126,7 @@
     assertHas('m', ElementKind.METHOD, mixinName: 'M');
   }
 
-  test_multipleFiles() async {
+  Future<void> test_multipleFiles() async {
     var a = newFile(join(testFolder, 'a.dart'), content: 'class A {}').path;
     var b = newFile(join(testFolder, 'b.dart'), content: 'class B {}').path;
 
@@ -155,7 +155,7 @@
     }
   }
 
-  test_onlyForFile() async {
+  Future<void> test_onlyForFile() async {
     var a = newFile(join(testFolder, 'a.dart'), content: 'class A {}').path;
     newFile(join(testFolder, 'b.dart'), content: 'class B {}').path;
 
@@ -170,7 +170,7 @@
     expect(declarationsResult.files[declaration.fileIndex], a);
   }
 
-  test_parameters() async {
+  Future<void> test_parameters() async {
     addTestFile(r'''
 void f(bool a, String b) {}
 ''');
@@ -180,7 +180,7 @@
     expect(declaration.parameters, '(bool a, String b)');
   }
 
-  test_regExp() async {
+  Future<void> test_regExp() async {
     addTestFile(r'''
 class A {}
 class B {}
@@ -195,7 +195,7 @@
     assertNo('D');
   }
 
-  test_top() async {
+  Future<void> test_top() async {
     addTestFile(r'''
 int get g => 0;
 void set s(_) {}
diff --git a/pkg/analysis_server/test/search/element_references_test.dart b/pkg/analysis_server/test/search/element_references_test.dart
index de7f04e..5792f5b 100644
--- a/pkg/analysis_server/test/search/element_references_test.dart
+++ b/pkg/analysis_server/test/search/element_references_test.dart
@@ -12,7 +12,7 @@
 
 import 'abstract_search_domain.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ElementReferencesTest);
   });
@@ -128,7 +128,7 @@
     assertHasResult(SearchResultKind.REFERENCE, '(1)', 0);
   }
 
-  test_extension() async {
+  Future<void> test_extension() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     addTestFile('''
 extension E on int {
@@ -238,7 +238,7 @@
     assertHasResult(SearchResultKind.READ, 'fff); // in m()');
   }
 
-  test_field_ofExtension_explicit_static() async {
+  Future<void> test_field_ofExtension_explicit_static() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     addTestFile('''
 extension E on int {
@@ -274,7 +274,7 @@
     assertHasResult(SearchResultKind.READ, 'fff(); // in main()');
   }
 
-  test_field_ofExtension_implicit_instance() async {
+  Future<void> test_field_ofExtension_implicit_instance() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     addTestFile('''
 extension E on int {
@@ -309,7 +309,7 @@
     }
   }
 
-  test_field_ofExtension_implicit_static() async {
+  Future<void> test_field_ofExtension_implicit_static() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     addTestFile('''
 extension E on int {
@@ -515,7 +515,7 @@
     assertHasResult(SearchResultKind.REFERENCE, 'mmm); // in main()');
   }
 
-  test_method_ofExtension() async {
+  Future<void> test_method_ofExtension() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     addTestFile('''
 extension E on int {
diff --git a/pkg/analysis_server/test/search/member_declarations_test.dart b/pkg/analysis_server/test/search/member_declarations_test.dart
index 9afda85..8c9016e 100644
--- a/pkg/analysis_server/test/search/member_declarations_test.dart
+++ b/pkg/analysis_server/test/search/member_declarations_test.dart
@@ -12,7 +12,7 @@
 
 import 'abstract_search_domain.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MemberDeclarationsTest);
   });
@@ -47,7 +47,7 @@
     return null;
   }
 
-  test_localVariable() async {
+  Future<void> test_localVariable() async {
     addTestFile('''
 class A {
   main() {
@@ -59,7 +59,7 @@
     expect(results, isEmpty);
   }
 
-  test_localVariable_forIn() async {
+  Future<void> test_localVariable_forIn() async {
     addTestFile('''
 class A {
   main() {
@@ -72,7 +72,7 @@
     expect(results, isEmpty);
   }
 
-  test_methodField() async {
+  Future<void> test_methodField() async {
     addTestFile('''
 class A {
   foo() {}
@@ -88,7 +88,7 @@
     assertHasDeclaration(ElementKind.FIELD, 'B');
   }
 
-  test_methodGetter() async {
+  Future<void> test_methodGetter() async {
     addTestFile('''
 class A {
   foo() {}
@@ -104,7 +104,7 @@
     assertHasDeclaration(ElementKind.GETTER, 'B');
   }
 
-  test_methodGetterSetter() async {
+  Future<void> test_methodGetterSetter() async {
     addTestFile('''
 class A {
   foo() {}
@@ -122,7 +122,7 @@
     assertHasDeclaration(ElementKind.SETTER, 'B');
   }
 
-  test_methodMethod() async {
+  Future<void> test_methodMethod() async {
     addTestFile('''
 class A {
   foo() {}
@@ -138,7 +138,7 @@
     assertHasDeclaration(ElementKind.METHOD, 'B');
   }
 
-  test_methodSetter() async {
+  Future<void> test_methodSetter() async {
     addTestFile('''
 class A {
   foo() {}
diff --git a/pkg/analysis_server/test/search/member_references_test.dart b/pkg/analysis_server/test/search/member_references_test.dart
index b60931a..9f65668 100644
--- a/pkg/analysis_server/test/search/member_references_test.dart
+++ b/pkg/analysis_server/test/search/member_references_test.dart
@@ -11,7 +11,7 @@
 
 import 'abstract_search_domain.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MemberReferencesTest);
   });
diff --git a/pkg/analysis_server/test/search/search_result_test.dart b/pkg/analysis_server/test/search/search_result_test.dart
index ffa7468..02c82a6 100644
--- a/pkg/analysis_server/test/search/search_result_test.dart
+++ b/pkg/analysis_server/test/search/search_result_test.dart
@@ -7,7 +7,7 @@
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SearchResultKindTest);
   });
diff --git a/pkg/analysis_server/test/search/test_all.dart b/pkg/analysis_server/test/search/test_all.dart
index 2e85dae..403be90 100644
--- a/pkg/analysis_server/test/search/test_all.dart
+++ b/pkg/analysis_server/test/search/test_all.dart
@@ -12,10 +12,7 @@
 import 'top_level_declarations_test.dart' as top_level_declarations_test;
 import 'type_hierarchy_test.dart' as type_hierarchy_test;
 
-/**
- * Utility for manually running all tests.
- */
-main() {
+void main() {
   defineReflectiveSuite(() {
     declarations_test.main();
     element_references_test.main();
diff --git a/pkg/analysis_server/test/search/top_level_declarations_test.dart b/pkg/analysis_server/test/search/top_level_declarations_test.dart
index c28648a..6895313 100644
--- a/pkg/analysis_server/test/search/top_level_declarations_test.dart
+++ b/pkg/analysis_server/test/search/top_level_declarations_test.dart
@@ -12,7 +12,7 @@
 
 import 'abstract_search_domain.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(TopLevelDeclarationsTest);
   });
@@ -56,7 +56,7 @@
     return null;
   }
 
-  test_extensionDeclaration() async {
+  Future<void> test_extensionDeclaration() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     addTestFile('''
 extension MyExtension on int {}
@@ -65,12 +65,12 @@
     assertHasDeclaration(ElementKind.EXTENSION, 'MyExtension');
   }
 
-  test_invalidRegex() async {
+  Future<void> test_invalidRegex() async {
     var result = await findTopLevelDeclarations('[A');
     expect(result, const TypeMatcher<RequestError>());
   }
 
-  test_startEndPattern() async {
+  Future<void> test_startEndPattern() async {
     addTestFile('''
 class A {} // A
 class B = Object with A;
diff --git a/pkg/analysis_server/test/search/type_hierarchy_test.dart b/pkg/analysis_server/test/search/type_hierarchy_test.dart
index a2a1be0..40a2278 100644
--- a/pkg/analysis_server/test/search/type_hierarchy_test.dart
+++ b/pkg/analysis_server/test/search/type_hierarchy_test.dart
@@ -13,7 +13,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetTypeHierarchyTest);
   });
@@ -32,7 +32,7 @@
     ];
   }
 
-  test_bad_function() async {
+  Future<void> test_bad_function() async {
     addTestFile('''
 main() {
 }
@@ -41,7 +41,7 @@
     expect(items, isNull);
   }
 
-  test_bad_noElement() async {
+  Future<void> test_bad_noElement() async {
     addTestFile('''
 main() {
   /* target */
@@ -87,7 +87,7 @@
     ]);
   }
 
-  test_class_displayName() async {
+  Future<void> test_class_displayName() async {
     addTestFile('''
 class A<T> {
 }
@@ -312,7 +312,7 @@
     ]);
   }
 
-  test_class_extendsTypeC() async {
+  Future<void> test_class_extendsTypeC() async {
     addTestFile('''
 class A {
 }
@@ -373,7 +373,7 @@
     ]);
   }
 
-  test_class_implementsTypes() async {
+  Future<void> test_class_implementsTypes() async {
     addTestFile('''
 class MA {}
 class MB {}
@@ -434,7 +434,7 @@
     ]);
   }
 
-  test_class_withTypes() async {
+  Future<void> test_class_withTypes() async {
     addTestFile('''
 class MA {}
 class MB {}
@@ -537,7 +537,7 @@
     expect(memberB.location.offset, findOffset('test(m) {}'));
   }
 
-  test_member_fromField_toField() async {
+  Future<void> test_member_fromField_toField() async {
     addTestFile('''
 class A {
   var test = 1;
@@ -555,7 +555,7 @@
     expect(itemB.memberElement.location.offset, findOffset('test = 2;'));
   }
 
-  test_member_fromField_toGetter() async {
+  Future<void> test_member_fromField_toGetter() async {
     addTestFile('''
 class A {
   get test => 1;
@@ -573,7 +573,7 @@
     expect(itemB.memberElement.location.offset, findOffset('test = 2;'));
   }
 
-  test_member_fromField_toSetter() async {
+  Future<void> test_member_fromField_toSetter() async {
     addTestFile('''
 class A {
   set test(a) {}
@@ -591,7 +591,7 @@
     expect(itemB.memberElement.location.offset, findOffset('test = 2;'));
   }
 
-  test_member_fromFinalField_toGetter() async {
+  Future<void> test_member_fromFinalField_toGetter() async {
     addTestFile('''
 class A {
   get test => 1;
@@ -609,7 +609,7 @@
     expect(itemB.memberElement.location.offset, findOffset('test = 2;'));
   }
 
-  test_member_fromFinalField_toSetter() async {
+  Future<void> test_member_fromFinalField_toSetter() async {
     addTestFile('''
 class A {
   set test(x) {}
@@ -1010,7 +1010,7 @@
         itemD.memberElement.location.offset, findOffset('test(x) {} // in D'));
   }
 
-  test_superOnly() async {
+  Future<void> test_superOnly() async {
     addTestFile('''
 class A {}
 class B {}
diff --git a/pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart
index 8336ebe..340d30f 100644
--- a/pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart
@@ -10,7 +10,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ArgListContributorTest);
   });
@@ -124,7 +124,7 @@
     return ArgListContributor();
   }
 
-  test_Annotation_imported_constructor_named_param() async {
+  Future<void> test_Annotation_imported_constructor_named_param() async {
     addSource('/home/test/lib/a.dart', '''
 library libA; class A { const A({int one, String two: 'defaultValue'}); }''');
     addTestSource('import "a.dart"; @A(^) main() { }');
@@ -133,7 +133,7 @@
         namedArgumentsWithTypes: {'one': 'int', 'two': 'String'});
   }
 
-  test_Annotation_importedConstructor_prefixed() async {
+  Future<void> test_Annotation_importedConstructor_prefixed() async {
     addSource('/home/test/lib/a.dart', '''
 class A {
   const A({int value});
@@ -148,7 +148,7 @@
     assertSuggestArgumentsAndTypes(namedArgumentsWithTypes: {'value': 'int'});
   }
 
-  test_Annotation_local_constructor_named_param() async {
+  Future<void> test_Annotation_local_constructor_named_param() async {
     addTestSource('''
 class A { const A({int one, String two: 'defaultValue'}); }
 @A(^) main() { }''');
@@ -158,7 +158,7 @@
   }
 
   @failingTest
-  test_Annotation_local_constructor_named_param_10() async {
+  Future<void> test_Annotation_local_constructor_named_param_10() async {
     addTestSource('''
 class A { const A({int one, String two: 'defaultValue'}); }
 @A(two: '2' ^) main() { }''');
@@ -166,7 +166,7 @@
     assertSuggestions([', one: ']);
   }
 
-  test_Annotation_local_constructor_named_param_11() async {
+  Future<void> test_Annotation_local_constructor_named_param_11() async {
     addTestSource('''
 class A { const A({int one, String two: 'defaultValue'}); }
 @A(two: '2', ^) main() { }''');
@@ -174,7 +174,7 @@
     assertSuggestArgumentsAndTypes(namedArgumentsWithTypes: {'one': 'int'});
   }
 
-  test_Annotation_local_constructor_named_param_2() async {
+  Future<void> test_Annotation_local_constructor_named_param_2() async {
     addTestSource('''
 class A { const A({int one, String two: 'defaultValue'}); }
 @A(^ two: '2') main() { }''');
@@ -182,7 +182,7 @@
     assertSuggestions(['one: ,']);
   }
 
-  test_Annotation_local_constructor_named_param_3() async {
+  Future<void> test_Annotation_local_constructor_named_param_3() async {
     addTestSource('''
 class A { const A({int one, String two: 'defaultValue'}); }
 @A(^two: '2') main() { }''');
@@ -190,7 +190,7 @@
     assertSuggestions(['one: ,']);
   }
 
-  test_Annotation_local_constructor_named_param_4() async {
+  Future<void> test_Annotation_local_constructor_named_param_4() async {
     addTestSource('''
 class A { const A({int one, String two: 'defaultValue'}); }
 @A(^, two: '2') main() { }''');
@@ -198,7 +198,7 @@
     assertSuggestArgumentsAndTypes(namedArgumentsWithTypes: {'one': 'int'});
   }
 
-  test_Annotation_local_constructor_named_param_5() async {
+  Future<void> test_Annotation_local_constructor_named_param_5() async {
     addTestSource('''
 class A { const A({int one, String two: 'defaultValue'}); }
 @A(^ , two: '2') main() { }''');
@@ -206,7 +206,7 @@
     assertSuggestArgumentsAndTypes(namedArgumentsWithTypes: {'one': 'int'});
   }
 
-  test_Annotation_local_constructor_named_param_6() async {
+  Future<void> test_Annotation_local_constructor_named_param_6() async {
     addTestSource('''
 class A { const A(int zero, {int one, String two: 'defaultValue'}); }
 @A(0, ^, two: '2') main() { }''');
@@ -214,7 +214,7 @@
     assertSuggestArgumentsAndTypes(namedArgumentsWithTypes: {'one': 'int'});
   }
 
-  test_Annotation_local_constructor_named_param_7() async {
+  Future<void> test_Annotation_local_constructor_named_param_7() async {
     addTestSource('''
 class A { const A(int zero, {int one, String two: 'defaultValue'}); }
 @A(0, ^ two: '2') main() { }''');
@@ -222,7 +222,7 @@
     assertSuggestions(['one: ,']);
   }
 
-  test_Annotation_local_constructor_named_param_8() async {
+  Future<void> test_Annotation_local_constructor_named_param_8() async {
     addTestSource('''
 class A { const A(int zero, {int one, String two: 'defaultValue'}); }
 @A(0, ^two: '2') main() { }''');
@@ -231,7 +231,7 @@
   }
 
   @failingTest
-  test_Annotation_local_constructor_named_param_9() async {
+  Future<void> test_Annotation_local_constructor_named_param_9() async {
     addTestSource('''
 class A { const A({int one, String two: 'defaultValue'}); }
 @A(two: '2'^) main() { }''');
@@ -239,7 +239,7 @@
     assertSuggestions([', one: ']);
   }
 
-  test_Annotation_local_constructor_named_param_negative() async {
+  Future<void> test_Annotation_local_constructor_named_param_negative() async {
     addTestSource('''
 class A { const A(int one, int two, int three, {int four, String five:
   'defaultValue'}); }
@@ -248,7 +248,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_closureFunction_namedParameter() async {
+  Future<void> test_ArgumentList_closureFunction_namedParameter() async {
     addTestSource(r'''
 void f({void Function(int a, String b) closure}) {}
 
@@ -273,7 +273,8 @@
     );
   }
 
-  test_ArgumentList_closureFunction_namedParameter_hasComma() async {
+  Future<void>
+      test_ArgumentList_closureFunction_namedParameter_hasComma() async {
     addTestSource(r'''
 void f({void Function(int a, String b) closure}) {}
 
@@ -301,7 +302,7 @@
 
   /// todo (pq): implement positional functional parameters
   @failingTest
-  test_ArgumentList_closureFunction_positionalParameter() async {
+  Future<void> test_ArgumentList_closureFunction_positionalParameter() async {
     addTestSource(r'''
 void f(void Function(int a, int b) closure) {}
 
@@ -317,7 +318,7 @@
     );
   }
 
-  test_ArgumentList_closureMethod_namedParameter() async {
+  Future<void> test_ArgumentList_closureMethod_namedParameter() async {
     addTestSource(r'''
 class C {
   void f({void Function(int a, String b) closure}) {}
@@ -343,7 +344,7 @@
     );
   }
 
-  test_ArgumentList_closureParameterOptionalNamed() async {
+  Future<void> test_ArgumentList_closureParameterOptionalNamed() async {
     addTestSource(r'''
 void f({void Function(int a, {int b, int c}) closure}) {}
 
@@ -359,7 +360,7 @@
     );
   }
 
-  test_ArgumentList_closureParameterOptionalPositional() async {
+  Future<void> test_ArgumentList_closureParameterOptionalPositional() async {
     addTestSource(r'''
 void f({void Function(int a, [int b, int c]) closure]) {}
 
@@ -376,7 +377,7 @@
     );
   }
 
-  test_ArgumentList_Flutter_InstanceCreationExpression_0() async {
+  Future<void> test_ArgumentList_Flutter_InstanceCreationExpression_0() async {
     addFlutterPackage();
 
     addTestSource('''
@@ -397,7 +398,7 @@
         defaultArgumentListTextRanges: null);
   }
 
-  test_ArgumentList_Flutter_InstanceCreationExpression_01() async {
+  Future<void> test_ArgumentList_Flutter_InstanceCreationExpression_01() async {
     addFlutterPackage();
 
     addTestSource('''
@@ -419,7 +420,7 @@
         selectionOffset: 17);
   }
 
-  test_ArgumentList_Flutter_InstanceCreationExpression_1() async {
+  Future<void> test_ArgumentList_Flutter_InstanceCreationExpression_1() async {
     addFlutterPackage();
 
     addTestSource('''
@@ -441,7 +442,7 @@
         defaultArgumentListTextRanges: null);
   }
 
-  test_ArgumentList_Flutter_InstanceCreationExpression_2() async {
+  Future<void> test_ArgumentList_Flutter_InstanceCreationExpression_2() async {
     addFlutterPackage();
 
     addTestSource('''
@@ -463,7 +464,8 @@
         defaultArgumentListTextRanges: null);
   }
 
-  test_ArgumentList_Flutter_InstanceCreationExpression_children_dynamic() async {
+  Future<void>
+      test_ArgumentList_Flutter_InstanceCreationExpression_children_dynamic() async {
     // Ensure we don't generate unneeded <dynamic> param if a future API doesn't
     // type it's children.
     addFlutterPackage();
@@ -490,7 +492,8 @@
         defaultArgumentListTextRanges: null);
   }
 
-  test_ArgumentList_Flutter_InstanceCreationExpression_children_Map() async {
+  Future<void>
+      test_ArgumentList_Flutter_InstanceCreationExpression_children_Map() async {
     // Ensure we don't generate Map params for a future API
     addFlutterPackage();
 
@@ -515,7 +518,8 @@
         defaultArgListString: null);
   }
 
-  test_ArgumentList_Flutter_InstanceCreationExpression_slivers() async {
+  Future<void>
+      test_ArgumentList_Flutter_InstanceCreationExpression_slivers() async {
     addFlutterPackage();
 
     addTestSource('''
@@ -540,7 +544,7 @@
         defaultArgumentListTextRanges: null);
   }
 
-  test_ArgumentList_Flutter_MethodExpression_children() async {
+  Future<void> test_ArgumentList_Flutter_MethodExpression_children() async {
     // Ensure we don't generate params for a method call
     // TODO(brianwilkerson) This test has been changed so that it no longer has
     // anything to do with Flutter (by moving the declaration of `foo` out of
@@ -565,13 +569,13 @@
         defaultArgListString: null);
   }
 
-  test_ArgumentList_getter() async {
+  Future<void> test_ArgumentList_getter() async {
     addTestSource('class A {int get foo => 7; main() {foo(^)}');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_ArgumentList_imported_constructor_named_param() async {
+  Future<void> test_ArgumentList_imported_constructor_named_param() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement
     addSource('/home/test/lib/a.dart', 'library libA; class A{A({int one}); }');
     addTestSource('import "a.dart"; main() { new A(^);}');
@@ -579,7 +583,7 @@
     assertSuggestArgumentsAndTypes(namedArgumentsWithTypes: {'one': 'int'});
   }
 
-  test_ArgumentList_imported_constructor_named_param2() async {
+  Future<void> test_ArgumentList_imported_constructor_named_param2() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement
     addSource(
         '/home/test/lib/a.dart', 'library libA; class A{A.foo({int one}); }');
@@ -588,7 +592,8 @@
     assertSuggestArgumentsAndTypes(namedArgumentsWithTypes: {'one': 'int'});
   }
 
-  test_ArgumentList_imported_constructor_named_typed_param() async {
+  Future<void>
+      test_ArgumentList_imported_constructor_named_typed_param() async {
     // ArgumentList  InstanceCreationExpression  VariableDeclaration
     addSource('/home/test/lib/a.dart',
         'library libA; class A { A({int i, String s, d}) {} }}');
@@ -598,7 +603,7 @@
         namedArgumentsWithTypes: {'i': 'int', 's': 'String', 'd': 'dynamic'});
   }
 
-  test_ArgumentList_imported_factory_named_param() async {
+  Future<void> test_ArgumentList_imported_factory_named_param() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement
     addSource('/home/test/lib/a.dart',
         'library libA; class A{factory A({int one}) => null;}');
@@ -607,7 +612,7 @@
     assertSuggestArgumentsAndTypes(namedArgumentsWithTypes: {'one': 'int'});
   }
 
-  test_ArgumentList_imported_factory_named_param2() async {
+  Future<void> test_ArgumentList_imported_factory_named_param2() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement
     addSource('/home/test/lib/a.dart',
         'library libA; abstract class A{factory A.foo({int one});}');
@@ -616,7 +621,7 @@
     assertSuggestArgumentsAndTypes(namedArgumentsWithTypes: {'one': 'int'});
   }
 
-  test_ArgumentList_imported_factory_named_typed_param() async {
+  Future<void> test_ArgumentList_imported_factory_named_typed_param() async {
     // ArgumentList  InstanceCreationExpression  VariableDeclaration
     addSource('/home/test/lib/a.dart',
         'library libA; class A {factory A({int i, String s, d}) {} }}');
@@ -626,7 +631,7 @@
         namedArgumentsWithTypes: {'i': 'int', 's': 'String', 'd': 'dynamic'});
   }
 
-  test_ArgumentList_imported_function_0() async {
+  Future<void> test_ArgumentList_imported_function_0() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
       library A;
@@ -642,7 +647,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_imported_function_3a() async {
+  Future<void> test_ArgumentList_imported_function_3a() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
       library A;
@@ -658,7 +663,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_imported_function_3b() async {
+  Future<void> test_ArgumentList_imported_function_3b() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
       library A;
@@ -674,7 +679,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_imported_function_3c() async {
+  Future<void> test_ArgumentList_imported_function_3c() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
       library A;
@@ -690,7 +695,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_imported_function_3d() async {
+  Future<void> test_ArgumentList_imported_function_3d() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
       library A;
@@ -706,7 +711,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_imported_function_named_param() async {
+  Future<void> test_ArgumentList_imported_function_named_param() async {
     //
     addTestSource('main() { int.parse("16", ^);}');
     await computeSuggestions();
@@ -716,7 +721,7 @@
     });
   }
 
-  test_ArgumentList_imported_function_named_param1() async {
+  Future<void> test_ArgumentList_imported_function_named_param1() async {
     //
     addTestSource('main() { int.parse("16", r^);}');
     await computeSuggestions();
@@ -726,7 +731,7 @@
     });
   }
 
-  test_ArgumentList_imported_function_named_param2() async {
+  Future<void> test_ArgumentList_imported_function_named_param2() async {
     //
     addTestSource('main() { int.parse("16", radix: 7, ^);}');
     await computeSuggestions();
@@ -734,14 +739,14 @@
         namedArgumentsWithTypes: {'onError': 'int Function(String)'});
   }
 
-  test_ArgumentList_imported_function_named_param2a() async {
+  Future<void> test_ArgumentList_imported_function_named_param2a() async {
     //
     addTestSource('main() { int.parse("16", radix: ^);}');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_ArgumentList_imported_function_named_param_label1() async {
+  Future<void> test_ArgumentList_imported_function_named_param_label1() async {
     //
     addTestSource('main() { int.parse("16", r^: 16);}');
     await computeSuggestions();
@@ -751,14 +756,14 @@
     }, includeColon: false);
   }
 
-  test_ArgumentList_imported_function_named_param_label2() async {
+  Future<void> test_ArgumentList_imported_function_named_param_label2() async {
     //
     addTestSource('main() { int.parse("16", ^r: 16);}');
     await computeSuggestions();
     assertSuggestions(['radix: ,', 'onError: ,']);
   }
 
-  test_ArgumentList_imported_function_named_param_label3() async {
+  Future<void> test_ArgumentList_imported_function_named_param_label3() async {
     //
     addTestSource('main() { int.parse("16", ^: 16);}');
     await computeSuggestions();
@@ -768,7 +773,8 @@
     });
   }
 
-  test_ArgumentList_local_constructor_named_fieldFormal_documentation() async {
+  Future<void>
+      test_ArgumentList_local_constructor_named_fieldFormal_documentation() async {
     String content = '''
 class A {
   /// aaa
@@ -797,7 +803,8 @@
     expect(element.location.offset, content.indexOf('fff})'));
   }
 
-  test_ArgumentList_local_constructor_named_fieldFormal_noDocumentation() async {
+  Future<void>
+      test_ArgumentList_local_constructor_named_fieldFormal_noDocumentation() async {
     String content = '''
 class A {
   int fff;
@@ -822,7 +829,7 @@
     expect(element.location.offset, content.indexOf('fff})'));
   }
 
-  test_ArgumentList_local_constructor_named_param() async {
+  Future<void> test_ArgumentList_local_constructor_named_param() async {
     //
     addTestSource('''
 class A { A({int one, String two: 'defaultValue'}) { } }
@@ -835,7 +842,7 @@
         completion: 'one: ', selectionOffset: 5);
   }
 
-  test_ArgumentList_local_constructor_named_param_1() async {
+  Future<void> test_ArgumentList_local_constructor_named_param_1() async {
     //
     addTestSource('''
 class A { A({int one, String two: 'defaultValue'}) { } }
@@ -848,7 +855,7 @@
         completion: 'one: ', selectionOffset: 5);
   }
 
-  test_ArgumentList_local_constructor_named_param_2() async {
+  Future<void> test_ArgumentList_local_constructor_named_param_2() async {
     //
     addTestSource('''
 class A { A({int one, String two: 'defaultValue'}) { } }
@@ -861,7 +868,7 @@
         completion: 'one: ', selectionOffset: 5);
   }
 
-  test_ArgumentList_local_constructor_named_param_3() async {
+  Future<void> test_ArgumentList_local_constructor_named_param_3() async {
     //
     addTestSource('''
 class A { A({int one, String two: 'defaultValue'}) { } }
@@ -873,7 +880,7 @@
         completion: 'one: ', selectionOffset: 5);
   }
 
-  test_ArgumentList_local_constructor_named_param_4() async {
+  Future<void> test_ArgumentList_local_constructor_named_param_4() async {
     //
     addTestSource('''
 class A { A({int one, String two: 'defaultValue'}) { } }
@@ -885,7 +892,7 @@
         completion: 'one: ', selectionOffset: 5);
   }
 
-  test_ArgumentList_local_constructor_named_param_5() async {
+  Future<void> test_ArgumentList_local_constructor_named_param_5() async {
     //
     addTestSource('''
 class A { A({int one, String two: 'defaultValue'}) { } }
@@ -897,7 +904,7 @@
         completion: 'one: ', selectionOffset: 5);
   }
 
-  test_ArgumentList_local_constructor_named_param_6() async {
+  Future<void> test_ArgumentList_local_constructor_named_param_6() async {
     //
     addTestSource('''
 class A { A.foo({int one, String two: 'defaultValue'}) { } }
@@ -907,7 +914,8 @@
         namedArgumentsWithTypes: {'one': 'int', 'two': 'String'});
   }
 
-  test_ArgumentList_local_constructor_named_param_prefixed_prepend() async {
+  Future<void>
+      test_ArgumentList_local_constructor_named_param_prefixed_prepend() async {
     //
     addTestSource('''
 class A { A({int one, String two: 'defaultValue'}) { } }
@@ -920,7 +928,7 @@
         completion: 'one: ,', selectionOffset: 5);
   }
 
-  test_ArgumentList_local_constructor_named_param_prepend() async {
+  Future<void> test_ArgumentList_local_constructor_named_param_prepend() async {
     //
     addTestSource('''
 class A { A({int one, String two: 'defaultValue'}) { } }
@@ -933,7 +941,8 @@
         completion: 'one: ,', selectionOffset: 5);
   }
 
-  test_ArgumentList_local_constructor_named_param_prepend_1() async {
+  Future<void>
+      test_ArgumentList_local_constructor_named_param_prepend_1() async {
     //
     addTestSource('''
 class A { A({int one, String two: 'defaultValue'}) { } }
@@ -946,7 +955,8 @@
         completion: 'one: ', selectionOffset: 5);
   }
 
-  test_ArgumentList_local_constructor_named_param_prepend_2() async {
+  Future<void>
+      test_ArgumentList_local_constructor_named_param_prepend_2() async {
     //
     addTestSource('''
 class A { A({int one, String two: 'defaultValue'}) { } }
@@ -959,7 +969,7 @@
         completion: 'one: ', selectionOffset: 5);
   }
 
-  test_ArgumentList_local_constructor_required_param_0() async {
+  Future<void> test_ArgumentList_local_constructor_required_param_0() async {
     addMetaPackage();
     addTestSource('''
 import 'package:meta/meta.dart';
@@ -971,7 +981,7 @@
         requiredParamIndices: [1]);
   }
 
-  test_ArgumentList_local_function_3a() async {
+  Future<void> test_ArgumentList_local_function_3a() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addTestSource('''
       expect(arg1, int arg2, {bool arg3}) { }
@@ -982,7 +992,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_local_function_3b() async {
+  Future<void> test_ArgumentList_local_function_3b() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addTestSource('''
       expect(arg1, int arg2, {bool arg3}) { }
@@ -993,7 +1003,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_local_function_3c() async {
+  Future<void> test_ArgumentList_local_function_3c() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addTestSource('''
       expect(arg1, int arg2, {bool arg3}) { }
@@ -1004,7 +1014,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_local_function_3d() async {
+  Future<void> test_ArgumentList_local_function_3d() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addTestSource('''
       expect(arg1, int arg2, {bool arg3}) { }
@@ -1015,7 +1025,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_local_function_named_param() async {
+  Future<void> test_ArgumentList_local_function_named_param() async {
     //
     addTestSource('''
 f(v,{int radix, int onError(String s)}){}
@@ -1027,7 +1037,7 @@
     });
   }
 
-  test_ArgumentList_local_function_named_param1() async {
+  Future<void> test_ArgumentList_local_function_named_param1() async {
     //
     addTestSource('''
 f(v,{int radix, int onError(String s)}){}
@@ -1039,7 +1049,7 @@
     });
   }
 
-  test_ArgumentList_local_function_named_param2() async {
+  Future<void> test_ArgumentList_local_function_named_param2() async {
     //
     addTestSource('''
 f(v,{int radix, int onError(String s)}){}
@@ -1049,7 +1059,7 @@
         namedArgumentsWithTypes: {'onError': 'int Function(String)'});
   }
 
-  test_ArgumentList_local_function_named_param2a() async {
+  Future<void> test_ArgumentList_local_function_named_param2a() async {
     //
     addTestSource('''
 f(v,{int radix, int onError(String s)}){}
@@ -1058,7 +1068,7 @@
     assertNoSuggestions();
   }
 
-  test_ArgumentList_local_method_0() async {
+  Future<void> test_ArgumentList_local_method_0() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
       library A;
diff --git a/pkg/analysis_server/test/services/completion/dart/combinator_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/combinator_contributor_test.dart
index abd9c3d..04a362b 100644
--- a/pkg/analysis_server/test/services/completion/dart/combinator_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/combinator_contributor_test.dart
@@ -9,7 +9,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CombinatorContributorTest);
   });
@@ -22,7 +22,7 @@
     return CombinatorContributor();
   }
 
-  test_Block_inherited_local() async {
+  Future<void> test_Block_inherited_local() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     addTestSource('''
       class F { var f1; f2() { } }
@@ -34,7 +34,7 @@
     assertNoSuggestions();
   }
 
-  test_Combinator_hide() async {
+  Future<void> test_Combinator_hide() async {
     // SimpleIdentifier  HideCombinator  ImportDirective
     addSource('/home/test/lib/ab.dart', '''
       library libAB;
@@ -74,7 +74,7 @@
     assertNotSuggested('Object');
   }
 
-  test_Combinator_show() async {
+  Future<void> test_Combinator_show() async {
     // SimpleIdentifier  HideCombinator  ImportDirective
     addSource('/home/test/lib/ab.dart', '''
       library libAB;
@@ -123,7 +123,7 @@
     assertNotSuggested('Object');
   }
 
-  test_Combinator_show_export_withShow() async {
+  Future<void> test_Combinator_show_export_withShow() async {
     addSource('/home/test/lib/a.dart', r'''
 class A {}
 class B {}
@@ -141,14 +141,14 @@
     assertNotSuggested('B');
   }
 
-  test_Combinator_show_PI() async {
+  Future<void> test_Combinator_show_PI() async {
     addTestSource('import "dart:math" show ^;');
     await computeSuggestions();
     assertSuggestTopLevelVar('PI', 'double',
         kind: CompletionSuggestionKind.IDENTIFIER);
   }
 
-  test_Combinator_show_recursive() async {
+  Future<void> test_Combinator_show_recursive() async {
     addSource('/home/test/lib/a.dart', '''
 class A {}
 ''');
diff --git a/pkg/analysis_server/test/services/completion/dart/common_usage_sorter_test.dart b/pkg/analysis_server/test/services/completion/dart/common_usage_sorter_test.dart
index 91f0b7b..be5ab67 100644
--- a/pkg/analysis_server/test/services/completion/dart/common_usage_sorter_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/common_usage_sorter_test.dart
@@ -13,7 +13,7 @@
 
 import '../../../domain_completion_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CommonUsageSorterTest);
   });
@@ -32,7 +32,7 @@
     }
   }
 
-  test_ConstructorName() async {
+  Future<void> test_ConstructorName() async {
     // SimpleIdentifier  ConstructorName  InstanceCreationExpression
     addTestFile('import "dart:async"; class A {x() {new Future.^}}');
     await getSuggestionsWith({
@@ -48,7 +48,7 @@
     assertNoResult('A');
   }
 
-  test_namedArgument_enum() async {
+  Future<void> test_namedArgument_enum() async {
     addTestFile('''
 enum E {e1, e2}
 f({E e}) {}
@@ -66,7 +66,7 @@
         relevance: DART_RELEVANCE_DEFAULT + DART_RELEVANCE_BOOST_TYPE);
   }
 
-  test_PrefixedIdentifier_field() async {
+  Future<void> test_PrefixedIdentifier_field() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestFile('class A {static int s1; static int s2; x() {A.^}}');
     await getSuggestionsWith({
@@ -82,7 +82,7 @@
     assertNoResult('A');
   }
 
-  test_PrefixedIdentifier_field_inPart() async {
+  Future<void> test_PrefixedIdentifier_field_inPart() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     newFile('/project/bin/myLib.dart',
         content:
@@ -100,7 +100,7 @@
     assertNoResult('A');
   }
 
-  test_PrefixedIdentifier_getter() async {
+  Future<void> test_PrefixedIdentifier_getter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestFile('class A {int get g1 => 1; int get g2 => 2; x() {new A().^}}');
     await getSuggestionsWith({
@@ -116,7 +116,7 @@
     assertNoResult('A');
   }
 
-  test_PrefixedIdentifier_setter() async {
+  Future<void> test_PrefixedIdentifier_setter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestFile('class A {set s1(v) {}; set s2(v) {}; x() {new A().^}}');
     await getSuggestionsWith({
@@ -132,7 +132,7 @@
     assertNoResult('A');
   }
 
-  test_PrefixedIdentifier_static_method() async {
+  Future<void> test_PrefixedIdentifier_static_method() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestFile('import "dart:async"; class A {x() {Future.^}}');
     await getSuggestionsWith({
@@ -147,7 +147,7 @@
     assertNoResult('A');
   }
 
-  test_PropertyAccess() async {
+  Future<void> test_PropertyAccess() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement
     addTestFile('import "dart:math"; class A {x() {new Random().^}}');
     await getSuggestionsWith({
diff --git a/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart b/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart
index f1b65fe..683d884 100644
--- a/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart
+++ b/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart
@@ -87,7 +87,7 @@
   }
 
   @override
-  setUp() {
+  void setUp() {
     super.setUp();
     completionManager = DartCompletionManager();
   }
diff --git a/pkg/analysis_server/test/services/completion/dart/completion_manager_test.dart b/pkg/analysis_server/test/services/completion/dart/completion_manager_test.dart
index 293acc2..baf3dde 100644
--- a/pkg/analysis_server/test/services/completion/dart/completion_manager_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/completion_manager_test.dart
@@ -15,7 +15,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CompletionManagerTest);
   });
@@ -28,7 +28,7 @@
     return ImportedReferenceContributor();
   }
 
-  test_resolveDirectives() async {
+  Future<void> test_resolveDirectives() async {
     addSource('/home/test/lib/a.dart', '''
 library libA;
 /// My class.
diff --git a/pkg/analysis_server/test/services/completion/dart/extension_member_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/extension_member_contributor_test.dart
index 4b38249..2d8bfc3 100644
--- a/pkg/analysis_server/test/services/completion/dart/extension_member_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/extension_member_contributor_test.dart
@@ -8,7 +8,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ExtensionMemberContributorTest);
   });
@@ -27,7 +27,7 @@
     super.setUp();
   }
 
-  test_extension() async {
+  Future<void> test_extension() async {
     addTestSource('''
 extension E on int {}
 void f() {
@@ -38,7 +38,7 @@
     assertNoSuggestions();
   }
 
-  test_extensionOverride_doesNotMatch() async {
+  Future<void> test_extensionOverride_doesNotMatch() async {
     addTestSource('''
 extension E on int {
   bool a(int b, int c) {}
@@ -55,7 +55,7 @@
     assertSuggestSetter('c');
   }
 
-  test_extensionOverride_matches() async {
+  Future<void> test_extensionOverride_matches() async {
     addTestSource('''
 extension E on int {
   bool a(int b, int c) {}
@@ -72,7 +72,7 @@
     assertSuggestSetter('c');
   }
 
-  test_function_doesNotMatch() async {
+  Future<void> test_function_doesNotMatch() async {
     addTestSource('''
 extension E<T extends num> on List<T> {
   bool a(int b, int c) {}
@@ -90,7 +90,7 @@
     assertNotSuggested('c');
   }
 
-  test_function_matches() async {
+  Future<void> test_function_matches() async {
     addTestSource('''
 extension E on int {
   bool a(int b, int c) {}
@@ -108,7 +108,7 @@
     assertSuggestSetter('c');
   }
 
-  test_identifier_doesNotMatch() async {
+  Future<void> test_identifier_doesNotMatch() async {
     addTestSource('''
 extension E<T extends num> on List<T> {
   bool a(int b, int c) {}
@@ -125,7 +125,7 @@
     assertNotSuggested('c');
   }
 
-  test_identifier_matches() async {
+  Future<void> test_identifier_matches() async {
     addTestSource('''
 extension E<T extends num> on List<T> {
   bool a(int b, int c) {}
@@ -142,7 +142,7 @@
     assertSuggestSetter('c');
   }
 
-  test_literal_doesNotMatch() async {
+  Future<void> test_literal_doesNotMatch() async {
     addTestSource('''
 extension E on String {
   bool a(int b, int c) {}
@@ -160,7 +160,7 @@
     assertNotSuggested('c');
   }
 
-  test_literal_doesNotMatch_generic() async {
+  Future<void> test_literal_doesNotMatch_generic() async {
     addTestSource('''
 extension E<T extends num> on List<T> {
   bool a(int b, int c) {}
@@ -177,7 +177,7 @@
     assertNotSuggested('c');
   }
 
-  test_literal_matches() async {
+  Future<void> test_literal_matches() async {
     addTestSource('''
 extension E on int {
   bool a(int b, int c) {}
@@ -194,7 +194,7 @@
     assertSuggestSetter('c');
   }
 
-  test_members_inExtendedClassMethod_getter() async {
+  Future<void> test_members_inExtendedClassMethod_getter() async {
     addTestSource('''
 class Person {
   void doSomething() {
@@ -211,7 +211,7 @@
     assertSuggestGetter('name', 'String');
   }
 
-  test_members_inExtendedClassMethod_method() async {
+  Future<void> test_members_inExtendedClassMethod_method() async {
     addTestSource('''
 class Person {
   void doSomething() {
@@ -228,7 +228,7 @@
     assertSuggestMethod('work', null, 'void');
   }
 
-  test_members_inExtendedClassMethod_multipleExtensions() async {
+  Future<void> test_members_inExtendedClassMethod_multipleExtensions() async {
     addTestSource('''
 class Person {
   void doSomething() {
@@ -249,7 +249,7 @@
     assertSuggestMethod('work', null, 'void');
   }
 
-  test_members_inExtendedClassMethod_setter() async {
+  Future<void> test_members_inExtendedClassMethod_setter() async {
     addTestSource('''
 class Person {
   void doSomething() {
@@ -266,7 +266,7 @@
     assertSuggestSetter('id');
   }
 
-  test_members_inMixinMethod_method() async {
+  Future<void> test_members_inMixinMethod_method() async {
     addTestSource('''
 class Person { }
 extension E on Person {
@@ -283,7 +283,7 @@
     assertSuggestMethod('work', null, 'void');
   }
 
-  test_members_with_this_inExtendedClass() async {
+  Future<void> test_members_with_this_inExtendedClass() async {
     addTestSource('''
 class Person {
   void doSomething() {
diff --git a/pkg/analysis_server/test/services/completion/dart/field_formal_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/field_formal_contributor_test.dart
index 621ecd0..9c45414 100644
--- a/pkg/analysis_server/test/services/completion/dart/field_formal_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/field_formal_contributor_test.dart
@@ -9,7 +9,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FieldFormalContributorTest);
   });
@@ -23,7 +23,7 @@
   }
 
   /// https://github.com/dart-lang/sdk/issues/39028
-  test_mixin_constructor() async {
+  Future<void> test_mixin_constructor() async {
     addTestSource('''
 mixin M {
   M(this.^);
@@ -33,7 +33,7 @@
     expect(suggestions, isEmpty);
   }
 
-  test_ThisExpression_constructor_param() async {
+  Future<void> test_ThisExpression_constructor_param() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -69,7 +69,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param2() async {
+  Future<void> test_ThisExpression_constructor_param2() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -104,7 +104,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param3() async {
+  Future<void> test_ThisExpression_constructor_param3() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -139,7 +139,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param4() async {
+  Future<void> test_ThisExpression_constructor_param4() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -174,7 +174,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param_optional() async {
+  Future<void> test_ThisExpression_constructor_param_optional() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -190,7 +190,7 @@
     assertNotSuggested('x');
   }
 
-  test_ThisExpression_constructor_param_positional() async {
+  Future<void> test_ThisExpression_constructor_param_positional() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
diff --git a/pkg/analysis_server/test/services/completion/dart/imported_reference_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/imported_reference_contributor_test.dart
index bd26c3c..92c0042 100644
--- a/pkg/analysis_server/test/services/completion/dart/imported_reference_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/imported_reference_contributor_test.dart
@@ -10,7 +10,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ImportedReferenceContributorTest);
   });
@@ -27,7 +27,7 @@
   }
 
   /// Sanity check.  Permutations tested in local_ref_contributor.
-  test_ArgDefaults_function_with_required_named() async {
+  Future<void> test_ArgDefaults_function_with_required_named() async {
     addMetaPackage();
 
     resolveSource('/home/test/lib/b.dart', '''
@@ -47,7 +47,7 @@
         defaultArgListString: 'bar, baz: null');
   }
 
-  test_ArgumentList() async {
+  Future<void> test_ArgumentList() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     resolveSource('/home/test/lib/a.dart', '''
         library A;
@@ -72,7 +72,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_imported_function() async {
+  Future<void> test_ArgumentList_imported_function() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     resolveSource('/home/test/lib/a.dart', '''
         library A;
@@ -98,7 +98,8 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_InstanceCreationExpression_functionalArg() async {
+  Future<void>
+      test_ArgumentList_InstanceCreationExpression_functionalArg() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -128,7 +129,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_InstanceCreationExpression_typedefArg() async {
+  Future<void> test_ArgumentList_InstanceCreationExpression_typedefArg() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -159,7 +160,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_local_function() async {
+  Future<void> test_ArgumentList_local_function() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     resolveSource('/home/test/lib/a.dart', '''
         library A;
@@ -185,7 +186,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_local_method() async {
+  Future<void> test_ArgumentList_local_method() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     resolveSource('/home/test/lib/a.dart', '''
         library A;
@@ -211,7 +212,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_MethodInvocation_functionalArg() async {
+  Future<void> test_ArgumentList_MethodInvocation_functionalArg() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -241,7 +242,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_MethodInvocation_methodArg() async {
+  Future<void> test_ArgumentList_MethodInvocation_methodArg() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -269,7 +270,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_namedParam() async {
+  Future<void> test_ArgumentList_namedParam() async {
     // SimpleIdentifier  NamedExpression  ArgumentList  MethodInvocation
     // ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
@@ -293,7 +294,7 @@
     assertNotSuggested('main');
   }
 
-  test_AsExpression() async {
+  Future<void> test_AsExpression() async {
     // SimpleIdentifier  TypeName  AsExpression
     addTestSource('''
         class A {var b; X _c; foo() {var a; (a as ^).foo();}''');
@@ -308,7 +309,7 @@
     assertNotSuggested('==');
   }
 
-  test_AsExpression_type_subtype_extends_filter() async {
+  Future<void> test_AsExpression_type_subtype_extends_filter() async {
     // SimpleIdentifier  TypeName  AsExpression  IfStatement
     addSource('/home/test/lib/b.dart', '''
           foo() { }
@@ -330,7 +331,7 @@
     assertNotSuggested('main');
   }
 
-  test_AsExpression_type_subtype_implements_filter() async {
+  Future<void> test_AsExpression_type_subtype_implements_filter() async {
     // SimpleIdentifier  TypeName  AsExpression  IfStatement
     addSource('/home/test/lib/b.dart', '''
           foo() { }
@@ -352,7 +353,7 @@
     assertNotSuggested('main');
   }
 
-  test_AssignmentExpression_name() async {
+  Future<void> test_AssignmentExpression_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('class A {} main() {int a; int ^b = 1;}');
@@ -361,7 +362,7 @@
     assertNoSuggestions();
   }
 
-  test_AssignmentExpression_RHS() async {
+  Future<void> test_AssignmentExpression_RHS() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('class A {} main() {int a; int b = ^}');
@@ -375,7 +376,7 @@
     assertSuggestClass('Object');
   }
 
-  test_AssignmentExpression_type() async {
+  Future<void> test_AssignmentExpression_type() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -398,7 +399,7 @@
     //assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_newline() async {
+  Future<void> test_AssignmentExpression_type_newline() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -420,7 +421,7 @@
     assertSuggestFunction('identical', 'bool');
   }
 
-  test_AssignmentExpression_type_partial() async {
+  Future<void> test_AssignmentExpression_type_partial() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -443,7 +444,7 @@
     //assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_partial_newline() async {
+  Future<void> test_AssignmentExpression_type_partial_newline() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -465,7 +466,7 @@
     assertSuggestFunction('identical', 'bool');
   }
 
-  test_AwaitExpression() async {
+  Future<void> test_AwaitExpression() async {
     // SimpleIdentifier  AwaitExpression  ExpressionStatement
     addTestSource('''
         class A {int x; int y() => 0;}
@@ -480,7 +481,7 @@
     assertSuggestClass('Object');
   }
 
-  test_AwaitExpression_function() async {
+  Future<void> test_AwaitExpression_function() async {
     resolveSource('/home/test/lib/a.dart', '''
 Future y() async {return 0;}
 ''');
@@ -499,7 +500,7 @@
     assertSuggestClass('Object');
   }
 
-  test_AwaitExpression_inherited() async {
+  Future<void> test_AwaitExpression_inherited() async {
     // SimpleIdentifier  AwaitExpression  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
 lib libB;
@@ -526,7 +527,7 @@
     assertNotSuggested('y');
   }
 
-  test_BinaryExpression_LHS() async {
+  Future<void> test_BinaryExpression_LHS() async {
     // SimpleIdentifier  BinaryExpression  VariableDeclaration
     // VariableDeclarationList  VariableDeclarationStatement
     addTestSource('main() {int a = 1, b = ^ + 2;}');
@@ -539,7 +540,7 @@
     assertNotSuggested('b');
   }
 
-  test_BinaryExpression_RHS() async {
+  Future<void> test_BinaryExpression_RHS() async {
     // SimpleIdentifier  BinaryExpression  VariableDeclaration
     // VariableDeclarationList  VariableDeclarationStatement
     addTestSource('main() {int a = 1, b = 2 + ^;}');
@@ -553,7 +554,7 @@
     assertNotSuggested('==');
   }
 
-  test_Block() async {
+  Future<void> test_Block() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/ab.dart', '''
         export "dart:math" hide max;
@@ -656,7 +657,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final() async {
+  Future<void> test_Block_final() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/ab.dart', '''
         export "dart:math" hide max;
@@ -755,21 +756,21 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final2() async {
+  Future<void> test_Block_final2() async {
     addTestSource('main() {final S^ v;}');
 
     await computeSuggestions();
     assertSuggestClass('String');
   }
 
-  test_Block_final3() async {
+  Future<void> test_Block_final3() async {
     addTestSource('main() {final ^ v;}');
 
     await computeSuggestions();
     assertSuggestClass('String');
   }
 
-  test_Block_final_final() async {
+  Future<void> test_Block_final_final() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/ab.dart', '''
         export "dart:math" hide max;
@@ -870,7 +871,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final_var() async {
+  Future<void> test_Block_final_var() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/ab.dart', '''
         export "dart:math" hide max;
@@ -969,7 +970,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_identifier_partial() async {
+  Future<void> test_Block_identifier_partial() async {
     resolveSource('/home/test/lib/ab.dart', '''
         export "dart:math" hide max;
         class A {int x;}
@@ -1046,7 +1047,7 @@
     assertNotSuggested('HtmlElement');
   }
 
-  test_Block_inherited_imported() async {
+  Future<void> test_Block_inherited_imported() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -1077,7 +1078,7 @@
     assertNotSuggested('==');
   }
 
-  test_Block_inherited_local() async {
+  Future<void> test_Block_inherited_local() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     addTestSource('''
         class F { var f1; f2() { } get f3 => 0; set f4(fx) { } }
@@ -1101,7 +1102,7 @@
     assertNotSuggested('m2');
   }
 
-  test_Block_local_function() async {
+  Future<void> test_Block_local_function() async {
     addSource('/home/test/lib/ab.dart', '''
         export "dart:math" hide max;
         class A {int x;}
@@ -1152,7 +1153,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_partial_results() async {
+  Future<void> test_Block_partial_results() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/ab.dart', '''
         export "dart:math" hide max;
@@ -1190,7 +1191,7 @@
     assertNotSuggested('H');
   }
 
-  test_Block_unimported() async {
+  Future<void> test_Block_unimported() async {
     addPackageFile('aaa', 'a.dart', 'class A {}');
     addTestSource('main() { ^ }');
 
@@ -1203,7 +1204,7 @@
     assertNotSuggested('Completer');
   }
 
-  test_CascadeExpression_selector1() async {
+  Future<void> test_CascadeExpression_selector1() async {
     // PropertyAccess  CascadeExpression  ExpressionStatement  Block
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1228,7 +1229,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_selector2() async {
+  Future<void> test_CascadeExpression_selector2() async {
     // SimpleIdentifier  PropertyAccess  CascadeExpression  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1251,7 +1252,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_selector2_withTrailingReturn() async {
+  Future<void> test_CascadeExpression_selector2_withTrailingReturn() async {
     // PropertyAccess  CascadeExpression  ExpressionStatement  Block
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1274,7 +1275,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_target() async {
+  Future<void> test_CascadeExpression_target() async {
     // SimpleIdentifier  CascadeExpression  ExpressionStatement
     addTestSource('''
         class A {var b; X _c;}
@@ -1294,7 +1295,7 @@
     assertNotSuggested('==');
   }
 
-  test_CatchClause_onType() async {
+  Future<void> test_CatchClause_onType() async {
     // TypeName  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on ^ {}}}');
 
@@ -1307,7 +1308,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_onType_noBrackets() async {
+  Future<void> test_CatchClause_onType_noBrackets() async {
     // TypeName  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on ^}}');
 
@@ -1319,7 +1320,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_typed() async {
+  Future<void> test_CatchClause_typed() async {
     // Block  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on E catch (e) {^}}}');
 
@@ -1332,7 +1333,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_untyped() async {
+  Future<void> test_CatchClause_untyped() async {
     // Block  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} catch (e, s) {^}}}');
 
@@ -1346,7 +1347,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body() async {
+  Future<void> test_ClassDeclaration_body() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1371,7 +1372,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final() async {
+  Future<void> test_ClassDeclaration_body_final() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1392,7 +1393,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_field() async {
+  Future<void> test_ClassDeclaration_body_final_field() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1413,7 +1414,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_field2() async {
+  Future<void> test_ClassDeclaration_body_final_field2() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1434,7 +1435,7 @@
     assertNotSuggested('Soo');
   }
 
-  test_ClassDeclaration_body_final_final() async {
+  Future<void> test_ClassDeclaration_body_final_final() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1455,7 +1456,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_var() async {
+  Future<void> test_ClassDeclaration_body_final_var() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1476,7 +1477,7 @@
     assertNotSuggested('x');
   }
 
-  test_Combinator_hide() async {
+  Future<void> test_Combinator_hide() async {
     // SimpleIdentifier  HideCombinator  ImportDirective
     addSource('/home/test/lib/ab.dart', '''
         library libAB;
@@ -1500,7 +1501,7 @@
     assertNoSuggestions();
   }
 
-  test_Combinator_show() async {
+  Future<void> test_Combinator_show() async {
     // SimpleIdentifier  HideCombinator  ImportDirective
     addSource('/home/test/lib/ab.dart', '''
         library libAB;
@@ -1526,7 +1527,7 @@
     assertNoSuggestions();
   }
 
-  test_ConditionalExpression_elseExpression() async {
+  Future<void> test_ConditionalExpression_elseExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1546,7 +1547,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_ConditionalExpression_elseExpression_empty() async {
+  Future<void> test_ConditionalExpression_elseExpression_empty() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1575,7 +1576,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_ConditionalExpression_partial_thenExpression() async {
+  Future<void> test_ConditionalExpression_partial_thenExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1595,7 +1596,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_ConditionalExpression_partial_thenExpression_empty() async {
+  Future<void> test_ConditionalExpression_partial_thenExpression_empty() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1624,7 +1625,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_ConditionalExpression_thenExpression() async {
+  Future<void> test_ConditionalExpression_thenExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1644,7 +1645,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_ConstructorName_importedClass() async {
+  Future<void> test_ConstructorName_importedClass() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -1669,7 +1670,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedFactory() async {
+  Future<void> test_ConstructorName_importedFactory() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -1694,7 +1695,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedFactory2() async {
+  Future<void> test_ConstructorName_importedFactory2() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -1712,7 +1713,7 @@
     assertNotSuggested('String');
   }
 
-  test_ConstructorName_localClass() async {
+  Future<void> test_ConstructorName_localClass() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -1733,7 +1734,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_localFactory() async {
+  Future<void> test_ConstructorName_localFactory() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -1754,7 +1755,7 @@
     assertNotSuggested('m');
   }
 
-  test_DefaultFormalParameter_named_expression() async {
+  Future<void> test_DefaultFormalParameter_named_expression() async {
     // DefaultFormalParameter FormalParameterList MethodDeclaration
     addTestSource('''
         foo() { }
@@ -1772,7 +1773,7 @@
     assertNotSuggested('bar');
   }
 
-  test_doc_class() async {
+  Future<void> test_doc_class() async {
     addSource('/home/test/lib/a.dart', r'''
 library A;
 /// My class.
@@ -1794,7 +1795,7 @@
     }
   }
 
-  test_doc_function() async {
+  Future<void> test_doc_function() async {
     resolveSource('/home/test/lib/a.dart', r'''
 library A;
 /// My function.
@@ -1813,7 +1814,7 @@
         'My function.\nShort description.\n\nLonger description.');
   }
 
-  test_doc_function_c_style() async {
+  Future<void> test_doc_function_c_style() async {
     resolveSource('/home/test/lib/a.dart', r'''
 library A;
 /**
@@ -1834,7 +1835,7 @@
         'My function.\nShort description.\n\nLonger description.');
   }
 
-  test_enum() async {
+  Future<void> test_enum() async {
     addSource('/home/test/lib/a.dart', 'library A; enum E { one, two }');
     addTestSource('import "a.dart"; main() {^}');
     await computeSuggestions();
@@ -1843,7 +1844,7 @@
     assertNotSuggested('two');
   }
 
-  test_enum_deprecated() async {
+  Future<void> test_enum_deprecated() async {
     addSource(
         '/home/test/lib/a.dart', 'library A; @deprecated enum E { one, two }');
     addTestSource('import "a.dart"; main() {^}');
@@ -1855,7 +1856,7 @@
     assertNotSuggested('two');
   }
 
-  test_enum_filter() async {
+  Future<void> test_enum_filter() async {
     addSource('/home/test/lib/a.dart', '''
 enum E { one, two }
 enum F { three, four }
@@ -1880,7 +1881,7 @@
     assertSuggestEnumConst('F.four');
   }
 
-  test_ExpressionStatement_identifier() async {
+  Future<void> test_ExpressionStatement_identifier() async {
     // SimpleIdentifier  ExpressionStatement  Block
     resolveSource('/home/test/lib/a.dart', '''
         _B F1() { }
@@ -1910,7 +1911,7 @@
     assertNotSuggested('_B');
   }
 
-  test_ExpressionStatement_name() async {
+  Future<void> test_ExpressionStatement_name() async {
     // ExpressionStatement  Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/a.dart', '''
         B T1;
@@ -1923,7 +1924,7 @@
     assertNoSuggestions();
   }
 
-  test_extendsClause() async {
+  Future<void> test_extendsClause() async {
     newFile('/home/test/lib/a.dart', content: 'class A {}');
     addTestSource('''
 import 'a.dart';
@@ -1934,7 +1935,7 @@
     assertSuggestClass('A');
   }
 
-  test_FieldDeclaration_name_typed() async {
+  Future<void> test_FieldDeclaration_name_typed() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // FieldDeclaration
     addSource('/home/test/lib/a.dart', 'class A { }');
@@ -1946,7 +1947,7 @@
     assertNoSuggestions();
   }
 
-  test_FieldDeclaration_name_var() async {
+  Future<void> test_FieldDeclaration_name_var() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // FieldDeclaration
     addSource('/home/test/lib/a.dart', 'class A { }');
@@ -1958,7 +1959,7 @@
     assertNoSuggestions();
   }
 
-  test_FieldFormalParameter_in_non_constructor() async {
+  Future<void> test_FieldFormalParameter_in_non_constructor() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('class A {B(this.^foo) {}}');
     await computeSuggestions();
@@ -1967,7 +1968,7 @@
     assertNoSuggestions();
   }
 
-  test_ForEachStatement_body_typed() async {
+  Future<void> test_ForEachStatement_body_typed() async {
     // Block  ForEachStatement
     addTestSource('main(args) {for (int foo in bar) {^}}');
 
@@ -1979,7 +1980,7 @@
     assertSuggestClass('Object');
   }
 
-  test_ForEachStatement_body_untyped() async {
+  Future<void> test_ForEachStatement_body_untyped() async {
     // Block  ForEachStatement
     addTestSource('main(args) {for (foo in bar) {^}}');
 
@@ -1991,7 +1992,7 @@
     assertSuggestClass('Object');
   }
 
-  test_ForEachStatement_iterable() async {
+  Future<void> test_ForEachStatement_iterable() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (int foo in ^) {}}');
 
@@ -2002,7 +2003,7 @@
     assertSuggestClass('Object');
   }
 
-  test_ForEachStatement_loopVariable() async {
+  Future<void> test_ForEachStatement_loopVariable() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (^ in args) {}}');
 
@@ -2013,7 +2014,7 @@
     assertSuggestClass('String');
   }
 
-  test_ForEachStatement_loopVariable_type() async {
+  Future<void> test_ForEachStatement_loopVariable_type() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (^ foo in args) {}}');
 
@@ -2025,7 +2026,7 @@
     assertSuggestClass('String');
   }
 
-  test_ForEachStatement_loopVariable_type2() async {
+  Future<void> test_ForEachStatement_loopVariable_type2() async {
     // DeclaredIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (S^ foo in args) {}}');
 
@@ -2037,7 +2038,7 @@
     assertSuggestClass('String');
   }
 
-  test_FormalParameterList() async {
+  Future<void> test_FormalParameterList() async {
     // FormalParameterList MethodDeclaration
     addTestSource('''
         foo() { }
@@ -2055,7 +2056,7 @@
     assertNotSuggested('bar');
   }
 
-  test_ForStatement_body() async {
+  Future<void> test_ForStatement_body() async {
     // Block  ForStatement
     addTestSource('main(args) {for (int i; i < 10; ++i) {^}}');
 
@@ -2066,7 +2067,7 @@
     assertSuggestClass('Object');
   }
 
-  test_ForStatement_condition() async {
+  Future<void> test_ForStatement_condition() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {for (int index = 0; i^)}');
 
@@ -2076,7 +2077,7 @@
     assertNotSuggested('index');
   }
 
-  test_ForStatement_initializer() async {
+  Future<void> test_ForStatement_initializer() async {
     addTestSource('''
 import 'dart:math';
 main() {
@@ -2094,19 +2095,19 @@
     assertSuggestClass('int');
   }
 
-  test_ForStatement_initializer_variableName_afterType() async {
+  Future<void> test_ForStatement_initializer_variableName_afterType() async {
     addTestSource('main() { for (String ^) }');
     await computeSuggestions();
     assertNotSuggested('int');
   }
 
-  test_ForStatement_typing_inKeyword() async {
+  Future<void> test_ForStatement_typing_inKeyword() async {
     addTestSource('main() { for (var v i^) }');
     await computeSuggestions();
     assertNotSuggested('int');
   }
 
-  test_ForStatement_updaters() async {
+  Future<void> test_ForStatement_updaters() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {for (int index = 0; index < 10; i^)}');
 
@@ -2116,7 +2117,7 @@
     assertNotSuggested('index');
   }
 
-  test_ForStatement_updaters_prefix_expression() async {
+  Future<void> test_ForStatement_updaters_prefix_expression() async {
     // SimpleIdentifier  PrefixExpression  ForStatement
     addTestSource('''
         void bar() { }
@@ -2130,7 +2131,7 @@
     assertNotSuggested('bar');
   }
 
-  test_function_parameters_mixed_required_and_named() async {
+  Future<void> test_function_parameters_mixed_required_and_named() async {
     resolveSource('/home/test/lib/a.dart', '''
 int m(x, {int y}) {}
 ''');
@@ -2151,7 +2152,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_function_parameters_mixed_required_and_positional() async {
+  Future<void> test_function_parameters_mixed_required_and_positional() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m(x, [int y]) {}
 ''');
@@ -2172,7 +2173,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_function_parameters_named() async {
+  Future<void> test_function_parameters_named() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m({x, int y}) {}
 ''');
@@ -2193,7 +2194,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_function_parameters_none() async {
+  Future<void> test_function_parameters_none() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m() {}
 ''');
@@ -2212,7 +2213,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_function_parameters_positional() async {
+  Future<void> test_function_parameters_positional() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m([x, int y]) {}
 ''');
@@ -2233,7 +2234,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_function_parameters_required() async {
+  Future<void> test_function_parameters_required() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m(x, int y) {}
 ''');
@@ -2254,7 +2255,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_FunctionDeclaration_returnType_afterComment() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment() async {
     // ClassDeclaration  CompilationUnit
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2284,7 +2285,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionDeclaration_returnType_afterComment2() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment2() async {
     // FunctionDeclaration  ClassDeclaration  CompilationUnit
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2314,7 +2315,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionDeclaration_returnType_afterComment3() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment3() async {
     // FunctionDeclaration  ClassDeclaration  CompilationUnit
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2345,7 +2346,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionExpression_body_function() async {
+  Future<void> test_FunctionExpression_body_function() async {
     // Block  BlockFunctionBody  FunctionExpression
     addTestSource('''
         void bar() { }
@@ -2361,7 +2362,7 @@
     assertSuggestClass('Object');
   }
 
-  test_functionTypeAlias_genericTypeAlias() async {
+  Future<void> test_functionTypeAlias_genericTypeAlias() async {
     addSource('/home/test/lib/a.dart', r'''
 typedef F = void Function();
 ''');
@@ -2376,7 +2377,7 @@
     assertSuggestFunctionTypeAlias('F', 'void');
   }
 
-  test_functionTypeAlias_old() async {
+  Future<void> test_functionTypeAlias_old() async {
     addSource('/home/test/lib/a.dart', r'''
 typedef void F();
 ''');
@@ -2391,7 +2392,7 @@
     assertSuggestFunctionTypeAlias('F', 'void');
   }
 
-  test_IfStatement() async {
+  Future<void> test_IfStatement() async {
     // SimpleIdentifier  IfStatement
     addTestSource('''
         class A {var b; X _c; foo() {A a; if (true) ^}}''');
@@ -2406,7 +2407,7 @@
     assertNotSuggested('==');
   }
 
-  test_IfStatement_condition() async {
+  Future<void> test_IfStatement_condition() async {
     // SimpleIdentifier  IfStatement  Block  BlockFunctionBody
     addTestSource('''
         class A {int x; int y() => 0;}
@@ -2421,7 +2422,7 @@
     assertSuggestClass('Object');
   }
 
-  test_IfStatement_empty() async {
+  Future<void> test_IfStatement_empty() async {
     // SimpleIdentifier  IfStatement
     addTestSource('''
         class A {var b; X _c; foo() {A a; if (^) something}}''');
@@ -2436,7 +2437,7 @@
     assertNotSuggested('==');
   }
 
-  test_IfStatement_invocation() async {
+  Future<void> test_IfStatement_invocation() async {
     // SimpleIdentifier  PrefixIdentifier  IfStatement
     addTestSource('''
         main() {var a; if (a.^) something}''');
@@ -2450,13 +2451,13 @@
     assertNotSuggested('==');
   }
 
-  test_IfStatement_typing_isKeyword() async {
+  Future<void> test_IfStatement_typing_isKeyword() async {
     addTestSource('main() { if (v i^) }');
     await computeSuggestions();
     assertNotSuggested('int');
   }
 
-  test_implementsClause() async {
+  Future<void> test_implementsClause() async {
     newFile('/home/test/lib/a.dart', content: 'class A {}');
     addTestSource('''
 import 'a.dart';
@@ -2467,7 +2468,7 @@
     assertSuggestClass('A');
   }
 
-  test_implicitCreation() async {
+  Future<void> test_implicitCreation() async {
     addSource('/home/test/lib/a.dart', '''
 class A {
   A.a1();
@@ -2496,7 +2497,7 @@
     assertSuggestConstructor('B.b2');
   }
 
-  test_ImportDirective_dart() async {
+  Future<void> test_ImportDirective_dart() async {
     // SimpleStringLiteral  ImportDirective
     addTestSource('''
         import "dart^";
@@ -2506,7 +2507,7 @@
     assertNoSuggestions();
   }
 
-  test_IndexExpression() async {
+  Future<void> test_IndexExpression() async {
     // ExpressionStatement  Block
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2535,7 +2536,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_IndexExpression2() async {
+  Future<void> test_IndexExpression2() async {
     // SimpleIdentifier IndexExpression ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2555,7 +2556,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_InstanceCreationExpression() async {
+  Future<void> test_InstanceCreationExpression() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {foo(){var f; {var x;}}}
 class B {B(this.x, [String boo]) { } int x;}
@@ -2604,7 +2605,7 @@
     assertNotSuggested('math');
   }
 
-  test_InstanceCreationExpression_abstractClass() async {
+  Future<void> test_InstanceCreationExpression_abstractClass() async {
     addSource('/home/test/lib/a.dart', '''
 abstract class A {
   A();
@@ -2626,7 +2627,8 @@
     assertSuggestConstructor('A.factory');
   }
 
-  test_InstanceCreationExpression_abstractClass_implicitConstructor() async {
+  Future<void>
+      test_InstanceCreationExpression_abstractClass_implicitConstructor() async {
     addSource('/home/test/lib/a.dart', '''
 abstract class A {}
 ''');
@@ -2642,7 +2644,7 @@
     assertNotSuggested('A');
   }
 
-  test_InstanceCreationExpression_filter() async {
+  Future<void> test_InstanceCreationExpression_filter() async {
     addSource('/home/test/lib/a.dart', '''
 class A {}
 class B extends A {}
@@ -2670,7 +2672,7 @@
     assertSuggestConstructor('D', elemOffset: -1);
   }
 
-  test_InstanceCreationExpression_imported() async {
+  Future<void> test_InstanceCreationExpression_imported() async {
     // SimpleIdentifier  TypeName  ConstructorName  InstanceCreationExpression
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2713,7 +2715,7 @@
     assertNotSuggested('T2');
   }
 
-  test_InstanceCreationExpression_unimported() async {
+  Future<void> test_InstanceCreationExpression_unimported() async {
     // SimpleIdentifier  TypeName  ConstructorName  InstanceCreationExpression
     addSource('/home/test/lib/ab.dart', 'class Clip { }');
     addTestSource('class A {foo(){new C^}}');
@@ -2726,7 +2728,7 @@
     assertNotSuggested('Clip');
   }
 
-  test_internal_sdk_libs() async {
+  Future<void> test_internal_sdk_libs() async {
     addTestSource('main() {p^}');
 
     await computeSuggestions();
@@ -2737,7 +2739,7 @@
     assertNotSuggested('printToConsole');
   }
 
-  test_InterpolationExpression() async {
+  Future<void> test_InterpolationExpression() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2772,7 +2774,7 @@
     assertNotSuggested('name');
   }
 
-  test_InterpolationExpression_block() async {
+  Future<void> test_InterpolationExpression_block() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2804,7 +2806,7 @@
     assertNotSuggested('name');
   }
 
-  test_InterpolationExpression_block2() async {
+  Future<void> test_InterpolationExpression_block2() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addTestSource('main() {String name; print("hello \${n^}");}');
 
@@ -2814,7 +2816,7 @@
     //assertSuggestClass('Object');
   }
 
-  test_InterpolationExpression_prefix_selector() async {
+  Future<void> test_InterpolationExpression_prefix_selector() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \${name.^}");}');
 
@@ -2827,7 +2829,7 @@
     assertNotSuggested('==');
   }
 
-  test_InterpolationExpression_prefix_selector2() async {
+  Future<void> test_InterpolationExpression_prefix_selector2() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \$name.^");}');
 
@@ -2835,7 +2837,7 @@
     assertNoSuggestions();
   }
 
-  test_InterpolationExpression_prefix_target() async {
+  Future<void> test_InterpolationExpression_prefix_target() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \${nam^e.length}");}');
 
@@ -2846,7 +2848,7 @@
     assertNotSuggested('length');
   }
 
-  test_IsExpression() async {
+  Future<void> test_IsExpression() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -2867,7 +2869,7 @@
     assertNotSuggested('foo');
   }
 
-  test_IsExpression_target() async {
+  Future<void> test_IsExpression_target() async {
     // IfStatement  Block  BlockFunctionBody
     addTestSource('''
         foo() { }
@@ -2886,7 +2888,7 @@
     assertSuggestClass('Object');
   }
 
-  test_IsExpression_type() async {
+  Future<void> test_IsExpression_type() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addTestSource('''
         class A {int x; int y() => 0;}
@@ -2901,7 +2903,7 @@
     assertSuggestClass('Object');
   }
 
-  test_IsExpression_type_partial() async {
+  Future<void> test_IsExpression_type_partial() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addTestSource('''
         class A {int x; int y() => 0;}
@@ -2916,7 +2918,7 @@
     assertSuggestClass('Object');
   }
 
-  test_IsExpression_type_subtype_extends_filter() async {
+  Future<void> test_IsExpression_type_subtype_extends_filter() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addSource('/home/test/lib/b.dart', '''
         foo() { }
@@ -2938,7 +2940,7 @@
     assertNotSuggested('main');
   }
 
-  test_IsExpression_type_subtype_implements_filter() async {
+  Future<void> test_IsExpression_type_subtype_implements_filter() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addSource('/home/test/lib/b.dart', '''
         foo() { }
@@ -2960,7 +2962,7 @@
     assertNotSuggested('main');
   }
 
-  test_keyword() async {
+  Future<void> test_keyword() async {
     resolveSource('/home/test/lib/b.dart', '''
         lib B;
         int newT1;
@@ -2987,7 +2989,7 @@
     assertNotSuggested('newer');
   }
 
-  test_Literal_list() async {
+  Future<void> test_Literal_list() async {
     // ']'  ListLiteral  ArgumentList  MethodInvocation
     addTestSource('main() {var Some; print([^]);}');
 
@@ -2996,7 +2998,7 @@
     assertSuggestClass('String');
   }
 
-  test_Literal_list2() async {
+  Future<void> test_Literal_list2() async {
     // SimpleIdentifier ListLiteral  ArgumentList  MethodInvocation
     addTestSource('main() {var Some; print([S^]);}');
 
@@ -3005,7 +3007,7 @@
     assertSuggestClass('String');
   }
 
-  test_Literal_string() async {
+  Future<void> test_Literal_string() async {
     // SimpleStringLiteral  ExpressionStatement  Block
     addTestSource('class A {a() {"hel^lo"}}');
 
@@ -3013,14 +3015,14 @@
     assertNoSuggestions();
   }
 
-  test_localVariableDeclarationName() async {
+  Future<void> test_localVariableDeclarationName() async {
     addTestSource('main() {String m^}');
     await computeSuggestions();
     assertNotSuggested('main');
     assertNotSuggested('min');
   }
 
-  test_MapLiteralEntry() async {
+  Future<void> test_MapLiteralEntry() async {
     // MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -3057,7 +3059,7 @@
     assertNotSuggested('C2');
   }
 
-  test_MapLiteralEntry1() async {
+  Future<void> test_MapLiteralEntry1() async {
     // MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -3084,7 +3086,7 @@
     assertNotSuggested('T2');
   }
 
-  test_MapLiteralEntry2() async {
+  Future<void> test_MapLiteralEntry2() async {
     // SimpleIdentifier  MapLiteralEntry  MapLiteral  VariableDeclaration
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -3106,7 +3108,7 @@
     assertNotSuggested('T2');
   }
 
-  test_method_parameters_mixed_required_and_named() async {
+  Future<void> test_method_parameters_mixed_required_and_named() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m(x, {int y}) {}
 ''');
@@ -3127,7 +3129,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_method_parameters_mixed_required_and_positional() async {
+  Future<void> test_method_parameters_mixed_required_and_positional() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m(x, [int y]) {}
 ''');
@@ -3148,7 +3150,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_named() async {
+  Future<void> test_method_parameters_named() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m({x, int y}) {}
 ''');
@@ -3169,7 +3171,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_method_parameters_none() async {
+  Future<void> test_method_parameters_none() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m() {}
 ''');
@@ -3188,7 +3190,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_positional() async {
+  Future<void> test_method_parameters_positional() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m([x, int y]) {}
 ''');
@@ -3209,7 +3211,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_required() async {
+  Future<void> test_method_parameters_required() async {
     resolveSource('/home/test/lib/a.dart', '''
 void m(x, int y) {}
 ''');
@@ -3230,7 +3232,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_MethodDeclaration_body_getters() async {
+  Future<void> test_MethodDeclaration_body_getters() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated X get f => 0; Z a() {^} get _g => 1;}');
 
@@ -3242,7 +3244,7 @@
     assertNotSuggested('_g');
   }
 
-  test_MethodDeclaration_body_static() async {
+  Future<void> test_MethodDeclaration_body_static() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/c.dart', '''
         class C {
@@ -3279,7 +3281,7 @@
     assertNotSuggested('c4');
   }
 
-  test_MethodDeclaration_members() async {
+  Future<void> test_MethodDeclaration_members() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated X f; Z _a() {^} var _g;}');
 
@@ -3295,7 +3297,7 @@
     }
   }
 
-  test_MethodDeclaration_parameters_named() async {
+  Future<void> test_MethodDeclaration_parameters_named() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated Z a(X x, _, b, {y: boo}) {^}}');
 
@@ -3310,7 +3312,7 @@
     assertNotSuggested('_');
   }
 
-  test_MethodDeclaration_parameters_positional() async {
+  Future<void> test_MethodDeclaration_parameters_positional() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('''
         foo() { }
@@ -3328,7 +3330,7 @@
     assertSuggestClass('String');
   }
 
-  test_MethodDeclaration_returnType() async {
+  Future<void> test_MethodDeclaration_returnType() async {
     // ClassDeclaration  CompilationUnit
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -3357,7 +3359,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment() async {
     // ClassDeclaration  CompilationUnit
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -3386,7 +3388,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment2() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment2() async {
     // MethodDeclaration  ClassDeclaration  CompilationUnit
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -3415,7 +3417,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment3() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment3() async {
     // MethodDeclaration  ClassDeclaration  CompilationUnit
     resolveSource('/home/test/lib/a.dart', '''
         int T1;
@@ -3446,7 +3448,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodInvocation_no_semicolon() async {
+  Future<void> test_MethodInvocation_no_semicolon() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
         main() { }
@@ -3479,7 +3481,7 @@
     assertNotSuggested('==');
   }
 
-  test_MethodTypeArgumentList() async {
+  Future<void> test_MethodTypeArgumentList() async {
     addSource('/home/test/lib/a.dart', '''
 class A {}
 class B {}
@@ -3503,7 +3505,7 @@
     assertNotSuggested('main');
   }
 
-  test_MethodTypeArgumentList_2() async {
+  Future<void> test_MethodTypeArgumentList_2() async {
     addTestSource('''
 void f<S,T>() { }
 
@@ -3520,7 +3522,7 @@
     assertNotSuggested('main');
   }
 
-  test_mixin_ordering() async {
+  Future<void> test_mixin_ordering() async {
     addSource('/home/test/lib/a.dart', '''
 class B {}
 class M1 {
@@ -3542,7 +3544,7 @@
     assertNotSuggested('m');
   }
 
-  test_new_instance() async {
+  Future<void> test_new_instance() async {
     addTestSource('import "dart:math"; class A {x() {new Random().^}}');
 
     await computeSuggestions();
@@ -3554,7 +3556,7 @@
     assertNotSuggested('A');
   }
 
-  test_no_parameters_field() async {
+  Future<void> test_no_parameters_field() async {
     addSource('/home/test/lib/a.dart', '''
 int x;
 ''');
@@ -3569,7 +3571,7 @@
     assertHasNoParameterInfo(suggestion);
   }
 
-  test_no_parameters_getter() async {
+  Future<void> test_no_parameters_getter() async {
     resolveSource('/home/test/lib/a.dart', '''
 int get x => null;
 ''');
@@ -3584,7 +3586,7 @@
     assertHasNoParameterInfo(suggestion);
   }
 
-  test_no_parameters_setter() async {
+  Future<void> test_no_parameters_setter() async {
     addSource('/home/test/lib/a.dart', '''
 set x(int value) {};
 ''');
@@ -3599,14 +3601,14 @@
     assertHasNoParameterInfo(suggestion);
   }
 
-  test_parameterName_excludeTypes() async {
+  Future<void> test_parameterName_excludeTypes() async {
     addTestSource('m(int ^) {}');
     await computeSuggestions();
     assertNotSuggested('int');
     assertNotSuggested('bool');
   }
 
-  test_partFile_TypeName() async {
+  Future<void> test_partFile_TypeName() async {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3641,7 +3643,7 @@
     assertNotSuggested('m');
   }
 
-  test_partFile_TypeName2() async {
+  Future<void> test_partFile_TypeName2() async {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/home/test/lib/b.dart', '''
         lib libB;
@@ -3676,7 +3678,7 @@
     assertNotSuggested('m');
   }
 
-  test_PrefixedIdentifier_class_const() async {
+  Future<void> test_PrefixedIdentifier_class_const() async {
     // SimpleIdentifier PrefixedIdentifier ExpressionStatement Block
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3723,7 +3725,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_class_imported() async {
+  Future<void> test_PrefixedIdentifier_class_imported() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3760,7 +3762,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_class_local() async {
+  Future<void> test_PrefixedIdentifier_class_local() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
         main() {A a; a.^}
@@ -3794,7 +3796,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_getter() async {
+  Future<void> test_PrefixedIdentifier_getter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String get g => "one"; f() {g.^}');
 
@@ -3802,7 +3804,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_library() async {
+  Future<void> test_PrefixedIdentifier_library() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3829,7 +3831,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_typesOnly() async {
+  Future<void> test_PrefixedIdentifier_library_typesOnly() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3856,7 +3858,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_typesOnly2() async {
+  Future<void> test_PrefixedIdentifier_library_typesOnly2() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3883,7 +3885,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_parameter() async {
+  Future<void> test_PrefixedIdentifier_parameter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3902,7 +3904,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_prefix() async {
+  Future<void> test_PrefixedIdentifier_prefix() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
         class A {static int bar = 10;}
@@ -3924,7 +3926,7 @@
     assertNotSuggested('_B');
   }
 
-  test_PrefixedIdentifier_propertyAccess() async {
+  Future<void> test_PrefixedIdentifier_propertyAccess() async {
     // PrefixedIdentifier  ExpressionStatement  Block  BlockFunctionBody
     addTestSource('class A {String x; int get foo {x.^}');
 
@@ -3935,7 +3937,7 @@
     assertNotSuggested('compareTo');
   }
 
-  test_PrefixedIdentifier_propertyAccess_newStmt() async {
+  Future<void> test_PrefixedIdentifier_propertyAccess_newStmt() async {
     // PrefixedIdentifier  ExpressionStatement  Block  BlockFunctionBody
     addTestSource('class A {String x; int get foo {x.^ int y = 0;}');
 
@@ -3946,7 +3948,7 @@
     assertNotSuggested('compareTo');
   }
 
-  test_PrefixedIdentifier_trailingStmt_const() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_const() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('const String g = "hello"; f() {g.^ int y = 0;}');
 
@@ -3954,7 +3956,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_field() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_field() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {String g; f() {g.^ int y = 0;}}');
 
@@ -3962,7 +3964,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_function() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_function() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String g() => "one"; f() {g.^ int y = 0;}');
 
@@ -3970,7 +3972,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_functionTypeAlias() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_functionTypeAlias() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('typedef String g(); f() {g.^ int y = 0;}');
 
@@ -3978,7 +3980,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_getter() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_getter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String get g => "one"; f() {g.^ int y = 0;}');
 
@@ -3986,7 +3988,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_local_typed() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_local_typed() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f() {String g; g.^ int y = 0;}');
 
@@ -3994,7 +3996,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_local_untyped() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_local_untyped() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f() {var g = "hello"; g.^ int y = 0;}');
 
@@ -4002,7 +4004,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_method() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_method() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {String g() {}; f() {g.^ int y = 0;}}');
 
@@ -4010,7 +4012,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_param() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_param() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {f(String g) {g.^ int y = 0;}}');
 
@@ -4018,7 +4020,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_param2() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_param2() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f(String g) {g.^ int y = 0;}');
 
@@ -4026,7 +4028,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_topLevelVar() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_topLevelVar() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String g; f() {g.^ int y = 0;}');
 
@@ -4034,7 +4036,7 @@
     assertNotSuggested('length');
   }
 
-  test_PropertyAccess_expression() async {
+  Future<void> test_PropertyAccess_expression() async {
     // SimpleIdentifier  MethodInvocation  PropertyAccess  ExpressionStatement
     addTestSource('class A {a() {"hello".to^String().length}}');
 
@@ -4048,7 +4050,7 @@
     assertNotSuggested('==');
   }
 
-  test_PropertyAccess_noTarget() async {
+  Future<void> test_PropertyAccess_noTarget() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement
     addSource('/home/test/lib/ab.dart', 'class Foo { }');
     addTestSource('class C {foo(){.^}}');
@@ -4057,7 +4059,7 @@
     assertNoSuggestions();
   }
 
-  test_PropertyAccess_noTarget2() async {
+  Future<void> test_PropertyAccess_noTarget2() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement
     addSource('/home/test/lib/ab.dart', 'class Foo { }');
     addTestSource('main() {.^}');
@@ -4066,7 +4068,7 @@
     assertNoSuggestions();
   }
 
-  test_PropertyAccess_selector() async {
+  Future<void> test_PropertyAccess_selector() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement  Block
     addTestSource('class A {a() {"hello".length.^}}');
 
@@ -4080,7 +4082,7 @@
     assertNotSuggested('==');
   }
 
-  test_SwitchStatement_c() async {
+  Future<void> test_SwitchStatement_c() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {switch(x) {c^}}}');
 
@@ -4088,7 +4090,7 @@
     assertNoSuggestions();
   }
 
-  test_SwitchStatement_case() async {
+  Future<void> test_SwitchStatement_case() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {var t; switch(x) {case 0: ^}}}');
 
@@ -4099,7 +4101,7 @@
     assertSuggestClass('String');
   }
 
-  test_SwitchStatement_empty() async {
+  Future<void> test_SwitchStatement_empty() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {switch(x) {^}}}');
 
@@ -4107,7 +4109,7 @@
     assertNoSuggestions();
   }
 
-  test_ThisExpression_block() async {
+  Future<void> test_ThisExpression_block() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
         main() { }
@@ -4143,7 +4145,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor() async {
+  Future<void> test_ThisExpression_constructor() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
         main() { }
@@ -4179,7 +4181,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param() async {
+  Future<void> test_ThisExpression_constructor_param() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -4217,7 +4219,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param2() async {
+  Future<void> test_ThisExpression_constructor_param2() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -4254,7 +4256,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param3() async {
+  Future<void> test_ThisExpression_constructor_param3() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -4291,7 +4293,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param4() async {
+  Future<void> test_ThisExpression_constructor_param4() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -4328,7 +4330,7 @@
     assertNotSuggested('==');
   }
 
-  test_TopLevelVariableDeclaration_typed_name() async {
+  Future<void> test_TopLevelVariableDeclaration_typed_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // TopLevelVariableDeclaration
     addTestSource('class A {} B ^');
@@ -4337,7 +4339,7 @@
     assertNoSuggestions();
   }
 
-  test_TopLevelVariableDeclaration_untyped_name() async {
+  Future<void> test_TopLevelVariableDeclaration_untyped_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // TopLevelVariableDeclaration
     addTestSource('class A {} var ^');
@@ -4346,7 +4348,7 @@
     assertNoSuggestions();
   }
 
-  test_TypeArgumentList() async {
+  Future<void> test_TypeArgumentList() async {
     // SimpleIdentifier  BinaryExpression  ExpressionStatement
     resolveSource('/home/test/lib/a.dart', '''
         class C1 {int x;}
@@ -4372,7 +4374,7 @@
     assertNotSuggested('F2');
   }
 
-  test_TypeArgumentList2() async {
+  Future<void> test_TypeArgumentList2() async {
     // TypeName  TypeArgumentList  TypeName
     addSource('/home/test/lib/a.dart', '''
         class C1 {int x;}
@@ -4393,7 +4395,7 @@
     assertNotSuggested('C2');
   }
 
-  test_TypeArgumentList_recursive() async {
+  Future<void> test_TypeArgumentList_recursive() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {}
 ''');
@@ -4413,7 +4415,7 @@
     assertSuggestClass('B');
   }
 
-  test_VariableDeclaration_name() async {
+  Future<void> test_VariableDeclaration_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addSource('/home/test/lib/b.dart', '''
@@ -4430,7 +4432,7 @@
     assertNoSuggestions();
   }
 
-  test_VariableDeclarationList_final() async {
+  Future<void> test_VariableDeclarationList_final() async {
     // VariableDeclarationList  VariableDeclarationStatement  Block
     addTestSource('main() {final ^} class C { }');
 
@@ -4440,7 +4442,7 @@
     assertNotSuggested('==');
   }
 
-  test_VariableDeclarationStatement_RHS() async {
+  Future<void> test_VariableDeclarationStatement_RHS() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement
     addSource('/home/test/lib/b.dart', '''
@@ -4465,7 +4467,7 @@
     assertNotSuggested('e');
   }
 
-  test_VariableDeclarationStatement_RHS_missing_semicolon() async {
+  Future<void> test_VariableDeclarationStatement_RHS_missing_semicolon() async {
     // VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement
     resolveSource('/home/test/lib/b.dart', '''
@@ -4496,7 +4498,7 @@
     assertNotSuggested('e');
   }
 
-  test_withClause_mixin() async {
+  Future<void> test_withClause_mixin() async {
     newFile('/home/test/lib/a.dart', content: 'mixin M {}');
     addTestSource('''
 import 'a.dart';
@@ -4507,7 +4509,7 @@
     assertSuggestMixin('M');
   }
 
-  test_YieldStatement() async {
+  Future<void> test_YieldStatement() async {
     addTestSource('''
 void main() async* {
   yield ^
diff --git a/pkg/analysis_server/test/services/completion/dart/inherited_reference_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/inherited_reference_contributor_test.dart
index 29526b5..2b43a5c 100644
--- a/pkg/analysis_server/test/services/completion/dart/inherited_reference_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/inherited_reference_contributor_test.dart
@@ -12,7 +12,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InheritedReferenceContributorTest);
   });
@@ -29,7 +29,7 @@
   }
 
   /// Sanity check.  Permutations tested in local_ref_contributor.
-  test_ArgDefaults_inherited_method_with_required_named() async {
+  Future<void> test_ArgDefaults_inherited_method_with_required_named() async {
     addMetaPackage();
     resolveSource('/home/test/lib/b.dart', '''
 import 'package:meta/meta.dart';
@@ -50,7 +50,7 @@
         defaultArgListString: 'bar, baz: null');
   }
 
-  test_AwaitExpression_inherited() async {
+  Future<void> test_AwaitExpression_inherited() async {
     // SimpleIdentifier  AwaitExpression  ExpressionStatement
     resolveSource('/home/test/lib/b.dart', '''
 lib libB;
@@ -76,7 +76,7 @@
     assertSuggestMethod('y', 'A', 'Future<dynamic>');
   }
 
-  test_Block_inherited_imported() async {
+  Future<void> test_Block_inherited_imported() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     resolveSource('/home/test/lib/b.dart', '''
       lib B;
@@ -103,7 +103,7 @@
     assertNotSuggested('==');
   }
 
-  test_Block_inherited_local() async {
+  Future<void> test_Block_inherited_local() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     addTestSource('''
 class F { var f1; f2() { } get f3 => 0; set f4(fx) { } }
@@ -127,7 +127,7 @@
     assertSuggestMethod('m2', 'M', 'int');
   }
 
-  test_flutter_setState_hasPrefix() async {
+  Future<void> test_flutter_setState_hasPrefix() async {
     var spaces_4 = ' ' * 4;
     var spaces_6 = ' ' * 6;
     await _check_flutter_setState(
@@ -139,7 +139,7 @@
         20);
   }
 
-  test_flutter_setState_longPrefix() async {
+  Future<void> test_flutter_setState_longPrefix() async {
     var spaces_6 = ' ' * 6;
     var spaces_8 = ' ' * 8;
     await _check_flutter_setState(
@@ -151,7 +151,7 @@
         22);
   }
 
-  test_flutter_setState_noPrefix() async {
+  Future<void> test_flutter_setState_noPrefix() async {
     var spaces_4 = ' ' * 4;
     var spaces_6 = ' ' * 6;
     await _check_flutter_setState(
@@ -163,7 +163,7 @@
         20);
   }
 
-  test_inherited() async {
+  Future<void> test_inherited() async {
     resolveSource('/home/test/lib/b.dart', '''
 lib libB;
 class A2 {
@@ -204,7 +204,7 @@
     assertSuggestMethod('y2', 'A2', 'int');
   }
 
-  test_method_inClass() async {
+  Future<void> test_method_inClass() async {
     addTestSource('''
 class A {
   void m(x, int y) {}
@@ -215,7 +215,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_inMixin() async {
+  Future<void> test_method_inMixin() async {
     addTestSource('''
 mixin A {
   void m(x, int y) {}
@@ -226,7 +226,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_inMixin_fromSuperclassConstraint() async {
+  Future<void> test_method_inMixin_fromSuperclassConstraint() async {
     addTestSource('''
 class C {
   void c(x, int y) {}
@@ -239,7 +239,7 @@
     assertSuggestMethod('c', 'C', 'void');
   }
 
-  test_method_parameters_mixed_required_and_named() async {
+  Future<void> test_method_parameters_mixed_required_and_named() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {
   void m(x, {int y}) {}
@@ -262,7 +262,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_method_parameters_mixed_required_and_named_local() async {
+  Future<void> test_method_parameters_mixed_required_and_named_local() async {
     addTestSource('''
 class A {
   void m(x, {int y}) {}
@@ -282,7 +282,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_method_parameters_mixed_required_and_positional() async {
+  Future<void> test_method_parameters_mixed_required_and_positional() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {
   void m(x, [int y]) {}
@@ -305,7 +305,8 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_mixed_required_and_positional_local() async {
+  Future<void>
+      test_method_parameters_mixed_required_and_positional_local() async {
     addTestSource('''
 class A {
   void m(x, [int y]) {}
@@ -325,7 +326,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_named() async {
+  Future<void> test_method_parameters_named() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {
   void m({x, int y}) {}
@@ -348,7 +349,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_method_parameters_named_local() async {
+  Future<void> test_method_parameters_named_local() async {
     addTestSource('''
 class A {
   void m({x, int y}) {}
@@ -368,7 +369,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_method_parameters_none() async {
+  Future<void> test_method_parameters_none() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {
   void m() {}
@@ -388,7 +389,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_none_local() async {
+  Future<void> test_method_parameters_none_local() async {
     addTestSource('''
 class A {
   void m() {}
@@ -405,7 +406,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_positional() async {
+  Future<void> test_method_parameters_positional() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {
   void m([x, int y]) {}
@@ -428,7 +429,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_positional_local() async {
+  Future<void> test_method_parameters_positional_local() async {
     addTestSource('''
 class A {
   void m([x, int y]) {}
@@ -448,7 +449,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_required() async {
+  Future<void> test_method_parameters_required() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {
   void m(x, int y) {}
@@ -471,7 +472,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_mixin_ordering() async {
+  Future<void> test_mixin_ordering() async {
     resolveSource('/home/test/lib/a.dart', '''
 class B {}
 class M1 {
@@ -493,7 +494,7 @@
     assertSuggestMethod('m', 'M1', 'void');
   }
 
-  test_no_parameters_field() async {
+  Future<void> test_no_parameters_field() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {
   int x;
@@ -510,7 +511,7 @@
     assertHasNoParameterInfo(suggestion);
   }
 
-  test_no_parameters_getter() async {
+  Future<void> test_no_parameters_getter() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {
   int get x => null;
@@ -527,7 +528,7 @@
     assertHasNoParameterInfo(suggestion);
   }
 
-  test_no_parameters_setter() async {
+  Future<void> test_no_parameters_setter() async {
     resolveSource('/home/test/lib/a.dart', '''
 class A {
   set x(int value) {};
@@ -544,7 +545,7 @@
     assertHasNoParameterInfo(suggestion);
   }
 
-  test_outside_class() async {
+  Future<void> test_outside_class() async {
     resolveSource('/home/test/lib/b.dart', '''
 lib libB;
 class A2 {
@@ -585,7 +586,7 @@
     assertNotSuggested('y2');
   }
 
-  test_static_field() async {
+  Future<void> test_static_field() async {
     resolveSource('/home/test/lib/b.dart', '''
 lib libB;
 class A2 {
@@ -626,7 +627,7 @@
     assertNotSuggested('y2');
   }
 
-  test_static_method() async {
+  Future<void> test_static_method() async {
     resolveSource('/home/test/lib/b.dart', '''
 lib libB;
 class A2 {
diff --git a/pkg/analysis_server/test/services/completion/dart/keyword_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/keyword_contributor_test.dart
index 4331d17..ebe6350 100644
--- a/pkg/analysis_server/test/services/completion/dart/keyword_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/keyword_contributor_test.dart
@@ -13,7 +13,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(KeywordContributorTest);
     defineReflectiveTests(KeywordContributorWithExtensionMethodsTest);
@@ -439,33 +439,33 @@
   bool isEnabled(Feature feature) =>
       driver.analysisOptions.contextFeatures.isEnabled(feature);
 
-  test_after_class_noPrefix() async {
+  Future<void> test_after_class_noPrefix() async {
     addTestSource('class A {} ^');
     await computeSuggestions();
     assertSuggestKeywords(declarationKeywords, relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_after_class_prefix() async {
+  Future<void> test_after_class_prefix() async {
     addTestSource('class A {} c^');
     await computeSuggestions();
     assertSuggestKeywords(declarationKeywords, relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_after_import_noPrefix() async {
+  Future<void> test_after_import_noPrefix() async {
     addTestSource('import "foo"; ^');
     await computeSuggestions();
     assertSuggestKeywords(directiveAndDeclarationKeywords,
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_after_import_prefix() async {
+  Future<void> test_after_import_prefix() async {
     addTestSource('import "foo"; c^');
     await computeSuggestions();
     assertSuggestKeywords(directiveAndDeclarationKeywords,
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_anonymous_function_async() async {
+  Future<void> test_anonymous_function_async() async {
     addTestSource('main() {foo(() ^ {}}}');
     await computeSuggestions();
     assertSuggestKeywords([],
@@ -473,7 +473,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_anonymous_function_async2() async {
+  Future<void> test_anonymous_function_async2() async {
     addTestSource('main() {foo(() a^ {}}}');
     await computeSuggestions();
     // Fasta adds a closing paren after the first `}`
@@ -485,27 +485,27 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_anonymous_function_async3() async {
+  Future<void> test_anonymous_function_async3() async {
     addTestSource('main() {foo(() async ^ {}}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_anonymous_function_async4() async {
+  Future<void> test_anonymous_function_async4() async {
     addTestSource('main() {foo(() ^ => 2}}');
     await computeSuggestions();
     assertSuggestKeywords([],
         pseudoKeywords: ['async'], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_anonymous_function_async5() async {
+  Future<void> test_anonymous_function_async5() async {
     addTestSource('main() {foo(() ^}}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE,
         pseudoKeywords: ['async', 'async*', 'sync*']);
   }
 
-  test_anonymous_function_async6() async {
+  Future<void> test_anonymous_function_async6() async {
     addTestSource('main() {foo("bar", () as^{}}');
     await computeSuggestions();
     assertSuggestKeywords([],
@@ -513,7 +513,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_anonymous_function_async7() async {
+  Future<void> test_anonymous_function_async7() async {
     addTestSource('main() {foo("bar", () as^ => null');
     await computeSuggestions();
     assertSuggestKeywords([],
@@ -522,7 +522,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_anonymous_function_async8() async {
+  Future<void> test_anonymous_function_async8() async {
     addTestSource('main() {foo(() ^ {})}}');
     await computeSuggestions();
     assertSuggestKeywords([],
@@ -530,7 +530,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_anonymous_function_async9() async {
+  Future<void> test_anonymous_function_async9() async {
     addTestSource('main() {foo(() a^ {})}}');
     await computeSuggestions();
     // Fasta interprets the argument as a function expression
@@ -540,81 +540,81 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_argument() async {
+  Future<void> test_argument() async {
     addTestSource('main() {foo(^);}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_argument2() async {
+  Future<void> test_argument2() async {
     addTestSource('main() {foo(n^);}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_argument_literal() async {
+  Future<void> test_argument_literal() async {
     addTestSource('main() {foo("^");}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_argument_named() async {
+  Future<void> test_argument_named() async {
     addTestSource('main() {foo(bar: ^);}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_argument_named2() async {
+  Future<void> test_argument_named2() async {
     addTestSource('main() {foo(bar: n^);}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_argument_named_literal() async {
+  Future<void> test_argument_named_literal() async {
     addTestSource('main() {foo(bar: "^");}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_assignment_field() async {
+  Future<void> test_assignment_field() async {
     addTestSource('class A {var foo = ^}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_assignment_field2() async {
+  Future<void> test_assignment_field2() async {
     addTestSource('class A {var foo = n^}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_assignment_local() async {
+  Future<void> test_assignment_local() async {
     addTestSource('main() {var foo = ^}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_assignment_local2() async {
+  Future<void> test_assignment_local2() async {
     addTestSource('main() {var foo = n^}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_assignment_local2_async() async {
+  Future<void> test_assignment_local2_async() async {
     addTestSource('main() async {var foo = n^}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE,
         pseudoKeywords: ['await']);
   }
 
-  test_assignment_local_async() async {
+  Future<void> test_assignment_local_async() async {
     addTestSource('main() async {var foo = ^}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE,
         pseudoKeywords: ['await']);
   }
 
-  test_before_import() async {
+  Future<void> test_before_import() async {
     addTestSource('^ import foo;');
     await computeSuggestions();
     assertSuggestKeywords(
@@ -622,7 +622,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_catch_1a() async {
+  Future<void> test_catch_1a() async {
     // '}'  Block  BlockFunctionBody  FunctionExpression
     addTestSource('main() {try {} ^}');
     await computeSuggestions();
@@ -632,7 +632,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_1b() async {
+  Future<void> test_catch_1b() async {
     // [ExpressionStatement 'c']  Block  BlockFunctionBody  FunctionExpression
     addTestSource('main() {try {} c^}');
     await computeSuggestions();
@@ -642,7 +642,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_1c() async {
+  Future<void> test_catch_1c() async {
     // [EmptyStatement] Block BlockFunction FunctionExpression
     addTestSource('main() {try {} ^;}');
     await computeSuggestions();
@@ -652,7 +652,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_1d() async {
+  Future<void> test_catch_1d() async {
     // [EmptyStatement] Block BlockFunction FunctionExpression
     addTestSource('main() {try {} ^ Foo foo;}');
     await computeSuggestions();
@@ -662,7 +662,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_2a() async {
+  Future<void> test_catch_2a() async {
     // '}'  Block  BlockFunctionBody  FunctionExpression
     addTestSource('main() {try {} on SomeException {} ^}');
     await computeSuggestions();
@@ -673,7 +673,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_2b() async {
+  Future<void> test_catch_2b() async {
     // [ExpressionStatement 'c']  Block  BlockFunctionBody  FunctionExpression
     addTestSource('main() {try {} on SomeException {} c^}');
     await computeSuggestions();
@@ -684,7 +684,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_2c() async {
+  Future<void> test_catch_2c() async {
     // [EmptyStatement] Block BlockFunction FunctionExpression
     addTestSource('main() {try {} on SomeException {} ^;}');
     await computeSuggestions();
@@ -695,7 +695,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_2d() async {
+  Future<void> test_catch_2d() async {
     // [EmptyStatement] Block BlockFunction FunctionExpression
     addTestSource('main() {try {} on SomeException {} ^ Foo foo;}');
     await computeSuggestions();
@@ -706,7 +706,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_3a() async {
+  Future<void> test_catch_3a() async {
     // '}'  Block  BlockFunctionBody  FunctionExpression
     addTestSource('main() {try {} catch (e) {} ^}');
     await computeSuggestions();
@@ -717,7 +717,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_3b() async {
+  Future<void> test_catch_3b() async {
     // [ExpressionStatement 'c']  Block  BlockFunctionBody  FunctionExpression
     addTestSource('main() {try {} catch (e) {} c^}');
     await computeSuggestions();
@@ -728,7 +728,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_3c() async {
+  Future<void> test_catch_3c() async {
     // [EmptyStatement] Block BlockFunction FunctionExpression
     addTestSource('main() {try {} catch (e) {} ^;}');
     await computeSuggestions();
@@ -739,7 +739,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_3d() async {
+  Future<void> test_catch_3d() async {
     // [EmptyStatement] Block BlockFunction FunctionExpression
     addTestSource('main() {try {} catch (e) {} ^ Foo foo;}');
     await computeSuggestions();
@@ -750,7 +750,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_4a1() async {
+  Future<void> test_catch_4a1() async {
     // [CatchClause]  TryStatement  Block
     addTestSource('main() {try {} ^ on SomeException {}}');
     await computeSuggestions();
@@ -759,7 +759,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_4a2() async {
+  Future<void> test_catch_4a2() async {
     // ['c' VariableDeclarationStatement]  Block  BlockFunctionBody
     addTestSource('main() {try {} c^ on SomeException {}}');
     await computeSuggestions();
@@ -770,7 +770,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_4b1() async {
+  Future<void> test_catch_4b1() async {
     // [CatchClause]  TryStatement  Block
     addTestSource('main() {try {} ^ catch (e) {}}');
     await computeSuggestions();
@@ -779,7 +779,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_4b2() async {
+  Future<void> test_catch_4b2() async {
     // ['c' ExpressionStatement]  Block  BlockFunctionBody
     addTestSource('main() {try {} c^ catch (e) {}}');
     await computeSuggestions();
@@ -790,7 +790,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_4c1() async {
+  Future<void> test_catch_4c1() async {
     // ['finally']  TryStatement  Block
     addTestSource('main() {try {} ^ finally {}}');
     await computeSuggestions();
@@ -799,7 +799,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_4c2() async {
+  Future<void> test_catch_4c2() async {
     // ['c' ExpressionStatement]  Block  BlockFunctionBody
     addTestSource('main() {try {} c^ finally {}}');
     await computeSuggestions();
@@ -810,7 +810,7 @@
     assertSuggestKeywords(keywords, pseudoKeywords: ['on']);
   }
 
-  test_catch_block() async {
+  Future<void> test_catch_block() async {
     // '}'  Block  CatchClause  TryStatement  Block
     addTestSource('main() {try {} catch (e) {^}}}');
     await computeSuggestions();
@@ -820,71 +820,71 @@
     assertSuggestKeywords(keywords);
   }
 
-  test_class() async {
+  Future<void> test_class() async {
     addTestSource('class A e^ { }');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.EXTENDS, Keyword.IMPLEMENTS],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_body() async {
+  Future<void> test_class_body() async {
     addTestSource('class A {^}');
     await computeSuggestions();
     assertSuggestKeywords(classBodyKeywords);
   }
 
-  test_class_body_beginning() async {
+  Future<void> test_class_body_beginning() async {
     addTestSource('class A {^ var foo;}');
     await computeSuggestions();
     assertSuggestKeywords(classBodyKeywords);
   }
 
-  test_class_body_between() async {
+  Future<void> test_class_body_between() async {
     addTestSource('class A {var bar; ^ var foo;}');
     await computeSuggestions();
     assertSuggestKeywords(classBodyKeywords);
   }
 
-  test_class_body_end() async {
+  Future<void> test_class_body_end() async {
     addTestSource('class A {var foo; ^}');
     await computeSuggestions();
     assertSuggestKeywords(classBodyKeywords);
   }
 
-  test_class_extends() async {
+  Future<void> test_class_extends() async {
     addTestSource('class A extends foo ^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IMPLEMENTS, Keyword.WITH],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_extends2() async {
+  Future<void> test_class_extends2() async {
     addTestSource('class A extends foo i^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IMPLEMENTS, Keyword.WITH],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_extends3() async {
+  Future<void> test_class_extends3() async {
     addTestSource('class A extends foo i^ { }');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IMPLEMENTS, Keyword.WITH],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_extends_name() async {
+  Future<void> test_class_extends_name() async {
     addTestSource('class A extends ^');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_class_implements() async {
+  Future<void> test_class_implements() async {
     addTestSource('class A ^ implements foo');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.EXTENDS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_implements2() async {
+  Future<void> test_class_implements2() async {
     addTestSource('class A e^ implements foo');
     await computeSuggestions();
     assertSuggestKeywords(
@@ -894,7 +894,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_implements3() async {
+  Future<void> test_class_implements3() async {
     addTestSource('class A e^ implements foo { }');
     await computeSuggestions();
     assertSuggestKeywords(
@@ -904,13 +904,13 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_implements_name() async {
+  Future<void> test_class_implements_name() async {
     addTestSource('class A implements ^');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_class_member_const_afterStatic() async {
+  Future<void> test_class_member_const_afterStatic() async {
     addTestSource('''
 class C {
   static c^
@@ -920,7 +920,7 @@
     assertSuggestKeywords(staticMember);
   }
 
-  test_class_member_final_afterStatic() async {
+  Future<void> test_class_member_final_afterStatic() async {
     addTestSource('''
 class C {
   static f^
@@ -930,153 +930,153 @@
     assertSuggestKeywords(staticMember);
   }
 
-  test_class_name() async {
+  Future<void> test_class_name() async {
     addTestSource('class ^');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_class_noBody() async {
+  Future<void> test_class_noBody() async {
     addTestSource('class A ^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.EXTENDS, Keyword.IMPLEMENTS],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_noBody2() async {
+  Future<void> test_class_noBody2() async {
     addTestSource('class A e^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.EXTENDS, Keyword.IMPLEMENTS],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_noBody3() async {
+  Future<void> test_class_noBody3() async {
     addTestSource('class A e^ String foo;');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.EXTENDS, Keyword.IMPLEMENTS],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_with() async {
+  Future<void> test_class_with() async {
     addTestSource('class A extends foo with bar ^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IMPLEMENTS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_with2() async {
+  Future<void> test_class_with2() async {
     addTestSource('class A extends foo with bar i^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IMPLEMENTS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_with3() async {
+  Future<void> test_class_with3() async {
     addTestSource('class A extends foo with bar i^ { }');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IMPLEMENTS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_class_with_name() async {
+  Future<void> test_class_with_name() async {
     addTestSource('class A extends foo with ^');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_constructor_initializers_first() async {
+  Future<void> test_constructor_initializers_first() async {
     addTestSource('class A { int f; A() : ^, f = 1; }');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.ASSERT]);
   }
 
-  test_constructor_initializers_last() async {
+  Future<void> test_constructor_initializers_last() async {
     addTestSource('class A { A() : ^; }');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.ASSERT, Keyword.SUPER, Keyword.THIS]);
   }
 
-  test_constructor_param_noPrefix() async {
+  Future<void> test_constructor_param_noPrefix() async {
     addTestSource('class A { A(^) {});}');
     await computeSuggestions();
     assertSuggestKeywords(constructorParameter);
   }
 
-  test_constructor_param_prefix() async {
+  Future<void> test_constructor_param_prefix() async {
     addTestSource('class A { A(t^) {});}');
     await computeSuggestions();
     assertSuggestKeywords(constructorParameter);
   }
 
-  test_do_break_continue_insideClass() async {
+  Future<void> test_do_break_continue_insideClass() async {
     addTestSource('class A {foo() {do {^} while (true);}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInLoopInClass,
         relevance: DART_RELEVANCE_KEYWORD);
   }
 
-  test_do_break_continue_outsideClass() async {
+  Future<void> test_do_break_continue_outsideClass() async {
     addTestSource('main() {do {^} while (true);}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInLoopOutsideClass,
         relevance: DART_RELEVANCE_KEYWORD);
   }
 
-  test_empty() async {
+  Future<void> test_empty() async {
     addTestSource('^');
     await computeSuggestions();
     assertSuggestKeywords(directiveDeclarationAndLibraryKeywords,
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_for_break_continue_insideClass() async {
+  Future<void> test_for_break_continue_insideClass() async {
     addTestSource('class A {foo() {for (int x in myList) {^}}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInLoopInClass,
         relevance: DART_RELEVANCE_KEYWORD);
   }
 
-  test_for_break_continue_outsideClass() async {
+  Future<void> test_for_break_continue_outsideClass() async {
     addTestSource('main() {for (int x in myList) {^}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInLoopOutsideClass,
         relevance: DART_RELEVANCE_KEYWORD);
   }
 
-  test_for_expression_in() async {
+  Future<void> test_for_expression_in() async {
     addTestSource('main() {for (int x i^)}');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IN], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_for_expression_in2() async {
+  Future<void> test_for_expression_in2() async {
     addTestSource('main() {for (int x in^)}');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IN], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_for_expression_in_inInitializer() async {
+  Future<void> test_for_expression_in_inInitializer() async {
     addTestSource('main() {for (int i^)}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_for_expression_init() async {
+  Future<void> test_for_expression_init() async {
     addTestSource('main() {for (int x = i^)}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_for_expression_init2() async {
+  Future<void> test_for_expression_init2() async {
     addTestSource('main() {for (int x = in^)}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_for_initialization_var() async {
+  Future<void> test_for_initialization_var() async {
     addTestSource('main() {for (^)}');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.VAR], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_function_async() async {
+  Future<void> test_function_async() async {
     addTestSource('main()^');
     await computeSuggestions();
     assertSuggestKeywords([],
@@ -1084,7 +1084,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_function_async2() async {
+  Future<void> test_function_async2() async {
     addTestSource('main()^{}');
     await computeSuggestions();
     assertSuggestKeywords([],
@@ -1092,7 +1092,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_function_async3() async {
+  Future<void> test_function_async3() async {
     addTestSource('main()a^');
     await computeSuggestions();
     assertSuggestKeywords(declarationKeywords,
@@ -1100,7 +1100,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_function_async4() async {
+  Future<void> test_function_async4() async {
     addTestSource('main()a^{}');
     await computeSuggestions();
     assertSuggestKeywords([],
@@ -1108,7 +1108,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_function_async5() async {
+  Future<void> test_function_async5() async {
     addTestSource('main()a^ Foo foo;');
     await computeSuggestions();
     assertSuggestKeywords(declarationKeywords,
@@ -1116,7 +1116,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_function_body_inClass_constructorInitializer() async {
+  Future<void> test_function_body_inClass_constructorInitializer() async {
     addTestSource(r'''
 foo(p) {}
 class A {
@@ -1128,7 +1128,7 @@
     assertSuggestKeywords(statementStartOutsideClass);
   }
 
-  test_function_body_inClass_constructorInitializer_async() async {
+  Future<void> test_function_body_inClass_constructorInitializer_async() async {
     addTestSource(r'''
 foo(p) {}
 class A {
@@ -1141,7 +1141,8 @@
         pseudoKeywords: ['await']);
   }
 
-  test_function_body_inClass_constructorInitializer_async_star() async {
+  Future<void>
+      test_function_body_inClass_constructorInitializer_async_star() async {
     addTestSource(r'''
   foo(p) {}
   class A {
@@ -1154,7 +1155,7 @@
         pseudoKeywords: ['await', 'yield', 'yield*']);
   }
 
-  test_function_body_inClass_field() async {
+  Future<void> test_function_body_inClass_field() async {
     addTestSource(r'''
 class A {
   var f = () {^};
@@ -1164,7 +1165,7 @@
     assertSuggestKeywords(statementStartOutsideClass);
   }
 
-  test_function_body_inClass_methodBody() async {
+  Future<void> test_function_body_inClass_methodBody() async {
     addTestSource(r'''
 class A {
   m() {
@@ -1176,7 +1177,7 @@
     assertSuggestKeywords(statementStartInClass);
   }
 
-  test_function_body_inClass_methodBody_inFunction() async {
+  Future<void> test_function_body_inClass_methodBody_inFunction() async {
     addTestSource(r'''
 class A {
   m() {
@@ -1190,7 +1191,7 @@
     assertSuggestKeywords(statementStartInClass);
   }
 
-  test_function_body_inClass_methodBody_inFunction_async() async {
+  Future<void> test_function_body_inClass_methodBody_inFunction_async() async {
     addTestSource(r'''
 class A {
   m() {
@@ -1204,7 +1205,8 @@
     assertSuggestKeywords(statementStartInClass, pseudoKeywords: ['await']);
   }
 
-  test_function_body_inClass_methodBody_inFunction_async_star() async {
+  Future<void>
+      test_function_body_inClass_methodBody_inFunction_async_star() async {
     addTestSource(r'''
   class A {
     m() {
@@ -1219,61 +1221,61 @@
         pseudoKeywords: ['await', 'yield', 'yield*']);
   }
 
-  test_function_body_inUnit() async {
+  Future<void> test_function_body_inUnit() async {
     addTestSource('main() {^}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass);
   }
 
-  test_function_body_inUnit_afterBlock() async {
+  Future<void> test_function_body_inUnit_afterBlock() async {
     addTestSource('main() {{}^}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass);
   }
 
-  test_function_body_inUnit_async() async {
+  Future<void> test_function_body_inUnit_async() async {
     addTestSource('main() async {^}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass,
         pseudoKeywords: ['await']);
   }
 
-  test_function_body_inUnit_async_star() async {
+  Future<void> test_function_body_inUnit_async_star() async {
     addTestSource('main() async* {n^}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass,
         pseudoKeywords: ['await', 'yield', 'yield*']);
   }
 
-  test_function_body_inUnit_async_star2() async {
+  Future<void> test_function_body_inUnit_async_star2() async {
     addTestSource('main() async* {n^ foo}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass,
         pseudoKeywords: ['await', 'yield', 'yield*']);
   }
 
-  test_function_body_inUnit_sync_star() async {
+  Future<void> test_function_body_inUnit_sync_star() async {
     addTestSource('main() sync* {n^}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass,
         pseudoKeywords: ['await', 'yield', 'yield*']);
   }
 
-  test_function_body_inUnit_sync_star2() async {
+  Future<void> test_function_body_inUnit_sync_star2() async {
     addTestSource('main() sync* {n^ foo}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass,
         pseudoKeywords: ['await', 'yield', 'yield*']);
   }
 
-  test_if_after_else() async {
+  Future<void> test_if_after_else() async {
     addTestSource('main() { if (true) {} else ^ }');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass,
         relevance: DART_RELEVANCE_KEYWORD);
   }
 
-  test_if_afterThen_nextCloseCurlyBrace0() async {
+  Future<void> test_if_afterThen_nextCloseCurlyBrace0() async {
     addTestSource('main() { if (true) {} ^ }');
     await computeSuggestions();
     List<Keyword> keywords = [];
@@ -1282,7 +1284,7 @@
     assertSuggestKeywords(keywords, relevance: DART_RELEVANCE_KEYWORD);
   }
 
-  test_if_afterThen_nextCloseCurlyBrace1() async {
+  Future<void> test_if_afterThen_nextCloseCurlyBrace1() async {
     addTestSource('main() { if (true) {} e^ }');
     await computeSuggestions();
     List<Keyword> keywords = [];
@@ -1291,7 +1293,7 @@
     assertSuggestKeywords(keywords, relevance: DART_RELEVANCE_KEYWORD);
   }
 
-  test_if_afterThen_nextStatement0() async {
+  Future<void> test_if_afterThen_nextStatement0() async {
     addTestSource('main() { if (true) {} ^ print(0); }');
     await computeSuggestions();
     List<Keyword> keywords = [];
@@ -1300,91 +1302,91 @@
     assertSuggestKeywords(keywords, relevance: DART_RELEVANCE_KEYWORD);
   }
 
-  test_if_condition_isKeyword() async {
+  Future<void> test_if_condition_isKeyword() async {
     addTestSource('main() { if (v i^) {} }');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_if_condition_isKeyword2() async {
+  Future<void> test_if_condition_isKeyword2() async {
     addTestSource('main() { if (v i^ && false) {} }');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_if_expression_in_class() async {
+  Future<void> test_if_expression_in_class() async {
     addTestSource('class A {foo() {if (^) }}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE);
   }
 
-  test_if_expression_in_class2() async {
+  Future<void> test_if_expression_in_class2() async {
     addTestSource('class A {foo() {if (n^) }}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE);
   }
 
-  test_if_expression_in_function() async {
+  Future<void> test_if_expression_in_function() async {
     addTestSource('foo() {if (^) }');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_if_expression_in_function2() async {
+  Future<void> test_if_expression_in_function2() async {
     addTestSource('foo() {if (n^) }');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_if_in_class() async {
+  Future<void> test_if_in_class() async {
     addTestSource('class A {foo() {if (true) ^}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInClass);
   }
 
-  test_if_in_class2() async {
+  Future<void> test_if_in_class2() async {
     addTestSource('class A {foo() {if (true) ^;}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInClass);
   }
 
-  test_if_in_class3() async {
+  Future<void> test_if_in_class3() async {
     addTestSource('class A {foo() {if (true) r^;}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInClass);
   }
 
-  test_if_in_class4() async {
+  Future<void> test_if_in_class4() async {
     addTestSource('class A {foo() {if (true) ^ go();}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInClass);
   }
 
-  test_if_outside_class() async {
+  Future<void> test_if_outside_class() async {
     addTestSource('foo() {if (true) ^}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass);
   }
 
-  test_if_outside_class2() async {
+  Future<void> test_if_outside_class2() async {
     addTestSource('foo() {if (true) ^;}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass);
   }
 
-  test_if_outside_class3() async {
+  Future<void> test_if_outside_class3() async {
     addTestSource('foo() {if (true) r^;}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass);
   }
 
-  test_if_outside_class4() async {
+  Future<void> test_if_outside_class4() async {
     addTestSource('foo() {if (true) ^ go();}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartOutsideClass);
   }
 
-  test_ifOrForElement_forElement() async {
+  Future<void> test_ifOrForElement_forElement() async {
     addTestSource('''
 f() => [for (var e in c) ^];
 ''');
@@ -1392,7 +1394,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_ifElement_else() async {
+  Future<void> test_ifOrForElement_ifElement_else() async {
     addTestSource('''
 f() => [if (true) 1 else ^];
 ''');
@@ -1400,7 +1402,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_ifElement_then() async {
+  Future<void> test_ifOrForElement_ifElement_then() async {
     addTestSource('''
 f() => [if (true) ^];
 ''');
@@ -1408,7 +1410,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_list_empty() async {
+  Future<void> test_ifOrForElement_list_empty() async {
     addTestSource('''
 f() => [^];
 ''');
@@ -1416,7 +1418,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_list_first() async {
+  Future<void> test_ifOrForElement_list_first() async {
     addTestSource('''
 f() => [^1, 2];
 ''');
@@ -1424,7 +1426,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_list_last() async {
+  Future<void> test_ifOrForElement_list_last() async {
     addTestSource('''
 f() => [1, 2, ^];
 ''');
@@ -1432,7 +1434,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_list_middle() async {
+  Future<void> test_ifOrForElement_list_middle() async {
     addTestSource('''
 f() => [1, ^, 2];
 ''');
@@ -1440,7 +1442,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_map_empty() async {
+  Future<void> test_ifOrForElement_map_empty() async {
     addTestSource('''
 f() => <String, int>{^};
 ''');
@@ -1448,7 +1450,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_map_first() async {
+  Future<void> test_ifOrForElement_map_first() async {
     addTestSource('''
 f() => <String, int>{^'a' : 1};
 ''');
@@ -1456,7 +1458,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_map_last() async {
+  Future<void> test_ifOrForElement_map_last() async {
     addTestSource('''
 f() => <String, int>{'a' : 1, 'b' : 2, ^};
 ''');
@@ -1464,7 +1466,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_map_middle() async {
+  Future<void> test_ifOrForElement_map_middle() async {
     addTestSource('''
 f() => <String, int>{'a' : 1, ^, 'b' : 2];
 ''');
@@ -1472,7 +1474,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_set_empty() async {
+  Future<void> test_ifOrForElement_set_empty() async {
     addTestSource('''
 f() => <int>{^};
 ''');
@@ -1480,7 +1482,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_set_first() async {
+  Future<void> test_ifOrForElement_set_first() async {
     addTestSource('''
 f() => <int>{^1, 2};
 ''');
@@ -1488,7 +1490,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_set_last() async {
+  Future<void> test_ifOrForElement_set_last() async {
     addTestSource('''
 f() => <int>{1, 2, ^};
 ''');
@@ -1496,7 +1498,7 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_ifOrForElement_set_middle() async {
+  Future<void> test_ifOrForElement_set_middle() async {
     addTestSource('''
 f() => <int>{1, ^, 2};
 ''');
@@ -1504,58 +1506,58 @@
     assertSuggestKeywords(COLLECTION_ELEMENT_START);
   }
 
-  test_import() async {
+  Future<void> test_import() async {
     addTestSource('import "foo" deferred as foo ^;');
     await computeSuggestions();
     assertSuggestKeywords([],
         pseudoKeywords: ['show', 'hide'], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_as() async {
+  Future<void> test_import_as() async {
     addTestSource('import "foo" deferred ^;');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_as2() async {
+  Future<void> test_import_as2() async {
     addTestSource('import "foo" deferred a^;');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_as3() async {
+  Future<void> test_import_as3() async {
     addTestSource('import "foo" deferred a^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred() async {
+  Future<void> test_import_deferred() async {
     addTestSource('import "foo" ^ as foo;');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.DEFERRED], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred2() async {
+  Future<void> test_import_deferred2() async {
     addTestSource('import "foo" d^ as foo;');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.DEFERRED], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred3() async {
+  Future<void> test_import_deferred3() async {
     addTestSource('import "foo" d^ show foo;');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS],
         pseudoKeywords: ['deferred as'], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred4() async {
+  Future<void> test_import_deferred4() async {
     addTestSource('import "foo" d^ hide foo;');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS],
         pseudoKeywords: ['deferred as'], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred5() async {
+  Future<void> test_import_deferred5() async {
     addTestSource('import "foo" d^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS],
@@ -1563,7 +1565,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred6() async {
+  Future<void> test_import_deferred6() async {
     addTestSource('import "foo" d^ import');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS],
@@ -1571,7 +1573,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred_as() async {
+  Future<void> test_import_deferred_as() async {
     addTestSource('import "foo" ^;');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS],
@@ -1579,7 +1581,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred_as2() async {
+  Future<void> test_import_deferred_as2() async {
     addTestSource('import "foo" d^;');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS],
@@ -1587,7 +1589,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred_as3() async {
+  Future<void> test_import_deferred_as3() async {
     addTestSource('import "foo" ^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS],
@@ -1595,7 +1597,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred_as4() async {
+  Future<void> test_import_deferred_as4() async {
     addTestSource('import "foo" d^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS],
@@ -1603,7 +1605,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred_as5() async {
+  Future<void> test_import_deferred_as5() async {
     addTestSource('import "foo" sh^ import "bar"; import "baz";');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.AS],
@@ -1611,14 +1613,14 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred_not() async {
+  Future<void> test_import_deferred_not() async {
     addTestSource('import "foo" as foo ^;');
     await computeSuggestions();
     assertSuggestKeywords([],
         pseudoKeywords: ['show', 'hide'], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_deferred_partial() async {
+  Future<void> test_import_deferred_partial() async {
     addTestSource('import "package:foo/foo.dart" def^ as foo;');
     await computeSuggestions();
     expect(replacementOffset, 30);
@@ -1628,13 +1630,13 @@
     expect(suggestions[0].selectionLength, 0);
   }
 
-  test_import_incomplete() async {
+  Future<void> test_import_incomplete() async {
     addTestSource('import "^"');
     await computeSuggestions();
     expect(suggestions, isEmpty);
   }
 
-  test_import_partial() async {
+  Future<void> test_import_partial() async {
     addTestSource('imp^ import "package:foo/foo.dart"; import "bar.dart";');
     await computeSuggestions();
     expect(replacementOffset, 0);
@@ -1644,7 +1646,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_partial2() async {
+  Future<void> test_import_partial2() async {
     addTestSource('^imp import "package:foo/foo.dart";');
     await computeSuggestions();
     expect(replacementOffset, 0);
@@ -1654,7 +1656,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_partial3() async {
+  Future<void> test_import_partial3() async {
     addTestSource(' ^imp import "package:foo/foo.dart"; import "bar.dart";');
     await computeSuggestions();
     expect(replacementOffset, 1);
@@ -1664,7 +1666,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_partial4() async {
+  Future<void> test_import_partial4() async {
     addTestSource('^ imp import "package:foo/foo.dart";');
     await computeSuggestions();
     expect(replacementOffset, 0);
@@ -1674,7 +1676,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_partial5() async {
+  Future<void> test_import_partial5() async {
     addTestSource('library libA; imp^ import "package:foo/foo.dart";');
     await computeSuggestions();
     expect(replacementOffset, 14);
@@ -1684,7 +1686,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_import_partial6() async {
+  Future<void> test_import_partial6() async {
     addTestSource(
         'library bar; import "zoo.dart"; imp^ import "package:foo/foo.dart";');
     await computeSuggestions();
@@ -1695,69 +1697,69 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_integerLiteral_inArgumentList() async {
+  Future<void> test_integerLiteral_inArgumentList() async {
     addTestSource('main() { print(42^); }');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_integerLiteral_inListLiteral() async {
+  Future<void> test_integerLiteral_inListLiteral() async {
     addTestSource('main() { var items = [42^]; }');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_is_expression() async {
+  Future<void> test_is_expression() async {
     addTestSource('main() {if (x is^)}');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_is_expression_partial() async {
+  Future<void> test_is_expression_partial() async {
     addTestSource('main() {if (x i^)}');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_library() async {
+  Future<void> test_library() async {
     addTestSource('library foo;^');
     await computeSuggestions();
     assertSuggestKeywords(directiveAndDeclarationKeywords,
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_library_declaration() async {
+  Future<void> test_library_declaration() async {
     addTestSource('library ^');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_library_declaration2() async {
+  Future<void> test_library_declaration2() async {
     addTestSource('library a^');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_library_declaration3() async {
+  Future<void> test_library_declaration3() async {
     addTestSource('library a.^');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_library_name() async {
+  Future<void> test_library_name() async {
     addTestSource('library ^');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_method_async() async {
+  Future<void> test_method_async() async {
     addTestSource('class A { foo() ^}');
     await computeSuggestions();
     assertSuggestKeywords(classBodyKeywords,
         pseudoKeywords: ['async', 'async*', 'sync*']);
   }
 
-  test_method_async2() async {
+  Future<void> test_method_async2() async {
     addTestSource('class A { foo() ^{}}');
     await computeSuggestions();
     assertSuggestKeywords([],
@@ -1765,14 +1767,14 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_method_async3() async {
+  Future<void> test_method_async3() async {
     addTestSource('class A { foo() a^}');
     await computeSuggestions();
     assertSuggestKeywords(classBodyKeywords,
         pseudoKeywords: ['async', 'async*', 'sync*']);
   }
 
-  test_method_async4() async {
+  Future<void> test_method_async4() async {
     addTestSource('class A { foo() a^{}}');
     await computeSuggestions();
     assertSuggestKeywords([],
@@ -1780,262 +1782,262 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_method_async5() async {
+  Future<void> test_method_async5() async {
     addTestSource('class A { foo() ^ Foo foo;}');
     await computeSuggestions();
     assertSuggestKeywords(classBodyKeywords,
         pseudoKeywords: ['async', 'async*', 'sync*']);
   }
 
-  test_method_async6() async {
+  Future<void> test_method_async6() async {
     addTestSource('class A { foo() a^ Foo foo;}');
     await computeSuggestions();
     assertSuggestKeywords(classBodyKeywords,
         pseudoKeywords: ['async', 'async*', 'sync*']);
   }
 
-  test_method_async7() async {
+  Future<void> test_method_async7() async {
     addTestSource('class A { foo() ^ => Foo foo;}');
     await computeSuggestions();
     assertSuggestKeywords([],
         pseudoKeywords: ['async'], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_method_async8() async {
+  Future<void> test_method_async8() async {
     addTestSource('class A { foo() a^ Foo foo;}');
     await computeSuggestions();
     assertSuggestKeywords(classBodyKeywords,
         pseudoKeywords: ['async', 'async*', 'sync*']);
   }
 
-  test_method_body() async {
+  Future<void> test_method_body() async {
     addTestSource('class A { foo() {^}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInClass);
   }
 
-  test_method_body2() async {
+  Future<void> test_method_body2() async {
     addTestSource('class A { foo() => ^}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE);
   }
 
-  test_method_body3() async {
+  Future<void> test_method_body3() async {
     addTestSource('class A { foo() => ^ Foo foo;}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE);
   }
 
-  test_method_body4() async {
+  Future<void> test_method_body4() async {
     addTestSource('class A { foo() => ^;}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE);
   }
 
-  test_method_body_async() async {
+  Future<void> test_method_body_async() async {
     addTestSource('class A { foo() async {^}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInClass, pseudoKeywords: ['await']);
   }
 
-  test_method_body_async2() async {
+  Future<void> test_method_body_async2() async {
     addTestSource('class A { foo() async => ^}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE, pseudoKeywords: ['await']);
   }
 
-  test_method_body_async3() async {
+  Future<void> test_method_body_async3() async {
     addTestSource('class A { foo() async => ^ Foo foo;}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE, pseudoKeywords: ['await']);
   }
 
-  test_method_body_async4() async {
+  Future<void> test_method_body_async4() async {
     addTestSource('class A { foo() async => ^;}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE, pseudoKeywords: ['await']);
   }
 
-  test_method_body_async_star() async {
+  Future<void> test_method_body_async_star() async {
     addTestSource('class A { foo() async* {^}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInClass,
         pseudoKeywords: ['await', 'yield', 'yield*']);
   }
 
-  test_method_body_expression1() async {
+  Future<void> test_method_body_expression1() async {
     addTestSource('class A { foo() {return b == true ? ^}}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE);
   }
 
-  test_method_body_expression2() async {
+  Future<void> test_method_body_expression2() async {
     addTestSource('class A { foo() {return b == true ? 1 : ^}}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE);
   }
 
-  test_method_body_return() async {
+  Future<void> test_method_body_return() async {
     addTestSource('class A { foo() {return ^}}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_INSTANCE);
   }
 
-  test_method_invocation() async {
+  Future<void> test_method_invocation() async {
     addTestSource('class A { foo() {bar.^}}');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_method_invocation2() async {
+  Future<void> test_method_invocation2() async {
     addTestSource('class A { foo() {bar.as^}}');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_method_param_named_init() async {
+  Future<void> test_method_param_named_init() async {
     addTestSource('class A { foo({bool bar: ^}) {}}');
     await computeSuggestions();
     expect(suggestions, isNotEmpty);
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_method_param_named_init2() async {
+  Future<void> test_method_param_named_init2() async {
     addTestSource('class A { foo({bool bar: f^}) {}}');
     await computeSuggestions();
     expect(suggestions, isNotEmpty);
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_method_param_noPrefix() async {
+  Future<void> test_method_param_noPrefix() async {
     addTestSource('class A { foo(^) {});}');
     await computeSuggestions();
     expect(suggestions, isNotEmpty);
     assertSuggestKeywords(methodParameter);
   }
 
-  test_method_param_positional_init() async {
+  Future<void> test_method_param_positional_init() async {
     addTestSource('class A { foo([bool bar = ^]) {}}');
     await computeSuggestions();
     expect(suggestions, isNotEmpty);
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_method_param_positional_init2() async {
+  Future<void> test_method_param_positional_init2() async {
     addTestSource('class A { foo([bool bar = f^]) {}}');
     await computeSuggestions();
     expect(suggestions, isNotEmpty);
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_method_param_prefix() async {
+  Future<void> test_method_param_prefix() async {
     addTestSource('class A { foo(t^) {});}');
     await computeSuggestions();
     expect(suggestions, isNotEmpty);
     assertSuggestKeywords(methodParameter);
   }
 
-  test_mixin() async {
+  Future<void> test_mixin() async {
     addTestSource('mixin M o^ { }');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.ON, Keyword.IMPLEMENTS],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_mixin_afterOnClause() async {
+  Future<void> test_mixin_afterOnClause() async {
     addTestSource('mixin M on A i^ { } class A {}');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.IMPLEMENTS], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_named_constructor_invocation() async {
+  Future<void> test_named_constructor_invocation() async {
     addTestSource('void main() {new Future.^}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_newInstance() async {
+  Future<void> test_newInstance() async {
     addTestSource('class A { foo() {new ^}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_newInstance2() async {
+  Future<void> test_newInstance2() async {
     addTestSource('class A { foo() {new ^ print("foo");}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_newInstance_prefixed() async {
+  Future<void> test_newInstance_prefixed() async {
     addTestSource('class A { foo() {new A.^}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_newInstance_prefixed2() async {
+  Future<void> test_newInstance_prefixed2() async {
     addTestSource('class A { foo() {new A.^ print("foo");}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_part_of() async {
+  Future<void> test_part_of() async {
     addTestSource('part of foo;^');
     await computeSuggestions();
     assertSuggestKeywords(directiveAndDeclarationKeywords,
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_partial_class() async {
+  Future<void> test_partial_class() async {
     addTestSource('cl^');
     await computeSuggestions();
     assertSuggestKeywords(directiveDeclarationAndLibraryKeywords,
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_partial_class2() async {
+  Future<void> test_partial_class2() async {
     addTestSource('library a; cl^');
     await computeSuggestions();
     assertSuggestKeywords(directiveAndDeclarationKeywords,
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_prefixed_field() async {
+  Future<void> test_prefixed_field() async {
     addTestSource('class A { int x; foo() {x.^}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_prefixed_field2() async {
+  Future<void> test_prefixed_field2() async {
     addTestSource('class A { int x; foo() {x.^ print("foo");}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_prefixed_library() async {
+  Future<void> test_prefixed_library() async {
     addTestSource('import "b" as b; class A { foo() {b.^}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_prefixed_local() async {
+  Future<void> test_prefixed_local() async {
     addTestSource('class A { foo() {int x; x.^}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_prefixed_local2() async {
+  Future<void> test_prefixed_local2() async {
     addTestSource('class A { foo() {int x; x.^ print("foo");}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_property_access() async {
+  Future<void> test_property_access() async {
     addTestSource('class A { get x => 7; foo() {new A().^}}');
     await computeSuggestions();
     assertSuggestKeywords([]);
   }
 
-  test_spreadElement() async {
+  Future<void> test_spreadElement() async {
     addTestSource('''
 f() => [...^];
 ''');
@@ -2043,53 +2045,53 @@
     assertSuggestKeywords(KeywordContributorTest.EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_switch_expression() async {
+  Future<void> test_switch_expression() async {
     addTestSource('main() {switch(^) {}}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_switch_expression2() async {
+  Future<void> test_switch_expression2() async {
     addTestSource('main() {switch(n^) {}}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_switch_expression3() async {
+  Future<void> test_switch_expression3() async {
     addTestSource('main() {switch(n^)}');
     await computeSuggestions();
     assertSuggestKeywords(EXPRESSION_START_NO_INSTANCE);
   }
 
-  test_switch_start() async {
+  Future<void> test_switch_start() async {
     addTestSource('main() {switch(1) {^}}');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.CASE, Keyword.DEFAULT],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_switch_start2() async {
+  Future<void> test_switch_start2() async {
     addTestSource('main() {switch(1) {^ case 1:}}');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.CASE, Keyword.DEFAULT],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_switch_start3() async {
+  Future<void> test_switch_start3() async {
     addTestSource('main() {switch(1) {^default:}}');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.CASE, Keyword.DEFAULT],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_switch_start4() async {
+  Future<void> test_switch_start4() async {
     addTestSource('main() {switch(1) {^ default:}}');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.CASE, Keyword.DEFAULT],
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_switch_start5() async {
+  Future<void> test_switch_start5() async {
     addTestSource('main() {switch(1) {c^ default:}}');
     await computeSuggestions();
     expect(replacementOffset, 19);
@@ -2098,7 +2100,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_switch_start6() async {
+  Future<void> test_switch_start6() async {
     addTestSource('main() {switch(1) {c^}}');
     await computeSuggestions();
     expect(replacementOffset, 19);
@@ -2107,7 +2109,7 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_switch_start7() async {
+  Future<void> test_switch_start7() async {
     addTestSource('main() {switch(1) { c^ }}');
     await computeSuggestions();
     expect(replacementOffset, 20);
@@ -2116,38 +2118,38 @@
         relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_switch_statement_case_break_insideClass() async {
+  Future<void> test_switch_statement_case_break_insideClass() async {
     addTestSource('class A{foo() {switch(1) {case 1: b^}}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInSwitchCaseInClass);
   }
 
-  test_switch_statement_case_break_outsideClass() async {
+  Future<void> test_switch_statement_case_break_outsideClass() async {
     addTestSource('foo() {switch(1) {case 1: b^}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInSwitchCaseOutsideClass);
   }
 
-  test_switch_statement_insideClass() async {
+  Future<void> test_switch_statement_insideClass() async {
     addTestSource('class A{foo() {switch(1) {case 1:^}}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInSwitchInClass);
   }
 
-  test_switch_statement_outsideClass() async {
+  Future<void> test_switch_statement_outsideClass() async {
     addTestSource('main() {switch(1) {case 1:^}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInSwitchOutsideClass);
   }
 
-  test_while_break_continue() async {
+  Future<void> test_while_break_continue() async {
     addTestSource('main() {while (true) {^}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInLoopOutsideClass,
         relevance: DART_RELEVANCE_KEYWORD);
   }
 
-  test_while_break_continue2() async {
+  Future<void> test_while_break_continue2() async {
     addTestSource('class A {foo() {while (true) {^}}}');
     await computeSuggestions();
     assertSuggestKeywords(statementStartInLoopInClass,
@@ -2191,31 +2193,31 @@
     createAnalysisOptionsFile(experiments: [EnableString.extension_methods]);
   }
 
-  test_class_body_empty() async {
+  Future<void> test_class_body_empty() async {
     addTestSource('extension E on int {^}');
     await computeSuggestions();
     assertSuggestKeywords(extensionBodyKeywords);
   }
 
-  test_extension_body_beginning() async {
+  Future<void> test_extension_body_beginning() async {
     addTestSource('extension E on int {^ foo() {}}');
     await computeSuggestions();
     assertSuggestKeywords(extensionBodyKeywords);
   }
 
-  test_extension_body_between() async {
+  Future<void> test_extension_body_between() async {
     addTestSource('extension E on int {foo() {} ^ void bar() {}}');
     await computeSuggestions();
     assertSuggestKeywords(extensionBodyKeywords);
   }
 
-  test_extension_body_end() async {
+  Future<void> test_extension_body_end() async {
     addTestSource('extension E on int {foo() {} ^}');
     await computeSuggestions();
     assertSuggestKeywords(extensionBodyKeywords);
   }
 
-  test_extension_member_const_afterStatic() async {
+  Future<void> test_extension_member_const_afterStatic() async {
     addTestSource('''
 extension E on int {
   static c^
@@ -2225,7 +2227,7 @@
     assertSuggestKeywords(staticMember);
   }
 
-  test_extension_member_final_afterStatic() async {
+  Future<void> test_extension_member_final_afterStatic() async {
     addTestSource('''
 extension E on int {
   static f^
@@ -2235,19 +2237,19 @@
     assertSuggestKeywords(staticMember);
   }
 
-  test_extension_noBody_named() async {
+  Future<void> test_extension_noBody_named() async {
     addTestSource('extension E ^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.ON], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_extension_noBody_unnamed() async {
+  Future<void> test_extension_noBody_unnamed() async {
     addTestSource('extension ^');
     await computeSuggestions();
     assertSuggestKeywords([Keyword.ON], relevance: DART_RELEVANCE_HIGH);
   }
 
-  test_method_type_params() async {
+  Future<void> test_method_type_params() async {
     addTestSource('''
 void f<T>() {}
 
diff --git a/pkg/analysis_server/test/services/completion/dart/label_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/label_contributor_test.dart
index 99e55eb..e6a7f5b 100644
--- a/pkg/analysis_server/test/services/completion/dart/label_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/label_contributor_test.dart
@@ -10,7 +10,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LabelContributorTest);
   });
@@ -40,7 +40,7 @@
     return LabelContributor();
   }
 
-  test_break_ignores_outer_functions_using_closure() async {
+  Future<void> test_break_ignores_outer_functions_using_closure() async {
     addTestSource('''
 void main() {
   foo: while (true) {
@@ -56,7 +56,7 @@
     assertNotSuggested('foo');
   }
 
-  test_break_ignores_outer_functions_using_local_function() async {
+  Future<void> test_break_ignores_outer_functions_using_local_function() async {
     addTestSource('''
 void main() {
   foo: while (true) {
@@ -72,7 +72,7 @@
     assertNotSuggested('foo');
   }
 
-  test_break_ignores_toplevel_variables() async {
+  Future<void> test_break_ignores_toplevel_variables() async {
     addTestSource('''
 int x;
 void main() {
@@ -85,7 +85,7 @@
     assertNotSuggested('x');
   }
 
-  test_break_ignores_unrelated_statements() async {
+  Future<void> test_break_ignores_unrelated_statements() async {
     addTestSource('''
 void main() {
   foo: while (true) {}
@@ -101,7 +101,7 @@
     assertNotSuggested('bar');
   }
 
-  test_break_to_enclosing_loop() async {
+  Future<void> test_break_to_enclosing_loop() async {
     addTestSource('''
 void main() {
   foo: while (true) {
@@ -116,7 +116,7 @@
     assertSuggestLabel('bar');
   }
 
-  test_continue_from_loop_to_switch() async {
+  Future<void> test_continue_from_loop_to_switch() async {
     addTestSource('''
 void main() {
   switch (x) {
@@ -138,7 +138,7 @@
     assertSuggestLabel('baz');
   }
 
-  test_continue_from_switch_to_loop() async {
+  Future<void> test_continue_from_switch_to_loop() async {
     addTestSource('''
 void main() {
   foo: while (true) {
@@ -153,7 +153,8 @@
     assertSuggestLabel('foo');
   }
 
-  test_continue_ignores_outer_functions_using_closure_with_loop() async {
+  Future<void>
+      test_continue_ignores_outer_functions_using_closure_with_loop() async {
     addTestSource('''
 void main() {
   foo: while (true) {
@@ -169,7 +170,8 @@
     assertNotSuggested('foo');
   }
 
-  test_continue_ignores_outer_functions_using_closure_with_switch() async {
+  Future<void>
+      test_continue_ignores_outer_functions_using_closure_with_switch() async {
     addTestSource('''
 void main() {
   switch (x) {
@@ -186,7 +188,8 @@
     assertNotSuggested('foo');
   }
 
-  test_continue_ignores_outer_functions_using_local_function_with_loop() async {
+  Future<void>
+      test_continue_ignores_outer_functions_using_local_function_with_loop() async {
     addTestSource('''
 void main() {
   foo: while (true) {
@@ -202,7 +205,8 @@
     assertNotSuggested('foo');
   }
 
-  test_continue_ignores_outer_functions_using_local_function_with_switch() async {
+  Future<void>
+      test_continue_ignores_outer_functions_using_local_function_with_switch() async {
     addTestSource('''
 void main() {
   switch (x) {
@@ -219,7 +223,7 @@
     assertNotSuggested('foo');
   }
 
-  test_continue_ignores_unrelated_statements() async {
+  Future<void> test_continue_ignores_unrelated_statements() async {
     addTestSource('''
 void main() {
   foo: while (true) {}
@@ -235,7 +239,7 @@
     assertNotSuggested('bar');
   }
 
-  test_continue_to_earlier_case() async {
+  Future<void> test_continue_to_earlier_case() async {
     addTestSource('''
 void main() {
   switch (x) {
@@ -250,7 +254,7 @@
     assertSuggestLabel('foo');
   }
 
-  test_continue_to_enclosing_loop() async {
+  Future<void> test_continue_to_enclosing_loop() async {
     addTestSource('''
 void main() {
   foo: while (true) {
@@ -265,7 +269,7 @@
     assertSuggestLabel('bar');
   }
 
-  test_continue_to_enclosing_switch() async {
+  Future<void> test_continue_to_enclosing_switch() async {
     addTestSource('''
 void main() {
   switch (x) {
@@ -288,7 +292,7 @@
     assertSuggestLabel('baz');
   }
 
-  test_continue_to_later_case() async {
+  Future<void> test_continue_to_later_case() async {
     addTestSource('''
 void main() {
   switch (x) {
@@ -303,7 +307,7 @@
     assertSuggestLabel('foo');
   }
 
-  test_continue_to_same_case() async {
+  Future<void> test_continue_to_same_case() async {
     addTestSource('''
 void main() {
   switch (x) {
diff --git a/pkg/analysis_server/test/services/completion/dart/library_member_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/library_member_contributor_test.dart
index a02d8b9..3e6ea08 100644
--- a/pkg/analysis_server/test/services/completion/dart/library_member_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/library_member_contributor_test.dart
@@ -10,7 +10,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
 //    defineReflectiveTests(LibraryMemberContributorTest);
     defineReflectiveTests(LibraryMemberContributorWithExtensionMethodsTest);
@@ -24,7 +24,7 @@
     return LibraryMemberContributor();
   }
 
-  test_libraryPrefix() async {
+  Future<void> test_libraryPrefix() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('import "dart:async" as bar; foo() {bar.^}');
     await computeSuggestions();
@@ -32,14 +32,14 @@
     assertNotSuggested('loadLibrary');
   }
 
-  test_libraryPrefix2() async {
+  Future<void> test_libraryPrefix2() async {
     // SimpleIdentifier  MethodInvocation  ExpressionStatement
     addTestSource('import "dart:async" as bar; foo() {bar.^ print("f")}');
     await computeSuggestions();
     assertSuggestClass('Future');
   }
 
-  test_libraryPrefix3() async {
+  Future<void> test_libraryPrefix3() async {
     // SimpleIdentifier  MethodInvocation  ExpressionStatement
     addTestSource('import "dart:async" as bar; foo() {new bar.F^ print("f")}');
     await computeSuggestions();
@@ -47,7 +47,7 @@
     assertSuggestConstructor('Future.delayed');
   }
 
-  test_libraryPrefix_cascade() async {
+  Future<void> test_libraryPrefix_cascade() async {
     addTestSource('''
     import "dart:math" as math;
     main() {math..^}''');
@@ -55,7 +55,7 @@
     assertNoSuggestions();
   }
 
-  test_libraryPrefix_cascade2() async {
+  Future<void> test_libraryPrefix_cascade2() async {
     addTestSource('''
     import "dart:math" as math;
     main() {math.^.}''');
@@ -63,7 +63,7 @@
     assertSuggestFunction('min', 'T');
   }
 
-  test_libraryPrefix_cascade3() async {
+  Future<void> test_libraryPrefix_cascade3() async {
     addTestSource('''
     import "dart:math" as math;
     main() {math..^a}''');
@@ -71,7 +71,7 @@
     assertNoSuggestions();
   }
 
-  test_libraryPrefix_cascade4() async {
+  Future<void> test_libraryPrefix_cascade4() async {
     addTestSource('''
     import "dart:math" as math;
     main() {math.^.a}''');
@@ -79,7 +79,7 @@
     assertSuggestFunction('min', 'T');
   }
 
-  test_libraryPrefix_deferred() async {
+  Future<void> test_libraryPrefix_deferred() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('import "dart:async" deferred as bar; foo() {bar.^}');
     await computeSuggestions();
@@ -87,7 +87,7 @@
     assertSuggestFunction('loadLibrary', 'Future<dynamic>');
   }
 
-  test_libraryPrefix_deferred_inPart() async {
+  Future<void> test_libraryPrefix_deferred_inPart() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
         library testA;
@@ -101,7 +101,7 @@
     assertNotSuggested('foo');
   }
 
-  test_libraryPrefix_with_exports() async {
+  Future<void> test_libraryPrefix_with_exports() async {
     addSource('/home/test/lib/a.dart', 'library libA; class A { }');
     addSource('/home/test/lib/b.dart', '''
         library libB;
@@ -116,7 +116,7 @@
     assertNotSuggested('C');
   }
 
-  test_PrefixedIdentifier_library() async {
+  Future<void> test_PrefixedIdentifier_library() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -141,7 +141,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_export_withShow() async {
+  Future<void> test_PrefixedIdentifier_library_export_withShow() async {
     addSource('/home/test/lib/a.dart', r'''
 class A {}
 class B {}
@@ -160,7 +160,7 @@
     assertNotSuggested('B');
   }
 
-  test_PrefixedIdentifier_library_import_withShow() async {
+  Future<void> test_PrefixedIdentifier_library_import_withShow() async {
     addSource('/home/test/lib/a.dart', r'''
 class A {}
 class B {}
@@ -176,7 +176,7 @@
     assertNotSuggested('B');
   }
 
-  test_PrefixedIdentifier_library_inPart() async {
+  Future<void> test_PrefixedIdentifier_library_inPart() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -206,7 +206,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_typesOnly() async {
+  Future<void> test_PrefixedIdentifier_library_typesOnly() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -231,7 +231,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_typesOnly2() async {
+  Future<void> test_PrefixedIdentifier_library_typesOnly2() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -256,7 +256,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_parameter() async {
+  Future<void> test_PrefixedIdentifier_parameter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -270,7 +270,7 @@
     assertNoSuggestions();
   }
 
-  test_PrefixedIdentifier_prefix() async {
+  Future<void> test_PrefixedIdentifier_prefix() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
         class A {static int bar = 10;}
@@ -297,7 +297,7 @@
     createAnalysisOptionsFile(experiments: [EnableString.extension_methods]);
   }
 
-  test_extension() async {
+  Future<void> test_extension() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
 extension MyExt on int {}
diff --git a/pkg/analysis_server/test/services/completion/dart/library_prefix_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/library_prefix_contributor_test.dart
index 2ecf6a6..1891fbf 100644
--- a/pkg/analysis_server/test/services/completion/dart/library_prefix_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/library_prefix_contributor_test.dart
@@ -10,7 +10,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LibraryPrefixContributorTest);
   });
@@ -40,7 +40,7 @@
     return LibraryPrefixContributor();
   }
 
-  test_Block() async {
+  Future<void> test_Block() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/ab.dart', '''
 export "dart:math" hide max;
@@ -87,7 +87,7 @@
     assertSuggestLibraryPrefixes(['g']);
   }
 
-  test_Block_final_final() async {
+  Future<void> test_Block_final_final() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testAB.dart', '''
 export "dart:math" hide max;
@@ -134,7 +134,7 @@
     assertSuggestLibraryPrefixes(['g']);
   }
 
-  test_Block_final_var() async {
+  Future<void> test_Block_final_var() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testAB.dart', '''
 export "dart:math" hide max;
@@ -181,7 +181,7 @@
     assertSuggestLibraryPrefixes(['g']);
   }
 
-  test_ClassDeclaration_body() async {
+  Future<void> test_ClassDeclaration_body() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -196,7 +196,7 @@
     assertSuggestLibraryPrefixes(['x']);
   }
 
-  test_ClassDeclaration_body_final() async {
+  Future<void> test_ClassDeclaration_body_final() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -211,7 +211,7 @@
     assertSuggestLibraryPrefixes(['x']);
   }
 
-  test_ClassDeclaration_body_final_field() async {
+  Future<void> test_ClassDeclaration_body_final_field() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -226,7 +226,7 @@
     assertSuggestLibraryPrefixes(['x']);
   }
 
-  test_ClassDeclaration_body_final_field2() async {
+  Future<void> test_ClassDeclaration_body_final_field2() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -241,7 +241,7 @@
     assertSuggestLibraryPrefixes(['Soo']);
   }
 
-  test_ClassDeclaration_body_final_final() async {
+  Future<void> test_ClassDeclaration_body_final_final() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -256,7 +256,7 @@
     assertSuggestLibraryPrefixes(['x']);
   }
 
-  test_ClassDeclaration_body_final_var() async {
+  Future<void> test_ClassDeclaration_body_final_var() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -271,7 +271,7 @@
     assertSuggestLibraryPrefixes(['x']);
   }
 
-  test_InstanceCreationExpression() async {
+  Future<void> test_InstanceCreationExpression() async {
     addSource('/home/test/lib/a.dart', '''
 class A {foo(){var f; {var x;}}}
 class B {B(this.x, [String boo]) { } int x;}
@@ -284,13 +284,13 @@
     assertSuggestLibraryPrefixes(['math', 't']);
   }
 
-  test_InstanceCreationExpression2() async {
+  Future<void> test_InstanceCreationExpression2() async {
     addTestSource('import "dart:convert" as json;f() {var x=new js^}');
     await computeSuggestions();
     assertSuggestLibraryPrefixes(['json']);
   }
 
-  test_InstanceCreationExpression_inPart() async {
+  Future<void> test_InstanceCreationExpression_inPart() async {
     addSource('/home/test/lib/a.dart', '''
 class A {foo(){var f; {var x;}}}
 class B {B(this.x, [String boo]) { } int x;}
@@ -308,7 +308,7 @@
     assertSuggestLibraryPrefixes(['math', 't']);
   }
 
-  test_InstanceCreationExpression_inPart_detached() async {
+  Future<void> test_InstanceCreationExpression_inPart_detached() async {
     addSource('/home/test/lib/a.dart', '''
 class A {foo(){var f; {var x;}}}
 class B {B(this.x, [String boo]) { } int x;}
diff --git a/pkg/analysis_server/test/services/completion/dart/local_constructor_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/local_constructor_contributor_test.dart
index f7ae6b1..8e5f5cb 100644
--- a/pkg/analysis_server/test/services/completion/dart/local_constructor_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/local_constructor_contributor_test.dart
@@ -10,7 +10,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LocalConstructorContributorTest);
   });
@@ -55,7 +55,7 @@
   }
 
   /// Sanity check.  Permutations tested in local_ref_contributor.
-  test_ArgDefaults_cons_with_required_named() async {
+  Future<void> test_ArgDefaults_cons_with_required_named() async {
     addMetaPackage();
     addTestSource('''
 import 'package:meta/meta.dart';
@@ -71,7 +71,7 @@
     assertSuggestConstructor('A', defaultArgListString: 'bar, baz: null');
   }
 
-  test_ArgumentList() async {
+  Future<void> test_ArgumentList() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -100,7 +100,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_imported_function() async {
+  Future<void> test_ArgumentList_imported_function() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -130,7 +130,8 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_InstanceCreationExpression_functionalArg() async {
+  Future<void>
+      test_ArgumentList_InstanceCreationExpression_functionalArg() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -162,7 +163,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_InstanceCreationExpression_typedefArg() async {
+  Future<void> test_ArgumentList_InstanceCreationExpression_typedefArg() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -195,7 +196,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_local_function() async {
+  Future<void> test_ArgumentList_local_function() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -225,7 +226,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_local_method() async {
+  Future<void> test_ArgumentList_local_method() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -255,7 +256,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_MethodInvocation_functionalArg() async {
+  Future<void> test_ArgumentList_MethodInvocation_functionalArg() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -287,7 +288,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_MethodInvocation_methodArg() async {
+  Future<void> test_ArgumentList_MethodInvocation_methodArg() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -317,7 +318,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_namedParam() async {
+  Future<void> test_ArgumentList_namedParam() async {
     // SimpleIdentifier  NamedExpression  ArgumentList  MethodInvocation
     // ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
@@ -336,7 +337,7 @@
     assertNotSuggested('main');
   }
 
-  test_AsExpression() async {
+  Future<void> test_AsExpression() async {
     // SimpleIdentifier  TypeName  AsExpression
     addTestSource('''
         class A {var b; X _c; foo() {var a; (a as ^).foo();}''');
@@ -351,7 +352,7 @@
     assertNotSuggested('==');
   }
 
-  test_AssignmentExpression_name() async {
+  Future<void> test_AssignmentExpression_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('class A {} main() {int a; int ^b = 1;}');
@@ -360,7 +361,7 @@
     assertNoSuggestions();
   }
 
-  test_AssignmentExpression_RHS() async {
+  Future<void> test_AssignmentExpression_RHS() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('class A {} main() {int a; int b = ^}');
@@ -378,7 +379,7 @@
     assertNotSuggested('Object');
   }
 
-  test_AssignmentExpression_type() async {
+  Future<void> test_AssignmentExpression_type() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -406,7 +407,7 @@
     //assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_newline() async {
+  Future<void> test_AssignmentExpression_type_newline() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -433,7 +434,7 @@
     assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_partial() async {
+  Future<void> test_AssignmentExpression_type_partial() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -461,7 +462,7 @@
     //assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_partial_newline() async {
+  Future<void> test_AssignmentExpression_type_partial_newline() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -488,7 +489,7 @@
     assertNotSuggested('identical');
   }
 
-  test_AwaitExpression() async {
+  Future<void> test_AwaitExpression() async {
     // SimpleIdentifier  AwaitExpression  ExpressionStatement
     addTestSource('''
 class A {int x; int y() => 0;}
@@ -507,7 +508,7 @@
     assertNotSuggested('Object');
   }
 
-  test_BinaryExpression_LHS() async {
+  Future<void> test_BinaryExpression_LHS() async {
     // SimpleIdentifier  BinaryExpression  VariableDeclaration
     // VariableDeclarationList  VariableDeclarationStatement
     addTestSource('main() {int a = 1, b = ^ + 2;}');
@@ -520,7 +521,7 @@
     assertNotSuggested('b');
   }
 
-  test_BinaryExpression_RHS() async {
+  Future<void> test_BinaryExpression_RHS() async {
     // SimpleIdentifier  BinaryExpression  VariableDeclaration
     // VariableDeclarationList  VariableDeclarationStatement
     addTestSource('main() {int a = 1, b = 2 + ^;}');
@@ -534,7 +535,7 @@
     assertNotSuggested('==');
   }
 
-  test_Block() async {
+  Future<void> test_Block() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testAB.dart', '''
 export "dart:math" hide max;
@@ -632,7 +633,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final() async {
+  Future<void> test_Block_final() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testAB.dart', '''
 export "dart:math" hide max;
@@ -731,21 +732,21 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final2() async {
+  Future<void> test_Block_final2() async {
     addTestSource('main() {final S^ v;}');
     await computeSuggestions();
 
     assertNotSuggested('String');
   }
 
-  test_Block_final3() async {
+  Future<void> test_Block_final3() async {
     addTestSource('main() {final ^ v;}');
     await computeSuggestions();
 
     assertNotSuggested('String');
   }
 
-  test_Block_final_final() async {
+  Future<void> test_Block_final_final() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testAB.dart', '''
 export "dart:math" hide max;
@@ -844,7 +845,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final_var() async {
+  Future<void> test_Block_final_var() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testAB.dart', '''
 export "dart:math" hide max;
@@ -943,7 +944,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_identifier_partial() async {
+  Future<void> test_Block_identifier_partial() async {
     addSource('/testAB.dart', '''
 export "dart:math" hide max;
 class A {int x;}
@@ -1026,7 +1027,7 @@
     assertNotSuggested('HtmlElement');
   }
 
-  test_Block_inherited_imported() async {
+  Future<void> test_Block_inherited_imported() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -1057,7 +1058,7 @@
     assertNotSuggested('==');
   }
 
-  test_Block_inherited_local() async {
+  Future<void> test_Block_inherited_local() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     addTestSource('''
 class F { var f1; f2() { } get f3 => 0; set f4(fx) { } }
@@ -1081,7 +1082,7 @@
     assertNotSuggested('m2');
   }
 
-  test_Block_local_function() async {
+  Future<void> test_Block_local_function() async {
     addSource('/testAB.dart', '''
 export "dart:math" hide max;
 class A {int x;}
@@ -1132,7 +1133,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_unimported() async {
+  Future<void> test_Block_unimported() async {
     addPackageFile('aaa', 'a.dart', 'class A {}');
     addTestSource('main() { ^ }');
 
@@ -1145,7 +1146,7 @@
     assertNotSuggested('Future');
   }
 
-  test_CascadeExpression_selector1() async {
+  Future<void> test_CascadeExpression_selector1() async {
     // PropertyAccess  CascadeExpression  ExpressionStatement  Block
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1170,7 +1171,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_selector2() async {
+  Future<void> test_CascadeExpression_selector2() async {
     // SimpleIdentifier  PropertyAccess  CascadeExpression  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1193,7 +1194,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_selector2_withTrailingReturn() async {
+  Future<void> test_CascadeExpression_selector2_withTrailingReturn() async {
     // PropertyAccess  CascadeExpression  ExpressionStatement  Block
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1216,7 +1217,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_target() async {
+  Future<void> test_CascadeExpression_target() async {
     // SimpleIdentifier  CascadeExpression  ExpressionStatement
     addTestSource('''
 class A {var b; X _c;}
@@ -1241,7 +1242,7 @@
     assertNotSuggested('==');
   }
 
-  test_CatchClause_onType() async {
+  Future<void> test_CatchClause_onType() async {
     // TypeName  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on ^ {}}}');
     await computeSuggestions();
@@ -1254,7 +1255,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_onType_noBrackets() async {
+  Future<void> test_CatchClause_onType_noBrackets() async {
     // TypeName  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on ^}}');
     await computeSuggestions();
@@ -1266,7 +1267,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_typed() async {
+  Future<void> test_CatchClause_typed() async {
     // Block  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on E catch (e) {^}}}');
     await computeSuggestions();
@@ -1279,7 +1280,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_untyped() async {
+  Future<void> test_CatchClause_untyped() async {
     // Block  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} catch (e, s) {^}}}');
     await computeSuggestions();
@@ -1293,7 +1294,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body() async {
+  Future<void> test_ClassDeclaration_body() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1314,7 +1315,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final() async {
+  Future<void> test_ClassDeclaration_body_final() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1335,7 +1336,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_field() async {
+  Future<void> test_ClassDeclaration_body_final_field() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1356,7 +1357,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_field2() async {
+  Future<void> test_ClassDeclaration_body_final_field2() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1377,7 +1378,7 @@
     assertNotSuggested('Soo');
   }
 
-  test_ClassDeclaration_body_final_final() async {
+  Future<void> test_ClassDeclaration_body_final_final() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1398,7 +1399,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_var() async {
+  Future<void> test_ClassDeclaration_body_final_var() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1419,7 +1420,7 @@
     assertNotSuggested('x');
   }
 
-  test_Combinator_hide() async {
+  Future<void> test_Combinator_hide() async {
     // SimpleIdentifier  HideCombinator  ImportDirective
     addSource('/testAB.dart', '''
 library libAB;
@@ -1443,7 +1444,7 @@
     assertNoSuggestions();
   }
 
-  test_Combinator_show() async {
+  Future<void> test_Combinator_show() async {
     // SimpleIdentifier  HideCombinator  ImportDirective
     addSource('/testAB.dart', '''
 library libAB;
@@ -1469,7 +1470,7 @@
     assertNoSuggestions();
   }
 
-  test_ConditionalExpression_elseExpression() async {
+  Future<void> test_ConditionalExpression_elseExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -1489,7 +1490,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_ConditionalExpression_elseExpression_empty() async {
+  Future<void> test_ConditionalExpression_elseExpression_empty() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -1519,7 +1520,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_ConditionalExpression_partial_thenExpression() async {
+  Future<void> test_ConditionalExpression_partial_thenExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -1539,7 +1540,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_ConditionalExpression_partial_thenExpression_empty() async {
+  Future<void> test_ConditionalExpression_partial_thenExpression_empty() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -1569,7 +1570,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_ConditionalExpression_thenExpression() async {
+  Future<void> test_ConditionalExpression_thenExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -1589,42 +1590,43 @@
     //assertNotSuggested('T1');
   }
 
-  test_constructor_parameters_mixed_required_and_named() async {
+  Future<void> test_constructor_parameters_mixed_required_and_named() async {
     addTestSource('class A {A(x, {int y}) {^}}');
     await computeSuggestions();
     assertNotSuggested('x');
     assertNotSuggested('y');
   }
 
-  test_constructor_parameters_mixed_required_and_positional() async {
+  Future<void>
+      test_constructor_parameters_mixed_required_and_positional() async {
     addTestSource('class A {A(x, [int y]) {^}}');
     await computeSuggestions();
     assertNotSuggested('x');
     assertNotSuggested('y');
   }
 
-  test_constructor_parameters_named() async {
+  Future<void> test_constructor_parameters_named() async {
     addTestSource('class A {A({x, int y}) {^}}');
     await computeSuggestions();
     assertNotSuggested('x');
     assertNotSuggested('y');
   }
 
-  test_constructor_parameters_positional() async {
+  Future<void> test_constructor_parameters_positional() async {
     addTestSource('class A {A([x, int y]) {^}}');
     await computeSuggestions();
     assertNotSuggested('x');
     assertNotSuggested('y');
   }
 
-  test_constructor_parameters_required() async {
+  Future<void> test_constructor_parameters_required() async {
     addTestSource('class A {A(x, int y) {^}}');
     await computeSuggestions();
     assertNotSuggested('x');
     assertNotSuggested('y');
   }
 
-  test_ConstructorName_importedClass() async {
+  Future<void> test_ConstructorName_importedClass() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -1649,7 +1651,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedFactory() async {
+  Future<void> test_ConstructorName_importedFactory() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -1674,7 +1676,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedFactory2() async {
+  Future<void> test_ConstructorName_importedFactory2() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -1692,7 +1694,7 @@
     assertNotSuggested('String');
   }
 
-  test_ConstructorName_localClass() async {
+  Future<void> test_ConstructorName_localClass() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -1713,7 +1715,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_localFactory() async {
+  Future<void> test_ConstructorName_localFactory() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -1734,7 +1736,7 @@
     assertNotSuggested('m');
   }
 
-  test_DefaultFormalParameter_named_expression() async {
+  Future<void> test_DefaultFormalParameter_named_expression() async {
     // DefaultFormalParameter FormalParameterList MethodDeclaration
     addTestSource('''
 foo() { }
@@ -1756,7 +1758,7 @@
     assertNotSuggested('bar');
   }
 
-  test_enum() async {
+  Future<void> test_enum() async {
     addTestSource('enum E { one, two } main() {^}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -1764,7 +1766,7 @@
     assertNotSuggested('two');
   }
 
-  test_enum_deprecated() async {
+  Future<void> test_enum_deprecated() async {
     addTestSource('@deprecated enum E { one, two } main() {^}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -1772,7 +1774,7 @@
     assertNotSuggested('two');
   }
 
-  test_ExpressionStatement_identifier() async {
+  Future<void> test_ExpressionStatement_identifier() async {
     // SimpleIdentifier  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 _B F1() { }
@@ -1802,7 +1804,7 @@
     assertNotSuggested('_B');
   }
 
-  test_ExpressionStatement_name() async {
+  Future<void> test_ExpressionStatement_name() async {
     // ExpressionStatement  Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/a.dart', '''
         B T1;
@@ -1815,7 +1817,7 @@
     assertNoSuggestions();
   }
 
-  test_FieldDeclaration_name_typed() async {
+  Future<void> test_FieldDeclaration_name_typed() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // FieldDeclaration
     addSource('/home/test/lib/a.dart', 'class A { }');
@@ -1827,7 +1829,7 @@
     assertNoSuggestions();
   }
 
-  test_FieldDeclaration_name_var() async {
+  Future<void> test_FieldDeclaration_name_var() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // FieldDeclaration
     addSource('/home/test/lib/a.dart', 'class A { }');
@@ -1839,7 +1841,7 @@
     assertNoSuggestions();
   }
 
-  test_FieldFormalParameter_in_non_constructor() async {
+  Future<void> test_FieldFormalParameter_in_non_constructor() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('class A {B(this.^foo) {}}');
     await computeSuggestions();
@@ -1849,7 +1851,7 @@
     assertNoSuggestions();
   }
 
-  test_ForEachStatement_body_typed() async {
+  Future<void> test_ForEachStatement_body_typed() async {
     // Block  ForEachStatement
     addTestSource('main(args) {for (int foo in bar) {^}}');
     await computeSuggestions();
@@ -1861,7 +1863,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForEachStatement_body_untyped() async {
+  Future<void> test_ForEachStatement_body_untyped() async {
     // Block  ForEachStatement
     addTestSource('main(args) {for (foo in bar) {^}}');
     await computeSuggestions();
@@ -1873,7 +1875,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForEachStatement_iterable() async {
+  Future<void> test_ForEachStatement_iterable() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (int foo in ^) {}}');
     await computeSuggestions();
@@ -1884,7 +1886,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForEachStatement_loopVariable() async {
+  Future<void> test_ForEachStatement_loopVariable() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (^ in args) {}}');
     await computeSuggestions();
@@ -1895,7 +1897,7 @@
     assertNotSuggested('String');
   }
 
-  test_ForEachStatement_loopVariable_type() async {
+  Future<void> test_ForEachStatement_loopVariable_type() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (^ foo in args) {}}');
     await computeSuggestions();
@@ -1907,7 +1909,7 @@
     assertNotSuggested('String');
   }
 
-  test_ForEachStatement_loopVariable_type2() async {
+  Future<void> test_ForEachStatement_loopVariable_type2() async {
     // DeclaredIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (S^ foo in args) {}}');
     await computeSuggestions();
@@ -1919,7 +1921,7 @@
     assertNotSuggested('String');
   }
 
-  test_FormalParameterList() async {
+  Future<void> test_FormalParameterList() async {
     // FormalParameterList MethodDeclaration
     addTestSource('''
 foo() { }
@@ -1937,7 +1939,7 @@
     assertNotSuggested('bar');
   }
 
-  test_ForStatement_body() async {
+  Future<void> test_ForStatement_body() async {
     // Block  ForStatement
     addTestSource('main(args) {for (int i; i < 10; ++i) {^}}');
     await computeSuggestions();
@@ -1948,7 +1950,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForStatement_condition() async {
+  Future<void> test_ForStatement_condition() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {for (int index = 0; i^)}');
     await computeSuggestions();
@@ -1958,7 +1960,7 @@
     assertNotSuggested('index');
   }
 
-  test_ForStatement_initializer() async {
+  Future<void> test_ForStatement_initializer() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {List a; for (^)}');
     await computeSuggestions();
@@ -1970,7 +1972,7 @@
     assertNotSuggested('int');
   }
 
-  test_ForStatement_updaters() async {
+  Future<void> test_ForStatement_updaters() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {for (int index = 0; index < 10; i^)}');
     await computeSuggestions();
@@ -1980,7 +1982,7 @@
     assertNotSuggested('index');
   }
 
-  test_ForStatement_updaters_prefix_expression() async {
+  Future<void> test_ForStatement_updaters_prefix_expression() async {
     // SimpleIdentifier  PrefixExpression  ForStatement
     addTestSource('''
 void bar() { }
@@ -1994,7 +1996,7 @@
     assertNotSuggested('bar');
   }
 
-  test_function_parameters_mixed_required_and_named() async {
+  Future<void> test_function_parameters_mixed_required_and_named() async {
     addTestSource('''
 void m(x, {int y}) {}
 class B extends A {
@@ -2005,7 +2007,7 @@
     assertNotSuggested('m');
   }
 
-  test_function_parameters_mixed_required_and_positional() async {
+  Future<void> test_function_parameters_mixed_required_and_positional() async {
     addTestSource('''
 void m(x, [int y]) {}
 class B extends A {
@@ -2016,7 +2018,7 @@
     assertNotSuggested('m');
   }
 
-  test_function_parameters_named() async {
+  Future<void> test_function_parameters_named() async {
     addTestSource('''
 void m({x, int y}) {}
 class B extends A {
@@ -2027,7 +2029,7 @@
     assertNotSuggested('m');
   }
 
-  test_function_parameters_none() async {
+  Future<void> test_function_parameters_none() async {
     addTestSource('''
 void m() {}
 class B extends A {
@@ -2038,7 +2040,7 @@
     assertNotSuggested('m');
   }
 
-  test_function_parameters_positional() async {
+  Future<void> test_function_parameters_positional() async {
     addTestSource('''
 void m([x, int y]) {}
 class B extends A {
@@ -2049,7 +2051,7 @@
     assertNotSuggested('m');
   }
 
-  test_function_parameters_required() async {
+  Future<void> test_function_parameters_required() async {
     addTestSource('''
 void m(x, int y) {}
 class B extends A {
@@ -2060,7 +2062,7 @@
     assertNotSuggested('m');
   }
 
-  test_FunctionDeclaration_returnType_afterComment() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2090,7 +2092,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionDeclaration_returnType_afterComment2() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment2() async {
     // FunctionDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2120,7 +2122,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionDeclaration_returnType_afterComment3() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment3() async {
     // FunctionDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2151,7 +2153,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionExpression_body_function() async {
+  Future<void> test_FunctionExpression_body_function() async {
     // Block  BlockFunctionBody  FunctionExpression
     addTestSource('''
         void bar() { }
@@ -2167,7 +2169,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IfStatement() async {
+  Future<void> test_IfStatement() async {
     // SimpleIdentifier  IfStatement
     addTestSource('''
         class A {var b; X _c; foo() {A a; if (true) ^}}''');
@@ -2186,7 +2188,7 @@
     assertNotSuggested('==');
   }
 
-  test_IfStatement_condition() async {
+  Future<void> test_IfStatement_condition() async {
     // SimpleIdentifier  IfStatement  Block  BlockFunctionBody
     addTestSource('''
 class A {int x; int y() => 0;}
@@ -2205,7 +2207,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IfStatement_empty() async {
+  Future<void> test_IfStatement_empty() async {
     // SimpleIdentifier  IfStatement
     addTestSource('''
         class A {var b; X _c; foo() {A a; if (^) something}}''');
@@ -2224,7 +2226,7 @@
     assertNotSuggested('==');
   }
 
-  test_IfStatement_invocation() async {
+  Future<void> test_IfStatement_invocation() async {
     // SimpleIdentifier  PrefixIdentifier  IfStatement
     addTestSource('''
 main() {var a; if (a.^) something}''');
@@ -2238,14 +2240,14 @@
     assertNotSuggested('==');
   }
 
-  test_ignore_symbol_being_completed() async {
+  Future<void> test_ignore_symbol_being_completed() async {
     addTestSource('class MyClass { } main(MC^) { }');
     await computeSuggestions();
     assertNotSuggested('MyClass');
     assertNotSuggested('MC');
   }
 
-  test_ImportDirective_dart() async {
+  Future<void> test_ImportDirective_dart() async {
     // SimpleStringLiteral  ImportDirective
     addTestSource('''
 import "dart^";
@@ -2255,7 +2257,7 @@
     assertNoSuggestions();
   }
 
-  test_inDartDoc_reference1() async {
+  Future<void> test_inDartDoc_reference1() async {
     addTestSource('''
 /// The [^
 main(aaa, bbb) {}''');
@@ -2263,7 +2265,7 @@
     assertNotSuggested('main');
   }
 
-  test_inDartDoc_reference2() async {
+  Future<void> test_inDartDoc_reference2() async {
     addTestSource('''
 /// The [m^
 main(aaa, bbb) {}''');
@@ -2271,7 +2273,7 @@
     assertNotSuggested('main');
   }
 
-  test_inDartDoc_reference3() async {
+  Future<void> test_inDartDoc_reference3() async {
     addTestSource('''
 /// The [^]
 main(aaa, bbb) {}''');
@@ -2279,7 +2281,7 @@
     assertNotSuggested('main');
   }
 
-  test_inDartDoc_reference4() async {
+  Future<void> test_inDartDoc_reference4() async {
     addTestSource('''
 /// The [m^]
 main(aaa, bbb) {}''');
@@ -2287,7 +2289,7 @@
     assertNotSuggested('main');
   }
 
-  test_IndexExpression() async {
+  Future<void> test_IndexExpression() async {
     // ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2317,7 +2319,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_IndexExpression2() async {
+  Future<void> test_IndexExpression2() async {
     // SimpleIdentifier IndexExpression ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2337,7 +2339,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_InstanceCreationExpression() async {
+  Future<void> test_InstanceCreationExpression() async {
     addTestSource('''
 class A {foo(){var f; {var x;}}}
 class B {B(this.x, [String boo]) { } int x;}
@@ -2380,7 +2382,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_InstanceCreationExpression_abstractClass() async {
+  Future<void> test_InstanceCreationExpression_abstractClass() async {
     addTestSource('''
 abstract class A {
   A();
@@ -2398,7 +2400,8 @@
     assertSuggestConstructor('A.factory');
   }
 
-  test_InstanceCreationExpression_abstractClass_implicitConstructor() async {
+  Future<void>
+      test_InstanceCreationExpression_abstractClass_implicitConstructor() async {
     addTestSource('''
 abstract class A {}
 
@@ -2410,7 +2413,8 @@
     assertNotSuggested('A');
   }
 
-  test_InstanceCreationExpression_assignment_expression_filter() async {
+  Future<void>
+      test_InstanceCreationExpression_assignment_expression_filter() async {
     addTestSource('''
 class A {} class B extends A {} class C implements A {} class D {}
 main() {
@@ -2431,7 +2435,8 @@
     assertSuggestConstructor('D', elemOffset: -1);
   }
 
-  test_InstanceCreationExpression_assignment_expression_filter2() async {
+  Future<void>
+      test_InstanceCreationExpression_assignment_expression_filter2() async {
     addTestSource('''
 class A {} class B extends A {} class C implements A {} class D {}
 main() {
@@ -2452,7 +2457,7 @@
     assertSuggestConstructor('D', elemOffset: -1);
   }
 
-  test_InstanceCreationExpression_imported() async {
+  Future<void> test_InstanceCreationExpression_imported() async {
     // SimpleIdentifier  TypeName  ConstructorName  InstanceCreationExpression
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2483,7 +2488,7 @@
     assertNotSuggested('T2');
   }
 
-  test_InstanceCreationExpression_invocationArgument() async {
+  Future<void> test_InstanceCreationExpression_invocationArgument() async {
     addTestSource('''
 class A {} class B extends A {} class C {}
 void foo(A a) {}
@@ -2501,7 +2506,8 @@
     assertSuggestConstructor('C', elemOffset: -1);
   }
 
-  test_InstanceCreationExpression_invocationArgument_named() async {
+  Future<void>
+      test_InstanceCreationExpression_invocationArgument_named() async {
     addTestSource('''
 class A {} class B extends A {} class C {}
 void foo({A a}) {}
@@ -2519,7 +2525,7 @@
     assertSuggestConstructor('C', elemOffset: -1);
   }
 
-  test_InstanceCreationExpression_unimported() async {
+  Future<void> test_InstanceCreationExpression_unimported() async {
     // SimpleIdentifier  TypeName  ConstructorName  InstanceCreationExpression
     addSource('/testAB.dart', 'class Foo { }');
     addTestSource('class C {foo(){new F^}}');
@@ -2531,7 +2537,8 @@
     assertNotSuggested('Foo');
   }
 
-  test_InstanceCreationExpression_variable_declaration_filter() async {
+  Future<void>
+      test_InstanceCreationExpression_variable_declaration_filter() async {
     addTestSource('''
 class A {} class B extends A {} class C implements A {} class D {}
 main() {
@@ -2551,7 +2558,8 @@
     assertSuggestConstructor('D', elemOffset: -1);
   }
 
-  test_InstanceCreationExpression_variable_declaration_filter2() async {
+  Future<void>
+      test_InstanceCreationExpression_variable_declaration_filter2() async {
     addTestSource('''
 class A {} class B extends A {} class C implements A {} class D {}
 main() {
@@ -2571,7 +2579,7 @@
     assertSuggestConstructor('D', elemOffset: -1);
   }
 
-  test_InterpolationExpression() async {
+  Future<void> test_InterpolationExpression() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2605,7 +2613,7 @@
     assertNotSuggested('name');
   }
 
-  test_InterpolationExpression_block() async {
+  Future<void> test_InterpolationExpression_block() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2639,7 +2647,7 @@
     assertNotSuggested('name');
   }
 
-  test_InterpolationExpression_block2() async {
+  Future<void> test_InterpolationExpression_block2() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addTestSource('main() {String name; print("hello \${n^}");}');
     await computeSuggestions();
@@ -2649,7 +2657,7 @@
     //assertNotSuggested('Object');
   }
 
-  test_InterpolationExpression_prefix_selector() async {
+  Future<void> test_InterpolationExpression_prefix_selector() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \${name.^}");}');
     await computeSuggestions();
@@ -2662,7 +2670,7 @@
     assertNotSuggested('==');
   }
 
-  test_InterpolationExpression_prefix_selector2() async {
+  Future<void> test_InterpolationExpression_prefix_selector2() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \$name.^");}');
     await computeSuggestions();
@@ -2670,7 +2678,7 @@
     assertNoSuggestions();
   }
 
-  test_InterpolationExpression_prefix_target() async {
+  Future<void> test_InterpolationExpression_prefix_target() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \${nam^e.length}");}');
     await computeSuggestions();
@@ -2681,7 +2689,7 @@
     assertNotSuggested('length');
   }
 
-  test_IsExpression() async {
+  Future<void> test_IsExpression() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -2702,7 +2710,7 @@
     assertNotSuggested('foo');
   }
 
-  test_IsExpression_target() async {
+  Future<void> test_IsExpression_target() async {
     // IfStatement  Block  BlockFunctionBody
     addTestSource('''
 foo() { }
@@ -2725,7 +2733,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IsExpression_type() async {
+  Future<void> test_IsExpression_type() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addTestSource('''
 class A {int x; int y() => 0;}
@@ -2740,7 +2748,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IsExpression_type_partial() async {
+  Future<void> test_IsExpression_type_partial() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addTestSource('''
 class A {int x; int y() => 0;}
@@ -2755,7 +2763,7 @@
     assertNotSuggested('Object');
   }
 
-  test_keyword() async {
+  Future<void> test_keyword() async {
     addSource('/home/test/lib/b.dart', '''
 lib B;
 int newT1;
@@ -2782,7 +2790,7 @@
     assertNotSuggested('newer');
   }
 
-  test_Literal_list() async {
+  Future<void> test_Literal_list() async {
     // ']'  ListLiteral  ArgumentList  MethodInvocation
     addTestSource('main() {var Some; print([^]);}');
     await computeSuggestions();
@@ -2791,7 +2799,7 @@
     assertNotSuggested('String');
   }
 
-  test_Literal_list2() async {
+  Future<void> test_Literal_list2() async {
     // SimpleIdentifier ListLiteral  ArgumentList  MethodInvocation
     addTestSource('main() {var Some; print([S^]);}');
     await computeSuggestions();
@@ -2800,7 +2808,7 @@
     assertNotSuggested('String');
   }
 
-  test_Literal_string() async {
+  Future<void> test_Literal_string() async {
     // SimpleStringLiteral  ExpressionStatement  Block
     addTestSource('class A {a() {"hel^lo"}}');
     await computeSuggestions();
@@ -2808,7 +2816,7 @@
     assertNoSuggestions();
   }
 
-  test_localVariableDeclarationName() async {
+  Future<void> test_localVariableDeclarationName() async {
     addTestSource('main() {String m^}');
     await computeSuggestions();
 
@@ -2816,7 +2824,7 @@
     assertNotSuggested('min');
   }
 
-  test_MapLiteralEntry() async {
+  Future<void> test_MapLiteralEntry() async {
     // MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2849,7 +2857,7 @@
     }
   }
 
-  test_MapLiteralEntry1() async {
+  Future<void> test_MapLiteralEntry1() async {
     // MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2871,7 +2879,7 @@
     assertNotSuggested('T2');
   }
 
-  test_MapLiteralEntry2() async {
+  Future<void> test_MapLiteralEntry2() async {
     // SimpleIdentifier  MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2893,7 +2901,7 @@
     assertNotSuggested('T2');
   }
 
-  test_method_parameters_mixed_required_and_named() async {
+  Future<void> test_method_parameters_mixed_required_and_named() async {
     addTestSource('''
 class A {
   void m(x, {int y}) {}
@@ -2906,7 +2914,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_parameters_mixed_required_and_positional() async {
+  Future<void> test_method_parameters_mixed_required_and_positional() async {
     addTestSource('''
 class A {
   void m(x, [int y]) {}
@@ -2919,7 +2927,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_parameters_named() async {
+  Future<void> test_method_parameters_named() async {
     addTestSource('''
 class A {
   void m({x, int y}) {}
@@ -2932,7 +2940,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_parameters_none() async {
+  Future<void> test_method_parameters_none() async {
     addTestSource('''
 class A {
   void m() {}
@@ -2945,7 +2953,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_parameters_positional() async {
+  Future<void> test_method_parameters_positional() async {
     addTestSource('''
 class A {
   void m([x, int y]) {}
@@ -2958,7 +2966,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_parameters_required() async {
+  Future<void> test_method_parameters_required() async {
     addTestSource('''
 class A {
   void m(x, int y) {}
@@ -2971,7 +2979,7 @@
     assertNotSuggested('m');
   }
 
-  test_MethodDeclaration_body_getters() async {
+  Future<void> test_MethodDeclaration_body_getters() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated X get f => 0; Z a() {^} get _g => 1;}');
     await computeSuggestions();
@@ -2983,7 +2991,7 @@
     assertNotSuggested('_g');
   }
 
-  test_MethodDeclaration_body_static() async {
+  Future<void> test_MethodDeclaration_body_static() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testC.dart', '''
 class C {
@@ -3020,7 +3028,7 @@
     assertNotSuggested('c4');
   }
 
-  test_MethodDeclaration_members() async {
+  Future<void> test_MethodDeclaration_members() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated X f; Z _a() {^} var _g;}');
     await computeSuggestions();
@@ -3034,7 +3042,7 @@
     assertNotSuggested('bool');
   }
 
-  test_MethodDeclaration_parameters_named() async {
+  Future<void> test_MethodDeclaration_parameters_named() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated Z a(X x, _, b, {y: boo}) {^}}');
     await computeSuggestions();
@@ -3049,7 +3057,7 @@
     assertNotSuggested('_');
   }
 
-  test_MethodDeclaration_parameters_positional() async {
+  Future<void> test_MethodDeclaration_parameters_positional() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('''
 foo() { }
@@ -3067,7 +3075,7 @@
     assertNotSuggested('String');
   }
 
-  test_MethodDeclaration_returnType() async {
+  Future<void> test_MethodDeclaration_returnType() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3096,7 +3104,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3125,7 +3133,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment2() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment2() async {
     // MethodDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3154,7 +3162,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment3() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment3() async {
     // MethodDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3185,7 +3193,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodInvocation_no_semicolon() async {
+  Future<void> test_MethodInvocation_no_semicolon() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
 main() { }
@@ -3218,22 +3226,22 @@
     assertNotSuggested('==');
   }
 
-  test_missing_params_constructor() async {
+  Future<void> test_missing_params_constructor() async {
     addTestSource('class C1{C1{} main(){C^}}');
     await computeSuggestions();
   }
 
-  test_missing_params_function() async {
+  Future<void> test_missing_params_function() async {
     addTestSource('int f1{} main(){f^}');
     await computeSuggestions();
   }
 
-  test_missing_params_method() async {
+  Future<void> test_missing_params_method() async {
     addTestSource('class C1{int f1{} main(){f^}}');
     await computeSuggestions();
   }
 
-  test_new_instance() async {
+  Future<void> test_new_instance() async {
     addTestSource('import "dart:math"; class A {x() {new Random().^}}');
     await computeSuggestions();
 
@@ -3245,7 +3253,7 @@
     assertNotSuggested('A');
   }
 
-  test_overrides() async {
+  Future<void> test_overrides() async {
     addTestSource('''
 class A {m() {}}
 class B extends A {m() {^}}
@@ -3254,7 +3262,7 @@
     assertNotSuggested('m');
   }
 
-  test_parameterName_excludeTypes() async {
+  Future<void> test_parameterName_excludeTypes() async {
     addTestSource('m(int ^) {}');
     await computeSuggestions();
 
@@ -3262,7 +3270,7 @@
     assertNotSuggested('bool');
   }
 
-  test_partFile_TypeName() async {
+  Future<void> test_partFile_TypeName() async {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -3295,7 +3303,7 @@
     assertNotSuggested('m');
   }
 
-  test_partFile_TypeName2() async {
+  Future<void> test_partFile_TypeName2() async {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -3328,7 +3336,7 @@
     assertNotSuggested('m');
   }
 
-  test_PrefixedIdentifier_class_const() async {
+  Future<void> test_PrefixedIdentifier_class_const() async {
     // SimpleIdentifier PrefixedIdentifier ExpressionStatement Block
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -3375,7 +3383,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_class_imported() async {
+  Future<void> test_PrefixedIdentifier_class_imported() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -3412,7 +3420,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_class_local() async {
+  Future<void> test_PrefixedIdentifier_class_local() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
 main() {A a; a.^}
@@ -3446,7 +3454,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_getter() async {
+  Future<void> test_PrefixedIdentifier_getter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String get g => "one"; f() {g.^}');
     await computeSuggestions();
@@ -3454,7 +3462,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_library() async {
+  Future<void> test_PrefixedIdentifier_library() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -3481,7 +3489,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_typesOnly() async {
+  Future<void> test_PrefixedIdentifier_library_typesOnly() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -3508,7 +3516,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_typesOnly2() async {
+  Future<void> test_PrefixedIdentifier_library_typesOnly2() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -3535,7 +3543,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_parameter() async {
+  Future<void> test_PrefixedIdentifier_parameter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -3554,7 +3562,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_prefix() async {
+  Future<void> test_PrefixedIdentifier_prefix() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
 class A {static int bar = 10;}
@@ -3577,7 +3585,7 @@
     assertNotSuggested('_B');
   }
 
-  test_PrefixedIdentifier_propertyAccess() async {
+  Future<void> test_PrefixedIdentifier_propertyAccess() async {
     // PrefixedIdentifier  ExpressionStatement  Block  BlockFunctionBody
     addTestSource('class A {String x; int get foo {x.^}');
     await computeSuggestions();
@@ -3588,7 +3596,7 @@
     assertNotSuggested('compareTo');
   }
 
-  test_PrefixedIdentifier_propertyAccess_newStmt() async {
+  Future<void> test_PrefixedIdentifier_propertyAccess_newStmt() async {
     // PrefixedIdentifier  ExpressionStatement  Block  BlockFunctionBody
     addTestSource('class A {String x; int get foo {x.^ int y = 0;}');
     await computeSuggestions();
@@ -3599,7 +3607,7 @@
     assertNotSuggested('compareTo');
   }
 
-  test_PrefixedIdentifier_trailingStmt_const() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_const() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('const String g = "hello"; f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -3607,7 +3615,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_field() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_field() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {String g; f() {g.^ int y = 0;}}');
     await computeSuggestions();
@@ -3615,7 +3623,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_function() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_function() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String g() => "one"; f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -3623,7 +3631,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_functionTypeAlias() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_functionTypeAlias() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('typedef String g(); f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -3631,7 +3639,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_getter() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_getter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String get g => "one"; f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -3639,7 +3647,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_local_typed() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_local_typed() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f() {String g; g.^ int y = 0;}');
     await computeSuggestions();
@@ -3647,7 +3655,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_local_untyped() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_local_untyped() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f() {var g = "hello"; g.^ int y = 0;}');
     await computeSuggestions();
@@ -3655,7 +3663,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_method() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_method() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {String g() {}; f() {g.^ int y = 0;}}');
     await computeSuggestions();
@@ -3663,7 +3671,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_param() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_param() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {f(String g) {g.^ int y = 0;}}');
     await computeSuggestions();
@@ -3671,7 +3679,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_param2() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_param2() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f(String g) {g.^ int y = 0;}');
     await computeSuggestions();
@@ -3679,7 +3687,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_topLevelVar() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_topLevelVar() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String g; f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -3687,28 +3695,28 @@
     assertNotSuggested('length');
   }
 
-  test_prioritization() async {
+  Future<void> test_prioritization() async {
     addTestSource('main() {var ab; var _ab; ^}');
     await computeSuggestions();
     assertNotSuggested('ab');
     assertNotSuggested('_ab');
   }
 
-  test_prioritization_private() async {
+  Future<void> test_prioritization_private() async {
     addTestSource('main() {var ab; var _ab; _^}');
     await computeSuggestions();
     assertNotSuggested('ab');
     assertNotSuggested('_ab');
   }
 
-  test_prioritization_public() async {
+  Future<void> test_prioritization_public() async {
     addTestSource('main() {var ab; var _ab; a^}');
     await computeSuggestions();
     assertNotSuggested('ab');
     assertNotSuggested('_ab');
   }
 
-  test_PropertyAccess_expression() async {
+  Future<void> test_PropertyAccess_expression() async {
     // SimpleIdentifier  MethodInvocation  PropertyAccess  ExpressionStatement
     addTestSource('class A {a() {"hello".to^String().length}}');
     await computeSuggestions();
@@ -3722,7 +3730,7 @@
     assertNotSuggested('==');
   }
 
-  test_PropertyAccess_noTarget() async {
+  Future<void> test_PropertyAccess_noTarget() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement
     addSource('/testAB.dart', 'class Foo { }');
     addTestSource('class C {foo(){.^}}');
@@ -3731,7 +3739,7 @@
     assertNoSuggestions();
   }
 
-  test_PropertyAccess_noTarget2() async {
+  Future<void> test_PropertyAccess_noTarget2() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement
     addSource('/testAB.dart', 'class Foo { }');
     addTestSource('main() {.^}');
@@ -3740,7 +3748,7 @@
     assertNoSuggestions();
   }
 
-  test_PropertyAccess_selector() async {
+  Future<void> test_PropertyAccess_selector() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement  Block
     addTestSource('class A {a() {"hello".length.^}}');
     await computeSuggestions();
@@ -3754,13 +3762,13 @@
     assertNotSuggested('==');
   }
 
-  test_shadowed_name() async {
+  Future<void> test_shadowed_name() async {
     addTestSource('var a; class A { var a; m() { ^ } }');
     await computeSuggestions();
     assertNotSuggested('a');
   }
 
-  test_SwitchStatement_c() async {
+  Future<void> test_SwitchStatement_c() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {switch(x) {c^}}}');
     await computeSuggestions();
@@ -3768,7 +3776,7 @@
     assertNoSuggestions();
   }
 
-  test_SwitchStatement_case() async {
+  Future<void> test_SwitchStatement_case() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {var t; switch(x) {case 0: ^}}}');
     await computeSuggestions();
@@ -3783,7 +3791,7 @@
     assertNotSuggested('String');
   }
 
-  test_SwitchStatement_empty() async {
+  Future<void> test_SwitchStatement_empty() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {switch(x) {^}}}');
     await computeSuggestions();
@@ -3791,7 +3799,7 @@
     assertNoSuggestions();
   }
 
-  test_ThisExpression_block() async {
+  Future<void> test_ThisExpression_block() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
 main() { }
@@ -3827,7 +3835,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor() async {
+  Future<void> test_ThisExpression_constructor() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
 main() { }
@@ -3863,7 +3871,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param() async {
+  Future<void> test_ThisExpression_constructor_param() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
 main() { }
@@ -3901,7 +3909,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param2() async {
+  Future<void> test_ThisExpression_constructor_param2() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
 main() { }
@@ -3938,7 +3946,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param3() async {
+  Future<void> test_ThisExpression_constructor_param3() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
 main() { }
@@ -3975,7 +3983,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param4() async {
+  Future<void> test_ThisExpression_constructor_param4() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
 main() { }
@@ -4012,7 +4020,7 @@
     assertNotSuggested('==');
   }
 
-  test_TopLevelVariableDeclaration_typed_name() async {
+  Future<void> test_TopLevelVariableDeclaration_typed_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // TopLevelVariableDeclaration
     addTestSource('class A {} B ^');
@@ -4021,7 +4029,7 @@
     assertNoSuggestions();
   }
 
-  test_TopLevelVariableDeclaration_untyped_name() async {
+  Future<void> test_TopLevelVariableDeclaration_untyped_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // TopLevelVariableDeclaration
     addTestSource('class A {} var ^');
@@ -4030,7 +4038,7 @@
     assertNoSuggestions();
   }
 
-  test_TypeArgumentList() async {
+  Future<void> test_TypeArgumentList() async {
     // SimpleIdentifier  BinaryExpression  ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
 class C1 {int x;}
@@ -4056,7 +4064,7 @@
     assertNotSuggested('F2');
   }
 
-  test_TypeArgumentList2() async {
+  Future<void> test_TypeArgumentList2() async {
     // TypeName  TypeArgumentList  TypeName
     addSource('/home/test/lib/a.dart', '''
 class C1 {int x;}
@@ -4077,7 +4085,7 @@
     assertNotSuggested('C2');
   }
 
-  test_VariableDeclaration_name() async {
+  Future<void> test_VariableDeclaration_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addSource('/home/test/lib/b.dart', '''
@@ -4094,7 +4102,7 @@
     assertNoSuggestions();
   }
 
-  test_VariableDeclarationList_final() async {
+  Future<void> test_VariableDeclarationList_final() async {
     // VariableDeclarationList  VariableDeclarationStatement  Block
     addTestSource('main() {final ^} class C { }');
     await computeSuggestions();
@@ -4104,7 +4112,7 @@
     assertNotSuggested('==');
   }
 
-  test_VariableDeclarationStatement_RHS() async {
+  Future<void> test_VariableDeclarationStatement_RHS() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement
     addSource('/home/test/lib/b.dart', '''
@@ -4133,7 +4141,7 @@
     assertNotSuggested('e');
   }
 
-  test_VariableDeclarationStatement_RHS_missing_semicolon() async {
+  Future<void> test_VariableDeclarationStatement_RHS_missing_semicolon() async {
     // VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement
     addSource('/home/test/lib/b.dart', '''
diff --git a/pkg/analysis_server/test/services/completion/dart/local_library_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/local_library_contributor_test.dart
index 4b1d3aa..f1b60ed 100644
--- a/pkg/analysis_server/test/services/completion/dart/local_library_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/local_library_contributor_test.dart
@@ -10,7 +10,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LocalLibraryContributorTest);
     defineReflectiveTests(LocalLibraryContributorWithExtensionMethodsTest);
@@ -24,7 +24,7 @@
     return LocalLibraryContributor();
   }
 
-  test_partFile_Constructor() async {
+  Future<void> test_partFile_Constructor() async {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -58,7 +58,7 @@
     assertNotSuggested('m');
   }
 
-  test_partFile_Constructor2() async {
+  Future<void> test_partFile_Constructor2() async {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -92,7 +92,8 @@
     assertNotSuggested('m');
   }
 
-  test_partFile_InstanceCreationExpression_assignment_filter() async {
+  Future<void>
+      test_partFile_InstanceCreationExpression_assignment_filter() async {
     // ConstructorName  InstanceCreationExpression  VariableDeclarationList
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -144,7 +145,8 @@
     assertNotSuggested('m');
   }
 
-  test_partFile_InstanceCreationExpression_variable_declaration_filter() async {
+  Future<void>
+      test_partFile_InstanceCreationExpression_variable_declaration_filter() async {
     // ConstructorName  InstanceCreationExpression  VariableDeclarationList
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -194,7 +196,7 @@
     assertNotSuggested('m');
   }
 
-  test_partFile_TypeName() async {
+  Future<void> test_partFile_TypeName() async {
     addSource('/home/test/lib/b.dart', '''
         lib B;
         int T1;
@@ -239,7 +241,7 @@
     assertNotSuggested('z');
   }
 
-  test_partFile_TypeName2() async {
+  Future<void> test_partFile_TypeName2() async {
     addSource('/home/test/lib/b.dart', '''
         lib B;
         int T1;
@@ -296,7 +298,7 @@
     createAnalysisOptionsFile(experiments: [EnableString.extension_methods]);
   }
 
-  test_partFile_extension() async {
+  Future<void> test_partFile_extension() async {
     addSource('/home/test/lib/a.dart', '''
 part of libA;
 extension E on int {}
diff --git a/pkg/analysis_server/test/services/completion/dart/local_reference_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/local_reference_contributor_test.dart
index cb7fffc..e03c3c7 100644
--- a/pkg/analysis_server/test/services/completion/dart/local_reference_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/local_reference_contributor_test.dart
@@ -11,7 +11,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LocalReferenceContributorTest);
     defineReflectiveTests(LocalReferenceContributorWithExtensionMethodsTest);
@@ -77,7 +77,7 @@
     return LocalReferenceContributor();
   }
 
-  test_ArgDefaults_function() async {
+  Future<void> test_ArgDefaults_function() async {
     addTestSource('''
 bool hasLength(int a, bool b) => false;
 void main() {h^}''');
@@ -89,7 +89,7 @@
         defaultArgumentListTextRanges: [0, 1, 3, 1]);
   }
 
-  test_ArgDefaults_function_none() async {
+  Future<void> test_ArgDefaults_function_none() async {
     addTestSource('''
 bool hasLength() => false;
 void main() {h^}''');
@@ -101,7 +101,7 @@
         defaultArgumentListTextRanges: null);
   }
 
-  test_ArgDefaults_function_with_optional_positional() async {
+  Future<void> test_ArgDefaults_function_with_optional_positional() async {
     addMetaPackage();
     addTestSource('''
 import 'package:meta/meta.dart';
@@ -116,7 +116,7 @@
         defaultArgumentListTextRanges: [0, 3]);
   }
 
-  test_ArgDefaults_function_with_required_named() async {
+  Future<void> test_ArgDefaults_function_with_required_named() async {
     addMetaPackage();
     addTestSource('''
 import 'package:meta/meta.dart';
@@ -131,7 +131,7 @@
         defaultArgumentListTextRanges: [0, 3, 10, 4]);
   }
 
-  test_ArgDefaults_method_with_required_named() async {
+  Future<void> test_ArgDefaults_method_with_required_named() async {
     addMetaPackage();
     addTestSource('''
 import 'package:meta/meta.dart';
@@ -150,7 +150,7 @@
         defaultArgumentListTextRanges: [0, 3, 10, 4]);
   }
 
-  test_ArgumentList() async {
+  Future<void> test_ArgumentList() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -176,7 +176,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_imported_function() async {
+  Future<void> test_ArgumentList_imported_function() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -203,7 +203,8 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_InstanceCreationExpression_functionalArg() async {
+  Future<void>
+      test_ArgumentList_InstanceCreationExpression_functionalArg() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -233,7 +234,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_InstanceCreationExpression_typedefArg() async {
+  Future<void> test_ArgumentList_InstanceCreationExpression_typedefArg() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -264,7 +265,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_local_function() async {
+  Future<void> test_ArgumentList_local_function() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -291,7 +292,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_local_method() async {
+  Future<void> test_ArgumentList_local_method() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -318,7 +319,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_MethodInvocation_functionalArg() async {
+  Future<void> test_ArgumentList_MethodInvocation_functionalArg() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -351,7 +352,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_MethodInvocation_functionalArg2() async {
+  Future<void> test_ArgumentList_MethodInvocation_functionalArg2() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -386,7 +387,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_MethodInvocation_methodArg() async {
+  Future<void> test_ArgumentList_MethodInvocation_methodArg() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 library A;
@@ -412,7 +413,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_namedFieldParam_tear_off() async {
+  Future<void> test_ArgumentList_namedFieldParam_tear_off() async {
     addSource('/home/test/lib/a.dart', '''
 typedef void VoidCallback();
         
@@ -441,7 +442,7 @@
         csKind: CompletionSuggestionKind.IDENTIFIER);
   }
 
-  test_ArgumentList_namedParam() async {
+  Future<void> test_ArgumentList_namedParam() async {
     // SimpleIdentifier  NamedExpression  ArgumentList  MethodInvocation
     // ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
@@ -461,7 +462,7 @@
     assertNotSuggested('main');
   }
 
-  test_ArgumentList_namedParam_filter() async {
+  Future<void> test_ArgumentList_namedParam_filter() async {
     // SimpleIdentifier  NamedExpression  ArgumentList
     // InstanceCreationExpression
     addTestSource('''
@@ -498,7 +499,7 @@
         relevance: DART_RELEVANCE_LOCAL_TOP_LEVEL_VARIABLE);
   }
 
-  test_ArgumentList_namedParam_tear_off() async {
+  Future<void> test_ArgumentList_namedParam_tear_off() async {
     addSource('/home/test/lib/a.dart', '''
 typedef void VoidCallback();
         
@@ -526,7 +527,7 @@
         csKind: CompletionSuggestionKind.IDENTIFIER);
   }
 
-  test_ArgumentList_namedParam_tear_off_1() async {
+  Future<void> test_ArgumentList_namedParam_tear_off_1() async {
     addSource('/home/test/lib/a.dart', '''
 typedef void VoidCallback();
         
@@ -554,7 +555,7 @@
         csKind: CompletionSuggestionKind.IDENTIFIER);
   }
 
-  test_ArgumentList_namedParam_tear_off_2() async {
+  Future<void> test_ArgumentList_namedParam_tear_off_2() async {
     addSource('/home/test/lib/a.dart', '''
 typedef void VoidCallback();
         
@@ -582,7 +583,7 @@
         csKind: CompletionSuggestionKind.IDENTIFIER);
   }
 
-  test_AsExpression_type() async {
+  Future<void> test_AsExpression_type() async {
     // SimpleIdentifier  TypeName  AsExpression
     addTestSource('''
         class A {var b; X _c; foo() {var a; (a as ^).foo();}''');
@@ -597,7 +598,7 @@
     assertNotSuggested('==');
   }
 
-  test_AsExpression_type_filter_extends() async {
+  Future<void> test_AsExpression_type_filter_extends() async {
     // SimpleIdentifier  TypeName  AsExpression
     addTestSource('''
 class A {} class B extends A {} class C extends A {} class D {}
@@ -613,7 +614,7 @@
     assertNotSuggested('Object');
   }
 
-  test_AsExpression_type_filter_implements() async {
+  Future<void> test_AsExpression_type_filter_implements() async {
     // SimpleIdentifier  TypeName  AsExpression
     addTestSource('''
 class A {} class B implements A {} class C implements A {} class D {}
@@ -629,7 +630,7 @@
     assertNotSuggested('Object');
   }
 
-  test_AsExpression_type_filter_undefined_type() async {
+  Future<void> test_AsExpression_type_filter_undefined_type() async {
     // SimpleIdentifier  TypeName  AsExpression
     addTestSource('''
 class A {}
@@ -641,7 +642,7 @@
     assertSuggestClass('A');
   }
 
-  test_AssignmentExpression_name() async {
+  Future<void> test_AssignmentExpression_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('class A {} main() {int a; int ^b = 1;}');
@@ -650,7 +651,7 @@
     assertNoSuggestions();
   }
 
-  test_AssignmentExpression_RHS() async {
+  Future<void> test_AssignmentExpression_RHS() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('class A {} main() {int a; int b = ^}');
@@ -665,7 +666,7 @@
     assertNotSuggested('Object');
   }
 
-  test_AssignmentExpression_type() async {
+  Future<void> test_AssignmentExpression_type() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -689,7 +690,7 @@
     //assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_newline() async {
+  Future<void> test_AssignmentExpression_type_newline() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -713,7 +714,7 @@
     assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_partial() async {
+  Future<void> test_AssignmentExpression_type_partial() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -737,7 +738,7 @@
     //assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_partial_newline() async {
+  Future<void> test_AssignmentExpression_type_partial_newline() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -761,7 +762,7 @@
     assertNotSuggested('identical');
   }
 
-  test_AwaitExpression() async {
+  Future<void> test_AwaitExpression() async {
     // SimpleIdentifier  AwaitExpression  ExpressionStatement
     addTestSource('''
 class A {int x; int y() => 0;}
@@ -777,7 +778,7 @@
     assertNotSuggested('Object');
   }
 
-  test_AwaitExpression2() async {
+  Future<void> test_AwaitExpression2() async {
     // SimpleIdentifier  AwaitExpression  ExpressionStatement
     addTestSource('''
         class A {
@@ -795,7 +796,7 @@
     assertNotSuggested('Object');
   }
 
-  test_BinaryExpression_LHS() async {
+  Future<void> test_BinaryExpression_LHS() async {
     // SimpleIdentifier  BinaryExpression  VariableDeclaration
     // VariableDeclarationList  VariableDeclarationStatement
     addTestSource('main() {int a = 1, b = ^ + 2;}');
@@ -812,7 +813,7 @@
     assertNotSuggested('b');
   }
 
-  test_BinaryExpression_RHS() async {
+  Future<void> test_BinaryExpression_RHS() async {
     // SimpleIdentifier  BinaryExpression  VariableDeclaration
     // VariableDeclarationList  VariableDeclarationStatement
     addTestSource('main() {int a = 1, b = 2 + ^;}');
@@ -826,7 +827,7 @@
     assertNotSuggested('==');
   }
 
-  test_Block() async {
+  Future<void> test_Block() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/ab.dart', '''
 export "dart:math" hide max;
@@ -924,7 +925,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final() async {
+  Future<void> test_Block_final() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/ab.dart', '''
 export "dart:math" hide max;
@@ -1023,21 +1024,21 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final2() async {
+  Future<void> test_Block_final2() async {
     addTestSource('main() {final S^ v;}');
     await computeSuggestions();
 
     assertNotSuggested('String');
   }
 
-  test_Block_final3() async {
+  Future<void> test_Block_final3() async {
     addTestSource('main() {final ^ v;}');
     await computeSuggestions();
 
     assertNotSuggested('String');
   }
 
-  test_Block_final_final() async {
+  Future<void> test_Block_final_final() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/ab.dart', '''
 export "dart:math" hide max;
@@ -1136,7 +1137,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final_var() async {
+  Future<void> test_Block_final_var() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/ab.dart', '''
 export "dart:math" hide max;
@@ -1235,7 +1236,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_identifier_partial() async {
+  Future<void> test_Block_identifier_partial() async {
     addSource('/home/test/lib/ab.dart', '''
 export "dart:math" hide max;
 class A {int x;}
@@ -1314,7 +1315,7 @@
     assertNotSuggested('HtmlElement');
   }
 
-  test_Block_inherited_imported() async {
+  Future<void> test_Block_inherited_imported() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     resolveSource('/home/test/lib/b.dart', '''
 lib B;
@@ -1345,7 +1346,7 @@
     assertNotSuggested('==');
   }
 
-  test_Block_inherited_local() async {
+  Future<void> test_Block_inherited_local() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     addTestSource('''
 class F { var f1; f2() { } get f3 => 0; set f4(fx) { } }
@@ -1369,7 +1370,7 @@
     assertNotSuggested('m2');
   }
 
-  test_Block_local_function() async {
+  Future<void> test_Block_local_function() async {
     addSource('/home/test/lib/ab.dart', '''
 export "dart:math" hide max;
 class A {int x;}
@@ -1420,7 +1421,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_unimported() async {
+  Future<void> test_Block_unimported() async {
     addPackageFile('aaa', 'a.dart', 'class A {}');
     addTestSource('main() { ^ }');
 
@@ -1433,7 +1434,7 @@
     assertNotSuggested('Future');
   }
 
-  test_CascadeExpression_selector1() async {
+  Future<void> test_CascadeExpression_selector1() async {
     // PropertyAccess  CascadeExpression  ExpressionStatement  Block
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1458,7 +1459,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_selector2() async {
+  Future<void> test_CascadeExpression_selector2() async {
     // SimpleIdentifier  PropertyAccess  CascadeExpression  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1481,7 +1482,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_selector2_withTrailingReturn() async {
+  Future<void> test_CascadeExpression_selector2_withTrailingReturn() async {
     // PropertyAccess  CascadeExpression  ExpressionStatement  Block
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1504,7 +1505,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_target() async {
+  Future<void> test_CascadeExpression_target() async {
     // SimpleIdentifier  CascadeExpression  ExpressionStatement
     addTestSource('''
 class A {var b; X _c;}
@@ -1524,7 +1525,7 @@
     assertNotSuggested('==');
   }
 
-  test_CatchClause_onType() async {
+  Future<void> test_CatchClause_onType() async {
     // TypeName  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on ^ {}}}');
     await computeSuggestions();
@@ -1537,7 +1538,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_onType_noBrackets() async {
+  Future<void> test_CatchClause_onType_noBrackets() async {
     // TypeName  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on ^}}');
     await computeSuggestions();
@@ -1549,7 +1550,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_typed() async {
+  Future<void> test_CatchClause_typed() async {
     // Block  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on E catch (e) {^}}}');
     await computeSuggestions();
@@ -1562,7 +1563,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_untyped() async {
+  Future<void> test_CatchClause_untyped() async {
     // Block  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} catch (e, s) {^}}}');
     await computeSuggestions();
@@ -1576,7 +1577,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body() async {
+  Future<void> test_ClassDeclaration_body() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1606,7 +1607,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final() async {
+  Future<void> test_ClassDeclaration_body_final() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1627,7 +1628,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_field() async {
+  Future<void> test_ClassDeclaration_body_final_field() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1648,7 +1649,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_field2() async {
+  Future<void> test_ClassDeclaration_body_final_field2() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1669,7 +1670,7 @@
     assertNotSuggested('Soo');
   }
 
-  test_ClassDeclaration_body_final_final() async {
+  Future<void> test_ClassDeclaration_body_final_final() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1690,7 +1691,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_var() async {
+  Future<void> test_ClassDeclaration_body_final_var() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -1711,7 +1712,7 @@
     assertNotSuggested('x');
   }
 
-  test_classReference_in_comment() async {
+  Future<void> test_classReference_in_comment() async {
     addTestSource(r'''
 class Abc { }
 class Abcd { }
@@ -1726,7 +1727,7 @@
 
   /// see: https://github.com/dart-lang/sdk/issues/36037
   @failingTest
-  test_classReference_in_comment_eof() async {
+  Future<void> test_classReference_in_comment_eof() async {
     addTestSource(r'''
 class Abc { }
 class Abcd { }
@@ -1738,7 +1739,7 @@
     assertNotSuggested('Abcd');
   }
 
-  test_Combinator_hide() async {
+  Future<void> test_Combinator_hide() async {
     // SimpleIdentifier  HideCombinator  ImportDirective
     addSource('/home/test/lib/ab.dart', '''
 library libAB;
@@ -1762,7 +1763,7 @@
     assertNoSuggestions();
   }
 
-  test_Combinator_show() async {
+  Future<void> test_Combinator_show() async {
     // SimpleIdentifier  HideCombinator  ImportDirective
     addSource('/home/test/lib/ab.dart', '''
 library libAB;
@@ -1788,7 +1789,7 @@
     assertNoSuggestions();
   }
 
-  test_ConditionalExpression_elseExpression() async {
+  Future<void> test_ConditionalExpression_elseExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -1809,7 +1810,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_ConditionalExpression_elseExpression_empty() async {
+  Future<void> test_ConditionalExpression_elseExpression_empty() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -1837,7 +1838,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_ConditionalExpression_partial_thenExpression() async {
+  Future<void> test_ConditionalExpression_partial_thenExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -1858,7 +1859,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_ConditionalExpression_partial_thenExpression_empty() async {
+  Future<void> test_ConditionalExpression_partial_thenExpression_empty() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -1886,7 +1887,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_ConditionalExpression_thenExpression() async {
+  Future<void> test_ConditionalExpression_thenExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -1907,42 +1908,43 @@
     //assertNotSuggested('T1');
   }
 
-  test_constructor_parameters_mixed_required_and_named() async {
+  Future<void> test_constructor_parameters_mixed_required_and_named() async {
     addTestSource('class A {A(x, {int y}) {^}}');
     await computeSuggestions();
     assertSuggestParameter('x', null);
     assertSuggestParameter('y', 'int');
   }
 
-  test_constructor_parameters_mixed_required_and_positional() async {
+  Future<void>
+      test_constructor_parameters_mixed_required_and_positional() async {
     addTestSource('class A {A(x, [int y]) {^}}');
     await computeSuggestions();
     assertSuggestParameter('x', null);
     assertSuggestParameter('y', 'int');
   }
 
-  test_constructor_parameters_named() async {
+  Future<void> test_constructor_parameters_named() async {
     addTestSource('class A {A({x, int y}) {^}}');
     await computeSuggestions();
     assertSuggestParameter('x', null);
     assertSuggestParameter('y', 'int');
   }
 
-  test_constructor_parameters_positional() async {
+  Future<void> test_constructor_parameters_positional() async {
     addTestSource('class A {A([x, int y]) {^}}');
     await computeSuggestions();
     assertSuggestParameter('x', null);
     assertSuggestParameter('y', 'int');
   }
 
-  test_constructor_parameters_required() async {
+  Future<void> test_constructor_parameters_required() async {
     addTestSource('class A {A(x, int y) {^}}');
     await computeSuggestions();
     assertSuggestParameter('x', null);
     assertSuggestParameter('y', 'int');
   }
 
-  test_ConstructorFieldInitializer_name() async {
+  Future<void> test_ConstructorFieldInitializer_name() async {
     addTestSource('''
 class A {
   final int foo;
@@ -1956,7 +1958,7 @@
     assertSuggestField('foo', 'int', relevance: DART_RELEVANCE_LOCAL_FIELD);
   }
 
-  test_ConstructorFieldInitializer_value() async {
+  Future<void> test_ConstructorFieldInitializer_value() async {
     addTestSource('''
 var foo = 0;
 
@@ -1976,7 +1978,7 @@
     );
   }
 
-  test_ConstructorName_importedClass() async {
+  Future<void> test_ConstructorName_importedClass() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -2001,7 +2003,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedFactory() async {
+  Future<void> test_ConstructorName_importedFactory() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -2026,7 +2028,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedFactory2() async {
+  Future<void> test_ConstructorName_importedFactory2() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -2044,7 +2046,7 @@
     assertNotSuggested('String');
   }
 
-  test_ConstructorName_localClass() async {
+  Future<void> test_ConstructorName_localClass() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -2065,7 +2067,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_localFactory() async {
+  Future<void> test_ConstructorName_localFactory() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -2086,7 +2088,7 @@
     assertNotSuggested('m');
   }
 
-  test_DefaultFormalParameter_named_expression() async {
+  Future<void> test_DefaultFormalParameter_named_expression() async {
     // DefaultFormalParameter FormalParameterList MethodDeclaration
     addTestSource('''
 foo() { }
@@ -2104,7 +2106,7 @@
     assertNotSuggested('identical');
   }
 
-  test_doc_classMember() async {
+  Future<void> test_doc_classMember() async {
     String docLines = r'''
   /// My documentation.
   /// Short description.
@@ -2149,7 +2151,7 @@
     }
   }
 
-  test_doc_topLevel() async {
+  Future<void> test_doc_topLevel() async {
     String docLines = r'''
 /// My documentation.
 /// Short description.
@@ -2208,7 +2210,7 @@
     }
   }
 
-  test_enum() async {
+  Future<void> test_enum() async {
     addTestSource('enum E { one, two } main() {^}');
     await computeSuggestions();
     assertSuggestEnum('E');
@@ -2218,7 +2220,7 @@
     assertNotSuggested('two');
   }
 
-  test_enum_deprecated() async {
+  Future<void> test_enum_deprecated() async {
     addTestSource('@deprecated enum E { one, two } main() {^}');
     await computeSuggestions();
     assertSuggestEnum('E', isDeprecated: true);
@@ -2228,7 +2230,7 @@
     assertNotSuggested('two');
   }
 
-  test_enum_filter() async {
+  Future<void> test_enum_filter() async {
     addTestSource('''
 enum E { one, two }
 enum F { three, four }
@@ -2250,7 +2252,7 @@
     assertSuggestEnumConst('F.four');
   }
 
-  test_enum_filter_assignment() async {
+  Future<void> test_enum_filter_assignment() async {
     addTestSource('''
 enum E { one, two }
 enum F { three, four }
@@ -2271,7 +2273,7 @@
     assertSuggestEnumConst('F.four');
   }
 
-  test_enum_filter_binaryEquals() async {
+  Future<void> test_enum_filter_binaryEquals() async {
     addTestSource('''
 enum E { one, two }
 enum F { three, four }
@@ -2291,7 +2293,7 @@
     assertSuggestEnumConst('F.four');
   }
 
-  test_enum_filter_switchCase() async {
+  Future<void> test_enum_filter_switchCase() async {
     addTestSource('''
 enum E { one, two }
 enum F { three, four }
@@ -2313,7 +2315,7 @@
     assertSuggestEnumConst('F.four');
   }
 
-  test_enum_filter_variableDeclaration() async {
+  Future<void> test_enum_filter_variableDeclaration() async {
     addTestSource('''
 enum E { one, two }
 enum F { three, four }
@@ -2333,7 +2335,7 @@
     assertSuggestEnumConst('F.four');
   }
 
-  test_expression_localVariable() async {
+  Future<void> test_expression_localVariable() async {
     addTestSource('''
 void f() {
   var v = 0;
@@ -2344,7 +2346,7 @@
     assertSuggestLocalVariable('v', 'int');
   }
 
-  test_expression_parameter() async {
+  Future<void> test_expression_parameter() async {
     addTestSource('''
 void f(int a) {
   ^
@@ -2354,7 +2356,7 @@
     assertSuggestParameter('a', 'int');
   }
 
-  test_expression_typeParameter_classDeclaration() async {
+  Future<void> test_expression_typeParameter_classDeclaration() async {
     addTestSource('''
 class A<T> {
   void m() {
@@ -2368,7 +2370,7 @@
     assertNotSuggested('U');
   }
 
-  test_expression_typeParameter_classTypeAlias() async {
+  Future<void> test_expression_typeParameter_classTypeAlias() async {
     addTestSource('''
 class A<U> {}
 class B<T> = A<^>;
@@ -2378,7 +2380,7 @@
     assertNotSuggested('U');
   }
 
-  test_expression_typeParameter_functionDeclaration() async {
+  Future<void> test_expression_typeParameter_functionDeclaration() async {
     addTestSource('''
 void f<T>() {
   ^
@@ -2390,7 +2392,7 @@
     assertNotSuggested('U');
   }
 
-  test_expression_typeParameter_functionDeclaration_local() async {
+  Future<void> test_expression_typeParameter_functionDeclaration_local() async {
     addTestSource('''
 void f() {
   void g2<U>() {}
@@ -2404,7 +2406,7 @@
     assertNotSuggested('U');
   }
 
-  test_expression_typeParameter_functionTypeAlias() async {
+  Future<void> test_expression_typeParameter_functionTypeAlias() async {
     addTestSource('''
 typedef void F<T>(^);
 ''');
@@ -2412,7 +2414,7 @@
     assertSuggestTypeParameter('T');
   }
 
-  test_expression_typeParameter_genericTypeAlias() async {
+  Future<void> test_expression_typeParameter_genericTypeAlias() async {
     addTestSource('''
 typedef F<T> = void Function<U>(^);
 ''');
@@ -2421,7 +2423,7 @@
     assertSuggestTypeParameter('U');
   }
 
-  test_expression_typeParameter_methodDeclaration() async {
+  Future<void> test_expression_typeParameter_methodDeclaration() async {
     addTestSource('''
 class A {
   void m<T>() {
@@ -2435,7 +2437,7 @@
     assertNotSuggested('U');
   }
 
-  test_expression_typeParameter_mixinDeclaration() async {
+  Future<void> test_expression_typeParameter_mixinDeclaration() async {
     addTestSource('''
 mixin M<T> {
   void m() {
@@ -2449,7 +2451,7 @@
     assertNotSuggested('U');
   }
 
-  test_ExpressionStatement_identifier() async {
+  Future<void> test_ExpressionStatement_identifier() async {
     // SimpleIdentifier  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 _B F1() { }
@@ -2478,7 +2480,7 @@
     assertNotSuggested('_B');
   }
 
-  test_ExpressionStatement_name() async {
+  Future<void> test_ExpressionStatement_name() async {
     // ExpressionStatement  Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/a.dart', '''
         B T1;
@@ -2491,7 +2493,7 @@
     assertNoSuggestions();
   }
 
-  test_extendsClause() async {
+  Future<void> test_extendsClause() async {
     addTestSource('''
 class A {}
 mixin M {}
@@ -2502,7 +2504,7 @@
     assertNotSuggested('M');
   }
 
-  test_FieldDeclaration_name_typed() async {
+  Future<void> test_FieldDeclaration_name_typed() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // FieldDeclaration
     addSource('/home/test/lib/a.dart', 'class A { }');
@@ -2514,7 +2516,7 @@
     assertNoSuggestions();
   }
 
-  test_FieldDeclaration_name_var() async {
+  Future<void> test_FieldDeclaration_name_var() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // FieldDeclaration
     addSource('/home/test/lib/a.dart', 'class A { }');
@@ -2526,7 +2528,7 @@
     assertNoSuggestions();
   }
 
-  test_FieldFormalParameter_in_non_constructor() async {
+  Future<void> test_FieldFormalParameter_in_non_constructor() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('class A {B(this.^foo) {}}');
     await computeSuggestions();
@@ -2536,7 +2538,7 @@
     assertNoSuggestions();
   }
 
-  test_forEachPartsWithIdentifier_class() async {
+  Future<void> test_forEachPartsWithIdentifier_class() async {
     addTestSource('''
 class C {}
 
@@ -2550,7 +2552,7 @@
     // Using `C` in for-each is invalid, but we should not crash.
   }
 
-  test_forEachPartsWithIdentifier_localLevelVariable() async {
+  Future<void> test_forEachPartsWithIdentifier_localLevelVariable() async {
     addTestSource('''
 main() {
   int v;
@@ -2565,7 +2567,7 @@
     assertSuggestLocalVariable('v', 'int');
   }
 
-  test_forEachPartsWithIdentifier_topLevelVariable() async {
+  Future<void> test_forEachPartsWithIdentifier_topLevelVariable() async {
     addTestSource('''
 int v;
 main() {
@@ -2581,7 +2583,7 @@
         relevance: DART_RELEVANCE_LOCAL_TOP_LEVEL_VARIABLE);
   }
 
-  test_ForEachStatement() async {
+  Future<void> test_ForEachStatement() async {
     // SimpleIdentifier  ForEachStatement
     addTestSource('main() {List<int> values; for (int index in ^)}');
     await computeSuggestions();
@@ -2592,7 +2594,7 @@
     assertNotSuggested('index');
   }
 
-  test_ForEachStatement2() async {
+  Future<void> test_ForEachStatement2() async {
     // SimpleIdentifier  ForEachStatement
     addTestSource('main() {List<int> values; for (int index in i^)}');
     await computeSuggestions();
@@ -2603,7 +2605,7 @@
     assertNotSuggested('index');
   }
 
-  test_ForEachStatement3() async {
+  Future<void> test_ForEachStatement3() async {
     // SimpleIdentifier ParenthesizedExpression  ForEachStatement
     addTestSource('main() {List<int> values; for (int index in (i^))}');
     await computeSuggestions();
@@ -2614,7 +2616,7 @@
     assertNotSuggested('index');
   }
 
-  test_ForEachStatement_body_typed() async {
+  Future<void> test_ForEachStatement_body_typed() async {
     // Block  ForEachStatement
     addTestSource('main(args) {for (int foo in bar) {^}}');
     await computeSuggestions();
@@ -2626,7 +2628,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForEachStatement_body_untyped() async {
+  Future<void> test_ForEachStatement_body_untyped() async {
     // Block  ForEachStatement
     addTestSource('main(args) {for (var foo in bar) {^}}');
     await computeSuggestions();
@@ -2638,7 +2640,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForEachStatement_iterable() async {
+  Future<void> test_ForEachStatement_iterable() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (int foo in ^) {}}');
     await computeSuggestions();
@@ -2649,7 +2651,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForEachStatement_loopVariable() async {
+  Future<void> test_ForEachStatement_loopVariable() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (^ in args) {}}');
     await computeSuggestions();
@@ -2660,7 +2662,7 @@
     assertNotSuggested('String');
   }
 
-  test_ForEachStatement_loopVariable_type() async {
+  Future<void> test_ForEachStatement_loopVariable_type() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (^ foo in args) {}}');
     await computeSuggestions();
@@ -2672,7 +2674,7 @@
     assertNotSuggested('String');
   }
 
-  test_ForEachStatement_loopVariable_type2() async {
+  Future<void> test_ForEachStatement_loopVariable_type2() async {
     // DeclaredIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (S^ foo in args) {}}');
     await computeSuggestions();
@@ -2684,7 +2686,7 @@
     assertNotSuggested('String');
   }
 
-  test_FormalParameterList() async {
+  Future<void> test_FormalParameterList() async {
     // FormalParameterList MethodDeclaration
     addTestSource('''
 foo() { }
@@ -2702,7 +2704,7 @@
     assertNotSuggested('bar');
   }
 
-  test_ForStatement_body() async {
+  Future<void> test_ForStatement_body() async {
     // Block  ForStatement
     addTestSource('main(args) {for (int i; i < 10; ++i) {^}}');
     await computeSuggestions();
@@ -2713,7 +2715,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForStatement_condition() async {
+  Future<void> test_ForStatement_condition() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {for (int index = 0; i^)}');
     await computeSuggestions();
@@ -2723,7 +2725,7 @@
     assertSuggestLocalVariable('index', 'int');
   }
 
-  test_ForStatement_initializer() async {
+  Future<void> test_ForStatement_initializer() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {List a; for (^)}');
     await computeSuggestions();
@@ -2735,7 +2737,7 @@
     assertNotSuggested('int');
   }
 
-  test_ForStatement_updaters() async {
+  Future<void> test_ForStatement_updaters() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {for (int index = 0; index < 10; i^)}');
     await computeSuggestions();
@@ -2745,7 +2747,7 @@
     assertSuggestLocalVariable('index', 'int');
   }
 
-  test_ForStatement_updaters_prefix_expression() async {
+  Future<void> test_ForStatement_updaters_prefix_expression() async {
     // SimpleIdentifier  PrefixExpression  ForStatement
     addTestSource('''
 void bar() { }
@@ -2760,7 +2762,7 @@
     assertNotSuggested('bar');
   }
 
-  test_function_parameters_mixed_required_and_named() async {
+  Future<void> test_function_parameters_mixed_required_and_named() async {
     addTestSource('''
 void m(x, {int y}) {}
 class B extends A {
@@ -2779,7 +2781,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_function_parameters_mixed_required_and_positional() async {
+  Future<void> test_function_parameters_mixed_required_and_positional() async {
     addTestSource('''
 void m(x, [int y]) {}
 class B extends A {
@@ -2798,7 +2800,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_function_parameters_named() async {
+  Future<void> test_function_parameters_named() async {
     addTestSource('''
 void m({x, int y}) {}
 class B extends A {
@@ -2817,7 +2819,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_function_parameters_none() async {
+  Future<void> test_function_parameters_none() async {
     addTestSource('''
 void m() {}
 class B extends A {
@@ -2833,7 +2835,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_function_parameters_positional() async {
+  Future<void> test_function_parameters_positional() async {
     addTestSource('''
 void m([x, int y]) {}
 class B extends A {
@@ -2852,7 +2854,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_function_parameters_required() async {
+  Future<void> test_function_parameters_required() async {
     addTestSource('''
 void m(x, int y) {}
 class B extends A {
@@ -2871,7 +2873,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_FunctionDeclaration_returnType_afterComment() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2901,7 +2903,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionDeclaration_returnType_afterComment2() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment2() async {
     // FunctionDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2931,7 +2933,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionDeclaration_returnType_afterComment3() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment3() async {
     // FunctionDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -2962,7 +2964,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionExpression_body_function() async {
+  Future<void> test_FunctionExpression_body_function() async {
     // Block  BlockFunctionBody  FunctionExpression
     addTestSource('''
         void bar() { }
@@ -2983,7 +2985,7 @@
     assertNotSuggested('Object');
   }
 
-  test_functionTypeAlias_genericTypeAlias() async {
+  Future<void> test_functionTypeAlias_genericTypeAlias() async {
     addTestSource(r'''
 typedef F = void Function();
 main() {
@@ -2994,7 +2996,7 @@
     assertSuggestFunctionTypeAlias('F', 'void');
   }
 
-  test_functionTypeAlias_genericTypeAlias_incomplete() async {
+  Future<void> test_functionTypeAlias_genericTypeAlias_incomplete() async {
     addTestSource(r'''
 typedef F = int;
 main() {
@@ -3005,7 +3007,7 @@
     assertSuggestFunctionTypeAlias('F', 'dynamic');
   }
 
-  test_functionTypeAlias_old() async {
+  Future<void> test_functionTypeAlias_old() async {
     addTestSource(r'''
 typedef void F();
 main() {
@@ -3016,7 +3018,7 @@
     assertSuggestFunctionTypeAlias('F', 'void');
   }
 
-  test_IfStatement() async {
+  Future<void> test_IfStatement() async {
     // SimpleIdentifier  IfStatement
     addTestSource('''
         class A {var b; X _c; foo() {A a; if (true) ^}}''');
@@ -3031,7 +3033,7 @@
     assertNotSuggested('==');
   }
 
-  test_IfStatement_condition() async {
+  Future<void> test_IfStatement_condition() async {
     // SimpleIdentifier  IfStatement  Block  BlockFunctionBody
     addTestSource('''
 class A {int x; int y() => 0;}
@@ -3047,7 +3049,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IfStatement_empty() async {
+  Future<void> test_IfStatement_empty() async {
     // SimpleIdentifier  IfStatement
     addTestSource('''
         class A {var b; X _c; foo() {A a; if (^) something}}''');
@@ -3062,7 +3064,7 @@
     assertNotSuggested('==');
   }
 
-  test_IfStatement_empty_private() async {
+  Future<void> test_IfStatement_empty_private() async {
     // SimpleIdentifier  IfStatement
     addTestSource('''
         class A {var b; X _c; foo() {A a; if (_^) something}}''');
@@ -3077,7 +3079,7 @@
     assertNotSuggested('==');
   }
 
-  test_IfStatement_invocation() async {
+  Future<void> test_IfStatement_invocation() async {
     // SimpleIdentifier  PrefixIdentifier  IfStatement
     addTestSource('''
 main() {var a; if (a.^) something}''');
@@ -3091,14 +3093,14 @@
     assertNotSuggested('==');
   }
 
-  test_ignore_symbol_being_completed() async {
+  Future<void> test_ignore_symbol_being_completed() async {
     addTestSource('class MyClass { } main(MC^) { }');
     await computeSuggestions();
     assertSuggestClass('MyClass');
     assertNotSuggested('MC');
   }
 
-  test_implementsClause() async {
+  Future<void> test_implementsClause() async {
     addTestSource('''
 class A {}
 mixin M {}
@@ -3109,7 +3111,7 @@
     assertSuggestMixin('M');
   }
 
-  test_ImportDirective_dart() async {
+  Future<void> test_ImportDirective_dart() async {
     // SimpleStringLiteral  ImportDirective
     addTestSource('''
 import "dart^";
@@ -3119,7 +3121,7 @@
     assertNoSuggestions();
   }
 
-  test_inDartDoc_reference3() async {
+  Future<void> test_inDartDoc_reference3() async {
     addTestSource('''
 /// The [^]
 main(aaa, bbb) {}''');
@@ -3129,7 +3131,7 @@
         relevance: DART_RELEVANCE_LOCAL_FUNCTION);
   }
 
-  test_inDartDoc_reference4() async {
+  Future<void> test_inDartDoc_reference4() async {
     addTestSource('''
 /// The [m^]
 main(aaa, bbb) {}''');
@@ -3139,7 +3141,7 @@
         relevance: DART_RELEVANCE_LOCAL_FUNCTION);
   }
 
-  test_IndexExpression() async {
+  Future<void> test_IndexExpression() async {
     // ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3167,7 +3169,7 @@
     //assertNotSuggested('T1');
   }
 
-  test_IndexExpression2() async {
+  Future<void> test_IndexExpression2() async {
     // SimpleIdentifier IndexExpression ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3188,13 +3190,13 @@
     //assertNotSuggested('T1');
   }
 
-  test_inferredType() async {
+  Future<void> test_inferredType() async {
     addTestSource('main() { var v = 42; ^ }');
     await computeSuggestions();
     assertSuggestLocalVariable('v', 'int');
   }
 
-  test_InstanceCreationExpression() async {
+  Future<void> test_InstanceCreationExpression() async {
     addTestSource('''
 class A {foo(){var f; {var x;}}}
 class B {B(this.x, [String boo]) { } int x;}
@@ -3205,7 +3207,7 @@
     assertNoSuggestions();
   }
 
-  test_InstanceCreationExpression_imported() async {
+  Future<void> test_InstanceCreationExpression_imported() async {
     // SimpleIdentifier  TypeName  ConstructorName  InstanceCreationExpression
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3237,7 +3239,7 @@
     assertNotSuggested('T2');
   }
 
-  test_InstanceCreationExpression_unimported() async {
+  Future<void> test_InstanceCreationExpression_unimported() async {
     // SimpleIdentifier  TypeName  ConstructorName  InstanceCreationExpression
     addSource('/home/test/lib/ab.dart', 'class Foo { }');
     addTestSource('class C {foo(){new F^}}');
@@ -3249,7 +3251,7 @@
     assertNotSuggested('Foo');
   }
 
-  test_InterpolationExpression() async {
+  Future<void> test_InterpolationExpression() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3280,7 +3282,7 @@
     assertSuggestLocalVariable('name', 'String');
   }
 
-  test_InterpolationExpression_block() async {
+  Future<void> test_InterpolationExpression_block() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3311,7 +3313,7 @@
     assertSuggestLocalVariable('name', 'String');
   }
 
-  test_InterpolationExpression_block2() async {
+  Future<void> test_InterpolationExpression_block2() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addTestSource('main() {String name; print("hello \${n^}");}');
     await computeSuggestions();
@@ -3321,7 +3323,7 @@
     //assertNotSuggested('Object');
   }
 
-  test_InterpolationExpression_prefix_selector() async {
+  Future<void> test_InterpolationExpression_prefix_selector() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \${name.^}");}');
     await computeSuggestions();
@@ -3334,7 +3336,7 @@
     assertNotSuggested('==');
   }
 
-  test_InterpolationExpression_prefix_selector2() async {
+  Future<void> test_InterpolationExpression_prefix_selector2() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \$name.^");}');
     await computeSuggestions();
@@ -3342,7 +3344,7 @@
     assertNoSuggestions();
   }
 
-  test_InterpolationExpression_prefix_target() async {
+  Future<void> test_InterpolationExpression_prefix_target() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \${nam^e.length}");}');
     await computeSuggestions();
@@ -3353,7 +3355,7 @@
     assertNotSuggested('length');
   }
 
-  test_IsExpression() async {
+  Future<void> test_IsExpression() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -3374,7 +3376,7 @@
     assertNotSuggested('foo');
   }
 
-  test_IsExpression_target() async {
+  Future<void> test_IsExpression_target() async {
     // IfStatement  Block  BlockFunctionBody
     addTestSource('''
 foo() { }
@@ -3395,7 +3397,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IsExpression_type() async {
+  Future<void> test_IsExpression_type() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addTestSource('''
 class A {int x; int y() => 0;}
@@ -3410,7 +3412,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IsExpression_type_filter_extends() async {
+  Future<void> test_IsExpression_type_filter_extends() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addTestSource('''
 class A {} class B extends A {} class C extends A {} class D {}
@@ -3426,7 +3428,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IsExpression_type_filter_implements() async {
+  Future<void> test_IsExpression_type_filter_implements() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addTestSource('''
 class A {} class B implements A {} class C implements A {} class D {}
@@ -3442,7 +3444,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IsExpression_type_filter_undefined_type() async {
+  Future<void> test_IsExpression_type_filter_undefined_type() async {
     // SimpleIdentifier  TypeName  AsExpression
     addTestSource('''
 class A {}
@@ -3454,7 +3456,7 @@
     assertSuggestClass('A');
   }
 
-  test_IsExpression_type_partial() async {
+  Future<void> test_IsExpression_type_partial() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addTestSource('''
 class A {int x; int y() => 0;}
@@ -3469,7 +3471,7 @@
     assertNotSuggested('Object');
   }
 
-  test_keyword() async {
+  Future<void> test_keyword() async {
     addSource('/home/test/lib/b.dart', '''
 lib B;
 int newT1;
@@ -3498,7 +3500,7 @@
         relevance: DART_RELEVANCE_LOCAL_FUNCTION);
   }
 
-  test_Literal_list() async {
+  Future<void> test_Literal_list() async {
     // ']'  ListLiteral  ArgumentList  MethodInvocation
     addTestSource('main() {var Some; print([^]);}');
     await computeSuggestions();
@@ -3507,7 +3509,7 @@
     assertNotSuggested('String');
   }
 
-  test_Literal_list2() async {
+  Future<void> test_Literal_list2() async {
     // SimpleIdentifier ListLiteral  ArgumentList  MethodInvocation
     addTestSource('main() {var Some; print([S^]);}');
     await computeSuggestions();
@@ -3516,7 +3518,7 @@
     assertNotSuggested('String');
   }
 
-  test_Literal_string() async {
+  Future<void> test_Literal_string() async {
     // SimpleStringLiteral  ExpressionStatement  Block
     addTestSource('class A {a() {"hel^lo"}}');
     await computeSuggestions();
@@ -3524,7 +3526,7 @@
     assertNoSuggestions();
   }
 
-  test_localVariableDeclarationName() async {
+  Future<void> test_localVariableDeclarationName() async {
     addTestSource('main() {String m^}');
     await computeSuggestions();
 
@@ -3532,7 +3534,7 @@
     assertNotSuggested('min');
   }
 
-  test_MapLiteralEntry() async {
+  Future<void> test_MapLiteralEntry() async {
     // MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3562,7 +3564,7 @@
     assertSuggestClass('C2');
   }
 
-  test_MapLiteralEntry1() async {
+  Future<void> test_MapLiteralEntry1() async {
     // MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3585,7 +3587,7 @@
         relevance: DART_RELEVANCE_LOCAL_TOP_LEVEL_VARIABLE);
   }
 
-  test_MapLiteralEntry2() async {
+  Future<void> test_MapLiteralEntry2() async {
     // SimpleIdentifier  MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3608,7 +3610,7 @@
         relevance: DART_RELEVANCE_LOCAL_TOP_LEVEL_VARIABLE);
   }
 
-  test_method_parameters_mixed_required_and_named() async {
+  Future<void> test_method_parameters_mixed_required_and_named() async {
     addTestSource('''
 class A {
   void m(x, {int y}) {}
@@ -3621,7 +3623,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_parameters_mixed_required_and_positional() async {
+  Future<void> test_method_parameters_mixed_required_and_positional() async {
     addTestSource('''
 class A {
   void m(x, [int y]) {}
@@ -3634,7 +3636,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_parameters_named() async {
+  Future<void> test_method_parameters_named() async {
     addTestSource('''
 class A {
   void m({x, int y}) {}
@@ -3647,7 +3649,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_parameters_none() async {
+  Future<void> test_method_parameters_none() async {
     addTestSource('''
 class A {
   void m() {}
@@ -3660,7 +3662,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_parameters_positional() async {
+  Future<void> test_method_parameters_positional() async {
     addTestSource('''
 class A {
   void m([x, int y]) {}
@@ -3673,7 +3675,7 @@
     assertNotSuggested('m');
   }
 
-  test_method_parameters_required() async {
+  Future<void> test_method_parameters_required() async {
     addTestSource('''
 class A {
   void m(x, int y) {}
@@ -3686,7 +3688,7 @@
     assertNotSuggested('m');
   }
 
-  test_MethodDeclaration_body_getters() async {
+  Future<void> test_MethodDeclaration_body_getters() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated X get f => 0; Z a() {^} get _g => 1;}');
     await computeSuggestions();
@@ -3713,7 +3715,7 @@
     }
   }
 
-  test_MethodDeclaration_body_static() async {
+  Future<void> test_MethodDeclaration_body_static() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/c.dart', '''
 class C {
@@ -3751,7 +3753,7 @@
     assertNotSuggested('c4');
   }
 
-  test_MethodDeclaration_members() async {
+  Future<void> test_MethodDeclaration_members() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated X f; Z _a() {^} var _g;}');
     await computeSuggestions();
@@ -3782,7 +3784,7 @@
     assertNotSuggested('bool');
   }
 
-  test_MethodDeclaration_members_private() async {
+  Future<void> test_MethodDeclaration_members_private() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated X f; Z _a() {_^} var _g;}');
     await computeSuggestions();
@@ -3814,7 +3816,7 @@
     assertNotSuggested('bool');
   }
 
-  test_MethodDeclaration_parameters_named() async {
+  Future<void> test_MethodDeclaration_parameters_named() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated Z a(X x, _, b, {y: boo}) {^}}');
     await computeSuggestions();
@@ -3834,7 +3836,7 @@
     assertNotSuggested('_');
   }
 
-  test_MethodDeclaration_parameters_positional() async {
+  Future<void> test_MethodDeclaration_parameters_positional() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('''
 foo() { }
@@ -3854,7 +3856,7 @@
     assertNotSuggested('String');
   }
 
-  test_MethodDeclaration_returnType() async {
+  Future<void> test_MethodDeclaration_returnType() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3883,7 +3885,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3912,7 +3914,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment2() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment2() async {
     // MethodDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3941,7 +3943,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment3() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment3() async {
     // MethodDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
 int T1;
@@ -3972,7 +3974,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodInvocation_no_semicolon() async {
+  Future<void> test_MethodInvocation_no_semicolon() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
 main() { }
@@ -4005,22 +4007,22 @@
     assertNotSuggested('==');
   }
 
-  test_missing_params_constructor() async {
+  Future<void> test_missing_params_constructor() async {
     addTestSource('class C1{C1{} main(){C^}}');
     await computeSuggestions();
   }
 
-  test_missing_params_function() async {
+  Future<void> test_missing_params_function() async {
     addTestSource('int f1{} main(){f^}');
     await computeSuggestions();
   }
 
-  test_missing_params_method() async {
+  Future<void> test_missing_params_method() async {
     addTestSource('class C1{int f1{} main(){f^}}');
     await computeSuggestions();
   }
 
-  test_mixinDeclaration_body() async {
+  Future<void> test_mixinDeclaration_body() async {
     // MixinDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -4049,7 +4051,7 @@
     assertNotSuggested('x');
   }
 
-  test_mixinDeclaration_method_access() async {
+  Future<void> test_mixinDeclaration_method_access() async {
     addTestSource(r'''
 class A { }
 
@@ -4062,7 +4064,7 @@
     assertSuggestMethod('_x', 'X', 'int');
   }
 
-  test_mixinDeclaration_property_access() async {
+  Future<void> test_mixinDeclaration_property_access() async {
     addTestSource(r'''
 class A { }
 
@@ -4075,7 +4077,7 @@
     assertSuggestField('_x', 'int');
   }
 
-  test_new_instance() async {
+  Future<void> test_new_instance() async {
     addTestSource('import "dart:math"; class A {x() {new Random().^}}');
     await computeSuggestions();
 
@@ -4087,7 +4089,7 @@
     assertNotSuggested('A');
   }
 
-  test_overrides() async {
+  Future<void> test_overrides() async {
     addTestSource('''
 class A {m() {}}
 class B extends A {m() {^}}
@@ -4096,7 +4098,7 @@
     assertSuggestMethod('m', 'B', null, relevance: DART_RELEVANCE_LOCAL_METHOD);
   }
 
-  test_parameterName_excludeTypes() async {
+  Future<void> test_parameterName_excludeTypes() async {
     addTestSource('m(int ^) {}');
     await computeSuggestions();
 
@@ -4104,7 +4106,7 @@
     assertNotSuggested('bool');
   }
 
-  test_partFile_TypeName() async {
+  Future<void> test_partFile_TypeName() async {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -4138,7 +4140,7 @@
     assertNotSuggested('m');
   }
 
-  test_partFile_TypeName2() async {
+  Future<void> test_partFile_TypeName2() async {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -4172,7 +4174,7 @@
     assertNotSuggested('m');
   }
 
-  test_PrefixedIdentifier_class_const() async {
+  Future<void> test_PrefixedIdentifier_class_const() async {
     // SimpleIdentifier PrefixedIdentifier ExpressionStatement Block
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -4219,7 +4221,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_class_imported() async {
+  Future<void> test_PrefixedIdentifier_class_imported() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -4256,7 +4258,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_class_local() async {
+  Future<void> test_PrefixedIdentifier_class_local() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
 main() {A a; a.^}
@@ -4290,7 +4292,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_getter() async {
+  Future<void> test_PrefixedIdentifier_getter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String get g => "one"; f() {g.^}');
     await computeSuggestions();
@@ -4298,7 +4300,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_library() async {
+  Future<void> test_PrefixedIdentifier_library() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -4325,7 +4327,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_typesOnly() async {
+  Future<void> test_PrefixedIdentifier_library_typesOnly() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -4352,7 +4354,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_typesOnly2() async {
+  Future<void> test_PrefixedIdentifier_library_typesOnly2() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -4379,7 +4381,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_parameter() async {
+  Future<void> test_PrefixedIdentifier_parameter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
 lib B;
@@ -4398,7 +4400,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_prefix() async {
+  Future<void> test_PrefixedIdentifier_prefix() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
 class A {static int bar = 10;}
@@ -4418,7 +4420,7 @@
     assertNotSuggested('_B');
   }
 
-  test_PrefixedIdentifier_propertyAccess() async {
+  Future<void> test_PrefixedIdentifier_propertyAccess() async {
     // PrefixedIdentifier  ExpressionStatement  Block  BlockFunctionBody
     addTestSource('class A {String x; int get foo {x.^}');
     await computeSuggestions();
@@ -4429,7 +4431,7 @@
     assertNotSuggested('compareTo');
   }
 
-  test_PrefixedIdentifier_propertyAccess_newStmt() async {
+  Future<void> test_PrefixedIdentifier_propertyAccess_newStmt() async {
     // PrefixedIdentifier  ExpressionStatement  Block  BlockFunctionBody
     addTestSource('class A {String x; int get foo {x.^ int y = 0;}');
     await computeSuggestions();
@@ -4440,7 +4442,7 @@
     assertNotSuggested('compareTo');
   }
 
-  test_PrefixedIdentifier_trailingStmt_const() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_const() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('const String g = "hello"; f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -4448,7 +4450,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_field() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_field() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {String g; f() {g.^ int y = 0;}}');
     await computeSuggestions();
@@ -4456,7 +4458,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_function() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_function() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String g() => "one"; f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -4464,7 +4466,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_functionTypeAlias() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_functionTypeAlias() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('typedef String g(); f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -4472,7 +4474,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_getter() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_getter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String get g => "one"; f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -4480,7 +4482,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_local_typed() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_local_typed() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f() {String g; g.^ int y = 0;}');
     await computeSuggestions();
@@ -4488,7 +4490,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_local_untyped() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_local_untyped() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f() {var g = "hello"; g.^ int y = 0;}');
     await computeSuggestions();
@@ -4496,7 +4498,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_method() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_method() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {String g() {}; f() {g.^ int y = 0;}}');
     await computeSuggestions();
@@ -4504,7 +4506,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_param() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_param() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {f(String g) {g.^ int y = 0;}}');
     await computeSuggestions();
@@ -4512,7 +4514,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_param2() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_param2() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f(String g) {g.^ int y = 0;}');
     await computeSuggestions();
@@ -4520,7 +4522,7 @@
     assertNotSuggested('length');
   }
 
-  test_PrefixedIdentifier_trailingStmt_topLevelVar() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_topLevelVar() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String g; f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -4528,28 +4530,28 @@
     assertNotSuggested('length');
   }
 
-  test_prioritization() async {
+  Future<void> test_prioritization() async {
     addTestSource('main() {var ab; var _ab; ^}');
     await computeSuggestions();
     assertSuggestLocalVariable('ab', null);
     assertSuggestLocalVariable('_ab', null, relevance: DART_RELEVANCE_DEFAULT);
   }
 
-  test_prioritization_private() async {
+  Future<void> test_prioritization_private() async {
     addTestSource('main() {var ab; var _ab; _^}');
     await computeSuggestions();
     assertSuggestLocalVariable('ab', null);
     assertSuggestLocalVariable('_ab', null);
   }
 
-  test_prioritization_public() async {
+  Future<void> test_prioritization_public() async {
     addTestSource('main() {var ab; var _ab; a^}');
     await computeSuggestions();
     assertSuggestLocalVariable('ab', null);
     assertSuggestLocalVariable('_ab', null, relevance: DART_RELEVANCE_DEFAULT);
   }
 
-  test_PropertyAccess_expression() async {
+  Future<void> test_PropertyAccess_expression() async {
     // SimpleIdentifier  MethodInvocation  PropertyAccess  ExpressionStatement
     addTestSource('class A {a() {"hello".to^String().length}}');
     await computeSuggestions();
@@ -4563,7 +4565,7 @@
     assertNotSuggested('==');
   }
 
-  test_PropertyAccess_noTarget() async {
+  Future<void> test_PropertyAccess_noTarget() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement
     addSource('/home/test/lib/ab.dart', 'class Foo { }');
     addTestSource('class C {foo(){.^}}');
@@ -4572,7 +4574,7 @@
     assertNoSuggestions();
   }
 
-  test_PropertyAccess_noTarget2() async {
+  Future<void> test_PropertyAccess_noTarget2() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement
     addSource('/home/test/lib/ab.dart', 'class Foo { }');
     addTestSource('main() {.^}');
@@ -4581,7 +4583,7 @@
     assertNoSuggestions();
   }
 
-  test_PropertyAccess_selector() async {
+  Future<void> test_PropertyAccess_selector() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement  Block
     addTestSource('class A {a() {"hello".length.^}}');
     await computeSuggestions();
@@ -4595,13 +4597,13 @@
     assertNotSuggested('==');
   }
 
-  test_shadowed_name() async {
+  Future<void> test_shadowed_name() async {
     addTestSource('var a; class A { var a; m() { ^ } }');
     await computeSuggestions();
     assertSuggestField('a', null, relevance: DART_RELEVANCE_LOCAL_FIELD);
   }
 
-  test_SwitchStatement_c() async {
+  Future<void> test_SwitchStatement_c() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {switch(x) {c^}}}');
     await computeSuggestions();
@@ -4609,7 +4611,7 @@
     assertNoSuggestions();
   }
 
-  test_SwitchStatement_case() async {
+  Future<void> test_SwitchStatement_case() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {var t; switch(x) {case 0: ^}}}');
     await computeSuggestions();
@@ -4621,7 +4623,7 @@
     assertNotSuggested('String');
   }
 
-  test_SwitchStatement_case_var() async {
+  Future<void> test_SwitchStatement_case_var() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('g(int x) {var t; switch(x) {case 0: var bar; b^}}');
     await computeSuggestions();
@@ -4634,7 +4636,7 @@
     assertNotSuggested('String');
   }
 
-  test_SwitchStatement_empty() async {
+  Future<void> test_SwitchStatement_empty() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {switch(x) {^}}}');
     await computeSuggestions();
@@ -4642,7 +4644,7 @@
     assertNoSuggestions();
   }
 
-  test_ThisExpression_block() async {
+  Future<void> test_ThisExpression_block() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
 main() { }
@@ -4678,7 +4680,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor() async {
+  Future<void> test_ThisExpression_constructor() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
 main() { }
@@ -4714,7 +4716,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param() async {
+  Future<void> test_ThisExpression_constructor_param() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
 main() { }
@@ -4752,7 +4754,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param2() async {
+  Future<void> test_ThisExpression_constructor_param2() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
 main() { }
@@ -4789,7 +4791,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param3() async {
+  Future<void> test_ThisExpression_constructor_param3() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
 main() { }
@@ -4826,7 +4828,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param4() async {
+  Future<void> test_ThisExpression_constructor_param4() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
 main() { }
@@ -4863,7 +4865,7 @@
     assertNotSuggested('==');
   }
 
-  test_TopLevelVariableDeclaration_typed_name() async {
+  Future<void> test_TopLevelVariableDeclaration_typed_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // TopLevelVariableDeclaration
     addTestSource('class A {} B ^');
@@ -4872,7 +4874,7 @@
     assertNoSuggestions();
   }
 
-  test_TopLevelVariableDeclaration_untyped_name() async {
+  Future<void> test_TopLevelVariableDeclaration_untyped_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // TopLevelVariableDeclaration
     addTestSource('class A {} var ^');
@@ -4881,7 +4883,7 @@
     assertNoSuggestions();
   }
 
-  test_type_typeParameter_classDeclaration() async {
+  Future<void> test_type_typeParameter_classDeclaration() async {
     addTestSource('''
 class A<T> {
   ^ m() {}
@@ -4891,7 +4893,7 @@
     assertSuggestTypeParameter('T');
   }
 
-  test_TypeArgumentList() async {
+  Future<void> test_TypeArgumentList() async {
     // SimpleIdentifier  BinaryExpression  ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
 class C1 {int x;}
@@ -4917,7 +4919,7 @@
     assertNotSuggested('F2');
   }
 
-  test_TypeArgumentList2() async {
+  Future<void> test_TypeArgumentList2() async {
     // TypeName  TypeArgumentList  TypeName
     addSource('/home/test/lib/a.dart', '''
 class C1 {int x;}
@@ -4938,7 +4940,7 @@
     assertSuggestClass('C2');
   }
 
-  test_VariableDeclaration_name() async {
+  Future<void> test_VariableDeclaration_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addSource('/home/test/lib/b.dart', '''
@@ -4955,7 +4957,7 @@
     assertNoSuggestions();
   }
 
-  test_VariableDeclarationList_final() async {
+  Future<void> test_VariableDeclarationList_final() async {
     // VariableDeclarationList  VariableDeclarationStatement  Block
     addTestSource('main() {final ^} class C { }');
     await computeSuggestions();
@@ -4965,7 +4967,7 @@
     assertNotSuggested('==');
   }
 
-  test_VariableDeclarationStatement_RHS() async {
+  Future<void> test_VariableDeclarationStatement_RHS() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement
     addSource('/home/test/lib/b.dart', '''
@@ -4990,7 +4992,7 @@
     assertNotSuggested('e');
   }
 
-  test_VariableDeclarationStatement_RHS_missing_semicolon() async {
+  Future<void> test_VariableDeclarationStatement_RHS_missing_semicolon() async {
     // VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement
     addSource('/home/test/lib/b.dart', '''
@@ -5023,7 +5025,7 @@
     assertNotSuggested('e');
   }
 
-  test_withClause_mixin() async {
+  Future<void> test_withClause_mixin() async {
     addTestSource('''
 class A {}
 mixin M {}
@@ -5033,7 +5035,7 @@
     assertSuggestMixin('M');
   }
 
-  test_YieldStatement() async {
+  Future<void> test_YieldStatement() async {
     addTestSource('''
 void main() async* {
   var value;
@@ -5059,7 +5061,7 @@
     super.setUp();
   }
 
-  test_extensionDeclaration_inMethod() async {
+  Future<void> test_extensionDeclaration_inMethod() async {
     // ExtensionDeclaration  CompilationUnit
     addTestSource('''
 extension E on int {}
@@ -5076,7 +5078,7 @@
     assertSuggest('E');
   }
 
-  test_extensionDeclaration_notInBody() async {
+  Future<void> test_extensionDeclaration_notInBody() async {
     // ExtensionDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
 class B { }''');
@@ -5101,7 +5103,7 @@
     assertNotSuggested('x');
   }
 
-  test_extensionDeclaration_unnamed() async {
+  Future<void> test_extensionDeclaration_unnamed() async {
     addTestSource('''
 extension on String {
   void something() => this.^
diff --git a/pkg/analysis_server/test/services/completion/dart/named_constructor_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/named_constructor_contributor_test.dart
index 3cc14d5..4c0b1c5 100644
--- a/pkg/analysis_server/test/services/completion/dart/named_constructor_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/named_constructor_contributor_test.dart
@@ -10,7 +10,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(NamedConstructorContributorTest);
   });
@@ -42,7 +42,7 @@
     return NamedConstructorContributor();
   }
 
-  test_ConstructorName_importedClass() async {
+  Future<void> test_ConstructorName_importedClass() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -66,7 +66,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedClass_unresolved() async {
+  Future<void> test_ConstructorName_importedClass_unresolved() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -91,7 +91,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedFactory() async {
+  Future<void> test_ConstructorName_importedFactory() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -115,7 +115,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedFactory2() async {
+  Future<void> test_ConstructorName_importedFactory2() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -131,7 +131,7 @@
     assertNotSuggested('String');
   }
 
-  test_ConstructorName_localClass() async {
+  Future<void> test_ConstructorName_localClass() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -150,7 +150,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_localFactory() async {
+  Future<void> test_ConstructorName_localFactory() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
diff --git a/pkg/analysis_server/test/services/completion/dart/override_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/override_contributor_test.dart
index 6cdf195..a43e2ea 100644
--- a/pkg/analysis_server/test/services/completion/dart/override_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/override_contributor_test.dart
@@ -10,7 +10,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveTests(OverrideContributorTest);
 }
 
@@ -21,7 +21,7 @@
     return OverrideContributor();
   }
 
-  test_alreadyOverridden() async {
+  Future<void> test_alreadyOverridden() async {
     addTestSource('''
 class A {
   void foo() {}
@@ -37,7 +37,7 @@
     _assertNoOverrideContaining('bar');
   }
 
-  test_customOperator() async {
+  Future<void> test_customOperator() async {
     addTestSource('''
 class A {
   void operator &(A other) { }
@@ -58,7 +58,7 @@
         selectionLength: 14);
   }
 
-  test_equalsOperator() async {
+  Future<void> test_equalsOperator() async {
     addTestSource('''
 class A {
   other^
@@ -76,7 +76,7 @@
         selectionLength: 22);
   }
 
-  test_fromMultipleSuperclasses() async {
+  Future<void> test_fromMultipleSuperclasses() async {
     addTestSource(r'''
 class A {
   A suggested1(int x) => null;
@@ -147,7 +147,7 @@
         selectionLength: 16);
   }
 
-  test_fromPart() async {
+  Future<void> test_fromPart() async {
     addSource('/home/test/lib/myLib.dart', '''
 library myLib;
 part 'test.dart';
@@ -207,7 +207,7 @@
         selectionLength: 27);
   }
 
-  test_inClass_of_interface() async {
+  Future<void> test_inClass_of_interface() async {
     addTestSource('''
 class A {
   void foo() {}
@@ -225,7 +225,7 @@
   }''', displayText: 'foo() { … }', selectionOffset: 51, selectionLength: 0);
   }
 
-  test_inMixin_of_interface() async {
+  Future<void> test_inMixin_of_interface() async {
     addTestSource('''
 class A {
   void foo() {}
@@ -243,7 +243,7 @@
   }''', displayText: 'foo() { … }', selectionOffset: 51, selectionLength: 0);
   }
 
-  test_inMixin_of_superclassConstraint() async {
+  Future<void> test_inMixin_of_superclassConstraint() async {
     addTestSource('''
 class A {
   void foo() {}
@@ -263,7 +263,7 @@
   }
 
   @failingTest
-  test_insideBareClass() async {
+  Future<void> test_insideBareClass() async {
     addTestSource('''
 class A {
   method() {}
@@ -285,7 +285,7 @@
         selectionLength: 22);
   }
 
-  test_outsideOfWorkspace() async {
+  Future<void> test_outsideOfWorkspace() async {
     testFile = convertPath('/home/other/lib/a.dart');
     addTestSource('''
 class A {
@@ -300,7 +300,7 @@
     _assertNoOverrideContaining('foo');
   }
 
-  test_private_otherLibrary() async {
+  Future<void> test_private_otherLibrary() async {
     addSource('/home/test/lib/a.dart', '''
 class A {
   void foo() {}
@@ -328,7 +328,7 @@
     }));
   }
 
-  test_private_thisLibrary() async {
+  Future<void> test_private_thisLibrary() async {
     addTestSource(r'''
 class A {
   void foo() {}
@@ -356,7 +356,7 @@
   }''', displayText: '_bar() { … }', selectionOffset: 58, selectionLength: 13);
   }
 
-  test_withExistingOverride() async {
+  Future<void> test_withExistingOverride() async {
     addTestSource('''
 class A {
   method() {}
@@ -380,7 +380,7 @@
   }
 
   @failingTest
-  test_withOverrideAnnotation() async {
+  Future<void> test_withOverrideAnnotation() async {
     addTestSource('''
 class A {
   method() {}
diff --git a/pkg/analysis_server/test/services/completion/dart/relevance/arglist_parameter_relevance_test.dart b/pkg/analysis_server/test/services/completion/dart/relevance/arglist_parameter_relevance_test.dart
index 34e36ee..9b11de9 100644
--- a/pkg/analysis_server/test/services/completion/dart/relevance/arglist_parameter_relevance_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/relevance/arglist_parameter_relevance_test.dart
@@ -7,7 +7,7 @@
 
 import '../completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ArglistParameterRelevanceTest);
   });
@@ -15,7 +15,7 @@
 
 @reflectiveTest
 class ArglistParameterRelevanceTest extends DartCompletionManagerTest {
-  test_closureParam() async {
+  Future<void> test_closureParam() async {
     addTestSource(r'''
 void f({void Function(int a, {int b, int c}) closure}) {}
 
diff --git a/pkg/analysis_server/test/services/completion/dart/relevance/bool_assignment_relevance_test.dart b/pkg/analysis_server/test/services/completion/dart/relevance/bool_assignment_relevance_test.dart
index f39ef0d..32cd07f 100644
--- a/pkg/analysis_server/test/services/completion/dart/relevance/bool_assignment_relevance_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/relevance/bool_assignment_relevance_test.dart
@@ -8,7 +8,7 @@
 
 import '../completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(BoolAssignmentRelevanceTest);
   });
@@ -16,35 +16,8 @@
 
 @reflectiveTest
 class BoolAssignmentRelevanceTest extends DartCompletionManagerTest {
-  /// These are 2 failing tests for http://dartbug.com/37907:
-  /// "Suggest `false` above other results when autocompleting a bool setter"
   @failingTest
-  test_boolLiterals_local() async {
-    addTestSource('''
-foo() {
-  bool b;
-  b = ^
-}
-''');
-    await computeSuggestions();
-
-    var trueSuggestion = suggestionWith(
-        completion: 'true', kind: CompletionSuggestionKind.KEYWORD);
-
-    var falseSuggestion = suggestionWith(
-        completion: 'false', kind: CompletionSuggestionKind.KEYWORD);
-
-    var bLocalVar = suggestionWith(
-        completion: 'b',
-        element: ElementKind.LOCAL_VARIABLE,
-        kind: CompletionSuggestionKind.INVOCATION);
-
-    expect(trueSuggestion.relevance, greaterThan(bLocalVar.relevance));
-    expect(falseSuggestion.relevance, greaterThan(bLocalVar.relevance));
-  }
-
-  @failingTest
-  test_boolLiterals_imported() async {
+  Future<void> test_boolLiterals_imported() async {
     addTestSource('''
 foo() {
   bool b;
@@ -69,4 +42,31 @@
     expect(
         falseSuggestion.relevance, greaterThan(boolFromEnvironment.relevance));
   }
+
+  /// These are 2 failing tests for http://dartbug.com/37907:
+  /// "Suggest `false` above other results when autocompleting a bool setter"
+  @failingTest
+  Future<void> test_boolLiterals_local() async {
+    addTestSource('''
+foo() {
+  bool b;
+  b = ^
+}
+''');
+    await computeSuggestions();
+
+    var trueSuggestion = suggestionWith(
+        completion: 'true', kind: CompletionSuggestionKind.KEYWORD);
+
+    var falseSuggestion = suggestionWith(
+        completion: 'false', kind: CompletionSuggestionKind.KEYWORD);
+
+    var bLocalVar = suggestionWith(
+        completion: 'b',
+        element: ElementKind.LOCAL_VARIABLE,
+        kind: CompletionSuggestionKind.INVOCATION);
+
+    expect(trueSuggestion.relevance, greaterThan(bLocalVar.relevance));
+    expect(falseSuggestion.relevance, greaterThan(bLocalVar.relevance));
+  }
 }
diff --git a/pkg/analysis_server/test/services/completion/dart/relevance/deprecated_member_relevance_test.dart b/pkg/analysis_server/test/services/completion/dart/relevance/deprecated_member_relevance_test.dart
index dbc3884..fd10530 100644
--- a/pkg/analysis_server/test/services/completion/dart/relevance/deprecated_member_relevance_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/relevance/deprecated_member_relevance_test.dart
@@ -8,7 +8,7 @@
 
 import '../completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(DeprecatedMemberRelevanceTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class DeprecatedMemberRelevanceTest extends DartCompletionManagerTest {
-  test_deprecated() async {
+  Future<void> test_deprecated() async {
     addTestSource('''
 class A {
   void a1() { }
diff --git a/pkg/analysis_server/test/services/completion/dart/relevance/test_all.dart b/pkg/analysis_server/test/services/completion/dart/relevance/test_all.dart
index 36651e0..c0f3240 100644
--- a/pkg/analysis_server/test/services/completion/dart/relevance/test_all.dart
+++ b/pkg/analysis_server/test/services/completion/dart/relevance/test_all.dart
@@ -8,7 +8,7 @@
 import 'bool_assignment_relevance_test.dart' as bool_assignments;
 import 'deprecated_member_relevance_test.dart' as deprecated_members;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     arglist_parameters.main();
     bool_assignments.main();
diff --git a/pkg/analysis_server/test/services/completion/dart/static_member_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/static_member_contributor_test.dart
index 199ebcb..c3c7033 100644
--- a/pkg/analysis_server/test/services/completion/dart/static_member_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/static_member_contributor_test.dart
@@ -10,7 +10,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(StaticMemberContributorTest);
     defineReflectiveTests(StaticMemberContributorWithExtensionMethodsTest);
@@ -24,7 +24,7 @@
     return StaticMemberContributor();
   }
 
-  test_enumConst() async {
+  Future<void> test_enumConst() async {
     addTestSource('enum E { one, two } main() {E.^}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -34,7 +34,7 @@
     assertSuggestField('values', 'List<E>');
   }
 
-  test_enumConst2() async {
+  Future<void> test_enumConst2() async {
     addTestSource('enum E { one, two } main() {E.o^}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -44,7 +44,7 @@
     assertSuggestField('values', 'List<E>');
   }
 
-  test_enumConst3() async {
+  Future<void> test_enumConst3() async {
     addTestSource('enum E { one, two } main() {E.^ int g;}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -54,13 +54,13 @@
     assertSuggestField('values', 'List<E>');
   }
 
-  test_enumConst_cascade1() async {
+  Future<void> test_enumConst_cascade1() async {
     addTestSource('enum E { one, two } main() {E..^}');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_enumConst_cascade2() async {
+  Future<void> test_enumConst_cascade2() async {
     addTestSource('enum E { one, two } main() {E.^.}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -70,13 +70,13 @@
     assertSuggestField('values', 'List<E>');
   }
 
-  test_enumConst_cascade3() async {
+  Future<void> test_enumConst_cascade3() async {
     addTestSource('enum E { one, two } main() {E..o^}');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_enumConst_cascade4() async {
+  Future<void> test_enumConst_cascade4() async {
     addTestSource('enum E { one, two } main() {E.^.o}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -87,7 +87,7 @@
   }
 
   @failingTest
-  test_enumConst_deprecated() async {
+  Future<void> test_enumConst_deprecated() async {
     addTestSource('@deprecated enum E { one, two } main() {E.^}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -99,7 +99,7 @@
     assertSuggestField('values', 'List<E>', isDeprecated: true);
   }
 
-  test_implicitCreation() async {
+  Future<void> test_implicitCreation() async {
     addSource('/home/test/lib/a.dart', '''
 class A {
   A.foo();
@@ -119,13 +119,13 @@
     assertSuggestConstructor('bar', elementName: 'bar');
   }
 
-  test_keyword() async {
+  Future<void> test_keyword() async {
     addTestSource('class C { static C get instance => null; } main() {C.in^}');
     await computeSuggestions();
     assertSuggestGetter('instance', 'C');
   }
 
-  test_only_static() async {
+  Future<void> test_only_static() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
 class B {
@@ -146,7 +146,7 @@
     assertSuggestMethod('m2', 'C', null);
   }
 
-  test_only_static2() async {
+  Future<void> test_only_static2() async {
     // SimpleIdentifier  MethodInvocation  ExpressionStatement
     addTestSource('''
 class B {
@@ -167,7 +167,7 @@
     assertSuggestMethod('m2', 'C', null);
   }
 
-  test_only_static_cascade1() async {
+  Future<void> test_only_static_cascade1() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
 class B {
@@ -184,7 +184,7 @@
     assertNoSuggestions();
   }
 
-  test_only_static_cascade2() async {
+  Future<void> test_only_static_cascade2() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
 class B {
@@ -205,7 +205,7 @@
     assertSuggestMethod('m2', 'C', null);
   }
 
-  test_only_static_cascade3() async {
+  Future<void> test_only_static_cascade3() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
 class B {
@@ -222,7 +222,7 @@
     assertNoSuggestions();
   }
 
-  test_only_static_cascade4() async {
+  Future<void> test_only_static_cascade4() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
 class B {
@@ -243,7 +243,7 @@
     assertSuggestMethod('m2', 'C', null);
   }
 
-  test_only_static_cascade_prefixed1() async {
+  Future<void> test_only_static_cascade_prefixed1() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
 import "dart:async" as async;
@@ -252,7 +252,7 @@
     assertNoSuggestions();
   }
 
-  test_only_static_cascade_prefixed2() async {
+  Future<void> test_only_static_cascade_prefixed2() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
 import "dart:async" as async;
@@ -261,7 +261,7 @@
     assertSuggestMethod('wait', 'Future', 'Future<List<T>>');
   }
 
-  test_PrefixedIdentifier_class_const() async {
+  Future<void> test_PrefixedIdentifier_class_const() async {
     // SimpleIdentifier PrefixedIdentifier ExpressionStatement Block
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -321,7 +321,7 @@
     createAnalysisOptionsFile(experiments: [EnableString.extension_methods]);
   }
 
-  test_extension() async {
+  Future<void> test_extension() async {
     addTestSource('''
 extension E on Object {
   static int i;
diff --git a/pkg/analysis_server/test/services/completion/dart/test_all.dart b/pkg/analysis_server/test/services/completion/dart/test_all.dart
index 834e5cf..181a87e 100644
--- a/pkg/analysis_server/test/services/completion/dart/test_all.dart
+++ b/pkg/analysis_server/test/services/completion/dart/test_all.dart
@@ -33,7 +33,7 @@
 import 'uri_contributor_test.dart' as uri_contributor_test;
 import 'variable_name_contributor_test.dart' as variable_name_contributor_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     arglist_test.main();
     combinator_test.main();
diff --git a/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart
index 26e0c7f..051c7ff 100644
--- a/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart
@@ -12,7 +12,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(TypeMemberContributorTest);
     defineReflectiveTests(TypeMemberContributorWithExtensionMethodsTest);
@@ -57,7 +57,7 @@
     return TypeMemberContributor();
   }
 
-  test_ArgDefaults_method() async {
+  Future<void> test_ArgDefaults_method() async {
     addTestSource('''
 class A {
   bool a(int b, bool c) => false;
@@ -69,7 +69,7 @@
     assertSuggestMethod('a', 'A', 'bool', defaultArgListString: 'b, c');
   }
 
-  test_ArgDefaults_method_none() async {
+  Future<void> test_ArgDefaults_method_none() async {
     addTestSource('''
 class A {
   bool a() => false;
@@ -81,7 +81,7 @@
     assertSuggestMethod('a', 'A', 'bool', defaultArgListString: null);
   }
 
-  test_ArgDefaults_method_with_optional_positional() async {
+  Future<void> test_ArgDefaults_method_with_optional_positional() async {
     addMetaPackage();
     addTestSource('''
 import 'package:meta/meta.dart';
@@ -96,7 +96,7 @@
     assertSuggestMethod('foo', 'A', 'bool', defaultArgListString: 'bar');
   }
 
-  test_ArgDefaults_method_with_required_named() async {
+  Future<void> test_ArgDefaults_method_with_required_named() async {
     addMetaPackage();
     addTestSource('''
 import 'package:meta/meta.dart';
@@ -112,7 +112,7 @@
         defaultArgListString: 'bar, baz: null');
   }
 
-  test_ArgumentList() async {
+  Future<void> test_ArgumentList() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -136,7 +136,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_imported_function() async {
+  Future<void> test_ArgumentList_imported_function() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -161,7 +161,8 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_InstanceCreationExpression_functionalArg() async {
+  Future<void>
+      test_ArgumentList_InstanceCreationExpression_functionalArg() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -188,7 +189,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_InstanceCreationExpression_typedefArg() async {
+  Future<void> test_ArgumentList_InstanceCreationExpression_typedefArg() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -216,7 +217,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_local_function() async {
+  Future<void> test_ArgumentList_local_function() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -241,7 +242,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_local_method() async {
+  Future<void> test_ArgumentList_local_method() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -266,7 +267,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_MethodInvocation_functionalArg() async {
+  Future<void> test_ArgumentList_MethodInvocation_functionalArg() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -293,7 +294,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_MethodInvocation_methodArg() async {
+  Future<void> test_ArgumentList_MethodInvocation_methodArg() async {
     // ArgumentList  MethodInvocation  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         library A;
@@ -318,7 +319,7 @@
     assertNotSuggested('print');
   }
 
-  test_ArgumentList_namedParam() async {
+  Future<void> test_ArgumentList_namedParam() async {
     // SimpleIdentifier  NamedExpression  ArgumentList  MethodInvocation
     // ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
@@ -336,7 +337,7 @@
     assertNotSuggested('main');
   }
 
-  test_AsExpression() async {
+  Future<void> test_AsExpression() async {
     // SimpleIdentifier  TypeName  AsExpression
     addTestSource('''
         class A {var b; X _c; foo() {var a; (a as ^).foo();}''');
@@ -350,7 +351,7 @@
     assertNotSuggested('==');
   }
 
-  test_AssignmentExpression_name() async {
+  Future<void> test_AssignmentExpression_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('class A {} main() {int a; int ^b = 1;}');
@@ -358,7 +359,7 @@
     assertNoSuggestions();
   }
 
-  test_AssignmentExpression_RHS() async {
+  Future<void> test_AssignmentExpression_RHS() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('class A {} main() {int a; int b = ^}');
@@ -371,7 +372,7 @@
     assertNotSuggested('Object');
   }
 
-  test_AssignmentExpression_type() async {
+  Future<void> test_AssignmentExpression_type() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -393,7 +394,7 @@
     //assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_newline() async {
+  Future<void> test_AssignmentExpression_type_newline() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -414,7 +415,7 @@
     assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_partial() async {
+  Future<void> test_AssignmentExpression_type_partial() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -436,7 +437,7 @@
     //assertNotSuggested('identical');
   }
 
-  test_AssignmentExpression_type_partial_newline() async {
+  Future<void> test_AssignmentExpression_type_partial_newline() async {
     // SimpleIdentifier  TypeName  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addTestSource('''
@@ -457,7 +458,7 @@
     assertNotSuggested('identical');
   }
 
-  test_AwaitExpression() async {
+  Future<void> test_AwaitExpression() async {
     // SimpleIdentifier  AwaitExpression  ExpressionStatement
     addTestSource('''
         class A {int x; int y() => 0;}
@@ -471,7 +472,7 @@
     assertNotSuggested('Object');
   }
 
-  test_BinaryExpression_LHS() async {
+  Future<void> test_BinaryExpression_LHS() async {
     // SimpleIdentifier  BinaryExpression  VariableDeclaration
     // VariableDeclarationList  VariableDeclarationStatement
     addTestSource('main() {int a = 1, b = ^ + 2;}');
@@ -483,7 +484,7 @@
     assertNotSuggested('b');
   }
 
-  test_BinaryExpression_RHS() async {
+  Future<void> test_BinaryExpression_RHS() async {
     // SimpleIdentifier  BinaryExpression  VariableDeclaration
     // VariableDeclarationList  VariableDeclarationStatement
     addTestSource('main() {int a = 1, b = 2 + ^;}');
@@ -496,7 +497,7 @@
     assertNotSuggested('==');
   }
 
-  test_Block() async {
+  Future<void> test_Block() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testAB.dart', '''
         export "dart:math" hide max;
@@ -588,7 +589,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final() async {
+  Future<void> test_Block_final() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testAB.dart', '''
         export "dart:math" hide max;
@@ -686,21 +687,21 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final2() async {
+  Future<void> test_Block_final2() async {
     addTestSource('main() {final S^ v;}');
     await computeSuggestions();
 
     assertNotSuggested('String');
   }
 
-  test_Block_final3() async {
+  Future<void> test_Block_final3() async {
     addTestSource('main() {final ^ v;}');
     await computeSuggestions();
 
     assertNotSuggested('String');
   }
 
-  test_Block_final_final() async {
+  Future<void> test_Block_final_final() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testAB.dart', '''
         export "dart:math" hide max;
@@ -798,7 +799,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_final_var() async {
+  Future<void> test_Block_final_var() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testAB.dart', '''
         export "dart:math" hide max;
@@ -896,7 +897,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_identifier_partial() async {
+  Future<void> test_Block_identifier_partial() async {
     addSource('/testAB.dart', '''
         export "dart:math" hide max;
         class A {int x;}
@@ -974,7 +975,7 @@
     assertNotSuggested('HtmlElement');
   }
 
-  test_Block_inherited_imported() async {
+  Future<void> test_Block_inherited_imported() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -1005,7 +1006,7 @@
     assertNotSuggested('==');
   }
 
-  test_Block_inherited_local() async {
+  Future<void> test_Block_inherited_local() async {
     // Block  BlockFunctionBody  MethodDeclaration  ClassDeclaration
     addTestSource('''
         class F { var f1; f2() { } get f3 => 0; set f4(fx) { } }
@@ -1028,7 +1029,7 @@
     assertNotSuggested('m2');
   }
 
-  test_Block_local_function() async {
+  Future<void> test_Block_local_function() async {
     addSource('/testAB.dart', '''
         export "dart:math" hide max;
         class A {int x;}
@@ -1077,7 +1078,7 @@
     assertNotSuggested('parseHex');
   }
 
-  test_Block_unimported() async {
+  Future<void> test_Block_unimported() async {
     addPackageFile('aaa', 'a.dart', 'class A {}');
     addTestSource('main() { ^ }');
 
@@ -1090,7 +1091,7 @@
     assertNotSuggested('Future');
   }
 
-  test_CascadeExpression_method1() async {
+  Future<void> test_CascadeExpression_method1() async {
     // PropertyAccess  CascadeExpression  ExpressionStatement  Block
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1114,7 +1115,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_selector1() async {
+  Future<void> test_CascadeExpression_selector1() async {
     // PropertyAccess  CascadeExpression  ExpressionStatement  Block
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1138,7 +1139,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_selector2() async {
+  Future<void> test_CascadeExpression_selector2() async {
     // SimpleIdentifier  PropertyAccess  CascadeExpression  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1160,7 +1161,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_selector2_withTrailingReturn() async {
+  Future<void> test_CascadeExpression_selector2_withTrailingReturn() async {
     // PropertyAccess  CascadeExpression  ExpressionStatement  Block
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1182,7 +1183,7 @@
     assertNotSuggested('==');
   }
 
-  test_CascadeExpression_target() async {
+  Future<void> test_CascadeExpression_target() async {
     // SimpleIdentifier  CascadeExpression  ExpressionStatement
     addTestSource('''
         class A {var b; X _c;}
@@ -1201,7 +1202,7 @@
     assertNotSuggested('==');
   }
 
-  test_CatchClause_onType() async {
+  Future<void> test_CatchClause_onType() async {
     // TypeName  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on ^ {}}}');
     await computeSuggestions();
@@ -1213,7 +1214,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_onType_noBrackets() async {
+  Future<void> test_CatchClause_onType_noBrackets() async {
     // TypeName  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on ^}}');
     await computeSuggestions();
@@ -1224,7 +1225,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_typed() async {
+  Future<void> test_CatchClause_typed() async {
     // Block  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} on E catch (e) {^}}}');
     await computeSuggestions();
@@ -1236,7 +1237,7 @@
     assertNotSuggested('x');
   }
 
-  test_CatchClause_untyped() async {
+  Future<void> test_CatchClause_untyped() async {
     // Block  CatchClause  TryStatement
     addTestSource('class A {a() {try{var x;} catch (e, s) {^}}}');
     await computeSuggestions();
@@ -1249,7 +1250,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body() async {
+  Future<void> test_ClassDeclaration_body() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1268,7 +1269,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final() async {
+  Future<void> test_ClassDeclaration_body_final() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1287,7 +1288,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_field() async {
+  Future<void> test_ClassDeclaration_body_final_field() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1306,7 +1307,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_field2() async {
+  Future<void> test_ClassDeclaration_body_final_field2() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1325,7 +1326,7 @@
     assertNotSuggested('Soo');
   }
 
-  test_ClassDeclaration_body_final_final() async {
+  Future<void> test_ClassDeclaration_body_final_final() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1344,7 +1345,7 @@
     assertNotSuggested('x');
   }
 
-  test_ClassDeclaration_body_final_var() async {
+  Future<void> test_ClassDeclaration_body_final_var() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/b.dart', '''
         class B { }''');
@@ -1363,7 +1364,7 @@
     assertNotSuggested('x');
   }
 
-  test_Combinator_hide() async {
+  Future<void> test_Combinator_hide() async {
     // SimpleIdentifier  HideCombinator  ImportDirective
     addSource('/testAB.dart', '''
         library libAB;
@@ -1386,7 +1387,7 @@
     assertNoSuggestions();
   }
 
-  test_Combinator_show() async {
+  Future<void> test_Combinator_show() async {
     // SimpleIdentifier  HideCombinator  ImportDirective
     addSource('/testAB.dart', '''
         library libAB;
@@ -1411,7 +1412,7 @@
     assertNoSuggestions();
   }
 
-  test_ConditionalExpression_elseExpression() async {
+  Future<void> test_ConditionalExpression_elseExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1430,7 +1431,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_ConditionalExpression_elseExpression_empty() async {
+  Future<void> test_ConditionalExpression_elseExpression_empty() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1455,7 +1456,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_ConditionalExpression_partial_thenExpression() async {
+  Future<void> test_ConditionalExpression_partial_thenExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1474,7 +1475,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_ConditionalExpression_partial_thenExpression_empty() async {
+  Future<void> test_ConditionalExpression_partial_thenExpression_empty() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1499,7 +1500,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_ConditionalExpression_thenExpression() async {
+  Future<void> test_ConditionalExpression_thenExpression() async {
     // SimpleIdentifier  ConditionalExpression  ReturnStatement
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1518,7 +1519,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_ConstructorName_importedClass() async {
+  Future<void> test_ConstructorName_importedClass() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -1542,7 +1543,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedFactory() async {
+  Future<void> test_ConstructorName_importedFactory() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addSource('/home/test/lib/b.dart', '''
@@ -1566,7 +1567,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_importedFactory2() async {
+  Future<void> test_ConstructorName_importedFactory2() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -1583,7 +1584,7 @@
     assertNotSuggested('String');
   }
 
-  test_ConstructorName_localClass() async {
+  Future<void> test_ConstructorName_localClass() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -1603,7 +1604,7 @@
     assertNotSuggested('m');
   }
 
-  test_ConstructorName_localFactory() async {
+  Future<void> test_ConstructorName_localFactory() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName  ConstructorName
     // InstanceCreationExpression
     addTestSource('''
@@ -1623,7 +1624,7 @@
     assertNotSuggested('m');
   }
 
-  test_DefaultFormalParameter_named_expression() async {
+  Future<void> test_DefaultFormalParameter_named_expression() async {
     // DefaultFormalParameter FormalParameterList MethodDeclaration
     addTestSource('''
         foo() { }
@@ -1640,7 +1641,7 @@
     assertNotSuggested('bar');
   }
 
-  test_enumConst() async {
+  Future<void> test_enumConst() async {
     addTestSource('enum E { one, two } main() {E.^}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -1651,7 +1652,7 @@
     assertNotSuggested('values');
   }
 
-  test_enumConst2() async {
+  Future<void> test_enumConst2() async {
     addTestSource('enum E { one, two } main() {E.o^}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -1662,7 +1663,7 @@
     assertNotSuggested('values');
   }
 
-  test_enumConst3() async {
+  Future<void> test_enumConst3() async {
     addTestSource('enum E { one, two } main() {E.^ int g;}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -1673,7 +1674,7 @@
     assertNotSuggested('values');
   }
 
-  test_enumConst_index() async {
+  Future<void> test_enumConst_index() async {
     addTestSource('enum E { one, two } main() {E.one.^}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -1683,7 +1684,7 @@
     assertNotSuggested('values');
   }
 
-  test_enumConst_index2() async {
+  Future<void> test_enumConst_index2() async {
     addTestSource('enum E { one, two } main() {E.one.i^}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -1693,7 +1694,7 @@
     assertNotSuggested('values');
   }
 
-  test_enumConst_index3() async {
+  Future<void> test_enumConst_index3() async {
     addTestSource('enum E { one, two } main() {E.one.^ int g;}');
     await computeSuggestions();
     assertNotSuggested('E');
@@ -1703,7 +1704,7 @@
     assertNotSuggested('values');
   }
 
-  test_ExpressionStatement_identifier() async {
+  Future<void> test_ExpressionStatement_identifier() async {
     // SimpleIdentifier  ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         _B F1() { }
@@ -1729,7 +1730,7 @@
     assertNotSuggested('_B');
   }
 
-  test_ExpressionStatement_name() async {
+  Future<void> test_ExpressionStatement_name() async {
     // ExpressionStatement  Block  BlockFunctionBody  MethodDeclaration
     addSource('/home/test/lib/a.dart', '''
         B T1;
@@ -1741,7 +1742,7 @@
     assertNoSuggestions();
   }
 
-  test_FieldDeclaration_name_typed() async {
+  Future<void> test_FieldDeclaration_name_typed() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // FieldDeclaration
     addSource('/home/test/lib/a.dart', 'class A { }');
@@ -1752,7 +1753,7 @@
     assertNoSuggestions();
   }
 
-  test_FieldDeclaration_name_var() async {
+  Future<void> test_FieldDeclaration_name_var() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // FieldDeclaration
     addSource('/home/test/lib/a.dart', 'class A { }');
@@ -1763,7 +1764,7 @@
     assertNoSuggestions();
   }
 
-  test_FieldFormalParameter_in_non_constructor() async {
+  Future<void> test_FieldFormalParameter_in_non_constructor() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('class A {B(this.^foo) {}}');
     await computeSuggestions();
@@ -1772,7 +1773,7 @@
     assertNoSuggestions();
   }
 
-  test_ForEachStatement_body_typed() async {
+  Future<void> test_ForEachStatement_body_typed() async {
     // Block  ForEachStatement
     addTestSource('main(args) {for (int foo in bar) {^}}');
     await computeSuggestions();
@@ -1783,7 +1784,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForEachStatement_body_untyped() async {
+  Future<void> test_ForEachStatement_body_untyped() async {
     // Block  ForEachStatement
     addTestSource('main(args) {for (foo in bar) {^}}');
     await computeSuggestions();
@@ -1794,7 +1795,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForEachStatement_iterable() async {
+  Future<void> test_ForEachStatement_iterable() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (int foo in ^) {}}');
     await computeSuggestions();
@@ -1804,7 +1805,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForEachStatement_loopVariable() async {
+  Future<void> test_ForEachStatement_loopVariable() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (^ in args) {}}');
     await computeSuggestions();
@@ -1814,7 +1815,7 @@
     assertNotSuggested('String');
   }
 
-  test_ForEachStatement_loopVariable_type() async {
+  Future<void> test_ForEachStatement_loopVariable_type() async {
     // SimpleIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (^ foo in args) {}}');
     await computeSuggestions();
@@ -1825,7 +1826,7 @@
     assertNotSuggested('String');
   }
 
-  test_ForEachStatement_loopVariable_type2() async {
+  Future<void> test_ForEachStatement_loopVariable_type2() async {
     // DeclaredIdentifier  ForEachStatement  Block
     addTestSource('main(args) {for (S^ foo in args) {}}');
     await computeSuggestions();
@@ -1836,7 +1837,7 @@
     assertNotSuggested('String');
   }
 
-  test_FormalParameterList() async {
+  Future<void> test_FormalParameterList() async {
     // FormalParameterList MethodDeclaration
     addTestSource('''
         foo() { }
@@ -1853,7 +1854,7 @@
     assertNotSuggested('bar');
   }
 
-  test_ForStatement_body() async {
+  Future<void> test_ForStatement_body() async {
     // Block  ForStatement
     addTestSource('main(args) {for (int i; i < 10; ++i) {^}}');
     await computeSuggestions();
@@ -1863,7 +1864,7 @@
     assertNotSuggested('Object');
   }
 
-  test_ForStatement_condition() async {
+  Future<void> test_ForStatement_condition() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {for (int index = 0; i^)}');
     await computeSuggestions();
@@ -1872,7 +1873,7 @@
     assertNotSuggested('index');
   }
 
-  test_ForStatement_initializer() async {
+  Future<void> test_ForStatement_initializer() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {List a; for (^)}');
     await computeSuggestions();
@@ -1883,7 +1884,7 @@
     assertNotSuggested('int');
   }
 
-  test_ForStatement_updaters() async {
+  Future<void> test_ForStatement_updaters() async {
     // SimpleIdentifier  ForStatement
     addTestSource('main() {for (int index = 0; index < 10; i^)}');
     await computeSuggestions();
@@ -1892,7 +1893,7 @@
     assertNotSuggested('index');
   }
 
-  test_ForStatement_updaters_prefix_expression() async {
+  Future<void> test_ForStatement_updaters_prefix_expression() async {
     // SimpleIdentifier  PrefixExpression  ForStatement
     addTestSource('''
         void bar() { }
@@ -1905,7 +1906,7 @@
     assertNotSuggested('bar');
   }
 
-  test_FunctionDeclaration_returnType_afterComment() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1934,7 +1935,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionDeclaration_returnType_afterComment2() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment2() async {
     // FunctionDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1963,7 +1964,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionDeclaration_returnType_afterComment3() async {
+  Future<void> test_FunctionDeclaration_returnType_afterComment3() async {
     // FunctionDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -1993,7 +1994,7 @@
     assertNotSuggested('name');
   }
 
-  test_FunctionExpression_body_function() async {
+  Future<void> test_FunctionExpression_body_function() async {
     // Block  BlockFunctionBody  FunctionExpression
     addTestSource('''
         void bar() { }
@@ -2009,7 +2010,24 @@
     assertNotSuggested('Object');
   }
 
-  test_generic_field() async {
+  Future<void> test_FunctionType_call() async {
+    addTestSource('''
+void f() {
+  void Function(int x) fun;
+  fun.^
+}
+''');
+
+    await computeSuggestions();
+    assertSuggest(
+      'call()',
+      selectionOffset: 6,
+      elemKind: ElementKind.METHOD,
+      isSynthetic: true,
+    );
+  }
+
+  Future<void> test_generic_field() async {
     addTestSource('''
 class C<T> {
   T t;
@@ -2022,7 +2040,7 @@
     assertSuggestField('t', 'int');
   }
 
-  test_generic_getter() async {
+  Future<void> test_generic_getter() async {
     addTestSource('''
 class C<T> {
   T get t => null;
@@ -2035,7 +2053,7 @@
     assertSuggestGetter('t', 'int');
   }
 
-  test_generic_method() async {
+  Future<void> test_generic_method() async {
     addTestSource('''
 class C<T> {
   T m(T t) {}
@@ -2051,7 +2069,7 @@
     expect(suggestion.element.parameters, '(int t)');
   }
 
-  test_generic_setter() async {
+  Future<void> test_generic_setter() async {
     addTestSource('''
 class C<T> {
   set t(T value) {}
@@ -2068,7 +2086,7 @@
     expect(suggestion.element.parameters, '(int value)');
   }
 
-  test_genericTypeAlias_noFunctionType() async {
+  Future<void> test_genericTypeAlias_noFunctionType() async {
     addTestSource('''
 typedef F=;
 g(F.^
@@ -2076,7 +2094,7 @@
     await computeSuggestions();
   }
 
-  test_IfStatement() async {
+  Future<void> test_IfStatement() async {
     // SimpleIdentifier  IfStatement
     addTestSource('''
         class A {var b; X _c; foo() {A a; if (true) ^}}''');
@@ -2090,7 +2108,7 @@
     assertNotSuggested('==');
   }
 
-  test_IfStatement_condition() async {
+  Future<void> test_IfStatement_condition() async {
     // SimpleIdentifier  IfStatement  Block  BlockFunctionBody
     addTestSource('''
         class A {int x; int y() => 0;}
@@ -2104,7 +2122,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IfStatement_empty() async {
+  Future<void> test_IfStatement_empty() async {
     // SimpleIdentifier  IfStatement
     addTestSource('''
         class A {var b; X _c; foo() {A a; if (^) something}}''');
@@ -2118,7 +2136,7 @@
     assertNotSuggested('==');
   }
 
-  test_IfStatement_invocation() async {
+  Future<void> test_IfStatement_invocation() async {
     // SimpleIdentifier  PrefixIdentifier  IfStatement
     addTestSource('''
         main() {var a; if (a.^) something}''');
@@ -2131,7 +2149,7 @@
     assertNotSuggested('==');
   }
 
-  test_ImportDirective_dart() async {
+  Future<void> test_ImportDirective_dart() async {
     // SimpleStringLiteral  ImportDirective
     addTestSource('''
         import "dart^";
@@ -2140,7 +2158,7 @@
     assertNoSuggestions();
   }
 
-  test_IndexExpression() async {
+  Future<void> test_IndexExpression() async {
     // ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2165,7 +2183,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_IndexExpression2() async {
+  Future<void> test_IndexExpression2() async {
     // SimpleIdentifier IndexExpression ExpressionStatement  Block
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2184,7 +2202,7 @@
     //assertSuggestImportedTopLevelVar('T1', 'int');
   }
 
-  test_InstanceCreationExpression_imported() async {
+  Future<void> test_InstanceCreationExpression_imported() async {
     // SimpleIdentifier  TypeName  ConstructorName  InstanceCreationExpression
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2214,7 +2232,7 @@
     assertNotSuggested('T2');
   }
 
-  test_InstanceCreationExpression_unimported() async {
+  Future<void> test_InstanceCreationExpression_unimported() async {
     // SimpleIdentifier  TypeName  ConstructorName  InstanceCreationExpression
     addSource('/testAB.dart', 'class Foo { }');
     addTestSource('class C {foo(){new F^}}');
@@ -2225,7 +2243,7 @@
     assertNotSuggested('Foo');
   }
 
-  test_InterfaceType_Function_call() async {
+  Future<void> test_InterfaceType_Function_call() async {
     addTestSource('''
 void f() {
   Function fun;
@@ -2242,7 +2260,7 @@
     );
   }
 
-  test_InterfaceType_Function_extended_call() async {
+  Future<void> test_InterfaceType_Function_extended_call() async {
     addTestSource('''
 class MyFun extends Function { }
 void f() {
@@ -2260,7 +2278,7 @@
     );
   }
 
-  test_InterfaceType_Function_implemented_call() async {
+  Future<void> test_InterfaceType_Function_implemented_call() async {
     addTestSource('''
 class MyFun implements Function { }
 void f() {
@@ -2278,7 +2296,7 @@
     );
   }
 
-  test_InterpolationExpression() async {
+  Future<void> test_InterpolationExpression() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2307,7 +2325,7 @@
     assertNotSuggested('name');
   }
 
-  test_InterpolationExpression_block() async {
+  Future<void> test_InterpolationExpression_block() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2335,7 +2353,7 @@
     assertNotSuggested('name');
   }
 
-  test_InterpolationExpression_block2() async {
+  Future<void> test_InterpolationExpression_block2() async {
     // SimpleIdentifier  InterpolationExpression  StringInterpolation
     addTestSource('main() {String name; print("hello \${n^}");}');
     await computeSuggestions();
@@ -2344,7 +2362,7 @@
     //assertNotSuggested('Object');
   }
 
-  test_InterpolationExpression_prefix_selector() async {
+  Future<void> test_InterpolationExpression_prefix_selector() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \${name.^}");}');
     await computeSuggestions();
@@ -2356,14 +2374,14 @@
     assertNotSuggested('==');
   }
 
-  test_InterpolationExpression_prefix_selector2() async {
+  Future<void> test_InterpolationExpression_prefix_selector2() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \$name.^");}');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_InterpolationExpression_prefix_target() async {
+  Future<void> test_InterpolationExpression_prefix_target() async {
     // SimpleIdentifier  PrefixedIdentifier  InterpolationExpression
     addTestSource('main() {String name; print("hello \${nam^e.length}");}');
     await computeSuggestions();
@@ -2373,7 +2391,7 @@
     assertNotSuggested('length');
   }
 
-  test_IsExpression() async {
+  Future<void> test_IsExpression() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -2393,7 +2411,7 @@
     assertNotSuggested('foo');
   }
 
-  test_IsExpression_target() async {
+  Future<void> test_IsExpression_target() async {
     // IfStatement  Block  BlockFunctionBody
     addTestSource('''
         foo() { }
@@ -2411,7 +2429,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IsExpression_type() async {
+  Future<void> test_IsExpression_type() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addTestSource('''
         class A {int x; int y() => 0;}
@@ -2425,7 +2443,7 @@
     assertNotSuggested('Object');
   }
 
-  test_IsExpression_type_partial() async {
+  Future<void> test_IsExpression_type_partial() async {
     // SimpleIdentifier  TypeName  IsExpression  IfStatement
     addTestSource('''
         class A {int x; int y() => 0;}
@@ -2439,14 +2457,14 @@
     assertNotSuggested('Object');
   }
 
-  test_keyword() async {
+  Future<void> test_keyword() async {
     addTestSource('class C { static C get instance => null; } main() {C.in^}');
     await computeSuggestions();
     // Suggested by StaticMemberContributor
     assertNotSuggested('instance');
   }
 
-  test_keyword2() async {
+  Future<void> test_keyword2() async {
     addSource('/home/test/lib/b.dart', '''
         lib B;
         int newT1;
@@ -2471,7 +2489,7 @@
     assertNotSuggested('newer');
   }
 
-  test_libraryPrefix() async {
+  Future<void> test_libraryPrefix() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('import "dart:async" as bar; foo() {bar.^}');
     await computeSuggestions();
@@ -2480,7 +2498,7 @@
     assertNotSuggested('loadLibrary');
   }
 
-  test_libraryPrefix2() async {
+  Future<void> test_libraryPrefix2() async {
     // SimpleIdentifier  MethodInvocation  ExpressionStatement
     addTestSource('import "dart:async" as bar; foo() {bar.^ print("f")}');
     await computeSuggestions();
@@ -2488,7 +2506,7 @@
     assertNotSuggested('Future');
   }
 
-  test_libraryPrefix3() async {
+  Future<void> test_libraryPrefix3() async {
     // SimpleIdentifier  MethodInvocation  ExpressionStatement
     addTestSource('import "dart:async" as bar; foo() {new bar.F^ print("f")}');
     await computeSuggestions();
@@ -2497,7 +2515,7 @@
     assertNotSuggested('Future.delayed');
   }
 
-  test_libraryPrefix_deferred() async {
+  Future<void> test_libraryPrefix_deferred() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('import "dart:async" deferred as bar; foo() {bar.^}');
     await computeSuggestions();
@@ -2506,7 +2524,7 @@
     assertNotSuggested('loadLibrary');
   }
 
-  test_libraryPrefix_with_exports() async {
+  Future<void> test_libraryPrefix_with_exports() async {
     addSource('/home/test/lib/a.dart', 'class A { }');
     addSource('/home/test/lib/b.dart', 'export "a.dart"; class B { }');
     addTestSource('import "b.dart" as foo; main() {foo.^} class C { }');
@@ -2516,7 +2534,7 @@
     assertNotSuggested('A');
   }
 
-  test_Literal_list() async {
+  Future<void> test_Literal_list() async {
     // ']'  ListLiteral  ArgumentList  MethodInvocation
     addTestSource('main() {var Some; print([^]);}');
     await computeSuggestions();
@@ -2524,7 +2542,7 @@
     assertNotSuggested('String');
   }
 
-  test_Literal_list2() async {
+  Future<void> test_Literal_list2() async {
     // SimpleIdentifier ListLiteral  ArgumentList  MethodInvocation
     addTestSource('main() {var Some; print([S^]);}');
     await computeSuggestions();
@@ -2532,39 +2550,39 @@
     assertNotSuggested('String');
   }
 
-  test_Literal_string() async {
+  Future<void> test_Literal_string() async {
     // SimpleStringLiteral  ExpressionStatement  Block
     addTestSource('class A {a() {"hel^lo"}}');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_local() async {
+  Future<void> test_local() async {
     addTestSource('foo() {String x = "bar"; x.^}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_local_is() async {
+  Future<void> test_local_is() async {
     addTestSource('foo() {var x; if (x is String) x.^}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_local_propogatedType() async {
+  Future<void> test_local_propogatedType() async {
     addTestSource('foo() {var x = "bar"; x.^}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_localVariableDeclarationName() async {
+  Future<void> test_localVariableDeclarationName() async {
     addTestSource('main() {String m^}');
     await computeSuggestions();
     assertNotSuggested('main');
     assertNotSuggested('min');
   }
 
-  test_MapLiteralEntry() async {
+  Future<void> test_MapLiteralEntry() async {
     // MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2591,7 +2609,7 @@
     assertNotSuggested('C2');
   }
 
-  test_MapLiteralEntry1() async {
+  Future<void> test_MapLiteralEntry1() async {
     // MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2611,7 +2629,7 @@
     assertNotSuggested('T2');
   }
 
-  test_MapLiteralEntry2() async {
+  Future<void> test_MapLiteralEntry2() async {
     // SimpleIdentifier  MapLiteralEntry  MapLiteral  VariableDeclaration
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2631,7 +2649,7 @@
     assertNotSuggested('T2');
   }
 
-  test_method_parameter_function_in_param_list() async {
+  Future<void> test_method_parameter_function_in_param_list() async {
     addTestSource('''
 class C {
   void f(int x, void Function(int a, int b) closure, int y) {}
@@ -2651,7 +2669,7 @@
         containsAllInOrder([0, 1, 11, 1, 15, 1]));
   }
 
-  test_method_parameter_function_return_bool() async {
+  Future<void> test_method_parameter_function_return_bool() async {
     addTestSource('''
 class C {
   void f(bool Function(int a, int b) closure) {}
@@ -2671,7 +2689,7 @@
         suggestion.defaultArgumentListTextRanges, containsAllInOrder([10, 5]));
   }
 
-  test_method_parameter_function_return_object() async {
+  Future<void> test_method_parameter_function_return_object() async {
     addTestSource('''
 class C {
   void f(Object Function(int a, int b) closure) {}
@@ -2691,7 +2709,7 @@
         suggestion.defaultArgumentListTextRanges, containsAllInOrder([10, 4]));
   }
 
-  test_method_parameter_function_return_void() async {
+  Future<void> test_method_parameter_function_return_void() async {
     addTestSource('''
 class C {
   void f(void Function(int a, int b) closure) {}
@@ -2711,7 +2729,7 @@
         suggestion.defaultArgumentListTextRanges, containsAllInOrder([8, 1]));
   }
 
-  test_method_parameters_mixed_required_and_named() async {
+  Future<void> test_method_parameters_mixed_required_and_named() async {
     addTestSource('''
 class C {
   void m(x, {int y}) {}
@@ -2728,7 +2746,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_method_parameters_mixed_required_and_positional() async {
+  Future<void> test_method_parameters_mixed_required_and_positional() async {
     addTestSource('''
 class C {
   void m(x, [int y]) {}
@@ -2745,7 +2763,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_named() async {
+  Future<void> test_method_parameters_named() async {
     addTestSource('''
 class C {
   void m({x, int y}) {}
@@ -2762,7 +2780,7 @@
     expect(suggestion.hasNamedParameters, true);
   }
 
-  test_method_parameters_none() async {
+  Future<void> test_method_parameters_none() async {
     addTestSource('''
 class C {
   void m() {}
@@ -2776,7 +2794,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_positional() async {
+  Future<void> test_method_parameters_positional() async {
     addTestSource('''
 class C {
   void m([x, int y]) {}
@@ -2793,7 +2811,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_method_parameters_required() async {
+  Future<void> test_method_parameters_required() async {
     addTestSource('''
 class C {
   void m(x, int y) {}
@@ -2810,7 +2828,7 @@
     expect(suggestion.hasNamedParameters, false);
   }
 
-  test_MethodDeclaration_body_getters() async {
+  Future<void> test_MethodDeclaration_body_getters() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated X get f => 0; Z a() {^} get _g => 1;}');
     await computeSuggestions();
@@ -2821,7 +2839,7 @@
     assertNotSuggested('_g');
   }
 
-  test_MethodDeclaration_body_static() async {
+  Future<void> test_MethodDeclaration_body_static() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addSource('/testC.dart', '''
         class C {
@@ -2857,7 +2875,7 @@
     assertNotSuggested('c4');
   }
 
-  test_MethodDeclaration_members() async {
+  Future<void> test_MethodDeclaration_members() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated X f; Z _a() {^} var _g;}');
     await computeSuggestions();
@@ -2869,7 +2887,7 @@
     assertNotSuggested('bool');
   }
 
-  test_MethodDeclaration_parameters_named() async {
+  Future<void> test_MethodDeclaration_parameters_named() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {@deprecated Z a(X x, _, b, {y: boo}) {^}}');
     await computeSuggestions();
@@ -2883,7 +2901,7 @@
     assertNotSuggested('_');
   }
 
-  test_MethodDeclaration_parameters_positional() async {
+  Future<void> test_MethodDeclaration_parameters_positional() async {
     // Block  BlockFunctionBody  MethodDeclaration
     addTestSource('''
         foo() { }
@@ -2900,7 +2918,7 @@
     assertNotSuggested('String');
   }
 
-  test_MethodDeclaration_returnType() async {
+  Future<void> test_MethodDeclaration_returnType() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2928,7 +2946,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment() async {
     // ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2956,7 +2974,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment2() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment2() async {
     // MethodDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -2984,7 +3002,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodDeclaration_returnType_afterComment3() async {
+  Future<void> test_MethodDeclaration_returnType_afterComment3() async {
     // MethodDeclaration  ClassDeclaration  CompilationUnit
     addSource('/home/test/lib/a.dart', '''
         int T1;
@@ -3014,7 +3032,7 @@
     assertNotSuggested('name');
   }
 
-  test_MethodInvocation_no_semicolon() async {
+  Future<void> test_MethodInvocation_no_semicolon() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource(r'''
         main() { }
@@ -3048,7 +3066,7 @@
     assertNotSuggested('==');
   }
 
-  test_mixin() async {
+  Future<void> test_mixin() async {
     addTestSource(r'''
 class A {
   void a() {}
@@ -3072,7 +3090,7 @@
     assertSuggestMethod('x', 'X', 'void');
   }
 
-  test_new_instance() async {
+  Future<void> test_new_instance() async {
     addTestSource('import "dart:math"; class A {x() {new Random().^}}');
     await computeSuggestions();
     assertSuggestMethod('nextBool', 'Random', 'bool');
@@ -3083,7 +3101,7 @@
     assertNotSuggested('A');
   }
 
-  test_no_parameters_field() async {
+  Future<void> test_no_parameters_field() async {
     addTestSource('''
 class C {
   int x;
@@ -3094,7 +3112,7 @@
     assertHasNoParameterInfo(suggestion);
   }
 
-  test_no_parameters_getter() async {
+  Future<void> test_no_parameters_getter() async {
     addTestSource('''
 class C {
   int get x => null;
@@ -3105,7 +3123,7 @@
     assertHasNoParameterInfo(suggestion);
   }
 
-  test_no_parameters_setter() async {
+  Future<void> test_no_parameters_setter() async {
     addTestSource('''
 class C {
   set x(int value) {};
@@ -3116,7 +3134,7 @@
     assertHasNoParameterInfo(suggestion);
   }
 
-  test_only_instance() async {
+  Future<void> test_only_instance() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement
     addTestSource('''
 class C {
@@ -3133,7 +3151,7 @@
     assertNotSuggested('m2');
   }
 
-  test_only_instance2() async {
+  Future<void> test_only_instance2() async {
     // SimpleIdentifier  MethodInvocation  ExpressionStatement
     addTestSource('''
 class C {
@@ -3150,7 +3168,7 @@
     assertNotSuggested('m2');
   }
 
-  test_only_static() async {
+  Future<void> test_only_static() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
 class C {
@@ -3168,7 +3186,7 @@
     assertNotSuggested('m2');
   }
 
-  test_only_static2() async {
+  Future<void> test_only_static2() async {
     // SimpleIdentifier  MethodInvocation  ExpressionStatement
     addTestSource('''
 class C {
@@ -3186,26 +3204,26 @@
     assertNotSuggested('m2');
   }
 
-  test_param() async {
+  Future<void> test_param() async {
     addTestSource('foo(String x) {x.^}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_param_is() async {
+  Future<void> test_param_is() async {
     addTestSource('foo(x) {if (x is String) x.^}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_parameterName_excludeTypes() async {
+  Future<void> test_parameterName_excludeTypes() async {
     addTestSource('m(int ^) {}');
     await computeSuggestions();
     assertNotSuggested('int');
     assertNotSuggested('bool');
   }
 
-  test_partFile_TypeName() async {
+  Future<void> test_partFile_TypeName() async {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3237,7 +3255,7 @@
     assertNotSuggested('m');
   }
 
-  test_partFile_TypeName2() async {
+  Future<void> test_partFile_TypeName2() async {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3269,7 +3287,7 @@
     assertNotSuggested('m');
   }
 
-  test_PrefixedIdentifier_class_const() async {
+  Future<void> test_PrefixedIdentifier_class_const() async {
     // SimpleIdentifier PrefixedIdentifier ExpressionStatement Block
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3315,7 +3333,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_class_imported() async {
+  Future<void> test_PrefixedIdentifier_class_imported() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3351,7 +3369,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_class_local() async {
+  Future<void> test_PrefixedIdentifier_class_local() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('''
         main() {A a; a.^}
@@ -3384,14 +3402,14 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_getter() async {
+  Future<void> test_PrefixedIdentifier_getter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String get g => "one"; f() {g.^}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_library() async {
+  Future<void> test_PrefixedIdentifier_library() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3417,7 +3435,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_typesOnly() async {
+  Future<void> test_PrefixedIdentifier_library_typesOnly() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3443,7 +3461,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_library_typesOnly2() async {
+  Future<void> test_PrefixedIdentifier_library_typesOnly2() async {
     // SimpleIdentifier  PrefixedIdentifier  TypeName
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3469,7 +3487,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_parameter() async {
+  Future<void> test_PrefixedIdentifier_parameter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/b.dart', '''
         lib B;
@@ -3487,7 +3505,7 @@
     assertNotSuggested('==');
   }
 
-  test_PrefixedIdentifier_prefix() async {
+  Future<void> test_PrefixedIdentifier_prefix() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
         class A {static int bar = 10;}
@@ -3505,7 +3523,7 @@
     assertNotSuggested('_B');
   }
 
-  test_PrefixedIdentifier_propertyAccess() async {
+  Future<void> test_PrefixedIdentifier_propertyAccess() async {
     // PrefixedIdentifier  ExpressionStatement  Block  BlockFunctionBody
     addTestSource('class A {String x; int get foo {x.^}');
     await computeSuggestions();
@@ -3515,7 +3533,7 @@
     assertSuggestMethod('compareTo', 'Comparable', 'int');
   }
 
-  test_PrefixedIdentifier_propertyAccess_newStmt() async {
+  Future<void> test_PrefixedIdentifier_propertyAccess_newStmt() async {
     // PrefixedIdentifier  ExpressionStatement  Block  BlockFunctionBody
     addTestSource('class A {String x; int get foo {x.^ int y = 0;}');
     await computeSuggestions();
@@ -3525,14 +3543,14 @@
     assertSuggestMethod('compareTo', 'Comparable', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_const() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_const() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('const String g = "hello"; f() {g.^ int y = 0;}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_const_untyped() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_const_untyped() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('const g = "hello"; f() {g.^ int y = 0;}');
     await computeSuggestions();
@@ -3540,77 +3558,77 @@
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_field() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_field() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {String g; f() {g.^ int y = 0;}}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_function() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_function() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String g() => "one"; f() {g.^ int y = 0;}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_functionTypeAlias() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_functionTypeAlias() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('typedef String g(); f() {g.^ int y = 0;}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_getter() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_getter() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String get g => "one"; f() {g.^ int y = 0;}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_local_typed() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_local_typed() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f() {String g; g.^ int y = 0;}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_local_untyped() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_local_untyped() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f() {var g = "hello"; g.^ int y = 0;}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_method() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_method() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {String g() {}; f() {g.^ int y = 0;}}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_param() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_param() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('class A {f(String g) {g.^ int y = 0;}}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_param2() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_param2() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('f(String g) {g.^ int y = 0;}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PrefixedIdentifier_trailingStmt_topLevelVar() async {
+  Future<void> test_PrefixedIdentifier_trailingStmt_topLevelVar() async {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('String g; f() {g.^ int y = 0;}');
     await computeSuggestions();
     assertSuggestGetter('length', 'int');
   }
 
-  test_PropertyAccess_expression() async {
+  Future<void> test_PropertyAccess_expression() async {
     // SimpleIdentifier  MethodInvocation  PropertyAccess  ExpressionStatement
     addTestSource('class A {a() {"hello".to^String().length}}');
     await computeSuggestions();
@@ -3623,7 +3641,7 @@
     assertNotSuggested('==');
   }
 
-  test_PropertyAccess_noTarget() async {
+  Future<void> test_PropertyAccess_noTarget() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement
     addSource('/testAB.dart', 'class Foo { }');
     addTestSource('class C {foo(){.^}}');
@@ -3631,7 +3649,7 @@
     assertNoSuggestions();
   }
 
-  test_PropertyAccess_noTarget2() async {
+  Future<void> test_PropertyAccess_noTarget2() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement
     addSource('/testAB.dart', 'class Foo { }');
     addTestSource('main() {.^}');
@@ -3639,7 +3657,7 @@
     assertNoSuggestions();
   }
 
-  test_PropertyAccess_selector() async {
+  Future<void> test_PropertyAccess_selector() async {
     // SimpleIdentifier  PropertyAccess  ExpressionStatement  Block
     addTestSource('class A {a() {"hello".length.^}}');
     await computeSuggestions();
@@ -3652,43 +3670,43 @@
     assertNotSuggested('==');
   }
 
-  test_shadowing_field_over_field() =>
+  Future<void> test_shadowing_field_over_field() =>
       check_shadowing('int x;', 'int x;', true);
 
-  test_shadowing_field_over_getter() =>
+  Future<void> test_shadowing_field_over_getter() =>
       check_shadowing('int x;', 'int get x => null;', true);
 
-  test_shadowing_field_over_method() =>
+  Future<void> test_shadowing_field_over_method() =>
       check_shadowing('int x;', 'void x() {}', true);
 
-  test_shadowing_field_over_setter() =>
+  Future<void> test_shadowing_field_over_setter() =>
       check_shadowing('int x;', 'set x(int value) {}', true);
 
-  test_shadowing_getter_over_field() =>
+  Future<void> test_shadowing_getter_over_field() =>
       check_shadowing('int get x => null;', 'int x;', false);
 
-  test_shadowing_getter_over_getter() =>
+  Future<void> test_shadowing_getter_over_getter() =>
       check_shadowing('int get x => null;', 'int get x => null;', true);
 
-  test_shadowing_getter_over_method() =>
+  Future<void> test_shadowing_getter_over_method() =>
       check_shadowing('int get x => null;', 'void x() {}', true);
 
-  test_shadowing_getter_over_setter() =>
+  Future<void> test_shadowing_getter_over_setter() =>
       check_shadowing('int get x => null;', 'set x(int value) {}', false);
 
-  test_shadowing_method_over_field() =>
+  Future<void> test_shadowing_method_over_field() =>
       check_shadowing('void x() {}', 'int x;', true);
 
-  test_shadowing_method_over_getter() =>
+  Future<void> test_shadowing_method_over_getter() =>
       check_shadowing('void x() {}', 'int get x => null;', true);
 
-  test_shadowing_method_over_method() =>
+  Future<void> test_shadowing_method_over_method() =>
       check_shadowing('void x() {}', 'void x() {}', true);
 
-  test_shadowing_method_over_setter() =>
+  Future<void> test_shadowing_method_over_setter() =>
       check_shadowing('void x() {}', 'set x(int value) {}', true);
 
-  test_shadowing_mixin_order() async {
+  Future<void> test_shadowing_mixin_order() async {
     addTestSource('''
 class Base {
 }
@@ -3713,7 +3731,7 @@
     assertSuggestMethod('f', 'Mixin2', 'void');
   }
 
-  test_shadowing_mixin_over_superclass() async {
+  Future<void> test_shadowing_mixin_over_superclass() async {
     addTestSource('''
 class Base {
   void f() {}
@@ -3731,19 +3749,19 @@
     assertSuggestMethod('f', 'Mixin', 'void');
   }
 
-  test_shadowing_setter_over_field() =>
+  Future<void> test_shadowing_setter_over_field() =>
       check_shadowing('set x(int value) {}', 'int x;', false);
 
-  test_shadowing_setter_over_getter() =>
+  Future<void> test_shadowing_setter_over_getter() =>
       check_shadowing('set x(int value) {}', 'int get x => null;', false);
 
-  test_shadowing_setter_over_method() =>
+  Future<void> test_shadowing_setter_over_method() =>
       check_shadowing('set x(int value) {}', 'void x() {}', true);
 
-  test_shadowing_setter_over_setter() =>
+  Future<void> test_shadowing_setter_over_setter() =>
       check_shadowing('set x(int value) {}', 'set x(int value) {}', true);
 
-  test_shadowing_superclass_over_interface() async {
+  Future<void> test_shadowing_superclass_over_interface() async {
     addTestSource('''
 class Base {
   void f() {}
@@ -3761,7 +3779,7 @@
     assertSuggestMethod('f', 'Base', 'void');
   }
 
-  test_super() async {
+  Future<void> test_super() async {
     // SimpleIdentifier  MethodInvocation  ExpressionStatement
     addTestSource('''
 class C3 {
@@ -3801,7 +3819,7 @@
     assertNotSuggested('ms3');
   }
 
-  test_super_fromSuperclassConstraint() async {
+  Future<void> test_super_fromSuperclassConstraint() async {
     addTestSource('''
 class C {
   void c(x, int y) {}
@@ -3814,7 +3832,7 @@
     assertSuggestMethod('c', 'C', 'void');
   }
 
-  test_super_withMixin() async {
+  Future<void> test_super_withMixin() async {
     addTestSource('''
 mixin M {
   void m() {}
@@ -3831,14 +3849,14 @@
     assertSuggestMethod('m', 'M', 'void');
   }
 
-  test_SwitchStatement_c() async {
+  Future<void> test_SwitchStatement_c() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {switch(x) {c^}}}');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_SwitchStatement_case() async {
+  Future<void> test_SwitchStatement_case() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {var t; switch(x) {case 0: ^}}}');
     await computeSuggestions();
@@ -3848,14 +3866,14 @@
     assertNotSuggested('String');
   }
 
-  test_SwitchStatement_empty() async {
+  Future<void> test_SwitchStatement_empty() async {
     // SwitchStatement  Block  BlockFunctionBody  MethodDeclaration
     addTestSource('class A {String g(int x) {switch(x) {^}}}');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_ThisExpression_block() async {
+  Future<void> test_ThisExpression_block() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
         main() { }
@@ -3890,7 +3908,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor() async {
+  Future<void> test_ThisExpression_constructor() async {
     // MethodInvocation  ExpressionStatement  Block
     addTestSource('''
         main() { }
@@ -3925,7 +3943,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param() async {
+  Future<void> test_ThisExpression_constructor_param() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -3962,7 +3980,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param2() async {
+  Future<void> test_ThisExpression_constructor_param2() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -3998,7 +4016,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param3() async {
+  Future<void> test_ThisExpression_constructor_param3() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -4034,7 +4052,7 @@
     assertNotSuggested('==');
   }
 
-  test_ThisExpression_constructor_param4() async {
+  Future<void> test_ThisExpression_constructor_param4() async {
     // SimpleIdentifier  FieldFormalParameter  FormalParameterList
     addTestSource('''
         main() { }
@@ -4070,7 +4088,7 @@
     assertNotSuggested('==');
   }
 
-  test_TopLevelVariableDeclaration_typed_name() async {
+  Future<void> test_TopLevelVariableDeclaration_typed_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // TopLevelVariableDeclaration
     addTestSource('class A {} B ^');
@@ -4078,7 +4096,7 @@
     assertNoSuggestions();
   }
 
-  test_TopLevelVariableDeclaration_untyped_name() async {
+  Future<void> test_TopLevelVariableDeclaration_untyped_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // TopLevelVariableDeclaration
     addTestSource('class A {} var ^');
@@ -4086,7 +4104,7 @@
     assertNoSuggestions();
   }
 
-  test_TypeArgumentList() async {
+  Future<void> test_TypeArgumentList() async {
     // SimpleIdentifier  BinaryExpression  ExpressionStatement
     addSource('/home/test/lib/a.dart', '''
         class C1 {int x;}
@@ -4111,7 +4129,7 @@
     assertNotSuggested('F2');
   }
 
-  test_TypeArgumentList2() async {
+  Future<void> test_TypeArgumentList2() async {
     // TypeName  TypeArgumentList  TypeName
     addSource('/home/test/lib/a.dart', '''
         class C1 {int x;}
@@ -4131,7 +4149,7 @@
     assertNotSuggested('C2');
   }
 
-  test_VariableDeclaration_name() async {
+  Future<void> test_VariableDeclaration_name() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement  Block
     addSource('/home/test/lib/b.dart', '''
@@ -4147,7 +4165,7 @@
     assertNoSuggestions();
   }
 
-  test_VariableDeclarationList_final() async {
+  Future<void> test_VariableDeclarationList_final() async {
     // VariableDeclarationList  VariableDeclarationStatement  Block
     addTestSource('main() {final ^} class C { }');
     await computeSuggestions();
@@ -4156,7 +4174,7 @@
     assertNotSuggested('==');
   }
 
-  test_VariableDeclarationStatement_RHS() async {
+  Future<void> test_VariableDeclarationStatement_RHS() async {
     // SimpleIdentifier  VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement
     addSource('/home/test/lib/b.dart', '''
@@ -4180,7 +4198,7 @@
     assertNotSuggested('e');
   }
 
-  test_VariableDeclarationStatement_RHS_missing_semicolon() async {
+  Future<void> test_VariableDeclarationStatement_RHS_missing_semicolon() async {
     // VariableDeclaration  VariableDeclarationList
     // VariableDeclarationStatement
     addSource('/home/test/lib/b.dart', '''
@@ -4226,7 +4244,7 @@
     super.setUp();
   }
 
-  test_extensionOverride() async {
+  Future<void> test_extensionOverride() async {
     addTestSource('''
 extension E on int {
   int get foo => 0;
diff --git a/pkg/analysis_server/test/services/completion/dart/uri_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/uri_contributor_test.dart
index 173e70e..bcfffa1 100644
--- a/pkg/analysis_server/test/services/completion/dart/uri_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/uri_contributor_test.dart
@@ -12,7 +12,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UriContributorTest);
     defineReflectiveTests(UriContributorWindowsTest);
@@ -26,7 +26,7 @@
     return UriContributor();
   }
 
-  test_after_import() async {
+  Future<void> test_after_import() async {
     addTestSource('import "p"^');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -34,7 +34,7 @@
     assertNoSuggestions();
   }
 
-  test_after_import_raw() async {
+  Future<void> test_after_import_raw() async {
     addTestSource('import r"p"^');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -42,7 +42,7 @@
     assertNoSuggestions();
   }
 
-  test_before_import() async {
+  Future<void> test_before_import() async {
     addTestSource('import ^"p"');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -50,7 +50,7 @@
     assertNoSuggestions();
   }
 
-  test_before_import_raw() async {
+  Future<void> test_before_import_raw() async {
     addTestSource('import ^r"p"');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -58,7 +58,7 @@
     assertNoSuggestions();
   }
 
-  test_before_import_raw2() async {
+  Future<void> test_before_import_raw2() async {
     addTestSource('import r^"p"');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -66,7 +66,7 @@
     assertNoSuggestions();
   }
 
-  test_export_package2() async {
+  Future<void> test_export_package2() async {
     addPackageFile('foo', 'foo.dart', 'library foo;');
     addPackageFile('foo', 'baz/too.dart', 'library too;');
     addPackageFile('bar', 'bar.dart', 'library bar;');
@@ -76,7 +76,7 @@
         csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_export_package2_off() async {
+  Future<void> test_export_package2_off() async {
     try {
       UriContributor.suggestFilePaths = false;
       addPackageFile('foo', 'foo.dart', 'library foo;');
@@ -90,7 +90,7 @@
     }
   }
 
-  test_import() async {
+  Future<void> test_import() async {
     addTestSource('import "^"');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -99,7 +99,7 @@
     assertSuggest('package:', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import2() async {
+  Future<void> test_import2() async {
     addTestSource('import "^" import');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -108,7 +108,7 @@
     assertSuggest('package:', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import3() async {
+  Future<void> test_import3() async {
     addTestSource('import "^ import');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -117,7 +117,7 @@
     assertSuggest('package:', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_dart() async {
+  Future<void> test_import_dart() async {
     addTestSource('import "d^" import');
     await computeSuggestions();
     expect(replacementOffset, completionOffset - 1);
@@ -130,7 +130,7 @@
     assertSuggest('dart:math', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_dart2() async {
+  Future<void> test_import_dart2() async {
     addTestSource('import "dart:async"; import "d^"');
     await computeSuggestions();
     expect(replacementOffset, completionOffset - 1);
@@ -143,7 +143,7 @@
     assertSuggest('dart:math', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_file() async {
+  Future<void> test_import_file() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     addSource('/proj/foo/bar.dart', 'library bar;');
@@ -160,7 +160,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_import_file2() async {
+  Future<void> test_import_file2() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     addSource('/proj/foo/bar.dart', 'library bar;');
@@ -177,7 +177,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_import_file2_off() async {
+  Future<void> test_import_file2_off() async {
     try {
       UriContributor.suggestFilePaths = false;
       testFile = convertPath('/proj/completion.dart');
@@ -199,7 +199,7 @@
     }
   }
 
-  test_import_file_child() async {
+  Future<void> test_import_file_child() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     addSource('/proj/foo/bar.dart', 'library bar;');
@@ -216,7 +216,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_import_file_outside_lib() async {
+  Future<void> test_import_file_outside_lib() async {
     testFile = convertPath('/proj/lib/completion.dart');
     addSource('/proj/lib/other.dart', 'library other;');
     addSource('/proj/lib/foo/bar.dart', 'library bar;');
@@ -236,7 +236,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_import_file_parent() async {
+  Future<void> test_import_file_parent() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     addSource('/proj/foo/bar.dart', 'library bar;');
@@ -255,7 +255,7 @@
     assertSuggest('../proj2/', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_file_parent2() async {
+  Future<void> test_import_file_parent2() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     addSource('/proj/foo/bar.dart', 'library bar;');
@@ -272,7 +272,7 @@
     assertSuggest('../blat.dart', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_no_dot_folders() async {
+  Future<void> test_import_no_dot_folders() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     newFolder('/proj/.fooFolder');
@@ -281,7 +281,7 @@
     assertNotSuggested('.fooFolder/');
   }
 
-  test_import_only_dart_files() async {
+  Future<void> test_import_only_dart_files() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     newFile('/proj/analysis_options.yaml', content: '# analysis options');
@@ -290,7 +290,7 @@
     assertNotSuggested('analysis_options.yaml');
   }
 
-  test_import_package() async {
+  Future<void> test_import_package() async {
     addPackageFile('foo', 'foo.dart', 'library foo;');
     addPackageFile('foo', 'baz/too.dart', 'library too;');
     addPackageFile('bar', 'bar.dart', 'library bar;');
@@ -309,7 +309,7 @@
         csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_package2() async {
+  Future<void> test_import_package2() async {
     addPackageFile('foo', 'foo.dart', 'library foo;');
     addPackageFile('foo', 'baz/too.dart', 'library too;');
     addPackageFile('bar', 'bar.dart', 'library bar;');
@@ -319,7 +319,7 @@
         csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_package2_off() async {
+  Future<void> test_import_package2_off() async {
     try {
       UriContributor.suggestFilePaths = false;
       addPackageFile('foo', 'foo.dart', 'library foo;');
@@ -333,7 +333,7 @@
     }
   }
 
-  test_import_package2_raw() async {
+  Future<void> test_import_package2_raw() async {
     addPackageFile('foo', 'foo.dart', 'library foo;');
     addPackageFile('foo', 'baz/too.dart', 'library too;');
     addPackageFile('bar', 'bar.dart', 'library bar;');
@@ -343,7 +343,7 @@
         csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_package2_with_trailing() async {
+  Future<void> test_import_package2_with_trailing() async {
     addPackageFile('foo', 'foo.dart', 'library foo;');
     addPackageFile('foo', 'baz/too.dart', 'library too;');
     addPackageFile('bar', 'bar.dart', 'library bar;');
@@ -355,7 +355,7 @@
     expect(replacementLength, 5 + 16);
   }
 
-  test_import_package_missing_lib() async {
+  Future<void> test_import_package_missing_lib() async {
     var pkgFile = addPackageFile('bar', 'bar.dart', 'library bar;');
     deleteFolder(pkgFile.parent.path);
     addTestSource('import "p^" class');
@@ -367,7 +367,7 @@
     assertNotSuggested('package:bar/bar.dart');
   }
 
-  test_import_package_raw() async {
+  Future<void> test_import_package_raw() async {
     addPackageFile('foo', 'foo.dart', 'library foo;');
     addPackageFile('foo', 'baz/too.dart', 'library too;');
     addPackageFile('bar', 'bar.dart', 'library bar;');
@@ -386,7 +386,7 @@
         csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_raw() async {
+  Future<void> test_import_raw() async {
     addTestSource('import r"^" import');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -395,7 +395,7 @@
     assertSuggest('package:', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_without_any_quotes() async {
+  Future<void> test_import_without_any_quotes() async {
     addTestSource('import ^ import');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -403,7 +403,7 @@
     assertNoSuggestions();
   }
 
-  test_import_without_any_quotes_eof() async {
+  Future<void> test_import_without_any_quotes_eof() async {
     addTestSource('import ^');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -411,7 +411,7 @@
     assertNoSuggestions();
   }
 
-  test_import_without_closing_quote_eof() async {
+  Future<void> test_import_without_closing_quote_eof() async {
     addTestSource('import "^');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -420,7 +420,7 @@
     assertSuggest('package:', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_without_closing_quote_eof2() async {
+  Future<void> test_import_without_closing_quote_eof2() async {
     addTestSource('import "^d');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -429,7 +429,7 @@
     assertSuggest('package:', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_without_closing_quote_eof3() async {
+  Future<void> test_import_without_closing_quote_eof3() async {
     addTestSource('import "d^');
     await computeSuggestions();
     expect(replacementOffset, completionOffset - 1);
@@ -438,7 +438,7 @@
     assertSuggest('package:', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_without_closing_quote_eof4() async {
+  Future<void> test_import_without_closing_quote_eof4() async {
     addTestSource('import "d^"');
     await computeSuggestions();
     expect(replacementOffset, completionOffset - 1);
@@ -447,19 +447,19 @@
     assertSuggest('package:', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_outside_import() async {
+  Future<void> test_outside_import() async {
     addTestSource('import ^"d" import');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_outside_import2() async {
+  Future<void> test_outside_import2() async {
     addTestSource('import "d"^ import');
     await computeSuggestions();
     assertNoSuggestions();
   }
 
-  test_part_file() async {
+  Future<void> test_part_file() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     addSource('/proj/foo/bar.dart', 'library bar;');
@@ -476,7 +476,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_part_file2() async {
+  Future<void> test_part_file2() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     addSource('/proj/foo/bar.dart', 'library bar;');
@@ -493,7 +493,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_part_file_child() async {
+  Future<void> test_part_file_child() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     addSource('/proj/foo/bar.dart', 'library bar;');
@@ -510,7 +510,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_part_file_parent() async {
+  Future<void> test_part_file_parent() async {
     testFile = convertPath('/proj/completion.dart');
     addSource('/proj/other.dart', 'library other;');
     addSource('/proj/foo/bar.dart', 'library bar;');
@@ -540,7 +540,7 @@
     resourceProvider = MemoryResourceProvider(context: windows);
   }
 
-  test_import_file() async {
+  Future<void> test_import_file() async {
     testFile = convertPath('\\proj\\completion.dart');
     addSource('\\proj\\other.dart', 'library other;');
     addSource('\\proj\\foo\\bar.dart', 'library bar;');
@@ -557,7 +557,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_import_file2() async {
+  Future<void> test_import_file2() async {
     testFile = convertPath('\\proj\\completion.dart');
     addSource('\\proj\\other.dart', 'library other;');
     addSource('\\proj\\foo\\bar.dart', 'library bar;');
@@ -574,7 +574,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_import_file_child() async {
+  Future<void> test_import_file_child() async {
     testFile = convertPath('\\proj\\completion.dart');
     addSource('\\proj\\other.dart', 'library other;');
     addSource('\\proj\\foo\\bar.dart', 'library bar;');
@@ -591,7 +591,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_import_file_parent() async {
+  Future<void> test_import_file_parent() async {
     testFile = convertPath('\\proj\\completion.dart');
     addSource('\\proj\\other.dart', 'library other;');
     addSource('\\proj\\foo\\bar.dart', 'library bar;');
@@ -608,7 +608,7 @@
     assertSuggest('../blat.dart', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_import_file_parent2() async {
+  Future<void> test_import_file_parent2() async {
     testFile = convertPath('\\proj\\completion.dart');
     addSource('\\proj\\other.dart', 'library other;');
     addSource('\\proj\\foo\\bar.dart', 'library bar;');
@@ -625,7 +625,7 @@
     assertSuggest('../blat.dart', csKind: CompletionSuggestionKind.IMPORT);
   }
 
-  test_part_file() async {
+  Future<void> test_part_file() async {
     testFile = convertPath('\\proj\\completion.dart');
     addSource('\\proj\\other.dart', 'library other;');
     addSource('\\proj\\foo\\bar.dart', 'library bar;');
@@ -642,7 +642,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_part_file2() async {
+  Future<void> test_part_file2() async {
     testFile = convertPath('\\proj\\completion.dart');
     addSource('\\proj\\other.dart', 'library other;');
     addSource('\\proj\\foo\\bar.dart', 'library bar;');
@@ -659,7 +659,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_part_file_child() async {
+  Future<void> test_part_file_child() async {
     testFile = convertPath('\\proj\\completion.dart');
     addSource('\\proj\\other.dart', 'library other;');
     addSource('\\proj\\foo\\bar.dart', 'library bar;');
@@ -676,7 +676,7 @@
     assertNotSuggested('../blat.dart');
   }
 
-  test_part_file_parent() async {
+  Future<void> test_part_file_parent() async {
     testFile = convertPath('\\proj\\completion.dart');
     addSource('\\proj\\other.dart', 'library other;');
     addSource('\\proj\\foo\\bar.dart', 'library bar;');
diff --git a/pkg/analysis_server/test/services/completion/dart/variable_name_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/variable_name_contributor_test.dart
index 1d2f19d..3b75a53 100644
--- a/pkg/analysis_server/test/services/completion/dart/variable_name_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/variable_name_contributor_test.dart
@@ -9,7 +9,7 @@
 
 import 'completion_contributor_util.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(VariableNameContributorTest);
   });
@@ -22,7 +22,7 @@
     return VariableNameContributor();
   }
 
-  test_ExpressionStatement_dont_suggest_type() async {
+  Future<void> test_ExpressionStatement_dont_suggest_type() async {
     addTestSource('''
     f() { a ^ }
     ''');
@@ -32,7 +32,7 @@
     assertNotSuggested('a');
   }
 
-  test_ExpressionStatement_dont_suggest_type_semicolon() async {
+  Future<void> test_ExpressionStatement_dont_suggest_type_semicolon() async {
     addTestSource('''
     f() { a ^; }
     ''');
@@ -42,7 +42,7 @@
     assertNotSuggested('a');
   }
 
-  test_ExpressionStatement_inConstructorBody() async {
+  Future<void> test_ExpressionStatement_inConstructorBody() async {
     addTestSource('''
     class A { A() { AbstractCrazyNonsenseClassName ^ } }
     ''');
@@ -63,7 +63,7 @@
     assertNotSuggested('_name');
   }
 
-  test_ExpressionStatement_inFunctionBody() async {
+  Future<void> test_ExpressionStatement_inFunctionBody() async {
     addTestSource('''
     f() { AbstractCrazyNonsenseClassName ^ }
     ''');
@@ -83,7 +83,7 @@
     assertNotSuggested('_name');
   }
 
-  test_ExpressionStatement_inMethodBody() async {
+  Future<void> test_ExpressionStatement_inMethodBody() async {
     addTestSource('''
     class A { f() { AbstractCrazyNonsenseClassName ^ } }
     ''');
@@ -103,7 +103,7 @@
     assertNotSuggested('_name');
   }
 
-  test_ExpressionStatement_long_semicolon() async {
+  Future<void> test_ExpressionStatement_long_semicolon() async {
     addTestSource('''
     f() { AbstractCrazyNonsenseClassName ^; }
     ''');
@@ -123,7 +123,7 @@
     assertNotSuggested('_name');
   }
 
-  test_ExpressionStatement_prefixed() async {
+  Future<void> test_ExpressionStatement_prefixed() async {
     addTestSource('''
     f() { prefix.AbstractCrazyNonsenseClassName ^ }
     ''');
@@ -143,7 +143,7 @@
     assertNotSuggested('_name');
   }
 
-  test_ExpressionStatement_prefixed_semicolon() async {
+  Future<void> test_ExpressionStatement_prefixed_semicolon() async {
     addTestSource('''
     f() { prefix.AbstractCrazyNonsenseClassName ^; }
     ''');
@@ -163,7 +163,7 @@
     assertNotSuggested('_name');
   }
 
-  test_ExpressionStatement_short() async {
+  Future<void> test_ExpressionStatement_short() async {
     addTestSource('''
     f() { A ^ }
     ''');
@@ -175,7 +175,7 @@
     assertNotSuggested('_a');
   }
 
-  test_ExpressionStatement_short_semicolon() async {
+  Future<void> test_ExpressionStatement_short_semicolon() async {
     addTestSource('''
     f() { A ^; }
     ''');
@@ -188,7 +188,7 @@
   }
 
   @failingTest
-  test_ForStatement() async {
+  Future<void> test_ForStatement() async {
     addTestSource('''
     f() { for(AbstractCrazyNonsenseClassName ^) {} }
     ''');
@@ -208,7 +208,7 @@
     assertNotSuggested('_name');
   }
 
-  test_ForStatement_partial() async {
+  Future<void> test_ForStatement_partial() async {
     addTestSource('''
     f() { for(AbstractCrazyNonsenseClassName a^) {} }
     ''');
@@ -229,7 +229,7 @@
   }
 
   @failingTest
-  test_ForStatement_prefixed() async {
+  Future<void> test_ForStatement_prefixed() async {
     addTestSource('''
     f() { for(prefix.AbstractCrazyNonsenseClassName ^) {} }
     ''');
@@ -249,7 +249,7 @@
     assertNotSuggested('_name');
   }
 
-  test_ForStatement_prefixed_partial() async {
+  Future<void> test_ForStatement_prefixed_partial() async {
     addTestSource('''
     f() { for(prefix.AbstractCrazyNonsenseClassName a^) {} }
     ''');
@@ -269,7 +269,7 @@
     assertNotSuggested('_name');
   }
 
-  test_SimpleFormalParameter_FormalParameterList() async {
+  Future<void> test_SimpleFormalParameter_FormalParameterList() async {
     addTestSource('''
 f(A ^) {}
 ''');
@@ -281,7 +281,7 @@
     assertNotSuggested('_a');
   }
 
-  test_SimpleFormalParameter_itself() async {
+  Future<void> test_SimpleFormalParameter_itself() async {
     addTestSource('''
 f(A n^) {}
 ''');
@@ -293,7 +293,7 @@
     assertNotSuggested('_a');
   }
 
-  test_TopLevelVariableDeclaration_dont_suggest_type() async {
+  Future<void> test_TopLevelVariableDeclaration_dont_suggest_type() async {
     addTestSource('''
     a ^
     ''');
@@ -305,7 +305,8 @@
     assertNotSuggested('_a');
   }
 
-  test_TopLevelVariableDeclaration_dont_suggest_type_semicolon() async {
+  Future<void>
+      test_TopLevelVariableDeclaration_dont_suggest_type_semicolon() async {
     addTestSource('''
     a ^;
     ''');
@@ -317,7 +318,7 @@
     assertNotSuggested('_a');
   }
 
-  test_TopLevelVariableDeclaration_long() async {
+  Future<void> test_TopLevelVariableDeclaration_long() async {
     addTestSource('''
     AbstractCrazyNonsenseClassName ^
     ''');
@@ -337,7 +338,7 @@
     assertSuggestName('_name');
   }
 
-  test_TopLevelVariableDeclaration_long_semicolon() async {
+  Future<void> test_TopLevelVariableDeclaration_long_semicolon() async {
     addTestSource('''
     AbstractCrazyNonsenseClassName ^;
     ''');
@@ -357,7 +358,7 @@
     assertSuggestName('_name');
   }
 
-  test_TopLevelVariableDeclaration_partial() async {
+  Future<void> test_TopLevelVariableDeclaration_partial() async {
     addTestSource('''
     AbstractCrazyNonsenseClassName abs^
     ''');
@@ -377,7 +378,7 @@
     assertSuggestName('_name');
   }
 
-  test_TopLevelVariableDeclaration_partial_semicolon() async {
+  Future<void> test_TopLevelVariableDeclaration_partial_semicolon() async {
     addTestSource('''
     AbstractCrazyNonsenseClassName abs^
     ''');
@@ -397,7 +398,7 @@
     assertSuggestName('_name');
   }
 
-  test_TopLevelVariableDeclaration_prefixed() async {
+  Future<void> test_TopLevelVariableDeclaration_prefixed() async {
     addTestSource('''
     prefix.AbstractCrazyNonsenseClassName ^
     ''');
@@ -417,7 +418,7 @@
     assertSuggestName('_name');
   }
 
-  test_TopLevelVariableDeclaration_prefixed_semicolon() async {
+  Future<void> test_TopLevelVariableDeclaration_prefixed_semicolon() async {
     addTestSource('''
     prefix.AbstractCrazyNonsenseClassName ^;
     ''');
@@ -437,7 +438,7 @@
     assertSuggestName('_name');
   }
 
-  test_TopLevelVariableDeclaration_short() async {
+  Future<void> test_TopLevelVariableDeclaration_short() async {
     addTestSource('''
     A ^
     ''');
@@ -449,7 +450,7 @@
     assertSuggestName('_a');
   }
 
-  test_TopLevelVariableDeclaration_short_semicolon() async {
+  Future<void> test_TopLevelVariableDeclaration_short_semicolon() async {
     addTestSource('''
     A ^;
     ''');
diff --git a/pkg/analysis_server/test/services/completion/postfix/postfix_completion_test.dart b/pkg/analysis_server/test/services/completion/postfix/postfix_completion_test.dart
index a83ad3c..22a6854 100644
--- a/pkg/analysis_server/test/services/completion/postfix/postfix_completion_test.dart
+++ b/pkg/analysis_server/test/services/completion/postfix/postfix_completion_test.dart
@@ -11,7 +11,7 @@
 
 import '../../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(_AssertTest);
     defineReflectiveTests(_ForTest);
@@ -86,7 +86,7 @@
 
 @reflectiveTest
 class _AssertTest extends PostfixCompletionTest {
-  test_assert() async {
+  Future<void> test_assert() async {
     await _prepareCompletion('.assert', '''
 f(bool expr) {
   expr.assert
@@ -99,7 +99,7 @@
 ''');
   }
 
-  test_assertFunc() async {
+  Future<void> test_assertFunc() async {
     await _prepareCompletion('.assert', '''
 f() {
   () => true.assert
@@ -112,7 +112,7 @@
 ''');
   }
 
-  test_assertFunc_invalid() async {
+  Future<void> test_assertFunc_invalid() async {
     await _assertNotApplicable('.assert', '''
 f() {
   () => null.assert
@@ -120,7 +120,7 @@
 ''');
   }
 
-  test_assertFuncCmp() async {
+  Future<void> test_assertFuncCmp() async {
     await _prepareCompletion('.assert', '''
 f(int x, int y) {
   () => x + 3 > y + 4.assert
@@ -136,7 +136,7 @@
 
 @reflectiveTest
 class _ForTest extends PostfixCompletionTest {
-  test_for_invalid() async {
+  Future<void> test_for_invalid() async {
     await _assertNotApplicable('.for', '''
 f() {
   {}.for
@@ -144,7 +144,7 @@
 ''');
   }
 
-  test_forEmptyDynamic() async {
+  Future<void> test_forEmptyDynamic() async {
     await _prepareCompletion('.for', '''
 f() {
   [].for
@@ -159,7 +159,7 @@
 ''');
   }
 
-  test_forEmptyString() async {
+  Future<void> test_forEmptyString() async {
     await _prepareCompletion('.for', '''
 f() {
   <String>[].for
@@ -174,7 +174,7 @@
 ''');
   }
 
-  test_fori() async {
+  Future<void> test_fori() async {
     await _prepareCompletion('.fori', '''
 f() {
   100.fori
@@ -189,7 +189,7 @@
 ''');
   }
 
-  test_fori_invalid() async {
+  Future<void> test_fori_invalid() async {
     await _assertNotApplicable('.fori', '''
 f() {
   [].fori
@@ -197,7 +197,7 @@
 ''');
   }
 
-  test_forIntList() async {
+  Future<void> test_forIntList() async {
     await _prepareCompletion('.for', '''
 f() {
   [1,2,3].for
@@ -212,7 +212,7 @@
 ''');
   }
 
-  test_foriVar() async {
+  Future<void> test_foriVar() async {
     await _prepareCompletion('.fori', '''
 f() {
   var n = 100;
@@ -229,7 +229,7 @@
 ''');
   }
 
-  test_iter_List_dynamic() async {
+  Future<void> test_iter_List_dynamic() async {
     await _prepareCompletion('.iter', '''
 f(List values) {
   values.iter
@@ -244,7 +244,7 @@
 ''');
   }
 
-  test_iter_List_int() async {
+  Future<void> test_iter_List_int() async {
     await _prepareCompletion('.iter', '''
 f(List<int> values) {
   values.iter
@@ -259,7 +259,7 @@
 ''');
   }
 
-  test_iterList() async {
+  Future<void> test_iterList() async {
     await _prepareCompletion('.iter', '''
 f() {
   [1,2,3].iter
@@ -274,7 +274,7 @@
 ''');
   }
 
-  test_iterName() async {
+  Future<void> test_iterName() async {
     await _prepareCompletion('.iter', '''
 f() {
   var value = [1,2,3];
@@ -294,7 +294,7 @@
 
 @reflectiveTest
 class _IfTest extends PostfixCompletionTest {
-  test_Else() async {
+  Future<void> test_Else() async {
     await _prepareCompletion('.else', '''
 f(bool val) {
   val.else
@@ -309,7 +309,7 @@
 ''');
   }
 
-  test_if() async {
+  Future<void> test_if() async {
     await _prepareCompletion('.if', '''
 f() {
   3 < 4.if
@@ -324,7 +324,7 @@
 ''');
   }
 
-  test_if_invalid() async {
+  Future<void> test_if_invalid() async {
     await _assertNotApplicable('.if', '''
 f(List expr) {
   expr.if
@@ -332,7 +332,7 @@
 ''');
   }
 
-  test_if_invalid_importPrefix() async {
+  Future<void> test_if_invalid_importPrefix() async {
     await _assertNotApplicable('.if', '''
 import 'dart:async' as p;
 f() {
@@ -341,7 +341,7 @@
 ''');
   }
 
-  test_ifDynamic() async {
+  Future<void> test_ifDynamic() async {
     await _assertNotApplicable('.if', '''
 f(expr) {
   expr.if
@@ -352,7 +352,7 @@
 
 @reflectiveTest
 class _NegateTest extends PostfixCompletionTest {
-  test_negate() async {
+  Future<void> test_negate() async {
     await _prepareCompletion('.not', '''
 f(bool expr) {
   if (expr.not)
@@ -365,7 +365,7 @@
 ''');
   }
 
-  test_negate_invalid() async {
+  Future<void> test_negate_invalid() async {
     await _assertNotApplicable('.not', '''
 f(int expr) {
   if (expr.not)
@@ -373,7 +373,7 @@
 ''');
   }
 
-  test_negateCascade() async {
+  Future<void> test_negateCascade() async {
     await _prepareCompletion('.not', '''
 f(bool expr) {
   if (expr..a..b..c.not)
@@ -386,7 +386,7 @@
 ''');
   }
 
-  test_negateExpr() async {
+  Future<void> test_negateExpr() async {
     await _prepareCompletion('.not', '''
 f(int i, int j) {
   if (i + 3 < j - 4.not)
@@ -399,7 +399,7 @@
 ''');
   }
 
-  test_negateProperty() async {
+  Future<void> test_negateProperty() async {
     await _prepareCompletion('.not', '''
 f(B b) {
   if (b.a.f.not)
@@ -428,7 +428,7 @@
 ''');
   }
 
-  test_notFalse() async {
+  Future<void> test_notFalse() async {
     await _prepareCompletion('!', '''
 f() {
   if (false!)
@@ -441,7 +441,7 @@
 ''');
   }
 
-  test_notFunc() async {
+  Future<void> test_notFunc() async {
     await _prepareCompletion('.not', '''
 bool f() {
   if (f().not)
@@ -454,7 +454,7 @@
 ''');
   }
 
-  test_notTrue() async {
+  Future<void> test_notTrue() async {
     await _prepareCompletion('.not', '''
 f() {
   if (true.not)
@@ -470,7 +470,7 @@
 
 @reflectiveTest
 class _NotNullTest extends PostfixCompletionTest {
-  test_nn() async {
+  Future<void> test_nn() async {
     await _prepareCompletion('.nn', '''
 f() {
   var list = [1,2,3];
@@ -487,7 +487,7 @@
 ''');
   }
 
-  test_nn_invalid() async {
+  Future<void> test_nn_invalid() async {
     await _assertNotApplicable('.nn', '''
 f() {
   var list = [1,2,3];
@@ -495,7 +495,7 @@
 ''');
   }
 
-  test_nnDynamic() async {
+  Future<void> test_nnDynamic() async {
     await _prepareCompletion('.nn', '''
 f(expr) {
   expr.nn
@@ -510,7 +510,7 @@
 ''');
   }
 
-  test_notnull() async {
+  Future<void> test_notnull() async {
     await _prepareCompletion('.notnull', '''
 f(expr) {
   var list = [1,2,3];
@@ -527,7 +527,7 @@
 ''');
   }
 
-  test_null() async {
+  Future<void> test_null() async {
     await _prepareCompletion('.null', '''
 f(expr) {
   expr.null
@@ -542,7 +542,7 @@
 ''');
   }
 
-  test_nullnn() async {
+  Future<void> test_nullnn() async {
     await _prepareCompletion('.nn', '''
 f() {
   null.nn
@@ -557,7 +557,7 @@
 ''');
   }
 
-  test_nullnull() async {
+  Future<void> test_nullnull() async {
     await _prepareCompletion('.null', '''
 f() {
   null.null
@@ -575,7 +575,7 @@
 
 @reflectiveTest
 class _ParenTest extends PostfixCompletionTest {
-  test_paren() async {
+  Future<void> test_paren() async {
     await _prepareCompletion('.par', '''
 f(expr) {
   expr.par
@@ -591,7 +591,7 @@
 
 @reflectiveTest
 class _ReturnTest extends PostfixCompletionTest {
-  test_return() async {
+  Future<void> test_return() async {
     await _prepareCompletion('.return', '''
 f(expr) {
   expr.return
@@ -607,7 +607,7 @@
 
 @reflectiveTest
 class _SwitchTest extends PostfixCompletionTest {
-  test_return() async {
+  Future<void> test_return() async {
     await _prepareCompletion('.switch', '''
 f(expr) {
   expr.switch
@@ -625,7 +625,7 @@
 
 @reflectiveTest
 class _TryTest extends PostfixCompletionTest {
-  test_try() async {
+  Future<void> test_try() async {
     await _prepareCompletion('.try', '''
 f() {
   var x = 1.try
@@ -642,7 +642,7 @@
 ''');
   }
 
-  test_try_invalid() async {
+  Future<void> test_try_invalid() async {
     // The semicolon is fine; this fails because of the do-statement.
     await _assertNotApplicable('.try', '''
 f() {
@@ -651,7 +651,7 @@
 ''');
   }
 
-  test_tryMultiline() async {
+  Future<void> test_tryMultiline() async {
     await _prepareCompletion('.try', '''
 f(arg) {
   arg
@@ -676,7 +676,7 @@
 ''');
   }
 
-  test_tryon() async {
+  Future<void> test_tryon() async {
     await _prepareCompletion('.tryon', '''
 f() {
   var x = 1.tryon
@@ -693,7 +693,7 @@
 ''');
   }
 
-  test_tryonThrowStatement() async {
+  Future<void> test_tryonThrowStatement() async {
     await _prepareCompletion('.tryon', '''
 f() {
   throw 'error';.tryon
@@ -710,7 +710,7 @@
 ''');
   }
 
-  test_tryonThrowString() async {
+  Future<void> test_tryonThrowString() async {
     await _prepareCompletion('.tryon', '''
 f() {
   throw 'error'.tryon
@@ -730,7 +730,7 @@
 
 @reflectiveTest
 class _WhileTest extends PostfixCompletionTest {
-  test_while() async {
+  Future<void> test_while() async {
     await _prepareCompletion('.while', '''
 f(bool expr) {
   expr.while
diff --git a/pkg/analysis_server/test/services/completion/postfix/test_all.dart b/pkg/analysis_server/test/services/completion/postfix/test_all.dart
index 4f4c9cb..36604fe 100644
--- a/pkg/analysis_server/test/services/completion/postfix/test_all.dart
+++ b/pkg/analysis_server/test/services/completion/postfix/test_all.dart
@@ -6,7 +6,7 @@
 
 import 'postfix_completion_test.dart' as postfix_completion_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     postfix_completion_test.main();
   }, name: 'postfix');
diff --git a/pkg/analysis_server/test/services/completion/statement/statement_completion_test.dart b/pkg/analysis_server/test/services/completion/statement/statement_completion_test.dart
index 1f6ebf7..3e3836c 100644
--- a/pkg/analysis_server/test/services/completion/statement/statement_completion_test.dart
+++ b/pkg/analysis_server/test/services/completion/statement/statement_completion_test.dart
@@ -10,7 +10,7 @@
 
 import '../../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(_ControlFlowCompletionTest);
     defineReflectiveTests(_DeclarationCompletionTest);
@@ -61,7 +61,7 @@
     fail('Expected to find |$message| but got: ' + change.message);
   }
 
-  _computeCompletion(int offset) async {
+  Future<void> _computeCompletion(int offset) async {
     driver.changeFile(testFile);
     ResolvedUnitResult result = await session.getResolvedUnit(testFile);
     var context = StatementCompletionContext(result, offset);
@@ -71,7 +71,7 @@
     change = completion.change;
   }
 
-  _prepareCompletion(String search, String sourceCode,
+  Future<void> _prepareCompletion(String search, String sourceCode,
       {bool atEnd = false, int delta = 0}) async {
     testCode = sourceCode.replaceAll('////', '');
     int offset = findOffset(search);
@@ -81,7 +81,7 @@
     await _prepareCompletionAt(offset + delta, testCode);
   }
 
-  _prepareCompletionAt(int offset, String sourceCode) async {
+  Future<void> _prepareCompletionAt(int offset, String sourceCode) async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit(sourceCode);
     await _computeCompletion(offset);
@@ -90,7 +90,7 @@
 
 @reflectiveTest
 class _ControlFlowCompletionTest extends StatementCompletionTest {
-  test_doReturnExprLineComment() async {
+  Future<void> test_doReturnExprLineComment() async {
     await _prepareCompletion(
         'return 3',
         '''
@@ -114,7 +114,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_doReturnUnterminated() async {
+  Future<void> test_doReturnUnterminated() async {
     await _prepareCompletion(
         'return',
         '''
@@ -138,7 +138,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_forEachReturn() async {
+  Future<void> test_forEachReturn() async {
     await _prepareCompletion(
         'return;',
         '''
@@ -162,7 +162,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_forThrowUnterminated() async {
+  Future<void> test_forThrowUnterminated() async {
     await _prepareCompletion(
         'throw e',
         '''
@@ -186,7 +186,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_ifNoBlock() async {
+  Future<void> test_ifNoBlock() async {
     await _prepareCompletion(
         'return',
         '''
@@ -206,7 +206,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_ifThrow() async {
+  Future<void> test_ifThrow() async {
     await _prepareCompletion(
         'throw e;',
         '''
@@ -230,7 +230,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_ifThrowUnterminated() async {
+  Future<void> test_ifThrowUnterminated() async {
     await _prepareCompletion(
         'throw e',
         '''
@@ -254,7 +254,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_whileReturnExpr() async {
+  Future<void> test_whileReturnExpr() async {
     await _prepareCompletion(
         '+ 4',
         '''
@@ -281,7 +281,7 @@
 
 @reflectiveTest
 class _DeclarationCompletionTest extends StatementCompletionTest {
-  test_classNameNoBody() async {
+  Future<void> test_classNameNoBody() async {
     await _prepareCompletion(
         'Sample',
         '''
@@ -298,7 +298,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_extendsNoBody() async {
+  Future<void> test_extendsNoBody() async {
     await _prepareCompletion(
         'Sample',
         '''
@@ -315,7 +315,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_functionDeclNoBody() async {
+  Future<void> test_functionDeclNoBody() async {
     await _prepareCompletion(
         'source()',
         '''
@@ -332,7 +332,7 @@
         (s) => _after(s, '  '));
   }
 
-  test_functionDeclNoParen() async {
+  Future<void> test_functionDeclNoParen() async {
     await _prepareCompletion(
         'source(',
         '''
@@ -349,7 +349,7 @@
         (s) => _after(s, '  '));
   }
 
-  test_implementsNoBody() async {
+  Future<void> test_implementsNoBody() async {
     await _prepareCompletion(
         'Sample',
         '''
@@ -368,7 +368,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_methodDeclNoBody() async {
+  Future<void> test_methodDeclNoBody() async {
     await _prepareCompletion(
         'source()',
         '''
@@ -389,7 +389,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_methodDeclNoParen() async {
+  Future<void> test_methodDeclNoParen() async {
     await _prepareCompletion(
         'source(',
         '''
@@ -410,7 +410,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_variableDeclNoBody() async {
+  Future<void> test_variableDeclNoBody() async {
     await _prepareCompletion(
         'source',
         '''
@@ -426,7 +426,7 @@
         (s) => _after(s, ';\n'));
   }
 
-  test_withNoBody() async {
+  Future<void> test_withNoBody() async {
     await _prepareCompletion(
         'Sample',
         '''
@@ -448,7 +448,7 @@
 
 @reflectiveTest
 class _DoCompletionTest extends StatementCompletionTest {
-  test_emptyCondition() async {
+  Future<void> test_emptyCondition() async {
     await _prepareCompletion(
         'while ()',
         '''
@@ -469,7 +469,7 @@
         (s) => _after(s, 'while ('));
   }
 
-  test_keywordOnly() async {
+  Future<void> test_keywordOnly() async {
     await _prepareCompletion(
         'do',
         '''
@@ -490,7 +490,7 @@
         (s) => _after(s, 'while ('));
   }
 
-  test_keywordStatement() async {
+  Future<void> test_keywordStatement() async {
     await _prepareCompletion(
         'do',
         '''
@@ -513,7 +513,7 @@
         (s) => _after(s, 'while ('));
   }
 
-  test_noBody() async {
+  Future<void> test_noBody() async {
     await _prepareCompletion(
         'do',
         '''
@@ -535,7 +535,7 @@
         (s) => _after(s, 'while ('));
   }
 
-  test_noCondition() async {
+  Future<void> test_noCondition() async {
     await _prepareCompletion(
         'while',
         '''
@@ -556,7 +556,7 @@
         (s) => _after(s, 'while ('));
   }
 
-  test_noWhile() async {
+  Future<void> test_noWhile() async {
     await _prepareCompletion(
         '}',
         '''
@@ -580,7 +580,7 @@
 
 @reflectiveTest
 class _ExpressionCompletionTest extends StatementCompletionTest {
-  test_listAssign() async {
+  Future<void> test_listAssign() async {
     await _prepareCompletion(
         '= ',
         '''
@@ -600,7 +600,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_listAssignMultiLine() async {
+  Future<void> test_listAssignMultiLine() async {
     // The indent of the final line is incorrect.
     await _prepareCompletion(
         '3',
@@ -629,7 +629,7 @@
   }
 
   @failingTest
-  test_mapAssign() async {
+  Future<void> test_mapAssign() async {
     await _prepareCompletion(
         '3: 3',
         '''
@@ -650,7 +650,7 @@
   }
 
   @failingTest
-  test_mapAssignMissingColon() async {
+  Future<void> test_mapAssignMissingColon() async {
     await _prepareCompletion(
         '3',
         '''
@@ -670,7 +670,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_returnString() async {
+  Future<void> test_returnString() async {
     await _prepareCompletion(
         'text',
         '''
@@ -694,7 +694,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_stringAssign() async {
+  Future<void> test_stringAssign() async {
     await _prepareCompletion(
         '= ',
         '''
@@ -714,7 +714,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_stringSingle() async {
+  Future<void> test_stringSingle() async {
     await _prepareCompletion(
         'text',
         '''
@@ -734,7 +734,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_stringSingleRaw() async {
+  Future<void> test_stringSingleRaw() async {
     await _prepareCompletion(
         'text',
         '''
@@ -754,7 +754,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_stringTriple() async {
+  Future<void> test_stringTriple() async {
     await _prepareCompletion(
         'text',
         '''
@@ -774,7 +774,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_stringTripleRaw() async {
+  Future<void> test_stringTripleRaw() async {
     await _prepareCompletion(
         'text',
         r"""
@@ -797,7 +797,7 @@
 
 @reflectiveTest
 class _ForCompletionTest extends StatementCompletionTest {
-  test_emptyCondition() async {
+  Future<void> test_emptyCondition() async {
     await _prepareCompletion(
         '0;',
         '''
@@ -818,7 +818,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_emptyConditionWithBody() async {
+  Future<void> test_emptyConditionWithBody() async {
     await _prepareCompletion(
         '0;',
         '''
@@ -839,7 +839,7 @@
         (s) => _after(s, '0; '));
   }
 
-  test_emptyInitializers() async {
+  Future<void> test_emptyInitializers() async {
     // This does nothing, same as for Java.
     await _prepareCompletion(
         'r (',
@@ -861,7 +861,7 @@
         (s) => _after(s, 'r ('));
   }
 
-  test_emptyInitializersAfterBody() async {
+  Future<void> test_emptyInitializersAfterBody() async {
     await _prepareCompletion(
         '}',
         '''
@@ -883,7 +883,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_emptyInitializersEmptyCondition() async {
+  Future<void> test_emptyInitializersEmptyCondition() async {
     await _prepareCompletion(
         '/**/',
         '''
@@ -904,7 +904,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_emptyParts() async {
+  Future<void> test_emptyParts() async {
     await _prepareCompletion(
         ';)',
         '''
@@ -925,7 +925,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_emptyUpdaters() async {
+  Future<void> test_emptyUpdaters() async {
     await _prepareCompletion(
         '/**/',
         '''
@@ -946,7 +946,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_emptyUpdatersWithBody() async {
+  Future<void> test_emptyUpdatersWithBody() async {
     await _prepareCompletion(
         '/**/',
         '''
@@ -967,7 +967,7 @@
         (s) => _after(s, '*/; '));
   }
 
-  test_keywordOnly() async {
+  Future<void> test_keywordOnly() async {
     await _prepareCompletion(
         'for',
         '''
@@ -988,7 +988,7 @@
         (s) => _after(s, 'for ('));
   }
 
-  test_missingLeftSeparator() async {
+  Future<void> test_missingLeftSeparator() async {
     await _prepareCompletion(
         '= 0',
         '''
@@ -1009,7 +1009,7 @@
         (s) => _after(s, '0; '));
   }
 
-  test_noError() async {
+  Future<void> test_noError() async {
     await _prepareCompletion(
         ';)',
         '''
@@ -1035,7 +1035,7 @@
 
 @reflectiveTest
 class _ForEachCompletionTest extends StatementCompletionTest {
-  test_emptyIdentifier() async {
+  Future<void> test_emptyIdentifier() async {
     await _prepareCompletion(
         'in xs)',
         '''
@@ -1056,7 +1056,7 @@
         (s) => _after(s, 'for ('));
   }
 
-  test_emptyIdentifierAndIterable() async {
+  Future<void> test_emptyIdentifierAndIterable() async {
     // Analyzer parser produces
     //    for (_s_ in _s_) ;
     // Fasta parser produces
@@ -1081,7 +1081,7 @@
         (s) => _after(s, 'for ('));
   }
 
-  test_emptyIterable() async {
+  Future<void> test_emptyIterable() async {
     await _prepareCompletion(
         'in)',
         '''
@@ -1102,7 +1102,7 @@
         (s) => _after(s, 'in '));
   }
 
-  test_noError() async {
+  Future<void> test_noError() async {
     await _prepareCompletion(
         '])',
         '''
@@ -1128,7 +1128,7 @@
 
 @reflectiveTest
 class _IfCompletionTest extends StatementCompletionTest {
-  test_afterCondition() async {
+  Future<void> test_afterCondition() async {
     await _prepareCompletion(
         'if (true) ', // Trigger completion after space.
         '''
@@ -1149,7 +1149,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_emptyCondition() async {
+  Future<void> test_emptyCondition() async {
     await _prepareCompletion(
         'if ()',
         '''
@@ -1170,7 +1170,7 @@
         (s) => _after(s, 'if ('));
   }
 
-  test_keywordOnly() async {
+  Future<void> test_keywordOnly() async {
     await _prepareCompletion(
         'if',
         '''
@@ -1191,7 +1191,7 @@
         (s) => _after(s, 'if ('));
   }
 
-  test_noError() async {
+  Future<void> test_noError() async {
     await _prepareCompletion(
         'if (true)',
         '''
@@ -1214,7 +1214,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_withCondition() async {
+  Future<void> test_withCondition() async {
     await _prepareCompletion(
         'if (tr', // Trigger completion from within expression.
         '''
@@ -1235,7 +1235,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_withCondition_noRightParenthesis() async {
+  Future<void> test_withCondition_noRightParenthesis() async {
     await _prepareCompletion(
         'if (true',
         '''
@@ -1256,7 +1256,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_withElse() async {
+  Future<void> test_withElse() async {
     await _prepareCompletion(
         'else',
         '''
@@ -1279,7 +1279,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_withElse_BAD() async {
+  Future<void> test_withElse_BAD() async {
     await _prepareCompletion(
         'if ()',
         '''
@@ -1301,7 +1301,7 @@
         (s) => _after(s, 'if ()'));
   }
 
-  test_withElseNoThen() async {
+  Future<void> test_withElseNoThen() async {
     await _prepareCompletion(
         'else',
         '''
@@ -1324,7 +1324,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_withinEmptyCondition() async {
+  Future<void> test_withinEmptyCondition() async {
     await _prepareCompletion(
         'if (',
         '''
@@ -1348,7 +1348,7 @@
 
 @reflectiveTest
 class _SimpleCompletionTest extends StatementCompletionTest {
-  test_enter() async {
+  Future<void> test_enter() async {
     await _prepareCompletion(
         'v = 1;',
         '''
@@ -1365,7 +1365,7 @@
 ''');
   }
 
-  test_expressionBody() async {
+  Future<void> test_expressionBody() async {
     await _prepareCompletion(
         '=> 1',
         '''
@@ -1382,7 +1382,7 @@
 ''');
   }
 
-  test_noCloseParen() async {
+  Future<void> test_noCloseParen() async {
     await _prepareCompletion(
         'ing(3',
         '''
@@ -1403,7 +1403,7 @@
   }
 
   @failingTest
-  test_noCloseParenWithSemicolon() async {
+  Future<void> test_noCloseParenWithSemicolon() async {
     // TODO(danrubel):
     // Fasta scanner produces an error message which is converted into
     // an Analyzer error message before the fasta parser gets a chance
@@ -1439,7 +1439,7 @@
     throw 'remove this once fasta parser is enabled by default';
   }
 
-  test_semicolonFn() async {
+  Future<void> test_semicolonFn() async {
     await _prepareCompletion(
         '=> 3',
         '''
@@ -1459,7 +1459,7 @@
         (s) => _afterLast(s, '  '));
   }
 
-  test_semicolonFnBody() async {
+  Future<void> test_semicolonFnBody() async {
     // It would be reasonable to add braces in this case. Unfortunately,
     // the incomplete line parses as two statements ['int;', 'f();'], not one.
     await _prepareCompletion(
@@ -1481,7 +1481,7 @@
   }
 
   @failingTest
-  test_semicolonFnBodyWithDef() async {
+  Future<void> test_semicolonFnBodyWithDef() async {
     // This ought to be the same as test_semicolonFnBody() but the definition
     // of f() removes an error and it appears to be a different case.
     // Suggestions for unifying the two are welcome.
@@ -1519,7 +1519,7 @@
     throw 'remove this once fasta parser is enabled by default';
   }
 
-  test_semicolonFnExpr() async {
+  Future<void> test_semicolonFnExpr() async {
     await _prepareCompletion(
         '=>',
         '''
@@ -1539,7 +1539,7 @@
         (s) => _afterLast(s, '=> '));
   }
 
-  test_semicolonFnSpaceExpr() async {
+  Future<void> test_semicolonFnSpaceExpr() async {
     await _prepareCompletion(
         '=>',
         '''
@@ -1559,7 +1559,7 @@
         (s) => _afterLast(s, '=> '));
   }
 
-  test_semicolonVar() async {
+  Future<void> test_semicolonVar() async {
     await _prepareCompletion(
         'v = 1',
         '''
@@ -1582,7 +1582,7 @@
 
 @reflectiveTest
 class _SwitchCompletionTest extends StatementCompletionTest {
-  test_caseNoColon() async {
+  Future<void> test_caseNoColon() async {
     await _prepareCompletion(
         'label',
         '''
@@ -1605,7 +1605,7 @@
         (s) => _after(s, 'label: '));
   }
 
-  test_defaultNoColon() async {
+  Future<void> test_defaultNoColon() async {
     await _prepareCompletion(
         'default',
         '''
@@ -1628,7 +1628,7 @@
         (s) => _after(s, 'default: '));
   }
 
-  test_emptyCondition() async {
+  Future<void> test_emptyCondition() async {
     await _prepareCompletion(
         'switch',
         '''
@@ -1649,7 +1649,7 @@
         (s) => _after(s, 'switch ('));
   }
 
-  test_keywordOnly() async {
+  Future<void> test_keywordOnly() async {
     await _prepareCompletion(
         'switch',
         '''
@@ -1670,7 +1670,7 @@
         (s) => _after(s, 'switch ('));
   }
 
-  test_keywordSpace() async {
+  Future<void> test_keywordSpace() async {
     await _prepareCompletion(
         'switch',
         '''
@@ -1694,7 +1694,7 @@
 
 @reflectiveTest
 class _TryCompletionTest extends StatementCompletionTest {
-  test_catchOnly() async {
+  Future<void> test_catchOnly() async {
     await _prepareCompletion(
         '{} catch',
         '''
@@ -1717,7 +1717,7 @@
         (s) => _after(s, 'catch ('));
   }
 
-  test_catchSecond() async {
+  Future<void> test_catchSecond() async {
     await _prepareCompletion(
         '} catch ',
         '''
@@ -1742,7 +1742,7 @@
         (s) => _afterLast(s, 'catch ('));
   }
 
-  test_finallyOnly() async {
+  Future<void> test_finallyOnly() async {
     await _prepareCompletion(
         'finally',
         '''
@@ -1765,7 +1765,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_keywordOnly() async {
+  Future<void> test_keywordOnly() async {
     await _prepareCompletion(
         'try',
         '''
@@ -1786,7 +1786,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_keywordSpace() async {
+  Future<void> test_keywordSpace() async {
     await _prepareCompletion(
         'try',
         '''
@@ -1807,7 +1807,7 @@
         (s) => _after(s, '    '));
   }
 
-  test_onCatch() async {
+  Future<void> test_onCatch() async {
     await _prepareCompletion(
         'on',
         '''
@@ -1830,7 +1830,7 @@
         (s) => _after(s, 'catch ('));
   }
 
-  test_onCatchComment() async {
+  Future<void> test_onCatchComment() async {
     await _prepareCompletion(
         'on',
         '''
@@ -1855,7 +1855,7 @@
         (s) => _after(s, 'catch ('));
   }
 
-  test_onOnly() async {
+  Future<void> test_onOnly() async {
     await _prepareCompletion(
         'on',
         '''
@@ -1878,7 +1878,7 @@
         (s) => _after(s, ' on '));
   }
 
-  test_onSpace() async {
+  Future<void> test_onSpace() async {
     await _prepareCompletion(
         'on',
         '''
@@ -1901,7 +1901,7 @@
         (s) => _after(s, ' on '));
   }
 
-  test_onSpaces() async {
+  Future<void> test_onSpaces() async {
     await _prepareCompletion(
         'on',
         '''
@@ -1924,7 +1924,7 @@
         (s) => _after(s, ' on '));
   }
 
-  test_onType() async {
+  Future<void> test_onType() async {
     await _prepareCompletion(
         'on',
         '''
@@ -1957,7 +1957,7 @@
      _IfCompletionTest tests. If the implementation changes then the same
      set of tests defined for if-statements should be duplicated here.
    */
-  test_keywordOnly() async {
+  Future<void> test_keywordOnly() async {
     await _prepareCompletion(
         'while',
         '''
diff --git a/pkg/analysis_server/test/services/completion/statement/test_all.dart b/pkg/analysis_server/test/services/completion/statement/test_all.dart
index fb89619..6d4d86e 100644
--- a/pkg/analysis_server/test/services/completion/statement/test_all.dart
+++ b/pkg/analysis_server/test/services/completion/statement/test_all.dart
@@ -6,7 +6,7 @@
 
 import 'statement_completion_test.dart' as statement_completion_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     statement_completion_test.main();
   }, name: 'statement');
diff --git a/pkg/analysis_server/test/services/completion/test_all.dart b/pkg/analysis_server/test/services/completion/test_all.dart
index 11542d1..533fb7a 100644
--- a/pkg/analysis_server/test/services/completion/test_all.dart
+++ b/pkg/analysis_server/test/services/completion/test_all.dart
@@ -8,7 +8,7 @@
 import 'postfix/test_all.dart' as postfix_all;
 import 'statement/test_all.dart' as statement_all;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     dart_all.main();
     postfix_all.main();
diff --git a/pkg/analysis_server/test/services/correction/change_test.dart b/pkg/analysis_server/test/services/correction/change_test.dart
index 1ce454e..75d9adf 100644
--- a/pkg/analysis_server/test/services/correction/change_test.dart
+++ b/pkg/analysis_server/test/services/correction/change_test.dart
@@ -9,7 +9,7 @@
 
 import '../../constants.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ChangeTest);
     defineReflectiveTests(EditTest);
diff --git a/pkg/analysis_server/test/services/correction/levenshtein_test.dart b/pkg/analysis_server/test/services/correction/levenshtein_test.dart
index d8a77e6..dc320bd 100644
--- a/pkg/analysis_server/test/services/correction/levenshtein_test.dart
+++ b/pkg/analysis_server/test/services/correction/levenshtein_test.dart
@@ -6,7 +6,7 @@
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LevenshteinTest);
   });
diff --git a/pkg/analysis_server/test/services/correction/name_suggestion_test.dart b/pkg/analysis_server/test/services/correction/name_suggestion_test.dart
index 3f50c49..747aa1a 100644
--- a/pkg/analysis_server/test/services/correction/name_suggestion_test.dart
+++ b/pkg/analysis_server/test/services/correction/name_suggestion_test.dart
@@ -10,7 +10,7 @@
 
 import '../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(VariableNameSuggestionTest);
   });
@@ -18,7 +18,7 @@
 
 @reflectiveTest
 class VariableNameSuggestionTest extends AbstractSingleUnitTest {
-  test_forExpression_cast() async {
+  Future<void> test_forExpression_cast() async {
     await resolveTestUnit('''
 main() {
   var sortedNodes;
@@ -31,7 +31,7 @@
         unorderedEquals(['sortedNodes', 'nodes']));
   }
 
-  test_forExpression_expectedType() async {
+  Future<void> test_forExpression_expectedType() async {
     await resolveTestUnit('''
 class TreeNode {}
 main() {
@@ -47,7 +47,7 @@
     expect(suggestions, unorderedEquals(['treeNode', 'node']));
   }
 
-  test_forExpression_expectedType_double() async {
+  Future<void> test_forExpression_expectedType_double() async {
     await resolveTestUnit('''
 main() {
   double res = 0.0;
@@ -67,7 +67,7 @@
         unorderedEquals(['f']));
   }
 
-  test_forExpression_expectedType_int() async {
+  Future<void> test_forExpression_expectedType_int() async {
     await resolveTestUnit('''
 main() {
   int res = 0;
@@ -87,7 +87,7 @@
         unorderedEquals(['k']));
   }
 
-  test_forExpression_expectedType_String() async {
+  Future<void> test_forExpression_expectedType_String() async {
     await resolveTestUnit('''
 main() {
   String res = 'abc';
@@ -102,7 +102,7 @@
         unorderedEquals(['s']));
   }
 
-  test_forExpression_inBuildMethod() async {
+  Future<void> test_forExpression_inBuildMethod() async {
     await resolveTestUnit('''
 class A {
   void build() {
@@ -122,7 +122,7 @@
         unorderedEquals(['buildList']));
   }
 
-  test_forExpression_indexExpression_endsWithE() async {
+  Future<void> test_forExpression_indexExpression_endsWithE() async {
     await resolveTestUnit('''
 main() {
   var topNodes = [0, 1, 2];
@@ -135,7 +135,7 @@
     expect(names, unorderedEquals(['topNode', 'node', 'object']));
   }
 
-  test_forExpression_instanceCreation() async {
+  Future<void> test_forExpression_instanceCreation() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 import 'dart:math' as p;
@@ -164,7 +164,7 @@
 //        unorderedEquals(['noSuchClass', 'suchClass', 'class']));
   }
 
-  test_forExpression_invocationArgument_named() async {
+  Future<void> test_forExpression_invocationArgument_named() async {
     await resolveTestUnit('''
 foo({a, b, c}) {}
 main() {
@@ -189,7 +189,7 @@
     }
   }
 
-  test_forExpression_invocationArgument_optional() async {
+  Future<void> test_forExpression_invocationArgument_optional() async {
     await resolveTestUnit('''
 foo(a, [b = 2, c = 3]) {}
 main() {
@@ -214,7 +214,7 @@
     }
   }
 
-  test_forExpression_invocationArgument_positional() async {
+  Future<void> test_forExpression_invocationArgument_positional() async {
     await resolveTestUnit('''
 foo(a, b) {}
 main() {
@@ -234,7 +234,7 @@
     }
   }
 
-  test_forExpression_methodInvocation() async {
+  Future<void> test_forExpression_methodInvocation() async {
     await resolveTestUnit('''
 main(p) {
   var res = p.getSortedNodes();
@@ -246,7 +246,7 @@
         unorderedEquals(['sortedNodes', 'nodes']));
   }
 
-  test_forExpression_methodInvocation_noPrefix() async {
+  Future<void> test_forExpression_methodInvocation_noPrefix() async {
     await resolveTestUnit('''
 main(p) {
   var res = p.sortedNodes();
@@ -258,7 +258,7 @@
         unorderedEquals(['sortedNodes', 'nodes']));
   }
 
-  test_forExpression_name_get() async {
+  Future<void> test_forExpression_name_get() async {
     await resolveTestUnit('''
 main(p) {
   var res = p.get();
@@ -270,7 +270,7 @@
         unorderedEquals([]));
   }
 
-  test_forExpression_prefixedIdentifier() async {
+  Future<void> test_forExpression_prefixedIdentifier() async {
     await resolveTestUnit('''
 main(p) {
   var res = p.sortedNodes;
@@ -285,7 +285,7 @@
         unorderedEquals(['sortedNodes', 'nodes']));
   }
 
-  test_forExpression_privateName() async {
+  Future<void> test_forExpression_privateName() async {
     await resolveTestUnit('''
 main(p) {
   p._name;
@@ -307,7 +307,7 @@
         unorderedEquals(['computeSuffix', 'suffix']));
   }
 
-  test_forExpression_propertyAccess() async {
+  Future<void> test_forExpression_propertyAccess() async {
     await resolveTestUnit('''
 main(p) {
   var res = p.q.sortedNodes;
@@ -320,7 +320,7 @@
         unorderedEquals(['sortedNodes', 'nodes']));
   }
 
-  test_forExpression_simpleName() async {
+  Future<void> test_forExpression_simpleName() async {
     await resolveTestUnit('''
 main(p) {
   var sortedNodes = null;
@@ -333,7 +333,7 @@
         unorderedEquals(['sortedNodes', 'nodes']));
   }
 
-  test_forExpression_unqualifiedInvocation() async {
+  Future<void> test_forExpression_unqualifiedInvocation() async {
     await resolveTestUnit('''
 getSortedNodes() => [];
 main(p) {
diff --git a/pkg/analysis_server/test/services/correction/organize_directives_test.dart b/pkg/analysis_server/test/services/correction/organize_directives_test.dart
index 5e85c38..9842672 100644
--- a/pkg/analysis_server/test/services/correction/organize_directives_test.dart
+++ b/pkg/analysis_server/test/services/correction/organize_directives_test.dart
@@ -14,7 +14,7 @@
 
 import '../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(OrganizeDirectivesTest);
   });
@@ -24,7 +24,7 @@
 class OrganizeDirectivesTest extends AbstractSingleUnitTest {
   List<AnalysisError> testErrors;
 
-  test_docComment_beforeDirective_hasUnresolvedIdentifier() async {
+  Future<void> test_docComment_beforeDirective_hasUnresolvedIdentifier() async {
     await _computeUnitAndErrors(r'''
 /// Library documentation comment A
 /// Library documentation comment B
@@ -44,7 +44,7 @@
 ''');
   }
 
-  test_keep_duplicateImports_withDifferentPrefix() async {
+  Future<void> test_keep_duplicateImports_withDifferentPrefix() async {
     await _computeUnitAndErrors(r'''
 import 'dart:async' as async1;
 import 'dart:async' as async2;
@@ -64,7 +64,7 @@
 }''', removeUnused: true);
   }
 
-  test_keep_unresolvedDirectives() async {
+  Future<void> test_keep_unresolvedDirectives() async {
     var code = r'''
 import 'dart:noSuchImportSdkLibrary';
 
@@ -80,7 +80,7 @@
     _assertOrganize(code);
   }
 
-  test_remove_duplicateImports() async {
+  Future<void> test_remove_duplicateImports() async {
     await _computeUnitAndErrors(r'''
 import 'dart:async';
 import 'dart:async';
@@ -97,7 +97,7 @@
 }''', removeUnused: true);
   }
 
-  test_remove_duplicateImports_differentText_uri() async {
+  Future<void> test_remove_duplicateImports_differentText_uri() async {
     await _computeUnitAndErrors(r'''
 import 'dart:async' as async;
 import "dart:async" as async;
@@ -114,7 +114,7 @@
 }''', removeUnused: true);
   }
 
-  test_remove_duplicateImports_withSamePrefix() async {
+  Future<void> test_remove_duplicateImports_withSamePrefix() async {
     await _computeUnitAndErrors(r'''
 import 'dart:async' as async;
 import 'dart:async' as async;
@@ -131,7 +131,7 @@
 }''', removeUnused: true);
   }
 
-  test_remove_unusedImports() async {
+  Future<void> test_remove_unusedImports() async {
     await _computeUnitAndErrors(r'''
 library lib;
 
@@ -159,7 +159,7 @@
 ''', removeUnused: true);
   }
 
-  test_remove_unusedImports2() async {
+  Future<void> test_remove_unusedImports2() async {
     await _computeUnitAndErrors(r'''
 import 'dart:async';
 import 'dart:math';
@@ -180,7 +180,7 @@
 }''', removeUnused: true);
   }
 
-  test_remove_unusedImports_hasUnresolvedError() async {
+  Future<void> test_remove_unusedImports_hasUnresolvedError() async {
     Future<void> check(String declaration) async {
       String code = '''
 import 'dart:async';
@@ -201,7 +201,7 @@
     await check('List<Unresolved> v;');
   }
 
-  test_sort() async {
+  Future<void> test_sort() async {
     await _computeUnitAndErrors(r'''
 library lib;
 
@@ -263,7 +263,7 @@
 ''');
   }
 
-  test_sort_hasComments() async {
+  Future<void> test_sort_hasComments() async {
     await _computeUnitAndErrors(r'''
 // header
 library lib;
@@ -291,7 +291,7 @@
 ''');
   }
 
-  test_sort_imports_packageAndPath() async {
+  Future<void> test_sort_imports_packageAndPath() async {
     await _computeUnitAndErrors(r'''
 library lib;
 
diff --git a/pkg/analysis_server/test/services/correction/sort_members_test.dart b/pkg/analysis_server/test/services/correction/sort_members_test.dart
index ca789b8..f218132 100644
--- a/pkg/analysis_server/test/services/correction/sort_members_test.dart
+++ b/pkg/analysis_server/test/services/correction/sort_members_test.dart
@@ -12,7 +12,7 @@
 
 import '../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SortMembersTest);
   });
@@ -20,7 +20,7 @@
 
 @reflectiveTest
 class SortMembersTest extends AbstractSingleUnitTest {
-  test_classMembers_accessor() async {
+  Future<void> test_classMembers_accessor() async {
     await _parseTestUnit(r'''
 class A {
   set c(x) {}
@@ -44,7 +44,7 @@
 ''');
   }
 
-  test_classMembers_accessor_static() async {
+  Future<void> test_classMembers_accessor_static() async {
     await _parseTestUnit(r'''
 class A {
   get a => null;
@@ -64,7 +64,7 @@
 ''');
   }
 
-  test_classMembers_constructor() async {
+  Future<void> test_classMembers_constructor() async {
     await _parseTestUnit(r'''
 class A {
   A.c() {   }
@@ -84,7 +84,7 @@
 ''');
   }
 
-  test_classMembers_external_constructorMethod() async {
+  Future<void> test_classMembers_external_constructorMethod() async {
     await _parseTestUnit(r'''
 class Chart {
   external Pie();
@@ -100,7 +100,7 @@
 ''');
   }
 
-  test_classMembers_field() async {
+  Future<void> test_classMembers_field() async {
     await _parseTestUnit(r'''
 class A {
   String c;
@@ -120,7 +120,7 @@
 ''');
   }
 
-  test_classMembers_field_static() async {
+  Future<void> test_classMembers_field_static() async {
     await _parseTestUnit(r'''
 class A {
   int b;
@@ -140,7 +140,7 @@
 ''');
   }
 
-  test_classMembers_method() async {
+  Future<void> test_classMembers_method() async {
     await _parseTestUnit(r'''
 class A {
   c() {}
@@ -158,7 +158,7 @@
 ''');
   }
 
-  test_classMembers_method_emptyLine() async {
+  Future<void> test_classMembers_method_emptyLine() async {
     await _parseTestUnit(r'''
 class A {
   b() {}
@@ -176,7 +176,7 @@
 ''');
   }
 
-  test_classMembers_method_ignoreCase() async {
+  Future<void> test_classMembers_method_ignoreCase() async {
     await _parseTestUnit(r'''
 class A {
   m_C() {}
@@ -194,7 +194,7 @@
 ''');
   }
 
-  test_classMembers_method_static() async {
+  Future<void> test_classMembers_method_static() async {
     await _parseTestUnit(r'''
 class A {
   static a() {}
@@ -210,7 +210,7 @@
 ''');
   }
 
-  test_classMembers_mix() async {
+  Future<void> test_classMembers_mix() async {
     await _parseTestUnit(r'''
 class A {
   /// static field public
@@ -310,7 +310,7 @@
 ''');
   }
 
-  test_directives() async {
+  Future<void> test_directives() async {
     await _parseTestUnit(r'''
 library lib;
 
@@ -372,7 +372,7 @@
 ''');
   }
 
-  test_directives_docComment_hasLibrary_lines() async {
+  Future<void> test_directives_docComment_hasLibrary_lines() async {
     await _parseTestUnit(r'''
 /// Library documentation comment A.
 /// Library documentation comment B.
@@ -402,7 +402,7 @@
 ''');
   }
 
-  test_directives_docComment_hasLibrary_stars() async {
+  Future<void> test_directives_docComment_hasLibrary_stars() async {
     await _parseTestUnit(r'''
 /**
  * Library documentation comment A.
@@ -440,7 +440,7 @@
 ''');
   }
 
-  test_directives_docComment_noLibrary_lines() async {
+  Future<void> test_directives_docComment_noLibrary_lines() async {
     await _parseTestUnit(r'''
 /// Library documentation comment A
 /// Library documentation comment B
@@ -460,7 +460,7 @@
 ''');
   }
 
-  test_directives_docComment_noLibrary_stars() async {
+  Future<void> test_directives_docComment_noLibrary_stars() async {
     await _parseTestUnit(r'''
 /**
  * Library documentation comment A.
@@ -488,7 +488,7 @@
 ''');
   }
 
-  test_directives_imports_packageAndPath() async {
+  Future<void> test_directives_imports_packageAndPath() async {
     await _parseTestUnit(r'''
 library lib;
 
@@ -512,7 +512,7 @@
 ''');
   }
 
-  test_mixinMembers_method() async {
+  Future<void> test_mixinMembers_method() async {
     await _parseTestUnit(r'''
 mixin A {
   c() {}
@@ -530,7 +530,7 @@
 ''');
   }
 
-  test_unitMembers_class() async {
+  Future<void> test_unitMembers_class() async {
     await _parseTestUnit(r'''
 class C {}
 class A {}
@@ -544,7 +544,7 @@
 ''');
   }
 
-  test_unitMembers_class_ignoreCase() async {
+  Future<void> test_unitMembers_class_ignoreCase() async {
     await _parseTestUnit(r'''
 class C {}
 class a {}
@@ -558,7 +558,7 @@
 ''');
   }
 
-  test_unitMembers_classTypeAlias() async {
+  Future<void> test_unitMembers_classTypeAlias() async {
     await _parseTestUnit(r'''
 class M {}
 class C = Object with M;
@@ -574,7 +574,7 @@
 ''');
   }
 
-  test_unitMembers_directive_hasDirective() async {
+  Future<void> test_unitMembers_directive_hasDirective() async {
     await _parseTestUnit(r'''
 library lib;
 class C {}
@@ -590,7 +590,7 @@
 ''');
   }
 
-  test_unitMembers_directive_noDirective_hasComment_line() async {
+  Future<void> test_unitMembers_directive_noDirective_hasComment_line() async {
     await _parseTestUnit(r'''
 // Some comment
 
@@ -608,7 +608,7 @@
 ''');
   }
 
-  test_unitMembers_directive_noDirective_noComment() async {
+  Future<void> test_unitMembers_directive_noDirective_noComment() async {
     await _parseTestUnit(r'''
 
 class B {}
@@ -624,7 +624,7 @@
 ''');
   }
 
-  test_unitMembers_enum() async {
+  Future<void> test_unitMembers_enum() async {
     await _parseTestUnit(r'''
 enum C {x, y}
 enum A {x, y}
@@ -638,7 +638,7 @@
 ''');
   }
 
-  test_unitMembers_enumClass() async {
+  Future<void> test_unitMembers_enumClass() async {
     await _parseTestUnit(r'''
 enum C {x, y}
 class A {}
@@ -654,7 +654,7 @@
 ''');
   }
 
-  test_unitMembers_extensionClass() async {
+  Future<void> test_unitMembers_extensionClass() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     await _parseTestUnit(r'''
 extension E on C {}
@@ -667,7 +667,7 @@
 ''');
   }
 
-  test_unitMembers_extensions() async {
+  Future<void> test_unitMembers_extensions() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     await _parseTestUnit(r'''
 extension E2 on String {}
@@ -684,7 +684,7 @@
 ''');
   }
 
-  test_unitMembers_function() async {
+  Future<void> test_unitMembers_function() async {
     await _parseTestUnit(r'''
 fc() {}
 fa() {}
@@ -698,7 +698,7 @@
 ''');
   }
 
-  test_unitMembers_functionTypeAlias() async {
+  Future<void> test_unitMembers_functionTypeAlias() async {
     await _parseTestUnit(r'''
 typedef FC();
 typedef FA();
@@ -712,7 +712,7 @@
 ''');
   }
 
-  test_unitMembers_genericTypeAlias() async {
+  Future<void> test_unitMembers_genericTypeAlias() async {
     await _parseTestUnit(r'''
 typedef FC = void Function();
 typedef FA = void Function();
@@ -726,7 +726,7 @@
 ''');
   }
 
-  test_unitMembers_importsAndDeclarations() async {
+  Future<void> test_unitMembers_importsAndDeclarations() async {
     await _parseTestUnit(r'''
 import 'dart:a';
 import 'package:b';
@@ -749,7 +749,7 @@
 ''');
   }
 
-  test_unitMembers_mainFirst() async {
+  Future<void> test_unitMembers_mainFirst() async {
     await _parseTestUnit(r'''
 class C {}
 aaa() {}
@@ -769,7 +769,7 @@
 ''');
   }
 
-  test_unitMembers_mix() async {
+  Future<void> test_unitMembers_mix() async {
     await _parseTestUnit(r'''
 _mmm() {}
 typedef nnn();
@@ -831,7 +831,7 @@
 ''');
   }
 
-  test_unitMembers_mixin() async {
+  Future<void> test_unitMembers_mixin() async {
     await _parseTestUnit(r'''
 mixin C {}
 mixin A {}
@@ -844,7 +844,7 @@
 ''');
   }
 
-  test_unitMembers_topLevelVariable() async {
+  Future<void> test_unitMembers_topLevelVariable() async {
     await _parseTestUnit(r'''
 int c;
 int a;
@@ -858,7 +858,7 @@
 ''');
   }
 
-  test_unitMembers_topLevelVariable_withConst() async {
+  Future<void> test_unitMembers_topLevelVariable_withConst() async {
     await _parseTestUnit(r'''
 int c;
 int a;
diff --git a/pkg/analysis_server/test/services/correction/status_test.dart b/pkg/analysis_server/test/services/correction/status_test.dart
index 7c9e180..250b663 100644
--- a/pkg/analysis_server/test/services/correction/status_test.dart
+++ b/pkg/analysis_server/test/services/correction/status_test.dart
@@ -15,7 +15,7 @@
 
 import '../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RefactoringLocationTest);
     defineReflectiveTests(RefactoringStatusTest);
@@ -24,7 +24,7 @@
 
 @reflectiveTest
 class RefactoringLocationTest extends AbstractSingleUnitTest {
-  test_createLocation_forElement() async {
+  Future<void> test_createLocation_forElement() async {
     await resolveTestUnit('class MyClass {}');
     Element element = findElement('MyClass');
     // check
@@ -36,7 +36,7 @@
     expect(location.startColumn, 7);
   }
 
-  test_createLocation_forMatch() async {
+  Future<void> test_createLocation_forMatch() async {
     await resolveTestUnit('class MyClass {}');
     Element element = findElement('MyClass');
     SourceRange sourceRange = range.elementName(element);
@@ -57,7 +57,7 @@
     expect(location.length, sourceRange.length);
   }
 
-  test_createLocation_forNode() async {
+  Future<void> test_createLocation_forNode() async {
     await resolveTestUnit('''
 main() {
 }
@@ -70,7 +70,7 @@
     expect(location.length, node.length);
   }
 
-  test_createLocation_forUnit() async {
+  Future<void> test_createLocation_forUnit() async {
     await resolveTestUnit('');
     SourceRange sourceRange = SourceRange(10, 20);
     // check
diff --git a/pkg/analysis_server/test/services/correction/test_all.dart b/pkg/analysis_server/test/services/correction/test_all.dart
index 022ae48..0b289d9 100644
--- a/pkg/analysis_server/test/services/correction/test_all.dart
+++ b/pkg/analysis_server/test/services/correction/test_all.dart
@@ -12,8 +12,7 @@
 import 'status_test.dart' as status_test;
 import 'util_test.dart' as util_test;
 
-/// Utility for manually running all tests.
-main() {
+void main() {
   defineReflectiveSuite(() {
     change_test.main();
     levenshtein_test.main();
diff --git a/pkg/analysis_server/test/services/correction/util_test.dart b/pkg/analysis_server/test/services/correction/util_test.dart
index 8fb699f..fdd64e2 100644
--- a/pkg/analysis_server/test/services/correction/util_test.dart
+++ b/pkg/analysis_server/test/services/correction/util_test.dart
@@ -13,7 +13,7 @@
 
 import '../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UtilTest);
   });
@@ -40,7 +40,7 @@
     expect(result, expected);
   }
 
-  test_addLibraryImports_dart_hasImports_between() async {
+  Future<void> test_addLibraryImports_dart_hasImports_between() async {
     await resolveTestUnit('''
 import 'dart:async';
 import 'dart:math';
@@ -53,7 +53,7 @@
 ''');
   }
 
-  test_addLibraryImports_dart_hasImports_first() async {
+  Future<void> test_addLibraryImports_dart_hasImports_first() async {
     await resolveTestUnit('''
 import 'dart:collection';
 import 'dart:math';
@@ -66,7 +66,7 @@
 ''');
   }
 
-  test_addLibraryImports_dart_hasImports_last() async {
+  Future<void> test_addLibraryImports_dart_hasImports_last() async {
     await resolveTestUnit('''
 import 'dart:async';
 import 'dart:collection';
@@ -79,7 +79,7 @@
 ''');
   }
 
-  test_addLibraryImports_dart_hasImports_multiple() async {
+  Future<void> test_addLibraryImports_dart_hasImports_multiple() async {
     await resolveTestUnit('''
 import 'dart:collection';
 import 'dart:math';
@@ -94,7 +94,7 @@
 ''');
   }
 
-  test_addLibraryImports_dart_hasImports_multiple_first() async {
+  Future<void> test_addLibraryImports_dart_hasImports_multiple_first() async {
     await resolveTestUnit('''
 import 'dart:html';
 import 'dart:math';
@@ -109,7 +109,7 @@
 ''');
   }
 
-  test_addLibraryImports_dart_hasImports_multiple_last() async {
+  Future<void> test_addLibraryImports_dart_hasImports_multiple_last() async {
     await resolveTestUnit('''
 import 'dart:async';
 import 'dart:collection';
@@ -124,7 +124,7 @@
 ''');
   }
 
-  test_addLibraryImports_dart_hasLibraryDirective() async {
+  Future<void> test_addLibraryImports_dart_hasLibraryDirective() async {
     await resolveTestUnit('''
 library test;
 
@@ -142,7 +142,7 @@
 ''');
   }
 
-  test_addLibraryImports_dart_noDirectives_hasComment() async {
+  Future<void> test_addLibraryImports_dart_noDirectives_hasComment() async {
     await resolveTestUnit('''
 /// Comment.
 
@@ -160,7 +160,7 @@
 ''');
   }
 
-  test_addLibraryImports_dart_noDirectives_hasShebang() async {
+  Future<void> test_addLibraryImports_dart_noDirectives_hasShebang() async {
     await resolveTestUnit('''
 #!/bin/dart
 
@@ -178,7 +178,7 @@
 ''');
   }
 
-  test_addLibraryImports_dart_noDirectives_noShebang() async {
+  Future<void> test_addLibraryImports_dart_noDirectives_noShebang() async {
     await resolveTestUnit('''
 class A {}
 ''');
@@ -192,7 +192,8 @@
 ''');
   }
 
-  test_addLibraryImports_package_hasDart_hasPackages_insertAfter() async {
+  Future<void>
+      test_addLibraryImports_package_hasDart_hasPackages_insertAfter() async {
     addPackageFile('aaa', 'aaa.dart', '');
     await resolveTestUnit('''
 import 'dart:async';
@@ -208,7 +209,8 @@
 ''');
   }
 
-  test_addLibraryImports_package_hasDart_hasPackages_insertBefore() async {
+  Future<void>
+      test_addLibraryImports_package_hasDart_hasPackages_insertBefore() async {
     addPackageFile('bbb', 'bbb.dart', '');
     await resolveTestUnit('''
 import 'dart:async';
@@ -224,7 +226,7 @@
 ''');
   }
 
-  test_addLibraryImports_package_hasImports_between() async {
+  Future<void> test_addLibraryImports_package_hasImports_between() async {
     addPackageFile('aaa', 'aaa.dart', '');
     addPackageFile('ddd', 'ddd.dart', '');
     await resolveTestUnit('''
@@ -241,7 +243,7 @@
 ''');
   }
 
-  test_invertCondition_binary_compare() async {
+  Future<void> test_invertCondition_binary_compare() async {
     await assert_invertCondition('0 < 1', '0 >= 1');
     await assert_invertCondition('0 > 1', '0 <= 1');
     await assert_invertCondition('0 <= 1', '0 > 1');
@@ -250,36 +252,36 @@
     await assert_invertCondition('0 != 1', '0 == 1');
   }
 
-  test_invertCondition_binary_compare_boolean() async {
+  Future<void> test_invertCondition_binary_compare_boolean() async {
     await assert_invertCondition('b1 == null', 'b1 != null');
     await assert_invertCondition('b1 != null', 'b1 == null');
   }
 
-  test_invertCondition_binary_logical() async {
+  Future<void> test_invertCondition_binary_logical() async {
     await assert_invertCondition('b1 && b2', '!b1 || !b2');
     await assert_invertCondition('!b1 && !b2', 'b1 || b2');
     await assert_invertCondition('b1 || b2', '!b1 && !b2');
     await assert_invertCondition('!b1 || !b2', 'b1 && b2');
   }
 
-  test_invertCondition_complex() async {
+  Future<void> test_invertCondition_complex() async {
     await assert_invertCondition('b1 && b2 || b3', '(!b1 || !b2) && !b3');
     await assert_invertCondition('b1 || b2 && b3', '!b1 && (!b2 || !b3)');
     await assert_invertCondition('(!b1 || !b2) && !b3', 'b1 && b2 || b3');
     await assert_invertCondition('!b1 && (!b2 || !b3)', 'b1 || b2 && b3');
   }
 
-  test_invertCondition_is() async {
+  Future<void> test_invertCondition_is() async {
     await assert_invertCondition('v1 is int', 'v1 is! int');
     await assert_invertCondition('v1 is! int', 'v1 is int');
   }
 
-  test_invertCondition_literal() async {
+  Future<void> test_invertCondition_literal() async {
     await assert_invertCondition('true', 'false');
     await assert_invertCondition('false', 'true');
   }
 
-  test_invertCondition_not() async {
+  Future<void> test_invertCondition_not() async {
     await assert_invertCondition('b1', '!b1');
     await assert_invertCondition('!b1', 'b1');
     await assert_invertCondition('!((b1))', 'b1');
@@ -317,5 +319,5 @@
   _SourceMock(this.fullName, this.uri);
 
   @override
-  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
diff --git a/pkg/analysis_server/test/services/linter/linter_test.dart b/pkg/analysis_server/test/services/linter/linter_test.dart
index 6ddf34a..1cc5461 100644
--- a/pkg/analysis_server/test/services/linter/linter_test.dart
+++ b/pkg/analysis_server/test/services/linter/linter_test.dart
@@ -12,7 +12,7 @@
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LinterRuleOptionsValidatorTest);
   });
@@ -28,7 +28,7 @@
 
   List<AnalysisError> get errors => recorder.errors;
 
-  setUp() {
+  void setUp() {
     registerLintRules();
     recorder = RecordingErrorListener();
     reporter = ErrorReporter(
@@ -38,7 +38,7 @@
     );
   }
 
-  test_linter_defined_rules() {
+  void test_linter_defined_rules() {
     validate('''
 linter:
   rules:
@@ -46,14 +46,14 @@
     ''', []);
   }
 
-  test_linter_no_rules() {
+  void test_linter_no_rules() {
     validate('''
 linter:
   rules:
     ''', []);
   }
 
-  test_linter_null_rule() {
+  void test_linter_null_rule() {
     validate('''
 linter:
   rules:
@@ -62,7 +62,7 @@
     ''', []);
   }
 
-  test_linter_undefined_rule() {
+  void test_linter_undefined_rule() {
     validate('''
 linter:
   rules:
@@ -70,7 +70,7 @@
     ''', [UNDEFINED_LINT_WARNING]);
   }
 
-  validate(String source, List<ErrorCode> expected) {
+  void validate(String source, List<ErrorCode> expected) {
     var options = optionsProvider.getOptionsFromString(source);
     validator.validate(reporter, options);
     expect(errors.map((AnalysisError e) => e.errorCode),
@@ -83,5 +83,5 @@
   String get fullName => '/package/lib/test.dart';
 
   @override
-  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
diff --git a/pkg/analysis_server/test/services/linter/test_all.dart b/pkg/analysis_server/test/services/linter/test_all.dart
index feb89d6..bfc8186 100644
--- a/pkg/analysis_server/test/services/linter/test_all.dart
+++ b/pkg/analysis_server/test/services/linter/test_all.dart
@@ -6,7 +6,7 @@
 
 import 'linter_test.dart' as linter_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     linter_test.main();
   }, name: 'linter');
diff --git a/pkg/analysis_server/test/services/refactoring/convert_getter_to_method_test.dart b/pkg/analysis_server/test/services/refactoring/convert_getter_to_method_test.dart
index 8761e0c..84fc2b4 100644
--- a/pkg/analysis_server/test/services/refactoring/convert_getter_to_method_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/convert_getter_to_method_test.dart
@@ -12,7 +12,7 @@
 
 import 'abstract_refactoring.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertGetterToMethodTest);
   });
@@ -23,7 +23,7 @@
   @override
   ConvertGetterToMethodRefactoring refactoring;
 
-  test_change_function() async {
+  Future<void> test_change_function() async {
     await indexTestUnit('''
 int get test => 42;
 main() {
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_change_method() async {
+  Future<void> test_change_method() async {
     await indexTestUnit('''
 class A {
   int get test => 1;
@@ -87,7 +87,7 @@
 ''');
   }
 
-  test_change_multipleFiles() async {
+  Future<void> test_change_multipleFiles() async {
     await indexUnit('/home/test/lib/other.dart', r'''
 class A {
   int get test => 1;
@@ -117,7 +117,7 @@
 ''');
   }
 
-  test_checkInitialConditions_syntheticGetter() async {
+  Future<void> test_checkInitialConditions_syntheticGetter() async {
     await indexTestUnit('''
 int test = 42;
 main() {
diff --git a/pkg/analysis_server/test/services/refactoring/convert_method_to_getter_test.dart b/pkg/analysis_server/test/services/refactoring/convert_method_to_getter_test.dart
index 6acd967..ee9378d 100644
--- a/pkg/analysis_server/test/services/refactoring/convert_method_to_getter_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/convert_method_to_getter_test.dart
@@ -14,7 +14,7 @@
 
 import 'abstract_refactoring.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertMethodToGetterTest);
   });
@@ -25,7 +25,7 @@
   @override
   ConvertMethodToGetterRefactoring refactoring;
 
-  test_change_function() async {
+  Future<void> test_change_function() async {
     await indexTestUnit('''
 int test() => 42;
 main() {
@@ -44,7 +44,7 @@
 ''');
   }
 
-  test_change_method() async {
+  Future<void> test_change_method() async {
     await indexTestUnit('''
 class A {
   int test() => 1;
@@ -89,7 +89,7 @@
 ''');
   }
 
-  test_change_multipleFiles() async {
+  Future<void> test_change_multipleFiles() async {
     await indexUnit('/home/test/lib/other.dart', r'''
 class A {
   int test() => 1;
@@ -119,7 +119,7 @@
 ''');
   }
 
-  test_checkInitialConditions_alreadyGetter() async {
+  Future<void> test_checkInitialConditions_alreadyGetter() async {
     await indexTestUnit('''
 int get test => 42;
 main() {
@@ -134,7 +134,7 @@
         'Only class methods or top-level functions can be converted to getters.');
   }
 
-  test_checkInitialConditions_hasParameters() async {
+  Future<void> test_checkInitialConditions_hasParameters() async {
     await indexTestUnit('''
 int test(x) => x * 2;
 main() {
@@ -147,7 +147,7 @@
         'Only methods without parameters can be converted to getters.');
   }
 
-  test_checkInitialConditions_localFunction() async {
+  Future<void> test_checkInitialConditions_localFunction() async {
     await indexTestUnit('''
 main() {
   test() {}
@@ -161,7 +161,7 @@
         'Only top-level functions can be converted to getters.');
   }
 
-  test_checkInitialConditions_notFunctionOrMethod() async {
+  Future<void> test_checkInitialConditions_notFunctionOrMethod() async {
     await indexTestUnit('''
 class A {
   A.test();
@@ -173,7 +173,7 @@
         'Only class methods or top-level functions can be converted to getters.');
   }
 
-  test_checkInitialConditions_returnTypeVoid() async {
+  Future<void> test_checkInitialConditions_returnTypeVoid() async {
     await indexTestUnit('''
 void test() {}
 ''');
diff --git a/pkg/analysis_server/test/services/refactoring/extract_local_test.dart b/pkg/analysis_server/test/services/refactoring/extract_local_test.dart
index 4790004..c027b46 100644
--- a/pkg/analysis_server/test/services/refactoring/extract_local_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/extract_local_test.dart
@@ -15,7 +15,7 @@
 
 import 'abstract_refactoring.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ExtractLocalTest);
   });
@@ -26,7 +26,7 @@
   @override
   ExtractLocalRefactoringImpl refactoring;
 
-  test_checkFinalConditions_sameVariable_after() async {
+  Future<void> test_checkFinalConditions_sameVariable_after() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -40,7 +40,7 @@
         expectedMessage: "The name 'res' is already used in the scope.");
   }
 
-  test_checkFinalConditions_sameVariable_before() async {
+  Future<void> test_checkFinalConditions_sameVariable_before() async {
     await indexTestUnit('''
 main() {
   var res;
@@ -54,7 +54,7 @@
         expectedMessage: "The name 'res' is already used in the scope.");
   }
 
-  test_checkInitialCondition_false_outOfRange_length() async {
+  Future<void> test_checkInitialCondition_false_outOfRange_length() async {
     await indexTestUnit('''
 main() {
   print(1 + 2);
@@ -65,7 +65,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL);
   }
 
-  test_checkInitialCondition_outOfRange_offset() async {
+  Future<void> test_checkInitialCondition_outOfRange_offset() async {
     await indexTestUnit('''
 main() {
   print(1 + 2);
@@ -76,7 +76,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL);
   }
 
-  test_checkInitialConditions_assignmentLeftHandSize() async {
+  Future<void> test_checkInitialConditions_assignmentLeftHandSize() async {
     await indexTestUnit('''
 main() {
   var v = 0;
@@ -90,7 +90,8 @@
         expectedMessage: 'Cannot extract the left-hand side of an assignment.');
   }
 
-  test_checkInitialConditions_namePartOfDeclaration_function() async {
+  Future<void>
+      test_checkInitialConditions_namePartOfDeclaration_function() async {
     await indexTestUnit('''
 void main() {
   void foo() {}
@@ -103,7 +104,8 @@
         expectedMessage: 'Cannot extract the name part of a declaration.');
   }
 
-  test_checkInitialConditions_namePartOfDeclaration_variable() async {
+  Future<void>
+      test_checkInitialConditions_namePartOfDeclaration_variable() async {
     await indexTestUnit('''
 main() {
   int vvv = 0;
@@ -116,7 +118,7 @@
         expectedMessage: 'Cannot extract the name part of a declaration.');
   }
 
-  test_checkInitialConditions_noExpression() async {
+  Future<void> test_checkInitialConditions_noExpression() async {
     await indexTestUnit('''
 main() {
   // abc
@@ -127,7 +129,7 @@
     await _assertInitialConditions_fatal_selection();
   }
 
-  test_checkInitialConditions_notPartOfFunction() async {
+  Future<void> test_checkInitialConditions_notPartOfFunction() async {
     await indexTestUnit('''
 int a = 1 + 2;
 ''');
@@ -139,7 +141,8 @@
             'to activate this refactoring.');
   }
 
-  test_checkInitialConditions_stringSelection_leadingQuote() async {
+  Future<void>
+      test_checkInitialConditions_stringSelection_leadingQuote() async {
     await indexTestUnit('''
 main() {
   var vvv = 'abc';
@@ -155,7 +158,8 @@
 ''');
   }
 
-  test_checkInitialConditions_stringSelection_trailingQuote() async {
+  Future<void>
+      test_checkInitialConditions_stringSelection_trailingQuote() async {
     await indexTestUnit('''
 main() {
   var vvv = 'abc';
@@ -171,7 +175,7 @@
 ''');
   }
 
-  test_checkInitialConditions_voidExpression() async {
+  Future<void> test_checkInitialConditions_voidExpression() async {
     await indexTestUnit('''
 main() {
   print(42);
@@ -184,7 +188,7 @@
         expectedMessage: 'Cannot extract the void expression.');
   }
 
-  test_checkName() async {
+  Future<void> test_checkName() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -207,7 +211,7 @@
     assertRefactoringStatusOK(refactoring.checkName());
   }
 
-  test_checkName_conflict_withInvokedFunction() async {
+  Future<void> test_checkName_conflict_withInvokedFunction() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -224,7 +228,7 @@
         expectedMessage: "The name 'res' is already used in the scope.");
   }
 
-  test_checkName_conflict_withOtherLocal() async {
+  Future<void> test_checkName_conflict_withOtherLocal() async {
     await indexTestUnit('''
 main() {
   var res;
@@ -239,7 +243,7 @@
         expectedMessage: "The name 'res' is already used in the scope.");
   }
 
-  test_checkName_conflict_withTypeName() async {
+  Future<void> test_checkName_conflict_withTypeName() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -256,7 +260,7 @@
         expectedMessage: "The name 'Res' is already used in the scope.");
   }
 
-  test_completeStatementExpression() async {
+  Future<void> test_completeStatementExpression() async {
     await indexTestUnit('''
 main(p) {
   p.toString();
@@ -271,7 +275,7 @@
 ''');
   }
 
-  test_const_argument_inConstInstanceCreation() async {
+  Future<void> test_const_argument_inConstInstanceCreation() async {
     await indexTestUnit('''
 class A {
   const A(int a, int b);
@@ -293,7 +297,7 @@
 ''');
   }
 
-  test_const_inList() async {
+  Future<void> test_const_inList() async {
     await indexTestUnit('''
 main() {
   const [1, 2];
@@ -309,7 +313,7 @@
 ''');
   }
 
-  test_const_inList_inBinaryExpression() async {
+  Future<void> test_const_inList_inBinaryExpression() async {
     await indexTestUnit('''
 main() {
   const [1 + 2, 3];
@@ -325,7 +329,7 @@
 ''');
   }
 
-  test_const_inList_inConditionalExpression() async {
+  Future<void> test_const_inList_inConditionalExpression() async {
     await indexTestUnit('''
 main() {
   const [true ? 1 : 2, 3];
@@ -341,7 +345,7 @@
 ''');
   }
 
-  test_const_inList_inParenthesis() async {
+  Future<void> test_const_inList_inParenthesis() async {
     await indexTestUnit('''
 main() {
   const [(1), 2];
@@ -357,7 +361,7 @@
 ''');
   }
 
-  test_const_inList_inPrefixExpression() async {
+  Future<void> test_const_inList_inPrefixExpression() async {
     await indexTestUnit('''
 main() {
   const [!true, 2];
@@ -373,7 +377,7 @@
 ''');
   }
 
-  test_const_inMap_key() async {
+  Future<void> test_const_inMap_key() async {
     await indexTestUnit('''
 main() {
   const {1: 2};
@@ -389,7 +393,7 @@
 ''');
   }
 
-  test_const_inMap_value() async {
+  Future<void> test_const_inMap_value() async {
     await indexTestUnit('''
 main() {
   const {1: 2};
@@ -405,7 +409,7 @@
 ''');
   }
 
-  test_coveringExpressions() async {
+  Future<void> test_coveringExpressions() async {
     await indexTestUnit('''
 main() {
   int aaa = 1;
@@ -421,7 +425,7 @@
         ['bbb', 'bbb * 2', 'aaa + bbb * 2', 'aaa + bbb * 2 + 3']);
   }
 
-  test_coveringExpressions_inArgumentList() async {
+  Future<void> test_coveringExpressions_inArgumentList() async {
     await indexTestUnit('''
 main() {
   foo(111 + 222);
@@ -435,7 +439,7 @@
     expect(subExpressions, ['111', '111 + 222', 'foo(111 + 222)']);
   }
 
-  test_coveringExpressions_inInvocationOfVoidFunction() async {
+  Future<void> test_coveringExpressions_inInvocationOfVoidFunction() async {
     await indexTestUnit('''
 main() {
   foo(111 + 222);
@@ -449,7 +453,7 @@
     expect(subExpressions, ['111', '111 + 222']);
   }
 
-  test_coveringExpressions_namedExpression_value() async {
+  Future<void> test_coveringExpressions_namedExpression_value() async {
     await indexTestUnit('''
 main() {
   foo(ppp: 42);
@@ -463,7 +467,7 @@
     expect(subExpressions, ['42', 'foo(ppp: 42)']);
   }
 
-  test_coveringExpressions_skip_assignment() async {
+  Future<void> test_coveringExpressions_skip_assignment() async {
     await indexTestUnit('''
 main() {
   int v;
@@ -478,7 +482,7 @@
     expect(subExpressions, ['111', '111 + 222', 'foo(v = 111 + 222)']);
   }
 
-  test_coveringExpressions_skip_constructorName() async {
+  Future<void> test_coveringExpressions_skip_constructorName() async {
     await indexTestUnit('''
 class AAA {
   AAA.name() {}
@@ -494,7 +498,7 @@
     expect(subExpressions, ['new AAA.name()']);
   }
 
-  test_coveringExpressions_skip_constructorName_name() async {
+  Future<void> test_coveringExpressions_skip_constructorName_name() async {
     await indexTestUnit('''
 class A {
   A.name() {}
@@ -510,7 +514,7 @@
     expect(subExpressions, ['new A.name()']);
   }
 
-  test_coveringExpressions_skip_constructorName_type() async {
+  Future<void> test_coveringExpressions_skip_constructorName_type() async {
     await indexTestUnit('''
 class A {}
 main() {
@@ -524,7 +528,8 @@
     expect(subExpressions, ['new A()']);
   }
 
-  test_coveringExpressions_skip_constructorName_typeArgument() async {
+  Future<void>
+      test_coveringExpressions_skip_constructorName_typeArgument() async {
     await indexTestUnit('''
 class A<T> {}
 main() {
@@ -538,7 +543,7 @@
     expect(subExpressions, ['new A<String>()']);
   }
 
-  test_coveringExpressions_skip_namedExpression() async {
+  Future<void> test_coveringExpressions_skip_namedExpression() async {
     await indexTestUnit('''
 main() {
   foo(ppp: 42);
@@ -552,7 +557,7 @@
     expect(subExpressions, ['foo(ppp: 42)']);
   }
 
-  test_fragmentExpression() async {
+  Future<void> test_fragmentExpression() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2 + 3 + 4;
@@ -568,7 +573,7 @@
 ''');
   }
 
-  test_fragmentExpression_leadingNotWhitespace() async {
+  Future<void> test_fragmentExpression_leadingNotWhitespace() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2 + 3 + 4;
@@ -584,7 +589,7 @@
 ''');
   }
 
-  test_fragmentExpression_leadingPartialSelection() async {
+  Future<void> test_fragmentExpression_leadingPartialSelection() async {
     await indexTestUnit('''
 main() {
   int a = 111 + 2 + 3 + 4;
@@ -600,7 +605,7 @@
 ''');
   }
 
-  test_fragmentExpression_leadingWhitespace() async {
+  Future<void> test_fragmentExpression_leadingWhitespace() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2 + 3 + 4;
@@ -616,7 +621,7 @@
 ''');
   }
 
-  test_fragmentExpression_notAssociativeOperator() async {
+  Future<void> test_fragmentExpression_notAssociativeOperator() async {
     await indexTestUnit('''
 main() {
   int a = 1 - 2 - 3 - 4;
@@ -632,7 +637,7 @@
 ''');
   }
 
-  test_fragmentExpression_trailingNotWhitespace() async {
+  Future<void> test_fragmentExpression_trailingNotWhitespace() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2 + 3 + 4;
@@ -648,7 +653,7 @@
 ''');
   }
 
-  test_fragmentExpression_trailingPartialSelection() async {
+  Future<void> test_fragmentExpression_trailingPartialSelection() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2 + 333 + 4;
@@ -664,7 +669,7 @@
 ''');
   }
 
-  test_fragmentExpression_trailingWhitespace() async {
+  Future<void> test_fragmentExpression_trailingWhitespace() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2 + 3 + 4;
@@ -680,7 +685,7 @@
 ''');
   }
 
-  test_guessNames_fragmentExpression() async {
+  Future<void> test_guessNames_fragmentExpression() async {
     await indexTestUnit('''
 main() {
   var a = 111 + 222 + 333 + 444;
@@ -692,7 +697,7 @@
     expect(refactoring.names, unorderedEquals(['i']));
   }
 
-  test_guessNames_singleExpression() async {
+  Future<void> test_guessNames_singleExpression() async {
     await indexTestUnit('''
 class TreeItem {}
 TreeItem getSelectedItem() => null;
@@ -708,7 +713,7 @@
         unorderedEquals(['selectedItem', 'item', 'my', 'treeItem']));
   }
 
-  test_guessNames_stringPart() async {
+  Future<void> test_guessNames_stringPart() async {
     await indexTestUnit('''
 main() {
   var s = 'Hello Bob... welcome to Dart!';
@@ -720,7 +725,7 @@
     expect(refactoring.names, unorderedEquals(['helloBob', 'bob']));
   }
 
-  test_isAvailable_false_notPartOfFunction() async {
+  Future<void> test_isAvailable_false_notPartOfFunction() async {
     await indexTestUnit('''
 var v = 1 + 2;
 ''');
@@ -728,7 +733,7 @@
     expect(refactoring.isAvailable(), isFalse);
   }
 
-  test_isAvailable_true() async {
+  Future<void> test_isAvailable_true() async {
     await indexTestUnit('''
 main() {
   print(1 + 2);
@@ -738,7 +743,7 @@
     expect(refactoring.isAvailable(), isTrue);
   }
 
-  test_lint_prefer_final_locals() async {
+  Future<void> test_lint_prefer_final_locals() async {
     createAnalysisOptionsFile(lints: [LintNames.prefer_final_locals]);
     await indexTestUnit('''
 main() {
@@ -755,7 +760,7 @@
 ''');
   }
 
-  test_occurrences_differentName_samePrefix() async {
+  Future<void> test_occurrences_differentName_samePrefix() async {
     await indexTestUnit('''
 void main(A a) {
   if (a.foo != 1) {
@@ -785,7 +790,7 @@
 ''');
   }
 
-  test_occurrences_differentVariable() async {
+  Future<void> test_occurrences_differentVariable() async {
     await indexTestUnit('''
 main() {
   {
@@ -819,7 +824,7 @@
         length: 3, offsets: [36, 59, 85], names: ['object', 'i']);
   }
 
-  test_occurrences_disableOccurrences() async {
+  Future<void> test_occurrences_disableOccurrences() async {
     await indexTestUnit('''
 int foo() => 42;
 main() {
@@ -840,7 +845,7 @@
 ''');
   }
 
-  test_occurrences_ignore_assignmentLeftHandSize() async {
+  Future<void> test_occurrences_ignore_assignmentLeftHandSize() async {
     await indexTestUnit('''
 main() {
   int v = 1;
@@ -864,7 +869,7 @@
 ''');
   }
 
-  test_occurrences_ignore_nameOfVariableDeclaration() async {
+  Future<void> test_occurrences_ignore_nameOfVariableDeclaration() async {
     await indexTestUnit('''
 main() {
   int v = 1;
@@ -882,7 +887,7 @@
 ''');
   }
 
-  test_occurrences_singleExpression() async {
+  Future<void> test_occurrences_singleExpression() async {
     await indexTestUnit('''
 int foo() => 42;
 main() {
@@ -902,7 +907,7 @@
 ''');
   }
 
-  test_occurrences_useDominator() async {
+  Future<void> test_occurrences_useDominator() async {
     await indexTestUnit('''
 main() {
   if (true) {
@@ -926,7 +931,7 @@
 ''');
   }
 
-  test_occurrences_whenComment() async {
+  Future<void> test_occurrences_whenComment() async {
     await indexTestUnit('''
 int foo() => 42;
 main() {
@@ -946,7 +951,7 @@
 ''');
   }
 
-  test_occurrences_withSpace() async {
+  Future<void> test_occurrences_withSpace() async {
     await indexTestUnit('''
 int foo(String s) => 42;
 main() {
@@ -966,7 +971,7 @@
 ''');
   }
 
-  test_offsets_lengths() async {
+  Future<void> test_offsets_lengths() async {
     await indexTestUnit('''
 int foo() => 42;
 main() {
@@ -982,7 +987,7 @@
     expect(refactoring.lengths, unorderedEquals([5, 6]));
   }
 
-  test_singleExpression() async {
+  Future<void> test_singleExpression() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -998,7 +1003,7 @@
 ''');
   }
 
-  test_singleExpression_getter() async {
+  Future<void> test_singleExpression_getter() async {
     await indexTestUnit('''
 class A {
   int get foo => 42;
@@ -1023,7 +1028,7 @@
   }
 
   @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/33992')
-  test_singleExpression_hasParseError_expectedSemicolon() async {
+  Future<void> test_singleExpression_hasParseError_expectedSemicolon() async {
     verifyNoTestUnitErrors = false;
     await indexTestUnit('''
 main(p) {
@@ -1042,7 +1047,7 @@
 ''');
   }
 
-  test_singleExpression_inExpressionBody_ofClosure() async {
+  Future<void> test_singleExpression_inExpressionBody_ofClosure() async {
     await indexTestUnit('''
 main() {
   print((x) => x.y * x.y + 1);
@@ -1062,7 +1067,7 @@
         length: 3, offsets: [31, 53, 59], names: ['y']);
   }
 
-  test_singleExpression_inExpressionBody_ofFunction() async {
+  Future<void> test_singleExpression_inExpressionBody_ofFunction() async {
     await indexTestUnit('''
 foo(Point p) => p.x * p.x + p.y * p.y;
 class Point {int x; int y;}
@@ -1080,7 +1085,7 @@
         length: 3, offsets: [21, 41, 47], names: ['x', 'i']);
   }
 
-  test_singleExpression_inExpressionBody_ofMethod() async {
+  Future<void> test_singleExpression_inExpressionBody_ofMethod() async {
     await indexTestUnit('''
 class A {
   foo(Point p) => p.x * p.x + p.y * p.y;
@@ -1102,7 +1107,7 @@
         length: 3, offsets: [35, 57, 63], names: ['x', 'i']);
   }
 
-  test_singleExpression_inIfElseIf() async {
+  Future<void> test_singleExpression_inIfElseIf() async {
     await indexTestUnit('''
 main(int p) {
   if (p == 1) {
@@ -1126,7 +1131,7 @@
 ''');
   }
 
-  test_singleExpression_inMethod() async {
+  Future<void> test_singleExpression_inMethod() async {
     await indexTestUnit('''
 class A {
   main() {
@@ -1146,7 +1151,7 @@
 ''');
   }
 
-  test_singleExpression_leadingNotWhitespace() async {
+  Future<void> test_singleExpression_leadingNotWhitespace() async {
     await indexTestUnit('''
 main() {
   int a = 12 + 345;
@@ -1162,7 +1167,7 @@
 ''');
   }
 
-  test_singleExpression_leadingWhitespace() async {
+  Future<void> test_singleExpression_leadingWhitespace() async {
     await indexTestUnit('''
 main() {
   int a = 1 /*abc*/ + 2 + 345;
@@ -1178,7 +1183,7 @@
 ''');
   }
 
-  test_singleExpression_methodName_reference() async {
+  Future<void> test_singleExpression_methodName_reference() async {
     await indexTestUnit('''
 main() {
   var v = foo().length;
@@ -1196,7 +1201,7 @@
 ''');
   }
 
-  test_singleExpression_nameOfProperty_prefixedIdentifier() async {
+  Future<void> test_singleExpression_nameOfProperty_prefixedIdentifier() async {
     await indexTestUnit('''
 main(p) {
   var v = p.value; // marker
@@ -1212,7 +1217,7 @@
 ''');
   }
 
-  test_singleExpression_nameOfProperty_propertyAccess() async {
+  Future<void> test_singleExpression_nameOfProperty_propertyAccess() async {
     await indexTestUnit('''
 main() {
   var v = foo().length; // marker
@@ -1235,7 +1240,7 @@
    * `1 + 2` will be a separate and complete binary expression, so it can be
    * handled as a single expression.
    */
-  test_singleExpression_partOfBinaryExpression() async {
+  Future<void> test_singleExpression_partOfBinaryExpression() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2 + 3 + 4;
@@ -1251,7 +1256,7 @@
 ''');
   }
 
-  test_singleExpression_string() async {
+  Future<void> test_singleExpression_string() async {
     await indexTestUnit('''
 void main() {
   print("1234");
@@ -1267,7 +1272,7 @@
 ''');
   }
 
-  test_singleExpression_trailingNotWhitespace() async {
+  Future<void> test_singleExpression_trailingNotWhitespace() async {
     await indexTestUnit('''
 main() {
   int a = 12 + 345;
@@ -1283,7 +1288,7 @@
 ''');
   }
 
-  test_singleExpression_trailingWhitespace() async {
+  Future<void> test_singleExpression_trailingWhitespace() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2 ;
@@ -1299,7 +1304,7 @@
 ''');
   }
 
-  test_stringLiteral_part() async {
+  Future<void> test_stringLiteral_part() async {
     await indexTestUnit('''
 main() {
   print('abcdefgh');
@@ -1316,7 +1321,7 @@
     _assertSingleLinkedEditGroup(length: 3, offsets: [15, 41], names: ['cde']);
   }
 
-  test_stringLiteral_whole() async {
+  Future<void> test_stringLiteral_whole() async {
     await indexTestUnit('''
 main() {
   print('abc');
@@ -1334,7 +1339,7 @@
         length: 3, offsets: [15, 36], names: ['object', 's']);
   }
 
-  test_stringLiteralPart() async {
+  Future<void> test_stringLiteralPart() async {
     await indexTestUnit(r'''
 main() {
   int x = 1;
diff --git a/pkg/analysis_server/test/services/refactoring/extract_method_test.dart b/pkg/analysis_server/test/services/refactoring/extract_method_test.dart
index 77be546..a6409cf 100644
--- a/pkg/analysis_server/test/services/refactoring/extract_method_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/extract_method_test.dart
@@ -13,7 +13,7 @@
 
 import 'abstract_refactoring.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ExtractMethodTest);
   });
@@ -24,7 +24,7 @@
   @override
   ExtractMethodRefactoringImpl refactoring;
 
-  test_bad_assignmentLeftHandSide() async {
+  Future<void> test_bad_assignmentLeftHandSide() async {
     await indexTestUnit('''
 main() {
   int aaa;
@@ -36,7 +36,7 @@
         'Cannot extract the left-hand side of an assignment.');
   }
 
-  test_bad_comment_selectionEndsInside() async {
+  Future<void> test_bad_comment_selectionEndsInside() async {
     await indexTestUnit('''
 main() {
 // start
@@ -50,7 +50,7 @@
     return _assertConditionsFatal('Selection ends inside a comment.');
   }
 
-  test_bad_comment_selectionStartsInside() async {
+  Future<void> test_bad_comment_selectionStartsInside() async {
     await indexTestUnit('''
 main() {
 /*
@@ -64,7 +64,7 @@
     return _assertConditionsFatal('Selection begins inside a comment.');
   }
 
-  test_bad_conflict_method_alreadyDeclaresMethod() async {
+  Future<void> test_bad_conflict_method_alreadyDeclaresMethod() async {
     await indexTestUnit('''
 class A {
   void res() {}
@@ -80,7 +80,7 @@
         "Class 'A' already declares method with name 'res'.");
   }
 
-  test_bad_conflict_method_shadowsSuperDeclaration() async {
+  Future<void> test_bad_conflict_method_shadowsSuperDeclaration() async {
     await indexTestUnit('''
 class A {
   void res() {} // marker
@@ -98,7 +98,7 @@
     return _assertConditionsError("Created method will shadow method 'A.res'.");
   }
 
-  test_bad_conflict_topLevel_alreadyDeclaresFunction() async {
+  Future<void> test_bad_conflict_topLevel_alreadyDeclaresFunction() async {
     await indexTestUnit('''
 library my.lib;
 
@@ -114,7 +114,7 @@
         "Library already declares function with name 'res'.");
   }
 
-  test_bad_conflict_topLevel_willHideInheritedMemberUsage() async {
+  Future<void> test_bad_conflict_topLevel_willHideInheritedMemberUsage() async {
     await indexTestUnit('''
 class A {
   void res() {}
@@ -135,7 +135,7 @@
         "Created function will shadow method 'A.res'.");
   }
 
-  test_bad_constructor_initializer() async {
+  Future<void> test_bad_constructor_initializer() async {
     await indexTestUnit('''
 class A {
   int f;
@@ -147,7 +147,7 @@
         'Cannot extract a constructor initializer. Select expression part of initializer.');
   }
 
-  test_bad_constructor_redirectingConstructor() async {
+  Future<void> test_bad_constructor_redirectingConstructor() async {
     await indexTestUnit('''
 class A {
   A() : this.named();
@@ -159,7 +159,7 @@
         'Cannot extract a constructor initializer. Select expression part of initializer.');
   }
 
-  test_bad_constructor_superConstructor() async {
+  Future<void> test_bad_constructor_superConstructor() async {
     await indexTestUnit('''
 class A {}
 class B extends A {
@@ -171,7 +171,7 @@
         'Cannot extract a constructor initializer. Select expression part of initializer.');
   }
 
-  test_bad_doWhile_body() async {
+  Future<void> test_bad_doWhile_body() async {
     await indexTestUnit('''
 main() {
   do
@@ -187,7 +187,7 @@
         "Operation not applicable to a 'do' statement's body and expression.");
   }
 
-  test_bad_emptySelection() async {
+  Future<void> test_bad_emptySelection() async {
     await indexTestUnit('''
 main() {
 // start
@@ -200,7 +200,7 @@
         'Can only extract a single expression or a set of statements.');
   }
 
-  test_bad_forLoop_conditionAndUpdaters() async {
+  Future<void> test_bad_forLoop_conditionAndUpdaters() async {
     await indexTestUnit('''
 main() {
   for (
@@ -217,7 +217,7 @@
         "Operation not applicable to a 'for' statement's condition and updaters.");
   }
 
-  test_bad_forLoop_init() async {
+  Future<void> test_bad_forLoop_init() async {
     await indexTestUnit('''
 main() {
   for (
@@ -234,7 +234,7 @@
         "Cannot extract initialization part of a 'for' statement.");
   }
 
-  test_bad_forLoop_initAndCondition() async {
+  Future<void> test_bad_forLoop_initAndCondition() async {
     await indexTestUnit('''
 main() {
   for (
@@ -251,7 +251,7 @@
         "Operation not applicable to a 'for' statement's initializer and condition.");
   }
 
-  test_bad_forLoop_updaters() async {
+  Future<void> test_bad_forLoop_updaters() async {
     await indexTestUnit('''
 main() {
   for (
@@ -268,7 +268,7 @@
         "Cannot extract increment part of a 'for' statement.");
   }
 
-  test_bad_forLoop_updatersAndBody() async {
+  Future<void> test_bad_forLoop_updatersAndBody() async {
     await indexTestUnit('''
 main() {
   for (
@@ -285,7 +285,7 @@
         'Not all selected statements are enclosed by the same parent statement.');
   }
 
-  test_bad_methodName_reference() async {
+  Future<void> test_bad_methodName_reference() async {
     await indexTestUnit('''
 main() {
   main();
@@ -295,7 +295,7 @@
     return _assertConditionsFatal('Cannot extract a single method name.');
   }
 
-  test_bad_namePartOfDeclaration_function() async {
+  Future<void> test_bad_namePartOfDeclaration_function() async {
     await indexTestUnit('''
 void main() {
 }
@@ -305,7 +305,7 @@
         'Cannot extract the name part of a declaration.');
   }
 
-  test_bad_namePartOfDeclaration_variable() async {
+  Future<void> test_bad_namePartOfDeclaration_variable() async {
     await indexTestUnit('''
 main() {
   int vvv = 0;
@@ -316,7 +316,7 @@
         'Cannot extract the name part of a declaration.');
   }
 
-  test_bad_namePartOfQualified() async {
+  Future<void> test_bad_namePartOfQualified() async {
     await indexTestUnit('''
 class A {
   var fff;
@@ -331,7 +331,7 @@
         'Can not extract name part of a property access.');
   }
 
-  test_bad_newMethodName_notIdentifier() async {
+  Future<void> test_bad_newMethodName_notIdentifier() async {
     await indexTestUnit('''
 main() {
 // start
@@ -345,7 +345,7 @@
     return _assertConditionsFatal("Method name must not contain '-'.");
   }
 
-  test_bad_notSameParent() async {
+  Future<void> test_bad_notSameParent() async {
     await indexTestUnit('''
 main() {
   while (false)
@@ -361,7 +361,7 @@
         'Not all selected statements are enclosed by the same parent statement.');
   }
 
-  test_bad_parameterName_duplicate() async {
+  Future<void> test_bad_parameterName_duplicate() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -384,7 +384,7 @@
     return _assertFinalConditionsError("Parameter 'dup' already exists");
   }
 
-  test_bad_parameterName_inUse_function() async {
+  Future<void> test_bad_parameterName_inUse_function() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -408,7 +408,7 @@
         "'f' is already used as a name in the selected code");
   }
 
-  test_bad_parameterName_inUse_localVariable() async {
+  Future<void> test_bad_parameterName_inUse_localVariable() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -431,7 +431,7 @@
         "'a' is already used as a name in the selected code");
   }
 
-  test_bad_parameterName_inUse_method() async {
+  Future<void> test_bad_parameterName_inUse_method() async {
     await indexTestUnit('''
 class A {
   main() {
@@ -457,7 +457,7 @@
         "'m' is already used as a name in the selected code");
   }
 
-  test_bad_selectionEndsInSomeNode() async {
+  Future<void> test_bad_selectionEndsInSomeNode() async {
     await indexTestUnit('''
 main() {
 // start
@@ -472,7 +472,7 @@
         'Extend selection to a valid range.');
   }
 
-  test_bad_statements_exit_notAllExecutionFlows() async {
+  Future<void> test_bad_statements_exit_notAllExecutionFlows() async {
     await indexTestUnit('''
 main(int p) {
 // start
@@ -487,7 +487,7 @@
     return _assertConditionsError(ExtractMethodRefactoringImpl.ERROR_EXITS);
   }
 
-  test_bad_statements_return_andAssignsVariable() async {
+  Future<void> test_bad_statements_return_andAssignsVariable() async {
     await indexTestUnit('''
 main() {
 // start
@@ -503,7 +503,7 @@
         'local variables and return statement.');
   }
 
-  test_bad_switchCase() async {
+  Future<void> test_bad_switchCase() async {
     await indexTestUnit('''
 main() {
   switch (1) {
@@ -519,7 +519,7 @@
         'or parts of a single case block.');
   }
 
-  test_bad_tokensBetweenLastNodeAndSelectionEnd() async {
+  Future<void> test_bad_tokensBetweenLastNodeAndSelectionEnd() async {
     await indexTestUnit('''
 main() {
 // start
@@ -533,7 +533,7 @@
         'The end of the selection contains characters that do not belong to a statement.');
   }
 
-  test_bad_tokensBetweenSelectionStartAndFirstNode() async {
+  Future<void> test_bad_tokensBetweenSelectionStartAndFirstNode() async {
     await indexTestUnit('''
 main() {
 // start
@@ -547,7 +547,7 @@
         'The beginning of the selection contains characters that do not belong to a statement.');
   }
 
-  test_bad_try_catchBlock_block() async {
+  Future<void> test_bad_try_catchBlock_block() async {
     await indexTestUnit('''
 main() {
   try
@@ -564,7 +564,7 @@
         'parts of try, catch, or finally block.');
   }
 
-  test_bad_try_catchBlock_complete() async {
+  Future<void> test_bad_try_catchBlock_complete() async {
     await indexTestUnit('''
 main() {
   try
@@ -581,7 +581,7 @@
         'parts of try, catch, or finally block.');
   }
 
-  test_bad_try_catchBlock_exception() async {
+  Future<void> test_bad_try_catchBlock_exception() async {
     await indexTestUnit('''
 main() {
   try {
@@ -598,7 +598,7 @@
         'Cannot extract the name part of a declaration.');
   }
 
-  test_bad_try_finallyBlock() async {
+  Future<void> test_bad_try_finallyBlock() async {
     await indexTestUnit('''
 main() {
   try
@@ -615,7 +615,7 @@
         'parts of try, catch, or finally block.');
   }
 
-  test_bad_try_tryBlock() async {
+  Future<void> test_bad_try_tryBlock() async {
     await indexTestUnit('''
 main() {
   try
@@ -632,7 +632,7 @@
         'parts of try, catch, or finally block.');
   }
 
-  test_bad_typeReference() async {
+  Future<void> test_bad_typeReference() async {
     await indexTestUnit('''
 main() {
   int a = 0;
@@ -642,7 +642,7 @@
     return _assertConditionsFatal('Cannot extract a single type reference.');
   }
 
-  test_bad_variableDeclarationFragment() async {
+  Future<void> test_bad_variableDeclarationFragment() async {
     await indexTestUnit('''
 main() {
   int
@@ -657,7 +657,7 @@
         'Cannot extract a variable declaration fragment. Select whole declaration statement.');
   }
 
-  test_bad_while_conditionAndBody() async {
+  Future<void> test_bad_while_conditionAndBody() async {
     await indexTestUnit('''
 main() {
   while
@@ -673,7 +673,7 @@
         "Operation not applicable to a while statement's expression and body.");
   }
 
-  test_canExtractGetter_false_closure() async {
+  Future<void> test_canExtractGetter_false_closure() async {
     await indexTestUnit('''
 main() {
   useFunction((_) => true);
@@ -687,7 +687,7 @@
     expect(refactoring.createGetter, false);
   }
 
-  test_canExtractGetter_false_fieldAssignment() async {
+  Future<void> test_canExtractGetter_false_fieldAssignment() async {
     await indexTestUnit('''
 class A {
   var f;
@@ -705,7 +705,7 @@
     expect(refactoring.createGetter, false);
   }
 
-  test_canExtractGetter_false_hasParameters() async {
+  Future<void> test_canExtractGetter_false_hasParameters() async {
     await indexTestUnit('''
 main(int p) {
   int a = p + 1;
@@ -718,7 +718,7 @@
     expect(refactoring.createGetter, false);
   }
 
-  test_canExtractGetter_false_returnNotUsed_assignment() async {
+  Future<void> test_canExtractGetter_false_returnNotUsed_assignment() async {
     await indexTestUnit('''
 var topVar = 0;
 f(int p) {
@@ -732,7 +732,7 @@
     expect(refactoring.createGetter, false);
   }
 
-  test_canExtractGetter_false_returnNotUsed_noReturn() async {
+  Future<void> test_canExtractGetter_false_returnNotUsed_noReturn() async {
     await indexTestUnit('''
 var topVar = 0;
 main() {
@@ -750,7 +750,7 @@
     expect(refactoring.createGetter, false);
   }
 
-  test_canExtractGetter_true() async {
+  Future<void> test_canExtractGetter_true() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -763,7 +763,7 @@
     expect(refactoring.createGetter, true);
   }
 
-  test_checkInitialCondition_false_outOfRange_length() async {
+  Future<void> test_checkInitialCondition_false_outOfRange_length() async {
     await indexTestUnit('''
 main() {
   1 + 2;
@@ -774,7 +774,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL);
   }
 
-  test_checkInitialCondition_outOfRange_offset() async {
+  Future<void> test_checkInitialCondition_outOfRange_offset() async {
     await indexTestUnit('''
 main() {
   1 + 2;
@@ -785,7 +785,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL);
   }
 
-  test_checkName() async {
+  Future<void> test_checkName() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -823,7 +823,7 @@
     assertRefactoringStatusOK(refactoring.checkName());
   }
 
-  test_closure_asFunction_singleExpression() async {
+  Future<void> test_closure_asFunction_singleExpression() async {
     await indexTestUnit('''
 process(f(x)) {}
 main() {
@@ -842,7 +842,7 @@
 ''');
   }
 
-  test_closure_asFunction_statements() async {
+  Future<void> test_closure_asFunction_statements() async {
     await indexTestUnit('''
 process(f(x)) {}
 main() {
@@ -867,7 +867,7 @@
 ''');
   }
 
-  test_closure_asMethod_statements() async {
+  Future<void> test_closure_asMethod_statements() async {
     await indexTestUnit('''
 process(f(x)) {}
 class A {
@@ -898,7 +898,7 @@
 ''');
   }
 
-  test_closure_atArgumentName() async {
+  Future<void> test_closure_atArgumentName() async {
     await indexTestUnit('''
 void process({int fff(int x)}) {}
 class C {
@@ -921,7 +921,7 @@
 ''');
   }
 
-  test_closure_atParameters() async {
+  Future<void> test_closure_atParameters() async {
     await indexTestUnit('''
 void process(num f(int x)) {}
 class C {
@@ -944,7 +944,7 @@
 ''');
   }
 
-  test_closure_bad_referencesLocalVariable() async {
+  Future<void> test_closure_bad_referencesLocalVariable() async {
     await indexTestUnit('''
 process(f(x)) {}
 main() {
@@ -960,7 +960,7 @@
             'Cannot extract closure as method, it references 1 external variable(s).');
   }
 
-  test_closure_bad_referencesParameter() async {
+  Future<void> test_closure_bad_referencesParameter() async {
     await indexTestUnit('''
 process(f(x)) {}
 main(int k) {
@@ -975,7 +975,7 @@
             'Cannot extract closure as method, it references 1 external variable(s).');
   }
 
-  test_fromTopLevelVariableInitializerClosure() async {
+  Future<void> test_fromTopLevelVariableInitializerClosure() async {
     await indexTestUnit('''
 var X = 1;
 
@@ -996,7 +996,7 @@
 ''');
   }
 
-  test_getExtractGetter_expression_true_binaryExpression() async {
+  Future<void> test_getExtractGetter_expression_true_binaryExpression() async {
     await indexTestUnit('''
 main() {
   print(1 + 2);
@@ -1008,7 +1008,7 @@
     expect(refactoring.createGetter, true);
   }
 
-  test_getExtractGetter_expression_true_literal() async {
+  Future<void> test_getExtractGetter_expression_true_literal() async {
     await indexTestUnit('''
 main() {
   print(42);
@@ -1020,7 +1020,8 @@
     expect(refactoring.createGetter, true);
   }
 
-  test_getExtractGetter_expression_true_prefixedExpression() async {
+  Future<void>
+      test_getExtractGetter_expression_true_prefixedExpression() async {
     await indexTestUnit('''
 main() {
   print(!true);
@@ -1032,7 +1033,8 @@
     expect(refactoring.createGetter, true);
   }
 
-  test_getExtractGetter_expression_true_prefixedIdentifier() async {
+  Future<void>
+      test_getExtractGetter_expression_true_prefixedIdentifier() async {
     await indexTestUnit('''
 main() {
   print(myValue.isEven);
@@ -1045,7 +1047,7 @@
     expect(refactoring.createGetter, true);
   }
 
-  test_getExtractGetter_expression_true_propertyAccess() async {
+  Future<void> test_getExtractGetter_expression_true_propertyAccess() async {
     await indexTestUnit('''
 main() {
   print(1.isEven);
@@ -1057,7 +1059,7 @@
     expect(refactoring.createGetter, true);
   }
 
-  test_getExtractGetter_statements() async {
+  Future<void> test_getExtractGetter_statements() async {
     await indexTestUnit('''
 main() {
 // start
@@ -1072,7 +1074,7 @@
     expect(refactoring.createGetter, false);
   }
 
-  test_getRefactoringName_function() async {
+  Future<void> test_getRefactoringName_function() async {
     await indexTestUnit('''
 main() {
   print(1 + 2);
@@ -1082,7 +1084,7 @@
     expect(refactoring.refactoringName, 'Extract Function');
   }
 
-  test_getRefactoringName_method() async {
+  Future<void> test_getRefactoringName_method() async {
     await indexTestUnit('''
 class A {
   main() {
@@ -1094,7 +1096,7 @@
     expect(refactoring.refactoringName, 'Extract Method');
   }
 
-  test_isAvailable_false_functionName() async {
+  Future<void> test_isAvailable_false_functionName() async {
     await indexTestUnit('''
 void main() {}
 ''');
@@ -1102,7 +1104,7 @@
     expect(refactoring.isAvailable(), isFalse);
   }
 
-  test_isAvailable_true() async {
+  Future<void> test_isAvailable_true() async {
     await indexTestUnit('''
 main() {
   1 + 2;
@@ -1112,7 +1114,7 @@
     expect(refactoring.isAvailable(), isTrue);
   }
 
-  test_names_singleExpression() async {
+  Future<void> test_names_singleExpression() async {
     await indexTestUnit('''
 class TreeItem {}
 TreeItem getSelectedItem() => null;
@@ -1129,7 +1131,7 @@
         unorderedEquals(['selectedItem', 'item', 'my', 'treeItem2']));
   }
 
-  test_offsets_lengths() async {
+  Future<void> test_offsets_lengths() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -1144,7 +1146,7 @@
     expect(refactoring.lengths, unorderedEquals([5, 6]));
   }
 
-  test_returnType_closure() async {
+  Future<void> test_returnType_closure() async {
     await indexTestUnit('''
 process(f(x)) {}
 main() {
@@ -1157,7 +1159,7 @@
     expect(refactoring.returnType, '');
   }
 
-  test_returnType_expression() async {
+  Future<void> test_returnType_expression() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -1169,7 +1171,7 @@
     expect(refactoring.returnType, 'int');
   }
 
-  test_returnType_mixInterfaceFunction() async {
+  Future<void> test_returnType_mixInterfaceFunction() async {
     await indexTestUnit('''
 main() {
 // start
@@ -1187,7 +1189,7 @@
     expect(refactoring.returnType, 'Object');
   }
 
-  test_returnType_statements() async {
+  Future<void> test_returnType_statements() async {
     await indexTestUnit('''
 main() {
 // start
@@ -1202,7 +1204,7 @@
     expect(refactoring.returnType, 'double');
   }
 
-  test_returnType_statements_nullMix() async {
+  Future<void> test_returnType_statements_nullMix() async {
     await indexTestUnit('''
 main(bool p) {
 // start
@@ -1219,7 +1221,7 @@
     expect(refactoring.returnType, 'int');
   }
 
-  test_returnType_statements_void() async {
+  Future<void> test_returnType_statements_void() async {
     await indexTestUnit('''
 main() {
 // start
@@ -1233,7 +1235,7 @@
     expect(refactoring.returnType, 'void');
   }
 
-  test_setExtractGetter() async {
+  Future<void> test_setExtractGetter() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -1254,7 +1256,7 @@
 ''');
   }
 
-  test_singleExpression() async {
+  Future<void> test_singleExpression() async {
     await indexTestUnit('''
 main() {
   int a = 1 + 2;
@@ -1271,7 +1273,7 @@
 ''');
   }
 
-  test_singleExpression_cascade() async {
+  Future<void> test_singleExpression_cascade() async {
     await indexTestUnit('''
 main() {
   String s = '';
@@ -1290,7 +1292,7 @@
 ''');
   }
 
-  test_singleExpression_coveringExpression() async {
+  Future<void> test_singleExpression_coveringExpression() async {
     await indexTestUnit('''
 main(int n) {
   var v = new FooBar(n);
@@ -1314,7 +1316,7 @@
 ''');
   }
 
-  test_singleExpression_dynamic() async {
+  Future<void> test_singleExpression_dynamic() async {
     await indexTestUnit('''
 dynaFunction() {}
 main() {
@@ -1333,7 +1335,7 @@
 ''');
   }
 
-  test_singleExpression_hasAwait() async {
+  Future<void> test_singleExpression_hasAwait() async {
     await indexTestUnit('''
 import 'dart:async';
 Future<int> getValue() async => 42;
@@ -1356,7 +1358,7 @@
 ''');
   }
 
-  test_singleExpression_ignore_assignmentLeftHandSize() async {
+  Future<void> test_singleExpression_ignore_assignmentLeftHandSize() async {
     await indexTestUnit('''
 main() {
   getButton().text = 'txt';
@@ -1377,7 +1379,7 @@
 ''');
   }
 
-  test_singleExpression_occurrences() async {
+  Future<void> test_singleExpression_occurrences() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -1414,7 +1416,7 @@
 ''');
   }
 
-  test_singleExpression_occurrences_disabled() async {
+  Future<void> test_singleExpression_occurrences_disabled() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -1440,7 +1442,7 @@
 ''');
   }
 
-  test_singleExpression_occurrences_inClassOnly() async {
+  Future<void> test_singleExpression_occurrences_inClassOnly() async {
     await indexTestUnit('''
 class A {
   myMethod() {
@@ -1475,7 +1477,7 @@
 ''');
   }
 
-  test_singleExpression_occurrences_incompatibleTypes() async {
+  Future<void> test_singleExpression_occurrences_incompatibleTypes() async {
     await indexTestUnit('''
 main() {
   int x = 1;
@@ -1498,7 +1500,7 @@
 ''');
   }
 
-  test_singleExpression_occurrences_inWholeUnit() async {
+  Future<void> test_singleExpression_occurrences_inWholeUnit() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -1533,7 +1535,7 @@
 ''');
   }
 
-  test_singleExpression_parameter_functionTypeAlias() async {
+  Future<void> test_singleExpression_parameter_functionTypeAlias() async {
     await indexTestUnit('''
 typedef R Foo<S, R>(S s);
 void main(Foo<String, int> foo, String s) {
@@ -1552,7 +1554,7 @@
 ''');
   }
 
-  test_singleExpression_returnType_importLibrary() async {
+  Future<void> test_singleExpression_returnType_importLibrary() async {
     _addLibraryReturningAsync();
     await indexTestUnit('''
 import 'asyncLib.dart';
@@ -1573,7 +1575,7 @@
 ''');
   }
 
-  test_singleExpression_returnTypeGeneric() async {
+  Future<void> test_singleExpression_returnTypeGeneric() async {
     await indexTestUnit('''
 main() {
   var v = new List<String>();
@@ -1590,7 +1592,7 @@
 ''');
   }
 
-  test_singleExpression_returnTypePrefix() async {
+  Future<void> test_singleExpression_returnTypePrefix() async {
     await indexTestUnit('''
 import 'dart:math' as pref;
 main() {
@@ -1609,7 +1611,8 @@
 ''');
   }
 
-  test_singleExpression_staticContext_extractFromInitializer() async {
+  Future<void>
+      test_singleExpression_staticContext_extractFromInitializer() async {
     await indexTestUnit('''
 class A {
   A(int v) {}
@@ -1632,7 +1635,7 @@
 ''');
   }
 
-  test_singleExpression_staticContext_extractFromInstance() async {
+  Future<void> test_singleExpression_staticContext_extractFromInstance() async {
     await indexTestUnit('''
 class A {
   instanceMethodA() {
@@ -1677,7 +1680,7 @@
 ''');
   }
 
-  test_singleExpression_staticContext_extractFromStatic() async {
+  Future<void> test_singleExpression_staticContext_extractFromStatic() async {
     await indexTestUnit('''
 class A {
   static staticMethodA() {
@@ -1722,7 +1725,7 @@
 ''');
   }
 
-  test_singleExpression_staticContext_hasInInitializer() async {
+  Future<void> test_singleExpression_staticContext_hasInInitializer() async {
     await indexTestUnit('''
 class A {
   A(int v) {}
@@ -1751,7 +1754,7 @@
 ''');
   }
 
-  test_singleExpression_usesParameter() async {
+  Future<void> test_singleExpression_usesParameter() async {
     await indexTestUnit('''
 fooA(int a1) {
   int a2 = 2;
@@ -1778,7 +1781,7 @@
 ''');
   }
 
-  test_singleExpression_withVariables() async {
+  Future<void> test_singleExpression_withVariables() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -1799,7 +1802,7 @@
 ''');
   }
 
-  test_singleExpression_withVariables_doRename() async {
+  Future<void> test_singleExpression_withVariables_doRename() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -1836,7 +1839,7 @@
 ''');
   }
 
-  test_singleExpression_withVariables_doReorder() async {
+  Future<void> test_singleExpression_withVariables_doReorder() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -1873,7 +1876,7 @@
 ''');
   }
 
-  test_singleExpression_withVariables_namedExpression() async {
+  Future<void> test_singleExpression_withVariables_namedExpression() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -1896,7 +1899,7 @@
 ''');
   }
 
-  test_singleExpression_withVariables_newType() async {
+  Future<void> test_singleExpression_withVariables_newType() async {
     await indexTestUnit('''
 main() {
   int v1 = 1;
@@ -1933,7 +1936,7 @@
 ''');
   }
 
-  test_singleExpression_withVariables_useBestType() async {
+  Future<void> test_singleExpression_withVariables_useBestType() async {
     await indexTestUnit('''
 main() {
   var v1 = 1;
@@ -1954,7 +1957,7 @@
 ''');
   }
 
-  test_statements_assignment() async {
+  Future<void> test_statements_assignment() async {
     await indexTestUnit('''
 main() {
   int v;
@@ -1982,7 +1985,7 @@
 ''');
   }
 
-  test_statements_changeIndentation() async {
+  Future<void> test_statements_changeIndentation() async {
     await indexTestUnit('''
 main() {
   {
@@ -2013,7 +2016,7 @@
 ''');
   }
 
-  test_statements_changeIndentation_multilineString() async {
+  Future<void> test_statements_changeIndentation_multilineString() async {
     await indexTestUnit('''
 main() {
   {
@@ -2046,7 +2049,7 @@
 ''');
   }
 
-  test_statements_definesVariable_notUsedOutside() async {
+  Future<void> test_statements_definesVariable_notUsedOutside() async {
     await indexTestUnit('''
 main() {
   int a = 1;
@@ -2075,7 +2078,8 @@
 ''');
   }
 
-  test_statements_definesVariable_oneUsedOutside_assignment() async {
+  Future<void>
+      test_statements_definesVariable_oneUsedOutside_assignment() async {
     await indexTestUnit('''
 myFunctionA() {
   int a = 1;
@@ -2113,7 +2117,8 @@
 ''');
   }
 
-  test_statements_definesVariable_oneUsedOutside_declaration() async {
+  Future<void>
+      test_statements_definesVariable_oneUsedOutside_declaration() async {
     await indexTestUnit('''
 myFunctionA() {
   int a = 1;
@@ -2155,7 +2160,7 @@
 ''');
   }
 
-  test_statements_definesVariable_twoUsedOutside() async {
+  Future<void> test_statements_definesVariable_twoUsedOutside() async {
     await indexTestUnit('''
 main() {
 // start
@@ -2171,7 +2176,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL);
   }
 
-  test_statements_duplicate_absolutelySame() async {
+  Future<void> test_statements_duplicate_absolutelySame() async {
     await indexTestUnit('''
 myFunctionA() {
   print(0);
@@ -2203,7 +2208,8 @@
 ''');
   }
 
-  test_statements_duplicate_declaresDifferentlyNamedVariable() async {
+  Future<void>
+      test_statements_duplicate_declaresDifferentlyNamedVariable() async {
     await indexTestUnit('''
 myFunctionA() {
   int varA = 1;
@@ -2235,7 +2241,7 @@
 ''');
   }
 
-  test_statements_dynamic() async {
+  Future<void> test_statements_dynamic() async {
     await indexTestUnit('''
 dynaFunction(p) => 0;
 main() {
@@ -2268,7 +2274,7 @@
   /**
    * We should always add ";" when invoke method with extracted statements.
    */
-  test_statements_endsWithBlock() async {
+  Future<void> test_statements_endsWithBlock() async {
     await indexTestUnit('''
 main() {
 // start
@@ -2295,7 +2301,7 @@
 ''');
   }
 
-  test_statements_exit_throws() async {
+  Future<void> test_statements_exit_throws() async {
     await indexTestUnit('''
 main(int p) {
 // start
@@ -2310,7 +2316,7 @@
     await assertRefactoringConditionsOK();
   }
 
-  test_statements_hasAwait_dynamicReturnType() async {
+  Future<void> test_statements_hasAwait_dynamicReturnType() async {
     await indexTestUnit('''
 import 'dart:async';
 Future getValue() async => 42;
@@ -2340,7 +2346,7 @@
 ''');
   }
 
-  test_statements_hasAwait_expression() async {
+  Future<void> test_statements_hasAwait_expression() async {
     await indexTestUnit('''
 import 'dart:async';
 Future<int> getValue() async => 42;
@@ -2372,7 +2378,7 @@
 ''');
   }
 
-  test_statements_hasAwait_forEach() async {
+  Future<void> test_statements_hasAwait_forEach() async {
     await indexTestUnit('''
 import 'dart:async';
 Stream<int> getValueStream() => null;
@@ -2408,7 +2414,7 @@
 ''');
   }
 
-  test_statements_hasAwait_voidReturnType() async {
+  Future<void> test_statements_hasAwait_voidReturnType() async {
     await indexTestUnit('''
 import 'dart:async';
 Future<int> getValue() async => 42;
@@ -2437,7 +2443,7 @@
 ''');
   }
 
-  test_statements_inSwitchMember() async {
+  Future<void> test_statements_inSwitchMember() async {
     await indexTestUnit('''
 class A {
   foo(int p) {
@@ -2476,7 +2482,7 @@
 ''');
   }
 
-  test_statements_method() async {
+  Future<void> test_statements_method() async {
     await indexTestUnit('''
 class A {
   foo() {
@@ -2503,7 +2509,7 @@
 ''');
   }
 
-  test_statements_noDuplicates() async {
+  Future<void> test_statements_noDuplicates() async {
     await indexTestUnit('''
 main() {
   int a = 1;
@@ -2530,7 +2536,7 @@
 ''');
   }
 
-  test_statements_parameters_ignoreInnerPropagatedType() async {
+  Future<void> test_statements_parameters_ignoreInnerPropagatedType() async {
     await indexTestUnit('''
 main(Object x) {
 // start
@@ -2563,7 +2569,7 @@
 ''');
   }
 
-  test_statements_parameters_importType() async {
+  Future<void> test_statements_parameters_importType() async {
     _addLibraryReturningAsync();
     await indexTestUnit('''
 import 'asyncLib.dart';
@@ -2592,7 +2598,7 @@
 ''');
   }
 
-  test_statements_parameters_localFunction() async {
+  Future<void> test_statements_parameters_localFunction() async {
     await indexTestUnit('''
 class C {
   int f(int a) {
@@ -2626,7 +2632,7 @@
 }''');
   }
 
-  test_statements_parameters_noLocalVariableConflict() async {
+  Future<void> test_statements_parameters_noLocalVariableConflict() async {
     await indexTestUnit('''
 int f(int x) {
   int y = x + 1;
@@ -2644,7 +2650,7 @@
     await assertRefactoringConditionsOK();
   }
 
-  test_statements_return_last() async {
+  Future<void> test_statements_return_last() async {
     await indexTestUnit('''
 main() {
 // start
@@ -2669,7 +2675,7 @@
 ''');
   }
 
-  test_statements_return_multiple_ifElse() async {
+  Future<void> test_statements_return_multiple_ifElse() async {
     await indexTestUnit('''
 num main(bool b) {
 // start
@@ -2700,7 +2706,7 @@
 ''');
   }
 
-  test_statements_return_multiple_ifThen() async {
+  Future<void> test_statements_return_multiple_ifThen() async {
     await indexTestUnit('''
 num main(bool b) {
 // start
@@ -2729,7 +2735,7 @@
 ''');
   }
 
-  test_statements_return_multiple_ignoreInFunction() async {
+  Future<void> test_statements_return_multiple_ignoreInFunction() async {
     await indexTestUnit('''
 int main() {
 // start
@@ -2758,7 +2764,7 @@
 ''');
   }
 
-  test_statements_return_multiple_interfaceFunction() async {
+  Future<void> test_statements_return_multiple_interfaceFunction() async {
     await indexTestUnit('''
 main(bool b) {
 // start
@@ -2787,7 +2793,8 @@
 ''');
   }
 
-  test_statements_return_multiple_sameElementDifferentTypeArgs() async {
+  Future<void>
+      test_statements_return_multiple_sameElementDifferentTypeArgs() async {
     await indexTestUnit('''
 main(bool b) {
 // start
@@ -2822,7 +2829,7 @@
 ''');
   }
 
-  test_statements_return_single() async {
+  Future<void> test_statements_return_single() async {
     await indexTestUnit('''
 main() {
 // start
@@ -2849,7 +2856,7 @@
    * We have 3 identical statements, but select only 2.
    * This should not cause problems.
    */
-  test_statements_twoOfThree() async {
+  Future<void> test_statements_twoOfThree() async {
     await indexTestUnit('''
 main() {
 // start
diff --git a/pkg/analysis_server/test/services/refactoring/extract_widget_test.dart b/pkg/analysis_server/test/services/refactoring/extract_widget_test.dart
index cc04abd..7212255 100644
--- a/pkg/analysis_server/test/services/refactoring/extract_widget_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/extract_widget_test.dart
@@ -13,7 +13,7 @@
 
 import 'abstract_refactoring.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ExtractWidgetTest);
   });
@@ -24,7 +24,7 @@
   @override
   ExtractWidgetRefactoringImpl refactoring;
 
-  test_checkAllConditions_selection() async {
+  Future<void> test_checkAllConditions_selection() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -36,7 +36,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL);
   }
 
-  test_checkName() async {
+  Future<void> test_checkName() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -67,7 +67,7 @@
     assertRefactoringStatusOK(refactoring.checkName());
   }
 
-  test_checkName_alreadyDeclared() async {
+  Future<void> test_checkName_alreadyDeclared() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -89,7 +89,7 @@
         expectedMessage: "Library already declares class with name 'Test'.");
   }
 
-  test_expression() async {
+  Future<void> test_expression() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -148,7 +148,7 @@
 ''');
   }
 
-  test_expression_localFunction() async {
+  Future<void> test_expression_localFunction() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -195,7 +195,7 @@
 ''');
   }
 
-  test_expression_onTypeName() async {
+  Future<void> test_expression_onTypeName() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -232,7 +232,7 @@
 ''');
   }
 
-  test_expression_selection() async {
+  Future<void> test_expression_selection() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -280,7 +280,7 @@
     await assertResult('return new Container();');
   }
 
-  test_expression_topFunction() async {
+  Future<void> test_expression_topFunction() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -321,7 +321,7 @@
 ''');
   }
 
-  test_invocation_enclosingClass() async {
+  Future<void> test_invocation_enclosingClass() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -346,7 +346,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.ERROR);
   }
 
-  test_invocation_enclosingSuperClass() async {
+  Future<void> test_invocation_enclosingSuperClass() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -373,7 +373,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.ERROR);
   }
 
-  test_invocation_otherClass() async {
+  Future<void> test_invocation_otherClass() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -435,7 +435,7 @@
 ''');
   }
 
-  test_method() async {
+  Future<void> test_method() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -484,7 +484,7 @@
 ''');
   }
 
-  test_method_parameters() async {
+  Future<void> test_method_parameters() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -556,7 +556,7 @@
 ''');
   }
 
-  test_method_parameters_named() async {
+  Future<void> test_method_parameters_named() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -628,7 +628,7 @@
 ''');
   }
 
-  test_parameters_field_read_enclosingClass() async {
+  Future<void> test_parameters_field_read_enclosingClass() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -672,7 +672,7 @@
 ''');
   }
 
-  test_parameters_field_read_otherClass() async {
+  Future<void> test_parameters_field_read_otherClass() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -724,7 +724,7 @@
 ''');
   }
 
-  test_parameters_field_read_topLevelVariable() async {
+  Future<void> test_parameters_field_read_topLevelVariable() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -765,7 +765,7 @@
 ''');
   }
 
-  test_parameters_field_write_enclosingClass() async {
+  Future<void> test_parameters_field_write_enclosingClass() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -790,7 +790,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.ERROR);
   }
 
-  test_parameters_field_write_enclosingSuperClass() async {
+  Future<void> test_parameters_field_write_enclosingSuperClass() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -817,7 +817,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.ERROR);
   }
 
-  test_parameters_field_write_otherClass() async {
+  Future<void> test_parameters_field_write_otherClass() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -879,7 +879,7 @@
 ''');
   }
 
-  test_parameters_key() async {
+  Future<void> test_parameters_key() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -898,7 +898,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.ERROR);
   }
 
-  test_parameters_local_read_enclosingScope() async {
+  Future<void> test_parameters_local_read_enclosingScope() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -940,7 +940,7 @@
 ''');
   }
 
-  test_parameters_local_write_enclosingScope() async {
+  Future<void> test_parameters_local_write_enclosingScope() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -964,7 +964,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.ERROR);
   }
 
-  test_parameters_private() async {
+  Future<void> test_parameters_private() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -1008,7 +1008,7 @@
 ''');
   }
 
-  test_parameters_private_conflictWithPublic() async {
+  Future<void> test_parameters_private_conflictWithPublic() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -1056,7 +1056,7 @@
 ''');
   }
 
-  test_parameters_readField_readLocal() async {
+  Future<void> test_parameters_readField_readLocal() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -1114,7 +1114,7 @@
 ''');
   }
 
-  test_refactoringName() async {
+  Future<void> test_refactoringName() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -1130,7 +1130,7 @@
     expect(refactoring.refactoringName, 'Extract Widget');
   }
 
-  test_statements() async {
+  Future<void> test_statements() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -1186,7 +1186,7 @@
 ''');
   }
 
-  test_statements_BAD_emptySelection() async {
+  Future<void> test_statements_BAD_emptySelection() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -1202,7 +1202,7 @@
         RefactoringProblemSeverity.FATAL);
   }
 
-  test_statements_BAD_notReturnStatement() async {
+  Future<void> test_statements_BAD_notReturnStatement() async {
     addFlutterPackage();
     await indexTestUnit(r'''
 import 'package:flutter/material.dart';
diff --git a/pkg/analysis_server/test/services/refactoring/inline_local_test.dart b/pkg/analysis_server/test/services/refactoring/inline_local_test.dart
index 7abb5ae..fb5784a 100644
--- a/pkg/analysis_server/test/services/refactoring/inline_local_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/inline_local_test.dart
@@ -11,7 +11,7 @@
 
 import 'abstract_refactoring.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InlineLocalTest);
   });
@@ -22,7 +22,7 @@
   @override
   InlineLocalRefactoringImpl refactoring;
 
-  test_access() async {
+  Future<void> test_access() async {
     await indexTestUnit('''
 main() {
   int test = 1 + 2;
@@ -38,7 +38,7 @@
     expect(refactoring.referenceCount, 2);
   }
 
-  test_bad_selectionMethod() async {
+  Future<void> test_bad_selectionMethod() async {
     await indexTestUnit(r'''
 main() {
 }
@@ -48,7 +48,7 @@
     _assert_fatalError_selection(status);
   }
 
-  test_bad_selectionParameter() async {
+  Future<void> test_bad_selectionParameter() async {
     await indexTestUnit(r'''
 main(int test) {
 }
@@ -58,7 +58,7 @@
     _assert_fatalError_selection(status);
   }
 
-  test_bad_selectionVariable_hasAssignments_1() async {
+  Future<void> test_bad_selectionVariable_hasAssignments_1() async {
     await indexTestUnit(r'''
 main() {
   int test = 0;
@@ -71,7 +71,7 @@
         expectedContextSearch: 'test = 1');
   }
 
-  test_bad_selectionVariable_hasAssignments_2() async {
+  Future<void> test_bad_selectionVariable_hasAssignments_2() async {
     await indexTestUnit(r'''
 main() {
   int test = 0;
@@ -84,7 +84,7 @@
         expectedContextSearch: 'test += 1');
   }
 
-  test_bad_selectionVariable_notInBlock() async {
+  Future<void> test_bad_selectionVariable_notInBlock() async {
     await indexTestUnit(r'''
 main() {
   if (true)
@@ -96,7 +96,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL);
   }
 
-  test_bad_selectionVariable_notInitialized() async {
+  Future<void> test_bad_selectionVariable_notInitialized() async {
     await indexTestUnit(r'''
 main() {
   int test;
@@ -107,7 +107,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL);
   }
 
-  test_OK_cascade_intoCascade() async {
+  Future<void> test_OK_cascade_intoCascade() async {
     await indexTestUnit(r'''
 class A {
   foo() {}
@@ -131,7 +131,7 @@
 ''');
   }
 
-  test_OK_cascade_intoNotCascade() async {
+  Future<void> test_OK_cascade_intoNotCascade() async {
     await indexTestUnit(r'''
 class A {
   foo() {}
@@ -155,7 +155,7 @@
 ''');
   }
 
-  test_OK_inSwitchCase() async {
+  Future<void> test_OK_inSwitchCase() async {
     await indexTestUnit('''
 main(int p) {
   switch (p) {
@@ -179,7 +179,7 @@
 ''');
   }
 
-  test_OK_intoStringInterpolation_binaryExpression() async {
+  Future<void> test_OK_intoStringInterpolation_binaryExpression() async {
     await indexTestUnit(r'''
 main() {
   int test = 1 + 2;
@@ -201,7 +201,7 @@
 ''');
   }
 
-  test_OK_intoStringInterpolation_simpleIdentifier() async {
+  Future<void> test_OK_intoStringInterpolation_simpleIdentifier() async {
     await indexTestUnit(r'''
 main() {
   int foo = 1 + 2;
@@ -225,7 +225,7 @@
 ''');
   }
 
-  test_OK_intoStringInterpolation_string_differentQuotes() async {
+  Future<void> test_OK_intoStringInterpolation_string_differentQuotes() async {
     await indexTestUnit(r'''
 main() {
   String a = "aaa";
@@ -241,7 +241,7 @@
 ''');
   }
 
-  test_OK_intoStringInterpolation_string_doubleQuotes() async {
+  Future<void> test_OK_intoStringInterpolation_string_doubleQuotes() async {
     await indexTestUnit(r'''
 main() {
   String a = "aaa";
@@ -257,7 +257,8 @@
 ''');
   }
 
-  test_OK_intoStringInterpolation_string_multiLineIntoMulti_leadingSpaces() async {
+  Future<void>
+      test_OK_intoStringInterpolation_string_multiLineIntoMulti_leadingSpaces() async {
     await indexTestUnit(r"""
 main() {
   String a = '''\ \
@@ -280,7 +281,8 @@
 """);
   }
 
-  test_OK_intoStringInterpolation_string_multiLineIntoMulti_unixEOL() async {
+  Future<void>
+      test_OK_intoStringInterpolation_string_multiLineIntoMulti_unixEOL() async {
     await indexTestUnit(r"""
 main() {
   String a = '''
@@ -305,7 +307,8 @@
 """);
   }
 
-  test_OK_intoStringInterpolation_string_multiLineIntoMulti_windowsEOL() async {
+  Future<void>
+      test_OK_intoStringInterpolation_string_multiLineIntoMulti_windowsEOL() async {
     await indexTestUnit(r"""
 main() {
   String a = '''
@@ -332,7 +335,8 @@
         .replaceAll('\n', '\r\n'));
   }
 
-  test_OK_intoStringInterpolation_string_multiLineIntoSingle() async {
+  Future<void>
+      test_OK_intoStringInterpolation_string_multiLineIntoSingle() async {
     await indexTestUnit(r'''
 main() {
   String a = """aaa""";
@@ -348,7 +352,7 @@
 ''');
   }
 
-  test_OK_intoStringInterpolation_string_raw() async {
+  Future<void> test_OK_intoStringInterpolation_string_raw() async {
     await indexTestUnit(r'''
 main() {
   String a = r'an $ignored interpolation';
@@ -364,7 +368,8 @@
 ''');
   }
 
-  test_OK_intoStringInterpolation_string_singleLineIntoMulti_doubleQuotes() async {
+  Future<void>
+      test_OK_intoStringInterpolation_string_singleLineIntoMulti_doubleQuotes() async {
     await indexTestUnit(r'''
 main() {
   String a = "aaa";
@@ -380,7 +385,8 @@
 ''');
   }
 
-  test_OK_intoStringInterpolation_string_singleLineIntoMulti_singleQuotes() async {
+  Future<void>
+      test_OK_intoStringInterpolation_string_singleLineIntoMulti_singleQuotes() async {
     await indexTestUnit(r"""
 main() {
   String a = 'aaa';
@@ -396,7 +402,7 @@
 """);
   }
 
-  test_OK_intoStringInterpolation_string_singleQuotes() async {
+  Future<void> test_OK_intoStringInterpolation_string_singleQuotes() async {
     await indexTestUnit(r'''
 main() {
   String a = 'aaa';
@@ -412,7 +418,7 @@
 ''');
   }
 
-  test_OK_intoStringInterpolation_stringInterpolation() async {
+  Future<void> test_OK_intoStringInterpolation_stringInterpolation() async {
     await indexTestUnit(r'''
 main() {
   String a = 'aaa';
@@ -434,7 +440,7 @@
    * <p>
    * https://code.google.com/p/dart/issues/detail?id=18587
    */
-  test_OK_keepNextCommentedLine() async {
+  Future<void> test_OK_keepNextCommentedLine() async {
     await indexTestUnit('''
 main() {
   int test = 1 + 2;
@@ -454,7 +460,7 @@
 ''');
   }
 
-  test_OK_noUsages_1() async {
+  Future<void> test_OK_noUsages_1() async {
     await indexTestUnit('''
 main() {
   int test = 1 + 2;
@@ -470,7 +476,7 @@
 ''');
   }
 
-  test_OK_noUsages_2() async {
+  Future<void> test_OK_noUsages_2() async {
     await indexTestUnit('''
 main() {
   int test = 1 + 2;
@@ -484,7 +490,7 @@
 ''');
   }
 
-  test_OK_oneUsage() async {
+  Future<void> test_OK_oneUsage() async {
     await indexTestUnit('''
 main() {
   int test = 1 + 2;
@@ -500,7 +506,7 @@
 ''');
   }
 
-  test_OK_parenthesis_decrement_intoNegate() async {
+  Future<void> test_OK_parenthesis_decrement_intoNegate() async {
     await indexTestUnit('''
 main() {
   var a = 1;
@@ -518,7 +524,7 @@
 ''');
   }
 
-  test_OK_parenthesis_instanceCreation_intoList() async {
+  Future<void> test_OK_parenthesis_instanceCreation_intoList() async {
     await indexTestUnit('''
 class A {}
 main() {
@@ -536,7 +542,7 @@
 ''');
   }
 
-  test_OK_parenthesis_intoIndexExpression_index() async {
+  Future<void> test_OK_parenthesis_intoIndexExpression_index() async {
     await indexTestUnit('''
 main() {
   var items = [];
@@ -554,7 +560,7 @@
 ''');
   }
 
-  test_OK_parenthesis_intoParenthesizedExpression() async {
+  Future<void> test_OK_parenthesis_intoParenthesizedExpression() async {
     await indexTestUnit('''
 f(m, x, y) {
   int test = x as int;
@@ -572,7 +578,7 @@
 ''');
   }
 
-  test_OK_parenthesis_negate_intoNegate() async {
+  Future<void> test_OK_parenthesis_negate_intoNegate() async {
     await indexTestUnit('''
 main() {
   var a = 1;
@@ -590,7 +596,7 @@
 ''');
   }
 
-  test_OK_parenthesis_plus_intoMultiply() async {
+  Future<void> test_OK_parenthesis_plus_intoMultiply() async {
     await indexTestUnit('''
 main() {
   var test = 1 + 2;
@@ -606,7 +612,7 @@
 ''');
   }
 
-  test_OK_twoUsages() async {
+  Future<void> test_OK_twoUsages() async {
     await indexTestUnit('''
 main() {
   int test = 1 + 2;
diff --git a/pkg/analysis_server/test/services/refactoring/inline_method_test.dart b/pkg/analysis_server/test/services/refactoring/inline_method_test.dart
index de0b7b0..aac7820 100644
--- a/pkg/analysis_server/test/services/refactoring/inline_method_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/inline_method_test.dart
@@ -14,7 +14,7 @@
 
 import 'abstract_refactoring.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InlineMethodTest);
   });
@@ -27,7 +27,7 @@
   bool deleteSource;
   bool inlineAll;
 
-  test_access_FunctionElement() async {
+  Future<void> test_access_FunctionElement() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a + b;
@@ -45,7 +45,7 @@
     expect(refactoring.isDeclaration, isFalse);
   }
 
-  test_access_MethodElement() async {
+  Future<void> test_access_MethodElement() async {
     await indexTestUnit(r'''
 class A {
   test(a, b) {
@@ -65,7 +65,7 @@
     expect(refactoring.isDeclaration, isTrue);
   }
 
-  test_bad_async_intoSyncStar() async {
+  Future<void> test_bad_async_intoSyncStar() async {
     await indexTestUnit(r'''
 import 'dart:async';
 class A {
@@ -80,7 +80,7 @@
     return _assertConditionsFatal('Cannot inline async into sync*.');
   }
 
-  test_bad_async_targetIsSync_doesNotReturnFuture() async {
+  Future<void> test_bad_async_targetIsSync_doesNotReturnFuture() async {
     await indexTestUnit(r'''
 import 'dart:async';
 class A {
@@ -97,7 +97,7 @@
         'Cannot inline async into a function that does not return a Future.');
   }
 
-  test_bad_asyncStar() async {
+  Future<void> test_bad_asyncStar() async {
     await indexTestUnit(r'''
 import 'dart:async';
 class A {
@@ -115,7 +115,7 @@
     return _assertConditionsFatal('Cannot inline a generator.');
   }
 
-  test_bad_cascadeInvocation() async {
+  Future<void> test_bad_cascadeInvocation() async {
     await indexTestUnit(r'''
 class A {
   foo() {}
@@ -136,7 +136,7 @@
         expectedContextRange: location);
   }
 
-  test_bad_constructor() async {
+  Future<void> test_bad_constructor() async {
     await indexTestUnit(r'''
 class A {
   A.named() {}
@@ -147,7 +147,7 @@
     return _assertInvalidSelection();
   }
 
-  test_bad_deleteSource_inlineOne() async {
+  Future<void> test_bad_deleteSource_inlineOne() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a + b;
@@ -170,7 +170,7 @@
             'All references must be inlined to remove the source.');
   }
 
-  test_bad_notExecutableElement() async {
+  Future<void> test_bad_notExecutableElement() async {
     await indexTestUnit(r'''
 main() {
 }
@@ -180,7 +180,7 @@
     return _assertInvalidSelection();
   }
 
-  test_bad_notSimpleIdentifier() async {
+  Future<void> test_bad_notSimpleIdentifier() async {
     await indexTestUnit(r'''
 main() {
   var test = 42;
@@ -192,7 +192,7 @@
     return _assertInvalidSelection();
   }
 
-  test_bad_operator() async {
+  Future<void> test_bad_operator() async {
     await indexTestUnit(r'''
 class A {
   operator -(other) => this;
@@ -203,7 +203,7 @@
     return _assertConditionsFatal('Cannot inline operator.');
   }
 
-  test_bad_propertyAccessor_synthetic() async {
+  Future<void> test_bad_propertyAccessor_synthetic() async {
     await indexTestUnit(r'''
 class A {
   int fff;
@@ -218,7 +218,7 @@
     return _assertInvalidSelection();
   }
 
-  test_bad_reference_toClassMethod() async {
+  Future<void> test_bad_reference_toClassMethod() async {
     await indexTestUnit(r'''
 class A {
   test(a, b) {
@@ -235,7 +235,7 @@
     return _assertConditionsFatal('Cannot inline class method reference.');
   }
 
-  test_bad_severalReturns() async {
+  Future<void> test_bad_severalReturns() async {
     await indexTestUnit(r'''
 test() {
   if (true) {
@@ -252,7 +252,7 @@
     return _assertConditionsError('Ambiguous return value.');
   }
 
-  test_cascadeInCascade() async {
+  Future<void> test_cascadeInCascade() async {
     await indexTestUnit(r'''
 class Inner {
   String a;
@@ -297,7 +297,7 @@
 ''');
   }
 
-  test_fieldAccessor_getter() async {
+  Future<void> test_fieldAccessor_getter() async {
     await indexTestUnit(r'''
 class A {
   var f;
@@ -323,7 +323,7 @@
 ''');
   }
 
-  test_fieldAccessor_getter_PropertyAccess() async {
+  Future<void> test_fieldAccessor_getter_PropertyAccess() async {
     await indexTestUnit(r'''
 class A {
   var f;
@@ -355,7 +355,7 @@
 ''');
   }
 
-  test_fieldAccessor_setter() async {
+  Future<void> test_fieldAccessor_setter() async {
     await indexTestUnit(r'''
 class A {
   var f;
@@ -381,7 +381,7 @@
 ''');
   }
 
-  test_fieldAccessor_setter_PropertyAccess() async {
+  Future<void> test_fieldAccessor_setter_PropertyAccess() async {
     await indexTestUnit(r'''
 class A {
   var f;
@@ -413,7 +413,7 @@
 ''');
   }
 
-  test_function_expressionFunctionBody() async {
+  Future<void> test_function_expressionFunctionBody() async {
     await indexTestUnit(r'''
 test(a, b) => a + b;
 main() {
@@ -429,7 +429,7 @@
 ''');
   }
 
-  test_function_hasReturn_assign() async {
+  Future<void> test_function_hasReturn_assign() async {
     await indexTestUnit(r'''
 test(a, b) {
   print(a);
@@ -453,7 +453,7 @@
 ''');
   }
 
-  test_function_hasReturn_hasReturnType() async {
+  Future<void> test_function_hasReturn_hasReturnType() async {
     await indexTestUnit(r'''
 int test(a, b) {
   return a + b;
@@ -471,7 +471,7 @@
 ''');
   }
 
-  test_function_hasReturn_noExpression() async {
+  Future<void> test_function_hasReturn_noExpression() async {
     await indexTestUnit(r'''
 test(a, b) {
   print(a);
@@ -492,7 +492,7 @@
 ''');
   }
 
-  test_function_hasReturn_noVars_oneUsage() async {
+  Future<void> test_function_hasReturn_noVars_oneUsage() async {
     await indexTestUnit(r'''
 test(a, b) {
   print(a);
@@ -514,7 +514,7 @@
 ''');
   }
 
-  test_function_multilineString() async {
+  Future<void> test_function_multilineString() async {
     await indexTestUnit(r"""
 main() {
   {
@@ -542,7 +542,8 @@
 """);
   }
 
-  test_function_noReturn_hasVars_hasConflict_fieldSuperClass() async {
+  Future<void>
+      test_function_noReturn_hasVars_hasConflict_fieldSuperClass() async {
     await indexTestUnit(r'''
 class A {
   var c;
@@ -572,7 +573,8 @@
 ''');
   }
 
-  test_function_noReturn_hasVars_hasConflict_fieldThisClass() async {
+  Future<void>
+      test_function_noReturn_hasVars_hasConflict_fieldThisClass() async {
     await indexTestUnit(r'''
 class A {
   var c;
@@ -598,7 +600,7 @@
 ''');
   }
 
-  test_function_noReturn_hasVars_hasConflict_localAfter() async {
+  Future<void> test_function_noReturn_hasVars_hasConflict_localAfter() async {
     await indexTestUnit(r'''
 test(a, b) {
   var c = a + b;
@@ -620,7 +622,7 @@
 ''');
   }
 
-  test_function_noReturn_hasVars_hasConflict_localBefore() async {
+  Future<void> test_function_noReturn_hasVars_hasConflict_localBefore() async {
     await indexTestUnit(r'''
 test(a, b) {
   var c = a + b;
@@ -642,7 +644,7 @@
 ''');
   }
 
-  test_function_noReturn_hasVars_noConflict() async {
+  Future<void> test_function_noReturn_hasVars_noConflict() async {
     await indexTestUnit(r'''
 test(a, b) {
   var c = a + b;
@@ -662,7 +664,7 @@
 ''');
   }
 
-  test_function_noReturn_noVars_oneUsage() async {
+  Future<void> test_function_noReturn_noVars_oneUsage() async {
     await indexTestUnit(r'''
 test(a, b) {
   print(a);
@@ -682,7 +684,7 @@
 ''');
   }
 
-  test_function_noReturn_noVars_useIndentation() async {
+  Future<void> test_function_noReturn_noVars_useIndentation() async {
     await indexTestUnit(r'''
 test(a, b) {
   print(a);
@@ -706,7 +708,7 @@
 ''');
   }
 
-  test_function_noReturn_voidReturnType() async {
+  Future<void> test_function_noReturn_voidReturnType() async {
     await indexTestUnit(r'''
 void test(a, b) {
   print(a + b);
@@ -724,7 +726,7 @@
 ''');
   }
 
-  test_function_notStatement_oneStatement_assign() async {
+  Future<void> test_function_notStatement_oneStatement_assign() async {
     await indexTestUnit(r'''
 test(int p) {
   print(p * 2);
@@ -746,7 +748,8 @@
 ''');
   }
 
-  test_function_notStatement_oneStatement_variableDeclaration() async {
+  Future<void>
+      test_function_notStatement_oneStatement_variableDeclaration() async {
     await indexTestUnit(r'''
 test(int p) {
   print(p * 2);
@@ -766,7 +769,7 @@
 ''');
   }
 
-  test_function_notStatement_severalStatements() async {
+  Future<void> test_function_notStatement_severalStatements() async {
     await indexTestUnit(r'''
 test(int p) {
   print(p);
@@ -788,7 +791,7 @@
 ''');
   }
 
-  test_function_notStatement_zeroStatements() async {
+  Future<void> test_function_notStatement_zeroStatements() async {
     await indexTestUnit(r'''
 test(int p) {
 }
@@ -806,7 +809,7 @@
 ''');
   }
 
-  test_function_singleStatement() async {
+  Future<void> test_function_singleStatement() async {
     await indexTestUnit(r'''
 var topLevelField = 0;
 test() {
@@ -826,7 +829,7 @@
 ''');
   }
 
-  test_getter_async_targetIsAsync() async {
+  Future<void> test_getter_async_targetIsAsync() async {
     await indexTestUnit(r'''
 import 'dart:async';
 class A {
@@ -848,7 +851,7 @@
 ''');
   }
 
-  test_getter_async_targetIsAsyncStar() async {
+  Future<void> test_getter_async_targetIsAsyncStar() async {
     await indexTestUnit(r'''
 import 'dart:async';
 class A {
@@ -870,7 +873,7 @@
 ''');
   }
 
-  test_getter_async_targetIsSync() async {
+  Future<void> test_getter_async_targetIsSync() async {
     await indexTestUnit(r'''
 import 'dart:async';
 class A {
@@ -892,7 +895,7 @@
 ''');
   }
 
-  test_getter_async_targetIsSync2() async {
+  Future<void> test_getter_async_targetIsSync2() async {
     await indexTestUnit(r'''
 import 'dart:async';
 class A {
@@ -920,7 +923,7 @@
 ''');
   }
 
-  test_getter_classMember_instance() async {
+  Future<void> test_getter_classMember_instance() async {
     await indexTestUnit(r'''
 class A {
   int f;
@@ -942,7 +945,7 @@
 ''');
   }
 
-  test_getter_classMember_static() async {
+  Future<void> test_getter_classMember_static() async {
     await indexTestUnit(r'''
 class A {
   static int get result => 1 + 2;
@@ -962,7 +965,7 @@
 ''');
   }
 
-  test_getter_topLevel() async {
+  Future<void> test_getter_topLevel() async {
     await indexTestUnit(r'''
 String get message => 'Hello, World!';
 main() {
@@ -978,7 +981,7 @@
 ''');
   }
 
-  test_initialMode_all() async {
+  Future<void> test_initialMode_all() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a + b;
@@ -994,7 +997,7 @@
     expect(refactoring.inlineAll, true);
   }
 
-  test_initialMode_single() async {
+  Future<void> test_initialMode_single() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a + b;
@@ -1012,7 +1015,7 @@
     expect(refactoring.inlineAll, false);
   }
 
-  test_method_async() async {
+  Future<void> test_method_async() async {
     await indexTestUnit(r'''
 import 'dart:async';
 class A {
@@ -1034,7 +1037,7 @@
 ''');
   }
 
-  test_method_async2() async {
+  Future<void> test_method_async2() async {
     await indexTestUnit(r'''
 import 'dart:async';
 class A {
@@ -1058,7 +1061,7 @@
 ''');
   }
 
-  test_method_emptyBody() async {
+  Future<void> test_method_emptyBody() async {
     await indexTestUnit(r'''
 abstract class A {
   test();
@@ -1072,7 +1075,7 @@
     return _assertConditionsFatal('Cannot inline method without body.');
   }
 
-  test_method_fieldInstance() async {
+  Future<void> test_method_fieldInstance() async {
     await indexTestUnit(r'''
 class A {
   var fA;
@@ -1110,7 +1113,7 @@
 ''');
   }
 
-  test_method_fieldStatic() async {
+  Future<void> test_method_fieldStatic() async {
     await indexTestUnit(r'''
 class A {
   static var FA = 1;
@@ -1146,7 +1149,7 @@
 ''');
   }
 
-  test_method_fieldStatic_sameClass() async {
+  Future<void> test_method_fieldStatic_sameClass() async {
     await indexTestUnit(r'''
 class A {
   static var F = 1;
@@ -1170,7 +1173,7 @@
 ''');
   }
 
-  test_method_methodInstance() async {
+  Future<void> test_method_methodInstance() async {
     await indexTestUnit(r'''
 class A {
   ma() {}
@@ -1206,7 +1209,7 @@
 ''');
   }
 
-  test_method_methodStatic() async {
+  Future<void> test_method_methodStatic() async {
     await indexTestUnit(r'''
 class A {
   static ma() {}
@@ -1245,7 +1248,7 @@
 ''');
   }
 
-  test_method_singleStatement() async {
+  Future<void> test_method_singleStatement() async {
     await indexTestUnit(r'''
 class A {
   test() {
@@ -1267,7 +1270,7 @@
 ''');
   }
 
-  test_method_this() async {
+  Future<void> test_method_this() async {
     await indexTestUnit(r'''
 class A {
   accept(B b) {}
@@ -1301,7 +1304,7 @@
 ''');
   }
 
-  test_method_unqualifiedInvocation() async {
+  Future<void> test_method_unqualifiedInvocation() async {
     await indexTestUnit(r'''
 class A {
   test(a, b) {
@@ -1327,7 +1330,7 @@
 ''');
   }
 
-  test_namedArgument_inBody() async {
+  Future<void> test_namedArgument_inBody() async {
     await indexTestUnit(r'''
 fa(pa) => fb(pb: true);
 fb({pb: false}) {}
@@ -1346,7 +1349,7 @@
 ''');
   }
 
-  test_namedArguments() async {
+  Future<void> test_namedArguments() async {
     await indexTestUnit(r'''
 test({a: 0, b: 2}) {
   print(a + b);
@@ -1366,7 +1369,7 @@
 ''');
   }
 
-  test_noArgument_named_hasDefault() async {
+  Future<void> test_noArgument_named_hasDefault() async {
     verifyNoTestUnitErrors = false;
     await indexTestUnit(r'''
 test({a: 42}) {
@@ -1385,7 +1388,7 @@
 ''');
   }
 
-  test_noArgument_positional_hasDefault() async {
+  Future<void> test_noArgument_positional_hasDefault() async {
     verifyNoTestUnitErrors = false;
     await indexTestUnit(r'''
 test([a = 42]) {
@@ -1404,7 +1407,7 @@
 ''');
   }
 
-  test_noArgument_positional_noDefault() async {
+  Future<void> test_noArgument_positional_noDefault() async {
     verifyNoTestUnitErrors = false;
     await indexTestUnit(r'''
 test([a]) {
@@ -1423,7 +1426,7 @@
 ''');
   }
 
-  test_noArgument_required() async {
+  Future<void> test_noArgument_required() async {
     verifyNoTestUnitErrors = false;
     await indexTestUnit(r'''
 test(a) {
@@ -1442,7 +1445,7 @@
         expectedContextRange: location);
   }
 
-  test_reference_expressionBody() async {
+  Future<void> test_reference_expressionBody() async {
     await indexTestUnit(r'''
 String message() => 'Hello, World!';
 main() {
@@ -1458,7 +1461,7 @@
 ''');
   }
 
-  test_reference_noStatement() async {
+  Future<void> test_reference_noStatement() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a || b;
@@ -1482,7 +1485,7 @@
 ''');
   }
 
-  test_reference_toLocal() async {
+  Future<void> test_reference_toLocal() async {
     await indexTestUnit(r'''
 main() {
   test(a, b) {
@@ -1504,7 +1507,7 @@
 ''');
   }
 
-  test_reference_toTopLevel() async {
+  Future<void> test_reference_toTopLevel() async {
     await indexTestUnit(r'''
 test(a, b) {
   print(a);
@@ -1526,7 +1529,7 @@
 ''');
   }
 
-  test_removeEmptyLinesBefore_method() async {
+  Future<void> test_removeEmptyLinesBefore_method() async {
     await indexTestUnit(r'''
 class A {
   before() {
@@ -1556,7 +1559,7 @@
 ''');
   }
 
-  test_setter_classMember_instance() async {
+  Future<void> test_setter_classMember_instance() async {
     await indexTestUnit(r'''
 class A {
   int f;
@@ -1580,7 +1583,7 @@
 ''');
   }
 
-  test_setter_topLevel() async {
+  Future<void> test_setter_topLevel() async {
     await indexTestUnit(r'''
 void set result(x) {
   print(x + 1);
@@ -1598,7 +1601,7 @@
 ''');
   }
 
-  test_singleExpression_oneUsage() async {
+  Future<void> test_singleExpression_oneUsage() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a + b;
@@ -1616,7 +1619,7 @@
 ''');
   }
 
-  test_singleExpression_oneUsage_keepMethod() async {
+  Future<void> test_singleExpression_oneUsage_keepMethod() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a + b;
@@ -1638,7 +1641,7 @@
 ''');
   }
 
-  test_singleExpression_twoUsages() async {
+  Future<void> test_singleExpression_twoUsages() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a + b;
@@ -1658,7 +1661,7 @@
 ''');
   }
 
-  test_singleExpression_twoUsages_inlineOne() async {
+  Future<void> test_singleExpression_twoUsages_inlineOne() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a + b;
@@ -1681,7 +1684,8 @@
 ''');
   }
 
-  test_singleExpression_wrapIntoParenthesized_alreadyInMethod() async {
+  Future<void>
+      test_singleExpression_wrapIntoParenthesized_alreadyInMethod() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a * (b);
@@ -1699,7 +1703,7 @@
 ''');
   }
 
-  test_singleExpression_wrapIntoParenthesized_asNeeded() async {
+  Future<void> test_singleExpression_wrapIntoParenthesized_asNeeded() async {
     await indexTestUnit(r'''
 test(a, b) {
   return a * b;
@@ -1719,7 +1723,7 @@
 ''');
   }
 
-  test_singleExpression_wrapIntoParenthesized_bool() async {
+  Future<void> test_singleExpression_wrapIntoParenthesized_bool() async {
     await indexTestUnit(r'''
 test(bool a, bool b) {
   return a || b;
diff --git a/pkg/analysis_server/test/services/refactoring/move_file_test.dart b/pkg/analysis_server/test/services/refactoring/move_file_test.dart
index 706d1cc..58c93882 100644
--- a/pkg/analysis_server/test/services/refactoring/move_file_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/move_file_test.dart
@@ -12,7 +12,7 @@
 
 import 'abstract_refactoring.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MoveFileTest);
   });
@@ -23,7 +23,7 @@
   @override
   MoveFileRefactoring refactoring;
 
-  test_file_containing_imports_exports_parts() async {
+  Future<void> test_file_containing_imports_exports_parts() async {
     String pathA = convertPath('/home/test/000/1111/a.dart');
     String pathB = convertPath('/home/test/000/1111/b.dart');
     String pathC = convertPath('/home/test/000/1111/22/c.dart');
@@ -57,7 +57,7 @@
 ''');
   }
 
-  test_file_imported_with_package_uri_down() async {
+  Future<void> test_file_imported_with_package_uri_down() async {
     var file = newFile('/home/test/lib/old_name.dart', content: '');
     addTestSource(r'''
 import 'package:test/old_name.dart';
@@ -77,7 +77,7 @@
   }
 
   @failingTest
-  test_file_imported_with_package_uri_lib_change() async {
+  Future<void> test_file_imported_with_package_uri_lib_change() async {
     // The current testing stack does not support creating such bazel roots
     var file =
         newFile('/home/test0/test1/test2/lib/111/name.dart', content: '');
@@ -100,7 +100,7 @@
   }
 
   @failingTest
-  test_file_imported_with_package_uri_lib_change_down() async {
+  Future<void> test_file_imported_with_package_uri_lib_change_down() async {
     // The current testing stack does not support creating such bazel roots
     var file =
         newFile('/home/test0/test1/test2/lib/111/name.dart', content: '');
@@ -123,7 +123,7 @@
   }
 
   @failingTest
-  test_file_imported_with_package_uri_lib_change_up() async {
+  Future<void> test_file_imported_with_package_uri_lib_change_up() async {
     // The current testing stack does not support creating such bazel roots
     var file =
         newFile('/home/test0/test1/test2/lib/111/name.dart', content: '');
@@ -145,7 +145,7 @@
 ''');
   }
 
-  test_file_imported_with_package_uri_sideways() async {
+  Future<void> test_file_imported_with_package_uri_sideways() async {
     var file = newFile('/home/test/lib/111/old_name.dart', content: '');
     addTestSource(r'''
 import 'package:test/111/old_name.dart';
@@ -164,7 +164,7 @@
 ''');
   }
 
-  test_file_imported_with_package_uri_up() async {
+  Future<void> test_file_imported_with_package_uri_up() async {
     var file = newFile('/home/test/lib/222/old_name.dart', content: '');
     addTestSource(r'''
 import 'package:test/222/old_name.dart';
@@ -183,7 +183,7 @@
 ''');
   }
 
-  test_file_imported_with_relative_uri_down() async {
+  Future<void> test_file_imported_with_relative_uri_down() async {
     String pathA = convertPath('/home/test/000/1111/a.dart');
     testFile = convertPath('/home/test/000/1111/test.dart');
     addSource(pathA, '''
@@ -201,7 +201,7 @@
     assertNoFileChange(testFile);
   }
 
-  test_file_imported_with_relative_uri_sideways() async {
+  Future<void> test_file_imported_with_relative_uri_sideways() async {
     String pathA = convertPath('/home/test/000/1111/a.dart');
     testFile = convertPath('/home/test/000/1111/sub/folder/test.dart');
     addSource(pathA, '''
@@ -217,7 +217,7 @@
     assertNoFileChange(testFile);
   }
 
-  test_file_imported_with_relative_uri_up() async {
+  Future<void> test_file_imported_with_relative_uri_up() async {
     String pathA = convertPath('/home/test/000/1111/a.dart');
     testFile = convertPath('/home/test/000/1111/22/test.dart');
     addSource(pathA, '''
@@ -234,7 +234,7 @@
   }
 
   @failingTest
-  test_file_referenced_by_multiple_libraries() async {
+  Future<void> test_file_referenced_by_multiple_libraries() async {
     // This test fails because the search index doesn't support multiple uris for
     // a library, so only one of them is updated.
     String pathA = convertPath('/home/test/000/1111/a.dart');
@@ -265,7 +265,7 @@
     assertNoFileChange(testFile);
   }
 
-  test_file_referenced_by_part() async {
+  Future<void> test_file_referenced_by_part() async {
     String pathA = convertPath('/home/test/000/1111/a.dart');
     testFile = convertPath('/home/test/000/1111/22/test.dart');
     addSource(pathA, '''
@@ -286,11 +286,11 @@
   }
 
   @failingTest
-  test_folder_inside_project() async {
+  Future<void> test_folder_inside_project() async {
     fail('Not yet implemented/tested');
   }
 
-  test_folder_outside_workspace_returns_failure() async {
+  Future<void> test_folder_outside_workspace_returns_failure() async {
     _createRefactoring('/tmp-new', oldFile: '/tmp');
     // TODO(dantup): These paths should all use convertPath so they're as expected
     // on Windows.
@@ -299,7 +299,7 @@
             '${convertPath('/tmp')} does not belong to an analysis root.');
   }
 
-  test_nonexistent_file_returns_failure() async {
+  Future<void> test_nonexistent_file_returns_failure() async {
     _createRefactoring(convertPath('/home/test/test_missing_new.dart'),
         oldFile: convertPath('/home/test/test_missing.dart'));
     await _assertFailedRefactoring(RefactoringProblemSeverity.FATAL,
@@ -308,20 +308,20 @@
   }
 
   @failingTest
-  test_project_folder_ancestor() async {
+  Future<void> test_project_folder_ancestor() async {
     // For this, we need the project to not be at top level (/project) so we can
     // rename an ancestor folder.
     fail('Not yet implemented/tested');
   }
 
-  test_projectFolder() async {
+  Future<void> test_projectFolder() async {
     _createRefactoring('/home/test2', oldFile: '/home/test');
     await _assertFailedRefactoring(RefactoringProblemSeverity.FATAL,
         expectedMessage: 'Renaming an analysis root is not supported '
             '(${convertPath('/home/test')})');
   }
 
-  test_renaming_part_that_uses_uri_in_part_of() async {
+  Future<void> test_renaming_part_that_uses_uri_in_part_of() async {
     // If the file is a part in a library, and the part-of directive uses a URI
     // rather than a library name, that will need updating too (if the relative
     // path to the parent changes).
@@ -346,7 +346,7 @@
 ''');
   }
 
-  test_renaming_part_that_uses_uri_in_part_of_2() async {
+  Future<void> test_renaming_part_that_uses_uri_in_part_of_2() async {
     // If the file is a part in a library, and the part-of directive uses a URI
     // rather than a library name, that will need updating too (if the relative
     // path to the parent changes).
@@ -369,7 +369,7 @@
 ''');
   }
 
-  test_renaming_part_that_uses_uri_in_part_of_3() async {
+  Future<void> test_renaming_part_that_uses_uri_in_part_of_3() async {
     // If the file is a part in a library, and the part-of directive uses a URI
     // rather than a library name, that will need updating too (if the relative
     // path to the parent changes).
@@ -392,7 +392,7 @@
 ''');
   }
 
-  test_renaming_part_that_uses_uri_in_part_of_4() async {
+  Future<void> test_renaming_part_that_uses_uri_in_part_of_4() async {
     // If the file is a part in a library, and the part-of directive uses a URI
     // rather than a library name, that will need updating too (if the relative
     // path to the parent changes).
@@ -415,7 +415,7 @@
 ''');
   }
 
-  test_renaming_part_that_uses_uri_in_part_of_5() async {
+  Future<void> test_renaming_part_that_uses_uri_in_part_of_5() async {
     // If the file is a part in a library, and the part-of directive uses a URI
     // rather than a library name, that will need updating too (if the relative
     // path to the parent changes).
diff --git a/pkg/analysis_server/test/services/refactoring/naming_conventions_test.dart b/pkg/analysis_server/test/services/refactoring/naming_conventions_test.dart
index a51399b..8c9ec86 100644
--- a/pkg/analysis_server/test/services/refactoring/naming_conventions_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/naming_conventions_test.dart
@@ -11,7 +11,7 @@
 
 import 'abstract_refactoring.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(NamingConventionsTest);
   });
diff --git a/pkg/analysis_server/test/services/refactoring/rename_class_member_test.dart b/pkg/analysis_server/test/services/refactoring/rename_class_member_test.dart
index 9fb1fd4..fc05cbd 100644
--- a/pkg/analysis_server/test/services/refactoring/rename_class_member_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/rename_class_member_test.dart
@@ -10,7 +10,7 @@
 
 import 'abstract_rename.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RenameClassMemberTest);
   });
@@ -18,7 +18,7 @@
 
 @reflectiveTest
 class RenameClassMemberTest extends RenameRefactoringTest {
-  test_checkFinalConditions_classNameConflict_sameClass() async {
+  Future<void> test_checkFinalConditions_classNameConflict_sameClass() async {
     await indexTestUnit('''
 class NewName {
   void test() {}
@@ -34,7 +34,7 @@
         expectedContextSearch: 'test() {}');
   }
 
-  test_checkFinalConditions_classNameConflict_subClass() async {
+  Future<void> test_checkFinalConditions_classNameConflict_subClass() async {
     await indexTestUnit('''
 class A {
   void test() {} // 1
@@ -53,7 +53,7 @@
         expectedContextSearch: 'test() {} // 2');
   }
 
-  test_checkFinalConditions_classNameConflict_superClass() async {
+  Future<void> test_checkFinalConditions_classNameConflict_superClass() async {
     await indexTestUnit('''
 class NewName {
   void test() {} // 1
@@ -72,7 +72,7 @@
         expectedContextSearch: 'test() {} // 1');
   }
 
-  test_checkFinalConditions_hasMember_MethodElement() async {
+  Future<void> test_checkFinalConditions_hasMember_MethodElement() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -89,7 +89,7 @@
         expectedContextSearch: 'newName() {} // existing');
   }
 
-  test_checkFinalConditions_OK_dropSuffix() async {
+  Future<void> test_checkFinalConditions_OK_dropSuffix() async {
     await indexTestUnit(r'''
 abstract class A {
   void testOld();
@@ -105,7 +105,7 @@
     assertRefactoringStatusOK(status);
   }
 
-  test_checkFinalConditions_OK_noShadow() async {
+  Future<void> test_checkFinalConditions_OK_noShadow() async {
     await indexTestUnit('''
 class A {
   int newName;
@@ -126,7 +126,7 @@
     assertRefactoringStatusOK(status);
   }
 
-  test_checkFinalConditions_OK_noShadow_nullVisibleRange() async {
+  Future<void> test_checkFinalConditions_OK_noShadow_nullVisibleRange() async {
     await indexTestUnit('''
 class A {
   int foo;
@@ -151,7 +151,8 @@
     assertRefactoringStatusOK(status);
   }
 
-  test_checkFinalConditions_publicToPrivate_usedInOtherLibrary() async {
+  Future<void>
+      test_checkFinalConditions_publicToPrivate_usedInOtherLibrary() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -173,7 +174,8 @@
         expectedMessage: "Renamed method will be invisible in 'my.lib'.");
   }
 
-  test_checkFinalConditions_shadowed_byLocalFunction_inSameClass() async {
+  Future<void>
+      test_checkFinalConditions_shadowed_byLocalFunction_inSameClass() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -193,7 +195,8 @@
         expectedContextSearch: 'test(); // marker');
   }
 
-  test_checkFinalConditions_shadowed_byLocalVariable_inSameClass() async {
+  Future<void>
+      test_checkFinalConditions_shadowed_byLocalVariable_inSameClass() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -213,7 +216,8 @@
         expectedContextSearch: 'test(); // marker');
   }
 
-  test_checkFinalConditions_shadowed_byLocalVariable_inSubClass() async {
+  Future<void>
+      test_checkFinalConditions_shadowed_byLocalVariable_inSubClass() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -235,7 +239,8 @@
         expectedContextSearch: 'test(); // marker');
   }
 
-  test_checkFinalConditions_shadowed_byLocalVariable_OK_qualifiedReference() async {
+  Future<void>
+      test_checkFinalConditions_shadowed_byLocalVariable_OK_qualifiedReference() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -252,7 +257,8 @@
     assertRefactoringStatusOK(status);
   }
 
-  test_checkFinalConditions_shadowed_byLocalVariable_OK_renamedNotUsed() async {
+  Future<void>
+      test_checkFinalConditions_shadowed_byLocalVariable_OK_renamedNotUsed() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -268,7 +274,8 @@
     assertRefactoringStatusOK(status);
   }
 
-  test_checkFinalConditions_shadowed_byParameter_inSameClass() async {
+  Future<void>
+      test_checkFinalConditions_shadowed_byParameter_inSameClass() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -287,7 +294,7 @@
         expectedContextSearch: 'test(); // marker');
   }
 
-  test_checkFinalConditions_shadowedBySub_MethodElement() async {
+  Future<void> test_checkFinalConditions_shadowedBySub_MethodElement() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -309,7 +316,7 @@
         expectedContextSearch: 'newName() {} // marker');
   }
 
-  test_checkFinalConditions_shadowsSuper_FieldElement() async {
+  Future<void> test_checkFinalConditions_shadowsSuper_FieldElement() async {
     await indexTestUnit('''
 class A {
   int newName; // marker
@@ -332,7 +339,7 @@
         expectedContextSearch: 'newName; // marker');
   }
 
-  test_checkFinalConditions_shadowsSuper_MethodElement() async {
+  Future<void> test_checkFinalConditions_shadowsSuper_MethodElement() async {
     await indexTestUnit('''
 class A {
   newName() {} // marker
@@ -350,7 +357,8 @@
         expectedContextSearch: 'newName() {} // marker');
   }
 
-  test_checkFinalConditions_shadowsSuper_MethodElement_otherLib() async {
+  Future<void>
+      test_checkFinalConditions_shadowsSuper_MethodElement_otherLib() async {
     var libCode = r'''
 class A {
   newName() {} // marker
@@ -373,7 +381,7 @@
             libCode.indexOf('newName() {} // marker'), 'newName'.length));
   }
 
-  test_checkInitialConditions_inSDK() async {
+  Future<void> test_checkInitialConditions_inSDK() async {
     await indexTestUnit('''
 main() {
   'abc'.toUpperCase();
@@ -388,7 +396,7 @@
             "The method 'String.toUpperCase' is defined in the SDK, so cannot be renamed.");
   }
 
-  test_checkInitialConditions_operator() async {
+  Future<void> test_checkInitialConditions_operator() async {
     await indexTestUnit('''
 class A {
   operator -(other) => this;
@@ -401,7 +409,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL);
   }
 
-  test_checkNewName_FieldElement() async {
+  Future<void> test_checkNewName_FieldElement() async {
     await indexTestUnit('''
 class A {
   int test;
@@ -418,7 +426,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_checkNewName_MethodElement() async {
+  Future<void> test_checkNewName_MethodElement() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -446,7 +454,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_createChange_FieldElement() async {
+  Future<void> test_createChange_FieldElement() async {
     await indexTestUnit('''
 class A {
   int test; // marker
@@ -512,7 +520,8 @@
 ''');
   }
 
-  test_createChange_FieldElement_constructorFieldInitializer() async {
+  Future<void>
+      test_createChange_FieldElement_constructorFieldInitializer() async {
     await indexTestUnit('''
 class A {
   final test;
@@ -533,7 +542,7 @@
 ''');
   }
 
-  test_createChange_FieldElement_fieldFormalParameter() async {
+  Future<void> test_createChange_FieldElement_fieldFormalParameter() async {
     await indexTestUnit('''
 class A {
   final test;
@@ -554,7 +563,8 @@
 ''');
   }
 
-  test_createChange_FieldElement_fieldFormalParameter_named() async {
+  Future<void>
+      test_createChange_FieldElement_fieldFormalParameter_named() async {
     await indexTestUnit('''
 class A {
   final test;
@@ -581,7 +591,7 @@
 ''');
   }
 
-  test_createChange_FieldElement_invocation() async {
+  Future<void> test_createChange_FieldElement_invocation() async {
     await indexTestUnit('''
 typedef F(a);
 class A {
@@ -616,7 +626,7 @@
 ''');
   }
 
-  test_createChange_MethodElement() async {
+  Future<void> test_createChange_MethodElement() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -684,7 +694,7 @@
 ''');
   }
 
-  test_createChange_MethodElement_potential() async {
+  Future<void> test_createChange_MethodElement_potential() async {
     await indexTestUnit('''
 class A {
   test() {}
@@ -714,7 +724,7 @@
     assertPotentialEdits(['test(); // 1', 'test(); // 2']);
   }
 
-  test_createChange_MethodElement_potential_inPubCache() async {
+  Future<void> test_createChange_MethodElement_potential_inPubCache() async {
     var externalPath = addPackageFile('aaa', 'lib.dart', r'''
 processObj(p) {
   p.test();
@@ -752,7 +762,8 @@
     expect(fileEdit, isNull);
   }
 
-  test_createChange_MethodElement_potential_private_otherLibrary() async {
+  Future<void>
+      test_createChange_MethodElement_potential_private_otherLibrary() async {
     await indexUnit('/lib.dart', '''
 library lib;
 main(p) {
@@ -786,7 +797,7 @@
     assertNoFileChange('/lib.dart');
   }
 
-  test_createChange_outsideOfProject_declarationInPackage() async {
+  Future<void> test_createChange_outsideOfProject_declarationInPackage() async {
     addPackageFile('aaa', 'aaa.dart', r'''
 class A {
   void test() {}
@@ -828,7 +839,7 @@
     expect(refactoringChange.edits[0].file, testFile);
   }
 
-  test_createChange_outsideOfProject_referenceInPart() async {
+  Future<void> test_createChange_outsideOfProject_referenceInPart() async {
     newFile('/home/part.dart', content: r'''
 part of test;
 
@@ -874,7 +885,7 @@
     expect(refactoringChange.edits[0].file, testFile);
   }
 
-  test_createChange_PropertyAccessorElement_getter() async {
+  Future<void> test_createChange_PropertyAccessorElement_getter() async {
     await indexTestUnit('''
 class A {
   get test {} // marker
@@ -929,7 +940,7 @@
 ''');
   }
 
-  test_createChange_PropertyAccessorElement_setter() async {
+  Future<void> test_createChange_PropertyAccessorElement_setter() async {
     await indexTestUnit('''
 class A {
   get test {}
@@ -984,7 +995,7 @@
 ''');
   }
 
-  test_createChange_TypeParameterElement() async {
+  Future<void> test_createChange_TypeParameterElement() async {
     await indexTestUnit('''
 class A<Test> {
   Test field;
diff --git a/pkg/analysis_server/test/services/refactoring/rename_constructor_test.dart b/pkg/analysis_server/test/services/refactoring/rename_constructor_test.dart
index 91686be..dc99c2b 100644
--- a/pkg/analysis_server/test/services/refactoring/rename_constructor_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/rename_constructor_test.dart
@@ -12,7 +12,7 @@
 
 import 'abstract_rename.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RenameConstructorTest);
   });
@@ -20,7 +20,7 @@
 
 @reflectiveTest
 class RenameConstructorTest extends RenameRefactoringTest {
-  test_checkInitialConditions_inSDK() async {
+  Future<void> test_checkInitialConditions_inSDK() async {
     await indexTestUnit('''
 main() {
   new String.fromCharCodes([]);
@@ -35,7 +35,7 @@
             "The constructor 'String.fromCharCodes' is defined in the SDK, so cannot be renamed.");
   }
 
-  test_checkNewName() async {
+  Future<void> test_checkNewName() async {
     await indexTestUnit('''
 class A {
   A.test() {}
@@ -62,7 +62,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_checkNewName_hasMember_constructor() async {
+  Future<void> test_checkNewName_hasMember_constructor() async {
     await indexTestUnit('''
 class A {
   A.test() {}
@@ -79,7 +79,7 @@
         expectedContextSearch: 'newName() {} // existing');
   }
 
-  test_checkNewName_hasMember_method() async {
+  Future<void> test_checkNewName_hasMember_method() async {
     await indexTestUnit('''
 class A {
   A.test() {}
@@ -96,7 +96,7 @@
         expectedContextSearch: 'newName() {} // existing');
   }
 
-  test_createChange_add() async {
+  Future<void> test_createChange_add() async {
     await indexTestUnit('''
 class A {
   A() {} // marker
@@ -130,7 +130,7 @@
 ''');
   }
 
-  test_createChange_add_toSynthetic() async {
+  Future<void> test_createChange_add_toSynthetic() async {
     await indexTestUnit('''
 class A {
 }
@@ -161,7 +161,7 @@
 ''');
   }
 
-  test_createChange_change() async {
+  Future<void> test_createChange_change() async {
     await indexTestUnit('''
 class A {
   A.test() {} // marker
@@ -195,7 +195,7 @@
 ''');
   }
 
-  test_createChange_remove() async {
+  Future<void> test_createChange_remove() async {
     await indexTestUnit('''
 class A {
   A.test() {} // marker
@@ -229,7 +229,7 @@
 ''');
   }
 
-  test_newInstance_nullElement() async {
+  Future<void> test_newInstance_nullElement() async {
     await indexTestUnit('');
     var workspace = RefactoringWorkspace([driver], searchEngine);
     var refactoring = RenameRefactoring(workspace, testAnalysisResult, null);
diff --git a/pkg/analysis_server/test/services/refactoring/rename_extension_member_test.dart b/pkg/analysis_server/test/services/refactoring/rename_extension_member_test.dart
index b26061f..87c9044 100644
--- a/pkg/analysis_server/test/services/refactoring/rename_extension_member_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/rename_extension_member_test.dart
@@ -9,7 +9,7 @@
 
 import 'abstract_rename.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RenameExtensionMemberTest);
   });
@@ -23,7 +23,7 @@
     super.setUp();
   }
 
-  test_checkFinalConditions_hasMember_MethodElement() async {
+  Future<void> test_checkFinalConditions_hasMember_MethodElement() async {
     await indexTestUnit('''
 extension E on int {
   test() {}
@@ -40,7 +40,7 @@
         expectedContextSearch: 'newName() {} // existing');
   }
 
-  test_checkFinalConditions_OK_dropSuffix() async {
+  Future<void> test_checkFinalConditions_OK_dropSuffix() async {
     await indexTestUnit(r'''
 extension E on int {
   void testOld() {}
@@ -53,7 +53,8 @@
     assertRefactoringStatusOK(status);
   }
 
-  test_checkFinalConditions_shadowed_byLocalFunction_inExtension() async {
+  Future<void>
+      test_checkFinalConditions_shadowed_byLocalFunction_inExtension() async {
     await indexTestUnit('''
 extension E on int {
   test() {}
@@ -76,7 +77,8 @@
     );
   }
 
-  test_checkFinalConditions_shadowed_byLocalVariable_inExtension() async {
+  Future<void>
+      test_checkFinalConditions_shadowed_byLocalVariable_inExtension() async {
     await indexTestUnit('''
 extension E on int {
   test() {}
@@ -99,7 +101,8 @@
     );
   }
 
-  test_checkFinalConditions_shadowed_byParameter_inExtension() async {
+  Future<void>
+      test_checkFinalConditions_shadowed_byParameter_inExtension() async {
     await indexTestUnit('''
 extension E on int {
   test() {}
@@ -121,7 +124,7 @@
     );
   }
 
-  test_checkInitialConditions_operator() async {
+  Future<void> test_checkInitialConditions_operator() async {
     await indexTestUnit('''
 extension E on int {
   operator -(other) => null;
@@ -134,7 +137,7 @@
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL);
   }
 
-  test_checkNewName_FieldElement() async {
+  Future<void> test_checkNewName_FieldElement() async {
     await indexTestUnit('''
 extension E on int {
   int get test => 0;
@@ -154,7 +157,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_checkNewName_MethodElement() async {
+  Future<void> test_checkNewName_MethodElement() async {
     await indexTestUnit('''
 extension E on int {
   void test() {}
@@ -191,7 +194,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_createChange_MethodElement_instance() async {
+  Future<void> test_createChange_MethodElement_instance() async {
     await indexTestUnit('''
 class A {}
 
@@ -227,7 +230,7 @@
 ''');
   }
 
-  test_createChange_PropertyAccessorElement_getter() async {
+  Future<void> test_createChange_PropertyAccessorElement_getter() async {
     await indexTestUnit('''
 extension E on int {
   get test {} // marker
@@ -270,7 +273,7 @@
 ''');
   }
 
-  test_createChange_PropertyAccessorElement_setter() async {
+  Future<void> test_createChange_PropertyAccessorElement_setter() async {
     await indexTestUnit('''
 extension E on int {
   get test {}
@@ -313,7 +316,7 @@
 ''');
   }
 
-  test_createChange_TypeParameterElement() async {
+  Future<void> test_createChange_TypeParameterElement() async {
     await indexTestUnit('''
 extension E<Test> on int {
   Test get g1 => null;
diff --git a/pkg/analysis_server/test/services/refactoring/rename_import_test.dart b/pkg/analysis_server/test/services/refactoring/rename_import_test.dart
index 51a5849..7c7bc63 100644
--- a/pkg/analysis_server/test/services/refactoring/rename_import_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/rename_import_test.dart
@@ -9,7 +9,7 @@
 
 import 'abstract_rename.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RenameImportTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class RenameImportTest extends RenameRefactoringTest {
-  test_checkNewName() async {
+  Future<void> test_checkNewName() async {
     await indexTestUnit("import 'dart:async' as test;");
     _createRefactoring("import 'dart:");
     expect(refactoring.oldName, 'test');
@@ -40,7 +40,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_createChange_add() async {
+  Future<void> test_createChange_add() async {
     await indexTestUnit('''
 import 'dart:async';
 import 'dart:math' show Random, min hide max;
@@ -66,7 +66,8 @@
 ''');
   }
 
-  test_createChange_add_interpolationExpression_hasCurlyBrackets() async {
+  Future<void>
+      test_createChange_add_interpolationExpression_hasCurlyBrackets() async {
     await indexTestUnit(r'''
 import 'dart:async';
 main() {
@@ -88,7 +89,8 @@
 ''');
   }
 
-  test_createChange_add_interpolationExpression_noCurlyBrackets() async {
+  Future<void>
+      test_createChange_add_interpolationExpression_noCurlyBrackets() async {
     await indexTestUnit(r'''
 import 'dart:async';
 main() {
@@ -110,7 +112,7 @@
 ''');
   }
 
-  test_createChange_change_className() async {
+  Future<void> test_createChange_change_className() async {
     await indexTestUnit('''
 import 'dart:math' as test;
 import 'dart:async' as test;
@@ -133,7 +135,7 @@
 ''');
   }
 
-  test_createChange_change_function() async {
+  Future<void> test_createChange_change_function() async {
     await indexTestUnit('''
 import 'dart:math' as test;
 import 'dart:async' as test;
@@ -158,7 +160,7 @@
 ''');
   }
 
-  test_createChange_change_onPrefixElement() async {
+  Future<void> test_createChange_change_onPrefixElement() async {
     await indexTestUnit('''
 import 'dart:async' as test;
 import 'dart:math' as test;
@@ -185,7 +187,7 @@
 ''');
   }
 
-  test_createChange_remove() async {
+  Future<void> test_createChange_remove() async {
     await indexTestUnit('''
 import 'dart:math' as test;
 import 'dart:async' as test;
@@ -208,7 +210,7 @@
 ''');
   }
 
-  test_oldName_empty() async {
+  Future<void> test_oldName_empty() async {
     await indexTestUnit('''
 import 'dart:math';
 import 'dart:async';
diff --git a/pkg/analysis_server/test/services/refactoring/rename_label_test.dart b/pkg/analysis_server/test/services/refactoring/rename_label_test.dart
index b583c5b..6ca432e 100644
--- a/pkg/analysis_server/test/services/refactoring/rename_label_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/rename_label_test.dart
@@ -8,7 +8,7 @@
 
 import 'abstract_rename.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RenameLabelTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class RenameLabelTest extends RenameRefactoringTest {
-  test_checkNewName_LocalVariableElement() async {
+  Future<void> test_checkNewName_LocalVariableElement() async {
     await indexTestUnit('''
 main() {
 test:
@@ -41,7 +41,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_createChange() async {
+  Future<void> test_createChange() async {
     await indexTestUnit('''
 main() {
 test:
@@ -66,7 +66,7 @@
 ''');
   }
 
-  test_oldName() async {
+  Future<void> test_oldName() async {
     await indexTestUnit('''
 main() {
 test:
diff --git a/pkg/analysis_server/test/services/refactoring/rename_library_test.dart b/pkg/analysis_server/test/services/refactoring/rename_library_test.dart
index 5ac2e21..38c315a 100644
--- a/pkg/analysis_server/test/services/refactoring/rename_library_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/rename_library_test.dart
@@ -8,7 +8,7 @@
 
 import 'abstract_rename.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RenameLibraryTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class RenameLibraryTest extends RenameRefactoringTest {
-  test_checkNewName() async {
+  Future<void> test_checkNewName() async {
     await indexTestUnit('''
 library my.app;
 ''');
@@ -39,7 +39,7 @@
             'The new name must be different than the current name.');
   }
 
-  test_createChange() async {
+  Future<void> test_createChange() async {
     addSource('/home/test/lib/part.dart', '''
 part of my.app;
 ''');
@@ -62,7 +62,7 @@
 ''');
   }
 
-  test_createChange_hasWhitespaces() async {
+  Future<void> test_createChange_hasWhitespaces() async {
     addSource('/home/test/lib/part.dart', '''
 part of my .  app;
 ''');
diff --git a/pkg/analysis_server/test/services/refactoring/rename_local_test.dart b/pkg/analysis_server/test/services/refactoring/rename_local_test.dart
index c677fca..0bd0de6 100644
--- a/pkg/analysis_server/test/services/refactoring/rename_local_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/rename_local_test.dart
@@ -9,7 +9,7 @@
 
 import 'abstract_rename.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RenameLocalTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class RenameLocalTest extends RenameRefactoringTest {
-  test_checkFinalConditions_hasLocalFunction_after() async {
+  Future<void> test_checkFinalConditions_hasLocalFunction_after() async {
     await indexTestUnit('''
 main() {
   int test = 0;
@@ -33,7 +33,7 @@
         expectedContextSearch: 'newName() => 1');
   }
 
-  test_checkFinalConditions_hasLocalFunction_before() async {
+  Future<void> test_checkFinalConditions_hasLocalFunction_before() async {
     await indexTestUnit('''
 main() {
   newName() => 1;
@@ -48,7 +48,7 @@
         expectedMessage: "Duplicate function 'newName'.");
   }
 
-  test_checkFinalConditions_hasLocalVariable_after() async {
+  Future<void> test_checkFinalConditions_hasLocalVariable_after() async {
     await indexTestUnit('''
 main() {
   int test = 0;
@@ -66,7 +66,7 @@
         expectedContextSearch: 'newName = 1;');
   }
 
-  test_checkFinalConditions_hasLocalVariable_before() async {
+  Future<void> test_checkFinalConditions_hasLocalVariable_before() async {
     await indexTestUnit('''
 main() {
   var newName = 1;
@@ -82,7 +82,7 @@
         expectedContextSearch: 'newName = 1;');
   }
 
-  test_checkFinalConditions_hasLocalVariable_otherBlock() async {
+  Future<void> test_checkFinalConditions_hasLocalVariable_otherBlock() async {
     await indexTestUnit('''
 main() {
   {
@@ -99,7 +99,8 @@
     return assertRefactoringConditionsOK();
   }
 
-  test_checkFinalConditions_hasLocalVariable_otherForEachLoop() async {
+  Future<void>
+      test_checkFinalConditions_hasLocalVariable_otherForEachLoop() async {
     await indexTestUnit('''
 main() {
   for (int newName in []) {}
@@ -112,7 +113,7 @@
     return assertRefactoringConditionsOK();
   }
 
-  test_checkFinalConditions_hasLocalVariable_otherForLoop() async {
+  Future<void> test_checkFinalConditions_hasLocalVariable_otherForLoop() async {
     await indexTestUnit('''
 main() {
   for (int newName = 0; newName < 10; newName++) {}
@@ -125,7 +126,8 @@
     return assertRefactoringConditionsOK();
   }
 
-  test_checkFinalConditions_hasLocalVariable_otherFunction() async {
+  Future<void>
+      test_checkFinalConditions_hasLocalVariable_otherFunction() async {
     await indexTestUnit('''
 main() {
   int test = 0;
@@ -140,7 +142,7 @@
     return assertRefactoringConditionsOK();
   }
 
-  test_checkFinalConditions_shadows_classMember() async {
+  Future<void> test_checkFinalConditions_shadows_classMember() async {
     await indexTestUnit('''
 class A {
   var newName = 1;
@@ -160,7 +162,8 @@
         expectedContextSearch: 'newName);');
   }
 
-  test_checkFinalConditions_shadows_classMember_namedParameter() async {
+  Future<void>
+      test_checkFinalConditions_shadows_classMember_namedParameter() async {
     await indexTestUnit('''
 class A {
   foo({test: 1}) { // in A
@@ -183,7 +186,8 @@
         expectedContextSearch: 'newName);');
   }
 
-  test_checkFinalConditions_shadows_classMemberOK_qualifiedReference() async {
+  Future<void>
+      test_checkFinalConditions_shadows_classMemberOK_qualifiedReference() async {
     await indexTestUnit('''
 class A {
   var newName = 1;
@@ -199,7 +203,8 @@
     return assertRefactoringConditionsOK();
   }
 
-  test_checkFinalConditions_shadows_OK_namedParameterReference() async {
+  Future<void>
+      test_checkFinalConditions_shadows_OK_namedParameterReference() async {
     await indexTestUnit('''
 void f({newName}) {}
 main() {
@@ -213,7 +218,7 @@
     return assertRefactoringFinalConditionsOK();
   }
 
-  test_checkFinalConditions_shadows_topLevelFunction() async {
+  Future<void> test_checkFinalConditions_shadows_topLevelFunction() async {
     await indexTestUnit('''
 newName() {}
 main() {
@@ -229,7 +234,7 @@
         expectedContextSearch: 'newName(); // ref');
   }
 
-  test_checkNewName_FunctionElement() async {
+  Future<void> test_checkNewName_FunctionElement() async {
     await indexTestUnit('''
 main() {
   int test() => 0;
@@ -246,7 +251,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_checkNewName_LocalVariableElement() async {
+  Future<void> test_checkNewName_LocalVariableElement() async {
     await indexTestUnit('''
 main() {
   int test = 0;
@@ -268,7 +273,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_checkNewName_ParameterElement() async {
+  Future<void> test_checkNewName_ParameterElement() async {
     await indexTestUnit('''
 main(test) {
 }
@@ -284,7 +289,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_createChange_localFunction() async {
+  Future<void> test_createChange_localFunction() async {
     await indexTestUnit('''
 main() {
   int test() => 0;
@@ -307,7 +312,8 @@
 ''');
   }
 
-  test_createChange_localFunction_sameNameDifferenceScopes() async {
+  Future<void>
+      test_createChange_localFunction_sameNameDifferenceScopes() async {
     await indexTestUnit('''
 main() {
   {
@@ -347,7 +353,7 @@
 ''');
   }
 
-  test_createChange_localVariable() async {
+  Future<void> test_createChange_localVariable() async {
     await indexTestUnit('''
 main() {
   int test = 0;
@@ -372,7 +378,8 @@
 ''');
   }
 
-  test_createChange_localVariable_sameNameDifferenceScopes() async {
+  Future<void>
+      test_createChange_localVariable_sameNameDifferenceScopes() async {
     await indexTestUnit('''
 main() {
   {
@@ -412,7 +419,7 @@
 ''');
   }
 
-  test_createChange_parameter_named() async {
+  Future<void> test_createChange_parameter_named() async {
     await indexTestUnit('''
 myFunction({int test}) {
   test = 1;
@@ -441,7 +448,7 @@
 ''');
   }
 
-  test_createChange_parameter_named_inOtherFile() async {
+  Future<void> test_createChange_parameter_named_inOtherFile() async {
     var a = convertPath('/home/test/lib/a.dart');
     var b = convertPath('/home/test/lib/b.dart');
 
@@ -484,7 +491,7 @@
 ''');
   }
 
-  test_createChange_parameter_named_updateHierarchy() async {
+  Future<void> test_createChange_parameter_named_updateHierarchy() async {
     await indexUnit('/home/test/lib/test2.dart', '''
 library test2;
 class A {
@@ -544,7 +551,7 @@
 ''');
   }
 
-  test_createChange_parameter_optionalPositional() async {
+  Future<void> test_createChange_parameter_optionalPositional() async {
     await indexTestUnit('''
 myFunction([int test]) {
   test = 1;
@@ -573,7 +580,7 @@
 ''');
   }
 
-  test_oldName() async {
+  Future<void> test_oldName() async {
     await indexTestUnit('''
 main() {
   int test = 0;
diff --git a/pkg/analysis_server/test/services/refactoring/rename_unit_member_test.dart b/pkg/analysis_server/test/services/refactoring/rename_unit_member_test.dart
index c075d62..d78f249 100644
--- a/pkg/analysis_server/test/services/refactoring/rename_unit_member_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/rename_unit_member_test.dart
@@ -9,7 +9,7 @@
 
 import 'abstract_rename.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RenameUnitMemberTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class RenameUnitMemberTest extends RenameRefactoringTest {
-  test_checkFinalConditions_hasTopLevel_ClassElement() async {
+  Future<void> test_checkFinalConditions_hasTopLevel_ClassElement() async {
     await indexTestUnit('''
 class Test {}
 class NewName {} // existing
@@ -31,7 +31,8 @@
         expectedContextSearch: 'NewName {} // existing');
   }
 
-  test_checkFinalConditions_hasTopLevel_FunctionTypeAliasElement() async {
+  Future<void>
+      test_checkFinalConditions_hasTopLevel_FunctionTypeAliasElement() async {
     await indexTestUnit('''
 class Test {}
 typedef NewName(); // existing
@@ -46,7 +47,8 @@
         expectedContextSearch: 'NewName(); // existing');
   }
 
-  test_checkFinalConditions_OK_qualifiedSuper_MethodElement() async {
+  Future<void>
+      test_checkFinalConditions_OK_qualifiedSuper_MethodElement() async {
     await indexTestUnit('''
 class Test {}
 class A {
@@ -65,7 +67,8 @@
     assertRefactoringStatusOK(status);
   }
 
-  test_checkFinalConditions_publicToPrivate_usedInOtherLibrary() async {
+  Future<void>
+      test_checkFinalConditions_publicToPrivate_usedInOtherLibrary() async {
     await indexTestUnit('''
 class Test {}
 ''');
@@ -85,7 +88,7 @@
         expectedMessage: "Renamed class will be invisible in 'my.lib'.");
   }
 
-  test_checkFinalConditions_shadowedBy_MethodElement() async {
+  Future<void> test_checkFinalConditions_shadowedBy_MethodElement() async {
     await indexTestUnit('''
 class Test {}
 class A {
@@ -105,7 +108,7 @@
         expectedContextSearch: 'NewName() {}');
   }
 
-  test_checkFinalConditions_shadowsInSubClass_importedLib() async {
+  Future<void> test_checkFinalConditions_shadowsInSubClass_importedLib() async {
     await indexTestUnit('''
 class Test {}
 ''');
@@ -129,7 +132,8 @@
         expectedMessage: "Renamed class will shadow method 'A.NewName'.");
   }
 
-  test_checkFinalConditions_shadowsInSubClass_importedLib_hideCombinator() async {
+  Future<void>
+      test_checkFinalConditions_shadowsInSubClass_importedLib_hideCombinator() async {
     await indexTestUnit('''
 class Test {}
 ''');
@@ -152,7 +156,8 @@
     assertRefactoringStatusOK(status);
   }
 
-  test_checkFinalConditions_shadowsInSubClass_MethodElement() async {
+  Future<void>
+      test_checkFinalConditions_shadowsInSubClass_MethodElement() async {
     await indexTestUnit('''
 class Test {}
 class A {
@@ -173,7 +178,8 @@
         expectedContextSearch: 'NewName(); // super-ref');
   }
 
-  test_checkFinalConditions_shadowsInSubClass_notImportedLib() async {
+  Future<void>
+      test_checkFinalConditions_shadowsInSubClass_notImportedLib() async {
     await indexUnit('/lib.dart', '''
 library my.lib;
 class A {
@@ -195,7 +201,7 @@
     assertRefactoringStatusOK(status);
   }
 
-  test_checkFinalConditions_shadowsInSubClass_notSubClass() async {
+  Future<void> test_checkFinalConditions_shadowsInSubClass_notSubClass() async {
     await indexTestUnit('''
 class Test {}
 class A {
@@ -214,7 +220,7 @@
     assertRefactoringStatusOK(status);
   }
 
-  test_checkInitialConditions_inSDK() async {
+  Future<void> test_checkInitialConditions_inSDK() async {
     await indexTestUnit('''
 main() {
   String s;
@@ -229,7 +235,7 @@
             "The class 'String' is defined in the SDK, so cannot be renamed.");
   }
 
-  test_checkInitialConditions_outsideOfProject() async {
+  Future<void> test_checkInitialConditions_outsideOfProject() async {
     addPackageFile('aaa', 'lib.dart', r'''
 class A {}
 ''');
@@ -248,7 +254,7 @@
             "The class 'A' is defined outside of the project, so cannot be renamed.");
   }
 
-  test_checkNewName_ClassElement() async {
+  Future<void> test_checkNewName_ClassElement() async {
     await indexTestUnit('''
 class Test {}
 ''');
@@ -274,7 +280,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_checkNewName_FunctionElement() async {
+  Future<void> test_checkNewName_FunctionElement() async {
     await indexTestUnit('''
 test() {}
 ''');
@@ -294,7 +300,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_checkNewName_FunctionTypeAliasElement() async {
+  Future<void> test_checkNewName_FunctionTypeAliasElement() async {
     await indexTestUnit('''
 typedef Test();
 ''');
@@ -309,7 +315,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_checkNewName_TopLevelVariableElement() async {
+  Future<void> test_checkNewName_TopLevelVariableElement() async {
     await indexTestUnit('''
 var test;
 ''');
@@ -329,7 +335,7 @@
     assertRefactoringStatusOK(refactoring.checkNewName());
   }
 
-  test_createChange_ClassElement() async {
+  Future<void> test_createChange_ClassElement() async {
     await indexTestUnit('''
 class Test implements Other {
   Test() {}
@@ -367,7 +373,7 @@
 ''');
   }
 
-  test_createChange_ClassElement_flutterWidget() async {
+  Future<void> test_createChange_ClassElement_flutterWidget() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -408,7 +414,8 @@
 ''');
   }
 
-  test_createChange_ClassElement_flutterWidget_privateBoth() async {
+  Future<void>
+      test_createChange_ClassElement_flutterWidget_privateBoth() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -449,7 +456,8 @@
 ''');
   }
 
-  test_createChange_ClassElement_flutterWidget_privateState() async {
+  Future<void>
+      test_createChange_ClassElement_flutterWidget_privateState() async {
     addFlutterPackage();
     await indexTestUnit('''
 import 'package:flutter/material.dart';
@@ -490,7 +498,7 @@
 ''');
   }
 
-  test_createChange_ClassElement_invocation() async {
+  Future<void> test_createChange_ClassElement_invocation() async {
     verifyNoTestUnitErrors = false;
     await indexTestUnit('''
 class Test {
@@ -515,7 +523,7 @@
 ''');
   }
 
-  test_createChange_ClassElement_parameterTypeNested() async {
+  Future<void> test_createChange_ClassElement_parameterTypeNested() async {
     await indexTestUnit('''
 class Test {
 }
@@ -536,7 +544,7 @@
 ''');
   }
 
-  test_createChange_ClassElement_typeAlias() async {
+  Future<void> test_createChange_ClassElement_typeAlias() async {
     await indexTestUnit('''
 class A {}
 class Test = Object with A;
@@ -558,7 +566,7 @@
 ''');
   }
 
-  test_createChange_FunctionElement() async {
+  Future<void> test_createChange_FunctionElement() async {
     await indexTestUnit('''
 test() {}
 foo() {}
@@ -586,7 +594,7 @@
 ''');
   }
 
-  test_createChange_FunctionElement_imported() async {
+  Future<void> test_createChange_FunctionElement_imported() async {
     await indexUnit('/home/test/lib/foo.dart', r'''
 test() {}
 foo() {}
@@ -620,7 +628,7 @@
 ''');
   }
 
-  test_createChange_FunctionTypeAliasElement() async {
+  Future<void> test_createChange_FunctionTypeAliasElement() async {
     await indexTestUnit('''
 typedef void F();
 void foo<T>() {}
@@ -644,7 +652,7 @@
 ''');
   }
 
-  test_createChange_outsideOfProject_referenceInPart() async {
+  Future<void> test_createChange_outsideOfProject_referenceInPart() async {
     newFile('/home/part.dart', content: r'''
 part of test;
 
@@ -680,43 +688,45 @@
     expect(refactoringChange.edits[0].file, testFile);
   }
 
-  test_createChange_PropertyAccessorElement_getter_declaration() async {
+  Future<void>
+      test_createChange_PropertyAccessorElement_getter_declaration() async {
     await _test_createChange_PropertyAccessorElement('test {}');
   }
 
-  test_createChange_PropertyAccessorElement_getter_usage() async {
+  Future<void> test_createChange_PropertyAccessorElement_getter_usage() async {
     await _test_createChange_PropertyAccessorElement('test);');
   }
 
-  test_createChange_PropertyAccessorElement_mix() async {
+  Future<void> test_createChange_PropertyAccessorElement_mix() async {
     await _test_createChange_PropertyAccessorElement('test += 2');
   }
 
-  test_createChange_PropertyAccessorElement_setter_declaration() async {
+  Future<void>
+      test_createChange_PropertyAccessorElement_setter_declaration() async {
     await _test_createChange_PropertyAccessorElement('test(x) {}');
   }
 
-  test_createChange_PropertyAccessorElement_setter_usage() async {
+  Future<void> test_createChange_PropertyAccessorElement_setter_usage() async {
     await _test_createChange_PropertyAccessorElement('test = 1');
   }
 
-  test_createChange_TopLevelVariableElement_field() async {
+  Future<void> test_createChange_TopLevelVariableElement_field() async {
     await _test_createChange_TopLevelVariableElement('test = 0');
   }
 
-  test_createChange_TopLevelVariableElement_getter() async {
+  Future<void> test_createChange_TopLevelVariableElement_getter() async {
     await _test_createChange_TopLevelVariableElement('test);');
   }
 
-  test_createChange_TopLevelVariableElement_mix() async {
+  Future<void> test_createChange_TopLevelVariableElement_mix() async {
     await _test_createChange_TopLevelVariableElement('test += 2');
   }
 
-  test_createChange_TopLevelVariableElement_setter() async {
+  Future<void> test_createChange_TopLevelVariableElement_setter() async {
     await _test_createChange_TopLevelVariableElement('test = 1');
   }
 
-  _test_createChange_PropertyAccessorElement(String search) async {
+  Future<void> _test_createChange_PropertyAccessorElement(String search) async {
     await indexTestUnit('''
 get test {}
 set test(x) {}
@@ -743,7 +753,7 @@
 ''');
   }
 
-  _test_createChange_TopLevelVariableElement(String search) async {
+  Future<void> _test_createChange_TopLevelVariableElement(String search) async {
     await indexTestUnit('''
 int test = 0;
 main() {
diff --git a/pkg/analysis_server/test/services/refactoring/test_all.dart b/pkg/analysis_server/test/services/refactoring/test_all.dart
index 17ce7af..d48e879 100644
--- a/pkg/analysis_server/test/services/refactoring/test_all.dart
+++ b/pkg/analysis_server/test/services/refactoring/test_all.dart
@@ -22,8 +22,7 @@
 import 'rename_local_test.dart' as rename_local_test;
 import 'rename_unit_member_test.dart' as rename_unit_member_test;
 
-/// Utility for manually running all tests.
-main() {
+void main() {
   defineReflectiveSuite(() {
     convert_getter_to_method_test.main();
     convert_method_to_getter_test.main();
diff --git a/pkg/analysis_server/test/services/search/element_visitors_test.dart b/pkg/analysis_server/test/services/search/element_visitors_test.dart
index 5739ea8..11d8bc7 100644
--- a/pkg/analysis_server/test/services/search/element_visitors_test.dart
+++ b/pkg/analysis_server/test/services/search/element_visitors_test.dart
@@ -9,7 +9,7 @@
 
 import '../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FindElementByNameOffsetTest);
   });
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class FindElementByNameOffsetTest extends AbstractSingleUnitTest {
-  test_class() async {
+  Future<void> test_class() async {
     await resolveTestUnit(r'''
 class AAA {}
 class BBB {}
@@ -26,7 +26,7 @@
     _assertElement(19, ElementKind.CLASS, 'BBB');
   }
 
-  test_function() async {
+  Future<void> test_function() async {
     await resolveTestUnit(r'''
 void aaa() {}
 void bbb() {}
@@ -35,7 +35,7 @@
     _assertElement(19, ElementKind.FUNCTION, 'bbb');
   }
 
-  test_null() async {
+  Future<void> test_null() async {
     await resolveTestUnit(r'''
 class AAA {}
 class BBB {}
@@ -49,7 +49,7 @@
     expect(findElementByNameOffset(testUnitElement, 7), isNull);
   }
 
-  test_topLevelVariable() async {
+  Future<void> test_topLevelVariable() async {
     await resolveTestUnit(r'''
 int aaa, bbb;
 int ccc;
diff --git a/pkg/analysis_server/test/services/search/hierarchy_test.dart b/pkg/analysis_server/test/services/search/hierarchy_test.dart
index 252bd3f..333b02a 100644
--- a/pkg/analysis_server/test/services/search/hierarchy_test.dart
+++ b/pkg/analysis_server/test/services/search/hierarchy_test.dart
@@ -12,7 +12,7 @@
 
 import '../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(HierarchyTest);
   });
@@ -28,7 +28,7 @@
     searchEngine = SearchEngineImpl([driver]);
   }
 
-  test_getClassMembers() async {
+  Future<void> test_getClassMembers() async {
     await _indexTestUnit('''
 class A {
   A() {}
@@ -54,7 +54,7 @@
     }
   }
 
-  test_getHierarchyMembers_constructors() async {
+  Future<void> test_getHierarchyMembers_constructors() async {
     await _indexTestUnit('''
 class A {
   A() {}
@@ -76,7 +76,7 @@
     return Future.wait([futureA, futureB]);
   }
 
-  test_getHierarchyMembers_fields() async {
+  Future<void> test_getHierarchyMembers_fields() async {
     await _indexTestUnit('''
 class A {
   int foo;
@@ -114,7 +114,7 @@
     return Future.wait([futureA, futureB, futureC, futureD]);
   }
 
-  test_getHierarchyMembers_fields_static() async {
+  Future<void> test_getHierarchyMembers_fields_static() async {
     await _indexTestUnit('''
 class A {
   static int foo;
@@ -149,7 +149,7 @@
     }
   }
 
-  test_getHierarchyMembers_methods() async {
+  Future<void> test_getHierarchyMembers_methods() async {
     await _indexTestUnit('''
 class A {
   foo() {}
@@ -195,7 +195,7 @@
     return Future.wait([futureA, futureB, futureC, futureD, futureE]);
   }
 
-  test_getHierarchyMembers_methods_static() async {
+  Future<void> test_getHierarchyMembers_methods_static() async {
     await _indexTestUnit('''
 class A {
   static foo() {}
@@ -220,7 +220,7 @@
     }
   }
 
-  test_getHierarchyMembers_withInterfaces() async {
+  Future<void> test_getHierarchyMembers_withInterfaces() async {
     await _indexTestUnit('''
 class A {
   foo() {}
@@ -255,7 +255,7 @@
     return Future.wait([futureA, futureB, futureD]);
   }
 
-  test_getHierarchyNamedParameters() async {
+  Future<void> test_getHierarchyNamedParameters() async {
     await _indexTestUnit('''
 class A {
   foo({p}) {}
@@ -310,7 +310,7 @@
     }
   }
 
-  test_getHierarchyNamedParameters_invalid_missing() async {
+  Future<void> test_getHierarchyNamedParameters_invalid_missing() async {
     verifyNoTestUnitErrors = false;
     await _indexTestUnit('''
 class A {
@@ -327,7 +327,7 @@
     expect(result, unorderedEquals([parameterA]));
   }
 
-  test_getHierarchyNamedParameters_invalid_notNamed() async {
+  Future<void> test_getHierarchyNamedParameters_invalid_notNamed() async {
     verifyNoTestUnitErrors = false;
     await _indexTestUnit('''
 class A {
@@ -344,7 +344,7 @@
     expect(result, unorderedEquals([parameterA]));
   }
 
-  test_getMembers() async {
+  Future<void> test_getMembers() async {
     await _indexTestUnit('''
 class A {
   A() {}
@@ -392,7 +392,7 @@
     }
   }
 
-  test_getSuperClasses() async {
+  Future<void> test_getSuperClasses() async {
     await _indexTestUnit('''
 class A {}
 class B extends A {}
@@ -446,7 +446,7 @@
     }
   }
 
-  test_getSuperClasses_superclassConstraints() async {
+  Future<void> test_getSuperClasses_superclassConstraints() async {
     await _indexTestUnit('''
 class A {}
 class B extends A {}
diff --git a/pkg/analysis_server/test/services/search/search_engine_test.dart b/pkg/analysis_server/test/services/search/search_engine_test.dart
index 96f9cd2..c46b81f 100644
--- a/pkg/analysis_server/test/services/search/search_engine_test.dart
+++ b/pkg/analysis_server/test/services/search/search_engine_test.dart
@@ -21,7 +21,7 @@
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SearchEngineImplTest);
   });
@@ -45,7 +45,7 @@
     scheduler.start();
   }
 
-  test_membersOfSubtypes_hasMembers() async {
+  Future<void> test_membersOfSubtypes_hasMembers() async {
     var a = newFile('/test/a.dart', content: '''
 class A {
   void a() {}
@@ -82,7 +82,7 @@
     expect(members, unorderedEquals(['a', 'b']));
   }
 
-  test_membersOfSubtypes_noMembers() async {
+  Future<void> test_membersOfSubtypes_noMembers() async {
     var a = newFile('/test/a.dart', content: '''
 class A {
   void a() {}
@@ -109,7 +109,7 @@
     expect(members, isEmpty);
   }
 
-  test_membersOfSubtypes_noSubtypes() async {
+  Future<void> test_membersOfSubtypes_noSubtypes() async {
     var a = newFile('/test/a.dart', content: '''
 class A {
   void a() {}
@@ -138,7 +138,7 @@
     expect(members, isNull);
   }
 
-  test_membersOfSubtypes_private() async {
+  Future<void> test_membersOfSubtypes_private() async {
     var a = newFile('/test/a.dart', content: '''
 class A {
   void a() {}
@@ -175,7 +175,7 @@
     expect(members, unorderedEquals(['a', '_b']));
   }
 
-  test_searchAllSubtypes() async {
+  Future<void> test_searchAllSubtypes() async {
     var p = newFile('/test.dart', content: '''
 class T {}
 class A extends T {}
@@ -197,7 +197,7 @@
     _assertContainsClass(subtypes, 'C');
   }
 
-  test_searchAllSubtypes_acrossDrivers() async {
+  Future<void> test_searchAllSubtypes_acrossDrivers() async {
     var a = newFile('/test/a.dart', content: '''
 class T {}
 class A extends T {}
@@ -225,7 +225,7 @@
     expect(subtypes, contains(predicate((ClassElement e) => e.name == 'C')));
   }
 
-  test_searchAllSubtypes_mixin() async {
+  Future<void> test_searchAllSubtypes_mixin() async {
     var p = newFile('/test.dart', content: '''
 class T {}
 
@@ -254,7 +254,7 @@
     _assertContainsClass(subtypes, 'E');
   }
 
-  test_searchMemberDeclarations() async {
+  Future<void> test_searchMemberDeclarations() async {
     var codeA = '''
 class A {
   int test; // 1
@@ -300,7 +300,7 @@
     assertHasElement('test', codeB.indexOf('test() {} // 2'));
   }
 
-  test_searchMemberReferences() async {
+  Future<void> test_searchMemberReferences() async {
     var a = newFile('/test/a.dart', content: '''
 class A {
   int test;
@@ -336,7 +336,7 @@
             m.element.name == 'bar' || m.kind == MatchKind.WRITE)));
   }
 
-  test_searchReferences() async {
+  Future<void> test_searchReferences() async {
     var a = newFile('/test/a.dart', content: '''
 class T {}
 T a;
@@ -364,7 +364,7 @@
         matches, contains(predicate((SearchMatch m) => m.element.name == 'b')));
   }
 
-  test_searchReferences_discover_owned() async {
+  Future<void> test_searchReferences_discover_owned() async {
     var t = newFile('/test/lib/t.dart', content: '''
 import 'package:aaa/a.dart';
 int t;
@@ -396,7 +396,7 @@
     assertHasOne(a, 'a');
   }
 
-  test_searchTopLevelDeclarations() async {
+  Future<void> test_searchTopLevelDeclarations() async {
     var a = newFile('/test/a.dart', content: '''
 class A {}
 int a;
@@ -433,7 +433,7 @@
     assertHasOneElement('b');
   }
 
-  test_searchTopLevelDeclarations_dependentPackage() async {
+  Future<void> test_searchTopLevelDeclarations_dependentPackage() async {
     var a = newFile('/a/lib/a.dart', content: '''
 class A {}
 ''').path;
diff --git a/pkg/analysis_server/test/services/search/test_all.dart b/pkg/analysis_server/test/services/search/test_all.dart
index 63d9465..c3f8f91 100644
--- a/pkg/analysis_server/test/services/search/test_all.dart
+++ b/pkg/analysis_server/test/services/search/test_all.dart
@@ -8,10 +8,7 @@
 import 'hierarchy_test.dart' as hierarchy_test;
 import 'search_engine_test.dart' as search_engine_test;
 
-/**
- * Utility for manually running all tests.
- */
-main() {
+void main() {
   defineReflectiveSuite(() {
     element_visitors.main();
     hierarchy_test.main();
diff --git a/pkg/analysis_server/test/services/test_all.dart b/pkg/analysis_server/test/services/test_all.dart
index 76edf82..954023d 100644
--- a/pkg/analysis_server/test/services/test_all.dart
+++ b/pkg/analysis_server/test/services/test_all.dart
@@ -10,7 +10,7 @@
 import 'refactoring/test_all.dart' as refactoring_all;
 import 'search/test_all.dart' as search_all;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     completion_all.main();
     correction_all.main();
diff --git a/pkg/analysis_server/test/socket_server_test.dart b/pkg/analysis_server/test/socket_server_test.dart
index e418a67..85d8c45 100644
--- a/pkg/analysis_server/test/socket_server_test.dart
+++ b/pkg/analysis_server/test/socket_server_test.dart
@@ -15,7 +15,7 @@
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:test/test.dart';
 
-main() {
+void main() {
   group('SocketServer', () {
     test('createAnalysisServer_successful',
         SocketServerTest.createAnalysisServer_successful);
diff --git a/pkg/analysis_server/test/src/computer/closing_labels_computer_test.dart b/pkg/analysis_server/test/src/computer/closing_labels_computer_test.dart
index 2304e90..b3783bb 100644
--- a/pkg/analysis_server/test/src/computer/closing_labels_computer_test.dart
+++ b/pkg/analysis_server/test/src/computer/closing_labels_computer_test.dart
@@ -12,7 +12,7 @@
 
 import '../../abstract_context.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ClosingLabelsComputerTest);
   });
@@ -23,12 +23,12 @@
   String sourcePath;
 
   @override
-  setUp() {
+  void setUp() {
     super.setUp();
     sourcePath = convertPath('/home/test/lib/test.dart');
   }
 
-  test_adjacentLinesExcluded() async {
+  Future<void> test_adjacentLinesExcluded() async {
     String content = '''
 void myMethod() {
   return /*1*/new Wrapper(
@@ -45,7 +45,7 @@
   /// When constructors span many like this, the node's start position is on the first line
   /// of the expression and not where the opening paren is, so this test ensures we
   /// don't end up with lots of unwanted labels on each line here.
-  test_chainedConstructorOverManyLines() async {
+  Future<void> test_chainedConstructorOverManyLines() async {
     String content = '''
 main() {
   return new thing
@@ -61,7 +61,7 @@
   /// When chaining methods like this, the node's start position is on the first line
   /// of the expression and not where the opening paren is, so this test ensures we
   /// don't end up with lots of unwanted labels on each line here.
-  test_chainedMethodsOverManyLines() async {
+  Future<void> test_chainedMethodsOverManyLines() async {
     String content = '''
 List<ClosingLabel> compute() {
   _unit.accept(new _DartUnitClosingLabelsComputerVisitor(this));
@@ -77,7 +77,7 @@
     _compareLabels(labels, content, expectedLabelCount: 0);
   }
 
-  test_constConstructor() async {
+  Future<void> test_constConstructor() async {
     String content = '''
 void myMethod() {
   return /*1*/new Wrapper(
@@ -93,7 +93,7 @@
     _compareLabels(labels, content, expectedLabelCount: 2);
   }
 
-  test_constNamedConstructor() async {
+  Future<void> test_constNamedConstructor() async {
     String content = '''
 void myMethod() {
   return /*1*/new Wrapper(
@@ -109,7 +109,7 @@
     _compareLabels(labels, content, expectedLabelCount: 2);
   }
 
-  test_knownBadCode1() async {
+  Future<void> test_knownBadCode1() async {
     // This code crashed during testing when I accidentally inserted a test snippet.
     String content = """
 @override
@@ -138,7 +138,7 @@
     await _computeElements(content);
   }
 
-  test_labelsShownForMultipleElements() async {
+  Future<void> test_labelsShownForMultipleElements() async {
     String content = '''
 Widget build(BuildContext context) {
   return /*1*/new Row(
@@ -151,7 +151,7 @@
     _compareLabels(labels, content, expectedLabelCount: 1);
   }
 
-  test_labelsShownForMultipleElements_2() async {
+  Future<void> test_labelsShownForMultipleElements_2() async {
     String content = '''
 Widget build(BuildContext context) {
   return /*1*/new Row(
@@ -166,7 +166,7 @@
     _compareLabels(labels, content, expectedLabelCount: 2);
   }
 
-  test_listLiterals() async {
+  Future<void> test_listLiterals() async {
     String content = '''
 void myMethod() {
   return /*1*/new Wrapper(
@@ -185,7 +185,7 @@
   /// When a line contains the end of a label, we need to ensure we also include any
   /// other labels that end on the same line, even if they are 1-2 lines, otherwise
   /// it isn't obvious which closing bracket goes with the label.
-  test_mixedLineSpanning() async {
+  Future<void> test_mixedLineSpanning() async {
     String content = '''
 main() {
     /*1*/new Foo((m) {
@@ -202,7 +202,7 @@
     _compareLabels(labels, content, expectedLabelCount: 3);
   }
 
-  test_multipleNested() async {
+  Future<void> test_multipleNested() async {
     String content = """
 Widget build(BuildContext context) {
   return /*1*/new Row(
@@ -226,7 +226,7 @@
     _compareLabels(labels, content, expectedLabelCount: 4);
   }
 
-  test_newConstructor() async {
+  Future<void> test_newConstructor() async {
     String content = '''
 void myMethod() {
   return /*1*/new Wrapper(
@@ -242,7 +242,7 @@
     _compareLabels(labels, content, expectedLabelCount: 2);
   }
 
-  test_newNamedConstructor() async {
+  Future<void> test_newNamedConstructor() async {
     String content = '''
 void myMethod() {
   return /*1*/new Wrapper(
@@ -258,7 +258,7 @@
     _compareLabels(labels, content, expectedLabelCount: 2);
   }
 
-  test_noLabelsForOneElement() async {
+  Future<void> test_noLabelsForOneElement() async {
     String content = '''
 Widget build(BuildContext context) {
   return new Row(
@@ -270,7 +270,7 @@
     _compareLabels(labels, content, expectedLabelCount: 0);
   }
 
-  test_NoLabelsFromInterpolatedStrings() async {
+  Future<void> test_NoLabelsFromInterpolatedStrings() async {
     String content = """
 void main(HighlightRegionType type, int offset, int length) {
   /*1*/new Wrapper(
@@ -285,7 +285,7 @@
     _compareLabels(labels, content, expectedLabelCount: 2);
   }
 
-  test_prefixedConstConstructor() async {
+  Future<void> test_prefixedConstConstructor() async {
     String content = """
 import 'dart:async' as a;
 void myMethod() {
@@ -302,7 +302,7 @@
     _compareLabels(labels, content, expectedLabelCount: 2);
   }
 
-  test_prefixedConstNamedConstructor() async {
+  Future<void> test_prefixedConstNamedConstructor() async {
     String content = """
 import 'dart:async' as a;
 void myMethod() {
@@ -319,7 +319,7 @@
     _compareLabels(labels, content, expectedLabelCount: 2);
   }
 
-  test_prefixedNewConstructor() async {
+  Future<void> test_prefixedNewConstructor() async {
     String content = """
 import 'dart:async' as a;
 void myMethod() {
@@ -336,7 +336,7 @@
     _compareLabels(labels, content, expectedLabelCount: 2);
   }
 
-  test_prefixedNewNamedConstructor() async {
+  Future<void> test_prefixedNewNamedConstructor() async {
     String content = """
 import 'dart:async' as a;
 void myMethod() {
@@ -353,7 +353,7 @@
     _compareLabels(labels, content, expectedLabelCount: 2);
   }
 
-  test_sameLineExcluded() async {
+  Future<void> test_sameLineExcluded() async {
     String content = '''
 void myMethod() {
   return new Thing();
diff --git a/pkg/analysis_server/test/src/computer/folding_computer_test.dart b/pkg/analysis_server/test/src/computer/folding_computer_test.dart
index bec25b0..fbe1015 100644
--- a/pkg/analysis_server/test/src/computer/folding_computer_test.dart
+++ b/pkg/analysis_server/test/src/computer/folding_computer_test.dart
@@ -12,7 +12,7 @@
 
 import '../../abstract_context.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FoldingComputerTest);
   });
@@ -23,12 +23,12 @@
   String sourcePath;
 
   @override
-  setUp() {
+  void setUp() {
     super.setUp();
     sourcePath = convertPath('/home/test/lib/test.dart');
   }
 
-  test_annotations() async {
+  Future<void> test_annotations() async {
     String content = '''
 @myMultilineAnnotation/*1:INC*/(
   "this",
@@ -79,7 +79,7 @@
     _compareRegions(regions, content);
   }
 
-  test_assertInitializer() async {
+  Future<void> test_assertInitializer() async {
     String content = '''
 class C {/*1:INC*/
   C() : assert(/*2:INC*/
@@ -92,7 +92,7 @@
     _compareRegions(regions, content);
   }
 
-  test_assertStatement() async {
+  Future<void> test_assertStatement() async {
     String content = '''
 main() {/*1:INC*/
   assert(/*2:INC*/
@@ -105,7 +105,7 @@
     _compareRegions(regions, content);
   }
 
-  test_class() async {
+  Future<void> test_class() async {
     String content = '''
 // Content before
 
@@ -126,7 +126,7 @@
     _compareRegions(regions, content);
   }
 
-  test_comment_is_not_considered_file_header() async {
+  Future<void> test_comment_is_not_considered_file_header() async {
     String content = """
 // This is not the file header
 // It's just a comment
@@ -139,7 +139,7 @@
     expect(regions, hasLength(0));
   }
 
-  test_constructor_invocations() async {
+  Future<void> test_constructor_invocations() async {
     String content = '''
 // Content before
 
@@ -156,7 +156,7 @@
     _compareRegions(regions, content);
   }
 
-  test_file_header() async {
+  Future<void> test_file_header() async {
     String content = """
 // Copyright some year by some people/*1:EXC*/
 // See LICENCE etc./*1:INC:FILE_HEADER*/
@@ -170,7 +170,7 @@
     _compareRegions(regions, content);
   }
 
-  test_file_header_does_not_include_block_comments() async {
+  Future<void> test_file_header_does_not_include_block_comments() async {
     String content = """
 /*
  * Copyright some year by some people
@@ -185,7 +185,7 @@
     expect(regions, hasLength(0));
   }
 
-  test_file_header_with_no_function_comment() async {
+  Future<void> test_file_header_with_no_function_comment() async {
     String content = '''
 // Copyright some year by some people/*1:EXC*/
 // See LICENCE etc./*1:INC:FILE_HEADER*/
@@ -197,7 +197,7 @@
     _compareRegions(regions, content);
   }
 
-  test_file_header_with_non_end_of_line_comment() async {
+  Future<void> test_file_header_with_non_end_of_line_comment() async {
     String content = """
 // Copyright some year by some people/*1:EXC*/
 // See LICENCE etc./*1:INC:FILE_HEADER*/
@@ -210,7 +210,7 @@
     _compareRegions(regions, content);
   }
 
-  test_file_header_with_script_prefix() async {
+  Future<void> test_file_header_with_script_prefix() async {
     String content = """
 #! /usr/bin/dart
 // Copyright some year by some people/*1:EXC*/
@@ -225,7 +225,7 @@
     _compareRegions(regions, content);
   }
 
-  test_function() async {
+  Future<void> test_function() async {
     String content = '''
 // Content before
 
@@ -240,7 +240,7 @@
     _compareRegions(regions, content);
   }
 
-  test_function_expression_invocation() async {
+  Future<void> test_function_expression_invocation() async {
     String content = '''
 // Content before
 
@@ -262,7 +262,7 @@
     _compareRegions(regions, content);
   }
 
-  test_function_with_dart_doc() async {
+  Future<void> test_function_with_dart_doc() async {
     String content = '''
 // Content before
 
@@ -279,7 +279,7 @@
     _compareRegions(regions, content);
   }
 
-  test_invocations() async {
+  Future<void> test_invocations() async {
     String content = '''
 // Content before
 
@@ -296,7 +296,7 @@
     _compareRegions(regions, content);
   }
 
-  test_literal_list() async {
+  Future<void> test_literal_list() async {
     String content = '''
 // Content before
 
@@ -314,7 +314,7 @@
     _compareRegions(regions, content);
   }
 
-  test_literal_map() async {
+  Future<void> test_literal_map() async {
     String content = '''
 // Content before
 
@@ -332,7 +332,7 @@
     _compareRegions(regions, content);
   }
 
-  test_mixin() async {
+  Future<void> test_mixin() async {
     String content = '''
 // Content before
 
@@ -349,7 +349,7 @@
     _compareRegions(regions, content);
   }
 
-  test_multiple_directive_types() async {
+  Future<void> test_multiple_directive_types() async {
     String content = """
 import/*1:INC*/ 'dart:async';
 
@@ -366,7 +366,7 @@
     _compareRegions(regions, content);
   }
 
-  test_multiple_import_directives() async {
+  Future<void> test_multiple_import_directives() async {
     String content = """
 import/*1:INC*/ 'dart:async';
 
@@ -383,7 +383,7 @@
     _compareRegions(regions, content);
   }
 
-  test_nested_function() async {
+  Future<void> test_nested_function() async {
     String content = '''
 // Content before
 
@@ -401,7 +401,7 @@
     _compareRegions(regions, content);
   }
 
-  test_nested_invocations() async {
+  Future<void> test_nested_invocations() async {
     String content = '''
 // Content before
 
@@ -422,7 +422,7 @@
     _compareRegions(regions, content);
   }
 
-  test_single_import_directives() async {
+  Future<void> test_single_import_directives() async {
     String content = """
 import 'dart:async';
 
diff --git a/pkg/analysis_server/test/src/computer/highlights2_computer_test.dart b/pkg/analysis_server/test/src/computer/highlights2_computer_test.dart
index 84e1537..6579b8d 100644
--- a/pkg/analysis_server/test/src/computer/highlights2_computer_test.dart
+++ b/pkg/analysis_server/test/src/computer/highlights2_computer_test.dart
@@ -12,7 +12,7 @@
 
 import '../../abstract_context.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(Highlights2ComputerTest);
   });
@@ -25,12 +25,12 @@
   List<HighlightRegion> highlights;
 
   @override
-  setUp() {
+  void setUp() {
     super.setUp();
     sourcePath = convertPath('/home/test/lib/test.dart');
   }
 
-  test_extension() async {
+  Future<void> test_extension() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     await _computeHighlights('''
 extension E on String {}
@@ -39,7 +39,7 @@
     _check(HighlightRegionType.BUILT_IN, 'on');
   }
 
-  test_methodInvocation_ofExtensionOverride_unresolved() async {
+  Future<void> test_methodInvocation_ofExtensionOverride_unresolved() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     await _computeHighlights('''
 extension E on int {}
@@ -51,12 +51,12 @@
     _check(HighlightRegionType.IDENTIFIER_DEFAULT, 'foo');
   }
 
-  test_nullLiteral() async {
+  Future<void> test_nullLiteral() async {
     await _computeHighlights('var x = null;');
     _check(HighlightRegionType.KEYWORD, 'null');
   }
 
-  test_throwExpression() async {
+  Future<void> test_throwExpression() async {
     await _computeHighlights('''
 void main() {
   throw 'foo';
diff --git a/pkg/analysis_server/test/src/computer/highlights_computer_test.dart b/pkg/analysis_server/test/src/computer/highlights_computer_test.dart
index 46c96b6..36860bd 100644
--- a/pkg/analysis_server/test/src/computer/highlights_computer_test.dart
+++ b/pkg/analysis_server/test/src/computer/highlights_computer_test.dart
@@ -12,7 +12,7 @@
 
 import '../../abstract_context.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(HighlightsComputerTest);
   });
@@ -25,12 +25,12 @@
   List<HighlightRegion> highlights;
 
   @override
-  setUp() {
+  void setUp() {
     super.setUp();
     sourcePath = convertPath('/home/test/lib/test.dart');
   }
 
-  test_extension() async {
+  Future<void> test_extension() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     await _computeHighlights('''
 extension E on String {}
@@ -39,7 +39,7 @@
     _check(HighlightRegionType.BUILT_IN, 'on');
   }
 
-  test_methodInvocation_ofExtensionOverride_unresolved() async {
+  Future<void> test_methodInvocation_ofExtensionOverride_unresolved() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     await _computeHighlights('''
 extension E on int {}
diff --git a/pkg/analysis_server/test/src/computer/import_elements_computer_test.dart b/pkg/analysis_server/test/src/computer/import_elements_computer_test.dart
index 8d78b6f..2fe414a 100644
--- a/pkg/analysis_server/test/src/computer/import_elements_computer_test.dart
+++ b/pkg/analysis_server/test/src/computer/import_elements_computer_test.dart
@@ -13,7 +13,7 @@
 
 import '../../abstract_context.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ImportElementsComputerTest);
   });
@@ -61,7 +61,7 @@
     path = convertPath('/home/test/lib/test.dart');
   }
 
-  test_createEdits_addImport_noDirectives() async {
+  Future<void> test_createEdits_addImport_noDirectives() async {
     await createBuilder('''
 main() {
   // paste here
@@ -80,7 +80,7 @@
 ''');
   }
 
-  test_createEdits_addImport_noPrefix() async {
+  Future<void> test_createEdits_addImport_noPrefix() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' as foo;
@@ -94,7 +94,7 @@
 ''');
   }
 
-  test_createEdits_addImport_prefix() async {
+  Future<void> test_createEdits_addImport_prefix() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart';
@@ -108,7 +108,7 @@
 ''');
   }
 
-  test_createEdits_addShow_multipleNames() async {
+  Future<void> test_createEdits_addShow_multipleNames() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' show B;
@@ -123,7 +123,7 @@
 ''');
   }
 
-  test_createEdits_addShow_removeHide() async {
+  Future<void> test_createEdits_addShow_removeHide() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' show A, B hide C, D;
@@ -136,7 +136,7 @@
 ''');
   }
 
-  test_createEdits_addShow_singleName_noPrefix() async {
+  Future<void> test_createEdits_addShow_singleName_noPrefix() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' show B;
@@ -149,7 +149,7 @@
 ''');
   }
 
-  test_createEdits_addShow_singleName_prefix() async {
+  Future<void> test_createEdits_addShow_singleName_prefix() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' show C;
@@ -164,7 +164,7 @@
 ''');
   }
 
-  test_createEdits_alreadyImported_noCombinators() async {
+  Future<void> test_createEdits_alreadyImported_noCombinators() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart';
@@ -175,7 +175,7 @@
     assertNoChanges();
   }
 
-  test_createEdits_alreadyImported_withPrefix() async {
+  Future<void> test_createEdits_alreadyImported_withPrefix() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' as foo;
@@ -186,7 +186,7 @@
     assertNoChanges();
   }
 
-  test_createEdits_alreadyImported_withShow() async {
+  Future<void> test_createEdits_alreadyImported_withShow() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' show A;
@@ -197,7 +197,7 @@
     assertNoChanges();
   }
 
-  test_createEdits_importSelf() async {
+  Future<void> test_createEdits_importSelf() async {
     await createBuilder('''
 class A {
   A parent;
@@ -209,7 +209,7 @@
     assertNoChanges();
   }
 
-  test_createEdits_invalidUri() async {
+  Future<void> test_createEdits_invalidUri() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'pakage:pkg/foo.dart';
@@ -223,13 +223,13 @@
 ''');
   }
 
-  test_createEdits_noElements() async {
+  Future<void> test_createEdits_noElements() async {
     await createBuilder('');
     await computeChanges(<ImportedElements>[]);
     assertNoChanges();
   }
 
-  test_createEdits_removeHide_firstInCombinator() async {
+  Future<void> test_createEdits_removeHide_firstInCombinator() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' hide A, B, C;
@@ -242,7 +242,7 @@
 ''');
   }
 
-  test_createEdits_removeHide_lastInCombinator() async {
+  Future<void> test_createEdits_removeHide_lastInCombinator() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' hide A, B, C;
@@ -255,7 +255,7 @@
 ''');
   }
 
-  test_createEdits_removeHide_middleInCombinator() async {
+  Future<void> test_createEdits_removeHide_middleInCombinator() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' hide A, B, C;
@@ -268,7 +268,7 @@
 ''');
   }
 
-  test_createEdits_removeHide_multipleCombinators() async {
+  Future<void> test_createEdits_removeHide_multipleCombinators() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' hide A, B, C hide A, B, C;
@@ -281,7 +281,7 @@
 ''');
   }
 
-  test_createEdits_removeHide_multipleNames() async {
+  Future<void> test_createEdits_removeHide_multipleNames() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' hide A, B, C hide D, E, F hide G, H, I;
@@ -294,7 +294,7 @@
 ''');
   }
 
-  test_createEdits_removeHideCombinator_first() async {
+  Future<void> test_createEdits_removeHideCombinator_first() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' hide A hide B hide C;
@@ -307,7 +307,7 @@
 ''');
   }
 
-  test_createEdits_removeHideCombinator_last() async {
+  Future<void> test_createEdits_removeHideCombinator_last() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' hide A hide B hide C;
@@ -320,7 +320,7 @@
 ''');
   }
 
-  test_createEdits_removeHideCombinator_middle() async {
+  Future<void> test_createEdits_removeHideCombinator_middle() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' hide A hide B hide C;
@@ -333,7 +333,7 @@
 ''');
   }
 
-  test_createEdits_removeHideCombinator_only() async {
+  Future<void> test_createEdits_removeHideCombinator_only() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' hide A;
@@ -346,7 +346,7 @@
 ''');
   }
 
-  test_createEdits_removeHideCombinator_only_multiple() async {
+  Future<void> test_createEdits_removeHideCombinator_only_multiple() async {
     var fooFile = addPackageFile('pkg', 'foo.dart', '');
     await createBuilder('''
 import 'package:pkg/foo.dart' hide A, B;
diff --git a/pkg/analysis_server/test/src/computer/imported_elements_computer_test.dart b/pkg/analysis_server/test/src/computer/imported_elements_computer_test.dart
index 127b4a6..b7c07c7 100644
--- a/pkg/analysis_server/test/src/computer/imported_elements_computer_test.dart
+++ b/pkg/analysis_server/test/src/computer/imported_elements_computer_test.dart
@@ -12,7 +12,7 @@
 
 import '../../abstract_context.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ImportedElementsComputerTest);
   });
@@ -45,12 +45,12 @@
   }
 
   @override
-  setUp() {
+  void setUp() {
     super.setUp();
     sourcePath = convertPath('/home/test/lib/test.dart');
   }
 
-  test_dartAsync_noPrefix() async {
+  Future<void> test_dartAsync_noPrefix() async {
     String selection = 'Future<String> f = null;';
     String content = '''
 import 'dart:async';
@@ -66,7 +66,7 @@
     ]);
   }
 
-  test_dartAsync_prefix() async {
+  Future<void> test_dartAsync_prefix() async {
     String selection = 'a.Future<String> f = null;';
     String content = '''
 import 'dart:async' as a;
@@ -82,7 +82,7 @@
     ]);
   }
 
-  test_dartCore_noPrefix() async {
+  Future<void> test_dartCore_noPrefix() async {
     String selection = "String s = '';";
     String content = '''
 blankLine() {
@@ -96,7 +96,7 @@
     ]);
   }
 
-  test_dartCore_prefix() async {
+  Future<void> test_dartCore_prefix() async {
     String selection = "core.String s = '';";
     String content = '''
 import 'dart:core' as core;
@@ -111,7 +111,7 @@
     ]);
   }
 
-  test_dartMath_noPrefix() async {
+  Future<void> test_dartMath_noPrefix() async {
     String selection = 'new Random();';
     String content = '''
 import 'dart:math';
@@ -126,7 +126,7 @@
     ]);
   }
 
-  test_import_simple() async {
+  Future<void> test_import_simple() async {
     String selection = "import 'dart:math';";
     String content = '''
 $selection
@@ -139,7 +139,7 @@
     expect(importedElements, hasLength(0));
   }
 
-  test_import_simple_show() async {
+  Future<void> test_import_simple_show() async {
     String selection = "import 'dart:math' show Random;";
     String content = '''
 $selection
@@ -152,7 +152,7 @@
     expect(importedElements, hasLength(0));
   }
 
-  test_multiple() async {
+  Future<void> test_multiple() async {
     String selection = r'''
 main() {
   Random r = new Random();
@@ -172,7 +172,7 @@
     ]);
   }
 
-  test_none_comment() async {
+  Future<void> test_none_comment() async {
     String selection = 'comment';
     String content = '''
 // Method $selection.
@@ -184,7 +184,7 @@
     expect(importedElements, hasLength(0));
   }
 
-  test_none_constructorDeclarationReturnType() async {
+  Future<void> test_none_constructorDeclarationReturnType() async {
     String selection = r'''
 class A {
   A();
@@ -198,7 +198,7 @@
     expect(importedElements, hasLength(0));
   }
 
-  test_none_partialNames() async {
+  Future<void> test_none_partialNames() async {
     String selection = 'x + y';
     String content = '''
 plusThree(int xx) {
@@ -210,7 +210,7 @@
     expect(importedElements, hasLength(0));
   }
 
-  test_none_wholeNames() async {
+  Future<void> test_none_wholeNames() async {
     String selection = 'x + y + 1';
     String content = '''
 plusThree(int x) {
@@ -222,7 +222,7 @@
     expect(importedElements, hasLength(0));
   }
 
-  test_package_multipleInSame() async {
+  Future<void> test_package_multipleInSame() async {
     addPackageFile('foo', 'foo.dart', '''
 class A {
   static String a = '';
@@ -244,7 +244,7 @@
     ]);
   }
 
-  test_package_noPrefix() async {
+  Future<void> test_package_noPrefix() async {
     addPackageFile('foo', 'foo.dart', '''
 class Foo {
   static String first = '';
@@ -263,7 +263,7 @@
     ]);
   }
 
-  test_package_prefix_selected_class() async {
+  Future<void> test_package_prefix_selected_class() async {
     addPackageFile('foo', 'foo.dart', '''
 class Foo {
   static String first = '';
@@ -282,7 +282,7 @@
     ]);
   }
 
-  test_package_prefix_selected_function() async {
+  Future<void> test_package_prefix_selected_function() async {
     addPackageFile('foo', 'foo.dart', '''
 String foo() => '';
 ''');
@@ -299,7 +299,7 @@
     ]);
   }
 
-  test_package_prefix_selected_getter() async {
+  Future<void> test_package_prefix_selected_getter() async {
     addPackageFile('foo', 'foo.dart', '''
 String foo = '';
 ''');
@@ -316,7 +316,7 @@
     ]);
   }
 
-  test_package_prefix_selected_setter() async {
+  Future<void> test_package_prefix_selected_setter() async {
     addPackageFile('foo', 'foo.dart', '''
 String foo = '';
 ''');
@@ -333,7 +333,7 @@
     ]);
   }
 
-  test_package_prefix_unselected() async {
+  Future<void> test_package_prefix_unselected() async {
     addPackageFile('foo', 'foo.dart', '''
 class Foo {
   static String first = '';
@@ -352,7 +352,7 @@
     ]);
   }
 
-  test_package_prefixedAndNot() async {
+  Future<void> test_package_prefixedAndNot() async {
     addPackageFile('foo', 'foo.dart', '''
 class Foo {
   static String first = '';
@@ -374,7 +374,7 @@
     ]);
   }
 
-  test_self() async {
+  Future<void> test_self() async {
     String selection = 'A parent;';
     String content = '''
 class A {
@@ -387,7 +387,7 @@
     ]);
   }
 
-  test_wholeFile_noImports() async {
+  Future<void> test_wholeFile_noImports() async {
     String content = '''
 blankLine() {
   String s = '';
@@ -400,7 +400,7 @@
     ]);
   }
 
-  test_wholeFile_withImports() async {
+  Future<void> test_wholeFile_withImports() async {
     String content = '''
 import 'dart:math';
 bool randomBool() {
diff --git a/pkg/analysis_server/test/src/computer/outline_computer_test.dart b/pkg/analysis_server/test/src/computer/outline_computer_test.dart
index 0da185a..8215a70 100644
--- a/pkg/analysis_server/test/src/computer/outline_computer_test.dart
+++ b/pkg/analysis_server/test/src/computer/outline_computer_test.dart
@@ -13,7 +13,7 @@
 
 import '../../abstract_context.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterOutlineComputerTest);
     defineReflectiveTests(OutlineComputerTest);
@@ -49,7 +49,7 @@
     addFlutterPackage();
   }
 
-  test_columnWithChildren() async {
+  Future<void> test_columnWithChildren() async {
     Outline unitOutline = await _computeOutline('''
 import 'package:flutter/widgets.dart';
 
@@ -139,7 +139,7 @@
 
 @reflectiveTest
 class OutlineComputerTest extends AbstractOutlineComputerTest {
-  test_class() async {
+  Future<void> test_class() async {
     Outline unitOutline = await _computeOutline('''
 abstract class A<K, V> {
   int fa, fb;
@@ -384,7 +384,7 @@
     }
   }
 
-  test_enum() async {
+  Future<void> test_enum() async {
     Outline unitOutline = await _computeOutline('''
 enum MyEnum {
   A, B, C
@@ -414,7 +414,7 @@
     }
   }
 
-  test_extension_named() async {
+  Future<void> test_extension_named() async {
     createAnalysisOptionsFile(experiments: [EnableString.extension_methods]);
     Outline unitOutline = await _computeOutline('''
 extension MyExt on String {
@@ -445,7 +445,7 @@
     }
   }
 
-  test_extension_unnamed() async {
+  Future<void> test_extension_unnamed() async {
     createAnalysisOptionsFile(experiments: [EnableString.extension_methods]);
     Outline unitOutline = await _computeOutline('''
 extension on String {
@@ -476,7 +476,7 @@
     }
   }
 
-  test_genericTypeAlias_incomplete() async {
+  Future<void> test_genericTypeAlias_incomplete() async {
     Outline unitOutline = await _computeOutline('''
 typedef F = Object;
 ''');
@@ -496,7 +496,7 @@
     expect(element_F.returnType, '');
   }
 
-  test_genericTypeAlias_minimal() async {
+  Future<void> test_genericTypeAlias_minimal() async {
     Outline unitOutline = await _computeOutline('''
 typedef F = void Function();
 ''');
@@ -516,7 +516,7 @@
     expect(element_F.returnType, 'void');
   }
 
-  test_genericTypeAlias_noReturnType() async {
+  Future<void> test_genericTypeAlias_noReturnType() async {
     Outline unitOutline = await _computeOutline('''
 typedef F = Function();
 ''');
@@ -536,7 +536,7 @@
     expect(element_F.returnType, '');
   }
 
-  test_groupAndTest() async {
+  Future<void> test_groupAndTest() async {
     Outline outline = await _computeOutline('''
 void group(name, closure) {}
 void test(name) {}
@@ -652,7 +652,7 @@
    *
    * https://code.google.com/p/dart/issues/detail?id=21373
    */
-  test_invalidGetterInConstructor() async {
+  Future<void> test_invalidGetterInConstructor() async {
     Outline outline = await _computeOutline('''
 class A {
   A() {
@@ -670,7 +670,7 @@
    *
    * https://github.com/dart-lang/sdk/issues/33228
    */
-  test_invocation_ofParameter() async {
+  Future<void> test_invocation_ofParameter() async {
     Outline outline = await _computeOutline('''
 main(p()) {
   p();
@@ -679,7 +679,7 @@
     expect(outline, isNotNull);
   }
 
-  test_isTest_isTestGroup() async {
+  Future<void> test_isTest_isTestGroup() async {
     addMetaPackage();
     Outline outline = await _computeOutline('''
 import 'package:meta/meta.dart';
@@ -797,7 +797,7 @@
         offset: testCode.indexOf("myTest('test2_2'"));
   }
 
-  test_localFunctions() async {
+  Future<void> test_localFunctions() async {
     Outline unitOutline = await _computeOutline('''
 class A {
   A() {
@@ -952,7 +952,7 @@
     }
   }
 
-  test_mixin() async {
+  Future<void> test_mixin() async {
     Outline unitOutline = await _computeOutline('''
 mixin M<N> {
   c(int d) {}
@@ -1023,7 +1023,7 @@
     }
   }
 
-  test_sourceRanges_fields() async {
+  Future<void> test_sourceRanges_fields() async {
     Outline unitOutline = await _computeOutline('''
 class A {
   int fieldA, fieldB = 2;
@@ -1094,7 +1094,7 @@
     }
   }
 
-  test_sourceRanges_inUnit() async {
+  Future<void> test_sourceRanges_inUnit() async {
     Outline unitOutline = await _computeOutline('''
 /// My first class.
 class A {}
@@ -1133,7 +1133,7 @@
     }
   }
 
-  test_sourceRanges_method() async {
+  Future<void> test_sourceRanges_method() async {
     Outline unitOutline = await _computeOutline('''
 class A {
   int methodA() {}
@@ -1175,7 +1175,7 @@
     }
   }
 
-  test_topLevel() async {
+  Future<void> test_topLevel() async {
     Outline unitOutline = await _computeOutline('''
 typedef String FTA<K, V>(int i, String s);
 typedef FTB(int p);
diff --git a/pkg/analysis_server/test/src/computer/test_all.dart b/pkg/analysis_server/test/src/computer/test_all.dart
index fa0c1a9..8d7653e 100644
--- a/pkg/analysis_server/test/src/computer/test_all.dart
+++ b/pkg/analysis_server/test/src/computer/test_all.dart
@@ -12,7 +12,7 @@
 import 'imported_elements_computer_test.dart' as imported_elements_computer;
 import 'outline_computer_test.dart' as outline_computer;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     closing_labels_computer.main();
     folding_computer.main();
diff --git a/pkg/analysis_server/test/src/domain_abstract_test.dart b/pkg/analysis_server/test/src/domain_abstract_test.dart
index cd94ff6..19f7c97 100644
--- a/pkg/analysis_server/test/src/domain_abstract_test.dart
+++ b/pkg/analysis_server/test/src/domain_abstract_test.dart
@@ -15,7 +15,7 @@
 
 import '../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AbstractRequestHandlerTest);
   });
@@ -23,7 +23,7 @@
 
 @reflectiveTest
 class AbstractRequestHandlerTest extends AbstractAnalysisTest {
-  test_waitForResponses_empty_noTimeout() async {
+  Future<void> test_waitForResponses_empty_noTimeout() async {
     AbstractRequestHandler handler = TestAbstractRequestHandler(server);
     Map<PluginInfo, Future<plugin.Response>> futures =
         <PluginInfo, Future<plugin.Response>>{};
@@ -31,7 +31,7 @@
     expect(responses, isEmpty);
   }
 
-  test_waitForResponses_empty_timeout() async {
+  Future<void> test_waitForResponses_empty_timeout() async {
     AbstractRequestHandler handler = TestAbstractRequestHandler(server);
     Map<PluginInfo, Future<plugin.Response>> futures =
         <PluginInfo, Future<plugin.Response>>{};
@@ -40,7 +40,7 @@
     expect(responses, isEmpty);
   }
 
-  test_waitForResponses_nonEmpty_noTimeout_immediate() async {
+  Future<void> test_waitForResponses_nonEmpty_noTimeout_immediate() async {
     AbstractRequestHandler handler = TestAbstractRequestHandler(server);
     PluginInfo plugin1 = DiscoveredPluginInfo('p1', '', '', null, null);
     PluginInfo plugin2 = DiscoveredPluginInfo('p2', '', '', null, null);
@@ -55,7 +55,7 @@
     expect(responses, unorderedEquals([response1, response2]));
   }
 
-  test_waitForResponses_nonEmpty_noTimeout_withError() async {
+  Future<void> test_waitForResponses_nonEmpty_noTimeout_withError() async {
     AbstractRequestHandler handler = TestAbstractRequestHandler(server);
     PluginInfo plugin1 = DiscoveredPluginInfo('p1', '', '', null, null);
     PluginInfo plugin2 = DiscoveredPluginInfo('p2', '', '', null, null);
@@ -72,7 +72,7 @@
     expect(responses, unorderedEquals([response1]));
   }
 
-  test_waitForResponses_nonEmpty_timeout_someDelayed() async {
+  Future<void> test_waitForResponses_nonEmpty_timeout_someDelayed() async {
     AbstractRequestHandler handler = TestAbstractRequestHandler(server);
     PluginInfo plugin1 = DiscoveredPluginInfo('p1', '', '', null, null);
     PluginInfo plugin2 = DiscoveredPluginInfo('p2', '', '', null, null);
diff --git a/pkg/analysis_server/test/src/domains/completion/available_suggestion_sets_test.dart b/pkg/analysis_server/test/src/domains/completion/available_suggestion_sets_test.dart
index 6e8af8e..9230187 100644
--- a/pkg/analysis_server/test/src/domains/completion/available_suggestion_sets_test.dart
+++ b/pkg/analysis_server/test/src/domains/completion/available_suggestion_sets_test.dart
@@ -8,7 +8,7 @@
 
 import 'available_suggestions_base.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AvailableSuggestionSetsTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class AvailableSuggestionSetsTest extends AvailableSuggestionsBase {
-  test_notifications_whenFileChanges() async {
+  Future<void> test_notifications_whenFileChanges() async {
     var path = convertPath('/home/test/lib/a.dart');
     var uriStr = 'package:test/a.dart';
 
@@ -47,7 +47,7 @@
     waitForSetWithUriRemoved(uriStr);
   }
 
-  test_suggestion_class() async {
+  Future<void> test_suggestion_class() async {
     var path = convertPath('/home/test/lib/a.dart');
     var uriStr = 'package:test/a.dart';
 
@@ -109,7 +109,7 @@
 ''');
   }
 
-  test_suggestion_enum() async {
+  Future<void> test_suggestion_enum() async {
     var path = convertPath('/home/test/lib/a.dart');
     var uriStr = 'package:test/a.dart';
 
@@ -189,7 +189,7 @@
 ''');
   }
 
-  test_suggestion_topLevelVariable() async {
+  Future<void> test_suggestion_topLevelVariable() async {
     var path = convertPath('/home/test/lib/a.dart');
     var uriStr = 'package:test/a.dart';
 
diff --git a/pkg/analysis_server/test/src/domains/completion/get_suggestion_details_test.dart b/pkg/analysis_server/test/src/domains/completion/get_suggestion_details_test.dart
index 33d5226..f0bed0b 100644
--- a/pkg/analysis_server/test/src/domains/completion/get_suggestion_details_test.dart
+++ b/pkg/analysis_server/test/src/domains/completion/get_suggestion_details_test.dart
@@ -12,7 +12,7 @@
 
 import 'available_suggestions_base.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetSuggestionDetailsTest);
   });
@@ -20,7 +20,7 @@
 
 @reflectiveTest
 class GetSuggestionDetailsTest extends AvailableSuggestionsBase {
-  test_enum() async {
+  Future<void> test_enum() async {
     newFile('/home/test/lib/a.dart', content: r'''
 enum MyEnum {
   aaa, bbb
@@ -47,7 +47,7 @@
 ''');
   }
 
-  test_existingImport() async {
+  Future<void> test_existingImport() async {
     addTestFile(r'''
 import 'dart:math';
 
@@ -67,7 +67,7 @@
     _assertEmptyChange(result.change);
   }
 
-  test_existingImport_prefixed() async {
+  Future<void> test_existingImport_prefixed() async {
     addTestFile(r'''
 import 'dart:math' as math;
 
@@ -87,7 +87,7 @@
     _assertEmptyChange(result.change);
   }
 
-  test_invalid_library() async {
+  Future<void> test_invalid_library() async {
     addTestFile('');
 
     var response = await waitResponse(
@@ -96,7 +96,7 @@
     expect(response.error.code, RequestErrorCode.INVALID_PARAMETER);
   }
 
-  test_newImport() async {
+  Future<void> test_newImport() async {
     addTestFile(r'''
 main() {} // ref
 ''');
@@ -118,7 +118,7 @@
 ''');
   }
 
-  test_newImport_part() async {
+  Future<void> test_newImport_part() async {
     var partCode = r'''
 part of 'test.dart';
 
diff --git a/pkg/analysis_server/test/src/domains/completion/get_suggestions_available_test.dart b/pkg/analysis_server/test/src/domains/completion/get_suggestions_available_test.dart
index d9f168d..b1a06be 100644
--- a/pkg/analysis_server/test/src/domains/completion/get_suggestions_available_test.dart
+++ b/pkg/analysis_server/test/src/domains/completion/get_suggestions_available_test.dart
@@ -8,7 +8,7 @@
 
 import 'available_suggestions_base.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ExistingImportsNotification);
     defineReflectiveTests(GetSuggestionAvailableTest);
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class ExistingImportsNotification extends GetSuggestionsBase {
-  test_dart() async {
+  Future<void> test_dart() async {
     addTestFile(r'''
 import 'dart:math';
 ''');
@@ -25,7 +25,7 @@
     _assertHasImport('dart:math', 'dart:math', 'Random');
   }
 
-  test_invalidUri() async {
+  Future<void> test_invalidUri() async {
     addTestFile(r'''
 import 'ht:';
 ''');
@@ -54,7 +54,7 @@
 
 @reflectiveTest
 class GetSuggestionAvailableTest extends GetSuggestionsBase {
-  test_dart() async {
+  Future<void> test_dart() async {
     addTestFile('');
     var mathSet = await waitForSetWithUri('dart:math');
     var asyncSet = await waitForSetWithUri('dart:async');
@@ -67,7 +67,7 @@
     expect(includedIdSet, contains(asyncSet.id));
   }
 
-  test_dart_instanceCreationExpression() async {
+  Future<void> test_dart_instanceCreationExpression() async {
     addTestFile(r'''
 main() {
   new ; // ref
@@ -88,7 +88,7 @@
     expect(includedIdSet, contains(asyncSet.id));
   }
 
-  test_defaultArgumentListString() async {
+  Future<void> test_defaultArgumentListString() async {
     newFile('/home/test/lib/a.dart', content: r'''
 void fff(int aaa, int bbb) {}
 
@@ -106,7 +106,7 @@
     expect(ggg.defaultArgumentListTextRanges, [5, 4, 16, 4]);
   }
 
-  test_displayUri_file() async {
+  Future<void> test_displayUri_file() async {
     var aPath = '/home/test/test/a.dart';
     newFile(aPath, content: 'class A {}');
 
@@ -123,7 +123,7 @@
     );
   }
 
-  test_displayUri_package() async {
+  Future<void> test_displayUri_package() async {
     var aPath = '/home/test/lib/a.dart';
     newFile(aPath, content: 'class A {}');
 
@@ -139,7 +139,7 @@
     );
   }
 
-  test_includedElementKinds_type() async {
+  Future<void> test_includedElementKinds_type() async {
     addTestFile(r'''
 class X extends {} // ref
 ''');
@@ -161,7 +161,7 @@
     );
   }
 
-  test_includedElementKinds_value() async {
+  Future<void> test_includedElementKinds_value() async {
     addTestFile(r'''
 main() {
   print(); // ref
@@ -190,7 +190,7 @@
     );
   }
 
-  test_inHtml() async {
+  Future<void> test_inHtml() async {
     newFile('/home/test/lib/a.dart', content: 'class A {}');
 
     var path = convertPath('/home/test/doc/a.html');
@@ -201,7 +201,7 @@
     );
   }
 
-  test_relevanceTags_enum() async {
+  Future<void> test_relevanceTags_enum() async {
     newFile('/home/test/lib/a.dart', content: r'''
 enum MyEnum {
   aaa, bbb
@@ -230,7 +230,7 @@
 ''');
   }
 
-  test_relevanceTags_location_argumentList_named() async {
+  Future<void> test_relevanceTags_location_argumentList_named() async {
     addTestFile(r'''
 void foo({int a, String b}) {}
 
@@ -254,7 +254,7 @@
 ''');
   }
 
-  test_relevanceTags_location_argumentList_positional() async {
+  Future<void> test_relevanceTags_location_argumentList_positional() async {
     addTestFile(r'''
 void foo(double a) {}
 
@@ -278,7 +278,7 @@
 ''');
   }
 
-  test_relevanceTags_location_assignment() async {
+  Future<void> test_relevanceTags_location_assignment() async {
     addTestFile(r'''
 main() {
   int v;
@@ -301,7 +301,7 @@
 ''');
   }
 
-  test_relevanceTags_location_initializer() async {
+  Future<void> test_relevanceTags_location_initializer() async {
     addTestFile(r'''
 int v = // ref;
 ''');
@@ -321,7 +321,7 @@
 ''');
   }
 
-  test_relevanceTags_location_listLiteral() async {
+  Future<void> test_relevanceTags_location_listLiteral() async {
     addTestFile(r'''
 main() {
   var v = [0, ]; // ref
diff --git a/pkg/analysis_server/test/src/domains/completion/test_all.dart b/pkg/analysis_server/test/src/domains/completion/test_all.dart
index 066f43c..1452e21 100644
--- a/pkg/analysis_server/test/src/domains/completion/test_all.dart
+++ b/pkg/analysis_server/test/src/domains/completion/test_all.dart
@@ -8,7 +8,7 @@
 import 'get_suggestion_details_test.dart' as get_suggestion_details;
 import 'get_suggestions_available_test.dart' as get_suggestions_available;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     available_suggestion_sets.main();
     get_suggestion_details.main();
diff --git a/pkg/analysis_server/test/src/domains/execution/completion_test.dart b/pkg/analysis_server/test/src/domains/execution/completion_test.dart
index 8507c09..a083383 100644
--- a/pkg/analysis_server/test/src/domains/execution/completion_test.dart
+++ b/pkg/analysis_server/test/src/domains/execution/completion_test.dart
@@ -11,7 +11,7 @@
 
 import '../../../abstract_context.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RuntimeCompletionComputerTest);
   });
@@ -87,7 +87,7 @@
     return null;
   }
 
-  test_class_fields() async {
+  Future<void> test_class_fields() async {
     addContextFile(r'''
 class A {
   int a;
@@ -105,7 +105,7 @@
     assertSuggested('c', returnType: 'double');
   }
 
-  test_class_methods() async {
+  Future<void> test_class_methods() async {
     addContextFile(r'''
 class A {
   int a() => null;
@@ -122,7 +122,7 @@
     assertSuggested('b', returnType: 'double');
   }
 
-  test_inPart() async {
+  Future<void> test_inPart() async {
     addSource('/home/test/lib/a.dart', r'''
 part 'b.dart';
 part 'context.dart';
@@ -149,7 +149,7 @@
     assertSuggested('c', returnType: 'String');
   }
 
-  test_locals_block() async {
+  Future<void> test_locals_block() async {
     addContextFile(r'''
 class A {
   int foo;
@@ -169,7 +169,7 @@
     assertSuggested('foo');
   }
 
-  test_locals_block_codeWithClosure() async {
+  Future<void> test_locals_block_codeWithClosure() async {
     addContextFile(r'''
 main() {
   var items = <String>[];
@@ -180,7 +180,7 @@
     assertSuggested('toUpperCase');
   }
 
-  test_locals_block_nested() async {
+  Future<void> test_locals_block_nested() async {
     addContextFile(r'''
 void main() {
   var a = 0;
@@ -200,7 +200,7 @@
     assertNotSuggested('c');
   }
 
-  test_locals_for() async {
+  Future<void> test_locals_for() async {
     addContextFile(r'''
 void main(List<int> intItems, List<double> doubleItems) {
   for (var a = 0, b = 0.0; a < 5; a++) {
@@ -213,7 +213,7 @@
     assertSuggested('b', returnType: 'double');
   }
 
-  test_locals_forEach() async {
+  Future<void> test_locals_forEach() async {
     addContextFile(r'''
 void main(List<int> intItems, List<double> doubleItems) {
   for (var a in intItems) {
@@ -228,7 +228,7 @@
     assertSuggested('b', returnType: 'double');
   }
 
-  test_parameters_constructor() async {
+  Future<void> test_parameters_constructor() async {
     addContextFile(r'''
 class C {
   C(int a, double b) {
@@ -241,7 +241,7 @@
     assertSuggested('b', returnType: 'double');
   }
 
-  test_parameters_function() async {
+  Future<void> test_parameters_function() async {
     addContextFile(r'''
 void main(int a, double b) {
   // context line
@@ -252,7 +252,7 @@
     assertSuggested('b', returnType: 'double');
   }
 
-  test_parameters_function_locals() async {
+  Future<void> test_parameters_function_locals() async {
     addContextFile(r'''
 void main(int a, int b) {
   String a;
@@ -266,7 +266,7 @@
     assertSuggested('c', returnType: 'double');
   }
 
-  test_parameters_function_nested() async {
+  Future<void> test_parameters_function_nested() async {
     addContextFile(r'''
 void foo(int a, double b) {
   void bar(String a, bool c) {
@@ -280,7 +280,7 @@
     assertSuggested('c', returnType: 'bool');
   }
 
-  test_parameters_functionExpression() async {
+  Future<void> test_parameters_functionExpression() async {
     addContextFile(r'''
 void main(List<int> intItems, List<double> doubleItems) {
   intItems.forEach((a) {
@@ -295,7 +295,7 @@
     assertSuggested('b', returnType: 'double');
   }
 
-  test_parameters_method() async {
+  Future<void> test_parameters_method() async {
     addContextFile(r'''
 class C {
   void main(int a, double b) {
@@ -308,7 +308,7 @@
     assertSuggested('b', returnType: 'double');
   }
 
-  test_parameters_method_locals() async {
+  Future<void> test_parameters_method_locals() async {
     addContextFile(r'''
 class C {
   void main(int a, int b) {
@@ -324,7 +324,7 @@
     assertSuggested('c', returnType: 'double');
   }
 
-  test_syntheticImportPrefix() async {
+  Future<void> test_syntheticImportPrefix() async {
     newFile('/test/lib/a.dart', content: 'class A {}');
     newFile('/test/lib/b.dart', content: 'class B {}');
     addContextFile(r'''
@@ -342,7 +342,7 @@
     }
   }
 
-  test_topLevelFunctions() async {
+  Future<void> test_topLevelFunctions() async {
     addContextFile(r'''
 int a() => null;
 double b() => null;
@@ -355,7 +355,7 @@
     assertSuggested('b', returnType: 'double');
   }
 
-  test_topLevelVariables() async {
+  Future<void> test_topLevelVariables() async {
     addContextFile(r'''
 int a;
 double b;
diff --git a/pkg/analysis_server/test/src/domains/execution/test_all.dart b/pkg/analysis_server/test/src/domains/execution/test_all.dart
index cde2384..1cbd9d3 100644
--- a/pkg/analysis_server/test/src/domains/execution/test_all.dart
+++ b/pkg/analysis_server/test/src/domains/execution/test_all.dart
@@ -6,7 +6,7 @@
 
 import 'completion_test.dart' as completion_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     completion_test.main();
   });
diff --git a/pkg/analysis_server/test/src/domains/flutter/get_widget_description_test.dart b/pkg/analysis_server/test/src/domains/flutter/get_widget_description_test.dart
index 9a319ca..45affaa 100644
--- a/pkg/analysis_server/test/src/domains/flutter/get_widget_description_test.dart
+++ b/pkg/analysis_server/test/src/domains/flutter/get_widget_description_test.dart
@@ -8,7 +8,7 @@
 
 import 'base.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetWidgetDescriptionTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class GetWidgetDescriptionTest extends FlutterBase {
-  test_kind_required() async {
+  Future<void> test_kind_required() async {
     addTestFile(r'''
 import 'package:flutter/material.dart';
 
@@ -35,7 +35,7 @@
     expect(property.value.stringValue, 'aaa');
   }
 
-  test_notInstanceCreation() async {
+  Future<void> test_notInstanceCreation() async {
     addTestFile(r'''
 void main() {
   42;
@@ -49,7 +49,7 @@
     );
   }
 
-  test_unresolvedInstanceCreation() async {
+  Future<void> test_unresolvedInstanceCreation() async {
     addTestFile(r'''
 void main() {
   new Foo();
diff --git a/pkg/analysis_server/test/src/domains/flutter/set_property_value_test.dart b/pkg/analysis_server/test/src/domains/flutter/set_property_value_test.dart
index 8306d1e..6475882 100644
--- a/pkg/analysis_server/test/src/domains/flutter/set_property_value_test.dart
+++ b/pkg/analysis_server/test/src/domains/flutter/set_property_value_test.dart
@@ -8,7 +8,7 @@
 
 import 'base.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SetPropertyValueTest);
   });
@@ -16,7 +16,7 @@
 
 @reflectiveTest
 class SetPropertyValueTest extends FlutterBase {
-  test_named_add() async {
+  Future<void> test_named_add() async {
     addTestFile(r'''
 import 'package:flutter/material.dart';
 
@@ -45,7 +45,7 @@
 ''');
   }
 
-  test_named_change() async {
+  Future<void> test_named_change() async {
     addTestFile(r'''
 import 'package:flutter/material.dart';
 
@@ -71,7 +71,7 @@
 ''');
   }
 
-  test_named_remove() async {
+  Future<void> test_named_remove() async {
     addTestFile(r'''
 import 'package:flutter/material.dart';
 
@@ -94,7 +94,7 @@
 ''');
   }
 
-  test_required_change() async {
+  Future<void> test_required_change() async {
     addTestFile(r'''
 import 'package:flutter/material.dart';
 
diff --git a/pkg/analysis_server/test/src/domains/flutter/test_all.dart b/pkg/analysis_server/test/src/domains/flutter/test_all.dart
index d25b982..2030531 100644
--- a/pkg/analysis_server/test/src/domains/flutter/test_all.dart
+++ b/pkg/analysis_server/test/src/domains/flutter/test_all.dart
@@ -7,7 +7,7 @@
 import 'get_widget_description_test.dart' as get_widget_description;
 import 'set_property_value_test.dart' as set_property_value;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     get_widget_description.main();
     set_property_value.main();
diff --git a/pkg/analysis_server/test/src/domains/test_all.dart b/pkg/analysis_server/test/src/domains/test_all.dart
index 5e6917d..dac4cfe 100644
--- a/pkg/analysis_server/test/src/domains/test_all.dart
+++ b/pkg/analysis_server/test/src/domains/test_all.dart
@@ -8,7 +8,7 @@
 import 'execution/test_all.dart' as execution;
 import 'flutter/test_all.dart' as flutter;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     completion.main();
     execution.main();
diff --git a/pkg/analysis_server/test/src/edit/fix/non_nullable_fix_test.dart b/pkg/analysis_server/test/src/edit/fix/non_nullable_fix_test.dart
index c4a53fe..a485d89 100644
--- a/pkg/analysis_server/test/src/edit/fix/non_nullable_fix_test.dart
+++ b/pkg/analysis_server/test/src/edit/fix/non_nullable_fix_test.dart
@@ -14,7 +14,7 @@
 
 import '../../../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(NonNullableFixTest);
   });
@@ -30,6 +30,13 @@
 
   String get nextRequestId => (++requestId).toString();
 
+  /// On Windows, canonicalization results in changing a drive letter to be
+  /// lowercase. When a path is canonicalized in [NonNullableFix], and asserted
+  /// on in a test below, the expected path below also needs to be
+  /// canonicalized.
+  String canonicalizeAndConvertPath(String p) =>
+      convertPath(context.canonicalize(p));
+
   Future<EditDartfixResult> performFix({List<String> included}) async {
     final id = nextRequestId;
     final params = EditDartfixParams(included);
@@ -71,59 +78,75 @@
     listener = DartFixListener(server);
   }
 
-  test_included_multipleRelativeDirectories() async {
+  Future<void> test_included_multipleRelativeDirectories() async {
     NonNullableFix fix = NonNullableFix(listener, included: ['lib', 'test']);
-    expect(fix.includedRoot, equals(convertPath('/project')));
+    expect(fix.includedRoot, equals(canonicalizeAndConvertPath('/project')));
   }
 
-  test_included_multipleRelativeDirectories_nonCanonical() async {
-    NonNullableFix fix = NonNullableFix(listener,
-        included: ['../project2/lib', '../project2/lib/src']);
-    expect(fix.includedRoot, equals(convertPath('/project2/lib')));
+  Future<void> test_included_multipleRelativeDirectories_nonCanonical() async {
+    NonNullableFix fix = NonNullableFix(listener, included: [
+      convertPath('../project2/lib'),
+      convertPath('../project2/lib/src')
+    ]);
+    expect(
+        fix.includedRoot, equals(canonicalizeAndConvertPath('/project2/lib')));
   }
 
-  test_included_multipleRelativeDirectories_nonCanonical_atFilesystemRoot() async {
-    NonNullableFix fix = NonNullableFix(listener,
-        included: ['../project2/lib', '../project/lib']);
-    expect(fix.includedRoot, equals(convertPath('/')));
+  Future<void>
+      test_included_multipleRelativeDirectories_nonCanonical_atRoot() async {
+    NonNullableFix fix = NonNullableFix(listener, included: [
+      convertPath('../project2/lib'),
+      convertPath('../project/lib')
+    ]);
+    expect(fix.includedRoot, equals(canonicalizeAndConvertPath('/')));
   }
 
-  test_included_multipleRelativeDirectories_subAndSuperDirectories() async {
+  Future<void>
+      test_included_multipleRelativeDirectories_subAndSuperDirectories() async {
     NonNullableFix fix = NonNullableFix(listener, included: ['lib', '.']);
-    expect(fix.includedRoot, equals(convertPath('/project')));
+    expect(fix.includedRoot, equals(canonicalizeAndConvertPath('/project')));
   }
 
-  test_included_multipleRelativeFiles() async {
-    NonNullableFix fix =
-        NonNullableFix(listener, included: ['lib/lib1.dart', 'test/test.dart']);
-    expect(fix.includedRoot, equals(convertPath('/project')));
+  Future<void> test_included_multipleRelativeFiles() async {
+    NonNullableFix fix = NonNullableFix(listener, included: [
+      convertPath('lib/lib1.dart'),
+      convertPath('test/test.dart')
+    ]);
+    expect(fix.includedRoot, equals(canonicalizeAndConvertPath('/project')));
   }
 
-  test_included_multipleRelativeFiles_sameDirectory() async {
-    NonNullableFix fix =
-        NonNullableFix(listener, included: ['lib/lib1.dart', 'lib/lib2.dart']);
-    expect(fix.includedRoot, equals(convertPath('/project/lib')));
-  }
-
-  test_included_multipleRelativeFilesAndDirectories() async {
+  Future<void> test_included_multipleRelativeFiles_sameDirectory() async {
     NonNullableFix fix = NonNullableFix(listener,
-        included: ['lib/lib1.dart', 'lib/src', '../project/lib/src/lib3.dart']);
-    expect(fix.includedRoot, equals(convertPath('/project/lib')));
+        included: [convertPath('lib/lib1.dart'), convertPath('lib/lib2.dart')]);
+    expect(
+        fix.includedRoot, equals(canonicalizeAndConvertPath('/project/lib')));
   }
 
-  test_included_singleAbsoluteDirectory() async {
-    NonNullableFix fix = NonNullableFix(listener, included: ['/project']);
-    expect(fix.includedRoot, equals(convertPath('/project')));
+  Future<void> test_included_multipleRelativeFilesAndDirectories() async {
+    NonNullableFix fix = NonNullableFix(listener, included: [
+      convertPath('lib/lib1.dart'),
+      convertPath('lib/src'),
+      convertPath('../project/lib/src/lib3.dart')
+    ]);
+    expect(
+        fix.includedRoot, equals(canonicalizeAndConvertPath('/project/lib')));
   }
 
-  test_included_singleAbsoluteFile() async {
+  Future<void> test_included_singleAbsoluteDirectory() async {
     NonNullableFix fix =
-        NonNullableFix(listener, included: ['/project/bin/bin.dart']);
-    expect(fix.includedRoot, equals(convertPath('/project/bin')));
+        NonNullableFix(listener, included: [convertPath('/project')]);
+    expect(fix.includedRoot, equals(canonicalizeAndConvertPath('/project')));
   }
 
-  test_included_singleRelativeDirectory() async {
+  Future<void> test_included_singleAbsoluteFile() async {
+    NonNullableFix fix = NonNullableFix(listener,
+        included: [convertPath('/project/bin/bin.dart')]);
+    expect(
+        fix.includedRoot, equals(canonicalizeAndConvertPath('/project/bin')));
+  }
+
+  Future<void> test_included_singleRelativeDirectory() async {
     NonNullableFix fix = NonNullableFix(listener, included: ['.']);
-    expect(fix.includedRoot, equals(convertPath('/project')));
+    expect(fix.includedRoot, equals(canonicalizeAndConvertPath('/project')));
   }
 }
diff --git a/pkg/analysis_server/test/src/edit/fix/test_all.dart b/pkg/analysis_server/test/src/edit/fix/test_all.dart
index 1bf972c..3d33c83 100644
--- a/pkg/analysis_server/test/src/edit/fix/test_all.dart
+++ b/pkg/analysis_server/test/src/edit/fix/test_all.dart
@@ -6,7 +6,7 @@
 
 import 'non_nullable_fix_test.dart' as non_nullable_fix;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     non_nullable_fix.main();
   }, name: 'fix');
diff --git a/pkg/analysis_server/test/src/edit/nnbd_migration/info_builder_test.dart b/pkg/analysis_server/test/src/edit/nnbd_migration/info_builder_test.dart
index 79735da..8883e30 100644
--- a/pkg/analysis_server/test/src/edit/nnbd_migration/info_builder_test.dart
+++ b/pkg/analysis_server/test/src/edit/nnbd_migration/info_builder_test.dart
@@ -13,7 +13,7 @@
 import '../../../analysis_abstract.dart';
 import 'nnbd_migration_test_base.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(BuildEnclosingMemberDescriptionTest);
     defineReflectiveTests(InfoBuilderTest);
@@ -31,7 +31,7 @@
         .getResolvedUnit(testFile);
   }
 
-  test_classConstructor_named() async {
+  Future<void> test_classConstructor_named() async {
     addTestFile(r'''
 class C {
   C.aaa();
@@ -44,7 +44,7 @@
         equals("the constructor 'C.aaa'"));
   }
 
-  test_classConstructor_unnamed() async {
+  Future<void> test_classConstructor_unnamed() async {
     addTestFile(r'''
 class C {
   C();
@@ -57,7 +57,7 @@
         equals("the default constructor of 'C'"));
   }
 
-  test_classGetter() async {
+  Future<void> test_classGetter() async {
     addTestFile(r'''
 class C {
   int get aaa => 7;
@@ -70,7 +70,7 @@
         equals("the getter 'C.aaa'"));
   }
 
-  test_classMethod() async {
+  Future<void> test_classMethod() async {
     addTestFile(r'''
 class C {
   int aaa() => 7;
@@ -83,7 +83,7 @@
         equals("the method 'C.aaa'"));
   }
 
-  test_classOperator() async {
+  Future<void> test_classOperator() async {
     addTestFile(r'''
 class C {
   bool operator ==(Object other) => false;
@@ -96,7 +96,7 @@
         equals("the operator 'C.=='"));
   }
 
-  test_classSetter() async {
+  Future<void> test_classSetter() async {
     addTestFile(r'''
 class C {
   void set aaa(value) {}
@@ -109,7 +109,7 @@
         equals("the setter 'C.aaa='"));
   }
 
-  test_extensionMethod() async {
+  Future<void> test_extensionMethod() async {
     addTestFile(r'''
 extension E on List {
   int aaa() => 7;
@@ -122,7 +122,7 @@
         equals("the method 'E.aaa'"));
   }
 
-  test_extensionMethod_unnamed() async {
+  Future<void> test_extensionMethod_unnamed() async {
     addTestFile(r'''
 extension on List {
   int aaa() => 7;
@@ -135,7 +135,7 @@
         equals("the method 'aaa' in unnamed extension on List<dynamic>"));
   }
 
-  test_mixinMethod() async {
+  Future<void> test_mixinMethod() async {
     addTestFile(r'''
 mixin C {
   int aaa() => 7;
@@ -148,7 +148,7 @@
         equals("the method 'C.aaa'"));
   }
 
-  test_topLevelFunction() async {
+  Future<void> test_topLevelFunction() async {
     addTestFile(r'''
 void aaa(value) {}
 ''');
@@ -158,7 +158,7 @@
         equals("the function 'aaa'"));
   }
 
-  test_topLevelGetter() async {
+  Future<void> test_topLevelGetter() async {
     addTestFile(r'''
 int get aaa => 7;
 ''');
@@ -168,7 +168,7 @@
         equals("the getter 'aaa'"));
   }
 
-  test_topLevelSetter() async {
+  Future<void> test_topLevelSetter() async {
     addTestFile(r'''
 void set aaa(value) {}
 ''');
@@ -237,7 +237,7 @@
     }
   }
 
-  test_asExpression() async {
+  Future<void> test_asExpression() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f([num a]) {
   int b = a as int;
@@ -260,7 +260,7 @@
         details: ['The value of the expression is nullable']);
   }
 
-  test_asExpression_insideReturn() async {
+  Future<void> test_asExpression_insideReturn() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 int f([num a]) {
   return a as int;
@@ -280,7 +280,7 @@
         details: ['The value of the expression is nullable']);
   }
 
-  test_discardCondition() async {
+  Future<void> test_discardCondition() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void g(int i) {
   print(i.isEven);
@@ -298,7 +298,7 @@
     assertRegion(region: regions[1], offset: 55, length: 3);
   }
 
-  test_discardElse() async {
+  Future<void> test_discardElse() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void g(int i) {
   print(i.isEven);
@@ -320,7 +320,7 @@
     assertRegion(region: regions[3], offset: 101, length: 3);
   }
 
-  test_dynamicValueIsUsed() async {
+  Future<void> test_dynamicValueIsUsed() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 bool f(int i) {
   if (i == null) return true;
@@ -352,7 +352,7 @@
     assertEdit(edit: edits[1], offset: 10, replacement: '/*?*/');
   }
 
-  test_exactNullable() async {
+  Future<void> test_exactNullable() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f(List<int> list) {
   list[0] = null;
@@ -382,7 +382,7 @@
         details: ['This is later required to accept null.']);
   }
 
-  test_exactNullable_exactNullable() async {
+  Future<void> test_exactNullable_exactNullable() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void g(List<int> list1, List<int> list2) {
   list1[0] = null;
@@ -409,7 +409,7 @@
         details: ["A nullable value is assigned in the function 'g'"]);
   }
 
-  test_expressionFunctionReturnTarget() async {
+  Future<void> test_expressionFunctionReturnTarget() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 String g() => 1 == 2 ? "Hello" : null;
 ''', migratedContent: '''
@@ -426,7 +426,7 @@
     assertDetail(detail: regions[0].details[0], offset: 11, length: 2);
   }
 
-  test_field_fieldFormalInitializer_optional() async {
+  Future<void> test_field_fieldFormalInitializer_optional() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   int _f;
@@ -446,7 +446,7 @@
     ]);
   }
 
-  test_field_fieldFormalInitializer_optional_defaultNull() async {
+  Future<void> test_field_fieldFormalInitializer_optional_defaultNull() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   int _f;
@@ -466,7 +466,7 @@
     ]);
   }
 
-  test_field_fieldFormalInitializer_required() async {
+  Future<void> test_field_fieldFormalInitializer_required() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   int _f;
@@ -494,7 +494,7 @@
     ]);
   }
 
-  test_field_initializer() async {
+  Future<void> test_field_initializer() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   int _f = null;
@@ -518,7 +518,7 @@
         details: ['This field is initialized to a nullable value']);
   }
 
-  test_fieldLaterAssignedNullable() async {
+  Future<void> test_fieldLaterAssignedNullable() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class Foo {
   int value = 7;
@@ -544,7 +544,179 @@
     assertDetail(detail: region.details[0], offset: 56, length: 4);
   }
 
-  test_insertedRequired_fieldFormal() async {
+  Future<void> test_functionType_nullable_asArgument() async {
+    UnitInfo unit = await buildInfoForSingleTestFile('''
+class C {
+  f(void Function(int) cb1) {}
+  g(void Function(int) cb2) {
+    f(cb2);
+  }
+  h() => f(null);
+}
+''', migratedContent: '''
+class C {
+  f(void Function(int)? cb1) {}
+  g(void Function(int) cb2) {
+    f(cb2);
+  }
+  h() => f(null);
+}
+''');
+    List<RegionInfo> regions = unit.fixRegions;
+    expect(regions, hasLength(1));
+    assertRegion(
+        region: regions[0],
+        offset: 32,
+        details: ["An explicit 'null' is passed as an argument"]);
+    assertDetail(detail: regions[0].details[0], offset: 98, length: 4);
+  }
+
+  Future<void> test_functionType_nullableParameter_asArgument() async {
+    UnitInfo unit = await buildInfoForSingleTestFile('''
+class C {
+  f(void Function(int) cb1) {
+    cb1(null);
+  }
+  g(void Function(int) cb2) {
+    f(cb2);
+  }
+}
+''', migratedContent: '''
+class C {
+  f(void Function(int?) cb1) {
+    cb1(null);
+  }
+  g(void Function(int?) cb2) {
+    f(cb2);
+  }
+}
+''');
+    List<RegionInfo> regions = unit.fixRegions;
+    expect(regions, hasLength(2));
+    assertRegion(
+        region: regions[0],
+        offset: 31,
+        details: ["An explicit 'null' is passed as an argument"]);
+    assertRegion(region: regions[1], offset: 81, details: [
+      'The function-typed element in which this parameter is declared is '
+          'assigned to a function whose matching parameter is nullable'
+    ]);
+    assertDetail(detail: regions[1].details[0], offset: 95, length: 3);
+  }
+
+  Future<void> test_functionType_nullableParameter_assignment() async {
+    UnitInfo unit = await buildInfoForSingleTestFile('''
+class C {
+  void Function(int) _cb = (x) {};
+  f(void Function(int) cb) {
+    _cb = cb;
+  }
+  g() => _cb(null);
+}
+''', migratedContent: '''
+class C {
+  void Function(int?) _cb = (x) {};
+  f(void Function(int?) cb) {
+    _cb = cb;
+  }
+  g() => _cb(null);
+}
+''');
+    List<RegionInfo> regions = unit.fixRegions;
+    expect(regions, hasLength(2));
+    // regions[0] is `void Function(int?) _cb`.
+    assertRegion(region: regions[1], offset: 67, details: [
+      'The function-typed element in which this parameter is declared is '
+          'assigned to a function whose matching parameter is nullable'
+    ]);
+    assertDetail(detail: regions[1].details[0], offset: 84, length: 2);
+  }
+
+  Future<void> test_functionType_nullableParameter_fieldInitializer() async {
+    UnitInfo unit = await buildInfoForSingleTestFile('''
+class C {
+  void Function(int) _cb;
+  C(void Function(int) cb): _cb = cb;
+  f() => _cb(null);
+}
+''', migratedContent: '''
+class C {
+  void Function(int?) _cb;
+  C(void Function(int?) cb): _cb = cb;
+  f() => _cb(null);
+}
+''');
+    List<RegionInfo> regions = unit.fixRegions;
+    expect(regions, hasLength(2));
+    assertRegion(
+        region: regions[0],
+        offset: 29,
+        details: ["An explicit 'null' is passed as an argument"]);
+    assertRegion(region: regions[1], offset: 58, details: [
+      'The function-typed element in which this parameter is declared is '
+          'assigned to a function whose matching parameter is nullable'
+    ]);
+    assertDetail(detail: regions[1].details[0], offset: 70, length: 2);
+  }
+
+  @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/40034')
+  Future<void> test_functionType_nullableParameter_typedef() async {
+    UnitInfo unit = await buildInfoForSingleTestFile('''
+typedef Cb = void Function(int);
+class C {
+  Cb _cb;
+  C(void Function(int) cb): _cb = cb;
+  f() => _cb(null);
+}
+''', migratedContent: '''
+typedef Cb = void Function(int?);
+class C {
+  Cb _cb;
+  C(void Function(int?) cb): _cb = cb;
+  f() => _cb(null);
+}
+''');
+    List<RegionInfo> regions = unit.fixRegions;
+    expect(regions, hasLength(2));
+    // regions[0] is `typedef Cb = void Function(int?);`.
+    assertRegion(region: regions[1], offset: 75, details: [
+      'The function-typed element in which this parameter is declared is '
+          'assigned to a function whose matching parameter is nullable'
+    ]);
+    assertDetail(detail: regions[1].details[0], offset: 70, length: 2);
+  }
+
+  Future<void> test_functionType_nullableReturn() async {
+    UnitInfo unit = await buildInfoForSingleTestFile('''
+class C {
+  int Function() _cb = () => 7;
+  f(int Function() cb) {
+    _cb = cb;
+  }
+  g() {
+    f(() => null);
+  }
+}
+''', migratedContent: '''
+class C {
+  int? Function() _cb = () => 7;
+  f(int? Function() cb) {
+    _cb = cb;
+  }
+  g() {
+    f(() => null);
+  }
+}
+''');
+    List<RegionInfo> regions = unit.fixRegions;
+    expect(regions, hasLength(2));
+    assertRegion(region: regions[0], offset: 15, details: [
+      'A function-typed value with a nullable return type is assigned'
+    ]);
+    assertDetail(detail: regions[0].details[0], offset: 77, length: 2);
+  }
+
+  Future<void> test_insertedRequired_fieldFormal() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class C {
   int level;
@@ -570,7 +742,7 @@
         edit: edits[0], offset: 42, length: 0, replacement: '@required ');
   }
 
-  test_insertedRequired_parameter() async {
+  Future<void> test_insertedRequired_parameter() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class C {
   int level;
@@ -596,7 +768,7 @@
     // regions[2] is the `level!` fix.
   }
 
-  test_insertParens() async {
+  Future<void> test_insertParens() async {
     var originalContent = '''
 class C {
   C operator+(C c) => null;
@@ -625,7 +797,7 @@
         details: ['This value must be null-checked before use here.']);
   }
 
-  test_listAndSetLiteralTypeArgument() async {
+  Future<void> test_listAndSetLiteralTypeArgument() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f() {
   String s = null;
@@ -654,7 +826,7 @@
     assertDetail(detail: regions[2].details[0], offset: 90, length: 1);
   }
 
-  test_listConstructor_length() async {
+  Future<void> test_listConstructor_length() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f() {
   List<int> list = List<int>(10);
@@ -668,13 +840,13 @@
     expect(regions, hasLength(2));
     // regions[0] is `num? a`.
     assertRegion(region: regions[1], offset: 39, details: [
-      'List value type must be nullable because a length is specified,'
-          ' and the list items are initialized as null.'
+      'A length is specified in the "List()" constructor and the list items '
+          'are initialized to null'
     ]);
   }
 
   @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/40064')
-  test_listConstructor_length_implicitType() async {
+  Future<void> test_listConstructor_length_implicitType() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f() {
   List<int> list = List(10);
@@ -693,7 +865,7 @@
     ]);
   }
 
-  test_listLiteralTypeArgument_collectionIf() async {
+  Future<void> test_listLiteralTypeArgument_collectionIf() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f() {
   String s = null;
@@ -721,7 +893,7 @@
     assertDetail(detail: regions[1].details[0], offset: 79, length: 1);
   }
 
-  test_localVariable() async {
+  Future<void> test_localVariable() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f() {
   int v1 = null;
@@ -745,7 +917,7 @@
         details: ['This variable is initialized to a nullable value']);
   }
 
-  test_mapLiteralTypeArgument() async {
+  Future<void> test_mapLiteralTypeArgument() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f() {
   String s = null;
@@ -774,7 +946,7 @@
     assertDetail(detail: regions[2].details[0], offset: 128, length: 1);
   }
 
-  test_namedParameterWithDefault_fromOverridden_explicit() async {
+  Future<void> test_namedParameterWithDefault_fromOverridden_explicit() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   void m({int p = 0}) {}
@@ -805,7 +977,7 @@
     assertDetail(detail: regions[1].details[0], offset: 20, length: 3);
   }
 
-  test_nonNullableType_assert() async {
+  Future<void> test_nonNullableType_assert() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f(String s) {
   assert(s != null);
@@ -824,7 +996,7 @@
         details: ['This value is asserted to be non-null']);
   }
 
-  test_nonNullableType_exclamationComment() async {
+  Future<void> test_nonNullableType_exclamationComment() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f(String /*!*/ s) {}
 ''', migratedContent: '''
@@ -837,7 +1009,7 @@
     ]);
   }
 
-  test_nonNullableType_unconditionalFieldAccess() async {
+  Future<void> test_nonNullableType_unconditionalFieldAccess() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f(String s) {
   print(s.length);
@@ -854,7 +1026,7 @@
     ]);
   }
 
-  test_nullCheck_onMemberAccess() async {
+  Future<void> test_nullCheck_onMemberAccess() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class C {
   int value;
@@ -883,7 +1055,7 @@
     assertEdit(edit: edits[0], offset: 64, length: 0, replacement: '/*!*/');
   }
 
-  test_nullCheck_onMethodCall() async {
+  Future<void> test_nullCheck_onMethodCall() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class C {
   int value;
@@ -909,7 +1081,7 @@
     ]);
   }
 
-  test_parameter_fromInvocation_explicit() async {
+  Future<void> test_parameter_fromInvocation_explicit() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f(String s) {}
 void g() {
@@ -929,7 +1101,7 @@
         details: ["An explicit 'null' is passed as an argument"]);
   }
 
-  test_parameter_fromInvocation_implicit() async {
+  Future<void> test_parameter_fromInvocation_implicit() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f(String s) {}
 void g(p) {
@@ -950,7 +1122,7 @@
     ]);
   }
 
-  test_parameter_fromMultipleOverridden_explicit() async {
+  Future<void> test_parameter_fromMultipleOverridden_explicit() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   void m(int p) {}
@@ -991,7 +1163,7 @@
     assertDetail(detail: regions[2].details[0], offset: 60, length: 3);
   }
 
-  test_parameter_fromMultipleOverridden_implicit() async {
+  Future<void> test_parameter_fromMultipleOverridden_implicit() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   void m(int p) {}
@@ -1028,7 +1200,7 @@
   }
 
   @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/39378')
-  test_parameter_fromOverridden_implicit() async {
+  Future<void> test_parameter_fromOverridden_implicit() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   void m(p) {}
@@ -1054,7 +1226,7 @@
         details: ['A nullable value is assigned']);
   }
 
-  test_parameter_fromOverriddenField_explicit() async {
+  Future<void> test_parameter_fromOverriddenField_explicit() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   int m;
@@ -1087,7 +1259,7 @@
     assertDetail(detail: regions[1].details[0], offset: 12, length: 3);
   }
 
-  test_parameter_named_omittedInCall() async {
+  Future<void> test_parameter_named_omittedInCall() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f() { g(); }
 
@@ -1100,13 +1272,35 @@
     List<RegionInfo> regions = unit.fixRegions;
     expect(regions, hasLength(1));
     assertRegion(region: regions[0], offset: 30, details: [
-      'This named parameter was omitted in a call to this function',
+      'This named parameter is omitted in a call to this function',
       "This parameter has an implicit default value of 'null'",
     ]);
     assertDetail(detail: regions[0].details[0], offset: 11, length: 3);
   }
 
-  test_parameter_optional_explicitDefault_null() async {
+  Future<void> test_parameter_named_omittedInCall_inArgumentList() async {
+    UnitInfo unit = await buildInfoForSingleTestFile('''
+int f({int compare}) => 7
+void g() {
+  h(f());
+}
+void h(int x) {}
+''', migratedContent: '''
+int f({int? compare}) => 7
+void g() {
+  h(f());
+}
+void h(int x) {}
+''');
+    List<RegionInfo> regions = unit.fixRegions;
+    expect(regions, hasLength(1));
+    assertRegion(region: regions[0], offset: 10, details: [
+      "This parameter has an implicit default value of 'null'",
+      'This named parameter is omitted in a call to this function'
+    ]);
+  }
+
+  Future<void> test_parameter_optional_explicitDefault_null() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f({String s = null}) {}
 ''', migratedContent: '''
@@ -1120,7 +1314,7 @@
         details: ["This parameter has an explicit default value of 'null'"]);
   }
 
-  test_parameter_optional_explicitDefault_nullable() async {
+  Future<void> test_parameter_optional_explicitDefault_nullable() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 String sd = null;
 void f({String s = sd}) {}
@@ -1136,7 +1330,7 @@
         details: ['This parameter has a nullable default value']);
   }
 
-  test_parameter_optional_implicitDefault_named() async {
+  Future<void> test_parameter_optional_implicitDefault_named() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f({String s}) {}
 ''', migratedContent: '''
@@ -1150,7 +1344,7 @@
         details: ["This parameter has an implicit default value of 'null'"]);
   }
 
-  test_parameter_optional_implicitDefault_positional() async {
+  Future<void> test_parameter_optional_implicitDefault_positional() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f([String s]) {}
 ''', migratedContent: '''
@@ -1164,7 +1358,7 @@
         details: ["This parameter has an implicit default value of 'null'"]);
   }
 
-  test_removal_handles_offsets_correctly() async {
+  Future<void> test_removal_handles_offsets_correctly() async {
     var originalContent = '''
 void f(num n, int/*?*/ i) {
   if (n is! int) return;
@@ -1184,9 +1378,8 @@
     UnitInfo unit = await buildInfoForSingleTestFile(originalContent,
         migratedContent: migratedContent, removeViaComments: false);
     List<RegionInfo> regions = unit.regions;
-    expect(regions, hasLength(4));
+    expect(regions, hasLength(3));
     // regions[0] is the addition of `?` to the type of `i`.
-    // TODO(paulberry): why does the discarded downcast appear twice?
     assertRegion(
         region: regions[1],
         offset: migratedContent.indexOf(' as int'),
@@ -1194,16 +1387,11 @@
         details: []);
     assertRegion(
         region: regions[2],
-        offset: migratedContent.indexOf(' as int'),
-        length: 0,
-        details: []);
-    assertRegion(
-        region: regions[3],
         offset: migratedContent.indexOf('! + 1'),
         details: ['node with no info (never)']);
   }
 
-  test_return_fromOverriden() async {
+  Future<void> test_return_fromOverriden() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 abstract class A {
   String m();
@@ -1228,7 +1416,7 @@
     assertDetail(detail: regions[0].details[0], offset: 60, length: 6);
   }
 
-  test_return_multipleReturns() async {
+  Future<void> test_return_multipleReturns() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 String g() {
   int x = 1;
@@ -1251,7 +1439,7 @@
     assertInTargets(targets: unit.targets, offset: 40, length: 6); // "return"
   }
 
-  test_returnDetailTarget() async {
+  Future<void> test_returnDetailTarget() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 String g() {
   return 1 == 2 ? "Hello" : null;
@@ -1272,7 +1460,7 @@
     assertDetail(detail: regions[0].details[0], offset: 15, length: 6);
   }
 
-  test_returnType_function_expression() async {
+  Future<void> test_returnType_function_expression() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 int _f = null;
 int f() => _f;
@@ -1292,7 +1480,7 @@
         details: ['This function returns a nullable value on line 2']);
   }
 
-  test_returnType_getter_block() async {
+  Future<void> test_returnType_getter_block() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   int _f = null;
@@ -1320,7 +1508,7 @@
         details: ['This getter returns a nullable value on line 4']);
   }
 
-  test_returnType_getter_expression() async {
+  Future<void> test_returnType_getter_expression() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class A {
   int _f = null;
@@ -1344,7 +1532,7 @@
         details: ['This getter returns a nullable value on line 3']);
   }
 
-  test_setLiteralTypeArgument_nestedList() async {
+  Future<void> test_setLiteralTypeArgument_nestedList() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f() {
   String s = null;
@@ -1374,7 +1562,7 @@
     assertDetail(detail: regions[1].details[0], offset: 87, length: 3);
   }
 
-  test_topLevelVariable() async {
+  Future<void> test_topLevelVariable() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 int _f = null;
 int _f2 = _f;
@@ -1394,7 +1582,7 @@
         details: ['This variable is initialized to a nullable value']);
   }
 
-  test_uninitializedField() async {
+  Future<void> test_uninitializedField() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 class C {
   int value;
@@ -1431,7 +1619,7 @@
     assertDetail(detail: region.details[2], offset: 70, length: 3);
   }
 
-  test_uninitializedVariable_notLate_uninitializedUse() async {
+  Future<void> test_uninitializedVariable_notLate_uninitializedUse() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f() {
   int v1;
diff --git a/pkg/analysis_server/test/src/edit/nnbd_migration/instrumentation_renderer_test.dart b/pkg/analysis_server/test/src/edit/nnbd_migration/instrumentation_renderer_test.dart
index c273850..dbc0e4a 100644
--- a/pkg/analysis_server/test/src/edit/nnbd_migration/instrumentation_renderer_test.dart
+++ b/pkg/analysis_server/test/src/edit/nnbd_migration/instrumentation_renderer_test.dart
@@ -10,7 +10,7 @@
 
 import 'nnbd_migration_test_base.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InstrumentationRendererTest);
   });
@@ -29,116 +29,10 @@
     return instrumentationRenderer.render();
   }
 
-  test_navigation_containsRoot() async {
+  Future<void> test_navigation_containsRoot() async {
     var renderedView = await renderViewForTestFiles(
         {convertPath('/project/lib/a.dart'): 'int a = null;'});
     var expectedPath = convertPath('/project');
     expect(renderedView, contains('<p class="root">$expectedPath</p>'));
   }
-
-  test_navigation_containsMultipleLinks_multipleRoots() async {
-    var renderedView = await renderViewForTestFiles({
-      convertPath('/project/bin/bin.dart'): 'int c = null;',
-      convertPath('/project/lib/a.dart'): 'int a = null;',
-      convertPath('/project/lib/src/b.dart'): 'int b = null;',
-      convertPath('/project/test/test.dart'): 'int d = null;',
-    });
-    renderedView = _stripAttributes(renderedView);
-    expect(renderedView, contains('''
-<ul>
-  <li class="dir"><span class="arrow">&#x25BC;</span>&#x1F4C1;bin
-    <ul>
-      <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">bin.dart</a> (1 modification)</li>
-    </ul>
-  </li>
-  <li class="dir"><span class="arrow">&#x25BC;</span>&#x1F4C1;lib
-    <ul>
-      <li class="dir"><span class="arrow">&#x25BC;</span>&#x1F4C1;src
-        <ul>
-          <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">b.dart</a> (1 modification)</li>
-        </ul>
-      </li>
-      <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">a.dart</a> (1 modification)</li>
-    </ul>
-  </li>
-  <li class="dir"><span class="arrow">&#x25BC;</span>&#x1F4C1;test
-    <ul>
-      <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">test.dart</a> (1 modification)</li>
-    </ul>
-  </li>
-</ul>'''));
-  }
-
-  test_navigation_containsMultipleLinks_multipleDepths() async {
-    var renderedView = await renderViewForTestFiles({
-      convertPath('/project/lib/a.dart'): 'int a = null;',
-      convertPath('/project/lib/src/b.dart'): 'int b = null;',
-      convertPath('/project/tool.dart'): 'int c = null;'
-    });
-    renderedView = _stripAttributes(renderedView);
-    expect(renderedView, contains('''
-<ul>
-  <li class="dir"><span class="arrow">&#x25BC;</span>&#x1F4C1;lib
-    <ul>
-      <li class="dir"><span class="arrow">&#x25BC;</span>&#x1F4C1;src
-        <ul>
-          <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">b.dart</a> (1 modification)</li>
-        </ul>
-      </li>
-      <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">a.dart</a> (1 modification)</li>
-    </ul>
-  </li>
-  <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">tool.dart</a> (1 modification)</li>
-</ul>'''));
-  }
-
-  test_navigation_containsMultipleLinks_sameDepth() async {
-    var renderedView = await renderViewForTestFiles({
-      convertPath('/project/lib/a.dart'): 'int a = null;',
-      convertPath('/project/lib/b.dart'): 'int b = null;'
-    });
-    renderedView = _stripAttributes(renderedView);
-    expect(renderedView, contains('''
-<ul>
-  <li class="dir"><span class="arrow">&#x25BC;</span>&#x1F4C1;lib
-    <ul>
-      <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">a.dart</a> (1 modification)</li>
-      <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">b.dart</a> (1 modification)</li>
-    </ul>
-  </li>
-</ul>'''));
-  }
-
-  test_navigation_containsSingleLink_deep() async {
-    var renderedView = await renderViewForTestFiles(
-        {convertPath('/project/lib/src/a.dart'): 'int a = null;'});
-    renderedView = _stripAttributes(renderedView);
-    expect(renderedView, contains('''
-<ul>
-  <li class="dir"><span class="arrow">&#x25BC;</span>&#x1F4C1;lib
-    <ul>
-      <li class="dir"><span class="arrow">&#x25BC;</span>&#x1F4C1;src
-        <ul>
-          <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">a.dart</a> (1 modification)</li>
-        </ul>
-      </li>
-    </ul>
-  </li>
-</ul>'''));
-  }
-
-  test_navigation_containsSingleLink_shallow() async {
-    var renderedView = await renderViewForTestFiles(
-        {convertPath('/project/a.dart'): 'int a = null;'});
-    renderedView = _stripAttributes(renderedView);
-    expect(renderedView, contains('''
-<ul>
-  <li>&#x1F4C4;<a href="..." class="nav-link" data-name="...">a.dart</a> (1 modification)</li>
-</ul>'''));
-  }
-
-  /// Strips out attributes which are not being tested.
-  String _stripAttributes(String html) => html
-      .replaceAll(RegExp('href=".*?"'), 'href="..."')
-      .replaceAll(RegExp('data-name=".*?"'), 'data-name="..."');
 }
diff --git a/pkg/analysis_server/test/src/edit/nnbd_migration/navigation_tree_renderer_test.dart b/pkg/analysis_server/test/src/edit/nnbd_migration/navigation_tree_renderer_test.dart
new file mode 100644
index 0000000..10a1557
--- /dev/null
+++ b/pkg/analysis_server/test/src/edit/nnbd_migration/navigation_tree_renderer_test.dart
@@ -0,0 +1,297 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:convert' show jsonDecode;
+
+import 'package:analysis_server/src/edit/nnbd_migration/migration_info.dart';
+import 'package:analysis_server/src/edit/nnbd_migration/navigation_tree_renderer.dart';
+import 'package:analysis_server/src/edit/nnbd_migration/path_mapper.dart';
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import 'nnbd_migration_test_base.dart';
+
+void main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(JsonMapTypeMatcherTest);
+    defineReflectiveTests(NavigationTreeRendererTest);
+  });
+}
+
+const isJsonMap = TypeMatcher<Map<String, dynamic>>();
+
+@reflectiveTest
+class JsonMapTypeMatcherTest {
+  void test_containing_doesNotMatch_invalidMatchers() {
+    expect(
+        isJsonMap.containing({'a': isJsonMap}).matches({
+          'a': [1, 2, 3]
+        }, {}),
+        isFalse);
+  }
+
+  void test_containing_doesNotMatch_invalidMatchers_list() {
+    expect(
+        isJsonMap.containing({
+          'a': isJsonMap.containing({
+            'b': [1, 2, 3]
+          })
+        }).matches({
+          'a': {
+            'b': [1, 2, 3, 4]
+          }
+        }, {}),
+        isFalse);
+  }
+
+  void test_containing_doesNotMatch_invalidValues() {
+    expect(isJsonMap.containing({'a': 1}).matches({'a': 2}, {}), isFalse);
+  }
+
+  void test_containing_matches_validMatchers() {
+    expect(
+        isJsonMap.containing({'a': isJsonMap}).matches(
+            {'a': <String, dynamic>{}}, {}),
+        isTrue);
+  }
+
+  void test_containing_matches_validMatchers_list() {
+    expect(
+        isJsonMap.containing({
+          'a': isJsonMap.containing({
+            'b': [1, 2, 3]
+          })
+        }).matches({
+          'a': {
+            'b': [1, 2, 3]
+          }
+        }, {}),
+        isTrue);
+  }
+
+  void test_containing_matches_validValues() {
+    expect(isJsonMap.containing({'a': 1}).matches({'a': 1}, {}), isTrue);
+  }
+
+  void test_isJsonMap_doesNotMatch_nonMaps() {
+    expect(isJsonMap.matches([], {}), isFalse);
+  }
+
+  void test_isJsonMap_doesNotMatch_nonStringKeyedMaps() {
+    expect(isJsonMap.matches(<int, int>{}, {}), isFalse);
+  }
+
+  void test_isJsonMap_matchesStringKeyedMaps() {
+    expect(isJsonMap.matches(<String, dynamic>{}, {}), isTrue);
+  }
+}
+
+@reflectiveTest
+class NavigationTreeRendererTest extends NnbdMigrationTestBase {
+  /// Render the navigation tree view for [files].
+  Future<String> renderNavigationTree(Map<String, String> files) async {
+    var packageRoot = convertPath('/project');
+    await buildInfoForTestFiles(files, includedRoot: packageRoot);
+    MigrationInfo migrationInfo =
+        MigrationInfo(infos, {}, resourceProvider.pathContext, packageRoot);
+    return NavigationTreeRenderer(migrationInfo, PathMapper(resourceProvider))
+        .render();
+  }
+
+  Future<void> test_containsEditCounts() async {
+    var response = jsonDecode(await renderNavigationTree({
+      convertPath('/project/lib/a.dart'): 'int a = 1;',
+      convertPath('/project/lib/b.dart'): 'int b = null;',
+      convertPath('/project/lib/c.dart'): 'int c = null;\nint d = null;',
+    }));
+
+    var libNode = response[0];
+    expect(
+        libNode,
+        isJsonMap.containing({
+          'subtree': [
+            isJsonMap.containing({'editCount': 0}),
+            isJsonMap.containing({'editCount': 1}),
+            isJsonMap.containing({'editCount': 2})
+          ]
+        }));
+  }
+
+  Future<void> test_containsHrefs() async {
+    var response = jsonDecode(await renderNavigationTree({
+      convertPath('/project/lib/a.dart'): 'int a = null;',
+      convertPath('/project/lib/src/b.dart'): 'int b = null;',
+      convertPath('/project/tool.dart'): 'int c = null;',
+    }));
+
+    var libNode = response[0];
+    expect(
+        libNode,
+        isJsonMap.containing({
+          'name': 'lib',
+          'subtree': [
+            isJsonMap.containing({
+              'name': 'src',
+              'subtree': [
+                isJsonMap.containing(
+                    {'href': convertPath('/project/lib/src/b.dart')})
+              ]
+            }),
+            isJsonMap.containing({'href': convertPath('/project/lib/a.dart')})
+          ]
+        }));
+
+    var toolNode = response[1];
+    expect(toolNode['href'], convertPath('/project/tool.dart'));
+  }
+
+  Future<void> test_containsMultipleLinks_multipleDepths() async {
+    var response = jsonDecode(await renderNavigationTree({
+      convertPath('/project/lib/a.dart'): 'int a = null;',
+      convertPath('/project/lib/src/b.dart'): 'int b = null;',
+      convertPath('/project/tool.dart'): 'int c = null;',
+    }));
+    expect(response, hasLength(2));
+
+    var libNode = response[0];
+    expect(
+        libNode,
+        isJsonMap.containing({
+          'name': 'lib',
+          'subtree': [
+            isJsonMap.containing({
+              'name': 'src',
+              'subtree': [
+                isJsonMap.containing({'name': 'b.dart'})
+              ]
+            }),
+            isJsonMap.containing({'name': 'a.dart'})
+          ]
+        }));
+
+    var toolNode = response[1];
+    expect(toolNode['name'], 'tool.dart');
+  }
+
+  Future<void> test_containsMultipleLinks_multipleRoots() async {
+    var response = jsonDecode(await renderNavigationTree({
+      convertPath('/project/bin/bin.dart'): 'int c = null;',
+      convertPath('/project/lib/a.dart'): 'int a = null;',
+    }));
+    expect(response, hasLength(2));
+
+    var binNode = response[0];
+    expect(binNode['type'], equals('directory'));
+    expect(binNode['name'], equals('bin'));
+    expect(binNode['subtree'], hasLength(1));
+
+    var libNode = response[1];
+    expect(libNode['type'], equals('directory'));
+    expect(libNode['name'], equals('lib'));
+    expect(libNode['subtree'], hasLength(1));
+  }
+
+  Future<void> test_containsMultipleLinks_sameDepth() async {
+    var response = jsonDecode(await renderNavigationTree({
+      convertPath('/project/lib/a.dart'): 'int a = null;',
+      convertPath('/project/lib/b.dart'): 'int b = null;',
+    }));
+    expect(response, hasLength(1));
+
+    var libNode = response[0];
+    expect(
+        libNode,
+        isJsonMap.containing({
+          'name': 'lib',
+          'subtree': [
+            isJsonMap.containing({
+              'name': 'a.dart',
+              'path': convertPath('lib/a.dart'),
+              'href': convertPath('/project/lib/a.dart')
+            }),
+            isJsonMap.containing({
+              'name': 'b.dart',
+              'path': convertPath('lib/b.dart'),
+              'href': convertPath('/project/lib/b.dart')
+            })
+          ]
+        }));
+  }
+
+  Future<void> test_containsPaths() async {
+    var response = jsonDecode(await renderNavigationTree({
+      convertPath('/project/lib/a.dart'): 'int a = null;',
+      convertPath('/project/lib/src/b.dart'): 'int b = null;',
+      convertPath('/project/tool.dart'): 'int c = null;',
+    }));
+
+    var libNode = response[0];
+    expect(
+        libNode,
+        isJsonMap.containing({
+          'name': 'lib',
+          'subtree': [
+            isJsonMap.containing({
+              'name': 'src',
+              'subtree': [
+                isJsonMap.containing({'path': convertPath('lib/src/b.dart')})
+              ]
+            }),
+            isJsonMap.containing({'path': convertPath('lib/a.dart')})
+          ]
+        }));
+
+    var toolNode = response[1];
+    expect(toolNode['path'], 'tool.dart');
+  }
+
+  Future<void> test_containsSingleLink_deep() async {
+    var response = jsonDecode(await renderNavigationTree({
+      convertPath('/project/lib/src/a.dart'): 'int a = null;',
+    }));
+    expect(response, hasLength(1));
+
+    var libNode = response[0];
+    expect(
+        libNode,
+        isJsonMap.containing({
+          'name': 'lib',
+          'subtree': [
+            isJsonMap.containing({
+              'name': 'src',
+              'subtree': [
+                isJsonMap.containing({
+                  'name': 'a.dart',
+                  'path': convertPath('lib/src/a.dart'),
+                  'href': convertPath('/project/lib/src/a.dart')
+                })
+              ]
+            })
+          ]
+        }));
+  }
+
+  Future<void> test_containsSingleLink_shallow() async {
+    var response = jsonDecode(await renderNavigationTree({
+      convertPath('/project/a.dart'): 'int a = null;',
+    }));
+    expect(response, hasLength(1));
+
+    var aNode = response[0];
+    expect(aNode['name'], 'a.dart');
+    expect(aNode['path'], 'a.dart');
+    expect(aNode['href'], convertPath('/project/a.dart'));
+  }
+}
+
+extension _E<T, U> on TypeMatcher<Map<T, U>> {
+  TypeMatcher<Map<T, U>> containing(Map<T, dynamic> matchers) {
+    var result = this;
+    for (var entry in matchers.entries) {
+      result = result.having(
+          (map) => map[entry.key], entry.key.toString(), entry.value);
+    }
+    return result;
+  }
+}
diff --git a/pkg/analysis_server/test/src/edit/nnbd_migration/offset_mapper_test.dart b/pkg/analysis_server/test/src/edit/nnbd_migration/offset_mapper_test.dart
index 4697e18..a8302c4 100644
--- a/pkg/analysis_server/test/src/edit/nnbd_migration/offset_mapper_test.dart
+++ b/pkg/analysis_server/test/src/edit/nnbd_migration/offset_mapper_test.dart
@@ -9,7 +9,7 @@
 
 import '../../../analysis_abstract.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(OffsetMapperTest);
   });
@@ -17,14 +17,14 @@
 
 @reflectiveTest
 class OffsetMapperTest extends AbstractAnalysisTest {
-  test_identity() {
+  void test_identity() {
     OffsetMapper mapper = OffsetMapper.identity;
     expect(mapper.map(0), 0);
     expect(mapper.map(20), 20);
     expect(mapper.map(0xFFFFFF), 0xFFFFFF);
   }
 
-  test_multipleEdits() {
+  void test_multipleEdits() {
     OffsetMapper mapper = OffsetMapper.forEdits([
       SourceEdit(13, 0, '?'),
       SourceEdit(21, 0, '!'),
@@ -40,7 +40,7 @@
     expect(mapper.map(55), 58);
   }
 
-  test_singleEdit() {
+  void test_singleEdit() {
     OffsetMapper mapper = OffsetMapper.forEdits([
       SourceEdit(13, 0, '?'),
     ]);
diff --git a/pkg/analysis_server/test/src/edit/nnbd_migration/region_renderer_test.dart b/pkg/analysis_server/test/src/edit/nnbd_migration/region_renderer_test.dart
index 093578e..fe76e3d 100644
--- a/pkg/analysis_server/test/src/edit/nnbd_migration/region_renderer_test.dart
+++ b/pkg/analysis_server/test/src/edit/nnbd_migration/region_renderer_test.dart
@@ -12,7 +12,7 @@
 
 import 'nnbd_migration_test_base.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RegionRendererTest);
   });
@@ -20,8 +20,8 @@
 
 @reflectiveTest
 class RegionRendererTest extends NnbdMigrationTestBase {
-  /// Render [libraryInfo], using a [MigrationInfo] which knows only about this
-  /// library.
+  /// Render the region at [offset], using a [MigrationInfo] which knows only
+  /// about the library at `infos.single`.
   String renderRegion(int offset) {
     String packageRoot = convertPath('/package');
     MigrationInfo migrationInfo =
@@ -33,7 +33,7 @@
         .render();
   }
 
-  test_modifiedOutput_containsDetail() async {
+  Future<void> test_modifiedOutput_containsDetail() async {
     await buildInfoForSingleTestFile('int a = null;',
         migratedContent: 'int? a = null;');
     var response = jsonDecode(renderRegion(3));
@@ -45,7 +45,7 @@
     expect(detail['link']['href'], equals('test.dart?offset=8&line=1'));
   }
 
-  test_modifiedOutput_containsExplanation() async {
+  Future<void> test_modifiedOutput_containsExplanation() async {
     await buildInfoForSingleTestFile('int a = null;',
         migratedContent: 'int? a = null;');
     var response = jsonDecode(renderRegion(3));
@@ -53,7 +53,7 @@
         response['explanation'], equals("Changed type 'int' to be nullable"));
   }
 
-  test_modifiedOutput_containsPath() async {
+  Future<void> test_modifiedOutput_containsPath() async {
     await buildInfoForSingleTestFile('int a = null;',
         migratedContent: 'int? a = null;');
     var response = jsonDecode(renderRegion(3));
@@ -61,7 +61,7 @@
     expect(response['line'], equals(1));
   }
 
-  test_unmodifiedOutput_containsDetail() async {
+  Future<void> test_unmodifiedOutput_containsDetail() async {
     await buildInfoForSingleTestFile('f(int a) => a.isEven;',
         migratedContent: 'f(int a) => a.isEven;');
     var response = jsonDecode(renderRegion(2));
@@ -75,7 +75,7 @@
     expect(detail['link']['href'], equals('test.dart?offset=12&line=1'));
   }
 
-  test_unmodifiedOutput_containsExplanation() async {
+  Future<void> test_unmodifiedOutput_containsExplanation() async {
     await buildInfoForSingleTestFile('f(int a) => a.isEven;',
         migratedContent: 'f(int a) => a.isEven;');
     var response = jsonDecode(renderRegion(2));
@@ -85,7 +85,7 @@
             'This type is not changed; it is determined to be non-nullable'));
   }
 
-  test_unmodifiedOutput_containsPath() async {
+  Future<void> test_unmodifiedOutput_containsPath() async {
     await buildInfoForSingleTestFile('f(int a) => a.isEven;',
         migratedContent: 'f(int a) => a.isEven;');
     var response = jsonDecode(renderRegion(2));
diff --git a/pkg/analysis_server/test/src/edit/nnbd_migration/test_all.dart b/pkg/analysis_server/test/src/edit/nnbd_migration/test_all.dart
index 632278c..f2277ef 100644
--- a/pkg/analysis_server/test/src/edit/nnbd_migration/test_all.dart
+++ b/pkg/analysis_server/test/src/edit/nnbd_migration/test_all.dart
@@ -6,14 +6,16 @@
 
 import 'info_builder_test.dart' as info_builder;
 import 'instrumentation_renderer_test.dart' as instrumentation_renderer;
+import 'navigation_tree_renderer_test.dart' as navigation_tree_renderer;
 import 'offset_mapper_test.dart' as offset_mapper;
 import 'region_renderer_test.dart' as region_renderer;
 import 'unit_renderer_test.dart' as unit_renderer;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     info_builder.main();
     instrumentation_renderer.main();
+    navigation_tree_renderer.main();
     offset_mapper.main();
     region_renderer.main();
     unit_renderer.main();
diff --git a/pkg/analysis_server/test/src/edit/nnbd_migration/unit_renderer_test.dart b/pkg/analysis_server/test/src/edit/nnbd_migration/unit_renderer_test.dart
index 5f5105b..20283a7 100644
--- a/pkg/analysis_server/test/src/edit/nnbd_migration/unit_renderer_test.dart
+++ b/pkg/analysis_server/test/src/edit/nnbd_migration/unit_renderer_test.dart
@@ -12,7 +12,7 @@
 
 import 'nnbd_migration_test_base.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UnitRendererTest);
   });
@@ -36,31 +36,7 @@
     return contents;
   }
 
-  test_editList_containsEdit() async {
-    await buildInfoForSingleTestFile('int a = null;',
-        migratedContent: 'int? a = null;');
-    var outputJson = renderUnits()[0];
-    var output = jsonDecode(outputJson);
-    var editList = output['editList'];
-    expect(
-        editList,
-        contains('<p class="edit">'
-            '<input type="checkbox" title="Click to mark reviewed" '
-            'disabled="disabled">'
-            " line 1: Changed type 'int' to be nullable.</p>"));
-  }
-
-  test_editList_containsEdit_htmlEscaped() async {
-    await buildInfoForSingleTestFile('List<String> a = null;',
-        migratedContent: 'List<String>? a = null;');
-    var outputJson = renderUnits()[0];
-    var output = jsonDecode(outputJson);
-    var editList = output['editList'];
-    expect(editList,
-        contains("line 1: Changed type 'List&lt;String&gt;' to be nullable."));
-  }
-
-  test_editList_containsEdit_twoEdits() async {
+  Future<void> test_editList_containsCount() async {
     await buildInfoForSingleTestFile('''
 int a = null;
 bool b = a.isEven;
@@ -71,22 +47,10 @@
     var outputJson = renderUnits()[0];
     var output = jsonDecode(outputJson);
     var editList = output['editList'];
-    expect(editList, contains("line 1: Changed type 'int' to be nullable."));
-    expect(editList,
-        contains('line 2: Added a non-null assertion to nullable expression.'));
+    expect(editList['editCount'], equals(2));
   }
 
-  test_editList_containsSummary() async {
-    await buildInfoForSingleTestFile('int a = null;',
-        migratedContent: 'int? a = null;');
-    var outputJson = renderUnits()[0];
-    var output = jsonDecode(outputJson);
-    var editList = output['editList'];
-    expect(editList,
-        contains('<p><strong>1</strong> edit was made to this file.'));
-  }
-
-  test_editList_containsSummary_twoEdits() async {
+  Future<void> test_editList_containsEdits() async {
     await buildInfoForSingleTestFile('''
 int a = null;
 bool b = a.isEven;
@@ -97,11 +61,18 @@
     var outputJson = renderUnits()[0];
     var output = jsonDecode(outputJson);
     var editList = output['editList'];
-    expect(editList,
-        contains('<p><strong>2</strong> edits were made to this file.'));
+    expect(editList['edits'], hasLength(2));
+    expect(editList['edits'][0]['line'], equals(1));
+    expect(editList['edits'][0]['offset'], equals(3));
+    expect(editList['edits'][0]['explanation'],
+        equals("Changed type 'int' to be nullable"));
+    expect(editList['edits'][1]['line'], equals(2));
+    expect(editList['edits'][1]['offset'], equals(25));
+    expect(editList['edits'][1]['explanation'],
+        equals('Added a non-null assertion to nullable expression'));
   }
 
-  test_navContentContainsEscapedHtml() async {
+  Future<void> test_navContentContainsEscapedHtml() async {
     await buildInfoForSingleTestFile('List<String> a = null;',
         migratedContent: 'List<String>? a = null;');
     var outputJson = renderUnits()[0];
@@ -117,17 +88,17 @@
             r'<span id="o13">a</span> = <span id="o17">null</span>;'));
   }
 
-  test_outputContainsModifiedAndUnmodifiedRegions() async {
+  Future<void> test_outputContainsModifiedAndUnmodifiedRegions() async {
     await buildInfoForSingleTestFile('int a = null;',
         migratedContent: 'int? a = null;');
     var outputJson = renderUnits()[0];
     var output = jsonDecode(outputJson);
     var regions = _stripDataAttributes(output['regions']);
     expect(regions,
-        contains('int<span class="region fix-region">?</span> a = null;'));
+        contains('int<span class="region added-region">?</span> a = null;'));
   }
 
-  test_regionsContainsEscapedHtml_ampersand() async {
+  Future<void> test_regionsContainsEscapedHtml_ampersand() async {
     await buildInfoForSingleTestFile('bool a = true && false;',
         migratedContent: 'bool a = true && false;');
     var outputJson = renderUnits()[0];
@@ -135,7 +106,7 @@
     expect(output['regions'], contains('bool a = true &amp;&amp; false;'));
   }
 
-  test_regionsContainsEscapedHtml_betweenRegions() async {
+  Future<void> test_regionsContainsEscapedHtml_betweenRegions() async {
     await buildInfoForSingleTestFile('List<String> a = null;',
         migratedContent: 'List<String>? a = null;');
     var outputJson = renderUnits()[0];
@@ -144,10 +115,10 @@
     expect(
         regions,
         contains('List&lt;String&gt;'
-            '<span class="region fix-region">?</span> a = null;'));
+            '<span class="region added-region">?</span> a = null;'));
   }
 
-  test_regionsContainsEscapedHtml_region() async {
+  Future<void> test_regionsContainsEscapedHtml_region() async {
     await buildInfoForSingleTestFile('f(List<String> a) => a.join(",");',
         migratedContent: 'f(List<String> a) => a.join(",");');
     var outputJson = renderUnits()[0];
@@ -155,8 +126,8 @@
     var regions = _stripDataAttributes(output['regions']);
     expect(
         regions,
-        contains('<span class="region non-nullable-type-region">'
-            'List&lt;String&gt;</span>'));
+        contains(
+            '<span class="region unchanged-region">List&lt;String&gt;</span>'));
   }
 
   UnitInfo unit(String path, String content, {List<RegionInfo> regions}) {
diff --git a/pkg/analysis_server/test/src/edit/test_all.dart b/pkg/analysis_server/test/src/edit/test_all.dart
index 9e41ed2..b36abbb 100644
--- a/pkg/analysis_server/test/src/edit/test_all.dart
+++ b/pkg/analysis_server/test/src/edit/test_all.dart
@@ -7,7 +7,7 @@
 import 'fix/test_all.dart' as fix;
 import 'nnbd_migration/test_all.dart' as nnbd_migration;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     fix.main();
     nnbd_migration.main();
diff --git a/pkg/analysis_server/test/src/flutter/flutter_correction_test.dart b/pkg/analysis_server/test/src/flutter/flutter_correction_test.dart
index 43a7967..96a9bcc 100644
--- a/pkg/analysis_server/test/src/flutter/flutter_correction_test.dart
+++ b/pkg/analysis_server/test/src/flutter/flutter_correction_test.dart
@@ -8,7 +8,7 @@
 
 import '../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterCorrectionTest);
   });
diff --git a/pkg/analysis_server/test/src/flutter/flutter_outline_computer_test.dart b/pkg/analysis_server/test/src/flutter/flutter_outline_computer_test.dart
index f4172fd..9950666 100644
--- a/pkg/analysis_server/test/src/flutter/flutter_outline_computer_test.dart
+++ b/pkg/analysis_server/test/src/flutter/flutter_outline_computer_test.dart
@@ -12,7 +12,7 @@
 
 import '../../abstract_context.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterOutlineComputerTest);
   });
@@ -32,7 +32,7 @@
     addFlutterPackage();
   }
 
-  test_attribute_namedExpression() async {
+  Future<void> test_attribute_namedExpression() async {
     FlutterOutline unitOutline = await _computeOutline('''
 import 'package:flutter/widgets.dart';
 
@@ -57,59 +57,63 @@
     _assertLocation(attribute.valueLocation, 82, 2);
   }
 
-  test_attributes_bool() async {
+  Future<void> test_attributes_bool() async {
     var attribute = await _getAttribute('test', 'true');
     expect(attribute.label, 'true');
     expect(attribute.literalValueBoolean, true);
   }
 
-  test_attributes_functionExpression_hasParameters_blockExpression() async {
+  Future<void>
+      test_attributes_functionExpression_hasParameters_blockExpression() async {
     var attribute = await _getAttribute('test', '(a) {}');
     expect(attribute.label, '(…) { … }');
   }
 
-  test_attributes_functionExpression_hasParameters_bodyExpression() async {
+  Future<void>
+      test_attributes_functionExpression_hasParameters_bodyExpression() async {
     var attribute = await _getAttribute('test', '(a) => 1');
     expect(attribute.label, '(…) => …');
   }
 
-  test_attributes_functionExpression_noParameters_blockExpression() async {
+  Future<void>
+      test_attributes_functionExpression_noParameters_blockExpression() async {
     var attribute = await _getAttribute('test', '() {}');
     expect(attribute.label, '() { … }');
   }
 
-  test_attributes_functionExpression_noParameters_bodyExpression() async {
+  Future<void>
+      test_attributes_functionExpression_noParameters_bodyExpression() async {
     var attribute = await _getAttribute('test', '() => 1');
     expect(attribute.label, '() => …');
   }
 
-  test_attributes_int() async {
+  Future<void> test_attributes_int() async {
     var attribute = await _getAttribute('test', '42');
     expect(attribute.label, '42');
     expect(attribute.literalValueInteger, 42);
   }
 
-  test_attributes_listLiteral() async {
+  Future<void> test_attributes_listLiteral() async {
     var attribute = await _getAttribute('test', '[1, 2, 3]');
     expect(attribute.label, '[…]');
   }
 
-  test_attributes_mapLiteral() async {
+  Future<void> test_attributes_mapLiteral() async {
     var attribute = await _getAttribute('test', '{1: 10, 2: 20}');
     expect(attribute.label, '{…}');
   }
 
-  test_attributes_multiLine() async {
+  Future<void> test_attributes_multiLine() async {
     var attribute = await _getAttribute('test', '1 +\n 2');
     expect(attribute.label, '…');
   }
 
-  test_attributes_setLiteral() async {
+  Future<void> test_attributes_setLiteral() async {
     var attribute = await _getAttribute('test', '{1, 2}');
     expect(attribute.label, '{…}');
   }
 
-  test_attributes_string_interpolation() async {
+  Future<void> test_attributes_string_interpolation() async {
     FlutterOutline unitOutline = await _computeOutline(r'''
 import 'package:flutter/widgets.dart';
 
@@ -133,13 +137,13 @@
     expect(attribute.literalValueString, isNull);
   }
 
-  test_attributes_string_literal() async {
+  Future<void> test_attributes_string_literal() async {
     var attribute = await _getAttribute('test', "'my text'");
     expect(attribute.label, "'my text'");
     expect(attribute.literalValueString, 'my text');
   }
 
-  test_attributes_unresolved() async {
+  Future<void> test_attributes_unresolved() async {
     FlutterOutline unitOutline = await _computeOutline('''
 import 'package:flutter/widgets.dart';
 
@@ -157,7 +161,7 @@
     expect(rowOutline.attributes, isEmpty);
   }
 
-  test_children() async {
+  Future<void> test_children() async {
     FlutterOutline unitOutline = await _computeOutline('''
 import 'package:flutter/widgets.dart';
 
@@ -207,7 +211,7 @@
     }
   }
 
-  test_children_closure_blockBody() async {
+  Future<void> test_children_closure_blockBody() async {
     newFile('/home/test/lib/a.dart', content: r'''
 import 'package:flutter/widgets.dart';
 
@@ -243,7 +247,7 @@
 ''');
   }
 
-  test_children_closure_expressionBody() async {
+  Future<void> test_children_closure_expressionBody() async {
     newFile('/home/test/lib/a.dart', content: r'''
 import 'package:flutter/widgets.dart';
 
@@ -274,7 +278,7 @@
 ''');
   }
 
-  test_children_withCollectionElements() async {
+  Future<void> test_children_withCollectionElements() async {
     FlutterOutline unitOutline = await _computeOutline('''
 import 'package:flutter/widgets.dart';
 
@@ -301,7 +305,7 @@
 ''');
   }
 
-  test_codeOffsetLength() async {
+  Future<void> test_codeOffsetLength() async {
     FlutterOutline unitOutline = await _computeOutline('''
 import 'package:flutter/widgets.dart';
 
@@ -332,7 +336,7 @@
     expect(container.codeLength, 15);
   }
 
-  test_genericLabel_invocation() async {
+  Future<void> test_genericLabel_invocation() async {
     FlutterOutline unitOutline = await _computeOutline(r'''
 import 'package:flutter/widgets.dart';
 
@@ -388,7 +392,7 @@
     }
   }
 
-  test_parentAssociationLabel() async {
+  Future<void> test_parentAssociationLabel() async {
     newFile('/home/test/lib/a.dart', content: r'''
 import 'package:flutter/widgets.dart';
 
@@ -422,7 +426,7 @@
 ''');
   }
 
-  test_variableName() async {
+  Future<void> test_variableName() async {
     FlutterOutline unitOutline = await _computeOutline('''
 import 'package:flutter/widgets.dart';
 
diff --git a/pkg/analysis_server/test/src/flutter/flutter_outline_notification_test.dart b/pkg/analysis_server/test/src/flutter/flutter_outline_notification_test.dart
index 250cb06..a9c7518 100644
--- a/pkg/analysis_server/test/src/flutter/flutter_outline_notification_test.dart
+++ b/pkg/analysis_server/test/src/flutter/flutter_outline_notification_test.dart
@@ -15,7 +15,7 @@
 import '../../analysis_abstract.dart';
 import '../utilities/mock_packages.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterNotificationOutlineTest);
   });
diff --git a/pkg/analysis_server/test/src/flutter/test_all.dart b/pkg/analysis_server/test/src/flutter/test_all.dart
index 09ef471..66e99d6 100644
--- a/pkg/analysis_server/test/src/flutter/test_all.dart
+++ b/pkg/analysis_server/test/src/flutter/test_all.dart
@@ -8,7 +8,7 @@
 import 'flutter_outline_computer_test.dart' as outline_computer;
 import 'flutter_outline_notification_test.dart' as outline_notification;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     flutter_correction.main();
     outline_computer.main();
diff --git a/pkg/analysis_server/test/src/lsp/lsp_packet_transformer_test.dart b/pkg/analysis_server/test/src/lsp/lsp_packet_transformer_test.dart
index ee603c7..a119979 100644
--- a/pkg/analysis_server/test/src/lsp/lsp_packet_transformer_test.dart
+++ b/pkg/analysis_server/test/src/lsp/lsp_packet_transformer_test.dart
@@ -7,7 +7,7 @@
 import 'package:analysis_server/src/lsp/lsp_packet_transformer.dart';
 import 'package:test/test.dart';
 
-main() {
+void main() {
   group('lsp_packet_transformer', () {
     test('transforms data received as individual bytes', () async {
       final payload = '{ json payload }';
diff --git a/pkg/analysis_server/test/src/lsp/test_all.dart b/pkg/analysis_server/test/src/lsp/test_all.dart
index fa29bbd..5f61e61 100644
--- a/pkg/analysis_server/test/src/lsp/test_all.dart
+++ b/pkg/analysis_server/test/src/lsp/test_all.dart
@@ -6,7 +6,7 @@
 
 import 'lsp_packet_transformer_test.dart' as lsp_packet_transformer;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     lsp_packet_transformer.main();
   }, name: 'lsp');
diff --git a/pkg/analysis_server/test/src/plugin/notification_manager_test.dart b/pkg/analysis_server/test/src/plugin/notification_manager_test.dart
index 5dfe529..8ffa2bf 100644
--- a/pkg/analysis_server/test/src/plugin/notification_manager_test.dart
+++ b/pkg/analysis_server/test/src/plugin/notification_manager_test.dart
@@ -16,7 +16,7 @@
 
 import 'protocol_test_utilities.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(NotificationManagerTest);
   });
diff --git a/pkg/analysis_server/test/src/plugin/plugin_locator_test.dart b/pkg/analysis_server/test/src/plugin/plugin_locator_test.dart
index c9f8259..6066b93 100644
--- a/pkg/analysis_server/test/src/plugin/plugin_locator_test.dart
+++ b/pkg/analysis_server/test/src/plugin/plugin_locator_test.dart
@@ -7,7 +7,7 @@
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(PluginLocatorTest);
   });
diff --git a/pkg/analysis_server/test/src/plugin/plugin_manager_test.dart b/pkg/analysis_server/test/src/plugin/plugin_manager_test.dart
index 93f39d8..83f72aa 100644
--- a/pkg/analysis_server/test/src/plugin/plugin_manager_test.dart
+++ b/pkg/analysis_server/test/src/plugin/plugin_manager_test.dart
@@ -22,7 +22,7 @@
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'package:watcher/watcher.dart' as watcher;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(BuiltInPluginInfoTest);
     defineReflectiveTests(DiscoveredPluginInfoTest);
@@ -48,7 +48,7 @@
         InstrumentationService.NULL_SERVICE);
   }
 
-  test_addContextRoot() {
+  void test_addContextRoot() {
     ContextRoot contextRoot1 = _newContextRoot('/pkg1');
     plugin.addContextRoot(contextRoot1);
     expect(plugin.contextRoots, [contextRoot1]);
@@ -56,14 +56,14 @@
     expect(plugin.contextRoots, [contextRoot1]);
   }
 
-  test_creation() {
+  void test_creation() {
     expect(plugin.pluginId, 'test plugin');
     expect(plugin.notificationManager, notificationManager);
     expect(plugin.contextRoots, isEmpty);
     expect(plugin.currentSession, isNull);
   }
 
-  test_removeContextRoot() {
+  void test_removeContextRoot() {
     ContextRoot contextRoot1 = _newContextRoot('/pkg1');
     ContextRoot contextRoot2 = _newContextRoot('/pkg2');
     plugin.addContextRoot(contextRoot1);
@@ -77,11 +77,11 @@
   }
 
   @failingTest
-  test_start_notRunning() {
+  Future<void> test_start_notRunning() {
     fail('Not tested');
   }
 
-  test_start_running() async {
+  Future<void> test_start_running() async {
     plugin.currentSession = PluginSession(plugin);
     try {
       await plugin.start('', '');
@@ -91,11 +91,11 @@
     }
   }
 
-  test_stop_notRunning() {
+  void test_stop_notRunning() {
     expect(() => plugin.stop(), throwsStateError);
   }
 
-  test_stop_running() async {
+  Future<void> test_stop_running() async {
     PluginSession session = PluginSession(plugin);
     TestServerCommunicationChannel channel =
         TestServerCommunicationChannel(session);
@@ -121,7 +121,7 @@
         notificationManager, InstrumentationService.NULL_SERVICE);
   }
 
-  test_addContextRoot() {
+  void test_addContextRoot() {
     String optionsFilePath = '/pkg1/analysis_options.yaml';
     ContextRoot contextRoot1 = _newContextRoot('/pkg1');
     contextRoot1.optionsFilePath = optionsFilePath;
@@ -139,7 +139,7 @@
     expect(roots[0]['optionsFile'], optionsFilePath);
   }
 
-  test_creation() {
+  void test_creation() {
     expect(plugin.path, pluginPath);
     expect(plugin.executionPath, executionPath);
     expect(plugin.notificationManager, notificationManager);
@@ -147,7 +147,7 @@
     expect(plugin.currentSession, isNull);
   }
 
-  test_removeContextRoot() {
+  void test_removeContextRoot() {
     ContextRoot contextRoot1 = _newContextRoot('/pkg1');
     ContextRoot contextRoot2 = _newContextRoot('/pkg2');
     plugin.addContextRoot(contextRoot1);
@@ -161,11 +161,11 @@
   }
 
   @failingTest
-  test_start_notRunning() {
+  Future<void> test_start_notRunning() {
     fail('Not tested');
   }
 
-  test_start_running() async {
+  Future<void> test_start_running() async {
     plugin.currentSession = PluginSession(plugin);
     try {
       await plugin.start('', '');
@@ -175,11 +175,11 @@
     }
   }
 
-  test_stop_notRunning() {
+  void test_stop_notRunning() {
     expect(() => plugin.stop(), throwsStateError);
   }
 
-  test_stop_running() async {
+  Future<void> test_stop_running() async {
     PluginSession session = PluginSession(plugin);
     TestServerCommunicationChannel channel =
         TestServerCommunicationChannel(session);
@@ -206,7 +206,7 @@
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')
-  test_addPluginToContextRoot() async {
+  Future<void> test_addPluginToContextRoot() async {
     io.Directory pkg1Dir = io.Directory.systemTemp.createTempSync('pkg1');
     String pkgPath = pkg1Dir.resolveSymbolicLinksSync();
     await withPlugin(test: (String pluginPath) async {
@@ -218,7 +218,7 @@
   }
 
   @failingTest
-  test_addPluginToContextRoot_pubspec() async {
+  Future<void> test_addPluginToContextRoot_pubspec() async {
     // We can't successfully run pub until after the analyzer_plugin package has
     // been published.
     fail('Cannot run pub');
@@ -240,7 +240,7 @@
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')
-  test_broadcastRequest_many() async {
+  Future<void> test_broadcastRequest_many() async {
     io.Directory pkg1Dir = io.Directory.systemTemp.createTempSync('pkg1');
     String pkgPath = pkg1Dir.resolveSymbolicLinksSync();
     await withPlugin(
@@ -269,7 +269,7 @@
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')
-  test_broadcastRequest_many_noContextRoot() async {
+  Future<void> test_broadcastRequest_many_noContextRoot() async {
     io.Directory pkg1Dir = io.Directory.systemTemp.createTempSync('pkg1');
     String pkgPath = pkg1Dir.resolveSymbolicLinksSync();
     await withPlugin(
@@ -296,7 +296,7 @@
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')
-  test_broadcastRequest_noCurrentSession() async {
+  Future<void> test_broadcastRequest_noCurrentSession() async {
     io.Directory pkg1Dir = io.Directory.systemTemp.createTempSync('pkg1');
     String pkgPath = pkg1Dir.resolveSymbolicLinksSync();
     await withPlugin(
@@ -320,7 +320,7 @@
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')
-  test_broadcastWatchEvent() async {
+  Future<void> test_broadcastWatchEvent() async {
     io.Directory pkg1Dir = io.Directory.systemTemp.createTempSync('pkg1');
     String pkgPath = pkg1Dir.resolveSymbolicLinksSync();
     await withPlugin(
@@ -346,7 +346,7 @@
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')
-  test_pluginsForContextRoot_multiple() async {
+  Future<void> test_pluginsForContextRoot_multiple() async {
     io.Directory pkg1Dir = io.Directory.systemTemp.createTempSync('pkg1');
     String pkgPath = pkg1Dir.resolveSymbolicLinksSync();
     await withPlugin(
@@ -376,7 +376,7 @@
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')
-  test_pluginsForContextRoot_one() async {
+  Future<void> test_pluginsForContextRoot_one() async {
     io.Directory pkg1Dir = io.Directory.systemTemp.createTempSync('pkg1');
     String pkgPath = pkg1Dir.resolveSymbolicLinksSync();
     await withPlugin(test: (String pluginPath) async {
@@ -395,7 +395,7 @@
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')
-  test_removedContextRoot() async {
+  Future<void> test_removedContextRoot() async {
     io.Directory pkg1Dir = io.Directory.systemTemp.createTempSync('pkg1');
     String pkgPath = pkg1Dir.resolveSymbolicLinksSync();
     await withPlugin(test: (String pluginPath) async {
@@ -413,7 +413,7 @@
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')
-  test_restartPlugins() async {
+  Future<void> test_restartPlugins() async {
     io.Directory pkg1Dir = io.Directory.systemTemp.createTempSync('pkg1');
     String pkg1Path = pkg1Dir.resolveSymbolicLinksSync();
     io.Directory pkg2Dir = io.Directory.systemTemp.createTempSync('pkg2');
@@ -565,7 +565,7 @@
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')
-  test_start_notRunning() async {
+  Future<void> test_start_notRunning() async {
     await withPlugin(test: (String pluginPath) async {
       String packagesPath = path.join(pluginPath, '.packages');
       String mainPath = path.join(pluginPath, 'bin', 'plugin.dart');
@@ -629,7 +629,7 @@
     fail('The method handleOnError is not implemented');
   }
 
-  test_handleResponse() async {
+  Future<void> test_handleResponse() async {
     TestServerCommunicationChannel(session);
     Response response = PluginVersionCheckResult(
             true, 'name', 'version', <String>[],
@@ -658,13 +658,13 @@
     expect(channel.sentRequests[0].method, 'plugin.versionCheck');
   }
 
-  test_start_notCompatible() async {
+  Future<void> test_start_notCompatible() async {
     session.isCompatible = false;
     expect(await session.start(path.join(pluginPath, 'byteStore'), sdkPath),
         isFalse);
   }
 
-  test_start_running() async {
+  Future<void> test_start_running() async {
     TestServerCommunicationChannel(session);
     try {
       await session.start(null, '');
@@ -674,11 +674,11 @@
     }
   }
 
-  test_stop_notRunning() {
+  void test_stop_notRunning() {
     expect(() => session.stop(), throwsStateError);
   }
 
-  test_stop_running() async {
+  Future<void> test_stop_running() async {
     TestServerCommunicationChannel channel =
         TestServerCommunicationChannel(session);
     await session.stop();
@@ -923,7 +923,7 @@
   }
 
   @override
-  noSuchMethod(Invocation invocation) {
+  dynamic noSuchMethod(Invocation invocation) {
     fail('Unexpected invocation of ${invocation.memberName}');
   }
 
diff --git a/pkg/analysis_server/test/src/plugin/plugin_watcher_test.dart b/pkg/analysis_server/test/src/plugin/plugin_watcher_test.dart
index c7eb179..8ae4f30 100644
--- a/pkg/analysis_server/test/src/plugin/plugin_watcher_test.dart
+++ b/pkg/analysis_server/test/src/plugin/plugin_watcher_test.dart
@@ -22,7 +22,7 @@
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(PluginWatcherTest);
   });
@@ -38,7 +38,7 @@
     watcher = PluginWatcher(resourceProvider, manager);
   }
 
-  test_addedDriver() async {
+  Future<void> test_addedDriver() async {
     String pkg1Path = newFolder('/pkg1').path;
     newFile('/pkg1/lib/test1.dart');
     newFile('/pkg2/lib/pkg2.dart');
@@ -72,7 +72,7 @@
     expect(manager.addedContextRoots, hasLength(1));
   }
 
-  test_addedDriver_missingPackage() async {
+  Future<void> test_addedDriver_missingPackage() async {
     String pkg1Path = newFolder('/pkg1').path;
     newFile('/pkg1/lib/test1.dart');
 
@@ -96,7 +96,7 @@
     expect(watcher.manager, manager);
   }
 
-  test_removedDriver() {
+  void test_removedDriver() {
     String pkg1Path = newFolder('/pkg1').path;
     ContextRoot contextRoot =
         ContextRoot(pkg1Path, [], pathContext: resourceProvider.pathContext);
@@ -141,7 +141,7 @@
   Stream<ResolvedUnitResult> get results => _resultController.stream;
 
   @override
-  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
 
 class TestPluginManager implements PluginManager {
@@ -157,7 +157,7 @@
   }
 
   @override
-  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 
   @override
   void recordPluginFailure(String hostPackageName, String message) {}
diff --git a/pkg/analysis_server/test/src/plugin/request_converter_test.dart b/pkg/analysis_server/test/src/plugin/request_converter_test.dart
index de83776..954b63b 100644
--- a/pkg/analysis_server/test/src/plugin/request_converter_test.dart
+++ b/pkg/analysis_server/test/src/plugin/request_converter_test.dart
@@ -12,7 +12,7 @@
 
 import 'protocol_test_utilities.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RequestConverterTest);
   });
diff --git a/pkg/analysis_server/test/src/plugin/result_collector_test.dart b/pkg/analysis_server/test/src/plugin/result_collector_test.dart
index f8f25c0..ad8e954 100644
--- a/pkg/analysis_server/test/src/plugin/result_collector_test.dart
+++ b/pkg/analysis_server/test/src/plugin/result_collector_test.dart
@@ -6,7 +6,7 @@
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ResultCollectorTest);
   });
diff --git a/pkg/analysis_server/test/src/plugin/result_converter_test.dart b/pkg/analysis_server/test/src/plugin/result_converter_test.dart
index 99fb20c..b782420 100644
--- a/pkg/analysis_server/test/src/plugin/result_converter_test.dart
+++ b/pkg/analysis_server/test/src/plugin/result_converter_test.dart
@@ -12,7 +12,7 @@
 
 import 'protocol_test_utilities.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ResultConverterTest);
   });
diff --git a/pkg/analysis_server/test/src/plugin/result_merger_test.dart b/pkg/analysis_server/test/src/plugin/result_merger_test.dart
index 46289ea..2bb41bc 100644
--- a/pkg/analysis_server/test/src/plugin/result_merger_test.dart
+++ b/pkg/analysis_server/test/src/plugin/result_merger_test.dart
@@ -9,7 +9,7 @@
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ResultMergerTest);
   });
diff --git a/pkg/analysis_server/test/src/plugin/test_all.dart b/pkg/analysis_server/test/src/plugin/test_all.dart
index 48883d7..9240a5d 100644
--- a/pkg/analysis_server/test/src/plugin/test_all.dart
+++ b/pkg/analysis_server/test/src/plugin/test_all.dart
@@ -13,7 +13,7 @@
 import 'result_converter_test.dart' as result_converter_test;
 import 'result_merger_test.dart' as result_merger_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     notification_manager_test.main();
     plugin_locator_test.main();
diff --git a/pkg/analysis_server/test/src/services/correction/assist/add_diagnostic_property_reference_test.dart b/pkg/analysis_server/test/src/services/correction/assist/add_diagnostic_property_reference_test.dart
index 9a533a0..b763bed 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/add_diagnostic_property_reference_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/add_diagnostic_property_reference_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddDiagnosticPropertyReferenceTest);
   });
@@ -20,7 +20,7 @@
   AssistKind get kind => DartAssistKind.ADD_DIAGNOSTIC_PROPERTY_REFERENCE;
 
   /// Full coverage in fix/add_diagnostic_property_reference_test.dart
-  test_boolField_debugFillProperties() async {
+  Future<void> test_boolField_debugFillProperties() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 class W extends Widget {
diff --git a/pkg/analysis_server/test/src/services/correction/assist/add_not_null_assert.dart b/pkg/analysis_server/test/src/services/correction/assist/add_not_null_assert.dart
index e39942c..bd8122e 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/add_not_null_assert.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/add_not_null_assert.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddNotNullAssert);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.ADD_NOT_NULL_ASSERT;
 
-  test_function_expressionBody_noAssert() async {
+  Future<void> test_function_expressionBody_noAssert() async {
     await resolveTestUnit('''
 int double(int x) => x * 2;
 ''');
@@ -27,7 +27,7 @@
     await assertNoAssistAt('x');
   }
 
-  test_function_noAssert() async {
+  Future<void> test_function_noAssert() async {
     await resolveTestUnit('''
 foo(int x) {
 }
@@ -39,7 +39,7 @@
 ''');
   }
 
-  test_function_withAssert() async {
+  Future<void> test_function_withAssert() async {
     await resolveTestUnit('''
 foo(int x) {
   assert(x != null);
@@ -48,7 +48,7 @@
     await assertNoAssistAt('x');
   }
 
-  test_function_withAssert2() async {
+  Future<void> test_function_withAssert2() async {
     await resolveTestUnit('''
 foo(int x) {
   print('foo');
@@ -58,7 +58,7 @@
     await assertNoAssistAt('x');
   }
 
-  test_method_noAssert() async {
+  Future<void> test_method_noAssert() async {
     await resolveTestUnit('''
 class A {
   foo(int x) {
diff --git a/pkg/analysis_server/test/src/services/correction/assist/add_return_type_test.dart b/pkg/analysis_server/test/src/services/correction/assist/add_return_type_test.dart
index 1024343..7f9bc17 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/add_return_type_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/add_return_type_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddTypeAnnotationTest);
   });
@@ -20,7 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.ADD_RETURN_TYPE;
 
-  test_localFunction_block() async {
+  Future<void> test_localFunction_block() async {
     await resolveTestUnit('''
 class A {
   void m() {
@@ -41,7 +41,7 @@
 ''');
   }
 
-  test_localFunction_expression() async {
+  Future<void> test_localFunction_expression() async {
     await resolveTestUnit('''
 class A {
   void m() {
@@ -58,7 +58,7 @@
 ''');
   }
 
-  test_method_block_noReturn() async {
+  Future<void> test_method_block_noReturn() async {
     await resolveTestUnit('''
 class A {
   /*caret*/m() {
@@ -68,7 +68,7 @@
     await assertNoAssist();
   }
 
-  test_method_block_returnDynamic() async {
+  Future<void> test_method_block_returnDynamic() async {
     await resolveTestUnit('''
 class A {
   /*caret*/m(p) {
@@ -79,7 +79,7 @@
     await assertNoAssist();
   }
 
-  test_method_block_returnNoValue() async {
+  Future<void> test_method_block_returnNoValue() async {
     await resolveTestUnit('''
 class A {
   /*caret*/m() {
@@ -96,7 +96,7 @@
 ''');
   }
 
-  test_method_block_singleReturn() async {
+  Future<void> test_method_block_singleReturn() async {
     await resolveTestUnit('''
 class A {
   /*caret*/m() {
@@ -113,7 +113,7 @@
 ''');
   }
 
-  test_method_expression() async {
+  Future<void> test_method_expression() async {
     await resolveTestUnit('''
 class A {
   /*caret*/m() => '';
@@ -126,7 +126,7 @@
 ''');
   }
 
-  test_topLevelFunction_block() async {
+  Future<void> test_topLevelFunction_block() async {
     await resolveTestUnit('''
 /*caret*/f() {
   return '';
@@ -139,7 +139,7 @@
 ''');
   }
 
-  test_topLevelFunction_expression() async {
+  Future<void> test_topLevelFunction_expression() async {
     await resolveTestUnit('''
 /*caret*/f() => '';
 ''');
@@ -148,7 +148,7 @@
 ''');
   }
 
-  test_topLevelFunction_expression_noAssistWithLint() async {
+  Future<void> test_topLevelFunction_expression_noAssistWithLint() async {
     createAnalysisOptionsFile(lints: [LintNames.always_declare_return_types]);
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
diff --git a/pkg/analysis_server/test/src/services/correction/assist/add_type_annotation_test.dart b/pkg/analysis_server/test/src/services/correction/assist/add_type_annotation_test.dart
index 736d455..78926b0 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/add_type_annotation_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/add_type_annotation_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddTypeAnnotationTest);
   });
@@ -20,18 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.ADD_TYPE_ANNOTATION;
 
-  test_classField_final_noAssistWithLint() async {
-    createAnalysisOptionsFile(lints: [LintNames.always_specify_types]);
-    verifyNoTestUnitErrors = false;
-    await resolveTestUnit('''
-class A {
-  /*caret*/final f = 0;
-}
-''');
-    await assertNoAssist();
-  }
-
-  test_classField_final() async {
+  Future<void> test_classField_final() async {
     await resolveTestUnit('''
 class A {
   final f = 0;
@@ -44,7 +33,18 @@
 ''');
   }
 
-  test_classField_int() async {
+  Future<void> test_classField_final_noAssistWithLint() async {
+    createAnalysisOptionsFile(lints: [LintNames.always_specify_types]);
+    verifyNoTestUnitErrors = false;
+    await resolveTestUnit('''
+class A {
+  /*caret*/final f = 0;
+}
+''');
+    await assertNoAssist();
+  }
+
+  Future<void> test_classField_int() async {
     await resolveTestUnit('''
 class A {
   var f = 0;
@@ -57,7 +57,7 @@
 ''');
   }
 
-  test_declaredIdentifier() async {
+  Future<void> test_declaredIdentifier() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (var item in items) {
@@ -80,7 +80,7 @@
 ''');
   }
 
-  test_declaredIdentifier_addImport_dartUri() async {
+  Future<void> test_declaredIdentifier_addImport_dartUri() async {
     addSource('/home/test/lib/my_lib.dart', r'''
 import 'dart:collection';
 List<HashMap<String, int>> getMap() => null;
@@ -103,7 +103,7 @@
 ''');
   }
 
-  test_declaredIdentifier_final() async {
+  Future<void> test_declaredIdentifier_final() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (final item in items) {
@@ -118,7 +118,7 @@
 ''');
   }
 
-  test_declaredIdentifier_generic() async {
+  Future<void> test_declaredIdentifier_generic() async {
     await resolveTestUnit('''
 class A<T> {
   main(List<List<T>> items) {
@@ -137,7 +137,7 @@
 ''');
   }
 
-  test_declaredIdentifier_hasTypeAnnotation() async {
+  Future<void> test_declaredIdentifier_hasTypeAnnotation() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (String item in items) {
@@ -147,7 +147,7 @@
     await assertNoAssistAt('item in');
   }
 
-  test_declaredIdentifier_inForEachBody() async {
+  Future<void> test_declaredIdentifier_inForEachBody() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (var item in items) {
@@ -158,7 +158,7 @@
     await assertNoAssistAt('42;');
   }
 
-  test_declaredIdentifier_unknownType() async {
+  Future<void> test_declaredIdentifier_unknownType() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 main() {
@@ -169,7 +169,7 @@
     await assertNoAssistAt('item in');
   }
 
-  test_local_addImport_dartUri() async {
+  Future<void> test_local_addImport_dartUri() async {
     addSource('/home/test/lib/my_lib.dart', r'''
 import 'dart:collection';
 HashMap<String, int> getMap() => null;
@@ -190,7 +190,7 @@
 ''');
   }
 
-  test_local_addImport_notLibraryUnit() async {
+  Future<void> test_local_addImport_notLibraryUnit() async {
     addSource('/home/test/lib/my_lib.dart', r'''
 import 'dart:collection';
 HashMap<String, int> getMap() => null;
@@ -232,7 +232,7 @@
     });
   }
 
-  test_local_addImport_relUri() async {
+  Future<void> test_local_addImport_relUri() async {
     testFile = convertPath('/home/test/bin/test.dart');
     addSource('/home/test/bin/aa/bbb/lib_a.dart', r'''
 class MyClass {}
@@ -256,7 +256,7 @@
 ''');
   }
 
-  test_local_bottom() async {
+  Future<void> test_local_bottom() async {
     await resolveTestUnit('''
 main() {
   var v = throw 42;
@@ -265,7 +265,7 @@
     await assertNoAssistAt('var ');
   }
 
-  test_local_Function() async {
+  Future<void> test_local_Function() async {
     await resolveTestUnit('''
 main() {
   var v = () => 1;
@@ -278,7 +278,7 @@
 ''');
   }
 
-  test_local_generic_literal() async {
+  Future<void> test_local_generic_literal() async {
     await resolveTestUnit('''
 class A {
   main(List<int> items) {
@@ -295,7 +295,7 @@
 ''');
   }
 
-  test_local_generic_local() async {
+  Future<void> test_local_generic_local() async {
     await resolveTestUnit('''
 class A<T> {
   main(List<T> items) {
@@ -312,7 +312,7 @@
 ''');
   }
 
-  test_local_hasTypeAnnotation() async {
+  Future<void> test_local_hasTypeAnnotation() async {
     await resolveTestUnit('''
 main() {
   int v = 42;
@@ -321,7 +321,7 @@
     await assertNoAssistAt(' = 42');
   }
 
-  test_local_int() async {
+  Future<void> test_local_int() async {
     await resolveTestUnit('''
 main() {
   var v = 0;
@@ -334,7 +334,7 @@
 ''');
   }
 
-  test_local_List() async {
+  Future<void> test_local_List() async {
     await resolveTestUnit('''
 main() {
   var v = <String>[];
@@ -347,7 +347,7 @@
 ''');
   }
 
-  test_local_localType() async {
+  Future<void> test_local_localType() async {
     await resolveTestUnit('''
 class C {}
 C f() => null;
@@ -364,7 +364,7 @@
 ''');
   }
 
-  test_local_multiple() async {
+  Future<void> test_local_multiple() async {
     await resolveTestUnit('''
 main() {
   var a = 1, b = '';
@@ -373,7 +373,7 @@
     await assertNoAssistAt('var ');
   }
 
-  test_local_noValue() async {
+  Future<void> test_local_noValue() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 main() {
@@ -383,7 +383,7 @@
     await assertNoAssistAt('var ');
   }
 
-  test_local_null() async {
+  Future<void> test_local_null() async {
     await resolveTestUnit('''
 main() {
   var v = null;
@@ -392,7 +392,7 @@
     await assertNoAssistAt('var ');
   }
 
-  test_local_onInitializer() async {
+  Future<void> test_local_onInitializer() async {
     await resolveTestUnit('''
 main() {
   var abc = 0;
@@ -401,7 +401,7 @@
     await assertNoAssistAt('0;');
   }
 
-  test_local_onName() async {
+  Future<void> test_local_onName() async {
     await resolveTestUnit('''
 main() {
   var abc = 0;
@@ -414,7 +414,7 @@
 ''');
   }
 
-  test_local_onVar() async {
+  Future<void> test_local_onVar() async {
     await resolveTestUnit('''
 main() {
   var v = 0;
@@ -427,7 +427,7 @@
 ''');
   }
 
-  test_local_unknown() async {
+  Future<void> test_local_unknown() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 main() {
@@ -437,7 +437,7 @@
     await assertNoAssistAt('var ');
   }
 
-  test_parameter() async {
+  Future<void> test_parameter() async {
     await resolveTestUnit('''
 foo(f(int p)) {}
 main() {
@@ -452,7 +452,7 @@
 ''');
   }
 
-  test_parameter_hasExplicitType() async {
+  Future<void> test_parameter_hasExplicitType() async {
     await resolveTestUnit('''
 foo(f(int p)) {}
 main() {
@@ -462,7 +462,7 @@
     await assertNoAssistAt('test');
   }
 
-  test_parameter_noPropagatedType() async {
+  Future<void> test_parameter_noPropagatedType() async {
     await resolveTestUnit('''
 foo(f(p)) {}
 main() {
@@ -472,7 +472,7 @@
     await assertNoAssistAt('test');
   }
 
-  test_privateType_closureParameter() async {
+  Future<void> test_privateType_closureParameter() async {
     addSource('/home/test/lib/my_lib.dart', '''
 library my_lib;
 class A {}
@@ -488,7 +488,7 @@
     await assertNoAssistAt('test)');
   }
 
-  test_privateType_declaredIdentifier() async {
+  Future<void> test_privateType_declaredIdentifier() async {
     addSource('/home/test/lib/my_lib.dart', '''
 library my_lib;
 class A {}
@@ -507,7 +507,7 @@
     await assertNoAssistAt('var item');
   }
 
-  test_privateType_list() async {
+  Future<void> test_privateType_list() async {
     // This is now failing because we're suggesting "List" rather than nothing.
     // Is it really better to produce nothing?
     addSource('/home/test/lib/my_lib.dart', '''
@@ -530,7 +530,7 @@
 ''');
   }
 
-  test_privateType_sameLibrary() async {
+  Future<void> test_privateType_sameLibrary() async {
     await resolveTestUnit('''
 class _A {}
 _A getValue() => _A();
@@ -547,7 +547,7 @@
 ''');
   }
 
-  test_privateType_variable() async {
+  Future<void> test_privateType_variable() async {
     addSource('/home/test/lib/my_lib.dart', '''
 library my_lib;
 class A {}
@@ -563,7 +563,7 @@
     await assertNoAssistAt('var ');
   }
 
-  test_topLevelField_int() async {
+  Future<void> test_topLevelField_int() async {
     await resolveTestUnit('''
 var V = 0;
 ''');
@@ -572,14 +572,14 @@
 ''');
   }
 
-  test_topLevelField_multiple() async {
+  Future<void> test_topLevelField_multiple() async {
     await resolveTestUnit('''
 var A = 1, V = '';
 ''');
     await assertNoAssistAt('var ');
   }
 
-  test_topLevelField_noValue() async {
+  Future<void> test_topLevelField_noValue() async {
     await resolveTestUnit('''
 var V;
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/assign_to_local_variable_test.dart b/pkg/analysis_server/test/src/services/correction/assist/assign_to_local_variable_test.dart
index 1668ea4..b117de0 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/assign_to_local_variable_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/assign_to_local_variable_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AssignToLocalVariableTest);
   });
@@ -20,7 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.ASSIGN_TO_LOCAL_VARIABLE;
 
-  test_alreadyAssignment() async {
+  Future<void> test_alreadyAssignment() async {
     await resolveTestUnit('''
 main() {
   var vvv;
@@ -30,7 +30,7 @@
     await assertNoAssistAt('vvv =');
   }
 
-  test_inClosure() async {
+  Future<void> test_inClosure() async {
     await resolveTestUnit(r'''
 main() {
   print(() {
@@ -47,7 +47,7 @@
 ''');
   }
 
-  test_invocation() async {
+  Future<void> test_invocation() async {
     await resolveTestUnit('''
 main() {
   List<int> bytes;
@@ -69,7 +69,7 @@
             ['list', 'bytes2', 'readBytes']));
   }
 
-  test_invocationArgument() async {
+  Future<void> test_invocationArgument() async {
     await resolveTestUnit(r'''
 main() {
   f(12345);
@@ -79,7 +79,7 @@
     await assertNoAssistAt('345');
   }
 
-  test_throw() async {
+  Future<void> test_throw() async {
     await resolveTestUnit('''
 main() {
   throw 42;
@@ -88,7 +88,7 @@
     await assertNoAssistAt('throw ');
   }
 
-  test_void() async {
+  Future<void> test_void() async {
     await resolveTestUnit('''
 main() {
   f();
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_class_to_mixin_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_class_to_mixin_test.dart
index d2dd242..14d3271 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_class_to_mixin_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_class_to_mixin_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertClassToMixinTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_CLASS_TO_MIXIN;
 
-  test_abstract() async {
+  Future<void> test_abstract() async {
     await resolveTestUnit('''
 abstract class A {}
 ''');
@@ -28,7 +28,7 @@
 ''');
   }
 
-  test_extends_noSuper() async {
+  Future<void> test_extends_noSuper() async {
     await resolveTestUnit('''
 class A {}
 class B extends A {}
@@ -39,7 +39,7 @@
 ''');
   }
 
-  test_extends_super() async {
+  Future<void> test_extends_super() async {
     await resolveTestUnit('''
 class A {
   a() {}
@@ -62,7 +62,7 @@
 ''');
   }
 
-  test_extends_superSuper() async {
+  Future<void> test_extends_superSuper() async {
     await resolveTestUnit('''
 class A {
   a() {}
@@ -87,7 +87,7 @@
 ''');
   }
 
-  test_extendsImplements_noSuper() async {
+  Future<void> test_extendsImplements_noSuper() async {
     await resolveTestUnit('''
 class A {}
 class B {}
@@ -100,7 +100,7 @@
 ''');
   }
 
-  test_extendsImplements_super_extends() async {
+  Future<void> test_extendsImplements_super_extends() async {
     await resolveTestUnit('''
 class A {
   a() {}
@@ -125,7 +125,7 @@
 ''');
   }
 
-  test_extendsWith_noSuper() async {
+  Future<void> test_extendsWith_noSuper() async {
     await resolveTestUnit('''
 class A {}
 class B {}
@@ -138,7 +138,7 @@
 ''');
   }
 
-  test_extendsWith_super_both() async {
+  Future<void> test_extendsWith_super_both() async {
     await resolveTestUnit('''
 class A {
   a() {}
@@ -169,7 +169,7 @@
 ''');
   }
 
-  test_extendsWith_super_extends() async {
+  Future<void> test_extendsWith_super_extends() async {
     await resolveTestUnit('''
 class A {
   a() {}
@@ -198,7 +198,7 @@
 ''');
   }
 
-  test_extendsWith_super_with() async {
+  Future<void> test_extendsWith_super_with() async {
     await resolveTestUnit('''
 class A {
   a() {}
@@ -227,7 +227,7 @@
 ''');
   }
 
-  test_extendsWithImplements_noSuper() async {
+  Future<void> test_extendsWithImplements_noSuper() async {
     await resolveTestUnit('''
 class A {}
 class B {}
@@ -242,7 +242,7 @@
 ''');
   }
 
-  test_extendsWithImplements_super_both() async {
+  Future<void> test_extendsWithImplements_super_both() async {
     await resolveTestUnit('''
 class A {
   a() {}
@@ -275,7 +275,7 @@
 ''');
   }
 
-  test_extendsWithImplements_super_extends() async {
+  Future<void> test_extendsWithImplements_super_extends() async {
     await resolveTestUnit('''
 class A {
   a() {}
@@ -306,7 +306,7 @@
 ''');
   }
 
-  test_extendsWithImplements_super_with() async {
+  Future<void> test_extendsWithImplements_super_with() async {
     await resolveTestUnit('''
 class A {
   a() {}
@@ -337,7 +337,7 @@
 ''');
   }
 
-  test_implements() async {
+  Future<void> test_implements() async {
     await resolveTestUnit('''
 class A {}
 class B implements A {}
@@ -348,14 +348,14 @@
 ''');
   }
 
-  test_noClauses_invalidSelection() async {
+  Future<void> test_noClauses_invalidSelection() async {
     await resolveTestUnit('''
 class A {}
 ''');
     await assertNoAssistAt('{}');
   }
 
-  test_noClauses_selectKeyword() async {
+  Future<void> test_noClauses_selectKeyword() async {
     await resolveTestUnit('''
 class A {}
 ''');
@@ -364,7 +364,7 @@
 ''');
   }
 
-  test_noClauses_selectName() async {
+  Future<void> test_noClauses_selectName() async {
     await resolveTestUnit('''
 class A {}
 ''');
@@ -373,7 +373,7 @@
 ''');
   }
 
-  test_typeParameters() async {
+  Future<void> test_typeParameters() async {
     await resolveTestUnit('''
 class A<T> {}
 ''');
@@ -382,7 +382,7 @@
 ''');
   }
 
-  test_with_noSuper() async {
+  Future<void> test_with_noSuper() async {
     await resolveTestUnit('''
 class A {}
 class B with A {}
@@ -393,7 +393,7 @@
 ''');
   }
 
-  test_with_super() async {
+  Future<void> test_with_super() async {
     await resolveTestUnit('''
 class A {
   a() {}
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_documentation_into_block_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_documentation_into_block_test.dart
index 895f645..a253255 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_documentation_into_block_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_documentation_into_block_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertDocumentationIntoBlockTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_DOCUMENTATION_INTO_BLOCK;
 
-  test_alreadyBlock() async {
+  Future<void> test_alreadyBlock() async {
     await resolveTestUnit('''
 /**
  * AAAAAAA
@@ -29,7 +29,7 @@
     await assertNoAssistAt('AAA');
   }
 
-  test_noSpaceBeforeText() async {
+  Future<void> test_noSpaceBeforeText() async {
     await resolveTestUnit('''
 class A {
   /// AAAAA
@@ -52,7 +52,7 @@
 ''');
   }
 
-  test_notDocumentation() async {
+  Future<void> test_notDocumentation() async {
     await resolveTestUnit('''
 // AAAA
 class A {}
@@ -60,7 +60,7 @@
     await assertNoAssistAt('AAA');
   }
 
-  test_onReference() async {
+  Future<void> test_onReference() async {
     await resolveTestUnit('''
 /// AAAAAAA [int] AAAAAAA
 class A {}
@@ -73,7 +73,7 @@
 ''');
   }
 
-  test_onText() async {
+  Future<void> test_onText() async {
     await resolveTestUnit('''
 class A {
   /// AAAAAAA [int] AAAAAAA
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_documentation_into_line_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_documentation_into_line_test.dart
index eb40c88..29c820b 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_documentation_into_line_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_documentation_into_line_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertDocumentationIntoLineTest);
   });
@@ -20,7 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_DOCUMENTATION_INTO_LINE;
 
-  test_alreadyLine() async {
+  Future<void> test_alreadyLine() async {
     await resolveTestUnit('''
 /// AAAAAAA
 class A {}
@@ -28,7 +28,7 @@
     await assertNoAssistAt('AAA');
   }
 
-  test_hasEmptyLine() async {
+  Future<void> test_hasEmptyLine() async {
     await resolveTestUnit('''
 class A {
   /**
@@ -49,7 +49,7 @@
 ''');
   }
 
-  test_notDocumentation() async {
+  Future<void> test_notDocumentation() async {
     await resolveTestUnit('''
 /* AAAA */
 class A {}
@@ -57,7 +57,7 @@
     await assertNoAssistAt('AAA');
   }
 
-  test_onReference() async {
+  Future<void> test_onReference() async {
     await resolveTestUnit('''
 /**
  * AAAAAAA [int] AAAAAAA
@@ -70,7 +70,7 @@
 ''');
   }
 
-  test_onText() async {
+  Future<void> test_onText() async {
     await resolveTestUnit('''
 class A {
   /**
@@ -91,23 +91,7 @@
 ''');
   }
 
-  test_onText_noAssistWithLint() async {
-    createAnalysisOptionsFile(lints: [LintNames.slash_for_doc_comments]);
-    verifyNoTestUnitErrors = false;
-    await resolveTestUnit('''
-class A {
-  /**
-   * AAAAAAA [int] AAAAAAA
-   * BBBBBBBB BBBB BBBB
-   * CCC [A] CCCCCCCCCCC
-   */
-  mmm() {}
-}
-''');
-    await assertNoAssist();
-  }
-
-  test_onText_hasFirstLine() async {
+  Future<void> test_onText_hasFirstLine() async {
     await resolveTestUnit('''
 class A {
   /** AAAAAAA [int] AAAAAAA
@@ -127,7 +111,23 @@
 ''');
   }
 
-  test_preserveIndentation() async {
+  Future<void> test_onText_noAssistWithLint() async {
+    createAnalysisOptionsFile(lints: [LintNames.slash_for_doc_comments]);
+    verifyNoTestUnitErrors = false;
+    await resolveTestUnit('''
+class A {
+  /**
+   * AAAAAAA [int] AAAAAAA
+   * BBBBBBBB BBBB BBBB
+   * CCC [A] CCCCCCCCCCC
+   */
+  mmm() {}
+}
+''');
+    await assertNoAssist();
+  }
+
+  Future<void> test_preserveIndentation() async {
     await resolveTestUnit('''
 class A {
   /**
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_into_async_body_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_into_async_body_test.dart
index 5e430f9..117edae 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_into_async_body_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_into_async_body_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertIntoAsyncBodyTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_INTO_ASYNC_BODY;
 
-  test_async() async {
+  Future<void> test_async() async {
     await resolveTestUnit('''
 import 'dart:async';
 Future<String> f() async => '';
@@ -27,7 +27,7 @@
     await assertNoAssistAt('=>');
   }
 
-  test_asyncStar() async {
+  Future<void> test_asyncStar() async {
     await resolveTestUnit('''
 import 'dart:async';
 Stream<String> f() async* {}
@@ -35,7 +35,7 @@
     await assertNoAssistAt('{}');
   }
 
-  test_closure() async {
+  Future<void> test_closure() async {
     await resolveTestUnit('''
 main() {
   f(() => 123);
@@ -50,7 +50,7 @@
 ''');
   }
 
-  test_constructor() async {
+  Future<void> test_constructor() async {
     await resolveTestUnit('''
 class C {
   C() {}
@@ -59,7 +59,7 @@
     await assertNoAssistAt('{}');
   }
 
-  test_function() async {
+  Future<void> test_function() async {
     await resolveTestUnit('''
 String f() => '';
 ''');
@@ -68,7 +68,7 @@
 ''');
   }
 
-  test_getter_expression_noSpace() async {
+  Future<void> test_getter_expression_noSpace() async {
     await resolveTestUnit('''
 class C {
   int get g=>0;
@@ -81,7 +81,7 @@
 ''');
   }
 
-  test_inBody_block() async {
+  Future<void> test_inBody_block() async {
     await resolveTestUnit('''
 class C {
   void foo() {
@@ -92,7 +92,7 @@
     await assertNoAssistAt('print');
   }
 
-  test_inBody_expression() async {
+  Future<void> test_inBody_expression() async {
     await resolveTestUnit('''
 class C {
   void foo() => print(42);
@@ -101,7 +101,7 @@
     await assertNoAssistAt('print');
   }
 
-  test_method() async {
+  Future<void> test_method() async {
     await resolveTestUnit('''
 class C {
   int m() { return 0; }
@@ -114,7 +114,7 @@
 ''');
   }
 
-  test_method_abstract() async {
+  Future<void> test_method_abstract() async {
     await resolveTestUnit('''
 abstract class C {
   int m();
@@ -123,7 +123,7 @@
     await assertNoAssist();
   }
 
-  test_method_noReturnType() async {
+  Future<void> test_method_noReturnType() async {
     await resolveTestUnit('''
 class C {
   m() { return 0; }
@@ -136,7 +136,7 @@
 ''');
   }
 
-  test_syncStar() async {
+  Future<void> test_syncStar() async {
     await resolveTestUnit('''
 Iterable<String> f() sync* {}
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_into_block_body_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_into_block_body_test.dart
index 4d3fa9c..cffee7e 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_into_block_body_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_into_block_body_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertIntoBlockBodyTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_INTO_BLOCK_BODY;
 
-  test_async() async {
+  Future<void> test_async() async {
     await resolveTestUnit('''
 class A {
   mmm() async => 123;
@@ -34,7 +34,7 @@
 ''');
   }
 
-  test_closure() async {
+  Future<void> test_closure() async {
     await resolveTestUnit('''
 setup(x) {}
 main() {
@@ -52,7 +52,7 @@
     assertExitPosition(after: '42;');
   }
 
-  test_closure_voidExpression() async {
+  Future<void> test_closure_voidExpression() async {
     await resolveTestUnit('''
 setup(x) {}
 main() {
@@ -70,7 +70,7 @@
     assertExitPosition(after: "');");
   }
 
-  test_constructor() async {
+  Future<void> test_constructor() async {
     await resolveTestUnit('''
 class A {
   factory A() => null;
@@ -85,14 +85,14 @@
 ''');
   }
 
-  test_inExpression() async {
+  Future<void> test_inExpression() async {
     await resolveTestUnit('''
 main() => 123;
 ''');
     await assertNoAssistAt('123;');
   }
 
-  test_method() async {
+  Future<void> test_method() async {
     await resolveTestUnit('''
 class A {
   mmm() => 123;
@@ -107,14 +107,14 @@
 ''');
   }
 
-  test_noEnclosingFunction() async {
+  Future<void> test_noEnclosingFunction() async {
     await resolveTestUnit('''
 var v = 123;
 ''');
     await assertNoAssistAt('v =');
   }
 
-  test_notExpressionBlock() async {
+  Future<void> test_notExpressionBlock() async {
     await resolveTestUnit('''
 fff() {
   return 123;
@@ -123,7 +123,7 @@
     await assertNoAssistAt('fff() {');
   }
 
-  test_onArrow() async {
+  Future<void> test_onArrow() async {
     await resolveTestUnit('''
 fff() => 123;
 ''');
@@ -134,7 +134,7 @@
 ''');
   }
 
-  test_onName() async {
+  Future<void> test_onName() async {
     await resolveTestUnit('''
 fff() => 123;
 ''');
@@ -145,7 +145,7 @@
 ''');
   }
 
-  test_throw() async {
+  Future<void> test_throw() async {
     await resolveTestUnit('''
 class A {
   mmm() => throw 'error';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_into_expression_body_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_into_expression_body_test.dart
index c5cb328..20b2a68 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_into_expression_body_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_into_expression_body_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertIntoExpressionBodyTest);
   });
@@ -20,14 +20,14 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_INTO_EXPRESSION_BODY;
 
-  test_already() async {
+  Future<void> test_already() async {
     await resolveTestUnit('''
 fff() => 42;
 ''');
     await assertNoAssistAt('fff()');
   }
 
-  test_async() async {
+  Future<void> test_async() async {
     await resolveTestUnit('''
 class A {
   mmm() async {
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_async_noAssistWithLint() async {
+  Future<void> test_async_noAssistWithLint() async {
     createAnalysisOptionsFile(
         lints: [LintNames.prefer_expression_function_bodies]);
     verifyNoTestUnitErrors = false;
@@ -56,7 +56,7 @@
     await assertNoAssist();
   }
 
-  test_closure() async {
+  Future<void> test_closure() async {
     await resolveTestUnit('''
 setup(x) {}
 main() {
@@ -73,7 +73,7 @@
 ''');
   }
 
-  test_closure_voidExpression() async {
+  Future<void> test_closure_voidExpression() async {
     await resolveTestUnit('''
 setup(x) {}
 main() {
@@ -90,7 +90,7 @@
 ''');
   }
 
-  test_constructor() async {
+  Future<void> test_constructor() async {
     await resolveTestUnit('''
 class A {
   factory A() {
@@ -105,7 +105,7 @@
 ''');
   }
 
-  test_function_onBlock() async {
+  Future<void> test_function_onBlock() async {
     await resolveTestUnit('''
 fff() {
   return 42;
@@ -116,7 +116,7 @@
 ''');
   }
 
-  test_function_onName() async {
+  Future<void> test_function_onName() async {
     await resolveTestUnit('''
 fff() {
   return 42;
@@ -127,7 +127,7 @@
 ''');
   }
 
-  test_inExpression() async {
+  Future<void> test_inExpression() async {
     await resolveTestUnit('''
 main() {
   return 42;
@@ -136,7 +136,7 @@
     await assertNoAssistAt('42;');
   }
 
-  test_method_onBlock() async {
+  Future<void> test_method_onBlock() async {
     await resolveTestUnit('''
 class A {
   m() { // marker
@@ -151,7 +151,7 @@
 ''');
   }
 
-  test_moreThanOneStatement() async {
+  Future<void> test_moreThanOneStatement() async {
     await resolveTestUnit('''
 fff() {
   var v = 42;
@@ -161,14 +161,14 @@
     await assertNoAssistAt('fff()');
   }
 
-  test_noEnclosingFunction() async {
+  Future<void> test_noEnclosingFunction() async {
     await resolveTestUnit('''
 var V = 42;
 ''');
     await assertNoAssistAt('V = ');
   }
 
-  test_noReturn() async {
+  Future<void> test_noReturn() async {
     await resolveTestUnit('''
 fff() {
   var v = 42;
@@ -177,7 +177,7 @@
     await assertNoAssistAt('fff()');
   }
 
-  test_noReturnValue() async {
+  Future<void> test_noReturnValue() async {
     await resolveTestUnit('''
 fff() {
   return;
@@ -186,7 +186,7 @@
     await assertNoAssistAt('fff()');
   }
 
-  test_topFunction_onReturnStatement() async {
+  Future<void> test_topFunction_onReturnStatement() async {
     await resolveTestUnit('''
 fff() {
   return 42;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_into_final_field_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_into_final_field_test.dart
index 4fa51fa..b81362d 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_into_final_field_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_into_final_field_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertIntoFinalFieldTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_INTO_FINAL_FIELD;
 
-  test_blockBody_onlyReturnStatement() async {
+  Future<void> test_blockBody_onlyReturnStatement() async {
     await resolveTestUnit('''
 class A {
   int get foo {
@@ -34,7 +34,7 @@
 ''');
   }
 
-  test_hasOverride() async {
+  Future<void> test_hasOverride() async {
     await resolveTestUnit('''
 const myAnnotation = const Object();
 class A {
@@ -51,7 +51,7 @@
 ''');
   }
 
-  test_hasSetter_inSuper() async {
+  Future<void> test_hasSetter_inSuper() async {
     await resolveTestUnit('''
 class A {
   void set foo(_) {}
@@ -70,7 +70,7 @@
 ''');
   }
 
-  test_hasSetter_inThisClass() async {
+  Future<void> test_hasSetter_inThisClass() async {
     await resolveTestUnit('''
 class A {
   int get foo => null;
@@ -80,7 +80,7 @@
     await assertNoAssistAt('get foo');
   }
 
-  test_noReturnType() async {
+  Future<void> test_noReturnType() async {
     await resolveTestUnit('''
 class A {
   get foo => 42;
@@ -93,7 +93,7 @@
 ''');
   }
 
-  test_noReturnType_static() async {
+  Future<void> test_noReturnType_static() async {
     await resolveTestUnit('''
 class A {
   static get foo => 42;
@@ -106,7 +106,7 @@
 ''');
   }
 
-  test_notExpressionBody() async {
+  Future<void> test_notExpressionBody() async {
     await resolveTestUnit('''
 class A {
   int get foo {
@@ -118,7 +118,7 @@
     await assertNoAssistAt('get foo');
   }
 
-  test_notGetter() async {
+  Future<void> test_notGetter() async {
     await resolveTestUnit('''
 class A {
   int foo() => 42;
@@ -127,7 +127,7 @@
     await assertNoAssistAt('foo');
   }
 
-  test_notNull() async {
+  Future<void> test_notNull() async {
     await resolveTestUnit('''
 class A {
   int get foo => 1 + 2;
@@ -140,7 +140,7 @@
 ''');
   }
 
-  test_null() async {
+  Future<void> test_null() async {
     await resolveTestUnit('''
 class A {
   int get foo => null;
@@ -153,7 +153,7 @@
 ''');
   }
 
-  test_onName() async {
+  Future<void> test_onName() async {
     await resolveTestUnit('''
 class A {
   int get foo => 42;
@@ -166,7 +166,7 @@
 ''');
   }
 
-  test_onReturnType_parameterized() async {
+  Future<void> test_onReturnType_parameterized() async {
     await resolveTestUnit('''
 class A {
   List<int> get foo => null;
@@ -179,7 +179,7 @@
 ''');
   }
 
-  test_onReturnType_simple() async {
+  Future<void> test_onReturnType_simple() async {
     await resolveTestUnit('''
 class A {
   int get foo => 42;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_into_for_index_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_into_for_index_test.dart
index 5816d3a..dc0a9e3 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_into_for_index_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_into_for_index_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertIntoForIndexTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_INTO_FOR_INDEX;
 
-  test_bodyNotBlock() async {
+  Future<void> test_bodyNotBlock() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (String item in items) print(item);
@@ -28,7 +28,7 @@
     await assertNoAssistAt('for (String');
   }
 
-  test_doesNotDeclareVariable() async {
+  Future<void> test_doesNotDeclareVariable() async {
     await resolveTestUnit('''
 main(List<String> items) {
   String item;
@@ -40,7 +40,7 @@
     await assertNoAssistAt('for (item');
   }
 
-  test_iterableIsNotVariable() async {
+  Future<void> test_iterableIsNotVariable() async {
     await resolveTestUnit('''
 main() {
   for (String item in ['a', 'b', 'c']) {
@@ -51,7 +51,7 @@
     await assertNoAssistAt('for (String');
   }
 
-  test_iterableNotList() async {
+  Future<void> test_iterableNotList() async {
     await resolveTestUnit('''
 main(Iterable<String> items) {
   for (String item in items) {
@@ -62,7 +62,7 @@
     await assertNoAssistAt('for (String');
   }
 
-  test_onDeclaredIdentifier_name() async {
+  Future<void> test_onDeclaredIdentifier_name() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (String item in items) {
@@ -80,7 +80,7 @@
 ''');
   }
 
-  test_onDeclaredIdentifier_type() async {
+  Future<void> test_onDeclaredIdentifier_type() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (String item in items) {
@@ -98,7 +98,7 @@
 ''');
   }
 
-  test_onFor() async {
+  Future<void> test_onFor() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (String item in items) {
@@ -116,7 +116,7 @@
 ''');
   }
 
-  test_usesI() async {
+  Future<void> test_usesI() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (String item in items) {
@@ -134,7 +134,7 @@
 ''');
   }
 
-  test_usesIJ() async {
+  Future<void> test_usesIJ() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (String item in items) {
@@ -154,7 +154,7 @@
 ''');
   }
 
-  test_usesIJK() async {
+  Future<void> test_usesIJK() async {
     await resolveTestUnit('''
 main(List<String> items) {
   for (String item in items) {
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_into_generic_function_syntax_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_into_generic_function_syntax_test.dart
index e9b034e..8ae79a7 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_into_generic_function_syntax_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_into_generic_function_syntax_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertIntoGenericFunctionSyntaxTest);
   });
@@ -19,21 +19,21 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_INTO_GENERIC_FUNCTION_SYNTAX;
 
-  test_functionTypeAlias_insideParameterList() async {
+  Future<void> test_functionTypeAlias_insideParameterList() async {
     await resolveTestUnit('''
 typedef String F(int x, int y);
 ''');
     await assertNoAssistAt('x,');
   }
 
-  test_functionTypeAlias_noParameterTypes() async {
+  Future<void> test_functionTypeAlias_noParameterTypes() async {
     await resolveTestUnit('''
 typedef String F(x);
 ''');
     await assertNoAssistAt('def');
   }
 
-  test_functionTypeAlias_noReturnType_noTypeParameters() async {
+  Future<void> test_functionTypeAlias_noReturnType_noTypeParameters() async {
     await resolveTestUnit('''
 typedef String F(int x);
 ''');
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_functionTypeAlias_noReturnType_typeParameters() async {
+  Future<void> test_functionTypeAlias_noReturnType_typeParameters() async {
     await resolveTestUnit('''
 typedef F<P, R>(P x);
 ''');
@@ -51,7 +51,7 @@
 ''');
   }
 
-  test_functionTypeAlias_returnType_noTypeParameters() async {
+  Future<void> test_functionTypeAlias_returnType_noTypeParameters() async {
     await resolveTestUnit('''
 typedef String F(int x);
 ''');
@@ -60,7 +60,7 @@
 ''');
   }
 
-  test_functionTypeAlias_returnType_typeParameters() async {
+  Future<void> test_functionTypeAlias_returnType_typeParameters() async {
     await resolveTestUnit('''
 typedef R F<P, R>(P x);
 ''');
@@ -69,21 +69,22 @@
 ''');
   }
 
-  test_functionTypedParameter_insideParameterList() async {
+  Future<void> test_functionTypedParameter_insideParameterList() async {
     await resolveTestUnit('''
 g(String f(int x, int y)) {}
 ''');
     await assertNoAssistAt('x,');
   }
 
-  test_functionTypedParameter_noParameterTypes() async {
+  Future<void> test_functionTypedParameter_noParameterTypes() async {
     await resolveTestUnit('''
 g(String f(x)) {}
 ''');
     await assertNoAssistAt('f(');
   }
 
-  test_functionTypedParameter_noReturnType_noTypeParameters() async {
+  Future<void>
+      test_functionTypedParameter_noReturnType_noTypeParameters() async {
     await resolveTestUnit('''
 g(f(int x)) {}
 ''');
@@ -92,7 +93,7 @@
 ''');
   }
 
-  test_functionTypedParameter_returnType() async {
+  Future<void> test_functionTypedParameter_returnType() async {
     await resolveTestUnit('''
 g(String f(int x)) {}
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_into_getter_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_into_getter_test.dart
index f3348c2..48f5200 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_into_getter_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_into_getter_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertIntoGetterTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_INTO_GETTER;
 
-  test_noInitializer() async {
+  Future<void> test_noInitializer() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 class A {
@@ -29,7 +29,7 @@
     await assertNoAssistAt('foo');
   }
 
-  test_notFinal() async {
+  Future<void> test_notFinal() async {
     await resolveTestUnit('''
 class A {
   int foo = 1;
@@ -38,7 +38,7 @@
     await assertNoAssistAt('foo');
   }
 
-  test_notSingleField() async {
+  Future<void> test_notSingleField() async {
     await resolveTestUnit('''
 class A {
   final int foo = 1, bar = 2;
@@ -47,7 +47,7 @@
     await assertNoAssistAt('foo');
   }
 
-  test_noType() async {
+  Future<void> test_noType() async {
     await resolveTestUnit('''
 class A {
   final foo = 42;
@@ -60,7 +60,7 @@
 ''');
   }
 
-  test_type() async {
+  Future<void> test_type() async {
     await resolveTestUnit('''
 const myAnnotation = const Object();
 class A {
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_into_is_not_empty_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_into_is_not_empty_test.dart
index cd522a7..18b1e53 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_into_is_not_empty_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_into_is_not_empty_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertIntoIsNotEmptyTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_INTO_IS_NOT_EMPTY;
 
-  test_noBang() async {
+  Future<void> test_noBang() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 main(String str) {
@@ -29,7 +29,7 @@
     await assertNoAssistAt('isEmpty;');
   }
 
-  test_noIsNotEmpty() async {
+  Future<void> test_noIsNotEmpty() async {
     await resolveTestUnit('''
 class A {
   bool get isEmpty => false;
@@ -41,7 +41,7 @@
     await assertNoAssistAt('isEmpty;');
   }
 
-  test_notInPrefixExpression() async {
+  Future<void> test_notInPrefixExpression() async {
     await resolveTestUnit('''
 main(String str) {
   str.isEmpty;
@@ -50,7 +50,7 @@
     await assertNoAssistAt('isEmpty;');
   }
 
-  test_notIsEmpty() async {
+  Future<void> test_notIsEmpty() async {
     await resolveTestUnit('''
 main(int p) {
   !p.isEven;
@@ -59,7 +59,7 @@
     await assertNoAssistAt('isEven;');
   }
 
-  test_on_isEmpty() async {
+  Future<void> test_on_isEmpty() async {
     await resolveTestUnit('''
 main(String str) {
   !str.isEmpty;
@@ -72,7 +72,7 @@
 ''');
   }
 
-  test_on_str() async {
+  Future<void> test_on_str() async {
     await resolveTestUnit('''
 main(String str) {
   !str.isEmpty;
@@ -85,7 +85,7 @@
 ''');
   }
 
-  test_propertyAccess() async {
+  Future<void> test_propertyAccess() async {
     await resolveTestUnit('''
 main(String str) {
   !'text'.isEmpty;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_into_is_not_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_into_is_not_test.dart
index f7e1ae1..a729944 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_into_is_not_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_into_is_not_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertIntoIsNotTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_INTO_IS_NOT;
 
-  test_childOfIs_left() async {
+  Future<void> test_childOfIs_left() async {
     await resolveTestUnit('''
 main(p) {
   !(p is String);
@@ -32,7 +32,7 @@
 ''');
   }
 
-  test_childOfIs_right() async {
+  Future<void> test_childOfIs_right() async {
     await resolveTestUnit('''
 main(p) {
   !(p is String);
@@ -45,7 +45,7 @@
 ''');
   }
 
-  test_is() async {
+  Future<void> test_is() async {
     await resolveTestUnit('''
 main(p) {
   !(p is String);
@@ -58,7 +58,7 @@
 ''');
   }
 
-  test_is_alreadyIsNot() async {
+  Future<void> test_is_alreadyIsNot() async {
     await resolveTestUnit('''
 main(p) {
   p is! String;
@@ -67,7 +67,7 @@
     await assertNoAssistAt('is!');
   }
 
-  test_is_higherPrecedencePrefix() async {
+  Future<void> test_is_higherPrecedencePrefix() async {
     await resolveTestUnit('''
 main(p) {
   !!(p is String);
@@ -80,7 +80,7 @@
 ''');
   }
 
-  test_is_noEnclosingParenthesis() async {
+  Future<void> test_is_noEnclosingParenthesis() async {
     await resolveTestUnit('''
 main(p) {
   p is String;
@@ -89,7 +89,7 @@
     await assertNoAssistAt('is String');
   }
 
-  test_is_noPrefix() async {
+  Future<void> test_is_noPrefix() async {
     await resolveTestUnit('''
 main(p) {
   (p is String);
@@ -98,7 +98,7 @@
     await assertNoAssistAt('is String');
   }
 
-  test_is_not_higherPrecedencePrefix() async {
+  Future<void> test_is_not_higherPrecedencePrefix() async {
     await resolveTestUnit('''
 main(p) {
   !!(p is String);
@@ -111,7 +111,7 @@
 ''');
   }
 
-  test_is_notIsExpression() async {
+  Future<void> test_is_notIsExpression() async {
     await resolveTestUnit('''
 main(p) {
   123 + 456;
@@ -120,7 +120,7 @@
     await assertNoAssistAt('123 +');
   }
 
-  test_is_notTheNotOperator() async {
+  Future<void> test_is_notTheNotOperator() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 main(p) {
@@ -130,7 +130,7 @@
     await assertNoAssistAt('is String');
   }
 
-  test_not() async {
+  Future<void> test_not() async {
     await resolveTestUnit('''
 main(p) {
   !(p is String);
@@ -143,7 +143,7 @@
 ''');
   }
 
-  test_not_alreadyIsNot() async {
+  Future<void> test_not_alreadyIsNot() async {
     await resolveTestUnit('''
 main(p) {
   !(p is! String);
@@ -152,7 +152,7 @@
     await assertNoAssistAt('!(p');
   }
 
-  test_not_noEnclosingParenthesis() async {
+  Future<void> test_not_noEnclosingParenthesis() async {
     await resolveTestUnit('''
 main(p) {
   !p;
@@ -161,7 +161,7 @@
     await assertNoAssistAt('!p');
   }
 
-  test_not_notIsExpression() async {
+  Future<void> test_not_notIsExpression() async {
     await resolveTestUnit('''
 main(p) {
   !(p == null);
@@ -170,7 +170,7 @@
     await assertNoAssistAt('!(p');
   }
 
-  test_not_notTheNotOperator() async {
+  Future<void> test_not_notTheNotOperator() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 main(p) {
@@ -180,7 +180,7 @@
     await assertNoAssistAt('++(');
   }
 
-  test_parentheses() async {
+  Future<void> test_parentheses() async {
     await resolveTestUnit('''
 main(p) {
   !(p is String);
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_part_of_to_uri_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_part_of_to_uri_test.dart
index 0dc747a..b09a195 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_part_of_to_uri_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_part_of_to_uri_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertPartOfToUriTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_PART_OF_TO_URI;
 
-  test_nonSibling() async {
+  Future<void> test_nonSibling() async {
     addSource('/home/test/lib/foo.dart', '''
 library foo;
 part 'src/bar.dart';
@@ -33,7 +33,7 @@
 ''');
   }
 
-  test_sibling() async {
+  Future<void> test_sibling() async {
     addSource('/home/test/lib/foo.dart', '''
 library foo;
 part 'bar.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_double_quoted_string_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_double_quoted_string_test.dart
index 5711b07..f031a25 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_double_quoted_string_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_double_quoted_string_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToDoubleQuotedStringTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_DOUBLE_QUOTED_STRING;
 
-  test_one_embeddedTarget() async {
+  Future<void> test_one_embeddedTarget() async {
     await resolveTestUnit('''
 main() {
   print('a"b"c');
@@ -28,7 +28,7 @@
     await assertNoAssistAt("'a");
   }
 
-  test_one_enclosingTarget() async {
+  Future<void> test_one_enclosingTarget() async {
     await resolveTestUnit('''
 main() {
   print("abc");
@@ -37,7 +37,7 @@
     await assertNoAssistAt('"ab');
   }
 
-  test_one_interpolation() async {
+  Future<void> test_one_interpolation() async {
     await resolveTestUnit(r'''
 main() {
   var b = 'b';
@@ -54,7 +54,7 @@
 ''');
   }
 
-  test_one_raw() async {
+  Future<void> test_one_raw() async {
     await resolveTestUnit('''
 main() {
   print(r'abc');
@@ -67,7 +67,7 @@
 ''');
   }
 
-  test_one_simple() async {
+  Future<void> test_one_simple() async {
     await resolveTestUnit('''
 main() {
   print('abc');
@@ -80,7 +80,7 @@
 ''');
   }
 
-  test_three_embeddedTarget() async {
+  Future<void> test_three_embeddedTarget() async {
     await resolveTestUnit("""
 main() {
   print('''a""\"c''');
@@ -89,7 +89,7 @@
     await assertNoAssistAt("'a");
   }
 
-  test_three_enclosingTarget() async {
+  Future<void> test_three_enclosingTarget() async {
     await resolveTestUnit('''
 main() {
   print("""abc""");
@@ -98,7 +98,7 @@
     await assertNoAssistAt('"ab');
   }
 
-  test_three_interpolation() async {
+  Future<void> test_three_interpolation() async {
     await resolveTestUnit(r"""
 main() {
   var b = 'b';
@@ -115,7 +115,7 @@
 ''');
   }
 
-  test_three_raw() async {
+  Future<void> test_three_raw() async {
     await resolveTestUnit("""
 main() {
   print(r'''abc''');
@@ -128,7 +128,7 @@
 ''');
   }
 
-  test_three_simple() async {
+  Future<void> test_three_simple() async {
     await resolveTestUnit("""
 main() {
   print('''abc''');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_field_parameter_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_field_parameter_test.dart
index 2cf9958..8ff735a 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_field_parameter_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_field_parameter_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToFieldParameterTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_FIELD_PARAMETER;
 
-  test_additionalUse() async {
+  Future<void> test_additionalUse() async {
     await resolveTestUnit('''
 class A {
   int aaa2;
@@ -30,7 +30,7 @@
     await assertNoAssistAt('aaa)');
   }
 
-  test_firstInitializer() async {
+  Future<void> test_firstInitializer() async {
     await resolveTestUnit('''
 class A {
   int aaa2;
@@ -47,7 +47,7 @@
 ''');
   }
 
-  test_notPureAssignment() async {
+  Future<void> test_notPureAssignment() async {
     await resolveTestUnit('''
 class A {
   int aaa2;
@@ -57,7 +57,7 @@
     await assertNoAssistAt('aaa)');
   }
 
-  test_onParameterName_inInitializer() async {
+  Future<void> test_onParameterName_inInitializer() async {
     await resolveTestUnit('''
 class A {
   int test2;
@@ -74,7 +74,7 @@
 ''');
   }
 
-  test_onParameterName_inParameters() async {
+  Future<void> test_onParameterName_inParameters() async {
     await resolveTestUnit('''
 class A {
   int test;
@@ -91,7 +91,7 @@
 ''');
   }
 
-  test_secondInitializer() async {
+  Future<void> test_secondInitializer() async {
     await resolveTestUnit('''
 class A {
   int aaa2;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_for_element_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_for_element_test.dart
index 001ae73..3dfe23e 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_for_element_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_for_element_test.dart
@@ -10,7 +10,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToIfElementTest);
   });
@@ -28,7 +28,7 @@
     super.setUp();
   }
 
-  test_mapFromIterable_complexKey() async {
+  Future<void> test_mapFromIterable_complexKey() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   return Map.fromIt/*caret*/erable(i, key: (e) {
@@ -40,7 +40,7 @@
     await assertNoAssist();
   }
 
-  test_mapFromIterable_complexValue() async {
+  Future<void> test_mapFromIterable_complexValue() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   return Map.fromIt/*caret*/erable(i, key: (e) => e * 2, value: (e) {
@@ -52,7 +52,8 @@
     await assertNoAssist();
   }
 
-  test_mapFromIterable_differentParameterNames_usedInKey_conflictInValue() async {
+  Future<void>
+      test_mapFromIterable_differentParameterNames_usedInKey_conflictInValue() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   var k = 3;
@@ -67,7 +68,8 @@
 ''');
   }
 
-  test_mapFromIterable_differentParameterNames_usedInKey_conflictInValue_noAssistWithLint() async {
+  Future<void>
+      test_mapFromIterable_differentParameterNames_usedInKey_conflictInValue_noAssistWithLint() async {
     createAnalysisOptionsFile(
         lints: [LintNames.prefer_for_elements_to_map_fromIterable]);
     verifyNoTestUnitErrors = false;
@@ -80,7 +82,8 @@
     await assertNoAssist();
   }
 
-  test_mapFromIterable_differentParameterNames_usedInKey_noConflictInValue() async {
+  Future<void>
+      test_mapFromIterable_differentParameterNames_usedInKey_noConflictInValue() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   return Map.fromIt/*caret*/erable(i, key: (k) => k * 2, value: (v) => 0);
@@ -93,7 +96,8 @@
 ''');
   }
 
-  test_mapFromIterable_differentParameterNames_usedInKeyAndValue_conflictWithDefault() async {
+  Future<void>
+      test_mapFromIterable_differentParameterNames_usedInKeyAndValue_conflictWithDefault() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   var e = 2;
@@ -108,7 +112,8 @@
 ''');
   }
 
-  test_mapFromIterable_differentParameterNames_usedInKeyAndValue_noConflictWithDefault() async {
+  Future<void>
+      test_mapFromIterable_differentParameterNames_usedInKeyAndValue_noConflictWithDefault() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   return Map.fromIt/*caret*/erable(i, key: (k) => k * 2, value: (v) => v + 3);
@@ -121,7 +126,8 @@
 ''');
   }
 
-  test_mapFromIterable_differentParameterNames_usedInValue_conflictInKey() async {
+  Future<void>
+      test_mapFromIterable_differentParameterNames_usedInValue_conflictInKey() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   int v = 0;
@@ -136,7 +142,8 @@
 ''');
   }
 
-  test_mapFromIterable_differentParameterNames_usedInValue_noConflictInKey() async {
+  Future<void>
+      test_mapFromIterable_differentParameterNames_usedInValue_noConflictInKey() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   int index = 0;
@@ -151,7 +158,7 @@
 ''');
   }
 
-  test_mapFromIterable_missingKey() async {
+  Future<void> test_mapFromIterable_missingKey() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   return Map.fromIt/*caret*/erable(i, value: (e) => e + 3);
@@ -160,7 +167,7 @@
     await assertNoAssist();
   }
 
-  test_mapFromIterable_missingKeyAndValue() async {
+  Future<void> test_mapFromIterable_missingKeyAndValue() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   return Map.fromIt/*caret*/erable(i);
@@ -169,7 +176,7 @@
     await assertNoAssist();
   }
 
-  test_mapFromIterable_missingValue() async {
+  Future<void> test_mapFromIterable_missingValue() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   return Map.fromIt/*caret*/erable(i, key: (e) => e * 2);
@@ -178,7 +185,7 @@
     await assertNoAssist();
   }
 
-  test_mapFromIterable_notMapFromIterable() async {
+  Future<void> test_mapFromIterable_notMapFromIterable() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   return A.fromIt/*caret*/erable(i, key: (e) => e * 2, value: (e) => e + 3);
@@ -190,7 +197,7 @@
     await assertNoAssist();
   }
 
-  test_mapFromIterable_sameParameterNames() async {
+  Future<void> test_mapFromIterable_sameParameterNames() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   return Map.fromIt/*caret*/erable(i, key: (e) => e * 2, value: (e) => e + 3);
@@ -203,7 +210,7 @@
 ''');
   }
 
-  test_undefinedConstructor() async {
+  Future<void> test_undefinedConstructor() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 f() {
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_if_element_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_if_element_test.dart
index 1a72f27..be17326 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_if_element_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_if_element_test.dart
@@ -10,7 +10,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToIfElementTest);
   });
@@ -28,7 +28,7 @@
     super.setUp();
   }
 
-  test_conditional_list() async {
+  Future<void> test_conditional_list() async {
     await resolveTestUnit('''
 f(bool b) {
   return ['a', b /*caret*/? 'c' : 'd', 'e'];
@@ -41,7 +41,7 @@
 ''');
   }
 
-  test_conditional_list_caret_at_start_of_expression() async {
+  Future<void> test_conditional_list_caret_at_start_of_expression() async {
     await resolveTestUnit('''
 f(bool b) {
   return ['a', /*caret*/b ? 'c' : 'd', 'e'];
@@ -54,7 +54,7 @@
 ''');
   }
 
-  test_conditional_list_noAssistWithLint() async {
+  Future<void> test_conditional_list_noAssistWithLint() async {
     createAnalysisOptionsFile(
         lints: [LintNames.prefer_if_elements_to_conditional_expressions]);
     verifyNoTestUnitErrors = false;
@@ -66,7 +66,7 @@
     await assertNoAssist();
   }
 
-  test_conditional_list_withParentheses() async {
+  Future<void> test_conditional_list_withParentheses() async {
     await resolveTestUnit('''
 f(bool b) {
   return ['a', (b /*caret*/? 'c' : 'd'), 'e'];
@@ -79,7 +79,7 @@
 ''');
   }
 
-  test_conditional_map() async {
+  Future<void> test_conditional_map() async {
     await resolveTestUnit('''
 f(bool b) {
   return {'a' : 1, b /*caret*/? 'c' : 'd' : 2, 'e' : 3};
@@ -88,7 +88,7 @@
     await assertNoAssist();
   }
 
-  test_conditional_notConditional() async {
+  Future<void> test_conditional_notConditional() async {
     await resolveTestUnit('''
 f(bool b) {
   return {'/*caret*/a', b ? 'c' : 'd', 'e'};
@@ -97,7 +97,7 @@
     await assertNoAssist();
   }
 
-  test_conditional_notInLiteral() async {
+  Future<void> test_conditional_notInLiteral() async {
     await resolveTestUnit('''
 f(bool b) {
   return b /*caret*/? 'c' : 'd';
@@ -106,7 +106,7 @@
     await assertNoAssist();
   }
 
-  test_conditional_set() async {
+  Future<void> test_conditional_set() async {
     await resolveTestUnit('''
 f(bool b) {
   return {'a', b /*caret*/? 'c' : 'd', 'e'};
@@ -119,7 +119,7 @@
 ''');
   }
 
-  test_conditional_set_withParentheses() async {
+  Future<void> test_conditional_set_withParentheses() async {
     await resolveTestUnit('''
 f(bool b) {
   return {'a', ((b /*caret*/? 'c' : 'd')), 'e'};
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_int_literal_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_int_literal_test.dart
index b1137ac..ae6bb6c 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_int_literal_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_int_literal_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToIntLiteralTest);
   });
@@ -20,7 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_INT_LITERAL;
 
-  test_decimal() async {
+  Future<void> test_decimal() async {
     await resolveTestUnit('''
 const double myDouble = /*caret*/42.0;
 ''');
@@ -29,7 +29,7 @@
 ''');
   }
 
-  test_decimal_noAssistWithLint() async {
+  Future<void> test_decimal_noAssistWithLint() async {
     createAnalysisOptionsFile(lints: [LintNames.prefer_int_literals]);
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
@@ -38,14 +38,14 @@
     await assertNoAssist();
   }
 
-  test_notDouble() async {
+  Future<void> test_notDouble() async {
     await resolveTestUnit('''
 const double myDouble = /*caret*/42;
 ''');
     await assertNoAssist();
   }
 
-  test_scientific() async {
+  Future<void> test_scientific() async {
     await resolveTestUnit('''
 const double myDouble = /*caret*/4.2e1;
 ''');
@@ -54,7 +54,7 @@
 ''');
   }
 
-  test_tooBig() async {
+  Future<void> test_tooBig() async {
     await resolveTestUnit('''
 const double myDouble = /*caret*/4.2e99999;
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_list_literal_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_list_literal_test.dart
index a9b106e..71a49aa 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_list_literal_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_list_literal_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToListLiteralTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_LIST_LITERAL;
 
-  test_default_declaredType() async {
+  Future<void> test_default_declaredType() async {
     await resolveTestUnit('''
 List l = Li/*caret*/st();
 ''');
@@ -28,7 +28,7 @@
 ''');
   }
 
-  test_default_minimal() async {
+  Future<void> test_default_minimal() async {
     await resolveTestUnit('''
 var l = Li/*caret*/st();
 ''');
@@ -37,7 +37,7 @@
 ''');
   }
 
-  test_default_newKeyword() async {
+  Future<void> test_default_newKeyword() async {
     await resolveTestUnit('''
 var l = new Li/*caret*/st();
 ''');
@@ -46,14 +46,14 @@
 ''');
   }
 
-  test_default_tooManyArguments() async {
+  Future<void> test_default_tooManyArguments() async {
     await resolveTestUnit('''
 var l = Li/*caret*/st(5);
 ''');
     await assertNoAssist();
   }
 
-  test_default_typeArg() async {
+  Future<void> test_default_typeArg() async {
     await resolveTestUnit('''
 var l = Li/*caret*/st<int>();
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_map_literal_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_map_literal_test.dart
index 150b545..22549b0 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_map_literal_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_map_literal_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToMapLiteralTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_MAP_LITERAL;
 
-  test_default_declaredType() async {
+  Future<void> test_default_declaredType() async {
     await resolveTestUnit('''
 Map m = Ma/*caret*/p();
 ''');
@@ -28,7 +28,7 @@
 ''');
   }
 
-  test_default_linkedHashMap() async {
+  Future<void> test_default_linkedHashMap() async {
     await resolveTestUnit('''
 import 'dart:collection';
 var m = LinkedHashMa/*caret*/p();
@@ -39,7 +39,7 @@
 ''');
   }
 
-  test_default_minimal() async {
+  Future<void> test_default_minimal() async {
     await resolveTestUnit('''
 var m = Ma/*caret*/p();
 ''');
@@ -48,7 +48,7 @@
 ''');
   }
 
-  test_default_newKeyword() async {
+  Future<void> test_default_newKeyword() async {
     await resolveTestUnit('''
 var m = new Ma/*caret*/p();
 ''');
@@ -57,7 +57,7 @@
 ''');
   }
 
-  test_default_typeArg() async {
+  Future<void> test_default_typeArg() async {
     await resolveTestUnit('''
 var m = Ma/*caret*/p<String, int>();
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_multiline_string_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_multiline_string_test.dart
index 1410b85..66fd199 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_multiline_string_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_multiline_string_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToMultilineStringTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_MULTILINE_STRING;
 
-  test_doubleQuoted() async {
+  Future<void> test_doubleQuoted() async {
     await resolveTestUnit('''
 main() {
   print("abc");
@@ -33,7 +33,7 @@
 ''');
   }
 
-  test_doubleQuoted_alreadyMultiline() async {
+  Future<void> test_doubleQuoted_alreadyMultiline() async {
     await resolveTestUnit('''
 main() {
   print("""abc""");
@@ -42,7 +42,7 @@
     await assertNoAssistAt('abc');
   }
 
-  test_doubleQuoted_interpolation_expressionElement() async {
+  Future<void> test_doubleQuoted_interpolation_expressionElement() async {
     await resolveTestUnit(r"""
 main() {
   var b = 'b';
@@ -53,7 +53,7 @@
     await assertNoAssistAt(r'c}');
   }
 
-  test_doubleQuoted_interpolation_stringElement_begin() async {
+  Future<void> test_doubleQuoted_interpolation_stringElement_begin() async {
     await resolveTestUnit(r"""
 main() {
   var b = 'b';
@@ -71,7 +71,7 @@
 ''');
   }
 
-  test_doubleQuoted_interpolation_stringElement_middle() async {
+  Future<void> test_doubleQuoted_interpolation_stringElement_middle() async {
     await resolveTestUnit(r"""
 main() {
   var b = 'b';
@@ -89,7 +89,7 @@
 ''');
   }
 
-  test_doubleQuoted_raw() async {
+  Future<void> test_doubleQuoted_raw() async {
     await resolveTestUnit('''
 main() {
   print(r"abc");
@@ -103,7 +103,7 @@
 ''');
   }
 
-  test_singleQuoted() async {
+  Future<void> test_singleQuoted() async {
     await resolveTestUnit('''
 main() {
   print('abc');
@@ -117,7 +117,7 @@
 """);
   }
 
-  test_singleQuoted_interpolation_expressionElement() async {
+  Future<void> test_singleQuoted_interpolation_expressionElement() async {
     await resolveTestUnit(r"""
 main() {
   var b = 'b';
@@ -128,7 +128,7 @@
     await assertNoAssistAt(r'c}');
   }
 
-  test_singleQuoted_interpolation_stringElement_begin() async {
+  Future<void> test_singleQuoted_interpolation_stringElement_begin() async {
     await resolveTestUnit(r"""
 main() {
   var b = 'b';
@@ -146,7 +146,7 @@
 """);
   }
 
-  test_singleQuoted_interpolation_stringElement_middle() async {
+  Future<void> test_singleQuoted_interpolation_stringElement_middle() async {
     await resolveTestUnit(r"""
 main() {
   var b = 'b';
@@ -164,7 +164,7 @@
 """);
   }
 
-  test_singleQuoted_raw() async {
+  Future<void> test_singleQuoted_raw() async {
     await resolveTestUnit('''
 main() {
   print(r'abc');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_normal_parameter_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_normal_parameter_test.dart
index f5ddc23..cdbf63e 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_normal_parameter_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_normal_parameter_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToNormalParameterTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_NORMAL_PARAMETER;
 
-  test_dynamic() async {
+  Future<void> test_dynamic() async {
     await resolveTestUnit('''
 class A {
   var test;
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_firstInitializer() async {
+  Future<void> test_firstInitializer() async {
     await resolveTestUnit('''
 class A {
   int test;
@@ -53,7 +53,7 @@
 ''');
   }
 
-  test_secondInitializer() async {
+  Future<void> test_secondInitializer() async {
     await resolveTestUnit('''
 class A {
   double aaa;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_null_aware_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_null_aware_test.dart
index dfe8b4e..47027ee 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_null_aware_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_null_aware_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToNormalParameterTest);
   });
@@ -20,7 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_NULL_AWARE;
 
-  test_equal_differentTarget() async {
+  Future<void> test_equal_differentTarget() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
@@ -30,7 +30,7 @@
     await assertNoAssistAt('?');
   }
 
-  test_equal_notComparedToNull() async {
+  Future<void> test_equal_notComparedToNull() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
@@ -40,7 +40,7 @@
     await assertNoAssistAt('?');
   }
 
-  test_equal_notIdentifier() async {
+  Future<void> test_equal_notIdentifier() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
@@ -50,7 +50,7 @@
     await assertNoAssistAt('?');
   }
 
-  test_equal_notInvocation() async {
+  Future<void> test_equal_notInvocation() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
@@ -61,7 +61,7 @@
     await assertNoAssistAt('?');
   }
 
-  test_equal_notNullPreserving() async {
+  Future<void> test_equal_notNullPreserving() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
@@ -71,7 +71,7 @@
     await assertNoAssistAt('?');
   }
 
-  test_equal_notPeriod() async {
+  Future<void> test_equal_notPeriod() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
@@ -81,7 +81,7 @@
     await assertNoAssistAt('? ');
   }
 
-  test_equal_nullOnLeft() async {
+  Future<void> test_equal_nullOnLeft() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
@@ -96,7 +96,7 @@
 ''');
   }
 
-  test_equal_nullOnLeft_noAssistWithLint() async {
+  Future<void> test_equal_nullOnLeft_noAssistWithLint() async {
     createAnalysisOptionsFile(lints: [LintNames.prefer_null_aware_operators]);
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
@@ -108,7 +108,7 @@
     await assertNoAssist();
   }
 
-  test_equal_nullOnRight() async {
+  Future<void> test_equal_nullOnRight() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
@@ -123,7 +123,7 @@
 ''');
   }
 
-  test_equal_prefixedIdentifier() async {
+  Future<void> test_equal_prefixedIdentifier() async {
     await resolveTestUnit('''
 class A {
   int p;
@@ -138,7 +138,7 @@
 ''');
   }
 
-  test_notEqual_notNullPreserving() async {
+  Future<void> test_notEqual_notNullPreserving() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
@@ -148,7 +148,7 @@
     await assertNoAssistAt('?');
   }
 
-  test_notEqual_nullOnLeft() async {
+  Future<void> test_notEqual_nullOnLeft() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
@@ -163,7 +163,7 @@
 ''');
   }
 
-  test_notEqual_nullOnRight() async {
+  Future<void> test_notEqual_nullOnRight() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_package_import_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_package_import_test.dart
index 9da35b6..db35739 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_package_import_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_package_import_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToPackageImportTest);
   });
@@ -20,7 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_PACKAGE_IMPORT;
 
-  test_fileName_onImport() async {
+  Future<void> test_fileName_onImport() async {
     addSource('/home/test/lib/foo.dart', '');
 
     await resolveTestUnit('''
@@ -32,7 +32,7 @@
 ''');
   }
 
-  test_fileName_onUri() async {
+  Future<void> test_fileName_onUri() async {
     addSource('/home/test/lib/foo.dart', '');
 
     await resolveTestUnit('''
@@ -43,7 +43,7 @@
 ''');
   }
 
-  test_invalidUri() async {
+  Future<void> test_invalidUri() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 import ':[invalidUri]';
@@ -51,7 +51,7 @@
     await assertNoAssistAt('invalid');
   }
 
-  test_nonPackage_Uri() async {
+  Future<void> test_nonPackage_Uri() async {
     addSource('/home/test/lib/foo.dart', '');
     testFile = convertPath('/home/test/lib/src/test.dart');
     await resolveTestUnit('''
@@ -62,7 +62,7 @@
     await assertNoAssistAt('import');
   }
 
-  test_packageUri() async {
+  Future<void> test_packageUri() async {
     addSource('/home/test/lib/foo.dart', '');
 
     await resolveTestUnit('''
@@ -72,7 +72,7 @@
     await assertNoAssistAt('import');
   }
 
-  test_path() async {
+  Future<void> test_path() async {
     addSource('/home/test/lib/foo/bar.dart', '');
 
     testFile = convertPath('/home/test/lib/src/test.dart');
@@ -85,7 +85,7 @@
 ''');
   }
 
-  test_relativeImport_noAssistWithLint() async {
+  Future<void> test_relativeImport_noAssistWithLint() async {
     createAnalysisOptionsFile(lints: [LintNames.avoid_relative_lib_imports]);
     verifyNoTestUnitErrors = false;
     addSource('/home/test/lib/foo.dart', '');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_set_literal_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_set_literal_test.dart
index 053bba7..1480548 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_set_literal_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_set_literal_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToSetLiteralTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_SET_LITERAL;
 
-  test_default_declaredType() async {
+  Future<void> test_default_declaredType() async {
     await resolveTestUnit('''
 Set s = S/*caret*/et();
 ''');
@@ -28,7 +28,7 @@
 ''');
   }
 
-  test_default_minimal() async {
+  Future<void> test_default_minimal() async {
     await resolveTestUnit('''
 var s = S/*caret*/et();
 ''');
@@ -37,7 +37,7 @@
 ''');
   }
 
-  test_default_newKeyword() async {
+  Future<void> test_default_newKeyword() async {
     await resolveTestUnit('''
 var s = new S/*caret*/et();
 ''');
@@ -46,7 +46,7 @@
 ''');
   }
 
-  test_default_typeArg() async {
+  Future<void> test_default_typeArg() async {
     await resolveTestUnit('''
 var s = S/*caret*/et<int>();
 ''');
@@ -55,7 +55,7 @@
 ''');
   }
 
-  test_from_empty() async {
+  Future<void> test_from_empty() async {
     await resolveTestUnit('''
 var s = S/*caret*/et.from([]);
 ''');
@@ -64,7 +64,7 @@
 ''');
   }
 
-  test_from_newKeyword() async {
+  Future<void> test_from_newKeyword() async {
     await resolveTestUnit('''
 var s = new S/*caret*/et.from([2, 3]);
 ''');
@@ -73,7 +73,7 @@
 ''');
   }
 
-  test_from_noKeyword_declaredType() async {
+  Future<void> test_from_noKeyword_declaredType() async {
     await resolveTestUnit('''
 Set s = S/*caret*/et.from([2, 3]);
 ''');
@@ -82,7 +82,7 @@
 ''');
   }
 
-  test_from_noKeyword_typeArg_onConstructor() async {
+  Future<void> test_from_noKeyword_typeArg_onConstructor() async {
     await resolveTestUnit('''
 var s = S/*caret*/et<int>.from([2, 3]);
 ''');
@@ -91,7 +91,7 @@
 ''');
   }
 
-  test_from_noKeyword_typeArg_onConstructorAndLiteral() async {
+  Future<void> test_from_noKeyword_typeArg_onConstructorAndLiteral() async {
     await resolveTestUnit('''
 var s = S/*caret*/et<int>.from(<num>[2, 3]);
 ''');
@@ -100,7 +100,7 @@
 ''');
   }
 
-  test_from_noKeyword_typeArg_onLiteral() async {
+  Future<void> test_from_noKeyword_typeArg_onLiteral() async {
     await resolveTestUnit('''
 var s = S/*caret*/et.from(<int>[2, 3]);
 ''');
@@ -109,7 +109,7 @@
 ''');
   }
 
-  test_from_nonEmpty() async {
+  Future<void> test_from_nonEmpty() async {
     await resolveTestUnit('''
 var s = S/*caret*/et.from([2, 3]);
 ''');
@@ -118,7 +118,7 @@
 ''');
   }
 
-  test_from_notALiteral() async {
+  Future<void> test_from_notALiteral() async {
     await resolveTestUnit('''
 var l = [1];
 Set s = new S/*caret*/et.from(l);
@@ -126,7 +126,7 @@
     await assertNoAssist();
   }
 
-  test_from_trailingComma() async {
+  Future<void> test_from_trailingComma() async {
     await resolveTestUnit('''
 var s = S/*caret*/et.from([2, 3,]);
 ''');
@@ -135,7 +135,7 @@
 ''');
   }
 
-  test_toSet_empty() async {
+  Future<void> test_toSet_empty() async {
     await resolveTestUnit('''
 var s = [].to/*caret*/Set();
 ''');
@@ -144,7 +144,7 @@
 ''');
   }
 
-  test_toSet_empty_typeArg() async {
+  Future<void> test_toSet_empty_typeArg() async {
     await resolveTestUnit('''
 var s = <int>[].to/*caret*/Set();
 ''');
@@ -153,7 +153,7 @@
 ''');
   }
 
-  test_toSet_nonEmpty() async {
+  Future<void> test_toSet_nonEmpty() async {
     await resolveTestUnit('''
 var s = [2, 3].to/*caret*/Set();
 ''');
@@ -162,7 +162,7 @@
 ''');
   }
 
-  test_toSet_nonEmpty_typeArg() async {
+  Future<void> test_toSet_nonEmpty_typeArg() async {
     await resolveTestUnit('''
 var s = <int>[2, 3].to/*caret*/Set();
 ''');
@@ -171,7 +171,7 @@
 ''');
   }
 
-  test_toSet_notALiteral() async {
+  Future<void> test_toSet_notALiteral() async {
     await resolveTestUnit('''
 var l = [];
 var s = l.to/*caret*/Set();
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_single_quoted_string_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_single_quoted_string_test.dart
index 6c34598..35bb812 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_single_quoted_string_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_single_quoted_string_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToSingleQuotedStringTest);
   });
@@ -20,7 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.CONVERT_TO_SINGLE_QUOTED_STRING;
 
-  test_one_embeddedTarget() async {
+  Future<void> test_one_embeddedTarget() async {
     await resolveTestUnit('''
 main() {
   print("a'b'c");
@@ -29,7 +29,7 @@
     await assertNoAssistAt('"a');
   }
 
-  test_one_enclosingTarget() async {
+  Future<void> test_one_enclosingTarget() async {
     await resolveTestUnit('''
 main() {
   print('abc');
@@ -38,7 +38,7 @@
     await assertNoAssistAt("'ab");
   }
 
-  test_one_interpolation() async {
+  Future<void> test_one_interpolation() async {
     await resolveTestUnit(r'''
 main() {
   var b = 'b';
@@ -55,7 +55,7 @@
 ''');
   }
 
-  test_one_raw() async {
+  Future<void> test_one_raw() async {
     await resolveTestUnit('''
 main() {
   print(r"abc");
@@ -68,7 +68,7 @@
 ''');
   }
 
-  test_one_simple() async {
+  Future<void> test_one_simple() async {
     await resolveTestUnit('''
 main() {
   print("abc");
@@ -81,7 +81,7 @@
 ''');
   }
 
-  test_one_simple_noAssistWithLint() async {
+  Future<void> test_one_simple_noAssistWithLint() async {
     createAnalysisOptionsFile(lints: [LintNames.prefer_single_quotes]);
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
@@ -92,7 +92,7 @@
     await assertNoAssist();
   }
 
-  test_three_embeddedTarget() async {
+  Future<void> test_three_embeddedTarget() async {
     await resolveTestUnit('''
 main() {
   print("""a''\'bc""");
@@ -101,7 +101,7 @@
     await assertNoAssistAt('"a');
   }
 
-  test_three_enclosingTarget() async {
+  Future<void> test_three_enclosingTarget() async {
     await resolveTestUnit("""
 main() {
   print('''abc''');
@@ -110,7 +110,7 @@
     await assertNoAssistAt("'ab");
   }
 
-  test_three_interpolation() async {
+  Future<void> test_three_interpolation() async {
     await resolveTestUnit(r'''
 main() {
   var b = 'b';
@@ -127,7 +127,7 @@
 """);
   }
 
-  test_three_raw() async {
+  Future<void> test_three_raw() async {
     await resolveTestUnit('''
 main() {
   print(r"""abc""");
@@ -140,7 +140,7 @@
 """);
   }
 
-  test_three_simple() async {
+  Future<void> test_three_simple() async {
     await resolveTestUnit('''
 main() {
   print("""abc""");
diff --git a/pkg/analysis_server/test/src/services/correction/assist/convert_to_spread_test.dart b/pkg/analysis_server/test/src/services/correction/assist/convert_to_spread_test.dart
index 31c242a..7a8b12d 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/convert_to_spread_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/convert_to_spread_test.dart
@@ -10,7 +10,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToSpreadTest);
     defineReflectiveTests(ConvertToSpreadWithControlFlowTest);
@@ -28,7 +28,7 @@
     super.setUp();
   }
 
-  test_addAll_expression() async {
+  Future<void> test_addAll_expression() async {
     await resolveTestUnit('''
 f() {
   var ints = [1, 2, 3];
@@ -43,7 +43,7 @@
 ''');
   }
 
-  test_addAll_expression_noAssistWithLint() async {
+  Future<void> test_addAll_expression_noAssistWithLint() async {
     createAnalysisOptionsFile(lints: [LintNames.prefer_spread_collections]);
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
@@ -55,7 +55,7 @@
     await assertNoAssist();
   }
 
-  test_addAll_expression_toEmptyList() async {
+  Future<void> test_addAll_expression_toEmptyList() async {
     await resolveTestUnit('''
 f() {
   var ints = [1, 2, 3];
@@ -70,7 +70,7 @@
 ''');
   }
 
-  test_addAll_literal() async {
+  Future<void> test_addAll_literal() async {
     // This case is covered by the INLINE_INVOCATION assist.
     await resolveTestUnit('''
 var l = ['a']..add/*caret*/All(['b'])..addAll(['c']);
@@ -78,7 +78,7 @@
     await assertNoAssist();
   }
 
-  test_addAll_nonLiteralTarget() async {
+  Future<void> test_addAll_nonLiteralTarget() async {
     await resolveTestUnit('''
 var l1 = [];
 var l2 = l1..addAl/*caret*/l(['b'])..addAll(['c']);
@@ -86,14 +86,14 @@
     await assertNoAssist();
   }
 
-  test_addAll_notFirst() async {
+  Future<void> test_addAll_notFirst() async {
     await resolveTestUnit('''
 var l = ['a']..addAll(['b'])../*caret*/addAll(['c']);
 ''');
     await assertNoAssist();
   }
 
-  test_addAll_nullAware_const() async {
+  Future<void> test_addAll_nullAware_const() async {
     await resolveTestUnit('''
 var things;
 var l = ['a']..add/*caret*/All(things ?? const []);
@@ -104,7 +104,7 @@
 ''');
   }
 
-  test_addAll_nullAware_nonConst() async {
+  Future<void> test_addAll_nullAware_nonConst() async {
     await resolveTestUnit('''
 var things;
 var l = ['a']..add/*caret*/All(things ?? []);
@@ -130,7 +130,7 @@
     super.setUp();
   }
 
-  test_addAll_condition_const() async {
+  Future<void> test_addAll_condition_const() async {
     await resolveTestUnit('''
 bool condition;
 var things;
@@ -143,7 +143,7 @@
 ''');
   }
 
-  test_addAll_condition_nonConst() async {
+  Future<void> test_addAll_condition_nonConst() async {
     await resolveTestUnit('''
 bool condition;
 var things;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/encapsulate_field_test.dart b/pkg/analysis_server/test/src/services/correction/assist/encapsulate_field_test.dart
index 98e3baf..55e1bcb 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/encapsulate_field_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/encapsulate_field_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(EncapsulateFieldTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.ENCAPSULATE_FIELD;
 
-  test_alreadyPrivate() async {
+  Future<void> test_alreadyPrivate() async {
     await resolveTestUnit('''
 class A {
   int _test = 42;
@@ -31,7 +31,7 @@
     await assertNoAssistAt('_test =');
   }
 
-  test_documentation() async {
+  Future<void> test_documentation() async {
     await resolveTestUnit('''
 class A {
   /// AAA
@@ -58,7 +58,7 @@
 ''');
   }
 
-  test_final() async {
+  Future<void> test_final() async {
     await resolveTestUnit('''
 class A {
   final int test = 42;
@@ -67,7 +67,7 @@
     await assertNoAssistAt('test =');
   }
 
-  test_hasType() async {
+  Future<void> test_hasType() async {
     await resolveTestUnit('''
 class A {
   int test = 42;
@@ -94,7 +94,7 @@
 ''');
   }
 
-  test_multipleFields() async {
+  Future<void> test_multipleFields() async {
     await resolveTestUnit('''
 class A {
   int aaa, bbb, ccc;
@@ -106,7 +106,7 @@
     await assertNoAssistAt('bbb, ');
   }
 
-  test_notOnName() async {
+  Future<void> test_notOnName() async {
     await resolveTestUnit('''
 class A {
   int test = 1 + 2 + 3;
@@ -115,7 +115,7 @@
     await assertNoAssistAt('+ 2');
   }
 
-  test_noType() async {
+  Future<void> test_noType() async {
     await resolveTestUnit('''
 class A {
   var test = 42;
@@ -140,7 +140,7 @@
 ''');
   }
 
-  test_parseError() async {
+  Future<void> test_parseError() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 class A {
@@ -153,7 +153,7 @@
     await assertNoAssistAt('; // marker');
   }
 
-  test_static() async {
+  Future<void> test_static() async {
     await resolveTestUnit('''
 class A {
   static int test = 42;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/exchange_operands_test.dart b/pkg/analysis_server/test/src/services/correction/assist/exchange_operands_test.dart
index f61f674..21b3f96 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/exchange_operands_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/exchange_operands_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ExchangeOperandsTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.EXCHANGE_OPERANDS;
 
-  test_compare() async {
+  Future<void> test_compare() async {
     const initialOperators = ['<', '<=', '>', '>='];
     const resultOperators = ['>', '>=', '<', '<='];
     for (int i = 0; i <= 0; i++) {
@@ -38,7 +38,7 @@
     }
   }
 
-  test_extended_mixOperator_1() async {
+  Future<void> test_extended_mixOperator_1() async {
     await resolveTestUnit('''
 main() {
   1 * 2 * 3 + 4;
@@ -51,7 +51,7 @@
 ''');
   }
 
-  test_extended_mixOperator_2() async {
+  Future<void> test_extended_mixOperator_2() async {
     await resolveTestUnit('''
 main() {
   1 + 2 - 3 + 4;
@@ -64,7 +64,7 @@
 ''');
   }
 
-  test_extended_sameOperator_afterFirst() async {
+  Future<void> test_extended_sameOperator_afterFirst() async {
     await resolveTestUnit('''
 main() {
   1 + 2 + 3;
@@ -77,7 +77,7 @@
 ''');
   }
 
-  test_extended_sameOperator_afterSecond() async {
+  Future<void> test_extended_sameOperator_afterSecond() async {
     await resolveTestUnit('''
 main() {
   1 + 2 + 3;
@@ -90,7 +90,7 @@
 ''');
   }
 
-  test_extraLength() async {
+  Future<void> test_extraLength() async {
     await resolveTestUnit('''
 main() {
   111 + 222;
@@ -99,7 +99,7 @@
     await assertNoAssistAt('+ 222', length: 3);
   }
 
-  test_onOperand() async {
+  Future<void> test_onOperand() async {
     await resolveTestUnit('''
 main() {
   111 + 222;
@@ -108,7 +108,7 @@
     await assertNoAssistAt('11 +', length: 3);
   }
 
-  test_selectionWithBinary() async {
+  Future<void> test_selectionWithBinary() async {
     await resolveTestUnit('''
 main() {
   1 + 2 + 3;
@@ -117,7 +117,7 @@
     await assertNoAssistAt('1 + 2 + 3', length: '1 + 2 + 3'.length);
   }
 
-  test_simple_afterOperator() async {
+  Future<void> test_simple_afterOperator() async {
     await resolveTestUnit('''
 main() {
   1 + 2;
@@ -130,7 +130,7 @@
 ''');
   }
 
-  test_simple_beforeOperator() async {
+  Future<void> test_simple_beforeOperator() async {
     await resolveTestUnit('''
 main() {
   1 + 2;
@@ -143,7 +143,7 @@
 ''');
   }
 
-  test_simple_fullSelection() async {
+  Future<void> test_simple_fullSelection() async {
     await resolveTestUnit('''
 main() {
   1 + 2;
@@ -159,7 +159,7 @@
         length: '1 + 2'.length);
   }
 
-  test_simple_withLength() async {
+  Future<void> test_simple_withLength() async {
     await resolveTestUnit('''
 main() {
   1 + 2;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_convert_to_children_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_convert_to_children_test.dart
index 00e8383..b34b23d 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_convert_to_children_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_convert_to_children_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterConvertToChildrenTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_CONVERT_TO_CHILDREN;
 
-  test_childUnresolved() async {
+  Future<void> test_childUnresolved() async {
     addFlutterPackage();
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
@@ -33,7 +33,7 @@
     await assertNoAssist();
   }
 
-  test_multiLine() async {
+  Future<void> test_multiLine() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -54,7 +54,7 @@
 build() {
   return Scaffold(
     body: Center(
-      children: <Widget>[
+      children: [
         Container(
           width: 200.0,
           height: 300.0,
@@ -67,7 +67,7 @@
 ''');
   }
 
-  test_newlineChild() async {
+  Future<void> test_newlineChild() async {
     // This case could occur with deeply nested constructors, common in Flutter.
     addFlutterPackage();
     await resolveTestUnit('''
@@ -90,7 +90,7 @@
 build() {
   return Scaffold(
     body: Center(
-      children: <Widget>[
+      children: [
         Container(
           width: 200.0,
           height: 300.0,
@@ -103,7 +103,7 @@
 ''');
   }
 
-  test_notOnChild() async {
+  Future<void> test_notOnChild() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -118,7 +118,7 @@
     await assertNoAssist();
   }
 
-  test_singleLine() async {
+  Future<void> test_singleLine() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -136,7 +136,7 @@
 build() {
   return Scaffold(
     body: Center(
-      children: <Widget>[GestureDetector()],
+      children: [GestureDetector()],
       key: null,
     ),
   );
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_convert_to_stateful_widget_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_convert_to_stateful_widget_test.dart
index bb90063..d239e4b 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_convert_to_stateful_widget_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_convert_to_stateful_widget_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterConvertToStatefulWidgetTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_CONVERT_TO_STATEFUL_WIDGET;
 
-  test_empty() async {
+  Future<void> test_empty() async {
     addFlutterPackage();
     await resolveTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -48,7 +48,7 @@
 ''');
   }
 
-  test_empty_typeParam() async {
+  Future<void> test_empty_typeParam() async {
     addFlutterPackage();
     await resolveTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -77,7 +77,7 @@
 ''');
   }
 
-  test_fields() async {
+  Future<void> test_fields() async {
     addFlutterPackage();
     await resolveTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -158,7 +158,7 @@
 ''');
   }
 
-  test_getters() async {
+  Future<void> test_getters() async {
     addFlutterPackage();
     await resolveTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -217,7 +217,7 @@
 ''');
   }
 
-  test_methods() async {
+  Future<void> test_methods() async {
     addFlutterPackage();
     await resolveTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -307,7 +307,7 @@
 ''');
   }
 
-  test_notClass() async {
+  Future<void> test_notClass() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -316,7 +316,7 @@
     await assertNoAssist();
   }
 
-  test_notStatelessWidget() async {
+  Future<void> test_notStatelessWidget() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -327,7 +327,7 @@
     await assertNoAssist();
   }
 
-  test_notWidget() async {
+  Future<void> test_notWidget() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -336,7 +336,7 @@
     await assertNoAssist();
   }
 
-  test_simple() async {
+  Future<void> test_simple() async {
     addFlutterPackage();
     await resolveTestUnit(r'''
 import 'package:flutter/material.dart';
@@ -389,7 +389,7 @@
 ''');
   }
 
-  test_tail() async {
+  Future<void> test_tail() async {
     addFlutterPackage();
     await resolveTestUnit(r'''
 import 'package:flutter/material.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_move_down_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_move_down_test.dart
index 27069f0..ee427b0 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_move_down_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_move_down_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterMoveDownTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_MOVE_DOWN;
 
-  test_first() async {
+  Future<void> test_first() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -48,7 +48,7 @@
     assertExitPosition(before: "Text('bbbbbb')");
   }
 
-  test_last() async {
+  Future<void> test_last() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -65,7 +65,7 @@
     await assertNoAssist();
   }
 
-  test_notInList() async {
+  Future<void> test_notInList() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_move_up_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_move_up_test.dart
index a6b58b6..a88b498 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_move_up_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_move_up_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterMoveUpTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_MOVE_UP;
 
-  test_first() async {
+  Future<void> test_first() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -36,7 +36,7 @@
     await assertNoAssist();
   }
 
-  test_last() async {
+  Future<void> test_last() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -65,7 +65,7 @@
     assertExitPosition(before: "Text('bbbbbb')");
   }
 
-  test_notInList() async {
+  Future<void> test_notInList() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_remove_widget_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_remove_widget_test.dart
index 03f1287..fb81386 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_remove_widget_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_remove_widget_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterRemoveWidgetTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_REMOVE_WIDGET;
 
-  test_childIntoChild_multiLine() async {
+  Future<void> test_childIntoChild_multiLine() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -56,7 +56,7 @@
 ''');
   }
 
-  test_childIntoChild_singleLine() async {
+  Future<void> test_childIntoChild_singleLine() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -81,7 +81,7 @@
 ''');
   }
 
-  test_childIntoChildren() async {
+  Future<void> test_childIntoChildren() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -118,7 +118,7 @@
 ''');
   }
 
-  test_childrenMultipleIntoChild() async {
+  Future<void> test_childrenMultipleIntoChild() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -136,7 +136,7 @@
     await assertNoAssist();
   }
 
-  test_childrenOneIntoChild() async {
+  Future<void> test_childrenOneIntoChild() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -160,7 +160,7 @@
 ''');
   }
 
-  test_childrenOneIntoReturn() async {
+  Future<void> test_childrenOneIntoReturn() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -180,7 +180,7 @@
 ''');
   }
 
-  test_intoChildren() async {
+  Future<void> test_intoChildren() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_surround_with_set_state_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_surround_with_set_state_test.dart
index 16d8754..35dac67 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_surround_with_set_state_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_surround_with_set_state_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterSurroundWithSetStateTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SURROUND_WITH_SET_STATE;
 
-  test_outsideState() async {
+  Future<void> test_outsideState() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -39,7 +39,7 @@
     await assertNoAssist();
   }
 
-  test_stateSubclass() async {
+  Future<void> test_stateSubclass() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_swap_with_child_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_swap_with_child_test.dart
index 7ec4246..0228ef0 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_swap_with_child_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_swap_with_child_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterSwapWithChildTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_SWAP_WITH_CHILD;
 
-  test_aroundCenter() async {
+  Future<void> test_aroundCenter() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -59,7 +59,7 @@
 ''');
   }
 
-  test_notFormatted() async {
+  Future<void> test_notFormatted() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_swap_with_parent_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_swap_with_parent_test.dart
index 13a88b7..dd3ce14 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_swap_with_parent_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_swap_with_parent_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterSwapWithParentTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_SWAP_WITH_PARENT;
 
-  test_inCenter() async {
+  Future<void> test_inCenter() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -59,7 +59,7 @@
 ''');
   }
 
-  test_notFormatted() async {
+  Future<void> test_notFormatted() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -110,7 +110,7 @@
 }''');
   }
 
-  test_outerIsInChildren() async {
+  Future<void> test_outerIsInChildren() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_center_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_center_test.dart
index caca61e..752cc43 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_center_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_center_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterWrapCenterTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_WRAP_CENTER;
 
-  test_aroundCenter() async {
+  Future<void> test_aroundCenter() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -32,7 +32,7 @@
     await assertNoAssist();
   }
 
-  test_aroundContainer() async {
+  Future<void> test_aroundContainer() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -52,7 +52,7 @@
 ''');
   }
 
-  test_aroundNamedConstructor() async {
+  Future<void> test_aroundNamedConstructor() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -82,7 +82,7 @@
 ''');
   }
 
-  test_assignment() async {
+  Future<void> test_assignment() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -102,7 +102,7 @@
 ''');
   }
 
-  test_expressionFunctionBody() async {
+  Future<void> test_expressionFunctionBody() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_column_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_column_test.dart
index c22ea1d9..629ebde 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_column_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_column_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterWrapColumnTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_WRAP_COLUMN;
 
-  test_controlFlowCollections_if() async {
+  Future<void> test_controlFlowCollections_if() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -53,7 +53,7 @@
 ''');
   }
 
-  test_coveredByWidget() async {
+  Future<void> test_coveredByWidget() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -83,7 +83,7 @@
 ''');
   }
 
-  test_coversWidgets() async {
+  Future<void> test_coversWidgets() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_container_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_container_test.dart
index f52a92c..26e88f7 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_container_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_container_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterWrapContainerTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_WRAP_CONTAINER;
 
-  test_aroundContainer() async {
+  Future<void> test_aroundContainer() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -30,7 +30,7 @@
     await assertNoAssist();
   }
 
-  test_aroundText() async {
+  Future<void> test_aroundText() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_generic_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_generic_test.dart
index 40983c8..6905f54 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_generic_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_generic_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterWrapGenericTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_WRAP_GENERIC;
 
-  test_minimal() async {
+  Future<void> test_minimal() async {
     addFlutterPackage();
     await resolveTestUnit('''
 /*caret*/x(){}
@@ -27,7 +27,7 @@
     await assertNoAssist();
   }
 
-  test_multiLine() async {
+  Future<void> test_multiLine() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -63,7 +63,7 @@
 ''');
   }
 
-  test_multiLine_inListLiteral() async {
+  Future<void> test_multiLine_inListLiteral() async {
     verifyNoTestUnitErrors = false;
     addFlutterPackage();
     await resolveTestUnit('''
@@ -85,7 +85,7 @@
     await assertNoAssist();
   }
 
-  test_multiLines() async {
+  Future<void> test_multiLines() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -125,7 +125,7 @@
 ''');
   }
 
-  test_multiLines_eol2() async {
+  Future<void> test_multiLines_eol2() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -165,7 +165,7 @@
 ''');
   }
 
-  test_prefixedIdentifier_identifier() async {
+  Future<void> test_prefixedIdentifier_identifier() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -191,7 +191,7 @@
 ''');
   }
 
-  test_prefixedIdentifier_prefix() async {
+  Future<void> test_prefixedIdentifier_prefix() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -217,7 +217,7 @@
 ''');
   }
 
-  test_singleLine() async {
+  Future<void> test_singleLine() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -231,7 +231,7 @@
     await assertNoAssist();
   }
 
-  test_singleLine1() async {
+  Future<void> test_singleLine1() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -251,7 +251,7 @@
 ''');
   }
 
-  test_singleLine2() async {
+  Future<void> test_singleLine2() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -271,7 +271,7 @@
 ''');
   }
 
-  test_variable() async {
+  Future<void> test_variable() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_padding_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_padding_test.dart
index d715dd2..27cf35b 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_padding_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_padding_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterWrapPaddingTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_WRAP_PADDING;
 
-  test_aroundContainer() async {
+  Future<void> test_aroundContainer() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_aroundPadding() async {
+  Future<void> test_aroundPadding() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_row_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_row_test.dart
index 32331c2..fe71efc 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_row_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_row_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterWrapRowTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_WRAP_ROW;
 
-  test_twoWidgets() async {
+  Future<void> test_twoWidgets() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_stream_builder_test.dart b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_stream_builder_test.dart
index c924f7e..c44049f 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_stream_builder_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/flutter_wrap_stream_builder_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterWrapStreamBuilderTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.FLUTTER_WRAP_STREAM_BUILDER;
 
-  test_aroundStreamBuilder() async {
+  Future<void> test_aroundStreamBuilder() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -34,7 +34,7 @@
     await assertNoAssist();
   }
 
-  test_aroundText() async {
+  Future<void> test_aroundText() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/import_add_show_test.dart b/pkg/analysis_server/test/src/services/correction/assist/import_add_show_test.dart
index 4c62dde..13c325b 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/import_add_show_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/import_add_show_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ImportAddShowTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.IMPORT_ADD_SHOW;
 
-  test_hasShow() async {
+  Future<void> test_hasShow() async {
     await resolveTestUnit('''
 import 'dart:math' show PI;
 main() {
@@ -29,7 +29,7 @@
     await assertNoAssistAt('import ');
   }
 
-  test_hasUnresolvedIdentifier() async {
+  Future<void> test_hasUnresolvedIdentifier() async {
     await resolveTestUnit('''
 import 'dart:math';
 main(x) {
@@ -46,7 +46,7 @@
 ''');
   }
 
-  test_onDirective() async {
+  Future<void> test_onDirective() async {
     await resolveTestUnit('''
 import 'dart:math';
 main() {
@@ -65,7 +65,7 @@
 ''');
   }
 
-  test_onUri() async {
+  Future<void> test_onUri() async {
     await resolveTestUnit('''
 import 'dart:math';
 main() {
@@ -84,7 +84,7 @@
 ''');
   }
 
-  test_unresolvedUri() async {
+  Future<void> test_unresolvedUri() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 import '/no/such/lib.dart';
@@ -92,7 +92,7 @@
     await assertNoAssistAt('import ');
   }
 
-  test_unused() async {
+  Future<void> test_unused() async {
     await resolveTestUnit('''
 import 'dart:math';
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/inline_invocation_test.dart b/pkg/analysis_server/test/src/services/correction/assist/inline_invocation_test.dart
index 7967c09..d013c1e 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/inline_invocation_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/inline_invocation_test.dart
@@ -10,7 +10,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InlineInvocationTest);
   });
@@ -27,7 +27,7 @@
     super.setUp();
   }
 
-  test_add_emptyTarget() async {
+  Future<void> test_add_emptyTarget() async {
     await resolveTestUnit('''
 var l = []..ad/*caret*/d('a')..add('b');
 ''');
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_add_emptyTarget_noAssistWithLint() async {
+  Future<void> test_add_emptyTarget_noAssistWithLint() async {
     createAnalysisOptionsFile(lints: [LintNames.prefer_inlined_adds]);
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
@@ -45,7 +45,7 @@
     await assertNoAssist();
   }
 
-  test_add_nonEmptyTarget() async {
+  Future<void> test_add_nonEmptyTarget() async {
     await resolveTestUnit('''
 var l = ['a']..ad/*caret*/d('b')..add('c');
 ''');
@@ -54,7 +54,7 @@
 ''');
   }
 
-  test_add_nonLiteralArgument() async {
+  Future<void> test_add_nonLiteralArgument() async {
     await resolveTestUnit('''
 var e = 'b';
 var l = ['a']..add/*caret*/(e);
@@ -65,7 +65,7 @@
 ''');
   }
 
-  test_add_nonLiteralTarget() async {
+  Future<void> test_add_nonLiteralTarget() async {
     await resolveTestUnit('''
 var l1 = [];
 var l2 = l1..ad/*caret*/d('b')..add('c');
@@ -73,14 +73,14 @@
     await assertNoAssist();
   }
 
-  test_add_notFirst() async {
+  Future<void> test_add_notFirst() async {
     await resolveTestUnit('''
 var l = ['a']..add('b')../*caret*/add('c');
 ''');
     await assertNoAssist();
   }
 
-  test_addAll_emptyTarget() async {
+  Future<void> test_addAll_emptyTarget() async {
     await resolveTestUnit('''
 var l = []..add/*caret*/All(['a'])..addAll(['b']);
 ''');
@@ -89,7 +89,7 @@
 ''');
   }
 
-  test_addAll_emptyTarget_noAssistWithLint() async {
+  Future<void> test_addAll_emptyTarget_noAssistWithLint() async {
     createAnalysisOptionsFile(lints: [LintNames.prefer_inlined_adds]);
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
@@ -98,7 +98,7 @@
     await assertNoAssist();
   }
 
-  test_addAll_nonEmptyTarget() async {
+  Future<void> test_addAll_nonEmptyTarget() async {
     await resolveTestUnit('''
 var l = ['a']..add/*caret*/All(['b'])..addAll(['c']);
 ''');
@@ -107,7 +107,7 @@
 ''');
   }
 
-  test_addAll_nonLiteralArgument() async {
+  Future<void> test_addAll_nonLiteralArgument() async {
     await resolveTestUnit('''
 var l1 = <String>[];
 var l2 = ['a']..add/*caret*/All(l1);
@@ -115,7 +115,7 @@
     await assertNoAssist();
   }
 
-  test_addAll_nonLiteralTarget() async {
+  Future<void> test_addAll_nonLiteralTarget() async {
     await resolveTestUnit('''
 var l1 = [];
 var l2 = l1..addAl/*caret*/l(['b'])..addAll(['c']);
@@ -123,7 +123,7 @@
     await assertNoAssist();
   }
 
-  test_addAll_notFirst() async {
+  Future<void> test_addAll_notFirst() async {
     await resolveTestUnit('''
 var l = ['a']..addAll(['b'])../*caret*/addAll(['c']);
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/assist/introduce_local_cast_type_test.dart b/pkg/analysis_server/test/src/services/correction/assist/introduce_local_cast_type_test.dart
index 2201266..1607452 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/introduce_local_cast_type_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/introduce_local_cast_type_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(IntroduceLocalCastTypeTest);
   });
@@ -20,36 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.INTRODUCE_LOCAL_CAST_TYPE;
 
-  test_introduceLocalTestedType_notBlock() async {
-    await resolveTestUnit('''
-main(p) {
-  if (p is String)
-    print('not a block');
-}
-''');
-    await assertNoAssistAt('if (p');
-  }
-
-  test_introduceLocalTestedType_notIsExpression() async {
-    await resolveTestUnit('''
-main(p) {
-  if (p == null) {
-  }
-}
-''');
-    await assertNoAssistAt('if (p');
-  }
-
-  test_introduceLocalTestedType_notStatement() async {
-    await resolveTestUnit('''
-class C {
-  bool b;
-  C(v) : b = v is int;
-}''');
-    await assertNoAssistAt('is int');
-  }
-
-  test_introduceLocalTestedType_if_is() async {
+  Future<void> test_introduceLocalTestedType_if_is() async {
     await resolveTestUnit('''
 class MyTypeName {}
 main(p) {
@@ -77,7 +48,7 @@
     await assertHasAssistAt('if (p', expected);
   }
 
-  test_introduceLocalTestedType_if_isNot() async {
+  Future<void> test_introduceLocalTestedType_if_isNot() async {
     await resolveTestUnit('''
 class MyTypeName {}
 main(p) {
@@ -105,7 +76,36 @@
     await assertHasAssistAt('if (p', expected);
   }
 
-  test_introduceLocalTestedType_while() async {
+  Future<void> test_introduceLocalTestedType_notBlock() async {
+    await resolveTestUnit('''
+main(p) {
+  if (p is String)
+    print('not a block');
+}
+''');
+    await assertNoAssistAt('if (p');
+  }
+
+  Future<void> test_introduceLocalTestedType_notIsExpression() async {
+    await resolveTestUnit('''
+main(p) {
+  if (p == null) {
+  }
+}
+''');
+    await assertNoAssistAt('if (p');
+  }
+
+  Future<void> test_introduceLocalTestedType_notStatement() async {
+    await resolveTestUnit('''
+class C {
+  bool b;
+  C(v) : b = v is int;
+}''');
+    await assertNoAssistAt('is int');
+  }
+
+  Future<void> test_introduceLocalTestedType_while() async {
     await resolveTestUnit('''
 main(p) {
   while (p is String) {
diff --git a/pkg/analysis_server/test/src/services/correction/assist/invert_if_statement_test.dart b/pkg/analysis_server/test/src/services/correction/assist/invert_if_statement_test.dart
index 54ba0aa..81f1950 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/invert_if_statement_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/invert_if_statement_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InvertIfStatementTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.INVERT_IF_STATEMENT;
 
-  test_blocks() async {
+  Future<void> test_blocks() async {
     await resolveTestUnit('''
 main() {
   if (true) {
@@ -40,7 +40,7 @@
 ''');
   }
 
-  test_statements() async {
+  Future<void> test_statements() async {
     await resolveTestUnit('''
 main() {
   if (true)
diff --git a/pkg/analysis_server/test/src/services/correction/assist/join_if_with_inner_test.dart b/pkg/analysis_server/test/src/services/correction/assist/join_if_with_inner_test.dart
index a57c603..ec1c3df 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/join_if_with_inner_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/join_if_with_inner_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(JoinInWithInnerTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.JOIN_IF_WITH_INNER;
 
-  test_conditionAndOr() async {
+  Future<void> test_conditionAndOr() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -38,7 +38,7 @@
 ''');
   }
 
-  test_conditionInvocation() async {
+  Future<void> test_conditionInvocation() async {
     await resolveTestUnit('''
 main() {
   if (isCheck()) {
@@ -59,7 +59,7 @@
 ''');
   }
 
-  test_conditionOrAnd() async {
+  Future<void> test_conditionOrAnd() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1 || 2 == 2) {
@@ -78,7 +78,7 @@
 ''');
   }
 
-  test_innerNotIf() async {
+  Future<void> test_innerNotIf() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -89,7 +89,7 @@
     await assertNoAssistAt('if (1 ==');
   }
 
-  test_innerWithElse() async {
+  Future<void> test_innerWithElse() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -104,7 +104,7 @@
     await assertNoAssistAt('if (1 ==');
   }
 
-  test_onCondition() async {
+  Future<void> test_onCondition() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -123,7 +123,7 @@
 ''');
   }
 
-  test_simpleConditions_block_block() async {
+  Future<void> test_simpleConditions_block_block() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -142,7 +142,7 @@
 ''');
   }
 
-  test_simpleConditions_block_single() async {
+  Future<void> test_simpleConditions_block_single() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -160,7 +160,7 @@
 ''');
   }
 
-  test_simpleConditions_single_blockMulti() async {
+  Future<void> test_simpleConditions_single_blockMulti() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -183,7 +183,7 @@
 ''');
   }
 
-  test_simpleConditions_single_blockOne() async {
+  Future<void> test_simpleConditions_single_blockOne() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1)
@@ -201,7 +201,7 @@
 ''');
   }
 
-  test_statementAfterInner() async {
+  Future<void> test_statementAfterInner() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -215,7 +215,7 @@
     await assertNoAssistAt('if (1 ==');
   }
 
-  test_statementBeforeInner() async {
+  Future<void> test_statementBeforeInner() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -229,7 +229,7 @@
     await assertNoAssistAt('if (1 ==');
   }
 
-  test_targetNotIf() async {
+  Future<void> test_targetNotIf() async {
     await resolveTestUnit('''
 main() {
   print(0);
@@ -238,7 +238,7 @@
     await assertNoAssistAt('print');
   }
 
-  test_targetWithElse() async {
+  Future<void> test_targetWithElse() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
diff --git a/pkg/analysis_server/test/src/services/correction/assist/join_if_with_outer_test.dart b/pkg/analysis_server/test/src/services/correction/assist/join_if_with_outer_test.dart
index ffbd3ab..79d87b5 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/join_if_with_outer_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/join_if_with_outer_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(JoinIfWithOuterTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.JOIN_IF_WITH_OUTER;
 
-  test_conditionAndOr() async {
+  Future<void> test_conditionAndOr() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -38,7 +38,7 @@
 ''');
   }
 
-  test_conditionInvocation() async {
+  Future<void> test_conditionInvocation() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -59,7 +59,7 @@
 ''');
   }
 
-  test_conditionOrAnd() async {
+  Future<void> test_conditionOrAnd() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1 || 2 == 2) {
@@ -78,7 +78,7 @@
 ''');
   }
 
-  test_onCondition() async {
+  Future<void> test_onCondition() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -97,7 +97,7 @@
 ''');
   }
 
-  test_outerNotIf() async {
+  Future<void> test_outerNotIf() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -108,7 +108,7 @@
     await assertNoAssistAt('if (1 == 1');
   }
 
-  test_outerWithElse() async {
+  Future<void> test_outerWithElse() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -123,7 +123,7 @@
     await assertNoAssistAt('if (2 == 2');
   }
 
-  test_simpleConditions_block_block() async {
+  Future<void> test_simpleConditions_block_block() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -142,7 +142,7 @@
 ''');
   }
 
-  test_simpleConditions_block_single() async {
+  Future<void> test_simpleConditions_block_single() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -160,7 +160,7 @@
 ''');
   }
 
-  test_simpleConditions_single_blockMulti() async {
+  Future<void> test_simpleConditions_single_blockMulti() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -183,7 +183,7 @@
 ''');
   }
 
-  test_simpleConditions_single_blockOne() async {
+  Future<void> test_simpleConditions_single_blockOne() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1)
@@ -201,7 +201,7 @@
 ''');
   }
 
-  test_statementAfterInner() async {
+  Future<void> test_statementAfterInner() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -215,7 +215,7 @@
     await assertNoAssistAt('if (2 == 2');
   }
 
-  test_statementBeforeInner() async {
+  Future<void> test_statementBeforeInner() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
@@ -229,7 +229,7 @@
     await assertNoAssistAt('if (2 == 2');
   }
 
-  test_targetNotIf() async {
+  Future<void> test_targetNotIf() async {
     await resolveTestUnit('''
 main() {
   print(0);
@@ -238,7 +238,7 @@
     await assertNoAssistAt('print');
   }
 
-  test_targetWithElse() async {
+  Future<void> test_targetWithElse() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1) {
diff --git a/pkg/analysis_server/test/src/services/correction/assist/join_variable_declaration_test.dart b/pkg/analysis_server/test/src/services/correction/assist/join_variable_declaration_test.dart
index 3216240..ac731da 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/join_variable_declaration_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/join_variable_declaration_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(JoinVariableDeclarationTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.JOIN_VARIABLE_DECLARATION;
 
-  test_onAssignment() async {
+  Future<void> test_onAssignment() async {
     await resolveTestUnit('''
 main() {
   var v;
@@ -33,7 +33,7 @@
 ''');
   }
 
-  test_onAssignment_hasInitializer() async {
+  Future<void> test_onAssignment_hasInitializer() async {
     await resolveTestUnit('''
 main() {
   var v = 1;
@@ -43,7 +43,7 @@
     await assertNoAssistAt('v = 2');
   }
 
-  test_onAssignment_notAdjacent() async {
+  Future<void> test_onAssignment_notAdjacent() async {
     await resolveTestUnit('''
 main() {
   var v;
@@ -54,7 +54,7 @@
     await assertNoAssistAt('v = 1');
   }
 
-  test_onAssignment_notAssignment() async {
+  Future<void> test_onAssignment_notAssignment() async {
     await resolveTestUnit('''
 main() {
   var v;
@@ -64,7 +64,7 @@
     await assertNoAssistAt('v += 1');
   }
 
-  test_onAssignment_notDeclaration() async {
+  Future<void> test_onAssignment_notDeclaration() async {
     await resolveTestUnit('''
 main(var v) {
   v = 1;
@@ -73,7 +73,7 @@
     await assertNoAssistAt('v = 1');
   }
 
-  test_onAssignment_notLeftArgument() async {
+  Future<void> test_onAssignment_notLeftArgument() async {
     await resolveTestUnit('''
 main() {
   var v;
@@ -83,7 +83,7 @@
     await assertNoAssistAt('v; // marker');
   }
 
-  test_onAssignment_notOneVariable() async {
+  Future<void> test_onAssignment_notOneVariable() async {
     await resolveTestUnit('''
 main() {
   var v, v2;
@@ -93,7 +93,7 @@
     await assertNoAssistAt('v = 1');
   }
 
-  test_onAssignment_notResolved() async {
+  Future<void> test_onAssignment_notResolved() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 main() {
@@ -104,7 +104,7 @@
     await assertNoAssistAt('x = 1');
   }
 
-  test_onAssignment_notSameBlock() async {
+  Future<void> test_onAssignment_notSameBlock() async {
     await resolveTestUnit('''
 main() {
   var v;
@@ -116,7 +116,7 @@
     await assertNoAssistAt('v = 1');
   }
 
-  test_onDeclaration_hasInitializer() async {
+  Future<void> test_onDeclaration_hasInitializer() async {
     await resolveTestUnit('''
 main() {
   var v = 1;
@@ -126,7 +126,7 @@
     await assertNoAssistAt('v = 1');
   }
 
-  test_onDeclaration_lastStatement() async {
+  Future<void> test_onDeclaration_lastStatement() async {
     await resolveTestUnit('''
 main() {
   if (true)
@@ -136,7 +136,7 @@
     await assertNoAssistAt('v;');
   }
 
-  test_onDeclaration_nextNotAssignmentExpression() async {
+  Future<void> test_onDeclaration_nextNotAssignmentExpression() async {
     await resolveTestUnit('''
 main() {
   var v;
@@ -146,7 +146,7 @@
     await assertNoAssistAt('v;');
   }
 
-  test_onDeclaration_nextNotExpressionStatement() async {
+  Future<void> test_onDeclaration_nextNotExpressionStatement() async {
     await resolveTestUnit('''
 main() {
   var v;
@@ -156,7 +156,7 @@
     await assertNoAssistAt('v;');
   }
 
-  test_onDeclaration_nextNotPureAssignment() async {
+  Future<void> test_onDeclaration_nextNotPureAssignment() async {
     await resolveTestUnit('''
 main() {
   var v;
@@ -166,7 +166,7 @@
     await assertNoAssistAt('v;');
   }
 
-  test_onDeclaration_notOneVariable() async {
+  Future<void> test_onDeclaration_notOneVariable() async {
     await resolveTestUnit('''
 main() {
   var v, v2;
@@ -176,7 +176,7 @@
     await assertNoAssistAt('v, ');
   }
 
-  test_onDeclaration_onName() async {
+  Future<void> test_onDeclaration_onName() async {
     await resolveTestUnit('''
 main() {
   var v;
@@ -190,7 +190,7 @@
 ''');
   }
 
-  test_onDeclaration_onType() async {
+  Future<void> test_onDeclaration_onType() async {
     await resolveTestUnit('''
 main() {
   int v;
@@ -204,7 +204,7 @@
 ''');
   }
 
-  test_onDeclaration_onVar() async {
+  Future<void> test_onDeclaration_onVar() async {
     await resolveTestUnit('''
 main() {
   var v;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/remove_type_annotation_test.dart b/pkg/analysis_server/test/src/services/correction/assist/remove_type_annotation_test.dart
index 869da1a..fd84462 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/remove_type_annotation_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/remove_type_annotation_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveTypeAnnotationTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.REMOVE_TYPE_ANNOTATION;
 
-  test_classField() async {
+  Future<void> test_classField() async {
     await resolveTestUnit('''
 class A {
   int v = 1;
@@ -32,7 +32,7 @@
 ''');
   }
 
-  test_classField_final() async {
+  Future<void> test_classField_final() async {
     await resolveTestUnit('''
 class A {
   final int v = 1;
@@ -45,7 +45,7 @@
 ''');
   }
 
-  test_field_noInitializer() async {
+  Future<void> test_field_noInitializer() async {
     await resolveTestUnit('''
 class A {
   int v;
@@ -54,7 +54,7 @@
     await assertNoAssistAt('v;');
   }
 
-  test_localVariable() async {
+  Future<void> test_localVariable() async {
     await resolveTestUnit('''
 main() {
   int a = 1, b = 2;
@@ -67,7 +67,7 @@
 ''');
   }
 
-  test_localVariable_const() async {
+  Future<void> test_localVariable_const() async {
     await resolveTestUnit('''
 main() {
   const int v = 1;
@@ -80,7 +80,7 @@
 ''');
   }
 
-  test_localVariable_final() async {
+  Future<void> test_localVariable_final() async {
     await resolveTestUnit('''
 main() {
   final int v = 1;
@@ -93,7 +93,7 @@
 ''');
   }
 
-  test_localVariable_noInitializer() async {
+  Future<void> test_localVariable_noInitializer() async {
     await resolveTestUnit('''
 main() {
   int v;
@@ -102,7 +102,7 @@
     await assertNoAssistAt('v;');
   }
 
-  test_localVariable_onInitializer() async {
+  Future<void> test_localVariable_onInitializer() async {
     await resolveTestUnit('''
 main() {
   final int v = 1;
@@ -111,7 +111,7 @@
     await assertNoAssistAt('1;');
   }
 
-  test_loopVariable() async {
+  Future<void> test_loopVariable() async {
     await resolveTestUnit('''
 main() {
   for(int i = 0; i < 3; i++) {}
@@ -124,7 +124,7 @@
 ''');
   }
 
-  test_loopVariable_noType() async {
+  Future<void> test_loopVariable_noType() async {
     await resolveTestUnit('''
 main() {
   for(var i = 0; i < 3; i++) {}
@@ -133,7 +133,7 @@
     await assertNoAssistAt('var ');
   }
 
-  test_topLevelVariable() async {
+  Future<void> test_topLevelVariable() async {
     await resolveTestUnit('''
 int V = 1;
 ''');
@@ -142,7 +142,7 @@
 ''');
   }
 
-  test_topLevelVariable_final() async {
+  Future<void> test_topLevelVariable_final() async {
     await resolveTestUnit('''
 final int V = 1;
 ''');
@@ -151,7 +151,7 @@
 ''');
   }
 
-  test_topLevelVariable_noInitializer() async {
+  Future<void> test_topLevelVariable_noInitializer() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 int v;
@@ -159,7 +159,7 @@
     await assertNoAssistAt('v;');
   }
 
-  test_topLevelVariable_syntheticName() async {
+  Future<void> test_topLevelVariable_syntheticName() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 MyType
diff --git a/pkg/analysis_server/test/src/services/correction/assist/replace_conditional_with_if_else_test.dart b/pkg/analysis_server/test/src/services/correction/assist/replace_conditional_with_if_else_test.dart
index 4ef97dd..2085f59 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/replace_conditional_with_if_else_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/replace_conditional_with_if_else_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceConditionalWithIfElseTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.REPLACE_CONDITIONAL_WITH_IF_ELSE;
 
-  test_assignment() async {
+  Future<void> test_assignment() async {
     await resolveTestUnit('''
 main() {
   var v;
@@ -50,14 +50,14 @@
 ''');
   }
 
-  test_noEnclosingStatement() async {
+  Future<void> test_noEnclosingStatement() async {
     await resolveTestUnit('''
 var v = true ? 111 : 222;
 ''');
     await assertNoAssistAt('? 111');
   }
 
-  test_notConditional() async {
+  Future<void> test_notConditional() async {
     await resolveTestUnit('''
 main() {
   var v = 42;
@@ -66,7 +66,7 @@
     await assertNoAssistAt('v = 42');
   }
 
-  test_return() async {
+  Future<void> test_return() async {
     await resolveTestUnit('''
 main() {
   return true ? 111 : 222;
@@ -83,7 +83,7 @@
 ''');
   }
 
-  test_variableDeclaration() async {
+  Future<void> test_variableDeclaration() async {
     await resolveTestUnit('''
 main() {
   int a = 1, vvv = true ? 111 : 222, b = 2;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/replace_if_else_with_conditional_test.dart b/pkg/analysis_server/test/src/services/correction/assist/replace_if_else_with_conditional_test.dart
index a21af08..d6139ed 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/replace_if_else_with_conditional_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/replace_if_else_with_conditional_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceIfElseWithConditionalTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.REPLACE_IF_ELSE_WITH_CONDITIONAL;
 
-  test_assignment() async {
+  Future<void> test_assignment() async {
     await resolveTestUnit('''
 main() {
   int vvv;
@@ -38,7 +38,7 @@
 ''');
   }
 
-  test_expressionVsReturn() async {
+  Future<void> test_expressionVsReturn() async {
     await resolveTestUnit('''
 main() {
   if (true) {
@@ -51,7 +51,7 @@
     await assertNoAssistAt('else');
   }
 
-  test_notIfStatement() async {
+  Future<void> test_notIfStatement() async {
     await resolveTestUnit('''
 main() {
   print(0);
@@ -60,7 +60,7 @@
     await assertNoAssistAt('print');
   }
 
-  test_notSingleStatement() async {
+  Future<void> test_notSingleStatement() async {
     await resolveTestUnit('''
 main() {
   int vvv;
@@ -76,7 +76,7 @@
     await assertNoAssistAt('if (true)');
   }
 
-  test_return() async {
+  Future<void> test_return() async {
     await resolveTestUnit('''
 main() {
   if (true) {
diff --git a/pkg/analysis_server/test/src/services/correction/assist/replace_with_var_test.dart b/pkg/analysis_server/test/src/services/correction/assist/replace_with_var_test.dart
index fc19a751..19eb57a 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/replace_with_var_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/replace_with_var_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceWithVarTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.REPLACE_WITH_VAR;
 
-  test_for() async {
+  Future<void> test_for() async {
     await resolveTestUnit('''
 void f(List<int> list) {
   for (/*caret*/int i = 0; i < list.length; i++) {
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_forEach() async {
+  Future<void> test_forEach() async {
     await resolveTestUnit('''
 void f(List<int> list) {
   for (/*caret*/int i in list) {
@@ -53,7 +53,7 @@
 ''');
   }
 
-  test_generic_instanceCreation_withArguments() async {
+  Future<void> test_generic_instanceCreation_withArguments() async {
     await resolveTestUnit('''
 C<int> f() {
   /*caret*/C<int> c = C<int>();
@@ -70,7 +70,7 @@
 ''');
   }
 
-  test_generic_instanceCreation_withoutArguments() async {
+  Future<void> test_generic_instanceCreation_withoutArguments() async {
     await resolveTestUnit('''
 C<int> f() {
   /*caret*/C<int> c = C();
@@ -87,7 +87,7 @@
 ''');
   }
 
-  test_generic_listLiteral() async {
+  Future<void> test_generic_listLiteral() async {
     await resolveTestUnit('''
 List f() {
   /*caret*/List<int> l = [];
@@ -102,7 +102,7 @@
 ''');
   }
 
-  test_generic_mapLiteral() async {
+  Future<void> test_generic_mapLiteral() async {
     await resolveTestUnit('''
 Map f() {
   /*caret*/Map<String, int> m = {};
@@ -117,7 +117,7 @@
 ''');
   }
 
-  test_generic_setLiteral() async {
+  Future<void> test_generic_setLiteral() async {
     await resolveTestUnit('''
 Set f() {
   /*caret*/Set<int> s = {};
@@ -132,7 +132,7 @@
 ''');
   }
 
-  test_generic_setLiteral_ambiguous() async {
+  Future<void> test_generic_setLiteral_ambiguous() async {
     await resolveTestUnit('''
 Set f() {
   /*caret*/Set s = {};
@@ -142,7 +142,7 @@
     await assertNoAssist();
   }
 
-  test_moreGeneral() async {
+  Future<void> test_moreGeneral() async {
     await resolveTestUnit('''
 num f() {
   /*caret*/num n = 0;
@@ -152,7 +152,7 @@
     await assertNoAssist();
   }
 
-  test_noInitializer() async {
+  Future<void> test_noInitializer() async {
     await resolveTestUnit('''
 String f() {
   /*caret*/String s;
@@ -163,7 +163,7 @@
     await assertNoAssist();
   }
 
-  test_noType() async {
+  Future<void> test_noType() async {
     await resolveTestUnit('''
 String f() {
   /*caret*/var s = '';
@@ -173,7 +173,7 @@
     await assertNoAssist();
   }
 
-  test_simple() async {
+  Future<void> test_simple() async {
     await resolveTestUnit('''
 String f() {
   /*caret*/String s = '';
diff --git a/pkg/analysis_server/test/src/services/correction/assist/sort_child_property_last_test.dart b/pkg/analysis_server/test/src/services/correction/assist/sort_child_property_last_test.dart
index 43725ad..9335cd1 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/sort_child_property_last_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/sort_child_property_last_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SortChildPropertyLastTest);
   });
@@ -20,7 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.SORT_CHILD_PROPERTY_LAST;
 
-  test_already_sorted() async {
+  Future<void> test_already_sorted() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -38,7 +38,7 @@
     await assertNoAssist();
   }
 
-  test_already_sorted_one_prop() async {
+  Future<void> test_already_sorted_one_prop() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -55,7 +55,7 @@
     await assertNoAssist();
   }
 
-  test_no_children() async {
+  Future<void> test_no_children() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -68,7 +68,7 @@
     await assertNoAssist();
   }
 
-  test_sort() async {
+  Future<void> test_sort() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -99,7 +99,7 @@
     assertExitPosition(after: '],');
   }
 
-  test_sort_noAssistWithLint() async {
+  Future<void> test_sort_noAssistWithLint() async {
     addFlutterPackage();
     createAnalysisOptionsFile(lints: [LintNames.sort_child_properties_last]);
     verifyNoTestUnitErrors = false;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/split_and_condition_test.dart b/pkg/analysis_server/test/src/services/correction/assist/split_and_condition_test.dart
index 31127f0..4371672 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/split_and_condition_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/split_and_condition_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SplitAndConditionTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SPLIT_AND_CONDITION;
 
-  test_hasElse() async {
+  Future<void> test_hasElse() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1 && 2 == 2) {
@@ -32,7 +32,7 @@
     await assertNoAssistAt('&& 2');
   }
 
-  test_innerAndExpression() async {
+  Future<void> test_innerAndExpression() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1 && 2 == 2 && 3 == 3) {
@@ -51,7 +51,7 @@
 ''');
   }
 
-  test_notAnd() async {
+  Future<void> test_notAnd() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1 || 2 == 2) {
@@ -62,7 +62,7 @@
     await assertNoAssistAt('|| 2');
   }
 
-  test_notOnOperator() async {
+  Future<void> test_notOnOperator() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1 && 2 == 2) {
@@ -74,7 +74,7 @@
     await assertNoAssistAt('main() {');
   }
 
-  test_notPartOfIf() async {
+  Future<void> test_notPartOfIf() async {
     await resolveTestUnit('''
 main() {
   print(1 == 1 && 2 == 2);
@@ -83,7 +83,7 @@
     await assertNoAssistAt('&& 2');
   }
 
-  test_notTopLevelAnd() async {
+  Future<void> test_notTopLevelAnd() async {
     await resolveTestUnit('''
 main() {
   if (true || (1 == 1 && 2 == 2)) {
@@ -98,7 +98,7 @@
     await assertNoAssistAt('&& 4');
   }
 
-  test_selectionTooLarge() async {
+  Future<void> test_selectionTooLarge() async {
     await resolveTestUnit('''
 main() {
   if (1 == 1
@@ -115,7 +115,7 @@
     await assertNoAssist();
   }
 
-  test_thenBlock() async {
+  Future<void> test_thenBlock() async {
     await resolveTestUnit('''
 main() {
   if (true && false) {
@@ -140,7 +140,7 @@
 ''');
   }
 
-  test_thenStatement() async {
+  Future<void> test_thenStatement() async {
     await resolveTestUnit('''
 main() {
   if (true && false)
diff --git a/pkg/analysis_server/test/src/services/correction/assist/split_variable_declaration_test.dart b/pkg/analysis_server/test/src/services/correction/assist/split_variable_declaration_test.dart
index aed39c3..07d4997 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/split_variable_declaration_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/split_variable_declaration_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SplitVariableDeclarationTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SPLIT_VARIABLE_DECLARATION;
 
-  test_const() async {
+  Future<void> test_const() async {
     await resolveTestUnit('''
 main() {
   const v = 1;
@@ -28,7 +28,7 @@
     await assertNoAssistAt('v = 1');
   }
 
-  test_final() async {
+  Future<void> test_final() async {
     await resolveTestUnit('''
 main() {
   final v = 1;
@@ -37,7 +37,7 @@
     await assertNoAssistAt('v = 1');
   }
 
-  test_notOneVariable() async {
+  Future<void> test_notOneVariable() async {
     await resolveTestUnit('''
 main() {
   var v = 1, v2;
@@ -46,7 +46,7 @@
     await assertNoAssistAt('v = 1');
   }
 
-  test_onName() async {
+  Future<void> test_onName() async {
     await resolveTestUnit('''
 main() {
   var v = 1;
@@ -60,7 +60,23 @@
 ''');
   }
 
-  test_onType() async {
+  Future<void> test_onName_functionStatement_noType() async {
+    await resolveTestUnit('''
+f() => 1;
+main() {
+  var v = f();
+}
+''');
+    await assertHasAssistAt('v =', '''
+f() => 1;
+main() {
+  var v;
+  v = f();
+}
+''');
+  }
+
+  Future<void> test_onType() async {
     await resolveTestUnit('''
 main() {
   int v = 1;
@@ -75,7 +91,7 @@
   }
 
   @failingTest
-  test_onType_prefixedByComment() async {
+  Future<void> test_onType_prefixedByComment() async {
     await resolveTestUnit('''
 main() {
   /*comment*/int v = 1;
@@ -89,7 +105,7 @@
 ''');
   }
 
-  test_onVar() async {
+  Future<void> test_onVar() async {
     await resolveTestUnit('''
 main() {
   var v = 1;
diff --git a/pkg/analysis_server/test/src/services/correction/assist/surround_with_block_test.dart b/pkg/analysis_server/test/src/services/correction/assist/surround_with_block_test.dart
index 365995d..3d35b43 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/surround_with_block_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/surround_with_block_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SurroundWithBlockTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SURROUND_WITH_BLOCK;
 
-  test_notStatementInBlock() async {
+  Future<void> test_notStatementInBlock() async {
     await resolveTestUnit('''
 main() {
   while (true)
@@ -31,7 +31,7 @@
     await assertNoAssist();
   }
 
-  test_twoStatements() async {
+  Future<void> test_twoStatements() async {
     await resolveTestUnit('''
 main() {
 // start
diff --git a/pkg/analysis_server/test/src/services/correction/assist/surround_with_do_while_test.dart b/pkg/analysis_server/test/src/services/correction/assist/surround_with_do_while_test.dart
index 56d81c3..3a1f308 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/surround_with_do_while_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/surround_with_do_while_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SurroundWithDoWhileTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SURROUND_WITH_DO_WHILE;
 
-  test_twoStatements() async {
+  Future<void> test_twoStatements() async {
     await resolveTestUnit('''
 main() {
 // start
diff --git a/pkg/analysis_server/test/src/services/correction/assist/surround_with_for_in_test.dart b/pkg/analysis_server/test/src/services/correction/assist/surround_with_for_in_test.dart
index 6427730..0dd79ed 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/surround_with_for_in_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/surround_with_for_in_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SurroundWithForInTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SURROUND_WITH_FOR_IN;
 
-  test_twoStatements() async {
+  Future<void> test_twoStatements() async {
     await resolveTestUnit('''
 main() {
 // start
diff --git a/pkg/analysis_server/test/src/services/correction/assist/surround_with_for_test.dart b/pkg/analysis_server/test/src/services/correction/assist/surround_with_for_test.dart
index 095f0ed..d946e3b 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/surround_with_for_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/surround_with_for_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SurroundWithForTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SURROUND_WITH_FOR;
 
-  test_twoStatements() async {
+  Future<void> test_twoStatements() async {
     await resolveTestUnit('''
 main() {
 // start
diff --git a/pkg/analysis_server/test/src/services/correction/assist/surround_with_if_test.dart b/pkg/analysis_server/test/src/services/correction/assist/surround_with_if_test.dart
index 5780cfa..288aae5 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/surround_with_if_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/surround_with_if_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SurroundWithIfTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SURROUND_WITH_IF;
 
-  test_twoStatements() async {
+  Future<void> test_twoStatements() async {
     await resolveTestUnit('''
 main() {
 // start
diff --git a/pkg/analysis_server/test/src/services/correction/assist/surround_with_try_catch_test.dart b/pkg/analysis_server/test/src/services/correction/assist/surround_with_try_catch_test.dart
index bf806e9..2b3121d 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/surround_with_try_catch_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/surround_with_try_catch_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SurroundWithTryCatchTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SURROUND_WITH_TRY_CATCH;
 
-  test_twoStatements() async {
+  Future<void> test_twoStatements() async {
     await resolveTestUnit('''
 main() {
 // start
diff --git a/pkg/analysis_server/test/src/services/correction/assist/surround_with_try_finally_test.dart b/pkg/analysis_server/test/src/services/correction/assist/surround_with_try_finally_test.dart
index 8527cd7..dc9a109 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/surround_with_try_finally_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/surround_with_try_finally_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SurroundWithTryFinallyTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SURROUND_WITH_TRY_FINALLY;
 
-  test_twoStatements() async {
+  Future<void> test_twoStatements() async {
     await resolveTestUnit('''
 main() {
 // start
diff --git a/pkg/analysis_server/test/src/services/correction/assist/surround_with_while_test.dart b/pkg/analysis_server/test/src/services/correction/assist/surround_with_while_test.dart
index 38f0beb..42502fe 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/surround_with_while_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/surround_with_while_test.dart
@@ -8,7 +8,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SurroundWithWhileTest);
   });
@@ -19,7 +19,7 @@
   @override
   AssistKind get kind => DartAssistKind.SURROUND_WITH_WHILE;
 
-  test_twoStatements() async {
+  Future<void> test_twoStatements() async {
     await resolveTestUnit('''
 main() {
 // start
diff --git a/pkg/analysis_server/test/src/services/correction/assist/test_all.dart b/pkg/analysis_server/test/src/services/correction/assist/test_all.dart
index 645dc53..2a1f7e2 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/test_all.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/test_all.dart
@@ -85,7 +85,7 @@
 import 'surround_with_while_test.dart' as surround_with_while;
 import 'use_curly_braces_test.dart' as use_curly_braces;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     add_diagnostic_property.main();
     add_not_null_assert.main();
diff --git a/pkg/analysis_server/test/src/services/correction/assist/use_curly_braces_test.dart b/pkg/analysis_server/test/src/services/correction/assist/use_curly_braces_test.dart
index 650dfd0..032f5ee 100644
--- a/pkg/analysis_server/test/src/services/correction/assist/use_curly_braces_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/assist/use_curly_braces_test.dart
@@ -9,7 +9,7 @@
 
 import 'assist_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UseCurlyBracesTest);
   });
@@ -20,7 +20,7 @@
   @override
   AssistKind get kind => DartAssistKind.USE_CURLY_BRACES;
 
-  test_do_block() async {
+  Future<void> test_do_block() async {
     await resolveTestUnit('''
 main() {
   /*caret*/do {
@@ -31,7 +31,7 @@
     await assertNoAssist();
   }
 
-  test_do_body_middle() async {
+  Future<void> test_do_body_middle() async {
     await resolveTestUnit('''
 main() {
   do print/*caret*/(0); while (true);
@@ -46,7 +46,7 @@
 ''');
   }
 
-  test_do_body_start() async {
+  Future<void> test_do_body_start() async {
     await resolveTestUnit('''
 main() {
   do /*caret*/print(0); while (true);
@@ -61,7 +61,7 @@
 ''');
   }
 
-  test_do_condition() async {
+  Future<void> test_do_condition() async {
     await resolveTestUnit('''
 main() {
   do print(0); while (/*caret*/true);
@@ -76,7 +76,7 @@
 ''');
   }
 
-  test_do_end() async {
+  Future<void> test_do_end() async {
     await resolveTestUnit('''
 main() {
   do print(0); while (true);/*caret*/
@@ -91,7 +91,7 @@
 ''');
   }
 
-  test_do_keyword_do() async {
+  Future<void> test_do_keyword_do() async {
     await resolveTestUnit('''
 main() {
   /*caret*/do print(0); while (true);
@@ -106,7 +106,7 @@
 ''');
   }
 
-  test_do_keyword_while() async {
+  Future<void> test_do_keyword_while() async {
     await resolveTestUnit('''
 main() {
   do print(0); /*caret*/while (true);
@@ -121,7 +121,7 @@
 ''');
   }
 
-  test_for_body_end() async {
+  Future<void> test_for_body_end() async {
     await resolveTestUnit('''
 main() {
   for (;;) print(0);/*caret*/
@@ -136,7 +136,7 @@
 ''');
   }
 
-  test_for_body_middle() async {
+  Future<void> test_for_body_middle() async {
     await resolveTestUnit('''
 main() {
   for (;;) print/*caret*/(0);
@@ -151,7 +151,7 @@
 ''');
   }
 
-  test_for_body_start() async {
+  Future<void> test_for_body_start() async {
     await resolveTestUnit('''
 main() {
   for (;;) /*caret*/print(0);
@@ -166,7 +166,7 @@
 ''');
   }
 
-  test_for_condition() async {
+  Future<void> test_for_condition() async {
     await resolveTestUnit('''
 main() {
   for (/*caret*/;;) print(0);
@@ -181,7 +181,7 @@
 ''');
   }
 
-  test_for_keyword() async {
+  Future<void> test_for_keyword() async {
     await resolveTestUnit('''
 main() {
   /*caret*/for (;;) print(0);
@@ -196,7 +196,7 @@
 ''');
   }
 
-  test_for_keyword_block() async {
+  Future<void> test_for_keyword_block() async {
     await resolveTestUnit('''
 main() {
   /*caret*/for (;;) {
@@ -207,7 +207,7 @@
     await assertNoAssist();
   }
 
-  test_if_else_keyword() async {
+  Future<void> test_if_else_keyword() async {
     await resolveTestUnit('''
 main(int a) {
   if (a == 0)
@@ -226,7 +226,7 @@
 ''');
   }
 
-  test_if_else_statement() async {
+  Future<void> test_if_else_statement() async {
     await resolveTestUnit('''
 main(int a) {
   if (a == 0)
@@ -245,7 +245,7 @@
 ''');
   }
 
-  test_if_keyword_blockBoth() async {
+  Future<void> test_if_keyword_blockBoth() async {
     await resolveTestUnit('''
 main(int a) {
   /*caret*/if (a == 0) {
@@ -258,7 +258,7 @@
     await assertNoAssist();
   }
 
-  test_if_keyword_blockElse() async {
+  Future<void> test_if_keyword_blockElse() async {
     await resolveTestUnit('''
 main(int a) {
   /*caret*/if (a == 0) print(0);
@@ -278,7 +278,7 @@
 ''');
   }
 
-  test_if_keyword_blockThen() async {
+  Future<void> test_if_keyword_blockThen() async {
     await resolveTestUnit('''
 main(int a) {
   /*caret*/if (a == 0) {
@@ -289,7 +289,7 @@
     await assertNoAssist();
   }
 
-  test_if_keyword_withElse() async {
+  Future<void> test_if_keyword_withElse() async {
     await resolveTestUnit('''
 main(int a) {
   /*caret*/if (a == 0)
@@ -308,7 +308,7 @@
 ''');
   }
 
-  test_if_keyword_withoutElse() async {
+  Future<void> test_if_keyword_withoutElse() async {
     await resolveTestUnit('''
 main(int a) {
   /*caret*/if (a == 0)
@@ -324,7 +324,7 @@
 ''');
   }
 
-  test_if_then_withElse() async {
+  Future<void> test_if_then_withElse() async {
     await resolveTestUnit('''
 main(int a) {
   if (a == 0)
@@ -341,7 +341,7 @@
 ''');
   }
 
-  test_if_then_withoutElse() async {
+  Future<void> test_if_then_withoutElse() async {
     await resolveTestUnit('''
 main(int a) {
   if (a == 0) /*caret*/print(0);
@@ -356,7 +356,7 @@
 ''');
   }
 
-  test_noAssistWithLint() async {
+  Future<void> test_noAssistWithLint() async {
     createAnalysisOptionsFile(
         lints: [LintNames.curly_braces_in_flow_control_structures]);
     verifyNoTestUnitErrors = false;
@@ -368,7 +368,7 @@
     await assertNoAssist();
   }
 
-  test_while_body_end() async {
+  Future<void> test_while_body_end() async {
     await resolveTestUnit('''
 main() {
   while (true) print(0);/*caret*/
@@ -383,7 +383,7 @@
 ''');
   }
 
-  test_while_body_middle() async {
+  Future<void> test_while_body_middle() async {
     await resolveTestUnit('''
 main() {
   while (true) print/*caret*/(0);
@@ -398,7 +398,7 @@
 ''');
   }
 
-  test_while_body_start() async {
+  Future<void> test_while_body_start() async {
     await resolveTestUnit('''
 main() {
   while (true) /*caret*/print(0);
@@ -413,7 +413,7 @@
 ''');
   }
 
-  test_while_condition() async {
+  Future<void> test_while_condition() async {
     await resolveTestUnit('''
 main() {
   while (/*caret*/true) print(0);
@@ -428,7 +428,7 @@
 ''');
   }
 
-  test_while_keyword() async {
+  Future<void> test_while_keyword() async {
     await resolveTestUnit('''
 main() {
   /*caret*/while (true) print(0);
@@ -443,7 +443,7 @@
 ''');
   }
 
-  test_while_keyword_block() async {
+  Future<void> test_while_keyword_block() async {
     await resolveTestUnit('''
 main() {
   /*caret*/while (true) {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_async_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_async_test.dart
index ec2d413..2dcde2c 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_async_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_async_test.dart
@@ -10,7 +10,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddAsyncTest);
   });
@@ -21,7 +21,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_ASYNC;
 
-  test_asyncFor() async {
+  Future<void> test_asyncFor() async {
     await resolveTestUnit('''
 import 'dart:async';
 void main(Stream<String> names) {
@@ -40,7 +40,7 @@
 ''');
   }
 
-  test_blockFunctionBody_function() async {
+  Future<void> test_blockFunctionBody_function() async {
     await resolveTestUnit('''
 foo() {}
 main() {
@@ -55,7 +55,7 @@
 ''');
   }
 
-  test_blockFunctionBody_getter() async {
+  Future<void> test_blockFunctionBody_getter() async {
     await resolveTestUnit('''
 int get foo => null;
 int f() {
@@ -74,7 +74,7 @@
     });
   }
 
-  test_closure() async {
+  Future<void> test_closure() async {
     await resolveTestUnit('''
 import 'dart:async';
 
@@ -93,7 +93,7 @@
     });
   }
 
-  test_expressionFunctionBody() async {
+  Future<void> test_expressionFunctionBody() async {
     await resolveTestUnit('''
 foo() {}
 main() => await foo();
@@ -104,14 +104,14 @@
 ''');
   }
 
-  test_nullFunctionBody() async {
+  Future<void> test_nullFunctionBody() async {
     await resolveTestUnit('''
 var F = await;
 ''');
     await assertNoFix();
   }
 
-  test_returnFuture_alreadyFuture() async {
+  Future<void> test_returnFuture_alreadyFuture() async {
     await resolveTestUnit('''
 import 'dart:async';
 foo() {}
@@ -132,7 +132,7 @@
     });
   }
 
-  test_returnFuture_dynamic() async {
+  Future<void> test_returnFuture_dynamic() async {
     await resolveTestUnit('''
 foo() {}
 dynamic main() {
@@ -149,7 +149,7 @@
 ''');
   }
 
-  test_returnFuture_nonFuture() async {
+  Future<void> test_returnFuture_nonFuture() async {
     await resolveTestUnit('''
 foo() {}
 int main() {
@@ -166,7 +166,7 @@
 ''');
   }
 
-  test_returnFuture_noType() async {
+  Future<void> test_returnFuture_noType() async {
     await resolveTestUnit('''
 foo() {}
 main() {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_await_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_await_test.dart
index f48d85d..f075f8f 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_await_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_await_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddAwaitTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.unawaited_futures;
 
-  test_intLiteral() async {
+  Future<void> test_intLiteral() async {
     await resolveTestUnit('''
 Future doSomething() => new Future();
 
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_const_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_const_test.dart
index 8a8ca02..189e3a8 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_const_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_const_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddConstTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_const_constructors;
 
-  test_basic() async {
+  Future<void> test_basic() async {
     await resolveTestUnit('''
 class C {
   const C();
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_not_present() async {
+  Future<void> test_not_present() async {
     await resolveTestUnit('''
 class C {
   const C();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_curly_braces_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_curly_braces_test.dart
index ae04af5..267ee17 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_curly_braces_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_curly_braces_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddCurlyBracesTest);
   });
@@ -24,7 +24,7 @@
   String get lintCode => LintNames.curly_braces_in_flow_control_structures;
 
   // More coverage in the `use_curly_braces_test.dart` assist test.
-  test_do_block() async {
+  Future<void> test_do_block() async {
     await resolveTestUnit('''
 main() {
   do /*LINT*/print(0); while (true);
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_diagnostic_property_reference_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_diagnostic_property_reference_test.dart
index d737fee..ac5dd64 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_diagnostic_property_reference_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_diagnostic_property_reference_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddDiagnosticPropertyReferenceTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.diagnostic_describe_all_properties;
 
-  test_boolField_debugFillProperties() async {
+  Future<void> test_boolField_debugFillProperties() async {
     await resolveTestUnit('''
 class Absorber extends Widget {
   bool get absorbing => _absorbing;
@@ -51,7 +51,7 @@
 ''');
   }
 
-  test_boolField_debugFillProperties_empty() async {
+  Future<void> test_boolField_debugFillProperties_empty() async {
     await resolveTestUnit('''
 class Absorber extends Widget {
   bool /*LINT*/ignoringSemantics;
@@ -71,7 +71,8 @@
 ''');
   }
 
-  test_boolField_debugFillProperties_empty_customParamName() async {
+  Future<void>
+      test_boolField_debugFillProperties_empty_customParamName() async {
     await resolveTestUnit('''
 class Absorber extends Widget {
   bool /*LINT*/ignoringSemantics;
@@ -91,7 +92,7 @@
 ''');
   }
 
-  test_boolGetter_debugFillProperties() async {
+  Future<void> test_boolGetter_debugFillProperties() async {
     await resolveTestUnit('''
 class Absorber extends Widget {
   bool get /*LINT*/absorbing => _absorbing;
@@ -115,7 +116,7 @@
 ''');
   }
 
-  test_colorField_debugFillProperties() async {
+  Future<void> test_colorField_debugFillProperties() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -140,7 +141,7 @@
 ''');
   }
 
-  test_doubleField_debugFillProperties() async {
+  Future<void> test_doubleField_debugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   double /*LINT*/field;
@@ -162,7 +163,7 @@
 ''');
   }
 
-  test_dynamicField_debugFillProperties() async {
+  Future<void> test_dynamicField_debugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   dynamic /*LINT*/field;
@@ -184,7 +185,7 @@
 ''');
   }
 
-  test_enumField_debugFillProperties() async {
+  Future<void> test_enumField_debugFillProperties() async {
     await resolveTestUnit('''
 enum Foo {bar}
 class A extends Widget {
@@ -208,7 +209,7 @@
 ''');
   }
 
-  test_functionField_debugFillProperties() async {
+  Future<void> test_functionField_debugFillProperties() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -239,7 +240,7 @@
 ''');
   }
 
-  test_intField_debugFillProperties() async {
+  Future<void> test_intField_debugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   int /*LINT*/field;
@@ -261,7 +262,7 @@
 ''');
   }
 
-  test_iterableField_debugFillProperties() async {
+  Future<void> test_iterableField_debugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   Iterable<String> /*LINT*/field;
@@ -283,7 +284,7 @@
 ''');
   }
 
-  test_listField_debugFillProperties() async {
+  Future<void> test_listField_debugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   List<List<String>> /*LINT*/field;
@@ -305,7 +306,7 @@
 ''');
   }
 
-  test_matrix4Field_debugFillProperties() async {
+  Future<void> test_matrix4Field_debugFillProperties() async {
     addVectorMathPackage();
     await resolveTestUnit('''
 import 'package:vector_math/vector_math_64.dart';
@@ -330,7 +331,7 @@
 ''');
   }
 
-  test_objectField_debugFillProperties() async {
+  Future<void> test_objectField_debugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   Object /*LINT*/field;
@@ -352,7 +353,7 @@
 ''');
   }
 
-  test_stringField_debugFillProperties() async {
+  Future<void> test_stringField_debugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   String /*LINT*/field;
@@ -374,7 +375,7 @@
 ''');
   }
 
-  test_stringField_noDebugFillProperties() async {
+  Future<void> test_stringField_noDebugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   String /*LINT*/field;
@@ -392,7 +393,7 @@
 ''');
   }
 
-  test_typeOutOfScopeField_debugFillProperties() async {
+  Future<void> test_typeOutOfScopeField_debugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   ClassNotInScope<bool> /*LINT*/onChanged;
@@ -416,7 +417,7 @@
 ''');
   }
 
-  test_typeOutOfScopeGetter_debugFillProperties() async {
+  Future<void> test_typeOutOfScopeGetter_debugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   ClassNotInScope<bool> get /*LINT*/onChanged => null;
@@ -440,7 +441,7 @@
 ''');
   }
 
-  test_varField_debugFillProperties() async {
+  Future<void> test_varField_debugFillProperties() async {
     await resolveTestUnit('''
 class A extends Widget {
   var /*LINT*/field;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_explicit_cast_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_explicit_cast_test.dart
index e0ff288..436ea7e 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_explicit_cast_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_explicit_cast_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddExplicitCastTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_EXPLICIT_CAST;
 
-  test_as() async {
+  Future<void> test_as() async {
     await resolveTestUnit('''
 f(A a) {
   C c = a as B;
@@ -33,7 +33,7 @@
     await assertNoFix();
   }
 
-  test_assignment_general() async {
+  Future<void> test_assignment_general() async {
     await resolveTestUnit('''
 f(A a) {
   B b;
@@ -54,7 +54,7 @@
 ''');
   }
 
-  test_assignment_general_all() async {
+  Future<void> test_assignment_general_all() async {
     await resolveTestUnit('''
 f(A a) {
   B b, b2;
@@ -75,7 +75,7 @@
 ''');
   }
 
-  test_assignment_list() async {
+  Future<void> test_assignment_list() async {
     await resolveTestUnit('''
 f(List<A> a) {
   List<B> b;
@@ -96,7 +96,7 @@
 ''');
   }
 
-  test_assignment_list_all() async {
+  Future<void> test_assignment_list_all() async {
     await resolveTestUnit('''
 f(List<A> a) {
   List<B> b, b2;
@@ -117,7 +117,7 @@
 ''');
   }
 
-  test_assignment_map() async {
+  Future<void> test_assignment_map() async {
     await resolveTestUnit('''
 f(Map<A, B> a) {
   Map<B, A> b;
@@ -138,7 +138,7 @@
 ''');
   }
 
-  test_assignment_map_all() async {
+  Future<void> test_assignment_map_all() async {
     await resolveTestUnit('''
 f(Map<A, B> a) {
   Map<B, A> b, b2;
@@ -159,7 +159,7 @@
 ''');
   }
 
-  test_assignment_needsParens() async {
+  Future<void> test_assignment_needsParens() async {
     await resolveTestUnit('''
 f(A a) {
   B b;
@@ -184,7 +184,7 @@
 ''');
   }
 
-  test_assignment_needsParens_all() async {
+  Future<void> test_assignment_needsParens_all() async {
     await resolveTestUnit('''
 f(A a) {
   B b, b2;
@@ -209,7 +209,7 @@
 ''');
   }
 
-  test_assignment_set() async {
+  Future<void> test_assignment_set() async {
     await resolveTestUnit('''
 f(Set<A> a) {
   Set<B> b;
@@ -230,7 +230,7 @@
 ''');
   }
 
-  test_assignment_set_all() async {
+  Future<void> test_assignment_set_all() async {
     await resolveTestUnit('''
 f(Set<A> a) {
   Set<B> b, b2;
@@ -251,7 +251,7 @@
 ''');
   }
 
-  test_cast() async {
+  Future<void> test_cast() async {
     await resolveTestUnit('''
 f(List<A> a) {
   List<B> b = a.cast<A>();
@@ -263,7 +263,7 @@
     await assertNoFix();
   }
 
-  test_declaration_general() async {
+  Future<void> test_declaration_general() async {
     await resolveTestUnit('''
 f(A a) {
   B b = a;
@@ -282,7 +282,7 @@
 ''');
   }
 
-  test_declaration_general_all() async {
+  Future<void> test_declaration_general_all() async {
     await resolveTestUnit('''
 f(A a) {
   B b = a;
@@ -301,7 +301,7 @@
 ''');
   }
 
-  test_declaration_list() async {
+  Future<void> test_declaration_list() async {
     await resolveTestUnit('''
 f(List<A> a) {
   List<B> b = a.where((e) => e is B).toList();
@@ -320,7 +320,7 @@
 ''');
   }
 
-  test_declaration_list_all() async {
+  Future<void> test_declaration_list_all() async {
     await resolveTestUnit('''
 f(List<A> a) {
   List<B> b = a.where((e) => e is B).toList();
@@ -339,7 +339,7 @@
 ''');
   }
 
-  test_declaration_map() async {
+  Future<void> test_declaration_map() async {
     await resolveTestUnit('''
 f(Map<A, B> a) {
   Map<B, A> b = a;
@@ -358,7 +358,7 @@
 ''');
   }
 
-  test_declaration_map_all() async {
+  Future<void> test_declaration_map_all() async {
     await resolveTestUnit('''
 f(Map<A, B> a) {
   Map<B, A> b = a;
@@ -377,7 +377,7 @@
 ''');
   }
 
-  test_declaration_needsParens() async {
+  Future<void> test_declaration_needsParens() async {
     await resolveTestUnit('''
 f(A a) {
   B b = a..m();
@@ -400,7 +400,7 @@
 ''');
   }
 
-  test_declaration_needsParens_all() async {
+  Future<void> test_declaration_needsParens_all() async {
     await resolveTestUnit('''
 f(A a) {
   B b = a..m();
@@ -423,7 +423,7 @@
 ''');
   }
 
-  test_declaration_set() async {
+  Future<void> test_declaration_set() async {
     await resolveTestUnit('''
 f(Set<A> a) {
   Set<B> b = a;
@@ -442,7 +442,7 @@
 ''');
   }
 
-  test_declaration_set_all() async {
+  Future<void> test_declaration_set_all() async {
     await resolveTestUnit('''
 f(Set<A> a) {
   Set<B> b = a;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_field_formal_parameters_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_field_formal_parameters_test.dart
index 172aee9..61a6718 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_field_formal_parameters_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_field_formal_parameters_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddFieldFormalParametersTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_FIELD_FORMAL_PARAMETERS;
 
-  test_flutter() async {
+  Future<void> test_flutter() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -45,7 +45,7 @@
 ''');
   }
 
-  test_hasRequiredParameter() async {
+  Future<void> test_hasRequiredParameter() async {
     await resolveTestUnit('''
 class Test {
   final int a;
@@ -64,7 +64,7 @@
 ''');
   }
 
-  test_noParameters() async {
+  Future<void> test_noParameters() async {
     await resolveTestUnit('''
 class Test {
   final int a;
@@ -83,7 +83,7 @@
 ''');
   }
 
-  test_noRequiredParameter() async {
+  Future<void> test_noRequiredParameter() async {
     await resolveTestUnit('''
 class Test {
   final int a;
@@ -102,7 +102,7 @@
 ''');
   }
 
-  test_notAllFinal() async {
+  Future<void> test_notAllFinal() async {
     await resolveTestUnit('''
 class Test {
   final int a;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_missing_enum_case_clauses_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_missing_enum_case_clauses_test.dart
index f796f39..ee1c619 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_missing_enum_case_clauses_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_missing_enum_case_clauses_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddMissingEnumCaseClausesTest);
   });
@@ -33,7 +33,7 @@
     });
   }
 
-  test_empty() async {
+  Future<void> test_empty() async {
     await resolveTestUnit('''
 enum E {a, b, c}
 void f(E e) {
@@ -59,7 +59,7 @@
 ''');
   }
 
-  test_nonEmpty() async {
+  Future<void> test_nonEmpty() async {
     await resolveTestUnit('''
 enum E {a, b, c}
 void f(E e) {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_named_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_named_test.dart
index 0378f7e..eee9f5c 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_named_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_named_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddMissingParameterNamedTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_MISSING_PARAMETER_NAMED;
 
-  test_constructor_hasNamed() async {
+  Future<void> test_constructor_hasNamed() async {
     await resolveTestUnit('''
 class A {
   A(int a, {int b}) {}
@@ -40,7 +40,7 @@
 ''');
   }
 
-  test_constructor_hasRequired() async {
+  Future<void> test_constructor_hasRequired() async {
     await resolveTestUnit('''
 class A {
   A(int a) {}
@@ -61,7 +61,7 @@
 ''');
   }
 
-  test_constructor_noParameters() async {
+  Future<void> test_constructor_noParameters() async {
     await resolveTestUnit('''
 class A {
   A() {}
@@ -82,7 +82,7 @@
 ''');
   }
 
-  test_constructor_noParameters_named() async {
+  Future<void> test_constructor_noParameters_named() async {
     await resolveTestUnit('''
 class A {
   A.aaa() {}
@@ -103,7 +103,7 @@
 ''');
   }
 
-  test_function_hasNamed() async {
+  Future<void> test_function_hasNamed() async {
     await resolveTestUnit('''
 test(int a, {int b: 0}) {}
 
@@ -120,7 +120,7 @@
 ''');
   }
 
-  test_function_hasRequired() async {
+  Future<void> test_function_hasRequired() async {
     await resolveTestUnit('''
 test(int a) {}
 
@@ -137,7 +137,7 @@
 ''');
   }
 
-  test_function_noParameters() async {
+  Future<void> test_function_noParameters() async {
     await resolveTestUnit('''
 test() {}
 
@@ -154,7 +154,7 @@
 ''');
   }
 
-  test_method_hasNamed() async {
+  Future<void> test_method_hasNamed() async {
     await resolveTestUnit('''
 class A {
   test(int a, {int b: 0}) {}
@@ -175,7 +175,7 @@
 ''');
   }
 
-  test_method_hasOptionalPositional() async {
+  Future<void> test_method_hasOptionalPositional() async {
     await resolveTestUnit('''
 class A {
   test(int a, [int b]) {}
@@ -188,7 +188,7 @@
     await assertNoFix();
   }
 
-  test_method_hasRequired() async {
+  Future<void> test_method_hasRequired() async {
     await resolveTestUnit('''
 class A {
   test(int a) {}
@@ -209,7 +209,7 @@
 ''');
   }
 
-  test_method_noParameters() async {
+  Future<void> test_method_noParameters() async {
     await resolveTestUnit('''
 class A {
   test() {}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_positional_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_positional_test.dart
index ba8e53d..757b017 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_positional_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_positional_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddMissingParameterPositionalTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_MISSING_PARAMETER_POSITIONAL;
 
-  test_function_hasNamed() async {
+  Future<void> test_function_hasNamed() async {
     await resolveTestUnit('''
 test({int a}) {}
 main() {
@@ -29,7 +29,7 @@
     await assertNoFix();
   }
 
-  test_function_hasZero() async {
+  Future<void> test_function_hasZero() async {
     await resolveTestUnit('''
 test() {}
 main() {
@@ -44,7 +44,7 @@
 ''');
   }
 
-  test_method_hasOne() async {
+  Future<void> test_method_hasOne() async {
     await resolveTestUnit('''
 class A {
   test(int a) {}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_required_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_required_test.dart
index b66930d..293c98a 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_required_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_missing_parameter_required_test.dart
@@ -10,7 +10,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddMissingParameterRequiredTest);
     defineReflectiveTests(AddMissingParameterRequiredTest_Workspace);
@@ -22,7 +22,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_MISSING_PARAMETER_REQUIRED;
 
-  test_constructor_named_hasOne() async {
+  Future<void> test_constructor_named_hasOne() async {
     await resolveTestUnit('''
 class A {
   A.named(int a) {}
@@ -41,7 +41,7 @@
 ''');
   }
 
-  test_constructor_unnamed_hasOne() async {
+  Future<void> test_constructor_unnamed_hasOne() async {
     await resolveTestUnit('''
 class A {
   A(int a) {}
@@ -60,7 +60,7 @@
 ''');
   }
 
-  test_function_hasNamed() async {
+  Future<void> test_function_hasNamed() async {
     await resolveTestUnit('''
 test({int a}) {}
 main() {
@@ -75,7 +75,7 @@
 ''');
   }
 
-  test_function_hasOne() async {
+  Future<void> test_function_hasOne() async {
     await resolveTestUnit('''
 test(int a) {}
 main() {
@@ -90,7 +90,7 @@
 ''');
   }
 
-  test_function_hasZero() async {
+  Future<void> test_function_hasZero() async {
     await resolveTestUnit('''
 test() {}
 main() {
@@ -105,7 +105,7 @@
 ''');
   }
 
-  test_method_hasOne() async {
+  Future<void> test_method_hasOne() async {
     await resolveTestUnit('''
 class A {
   test(int a) {}
@@ -124,7 +124,7 @@
 ''');
   }
 
-  test_method_hasZero() async {
+  Future<void> test_method_hasZero() async {
     await resolveTestUnit('''
 class A {
   test() {}
@@ -154,7 +154,7 @@
     return _workspace ?? super.workspace;
   }
 
-  test_function_inPackage_inWorkspace() async {
+  Future<void> test_function_inPackage_inWorkspace() async {
     newFile('/home/aaa/lib/a.dart', content: 'void test() {}');
     addTestPackageDependency('aaa', '/home/aaa');
 
@@ -177,7 +177,7 @@
     );
   }
 
-  test_function_inPackage_outsideWorkspace() async {
+  Future<void> test_function_inPackage_outsideWorkspace() async {
     addPackageFile('bbb', 'b.dart', 'void test() {}');
 
     await resolveTestUnit('''
@@ -190,7 +190,7 @@
     await assertNoFix();
   }
 
-  test_method_inSdk() async {
+  Future<void> test_method_inSdk() async {
     await resolveTestUnit('''
 main() {
   42.abs(true);
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_missing_required_argument_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_missing_required_argument_test.dart
index dcd6666..b471caa 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_missing_required_argument_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_missing_required_argument_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddMissingRequiredArgumentTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_MISSING_REQUIRED_ARGUMENT;
 
-  test_cons_flutter_children() async {
+  Future<void> test_cons_flutter_children() async {
     addFlutterPackage();
     addMetaPackage();
     await resolveTestUnit('''
@@ -48,75 +48,7 @@
 ''');
   }
 
-  test_param_child() async {
-    addFlutterPackage();
-    addMetaPackage();
-    await resolveTestUnit('''
-import 'package:flutter/widgets.dart';
-import 'package:meta/meta.dart';
-
-class MyWidget extends Widget {
-  MyWidget({@required String foo, @required Widget child});
-}
-
-build() {
-  return new MyWidget(
-    child: null,
-  );
-}
-''');
-    await assertHasFix('''
-import 'package:flutter/widgets.dart';
-import 'package:meta/meta.dart';
-
-class MyWidget extends Widget {
-  MyWidget({@required String foo, @required Widget child});
-}
-
-build() {
-  return new MyWidget(
-    foo: null,
-    child: null,
-  );
-}
-''');
-  }
-
-  test_param_children() async {
-    addFlutterPackage();
-    addMetaPackage();
-    await resolveTestUnit('''
-import 'package:flutter/widgets.dart';
-import 'package:meta/meta.dart';
-
-class MyWidget extends Widget {
-  MyWidget({@required String foo, @required List<Widget> children});
-}
-
-build() {
-  return new MyWidget(
-    children: null,
-  );
-}
-''');
-    await assertHasFix('''
-import 'package:flutter/widgets.dart';
-import 'package:meta/meta.dart';
-
-class MyWidget extends Widget {
-  MyWidget({@required String foo, @required List<Widget> children});
-}
-
-build() {
-  return new MyWidget(
-    foo: null,
-    children: null,
-  );
-}
-''');
-  }
-
-  test_cons_flutter_hasTrailingComma() async {
+  Future<void> test_cons_flutter_hasTrailingComma() async {
     addFlutterPackage();
     addMetaPackage();
     await resolveTestUnit('''
@@ -145,7 +77,7 @@
 ''');
   }
 
-  test_cons_single() async {
+  Future<void> test_cons_single() async {
     addMetaPackage();
     addSource('/home/test/lib/a.dart', r'''
 import 'package:meta/meta.dart';
@@ -172,7 +104,7 @@
 ''');
   }
 
-  test_cons_single_closure() async {
+  Future<void> test_cons_single_closure() async {
     addMetaPackage();
     addSource('/home/test/lib/a.dart', r'''
 import 'package:meta/meta.dart';
@@ -201,7 +133,7 @@
 ''');
   }
 
-  test_cons_single_closure_2() async {
+  Future<void> test_cons_single_closure_2() async {
     addMetaPackage();
     addSource('/home/test/lib/a.dart', r'''
 import 'package:meta/meta.dart';
@@ -230,7 +162,7 @@
 ''');
   }
 
-  test_cons_single_closure_3() async {
+  Future<void> test_cons_single_closure_3() async {
     addMetaPackage();
     addSource('/home/test/lib/a.dart', r'''
 import 'package:meta/meta.dart';
@@ -259,7 +191,7 @@
 ''');
   }
 
-  test_cons_single_closure_4() async {
+  Future<void> test_cons_single_closure_4() async {
     addMetaPackage();
     addSource('/home/test/lib/a.dart', r'''
 import 'package:meta/meta.dart';
@@ -288,7 +220,7 @@
 ''');
   }
 
-  test_cons_single_list() async {
+  Future<void> test_cons_single_list() async {
     addMetaPackage();
     addSource('/home/test/lib/a.dart', r'''
 import 'package:meta/meta.dart';
@@ -315,7 +247,7 @@
 ''');
   }
 
-  test_multiple() async {
+  Future<void> test_multiple() async {
     addMetaPackage();
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
@@ -335,7 +267,7 @@
 ''');
   }
 
-  test_multiple_1of2() async {
+  Future<void> test_multiple_1of2() async {
     addMetaPackage();
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
@@ -355,7 +287,7 @@
 ''', errorFilter: (error) => error.message.contains("'a'"));
   }
 
-  test_multiple_2of2() async {
+  Future<void> test_multiple_2of2() async {
     addMetaPackage();
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
@@ -375,7 +307,75 @@
 ''', errorFilter: (error) => error.message.contains("'bcd'"));
   }
 
-  test_single() async {
+  Future<void> test_param_child() async {
+    addFlutterPackage();
+    addMetaPackage();
+    await resolveTestUnit('''
+import 'package:flutter/widgets.dart';
+import 'package:meta/meta.dart';
+
+class MyWidget extends Widget {
+  MyWidget({@required String foo, @required Widget child});
+}
+
+build() {
+  return new MyWidget(
+    child: null,
+  );
+}
+''');
+    await assertHasFix('''
+import 'package:flutter/widgets.dart';
+import 'package:meta/meta.dart';
+
+class MyWidget extends Widget {
+  MyWidget({@required String foo, @required Widget child});
+}
+
+build() {
+  return new MyWidget(
+    foo: null,
+    child: null,
+  );
+}
+''');
+  }
+
+  Future<void> test_param_children() async {
+    addFlutterPackage();
+    addMetaPackage();
+    await resolveTestUnit('''
+import 'package:flutter/widgets.dart';
+import 'package:meta/meta.dart';
+
+class MyWidget extends Widget {
+  MyWidget({@required String foo, @required List<Widget> children});
+}
+
+build() {
+  return new MyWidget(
+    children: null,
+  );
+}
+''');
+    await assertHasFix('''
+import 'package:flutter/widgets.dart';
+import 'package:meta/meta.dart';
+
+class MyWidget extends Widget {
+  MyWidget({@required String foo, @required List<Widget> children});
+}
+
+build() {
+  return new MyWidget(
+    foo: null,
+    children: null,
+  );
+}
+''');
+  }
+
+  Future<void> test_single() async {
     addMetaPackage();
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
@@ -396,7 +396,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['null);']);
   }
 
-  test_single_normal() async {
+  Future<void> test_single_normal() async {
     addMetaPackage();
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
@@ -416,7 +416,7 @@
 ''');
   }
 
-  test_single_with_details() async {
+  Future<void> test_single_with_details() async {
     addMetaPackage();
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_ne_null_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_ne_null_test.dart
index c8b6d00..a844e27 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_ne_null_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_ne_null_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddNeNullTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_NE_NULL;
 
-  test_nonBoolCondition() async {
+  Future<void> test_nonBoolCondition() async {
     await resolveTestUnit('''
 main(String p) {
   if (p) {
@@ -37,7 +37,7 @@
 ''');
   }
 
-  test_nonBoolCondition_all() async {
+  Future<void> test_nonBoolCondition_all() async {
     await resolveTestUnit('''
 main(String p, String q) {
   if (p) {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_override_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_override_test.dart
index 69c6aeb..4113925 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_override_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_override_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddOverrideTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.annotate_overrides;
 
-  test_field() async {
+  Future<void> test_field() async {
     await resolveTestUnit('''
 class abstract Test {
   int get t;
@@ -43,7 +43,7 @@
 ''');
   }
 
-  test_getter() async {
+  Future<void> test_getter() async {
     await resolveTestUnit('''
 class Test {
   int get t => null;
@@ -63,7 +63,7 @@
 ''');
   }
 
-  test_method() async {
+  Future<void> test_method() async {
     await resolveTestUnit('''
 class Test {
   void t() { }
@@ -83,7 +83,7 @@
 ''');
   }
 
-  test_method_with_doc_comment() async {
+  Future<void> test_method_with_doc_comment() async {
     await resolveTestUnit('''
 class Test {
   void t() { }
@@ -105,7 +105,7 @@
 ''');
   }
 
-  test_method_with_doc_comment_2() async {
+  Future<void> test_method_with_doc_comment_2() async {
     await resolveTestUnit('''
 class Test {
   void t() { }
@@ -131,7 +131,7 @@
 ''');
   }
 
-  test_method_with_doc_comment_and_metadata() async {
+  Future<void> test_method_with_doc_comment_and_metadata() async {
     await resolveTestUnit('''
 class Test {
   void t() { }
@@ -155,7 +155,7 @@
 ''');
   }
 
-  test_method_with_non_doc_comment() async {
+  Future<void> test_method_with_non_doc_comment() async {
     await resolveTestUnit('''
 class Test {
   void t() { }
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_required_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_required_test.dart
index 79a452c..8eccd35 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_required_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_required_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddRequiredTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.always_require_non_null_named_parameters;
 
-  test_withAssert() async {
+  Future<void> test_withAssert() async {
     await resolveTestUnit('''
 void function({String /*LINT*/param}) {
   assert(param != null);
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_return_type_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_return_type_test.dart
index d7540ca..dc6e266 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_return_type_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_return_type_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddReturnTypeLintTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.always_declare_return_types;
 
-  test_localFunction_block() async {
+  Future<void> test_localFunction_block() async {
     await resolveTestUnit('''
 class A {
   void m() {
@@ -44,7 +44,7 @@
 ''');
   }
 
-  test_localFunction_expression() async {
+  Future<void> test_localFunction_expression() async {
     await resolveTestUnit('''
 class A {
   void m() {
@@ -61,7 +61,7 @@
 ''');
   }
 
-  test_method_block_noReturn() async {
+  Future<void> test_method_block_noReturn() async {
     await resolveTestUnit('''
 class A {
   /*LINT*/m() {
@@ -71,7 +71,7 @@
     await assertNoFix();
   }
 
-  test_method_block_returnDynamic() async {
+  Future<void> test_method_block_returnDynamic() async {
     await resolveTestUnit('''
 class A {
   /*LINT*/m(p) {
@@ -82,7 +82,7 @@
     await assertNoFix();
   }
 
-  test_method_block_returnNoValue() async {
+  Future<void> test_method_block_returnNoValue() async {
     await resolveTestUnit('''
 class A {
   /*LINT*/m() {
@@ -99,7 +99,7 @@
 ''');
   }
 
-  test_method_block_singleReturn() async {
+  Future<void> test_method_block_singleReturn() async {
     await resolveTestUnit('''
 class A {
   /*LINT*/m() {
@@ -116,7 +116,7 @@
 ''');
   }
 
-  test_method_expression() async {
+  Future<void> test_method_expression() async {
     await resolveTestUnit('''
 class A {
   /*LINT*/m() => '';
@@ -129,7 +129,7 @@
 ''');
   }
 
-  test_topLevelFunction_block() async {
+  Future<void> test_topLevelFunction_block() async {
     await resolveTestUnit('''
 /*LINT*/f() {
   return '';
@@ -142,7 +142,7 @@
 ''');
   }
 
-  test_topLevelFunction_expression() async {
+  Future<void> test_topLevelFunction_expression() async {
     await resolveTestUnit('''
 /*LINT*/f() => '';
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_static_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_static_test.dart
index bf136bd..13f5b25 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_static_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_static_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddStaticTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_STATIC;
 
-  test_multipleFields() async {
+  Future<void> test_multipleFields() async {
     await resolveTestUnit('''
 class C {
   const int x = 0, y = 0;
@@ -32,7 +32,7 @@
 ''');
   }
 
-  test_oneField() async {
+  Future<void> test_oneField() async {
     await resolveTestUnit('''
 class C {
   const int x = 0;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_super_constructor_invocation_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_super_constructor_invocation_test.dart
index f923e4f..ba495c8 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_super_constructor_invocation_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_super_constructor_invocation_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddSuperConstructorInvocationTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_SUPER_CONSTRUCTOR_INVOCATION;
 
-  test_hasInitializers() async {
+  Future<void> test_hasInitializers() async {
     await resolveTestUnit('''
 class A {
   A(int p);
@@ -40,7 +40,7 @@
 ''');
   }
 
-  test_named() async {
+  Future<void> test_named() async {
     await resolveTestUnit('''
 class A {
   A.named(int p);
@@ -59,7 +59,7 @@
 ''');
   }
 
-  test_named_private() async {
+  Future<void> test_named_private() async {
     await resolveTestUnit('''
 class A {
   A._named(int p); // ignore: unused_element
@@ -71,7 +71,7 @@
     await assertNoFix();
   }
 
-  test_requiredAndNamed() async {
+  Future<void> test_requiredAndNamed() async {
     await resolveTestUnit('''
 class A {
   A(bool p1, int p2, double p3, String p4, {p5});
@@ -90,7 +90,7 @@
 ''');
   }
 
-  test_typeArgument() async {
+  Future<void> test_typeArgument() async {
     await resolveTestUnit('''
 class A<T> {
   A(T p);
diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_type_annotation_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_type_annotation_test.dart
index 21b86e4..5eacfec 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_type_annotation_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_type_annotation_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddTypeAnnotationLintTest);
     defineReflectiveTests(AddTypeAnnotationTest);
@@ -25,7 +25,7 @@
   String get lintCode => LintNames.always_specify_types;
 
   // More coverage in the `add_type_annotation_test.dart` assist test.
-  test_do_block() async {
+  Future<void> test_do_block() async {
     await resolveTestUnit('''
 class A {
   /*LINT*/final f = 0;
@@ -44,7 +44,7 @@
   @override
   FixKind get kind => DartFixKind.ADD_TYPE_ANNOTATION;
 
-  test_missingFieldType() async {
+  Future<void> test_missingFieldType() async {
     // MISSING_CONST_FINAL_VAR_OR_TYPE
     await resolveTestUnit('''
 class A {
@@ -58,7 +58,7 @@
 ''');
   }
 
-  test_missingStaticFieldType() async {
+  Future<void> test_missingStaticFieldType() async {
     // MISSING_CONST_FINAL_VAR_OR_TYPE
     await resolveTestUnit('''
 class A {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/analysis_options/remove_setting_test.dart b/pkg/analysis_server/test/src/services/correction/fix/analysis_options/remove_setting_test.dart
index 548d53a..c378884 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/analysis_options/remove_setting_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/analysis_options/remove_setting_test.dart
@@ -6,7 +6,7 @@
 
 import 'test_support.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveSettingTest);
   });
@@ -14,7 +14,7 @@
 
 @reflectiveTest
 class RemoveSettingTest extends AnalysisOptionsFixTest {
-  test_enableSuperMixins() async {
+  Future<void> test_enableSuperMixins() async {
     await assertHasFix('''
 analyzer:
   enable-experiment:
@@ -28,7 +28,7 @@
 ''');
   }
 
-  test_invalidExperiment_first() async {
+  Future<void> test_invalidExperiment_first() async {
     await assertHasFix('''
 analyzer:
   enable-experiment:
@@ -41,7 +41,7 @@
 ''');
   }
 
-  test_invalidExperiment_last() async {
+  Future<void> test_invalidExperiment_last() async {
     await assertHasFix('''
 analyzer:
   enable-experiment:
@@ -54,7 +54,7 @@
 ''');
   }
 
-  test_invalidExperiment_only() async {
+  Future<void> test_invalidExperiment_only() async {
     await assertHasFix('''
 analyzer:
   enable-experiment:
diff --git a/pkg/analysis_server/test/src/services/correction/fix/analysis_options/test_all.dart b/pkg/analysis_server/test/src/services/correction/fix/analysis_options/test_all.dart
index c202ee9..e17f40e 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/analysis_options/test_all.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/analysis_options/test_all.dart
@@ -6,7 +6,7 @@
 
 import 'remove_setting_test.dart' as remove_setting;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     remove_setting.main();
   });
diff --git a/pkg/analysis_server/test/src/services/correction/fix/change_argument_name_test.dart b/pkg/analysis_server/test/src/services/correction/fix/change_argument_name_test.dart
index 2707a41..bd4ac94 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/change_argument_name_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/change_argument_name_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ChangeArgumentNameTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.CHANGE_ARGUMENT_NAME;
 
-  test_child_constructor() async {
+  Future<void> test_child_constructor() async {
     await resolveTestUnit('''
 f() => new A(children: 2);
 class A {
@@ -34,7 +34,7 @@
 ''');
   }
 
-  test_child_function() async {
+  Future<void> test_child_function() async {
     await resolveTestUnit('''
 f() {
   g(children: 0);
@@ -49,7 +49,7 @@
 ''');
   }
 
-  test_child_method() async {
+  Future<void> test_child_method() async {
     await resolveTestUnit('''
 f(A a) {
   a.m(children: 0);
@@ -68,7 +68,7 @@
 ''');
   }
 
-  test_children_constructor() async {
+  Future<void> test_children_constructor() async {
     await resolveTestUnit('''
 f() => new A(child: 2);
 class A {
@@ -83,7 +83,7 @@
 ''');
   }
 
-  test_children_function() async {
+  Future<void> test_children_function() async {
     await resolveTestUnit('''
 f() {
   g(child: 0);
@@ -98,7 +98,7 @@
 ''');
   }
 
-  test_children_method() async {
+  Future<void> test_children_method() async {
     await resolveTestUnit('''
 f(A a) {
   a.m(child: 0);
@@ -117,7 +117,7 @@
 ''');
   }
 
-  test_default_annotation() async {
+  Future<void> test_default_annotation() async {
     await resolveTestUnit('''
 @A(boot: 2)
 f() => null;
@@ -134,7 +134,7 @@
 ''');
   }
 
-  test_default_constructor() async {
+  Future<void> test_default_constructor() async {
     await resolveTestUnit('''
 f() => new A(boot: 2);
 class A {
@@ -149,7 +149,7 @@
 ''');
   }
 
-  test_default_function() async {
+  Future<void> test_default_function() async {
     await resolveTestUnit('''
 f() {
   g(boot: 0);
@@ -164,7 +164,7 @@
 ''');
   }
 
-  test_default_method() async {
+  Future<void> test_default_method() async {
     await resolveTestUnit('''
 f(A a) {
   a.m(boot: 0);
@@ -183,7 +183,7 @@
 ''');
   }
 
-  test_default_redirectingConstructor() async {
+  Future<void> test_default_redirectingConstructor() async {
     await resolveTestUnit('''
 class A {
   A.one() : this.two(boot: 3);
@@ -198,7 +198,7 @@
 ''');
   }
 
-  test_default_superConstructor() async {
+  Future<void> test_default_superConstructor() async {
     await resolveTestUnit('''
 class A {
   A.a({int boat});
@@ -217,7 +217,7 @@
 ''');
   }
 
-  test_tooDistant_constructor() async {
+  Future<void> test_tooDistant_constructor() async {
     await resolveTestUnit('''
 f() => new A(bbbbb: 2);
 class A {
@@ -227,7 +227,7 @@
     await assertNoFix();
   }
 
-  test_tooDistant_function() async {
+  Future<void> test_tooDistant_function() async {
     await resolveTestUnit('''
 f() {
   g(bbbbb: 0);
@@ -237,7 +237,7 @@
     await assertNoFix();
   }
 
-  test_tooDistant_method() async {
+  Future<void> test_tooDistant_method() async {
     await resolveTestUnit('''
 f(A a) {
   a.m(bbbbb: 0);
diff --git a/pkg/analysis_server/test/src/services/correction/fix/change_to_nearest_precise_value_test.dart b/pkg/analysis_server/test/src/services/correction/fix/change_to_nearest_precise_value_test.dart
index 01c6749..6a9c074 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/change_to_nearest_precise_value_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/change_to_nearest_precise_value_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ChangeToNearestPreciseValueTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.CHANGE_TO_NEAREST_PRECISE_VALUE;
 
-  test_impreciseIntAsDouble() async {
+  Future<void> test_impreciseIntAsDouble() async {
     await resolveTestUnit('''
 double x = 1000000000000000000000000;
 ''');
@@ -28,7 +28,7 @@
 ''');
   }
 
-  test_impreciseIntAsDouble_asCapitalHex() async {
+  Future<void> test_impreciseIntAsDouble_asCapitalHex() async {
     await resolveTestUnit('''
 double x = 0X1000000000000000000000001;
 ''');
@@ -37,7 +37,7 @@
 ''');
   }
 
-  test_impreciseIntAsDouble_asHex() async {
+  Future<void> test_impreciseIntAsDouble_asHex() async {
     await resolveTestUnit('''
 double x = 0x1000000000000000000000001;
 ''');
@@ -46,7 +46,7 @@
 ''');
   }
 
-  test_impreciseIntAsDouble_maxValue() async {
+  Future<void> test_impreciseIntAsDouble_maxValue() async {
     await resolveTestUnit('''
 double x = 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000;
 ''');
@@ -55,7 +55,7 @@
 ''');
   }
 
-  test_impreciseIntAsDouble_maxValue_asHex() async {
+  Future<void> test_impreciseIntAsDouble_maxValue_asHex() async {
     await resolveTestUnit('''
 double x = 0x100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000;
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/change_to_static_access_test.dart b/pkg/analysis_server/test/src/services/correction/fix/change_to_static_access_test.dart
index 8ae3d08..0011642 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/change_to_static_access_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/change_to_static_access_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ChangeToStaticAccessClassTest);
     defineReflectiveTests(ChangeToStaticAccessExtensionTest);
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.CHANGE_TO_STATIC_ACCESS;
 
-  test_method() async {
+  Future<void> test_method() async {
     await resolveTestUnit('''
 class A {
   static foo() {}
@@ -39,7 +39,7 @@
 ''');
   }
 
-  test_method_importType() async {
+  Future<void> test_method_importType() async {
     addSource('/home/test/lib/a.dart', r'''
 class A {
   static foo() {}
@@ -67,7 +67,7 @@
 ''');
   }
 
-  test_method_prefixLibrary() async {
+  Future<void> test_method_prefixLibrary() async {
     await resolveTestUnit('''
 import 'dart:async' as pref;
 main(pref.Future f) {
@@ -82,7 +82,7 @@
 ''');
   }
 
-  test_property() async {
+  Future<void> test_property() async {
     await resolveTestUnit('''
 class A {
   static get foo => 42;
@@ -101,7 +101,7 @@
 ''');
   }
 
-  test_property_importType() async {
+  Future<void> test_property_importType() async {
     addSource('/home/test/lib/a.dart', r'''
 class A {
   static get foo => null;
@@ -135,7 +135,7 @@
   @override
   FixKind get kind => DartFixKind.CHANGE_TO_STATIC_ACCESS;
 
-  test_method() async {
+  Future<void> test_method() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     await resolveTestUnit('''
 extension E on int {
@@ -156,7 +156,7 @@
   }
 
   @failingTest
-  test_property() async {
+  Future<void> test_property() async {
     createAnalysisOptionsFile(experiments: ['extension-methods']);
     await resolveTestUnit('''
 extension E on int {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/change_to_test.dart b/pkg/analysis_server/test/src/services/correction/fix/change_to_test.dart
index 0f02b8c..a91fc11 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/change_to_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/change_to_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ChangeToTest);
     defineReflectiveTests(ChangeToWithExtensionMethodsTest);
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.CHANGE_TO;
 
-  test_class_fromImport() async {
+  Future<void> test_class_fromImport() async {
     await resolveTestUnit('''
 main() {
   Stirng s = 'abc';
@@ -35,7 +35,7 @@
 ''');
   }
 
-  test_class_fromThisLibrary() async {
+  Future<void> test_class_fromThisLibrary() async {
     await resolveTestUnit('''
 class MyClass {}
 main() {
@@ -52,7 +52,7 @@
 ''');
   }
 
-  test_class_prefixed() async {
+  Future<void> test_class_prefixed() async {
     await resolveTestUnit('''
 import 'dart:async' as c;
 main() {
@@ -69,7 +69,7 @@
 ''');
   }
 
-  test_function_fromImport() async {
+  Future<void> test_function_fromImport() async {
     await resolveTestUnit('''
 main() {
   pritn(0);
@@ -82,7 +82,7 @@
 ''');
   }
 
-  test_function_prefixed_fromImport() async {
+  Future<void> test_function_prefixed_fromImport() async {
     await resolveTestUnit('''
 import 'dart:core' as c;
 main() {
@@ -97,7 +97,7 @@
 ''');
   }
 
-  test_function_prefixed_ignoreLocal() async {
+  Future<void> test_function_prefixed_ignoreLocal() async {
     await resolveTestUnit('''
 import 'dart:async' as c;
 main() {
@@ -107,7 +107,7 @@
     await assertNoFix();
   }
 
-  test_function_thisLibrary() async {
+  Future<void> test_function_thisLibrary() async {
     await resolveTestUnit('''
 myFunction() {}
 main() {
@@ -122,7 +122,7 @@
 ''');
   }
 
-  test_getter_hint() async {
+  Future<void> test_getter_hint() async {
     await resolveTestUnit('''
 class A {
   int myField;
@@ -143,7 +143,7 @@
 ''');
   }
 
-  test_getter_qualified() async {
+  Future<void> test_getter_qualified() async {
     await resolveTestUnit('''
 class A {
   int myField;
@@ -162,7 +162,7 @@
 ''');
   }
 
-  test_getter_qualified_static() async {
+  Future<void> test_getter_qualified_static() async {
     await resolveTestUnit('''
 class A {
   static int MY_NAME = 1;
@@ -181,7 +181,7 @@
 ''');
   }
 
-  test_getter_unqualified() async {
+  Future<void> test_getter_unqualified() async {
     await resolveTestUnit('''
 class A {
   int myField;
@@ -200,7 +200,7 @@
 ''');
   }
 
-  test_method_ignoreOperators() async {
+  Future<void> test_method_ignoreOperators() async {
     await resolveTestUnit('''
 main(Object object) {
   object.then();
@@ -209,7 +209,7 @@
     await assertNoFix();
   }
 
-  test_method_qualified() async {
+  Future<void> test_method_qualified() async {
     await resolveTestUnit('''
 class A {
   myMethod() {}
@@ -230,7 +230,7 @@
 ''');
   }
 
-  test_method_unqualified_superClass() async {
+  Future<void> test_method_unqualified_superClass() async {
     await resolveTestUnit('''
 class A {
   myMethod() {}
@@ -253,7 +253,7 @@
 ''');
   }
 
-  test_method_unqualified_thisClass() async {
+  Future<void> test_method_unqualified_thisClass() async {
     await resolveTestUnit('''
 class A {
   myMethod() {}
@@ -272,7 +272,7 @@
 ''');
   }
 
-  test_setter_hint() async {
+  Future<void> test_setter_hint() async {
     await resolveTestUnit('''
 class A {
   int myField;
@@ -293,7 +293,7 @@
 ''');
   }
 
-  test_setter_qualified() async {
+  Future<void> test_setter_qualified() async {
     await resolveTestUnit('''
 class A {
   int myField;
@@ -312,7 +312,7 @@
 ''');
   }
 
-  test_setter_unqualified() async {
+  Future<void> test_setter_unqualified() async {
     await resolveTestUnit('''
 class A {
   int myField;
@@ -343,7 +343,7 @@
     super.setUp();
   }
 
-  test_getter_override() async {
+  Future<void> test_getter_override() async {
     await resolveTestUnit('''
 extension E on int {
   int get myGetter => 0;
@@ -362,7 +362,7 @@
 ''');
   }
 
-  test_getter_static() async {
+  Future<void> test_getter_static() async {
     await resolveTestUnit('''
 extension E on int {
   static int get myGetter => 0;
@@ -381,7 +381,7 @@
 ''');
   }
 
-  test_method_override() async {
+  Future<void> test_method_override() async {
     await resolveTestUnit('''
 extension E on int {
   int myMethod() => 0;
@@ -400,7 +400,7 @@
 ''');
   }
 
-  test_method_static() async {
+  Future<void> test_method_static() async {
     await resolveTestUnit('''
 extension E on int {
   static int myMethod() => 0;
@@ -419,7 +419,7 @@
 ''');
   }
 
-  test_setter_override() async {
+  Future<void> test_setter_override() async {
     await resolveTestUnit('''
 extension E on int {
   void set mySetter(int i) {}
@@ -438,7 +438,7 @@
 ''');
   }
 
-  test_setter_static() async {
+  Future<void> test_setter_static() async {
     await resolveTestUnit('''
 extension E on int {
   static void set mySetter(int i) {}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/change_type_annotation_test.dart b/pkg/analysis_server/test/src/services/correction/fix/change_type_annotation_test.dart
index 8fbb66a..b40284a 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/change_type_annotation_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/change_type_annotation_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ChangeTypeAnnotationTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.CHANGE_TYPE_ANNOTATION;
 
-  test_generic() async {
+  Future<void> test_generic() async {
     await resolveTestUnit('''
 main() {
   String v = <int>[];
@@ -34,7 +34,7 @@
 ''');
   }
 
-  test_multipleVariables() async {
+  Future<void> test_multipleVariables() async {
     await resolveTestUnit('''
 main() {
   String a, b = 42;
@@ -44,7 +44,7 @@
     await assertNoFix();
   }
 
-  test_notVariableDeclaration() async {
+  Future<void> test_notVariableDeclaration() async {
     await resolveTestUnit('''
 main() {
   String v;
@@ -55,7 +55,7 @@
     await assertNoFix();
   }
 
-  test_simple() async {
+  Future<void> test_simple() async {
     await resolveTestUnit('''
 main() {
   String v = 'abc'.length;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_documentation_into_line_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_documentation_into_line_test.dart
index 0d75e37..2dccc30 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_documentation_into_line_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_documentation_into_line_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertDocumentationIntoLineTest);
   });
@@ -24,7 +24,7 @@
   String get lintCode => LintNames.slash_for_doc_comments;
 
   /// More coverage in the `convert_to_documentation_line_test.dart` assist test.
-  test_onText() async {
+  Future<void> test_onText() async {
     await resolveTestUnit('''
 class A {
   /**
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_flutter_child_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_flutter_child_test.dart
index e75321d..3e17f59 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_flutter_child_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_flutter_child_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertFlutterChildTest);
   });
@@ -19,7 +19,67 @@
   @override
   FixKind get kind => DartFixKind.CONVERT_FLUTTER_CHILD;
 
-  test_hasList() async {
+  Future<void> test_hasList() async {
+    addFlutterPackage();
+    await resolveTestUnit('''
+import 'package:flutter/widgets.dart';
+build() {
+  return Container(
+    child: Row(
+      child: [
+        Text('111'),
+        Text('222'),
+      ],
+    ),
+  );
+}
+''');
+    await assertHasFix('''
+import 'package:flutter/widgets.dart';
+build() {
+  return Container(
+    child: Row(
+      children: [
+        Text('111'),
+        Text('222'),
+      ],
+    ),
+  );
+}
+''');
+  }
+
+  Future<void> test_hasTypedList() async {
+    addFlutterPackage();
+    await resolveTestUnit('''
+import 'package:flutter/widgets.dart';
+build() {
+  return new Container(
+    child: new Row(
+      child: <Widget>[
+        new Text('111'),
+        new Text('222'),
+      ],
+    ),
+  );
+}
+''');
+    await assertHasFix('''
+import 'package:flutter/widgets.dart';
+build() {
+  return new Container(
+    child: new Row(
+      children: <Widget>[
+        new Text('111'),
+        new Text('222'),
+      ],
+    ),
+  );
+}
+''');
+  }
+
+  Future<void> test_listNotWidget() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -27,66 +87,6 @@
   return new Container(
     child: new Row(
       child: [
-        new Text('111'),
-        new Text('222'),
-      ],
-    ),
-  );
-}
-''');
-    await assertHasFix('''
-import 'package:flutter/widgets.dart';
-build() {
-  return new Container(
-    child: new Row(
-      children: <Widget>[
-        new Text('111'),
-        new Text('222'),
-      ],
-    ),
-  );
-}
-''');
-  }
-
-  test_hasTypedList() async {
-    addFlutterPackage();
-    await resolveTestUnit('''
-import 'package:flutter/widgets.dart';
-build() {
-  return new Container(
-    child: new Row(
-      child: <Widget>[
-        new Text('111'),
-        new Text('222'),
-      ],
-    ),
-  );
-}
-''');
-    await assertHasFix('''
-import 'package:flutter/widgets.dart';
-build() {
-  return new Container(
-    child: new Row(
-      children: <Widget>[
-        new Text('111'),
-        new Text('222'),
-      ],
-    ),
-  );
-}
-''');
-  }
-
-  test_listNotWidget() async {
-    addFlutterPackage();
-    await resolveTestUnit('''
-import 'package:flutter/widgets.dart';
-build() {
-  return new Container(
-    child: new Row(
-      child: <Widget>[
         new Container(),
         null,
       ],
@@ -97,7 +97,7 @@
     await assertNoFix();
   }
 
-  test_multiLine() async {
+  Future<void> test_multiLine() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -117,7 +117,7 @@
 build() {
   return new Scaffold(
     body: new Row(
-      children: <Widget>[
+      children: [
         new Container(
           width: 200.0,
           height: 300.0,
@@ -129,7 +129,7 @@
 ''');
   }
 
-  test_widgetVariable() async {
+  Future<void> test_widgetVariable() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -145,7 +145,7 @@
 build() {
   var text = new Text('foo');
   new Row(
-    children: <Widget>[text],
+    children: [text],
   );
 }
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_flutter_children_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_flutter_children_test.dart
index f975f0a..8f71ef6 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_flutter_children_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_flutter_children_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertFlutterChildrenTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.CONVERT_FLUTTER_CHILDREN;
 
-  test_undefinedParameter_multiLine() async {
+  Future<void> test_undefinedParameter_multiLine() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -47,7 +47,7 @@
 ''');
   }
 
-  test_undefinedParameter_notWidget() async {
+  Future<void> test_undefinedParameter_notWidget() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -62,7 +62,7 @@
     await assertNoFix();
   }
 
-  test_undefinedParameter_singleLine() async {
+  Future<void> test_undefinedParameter_singleLine() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -84,7 +84,7 @@
 ''');
   }
 
-  test_undefinedParameter_singleLine2() async {
+  Future<void> test_undefinedParameter_singleLine2() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_into_expression_body_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_into_expression_body_test.dart
index 6ec1ad1..832ea45 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_into_expression_body_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_into_expression_body_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertIntoExpressionBodyTest);
   });
@@ -24,7 +24,7 @@
   String get lintCode => LintNames.prefer_expression_function_bodies;
 
   /// More coverage in the `convert_into_expression_body_test.dart` assist test.
-  test_async() async {
+  Future<void> test_async() async {
     await resolveTestUnit('''
 class A {
   mmm() async { 
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_for_element_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_for_element_test.dart
index 450db7e..76ae348 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_for_element_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_for_element_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToForElementTest);
   });
@@ -24,7 +24,8 @@
   String get lintCode => LintNames.prefer_for_elements_to_map_fromIterable;
 
   /// More coverage in the `convert_to_for_element_line_test.dart` assist test.
-  test_mapFromIterable_differentParameterNames_usedInKey_conflictInValue() async {
+  Future<void>
+      test_mapFromIterable_differentParameterNames_usedInKey_conflictInValue() async {
     await resolveTestUnit('''
 f(Iterable<int> i) {
   var k = 3;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_generic_function_syntax_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_generic_function_syntax_test.dart
index 4ce86e6..fd4e744 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_generic_function_syntax_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_generic_function_syntax_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(PreferGenericFunctionTypeAliasesTest);
     defineReflectiveTests(UseFunctionTypeSyntaxForParametersTest);
@@ -24,14 +24,14 @@
   @override
   String get lintCode => LintNames.prefer_generic_function_type_aliases;
 
-  test_functionTypeAlias_noParameterTypes() async {
+  Future<void> test_functionTypeAlias_noParameterTypes() async {
     await resolveTestUnit('''
 typedef String /*LINT*/F(x);
 ''');
     await assertNoFix();
   }
 
-  test_functionTypeAlias_noReturnType_noTypeParameters() async {
+  Future<void> test_functionTypeAlias_noReturnType_noTypeParameters() async {
     await resolveTestUnit('''
 typedef String /*LINT*/F(int x);
 ''');
@@ -40,7 +40,7 @@
 ''');
   }
 
-  test_functionTypeAlias_noReturnType_typeParameters() async {
+  Future<void> test_functionTypeAlias_noReturnType_typeParameters() async {
     await resolveTestUnit('''
 typedef /*LINT*/F<P, R>(P x);
 ''');
@@ -49,7 +49,7 @@
 ''');
   }
 
-  test_functionTypeAlias_returnType_noTypeParameters() async {
+  Future<void> test_functionTypeAlias_returnType_noTypeParameters() async {
     await resolveTestUnit('''
 typedef String /*LINT*/F(int x);
 ''');
@@ -58,7 +58,7 @@
 ''');
   }
 
-  test_functionTypeAlias_returnType_typeParameters() async {
+  Future<void> test_functionTypeAlias_returnType_typeParameters() async {
     await resolveTestUnit('''
 typedef R /*LINT*/F<P, R>(P x);
 ''');
@@ -76,14 +76,14 @@
   @override
   String get lintCode => LintNames.use_function_type_syntax_for_parameters;
 
-  test_functionTypedParameter_noParameterTypes() async {
+  Future<void> test_functionTypedParameter_noParameterTypes() async {
     await resolveTestUnit('''
 g(String /*LINT*/f(x)) {}
 ''');
     await assertNoFix();
   }
 
-  test_functionTypedParameter_returnType() async {
+  Future<void> test_functionTypedParameter_returnType() async {
     await resolveTestUnit('''
 g(String /*LINT*/f(int x)) {}
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_if_element_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_if_element_test.dart
index c99a0be..b4a8b0d 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_if_element_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_if_element_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToIfElementTest);
   });
@@ -25,7 +25,7 @@
       LintNames.prefer_if_elements_to_conditional_expressions;
 
   // More coverage in the `convert_to_if_element_test.dart` assist test.
-  test_conditional_list() async {
+  Future<void> test_conditional_list() async {
     await resolveTestUnit('''
 f(bool b) {
   return ['a', b /*LINT*/? 'c' : 'd', 'e'];
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_if_null_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_if_null_test.dart
index 50e4277..feac4bd 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_if_null_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_if_null_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToIfNullTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_if_null_operators;
 
-  test_equalEqual() async {
+  Future<void> test_equalEqual() async {
     await resolveTestUnit('''
 void f(String s) {
   print(/*LINT*/s == null ? 'default' : s);
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_notEqual() async {
+  Future<void> test_notEqual() async {
     await resolveTestUnit('''
 void f(String s) {
   print(/*LINT*/s != null ? s : 'default');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_int_literal_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_int_literal_test.dart
index 09a819e..76a903e 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_int_literal_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_int_literal_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToIntLiteralTest);
   });
@@ -24,7 +24,7 @@
   String get lintCode => LintNames.prefer_int_literals;
 
   /// More coverage in the `convert_to_int_literal_test.dart` assist test.
-  test_decimal() async {
+  Future<void> test_decimal() async {
     await resolveTestUnit('''
 const double myDouble = /*LINT*/42.0;
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_list_literal_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_list_literal_test.dart
index 26164f4..d3af501 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_list_literal_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_list_literal_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToListLiteralTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_collection_literals;
 
-  test_default_declaredType() async {
+  Future<void> test_default_declaredType() async {
     await resolveTestUnit('''
 List l = /*LINT*/List();
 ''');
@@ -32,7 +32,7 @@
 ''');
   }
 
-  test_default_minimal() async {
+  Future<void> test_default_minimal() async {
     await resolveTestUnit('''
 var l = /*LINT*/List();
 ''');
@@ -41,7 +41,7 @@
 ''');
   }
 
-  test_default_newKeyword() async {
+  Future<void> test_default_newKeyword() async {
     await resolveTestUnit('''
 var l = /*LINT*/new List();
 ''');
@@ -50,14 +50,14 @@
 ''');
   }
 
-  test_default_tooManyArguments() async {
+  Future<void> test_default_tooManyArguments() async {
     await resolveTestUnit('''
 var l = /*LINT*/List(5);
 ''');
     await assertNoFix();
   }
 
-  test_default_typeArg() async {
+  Future<void> test_default_typeArg() async {
     await resolveTestUnit('''
 var l = /*LINT*/List<int>();
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_map_literal_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_map_literal_test.dart
index be18574..1287453 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_map_literal_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_map_literal_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToMapLiteralTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_collection_literals;
 
-  test_default_declaredType() async {
+  Future<void> test_default_declaredType() async {
     await resolveTestUnit('''
 Map m = /*LINT*/Map();
 ''');
@@ -32,7 +32,7 @@
 ''');
   }
 
-  test_default_linkedHashMap() async {
+  Future<void> test_default_linkedHashMap() async {
     await resolveTestUnit('''
 import 'dart:collection';
 var m = /*LINT*/LinkedHashMap();
@@ -43,7 +43,7 @@
 ''');
   }
 
-  test_default_minimal() async {
+  Future<void> test_default_minimal() async {
     await resolveTestUnit('''
 var m = /*LINT*/Map();
 ''');
@@ -52,7 +52,7 @@
 ''');
   }
 
-  test_default_newKeyword() async {
+  Future<void> test_default_newKeyword() async {
     await resolveTestUnit('''
 var m = /*LINT*/new Map();
 ''');
@@ -61,7 +61,7 @@
 ''');
   }
 
-  test_default_typeArg() async {
+  Future<void> test_default_typeArg() async {
     await resolveTestUnit('''
 var m = /*LINT*/Map<String, int>();
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_named_arguments_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_named_arguments_test.dart
index 7760596..95bcb68 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_named_arguments_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_named_arguments_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToNamedArgumentsTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.CONVERT_TO_NAMED_ARGUMENTS;
 
-  test_ambiguous() async {
+  Future<void> test_ambiguous() async {
     await resolveTestUnit('''
 class A {
   A({int a, int b});
@@ -32,7 +32,7 @@
     await assertNoFix();
   }
 
-  test_functionExpressionInvocation_getter() async {
+  Future<void> test_functionExpressionInvocation_getter() async {
     await resolveTestUnit('''
 class A {
   void Function({int aaa}) get g => null;
@@ -53,7 +53,7 @@
 ''');
   }
 
-  test_functionExpressionInvocation_variable() async {
+  Future<void> test_functionExpressionInvocation_variable() async {
     await resolveTestUnit('''
 typedef F = void Function({int aaa});
 
@@ -70,7 +70,7 @@
 ''');
   }
 
-  test_instanceCreation() async {
+  Future<void> test_instanceCreation() async {
     await resolveTestUnit('''
 class A {
   A({int a, double b});
@@ -91,7 +91,7 @@
 ''');
   }
 
-  test_instanceCreation_hasPositional() async {
+  Future<void> test_instanceCreation_hasPositional() async {
     await resolveTestUnit('''
 class A {
   A(int a, {int b});
@@ -112,7 +112,7 @@
 ''');
   }
 
-  test_methodInvocation() async {
+  Future<void> test_methodInvocation() async {
     await resolveTestUnit('''
 class C {
   void foo({int a}) {}
@@ -133,7 +133,7 @@
 ''');
   }
 
-  test_noCompatibleParameter() async {
+  Future<void> test_noCompatibleParameter() async {
     await resolveTestUnit('''
 class A {
   A({String a});
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_null_aware_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_null_aware_test.dart
index 3f8d5e6..f84f0ec 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_null_aware_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_null_aware_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToNullAwareTest);
   });
@@ -24,7 +24,7 @@
   String get lintCode => LintNames.prefer_null_aware_operators;
 
   /// More coverage in the `convert_to_null_aware_test.dart` assist test.
-  test_equal_nullOnLeft() async {
+  Future<void> test_equal_nullOnLeft() async {
     await resolveTestUnit('''
 abstract class A {
   int m();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_package_import_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_package_import_test.dart
index 981d0e8..c55737c 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_package_import_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_package_import_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToPackageImportTest);
   });
@@ -24,7 +24,7 @@
   String get lintCode => LintNames.avoid_relative_lib_imports;
 
   /// More coverage in the `convert_to_package_import_test.dart` assist test.
-  test_relativeImport() async {
+  Future<void> test_relativeImport() async {
     addSource('/home/test/lib/foo.dart', '');
     testFile = convertPath('/home/test/lib/src/test.dart');
     await resolveTestUnit('''
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_relative_import_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_relative_import_test.dart
index 26a0b78..f1ccd9a 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_relative_import_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_relative_import_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToRelativeImportTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_relative_imports;
 
-  test_relativeImport() async {
+  Future<void> test_relativeImport() async {
     addSource('/home/test/lib/foo.dart', '');
     testFile = convertPath('/home/test/lib/src/test.dart');
     await resolveTestUnit('''
@@ -35,7 +35,7 @@
 ''');
   }
 
-  test_relativeImportDifferentPackages() async {
+  Future<void> test_relativeImportDifferentPackages() async {
     // Validate we don't get a fix with imports referencing different packages.
     addSource('/home/test1/lib/foo.dart', '');
     testFile = convertPath('/home/test2/lib/bar.dart');
@@ -46,7 +46,7 @@
     await assertNoFix();
   }
 
-  test_relativeImportGarbledUri() async {
+  Future<void> test_relativeImportGarbledUri() async {
     addSource('/home/test/lib/foo.dart', '');
     testFile = convertPath('/home/test/lib/bar.dart');
     await resolveTestUnit('''
@@ -58,7 +58,7 @@
 ''');
   }
 
-  test_relativeImportRespectQuoteStyle() async {
+  Future<void> test_relativeImportRespectQuoteStyle() async {
     addSource('/home/test/lib/foo.dart', '');
     testFile = convertPath('/home/test/lib/bar.dart');
     await resolveTestUnit('''
@@ -70,7 +70,7 @@
 ''');
   }
 
-  test_relativeImportSameDirectory() async {
+  Future<void> test_relativeImportSameDirectory() async {
     addSource('/home/test/lib/foo.dart', '');
     testFile = convertPath('/home/test/lib/bar.dart');
     await resolveTestUnit('''
@@ -82,7 +82,7 @@
 ''');
   }
 
-  test_relativeImportSubDirectory() async {
+  Future<void> test_relativeImportSubDirectory() async {
     addSource('/home/test/lib/baz/foo.dart', '');
     testFile = convertPath('/home/test/lib/test.dart');
     await resolveTestUnit('''
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_set_literal_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_set_literal_test.dart
index 9fdd206..553d2a0 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_set_literal_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_set_literal_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToSetLiteralTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_collection_literals;
 
-  test_default_declaredType() async {
+  Future<void> test_default_declaredType() async {
     await resolveTestUnit('''
 Set s = /*LINT*/Set();
 ''');
@@ -32,7 +32,7 @@
 ''');
   }
 
-  test_default_minimal() async {
+  Future<void> test_default_minimal() async {
     await resolveTestUnit('''
 var s = /*LINT*/Set();
 ''');
@@ -41,7 +41,7 @@
 ''');
   }
 
-  test_default_newKeyword() async {
+  Future<void> test_default_newKeyword() async {
     await resolveTestUnit('''
 var s = /*LINT*/new Set();
 ''');
@@ -50,7 +50,7 @@
 ''');
   }
 
-  test_default_typeArg() async {
+  Future<void> test_default_typeArg() async {
     await resolveTestUnit('''
 var s = /*LINT*/Set<int>();
 ''');
@@ -60,7 +60,7 @@
   }
 
   @failingTest
-  test_default_typeArg_linkedHashSet() async {
+  Future<void> test_default_typeArg_linkedHashSet() async {
     // LinkedHashSet isn't converted even though the lint reports that case.
     await resolveTestUnit('''
 import 'dart:collection';
@@ -74,7 +74,7 @@
 ''');
   }
 
-  test_from_empty() async {
+  Future<void> test_from_empty() async {
     await resolveTestUnit('''
 var s = /*LINT*/Set.from([]);
 ''');
@@ -84,7 +84,7 @@
   }
 
   @failingTest
-  test_from_inferred() async {
+  Future<void> test_from_inferred() async {
     // _setWouldBeInferred does not check for inference based on the parameter
     // type.
     await resolveTestUnit('''
@@ -97,7 +97,7 @@
 ''');
   }
 
-  test_from_newKeyword() async {
+  Future<void> test_from_newKeyword() async {
     await resolveTestUnit('''
 var s = /*LINT*/new Set.from([2, 3]);
 ''');
@@ -106,7 +106,7 @@
 ''');
   }
 
-  test_from_noKeyword_declaredType() async {
+  Future<void> test_from_noKeyword_declaredType() async {
     await resolveTestUnit('''
 Set s = /*LINT*/Set.from([2, 3]);
 ''');
@@ -115,7 +115,7 @@
 ''');
   }
 
-  test_from_noKeyword_typeArg_onConstructor() async {
+  Future<void> test_from_noKeyword_typeArg_onConstructor() async {
     await resolveTestUnit('''
 var s = /*LINT*/Set<int>.from([2, 3]);
 ''');
@@ -124,7 +124,7 @@
 ''');
   }
 
-  test_from_noKeyword_typeArg_onConstructorAndLiteral() async {
+  Future<void> test_from_noKeyword_typeArg_onConstructorAndLiteral() async {
     await resolveTestUnit('''
 var s = /*LINT*/Set<int>.from(<num>[2, 3]);
 ''');
@@ -133,7 +133,7 @@
 ''');
   }
 
-  test_from_noKeyword_typeArg_onLiteral() async {
+  Future<void> test_from_noKeyword_typeArg_onLiteral() async {
     await resolveTestUnit('''
 var s = /*LINT*/Set.from(<int>[2, 3]);
 ''');
@@ -142,7 +142,7 @@
 ''');
   }
 
-  test_from_nonEmpty() async {
+  Future<void> test_from_nonEmpty() async {
     await resolveTestUnit('''
 var s = /*LINT*/Set.from([2, 3]);
 ''');
@@ -151,7 +151,7 @@
 ''');
   }
 
-  test_from_notALiteral() async {
+  Future<void> test_from_notALiteral() async {
     await resolveTestUnit('''
 var l = [1];
 Set s = /*LINT*/new Set.from(l);
@@ -159,7 +159,7 @@
     await assertNoFix();
   }
 
-  test_from_trailingComma() async {
+  Future<void> test_from_trailingComma() async {
     await resolveTestUnit('''
 var s = /*LINT*/Set.from([2, 3,]);
 ''');
@@ -168,7 +168,7 @@
 ''');
   }
 
-  test_toSet_empty() async {
+  Future<void> test_toSet_empty() async {
     await resolveTestUnit('''
 var s = /*LINT*/[].toSet();
 ''');
@@ -177,7 +177,7 @@
 ''');
   }
 
-  test_toSet_empty_typeArg() async {
+  Future<void> test_toSet_empty_typeArg() async {
     await resolveTestUnit('''
 var s = /*LINT*/<int>[].toSet();
 ''');
@@ -186,7 +186,7 @@
 ''');
   }
 
-  test_toSet_nonEmpty() async {
+  Future<void> test_toSet_nonEmpty() async {
     await resolveTestUnit('''
 var s = /*LINT*/[2, 3].toSet();
 ''');
@@ -195,7 +195,7 @@
 ''');
   }
 
-  test_toSet_nonEmpty_typeArg() async {
+  Future<void> test_toSet_nonEmpty_typeArg() async {
     await resolveTestUnit('''
 var s = /*LINT*/<int>[2, 3].toSet();
 ''');
@@ -204,7 +204,7 @@
 ''');
   }
 
-  test_toSet_notALiteral() async {
+  Future<void> test_toSet_notALiteral() async {
     await resolveTestUnit('''
 var l = [];
 var s = /*LINT*/l.toSet();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_single_quoted_string_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_single_quoted_string_test.dart
index 610b82d..5899c01 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_single_quoted_string_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_single_quoted_string_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToSingleQuotedStringTest);
   });
@@ -24,7 +24,7 @@
   String get lintCode => LintNames.prefer_single_quotes;
 
   /// More coverage in the `convert_to_single_quoted_string_test.dart` assist test.
-  test_one_simple() async {
+  Future<void> test_one_simple() async {
     await resolveTestUnit('''
 main() {
   print(/*LINT*/"abc");
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_spread_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_spread_test.dart
index a2cf96e..089c9db 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_spread_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_spread_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToSpreadTest);
   });
@@ -24,7 +24,7 @@
   String get lintCode => LintNames.prefer_spread_collections;
 
   /// More coverage in the `convert_to_spread_test.dart` assist test.
-  test_addAll_expression() async {
+  Future<void> test_addAll_expression() async {
     await resolveTestUnit('''
 f() {
   var ints = [1, 2, 3];
diff --git a/pkg/analysis_server/test/src/services/correction/fix/convert_to_where_type_test.dart b/pkg/analysis_server/test/src/services/correction/fix/convert_to_where_type_test.dart
index c7e8f40..847c04a 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/convert_to_where_type_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/convert_to_where_type_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertToWhereTypeTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_iterable_whereType;
 
-  test_default_declaredType() async {
+  Future<void> test_default_declaredType() async {
     await resolveTestUnit('''
 Iterable<C> f(List<Object> list) {
   return list./*LINT*/where((e) => e is C);
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_class_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_class_test.dart
index 610c742..5a0c97c 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_class_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_class_test.dart
@@ -10,7 +10,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateClassTest);
   });
@@ -21,7 +21,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_CLASS;
 
-  test_hasUnresolvedPrefix() async {
+  Future<void> test_hasUnresolvedPrefix() async {
     await resolveTestUnit('''
 main() {
   prefix.Test v = null;
@@ -31,7 +31,7 @@
     await assertNoFix();
   }
 
-  test_inLibraryOfPrefix() async {
+  Future<void> test_inLibraryOfPrefix() async {
     addSource('/home/test/lib/lib.dart', r'''
 class A {}
 ''');
@@ -55,7 +55,7 @@
     expect(change.linkedEditGroups, hasLength(1));
   }
 
-  test_innerLocalFunction() async {
+  Future<void> test_innerLocalFunction() async {
     await resolveTestUnit('''
 f() {
   g() {
@@ -80,7 +80,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['Test v =', 'Test {']);
   }
 
-  test_instanceCreation_withoutNew_fromFunction() async {
+  Future<void> test_instanceCreation_withoutNew_fromFunction() async {
     await resolveTestUnit('''
 main() {
   Test ();
@@ -97,7 +97,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['Test ()', 'Test {']);
   }
 
-  test_instanceCreation_withoutNew_fromMethod() async {
+  Future<void> test_instanceCreation_withoutNew_fromMethod() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -118,7 +118,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['Test ()', 'Test {']);
   }
 
-  test_itemOfList() async {
+  Future<void> test_itemOfList() async {
     await resolveTestUnit('''
 main() {
   var a = [Test];
@@ -137,7 +137,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['Test];', 'Test {']);
   }
 
-  test_itemOfList_inAnnotation() async {
+  Future<void> test_itemOfList_inAnnotation() async {
     await resolveTestUnit('''
 class MyAnnotation {
   const MyAnnotation(a, b);
@@ -160,7 +160,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['Test])', 'Test {']);
   }
 
-  test_simple() async {
+  Future<void> test_simple() async {
     await resolveTestUnit('''
 main() {
   Test v = null;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_constructor_for_final_fields_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_constructor_for_final_fields_test.dart
index fa355b6..741a585 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_constructor_for_final_fields_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_constructor_for_final_fields_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateConstructorForFinalFieldsTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_CONSTRUCTOR_FOR_FINAL_FIELDS;
 
-  test_flutter() async {
+  Future<void> test_flutter() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -45,7 +45,7 @@
     });
   }
 
-  test_flutter_childLast() async {
+  Future<void> test_flutter_childLast() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -71,7 +71,7 @@
     });
   }
 
-  test_flutter_childrenLast() async {
+  Future<void> test_flutter_childrenLast() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
@@ -97,7 +97,7 @@
     });
   }
 
-  test_inTopLevelMethod() async {
+  Future<void> test_inTopLevelMethod() async {
     await resolveTestUnit('''
 main() {
   final int v;
@@ -107,7 +107,7 @@
     await assertNoFix();
   }
 
-  test_simple() async {
+  Future<void> test_simple() async {
     await resolveTestUnit('''
 class Test {
   final int a;
@@ -128,7 +128,7 @@
     });
   }
 
-  test_topLevelField() async {
+  Future<void> test_topLevelField() async {
     await resolveTestUnit('''
 final int v;
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_constructor_super_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_constructor_super_test.dart
index 0dd5c45..77e3e05 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_constructor_super_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_constructor_super_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateConstructorSuperTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_CONSTRUCTOR_SUPER;
 
-  test_fieldInitializer() async {
+  Future<void> test_fieldInitializer() async {
     await resolveTestUnit('''
 class A {
   int _field;
@@ -48,7 +48,7 @@
 ''');
   }
 
-  test_importType() async {
+  Future<void> test_importType() async {
     addSource('/home/test/lib/a.dart', r'''
 class A {}
 ''');
@@ -75,7 +75,7 @@
 ''');
   }
 
-  test_named() async {
+  Future<void> test_named() async {
     await resolveTestUnit('''
 class A {
   A.named(p1, int p2);
@@ -100,7 +100,7 @@
 ''');
   }
 
-  test_optional() async {
+  Future<void> test_optional() async {
     await resolveTestUnit('''
 class A {
   A(p1, int p2, List<String> p3, [int p4]);
@@ -125,7 +125,7 @@
 ''');
   }
 
-  test_private() async {
+  Future<void> test_private() async {
     await resolveTestUnit('''
 class A {
   A._named(p); // ignore: unused_element
@@ -136,7 +136,7 @@
     await assertNoFix();
   }
 
-  test_typeArgument() async {
+  Future<void> test_typeArgument() async {
     await resolveTestUnit('''
 class C<T> {
   final T x;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_constructor_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_constructor_test.dart
index c847a3d..83eb64c 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_constructor_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_constructor_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateConstructorTest);
     defineReflectiveTests(CreateConstructorMixinTest);
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_CONSTRUCTOR;
 
-  test_named() async {
+  Future<void> test_named() async {
     await resolveTestUnit('''
 mixin M {}
 
@@ -39,7 +39,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_CONSTRUCTOR;
 
-  test_inLibrary_insteadOfSyntheticDefault() async {
+  Future<void> test_inLibrary_insteadOfSyntheticDefault() async {
     var a = newFile('/home/test/lib/a.dart', content: '''
 /// $_text200
 class A {}
@@ -59,7 +59,7 @@
 ''', target: a);
   }
 
-  test_inLibrary_named() async {
+  Future<void> test_inLibrary_named() async {
     var a = newFile('/home/test/lib/a.dart', content: '''
 /// $_text200
 class A {}
@@ -79,7 +79,7 @@
 ''', target: a);
   }
 
-  test_insteadOfSyntheticDefault() async {
+  Future<void> test_insteadOfSyntheticDefault() async {
     await resolveTestUnit('''
 class A {
   int field;
@@ -104,7 +104,7 @@
 ''');
   }
 
-  test_named() async {
+  Future<void> test_named() async {
     await resolveTestUnit('''
 class A {
   method() {}
@@ -126,7 +126,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['named(int ', 'named(1']);
   }
 
-  test_named_emptyClassBody() async {
+  Future<void> test_named_emptyClassBody() async {
     await resolveTestUnit('''
 class A {}
 main() {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_field_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_field_test.dart
index b0fad28..ff6b144 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_field_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_field_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateFieldTest);
     defineReflectiveTests(CreateFieldMixinTest);
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_FIELD;
 
-  test_getter_qualified_instance() async {
+  Future<void> test_getter_qualified_instance() async {
     await resolveTestUnit('''
 mixin M {
 }
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_setter_qualified_instance_hasField() async {
+  Future<void> test_setter_qualified_instance_hasField() async {
     await resolveTestUnit('''
 mixin M {
   int aaa;
@@ -77,7 +77,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_FIELD;
 
-  test_getter_multiLevel() async {
+  Future<void> test_getter_multiLevel() async {
     await resolveTestUnit('''
 class A {
 }
@@ -109,7 +109,7 @@
 ''');
   }
 
-  test_getter_qualified_instance() async {
+  Future<void> test_getter_qualified_instance() async {
     await resolveTestUnit('''
 class A {
 }
@@ -129,7 +129,7 @@
 ''');
   }
 
-  test_getter_qualified_instance_differentLibrary() async {
+  Future<void> test_getter_qualified_instance_differentLibrary() async {
     addSource('/home/test/lib/other.dart', '''
 /**
  * A comment to push the offset of the braces for the following class
@@ -163,7 +163,7 @@
 ''', target: '/home/test/lib/other.dart');
   }
 
-  test_getter_qualified_instance_dynamicType() async {
+  Future<void> test_getter_qualified_instance_dynamicType() async {
     await resolveTestUnit('''
 class A {
   B b;
@@ -187,7 +187,7 @@
 ''');
   }
 
-  test_getter_qualified_propagatedType() async {
+  Future<void> test_getter_qualified_propagatedType() async {
     await resolveTestUnit('''
 class A {
   A get self => this;
@@ -212,7 +212,7 @@
 ''');
   }
 
-  test_getter_unqualified_instance_asInvocationArgument() async {
+  Future<void> test_getter_unqualified_instance_asInvocationArgument() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -233,7 +233,7 @@
 ''');
   }
 
-  test_getter_unqualified_instance_assignmentRhs() async {
+  Future<void> test_getter_unqualified_instance_assignmentRhs() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -254,7 +254,7 @@
 ''');
   }
 
-  test_getter_unqualified_instance_asStatement() async {
+  Future<void> test_getter_unqualified_instance_asStatement() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -273,7 +273,7 @@
 ''');
   }
 
-  test_hint() async {
+  Future<void> test_hint() async {
     await resolveTestUnit('''
 class A {
 }
@@ -295,7 +295,7 @@
 ''');
   }
 
-  test_hint_setter() async {
+  Future<void> test_hint_setter() async {
     await resolveTestUnit('''
 class A {
 }
@@ -315,7 +315,7 @@
 ''');
   }
 
-  test_importType() async {
+  Future<void> test_importType() async {
     addSource('/home/test/lib/a.dart', r'''
 class A {}
 ''');
@@ -351,7 +351,7 @@
 ''');
   }
 
-  test_inEnum() async {
+  Future<void> test_inEnum() async {
     await resolveTestUnit('''
 enum MyEnum {
   AAA, BBB
@@ -363,7 +363,7 @@
     await assertNoFix();
   }
 
-  test_inSDK() async {
+  Future<void> test_inSDK() async {
     await resolveTestUnit('''
 main(List p) {
   p.foo = 1;
@@ -372,7 +372,7 @@
     await assertNoFix();
   }
 
-  test_invalidInitializer_withoutType() async {
+  Future<void> test_invalidInitializer_withoutType() async {
     await resolveTestUnit('''
 class C {
   C(this.text);
@@ -387,7 +387,7 @@
 ''');
   }
 
-  test_invalidInitializer_withType() async {
+  Future<void> test_invalidInitializer_withType() async {
     await resolveTestUnit('''
 class C {
   C(String this.text);
@@ -402,7 +402,7 @@
 ''');
   }
 
-  test_setter_generic_BAD() async {
+  Future<void> test_setter_generic_BAD() async {
     await resolveTestUnit('''
 class A {
 }
@@ -426,7 +426,7 @@
 ''');
   }
 
-  test_setter_generic_OK_local() async {
+  Future<void> test_setter_generic_OK_local() async {
     await resolveTestUnit('''
 class A<T> {
   List<T> items;
@@ -449,7 +449,7 @@
 ''');
   }
 
-  test_setter_qualified_instance_hasField() async {
+  Future<void> test_setter_qualified_instance_hasField() async {
     await resolveTestUnit('''
 class A {
   int aaa;
@@ -476,7 +476,7 @@
 ''');
   }
 
-  test_setter_qualified_instance_hasMethod() async {
+  Future<void> test_setter_qualified_instance_hasMethod() async {
     await resolveTestUnit('''
 class A {
   existingMethod() {}
@@ -497,7 +497,7 @@
 ''');
   }
 
-  test_setter_qualified_static() async {
+  Future<void> test_setter_qualified_static() async {
     await resolveTestUnit('''
 class A {
 }
@@ -515,7 +515,7 @@
 ''');
   }
 
-  test_setter_unqualified_instance() async {
+  Future<void> test_setter_unqualified_instance() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -534,7 +534,7 @@
 ''');
   }
 
-  test_setter_unqualified_static() async {
+  Future<void> test_setter_unqualified_static() async {
     await resolveTestUnit('''
 class A {
   static main() {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_file_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_file_test.dart
index 3bb2fd8..af8e317 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_file_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_file_test.dart
@@ -10,7 +10,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateFileTest);
   });
@@ -21,7 +21,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_FILE;
 
-  test_forImport() async {
+  Future<void> test_forImport() async {
     await resolveTestUnit('''
 import 'my_file.dart';
 ''');
@@ -39,14 +39,14 @@
     );
   }
 
-  test_forImport_BAD_notDart() async {
+  Future<void> test_forImport_BAD_notDart() async {
     await resolveTestUnit('''
 import 'my_file.txt';
 ''');
     await assertNoFix();
   }
 
-  test_forImport_inPackage_lib() async {
+  Future<void> test_forImport_inPackage_lib() async {
     await resolveTestUnit('''
 import 'a/bb/my_lib.dart';
 ''');
@@ -64,7 +64,7 @@
     );
   }
 
-  test_forImport_inPackage_test() async {
+  Future<void> test_forImport_inPackage_test() async {
     testFile = convertPath('/home/test/test/test.dart');
     await resolveTestUnit('''
 import 'a/bb/my_lib.dart';
@@ -83,7 +83,7 @@
     );
   }
 
-  test_forPart() async {
+  Future<void> test_forPart() async {
     await resolveTestUnit('''
 library my.lib;
 part 'my_part.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_function_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_function_test.dart
index 36c8426..e7bb640 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_function_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_function_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateFunctionTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_FUNCTION;
 
-  assert_returnType_bool(String lineWithTest) async {
+  Future<void> assert_returnType_bool(String lineWithTest) async {
     await resolveTestUnit('''
 main() {
   bool b = true;
@@ -40,7 +40,7 @@
 ''');
   }
 
-  test_bottomArgument() async {
+  Future<void> test_bottomArgument() async {
     await resolveTestUnit('''
 main() {
   test(throw 42);
@@ -56,7 +56,7 @@
 ''');
   }
 
-  test_duplicateArgumentNames() async {
+  Future<void> test_duplicateArgumentNames() async {
     await resolveTestUnit('''
 class C {
   int x;
@@ -80,7 +80,7 @@
 ''');
   }
 
-  test_dynamicArgument() async {
+  Future<void> test_dynamicArgument() async {
     await resolveTestUnit('''
 main() {
   dynamic v;
@@ -98,7 +98,7 @@
 ''');
   }
 
-  test_dynamicReturnType() async {
+  Future<void> test_dynamicReturnType() async {
     await resolveTestUnit('''
 main() {
   dynamic v = test();
@@ -116,7 +116,7 @@
 ''');
   }
 
-  test_fromFunction() async {
+  Future<void> test_fromFunction() async {
     await resolveTestUnit('''
 main() {
   int v = myUndefinedFunction(1, 2.0, '3');
@@ -134,7 +134,7 @@
 ''');
   }
 
-  test_fromMethod() async {
+  Future<void> test_fromMethod() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -156,7 +156,7 @@
 ''');
   }
 
-  test_functionType_cascadeSecond() async {
+  Future<void> test_functionType_cascadeSecond() async {
     await resolveTestUnit('''
 class A {
   B ma() => null;
@@ -188,7 +188,7 @@
 ''');
   }
 
-  test_functionType_coreFunction() async {
+  Future<void> test_functionType_coreFunction() async {
     await resolveTestUnit('''
 main() {
   useFunction(g: test);
@@ -206,7 +206,7 @@
 ''');
   }
 
-  test_functionType_dynamicArgument() async {
+  Future<void> test_functionType_dynamicArgument() async {
     await resolveTestUnit('''
 main() {
   useFunction(test);
@@ -224,7 +224,7 @@
 ''');
   }
 
-  test_functionType_function() async {
+  Future<void> test_functionType_function() async {
     await resolveTestUnit('''
 main() {
   useFunction(test);
@@ -242,7 +242,7 @@
 ''');
   }
 
-  test_functionType_function_namedArgument() async {
+  Future<void> test_functionType_function_namedArgument() async {
     await resolveTestUnit('''
 main() {
   useFunction(g: test);
@@ -260,7 +260,7 @@
 ''');
   }
 
-  test_functionType_importType() async {
+  Future<void> test_functionType_importType() async {
     addSource('/home/test/lib/a.dart', r'''
 class A {}
 ''');
@@ -289,7 +289,7 @@
 ''');
   }
 
-  test_functionType_notFunctionType() async {
+  Future<void> test_functionType_notFunctionType() async {
     await resolveTestUnit('''
 main(A a) {
   useFunction(a.test);
@@ -300,7 +300,7 @@
     await assertNoFix();
   }
 
-  test_generic_type() async {
+  Future<void> test_generic_type() async {
     await resolveTestUnit('''
 class A {
   List<int> items;
@@ -327,7 +327,7 @@
             ['List<int>', 'Iterable<int>', 'Object']));
   }
 
-  test_generic_typeParameter() async {
+  Future<void> test_generic_typeParameter() async {
     await resolveTestUnit('''
 class A<T> {
   Map<int, T> items;
@@ -349,7 +349,7 @@
 ''');
   }
 
-  test_importType() async {
+  Future<void> test_importType() async {
     addSource('/home/test/lib/lib.dart', r'''
 library lib;
 import 'dart:async';
@@ -372,7 +372,7 @@
 ''');
   }
 
-  test_nullArgument() async {
+  Future<void> test_nullArgument() async {
     await resolveTestUnit('''
 main() {
   test(null);
@@ -388,43 +388,43 @@
 ''');
   }
 
-  test_returnType_bool_and_left() async {
+  Future<void> test_returnType_bool_and_left() async {
     await assert_returnType_bool('test() && b;');
   }
 
-  test_returnType_bool_and_right() async {
+  Future<void> test_returnType_bool_and_right() async {
     await assert_returnType_bool('b && test();');
   }
 
-  test_returnType_bool_assert() async {
+  Future<void> test_returnType_bool_assert() async {
     await assert_returnType_bool('assert ( test() );');
   }
 
-  test_returnType_bool_do() async {
+  Future<void> test_returnType_bool_do() async {
     await assert_returnType_bool('do {} while ( test() );');
   }
 
-  test_returnType_bool_if() async {
+  Future<void> test_returnType_bool_if() async {
     await assert_returnType_bool('if ( test() ) {}');
   }
 
-  test_returnType_bool_or_left() async {
+  Future<void> test_returnType_bool_or_left() async {
     await assert_returnType_bool('test() || b;');
   }
 
-  test_returnType_bool_or_right() async {
+  Future<void> test_returnType_bool_or_right() async {
     await assert_returnType_bool('b || test();');
   }
 
-  test_returnType_bool_unaryNegation() async {
+  Future<void> test_returnType_bool_unaryNegation() async {
     await assert_returnType_bool('!test();');
   }
 
-  test_returnType_bool_while() async {
+  Future<void> test_returnType_bool_while() async {
     await assert_returnType_bool('while ( test() ) {}');
   }
 
-  test_returnType_fromAssignment_eq() async {
+  Future<void> test_returnType_fromAssignment_eq() async {
     await resolveTestUnit('''
 main() {
   int v;
@@ -444,7 +444,7 @@
 ''');
   }
 
-  test_returnType_fromAssignment_plusEq() async {
+  Future<void> test_returnType_fromAssignment_plusEq() async {
     await resolveTestUnit('''
 main() {
   int v;
@@ -464,7 +464,7 @@
 ''');
   }
 
-  test_returnType_fromBinary_right() async {
+  Future<void> test_returnType_fromBinary_right() async {
     await resolveTestUnit('''
 main() {
   0 + myUndefinedFunction();
@@ -480,7 +480,7 @@
 ''');
   }
 
-  test_returnType_fromInitializer() async {
+  Future<void> test_returnType_fromInitializer() async {
     await resolveTestUnit('''
 main() {
   int v = myUndefinedFunction();
@@ -498,7 +498,7 @@
 ''');
   }
 
-  test_returnType_fromInvocationArgument() async {
+  Future<void> test_returnType_fromInvocationArgument() async {
     await resolveTestUnit('''
 foo(int p) {}
 main() {
@@ -516,7 +516,7 @@
 ''');
   }
 
-  test_returnType_fromReturn() async {
+  Future<void> test_returnType_fromReturn() async {
     await resolveTestUnit('''
 int main() {
   return myUndefinedFunction();
@@ -532,7 +532,7 @@
 ''');
   }
 
-  test_returnType_void() async {
+  Future<void> test_returnType_void() async {
     await resolveTestUnit('''
 main() {
   myUndefinedFunction();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_getter_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_getter_test.dart
index bf58fc7..f7d0fb6 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_getter_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_getter_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateGetterTest);
     defineReflectiveTests(CreateGetterMixinTest);
@@ -21,7 +21,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_GETTER;
 
-  test_qualified_instance() async {
+  Future<void> test_qualified_instance() async {
     await resolveTestUnit('''
 mixin M {
 }
@@ -43,7 +43,7 @@
 ''');
   }
 
-  test_unqualified_instance_assignmentLhs() async {
+  Future<void> test_unqualified_instance_assignmentLhs() async {
     await resolveTestUnit('''
 mixin M {
   main() {
@@ -54,7 +54,7 @@
     await assertNoFix();
   }
 
-  test_unqualified_instance_assignmentRhs() async {
+  Future<void> test_unqualified_instance_assignmentRhs() async {
     await resolveTestUnit('''
 mixin M {
   main() {
@@ -81,7 +81,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_GETTER;
 
-  test_hint_getter() async {
+  Future<void> test_hint_getter() async {
     await resolveTestUnit('''
 class A {
 }
@@ -103,7 +103,7 @@
 ''');
   }
 
-  test_inSDK() async {
+  Future<void> test_inSDK() async {
     await resolveTestUnit('''
 main(List p) {
   int v = p.foo;
@@ -113,7 +113,7 @@
     await assertNoFix();
   }
 
-  test_location_afterLastGetter() async {
+  Future<void> test_location_afterLastGetter() async {
     await resolveTestUnit('''
 class A {
   int existingField;
@@ -144,7 +144,7 @@
 ''');
   }
 
-  test_multiLevel() async {
+  Future<void> test_multiLevel() async {
     await resolveTestUnit('''
 class A {
 }
@@ -176,7 +176,7 @@
 ''');
   }
 
-  test_qualified_instance() async {
+  Future<void> test_qualified_instance() async {
     await resolveTestUnit('''
 class A {
 }
@@ -196,7 +196,7 @@
 ''');
   }
 
-  test_qualified_instance_differentLibrary() async {
+  Future<void> test_qualified_instance_differentLibrary() async {
     addSource('/home/test/lib/other.dart', '''
 /**
  * A comment to push the offset of the braces for the following class
@@ -230,7 +230,7 @@
 ''', target: '/home/test/lib/other.dart');
   }
 
-  test_qualified_instance_dynamicType() async {
+  Future<void> test_qualified_instance_dynamicType() async {
     await resolveTestUnit('''
 class A {
   B b;
@@ -254,7 +254,7 @@
 ''');
   }
 
-  test_qualified_propagatedType() async {
+  Future<void> test_qualified_propagatedType() async {
     await resolveTestUnit('''
 class A {
   A get self => this;
@@ -279,7 +279,7 @@
 ''');
   }
 
-  test_setterContext() async {
+  Future<void> test_setterContext() async {
     await resolveTestUnit('''
 class A {
 }
@@ -290,7 +290,7 @@
     await assertNoFix();
   }
 
-  test_unqualified_instance_asInvocationArgument() async {
+  Future<void> test_unqualified_instance_asInvocationArgument() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -311,7 +311,7 @@
 ''');
   }
 
-  test_unqualified_instance_assignmentLhs() async {
+  Future<void> test_unqualified_instance_assignmentLhs() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -322,7 +322,7 @@
     await assertNoFix();
   }
 
-  test_unqualified_instance_assignmentRhs() async {
+  Future<void> test_unqualified_instance_assignmentRhs() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -343,7 +343,7 @@
 ''');
   }
 
-  test_unqualified_instance_asStatement() async {
+  Future<void> test_unqualified_instance_asStatement() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -374,7 +374,7 @@
     super.setUp();
   }
 
-  test_internal_instance() async {
+  Future<void> test_internal_instance() async {
     await resolveTestUnit('''
 extension E on String {
   int m()  => g;
@@ -389,7 +389,7 @@
 ''');
   }
 
-  test_internal_static() async {
+  Future<void> test_internal_static() async {
     await resolveTestUnit('''
 extension E on String {
   static int m()  => g;
@@ -404,7 +404,7 @@
 ''');
   }
 
-  test_override() async {
+  Future<void> test_override() async {
     await resolveTestUnit('''
 extension E on String {
 }
@@ -426,7 +426,7 @@
 ''');
   }
 
-  test_static() async {
+  Future<void> test_static() async {
     await resolveTestUnit('''
 extension E on String {
 }
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_local_variable_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_local_variable_test.dart
index 933eec9..b632fa0 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_local_variable_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_local_variable_test.dart
@@ -10,7 +10,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateLocalVariableTest);
   });
@@ -21,7 +21,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_LOCAL_VARIABLE;
 
-  test_functionType_named() async {
+  Future<void> test_functionType_named() async {
     await resolveTestUnit('''
 typedef MY_FUNCTION(int p);
 foo(MY_FUNCTION f) {}
@@ -39,7 +39,7 @@
 ''');
   }
 
-  test_functionType_named_generic() async {
+  Future<void> test_functionType_named_generic() async {
     await resolveTestUnit('''
 typedef MY_FUNCTION<T>(T p);
 foo(MY_FUNCTION<int> f) {}
@@ -57,7 +57,7 @@
 ''');
   }
 
-  test_functionType_synthetic() async {
+  Future<void> test_functionType_synthetic() async {
     await resolveTestUnit('''
 foo(f(int p)) {}
 main() {
@@ -73,7 +73,7 @@
 ''');
   }
 
-  test_read_typeAssignment() async {
+  Future<void> test_read_typeAssignment() async {
     await resolveTestUnit('''
 main() {
   int a = test;
@@ -89,7 +89,7 @@
 ''');
   }
 
-  test_read_typeCondition() async {
+  Future<void> test_read_typeCondition() async {
     await resolveTestUnit('''
 main() {
   if (!test) {
@@ -107,7 +107,7 @@
 ''');
   }
 
-  test_read_typeInvocationArgument() async {
+  Future<void> test_read_typeInvocationArgument() async {
     await resolveTestUnit('''
 main() {
   f(test);
@@ -125,7 +125,7 @@
     assertLinkedGroup(change.linkedEditGroups[1], ['test;', 'test);']);
   }
 
-  test_read_typeInvocationTarget() async {
+  Future<void> test_read_typeInvocationTarget() async {
     await resolveTestUnit('''
 main() {
   test.add('hello');
@@ -140,7 +140,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['test;', 'test.add(']);
   }
 
-  test_withImport() async {
+  Future<void> test_withImport() async {
     addPackageFile('pkg', 'a/a.dart', '''
 class A {}
 ''');
@@ -189,7 +189,7 @@
     expect(groupPositions[1].offset, 128);
   }
 
-  test_write_assignment() async {
+  Future<void> test_write_assignment() async {
     await resolveTestUnit('''
 main() {
   test = 42;
@@ -202,7 +202,7 @@
 ''');
   }
 
-  test_write_assignment_compound() async {
+  Future<void> test_write_assignment_compound() async {
     await resolveTestUnit('''
 main() {
   test += 42;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_method_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_method_test.dart
index e6800eb..fd279c4 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_method_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_method_test.dart
@@ -10,7 +10,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateMethodTest);
     defineReflectiveTests(CreateMethodMixinTest);
@@ -27,7 +27,7 @@
   @override
   String get lintCode => LintNames.hash_and_equals;
 
-  test_equals() async {
+  Future<void> test_equals() async {
     await resolveTestUnit('''
 class C {
   @override
@@ -48,7 +48,7 @@
 ''');
   }
 
-  test_hashCode() async {
+  Future<void> test_hashCode() async {
     await resolveTestUnit('''
 class C {
   @override
@@ -74,7 +74,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_METHOD;
 
-  test_createQualified_instance() async {
+  Future<void> test_createQualified_instance() async {
     await resolveTestUnit('''
 mixin M {}
 
@@ -93,7 +93,7 @@
 ''');
   }
 
-  test_createQualified_static() async {
+  Future<void> test_createQualified_static() async {
     await resolveTestUnit('''
 mixin M {}
 
@@ -112,7 +112,7 @@
 ''');
   }
 
-  test_createUnqualified() async {
+  Future<void> test_createUnqualified() async {
     await resolveTestUnit('''
 mixin M {
   main() {
@@ -131,7 +131,7 @@
 ''');
   }
 
-  test_functionType_method_enclosingMixin_static() async {
+  Future<void> test_functionType_method_enclosingMixin_static() async {
     await resolveTestUnit('''
 mixin M {
   static foo() {
@@ -155,7 +155,7 @@
 ''');
   }
 
-  test_functionType_method_targetMixin() async {
+  Future<void> test_functionType_method_targetMixin() async {
     await resolveTestUnit('''
 main(M m) {
   useFunction(m.test);
@@ -186,7 +186,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_METHOD;
 
-  test_createQualified_emptyClassBody() async {
+  Future<void> test_createQualified_emptyClassBody() async {
     await resolveTestUnit('''
 class A {}
 main() {
@@ -203,7 +203,7 @@
 ''');
   }
 
-  test_createQualified_fromClass() async {
+  Future<void> test_createQualified_fromClass() async {
     await resolveTestUnit('''
 class A {
 }
@@ -221,7 +221,7 @@
 ''');
   }
 
-  test_createQualified_fromClass_hasOtherMember() async {
+  Future<void> test_createQualified_fromClass_hasOtherMember() async {
     await resolveTestUnit('''
 class A {
   foo() {}
@@ -242,7 +242,7 @@
 ''');
   }
 
-  test_createQualified_fromInstance() async {
+  Future<void> test_createQualified_fromInstance() async {
     await resolveTestUnit('''
 class A {
 }
@@ -260,7 +260,7 @@
 ''');
   }
 
-  test_createQualified_targetIsFunctionType() async {
+  Future<void> test_createQualified_targetIsFunctionType() async {
     await resolveTestUnit('''
 typedef A();
 main() {
@@ -270,7 +270,7 @@
     await assertNoFix();
   }
 
-  test_createQualified_targetIsUnresolved() async {
+  Future<void> test_createQualified_targetIsUnresolved() async {
     await resolveTestUnit('''
 main() {
   NoSuchClass.myUndefinedMethod();
@@ -279,7 +279,7 @@
     await assertNoFix();
   }
 
-  test_createUnqualified_duplicateArgumentNames() async {
+  Future<void> test_createUnqualified_duplicateArgumentNames() async {
     await resolveTestUnit('''
 class C {
   int x;
@@ -304,7 +304,7 @@
 }''');
   }
 
-  test_createUnqualified_parameters() async {
+  Future<void> test_createUnqualified_parameters() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -347,7 +347,7 @@
     assertLinkedGroup(change.linkedEditGroups[index++], ['s)']);
   }
 
-  test_createUnqualified_parameters_named() async {
+  Future<void> test_createUnqualified_parameters_named() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -388,7 +388,7 @@
             ['String', 'Object', 'Comparable<String>', 'Pattern']));
   }
 
-  test_createUnqualified_returnType() async {
+  Future<void> test_createUnqualified_returnType() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -413,7 +413,7 @@
         ['myUndefinedMethod();', 'myUndefinedMethod() {']);
   }
 
-  test_createUnqualified_staticFromField() async {
+  Future<void> test_createUnqualified_staticFromField() async {
     await resolveTestUnit('''
 class A {
   static var f = myUndefinedMethod();
@@ -428,7 +428,7 @@
 ''');
   }
 
-  test_createUnqualified_staticFromMethod() async {
+  Future<void> test_createUnqualified_staticFromMethod() async {
     await resolveTestUnit('''
 class A {
   static main() {
@@ -447,7 +447,7 @@
 ''');
   }
 
-  test_functionType_method_enclosingClass_static() async {
+  Future<void> test_functionType_method_enclosingClass_static() async {
     await resolveTestUnit('''
 class A {
   static foo() {
@@ -469,7 +469,7 @@
 ''');
   }
 
-  test_functionType_method_enclosingClass_static2() async {
+  Future<void> test_functionType_method_enclosingClass_static2() async {
     await resolveTestUnit('''
 class A {
   var f;
@@ -489,7 +489,7 @@
 ''');
   }
 
-  test_functionType_method_targetClass() async {
+  Future<void> test_functionType_method_targetClass() async {
     await resolveTestUnit('''
 main(A a) {
   useFunction(a.test);
@@ -510,7 +510,7 @@
 ''');
   }
 
-  test_functionType_method_targetClass_hasOtherMember() async {
+  Future<void> test_functionType_method_targetClass_hasOtherMember() async {
     await resolveTestUnit('''
 main(A a) {
   useFunction(a.test);
@@ -534,7 +534,7 @@
 ''');
   }
 
-  test_functionType_notFunctionType() async {
+  Future<void> test_functionType_notFunctionType() async {
     await resolveTestUnit('''
 main(A a) {
   useFunction(a.test);
@@ -545,7 +545,7 @@
     await assertNoFix();
   }
 
-  test_functionType_unknownTarget() async {
+  Future<void> test_functionType_unknownTarget() async {
     await resolveTestUnit('''
 main(A a) {
   useFunction(a.test);
@@ -557,7 +557,7 @@
     await assertNoFix();
   }
 
-  test_generic_argumentType() async {
+  Future<void> test_generic_argumentType() async {
     await resolveTestUnit('''
 class A<T> {
   B b;
@@ -585,7 +585,7 @@
 ''');
   }
 
-  test_generic_literal() async {
+  Future<void> test_generic_literal() async {
     await resolveTestUnit('''
 class A {
   B b;
@@ -612,7 +612,7 @@
 ''');
   }
 
-  test_generic_local() async {
+  Future<void> test_generic_local() async {
     await resolveTestUnit('''
 class A<T> {
   List<T> items;
@@ -633,7 +633,7 @@
 ''');
   }
 
-  test_generic_returnType() async {
+  Future<void> test_generic_returnType() async {
     await resolveTestUnit('''
 class A<T> {
   main() {
@@ -659,7 +659,7 @@
 ''');
   }
 
-  test_hint_createQualified_fromInstance() async {
+  Future<void> test_hint_createQualified_fromInstance() async {
     await resolveTestUnit('''
 class A {
 }
@@ -679,7 +679,7 @@
 ''');
   }
 
-  test_inSDK() async {
+  Future<void> test_inSDK() async {
     await resolveTestUnit('''
 main() {
   List.foo();
@@ -688,7 +688,7 @@
     await assertNoFix();
   }
 
-  test_parameterType_differentPrefixInTargetUnit() async {
+  Future<void> test_parameterType_differentPrefixInTargetUnit() async {
     String code2 = r'''
 import 'test3.dart' as bbb;
 export 'test3.dart';
@@ -721,7 +721,7 @@
 ''', target: '/home/test/lib/test2.dart');
   }
 
-  test_parameterType_inTargetUnit() async {
+  Future<void> test_parameterType_inTargetUnit() async {
     addSource('/home/test/lib/test2.dart', r'''
 class D {
 }
@@ -746,7 +746,7 @@
 ''', target: '/home/test/lib/test2.dart');
   }
 
-  test_targetIsEnum() async {
+  Future<void> test_targetIsEnum() async {
     await resolveTestUnit('''
 enum MyEnum {A, B}
 main() {
@@ -768,7 +768,7 @@
     super.setUp();
   }
 
-  test_internal_instance() async {
+  Future<void> test_internal_instance() async {
     await resolveTestUnit('''
 extension E on String {
   int m() => n();
@@ -783,7 +783,7 @@
 ''');
   }
 
-  test_internal_static() async {
+  Future<void> test_internal_static() async {
     await resolveTestUnit('''
 extension E on String {
   static int m() => n();
@@ -798,7 +798,7 @@
 ''');
   }
 
-  test_override() async {
+  Future<void> test_override() async {
     await resolveTestUnit('''
 extension E on String {}
 
@@ -817,7 +817,7 @@
 ''');
   }
 
-  test_static() async {
+  Future<void> test_static() async {
     await resolveTestUnit('''
 extension E on String {}
 
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_missing_overrides_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_missing_overrides_test.dart
index 20e87d0..fe9c123 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_missing_overrides_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_missing_overrides_test.dart
@@ -10,7 +10,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateMissingOverridesTest);
   });
@@ -21,7 +21,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_MISSING_OVERRIDES;
 
-  test_field_untyped() async {
+  Future<void> test_field_untyped() async {
     await resolveTestUnit('''
 class A {
   var f;
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_functionTypeAlias() async {
+  Future<void> test_functionTypeAlias() async {
     await resolveTestUnit('''
 typedef int Binary(int left, int right);
 
@@ -69,7 +69,7 @@
 ''');
   }
 
-  test_functionTypedParameter() async {
+  Future<void> test_functionTypedParameter() async {
     await resolveTestUnit('''
 abstract class A {
   void forEach(int f(double p1, String p2));
@@ -92,7 +92,7 @@
 ''');
   }
 
-  test_generics_typeArguments() async {
+  Future<void> test_generics_typeArguments() async {
     await resolveTestUnit('''
 class Iterator<T> {
 }
@@ -120,7 +120,7 @@
 ''');
   }
 
-  test_generics_typeParameters() async {
+  Future<void> test_generics_typeParameters() async {
     await resolveTestUnit('''
 abstract class ItemProvider<T> {
   List<T> getItems();
@@ -144,7 +144,7 @@
 ''');
   }
 
-  test_getter() async {
+  Future<void> test_getter() async {
     await resolveTestUnit('''
 abstract class A {
   get g1;
@@ -172,7 +172,7 @@
 ''');
   }
 
-  test_importPrefix() async {
+  Future<void> test_importPrefix() async {
     await resolveTestUnit('''
 import 'dart:async' as aaa;
 abstract class A {
@@ -198,7 +198,7 @@
 ''');
   }
 
-  test_mergeToField_getterSetter() async {
+  Future<void> test_mergeToField_getterSetter() async {
     await resolveTestUnit('''
 class A {
   int ma;
@@ -231,7 +231,7 @@
 ''');
   }
 
-  test_method() async {
+  Future<void> test_method() async {
     await resolveTestUnit('''
 abstract class A {
   void m1();
@@ -309,7 +309,7 @@
     }
   }
 
-  test_method_emptyClassBody() async {
+  Future<void> test_method_emptyClassBody() async {
     await resolveTestUnit('''
 abstract class A {
   void foo();
@@ -331,7 +331,7 @@
 ''');
   }
 
-  test_method_generic() async {
+  Future<void> test_method_generic() async {
     await resolveTestUnit('''
 class C<T> {}
 class V<E> {}
@@ -361,7 +361,7 @@
 ''');
   }
 
-  test_method_generic_withBounds() async {
+  Future<void> test_method_generic_withBounds() async {
     // https://github.com/dart-lang/sdk/issues/31199
     await resolveTestUnit('''
 abstract class A<K, V> {
@@ -386,7 +386,7 @@
 ''');
   }
 
-  test_method_genericClass2() async {
+  Future<void> test_method_genericClass2() async {
     await resolveTestUnit('''
 class A<R> {
   R foo(int a) => null;
@@ -424,7 +424,7 @@
 ''');
   }
 
-  test_method_notEmptyClassBody() async {
+  Future<void> test_method_notEmptyClassBody() async {
     await resolveTestUnit('''
 abstract class A {
   void foo();
@@ -450,7 +450,7 @@
 ''');
   }
 
-  test_operator() async {
+  Future<void> test_operator() async {
     await resolveTestUnit('''
 abstract class A {
   int operator [](int index);
@@ -481,7 +481,7 @@
 ''');
   }
 
-  test_setter() async {
+  Future<void> test_setter() async {
     await resolveTestUnit('''
 abstract class A {
   set s1(x);
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_mixin_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_mixin_test.dart
index 463f417..cfb47a1 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_mixin_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_mixin_test.dart
@@ -10,7 +10,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateMixinTest);
   });
@@ -21,7 +21,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_MIXIN;
 
-  test_hasUnresolvedPrefix() async {
+  Future<void> test_hasUnresolvedPrefix() async {
     await resolveTestUnit('''
 main() {
   prefix.Test v = null;
@@ -31,7 +31,7 @@
     await assertNoFix();
   }
 
-  test_inLibraryOfPrefix() async {
+  Future<void> test_inLibraryOfPrefix() async {
     String libCode = r'''
 class A {}
 ''';
@@ -54,7 +54,7 @@
     expect(change.linkedEditGroups, hasLength(1));
   }
 
-  test_innerLocalFunction() async {
+  Future<void> test_innerLocalFunction() async {
     await resolveTestUnit('''
 f() {
   g() {
@@ -79,7 +79,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['Test v =', 'Test {']);
   }
 
-  test_instanceCreation_withNew() async {
+  Future<void> test_instanceCreation_withNew() async {
     await resolveTestUnit('''
 main() {
   new Test();
@@ -88,7 +88,7 @@
     await assertNoFix();
   }
 
-  test_instanceCreation_withoutNew() async {
+  Future<void> test_instanceCreation_withoutNew() async {
     await resolveTestUnit('''
 main() {
   Test();
@@ -97,7 +97,7 @@
     await assertNoFix();
   }
 
-  test_itemOfList() async {
+  Future<void> test_itemOfList() async {
     await resolveTestUnit('''
 main() {
   var a = [Test];
@@ -116,7 +116,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['Test];', 'Test {']);
   }
 
-  test_itemOfList_inAnnotation() async {
+  Future<void> test_itemOfList_inAnnotation() async {
     await resolveTestUnit('''
 class MyAnnotation {
   const MyAnnotation(a, b);
@@ -139,7 +139,7 @@
     assertLinkedGroup(change.linkedEditGroups[0], ['Test])', 'Test {']);
   }
 
-  test_simple() async {
+  Future<void> test_simple() async {
     await resolveTestUnit('''
 main() {
   Test v = null;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_no_such_method_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_no_such_method_test.dart
index 5799c31..9f904f3 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_no_such_method_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_no_such_method_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateNoSuchMethodTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_NO_SUCH_METHOD;
 
-  test_class() async {
+  Future<void> test_class() async {
     await resolveTestUnit('''
 abstract class A {
   m1();
@@ -44,7 +44,7 @@
 ''');
   }
 
-  test_classTypeAlias() async {
+  Future<void> test_classTypeAlias() async {
     await resolveTestUnit('''
 abstract class A {
   m();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/create_setter_test.dart b/pkg/analysis_server/test/src/services/correction/fix/create_setter_test.dart
index eb1da45..aba94f8 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/create_setter_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/create_setter_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(CreateSetterTest);
     defineReflectiveTests(CreateSetterMixinTest);
@@ -21,7 +21,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_SETTER;
 
-  test_qualified_instance() async {
+  Future<void> test_qualified_instance() async {
     await resolveTestUnit('''
 mixin M {
 }
@@ -41,7 +41,7 @@
 ''');
   }
 
-  test_unqualified_instance_assignmentLhs() async {
+  Future<void> test_unqualified_instance_assignmentLhs() async {
     await resolveTestUnit('''
 mixin M {
   main() {
@@ -60,7 +60,7 @@
 ''');
   }
 
-  test_unqualified_instance_assignmentRhs() async {
+  Future<void> test_unqualified_instance_assignmentRhs() async {
     await resolveTestUnit('''
 mixin M {
   main() {
@@ -77,7 +77,7 @@
   @override
   FixKind get kind => DartFixKind.CREATE_SETTER;
 
-  test_getterContext() async {
+  Future<void> test_getterContext() async {
     await resolveTestUnit('''
 class A {
 }
@@ -88,7 +88,7 @@
     await assertNoFix();
   }
 
-  test_inferredTargetType() async {
+  Future<void> test_inferredTargetType() async {
     await resolveTestUnit('''
 class A {
 }
@@ -108,7 +108,7 @@
 ''');
   }
 
-  test_inSDK() async {
+  Future<void> test_inSDK() async {
     await resolveTestUnit('''
 main(List p) {
   p.foo = 0;
@@ -117,7 +117,7 @@
     await assertNoFix();
   }
 
-  test_location_afterLastAccessor() async {
+  Future<void> test_location_afterLastAccessor() async {
     await resolveTestUnit('''
 class A {
   int existingField;
@@ -146,7 +146,7 @@
 ''');
   }
 
-  test_multiLevel() async {
+  Future<void> test_multiLevel() async {
     await resolveTestUnit('''
 class A {
 }
@@ -176,7 +176,7 @@
 ''');
   }
 
-  test_qualified_instance() async {
+  Future<void> test_qualified_instance() async {
     await resolveTestUnit('''
 class A {
 }
@@ -194,7 +194,7 @@
 ''');
   }
 
-  test_qualified_instance_differentLibrary() async {
+  Future<void> test_qualified_instance_differentLibrary() async {
     addSource('/home/test/lib/other.dart', '''
 /**
  * A comment to push the offset of the braces for the following class
@@ -227,7 +227,7 @@
 ''', target: '/home/test/lib/other.dart');
   }
 
-  test_qualified_instance_dynamicType() async {
+  Future<void> test_qualified_instance_dynamicType() async {
     await resolveTestUnit('''
 class A {
   B b;
@@ -251,7 +251,7 @@
 ''');
   }
 
-  test_qualified_propagatedType() async {
+  Future<void> test_qualified_propagatedType() async {
     await resolveTestUnit('''
 class A {
   A get self => this;
@@ -274,7 +274,7 @@
 ''');
   }
 
-  test_unqualified_instance_assignmentLhs() async {
+  Future<void> test_unqualified_instance_assignmentLhs() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -293,7 +293,7 @@
 ''');
   }
 
-  test_unqualified_instance_assignmentRhs() async {
+  Future<void> test_unqualified_instance_assignmentRhs() async {
     await resolveTestUnit('''
 class A {
   main() {
@@ -316,7 +316,7 @@
     super.setUp();
   }
 
-  test_internal_instance() async {
+  Future<void> test_internal_instance() async {
     await resolveTestUnit('''
 extension E on String {
   int m(int x) => s = x;
@@ -331,7 +331,7 @@
 ''');
   }
 
-  test_internal_static() async {
+  Future<void> test_internal_static() async {
     await resolveTestUnit('''
 extension E on String {
   static int m(int x) => s = x;
@@ -346,7 +346,7 @@
 ''');
   }
 
-  test_override() async {
+  Future<void> test_override() async {
     await resolveTestUnit('''
 extension E on String {
 }
@@ -366,7 +366,7 @@
 ''');
   }
 
-  test_static() async {
+  Future<void> test_static() async {
     await resolveTestUnit('''
 extension E on String {
 }
diff --git a/pkg/analysis_server/test/src/services/correction/fix/extend_class_for_mixin_test.dart b/pkg/analysis_server/test/src/services/correction/fix/extend_class_for_mixin_test.dart
index d65e90a..b713d0e 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/extend_class_for_mixin_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/extend_class_for_mixin_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ExtendClassForMixinTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.EXTEND_CLASS_FOR_MIXIN;
 
-  test_missingClass_withExtends() async {
+  Future<void> test_missingClass_withExtends() async {
     await resolveTestUnit('''
 class A {}
 class B {}
@@ -29,7 +29,7 @@
     await assertNoFix();
   }
 
-  test_missingClass_withoutExtends_withImplements() async {
+  Future<void> test_missingClass_withoutExtends_withImplements() async {
     await resolveTestUnit('''
 class A {}
 class B {}
@@ -44,7 +44,7 @@
 ''');
   }
 
-  test_missingClass_withoutExtends_withoutImplements() async {
+  Future<void> test_missingClass_withoutExtends_withoutImplements() async {
     await resolveTestUnit('''
 class A {}
 mixin M on A {}
@@ -57,7 +57,7 @@
 ''');
   }
 
-  test_missingMixin_withExtends() async {
+  Future<void> test_missingMixin_withExtends() async {
     await resolveTestUnit('''
 class A {}
 mixin M {}
@@ -68,7 +68,7 @@
   }
 
   @failingTest
-  test_missingMixin_withoutExtends() async {
+  Future<void> test_missingMixin_withoutExtends() async {
     await resolveTestUnit('''
 mixin M {}
 mixin N on M {}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/fix_processor.dart b/pkg/analysis_server/test/src/services/correction/fix/fix_processor.dart
index 4f1daf2..7d8cbb1 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/fix_processor.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/fix_processor.dart
@@ -104,7 +104,7 @@
     expect(resultCode, expected);
   }
 
-  assertHasFixAllFix(ErrorCode errorCode, String expected,
+  void assertHasFixAllFix(ErrorCode errorCode, String expected,
       {String target}) async {
     AnalysisError error = await _findErrorToFixOfType(errorCode);
     Fix fix = await _assertHasFixAllFix(error);
diff --git a/pkg/analysis_server/test/src/services/correction/fix/fix_test.dart b/pkg/analysis_server/test/src/services/correction/fix/fix_test.dart
index 655614c..8b2ae57 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/fix_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/fix_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FixTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => fail('kind should not be requested');
 
-  test_malformedTypeTest() async {
+  Future<void> test_malformedTypeTest() async {
     await resolveTestUnit('''
 main(p) {
   p i s Null;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/import_async_test.dart b/pkg/analysis_server/test/src/services/correction/fix/import_async_test.dart
index 7bd9141..592952f 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/import_async_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/import_async_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ImportAsyncTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.IMPORT_ASYNC;
 
-  test_future() async {
+  Future<void> test_future() async {
     updateTestPubspecFile('''
 environment:
   sdk: ^2.0.0
@@ -34,7 +34,7 @@
 ''');
   }
 
-  test_stream() async {
+  Future<void> test_stream() async {
     updateTestPubspecFile('''
 environment:
   sdk: ^2.0.0
diff --git a/pkg/analysis_server/test/src/services/correction/fix/import_library_prefix_test.dart b/pkg/analysis_server/test/src/services/correction/fix/import_library_prefix_test.dart
index 524eee6..d87f1e7 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/import_library_prefix_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/import_library_prefix_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ImportLibraryPrefixTest);
     defineReflectiveTests(ImportLibraryPrefixWithExtensionMethodsTest);
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.IMPORT_LIBRARY_PREFIX;
 
-  test_withClass() async {
+  Future<void> test_withClass() async {
     await resolveTestUnit('''
 import 'dart:collection' as pref;
 main() {
@@ -39,7 +39,7 @@
 ''');
   }
 
-  test_withTopLevelVariable() async {
+  Future<void> test_withTopLevelVariable() async {
     await resolveTestUnit('''
 import 'dart:math' as pref;
 main() {
@@ -68,7 +68,7 @@
     super.setUp();
   }
 
-  test_withExtension() async {
+  Future<void> test_withExtension() async {
     addSource('/home/test/lib/lib.dart', '''
 class C {}
 extension E on int {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/import_library_project_test.dart b/pkg/analysis_server/test/src/services/correction/fix/import_library_project_test.dart
index ed96c20..a2a8902 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/import_library_project_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/import_library_project_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ImportLibraryProject1Test);
     defineReflectiveTests(ImportLibraryProject1WithExtensionMethodsTest);
@@ -21,6 +21,501 @@
 }
 
 @reflectiveTest
+class ImportLibraryProject1Test extends FixProcessorTest {
+  @override
+  FixKind get kind => DartFixKind.IMPORT_LIBRARY_PROJECT1;
+
+  Future<void> test_alreadyImported_package() async {
+    addSource('/home/test/lib/lib.dart', '''
+class A {}
+class B {}
+''');
+    await resolveTestUnit('''
+import 'lib.dart' show A;
+main() {
+  A a;
+  B b;
+  print('\$a \$b');
+}
+''');
+    await assertNoFix();
+  }
+
+  Future<void> test_lib() async {
+    addPackageFile('my_pkg', 'a.dart', 'class Test {}');
+    newFile('/home/test/pubspec.yaml', content: r'''
+dependencies:
+  my_pkg: any
+''');
+
+    await resolveTestUnit('''
+main() {
+  Test test = null;
+  print(test);
+}
+''');
+
+    await assertHasFix('''
+import 'package:my_pkg/a.dart';
+
+main() {
+  Test test = null;
+  print(test);
+}
+''', expectedNumberOfFixesForKind: 1);
+  }
+
+  Future<void> test_lib_src() async {
+    addPackageFile('my_pkg', 'src/a.dart', 'class Test {}');
+    newFile('/home/test/pubspec.yaml', content: r'''
+dependencies:
+  my_pkg: any
+''');
+    await resolveTestUnit('''
+main() {
+  Test test = null;
+  print(test);
+}
+''');
+    await assertNoFix();
+  }
+
+  Future<void> test_notInLib() async {
+    addSource('/home/other/test/lib.dart', 'class Test {}');
+    await resolveTestUnit('''
+main() {
+  Test t;
+  print(t);
+}
+''');
+    await assertNoFix();
+  }
+
+  Future<void> test_relativeDirective() async {
+    addSource('/home/test/lib/a.dart', '''
+class Foo {}
+''');
+    await resolveTestUnit('''
+main() { new Foo(); }
+''');
+    await assertHasFix('''
+import 'a.dart';
+
+main() { new Foo(); }
+''',
+        expectedNumberOfFixesForKind: 2,
+        matchFixMessage: "Import library 'a.dart'");
+  }
+
+  Future<void> test_relativeDirective_downOneDirectory() async {
+    addSource('/home/test/lib/dir/a.dart', '''
+class Foo {}
+''');
+    await resolveTestUnit('''
+main() { new Foo(); }
+''');
+    await assertHasFix('''
+import 'dir/a.dart';
+
+main() { new Foo(); }
+''',
+        expectedNumberOfFixesForKind: 2,
+        matchFixMessage: "Import library 'dir/a.dart'");
+  }
+
+  Future<void> test_relativeDirective_upOneDirectory() async {
+    addSource('/home/test/lib/a.dart', '''
+class Foo {}
+''');
+    testFile = convertPath('/home/test/lib/dir/test.dart');
+    await resolveTestUnit('''
+main() { new Foo(); }
+''');
+    await assertHasFix('''
+import '../a.dart';
+
+main() { new Foo(); }
+''',
+        expectedNumberOfFixesForKind: 2,
+        matchFixMessage: "Import library '../a.dart'");
+  }
+
+  Future<void> test_withClass_annotation() async {
+    addSource('/home/test/lib/lib.dart', '''
+library lib;
+class Test {
+  const Test(int p);
+}
+''');
+    await resolveTestUnit('''
+@Test(0)
+main() {
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+@Test(0)
+main() {
+}
+''');
+  }
+
+  Future<void> test_withClass_hasOtherLibraryWithPrefix() async {
+    addSource('/home/test/lib/a.dart', '''
+library a;
+class One {}
+''');
+    addSource('/home/test/lib/b.dart', '''
+library b;
+class One {}
+class Two {}
+''');
+    await resolveTestUnit('''
+import 'package:test/b.dart' show Two;
+main () {
+  new Two();
+  new One();
+}
+''');
+    await assertHasFix('''
+import 'package:test/a.dart';
+import 'package:test/b.dart' show Two;
+main () {
+  new Two();
+  new One();
+}
+''');
+  }
+
+  Future<void> test_withClass_inParentFolder() async {
+    testFile = convertPath('/home/test/bin/aaa/test.dart');
+    addSource('/home/test/bin/lib.dart', '''
+library lib;
+class Test {}
+''');
+    await resolveTestUnit('''
+main() {
+  Test t = null;
+  print(t);
+}
+''');
+    await assertHasFix('''
+import '../lib.dart';
+
+main() {
+  Test t = null;
+  print(t);
+}
+''');
+  }
+
+  Future<void> test_withClass_inRelativeFolder() async {
+    testFile = convertPath('/home/test/bin/test.dart');
+    addSource('/home/test/tool/sub/folder/lib.dart', '''
+library lib;
+class Test {}
+''');
+    await resolveTestUnit('''
+main() {
+  Test t = null;
+  print(t);
+}
+''');
+    await assertHasFix('''
+import '../tool/sub/folder/lib.dart';
+
+main() {
+  Test t = null;
+  print(t);
+}
+''');
+  }
+
+  Future<void> test_withClass_inSameFolder() async {
+    testFile = convertPath('/home/test/bin/test.dart');
+    addSource('/home/test/bin/lib.dart', '''
+library lib;
+class Test {}
+''');
+    await resolveTestUnit('''
+main() {
+  Test t = null;
+  print(t);
+}
+''');
+    await assertHasFix('''
+import 'lib.dart';
+
+main() {
+  Test t = null;
+  print(t);
+}
+''');
+  }
+
+  Future<void> test_withClass_instanceCreation_const() async {
+    addSource('/home/test/lib/lib.dart', '''
+class Test {
+  const Test();
+}
+''');
+    await resolveTestUnit('''
+main() {
+  return const Test();
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  return const Test();
+}
+''');
+  }
+
+  Future<void> test_withClass_instanceCreation_const_namedConstructor() async {
+    addSource('/home/test/lib/lib.dart', '''
+class Test {
+  const Test.named();
+}
+''');
+    await resolveTestUnit('''
+main() {
+  const Test.named();
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  const Test.named();
+}
+''');
+  }
+
+  Future<void> test_withClass_instanceCreation_implicit() async {
+    addSource('/home/test/lib/lib.dart', '''
+class Test {
+  const Test();
+}
+''');
+    await resolveTestUnit('''
+main() {
+  return Test();
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  return Test();
+}
+''');
+  }
+
+  Future<void> test_withClass_instanceCreation_new() async {
+    addSource('/home/test/lib/lib.dart', '''
+class Test {
+  const Test();
+}
+''');
+    await resolveTestUnit('''
+main() {
+  return new Test();
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  return new Test();
+}
+''');
+  }
+
+  Future<void> test_withClass_instanceCreation_new_namedConstructor() async {
+    addSource('/home/test/lib/lib.dart', '''
+class Test {
+  Test.named();
+}
+''');
+    await resolveTestUnit('''
+main() {
+  new Test.named();
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  new Test.named();
+}
+''');
+  }
+
+  Future<void> test_withFunction() async {
+    addSource('/home/test/lib/lib.dart', '''
+library lib;
+myFunction() {}
+''');
+    await resolveTestUnit('''
+main() {
+  myFunction();
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  myFunction();
+}
+''');
+  }
+
+  Future<void> test_withFunction_functionTopLevelVariable() async {
+    addSource('/home/test/lib/lib.dart', 'var myFunction = () {};');
+    await resolveTestUnit('''
+main() {
+  myFunction();
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  myFunction();
+}
+''');
+  }
+
+  Future<void> test_withFunction_functionTopLevelVariableIdentifier() async {
+    addSource('/home/test/lib/lib.dart', 'var myFunction = () {};');
+    await resolveTestUnit('''
+main() {
+  myFunction;
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  myFunction;
+}
+''');
+  }
+
+  Future<void> test_withFunction_identifier() async {
+    addSource('/home/test/lib/lib.dart', '''
+library lib;
+myFunction() {}
+''');
+    await resolveTestUnit('''
+main() {
+  myFunction;
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  myFunction;
+}
+''');
+  }
+
+  @failingTest
+  Future<void> test_withFunction_nonFunctionType() async {
+    addSource('/home/test/lib/lib.dart', 'int zero = 0;');
+    await resolveTestUnit('''
+main() {
+  zero();
+}
+''');
+    await assertNoFix();
+  }
+
+  Future<void> test_withFunction_unresolvedMethod() async {
+    addSource('/home/test/lib/lib.dart', '''
+library lib;
+myFunction() {}
+''');
+    await resolveTestUnit('''
+class A {
+  main() {
+    myFunction();
+  }
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+class A {
+  main() {
+    myFunction();
+  }
+}
+''');
+  }
+
+  Future<void> test_withFunctionTypeAlias() async {
+    addSource('/home/test/lib/lib.dart', '''
+library lib;
+typedef MyFunction();
+''');
+    await resolveTestUnit('''
+main() {
+  MyFunction t = null;
+  print(t);
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  MyFunction t = null;
+  print(t);
+}
+''');
+  }
+
+  Future<void> test_withMixin() async {
+    addSource('/home/test/lib/lib.dart', '''
+mixin Test {}
+''');
+    await resolveTestUnit('''
+class X = Object with Test;
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+class X = Object with Test;
+''', errorFilter: (error) {
+      return error.errorCode == CompileTimeErrorCode.UNDEFINED_CLASS;
+    });
+  }
+
+  Future<void> test_withTopLevelVariable() async {
+    addSource('/home/test/lib/lib.dart', '''
+library lib;
+int MY_VAR = 42;
+''');
+    await resolveTestUnit('''
+main() {
+  print(MY_VAR);
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+main() {
+  print(MY_VAR);
+}
+''');
+  }
+}
+
+@reflectiveTest
 class ImportLibraryProject1WithExtensionMethodsTest extends FixProcessorTest {
   @override
   FixKind get kind => DartFixKind.IMPORT_LIBRARY_PROJECT1;
@@ -31,7 +526,7 @@
     super.setUp();
   }
 
-  test_lib() async {
+  Future<void> test_lib() async {
     addPackageFile('my_pkg', 'a.dart', '''
 extension E on int {
   static String m() => '';
@@ -59,40 +554,23 @@
 }
 
 @reflectiveTest
-class ImportLibraryProject1Test extends FixProcessorTest {
+class ImportLibraryProject2Test extends FixProcessorTest {
   @override
-  FixKind get kind => DartFixKind.IMPORT_LIBRARY_PROJECT1;
+  FixKind get kind => DartFixKind.IMPORT_LIBRARY_PROJECT2;
 
-  test_alreadyImported_package() async {
-    addSource('/home/test/lib/lib.dart', '''
-class A {}
-class B {}
-''');
-    await resolveTestUnit('''
-import 'lib.dart' show A;
-main() {
-  A a;
-  B b;
-  print('\$a \$b');
-}
-''');
-    await assertNoFix();
-  }
-
-  test_lib() async {
-    addPackageFile('my_pkg', 'a.dart', 'class Test {}');
+  Future<void> test_lib() async {
+    addPackageFile('my_pkg', 'a.dart', "export 'b.dart';");
+    addPackageFile('my_pkg', 'b.dart', 'class Test {}');
     newFile('/home/test/pubspec.yaml', content: r'''
 dependencies:
   my_pkg: any
 ''');
-
     await resolveTestUnit('''
 main() {
   Test test = null;
   print(test);
 }
 ''');
-
     await assertHasFix('''
 import 'package:my_pkg/a.dart';
 
@@ -100,11 +578,12 @@
   Test test = null;
   print(test);
 }
-''', expectedNumberOfFixesForKind: 1);
+''');
   }
 
-  test_lib_src() async {
-    addPackageFile('my_pkg', 'src/a.dart', 'class Test {}');
+  Future<void> test_lib_src() async {
+    addPackageFile('my_pkg', 'a.dart', "export 'src/b.dart';");
+    addPackageFile('my_pkg', 'src/b.dart', 'class Test {}');
     newFile('/home/test/pubspec.yaml', content: r'''
 dependencies:
   my_pkg: any
@@ -115,439 +594,12 @@
   print(test);
 }
 ''');
-    await assertNoFix();
-  }
-
-  test_notInLib() async {
-    addSource('/home/other/test/lib.dart', 'class Test {}');
-    await resolveTestUnit('''
-main() {
-  Test t;
-  print(t);
-}
-''');
-    await assertNoFix();
-  }
-
-  test_relativeDirective() async {
-    addSource('/home/test/lib/a.dart', '''
-class Foo {}
-''');
-    await resolveTestUnit('''
-main() { new Foo(); }
-''');
     await assertHasFix('''
-import 'a.dart';
-
-main() { new Foo(); }
-''',
-        expectedNumberOfFixesForKind: 2,
-        matchFixMessage: "Import library 'a.dart'");
-  }
-
-  test_relativeDirective_downOneDirectory() async {
-    addSource('/home/test/lib/dir/a.dart', '''
-class Foo {}
-''');
-    await resolveTestUnit('''
-main() { new Foo(); }
-''');
-    await assertHasFix('''
-import 'dir/a.dart';
-
-main() { new Foo(); }
-''',
-        expectedNumberOfFixesForKind: 2,
-        matchFixMessage: "Import library 'dir/a.dart'");
-  }
-
-  test_relativeDirective_upOneDirectory() async {
-    addSource('/home/test/lib/a.dart', '''
-class Foo {}
-''');
-    testFile = convertPath('/home/test/lib/dir/test.dart');
-    await resolveTestUnit('''
-main() { new Foo(); }
-''');
-    await assertHasFix('''
-import '../a.dart';
-
-main() { new Foo(); }
-''',
-        expectedNumberOfFixesForKind: 2,
-        matchFixMessage: "Import library '../a.dart'");
-  }
-
-  test_withClass_annotation() async {
-    addSource('/home/test/lib/lib.dart', '''
-library lib;
-class Test {
-  const Test(int p);
-}
-''');
-    await resolveTestUnit('''
-@Test(0)
-main() {
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-@Test(0)
-main() {
-}
-''');
-  }
-
-  test_withClass_hasOtherLibraryWithPrefix() async {
-    addSource('/home/test/lib/a.dart', '''
-library a;
-class One {}
-''');
-    addSource('/home/test/lib/b.dart', '''
-library b;
-class One {}
-class Two {}
-''');
-    await resolveTestUnit('''
-import 'package:test/b.dart' show Two;
-main () {
-  new Two();
-  new One();
-}
-''');
-    await assertHasFix('''
-import 'package:test/a.dart';
-import 'package:test/b.dart' show Two;
-main () {
-  new Two();
-  new One();
-}
-''');
-  }
-
-  test_withClass_inParentFolder() async {
-    testFile = convertPath('/home/test/bin/aaa/test.dart');
-    addSource('/home/test/bin/lib.dart', '''
-library lib;
-class Test {}
-''');
-    await resolveTestUnit('''
-main() {
-  Test t = null;
-  print(t);
-}
-''');
-    await assertHasFix('''
-import '../lib.dart';
+import 'package:my_pkg/a.dart';
 
 main() {
-  Test t = null;
-  print(t);
-}
-''');
-  }
-
-  test_withClass_inRelativeFolder() async {
-    testFile = convertPath('/home/test/bin/test.dart');
-    addSource('/home/test/tool/sub/folder/lib.dart', '''
-library lib;
-class Test {}
-''');
-    await resolveTestUnit('''
-main() {
-  Test t = null;
-  print(t);
-}
-''');
-    await assertHasFix('''
-import '../tool/sub/folder/lib.dart';
-
-main() {
-  Test t = null;
-  print(t);
-}
-''');
-  }
-
-  test_withClass_inSameFolder() async {
-    testFile = convertPath('/home/test/bin/test.dart');
-    addSource('/home/test/bin/lib.dart', '''
-library lib;
-class Test {}
-''');
-    await resolveTestUnit('''
-main() {
-  Test t = null;
-  print(t);
-}
-''');
-    await assertHasFix('''
-import 'lib.dart';
-
-main() {
-  Test t = null;
-  print(t);
-}
-''');
-  }
-
-  test_withClass_instanceCreation_const() async {
-    addSource('/home/test/lib/lib.dart', '''
-class Test {
-  const Test();
-}
-''');
-    await resolveTestUnit('''
-main() {
-  return const Test();
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  return const Test();
-}
-''');
-  }
-
-  test_withClass_instanceCreation_const_namedConstructor() async {
-    addSource('/home/test/lib/lib.dart', '''
-class Test {
-  const Test.named();
-}
-''');
-    await resolveTestUnit('''
-main() {
-  const Test.named();
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  const Test.named();
-}
-''');
-  }
-
-  test_withClass_instanceCreation_implicit() async {
-    addSource('/home/test/lib/lib.dart', '''
-class Test {
-  const Test();
-}
-''');
-    await resolveTestUnit('''
-main() {
-  return Test();
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  return Test();
-}
-''');
-  }
-
-  test_withClass_instanceCreation_new() async {
-    addSource('/home/test/lib/lib.dart', '''
-class Test {
-  const Test();
-}
-''');
-    await resolveTestUnit('''
-main() {
-  return new Test();
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  return new Test();
-}
-''');
-  }
-
-  test_withClass_instanceCreation_new_namedConstructor() async {
-    addSource('/home/test/lib/lib.dart', '''
-class Test {
-  Test.named();
-}
-''');
-    await resolveTestUnit('''
-main() {
-  new Test.named();
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  new Test.named();
-}
-''');
-  }
-
-  test_withFunction() async {
-    addSource('/home/test/lib/lib.dart', '''
-library lib;
-myFunction() {}
-''');
-    await resolveTestUnit('''
-main() {
-  myFunction();
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  myFunction();
-}
-''');
-  }
-
-  test_withFunction_functionTopLevelVariable() async {
-    addSource('/home/test/lib/lib.dart', 'var myFunction = () {};');
-    await resolveTestUnit('''
-main() {
-  myFunction();
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  myFunction();
-}
-''');
-  }
-
-  test_withFunction_functionTopLevelVariableIdentifier() async {
-    addSource('/home/test/lib/lib.dart', 'var myFunction = () {};');
-    await resolveTestUnit('''
-main() {
-  myFunction;
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  myFunction;
-}
-''');
-  }
-
-  test_withFunction_identifier() async {
-    addSource('/home/test/lib/lib.dart', '''
-library lib;
-myFunction() {}
-''');
-    await resolveTestUnit('''
-main() {
-  myFunction;
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  myFunction;
-}
-''');
-  }
-
-  @failingTest
-  test_withFunction_nonFunctionType() async {
-    addSource('/home/test/lib/lib.dart', 'int zero = 0;');
-    await resolveTestUnit('''
-main() {
-  zero();
-}
-''');
-    await assertNoFix();
-  }
-
-  test_withFunction_unresolvedMethod() async {
-    addSource('/home/test/lib/lib.dart', '''
-library lib;
-myFunction() {}
-''');
-    await resolveTestUnit('''
-class A {
-  main() {
-    myFunction();
-  }
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-class A {
-  main() {
-    myFunction();
-  }
-}
-''');
-  }
-
-  test_withFunctionTypeAlias() async {
-    addSource('/home/test/lib/lib.dart', '''
-library lib;
-typedef MyFunction();
-''');
-    await resolveTestUnit('''
-main() {
-  MyFunction t = null;
-  print(t);
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  MyFunction t = null;
-  print(t);
-}
-''');
-  }
-
-  test_withMixin() async {
-    addSource('/home/test/lib/lib.dart', '''
-mixin Test {}
-''');
-    await resolveTestUnit('''
-class X = Object with Test;
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-class X = Object with Test;
-''', errorFilter: (error) {
-      return error.errorCode == CompileTimeErrorCode.UNDEFINED_CLASS;
-    });
-  }
-
-  test_withTopLevelVariable() async {
-    addSource('/home/test/lib/lib.dart', '''
-library lib;
-int MY_VAR = 42;
-''');
-    await resolveTestUnit('''
-main() {
-  print(MY_VAR);
-}
-''');
-    await assertHasFix('''
-import 'package:test/lib.dart';
-
-main() {
-  print(MY_VAR);
+  Test test = null;
+  print(test);
 }
 ''');
   }
@@ -564,7 +616,7 @@
     super.setUp();
   }
 
-  test_lib_src() async {
+  Future<void> test_lib_src() async {
     addPackageFile('my_pkg', 'a.dart', "export 'src/b.dart';");
     addPackageFile('my_pkg', 'src/b.dart', '''
 extension E on int {
@@ -591,95 +643,11 @@
 }
 
 @reflectiveTest
-class ImportLibraryProject2Test extends FixProcessorTest {
-  @override
-  FixKind get kind => DartFixKind.IMPORT_LIBRARY_PROJECT2;
-
-  test_lib() async {
-    addPackageFile('my_pkg', 'a.dart', "export 'b.dart';");
-    addPackageFile('my_pkg', 'b.dart', 'class Test {}');
-    newFile('/home/test/pubspec.yaml', content: r'''
-dependencies:
-  my_pkg: any
-''');
-    await resolveTestUnit('''
-main() {
-  Test test = null;
-  print(test);
-}
-''');
-    await assertHasFix('''
-import 'package:my_pkg/a.dart';
-
-main() {
-  Test test = null;
-  print(test);
-}
-''');
-  }
-
-  test_lib_src() async {
-    addPackageFile('my_pkg', 'a.dart', "export 'src/b.dart';");
-    addPackageFile('my_pkg', 'src/b.dart', 'class Test {}');
-    newFile('/home/test/pubspec.yaml', content: r'''
-dependencies:
-  my_pkg: any
-''');
-    await resolveTestUnit('''
-main() {
-  Test test = null;
-  print(test);
-}
-''');
-    await assertHasFix('''
-import 'package:my_pkg/a.dart';
-
-main() {
-  Test test = null;
-  print(test);
-}
-''');
-  }
-}
-
-@reflectiveTest
-class ImportLibraryProject3WithExtensionMethodsTest extends FixProcessorTest {
-  @override
-  FixKind get kind => DartFixKind.IMPORT_LIBRARY_PROJECT3;
-
-  @override
-  void setUp() {
-    createAnalysisOptionsFile(experiments: ['extension-methods']);
-    super.setUp();
-  }
-
-  test_inLibSrc_thisContextRoot() async {
-    addSource('/home/test/lib/src/lib.dart', '''
-extension E on int {
-  static String m() => '';
-}
-''');
-    await resolveTestUnit('''
-f() {
-  print(E.m());
-}
-''');
-    await assertHasFix('''
-import 'package:test/src/lib.dart';
-
-f() {
-  print(E.m());
-}
-''');
-  }
-}
-
-@reflectiveTest
 class ImportLibraryProject3Test extends FixProcessorTest {
   @override
   FixKind get kind => DartFixKind.IMPORT_LIBRARY_PROJECT3;
 
-  test_inLibSrc_differentContextRoot() async {
+  Future<void> test_inLibSrc_differentContextRoot() async {
     addPackageFile('bbb', 'b1.dart', r'''
 import 'src/b2.dart';
 class A {}
@@ -696,7 +664,7 @@
     await assertNoFix();
   }
 
-  test_inLibSrc_thisContextRoot() async {
+  Future<void> test_inLibSrc_thisContextRoot() async {
     addSource('/home/test/lib/src/lib.dart', 'class Test {}');
     await resolveTestUnit('''
 main() {
@@ -714,3 +682,35 @@
 ''');
   }
 }
+
+@reflectiveTest
+class ImportLibraryProject3WithExtensionMethodsTest extends FixProcessorTest {
+  @override
+  FixKind get kind => DartFixKind.IMPORT_LIBRARY_PROJECT3;
+
+  @override
+  void setUp() {
+    createAnalysisOptionsFile(experiments: ['extension-methods']);
+    super.setUp();
+  }
+
+  Future<void> test_inLibSrc_thisContextRoot() async {
+    addSource('/home/test/lib/src/lib.dart', '''
+extension E on int {
+  static String m() => '';
+}
+''');
+    await resolveTestUnit('''
+f() {
+  print(E.m());
+}
+''');
+    await assertHasFix('''
+import 'package:test/src/lib.dart';
+
+f() {
+  print(E.m());
+}
+''');
+  }
+}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/import_library_sdk_test.dart b/pkg/analysis_server/test/src/services/correction/fix/import_library_sdk_test.dart
index ce3dcc4..1f5ad4c 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/import_library_sdk_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/import_library_sdk_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ImportLibrarySdkTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.IMPORT_LIBRARY_SDK;
 
-  test_alreadyImported_sdk() async {
+  Future<void> test_alreadyImported_sdk() async {
     await resolveTestUnit('''
 import 'dart:collection' show HashMap;
 main() {
@@ -32,7 +32,7 @@
     await assertNoFix();
   }
 
-  test_withClass_asExpression() async {
+  Future<void> test_withClass_asExpression() async {
     await resolveTestUnit('''
 main(p) {
   p as HashMap;
@@ -47,7 +47,7 @@
 ''');
   }
 
-  test_withClass_instanceCreation_explicitNew() async {
+  Future<void> test_withClass_instanceCreation_explicitNew() async {
     await resolveTestUnit('''
 class C {
   foo() {
@@ -66,7 +66,8 @@
 ''');
   }
 
-  test_withClass_instanceCreation_explicitNew_namedConstructor() async {
+  Future<void>
+      test_withClass_instanceCreation_explicitNew_namedConstructor() async {
     await resolveTestUnit('''
 class C {
   foo() {
@@ -85,7 +86,7 @@
 ''');
   }
 
-  test_withClass_instanceCreation_implicitNew() async {
+  Future<void> test_withClass_instanceCreation_implicitNew() async {
     await resolveTestUnit('''
 class C {
   foo() {
@@ -104,7 +105,8 @@
 ''');
   }
 
-  test_withClass_instanceCreation_implicitNew_namedConstructor() async {
+  Future<void>
+      test_withClass_instanceCreation_implicitNew_namedConstructor() async {
     await resolveTestUnit('''
 class C {
   foo() {
@@ -123,7 +125,7 @@
 ''');
   }
 
-  test_withClass_invocationTarget() async {
+  Future<void> test_withClass_invocationTarget() async {
     await resolveTestUnit('''
 main() {
   Timer.run(null);
@@ -138,7 +140,7 @@
 ''');
   }
 
-  test_withClass_IsExpression() async {
+  Future<void> test_withClass_IsExpression() async {
     await resolveTestUnit('''
 main(p) {
   p is Completer;
@@ -153,7 +155,7 @@
 ''');
   }
 
-  test_withClass_itemOfList() async {
+  Future<void> test_withClass_itemOfList() async {
     await resolveTestUnit('''
 main() {
   var a = [Completer];
@@ -170,7 +172,7 @@
 ''');
   }
 
-  test_withClass_itemOfList_inAnnotation() async {
+  Future<void> test_withClass_itemOfList_inAnnotation() async {
     await resolveTestUnit('''
 class MyAnnotation {
   const MyAnnotation(a, b);
@@ -191,7 +193,7 @@
     });
   }
 
-  test_withClass_typeAnnotation() async {
+  Future<void> test_withClass_typeAnnotation() async {
     await resolveTestUnit('''
 main() {
   Completer f = null;
@@ -208,7 +210,7 @@
 ''');
   }
 
-  test_withClass_typeAnnotation_PrefixedIdentifier() async {
+  Future<void> test_withClass_typeAnnotation_PrefixedIdentifier() async {
     await resolveTestUnit('''
 main() {
   Timer.run;
@@ -223,7 +225,7 @@
 ''');
   }
 
-  test_withClass_typeArgument() async {
+  Future<void> test_withClass_typeArgument() async {
     await resolveTestUnit('''
 main() {
   List<Completer> completers = [];
@@ -240,7 +242,7 @@
 ''');
   }
 
-  test_withTopLevelVariable() async {
+  Future<void> test_withTopLevelVariable() async {
     await resolveTestUnit('''
 main() {
   print(PI);
@@ -255,7 +257,7 @@
 ''');
   }
 
-  test_withTopLevelVariable_annotation() async {
+  Future<void> test_withTopLevelVariable_annotation() async {
     await resolveTestUnit('''
 @PI
 main() {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/import_library_show_test.dart b/pkg/analysis_server/test/src/services/correction/fix/import_library_show_test.dart
index 432c284..a89b015 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/import_library_show_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/import_library_show_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ImportLibraryShowTest);
     defineReflectiveTests(ImportLibraryShowWithExtensionMethodsTest);
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.IMPORT_LIBRARY_SHOW;
 
-  test_package() async {
+  Future<void> test_package() async {
     addSource('/home/test/lib/lib.dart', '''
 class A {}
 class B {}
@@ -43,7 +43,7 @@
 ''');
   }
 
-  test_sdk() async {
+  Future<void> test_sdk() async {
     await resolveTestUnit(r'''
 import 'dart:collection' show HashMap;
 main() {
@@ -74,7 +74,7 @@
     super.setUp();
   }
 
-  test_override_samePackage() async {
+  Future<void> test_override_samePackage() async {
     addSource('/home/test/lib/lib.dart', '''
 class A {}
 extension E on int {
@@ -95,7 +95,7 @@
 ''');
   }
 
-  test_static_samePackage() async {
+  Future<void> test_static_samePackage() async {
     addSource('/home/test/lib/lib.dart', '''
 class A {}
 extension E on int {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/inline_invocation_test.dart b/pkg/analysis_server/test/src/services/correction/fix/inline_invocation_test.dart
index b3c8344..e895e79 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/inline_invocation_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/inline_invocation_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InlineInvocationTest);
   });
@@ -24,7 +24,7 @@
   String get lintCode => LintNames.prefer_inlined_adds;
 
   /// More coverage in the `inline_invocation_test.dart` assist test.
-  test_add_emptyTarget() async {
+  Future<void> test_add_emptyTarget() async {
     await resolveTestUnit('''
 var l = []../*LINT*/add('a')..add('b');
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/insert_semicolon_test.dart b/pkg/analysis_server/test/src/services/correction/fix/insert_semicolon_test.dart
index 77123f3..3e0fc37 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/insert_semicolon_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/insert_semicolon_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InsertSemicolonTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.INSERT_SEMICOLON;
 
-  test_expectedToken_semicolon() async {
+  Future<void> test_expectedToken_semicolon() async {
     await resolveTestUnit('''
 main() {
   print(0)
diff --git a/pkg/analysis_server/test/src/services/correction/fix/make_class_abstract_test.dart b/pkg/analysis_server/test/src/services/correction/fix/make_class_abstract_test.dart
index 7dbf4e9..cc90674 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/make_class_abstract_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/make_class_abstract_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MakeClassAbstractTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.MAKE_CLASS_ABSTRACT;
 
-  test_declaresAbstractMethod() async {
+  Future<void> test_declaresAbstractMethod() async {
     await resolveTestUnit('''
 class A {
   m();
@@ -32,7 +32,7 @@
 ''');
   }
 
-  test_inheritsAbstractMethod() async {
+  Future<void> test_inheritsAbstractMethod() async {
     await resolveTestUnit('''
 abstract class A {
   m();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/make_field_not_final_test.dart b/pkg/analysis_server/test/src/services/correction/fix/make_field_not_final_test.dart
index 6027ac6..d0b89d3 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/make_field_not_final_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/make_field_not_final_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MakeFieldNotFinalTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.MAKE_FIELD_NOT_FINAL;
 
-  test_hasType() async {
+  Future<void> test_hasType() async {
     await resolveTestUnit('''
 class A {
   final int fff = 1;
@@ -38,7 +38,7 @@
 ''');
   }
 
-  test_noType() async {
+  Future<void> test_noType() async {
     await resolveTestUnit('''
 class A {
   final fff = 1;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/make_final_test.dart b/pkg/analysis_server/test/src/services/correction/fix/make_final_test.dart
index 1831cff..5fccf8e 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/make_final_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/make_final_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MakeFinalTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_final_fields;
 
-  test_field_type() async {
+  Future<void> test_field_type() async {
     await resolveTestUnit('''
 class C {
   int /*LINT*/f = 2;
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_field_var() async {
+  Future<void> test_field_var() async {
     await resolveTestUnit('''
 class C {
   var /*LINT*/f = 2;
@@ -49,7 +49,7 @@
 ''');
   }
 
-  test_local_type() async {
+  Future<void> test_local_type() async {
     await resolveTestUnit('''
 bad() {
   int /*LINT*/x = 2;
@@ -62,7 +62,7 @@
 ''');
   }
 
-  test_local_var() async {
+  Future<void> test_local_var() async {
     await resolveTestUnit('''
 bad() {
   var /*LINT*/x = 2;
@@ -75,7 +75,7 @@
 ''');
   }
 
-  test_noKeyword() async {
+  Future<void> test_noKeyword() async {
     await resolveTestUnit('''
 class C {
   /*LINT*/f = 2;
@@ -88,7 +88,7 @@
 ''');
   }
 
-  test_topLevel_type() async {
+  Future<void> test_topLevel_type() async {
     await resolveTestUnit('''
 int /*LINT*/x = 2;
 ''');
@@ -97,7 +97,7 @@
 ''');
   }
 
-  test_topLevel_var() async {
+  Future<void> test_topLevel_var() async {
     await resolveTestUnit('''
 var /*LINT*/x = 2;
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/make_variable_not_final_test.dart b/pkg/analysis_server/test/src/services/correction/fix/make_variable_not_final_test.dart
index 3c210a0..441cbbf 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/make_variable_not_final_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/make_variable_not_final_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MakeVariableNotFinalTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.MAKE_VARIABLE_NOT_FINAL;
 
-  test_hasType() async {
+  Future<void> test_hasType() async {
     await resolveTestUnit('''
 main() {
   final int fff = 1;
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_noType() async {
+  Future<void> test_noType() async {
     await resolveTestUnit('''
 main() {
   final fff = 1;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/move_type_arguments_to_class_test.dart b/pkg/analysis_server/test/src/services/correction/fix/move_type_arguments_to_class_test.dart
index b7622e9..cbbf990 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/move_type_arguments_to_class_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/move_type_arguments_to_class_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(MoveTypeArgumentsToClassTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.MOVE_TYPE_ARGUMENTS_TO_CLASS;
 
-  test_explicitConst() async {
+  Future<void> test_explicitConst() async {
     await resolveTestUnit('''
 main() {
   const C.named<int>();
@@ -38,7 +38,7 @@
 ''');
   }
 
-  test_explicitNew() async {
+  Future<void> test_explicitNew() async {
     await resolveTestUnit('''
 main() {
   new C.named<int>();
@@ -57,7 +57,7 @@
 ''');
   }
 
-  test_explicitNew_alreadyThere() async {
+  Future<void> test_explicitNew_alreadyThere() async {
     await resolveTestUnit('''
 main() {
   new C<String>.named<int>();
@@ -69,7 +69,7 @@
     await assertNoFix();
   }
 
-  test_explicitNew_wrongNumber() async {
+  Future<void> test_explicitNew_wrongNumber() async {
     await resolveTestUnit('''
 main() {
   new C.named<int, String>();
@@ -81,7 +81,7 @@
     await assertNoFix();
   }
 
-  test_implicitConst() async {
+  Future<void> test_implicitConst() async {
     await resolveTestUnit('''
 main() {
   const C c = C.named<int>();
@@ -102,7 +102,7 @@
 ''');
   }
 
-  test_implicitNew() async {
+  Future<void> test_implicitNew() async {
     await resolveTestUnit('''
 main() {
   C.named<int>();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/qualify_reference_test.dart b/pkg/analysis_server/test/src/services/correction/fix/qualify_reference_test.dart
index 1184cb4..000b9bb 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/qualify_reference_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/qualify_reference_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(QualifyReferenceTest);
     defineReflectiveTests(QualifyReferenceWithExtensionMethodsTest);
@@ -21,7 +21,7 @@
   @override
   FixKind get kind => DartFixKind.QUALIFY_REFERENCE;
 
-  test_class_direct() async {
+  Future<void> test_class_direct() async {
     await resolveTestUnit('''
 class C {
   static void m() {}
@@ -44,7 +44,7 @@
 ''');
   }
 
-  test_class_imported() async {
+  Future<void> test_class_imported() async {
     newFile('/home/test/lib/a.dart', content: '''
 class A {
   static void m() {}
@@ -61,7 +61,7 @@
     await assertNoFix();
   }
 
-  test_class_importedWithPrefix() async {
+  Future<void> test_class_importedWithPrefix() async {
     newFile('/home/test/lib/a.dart', content: '''
 class A {
   static void m() {}
@@ -78,7 +78,7 @@
     await assertNoFix();
   }
 
-  test_class_indirect() async {
+  Future<void> test_class_indirect() async {
     await resolveTestUnit('''
 class A {
   static void m() {}
@@ -105,7 +105,7 @@
 ''');
   }
 
-  test_class_notImported() async {
+  Future<void> test_class_notImported() async {
     newFile('/home/test/lib/a.dart', content: '''
 class A {
   static void m() {}
@@ -135,7 +135,7 @@
     createAnalysisOptionsFile(experiments: [EnableString.extension_methods]);
   }
 
-  test_extension_direct() async {
+  Future<void> test_extension_direct() async {
     await resolveTestUnit('''
 class C {
   static void m() {}
@@ -158,7 +158,7 @@
 ''');
   }
 
-  test_extension_imported() async {
+  Future<void> test_extension_imported() async {
     newFile('/home/test/lib/a.dart', content: '''
 class A {
   static void m() {}
@@ -175,7 +175,7 @@
     await assertNoFix();
   }
 
-  test_extension_importedWithPrefix() async {
+  Future<void> test_extension_importedWithPrefix() async {
     newFile('/home/test/lib/a.dart', content: '''
 class A {
   static void m() {}
@@ -192,7 +192,7 @@
     await assertNoFix();
   }
 
-  test_extension_indirect() async {
+  Future<void> test_extension_indirect() async {
     await resolveTestUnit('''
 class A {
   static void m() {}
@@ -219,7 +219,7 @@
 ''');
   }
 
-  test_extension_notImported() async {
+  Future<void> test_extension_notImported() async {
     newFile('/home/test/lib/a.dart', content: '''
 class A {
   static void m() {}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_annotation_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_annotation_test.dart
index 1874b6f..f69c58b 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_annotation_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_annotation_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveAnnotationTest);
   });
@@ -25,7 +25,7 @@
     addMetaPackage();
   }
 
-  test_factory() async {
+  Future<void> test_factory() async {
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
 
@@ -39,7 +39,7 @@
 ''');
   }
 
-  test_immutable() async {
+  Future<void> test_immutable() async {
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
 
@@ -53,7 +53,7 @@
 ''');
   }
 
-  test_literal() async {
+  Future<void> test_literal() async {
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
 
@@ -67,7 +67,7 @@
 ''');
   }
 
-  test_override_field() async {
+  Future<void> test_override_field() async {
     await resolveTestUnit('''
 class A {
   @override
@@ -81,7 +81,7 @@
 ''');
   }
 
-  test_override_getter() async {
+  Future<void> test_override_getter() async {
     await resolveTestUnit('''
 class A {
   @override
@@ -95,7 +95,7 @@
 ''');
   }
 
-  test_override_method() async {
+  Future<void> test_override_method() async {
     await resolveTestUnit('''
 class A {
   @override
@@ -109,7 +109,7 @@
 ''');
   }
 
-  test_override_setter() async {
+  Future<void> test_override_setter() async {
     await resolveTestUnit('''
 class A {
   @override
@@ -123,7 +123,7 @@
 ''');
   }
 
-  test_required_namedWithDefault() async {
+  Future<void> test_required_namedWithDefault() async {
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
 
@@ -136,7 +136,7 @@
 ''');
   }
 
-  test_required_positional() async {
+  Future<void> test_required_positional() async {
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
 
@@ -149,7 +149,7 @@
 ''');
   }
 
-  test_required_required() async {
+  Future<void> test_required_required() async {
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
 
@@ -162,7 +162,7 @@
 ''');
   }
 
-  test_sealed() async {
+  Future<void> test_sealed() async {
     await resolveTestUnit('''
 import 'package:meta/meta.dart';
 
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_argument_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_argument_test.dart
index fde711d..0ebd9c2 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_argument_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_argument_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveArgumentTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.avoid_redundant_argument_values;
 
-  test_named_param() async {
+  Future<void> test_named_param() async {
     await resolveTestUnit('''
 void f({bool valWithDefault = true, bool val}) {}
 
@@ -40,7 +40,7 @@
 ''');
   }
 
-  test_named_param_2() async {
+  Future<void> test_named_param_2() async {
     await resolveTestUnit('''
 void f({bool valWithDefault = true, bool val}) {}
 
@@ -57,7 +57,7 @@
 ''');
   }
 
-  test_optional_positional() async {
+  Future<void> test_optional_positional() async {
     await resolveTestUnit('''
 void g(int x, [int y = 0]) {}
 
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_await_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_await_test.dart
index dcb6d79..a0e4787 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_await_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_await_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveAwaitTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.await_only_futures;
 
-  test_intLiteral() async {
+  Future<void> test_intLiteral() async {
     await resolveTestUnit('''
 bad() async {
   print(/*LINT*/await 23);
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_stringLiteral() async {
+  Future<void> test_stringLiteral() async {
     await resolveTestUnit('''
 bad() async {
   print(/*LINT*/await 'hola');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_dead_code_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_dead_code_test.dart
index 7f2fc41..6d4e023 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_dead_code_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_dead_code_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveDeadCodeTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_DEAD_CODE;
 
-  test_catch_afterCatchAll_catch() async {
+  Future<void> test_catch_afterCatchAll_catch() async {
     await resolveTestUnit('''
 main() {
   try {
@@ -40,7 +40,7 @@
 ''');
   }
 
-  test_catch_afterCatchAll_on() async {
+  Future<void> test_catch_afterCatchAll_on() async {
     await resolveTestUnit('''
 main() {
   try {
@@ -61,7 +61,7 @@
 ''');
   }
 
-  test_catch_subtype() async {
+  Future<void> test_catch_subtype() async {
     await resolveTestUnit('''
 class A {}
 class B extends A {}
@@ -86,7 +86,7 @@
 ''');
   }
 
-  test_condition() async {
+  Future<void> test_condition() async {
     await resolveTestUnit('''
 main(int p) {
   if (true || p > 5) {
@@ -103,7 +103,7 @@
 ''');
   }
 
-  test_statements_one() async {
+  Future<void> test_statements_one() async {
     await resolveTestUnit('''
 int main() {
   print(0);
@@ -119,7 +119,7 @@
 ''');
   }
 
-  test_statements_two() async {
+  Future<void> test_statements_two() async {
     await resolveTestUnit('''
 int main() {
   print(0);
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_duplicate_case_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_duplicate_case_test.dart
index 3cd7576..d8c9b4e 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_duplicate_case_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_duplicate_case_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveDuplicateCaseTest);
   });
@@ -23,7 +23,35 @@
   @override
   String get lintCode => LintNames.no_duplicate_case_values;
 
-  test_removeStringCase() async {
+  Future<void> test_removeIntCase() async {
+    await resolveTestUnit('''
+void switchInt() {
+  switch (2) {
+    case 1:
+      print('a');
+      break;
+    case 2:
+    case 2 /*LINT*/:
+    default:
+      print('?);
+  }
+}
+''');
+    await assertHasFix('''
+void switchInt() {
+  switch (2) {
+    case 1:
+      print('a');
+      break;
+    case 2:
+    default:
+      print('?);
+  }
+}
+''');
+  }
+
+  Future<void> test_removeStringCase() async {
     await resolveTestUnit('''
 void switchString() {
   String v = 'a';
@@ -58,32 +86,4 @@
 }
 ''');
   }
-
-  test_removeIntCase() async {
-    await resolveTestUnit('''
-void switchInt() {
-  switch (2) {
-    case 1:
-      print('a');
-      break;
-    case 2:
-    case 2 /*LINT*/:
-    default:
-      print('?);
-  }
-}
-''');
-    await assertHasFix('''
-void switchInt() {
-  switch (2) {
-    case 1:
-      print('a');
-      break;
-    case 2:
-    default:
-      print('?);
-  }
-}
-''');
-  }
 }
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_empty_catch_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_empty_catch_test.dart
index 317e9a1..bfff423 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_empty_catch_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_empty_catch_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveEmptyCatchTest);
   });
@@ -23,23 +23,29 @@
   @override
   String get lintCode => LintNames.empty_catches;
 
-  test_newLine() async {
+  Future<void> test_singleCatch_finally_newLine() async {
     await resolveTestUnit('''
 void foo() {
-  try {}
-  catch (e) {/*LINT*/}
-  finally {}
+  try {
+    1;
+  } catch (e) {/*LINT*/
+  } finally {
+    2;
+  }
 }
 ''');
     await assertHasFix('''
 void foo() {
-  try {}
-  finally {}
+  try {
+    1;
+  } finally {
+    2;
+  }
 }
 ''');
   }
 
-  test_sameLine() async {
+  Future<void> test_singleCatch_finally_sameLine() async {
     await resolveTestUnit('''
 void foo() {
   try {} catch (e) {/*LINT*/} finally {}
@@ -51,4 +57,16 @@
 }
 ''');
   }
+
+  Future<void> test_singleCatch_noFinally() async {
+    // The catch can't be removed unless we also remove the try, which is more
+    // than this fix does at the moment.
+    await resolveTestUnit('''
+void foo() {
+  try {
+  } catch (e) {/*LINT*/}
+}
+''');
+    await assertNoFix();
+  }
 }
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_empty_constructor_body_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_empty_constructor_body_test.dart
index 93f33be..fc57229 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_empty_constructor_body_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_empty_constructor_body_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveEmptyConstructorBodyTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.empty_constructor_bodies;
 
-  test_empty() async {
+  Future<void> test_empty() async {
     await resolveTestUnit('''
 class C {
   C() {/*LINT*/}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_empty_else_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_empty_else_test.dart
index f65b70e..14fb311 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_empty_else_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_empty_else_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveEmptyElseTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.avoid_empty_else;
 
-  test_newLine() async {
+  Future<void> test_newLine() async {
     await resolveTestUnit('''
 void foo(bool cond) {
   if (cond) {
@@ -41,7 +41,7 @@
 ''');
   }
 
-  test_sameLine() async {
+  Future<void> test_sameLine() async {
     await resolveTestUnit('''
 void foo(bool cond) {
   if (cond) {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_empty_statement_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_empty_statement_test.dart
index e225dda..211a7c3 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_empty_statement_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_empty_statement_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveEmptyStatementTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.empty_statements;
 
-  test_insideBlock() async {
+  Future<void> test_insideBlock() async {
     await resolveTestUnit('''
 void foo() {
   while(true) {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_if_null_operator_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_if_null_operator_test.dart
index f6559c8..3feb40a 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_if_null_operator_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_if_null_operator_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveIfNullOperatorTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.unnecessary_null_in_if_null_operators;
 
-  test_left() async {
+  Future<void> test_left() async {
     await resolveTestUnit('''
 var a = '';
 var b = /*LINT*/null ?? a;
@@ -34,7 +34,7 @@
 ''');
   }
 
-  test_right() async {
+  Future<void> test_right() async {
     await resolveTestUnit('''
 var a = '';
 var b = /*LINT*/a ?? null;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_initializer_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_initializer_test.dart
index b2bed15..25f3bd5 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_initializer_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_initializer_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveInitializerTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.avoid_init_to_null;
 
-  test_field() async {
+  Future<void> test_field() async {
     await resolveTestUnit('''
 class Test {
   int /*LINT*/x = null;
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_forLoop() async {
+  Future<void> test_forLoop() async {
     await resolveTestUnit('''
 void f() {
   for (var /*LINT*/i = null; i != null; i++) {
@@ -51,7 +51,7 @@
 ''');
   }
 
-  test_listOfVariableDeclarations() async {
+  Future<void> test_listOfVariableDeclarations() async {
     await resolveTestUnit('''
 String a = 'a', /*LINT*/b = null, c = 'c';
 ''');
@@ -60,7 +60,7 @@
 ''');
   }
 
-  test_parameter_optionalNamed() async {
+  Future<void> test_parameter_optionalNamed() async {
     await resolveTestUnit('''
 void f({String /*LINT*/s = null}) {}
 ''');
@@ -69,7 +69,7 @@
 ''');
   }
 
-  test_parameter_optionalPositional() async {
+  Future<void> test_parameter_optionalPositional() async {
     await resolveTestUnit('''
 void f([String /*LINT*/s = null]) {}
 ''');
@@ -78,7 +78,7 @@
 ''');
   }
 
-  test_topLevel() async {
+  Future<void> test_topLevel() async {
     await resolveTestUnit('''
 var /*LINT*/x = null;
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_interpolation_braces_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_interpolation_braces_test.dart
index 876d066..fcb23eb 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_interpolation_braces_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_interpolation_braces_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveInterpolationBracesTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.unnecessary_brace_in_string_interps;
 
-  test_withSpace() async {
+  Future<void> test_withSpace() async {
     await resolveTestUnit(r'''
 main() {
   var v = 42;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_method_declaration_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_method_declaration_test.dart
index 730249c..fd19334 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_method_declaration_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_method_declaration_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveMethodDeclarationTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.unnecessary_overrides;
 
-  test_getter() async {
+  Future<void> test_getter() async {
     await resolveTestUnit('''
 class A {
   int x;
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_method() async {
+  Future<void> test_method() async {
     await resolveTestUnit('''
 class A {
   @override
@@ -55,7 +55,7 @@
 ''');
   }
 
-  test_setter() async {
+  Future<void> test_setter() async {
     await resolveTestUnit('''
 class A {
   int x;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_name_from_combinator_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_name_from_combinator_test.dart
index 3ed155e..3bf7a32 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_name_from_combinator_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_name_from_combinator_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveNameFromCombinatorTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_NAME_FROM_COMBINATOR;
 
-  test_duplicateHiddenName_last() async {
+  Future<void> test_duplicateHiddenName_last() async {
     await resolveTestUnit('''
 import 'dart:math' hide cos, sin, sin;
 
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_duplicateHiddenName_middle() async {
+  Future<void> test_duplicateHiddenName_middle() async {
     await resolveTestUnit('''
 import 'dart:math' hide cos, cos, sin;
 
@@ -54,7 +54,7 @@
   }
 
   @failingTest
-  test_duplicateHiddenName_only_last() async {
+  Future<void> test_duplicateHiddenName_only_last() async {
     // It appears that the hint does not detect names that are duplicated across
     // multiple combinators.
     await resolveTestUnit('''
@@ -74,7 +74,7 @@
   }
 
   @failingTest
-  test_duplicateHiddenName_only_middle() async {
+  Future<void> test_duplicateHiddenName_only_middle() async {
     // It appears that the hint does not detect names that are duplicated across
     // multiple combinators.
     await resolveTestUnit('''
@@ -93,7 +93,7 @@
 ''');
   }
 
-  test_duplicateShownName_last() async {
+  Future<void> test_duplicateShownName_last() async {
     await resolveTestUnit(
       '''
 import 'dart:math' show cos, sin, sin;
@@ -112,7 +112,7 @@
 ''');
   }
 
-  test_duplicateShownName_middle() async {
+  Future<void> test_duplicateShownName_middle() async {
     await resolveTestUnit('''
 import 'dart:math' show cos, cos, sin;
 
@@ -129,7 +129,7 @@
 ''');
   }
 
-  test_undefinedHiddenName_first() async {
+  Future<void> test_undefinedHiddenName_first() async {
     await resolveTestUnit('''
 import 'dart:math' hide aaa, sin, tan;
 
@@ -146,7 +146,7 @@
 ''');
   }
 
-  test_undefinedHiddenName_last() async {
+  Future<void> test_undefinedHiddenName_last() async {
     await resolveTestUnit('''
 import 'dart:math' hide cos, sin, xxx;
 
@@ -163,7 +163,7 @@
 ''');
   }
 
-  test_undefinedHiddenName_middle() async {
+  Future<void> test_undefinedHiddenName_middle() async {
     await resolveTestUnit('''
 import 'dart:math' hide cos, mmm, tan;
 
@@ -180,7 +180,7 @@
 ''');
   }
 
-  test_undefinedHiddenName_only_first() async {
+  Future<void> test_undefinedHiddenName_only_first() async {
     await resolveTestUnit('''
 import 'dart:math' hide aaa hide cos, sin;
 
@@ -197,7 +197,7 @@
 ''');
   }
 
-  test_undefinedHiddenName_only_last() async {
+  Future<void> test_undefinedHiddenName_only_last() async {
     await resolveTestUnit('''
 import 'dart:math' hide cos, sin hide aaa;
 
@@ -214,7 +214,7 @@
 ''');
   }
 
-  test_undefinedHiddenName_only_middle() async {
+  Future<void> test_undefinedHiddenName_only_middle() async {
     await resolveTestUnit('''
 import 'dart:math' hide cos hide aaa hide sin;
 
@@ -231,7 +231,7 @@
 ''');
   }
 
-  test_undefinedHiddenName_only_only() async {
+  Future<void> test_undefinedHiddenName_only_only() async {
     await resolveTestUnit('''
 import 'dart:math' hide aaa;
 var c = sin(0.3);
@@ -242,7 +242,7 @@
 ''');
   }
 
-  test_undefinedHiddenName_only_only_withAs() async {
+  Future<void> test_undefinedHiddenName_only_only_withAs() async {
     await resolveTestUnit('''
 import 'dart:math' as math hide aaa;
 var c = math.sin(0.3);
@@ -253,7 +253,7 @@
 ''');
   }
 
-  test_undefinedShownName_first() async {
+  Future<void> test_undefinedShownName_first() async {
     await resolveTestUnit('''
 import 'dart:math' show aaa, sin, tan;
 
@@ -270,7 +270,7 @@
 ''');
   }
 
-  test_undefinedShownName_last() async {
+  Future<void> test_undefinedShownName_last() async {
     await resolveTestUnit('''
 import 'dart:math' show cos, sin, xxx;
 
@@ -287,7 +287,7 @@
 ''');
   }
 
-  test_undefinedShownName_middle() async {
+  Future<void> test_undefinedShownName_middle() async {
     await resolveTestUnit('''
 import 'dart:math' show cos, mmm, tan;
 
@@ -304,7 +304,7 @@
 ''');
   }
 
-  test_unusedShownName_first() async {
+  Future<void> test_unusedShownName_first() async {
     await resolveTestUnit('''
 import 'dart:math' show cos, sin, tan;
 
@@ -321,7 +321,7 @@
 ''');
   }
 
-  test_unusedShownName_last() async {
+  Future<void> test_unusedShownName_last() async {
     await resolveTestUnit('''
 import 'dart:math' show cos, sin, tan;
 
@@ -338,7 +338,7 @@
 ''');
   }
 
-  test_unusedShownName_middle() async {
+  Future<void> test_unusedShownName_middle() async {
     await resolveTestUnit('''
 import 'dart:math' show cos, sin, tan;
 
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_operator_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_operator_test.dart
index aef5f95..1568cf3 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_operator_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_operator_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveOperatorTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_adjacent_string_concatenation;
 
-  test_plus() async {
+  Future<void> test_plus() async {
     await resolveTestUnit('''
 var s = 'a' /*LINT*/+ 'b';
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_parameters_in_getter_declaration_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_parameters_in_getter_declaration_test.dart
index 20606f5..53a3e6b 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_parameters_in_getter_declaration_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_parameters_in_getter_declaration_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveParametersInGetterDeclarationTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_PARAMETERS_IN_GETTER_DECLARATION;
 
-  test_emptyList() async {
+  Future<void> test_emptyList() async {
     await resolveTestUnit('''
 class A {
   int get foo() => 0;
@@ -32,7 +32,7 @@
 ''');
   }
 
-  test_nonEmptyList() async {
+  Future<void> test_nonEmptyList() async {
     await resolveTestUnit('''
 class A {
   int get foo(int a) => 0;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_parentheses_in_getter_invocation_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_parentheses_in_getter_invocation_test.dart
index 65e1c39..c968a3f 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_parentheses_in_getter_invocation_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_parentheses_in_getter_invocation_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveParenthesesInGetterInvocationTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_PARENTHESIS_IN_GETTER_INVOCATION;
 
-  test_noArguments() async {
+  Future<void> test_noArguments() async {
     await resolveTestUnit('''
 class A {
   int get foo => 0;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_this_expression_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_this_expression_test.dart
index bcb188a..ad30634 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_this_expression_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_this_expression_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveThisExpressionTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.unnecessary_this;
 
-  test_constructorInitializer() async {
+  Future<void> test_constructorInitializer() async {
     await resolveTestUnit('''
 class A {
   int x;
@@ -38,7 +38,7 @@
 ''');
   }
 
-  test_methodInvocation_oneCharacterOperator() async {
+  Future<void> test_methodInvocation_oneCharacterOperator() async {
     await resolveTestUnit('''
 class A {
   void foo() {
@@ -55,7 +55,7 @@
 ''');
   }
 
-  test_methodInvocation_twoCharactersOperator() async {
+  Future<void> test_methodInvocation_twoCharactersOperator() async {
     await resolveTestUnit('''
 class A {
   void foo() {
@@ -72,7 +72,7 @@
 ''');
   }
 
-  test_notAThisExpression() async {
+  Future<void> test_notAThisExpression() async {
     await resolveTestUnit('''
 void foo() {
   final /*LINT*/this.id;
@@ -81,7 +81,7 @@
     await assertNoFix();
   }
 
-  test_propertyAccess_oneCharacterOperator() async {
+  Future<void> test_propertyAccess_oneCharacterOperator() async {
     await resolveTestUnit('''
 class A {
   int x;
@@ -100,7 +100,7 @@
 ''');
   }
 
-  test_propertyAccess_twoCharactersOperator() async {
+  Future<void> test_propertyAccess_twoCharactersOperator() async {
     await resolveTestUnit('''
 class A {
   int x;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_type_annotation_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_type_annotation_test.dart
index 7e0b234..3e99462 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_type_annotation_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_type_annotation_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AvoidAnnotatingWithDynamicTest);
     defineReflectiveTests(AvoidReturnTypesOnSettersTest);
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.avoid_annotating_with_dynamic;
 
-  test_insideFunctionTypedFormalParameter() async {
+  Future<void> test_insideFunctionTypedFormalParameter() async {
     await resolveTestUnit('''
 bad(void foo(/*LINT*/dynamic x)) {
   return null;
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_namedParameter() async {
+  Future<void> test_namedParameter() async {
     await resolveTestUnit('''
 bad({/*LINT*/dynamic defaultValue}) {
   return null;
@@ -49,7 +49,7 @@
 ''');
   }
 
-  test_normalParameter() async {
+  Future<void> test_normalParameter() async {
     await resolveTestUnit('''
 bad(/*LINT*/dynamic defaultValue) {
   return null;
@@ -62,7 +62,7 @@
 ''');
   }
 
-  test_optionalParameter() async {
+  Future<void> test_optionalParameter() async {
     await resolveTestUnit('''
 bad([/*LINT*/dynamic defaultValue]) {
   return null;
@@ -81,7 +81,7 @@
   @override
   String get lintCode => LintNames.avoid_return_types_on_setters;
 
-  test_void() async {
+  Future<void> test_void() async {
     await resolveTestUnit('''
 /*LINT*/void set speed2(int ms) {}
 ''');
@@ -96,7 +96,7 @@
   @override
   String get lintCode => LintNames.avoid_types_on_closure_parameters;
 
-  test_namedParameter() async {
+  Future<void> test_namedParameter() async {
     await resolveTestUnit('''
 var x = ({/*LINT*/Future<int> defaultValue}) {
   return null;
@@ -109,7 +109,7 @@
 ''');
   }
 
-  test_normalParameter() async {
+  Future<void> test_normalParameter() async {
     await resolveTestUnit('''
 var x = (/*LINT*/Future<int> defaultValue) {
   return null;
@@ -122,7 +122,7 @@
 ''');
   }
 
-  test_optionalParameter() async {
+  Future<void> test_optionalParameter() async {
     await resolveTestUnit('''
 var x = ([/*LINT*/Future<int> defaultValue]) {
   return null;
@@ -147,7 +147,7 @@
   @override
   String get lintCode => LintNames.type_init_formals;
 
-  test_void() async {
+  Future<void> test_void() async {
     await resolveTestUnit('''
 class C {
   int f;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_type_arguments_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_type_arguments_test.dart
index b27594f..cc3a812 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_type_arguments_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_type_arguments_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveTypeArgumentsTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_TYPE_ARGUMENTS;
 
-  test_explicitConst() async {
+  Future<void> test_explicitConst() async {
     await resolveTestUnit('''
 main() {
   const C.named<int>();
@@ -38,7 +38,7 @@
 ''');
   }
 
-  test_explicitNew() async {
+  Future<void> test_explicitNew() async {
     await resolveTestUnit('''
 main() {
   new C.named<int>();
@@ -57,7 +57,7 @@
 ''');
   }
 
-  test_implicitConst() async {
+  Future<void> test_implicitConst() async {
     await resolveTestUnit('''
 main() {
   const C c = C.named<int>();
@@ -78,7 +78,7 @@
 ''');
   }
 
-  test_implicitNew() async {
+  Future<void> test_implicitNew() async {
     await resolveTestUnit('''
 main() {
   C.named<int>();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_cast_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_cast_test.dart
index 9218c3b..576f52d 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_cast_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_cast_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveUnnecessaryCastTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_UNNECESSARY_CAST;
 
-  test_assignment() async {
+  Future<void> test_assignment() async {
     await resolveTestUnit('''
 main(Object p) {
   if (p is String) {
@@ -39,7 +39,7 @@
 ''');
   }
 
-  test_assignment_all() async {
+  Future<void> test_assignment_all() async {
     await resolveTestUnit('''
 main(Object p, Object q) {
   if (p is String) {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_const_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_const_test.dart
index f6d1bb9..7146abd 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_const_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_const_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveUnnecessaryConstTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.unnecessary_const;
 
-  test_constConstructor() async {
+  Future<void> test_constConstructor() async {
     await resolveTestUnit('''
 class A { const A(); }
 m(){
@@ -38,7 +38,7 @@
 ''');
   }
 
-  test_instanceCreation() async {
+  Future<void> test_instanceCreation() async {
     await resolveTestUnit('''
 const list = /*LINT*/const List();
 ''');
@@ -47,7 +47,7 @@
 ''', length: 5);
   }
 
-  test_typedLiteral() async {
+  Future<void> test_typedLiteral() async {
     await resolveTestUnit('''
 const list = /*LINT*/const [];
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_new_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_new_test.dart
index 69075a9..d416ab8 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_new_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_unnecessary_new_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveUnnecessaryNewTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.unnecessary_new;
 
-  test_constructor() async {
+  Future<void> test_constructor() async {
     await resolveTestUnit('''
 class A { A(); }
 m(){
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_catch_clause_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_catch_clause_test.dart
index 8bd4f51..7f5f40a 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_catch_clause_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_catch_clause_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveUnusedCatchClauseTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_UNUSED_CATCH_CLAUSE;
 
-  test_removeUnusedCatchClause() async {
+  Future<void> test_removeUnusedCatchClause() async {
     await resolveTestUnit('''
 main() {
   try {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_catch_stack_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_catch_stack_test.dart
index da067cd..31fc9a3 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_catch_stack_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_catch_stack_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveUnusedCatchStackTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_UNUSED_CATCH_STACK;
 
-  test_removeUnusedCatchStack() async {
+  Future<void> test_removeUnusedCatchStack() async {
     await resolveTestUnit('''
 main() {
   try {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_element_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_element_test.dart
index 9f6a7928..2160a9c 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_element_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_element_test.dart
@@ -10,7 +10,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveUnusedElementTest);
   });
@@ -21,7 +21,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_UNUSED_ELEMENT;
 
-  test_class_notUsed_inClassMember() async {
+  Future<void> test_class_notUsed_inClassMember() async {
     await resolveTestUnit(r'''
 class _A {
   staticMethod() {
@@ -34,7 +34,7 @@
     await assertNoFix();
   }
 
-  test_class_notUsed_isExpression() async {
+  Future<void> test_class_notUsed_isExpression() async {
     await resolveTestUnit(r'''
 class _A {}
 main(p) {
@@ -46,7 +46,7 @@
     await assertNoFix();
   }
 
-  test_class_notUsed_noReference() async {
+  Future<void> test_class_notUsed_noReference() async {
     await resolveTestUnit(r'''
 class _A {
 }
@@ -55,7 +55,7 @@
 ''');
   }
 
-  test_enum_notUsed_noReference() async {
+  Future<void> test_enum_notUsed_noReference() async {
     await resolveTestUnit(r'''
 enum _MyEnum {A, B, C}
 ''');
@@ -65,7 +65,7 @@
     });
   }
 
-  test_functionLocal_notUsed_noReference() async {
+  Future<void> test_functionLocal_notUsed_noReference() async {
     await resolveTestUnit(r'''
 main() {
   f() {}
@@ -77,7 +77,7 @@
 ''');
   }
 
-  test_functionTop_notUsed_noReference() async {
+  Future<void> test_functionTop_notUsed_noReference() async {
     await resolveTestUnit(r'''
 _f() {}
 main() {
@@ -89,7 +89,7 @@
 ''');
   }
 
-  test_functionTypeAlias_notUsed_noReference() async {
+  Future<void> test_functionTypeAlias_notUsed_noReference() async {
     await resolveTestUnit(r'''
 typedef _F(a, b);
 main() {
@@ -101,7 +101,7 @@
 ''');
   }
 
-  test_getter_notUsed_noReference() async {
+  Future<void> test_getter_notUsed_noReference() async {
     await resolveTestUnit(r'''
 class A {
   get _g => null;
@@ -113,7 +113,7 @@
 ''');
   }
 
-  test_method_notUsed_noReference() async {
+  Future<void> test_method_notUsed_noReference() async {
     await resolveTestUnit(r'''
 class A {
   static _m() {}
@@ -125,7 +125,7 @@
 ''');
   }
 
-  test_setter_notUsed_noReference() async {
+  Future<void> test_setter_notUsed_noReference() async {
     await resolveTestUnit(r'''
 class A {
   set _s(x) {}
@@ -137,7 +137,7 @@
 ''');
   }
 
-  test_staticMethod_extension_notUsed_noReference() async {
+  Future<void> test_staticMethod_extension_notUsed_noReference() async {
     await resolveTestUnit(r'''
 extension _E on String {
   static int m1() => 3;
@@ -153,7 +153,7 @@
 ''');
   }
 
-  test_staticMethod_mixim_notUsed_noReference() async {
+  Future<void> test_staticMethod_mixim_notUsed_noReference() async {
     await resolveTestUnit(r'''
 mixin _M {
   static int m1() => 3;
@@ -169,7 +169,7 @@
 ''');
   }
 
-  test_staticMethod_notUsed_noReference() async {
+  Future<void> test_staticMethod_notUsed_noReference() async {
     await resolveTestUnit(r'''
 class _A {
   static int m() => 7;
@@ -183,7 +183,7 @@
 ''');
   }
 
-  test_topLevelVariable_notUsed() async {
+  Future<void> test_topLevelVariable_notUsed() async {
     await resolveTestUnit(r'''
 int _a = 1;
 main() {
@@ -194,7 +194,7 @@
     await assertNoFix();
   }
 
-  test_topLevelVariable_notUsed_noReference() async {
+  Future<void> test_topLevelVariable_notUsed_noReference() async {
     await resolveTestUnit(r'''
 int _a = 1;
 main() {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_field_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_field_test.dart
index 139fb95..99ea7c3 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_field_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_field_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveUnusedFieldTest);
   });
@@ -20,7 +20,7 @@
   FixKind get kind => DartFixKind.REMOVE_UNUSED_FIELD;
 
   @FailingTest(reason: 'Unimplemented')
-  test_enumValue_notUsed_noReference() async {
+  Future<void> test_enumValue_notUsed_noReference() async {
     await resolveTestUnit(r'''
 enum _E { a, b, c }
 bool f(_E e) => e == _E.a || e == _E.b;
@@ -31,7 +31,7 @@
 ''');
   }
 
-  test_unusedField_notUsed_assign() async {
+  Future<void> test_unusedField_notUsed_assign() async {
     await resolveTestUnit(r'''
 class A {
   int _f;
@@ -48,7 +48,7 @@
 ''');
   }
 
-  test_unusedField_notUsed_compoundAssign() async {
+  Future<void> test_unusedField_notUsed_compoundAssign() async {
     await resolveTestUnit(r'''
 class A {
   int _f;
@@ -65,7 +65,7 @@
 ''');
   }
 
-  test_unusedField_notUsed_constructorFieldInitializers() async {
+  Future<void> test_unusedField_notUsed_constructorFieldInitializers() async {
     await resolveTestUnit(r'''
 class A {
   int _f;
@@ -79,7 +79,7 @@
 ''');
   }
 
-  test_unusedField_notUsed_constructorFieldInitializers1() async {
+  Future<void> test_unusedField_notUsed_constructorFieldInitializers1() async {
     await resolveTestUnit(r'''
 class A {
   int _f;
@@ -95,7 +95,7 @@
 ''');
   }
 
-  test_unusedField_notUsed_constructorFieldInitializers2() async {
+  Future<void> test_unusedField_notUsed_constructorFieldInitializers2() async {
     await resolveTestUnit(r'''
 class A {
   int _f;
@@ -111,7 +111,7 @@
 ''');
   }
 
-  test_unusedField_notUsed_declarationList() async {
+  Future<void> test_unusedField_notUsed_declarationList() async {
     await resolveTestUnit(r'''
 class A {
   int _f, x;
@@ -130,7 +130,7 @@
 ''');
   }
 
-  test_unusedField_notUsed_declarationList2() async {
+  Future<void> test_unusedField_notUsed_declarationList2() async {
     await resolveTestUnit(r'''
 class A {
   int x, _f;
@@ -149,7 +149,7 @@
 ''');
   }
 
-  test_unusedField_notUsed_fieldFormalParameter() async {
+  Future<void> test_unusedField_notUsed_fieldFormalParameter() async {
     await resolveTestUnit(r'''
 class A {
   int _f;
@@ -163,7 +163,7 @@
 ''');
   }
 
-  test_unusedField_notUsed_fieldFormalParameter2() async {
+  Future<void> test_unusedField_notUsed_fieldFormalParameter2() async {
     await resolveTestUnit(r'''
 class A {
   int _f;
@@ -179,7 +179,7 @@
 ''');
   }
 
-  test_unusedField_notUsed_fieldFormalParameter3() async {
+  Future<void> test_unusedField_notUsed_fieldFormalParameter3() async {
     await resolveTestUnit(r'''
 class A {
   int x;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_import_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_import_test.dart
index e7a4db9..7ac2650 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_import_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_import_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveUnusedImportTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_UNUSED_IMPORT;
 
-  test_all_diverseImports() async {
+  Future<void> test_all_diverseImports() async {
     await resolveTestUnit('''
 import 'dart:math';
 import 'dart:math';
@@ -34,7 +34,7 @@
 ''');
   }
 
-  test_all_diverseImports2() async {
+  Future<void> test_all_diverseImports2() async {
     await resolveTestUnit('''
 import 'dart:async';
 import 'dart:math' as math;
@@ -55,7 +55,7 @@
 ''');
   }
 
-  test_all_singleLine() async {
+  Future<void> test_all_singleLine() async {
     await resolveTestUnit('''
 import 'dart:math'; import 'dart:math'; import 'dart:math';
 main() {
@@ -67,7 +67,7 @@
 ''');
   }
 
-  test_anotherImportOnLine() async {
+  Future<void> test_anotherImportOnLine() async {
     await resolveTestUnit('''
 import 'dart:math'; import 'dart:async';
 
@@ -86,7 +86,7 @@
 ''');
   }
 
-  test_duplicateImport() async {
+  Future<void> test_duplicateImport() async {
     await resolveTestUnit('''
 import 'dart:math';
 import 'dart:math';
@@ -104,7 +104,7 @@
 ''');
   }
 
-  test_multipleOfSame_all() async {
+  Future<void> test_multipleOfSame_all() async {
     await resolveTestUnit('''
 import 'dart:math';
 import 'dart:math';
@@ -118,7 +118,7 @@
 ''');
   }
 
-  test_severalLines() async {
+  Future<void> test_severalLines() async {
     await resolveTestUnit('''
 import
   'dart:math';
@@ -131,7 +131,7 @@
 ''');
   }
 
-  test_single() async {
+  Future<void> test_single() async {
     await resolveTestUnit('''
 import 'dart:math';
 main() {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_label_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_label_test.dart
index 3b0f339..a709788 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_label_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_label_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveUnusedLabelTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_UNUSED_LABEL;
 
-  test_unused_onWhile() async {
+  Future<void> test_unused_onWhile() async {
     await resolveTestUnit('''
 f() {
   x:
@@ -37,7 +37,7 @@
 ''');
   }
 
-  test_unused_onWhile_sameLine() async {
+  Future<void> test_unused_onWhile_sameLine() async {
     await resolveTestUnit('''
 f() {
   x: while (true) {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_local_variable_test.dart b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_local_variable_test.dart
index c05e4cc..cf625ca 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/remove_unused_local_variable_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/remove_unused_local_variable_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RemoveUnusedLocalVariableTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.REMOVE_UNUSED_LOCAL_VARIABLE;
 
-  test_inArgumentList() async {
+  Future<void> test_inArgumentList() async {
     await resolveTestUnit(r'''
 main() {
   var v = 1;
@@ -34,7 +34,7 @@
 ''');
   }
 
-  test_inArgumentList2() async {
+  Future<void> test_inArgumentList2() async {
     await resolveTestUnit(r'''
 main() {
   var v = 1;
@@ -50,7 +50,7 @@
 ''');
   }
 
-  test_inArgumentList3() async {
+  Future<void> test_inArgumentList3() async {
     await resolveTestUnit(r'''
 main() {
   var v = 1;
@@ -66,7 +66,7 @@
 ''');
   }
 
-  test_inDeclarationList() async {
+  Future<void> test_inDeclarationList() async {
     await resolveTestUnit(r'''
 main() {
   var v = 1, v2 = 3;
@@ -82,7 +82,7 @@
 ''');
   }
 
-  test_inDeclarationList2() async {
+  Future<void> test_inDeclarationList2() async {
     await resolveTestUnit(r'''
 main() {
   var v = 1, v2 = 3;
@@ -97,7 +97,7 @@
 ''');
   }
 
-  test_withReferences() async {
+  Future<void> test_withReferences() async {
     await resolveTestUnit(r'''
 main() {
   var v = 1;
@@ -110,7 +110,7 @@
 ''');
   }
 
-  test_withReferences_beforeDeclaration() async {
+  Future<void> test_withReferences_beforeDeclaration() async {
     // CompileTimeErrorCode.REFERENCED_BEFORE_DECLARATION
     verifyNoTestUnitErrors = false;
     await resolveTestUnit(r'''
diff --git a/pkg/analysis_server/test/src/services/correction/fix/rename_to_camel_case_test.dart b/pkg/analysis_server/test/src/services/correction/fix/rename_to_camel_case_test.dart
index 9c8715a..47d4102 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/rename_to_camel_case_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/rename_to_camel_case_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(RenameToCamelCaseTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.non_constant_identifier_names;
 
-  test_localVariable() async {
+  Future<void> test_localVariable() async {
     await resolveTestUnit('''
 main() {
   int /*LINT*/my_integer_variable = 42;
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_parameter_closure() async {
+  Future<void> test_parameter_closure() async {
     await resolveTestUnit('''
 main() {
   [0, 1, 2].forEach((/*LINT*/my_integer_variable) {
@@ -59,7 +59,7 @@
 ''');
   }
 
-  test_parameter_function() async {
+  Future<void> test_parameter_function() async {
     await resolveTestUnit('''
 main(int /*LINT*/my_integer_variable) {
   print(my_integer_variable);
@@ -72,7 +72,7 @@
 ''');
   }
 
-  test_parameter_method() async {
+  Future<void> test_parameter_method() async {
     await resolveTestUnit('''
 class A {
   main(int /*LINT*/my_integer_variable) {
@@ -89,7 +89,7 @@
 ''');
   }
 
-  test_parameter_optionalNamed() async {
+  Future<void> test_parameter_optionalNamed() async {
     await resolveTestUnit('''
 foo({int /*LINT*/my_integer_variable}) {
   print(my_integer_variable);
@@ -98,7 +98,7 @@
     await assertNoFix();
   }
 
-  test_parameter_optionalPositional() async {
+  Future<void> test_parameter_optionalPositional() async {
     await resolveTestUnit('''
 main([int /*LINT*/my_integer_variable]) {
   print(my_integer_variable);
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_boolean_with_bool_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_boolean_with_bool_test.dart
index 29fe96e..d3e3acc 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_boolean_with_bool_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_boolean_with_bool_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceBooleanWithBoolTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.REPLACE_BOOLEAN_WITH_BOOL;
 
-  test_all() async {
+  Future<void> test_all() async {
     await resolveTestUnit('''
 main() {
   boolean v;
@@ -35,7 +35,7 @@
 ''');
   }
 
-  test_single() async {
+  Future<void> test_single() async {
     await resolveTestUnit('''
 main() {
   boolean v;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_colon_with_equals_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_colon_with_equals_test.dart
index 01296a0..c7e3e59 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_colon_with_equals_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_colon_with_equals_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceColonWithEqualsTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_equal_for_default_values;
 
-  test_method() async {
+  Future<void> test_method() async {
     await resolveTestUnit('''
 void f1({int a}) { }    
 
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_final_with_const_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_final_with_const_test.dart
index 48416db..60ea7bc 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_final_with_const_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_final_with_const_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceFinalWithConstTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_const_declarations;
 
-  test_method() async {
+  Future<void> test_method() async {
     await resolveTestUnit('''
 /*LINT*/final int a = 1;
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_new_with_const_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_new_with_const_test.dart
index ae07cfc..95d3073 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_new_with_const_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_new_with_const_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceNewWithConstTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_const_constructors;
 
-  test_basic() async {
+  Future<void> test_basic() async {
     await resolveTestUnit('''
 class C {
   const C();
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_not_present() async {
+  Future<void> test_not_present() async {
     await resolveTestUnit('''
 class C {
   const C();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_null_with_closure_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_null_with_closure_test.dart
index f2c38c9..4c6024c 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_null_with_closure_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_null_with_closure_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceNullWithClosureTest);
   });
@@ -27,7 +27,7 @@
   /// where the fix (and lint) expect a NullLiteral.
   /// todo (pq): re-write FixProcessorLintTest to run the actual lints.
   @failingTest
-  test_null_closure_literal() async {
+  Future<void> test_null_closure_literal() async {
     await resolveTestUnit('''
 void f(dynamic x) { }
 main() {
@@ -42,7 +42,7 @@
 ''');
   }
 
-  test_null_closure_named_expression() async {
+  Future<void> test_null_closure_named_expression() async {
     await resolveTestUnit('''
 main() {
   [1, 3, 5].firstWhere((e) => e.isOdd, orElse: /*LINT*/null);
@@ -55,7 +55,7 @@
 ''');
   }
 
-  test_null_closure_named_expression_with_args() async {
+  Future<void> test_null_closure_named_expression_with_args() async {
     await resolveTestUnit('''
 void f({int closure(x, y)}) { }
 main() {
@@ -70,7 +70,7 @@
 ''');
   }
 
-  test_null_closure_named_expression_with_args_2() async {
+  Future<void> test_null_closure_named_expression_with_args_2() async {
     await resolveTestUnit('''
 void f({int closure(x, y, {z})}) { }
 main() {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_return_type_future_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_return_type_future_test.dart
index 244178e..c7f6976 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_return_type_future_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_return_type_future_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceReturnTypeFutureTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.REPLACE_RETURN_TYPE_FUTURE;
 
-  test_adjacentNodes_withImport() async {
+  Future<void> test_adjacentNodes_withImport() async {
     await resolveTestUnit('''
 import 'dart:async';
 var v;int main() async => 0;
@@ -33,7 +33,7 @@
     });
   }
 
-  test_adjacentNodes_withoutImport() async {
+  Future<void> test_adjacentNodes_withoutImport() async {
     await resolveTestUnit('''
 var v;int main() async => 0;
 ''');
@@ -44,7 +44,7 @@
     });
   }
 
-  test_complexTypeName_withImport() async {
+  Future<void> test_complexTypeName_withImport() async {
     await resolveTestUnit('''
 import 'dart:async';
 List<int> main() async {
@@ -60,7 +60,7 @@
   }
 
   @failingTest
-  test_complexTypeName_withoutImport() async {
+  Future<void> test_complexTypeName_withoutImport() async {
     await resolveTestUnit('''
 List<int> main() async {
 }
@@ -75,7 +75,7 @@
     });
   }
 
-  test_importedWithPrefix() async {
+  Future<void> test_importedWithPrefix() async {
     await resolveTestUnit('''
 import 'dart:async' as al;
 int main() async {
@@ -90,7 +90,7 @@
     });
   }
 
-  test_simpleTypeName_withImport() async {
+  Future<void> test_simpleTypeName_withImport() async {
     await resolveTestUnit('''
 import 'dart:async';
 int main() async => 0;
@@ -104,7 +104,7 @@
   }
 
   @failingTest
-  test_simpleTypeName_withoutImport() async {
+  Future<void> test_simpleTypeName_withoutImport() async {
     await resolveTestUnit('''
 int main() async => 0;
 ''');
@@ -117,7 +117,7 @@
     });
   }
 
-  test_withLibraryDirective_withImport() async {
+  Future<void> test_withLibraryDirective_withImport() async {
     await resolveTestUnit('''
 library main;
 import 'dart:async';
@@ -134,7 +134,7 @@
     });
   }
 
-  test_withLibraryDirective_withoutImport() async {
+  Future<void> test_withLibraryDirective_withoutImport() async {
     await resolveTestUnit('''
 library main;
 int main() async {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_var_with_dynamic_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_var_with_dynamic_test.dart
index f0463c8..39f3c9f 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_var_with_dynamic_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_var_with_dynamic_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceVarWithDynamicTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.REPLACE_VAR_WITH_DYNAMIC;
 
-  test_simple() async {
+  Future<void> test_simple() async {
     await resolveTestUnit('''
 class A {
   Map<String, var> m;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_with_brackets_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_with_brackets_test.dart
index bac5617..1d5ddaf 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_with_brackets_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_with_brackets_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceWithBracketsTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.empty_statements;
 
-  test_outOfBlock_otherLine() async {
+  Future<void> test_outOfBlock_otherLine() async {
     await resolveTestUnit('''
 void foo() {
   while(true)
@@ -39,7 +39,7 @@
 ''');
   }
 
-  test_outOfBlock_sameLine() async {
+  Future<void> test_outOfBlock_sameLine() async {
     await resolveTestUnit('''
 void foo() {
   while(true)/*LINT*/;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_with_conditional_assignment_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_with_conditional_assignment_test.dart
index cfca8d5..c54e29a 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_with_conditional_assignment_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_with_conditional_assignment_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceWithConditionalAssignmentTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_conditional_assignment;
 
-  test_withCodeBeforeAndAfter() async {
+  Future<void> test_withCodeBeforeAndAfter() async {
     await resolveTestUnit('''
 class Person {
   String _fullName;
@@ -48,7 +48,7 @@
 ''');
   }
 
-  test_withOneBlock() async {
+  Future<void> test_withOneBlock() async {
     await resolveTestUnit('''
 class Person {
   String _fullName;
@@ -69,7 +69,7 @@
 ''');
   }
 
-  test_withoutBlock() async {
+  Future<void> test_withoutBlock() async {
     await resolveTestUnit('''
 class Person {
   String _fullName;
@@ -89,7 +89,7 @@
 ''');
   }
 
-  test_withTwoBlock() async {
+  Future<void> test_withTwoBlock() async {
     await resolveTestUnit('''
 class Person {
   String _fullName;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_with_extension_name_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_with_extension_name_test.dart
index b31de86..bd4dfcd 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_with_extension_name_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_with_extension_name_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceWithExtensionNameTest);
   });
@@ -26,7 +26,7 @@
     createAnalysisOptionsFile(experiments: [EnableString.extension_methods]);
   }
 
-  test_getter() async {
+  Future<void> test_getter() async {
     await resolveTestUnit('''
 extension E on String {
   static int get g => 0;
@@ -47,7 +47,7 @@
 ''');
   }
 
-  test_method() async {
+  Future<void> test_method() async {
     await resolveTestUnit('''
 extension E on String {
   static int m() => 0;
@@ -68,7 +68,7 @@
 ''');
   }
 
-  test_qualified() async {
+  Future<void> test_qualified() async {
     newFile('/home/test/lib/ext.dart', content: '''
 extension E on String {
   static int m() => 0;
@@ -90,7 +90,7 @@
 ''');
   }
 
-  test_setter() async {
+  Future<void> test_setter() async {
     await resolveTestUnit('''
 extension E on String {
   static set s(int i) {}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_with_identifier_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_with_identifier_test.dart
index a4cc442..5a5b9c3 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_with_identifier_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_with_identifier_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceWithIdentifierTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.avoid_types_on_closure_parameters;
 
-  test_functionTypedFormalParameter() async {
+  Future<void> test_functionTypedFormalParameter() async {
     await resolveTestUnit('''
 var functionWithFunction = (/*LINT*/int f(int x)) => f(0);
 ''');
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_with_is_empty_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_with_is_empty_test.dart
index 909b335..1ecf23e 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_with_is_empty_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_with_is_empty_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceWithIsEmptyTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_is_empty;
 
-  test_constantOnLeft_equal() async {
+  Future<void> test_constantOnLeft_equal() async {
     await resolveTestUnit('''
 f(List c) {
   if (/*LINT*/0 == c.length) {}
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_constantOnLeft_greaterThan() async {
+  Future<void> test_constantOnLeft_greaterThan() async {
     await resolveTestUnit('''
 f(List c) {
   if (/*LINT*/1 > c.length) {}
@@ -49,7 +49,7 @@
 ''');
   }
 
-  test_constantOnLeft_greaterThanOrEqual() async {
+  Future<void> test_constantOnLeft_greaterThanOrEqual() async {
     await resolveTestUnit('''
 f(List c) {
   if (/*LINT*/0 >= c.length) {}
@@ -62,7 +62,7 @@
 ''');
   }
 
-  test_constantOnRight_equal() async {
+  Future<void> test_constantOnRight_equal() async {
     await resolveTestUnit('''
 f(List c) {
   if (/*LINT*/c.length == 0) {}
@@ -75,7 +75,7 @@
 ''');
   }
 
-  test_constantOnRight_lessThan() async {
+  Future<void> test_constantOnRight_lessThan() async {
     await resolveTestUnit('''
 f(List c) {
   if (/*LINT*/c.length < 1) {}
@@ -88,7 +88,7 @@
 ''');
   }
 
-  test_constantOnRight_lessThanOrEqual() async {
+  Future<void> test_constantOnRight_lessThanOrEqual() async {
     await resolveTestUnit('''
 f(List c) {
   if (/*LINT*/c.length <= 0) {}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_with_is_not_empty_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_with_is_not_empty_test.dart
index 2fda33b..c26dbb6 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_with_is_not_empty_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_with_is_not_empty_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceWithIsNotEmptyTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_is_empty;
 
-  test_constantOnLeft_lessThanOrEqual() async {
+  Future<void> test_constantOnLeft_lessThanOrEqual() async {
     await resolveTestUnit('''
 f(List c) {
   if (/*LINT*/1 <= c.length) {}
@@ -36,7 +36,7 @@
 ''');
   }
 
-  test_constantOnLeft_notEqual() async {
+  Future<void> test_constantOnLeft_notEqual() async {
     await resolveTestUnit('''
 f(List c) {
   if (/*LINT*/0 != c.length) {}
@@ -49,7 +49,7 @@
 ''');
   }
 
-  test_constantOnRight_greaterThanOrEqual() async {
+  Future<void> test_constantOnRight_greaterThanOrEqual() async {
     await resolveTestUnit('''
 f(List c) {
   if (/*LINT*/c.length >= 1) {}
@@ -62,7 +62,7 @@
 ''');
   }
 
-  test_constantOnRight_notEqual() async {
+  Future<void> test_constantOnRight_notEqual() async {
     await resolveTestUnit('''
 f(List c) {
   if (/*LINT*/c.length != 0) {}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_with_null_aware_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_with_null_aware_test.dart
index f758081..526cecc 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_with_null_aware_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_with_null_aware_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceWithNullAwareTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.REPLACE_WITH_NULL_AWARE;
 
-  test_chain() async {
+  Future<void> test_chain() async {
     await resolveTestUnit('''
 main(x) {
   x?.a.b.c;
@@ -32,7 +32,7 @@
 ''');
   }
 
-  test_methodInvocation() async {
+  Future<void> test_methodInvocation() async {
     await resolveTestUnit('''
 main(x) {
   x?.a.b();
@@ -45,7 +45,7 @@
 ''');
   }
 
-  test_propertyAccess() async {
+  Future<void> test_propertyAccess() async {
     await resolveTestUnit('''
 main(x) {
   x?.a().b;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_with_tear_off_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_with_tear_off_test.dart
index 88cc858..2199104 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_with_tear_off_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_with_tear_off_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceWithTearOffTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.unnecessary_lambdas;
 
-  test_function_oneParameter() async {
+  Future<void> test_function_oneParameter() async {
     await resolveTestUnit('''
 final x = /*LINT*/(name) {
   print(name);
@@ -34,7 +34,7 @@
 ''');
   }
 
-  test_function_zeroParameters() async {
+  Future<void> test_function_zeroParameters() async {
     await resolveTestUnit('''
 void foo(){}
 Function finalVar() {
@@ -51,7 +51,7 @@
 ''');
   }
 
-  test_lambda_asArgument() async {
+  Future<void> test_lambda_asArgument() async {
     await resolveTestUnit('''
 void foo() {
   bool isPair(int a) => a % 2 == 0;
@@ -69,7 +69,7 @@
 ''');
   }
 
-  test_method_oneParameter() async {
+  Future<void> test_method_oneParameter() async {
     await resolveTestUnit('''
 var a = /*LINT*/(x) => finalList.remove(x);
 ''');
@@ -78,7 +78,7 @@
 ''');
   }
 
-  test_method_zeroParameter() async {
+  Future<void> test_method_zeroParameter() async {
     await resolveTestUnit('''
 final Object a;
 Function finalVar() {
diff --git a/pkg/analysis_server/test/src/services/correction/fix/replace_with_var_test.dart b/pkg/analysis_server/test/src/services/correction/fix/replace_with_var_test.dart
index a657b44..b1b2d9c 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/replace_with_var_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/replace_with_var_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ReplaceWithVarTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.omit_local_variable_types;
 
-  test_for() async {
+  Future<void> test_for() async {
     await resolveTestUnit('''
 void f(List<int> list) {
   for (/*LINT*/int i = 0; i < list.length; i++) {
@@ -40,7 +40,7 @@
 ''');
   }
 
-  test_forEach() async {
+  Future<void> test_forEach() async {
     await resolveTestUnit('''
 void f(List<int> list) {
   for (/*LINT*/int i in list) {
@@ -57,7 +57,7 @@
 ''');
   }
 
-  test_generic_instanceCreation_withArguments() async {
+  Future<void> test_generic_instanceCreation_withArguments() async {
     await resolveTestUnit('''
 C<int> f() {
   /*LINT*/C<int> c = C<int>();
@@ -74,7 +74,7 @@
 ''');
   }
 
-  test_generic_instanceCreation_withoutArguments() async {
+  Future<void> test_generic_instanceCreation_withoutArguments() async {
     await resolveTestUnit('''
 C<int> f() {
   /*LINT*/C<int> c = C();
@@ -91,7 +91,7 @@
 ''');
   }
 
-  test_generic_listLiteral() async {
+  Future<void> test_generic_listLiteral() async {
     await resolveTestUnit('''
 List f() {
   /*LINT*/List<int> l = [];
@@ -106,7 +106,7 @@
 ''');
   }
 
-  test_generic_mapLiteral() async {
+  Future<void> test_generic_mapLiteral() async {
     await resolveTestUnit('''
 Map f() {
   /*LINT*/Map<String, int> m = {};
@@ -121,7 +121,7 @@
 ''');
   }
 
-  test_generic_setLiteral() async {
+  Future<void> test_generic_setLiteral() async {
     await resolveTestUnit('''
 Set f() {
   /*LINT*/Set<int> s = {};
@@ -136,7 +136,7 @@
 ''');
   }
 
-  test_generic_setLiteral_ambiguous() async {
+  Future<void> test_generic_setLiteral_ambiguous() async {
     await resolveTestUnit('''
 Set f() {
   /*LINT*/Set s = {};
@@ -146,7 +146,7 @@
     await assertNoFix();
   }
 
-  test_simple() async {
+  Future<void> test_simple() async {
     await resolveTestUnit('''
 String f() {
   /*LINT*/String s = '';
diff --git a/pkg/analysis_server/test/src/services/correction/fix/sort_child_property_last_test.dart b/pkg/analysis_server/test/src/services/correction/fix/sort_child_property_last_test.dart
index d9e72c7..035a6cf 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/sort_child_property_last_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/sort_child_property_last_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(SortChildPropertiesLastTest);
   });
@@ -24,7 +24,7 @@
   String get lintCode => LintNames.sort_child_properties_last;
 
   /// More coverage in the `sort_child_properties_last_test.dart` assist test.
-  test_sort() async {
+  Future<void> test_sort() async {
     addFlutterPackage();
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
diff --git a/pkg/analysis_server/test/src/services/correction/fix/test_all.dart b/pkg/analysis_server/test/src/services/correction/fix/test_all.dart
index 3a8d4a1..cb1657b 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/test_all.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/test_all.dart
@@ -149,7 +149,7 @@
 import 'use_not_eq_null_test.dart' as use_not_eq_null;
 import 'use_rethrow_test.dart' as use_rethrow;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     add_async.main();
     add_await.main();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/update_sdk_constraints_test.dart b/pkg/analysis_server/test/src/services/correction/fix/update_sdk_constraints_test.dart
index f6f3724..7dc77c9 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/update_sdk_constraints_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/update_sdk_constraints_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UpdateSdkConstraintsTest);
   });
@@ -20,11 +20,11 @@
   @override
   FixKind get kind => DartFixKind.UPDATE_SDK_CONSTRAINTS;
 
-  test_any() async {
+  Future<void> test_any() async {
     await testUpdate(from: 'any', to: '^2.1.0');
   }
 
-  test_asInConstContext() async {
+  Future<void> test_asInConstContext() async {
     createAnalysisOptionsFile(experiments: [EnableString.constant_update_2018]);
     await testUpdate(content: '''
 const dynamic a = 2;
@@ -32,22 +32,22 @@
 ''', to: '^2.2.2');
   }
 
-  test_boolOperator() async {
+  Future<void> test_boolOperator() async {
     createAnalysisOptionsFile(experiments: [EnableString.constant_update_2018]);
     await testUpdate(content: '''
 const c = true & false;
 ''', to: '^2.2.2');
   }
 
-  test_caret() async {
+  Future<void> test_caret() async {
     await testUpdate(from: '^2.0.0', to: '^2.1.0');
   }
 
-  test_compound() async {
+  Future<void> test_compound() async {
     await testUpdate(from: "'>=2.0.0 <3.0.0'", to: "'>=2.1.0 <3.0.0'");
   }
 
-  test_eqEqOperatorInConstContext() async {
+  Future<void> test_eqEqOperatorInConstContext() async {
     await testUpdate(content: '''
 class A {
   const A();
@@ -57,15 +57,15 @@
 ''', to: '^2.2.2');
   }
 
-  test_gt() async {
+  Future<void> test_gt() async {
     await testUpdate(from: "'>2.0.0'", to: "'>=2.1.0'");
   }
 
-  test_gte() async {
+  Future<void> test_gte() async {
     await testUpdate(from: "'>=2.0.0'", to: "'>=2.1.0'");
   }
 
-  test_gtGtGtOperator() async {
+  Future<void> test_gtGtGtOperator() async {
     createAnalysisOptionsFile(experiments: [EnableString.triple_shift]);
     await testUpdate(content: '''
 class C {
@@ -74,7 +74,7 @@
 ''', to: '^2.2.2');
   }
 
-  test_isInConstContext() async {
+  Future<void> test_isInConstContext() async {
     createAnalysisOptionsFile(experiments: [EnableString.constant_update_2018]);
     await testUpdate(content: '''
 const a = 0;
@@ -82,13 +82,14 @@
 ''', to: '^2.2.2');
   }
 
-  test_setLiteral() async {
+  Future<void> test_setLiteral() async {
     await testUpdate(content: '''
 var s = <int>{};
 ''', to: '^2.2.0');
   }
 
-  testUpdate({String content, String from = '^2.0.0', String to}) async {
+  Future<void> testUpdate(
+      {String content, String from = '^2.0.0', String to}) async {
     updateTestPubspecFile('''
 environment:
   sdk: $from
diff --git a/pkg/analysis_server/test/src/services/correction/fix/use_const_test.dart b/pkg/analysis_server/test/src/services/correction/fix/use_const_test.dart
index 9ac1952..fca39ddf 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/use_const_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/use_const_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UseConstTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.USE_CONST;
 
-  test_explicitNew() async {
+  Future<void> test_explicitNew() async {
     await resolveTestUnit('''
 class A {
   const A();
diff --git a/pkg/analysis_server/test/src/services/correction/fix/use_effective_integer_division_test.dart b/pkg/analysis_server/test/src/services/correction/fix/use_effective_integer_division_test.dart
index 770f505..d47bc80 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/use_effective_integer_division_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/use_effective_integer_division_test.dart
@@ -8,7 +8,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UseEffectiveIntegerDivisionTest);
   });
@@ -19,7 +19,7 @@
   @override
   FixKind get kind => DartFixKind.USE_EFFECTIVE_INTEGER_DIVISION;
 
-  test_normalDivision() async {
+  Future<void> test_normalDivision() async {
     await resolveTestUnit('''
 main() {
   var a = 5;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/use_eq_eq_null_test.dart b/pkg/analysis_server/test/src/services/correction/fix/use_eq_eq_null_test.dart
index de6b873..c2203bb 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/use_eq_eq_null_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/use_eq_eq_null_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UseEqEqNullTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.USE_EQ_EQ_NULL;
 
-  test_isNull() async {
+  Future<void> test_isNull() async {
     await resolveTestUnit('''
 main(p) {
   p is Null;
@@ -33,7 +33,7 @@
 ''');
   }
 
-  test_isNull_all() async {
+  Future<void> test_isNull_all() async {
     await resolveTestUnit('''
 main(p, q) {
   p is Null;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/use_is_not_empty_test.dart b/pkg/analysis_server/test/src/services/correction/fix/use_is_not_empty_test.dart
index b2e3bec..b413b49 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/use_is_not_empty_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/use_is_not_empty_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UseIsNotEmptyTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.prefer_is_not_empty;
 
-  test_notIsEmpty() async {
+  Future<void> test_notIsEmpty() async {
     await resolveTestUnit('''
 f(c) {
   if (/*LINT*/!c.isEmpty) {}
diff --git a/pkg/analysis_server/test/src/services/correction/fix/use_not_eq_null_test.dart b/pkg/analysis_server/test/src/services/correction/fix/use_not_eq_null_test.dart
index 3fdd82a..f4c8590 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/use_not_eq_null_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/use_not_eq_null_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UseNotEqNullTest);
   });
@@ -20,7 +20,7 @@
   @override
   FixKind get kind => DartFixKind.USE_NOT_EQ_NULL;
 
-  test_isNotNull() async {
+  Future<void> test_isNotNull() async {
     await resolveTestUnit('''
 main(p) {
   p is! Null;
@@ -33,7 +33,7 @@
 ''');
   }
 
-  test_isNotNull_all() async {
+  Future<void> test_isNotNull_all() async {
     await resolveTestUnit('''
 main(p, q) {
   p is! Null;
diff --git a/pkg/analysis_server/test/src/services/correction/fix/use_rethrow_test.dart b/pkg/analysis_server/test/src/services/correction/fix/use_rethrow_test.dart
index 6ad46df..9a4eb7a 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/use_rethrow_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/use_rethrow_test.dart
@@ -9,7 +9,7 @@
 
 import 'fix_processor.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UseRethrowTest);
   });
@@ -23,7 +23,7 @@
   @override
   String get lintCode => LintNames.use_rethrow_when_possible;
 
-  test_rethrow() async {
+  Future<void> test_rethrow() async {
     await resolveTestUnit('''
 void bad1() {
   try {} catch (e) {
diff --git a/pkg/analysis_server/test/src/services/correction/test_all.dart b/pkg/analysis_server/test/src/services/correction/test_all.dart
index 7c6c49d..abc5ddb 100644
--- a/pkg/analysis_server/test/src/services/correction/test_all.dart
+++ b/pkg/analysis_server/test/src/services/correction/test_all.dart
@@ -7,7 +7,7 @@
 import 'assist/test_all.dart' as assist_all;
 import 'fix/test_all.dart' as fix_all;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     assist_all.main();
     fix_all.main();
diff --git a/pkg/analysis_server/test/src/services/flutter/container_properties_test.dart b/pkg/analysis_server/test/src/services/flutter/container_properties_test.dart
index 6968e64..5947dcc 100644
--- a/pkg/analysis_server/test/src/services/flutter/container_properties_test.dart
+++ b/pkg/analysis_server/test/src/services/flutter/container_properties_test.dart
@@ -9,7 +9,7 @@
 import 'constants.dart';
 import 'widget_description.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ContainerPropertiesTest);
     defineReflectiveTests(ContainerPropertyAlignmentTest);
@@ -19,7 +19,7 @@
 
 @reflectiveTest
 class ContainerPropertiesTest extends WidgetDescriptionBase {
-  test_container_existing() async {
+  Future<void> test_container_existing() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -48,7 +48,7 @@
     expect(childrenNames, isNot(contains('child')));
   }
 
-  test_container_virtual() async {
+  Future<void> test_container_virtual() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -81,7 +81,7 @@
 
 @reflectiveTest
 class ContainerPropertyAlignmentTest extends WidgetDescriptionBase {
-  test_read_hasAlign_notSimple() async {
+  Future<void> test_read_hasAlign_notSimple() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -98,7 +98,7 @@
     expect(alignmentProperty.expression, isNull);
   }
 
-  test_read_hasAlign_simple() async {
+  Future<void> test_read_hasAlign_simple() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -130,7 +130,7 @@
 ''');
   }
 
-  test_read_hasContainer() async {
+  Future<void> test_read_hasContainer() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -162,7 +162,7 @@
 ''');
   }
 
-  test_read_hasContainer_directional() async {
+  Future<void> test_read_hasContainer_directional() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -194,7 +194,7 @@
 ''');
   }
 
-  test_write_hasAlign_change() async {
+  Future<void> test_write_hasAlign_change() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -226,7 +226,7 @@
 ''');
   }
 
-  test_write_hasAlign_remove() async {
+  Future<void> test_write_hasAlign_remove() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -255,7 +255,7 @@
 ''');
   }
 
-  test_write_hasContainer_add() async {
+  Future<void> test_write_hasContainer_add() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -286,7 +286,7 @@
 ''');
   }
 
-  test_write_hasContainer_change() async {
+  Future<void> test_write_hasContainer_change() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -318,7 +318,7 @@
 ''');
   }
 
-  test_write_hasContainer_remove() async {
+  Future<void> test_write_hasContainer_remove() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -347,7 +347,7 @@
 ''');
   }
 
-  test_write_hasPadding_add() async {
+  Future<void> test_write_hasPadding_add() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -380,7 +380,7 @@
 ''');
   }
 
-  test_write_noContainer_add() async {
+  Future<void> test_write_noContainer_add() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -437,7 +437,7 @@
 
 @reflectiveTest
 class ContainerPropertyPaddingTest extends WidgetDescriptionBase {
-  test_read_hasContainer_all() async {
+  Future<void> test_read_hasContainer_all() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -515,7 +515,7 @@
 ''');
   }
 
-  test_read_hasContainer_fromLTRB() async {
+  Future<void> test_read_hasContainer_fromLTRB() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -593,7 +593,7 @@
 ''');
   }
 
-  test_read_hasContainer_only() async {
+  Future<void> test_read_hasContainer_only() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -663,7 +663,7 @@
 ''');
   }
 
-  test_read_hasContainer_symmetric() async {
+  Future<void> test_read_hasContainer_symmetric() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -741,7 +741,7 @@
 ''');
   }
 
-  test_read_hasPadding_only() async {
+  Future<void> test_read_hasPadding_only() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -811,7 +811,7 @@
 ''');
   }
 
-  test_write_hasAlign_add_only() async {
+  Future<void> test_write_hasAlign_add_only() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -845,7 +845,7 @@
 ''');
   }
 
-  test_write_hasContainer_add_only() async {
+  Future<void> test_write_hasContainer_add_only() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -877,7 +877,7 @@
 ''');
   }
 
-  test_write_hasContainer_change_all() async {
+  Future<void> test_write_hasContainer_change_all() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -910,7 +910,7 @@
 ''');
   }
 
-  test_write_hasContainer_change_only() async {
+  Future<void> test_write_hasContainer_change_only() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -943,7 +943,7 @@
 ''');
   }
 
-  test_write_hasContainer_change_remove() async {
+  Future<void> test_write_hasContainer_change_remove() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -975,7 +975,7 @@
 ''');
   }
 
-  test_write_hasContainer_change_symmetric_both() async {
+  Future<void> test_write_hasContainer_change_symmetric_both() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -1008,7 +1008,7 @@
 ''');
   }
 
-  test_write_hasContainer_change_symmetric_horizontal() async {
+  Future<void> test_write_hasContainer_change_symmetric_horizontal() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -1041,7 +1041,7 @@
 ''');
   }
 
-  test_write_hasContainer_change_symmetric_vertical() async {
+  Future<void> test_write_hasContainer_change_symmetric_vertical() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -1074,7 +1074,7 @@
 ''');
   }
 
-  test_write_hasPadding_change_only() async {
+  Future<void> test_write_hasPadding_change_only() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -1107,7 +1107,7 @@
 ''');
   }
 
-  test_write_noContainer_add_only() async {
+  Future<void> test_write_noContainer_add_only() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
diff --git a/pkg/analysis_server/test/src/services/flutter/test_all.dart b/pkg/analysis_server/test/src/services/flutter/test_all.dart
index 935e759..c35d704 100644
--- a/pkg/analysis_server/test/src/services/flutter/test_all.dart
+++ b/pkg/analysis_server/test/src/services/flutter/test_all.dart
@@ -7,7 +7,7 @@
 import 'container_properties_test.dart' as container_properties;
 import 'widget_descriptions_test.dart' as widget_descriptions;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     container_properties.main();
     widget_descriptions.main();
diff --git a/pkg/analysis_server/test/src/services/flutter/widget_descriptions_test.dart b/pkg/analysis_server/test/src/services/flutter/widget_descriptions_test.dart
index 980d4b4..4fcb4b3 100644
--- a/pkg/analysis_server/test/src/services/flutter/widget_descriptions_test.dart
+++ b/pkg/analysis_server/test/src/services/flutter/widget_descriptions_test.dart
@@ -8,7 +8,7 @@
 
 import 'widget_description.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(GetDescriptionTest);
     defineReflectiveTests(SetPropertyValueSelfTest);
@@ -17,7 +17,7 @@
 
 @reflectiveTest
 class GetDescriptionTest extends WidgetDescriptionBase {
-  test_kind_named_notSet() async {
+  Future<void> test_kind_named_notSet() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -40,7 +40,7 @@
 ''');
   }
 
-  test_kind_named_set() async {
+  Future<void> test_kind_named_set() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -67,7 +67,7 @@
 ''');
   }
 
-  test_kind_required() async {
+  Future<void> test_kind_required() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -94,7 +94,7 @@
 ''');
   }
 
-  test_nested_notSet() async {
+  Future<void> test_nested_notSet() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -118,7 +118,7 @@
 ''');
   }
 
-  test_nested_set() async {
+  Future<void> test_nested_set() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -171,7 +171,7 @@
 ''');
   }
 
-  test_notInstanceCreation() async {
+  Future<void> test_notInstanceCreation() async {
     await resolveTestUnit('''
 void main() {
   42;
@@ -181,7 +181,7 @@
     expect(description, isNull);
   }
 
-  test_type_double() async {
+  Future<void> test_type_double() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -203,7 +203,7 @@
 ''');
   }
 
-  test_type_enum() async {
+  Future<void> test_type_enum() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -261,7 +261,7 @@
 ''');
   }
 
-  test_type_int() async {
+  Future<void> test_type_int() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -283,7 +283,7 @@
 ''');
   }
 
-  test_unresolvedInstanceCreation() async {
+  Future<void> test_unresolvedInstanceCreation() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 void main() {
@@ -297,7 +297,7 @@
 
 @reflectiveTest
 class SetPropertyValueSelfTest extends WidgetDescriptionBase {
-  test_expression() async {
+  Future<void> test_expression() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -321,7 +321,7 @@
 ''');
   }
 
-  test_expression_formatError() async {
+  Future<void> test_expression_formatError() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -344,7 +344,7 @@
     expect(result.change, isNull);
   }
 
-  test_format_dontFormatOther() async {
+  Future<void> test_format_dontFormatOther() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -387,7 +387,7 @@
 ''');
   }
 
-  test_invalidId() async {
+  Future<void> test_invalidId() async {
     await resolveTestUnit('');
 
     var result = await descriptions.setPropertyValue(42, null);
@@ -399,7 +399,7 @@
     expect(result.change, isNull);
   }
 
-  test_named_addValue_beforeChild() async {
+  Future<void> test_named_addValue_beforeChild() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -436,7 +436,7 @@
 ''');
   }
 
-  test_named_addValue_beforeChildren() async {
+  Future<void> test_named_addValue_beforeChildren() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -473,7 +473,7 @@
 ''');
   }
 
-  test_named_addValue_hasComma() async {
+  Future<void> test_named_addValue_hasComma() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -500,7 +500,7 @@
 ''');
   }
 
-  test_named_addValue_noComma() async {
+  Future<void> test_named_addValue_noComma() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -527,7 +527,7 @@
 ''');
   }
 
-  test_named_addValue_sortedByName_first() async {
+  Future<void> test_named_addValue_sortedByName_first() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -564,7 +564,7 @@
 ''');
   }
 
-  test_named_addValue_sortedByName_last() async {
+  Future<void> test_named_addValue_sortedByName_last() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -601,7 +601,7 @@
 ''');
   }
 
-  test_named_addValue_sortedByName_middle() async {
+  Future<void> test_named_addValue_sortedByName_middle() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -640,7 +640,7 @@
 ''');
   }
 
-  test_named_changeValue() async {
+  Future<void> test_named_changeValue() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -664,7 +664,7 @@
 ''');
   }
 
-  test_named_removeValue_last() async {
+  Future<void> test_named_removeValue_last() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -685,7 +685,7 @@
 ''');
   }
 
-  test_named_removeValue_notLast() async {
+  Future<void> test_named_removeValue_notLast() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -706,7 +706,7 @@
 ''');
   }
 
-  test_nested_addValue() async {
+  Future<void> test_nested_addValue() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -737,7 +737,7 @@
 ''');
   }
 
-  test_nested_addValue_materialize() async {
+  Future<void> test_nested_addValue_materialize() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -768,7 +768,7 @@
 ''');
   }
 
-  test_required_changeValue() async {
+  Future<void> test_required_changeValue() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -792,7 +792,7 @@
 ''');
   }
 
-  test_required_removeValue() async {
+  Future<void> test_required_removeValue() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
@@ -811,7 +811,7 @@
     expect(result.change, isNull);
   }
 
-  test_type_enum_addValue() async {
+  Future<void> test_type_enum_addValue() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 
diff --git a/pkg/analysis_server/test/src/services/test_all.dart b/pkg/analysis_server/test/src/services/test_all.dart
index cc3293f..a2c9b81 100644
--- a/pkg/analysis_server/test/src/services/test_all.dart
+++ b/pkg/analysis_server/test/src/services/test_all.dart
@@ -7,7 +7,7 @@
 import 'correction/test_all.dart' as correction_all;
 import 'flutter/test_all.dart' as flutter_all;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     correction_all.main();
     flutter_all.main();
diff --git a/pkg/analysis_server/test/src/test_all.dart b/pkg/analysis_server/test/src/test_all.dart
index fa37c50..85107e0 100644
--- a/pkg/analysis_server/test/src/test_all.dart
+++ b/pkg/analysis_server/test/src/test_all.dart
@@ -14,10 +14,7 @@
 import 'services/test_all.dart' as services;
 import 'utilities/test_all.dart' as utilities;
 
-/**
- * Utility for manually running all tests.
- */
-main() {
+void main() {
   defineReflectiveSuite(() {
     computer.main();
     domain_abstract.main();
diff --git a/pkg/analysis_server/test/src/utilities/flutter_test.dart b/pkg/analysis_server/test/src/utilities/flutter_test.dart
index ee8db5f..1dd384d 100644
--- a/pkg/analysis_server/test/src/utilities/flutter_test.dart
+++ b/pkg/analysis_server/test/src/utilities/flutter_test.dart
@@ -9,7 +9,7 @@
 
 import '../../abstract_single_unit.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(FlutterTest);
   });
@@ -25,7 +25,7 @@
     addFlutterPackage();
   }
 
-  test_getWidgetPresentationText_icon() async {
+  Future<void> test_getWidgetPresentationText_icon() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 var w = const Icon(Icons.book);
@@ -34,7 +34,7 @@
     expect(flutter.getWidgetPresentationText(w), 'Icon(Icons.book)');
   }
 
-  test_getWidgetPresentationText_icon_withoutArguments() async {
+  Future<void> test_getWidgetPresentationText_icon_withoutArguments() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -44,7 +44,7 @@
     expect(flutter.getWidgetPresentationText(w), 'Icon');
   }
 
-  test_getWidgetPresentationText_notWidget() async {
+  Future<void> test_getWidgetPresentationText_notWidget() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 var w = new Object();
@@ -53,7 +53,7 @@
     expect(flutter.getWidgetPresentationText(w), isNull);
   }
 
-  test_getWidgetPresentationText_text() async {
+  Future<void> test_getWidgetPresentationText_text() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 var w = const Text('foo');
@@ -62,7 +62,7 @@
     expect(flutter.getWidgetPresentationText(w), "Text('foo')");
   }
 
-  test_getWidgetPresentationText_text_longText() async {
+  Future<void> test_getWidgetPresentationText_text_longText() async {
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
 var w = const Text('${'abc' * 100}');
@@ -74,7 +74,7 @@
     );
   }
 
-  test_getWidgetPresentationText_text_withoutArguments() async {
+  Future<void> test_getWidgetPresentationText_text_withoutArguments() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -84,7 +84,7 @@
     expect(flutter.getWidgetPresentationText(w), 'Text');
   }
 
-  test_getWidgetPresentationText_unresolved() async {
+  Future<void> test_getWidgetPresentationText_unresolved() async {
     verifyNoTestUnitErrors = false;
     await resolveTestUnit('''
 import 'package:flutter/material.dart';
@@ -94,7 +94,7 @@
     expect(flutter.getWidgetPresentationText(w), isNull);
   }
 
-  test_identifyWidgetExpression_node_instanceCreation() async {
+  Future<void> test_identifyWidgetExpression_node_instanceCreation() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -150,7 +150,7 @@
     }
   }
 
-  test_identifyWidgetExpression_node_invocation() async {
+  Future<void> test_identifyWidgetExpression_node_invocation() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -183,7 +183,7 @@
     }
   }
 
-  test_identifyWidgetExpression_node_namedExpression() async {
+  Future<void> test_identifyWidgetExpression_node_namedExpression() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -197,7 +197,8 @@
     expect(flutter.identifyWidgetExpression(childExpression), isNull);
   }
 
-  test_identifyWidgetExpression_node_prefixedIdentifier_identifier() async {
+  Future<void>
+      test_identifyWidgetExpression_node_prefixedIdentifier_identifier() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -213,7 +214,8 @@
     expect(flutter.identifyWidgetExpression(bar), bar.parent);
   }
 
-  test_identifyWidgetExpression_node_prefixedIdentifier_prefix() async {
+  Future<void>
+      test_identifyWidgetExpression_node_prefixedIdentifier_prefix() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -229,7 +231,7 @@
     expect(flutter.identifyWidgetExpression(foo), foo.parent);
   }
 
-  test_identifyWidgetExpression_node_simpleIdentifier() async {
+  Future<void> test_identifyWidgetExpression_node_simpleIdentifier() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -241,7 +243,7 @@
     expect(flutter.identifyWidgetExpression(expression), expression);
   }
 
-  test_identifyWidgetExpression_null() async {
+  Future<void> test_identifyWidgetExpression_null() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -264,7 +266,7 @@
     }
   }
 
-  test_identifyWidgetExpression_parent_argumentList() async {
+  Future<void> test_identifyWidgetExpression_parent_argumentList() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -279,7 +281,8 @@
     expect(flutter.identifyWidgetExpression(expression), expression);
   }
 
-  test_identifyWidgetExpression_parent_assignmentExpression() async {
+  Future<void>
+      test_identifyWidgetExpression_parent_assignmentExpression() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -309,7 +312,8 @@
     }
   }
 
-  test_identifyWidgetExpression_parent_conditionalExpression() async {
+  Future<void>
+      test_identifyWidgetExpression_parent_conditionalExpression() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -324,7 +328,8 @@
     expect(flutter.identifyWidgetExpression(elseWidget), elseWidget);
   }
 
-  test_identifyWidgetExpression_parent_expressionFunctionBody() async {
+  Future<void>
+      test_identifyWidgetExpression_parent_expressionFunctionBody() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -334,7 +339,8 @@
     expect(flutter.identifyWidgetExpression(expression), expression);
   }
 
-  test_identifyWidgetExpression_parent_expressionStatement() async {
+  Future<void>
+      test_identifyWidgetExpression_parent_expressionStatement() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -346,7 +352,7 @@
     expect(flutter.identifyWidgetExpression(expression), expression);
   }
 
-  test_identifyWidgetExpression_parent_forElement() async {
+  Future<void> test_identifyWidgetExpression_parent_forElement() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -362,7 +368,7 @@
     expect(flutter.identifyWidgetExpression(expression), expression);
   }
 
-  test_identifyWidgetExpression_parent_ifElement() async {
+  Future<void> test_identifyWidgetExpression_parent_ifElement() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -384,7 +390,7 @@
     expect(flutter.identifyWidgetExpression(elseExpression), elseExpression);
   }
 
-  test_identifyWidgetExpression_parent_listLiteral() async {
+  Future<void> test_identifyWidgetExpression_parent_listLiteral() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -396,7 +402,7 @@
     expect(flutter.identifyWidgetExpression(expression), expression);
   }
 
-  test_identifyWidgetExpression_parent_namedExpression() async {
+  Future<void> test_identifyWidgetExpression_parent_namedExpression() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -411,7 +417,7 @@
     expect(flutter.identifyWidgetExpression(expression), expression);
   }
 
-  test_identifyWidgetExpression_parent_returnStatement() async {
+  Future<void> test_identifyWidgetExpression_parent_returnStatement() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -423,7 +429,7 @@
     expect(flutter.identifyWidgetExpression(expression), expression);
   }
 
-  test_isWidget() async {
+  Future<void> test_isWidget() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -449,7 +455,7 @@
     expect(flutter.isWidget(notWidget), isFalse);
   }
 
-  test_isWidgetCreation() async {
+  Future<void> test_isWidgetCreation() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
@@ -465,7 +471,7 @@
     expect(flutter.isWidgetCreation(b), isTrue);
   }
 
-  test_isWidgetExpression() async {
+  Future<void> test_isWidgetExpression() async {
     await resolveTestUnit('''
 import 'package:flutter/widgets.dart';
 
diff --git a/pkg/analysis_server/test/src/utilities/profiling_test.dart b/pkg/analysis_server/test/src/utilities/profiling_test.dart
index ccc4c22..a846dd1 100644
--- a/pkg/analysis_server/test/src/utilities/profiling_test.dart
+++ b/pkg/analysis_server/test/src/utilities/profiling_test.dart
@@ -7,7 +7,7 @@
 import 'package:analysis_server/src/utilities/profiling.dart';
 import 'package:test/test.dart';
 
-main() {
+void main() {
   group('ProcessProfiler', () {
     // Skip on windows.
     if (Platform.isWindows) {
diff --git a/pkg/analysis_server/test/src/utilities/strings_test.dart b/pkg/analysis_server/test/src/utilities/strings_test.dart
index d1c51f4..0a7ce0d 100644
--- a/pkg/analysis_server/test/src/utilities/strings_test.dart
+++ b/pkg/analysis_server/test/src/utilities/strings_test.dart
@@ -6,7 +6,7 @@
 import 'package:test/test.dart' hide isEmpty;
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(StringsTest);
   });
@@ -31,7 +31,7 @@
   }
 
   void test_computeSimpleDiff() {
-    assertDiff(String oldStr, String newStr) {
+    void assertDiff(String oldStr, String newStr) {
       SimpleDiff diff = computeSimpleDiff(oldStr, newStr);
       expect(diff.offset, isNonNegative);
       expect(diff.length, isNonNegative);
diff --git a/pkg/analysis_server/test/src/utilities/test_all.dart b/pkg/analysis_server/test/src/utilities/test_all.dart
index 1bfac03..a9cd96e 100644
--- a/pkg/analysis_server/test/src/utilities/test_all.dart
+++ b/pkg/analysis_server/test/src/utilities/test_all.dart
@@ -8,7 +8,7 @@
 import 'profiling_test.dart' as profiling_test;
 import 'strings_test.dart' as strings_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     flutter_test.main();
     profiling_test.main();
diff --git a/pkg/analysis_server/test/stress/completion/completion_runner.dart b/pkg/analysis_server/test/stress/completion/completion_runner.dart
index 684a67b..e114f0d 100644
--- a/pkg/analysis_server/test/stress/completion/completion_runner.dart
+++ b/pkg/analysis_server/test/stress/completion/completion_runner.dart
@@ -290,7 +290,7 @@
   final List<SimpleIdentifier> identifiers = <SimpleIdentifier>[];
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     identifiers.add(node);
   }
 }
diff --git a/pkg/analysis_server/test/test_all.dart b/pkg/analysis_server/test/test_all.dart
index 9d87caa..9ed34eb 100644
--- a/pkg/analysis_server/test/test_all.dart
+++ b/pkg/analysis_server/test/test_all.dart
@@ -29,7 +29,7 @@
 import 'tool/test_all.dart' as tool;
 import 'verify_tests_test.dart' as verify_tests;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     analysis.main();
     analysis_server.main();
@@ -62,7 +62,7 @@
 
 @reflectiveTest
 class SpecTest {
-  test_specHasBeenGenerated() {
+  void test_specHasBeenGenerated() {
     check_spec.main();
   }
 }
diff --git a/pkg/analysis_server/test/tool/lsp_spec/dart_test.dart b/pkg/analysis_server/test/tool/lsp_spec/dart_test.dart
index 7a4f91e..9a3d26f 100644
--- a/pkg/analysis_server/test/tool/lsp_spec/dart_test.dart
+++ b/pkg/analysis_server/test/tool/lsp_spec/dart_test.dart
@@ -6,7 +6,7 @@
 
 import '../../../tool/lsp_spec/typescript_parser.dart' as ast;
 
-main() {
+void main() {
   group('dartType mapping', () {
     test('handles basic types', () {
       expect(_simple('string').dartType, equals('String'));
diff --git a/pkg/analysis_server/test/tool/lsp_spec/json_test.dart b/pkg/analysis_server/test/tool/lsp_spec/json_test.dart
index 0ec2b14..37450f5 100644
--- a/pkg/analysis_server/test/tool/lsp_spec/json_test.dart
+++ b/pkg/analysis_server/test/tool/lsp_spec/json_test.dart
@@ -9,7 +9,7 @@
 import 'package:analysis_server/src/lsp/json_parsing.dart';
 import 'package:test/test.dart';
 
-main() {
+void main() {
   group('toJson', () {
     test('returns correct JSON for a union', () {
       final _num = Either2.t1(1);
diff --git a/pkg/analysis_server/test/tool/lsp_spec/markdown_test.dart b/pkg/analysis_server/test/tool/lsp_spec/markdown_test.dart
index 23afaca..834617f 100644
--- a/pkg/analysis_server/test/tool/lsp_spec/markdown_test.dart
+++ b/pkg/analysis_server/test/tool/lsp_spec/markdown_test.dart
@@ -6,7 +6,7 @@
 
 import '../../../tool/lsp_spec/markdown.dart';
 
-main() {
+void main() {
   group('markdown parser', () {
     test('extracts a typescript fenced block from Markdown', () {
       final String input = '''
diff --git a/pkg/analysis_server/test/tool/lsp_spec/test_all.dart b/pkg/analysis_server/test/tool/lsp_spec/test_all.dart
index 1edfb80..1717817 100644
--- a/pkg/analysis_server/test/tool/lsp_spec/test_all.dart
+++ b/pkg/analysis_server/test/tool/lsp_spec/test_all.dart
@@ -9,7 +9,7 @@
 import 'markdown_test.dart' as markdown_test;
 import 'typescript_test.dart' as typescript_test;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     dart_test.main();
     json_test.main();
diff --git a/pkg/analysis_server/test/tool/lsp_spec/typescript_test.dart b/pkg/analysis_server/test/tool/lsp_spec/typescript_test.dart
index e3e874e..9464b50 100644
--- a/pkg/analysis_server/test/tool/lsp_spec/typescript_test.dart
+++ b/pkg/analysis_server/test/tool/lsp_spec/typescript_test.dart
@@ -7,7 +7,7 @@
 import '../../../tool/lsp_spec/typescript_parser.dart';
 import 'matchers.dart';
 
-main() {
+void main() {
   group('typescript parser', () {
     test('parses an interface', () {
       final String input = '''
diff --git a/pkg/analysis_server/test/tool/test_all.dart b/pkg/analysis_server/test/tool/test_all.dart
index 8f79e7d..e70aa9b 100644
--- a/pkg/analysis_server/test/tool/test_all.dart
+++ b/pkg/analysis_server/test/tool/test_all.dart
@@ -6,7 +6,7 @@
 
 import 'lsp_spec/test_all.dart' as lsp_spec;
 
-main() {
+void main() {
   defineReflectiveSuite(() {
     lsp_spec.main();
   }, name: 'tool');
diff --git a/pkg/analysis_server/test/verify_tests_test.dart b/pkg/analysis_server/test/verify_tests_test.dart
index d84d489..73ad1dc 100644
--- a/pkg/analysis_server/test/verify_tests_test.dart
+++ b/pkg/analysis_server/test/verify_tests_test.dart
@@ -14,7 +14,7 @@
 
 import 'utils/package_root.dart' as package_root;
 
-main() {
+void main() {
   PhysicalResourceProvider provider = PhysicalResourceProvider.INSTANCE;
   String packageRoot = provider.pathContext.normalize(package_root.packageRoot);
   String analysisServerPath =
diff --git a/pkg/analysis_server/tool/completion_metrics/completion_metrics.dart b/pkg/analysis_server/tool/completion_metrics/completion_metrics.dart
index 629549a..e3cbbcb 100644
--- a/pkg/analysis_server/tool/completion_metrics/completion_metrics.dart
+++ b/pkg/analysis_server/tool/completion_metrics/completion_metrics.dart
@@ -14,17 +14,20 @@
 import 'package:analysis_server/src/status/pages.dart';
 import 'package:analyzer/dart/analysis/analysis_context_collection.dart';
 import 'package:analyzer/dart/analysis/results.dart';
+import 'package:analyzer/diagnostic/diagnostic.dart';
+import 'package:analyzer/error/error.dart' as err;
 import 'package:analyzer/file_system/physical_file_system.dart';
 import 'package:analyzer/src/dart/analysis/byte_store.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/services/available_declarations.dart';
 
 import 'metrics_util.dart';
+import 'relevance_analyzers.dart';
 import 'visitors.dart';
 
 // TODO(jwren) have the analysis root and verbose option be configurable via a
 //  command line UX
-main() async {
+Future<void> main() async {
   await CompletionMetricsComputer('', true).computeCompletionMetrics();
 }
 
@@ -39,11 +42,14 @@
   /// stdout.
   final bool _verbose;
 
+  final RelevanceAnalyzer _relevanceAnalyzer = null;
+
   CompletionMetricsComputer(this._rootPath, this._verbose);
 
   Future computeCompletionMetrics() async {
     int includedCount = 0;
     int notIncludedCount = 0;
+    var completionMissedTokenCounter = Counter('missing completion counter');
     var completionKindCounter = Counter('completion kind counter');
     var completionElementKindCounter =
         Counter('completion element kind counter');
@@ -75,8 +81,18 @@
           try {
             final resolvedUnitResult =
                 await context.currentSession.getResolvedUnit(filePath);
-            final visitor = ExpectedCompletionsVisitor();
 
+            var error = _getFirstErrorOrNull(resolvedUnitResult);
+            if (error != null) {
+              print('File $filePath skipped due to errors such as:');
+              print('  ${error.toString()}');
+              print('');
+              continue;
+            }
+
+            // Use the ExpectedCompletionsVisitor to compute the set of expected
+            // completions for this CompilationUnit.
+            final visitor = ExpectedCompletionsVisitor();
             resolvedUnitResult.unit.accept(visitor);
 
             for (var expectedCompletion in visitor.expectedCompletions) {
@@ -90,11 +106,15 @@
 
               mRRComputer.addReciprocalRank(place);
 
+              _relevanceAnalyzer?.report(expectedCompletion);
+
               if (place.denominator != 0) {
                 includedCount++;
               } else {
                 notIncludedCount++;
 
+                completionMissedTokenCounter
+                    .count(expectedCompletion.completion);
                 completionKindCounter.count(expectedCompletion.kind.toString());
                 completionElementKindCounter
                     .count(expectedCompletion.elementKind.toString());
@@ -122,6 +142,9 @@
     final percentIncluded = includedCount / totalCompletionCount;
     final percentNotIncluded = 1 - percentIncluded;
 
+    completionMissedTokenCounter.printCounterValues();
+    print('');
+
     completionKindCounter.printCounterValues();
     print('');
 
@@ -140,9 +163,13 @@
 
     includedCount = 0;
     notIncludedCount = 0;
+    completionMissedTokenCounter.clear();
     completionKindCounter.clear();
     completionElementKindCounter.clear();
     mRRComputer.clear();
+
+    _relevanceAnalyzer?.printData();
+    _relevanceAnalyzer?.clear();
   }
 
   Future<List<CompletionSuggestion>> _computeCompletionSuggestions(
@@ -185,6 +212,18 @@
     return suggestions;
   }
 
+  /// Given some [ResolvedUnitResult] return the first error of high severity
+  /// if such an error exists, null otherwise.
+  err.AnalysisError _getFirstErrorOrNull(
+      ResolvedUnitResult resolvedUnitResult) {
+    for (var error in resolvedUnitResult.errors) {
+      if (error.severity == Severity.error) {
+        return error;
+      }
+    }
+    return null;
+  }
+
   Place _placementInSuggestionList(List<CompletionSuggestion> suggestions,
       ExpectedCompletion expectedCompletion) {
     var placeCounter = 1;
diff --git a/pkg/analysis_server/tool/completion_metrics/relevance_analyzers.dart b/pkg/analysis_server/tool/completion_metrics/relevance_analyzers.dart
new file mode 100644
index 0000000..ff8fc20
--- /dev/null
+++ b/pkg/analysis_server/tool/completion_metrics/relevance_analyzers.dart
@@ -0,0 +1,51 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/dart/ast/ast.dart';
+
+import 'metrics_util.dart';
+import 'visitors.dart';
+
+abstract class RelevanceAnalyzer {
+  final String _name;
+  final Counter _counter;
+
+  RelevanceAnalyzer(this._name)
+      : _counter = Counter('$_name element kind counter');
+
+  String get name => _name;
+
+  void clear() => _counter.clear();
+
+  bool isApplicable(ExpectedCompletion expectedCompletion);
+
+  void printData() {
+    _counter.printCounterValues();
+  }
+
+  void report(ExpectedCompletion expectedCompletion) {
+    if (isApplicable(expectedCompletion)) {
+      _counter.count(expectedCompletion.elementKind.toString());
+    }
+  }
+}
+
+class RHSOfAsExpression extends RelevanceAnalyzer {
+  RHSOfAsExpression() : super('RHS Of AsExpression');
+
+  @override
+  bool isApplicable(ExpectedCompletion expectedCompletion) {
+    var entity = expectedCompletion.syntacticEntity;
+    if (entity is AstNode) {
+      var asExpression = entity.thisOrAncestorOfType<AsExpression>();
+      if (asExpression != null) {
+        var typeAnnotation = asExpression.type;
+        if (typeAnnotation is TypeName) {
+          return typeAnnotation.name == entity;
+        }
+      }
+    }
+    return false;
+  }
+}
diff --git a/pkg/analysis_server/tool/completion_metrics/visitors.dart b/pkg/analysis_server/tool/completion_metrics/visitors.dart
index f1c0f4e..dcb21a8 100644
--- a/pkg/analysis_server/tool/completion_metrics/visitors.dart
+++ b/pkg/analysis_server/tool/completion_metrics/visitors.dart
@@ -8,6 +8,7 @@
 import 'package:analyzer/dart/ast/syntactic_entity.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
+import 'package:analyzer/dart/element/element.dart' as element;
 
 class ExpectedCompletion {
   final SyntacticEntity _entity;
@@ -69,7 +70,7 @@
   }
 }
 
-class ExpectedCompletionsVisitor extends RecursiveAstVisitor {
+class ExpectedCompletionsVisitor extends RecursiveAstVisitor<void> {
   final List<ExpectedCompletion> expectedCompletions;
 
   CompilationUnit _enclosingCompilationUnit;
@@ -89,7 +90,7 @@
 
   ExpectedCompletionsVisitor() : expectedCompletions = <ExpectedCompletion>[];
 
-  safelyRecordEntity(SyntacticEntity entity,
+  void safelyRecordEntity(SyntacticEntity entity,
       {protocol.CompletionSuggestionKind kind,
       protocol.ElementKind elementKind}) {
     // Only record if this entity is not null, has a length, etc.
@@ -156,7 +157,7 @@
     }
   }
 
-  safelyRecordKeywordCompletion(SyntacticEntity entity) {
+  void safelyRecordKeywordCompletion(SyntacticEntity entity) {
     if (_doExpectKeywordCompletions) {
       safelyRecordEntity(entity,
           kind: protocol.CompletionSuggestionKind.KEYWORD);
@@ -164,39 +165,39 @@
   }
 
   @override
-  visitAsExpression(AsExpression node) {
+  void visitAsExpression(AsExpression node) {
     safelyRecordKeywordCompletion(node.asOperator);
     return super.visitAsExpression(node);
   }
 
   @override
-  visitAwaitExpression(AwaitExpression node) {
+  void visitAwaitExpression(AwaitExpression node) {
     safelyRecordKeywordCompletion(node.awaitKeyword);
     return super.visitAwaitExpression(node);
   }
 
   @override
-  visitBlockFunctionBody(BlockFunctionBody node) {
+  void visitBlockFunctionBody(BlockFunctionBody node) {
     // 'async' | 'async' '*' | 'sync' '*':
     safelyRecordKeywordCompletion(node.keyword);
     return super.visitBlockFunctionBody(node);
   }
 
   @override
-  visitBooleanLiteral(BooleanLiteral node) {
+  void visitBooleanLiteral(BooleanLiteral node) {
     // 'false' | 'true'
     safelyRecordKeywordCompletion(node.literal);
     return super.visitBooleanLiteral(node);
   }
 
   @override
-  visitBreakStatement(BreakStatement node) {
+  void visitBreakStatement(BreakStatement node) {
     safelyRecordKeywordCompletion(node.breakKeyword);
     return super.visitBreakStatement(node);
   }
 
   @override
-  visitCatchClause(CatchClause node) {
+  void visitCatchClause(CatchClause node) {
     // Should we 'catch', it won't be suggested when it already exists as a
     // keyword in the file?
     safelyRecordKeywordCompletion(node.catchKeyword);
@@ -205,33 +206,33 @@
   }
 
   @override
-  visitClassDeclaration(ClassDeclaration node) {
+  void visitClassDeclaration(ClassDeclaration node) {
     safelyRecordKeywordCompletion(node.abstractKeyword);
     safelyRecordKeywordCompletion(node.classKeyword);
     return super.visitClassDeclaration(node);
   }
 
   @override
-  visitClassTypeAlias(ClassTypeAlias node) {
+  void visitClassTypeAlias(ClassTypeAlias node) {
     safelyRecordKeywordCompletion(node.abstractKeyword);
     safelyRecordKeywordCompletion(node.typedefKeyword);
     return super.visitClassTypeAlias(node);
   }
 
   @override
-  visitCompilationUnit(CompilationUnit node) {
+  void visitCompilationUnit(CompilationUnit node) {
     _enclosingCompilationUnit = node;
     return super.visitCompilationUnit(node);
   }
 
   @override
-  visitConfiguration(Configuration node) {
+  void visitConfiguration(Configuration node) {
     safelyRecordKeywordCompletion(node.ifKeyword);
     return super.visitConfiguration(node);
   }
 
   @override
-  visitConstructorDeclaration(ConstructorDeclaration node) {
+  void visitConstructorDeclaration(ConstructorDeclaration node) {
     safelyRecordKeywordCompletion(node.externalKeyword);
     safelyRecordKeywordCompletion(node.constKeyword);
     safelyRecordKeywordCompletion(node.factoryKeyword);
@@ -239,77 +240,77 @@
   }
 
   @override
-  visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
+  void visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
     safelyRecordKeywordCompletion(node.thisKeyword);
     return super.visitConstructorFieldInitializer(node);
   }
 
   @override
-  visitContinueStatement(ContinueStatement node) {
+  void visitContinueStatement(ContinueStatement node) {
     safelyRecordKeywordCompletion(node.continueKeyword);
     return super.visitContinueStatement(node);
   }
 
   @override
-  visitDeclaredIdentifier(DeclaredIdentifier node) {
+  void visitDeclaredIdentifier(DeclaredIdentifier node) {
     // 'final', 'const' or 'var'
     safelyRecordKeywordCompletion(node.keyword);
     return super.visitDeclaredIdentifier(node);
   }
 
   @override
-  visitDoStatement(DoStatement node) {
+  void visitDoStatement(DoStatement node) {
     safelyRecordKeywordCompletion(node.doKeyword);
     safelyRecordKeywordCompletion(node.whileKeyword);
     return super.visitDoStatement(node);
   }
 
   @override
-  visitEnumDeclaration(EnumDeclaration node) {
+  void visitEnumDeclaration(EnumDeclaration node) {
     safelyRecordKeywordCompletion(node.enumKeyword);
     return super.visitEnumDeclaration(node);
   }
 
   @override
-  visitExportDirective(ExportDirective node) {
+  void visitExportDirective(ExportDirective node) {
     safelyRecordKeywordCompletion(node.keyword);
     return super.visitExportDirective(node);
   }
 
   @override
-  visitExpressionFunctionBody(ExpressionFunctionBody node) {
+  void visitExpressionFunctionBody(ExpressionFunctionBody node) {
     safelyRecordKeywordCompletion(node.keyword);
     return super.visitExpressionFunctionBody(node);
   }
 
   @override
-  visitExtendsClause(ExtendsClause node) {
+  void visitExtendsClause(ExtendsClause node) {
     safelyRecordKeywordCompletion(node.extendsKeyword);
     return super.visitExtendsClause(node);
   }
 
   @override
-  visitExtensionDeclaration(ExtensionDeclaration node) {
+  void visitExtensionDeclaration(ExtensionDeclaration node) {
     safelyRecordKeywordCompletion(node.extensionKeyword);
     safelyRecordKeywordCompletion(node.onKeyword);
     return super.visitExtensionDeclaration(node);
   }
 
   @override
-  visitExtensionOverride(ExtensionOverride node) {
+  void visitExtensionOverride(ExtensionOverride node) {
     node.visitChildren(this);
     return null;
   }
 
   @override
-  visitFieldDeclaration(FieldDeclaration node) {
+  void visitFieldDeclaration(FieldDeclaration node) {
     safelyRecordKeywordCompletion(node.covariantKeyword);
     safelyRecordKeywordCompletion(node.staticKeyword);
     return super.visitFieldDeclaration(node);
   }
 
   @override
-  visitFieldFormalParameter(FieldFormalParameter node) {
+  void visitFieldFormalParameter(FieldFormalParameter node) {
     // 'final', 'const' or 'var'
     safelyRecordKeywordCompletion(node.keyword);
     safelyRecordKeywordCompletion(node.thisKeyword);
@@ -317,33 +318,33 @@
   }
 
   @override
-  visitForEachPartsWithDeclaration(ForEachPartsWithDeclaration node) {
+  void visitForEachPartsWithDeclaration(ForEachPartsWithDeclaration node) {
     safelyRecordKeywordCompletion(node.inKeyword);
     return super.visitForEachPartsWithDeclaration(node);
   }
 
   @override
-  visitForEachPartsWithIdentifier(ForEachPartsWithIdentifier node) {
+  void visitForEachPartsWithIdentifier(ForEachPartsWithIdentifier node) {
     safelyRecordKeywordCompletion(node.inKeyword);
     return super.visitForEachPartsWithIdentifier(node);
   }
 
   @override
-  visitForElement(ForElement node) {
+  void visitForElement(ForElement node) {
     safelyRecordKeywordCompletion(node.awaitKeyword);
     safelyRecordKeywordCompletion(node.forKeyword);
     return super.visitForElement(node);
   }
 
   @override
-  visitForStatement(ForStatement node) {
+  void visitForStatement(ForStatement node) {
     safelyRecordKeywordCompletion(node.awaitKeyword);
     safelyRecordKeywordCompletion(node.forKeyword);
     return super.visitForStatement(node);
   }
 
   @override
-  visitFunctionDeclaration(FunctionDeclaration node) {
+  void visitFunctionDeclaration(FunctionDeclaration node) {
     safelyRecordKeywordCompletion(node.externalKeyword);
     // 'get' or 'set':
     safelyRecordKeywordCompletion(node.propertyKeyword);
@@ -351,58 +352,58 @@
   }
 
   @override
-  visitFunctionTypeAlias(FunctionTypeAlias node) {
+  void visitFunctionTypeAlias(FunctionTypeAlias node) {
     safelyRecordKeywordCompletion(node.typedefKeyword);
     return super.visitFunctionTypeAlias(node);
   }
 
   @override
-  visitGenericFunctionType(GenericFunctionType node) {
+  void visitGenericFunctionType(GenericFunctionType node) {
     safelyRecordKeywordCompletion(node.functionKeyword);
     return super.visitGenericFunctionType(node);
   }
 
   @override
-  visitGenericTypeAlias(GenericTypeAlias node) {
+  void visitGenericTypeAlias(GenericTypeAlias node) {
     safelyRecordKeywordCompletion(node.typedefKeyword);
     return super.visitGenericTypeAlias(node);
   }
 
   @override
-  visitHideCombinator(HideCombinator node) {
+  void visitHideCombinator(HideCombinator node) {
     safelyRecordKeywordCompletion(node.keyword);
     return super.visitHideCombinator(node);
   }
 
   @override
-  visitIfElement(IfElement node) {
+  void visitIfElement(IfElement node) {
     safelyRecordKeywordCompletion(node.ifKeyword);
     safelyRecordKeywordCompletion(node.elseKeyword);
     return super.visitIfElement(node);
   }
 
   @override
-  visitIfStatement(IfStatement node) {
+  void visitIfStatement(IfStatement node) {
     safelyRecordKeywordCompletion(node.ifKeyword);
     safelyRecordKeywordCompletion(node.elseKeyword);
     return super.visitIfStatement(node);
   }
 
   @override
-  visitImplementsClause(ImplementsClause node) {
+  void visitImplementsClause(ImplementsClause node) {
     safelyRecordKeywordCompletion(node.implementsKeyword);
     return super.visitImplementsClause(node);
   }
 
   @override
-  visitImportDirective(ImportDirective node) {
+  void visitImportDirective(ImportDirective node) {
     safelyRecordKeywordCompletion(node.keyword);
     safelyRecordKeywordCompletion(node.asKeyword);
     return super.visitImportDirective(node);
   }
 
   @override
-  visitInstanceCreationExpression(InstanceCreationExpression node) {
+  void visitInstanceCreationExpression(InstanceCreationExpression node) {
     // Here we explicitly do not record 'new' as we don't suggest it in the
     // completion service.
     // https://dart-review.googlesource.com/c/sdk/+/131020
@@ -414,25 +415,25 @@
   }
 
   @override
-  visitIsExpression(IsExpression node) {
+  void visitIsExpression(IsExpression node) {
     safelyRecordKeywordCompletion(node.isOperator);
     return super.visitIsExpression(node);
   }
 
   @override
-  visitLibraryDirective(LibraryDirective node) {
+  void visitLibraryDirective(LibraryDirective node) {
     safelyRecordKeywordCompletion(node.libraryKeyword);
     return super.visitLibraryDirective(node);
   }
 
   @override
-  visitListLiteral(ListLiteral node) {
+  void visitListLiteral(ListLiteral node) {
     safelyRecordKeywordCompletion(node.constKeyword);
     return super.visitListLiteral(node);
   }
 
   @override
-  visitMethodDeclaration(MethodDeclaration node) {
+  void visitMethodDeclaration(MethodDeclaration node) {
     safelyRecordKeywordCompletion(node.externalKeyword);
     safelyRecordKeywordCompletion(node.modifierKeyword);
     safelyRecordKeywordCompletion(node.operatorKeyword);
@@ -441,80 +442,81 @@
   }
 
   @override
-  visitMixinDeclaration(MixinDeclaration node) {
+  void visitMixinDeclaration(MixinDeclaration node) {
     safelyRecordKeywordCompletion(node.mixinKeyword);
     return super.visitMixinDeclaration(node);
   }
 
   @override
-  visitNativeClause(NativeClause node) {
+  void visitNativeClause(NativeClause node) {
     safelyRecordKeywordCompletion(node.nativeKeyword);
     return super.visitNativeClause(node);
   }
 
   @override
-  visitNativeFunctionBody(NativeFunctionBody node) {
+  void visitNativeFunctionBody(NativeFunctionBody node) {
     safelyRecordKeywordCompletion(node.nativeKeyword);
     return super.visitNativeFunctionBody(node);
   }
 
   @override
-  visitNullLiteral(NullLiteral node) {
+  void visitNullLiteral(NullLiteral node) {
     safelyRecordKeywordCompletion(node.literal);
     return super.visitNullLiteral(node);
   }
 
   @override
-  visitOnClause(OnClause node) {
+  void visitOnClause(OnClause node) {
     safelyRecordKeywordCompletion(node.onKeyword);
     return super.visitOnClause(node);
   }
 
   @override
-  visitPartDirective(PartDirective node) {
+  void visitPartDirective(PartDirective node) {
     safelyRecordKeywordCompletion(node.partKeyword);
     return super.visitPartDirective(node);
   }
 
   @override
-  visitPartOfDirective(PartOfDirective node) {
+  void visitPartOfDirective(PartOfDirective node) {
     safelyRecordKeywordCompletion(node.partKeyword);
     safelyRecordKeywordCompletion(node.ofKeyword);
     return super.visitPartOfDirective(node);
   }
 
   @override
-  visitRedirectingConstructorInvocation(RedirectingConstructorInvocation node) {
+  void visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) {
     safelyRecordKeywordCompletion(node.thisKeyword);
     return super.visitRedirectingConstructorInvocation(node);
   }
 
   @override
-  visitRethrowExpression(RethrowExpression node) {
+  void visitRethrowExpression(RethrowExpression node) {
     safelyRecordKeywordCompletion(node.rethrowKeyword);
     return super.visitRethrowExpression(node);
   }
 
   @override
-  visitReturnStatement(ReturnStatement node) {
+  void visitReturnStatement(ReturnStatement node) {
     safelyRecordKeywordCompletion(node.returnKeyword);
     return super.visitReturnStatement(node);
   }
 
   @override
-  visitSetOrMapLiteral(SetOrMapLiteral node) {
+  void visitSetOrMapLiteral(SetOrMapLiteral node) {
     safelyRecordKeywordCompletion(node.constKeyword);
     return super.visitSetOrMapLiteral(node);
   }
 
   @override
-  visitShowCombinator(ShowCombinator node) {
+  void visitShowCombinator(ShowCombinator node) {
     safelyRecordKeywordCompletion(node.keyword);
     return super.visitShowCombinator(node);
   }
 
   @override
-  visitSimpleFormalParameter(SimpleFormalParameter node) {
+  void visitSimpleFormalParameter(SimpleFormalParameter node) {
     // 'final', 'const' or 'var'
     safelyRecordKeywordCompletion(node.keyword);
     safelyRecordKeywordCompletion(node.covariantKeyword);
@@ -522,7 +524,7 @@
   }
 
   @override
-  visitSimpleIdentifier(SimpleIdentifier node) {
+  void visitSimpleIdentifier(SimpleIdentifier node) {
     if (_doIncludeSimpleIdentifier(node)) {
       var elementKind;
       if (node.staticElement?.kind != null) {
@@ -541,6 +543,14 @@
         if (elementKind == protocol.ElementKind.PREFIX) {
           elementKind = protocol.ElementKind.LIBRARY;
         }
+
+        // For identifiers in a FieldFormalParameter, i.e. the 'foo' in some
+        // ClassName(this.foo), set the elementKind to FIELD which is what the
+        // completion engine does (elementKind before this if statement is a
+        // PARAMETER).
+        if (node.parent is FieldFormalParameter) {
+          elementKind = protocol.ElementKind.FIELD;
+        }
       }
       safelyRecordEntity(node, elementKind: elementKind);
     }
@@ -548,62 +558,62 @@
   }
 
   @override
-  visitSuperConstructorInvocation(SuperConstructorInvocation node) {
+  void visitSuperConstructorInvocation(SuperConstructorInvocation node) {
     safelyRecordKeywordCompletion(node.superKeyword);
     return super.visitSuperConstructorInvocation(node);
   }
 
   @override
-  visitSuperExpression(SuperExpression node) {
+  void visitSuperExpression(SuperExpression node) {
     safelyRecordKeywordCompletion(node.superKeyword);
     return super.visitSuperExpression(node);
   }
 
   @override
-  visitSwitchCase(SwitchCase node) {
+  void visitSwitchCase(SwitchCase node) {
     safelyRecordKeywordCompletion(node.keyword);
     return super.visitSwitchCase(node);
   }
 
   @override
-  visitSwitchDefault(SwitchDefault node) {
+  void visitSwitchDefault(SwitchDefault node) {
     safelyRecordKeywordCompletion(node.keyword);
     return super.visitSwitchDefault(node);
   }
 
   @override
-  visitSwitchStatement(SwitchStatement node) {
+  void visitSwitchStatement(SwitchStatement node) {
     safelyRecordKeywordCompletion(node.switchKeyword);
     return super.visitSwitchStatement(node);
   }
 
   @override
-  visitThisExpression(ThisExpression node) {
+  void visitThisExpression(ThisExpression node) {
     safelyRecordKeywordCompletion(node.thisKeyword);
     return super.visitThisExpression(node);
   }
 
   @override
-  visitThrowExpression(ThrowExpression node) {
+  void visitThrowExpression(ThrowExpression node) {
     safelyRecordKeywordCompletion(node.throwKeyword);
     return super.visitThrowExpression(node);
   }
 
   @override
-  visitTryStatement(TryStatement node) {
+  void visitTryStatement(TryStatement node) {
     safelyRecordKeywordCompletion(node.tryKeyword);
     safelyRecordKeywordCompletion(node.finallyKeyword);
     return super.visitTryStatement(node);
   }
 
   @override
-  visitTypeParameter(TypeParameter node) {
+  void visitTypeParameter(TypeParameter node) {
     safelyRecordKeywordCompletion(node.extendsKeyword);
     return super.visitTypeParameter(node);
   }
 
   @override
-  visitVariableDeclarationList(VariableDeclarationList node) {
+  void visitVariableDeclarationList(VariableDeclarationList node) {
     // 'final', 'const' or 'var'
     safelyRecordKeywordCompletion(node.keyword);
     safelyRecordKeywordCompletion(node.lateKeyword);
@@ -611,19 +621,19 @@
   }
 
   @override
-  visitWhileStatement(WhileStatement node) {
+  void visitWhileStatement(WhileStatement node) {
     safelyRecordKeywordCompletion(node.whileKeyword);
     return super.visitWhileStatement(node);
   }
 
   @override
-  visitWithClause(WithClause node) {
+  void visitWithClause(WithClause node) {
     safelyRecordKeywordCompletion(node.withKeyword);
     return super.visitWithClause(node);
   }
 
   @override
-  visitYieldStatement(YieldStatement node) {
+  void visitYieldStatement(YieldStatement node) {
     safelyRecordKeywordCompletion(node.yieldKeyword);
     return super.visitYieldStatement(node);
   }
@@ -639,6 +649,28 @@
     if (node.thisOrAncestorOfType<CommentReference>() != null) {
       return _doExpectCommentRefs;
     }
+
+    // Ignore the SimpleIdentifiers that make up library directives.
+    if (node.thisOrAncestorOfType<LibraryDirective>() != null) {
+      return false;
+    }
+
+    // TODO (jwren) If there is a mode of completing at a token location where
+    //  the token is removed before the completion query happens, then this
+    //  should be disabled in such a case:
+    // Named arguments, i.e. the 'foo' in 'method_call(foo: 1)' should not be
+    // included, by design, the completion engine won't suggest named arguments
+    // already it the source.
+    if (node.staticElement?.kind == element.ElementKind.PARAMETER &&
+        node.parent is Label &&
+        node.thisOrAncestorOfType<ArgumentList>() != null) {
+      return false;
+    }
+
+    // If the type of the SimpleIdentifier is dynamic, don't include.
+    if (node.staticType != null && node.staticType.isDynamic) {
+      return false;
+    }
     return true;
   }
 }
diff --git a/pkg/analysis_server/tool/lsp_spec/codegen_dart.dart b/pkg/analysis_server/tool/lsp_spec/codegen_dart.dart
index 11c69dd..a830ba6 100644
--- a/pkg/analysis_server/tool/lsp_spec/codegen_dart.dart
+++ b/pkg/analysis_server/tool/lsp_spec/codegen_dart.dart
@@ -9,9 +9,9 @@
 
 final formatter = DartFormatter();
 Map<String, Interface> _interfaces = {};
-Map<String, List<String>> _subtypes = {};
-// TODO(dantup): Rename namespaces -> enums since they're always that now.
 Map<String, Namespace> _namespaces = {};
+// TODO(dantup): Rename namespaces -> enums since they're always that now.
+Map<String, List<String>> _subtypes = {};
 Map<String, TypeAlias> _typeAliases = {};
 
 /// Whether our enum class allows any value (eg. should always return true
@@ -34,6 +34,13 @@
       name != 'ResourceOperationKind';
 }
 
+String generateDartForTypes(List<AstNode> types) {
+  final buffer = IndentableStringBuffer();
+  _getSorted(types).forEach((t) => _writeType(buffer, t));
+  final formattedCode = _formatCode(buffer.toString());
+  return formattedCode.trim() + '\n'; // Ensure a single trailing newline.
+}
+
 void recordTypes(List<AstNode> types) {
   types
       .whereType<TypeAlias>()
@@ -52,13 +59,6 @@
       .forEach((namespace) => _namespaces[namespace.name] = namespace);
 }
 
-String generateDartForTypes(List<AstNode> types) {
-  final buffer = IndentableStringBuffer();
-  _getSorted(types).forEach((t) => _writeType(buffer, t));
-  final formattedCode = _formatCode(buffer.toString());
-  return formattedCode.trim() + '\n'; // Ensure a single trailing newline.
-}
-
 TypeBase resolveTypeAlias(TypeBase type, {resolveEnumClasses = false}) {
   if (type is Type && _typeAliases.containsKey(type.name)) {
     final alias = _typeAliases[type.name];
@@ -179,7 +179,7 @@
       buffer
         ..writeIndentedln("if (!obj.containsKey('${field.name}')) {")
         ..indent()
-        ..writeIndentedln('reporter.reportError("must not be undefined");')
+        ..writeIndentedln("reporter.reportError('must not be undefined');")
         ..writeIndentedln('return false;')
         ..outdent()
         ..writeIndentedln('}');
@@ -188,7 +188,7 @@
       buffer
         ..writeIndentedln("if (obj['${field.name}'] == null) {")
         ..indent()
-        ..writeIndentedln('reporter.reportError("must not be null");')
+        ..writeIndentedln("reporter.reportError('must not be null');")
         ..writeIndentedln('return false;')
         ..outdent()
         ..writeIndentedln('}');
@@ -204,7 +204,7 @@
       ..write(')) {')
       ..indent()
       ..writeIndentedln(
-          'reporter.reportError("must be of type ${field.type.dartTypeWithTypeArgs}");')
+          "reporter.reportError('must be of type ${field.type.dartTypeWithTypeArgs}');")
       ..writeIndentedln('return false;')
       ..outdent()
       ..writeIndentedln('}')
@@ -221,7 +221,7 @@
     ..writeIndentedln('} else {')
     ..indent()
     ..writeIndentedln(
-        'reporter.reportError("must be of type ${interface.nameWithTypeArgs}");')
+        "reporter.reportError('must be of type ${interface.nameWithTypeArgs}');")
     ..writeIndentedln('return false;')
     ..outdent()
     ..writeIndentedln('}')
@@ -266,15 +266,6 @@
   }
 }
 
-void _writeJsonHandler(IndentableStringBuffer buffer, Interface interface) {
-  buffer
-    ..writeIndented('static const jsonHandler = ')
-    ..write('LspJsonHandler(')
-    ..write('${interface.name}.canParse, ${interface.name}.fromJson')
-    ..writeln(');')
-    ..writeln();
-}
-
 void _writeDocCommentsAndAnnotations(
     IndentableStringBuffer buffer, AstNode node) {
   var comment = node.commentText?.trim();
@@ -343,7 +334,7 @@
     ..writeln()
     ..writeIndentedln('@override String toString() => _value.toString();')
     ..writeln()
-    ..writeIndentedln('@override get hashCode => _value.hashCode;')
+    ..writeIndentedln('@override int get hashCode => _value.hashCode;')
     ..writeln()
     ..writeIndentedln(
         'bool operator ==(Object o) => o is ${namespace.name} && o._value == _value;')
@@ -558,6 +549,15 @@
     ..writeln();
 }
 
+void _writeJsonHandler(IndentableStringBuffer buffer, Interface interface) {
+  buffer
+    ..writeIndented('static const jsonHandler = ')
+    ..write('LspJsonHandler(')
+    ..write('${interface.name}.canParse, ${interface.name}.fromJson')
+    ..writeln(');')
+    ..writeln();
+}
+
 void _writeJsonMapAssignment(
     IndentableStringBuffer buffer, Field field, String mapName) {
   // If we are allowed to be undefined, we'll only add the value if set.
@@ -593,29 +593,6 @@
   _getSorted(members).forEach((m) => _writeMember(buffer, m));
 }
 
-void _writeToJsonMethod(IndentableStringBuffer buffer, Interface interface) {
-  // It's important the name we use for the map here isn't in use in the object
-  // already. 'result' was, so we prefix it with some underscores.
-  buffer
-    ..writeIndentedln('Map<String, dynamic> toJson() {')
-    ..indent()
-    ..writeIndentedln('Map<String, dynamic> __result = {};');
-  // ResponseMessage must confirm to JSON-RPC which says only one of
-  // result/error can be included. Since this isn't encoded in the types we
-  // need to special-case it's toJson generation.
-  if (interface.name == 'ResponseMessage') {
-    _writeToJsonFieldsForResponseMessage(buffer, interface);
-  } else {
-    for (var field in _getAllFields(interface)) {
-      _writeJsonMapAssignment(buffer, field, '__result');
-    }
-  }
-  buffer
-    ..writeIndentedln('return __result;')
-    ..outdent()
-    ..writeIndentedln('}');
-}
-
 void _writeToJsonFieldsForResponseMessage(
     IndentableStringBuffer buffer, Interface interface) {
   const mapName = '__result';
@@ -645,6 +622,29 @@
     ..writeIndentedln('}');
 }
 
+void _writeToJsonMethod(IndentableStringBuffer buffer, Interface interface) {
+  // It's important the name we use for the map here isn't in use in the object
+  // already. 'result' was, so we prefix it with some underscores.
+  buffer
+    ..writeIndentedln('Map<String, dynamic> toJson() {')
+    ..indent()
+    ..writeIndentedln('Map<String, dynamic> __result = {};');
+  // ResponseMessage must confirm to JSON-RPC which says only one of
+  // result/error can be included. Since this isn't encoded in the types we
+  // need to special-case it's toJson generation.
+  if (interface.name == 'ResponseMessage') {
+    _writeToJsonFieldsForResponseMessage(buffer, interface);
+  } else {
+    for (var field in _getAllFields(interface)) {
+      _writeJsonMapAssignment(buffer, field, '__result');
+    }
+  }
+  buffer
+    ..writeIndentedln('return __result;')
+    ..outdent()
+    ..writeIndentedln('}');
+}
+
 void _writeToString(IndentableStringBuffer buffer, Interface interface) {
   buffer
     ..writeIndentedln('@override')
diff --git a/pkg/analysis_server/tool/lsp_spec/generate_all.dart b/pkg/analysis_server/tool/lsp_spec/generate_all.dart
index 2155204..9f90859 100644
--- a/pkg/analysis_server/tool/lsp_spec/generate_all.dart
+++ b/pkg/analysis_server/tool/lsp_spec/generate_all.dart
@@ -15,7 +15,7 @@
 import 'typescript.dart';
 import 'typescript_parser.dart';
 
-main(List<String> arguments) async {
+Future<void> main(List<String> arguments) async {
   final args = argParser.parse(arguments);
   if (args[argHelp]) {
     print(argParser.usage);
@@ -182,11 +182,11 @@
 ''';
 
 List<AstNode> getCustomClasses() {
-  interface(String name, List<Member> fields) {
+  Interface interface(String name, List<Member> fields) {
     return Interface(null, Token.identifier(name), [], [], fields);
   }
 
-  field(String name,
+  Field field(String name,
       {String type, array = false, canBeNull = false, canBeUndefined = false}) {
     var fieldType =
         array ? ArrayType(Type.identifier(type)) : Type.identifier(type);
diff --git a/pkg/analysis_server/tool/migration_runner.dart b/pkg/analysis_server/tool/migration_runner.dart
index 581f406..ce974de 100644
--- a/pkg/analysis_server/tool/migration_runner.dart
+++ b/pkg/analysis_server/tool/migration_runner.dart
@@ -34,7 +34,7 @@
 import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 
-main(List<String> args) async {
+Future<void> main(List<String> args) async {
   if (args.length != 2) {
     throw StateError(
         'Exactly two arguments are required: the path to a JSON configuration '
diff --git a/pkg/analysis_server/tool/nnbd_migration/generate_resources.dart b/pkg/analysis_server/tool/nnbd_migration/generate_resources.dart
new file mode 100644
index 0000000..7e8fc56
--- /dev/null
+++ b/pkg/analysis_server/tool/nnbd_migration/generate_resources.dart
@@ -0,0 +1,105 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// This script generates the
+// lib/src/edit/nnbd_migration/resources/resources.g.dart file from the contents
+// of the lib/src/edit/nnbd_migration/resources directory.
+
+import 'dart:convert';
+import 'dart:io';
+import 'dart:math' as math;
+
+import 'package:path/path.dart' as path;
+
+void main(List<String> args) {
+  if (FileSystemEntity.isFileSync(
+      path.join('tool', 'nnbd_migration', 'generate_resources.dart'))) {
+    // We're running from the project root - cd up two directories.
+    Directory.current = Directory.current.parent.parent;
+  } else if (!FileSystemEntity.isDirectorySync(
+      path.join('pkg', 'analysis_server'))) {
+    fail('Please run this tool from the root of the sdk repo.');
+  }
+
+  Directory resourceDir = Directory(path.join('pkg', 'analysis_server', 'lib',
+      'src', 'edit', 'nnbd_migration', 'resources'));
+
+  String content = generateResourceFile(resourceDir.listSync().where((entity) {
+    String name = path.basename(entity.path);
+    return entity is File && (name.endsWith('.js') || name.endsWith('.css'));
+  }).cast<File>());
+
+  // write the content
+  File resourcesFile = File(path.join('pkg', 'analysis_server', 'lib', 'src',
+      'edit', 'nnbd_migration', 'resources', 'resources.g.dart'));
+  resourcesFile.writeAsStringSync(content);
+}
+
+String generateResourceFile(Iterable<File> resources) {
+  String filePath = path.relative(Platform.script.toFilePath());
+  StringBuffer buf = StringBuffer('''
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// This file is generated; don't edit it directly.
+//
+// See $filePath for how
+// to edit the source content and for re-generation instructions.
+
+import 'dart:convert' as convert;
+''');
+
+  for (File resource in resources) {
+    String name = path.basename(resource.path).replaceAll('.', '_');
+    buf.writeln();
+    buf.writeln('String get $name {');
+    buf.writeln('  return _$name ??= _decode(_${name}_base64);');
+    buf.writeln('}');
+  }
+
+  buf.writeln(r'''
+
+String _decode(String data) {
+  data = data.replaceAll('\n', '').trim();
+  return String.fromCharCodes(convert.base64Decode(data));
+}''');
+
+  for (File resource in resources) {
+    String name = path.basename(resource.path).replaceAll('.', '_');
+    String source = resource.readAsStringSync();
+
+    String delimiter = "'''";
+
+    buf.writeln();
+    buf.writeln('String _$name;');
+    buf.writeln('String _${name}_base64 = $delimiter');
+    buf.writeln(base64Encode(source.codeUnits));
+    buf.writeln('$delimiter;');
+  }
+
+  return buf.toString();
+}
+
+String base64Encode(List<int> bytes) {
+  String encoded = base64.encode(bytes);
+
+  // Logic to cut lines into 80-character chunks
+  // – makes for prettier source code
+  var lines = <String>[];
+  var index = 0;
+
+  while (index < encoded.length) {
+    var line = encoded.substring(index, math.min(index + 80, encoded.length));
+    lines.add(line);
+    index += line.length;
+  }
+
+  return lines.join('\n');
+}
+
+void fail(String message) {
+  stderr.writeln(message);
+  exit(1);
+}
diff --git a/pkg/analysis_server/tool/spec/api.dart b/pkg/analysis_server/tool/spec/api.dart
index c21cb15..bbe6bd3 100644
--- a/pkg/analysis_server/tool/spec/api.dart
+++ b/pkg/analysis_server/tool/spec/api.dart
@@ -56,7 +56,7 @@
   /**
    * Dispatch the given [type] to the visitor.
    */
-  T visitTypeDecl(TypeDecl type) => type.accept(this) as T;
+  T visitTypeDecl(TypeDecl type) => type.accept(this);
   T visitTypeEnum(TypeEnum typeEnum);
   T visitTypeList(TypeList typeList);
   T visitTypeMap(TypeMap typeMap);
@@ -347,7 +347,7 @@
   TypeDecl(dom.Element html, bool experimental, bool deprecated)
       : super(html, experimental, deprecated);
 
-  accept(ApiVisitor visitor);
+  T accept<T>(ApiVisitor<T> visitor);
 }
 
 /**
@@ -375,7 +375,7 @@
       : super(html, experimental, deprecated);
 
   @override
-  accept(ApiVisitor visitor) => visitor.visitTypeEnum(this);
+  T accept<T>(ApiVisitor<T> visitor) => visitor.visitTypeEnum(this);
 }
 
 /**
@@ -399,7 +399,7 @@
       : super(html, experimental, false);
 
   @override
-  accept(ApiVisitor visitor) => visitor.visitTypeList(this);
+  T accept<T>(ApiVisitor<T> visitor) => visitor.visitTypeList(this);
 }
 
 /**
@@ -422,7 +422,7 @@
       : super(html, experimental, false);
 
   @override
-  accept(ApiVisitor visitor) => visitor.visitTypeMap(this);
+  T accept<T>(ApiVisitor<T> visitor) => visitor.visitTypeMap(this);
 }
 
 /**
@@ -436,7 +436,7 @@
       : super(html, experimental, deprecated);
 
   @override
-  accept(ApiVisitor visitor) => visitor.visitTypeObject(this);
+  T accept<T>(ApiVisitor<T> visitor) => visitor.visitTypeObject(this);
 
   /**
    * Return the field with the given [name], or null if there is no such field.
@@ -484,7 +484,7 @@
   }
 
   @override
-  accept(ApiVisitor visitor) => visitor.visitTypeReference(this);
+  T accept<T>(ApiVisitor<T> visitor) => visitor.visitTypeReference(this);
 }
 
 /**
@@ -523,5 +523,5 @@
       : super(html, experimental, false);
 
   @override
-  accept(ApiVisitor visitor) => visitor.visitTypeUnion(this);
+  T accept<T>(ApiVisitor<T> visitor) => visitor.visitTypeUnion(this);
 }
diff --git a/pkg/analysis_server/tool/spec/check_all_test.dart b/pkg/analysis_server/tool/spec/check_all_test.dart
index e37d58f..c390d6f 100644
--- a/pkg/analysis_server/tool/spec/check_all_test.dart
+++ b/pkg/analysis_server/tool/spec/check_all_test.dart
@@ -13,7 +13,7 @@
  * Check that all targets have been code generated.  If they haven't tell the
  * user to run generate_all.dart.
  */
-main() async {
+void main() async {
   String script = Platform.script.toFilePath(windows: Platform.isWindows);
   List<String> components = split(script);
   int index = components.indexOf('analysis_server');
diff --git a/pkg/analysis_server/tool/spec/codegen_dart_notification_handler.dart b/pkg/analysis_server/tool/spec/codegen_dart_notification_handler.dart
index e8892a8..1d152ae 100644
--- a/pkg/analysis_server/tool/spec/codegen_dart_notification_handler.dart
+++ b/pkg/analysis_server/tool/spec/codegen_dart_notification_handler.dart
@@ -20,7 +20,7 @@
   });
 }
 
-_capitalize(String name) =>
+String _capitalize(String name) =>
     '${name.substring(0, 1).toUpperCase()}${name.substring(1)}';
 
 List<String> _generateDartDoc(Element html) => html.children
@@ -110,7 +110,7 @@
   }
 
   @override
-  visitApi() {
+  void visitApi() {
     outputHeader(year: '2018');
     writeln();
     emitImports();
diff --git a/pkg/analysis_server/tool/spec/codegen_dart_protocol.dart b/pkg/analysis_server/tool/spec/codegen_dart_protocol.dart
index bfe7954..e5a3080 100644
--- a/pkg/analysis_server/tool/spec/codegen_dart_protocol.dart
+++ b/pkg/analysis_server/tool/spec/codegen_dart_protocol.dart
@@ -1197,7 +1197,7 @@
   }
 
   @override
-  visitApi() {
+  void visitApi() {
     outputHeader(year: '2017');
     writeln();
     emitImports();
diff --git a/pkg/analysis_server/tool/spec/codegen_inttest_methods.dart b/pkg/analysis_server/tool/spec/codegen_inttest_methods.dart
index 1e1088c..f0aecd6 100644
--- a/pkg/analysis_server/tool/spec/codegen_inttest_methods.dart
+++ b/pkg/analysis_server/tool/spec/codegen_inttest_methods.dart
@@ -97,7 +97,7 @@
   }
 
   @override
-  visitApi() {
+  void visitApi() {
     outputHeader(year: '2017');
     writeln();
     writeln('/// Convenience methods for running integration tests.');
@@ -157,7 +157,7 @@
   }
 
   @override
-  visitNotification(Notification notification) {
+  void visitNotification(Notification notification) {
     String streamName =
         camelJoin(['on', notification.domainName, notification.event]);
     String className = camelJoin(
@@ -197,7 +197,7 @@
   }
 
   @override
-  visitRequest(Request request) {
+  void visitRequest(Request request) {
     String methodName = camelJoin(['send', request.domainName, request.method]);
     List<String> args = <String>[];
     List<String> optionalArgs = <String>[];
diff --git a/pkg/analysis_server/tool/spec/codegen_matchers.dart b/pkg/analysis_server/tool/spec/codegen_matchers.dart
index 73cb89b..49805e1 100644
--- a/pkg/analysis_server/tool/spec/codegen_matchers.dart
+++ b/pkg/analysis_server/tool/spec/codegen_matchers.dart
@@ -96,7 +96,7 @@
   }
 
   @override
-  visitApi() {
+  void visitApi() {
     outputHeader(year: '2017');
     writeln();
     writeln('/// Matchers for data types defined in the analysis server API.');
@@ -113,7 +113,7 @@
   }
 
   @override
-  visitTypeEnum(TypeEnum typeEnum) {
+  void visitTypeEnum(TypeEnum typeEnum) {
     writeln("MatchesEnum('$context', [");
     indent(() {
       bool commaNeeded = false;
@@ -130,14 +130,14 @@
   }
 
   @override
-  visitTypeList(TypeList typeList) {
+  void visitTypeList(TypeList typeList) {
     write('isListOf(');
     visitTypeDecl(typeList.itemType);
     write(')');
   }
 
   @override
-  visitTypeMap(TypeMap typeMap) {
+  void visitTypeMap(TypeMap typeMap) {
     write('isMapOf(');
     visitTypeDecl(typeMap.keyType);
     write(', ');
diff --git a/pkg/analysis_server/tool/spec/codegen_protocol_constants.dart b/pkg/analysis_server/tool/spec/codegen_protocol_constants.dart
index 7d4ef33..efa6638 100644
--- a/pkg/analysis_server/tool/spec/codegen_protocol_constants.dart
+++ b/pkg/analysis_server/tool/spec/codegen_protocol_constants.dart
@@ -96,7 +96,7 @@
   }
 
   @override
-  visitApi() {
+  void visitApi() {
     outputHeader(year: '2017');
     writeln();
     generateConstants();
diff --git a/pkg/analysis_server/tool/spec/generate_all.dart b/pkg/analysis_server/tool/spec/generate_all.dart
index 000b487..5066956 100644
--- a/pkg/analysis_server/tool/spec/generate_all.dart
+++ b/pkg/analysis_server/tool/spec/generate_all.dart
@@ -20,7 +20,7 @@
 /**
  * Generate all targets.
  */
-main() async {
+void main() async {
   String script = Platform.script.toFilePath(windows: Platform.isWindows);
   String pkgPath = normalize(join(dirname(script), '..', '..'));
   await GeneratedContent.generateAll(pkgPath, allTargets);
diff --git a/pkg/analysis_server/tool/spec/implied_types.dart b/pkg/analysis_server/tool/spec/implied_types.dart
index 068590f..22380a9 100644
--- a/pkg/analysis_server/tool/spec/implied_types.dart
+++ b/pkg/analysis_server/tool/spec/implied_types.dart
@@ -59,13 +59,13 @@
   }
 
   @override
-  visitNotification(Notification notification) {
+  void visitNotification(Notification notification) {
     storeType(notification.longEvent, 'params', notification.params,
         'notificationParams', notification);
   }
 
   @override
-  visitRefactoring(Refactoring refactoring) {
+  void visitRefactoring(Refactoring refactoring) {
     String camelKind = camelJoin(refactoring.kind.toLowerCase().split('_'));
     storeType(camelKind, 'feedback', refactoring.feedback,
         'refactoringFeedback', refactoring);
@@ -74,7 +74,7 @@
   }
 
   @override
-  visitRequest(Request request) {
+  void visitRequest(Request request) {
     storeType(
         request.longMethod, 'params', request.params, 'requestParams', request);
     storeType(
@@ -82,7 +82,7 @@
   }
 
   @override
-  visitTypeDefinition(TypeDefinition typeDefinition) {
+  void visitTypeDefinition(TypeDefinition typeDefinition) {
     storeType(typeDefinition.name, null, typeDefinition.type, 'typeDefinition',
         typeDefinition);
   }
diff --git a/pkg/analysis_server/tool/spec/to_html.dart b/pkg/analysis_server/tool/spec/to_html.dart
index 95cf23a..6da5abf 100644
--- a/pkg/analysis_server/tool/spec/to_html.dart
+++ b/pkg/analysis_server/tool/spec/to_html.dart
@@ -559,7 +559,7 @@
   }
 
   @override
-  visitRefactoring(Refactoring refactoring) {
+  void visitRefactoring(Refactoring refactoring) {
     dt('refactoring', () {
       write(refactoring.kind);
     });
diff --git a/pkg/analyzer/lib/error/error.dart b/pkg/analyzer/lib/error/error.dart
index 1ab825e..89511e8 100644
--- a/pkg/analyzer/lib/error/error.dart
+++ b/pkg/analyzer/lib/error/error.dart
@@ -642,6 +642,7 @@
   ParserErrorCode.TYPE_ARGUMENTS_ON_TYPE_VARIABLE,
   ParserErrorCode.TYPE_BEFORE_FACTORY,
   ParserErrorCode.TYPE_PARAMETER_ON_CONSTRUCTOR,
+  ParserErrorCode.TYPE_PARAMETER_ON_OPERATOR,
   ParserErrorCode.UNEXPECTED_TERMINATOR_FOR_PARAMETER_GROUP,
   ParserErrorCode.UNEXPECTED_TOKEN,
   ParserErrorCode.VAR_AND_TYPE,
@@ -731,6 +732,8 @@
   StaticWarningCode.FINAL_NOT_INITIALIZED_CONSTRUCTOR_1,
   StaticWarningCode.FINAL_NOT_INITIALIZED_CONSTRUCTOR_2,
   StaticWarningCode.FINAL_NOT_INITIALIZED_CONSTRUCTOR_3_PLUS,
+  StaticWarningCode.GETTER_NOT_ASSIGNABLE_SETTER_TYPES,
+  StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES,
   StaticWarningCode.IMPORT_DUPLICATED_LIBRARY_NAMED,
   // ignore: deprecated_member_use_from_same_package
   StaticWarningCode.IMPORT_OF_NON_LIBRARY,
@@ -741,7 +744,6 @@
   StaticWarningCode.LIST_ELEMENT_TYPE_NOT_ASSIGNABLE,
   StaticWarningCode.MAP_KEY_TYPE_NOT_ASSIGNABLE,
   StaticWarningCode.MAP_VALUE_TYPE_NOT_ASSIGNABLE,
-  StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES,
   StaticWarningCode.MISSING_ENUM_CONSTANT_IN_SWITCH,
   // ignore: deprecated_member_use_from_same_package
   StaticWarningCode.MIXED_RETURN_TYPES,
diff --git a/pkg/analyzer/lib/src/dart/analysis/driver.dart b/pkg/analyzer/lib/src/dart/analysis/driver.dart
index ceabe27..d94e3f8 100644
--- a/pkg/analyzer/lib/src/dart/analysis/driver.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/driver.dart
@@ -89,7 +89,7 @@
 /// TODO(scheglov) Clean up the list of implicitly analyzed files.
 class AnalysisDriver implements AnalysisDriverGeneric {
   /// The version of data format, should be incremented on every format change.
-  static const int DATA_VERSION = 95;
+  static const int DATA_VERSION = 96;
 
   /// The length of the list returned by [_computeDeclaredVariablesSignature].
   static const int _declaredVariablesSignatureLength = 4;
diff --git a/pkg/analyzer/lib/src/dart/analysis/search.dart b/pkg/analyzer/lib/src/dart/analysis/search.dart
index 9bdc1cc..09d57b4 100644
--- a/pkg/analyzer/lib/src/dart/analysis/search.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/search.dart
@@ -704,18 +704,21 @@
       if (node.staticElement == importElement.prefix) {
         AstNode parent = node.parent;
         if (parent is PrefixedIdentifier && parent.prefix == node) {
-          if (importedElements.contains(parent.staticElement)) {
+          var element = parent.staticElement?.declaration;
+          if (importedElements.contains(element)) {
             _addResultForPrefix(node, parent.identifier);
           }
         }
         if (parent is MethodInvocation && parent.target == node) {
-          if (importedElements.contains(parent.methodName.staticElement)) {
+          var element = parent.methodName.staticElement?.declaration;
+          if (importedElements.contains(element)) {
             _addResultForPrefix(node, parent.methodName);
           }
         }
       }
     } else {
-      if (importedElements.contains(node.staticElement)) {
+      var element = node.staticElement?.declaration;
+      if (importedElements.contains(element)) {
         _addResult(node.offset, 0);
       }
     }
diff --git a/pkg/analyzer/lib/src/dart/ast/ast.dart b/pkg/analyzer/lib/src/dart/ast/ast.dart
index d0de664..401e022 100644
--- a/pkg/analyzer/lib/src/dart/ast/ast.dart
+++ b/pkg/analyzer/lib/src/dart/ast/ast.dart
@@ -6960,6 +6960,7 @@
 ///        ([Expression] '.')? [SimpleIdentifier] [TypeArgumentList]?
 ///        [ArgumentList]
 class MethodInvocationImpl extends InvocationExpressionImpl
+    with NullShortableExpressionImpl
     implements MethodInvocation {
   /// The expression producing the object on which the method is defined, or
   /// `null` if there is no target (that is, the target is implicitly `this`).
@@ -7078,6 +7079,9 @@
   }
 
   @override
+  AstNode get _nullShortingExtensionCandidate => parent;
+
+  @override
   E accept<E>(AstVisitor<E> visitor) => visitor.visitMethodInvocation(this);
 
   @override
@@ -7087,6 +7091,9 @@
     _typeArguments?.accept(visitor);
     _argumentList?.accept(visitor);
   }
+
+  @override
+  bool _extendsNullShorting(Expression child) => identical(child, _target);
 }
 
 /// The declaration of a mixin.
diff --git a/pkg/analyzer/lib/src/dart/element/runtime_type_equality.dart b/pkg/analyzer/lib/src/dart/element/runtime_type_equality.dart
new file mode 100644
index 0000000..e49bcc5
--- /dev/null
+++ b/pkg/analyzer/lib/src/dart/element/runtime_type_equality.dart
@@ -0,0 +1,201 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/nullability_suffix.dart';
+import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/src/dart/element/element.dart';
+import 'package:analyzer/src/dart/element/type.dart';
+import 'package:analyzer/src/dart/element/type_algebra.dart';
+import 'package:analyzer/src/dart/element/type_visitor.dart';
+import 'package:analyzer/src/generated/type_system.dart';
+
+class RuntimeTypeEqualityHelper {
+  final TypeSystemImpl _typeSystem;
+
+  RuntimeTypeEqualityHelper(TypeSystemImpl typeSystem)
+      : _typeSystem = typeSystem;
+
+  /// Return `true` if runtime types [T1] and [T2] are equal.
+  ///
+  /// nnbd/feature-specification.md#runtime-type-equality-operator
+  bool equal(DartType T1, DartType T2) {
+    var N1 = _typeSystem.normalize(T1);
+    var N2 = _typeSystem.normalize(T2);
+    return const RuntimeTypeEqualityVisitor().visit(N1, N2);
+  }
+}
+
+class RuntimeTypeEqualityVisitor extends DartTypeVisitor1<bool, DartType> {
+  const RuntimeTypeEqualityVisitor();
+
+  @override
+  bool defaultDartType(DartType T1, DartType T2) {
+    throw UnimplementedError('(${T1.runtimeType}) $T1');
+  }
+
+  bool visit(DartType T1, DartType T2) {
+    return DartTypeVisitor1.visit(T1, this, T2);
+  }
+
+  @override
+  bool visitDynamicType(DynamicTypeImpl T1, DartType T2) {
+    return identical(T1, T2);
+  }
+
+  @override
+  bool visitFunctionType(FunctionType T1, DartType T2) {
+    if (T2 is FunctionType) {
+      var typeParameters = _typeParameters(T1.typeFormals, T2.typeFormals);
+      if (typeParameters == null) {
+        return false;
+      }
+
+      bool equal(DartType T1, DartType T2) {
+        T1 = typeParameters.T1_substitution.substituteType(T1);
+        T2 = typeParameters.T2_substitution.substituteType(T2);
+        return visit(T1, T2);
+      }
+
+      if (!equal(T1.returnType, T2.returnType)) {
+        return false;
+      }
+
+      var T1_parameters = T1.parameters;
+      var T2_parameters = T2.parameters;
+      if (T1_parameters.length != T2_parameters.length) {
+        return false;
+      }
+
+      for (var i = 0; i < T1_parameters.length; i++) {
+        var T1_parameter = T1_parameters[i];
+        var T2_parameter = T2_parameters[i];
+
+        // ignore: deprecated_member_use_from_same_package
+        if (T1_parameter.parameterKind != T2_parameter.parameterKind) {
+          return false;
+        }
+
+        if (T1_parameter.isNamed) {
+          if (T1_parameter.name != T2_parameter.name) {
+            return false;
+          }
+        }
+
+        if (!equal(T1_parameter.type, T2_parameter.type)) {
+          return false;
+        }
+      }
+
+      return true;
+    }
+    return false;
+  }
+
+  @override
+  bool visitInterfaceType(InterfaceType T1, DartType T2) {
+    if (T2 is InterfaceType &&
+        T1.element == T2.element &&
+        _compatibleNullability(T1, T2)) {
+      var T1_typeArguments = T1.typeArguments;
+      var T2_typeArguments = T2.typeArguments;
+      if (T1_typeArguments.length == T2_typeArguments.length) {
+        for (var i = 0; i < T1_typeArguments.length; i++) {
+          var T1_typeArgument = T1_typeArguments[i];
+          var T2_typeArgument = T2_typeArguments[i];
+          if (!visit(T1_typeArgument, T2_typeArgument)) {
+            return false;
+          }
+        }
+        return true;
+      }
+    }
+    return false;
+  }
+
+  @override
+  bool visitNeverType(NeverTypeImpl T1, DartType T2) {
+    // Note, that all types are normalized before this visitor.
+    // So, `Never?` never happens, it is already `Null`.
+    assert(T1.nullabilitySuffix != NullabilitySuffix.question);
+    return T2 is NeverTypeImpl && _compatibleNullability(T1, T2);
+  }
+
+  @override
+  bool visitTypeParameterType(TypeParameterType T1, DartType T2) {
+    return T2 is TypeParameterType &&
+        _compatibleNullability(T1, T2) &&
+        T1.element == T2.element;
+  }
+
+  @override
+  bool visitVoidType(VoidType T1, DartType T2) {
+    return identical(T1, T2);
+  }
+
+  bool _compatibleNullability(DartType T1, DartType T2) {
+    var T1_nullability = T1.nullabilitySuffix;
+    var T2_nullability = T2.nullabilitySuffix;
+    return T1_nullability == T2_nullability ||
+        T1_nullability == NullabilitySuffix.star &&
+            T2_nullability == NullabilitySuffix.none ||
+        T2_nullability == NullabilitySuffix.star &&
+            T1_nullability == NullabilitySuffix.none;
+  }
+
+  /// Determines if the two lists of type parameters are equal.  If they are,
+  /// returns a [_TypeParametersResult] indicating the substitutions necessary
+  /// to demonstrate their equality.  If they aren't, returns `null`.
+  _TypeParametersResult _typeParameters(
+    List<TypeParameterElement> T1_parameters,
+    List<TypeParameterElement> T2_parameters,
+  ) {
+    if (T1_parameters.length != T2_parameters.length) {
+      return null;
+    }
+
+    var newParameters = <TypeParameterElementImpl>[];
+    var newTypes = <TypeParameterType>[];
+    for (var i = 0; i < T1_parameters.length; i++) {
+      var name = T1_parameters[i].name;
+      var newParameter = TypeParameterElementImpl.synthetic(name);
+      newParameters.add(newParameter);
+
+      var newType = newParameter.instantiate(
+        nullabilitySuffix: NullabilitySuffix.none,
+      );
+      newTypes.add(newType);
+    }
+
+    var T1_substitution = Substitution.fromPairs(T1_parameters, newTypes);
+    var T2_substitution = Substitution.fromPairs(T2_parameters, newTypes);
+    for (var i = 0; i < T1_parameters.length; i++) {
+      var T1_parameter = T1_parameters[i];
+      var T2_parameter = T2_parameters[i];
+
+      var T1_bound = T1_parameter.bound;
+      var T2_bound = T2_parameter.bound;
+      if (T1_bound == null && T2_bound == null) {
+        // OK, no bound.
+      } else if (T1_bound != null && T2_bound != null) {
+        T1_bound = T1_substitution.substituteType(T1_bound);
+        T2_bound = T2_substitution.substituteType(T2_bound);
+        if (!visit(T1_bound, T2_bound)) {
+          return null;
+        }
+      } else {
+        return null;
+      }
+    }
+
+    return _TypeParametersResult(T1_substitution, T2_substitution);
+  }
+}
+
+class _TypeParametersResult {
+  final Substitution T1_substitution;
+  final Substitution T2_substitution;
+
+  _TypeParametersResult(this.T1_substitution, this.T2_substitution);
+}
diff --git a/pkg/analyzer/lib/src/dart/element/type_schema_elimination.dart b/pkg/analyzer/lib/src/dart/element/type_schema_elimination.dart
index cbd52e8..e313b5c 100644
--- a/pkg/analyzer/lib/src/dart/element/type_schema_elimination.dart
+++ b/pkg/analyzer/lib/src/dart/element/type_schema_elimination.dart
@@ -5,57 +5,25 @@
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_algebra.dart';
-import 'package:analyzer/src/dart/element/type_provider.dart';
 import 'package:analyzer/src/generated/type_system.dart';
-
-/// Returns the greatest closure of the given type [schema] with respect to `?`.
-///
-/// The greatest closure of a type schema `P` with respect to `?` is defined as
-/// `P` with every covariant occurrence of `?` replaced with `Null`, and every
-/// contravariant occurrence of `?` replaced with `Object`.
-///
-/// If the schema contains no instances of `?`, the original schema object is
-/// returned to avoid unnecessary allocation.
-///
-/// Note that the closure of a type schema is a proper type.
-///
-/// Note that the greatest closure of a type schema is always a supertype of any
-/// type which matches the schema.
-DartType greatestClosure(TypeProviderImpl typeProvider, DartType schema) {
-  return _TypeSchemaEliminationVisitor.run(typeProvider, false, schema);
-}
-
-/// Returns the least closure of the given type [schema] with respect to `?`.
-///
-/// The least closure of a type schema `P` with respect to `?` is defined as
-/// `P` with every covariant occurrence of `?` replaced with `Object`, and every
-/// contravariant occurrence of `?` replaced with `Null`.
-///
-/// If the schema contains no instances of `?`, the original schema object is
-/// returned to avoid unnecessary allocation.
-///
-/// Note that the closure of a type schema is a proper type.
-///
-/// Note that the least closure of a type schema is always a subtype of any type
-/// which matches the schema.
-DartType leastClosure(TypeProviderImpl typeProvider, DartType schema) {
-  return _TypeSchemaEliminationVisitor.run(typeProvider, true, schema);
-}
+import 'package:meta/meta.dart';
 
 /// Visitor that computes least and greatest closures of a type schema.
 ///
 /// Each visitor method returns `null` if there are no `?`s contained in the
-/// type, otherwise it returns the result of substituting `?` with `Null` or
-/// `Object`, as appropriate.
+/// type, otherwise it returns the result of substituting `?` with [_bottomType]
+/// or [_topType], as appropriate.
 ///
 /// TODO(scheglov) Rewrite using `ReplacementVisitor`, once we have it.
-class _TypeSchemaEliminationVisitor extends InternalTypeSubstitutor {
-  final TypeProviderImpl _typeProvider;
+class TypeSchemaEliminationVisitor extends InternalTypeSubstitutor {
+  final DartType _topType;
+  final DartType _bottomType;
 
   bool _isLeastClosure;
 
-  _TypeSchemaEliminationVisitor(
-    this._typeProvider,
+  TypeSchemaEliminationVisitor._(
+    this._topType,
+    this._bottomType,
     this._isLeastClosure,
   ) : super(null);
 
@@ -79,18 +47,23 @@
   @override
   DartType visitUnknownInferredType(UnknownInferredType type) {
     useCounter++;
-    return _isLeastClosure ? _typeProvider.nullType : _typeProvider.dynamicType;
+    return _isLeastClosure ? _bottomType : _topType;
   }
 
   /// Runs an instance of the visitor on the given [schema] and returns the
   /// resulting type.  If the schema contains no instances of `?`, the original
   /// schema object is returned to avoid unnecessary allocation.
-  static DartType run(
-    TypeProviderImpl typeProvider,
-    bool isLeastClosure,
-    DartType schema,
-  ) {
-    var visitor = _TypeSchemaEliminationVisitor(typeProvider, isLeastClosure);
+  static DartType run({
+    @required DartType topType,
+    @required DartType bottomType,
+    @required bool isLeastClosure,
+    @required DartType schema,
+  }) {
+    var visitor = TypeSchemaEliminationVisitor._(
+      topType,
+      bottomType,
+      isLeastClosure,
+    );
     var result = visitor.visit(schema);
     assert(visitor._isLeastClosure == isLeastClosure);
     return result ?? schema;
diff --git a/pkg/analyzer/lib/src/dart/element/type_visitor.dart b/pkg/analyzer/lib/src/dart/element/type_visitor.dart
index 60ce66d..eff54ee 100644
--- a/pkg/analyzer/lib/src/dart/element/type_visitor.dart
+++ b/pkg/analyzer/lib/src/dart/element/type_visitor.dart
@@ -62,3 +62,76 @@
     throw UnimplementedError('(${type.runtimeType}) $type');
   }
 }
+
+class DartTypeVisitor1<R, T> {
+  const DartTypeVisitor1();
+
+  R defaultDartType(DartType type, T arg) => null;
+
+  R visitDynamicType(DynamicTypeImpl type, T arg) {
+    return defaultDartType(type, arg);
+  }
+
+  R visitFunctionType(FunctionType type, T arg) {
+    return defaultDartType(type, arg);
+  }
+
+  R visitFunctionTypeBuilder(FunctionTypeBuilder type, T arg) {
+    return defaultDartType(type, arg);
+  }
+
+  R visitInterfaceType(InterfaceType type, T arg) {
+    return defaultDartType(type, arg);
+  }
+
+  R visitNamedTypeBuilder(NamedTypeBuilder type, T arg) {
+    return defaultDartType(type, arg);
+  }
+
+  R visitNeverType(NeverTypeImpl type, T arg) {
+    return defaultDartType(type, arg);
+  }
+
+  R visitTypeParameterType(TypeParameterType type, T arg) {
+    return defaultDartType(type, arg);
+  }
+
+  R visitUnknownInferredType(UnknownInferredType type, T arg) {
+    return defaultDartType(type, arg);
+  }
+
+  R visitVoidType(VoidType type, T arg) {
+    return defaultDartType(type, arg);
+  }
+
+  static R visit<R, T>(DartType type, DartTypeVisitor1<R, T> visitor, T arg) {
+    if (type is NeverTypeImpl) {
+      return visitor.visitNeverType(type, arg);
+    }
+    if (type is DynamicTypeImpl) {
+      return visitor.visitDynamicType(type, arg);
+    }
+    if (type is FunctionType) {
+      return visitor.visitFunctionType(type, arg);
+    }
+    if (type is FunctionTypeBuilder) {
+      return visitor.visitFunctionTypeBuilder(type, arg);
+    }
+    if (type is InterfaceType) {
+      return visitor.visitInterfaceType(type, arg);
+    }
+    if (type is NamedTypeBuilder) {
+      return visitor.visitNamedTypeBuilder(type, arg);
+    }
+    if (type is TypeParameterType) {
+      return visitor.visitTypeParameterType(type, arg);
+    }
+    if (type is UnknownInferredType) {
+      return visitor.visitUnknownInferredType(type, arg);
+    }
+    if (type is VoidType) {
+      return visitor.visitVoidType(type, arg);
+    }
+    throw UnimplementedError('(${type.runtimeType}) $type');
+  }
+}
diff --git a/pkg/analyzer/lib/src/dart/error/syntactic_errors.dart b/pkg/analyzer/lib/src/dart/error/syntactic_errors.dart
index c3b76ba..3d72df4 100644
--- a/pkg/analyzer/lib/src/dart/error/syntactic_errors.dart
+++ b/pkg/analyzer/lib/src/dart/error/syntactic_errors.dart
@@ -820,6 +820,15 @@
       _TYPE_PARAMETER_ON_CONSTRUCTOR;
 
   /**
+   * 7.1.1 Operators: Type parameters are not syntactically supported on an
+   * operator.
+   */
+  static const ParserErrorCode TYPE_PARAMETER_ON_OPERATOR = ParserErrorCode(
+      'TYPE_PARAMETERS_ON_OPERATOR',
+      "Types parameters aren't allowed when defining an operator.",
+      correction: "Try removing the type parameters.");
+
+  /**
    * Parameters:
    * 0: the starting character that was missing
    */
diff --git a/pkg/analyzer/lib/src/dart/resolver/invocation_inference_helper.dart b/pkg/analyzer/lib/src/dart/resolver/invocation_inference_helper.dart
index 4275f25..9ac8a76 100644
--- a/pkg/analyzer/lib/src/dart/resolver/invocation_inference_helper.dart
+++ b/pkg/analyzer/lib/src/dart/resolver/invocation_inference_helper.dart
@@ -190,6 +190,7 @@
     if (inferredElement == null || inferredElement.isStatic) {
       return false;
     }
+    inferredElement = _resolver.toLegacyElement(inferredElement);
     DartType inferredType =
         _elementTypeProvider.getExecutableType(inferredElement);
     if (inferredType is FunctionType) {
diff --git a/pkg/analyzer/lib/src/dart/resolver/method_invocation_resolver.dart b/pkg/analyzer/lib/src/dart/resolver/method_invocation_resolver.dart
index 3540a44..d59be4a 100644
--- a/pkg/analyzer/lib/src/dart/resolver/method_invocation_resolver.dart
+++ b/pkg/analyzer/lib/src/dart/resolver/method_invocation_resolver.dart
@@ -549,11 +549,12 @@
       var imports = _definingLibrary.getImportsWithPrefix(prefix);
       if (imports.length == 1 && imports[0].isDeferred) {
         var importedLibrary = imports[0].importedLibrary;
-        var loadLibraryFunction = importedLibrary?.loadLibraryFunction;
-        if (loadLibraryFunction is ExecutableElement) {
-          nameNode.staticElement = loadLibraryFunction;
-          return _setResolution(node,
-              _elementTypeProvider.getExecutableType(loadLibraryFunction));
+        var element = importedLibrary?.loadLibraryFunction;
+        element = _resolver.toLegacyElement(element);
+        if (element is ExecutableElement) {
+          nameNode.staticElement = element;
+          return _setResolution(
+              node, _elementTypeProvider.getExecutableType(element));
         }
       }
     }
diff --git a/pkg/analyzer/lib/src/error/codes.dart b/pkg/analyzer/lib/src/error/codes.dart
index 5439b11..a371761 100644
--- a/pkg/analyzer/lib/src/error/codes.dart
+++ b/pkg/analyzer/lib/src/error/codes.dart
@@ -6719,15 +6719,12 @@
   // ```dart
   // int f(String s) => s.length;
   // ```
-  static const StaticTypeWarningCode UNDEFINED_GETTER =
-      // TODO(brianwilkerson) When the "target" is an enum, report
-      //  UNDEFINED_ENUM_CONSTANT instead.
-      StaticTypeWarningCode('UNDEFINED_GETTER',
-          "The getter '{0}' isn't defined for the class '{1}'.",
-          correction: "Try importing the library that defines '{0}', "
-              "correcting the name to the name of an existing getter, or "
-              "defining a getter or field named '{0}'.",
-          hasPublishedDocs: true);
+  static const StaticTypeWarningCode UNDEFINED_GETTER = StaticTypeWarningCode(
+      'UNDEFINED_GETTER', "The getter '{0}' isn't defined for the type '{1}'.",
+      correction: "Try importing the library that defines '{0}', "
+          "correcting the name to the name of an existing getter, or "
+          "defining a getter or field named '{0}'.",
+      hasPublishedDocs: true);
 
   /**
    * Parameters:
@@ -6759,7 +6756,7 @@
   // int f(List<int> l) => l.removeLast();
   // ```
   static const StaticTypeWarningCode UNDEFINED_METHOD = StaticTypeWarningCode(
-      'UNDEFINED_METHOD', "The method '{0}' isn't defined for the class '{1}'.",
+      'UNDEFINED_METHOD', "The method '{0}' isn't defined for the type '{1}'.",
       correction:
           "Try correcting the name to the name of an existing method, or "
           "defining a method named '{0}'.",
@@ -6799,7 +6796,7 @@
   // ```
   static const StaticTypeWarningCode UNDEFINED_OPERATOR = StaticTypeWarningCode(
       'UNDEFINED_OPERATOR',
-      "The operator '{0}' isn't defined for the class '{1}'.",
+      "The operator '{0}' isn't defined for the type '{1}'.",
       correction: "Try defining the operator '{0}'.",
       hasPublishedDocs: true);
 
@@ -6882,7 +6879,7 @@
   // }
   // ```
   static const StaticTypeWarningCode UNDEFINED_SETTER = StaticTypeWarningCode(
-      'UNDEFINED_SETTER', "The setter '{0}' isn't defined for the class '{1}'.",
+      'UNDEFINED_SETTER', "The setter '{0}' isn't defined for the type '{1}'.",
       correction: "Try importing the library that defines '{0}', "
           "correcting the name to the name of an existing setter, or "
           "defining a setter or field named '{0}'.",
@@ -7943,6 +7940,45 @@
           hasPublishedDocs: true);
 
   /**
+   * 10.3 Setters: It is a compile-time error if a class has a setter named
+   * `v=` with argument type `T` and a getter named `v` with return type `S`,
+   * and `S` may not be assigned to `T`.
+   *
+   * Parameters:
+   * 0: the name of the getter
+   * 1: the type of the getter
+   * 2: the type of the setter
+   * 3: the name of the setter
+   */
+  static const StaticWarningCode GETTER_NOT_ASSIGNABLE_SETTER_TYPES =
+      StaticWarningCode(
+          'GETTER_NOT_ASSIGNABLE_SETTER_TYPES',
+          "The return type of getter '{0}' is '{1}' which isn't assignable "
+              "to the type '{2}' of its setter '{3}'.",
+          correction: "Try changing the types so that they are compatible.");
+
+  /**
+   * nnbd/feature-specification.md
+   *
+   * It is an error if a class has a setter and a getter with the same basename
+   * where the return type of the getter is not a subtype of the argument type
+   * of the setter. Note that this error specifically requires subtyping and
+   * not assignability and hence makes no exception for `dynamic`.
+   *
+   * Parameters:
+   * 0: the name of the getter
+   * 1: the type of the getter
+   * 2: the type of the setter
+   * 3: the name of the setter
+   */
+  static const StaticWarningCode GETTER_NOT_SUBTYPE_SETTER_TYPES =
+      StaticWarningCode(
+          'GETTER_NOT_SUBTYPE_SETTER_TYPES',
+          "The return type of getter '{0}' is '{1}' which isn't a subtype "
+              "of the type '{2}' of its setter '{3}'.",
+          correction: "Try changing the types so that they are compatible.");
+
+  /**
    * 14.1 Imports: It is a static warning to import two different libraries with
    * the same name.
    *
@@ -8165,24 +8201,6 @@
               "'{1}'.");
 
   /**
-   * 10.3 Setters: It is a compile-time error if a class has a setter named
-   * `v=` with argument type `T` and a getter named `v` with return type `S`,
-   * and `S` may not be assigned to `T`.
-   *
-   * Parameters:
-   * 0: the name of the getter
-   * 1: the type of the getter
-   * 2: the type of the setter
-   * 3: the name of the setter
-   */
-  static const StaticWarningCode MISMATCHED_GETTER_AND_SETTER_TYPES =
-      StaticWarningCode(
-          'MISMATCHED_GETTER_AND_SETTER_TYPES',
-          "The return type of getter '{0}' is '{1}' which isn't assignable "
-              "to the type '{2}' of its setter '{3}'.",
-          correction: "Try changing the types so that they are compatible.");
-
-  /**
    * Parameters:
    * 0: the name of the constant that is missing
    */
diff --git a/pkg/analyzer/lib/src/error/correct_override.dart b/pkg/analyzer/lib/src/error/correct_override.dart
new file mode 100644
index 0000000..a737b71
--- /dev/null
+++ b/pkg/analyzer/lib/src/error/correct_override.dart
@@ -0,0 +1,207 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/nullability_suffix.dart';
+import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/error/listener.dart';
+import 'package:analyzer/src/dart/element/element.dart';
+import 'package:analyzer/src/dart/element/type.dart';
+import 'package:analyzer/src/dart/element/type_algebra.dart';
+import 'package:analyzer/src/error/codes.dart';
+import 'package:analyzer/src/generated/resolver.dart' show TypeSystemImpl;
+import 'package:analyzer/src/generated/type_system.dart';
+import 'package:meta/meta.dart';
+
+class CorrectOverrideHelper {
+  final TypeSystemImpl _typeSystem;
+  final ErrorReporter _errorReporter;
+
+  final ExecutableElement _thisMember;
+  FunctionType _thisTypeForSubtype;
+
+  bool _hasCovariant = false;
+  Substitution _thisSubstitution;
+  Substitution _superSubstitution;
+
+  CorrectOverrideHelper({
+    @required TypeSystemImpl typeSystem,
+    @required ErrorReporter errorReporter,
+    @required ExecutableElement thisMember,
+  })  : _typeSystem = typeSystem,
+        _errorReporter = errorReporter,
+        _thisMember = thisMember {
+    _computeThisTypeForSubtype();
+  }
+
+  /// Return `true` if [_thisMember] is a correct override of [superMember].
+  bool isCorrectOverrideOf({
+    @required ExecutableElement superMember,
+  }) {
+    var superType = superMember.type;
+    if (!_typeSystem.isSubtypeOf(_thisTypeForSubtype, superType)) {
+      return false;
+    }
+
+    // If no covariant parameters, then the subtype checking above is enough.
+    if (!_hasCovariant) {
+      return true;
+    }
+
+    _initSubstitutions(superType);
+
+    var thisParameters = _thisMember.parameters;
+    for (var i = 0; i < thisParameters.length; i++) {
+      var thisParameter = thisParameters[i];
+      if (thisParameter.isCovariant) {
+        var superParameter = _correspondingParameter(
+          superType.parameters,
+          thisParameter,
+          i,
+        );
+        if (superParameter != null) {
+          var thisParameterType = thisParameter.type;
+          var superParameterType = superParameter.type;
+
+          if (_thisSubstitution != null) {
+            thisParameterType = _thisSubstitution.substituteType(
+              thisParameterType,
+            );
+            superParameterType = _superSubstitution.substituteType(
+              superParameterType,
+            );
+          }
+
+          if (!_typeSystem.isSubtypeOf(superParameterType, thisParameterType) &&
+              !_typeSystem.isSubtypeOf(thisParameterType, superParameterType)) {
+            return false;
+          }
+        }
+      }
+    }
+
+    return true;
+  }
+
+  /// If [_thisMember] is not a correct override of [superMember], report the
+  /// error.
+  void verify({
+    @required ExecutableElement superMember,
+    @required AstNode errorNode,
+  }) {
+    var isCorrect = isCorrectOverrideOf(superMember: superMember);
+    if (!isCorrect) {
+      _reportInvalidOverride(errorNode, _thisMember, superMember);
+    }
+  }
+
+  /// Fill [_thisTypeForSubtype]. If [_thisMember] has covariant formal
+  /// parameters, replace their types with `Object?` or `Object`.
+  void _computeThisTypeForSubtype() {
+    var parameters = _thisMember.parameters;
+
+    List<ParameterElement> newParameters;
+    for (var i = 0; i < parameters.length; i++) {
+      var parameter = parameters[i];
+      if (parameter.isCovariant) {
+        _hasCovariant = true;
+        newParameters ??= parameters.toList(growable: false);
+        newParameters[i] = ParameterElementImpl.synthetic(
+          parameter.name,
+          _typeSystem.isNonNullableByDefault
+              ? _typeSystem.objectQuestion
+              : _typeSystem.objectStar,
+          // ignore: deprecated_member_use_from_same_package
+          parameter.parameterKind,
+        );
+      }
+    }
+
+    var type = _thisMember.type;
+    if (newParameters != null) {
+      _thisTypeForSubtype = FunctionTypeImpl(
+        typeFormals: type.typeFormals,
+        parameters: newParameters,
+        returnType: type.returnType,
+        nullabilitySuffix: type.nullabilitySuffix,
+      );
+    } else {
+      _thisTypeForSubtype = type;
+    }
+  }
+
+  /// We know that [_thisMember] has a covariant parameter, which we need
+  /// to check against the corresponding parameters in [superType]. their types
+  /// should be compatible. If [_thisMember] (and correspondingly [superType])
+  /// has type parameters, we need to convert types of formal parameters in
+  /// both to the same type parameters.
+  void _initSubstitutions(FunctionType superType) {
+    var thisParameters = _thisMember.typeParameters;
+    var superParameters = superType.typeFormals;
+    if (thisParameters.isEmpty) {
+      return;
+    }
+
+    var newParameters = <TypeParameterElement>[];
+    var newTypes = <TypeParameterType>[];
+    for (var i = 0; i < thisParameters.length; i++) {
+      var newParameter = TypeParameterElementImpl.synthetic(
+        thisParameters[i].name,
+      );
+      newParameters.add(newParameter);
+
+      var newType = newParameter.instantiate(
+        nullabilitySuffix: NullabilitySuffix.none,
+      );
+      newTypes.add(newType);
+    }
+
+    _thisSubstitution = Substitution.fromPairs(thisParameters, newTypes);
+    _superSubstitution = Substitution.fromPairs(superParameters, newTypes);
+  }
+
+  void _reportInvalidOverride(
+    AstNode node,
+    ExecutableElement member,
+    ExecutableElement superMember,
+  ) {
+    _errorReporter.reportErrorForNode(
+      CompileTimeErrorCode.INVALID_OVERRIDE,
+      node,
+      [
+        member.name,
+        member.enclosingElement.name,
+        member.type,
+        superMember.enclosingElement.name,
+        superMember.type,
+      ],
+    );
+  }
+
+  /// Return an element of [parameters] that corresponds for the [proto],
+  /// or `null` if no such parameter exist.
+  static ParameterElement _correspondingParameter(
+    List<ParameterElement> parameters,
+    ParameterElement proto,
+    int protoIndex,
+  ) {
+    if (proto.isPositional) {
+      if (parameters.length > protoIndex) {
+        var parameter = parameters[protoIndex];
+        if (parameter.isPositional) {
+          return parameter;
+        }
+      }
+    } else {
+      assert(proto.isNamed);
+      for (var parameter in parameters) {
+        if (parameter.isNamed && parameter.name == proto.name) {
+          return parameter;
+        }
+      }
+    }
+    return null;
+  }
+}
diff --git a/pkg/analyzer/lib/src/error/getter_setter_types_verifier.dart b/pkg/analyzer/lib/src/error/getter_setter_types_verifier.dart
new file mode 100644
index 0000000..c9287f4
--- /dev/null
+++ b/pkg/analyzer/lib/src/error/getter_setter_types_verifier.dart
@@ -0,0 +1,136 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/error/error.dart';
+import 'package:analyzer/error/listener.dart';
+import 'package:analyzer/src/dart/element/inheritance_manager3.dart';
+import 'package:analyzer/src/error/codes.dart';
+import 'package:analyzer/src/generated/type_system.dart';
+import 'package:meta/meta.dart';
+
+/// Verifies that the return type of the getter matches the parameter type
+/// of the corresponding setter. Where "match" means "subtype" in non-nullable,
+/// and "assignable" in legacy.
+class GetterSetterTypesVerifier {
+  final TypeSystemImpl _typeSystem;
+  final ErrorReporter _errorReporter;
+
+  GetterSetterTypesVerifier({
+    @required TypeSystemImpl typeSystem,
+    @required ErrorReporter errorReporter,
+  })  : _typeSystem = typeSystem,
+        _errorReporter = errorReporter;
+
+  ErrorCode get _errorCode {
+    return _isNonNullableByDefault
+        ? StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES
+        : StaticWarningCode.GETTER_NOT_ASSIGNABLE_SETTER_TYPES;
+  }
+
+  bool get _isNonNullableByDefault => _typeSystem.isNonNullableByDefault;
+
+  void checkExtension(ExtensionDeclaration node) {
+    for (var getterNode in node.members) {
+      if (getterNode is MethodDeclaration && getterNode.isGetter) {
+        checkGetter(getterNode.name, getterNode.declaredElement);
+      }
+    }
+  }
+
+  void checkGetter(
+    SimpleIdentifier nameNode,
+    PropertyAccessorElement getter,
+  ) {
+    assert(getter.isGetter);
+
+    var setter = getter.correspondingSetter;
+    if (setter == null) {
+      return;
+    }
+
+    var getterType = _getGetterType(getter);
+    var setterType = _getSetterType(setter);
+    if (setterType == null) {
+      return;
+    }
+
+    if (!_match(getterType, setterType)) {
+      var name = nameNode.name;
+      _errorReporter.reportErrorForNode(
+        _errorCode,
+        nameNode,
+        [name, getterType, setterType, name],
+      );
+    }
+  }
+
+  void checkInterface(ClassElement classElement, Interface interface) {
+    var libraryUri = classElement.library.source.uri;
+
+    for (var name in interface.map.keys) {
+      if (!name.isAccessibleFor(libraryUri)) continue;
+
+      var getter = interface.map[name];
+      if (getter.kind == ElementKind.GETTER) {
+        var setter = interface.map[Name(libraryUri, '${name.name}=')];
+        if (setter != null && setter.parameters.length == 1) {
+          var getterType = getter.returnType;
+          var setterType = setter.parameters[0].type;
+          if (!_match(getterType, setterType)) {
+            Element errorElement;
+            if (getter.enclosingElement == classElement) {
+              errorElement = getter;
+            } else if (setter.enclosingElement == classElement) {
+              errorElement = setter;
+            } else {
+              errorElement = classElement;
+            }
+
+            var getterName = getter.displayName;
+            if (getter.enclosingElement != classElement) {
+              var getterClassName = getter.enclosingElement.displayName;
+              getterName = '$getterClassName.$getterName';
+            }
+
+            var setterName = setter.displayName;
+            if (setter.enclosingElement != classElement) {
+              var setterClassName = setter.enclosingElement.displayName;
+              setterName = '$setterClassName.$setterName';
+            }
+
+            _errorReporter.reportErrorForElement(
+              _errorCode,
+              errorElement,
+              [getterName, getterType, setterType, setterName],
+            );
+          }
+        }
+      }
+    }
+  }
+
+  bool _match(DartType getterType, DartType setterType) {
+    return _isNonNullableByDefault
+        ? _typeSystem.isSubtypeOf(getterType, setterType)
+        : _typeSystem.isAssignableTo(getterType, setterType);
+  }
+
+  /// Return the return type of the [getter].
+  static DartType _getGetterType(PropertyAccessorElement getter) {
+    return getter.returnType;
+  }
+
+  /// Return the type of the first parameter of the [setter].
+  static DartType _getSetterType(PropertyAccessorElement setter) {
+    var parameters = setter.parameters;
+    if (parameters.isNotEmpty) {
+      return parameters[0].type;
+    } else {
+      return null;
+    }
+  }
+}
diff --git a/pkg/analyzer/lib/src/error/inheritance_override.dart b/pkg/analyzer/lib/src/error/inheritance_override.dart
index 9d3bce8..9d4da67 100644
--- a/pkg/analyzer/lib/src/error/inheritance_override.dart
+++ b/pkg/analyzer/lib/src/error/inheritance_override.dart
@@ -14,6 +14,8 @@
 import 'package:analyzer/src/dart/element/inheritance_manager3.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/error/codes.dart';
+import 'package:analyzer/src/error/correct_override.dart';
+import 'package:analyzer/src/error/getter_setter_types_verifier.dart';
 import 'package:analyzer/src/generated/resolver.dart' show TypeSystemImpl;
 import 'package:analyzer/src/generated/type_system.dart';
 
@@ -184,7 +186,10 @@
       _reportInconsistentInheritance(classNameNode, conflict);
     }
 
-    _checkForMismatchedAccessorTypes(interface);
+    GetterSetterTypesVerifier(
+      typeSystem: typeSystem,
+      errorReporter: reporter,
+    ).checkInterface(classElement, interface);
 
     if (!classElement.isAbstract) {
       List<ExecutableElement> inheritedAbstract;
@@ -226,20 +231,14 @@
         //  diagnostic should be reported on the name of the mixin defining the
         //  method. In other cases, it should be reported on the name of the
         //  overriding method. The classNameNode is always wrong.
-        if (!typeSystem.isOverrideSubtypeOf(
-            concreteElement.type, interfaceElement.type)) {
-          reporter.reportErrorForNode(
-            CompileTimeErrorCode.INVALID_OVERRIDE,
-            classNameNode,
-            [
-              name.name,
-              interfaceElement.enclosingElement.name,
-              interfaceElement.type,
-              concreteElement.enclosingElement.name,
-              concreteElement.type,
-            ],
-          );
-        }
+        CorrectOverrideHelper(
+          typeSystem: typeSystem,
+          errorReporter: reporter,
+          thisMember: concreteElement,
+        ).verify(
+          superMember: interfaceElement,
+          errorNode: classNameNode,
+        );
       }
 
       _reportInheritedAbstractMembers(inheritedAbstract);
@@ -271,35 +270,35 @@
     if (member.isStatic) return;
 
     var name = Name(libraryUri, member.name);
+    var correctOverrideHelper = CorrectOverrideHelper(
+      typeSystem: typeSystem,
+      errorReporter: reporter,
+      thisMember: member,
+    );
+
     for (var superInterface in allSuperinterfaces) {
       var superMember = superInterface.declared[name];
-      if (superMember != null) {
-        // The case when members have different kinds is reported in verifier.
-        // TODO(scheglov) Do it here?
-        if (member.kind != superMember.kind) {
-          continue;
-        }
+      if (superMember == null) {
+        continue;
+      }
 
-        if (!typeSystem.isOverrideSubtypeOf(member.type, superMember.type)) {
-          reporter.reportErrorForNode(
-            CompileTimeErrorCode.INVALID_OVERRIDE,
-            node,
-            [
-              name.name,
-              member.enclosingElement.name,
-              member.type,
-              superMember.enclosingElement.name,
-              superMember.type,
-            ],
-          );
-        }
-        if (methodParameterNodes != null) {
-          _checkForOptionalParametersDifferentDefaultValues(
-            superMember,
-            member,
-            methodParameterNodes,
-          );
-        }
+      // The case when members have different kinds is reported in verifier.
+      // TODO(scheglov) Do it here?
+      if (member.kind != superMember.kind) {
+        continue;
+      }
+
+      correctOverrideHelper.verify(
+        superMember: superMember,
+        errorNode: node,
+      );
+
+      if (methodParameterNodes != null) {
+        _checkForOptionalParametersDifferentDefaultValues(
+          superMember,
+          member,
+          methodParameterNodes,
+        );
       }
     }
   }
@@ -385,49 +384,6 @@
     return hasError;
   }
 
-  void _checkForMismatchedAccessorTypes(Interface interface) {
-    for (var name in interface.map.keys) {
-      if (!name.isAccessibleFor(libraryUri)) continue;
-
-      var getter = interface.map[name];
-      if (getter.kind == ElementKind.GETTER) {
-        // TODO(scheglov) We should separate getters and setters.
-        var setter = interface.map[Name(libraryUri, '${name.name}=')];
-        if (setter != null && setter.parameters.length == 1) {
-          var getterType = getter.returnType;
-          var setterType = setter.parameters[0].type;
-          if (!typeSystem.isAssignableTo(getterType, setterType)) {
-            Element errorElement;
-            if (getter.enclosingElement == classElement) {
-              errorElement = getter;
-            } else if (setter.enclosingElement == classElement) {
-              errorElement = setter;
-            } else {
-              errorElement = classElement;
-            }
-
-            String getterName = getter.displayName;
-            if (getter.enclosingElement != classElement) {
-              var getterClassName = getter.enclosingElement.displayName;
-              getterName = '$getterClassName.$getterName';
-            }
-
-            String setterName = setter.displayName;
-            if (setter.enclosingElement != classElement) {
-              var setterClassName = setter.enclosingElement.displayName;
-              setterName = '$setterClassName.$setterName';
-            }
-
-            reporter.reportErrorForElement(
-                StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES,
-                errorElement,
-                [getterName, getterType, setterType, setterName]);
-          }
-        }
-      }
-    }
-  }
-
   void _checkForOptionalParametersDifferentDefaultValues(
     ExecutableElement baseExecutable,
     ExecutableElement derivedExecutable,
diff --git a/pkg/analyzer/lib/src/fasta/ast_builder.dart b/pkg/analyzer/lib/src/fasta/ast_builder.dart
index 4ab22f4..c612c30 100644
--- a/pkg/analyzer/lib/src/fasta/ast_builder.dart
+++ b/pkg/analyzer/lib/src/fasta/ast_builder.dart
@@ -21,6 +21,7 @@
         messageMissingAssignableSelector,
         messageNativeClauseShouldBeAnnotation,
         messageTypedefNotFunction,
+        messageOperatorWithTypeParameters,
         templateDuplicateLabelInSwitchStatement,
         templateExpectedButGot,
         templateExpectedIdentifier,
@@ -892,6 +893,10 @@
     } else if (name is _OperatorName) {
       operatorKeyword = name.operatorKeyword;
       nameId = name.name;
+      if (typeParameters != null) {
+        handleRecoverableError(messageOperatorWithTypeParameters,
+            typeParameters.beginToken, typeParameters.endToken);
+      }
     } else {
       throw UnimplementedError(
           'name is an instance of ${name.runtimeType} in endClassMethod');
diff --git a/pkg/analyzer/lib/src/fasta/error_converter.dart b/pkg/analyzer/lib/src/fasta/error_converter.dart
index e82aa1a..320a314 100644
--- a/pkg/analyzer/lib/src/fasta/error_converter.dart
+++ b/pkg/analyzer/lib/src/fasta/error_converter.dart
@@ -278,6 +278,10 @@
             offset,
             length);
         return;
+      case "TYPE_PARAMETER_ON_OPERATOR":
+        errorReporter?.reportErrorForOffset(
+            ParserErrorCode.TYPE_PARAMETER_ON_OPERATOR, offset, length);
+        return;
       case "UNDEFINED_CLASS":
         errorReporter?.reportErrorForOffset(
             CompileTimeErrorCode.UNDEFINED_CLASS, offset, length);
diff --git a/pkg/analyzer/lib/src/generated/element_resolver.dart b/pkg/analyzer/lib/src/generated/element_resolver.dart
index d098560..03abc79 100644
--- a/pkg/analyzer/lib/src/generated/element_resolver.dart
+++ b/pkg/analyzer/lib/src/generated/element_resolver.dart
@@ -483,6 +483,7 @@
   @override
   void visitMethodInvocation(MethodInvocation node) {
     _methodInvocationResolver.resolve(node);
+    _resolver.nullShortingTermination(node);
   }
 
   @override
@@ -505,7 +506,9 @@
     if (identifier.name == FunctionElement.LOAD_LIBRARY_NAME &&
         _isDeferredPrefix(prefix)) {
       LibraryElement importedLibrary = _getImportedLibrary(prefix);
-      identifier.staticElement = importedLibrary?.loadLibraryFunction;
+      var element = importedLibrary?.loadLibraryFunction;
+      element = _resolver.toLegacyElement(element);
+      identifier.staticElement = element;
       return;
     }
     //
@@ -1367,8 +1370,11 @@
           propertyName.staticElement = element;
           _checkForStaticAccessToInstanceMember(propertyName, element);
         } else {
+          var code = typeReference.isEnum
+              ? StaticTypeWarningCode.UNDEFINED_ENUM_CONSTANT
+              : StaticTypeWarningCode.UNDEFINED_GETTER;
           _errorReporter.reportErrorForNode(
-            StaticTypeWarningCode.UNDEFINED_GETTER,
+            code,
             propertyName,
             [propertyName.name, typeReference.name],
           );
diff --git a/pkg/analyzer/lib/src/generated/error_verifier.dart b/pkg/analyzer/lib/src/generated/error_verifier.dart
index 7577076..f070892 100644
--- a/pkg/analyzer/lib/src/generated/error_verifier.dart
+++ b/pkg/analyzer/lib/src/generated/error_verifier.dart
@@ -23,7 +23,9 @@
 import 'package:analyzer/src/diagnostic/diagnostic_factory.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/error/constructor_fields_verifier.dart';
+import 'package:analyzer/src/error/correct_override.dart';
 import 'package:analyzer/src/error/duplicate_definition_verifier.dart';
+import 'package:analyzer/src/error/getter_setter_types_verifier.dart';
 import 'package:analyzer/src/error/literal_element_verifier.dart';
 import 'package:analyzer/src/error/required_parameters_verifier.dart';
 import 'package:analyzer/src/error/type_arguments_verifier.dart';
@@ -624,7 +626,12 @@
     _enclosingExtension = node.declaredElement;
     _duplicateDefinitionVerifier.checkExtension(node);
     _checkForFinalNotInitializedInClass(node.members);
-    _checkForMismatchedAccessorTypesInExtension(node);
+
+    GetterSetterTypesVerifier(
+      typeSystem: _typeSystem,
+      errorReporter: _errorReporter,
+    ).checkExtension(node);
+
     final name = node.name;
     if (name != null) {
       _checkForBuiltInIdentifierAsName(
@@ -722,24 +729,21 @@
     ExecutableElement outerFunction = _enclosingFunction;
     try {
       SimpleIdentifier identifier = node.name;
-      String methodName = "";
-      if (identifier != null) {
-        methodName = identifier.name;
-      }
       _enclosingFunction = functionElement;
       TypeAnnotation returnType = node.returnType;
-      if (node.isSetter || node.isGetter) {
-        _checkForMismatchedAccessorTypes(node, methodName);
-        if (node.isSetter) {
-          FunctionExpression functionExpression = node.functionExpression;
-          if (functionExpression != null) {
-            _checkForWrongNumberOfParametersForSetter(
-                identifier, functionExpression.parameters);
-          }
-          _checkForNonVoidReturnTypeForSetter(returnType);
-        }
+      if (node.isGetter) {
+        GetterSetterTypesVerifier(
+          typeSystem: _typeSystem,
+          errorReporter: _errorReporter,
+        ).checkGetter(node.name, node.declaredElement);
       }
       if (node.isSetter) {
+        FunctionExpression functionExpression = node.functionExpression;
+        if (functionExpression != null) {
+          _checkForWrongNumberOfParametersForSetter(
+              identifier, functionExpression.parameters);
+        }
+        _checkForNonVoidReturnTypeForSetter(returnType);
         _checkForInvalidModifierOnBody(node.functionExpression.body,
             CompileTimeErrorCode.INVALID_MODIFIER_ON_SETTER);
       }
@@ -934,6 +938,12 @@
       _isInStaticMethod = node.isStatic;
       _enclosingFunction = node.declaredElement;
       TypeAnnotation returnType = node.returnType;
+      if (node.isStatic && node.isGetter) {
+        GetterSetterTypesVerifier(
+          typeSystem: _typeSystem,
+          errorReporter: _errorReporter,
+        ).checkGetter(node.name, node.declaredElement);
+      }
       if (node.isSetter) {
         _checkForInvalidModifierOnBody(
             node.body, CompileTimeErrorCode.INVALID_MODIFIER_ON_SETTER);
@@ -3374,86 +3384,6 @@
   }
 
   /**
-   * Check to make sure that all similarly typed accessors are of the same type
-   * (including inherited accessors).
-   *
-   * See [StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES].
-   */
-  void _checkForMismatchedAccessorTypes(
-      Declaration accessorDeclaration, String accessorTextName) {
-    ExecutableElement accessorElement =
-        accessorDeclaration.declaredElement as ExecutableElement;
-    if (accessorElement is PropertyAccessorElement) {
-      PropertyAccessorElement counterpartAccessor;
-      if (accessorElement.isGetter) {
-        counterpartAccessor = accessorElement.correspondingSetter;
-      } else {
-        counterpartAccessor = accessorElement.correspondingGetter;
-        // If the setter and getter are in the same enclosing element, return,
-        // this prevents having MISMATCHED_GETTER_AND_SETTER_TYPES reported twice.
-        if (counterpartAccessor != null &&
-            identical(counterpartAccessor.enclosingElement,
-                accessorElement.enclosingElement)) {
-          return;
-        }
-      }
-      if (counterpartAccessor == null) {
-        return;
-      }
-      // Default of null == no accessor or no type (dynamic)
-      DartType getterType;
-      DartType setterType;
-      // Get an existing counterpart accessor if any.
-      if (accessorElement.isGetter) {
-        getterType = _getGetterType(accessorElement);
-        setterType = _getSetterType(counterpartAccessor);
-      } else if (accessorElement.isSetter) {
-        setterType = _getSetterType(accessorElement);
-        getterType = _getGetterType(counterpartAccessor);
-      }
-      // If either types are not assignable to each other, report an error
-      // (if the getter is null, it is dynamic which is assignable to everything).
-      if (setterType != null &&
-          getterType != null &&
-          !_typeSystem.isAssignableTo(getterType, setterType)) {
-        _errorReporter.reportErrorForNode(
-            StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES,
-            accessorDeclaration,
-            [accessorTextName, getterType, setterType, accessorTextName]);
-      }
-    }
-  }
-
-  /**
-   * Check whether all similarly named accessors have consistent types.
-   */
-  void _checkForMismatchedAccessorTypesInExtension(
-      ExtensionDeclaration extension) {
-    for (ClassMember member in extension.members) {
-      if (member is MethodDeclaration && member.isGetter) {
-        PropertyAccessorElement getterElement =
-            member.declaredElement as PropertyAccessorElement;
-        PropertyAccessorElement setterElement =
-            getterElement.correspondingSetter;
-        if (setterElement != null) {
-          DartType getterType = _getGetterType(getterElement);
-          DartType setterType = _getSetterType(setterElement);
-          if (setterType != null &&
-              getterType != null &&
-              !_typeSystem.isAssignableTo(getterType, setterType)) {
-            SimpleIdentifier nameNode = member.name;
-            String name = nameNode.name;
-            _errorReporter.reportErrorForNode(
-                StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES,
-                nameNode,
-                [name, getterType, setterType, name]);
-          }
-        }
-      }
-    }
-  }
-
-  /**
    * Check to make sure that the given switch [statement] whose static type is
    * an enum type either have a default case or include all of the enum
    * constants.
@@ -3643,15 +3573,23 @@
       ExecutableElement mixinMember =
           _inheritanceManager.getMember(mixinType, nameObject, forSuper: true);
 
-      if (mixinMember != null &&
-          !_typeSystem.isOverrideSubtypeOf(
-              superMember.type, mixinMember.type)) {
-        _errorReporter.reportErrorForNode(
+      if (mixinMember != null) {
+        var isCorrect = CorrectOverrideHelper(
+          typeSystem: _typeSystem,
+          errorReporter: _errorReporter,
+          thisMember: superMember,
+        ).isCorrectOverrideOf(
+          superMember: mixinMember,
+        );
+        if (!isCorrect) {
+          _errorReporter.reportErrorForNode(
             CompileTimeErrorCode
                 .MIXIN_APPLICATION_CONCRETE_SUPER_INVOKED_MEMBER_TYPE,
             mixinName.name,
-            [name, mixinMember.type, superMember.type]);
-        return true;
+            [name, mixinMember.type, superMember.type],
+          );
+          return true;
+        }
       }
     }
     return false;
@@ -5416,18 +5354,6 @@
   }
 
   /**
-   * Return the return type of the given [getter].
-   */
-  DartType _getGetterType(PropertyAccessorElement getter) {
-    FunctionType functionType = getter.type;
-    if (functionType != null) {
-      return functionType.returnType;
-    } else {
-      return null;
-    }
-  }
-
-  /**
    * Return a human-readable representation of the kind of the [element].
    */
   String _getKind(ExecutableElement element) {
@@ -5500,19 +5426,6 @@
     return buffer.toString();
   }
 
-  /**
-   * Return the type of the first and only parameter of the given [setter].
-   */
-  DartType _getSetterType(PropertyAccessorElement setter) {
-    // Get the parameters for MethodDeclaration or FunctionDeclaration
-    List<ParameterElement> setterParameters = setter.parameters;
-    // If there are no setter parameters, return no type.
-    if (setterParameters.isEmpty) {
-      return null;
-    }
-    return setterParameters[0].type;
-  }
-
   /// Returns whether [node] overrides a concrete method.
   bool _hasConcreteSuperMethod(MethodDeclaration node) {
     ClassElement classElement = node.declaredElement.enclosingElement;
diff --git a/pkg/analyzer/lib/src/generated/resolver.dart b/pkg/analyzer/lib/src/generated/resolver.dart
index 29fe5a7..90fa793 100644
--- a/pkg/analyzer/lib/src/generated/resolver.dart
+++ b/pkg/analyzer/lib/src/generated/resolver.dart
@@ -2000,6 +2000,7 @@
       // TODO(jmesserly): should we store this earlier in resolution?
       // Or look it up, instead of jumping backwards through the Member?
       var rawElement = originalElement.declaration;
+      rawElement = toLegacyElement(rawElement);
 
       FunctionType constructorType =
           typeAnalyzer.constructorToGenericFunctionType(rawElement);
@@ -2019,15 +2020,20 @@
 
         // Update the static element as well. This is used in some cases, such
         // as computing constant values. It is stored in two places.
-        constructor.staticElement =
-            ConstructorMember.from(rawElement, inferred.returnType);
+        var constructorElement = ConstructorMember.from(
+          rawElement,
+          inferred.returnType,
+        );
+        constructorElement = toLegacyElement(constructorElement);
+        constructor.staticElement = constructorElement;
         node.staticElement = constructor.staticElement;
       }
     }
 
     if (inferred == null) {
-      InferenceContext.setType(node.argumentList,
-          _elementTypeProvider.safeExecutableType(originalElement));
+      var type = _elementTypeProvider.safeExecutableType(originalElement);
+      type = toLegacyTypeIfOptOut(type);
+      InferenceContext.setType(node.argumentList, type);
     }
   }
 
diff --git a/pkg/analyzer/lib/src/generated/static_type_analyzer.dart b/pkg/analyzer/lib/src/generated/static_type_analyzer.dart
index 52ef3d6..295cb6f 100644
--- a/pkg/analyzer/lib/src/generated/static_type_analyzer.dart
+++ b/pkg/analyzer/lib/src/generated/static_type_analyzer.dart
@@ -13,7 +13,6 @@
 import 'package:analyzer/src/dart/element/member.dart' show ConstructorMember;
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_provider.dart';
-import 'package:analyzer/src/dart/element/type_schema_elimination.dart';
 import 'package:analyzer/src/dart/resolver/flow_analysis_visitor.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/element_type_provider.dart';
@@ -165,7 +164,7 @@
         if (p.hasImplicitType &&
             (_elementTypeProvider.getVariableType(p) == null ||
                 _elementTypeProvider.getVariableType(p).isDynamic)) {
-          inferredType = greatestClosure(_typeProvider, inferredType);
+          inferredType = _typeSystem.greatestClosure(inferredType);
           if (inferredType.isDartCoreNull) {
             inferredType = _typeProvider.objectType;
           }
@@ -233,18 +232,9 @@
    */
   @override
   void visitAwaitExpression(AwaitExpression node) {
-    // Await the Future. This results in whatever type is (ultimately) returned.
-    DartType awaitType(DartType awaitedType) {
-      if (awaitedType == null) {
-        return null;
-      }
-      if (awaitedType.isDartAsyncFutureOr) {
-        return awaitType((awaitedType as InterfaceType).typeArguments[0]);
-      }
-      return _typeSystem.flatten(awaitedType);
-    }
-
-    _recordStaticType(node, awaitType(_getStaticType(node.expression)));
+    DartType resultType = _getStaticType(node.expression);
+    if (resultType != null) resultType = _typeSystem.flatten(resultType);
+    _recordStaticType(node, resultType);
   }
 
   /**
@@ -935,6 +925,7 @@
     // TODO(jmesserly): should we store this earlier in resolution?
     // Or look it up, instead of jumping backwards through the Member?
     var rawElement = originalElement.declaration;
+    rawElement = _resolver.toLegacyElement(rawElement);
 
     FunctionType constructorType = constructorToGenericFunctionType(rawElement);
 
@@ -957,8 +948,12 @@
       constructor.type.type = inferred.returnType;
       // Update the static element as well. This is used in some cases, such as
       // computing constant values. It is stored in two places.
-      constructor.staticElement =
-          ConstructorMember.from(rawElement, inferred.returnType);
+      var constructorElement = ConstructorMember.from(
+        rawElement,
+        inferred.returnType,
+      );
+      constructorElement = _resolver.toLegacyElement(constructorElement);
+      constructor.staticElement = constructorElement;
       node.staticElement = constructor.staticElement;
     }
   }
@@ -1032,6 +1027,7 @@
     if (inferredElement == null || inferredElement.isStatic) {
       return false;
     }
+    inferredElement = _resolver.toLegacyElement(inferredElement);
     DartType inferredType =
         _elementTypeProvider.getExecutableReturnType(inferredElement);
     if (nodeType != null &&
diff --git a/pkg/analyzer/lib/src/generated/type_system.dart b/pkg/analyzer/lib/src/generated/type_system.dart
index b984405..ed9acc4 100644
--- a/pkg/analyzer/lib/src/generated/type_system.dart
+++ b/pkg/analyzer/lib/src/generated/type_system.dart
@@ -18,6 +18,7 @@
 import 'package:analyzer/src/dart/element/member.dart' show TypeParameterMember;
 import 'package:analyzer/src/dart/element/normalize.dart';
 import 'package:analyzer/src/dart/element/nullability_eliminator.dart';
+import 'package:analyzer/src/dart/element/runtime_type_equality.dart';
 import 'package:analyzer/src/dart/element/top_merge.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_algebra.dart';
@@ -85,6 +86,9 @@
   /// The cached instance of `Object?`.
   InterfaceTypeImpl _objectQuestionCached;
 
+  /// The cached instance of `Object*`.
+  InterfaceTypeImpl _objectStarCached;
+
   /// The cached instance of `Object!`.
   InterfaceTypeImpl _objectNoneCached;
 
@@ -110,6 +114,10 @@
       _objectQuestionCached ??= (typeProvider.objectType as TypeImpl)
           .withNullability(NullabilitySuffix.question);
 
+  InterfaceTypeImpl get objectStar =>
+      _objectStarCached ??= (typeProvider.objectType as TypeImpl)
+          .withNullability(NullabilitySuffix.star);
+
   InterfaceType get _interfaceTypeFunctionNone {
     return typeProvider.functionType.element.instantiate(
       typeArguments: const [],
@@ -138,6 +146,35 @@
     return ft.parameters.any((p) => predicate(p.type));
   }
 
+  /**
+   * Eliminates type variables from the context [type], replacing them with
+   * `Null` or `Object` as appropriate.
+   *
+   * For example in `List<T> list = const []`, the context type for inferring
+   * the list should be changed from `List<T>` to `List<Null>` so the constant
+   * doesn't depend on the type variables `T` (because it can't be canonicalized
+   * at compile time, as `T` is unknown).
+   *
+   * Conceptually this is similar to the "least closure", except instead of
+   * eliminating `?` ([UnknownInferredType]) it eliminates all type variables
+   * ([TypeParameterType]).
+   *
+   * The equivalent CFE code can be found in the `TypeVariableEliminator` class.
+   */
+  DartType eliminateTypeVariables(DartType type) {
+    if (isNonNullableByDefault) {
+      return _TypeVariableEliminator(
+        objectQuestion,
+        NeverTypeImpl.instance,
+      ).substituteType(type);
+    } else {
+      return _TypeVariableEliminator(
+        objectNone,
+        typeProvider.nullType,
+      ).substituteType(type);
+    }
+  }
+
   /// Given a type t, if t is an interface type with a call method
   /// defined, return the function type for the call method, otherwise
   /// return null.
@@ -669,7 +706,7 @@
 
     if (contextReturnType != null) {
       if (isConst) {
-        contextReturnType = _eliminateTypeVariables(contextReturnType);
+        contextReturnType = eliminateTypeVariables(contextReturnType);
       }
       inferrer.constrainReturnType(declaredReturnType, contextReturnType);
     }
@@ -1444,6 +1481,11 @@
 
   /// Return `true` for any type which is in the equivalence class of top types.
   bool isTop(DartType type) {
+    // TOP(?) is true
+    if (identical(type, UnknownInferredType.instance)) {
+      return true;
+    }
+
     // TOP(dynamic) is true
     if (identical(type, DynamicTypeImpl.instance)) {
       return true;
@@ -1486,6 +1528,13 @@
     return NormalizeHelper(this).normalize(T);
   }
 
+  /// Return `true` if runtime types [T1] and [T2] are equal.
+  ///
+  /// nnbd/feature-specification.md#runtime-type-equality-operator
+  bool runtimeTypesEqual(DartType T1, DartType T2) {
+    return RuntimeTypeEqualityHelper(this).equal(T1, T2);
+  }
+
   @override
   DartType refineBinaryExpressionType(DartType leftType, TokenType operator,
       DartType rightType, DartType currentType) {
@@ -1578,25 +1627,6 @@
   }
 
   /**
-   * Eliminates type variables from the context [type], replacing them with
-   * `Null` or `Object` as appropriate.
-   *
-   * For example in `List<T> list = const []`, the context type for inferring
-   * the list should be changed from `List<T>` to `List<Null>` so the constant
-   * doesn't depend on the type variables `T` (because it can't be canonicalized
-   * at compile time, as `T` is unknown).
-   *
-   * Conceptually this is similar to the "least closure", except instead of
-   * eliminating `?` ([UnknownInferredType]) it eliminates all type variables
-   * ([TypeParameterType]).
-   *
-   * The equivalent CFE code can be found in the `TypeVariableEliminator` class.
-   */
-  DartType _eliminateTypeVariables(DartType type) {
-    return TypeVariableEliminator(typeProvider).substituteType(type);
-  }
-
-  /**
    * Compute the greatest lower bound of function types [f] and [g].
    *
    * https://github.com/dart-lang/language
@@ -2400,14 +2430,10 @@
         return lower;
       }
       if (!identical(UnknownInferredType.instance, upper)) {
-        return toKnownType
-            ? greatestClosure(_typeSystem.typeProvider, upper)
-            : upper;
+        return toKnownType ? _typeSystem.greatestClosure(upper) : upper;
       }
       if (!identical(UnknownInferredType.instance, lower)) {
-        return toKnownType
-            ? leastClosure(_typeSystem.typeProvider, lower)
-            : lower;
+        return toKnownType ? _typeSystem.leastClosure(lower) : lower;
       }
       return upper;
     } else {
@@ -2418,14 +2444,10 @@
         return upper;
       }
       if (!identical(UnknownInferredType.instance, lower)) {
-        return toKnownType
-            ? leastClosure(_typeSystem.typeProvider, lower)
-            : lower;
+        return toKnownType ? _typeSystem.leastClosure(lower) : lower;
       }
       if (!identical(UnknownInferredType.instance, upper)) {
-        return toKnownType
-            ? greatestClosure(_typeSystem.typeProvider, upper)
-            : upper;
+        return toKnownType ? _typeSystem.greatestClosure(upper) : upper;
       }
       return lower;
     }
@@ -2503,7 +2525,6 @@
         // GLB(A, FutureOr<B>) ==  GLB(FutureOr<B>, A)
         return _getGreatestLowerBound(t2, t1);
       }
-      return typeProvider.nullType;
     }
     return result;
   }
@@ -3727,16 +3748,67 @@
           strictInference: strictInference,
           typeProvider: typeProvider,
         );
-}
 
-class TypeVariableEliminator extends Substitution {
-  final TypeProvider _typeProvider;
+  /// Returns the greatest closure of the given type [schema] with respect to `?`.
+  ///
+  /// The greatest closure of a type schema `P` with respect to `?` is defined as
+  /// `P` with every covariant occurrence of `?` replaced with `Null`, and every
+  /// contravariant occurrence of `?` replaced with `Object`.
+  ///
+  /// If the schema contains no instances of `?`, the original schema object is
+  /// returned to avoid unnecessary allocation.
+  ///
+  /// Note that the closure of a type schema is a proper type.
+  ///
+  /// Note that the greatest closure of a type schema is always a supertype of
+  /// any type which matches the schema.
+  DartType greatestClosure(DartType schema) {
+    if (isNonNullableByDefault) {
+      return TypeSchemaEliminationVisitor.run(
+        topType: objectQuestion,
+        bottomType: NeverTypeImpl.instance,
+        isLeastClosure: false,
+        schema: schema,
+      );
+    } else {
+      return TypeSchemaEliminationVisitor.run(
+        topType: DynamicTypeImpl.instance,
+        bottomType: typeProvider.nullType,
+        isLeastClosure: false,
+        schema: schema,
+      );
+    }
+  }
 
-  TypeVariableEliminator(this._typeProvider);
-
-  @override
-  DartType getSubstitute(TypeParameterElement parameter, bool upperBound) {
-    return upperBound ? _typeProvider.nullType : _typeProvider.objectType;
+  /// Returns the least closure of the given type [schema] with respect to `?`.
+  ///
+  /// The least closure of a type schema `P` with respect to `?` is defined as
+  /// `P` with every covariant occurrence of `?` replaced with `Object`, an
+  /// every contravariant occurrence of `?` replaced with `Null`.
+  ///
+  /// If the schema contains no instances of `?`, the original schema object is
+  /// returned to avoid unnecessary allocation.
+  ///
+  /// Note that the closure of a type schema is a proper type.
+  ///
+  /// Note that the least closure of a type schema is always a subtype of any
+  /// type which matches the schema.
+  DartType leastClosure(DartType schema) {
+    if (isNonNullableByDefault) {
+      return TypeSchemaEliminationVisitor.run(
+        topType: objectQuestion,
+        bottomType: NeverTypeImpl.instance,
+        isLeastClosure: true,
+        schema: schema,
+      );
+    } else {
+      return TypeSchemaEliminationVisitor.run(
+        topType: DynamicTypeImpl.instance,
+        bottomType: typeProvider.nullType,
+        isLeastClosure: true,
+        schema: schema,
+      );
+    }
   }
 }
 
@@ -4055,3 +4127,18 @@
   @override
   String toString() => format('(type)', withNullability: true);
 }
+
+class _TypeVariableEliminator extends Substitution {
+  final DartType _topType;
+  final DartType _bottomType;
+
+  _TypeVariableEliminator(
+    this._topType,
+    this._bottomType,
+  );
+
+  @override
+  DartType getSubstitute(TypeParameterElement parameter, bool upperBound) {
+    return upperBound ? _bottomType : _topType;
+  }
+}
diff --git a/pkg/analyzer/lib/src/lint/pub.dart b/pkg/analyzer/lib/src/lint/pub.dart
index def9287..5b85e71 100644
--- a/pkg/analyzer/lib/src/lint/pub.dart
+++ b/pkg/analyzer/lib/src/lint/pub.dart
@@ -77,6 +77,7 @@
   PSGitRepo get git;
   PSHost get host;
   PSNode get name;
+  PSEntry get path;
   PSEntry get version;
 }
 
@@ -150,6 +151,8 @@
   @override
   PSNode name;
   @override
+  PSEntry path;
+  @override
   PSEntry version;
   @override
   PSHost host;
@@ -181,6 +184,9 @@
         }
         YamlScalar key = k;
         switch (key.toString()) {
+          case 'path':
+            dep.path = _processScalar(key, v);
+            break;
           case 'version':
             dep.version = _processScalar(key, v);
             break;
diff --git a/pkg/analyzer/lib/src/summary2/default_value_resolver.dart b/pkg/analyzer/lib/src/summary2/default_value_resolver.dart
index f879cd1..3a68f9e 100644
--- a/pkg/analyzer/lib/src/summary2/default_value_resolver.dart
+++ b/pkg/analyzer/lib/src/summary2/default_value_resolver.dart
@@ -16,6 +16,7 @@
 class DefaultValueResolver {
   final Linker _linker;
   final LibraryElementImpl _libraryElement;
+  final TypeSystemImpl _typeSystem;
 
   ClassElement _classElement;
   CompilationUnitElement _unitElement;
@@ -24,7 +25,8 @@
 
   AstResolver _astResolver;
 
-  DefaultValueResolver(this._linker, this._libraryElement);
+  DefaultValueResolver(this._linker, this._libraryElement)
+      : _typeSystem = _libraryElement.typeSystem;
 
   void resolve() {
     for (CompilationUnitElementImpl unit in _libraryElement.units) {
@@ -100,8 +102,7 @@
     var node = _defaultParameter(parameter);
     if (node == null) return;
 
-    var contextType = TypeVariableEliminator(_libraryElement.typeProvider)
-        .substituteType(parameter.type);
+    var contextType = _typeSystem.eliminateTypeVariables(parameter.type);
 
     _astResolver ??= AstResolver(_linker, _unitElement, _scope);
     _astResolver.resolve(
diff --git a/pkg/analyzer/test/generated/elements_types_mixin.dart b/pkg/analyzer/test/generated/elements_types_mixin.dart
index d611abf..95d38f6 100644
--- a/pkg/analyzer/test/generated/elements_types_mixin.dart
+++ b/pkg/analyzer/test/generated/elements_types_mixin.dart
@@ -14,6 +14,21 @@
 import 'package:meta/meta.dart';
 
 mixin ElementsTypesMixin {
+  InterfaceType get boolNone {
+    var element = typeProvider.boolElement;
+    return interfaceTypeNone(element);
+  }
+
+  InterfaceType get boolQuestion {
+    var element = typeProvider.boolElement;
+    return interfaceTypeQuestion(element);
+  }
+
+  InterfaceType get boolStar {
+    var element = typeProvider.boolElement;
+    return interfaceTypeStar(element);
+  }
+
   InterfaceType get doubleNone {
     var element = typeProvider.doubleType.element;
     return interfaceTypeNone(element);
diff --git a/pkg/analyzer/test/generated/non_error_resolver_test.dart b/pkg/analyzer/test/generated/non_error_resolver_test.dart
index 7903489..11645ae 100644
--- a/pkg/analyzer/test/generated/non_error_resolver_test.dart
+++ b/pkg/analyzer/test/generated/non_error_resolver_test.dart
@@ -3528,16 +3528,6 @@
 ''');
   }
 
-  @failingTest
-  test_undefinedEnumConstant() async {
-    await assertNoErrorsInCode(r'''
-enum E { ONE }
-E e() {
-  return E.TWO;
-}
-''');
-  }
-
   test_undefinedSuperMethod_field() async {
     await assertNoErrorsInCode(r'''
 class A {
diff --git a/pkg/analyzer/test/generated/simple_resolver_test.dart b/pkg/analyzer/test/generated/simple_resolver_test.dart
index 37a9f11..fc78f6a 100644
--- a/pkg/analyzer/test/generated/simple_resolver_test.dart
+++ b/pkg/analyzer/test/generated/simple_resolver_test.dart
@@ -652,20 +652,6 @@
     );
   }
 
-  test_getterAndSetterWithDifferentTypes() async {
-    await assertErrorsInCode(r'''
-class A {
-  int get f => 0;
-  void set f(String s) {}
-}
-g (A a) {
-  a.f = a.f.toString();
-}''', [
-      error(StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES, 20, 1),
-    ]);
-    verifyTestResolved();
-  }
-
   test_hasReferenceToSuper() async {
     await assertNoErrorsInCode(r'''
 class A {}
diff --git a/pkg/analyzer/test/generated/static_type_warning_code_test.dart b/pkg/analyzer/test/generated/static_type_warning_code_test.dart
index d388a8a..9e1de0d 100644
--- a/pkg/analyzer/test/generated/static_type_warning_code_test.dart
+++ b/pkg/analyzer/test/generated/static_type_warning_code_test.dart
@@ -1173,18 +1173,6 @@
     ]);
   }
 
-  test_undefinedEnumConstant() async {
-    // We should be reporting UNDEFINED_ENUM_CONSTANT here.
-    await assertErrorsInCode(r'''
-enum E { ONE }
-E e() {
-  return E.TWO;
-}
-''', [
-      error(StaticTypeWarningCode.UNDEFINED_GETTER, 34, 3),
-    ]);
-  }
-
   test_unqualifiedReferenceToNonLocalStaticMember_getter() async {
     await assertErrorsInCode(r'''
 class A {
diff --git a/pkg/analyzer/test/src/dart/analysis/driver_resolution_test.dart b/pkg/analyzer/test/src/dart/analysis/driver_resolution_test.dart
index 016cab85..06c9a55 100644
--- a/pkg/analyzer/test/src/dart/analysis/driver_resolution_test.dart
+++ b/pkg/analyzer/test/src/dart/analysis/driver_resolution_test.dart
@@ -2584,7 +2584,13 @@
     var invocation = findNode.methodInvocation('codeUnitAt');
     assertType(invocation, 'int');
     assertInvokeType(invocation, 'int Function(int)');
-    assertElement(invocation.methodName, stringElement.getMethod('codeUnitAt'));
+    assertElement(
+      invocation.methodName,
+      elementMatcher(
+        stringElement.getMethod('codeUnitAt'),
+        isLegacy: isNullSafetySdkAndLegacyLibrary,
+      ),
+    );
 
     var aRef = invocation.target;
     assertElement(aRef, findElement.topGet('a'));
@@ -8373,7 +8379,7 @@
     expect(result.errors, isNotEmpty);
 
     PropertyAccessorElement objectHashCode =
-        typeProvider.objectType.getGetter('hashCode');
+        objectElement.getGetter('hashCode');
     TopLevelVariableElement foo = _getTopLevelVariable(result, 'foo');
 
     List<Statement> statements = _getMainStatements(result);
@@ -8384,16 +8390,28 @@
 
     {
       PrefixedIdentifier prefixed = propertyAccess.target;
-      expect(prefixed.staticElement, same(objectHashCode));
-      expect(prefixed.staticType, typeProvider.intType);
+      assertPrefixedIdentifier(
+        prefixed,
+        element: elementMatcher(
+          objectHashCode,
+          isLegacy: isNullSafetySdkAndLegacyLibrary,
+        ),
+        type: 'int',
+      );
 
       SimpleIdentifier prefix = prefixed.prefix;
       expect(prefix.staticElement, same(foo.getter));
       expect(prefix.staticType, typeProvider.objectType);
 
       SimpleIdentifier identifier = prefixed.identifier;
-      expect(identifier.staticElement, same(objectHashCode));
-      expect(identifier.staticType, typeProvider.intType);
+      assertSimpleIdentifier(
+        identifier,
+        element: elementMatcher(
+          objectHashCode,
+          isLegacy: isNullSafetySdkAndLegacyLibrary,
+        ),
+        type: 'int',
+      );
     }
 
     SimpleIdentifier property = propertyAccess.propertyName;
diff --git a/pkg/analyzer/test/src/dart/analysis/search_test.dart b/pkg/analyzer/test/src/dart/analysis/search_test.dart
index 3cd4c5d..9da9fb7 100644
--- a/pkg/analyzer/test/src/dart/analysis/search_test.dart
+++ b/pkg/analyzer/test/src/dart/analysis/search_test.dart
@@ -23,6 +23,7 @@
   defineReflectiveSuite(() {
     defineReflectiveTests(SearchTest);
     defineReflectiveTests(SearchWithExtensionMethodsTest);
+    defineReflectiveTests(SearchWithNnbdTest);
   });
 }
 
@@ -1791,3 +1792,72 @@
     await _verifyReferences(element, expected);
   }
 }
+
+@reflectiveTest
+class SearchWithNnbdTest extends SearchTest {
+  @override
+  AnalysisOptionsImpl createAnalysisOptions() => AnalysisOptionsImpl()
+    ..contextFeatures = FeatureSet.forTesting(
+        sdkVersion: '2.7.0', additionalFeatures: [Feature.non_nullable]);
+
+  test_searchReferences_ImportElement_noPrefix_optIn_fromOptOut() async {
+    newFile('/test/lib/a.dart', content: r'''
+class N1 {}
+void N2() {}
+int get N3 => 0;
+set N4(int _) {}
+''');
+
+    await _resolveTestUnit('''
+// @dart = 2.7
+import 'a.dart';
+
+main() {
+  N1;
+  N2();
+  N3;
+}
+''');
+    ImportElement element = testLibraryElement.imports[0];
+    Element mainElement = _findElement('main');
+    var kind = SearchResultKind.REFERENCE;
+    var expected = [
+      _expectId(mainElement, kind, 'N1;', length: 0),
+      _expectId(mainElement, kind, 'N2();', length: 0),
+      _expectId(mainElement, kind, 'N3;', length: 0),
+//      _expectId(mainElement, kind, 'N4 =', length: 0),
+    ];
+    await _verifyReferences(element, expected);
+  }
+
+  test_searchReferences_ImportElement_withPrefix_optIn_fromOptOut() async {
+    newFile('/test/lib/a.dart', content: r'''
+class N1 {}
+void N2() {}
+int get N3 => 0;
+set N4(int _) {}
+''');
+
+    await _resolveTestUnit('''
+// @dart = 2.7
+import 'a.dart' as a;
+
+main() {
+  a.N1;
+  a.N2();
+  a.N3;
+}
+''');
+    ImportElement element = testLibraryElement.imports[0];
+    Element mainElement = _findElement('main');
+    var kind = SearchResultKind.REFERENCE;
+    var length = 'a.'.length;
+    var expected = [
+      _expectId(mainElement, kind, 'a.N1;', length: length),
+      _expectId(mainElement, kind, 'a.N2()', length: length),
+      _expectId(mainElement, kind, 'a.N3', length: length),
+//      _expectId(mainElement, kind, 'a.N4', length: length),
+    ];
+    await _verifyReferences(element, expected);
+  }
+}
diff --git a/pkg/analyzer/test/src/dart/element/runtime_type_equality_test.dart b/pkg/analyzer/test/src/dart/element/runtime_type_equality_test.dart
new file mode 100644
index 0000000..8a1b16f
--- /dev/null
+++ b/pkg/analyzer/test/src/dart/element/runtime_type_equality_test.dart
@@ -0,0 +1,360 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/dart/analysis/features.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/dart/element/type_provider.dart';
+import 'package:analyzer/src/dart/element/type.dart';
+import 'package:analyzer/src/generated/resolver.dart' show TypeSystemImpl;
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../../../generated/elements_types_mixin.dart';
+import '../../../generated/test_analysis_context.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(RuntimeTypeEqualityTypeTest);
+  });
+}
+
+@reflectiveTest
+class RuntimeTypeEqualityTypeTest with ElementsTypesMixin {
+  @override
+  TypeProvider typeProvider;
+
+  TypeSystemImpl typeSystem;
+
+  FeatureSet get testFeatureSet {
+    return FeatureSet.forTesting(
+      additionalFeatures: [Feature.non_nullable],
+    );
+  }
+
+  void setUp() {
+    var analysisContext = TestAnalysisContext(
+      featureSet: testFeatureSet,
+    );
+    typeProvider = analysisContext.typeProviderNonNullableByDefault;
+    typeSystem = analysisContext.typeSystemNonNullableByDefault;
+  }
+
+  test_dynamic() {
+    _equal(dynamicNone, dynamicNone);
+    _notEqual(dynamicNone, voidNone);
+    _notEqual(dynamicNone, intNone);
+
+    _notEqual(dynamicNone, neverNone);
+    _notEqual(dynamicNone, neverQuestion);
+    _notEqual(dynamicNone, neverStar);
+  }
+
+  test_functionType_parameters() {
+    void check(
+      ParameterElement T1_parameter,
+      ParameterElement T2_parameter,
+      bool expected,
+    ) {
+      var T1 = functionTypeNone(
+        returnType: voidNone,
+        parameters: [T1_parameter],
+      );
+      var T2 = functionTypeNone(
+        returnType: voidNone,
+        parameters: [T2_parameter],
+      );
+      _check(T1, T2, expected);
+    }
+
+    {
+      void checkRequiredParameter(
+        DartType T1_type,
+        DartType T2_type,
+        bool expected,
+      ) {
+        check(
+          requiredParameter(type: T1_type),
+          requiredParameter(type: T2_type),
+          expected,
+        );
+      }
+
+      checkRequiredParameter(intNone, intNone, true);
+      checkRequiredParameter(intNone, intQuestion, false);
+      checkRequiredParameter(intNone, intStar, true);
+
+      checkRequiredParameter(intQuestion, intNone, false);
+      checkRequiredParameter(intQuestion, intQuestion, true);
+      checkRequiredParameter(intQuestion, intStar, false);
+
+      checkRequiredParameter(intStar, intNone, true);
+      checkRequiredParameter(intStar, intQuestion, false);
+      checkRequiredParameter(intStar, intStar, true);
+
+      check(
+        requiredParameter(type: intNone, name: 'a'),
+        requiredParameter(type: intNone, name: 'b'),
+        true,
+      );
+
+      check(
+        requiredParameter(type: intNone),
+        positionalParameter(type: intNone),
+        false,
+      );
+
+      check(
+        requiredParameter(type: intNone),
+        namedParameter(type: intNone, name: 'a'),
+        false,
+      );
+
+      check(
+        requiredParameter(type: intNone),
+        namedRequiredParameter(type: intNone, name: 'a'),
+        false,
+      );
+    }
+
+    {
+      check(
+        namedParameter(type: intNone, name: 'a'),
+        namedParameter(type: intNone, name: 'a'),
+        true,
+      );
+
+      check(
+        namedParameter(type: intNone, name: 'a'),
+        namedParameter(type: boolNone, name: 'a'),
+        false,
+      );
+
+      check(
+        namedParameter(type: intNone, name: 'a'),
+        namedParameter(type: intNone, name: 'b'),
+        false,
+      );
+
+      check(
+        namedParameter(type: intNone, name: 'a'),
+        namedRequiredParameter(type: intNone, name: 'a'),
+        false,
+      );
+    }
+
+    {
+      check(
+        namedRequiredParameter(type: intNone, name: 'a'),
+        namedRequiredParameter(type: intNone, name: 'a'),
+        true,
+      );
+
+      check(
+        namedRequiredParameter(type: intNone, name: 'a'),
+        namedRequiredParameter(type: boolNone, name: 'a'),
+        false,
+      );
+
+      check(
+        namedRequiredParameter(type: intNone, name: 'a'),
+        namedRequiredParameter(type: intNone, name: 'b'),
+        false,
+      );
+
+      check(
+        namedRequiredParameter(type: intNone, name: 'a'),
+        namedParameter(type: intNone, name: 'a'),
+        false,
+      );
+    }
+  }
+
+  test_functionType_returnType() {
+    void check(
+      DartType T1_returnType,
+      DartType T2_returnType,
+      bool expected,
+    ) {
+      var T1 = functionTypeNone(
+        returnType: T1_returnType,
+      );
+      var T2 = functionTypeNone(
+        returnType: T2_returnType,
+      );
+      _check(T1, T2, expected);
+    }
+
+    check(intNone, intNone, true);
+    check(intNone, intQuestion, false);
+    check(intNone, intStar, true);
+  }
+
+  test_functionType_typeParameters() {
+    {
+      var T1_T = typeParameter('T', bound: numNone);
+      _check(
+        functionTypeNone(
+          typeFormals: [T1_T],
+          returnType: voidNone,
+        ),
+        functionTypeNone(
+          returnType: voidNone,
+        ),
+        false,
+      );
+    }
+
+    {
+      var T1_T = typeParameter('T', bound: numNone);
+      var T2_U = typeParameter('U');
+      _check(
+        functionTypeNone(
+          typeFormals: [T1_T],
+          returnType: voidNone,
+        ),
+        functionTypeNone(
+          typeFormals: [T2_U],
+          returnType: voidNone,
+        ),
+        false,
+      );
+    }
+
+    {
+      var T1_T = typeParameter('T');
+      var T2_U = typeParameter('U');
+      _check(
+        functionTypeNone(
+          typeFormals: [T1_T],
+          returnType: typeParameterTypeNone(T1_T),
+          parameters: [
+            requiredParameter(
+              type: typeParameterTypeNone(T1_T),
+            )
+          ],
+        ),
+        functionTypeNone(
+          typeFormals: [T2_U],
+          returnType: typeParameterTypeNone(T2_U),
+          parameters: [
+            requiredParameter(
+              type: typeParameterTypeNone(T2_U),
+            )
+          ],
+        ),
+        true,
+      );
+    }
+  }
+
+  test_interfaceType() {
+    _notEqual(intNone, boolNone);
+
+    _equal(intNone, intNone);
+    _notEqual(intNone, intQuestion);
+    _equal(intNone, intStar);
+
+    _notEqual(intQuestion, intNone);
+    _equal(intQuestion, intQuestion);
+    _notEqual(intQuestion, intStar);
+
+    _equal(intStar, intNone);
+    _notEqual(intStar, intQuestion);
+    _equal(intStar, intStar);
+  }
+
+  test_interfaceType_typeArguments() {
+    void _equal(DartType T1, DartType T2) {
+      this._equal(listNone(T1), listNone(T2));
+    }
+
+    void _notEqual(DartType T1, DartType T2) {
+      this._notEqual(listNone(T1), listNone(T2));
+    }
+
+    _notEqual(intNone, boolNone);
+
+    _equal(intNone, intNone);
+    _notEqual(intNone, intQuestion);
+    _equal(intNone, intStar);
+
+    _notEqual(intQuestion, intNone);
+    _equal(intQuestion, intQuestion);
+    _notEqual(intQuestion, intStar);
+
+    _equal(intStar, intNone);
+    _notEqual(intStar, intQuestion);
+    _equal(intStar, intStar);
+  }
+
+  test_never() {
+    _equal(neverNone, neverNone);
+    _notEqual(neverNone, neverQuestion);
+    _equal(neverNone, neverStar);
+    _notEqual(neverNone, intNone);
+
+    _notEqual(neverQuestion, neverNone);
+    _equal(neverQuestion, neverQuestion);
+    _notEqual(neverQuestion, neverStar);
+    _notEqual(neverQuestion, intNone);
+    _equal(neverQuestion, nullNone);
+
+    _equal(neverStar, neverNone);
+    _notEqual(neverStar, neverQuestion);
+    _equal(neverStar, neverStar);
+    _notEqual(neverStar, intNone);
+  }
+
+  test_norm() {
+    _equal(futureOrNone(objectNone), objectNone);
+    _equal(futureOrNone(neverNone), futureNone(neverNone));
+    _equal(neverQuestion, nullNone);
+  }
+
+  test_void() {
+    _equal(voidNone, voidNone);
+    _notEqual(voidNone, dynamicNone);
+    _notEqual(voidNone, intNone);
+
+    _notEqual(voidNone, neverNone);
+    _notEqual(voidNone, neverQuestion);
+    _notEqual(voidNone, neverStar);
+  }
+
+  void _check(DartType T1, DartType T2, bool expected) {
+    bool result;
+
+    result = typeSystem.runtimeTypesEqual(T1, T2);
+    if (result != expected) {
+      fail('''
+Expected ${expected ? 'equal' : 'not equal'}.
+T1: ${_typeString(T1)}
+T2: ${_typeString(T2)}
+''');
+    }
+
+    result = typeSystem.runtimeTypesEqual(T2, T1);
+    if (result != expected) {
+      fail('''
+Expected ${expected ? 'equal' : 'not equal'}.
+T1: ${_typeString(T1)}
+T2: ${_typeString(T2)}
+''');
+    }
+  }
+
+  void _equal(DartType T1, DartType T2) {
+    _check(T1, T2, true);
+  }
+
+  void _notEqual(DartType T1, DartType T2) {
+    _check(T1, T2, false);
+  }
+
+  String _typeString(TypeImpl type) {
+    if (type == null) return null;
+    return type.getDisplayString(withNullability: true);
+  }
+}
diff --git a/pkg/analyzer/test/src/dart/element/test_all.dart b/pkg/analyzer/test/src/dart/element/test_all.dart
index 8c6df5f..3f89e34 100644
--- a/pkg/analyzer/test/src/dart/element/test_all.dart
+++ b/pkg/analyzer/test/src/dart/element/test_all.dart
@@ -11,6 +11,7 @@
 import 'normalize_type_test.dart' as normalize_type;
 import 'nullability_eliminator_test.dart' as nullability_eliminator;
 import 'nullable_test.dart' as nullable;
+import 'runtime_type_equality_test.dart' as runtime_type_equality;
 import 'subtype_test.dart' as subtype;
 import 'top_merge_test.dart' as top_merge;
 import 'type_algebra_test.dart' as type_algebra;
@@ -27,6 +28,7 @@
     normalize_type.main();
     nullability_eliminator.main();
     nullable.main();
+    runtime_type_equality.main();
     subtype.main();
     top_merge.main();
     type_algebra.main();
diff --git a/pkg/analyzer/test/src/dart/element/upper_lower_bound_test.dart b/pkg/analyzer/test/src/dart/element/upper_lower_bound_test.dart
index 78fd11a..b7a32e6 100644
--- a/pkg/analyzer/test/src/dart/element/upper_lower_bound_test.dart
+++ b/pkg/analyzer/test/src/dart/element/upper_lower_bound_test.dart
@@ -11,6 +11,7 @@
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_visitor.dart';
 import 'package:analyzer/src/generated/resolver.dart' show TypeSystemImpl;
+import 'package:analyzer/src/generated/type_system.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ -488,6 +489,7 @@
 
     // TOP(dynamic) is true
     isTop(dynamicNone);
+    isTop(UnknownInferredType.instance);
 
     // TOP(void) is true
     isTop(voidNone);
@@ -2226,5 +2228,8 @@
   }
 
   @override
+  void visitUnknownInferredType(UnknownInferredType type) {}
+
+  @override
   void visitVoidType(VoidType type) {}
 }
diff --git a/pkg/analyzer/test/src/dart/resolution/class_test.dart b/pkg/analyzer/test/src/dart/resolution/class_test.dart
index 72deb9d..953b08a 100644
--- a/pkg/analyzer/test/src/dart/resolution/class_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/class_test.dart
@@ -456,155 +456,6 @@
     expect(method.isStatic, isTrue);
   }
 
-  test_error_mismatchedGetterAndSetterTypes_class() async {
-    await assertErrorsInCode(r'''
-class C {
-  int get foo => 0;
-  set foo(String _) {}
-}
-''', [
-      error(StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES, 20, 3),
-    ]);
-  }
-
-  test_error_mismatchedGetterAndSetterTypes_interfaces() async {
-    await assertErrorsInCode(r'''
-class A {
-  int get foo {
-    return 0;
-  }
-}
-
-class B {
-  set foo(String _) {}
-}
-
-abstract class X implements A, B {}
-''', [
-      error(StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES, 98, 1),
-    ]);
-  }
-
-  test_error_mismatchedGetterAndSetterTypes_OK_private_getter() async {
-    newFile('/test/lib/a.dart', content: r'''
-class A {
-  int get _foo => 0;
-}
-''');
-    await assertErrorsInCode(r'''
-import 'a.dart';
-
-class B extends A {
-  set _foo(String _) {}
-}
-''', [
-      error(HintCode.UNUSED_ELEMENT, 44, 4),
-    ]);
-  }
-
-  test_error_mismatchedGetterAndSetterTypes_OK_private_interfaces() async {
-    newFile('/test/lib/a.dart', content: r'''
-class A {
-  int get _foo => 0;
-}
-''');
-    newFile('/test/lib/b.dart', content: r'''
-class B {
-  set _foo(String _) {}
-}
-''');
-    await assertNoErrorsInCode(r'''
-import 'a.dart';
-import 'b.dart';
-
-class X implements A, B {}
-''');
-  }
-
-  test_error_mismatchedGetterAndSetterTypes_OK_private_interfaces2() async {
-    newFile('/test/lib/a.dart', content: r'''
-class A {
-  int get _foo => 0;
-}
-
-class B {
-  set _foo(String _) {}
-}
-''');
-    await assertNoErrorsInCode(r'''
-import 'a.dart';
-
-class X implements A, B {}
-''');
-  }
-
-  test_error_mismatchedGetterAndSetterTypes_OK_private_setter() async {
-    newFile('/test/lib/a.dart', content: r'''
-class A {
-  set _foo(String _) {}
-}
-''');
-    await assertErrorsInCode(r'''
-import 'a.dart';
-
-class B extends A {
-  int get _foo => 0;
-}
-''', [
-      error(HintCode.UNUSED_ELEMENT, 48, 4),
-    ]);
-  }
-
-  test_error_mismatchedGetterAndSetterTypes_OK_setterParameter_0() async {
-    await assertErrorsInCode(r'''
-class C {
-  int get foo => 0;
-  set foo() {}
-}
-''', [
-      error(CompileTimeErrorCode.WRONG_NUMBER_OF_PARAMETERS_FOR_SETTER, 36, 3),
-    ]);
-  }
-
-  test_error_mismatchedGetterAndSetterTypes_OK_setterParameter_2() async {
-    await assertErrorsInCode(r'''
-class C {
-  int get foo => 0;
-  set foo(String p1, String p2) {}
-}
-''', [
-      error(CompileTimeErrorCode.WRONG_NUMBER_OF_PARAMETERS_FOR_SETTER, 36, 3),
-    ]);
-  }
-
-  test_error_mismatchedGetterAndSetterTypes_superGetter() async {
-    await assertErrorsInCode(r'''
-class A {
-  int get foo => 0;
-}
-
-class B extends A {
-  set foo(String _) {}
-}
-''', [
-      error(StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES, 59, 3),
-    ]);
-  }
-
-  test_error_mismatchedGetterAndSetterTypes_superSetter() async {
-    await assertErrorsInCode(r'''
-class A {
-  set foo(String _) {}
-}
-
-class B extends A {
-  int get foo => 0;
-}
-''', [
-      error(StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES, 66, 3),
-    ]);
-  }
-
   test_inconsistentInheritance_parameterType() async {
     await assertErrorsInCode(r'''
 abstract class A {
diff --git a/pkg/analyzer/test/src/dart/resolution/constant_test.dart b/pkg/analyzer/test/src/dart/resolution/constant_test.dart
index 396b5f0..510112c 100644
--- a/pkg/analyzer/test/src/dart/resolution/constant_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/constant_test.dart
@@ -3,8 +3,10 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/src/dart/analysis/experiments.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/error/codes.dart';
+import 'package:analyzer/src/generated/engine.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ -12,12 +14,13 @@
 
 main() {
   defineReflectiveSuite(() {
-    defineReflectiveTests(ConstantDriverTest);
+    defineReflectiveTests(ConstantResolutionTest);
+    defineReflectiveTests(ConstantResolutionWithNnbdTest);
   });
 }
 
 @reflectiveTest
-class ConstantDriverTest extends DriverResolutionTest {
+class ConstantResolutionTest extends DriverResolutionTest {
   test_constantValue_defaultParameter_noDefaultValue() async {
     newFile('/test/lib/a.dart', content: r'''
 class A {
@@ -79,6 +82,27 @@
     ]);
   }
 
+  test_context_eliminateTypeVariables() async {
+    await assertNoErrorsInCode(r'''
+class A<T> {
+  const A({List<T> a = const []});
+}
+''');
+    assertType(findNode.listLiteral('const []'), 'List<Null>');
+  }
+
+  test_context_eliminateTypeVariables_functionType() async {
+    await assertNoErrorsInCode(r'''
+class A<T, U> {
+  const A({List<T Function(U)> a = const []});
+}
+''');
+    assertType(
+      findNode.listLiteral('const []'),
+      'List<Null Function(Object)>',
+    );
+  }
+
   test_functionType_element_typeArguments() async {
     newFile('/test/lib/a.dart', content: r'''
 typedef F<T> = T Function(int);
@@ -177,3 +201,35 @@
     expect(a.computeConstantValue().toIntValue(), 42);
   }
 }
+
+@reflectiveTest
+class ConstantResolutionWithNnbdTest extends DriverResolutionTest {
+  @override
+  AnalysisOptionsImpl get analysisOptions => AnalysisOptionsImpl()
+    ..enabledExperiments = [EnableString.non_nullable]
+    ..implicitCasts = false;
+
+  @override
+  bool get typeToStringWithNullability => true;
+
+  test_context_eliminateTypeVariables() async {
+    await assertNoErrorsInCode(r'''
+class A<T> {
+  const A({List<T> a = const []});
+}
+''');
+    assertType(findNode.listLiteral('const []'), 'List<Never>');
+  }
+
+  test_context_eliminateTypeVariables_functionType() async {
+    await assertNoErrorsInCode(r'''
+class A<T, U> {
+  const A({List<T Function(U)> a = const []});
+}
+''');
+    assertType(
+      findNode.listLiteral('const []'),
+      'List<Never Function(Object?)>',
+    );
+  }
+}
diff --git a/pkg/analyzer/test/src/dart/resolution/method_invocation_test.dart b/pkg/analyzer/test/src/dart/resolution/method_invocation_test.dart
index 8bedd48..a195ee3 100644
--- a/pkg/analyzer/test/src/dart/resolution/method_invocation_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/method_invocation_test.dart
@@ -1699,6 +1699,32 @@
   AnalysisOptionsImpl get analysisOptions =>
       AnalysisOptionsImpl()..enabledExperiments = [EnableString.non_nullable];
 
+  test_hasReceiver_deferredImportPrefix_loadLibrary_optIn_fromOptOut() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {}
+''');
+
+    await assertNoErrorsInCode(r'''
+// @dart = 2.7
+import 'a.dart' deferred as a;
+
+main() {
+  a.loadLibrary();
+}
+''');
+
+    var import = findElement.importFind('package:test/a.dart');
+
+    var invocation = findNode.methodInvocation('loadLibrary()');
+    assertImportPrefix(invocation.target, import.prefix);
+
+    assertMethodInvocation(
+      invocation,
+      import.importedLibrary.loadLibraryFunction,
+      'Future<dynamic> Function()',
+    );
+  }
+
   test_hasReceiver_interfaceTypeQ_defined() async {
     await assertErrorsInCode(r'''
 class A {
diff --git a/pkg/analyzer/test/src/dart/resolution/postfix_expression_test.dart b/pkg/analyzer/test/src/dart/resolution/postfix_expression_test.dart
index fda3a9e..74fb1e9 100644
--- a/pkg/analyzer/test/src/dart/resolution/postfix_expression_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/postfix_expression_test.dart
@@ -53,9 +53,9 @@
 
   test_inc_property_differentTypes() async {
     await assertNoErrorsInCode(r'''
-dynamic get x => 0;
+int get x => 0;
 
-set x(Object _) {}
+set x(num _) {}
 
 f() {
   x++;
@@ -65,13 +65,16 @@
     assertSimpleIdentifier(
       findNode.simple('x++'),
       element: findElement.topSet('x'),
-      type: 'Object',
+      type: 'num',
     );
 
     assertPostfixExpression(
       findNode.postfix('x++'),
-      element: null,
-      type: 'dynamic',
+      element: elementMatcher(
+        numElement.getMethod('+'),
+        isLegacy: isNullSafetySdkAndLegacyLibrary,
+      ),
+      type: 'int',
     );
   }
 }
diff --git a/pkg/analyzer/test/src/dart/resolution/prefixed_identifier_test.dart b/pkg/analyzer/test/src/dart/resolution/prefixed_identifier_test.dart
index 8000e7e..a47b170 100644
--- a/pkg/analyzer/test/src/dart/resolution/prefixed_identifier_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/prefixed_identifier_test.dart
@@ -54,6 +54,32 @@
   @override
   bool get typeToStringWithNullability => true;
 
+  test_deferredImportPrefix_loadLibrary_optIn_fromOptOut() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {}
+''');
+
+    await assertNoErrorsInCode(r'''
+// @dart = 2.7
+import 'a.dart' deferred as a;
+
+main() {
+  a.loadLibrary;
+}
+''');
+
+    var import = findElement.importFind('package:test/a.dart');
+
+    assertPrefixedIdentifier(
+      findNode.prefixed('a.loadLibrary'),
+      element: elementMatcher(
+        import.importedLibrary.loadLibraryFunction,
+        isLegacy: true,
+      ),
+      type: 'Future<dynamic>* Function()*',
+    );
+  }
+
   test_implicitCall_tearOff_nullable() async {
     newFile('/test/lib/a.dart', content: r'''
 class A {
diff --git a/pkg/analyzer/test/src/dart/resolution/resolution.dart b/pkg/analyzer/test/src/dart/resolution/resolution.dart
index 368064b..459660e 100644
--- a/pkg/analyzer/test/src/dart/resolution/resolution.dart
+++ b/pkg/analyzer/test/src/dart/resolution/resolution.dart
@@ -502,6 +502,15 @@
     assertType(node, type);
   }
 
+  void assertPrefixedIdentifier(
+    PrefixedIdentifier node, {
+    @required Object element,
+    @required String type,
+  }) {
+    assertElement(node.staticElement, element);
+    assertType(node, type);
+  }
+
   void assertPrefixExpression(
     PrefixExpression node, {
     @required Object element,
diff --git a/pkg/analyzer/test/src/dart/resolution/type_inference/collection_elements_test.dart b/pkg/analyzer/test/src/dart/resolution/type_inference/collection_elements_test.dart
index ada9374..33f1c6b 100644
--- a/pkg/analyzer/test/src/dart/resolution/type_inference/collection_elements_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/type_inference/collection_elements_test.dart
@@ -35,7 +35,7 @@
 T a<T>() => throw '';
 ''');
     assertInvokeType(
-        findNode.methodInvocation('a('), 'Stream<dynamic> Function()');
+        findNode.methodInvocation('a('), 'Stream<Object?> Function()');
   }
 
   test_list_awaitForIn_int_downward() async {
@@ -69,7 +69,7 @@
 T a<T>() => throw '';
 ''');
     assertInvokeType(
-        findNode.methodInvocation('a('), 'Iterable<dynamic> Function()');
+        findNode.methodInvocation('a('), 'Iterable<Object?> Function()');
   }
 
   test_list_forIn_int_downward() async {
@@ -93,7 +93,7 @@
 T a<T>() => throw '';
 ''');
     assertInvokeType(
-        findNode.methodInvocation('a('), 'Stream<dynamic> Function()');
+        findNode.methodInvocation('a('), 'Stream<Object?> Function()');
   }
 
   test_map_awaitForIn_int_downward() async {
@@ -127,7 +127,7 @@
 T a<T>() => throw '';
 ''');
     assertInvokeType(
-        findNode.methodInvocation('a('), 'Iterable<dynamic> Function()');
+        findNode.methodInvocation('a('), 'Iterable<Object?> Function()');
   }
 
   test_map_forIn_int_downward() async {
@@ -151,7 +151,7 @@
 T a<T>() => throw '';
 ''');
     assertInvokeType(
-        findNode.methodInvocation('a('), 'Stream<dynamic> Function()');
+        findNode.methodInvocation('a('), 'Stream<Object?> Function()');
   }
 
   test_set_awaitForIn_int_downward() async {
@@ -185,7 +185,7 @@
 T a<T>() => throw '';
 ''');
     assertInvokeType(
-        findNode.methodInvocation('a('), 'Iterable<dynamic> Function()');
+        findNode.methodInvocation('a('), 'Iterable<Object?> Function()');
   }
 
   test_set_forIn_int_downward() async {
diff --git a/pkg/analyzer/test/src/dart/resolution/type_inference/statements_test.dart b/pkg/analyzer/test/src/dart/resolution/type_inference/statements_test.dart
index 5848d62..025800d 100644
--- a/pkg/analyzer/test/src/dart/resolution/type_inference/statements_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/type_inference/statements_test.dart
@@ -78,7 +78,7 @@
 T a<T>() => throw '';
 ''');
     assertInvokeType(
-        findNode.methodInvocation('a('), 'Stream<dynamic> Function()');
+        findNode.methodInvocation('a('), 'Stream<Object?> Function()');
   }
 
   test_awaitForIn_int_downward() async {
@@ -109,7 +109,7 @@
 T a<T>() => throw '';
 ''');
     assertInvokeType(
-        findNode.methodInvocation('a('), 'Iterable<dynamic> Function()');
+        findNode.methodInvocation('a('), 'Iterable<Object?> Function()');
   }
 
   test_forIn_int_downward() async {
diff --git a/pkg/analyzer/test/src/diagnostics/getter_not_assignable_setter_types_test.dart b/pkg/analyzer/test/src/diagnostics/getter_not_assignable_setter_types_test.dart
new file mode 100644
index 0000000..6bb253e
--- /dev/null
+++ b/pkg/analyzer/test/src/diagnostics/getter_not_assignable_setter_types_test.dart
@@ -0,0 +1,254 @@
+// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/src/error/codes.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../dart/resolution/driver_resolution.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(GetterNotAssignableSetterTypesTest);
+  });
+}
+
+@reflectiveTest
+class GetterNotAssignableSetterTypesTest extends DriverResolutionTest {
+  test_class_instance_dynamicGetter() async {
+    await assertNoErrorsInCode(r'''
+class C {
+  get foo => 0;
+  set foo(String v) {}
+}
+''');
+  }
+
+  test_class_instance_dynamicSetter() async {
+    await assertNoErrorsInCode(r'''
+class C {
+  int get foo => 0;
+  set foo(v) {}
+}
+''');
+  }
+
+  test_class_instance_interfaces() async {
+    await assertErrorsInCode(r'''
+class A {
+  int get foo => 0;
+}
+
+class B {
+  set foo(String _) {}
+}
+
+abstract class X implements A, B {}
+''', [
+      error(StaticWarningCode.GETTER_NOT_ASSIGNABLE_SETTER_TYPES, 84, 1),
+    ]);
+  }
+
+  test_class_instance_private_getter() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  int get _foo => 0;
+}
+''');
+    await assertErrorsInCode(r'''
+import 'a.dart';
+
+class B extends A {
+  set _foo(String _) {}
+}
+''', [
+      error(HintCode.UNUSED_ELEMENT, 44, 4),
+    ]);
+  }
+
+  test_class_instance_private_interfaces() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  int get _foo => 0;
+}
+''');
+    newFile('/test/lib/b.dart', content: r'''
+class B {
+  set _foo(String _) {}
+}
+''');
+    await assertNoErrorsInCode(r'''
+import 'a.dart';
+import 'b.dart';
+
+class X implements A, B {}
+''');
+  }
+
+  test_class_instance_private_interfaces2() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  int get _foo => 0;
+}
+
+class B {
+  set _foo(String _) {}
+}
+''');
+    await assertNoErrorsInCode(r'''
+import 'a.dart';
+
+class X implements A, B {}
+''');
+  }
+
+  test_class_instance_private_setter() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  set _foo(String _) {}
+}
+''');
+    await assertErrorsInCode(r'''
+import 'a.dart';
+
+class B extends A {
+  int get _foo => 0;
+}
+''', [
+      error(HintCode.UNUSED_ELEMENT, 48, 4),
+    ]);
+  }
+
+  test_class_instance_sameClass() async {
+    await assertErrorsInCode(r'''
+class C {
+  int get foo => 0;
+  set foo(String _) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_ASSIGNABLE_SETTER_TYPES, 20, 3),
+    ]);
+  }
+
+  test_class_instance_sameTypes() async {
+    await assertNoErrorsInCode(r'''
+class C {
+  int get foo => 0;
+  set foo(int v) {}
+}
+''');
+  }
+
+  test_class_instance_setterParameter_0() async {
+    await assertErrorsInCode(r'''
+class C {
+  int get foo => 0;
+  set foo() {}
+}
+''', [
+      error(CompileTimeErrorCode.WRONG_NUMBER_OF_PARAMETERS_FOR_SETTER, 36, 3),
+    ]);
+  }
+
+  test_class_instance_setterParameter_2() async {
+    await assertErrorsInCode(r'''
+class C {
+  int get foo => 0;
+  set foo(String p1, String p2) {}
+}
+''', [
+      error(CompileTimeErrorCode.WRONG_NUMBER_OF_PARAMETERS_FOR_SETTER, 36, 3),
+    ]);
+  }
+
+  test_class_instance_superGetter() async {
+    await assertErrorsInCode(r'''
+class A {
+  int get foo => 0;
+}
+
+class B extends A {
+  set foo(String _) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_ASSIGNABLE_SETTER_TYPES, 59, 3),
+    ]);
+  }
+
+  test_class_instance_superSetter() async {
+    await assertErrorsInCode(r'''
+class A {
+  set foo(String _) {}
+}
+
+class B extends A {
+  int get foo => 0;
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_ASSIGNABLE_SETTER_TYPES, 66, 3),
+    ]);
+  }
+
+  test_class_static() async {
+    await assertErrorsInCode(r'''
+class C {
+  static int get foo => 0;
+  static set foo(String _) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_ASSIGNABLE_SETTER_TYPES, 27, 3),
+    ]);
+  }
+
+  test_extension_instance() async {
+    await assertErrorsInCode('''
+extension E on Object {
+  int get foo { return 0; }
+  set foo(String v) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_ASSIGNABLE_SETTER_TYPES, 34, 3),
+    ]);
+  }
+
+  test_extension_static() async {
+    await assertErrorsInCode('''
+extension E on Object {
+  static int get foo { return 0; }
+  static set foo(String v) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_ASSIGNABLE_SETTER_TYPES, 41, 3),
+    ]);
+  }
+
+  test_topLevel() async {
+    await assertErrorsInCode('''
+int get foo { return 0; }
+set foo(String v) {}
+''', [
+      error(StaticWarningCode.GETTER_NOT_ASSIGNABLE_SETTER_TYPES, 8, 3),
+    ]);
+  }
+
+  test_topLevel_dynamicGetter() async {
+    await assertNoErrorsInCode(r'''
+get foo => 0;
+set foo(String v) {}
+''');
+  }
+
+  test_topLevel_dynamicSetter() async {
+    await assertNoErrorsInCode(r'''
+int get foo => 0;
+set foo(v) {}
+''');
+  }
+
+  test_topLevel_sameTypes() async {
+    await assertNoErrorsInCode(r'''
+int get foo => 0;
+set foo(int v) {}
+''');
+  }
+}
diff --git a/pkg/analyzer/test/src/diagnostics/getter_not_subtype_setter_types_test.dart b/pkg/analyzer/test/src/diagnostics/getter_not_subtype_setter_types_test.dart
new file mode 100644
index 0000000..8cbbe24
--- /dev/null
+++ b/pkg/analyzer/test/src/diagnostics/getter_not_subtype_setter_types_test.dart
@@ -0,0 +1,279 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/dart/analysis/features.dart';
+import 'package:analyzer/src/error/codes.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../dart/resolution/driver_resolution.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(GetterNotSubtypeSetterTypesTest);
+  });
+}
+
+@reflectiveTest
+class GetterNotSubtypeSetterTypesTest extends DriverResolutionTest {
+  @override
+  AnalysisOptionsImpl get analysisOptions => AnalysisOptionsImpl()
+    ..contextFeatures = FeatureSet.forTesting(
+        sdkVersion: '2.7.0', additionalFeatures: [Feature.non_nullable]);
+
+  @override
+  bool get typeToStringWithNullability => true;
+
+  test_class_instance() async {
+    await assertErrorsInCode('''
+class C {
+  num get foo => 0;
+  set foo(int v) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 20, 3),
+    ]);
+  }
+
+  test_class_instance_dynamicGetter() async {
+    await assertErrorsInCode(r'''
+class C {
+  get foo => 0;
+  set foo(String v) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 16, 3),
+    ]);
+  }
+
+  test_class_instance_dynamicSetter() async {
+    await assertNoErrorsInCode(r'''
+class C {
+  int get foo => 0;
+  set foo(v) {}
+}
+''');
+  }
+
+  test_class_instance_interfaces() async {
+    await assertErrorsInCode(r'''
+class A {
+  int get foo => 0;
+}
+
+class B {
+  set foo(String _) {}
+}
+
+abstract class X implements A, B {}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 84, 1),
+    ]);
+  }
+
+  test_class_instance_private_getter() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  int get _foo => 0;
+}
+''');
+    await assertErrorsInCode(r'''
+import 'a.dart';
+
+class B extends A {
+  set _foo(String _) {}
+}
+''', [
+      error(HintCode.UNUSED_ELEMENT, 44, 4),
+    ]);
+  }
+
+  test_class_instance_private_interfaces() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  int get _foo => 0;
+}
+''');
+    newFile('/test/lib/b.dart', content: r'''
+class B {
+  set _foo(String _) {}
+}
+''');
+    await assertNoErrorsInCode(r'''
+import 'a.dart';
+import 'b.dart';
+
+class X implements A, B {}
+''');
+  }
+
+  test_class_instance_private_interfaces2() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  int get _foo => 0;
+}
+
+class B {
+  set _foo(String _) {}
+}
+''');
+    await assertNoErrorsInCode(r'''
+import 'a.dart';
+
+class X implements A, B {}
+''');
+  }
+
+  test_class_instance_private_setter() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  set _foo(String _) {}
+}
+''');
+    await assertErrorsInCode(r'''
+import 'a.dart';
+
+class B extends A {
+  int get _foo => 0;
+}
+''', [
+      error(HintCode.UNUSED_ELEMENT, 48, 4),
+    ]);
+  }
+
+  test_class_instance_sameClass() async {
+    await assertErrorsInCode(r'''
+class C {
+  int get foo => 0;
+  set foo(String _) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 20, 3),
+    ]);
+  }
+
+  test_class_instance_sameTypes() async {
+    await assertNoErrorsInCode(r'''
+class C {
+  int get foo => 0;
+  set foo(int v) {}
+}
+''');
+  }
+
+  test_class_instance_setterParameter_0() async {
+    await assertErrorsInCode(r'''
+class C {
+  int get foo => 0;
+  set foo() {}
+}
+''', [
+      error(CompileTimeErrorCode.WRONG_NUMBER_OF_PARAMETERS_FOR_SETTER, 36, 3),
+    ]);
+  }
+
+  test_class_instance_setterParameter_2() async {
+    await assertErrorsInCode(r'''
+class C {
+  int get foo => 0;
+  set foo(String p1, String p2) {}
+}
+''', [
+      error(CompileTimeErrorCode.WRONG_NUMBER_OF_PARAMETERS_FOR_SETTER, 36, 3),
+    ]);
+  }
+
+  test_class_instance_superGetter() async {
+    await assertErrorsInCode(r'''
+class A {
+  int get foo => 0;
+}
+
+class B extends A {
+  set foo(String _) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 59, 3),
+    ]);
+  }
+
+  test_class_instance_superSetter() async {
+    await assertErrorsInCode(r'''
+class A {
+  set foo(String _) {}
+}
+
+class B extends A {
+  int get foo => 0;
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 66, 3),
+    ]);
+  }
+
+  test_class_static() async {
+    await assertErrorsInCode('''
+class C {
+  static num get foo => 0;
+  static set foo(int v) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 27, 3),
+    ]);
+  }
+
+  test_extension_instance() async {
+    await assertErrorsInCode('''
+extension E on Object {
+  int get foo => 0;
+  set foo(String v) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 34, 3),
+    ]);
+  }
+
+  test_extension_static() async {
+    await assertErrorsInCode('''
+extension E on Object {
+  static int get foo => 0;
+  static set foo(String v) {}
+}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 41, 3),
+    ]);
+  }
+
+  test_topLevel() async {
+    await assertErrorsInCode('''
+int get foo => 0;
+set foo(String v) {}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 8, 3),
+    ]);
+  }
+
+  test_topLevel_dynamicGetter() async {
+    await assertErrorsInCode(r'''
+get foo => 0;
+set foo(int v) {}
+''', [
+      error(StaticWarningCode.GETTER_NOT_SUBTYPE_SETTER_TYPES, 4, 3),
+    ]);
+  }
+
+  test_topLevel_dynamicSetter() async {
+    await assertNoErrorsInCode(r'''
+int get foo => 0;
+set foo(v) {}
+''');
+  }
+
+  test_topLevel_sameTypes() async {
+    await assertNoErrorsInCode(r'''
+int get foo => 0;
+set foo(int v) {}
+''');
+  }
+}
diff --git a/pkg/analyzer/test/src/diagnostics/invalid_assignment_test.dart b/pkg/analyzer/test/src/diagnostics/invalid_assignment_test.dart
index 85628c7..d9209a9 100644
--- a/pkg/analyzer/test/src/diagnostics/invalid_assignment_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/invalid_assignment_test.dart
@@ -23,20 +23,6 @@
     ..contextFeatures = FeatureSet.forTesting(
         sdkVersion: '2.7.0', additionalFeatures: [Feature.non_nullable]);
 
-  @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/38200')
-  test_defaultValue_list_inferredTypeVariable() async {
-    // We have a test somewhere that verifies that we infer `<Null>` type
-    // arguments in constant contexts, probably somewhere in
-    // `ResynthesizeTestCases`. We need a similar test nearby for NNBD enabled.
-    await assertNoErrorsInCode('''
-class Vector<T> {
-  bool contains([List<T> elements = const []]) {
-    return true;
-  }
-}
-''');
-  }
-
   @override
   test_ifNullAssignment_sameType() async {
     // This test is overridden solely to make [j] nullable.
diff --git a/pkg/analyzer/test/src/diagnostics/invalid_override_test.dart b/pkg/analyzer/test/src/diagnostics/invalid_override_test.dart
index 8ca6262..aad1f2d 100644
--- a/pkg/analyzer/test/src/diagnostics/invalid_override_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/invalid_override_test.dart
@@ -92,6 +92,34 @@
     ]);
   }
 
+  test_method_covariant_1() async {
+    await assertNoErrorsInCode(r'''
+abstract class A<T> {
+  A<U> foo<U>(covariant A<Map<T, U>> a);
+}
+
+abstract class B<U, T> extends A<T> {
+  B<U, V> foo<V>(B<U, Map<T, V>> a);
+}
+''');
+  }
+
+  test_method_covariant_2() async {
+    await assertNoErrorsInCode(r'''
+abstract class A {
+  R foo<R>(VA<R> v);
+}
+
+abstract class B implements A {
+  R foo<R>(covariant VB<R> v);
+}
+
+abstract class VA<T> {}
+
+abstract class VB<T> implements VA<T> {}
+''');
+  }
+
   test_method_named_fewerNamedParameters() async {
     await assertErrorsInCode('''
 class A {
diff --git a/pkg/analyzer/test/src/diagnostics/mismatched_getter_and_setter_types_test.dart b/pkg/analyzer/test/src/diagnostics/mismatched_getter_and_setter_types_test.dart
deleted file mode 100644
index 1bf2690..0000000
--- a/pkg/analyzer/test/src/diagnostics/mismatched_getter_and_setter_types_test.dart
+++ /dev/null
@@ -1,141 +0,0 @@
-// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-import 'package:analyzer/dart/analysis/features.dart';
-import 'package:analyzer/src/error/codes.dart';
-import 'package:analyzer/src/generated/engine.dart';
-import 'package:test_reflective_loader/test_reflective_loader.dart';
-
-import '../dart/resolution/driver_resolution.dart';
-
-main() {
-  defineReflectiveSuite(() {
-    defineReflectiveTests(MismatchedGetterAndSetterTypesTest);
-    defineReflectiveTests(
-        MismatchedGetterAndSetterTypesWithExtensionMethodsTest);
-    defineReflectiveTests(MismatchedGetterAndSetterTypesWithNNBDTest);
-  });
-}
-
-@reflectiveTest
-class MismatchedGetterAndSetterTypesTest extends DriverResolutionTest {
-  test_topLevel() async {
-    await assertErrorsInCode('''
-int get g { return 0; }
-set g(String v) {}''', [
-      error(StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES, 0, 23),
-    ]);
-  }
-
-  test_instance_sameTypes() async {
-    await assertNoErrorsInCode(r'''
-class C {
-  int get x => 0;
-  set x(int v) {}
-}
-''');
-  }
-
-  test_instance_unspecifiedGetter() async {
-    await assertNoErrorsInCode(r'''
-class C {
-  get x => 0;
-  set x(String v) {}
-}
-''');
-  }
-
-  test_instance_unspecifiedSetter() async {
-    await assertNoErrorsInCode(r'''
-class C {
-  int get x => 0;
-  set x(v) {}
-}
-''');
-  }
-
-  test_topLevel_sameTypes() async {
-    await assertNoErrorsInCode(r'''
-int get x => 0;
-set x(int v) {}
-''');
-  }
-
-  test_topLevel_unspecifiedGetter() async {
-    await assertNoErrorsInCode(r'''
-get x => 0;
-set x(String v) {}
-''');
-  }
-
-  test_topLevel_unspecifiedSetter() async {
-    await assertNoErrorsInCode(r'''
-int get x => 0;
-set x(v) {}
-''');
-  }
-}
-
-@reflectiveTest
-class MismatchedGetterAndSetterTypesWithExtensionMethodsTest
-    extends MismatchedGetterAndSetterTypesTest {
-  @override
-  AnalysisOptionsImpl get analysisOptions => AnalysisOptionsImpl()
-    ..contextFeatures = FeatureSet.forTesting(
-        sdkVersion: '2.3.0', additionalFeatures: [Feature.extension_methods]);
-
-  test_extensionMembers_instance() async {
-    await assertErrorsInCode('''
-extension E on Object {
-  int get g { return 0; }
-  set g(String v) {}
-}
-''', [
-      error(StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES, 34, 1),
-    ]);
-  }
-
-  test_extensionMembers_static() async {
-    await assertErrorsInCode('''
-extension E on Object {
-  static int get g { return 0; }
-  static set g(String v) {}
-}
-''', [
-      error(StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES, 41, 1),
-    ]);
-  }
-}
-
-@reflectiveTest
-class MismatchedGetterAndSetterTypesWithNNBDTest
-    extends MismatchedGetterAndSetterTypesTest {
-  @override
-  AnalysisOptionsImpl get analysisOptions => AnalysisOptionsImpl()
-    ..contextFeatures = FeatureSet.forTesting(
-        sdkVersion: '2.3.0', additionalFeatures: [Feature.non_nullable]);
-
-  test_classMembers_instance() async {
-    await assertErrorsInCode('''
-class C {
-  num get g { return 0; }
-  set g(int v) {}
-}
-''', [
-      error(StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES, 20, 1),
-    ]);
-  }
-
-  @failingTest
-  test_classMembers_static() async {
-    await assertErrorsInCode('''
-class C {
-  static num get g { return 0; }
-  static set g(int v) {}
-}
-''', [
-      error(StaticWarningCode.MISMATCHED_GETTER_AND_SETTER_TYPES, 12, 30),
-    ]);
-  }
-}
diff --git a/pkg/analyzer/test/src/diagnostics/test_all.dart b/pkg/analyzer/test/src/diagnostics/test_all.dart
index 14347e0..5879733 100644
--- a/pkg/analyzer/test/src/diagnostics/test_all.dart
+++ b/pkg/analyzer/test/src/diagnostics/test_all.dart
@@ -139,6 +139,10 @@
 import 'for_in_of_invalid_type_test.dart' as for_in_of_invalid_type;
 import 'for_in_with_const_variable_test.dart' as for_in_with_const_variable;
 import 'generic_struct_subclass_test.dart' as generic_struct_subclass;
+import 'getter_not_assignable_setter_types_test.dart'
+    as getter_not_assignable_setter_types;
+import 'getter_not_subtype_setter_types_test.dart'
+    as getter_not_subtype_setter_types;
 import 'if_element_condition_from_deferred_library_test.dart'
     as if_element_condition_from_deferred_library;
 import 'illegal_async_return_type_test.dart' as illegal_async_return_type;
@@ -239,8 +243,6 @@
 import 'member_with_class_name_test.dart' as member_with_class_name;
 import 'mismatched_annotation_on_struct_field_test.dart'
     as mismatched_annotation_on_struct_field;
-import 'mismatched_getter_and_setter_types_test.dart'
-    as mismatched_getter_and_setter_types;
 import 'missing_annotation_on_struct_field_test.dart'
     as missing_annotation_on_struct_field;
 import 'missing_default_value_for_parameter_test.dart'
@@ -435,6 +437,7 @@
     as undefined_constructor_in_initializer_default;
 import 'undefined_constructor_in_initializer_test.dart'
     as undefined_constructor_in_initializer;
+import 'undefined_enum_constant_test.dart' as undefined_enum_constant;
 import 'undefined_extension_getter_test.dart' as undefined_extension_getter;
 import 'undefined_extension_method_test.dart' as undefined_extension_method;
 import 'undefined_extension_operator_test.dart' as undefined_extension_operator;
@@ -576,6 +579,8 @@
     for_in_of_invalid_type.main();
     for_in_with_const_variable.main();
     generic_struct_subclass.main();
+    getter_not_assignable_setter_types.main();
+    getter_not_subtype_setter_types.main();
     if_element_condition_from_deferred_library.main();
     illegal_async_return_type.main();
     implements_disallowed_class.main();
@@ -643,7 +648,6 @@
     map_value_type_not_assignable.main();
     member_with_class_name.main();
     mismatched_annotation_on_struct_field.main();
-    mismatched_getter_and_setter_types.main();
     missing_annotation_on_struct_field.main();
     missing_default_value_for_parameter.main();
     missing_enum_value_in_switch.main();
@@ -775,6 +779,7 @@
     undefined_class.main();
     undefined_constructor_in_initializer_default.main();
     undefined_constructor_in_initializer.main();
+    undefined_enum_constant.main();
     undefined_extension_getter.main();
     undefined_extension_method.main();
     undefined_extension_operator.main();
diff --git a/pkg/analyzer/test/src/diagnostics/unchecked_use_of_nullable_value_test.dart b/pkg/analyzer/test/src/diagnostics/unchecked_use_of_nullable_value_test.dart
index 26be039..ee9d7e7 100644
--- a/pkg/analyzer/test/src/diagnostics/unchecked_use_of_nullable_value_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/unchecked_use_of_nullable_value_test.dart
@@ -874,6 +874,34 @@
 ''');
   }
 
+  test_nullable_dotQ_propertyAccess_dot_methodInvocation() async {
+    await assertNoErrorsInCode(r'''
+class A {
+  int get foo => 0;
+}
+
+void f(A? a) {
+  a?.foo.abs();
+}
+''');
+    assertType(findNode.propertyAccess('.foo'), 'int');
+    assertType(findNode.methodInvocation('.abs()'), 'int?');
+  }
+
+  test_nullable_dotQ_propertyAccess_dot_propertyAccess() async {
+    await assertNoErrorsInCode(r'''
+class A {
+  int get foo => 0;
+}
+
+void f(A? a) {
+  a?.foo.isEven;
+}
+''');
+    assertType(findNode.propertyAccess('.foo'), 'int');
+    assertType(findNode.propertyAccess('.isEven'), 'bool?');
+  }
+
   test_operatorMinus_nonNullable() async {
     await assertNoErrorsInCode(r'''
 m() {
diff --git a/pkg/analyzer/test/src/diagnostics/undefined_enum_constant_test.dart b/pkg/analyzer/test/src/diagnostics/undefined_enum_constant_test.dart
new file mode 100644
index 0000000..1d6ca2b
--- /dev/null
+++ b/pkg/analyzer/test/src/diagnostics/undefined_enum_constant_test.dart
@@ -0,0 +1,37 @@
+// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/src/error/codes.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../dart/resolution/driver_resolution.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(UndefinedEnumConstantTest);
+  });
+}
+
+@reflectiveTest
+class UndefinedEnumConstantTest extends DriverResolutionTest {
+  test_defined() async {
+    await assertNoErrorsInCode(r'''
+enum E { ONE }
+E e() {
+  return E.ONE;
+}
+''');
+  }
+
+  test_undefined() async {
+    await assertErrorsInCode(r'''
+enum E { ONE }
+E e() {
+  return E.TWO;
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_ENUM_CONSTANT, 34, 3),
+    ]);
+  }
+}
diff --git a/pkg/analyzer/test/src/diagnostics/undefined_getter_test.dart b/pkg/analyzer/test/src/diagnostics/undefined_getter_test.dart
index 177bd1f..6a77a6a 100644
--- a/pkg/analyzer/test/src/diagnostics/undefined_getter_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/undefined_getter_test.dart
@@ -142,6 +142,16 @@
     ]);
   }
 
+  test_instance_undefined_mixin() async {
+    await assertErrorsInCode(r'''
+mixin M {
+  f() { return this.m; }
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_GETTER, 30, 1),
+    ]);
+  }
+
   test_nullMember_undefined() async {
     await assertErrorsInCode(r'''
 m() {
diff --git a/pkg/analyzer/test/src/diagnostics/undefined_method_test.dart b/pkg/analyzer/test/src/diagnostics/undefined_method_test.dart
index 97943ad..b399b33 100644
--- a/pkg/analyzer/test/src/diagnostics/undefined_method_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/undefined_method_test.dart
@@ -68,6 +68,60 @@
     ]);
   }
 
+  test_method_undefined() async {
+    await assertErrorsInCode(r'''
+class C {
+  f() {
+    abs();
+  }
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_METHOD, 22, 3),
+    ]);
+  }
+
+  test_method_undefined_cascade() async {
+    await assertErrorsInCode(r'''
+class C {}
+f(C c) {
+  c..abs();
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_METHOD, 25, 3),
+    ]);
+  }
+
+  test_method_undefined_enum() async {
+    await assertErrorsInCode(r'''
+enum E { A }
+f() => E.abs();
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_METHOD, 22, 3),
+    ]);
+  }
+
+  test_method_undefined_mixin_cascade() async {
+    await assertErrorsInCode(r'''
+mixin M {}
+f(M m) {
+  m..abs();
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_METHOD, 25, 3),
+    ]);
+  }
+
+  test_method_undefined_mixin() async {
+    await assertErrorsInCode(r'''
+mixin M {}
+f(M m) {
+  m.abs();
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_METHOD, 24, 3),
+    ]);
+  }
+
   test_method_undefined_onNull() async {
     await assertErrorsInCode(r'''
 Null f(int x) => null;
diff --git a/pkg/analyzer/test/src/diagnostics/undefined_operator_test.dart b/pkg/analyzer/test/src/diagnostics/undefined_operator_test.dart
index 02ea237..6ca4c67 100644
--- a/pkg/analyzer/test/src/diagnostics/undefined_operator_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/undefined_operator_test.dart
@@ -45,6 +45,15 @@
     ]);
   }
 
+  test_binaryExpression_enum() async {
+    await assertErrorsInCode(r'''
+enum E { A }
+f(E e) => e + 1;
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_OPERATOR, 25, 1),
+    ]);
+  }
+
   test_binaryExpression_inSubtype() async {
     await assertErrorsInCode(r'''
 class A {}
@@ -61,6 +70,15 @@
     ]);
   }
 
+  test_binaryExpression_mixin() async {
+    await assertErrorsInCode(r'''
+mixin M {}
+f(M m) => m + 1;
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_OPERATOR, 23, 1),
+    ]);
+  }
+
   test_index_both() async {
     await assertErrorsInCode(r'''
 class A {}
@@ -87,6 +105,17 @@
 ''');
   }
 
+  test_index_enum() async {
+    await assertErrorsInCode(r'''
+enum E { A }
+f(E e) {
+  e[0];
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_OPERATOR, 25, 3),
+    ]);
+  }
+
   test_index_getter() async {
     await assertErrorsInCode(r'''
 class A {}
@@ -99,6 +128,17 @@
     ]);
   }
 
+  test_index_mixin() async {
+    await assertErrorsInCode(r'''
+mixin M {}
+f(M m) {
+  m[0];
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_OPERATOR, 23, 3),
+    ]);
+  }
+
   test_index_null() async {
     await assertErrorsInCode(r'''
 f(Null x) {
@@ -249,6 +289,17 @@
 ''');
   }
 
+  test_postfixExpression_mixin() async {
+    await assertErrorsInCode(r'''
+mixin M {}
+f(M m) {
+  m++;
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_OPERATOR, 23, 2),
+    ]);
+  }
+
   test_postfixExpression_undefined() async {
     await assertErrorsInCode(r'''
 class A {}
@@ -309,6 +360,17 @@
 ''');
   }
 
+  test_prefixExpression_mixin() async {
+    await assertErrorsInCode(r'''
+mixin M {}
+f(M m) {
+  -m;
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_OPERATOR, 22, 1),
+    ]);
+  }
+
   test_prefixExpression_undefined() async {
     await assertErrorsInCode(r'''
 class A {}
diff --git a/pkg/analyzer/test/src/diagnostics/undefined_setter_test.dart b/pkg/analyzer/test/src/diagnostics/undefined_setter_test.dart
index 38e017a..9179738 100644
--- a/pkg/analyzer/test/src/diagnostics/undefined_setter_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/undefined_setter_test.dart
@@ -40,6 +40,16 @@
     ]);
   }
 
+  test_instance_undefined_mixin() async {
+    await assertErrorsInCode(r'''
+mixin M {
+  f() { this.m = 0; }
+}
+''', [
+      error(StaticTypeWarningCode.UNDEFINED_SETTER, 23, 1),
+    ]);
+  }
+
   test_inSubtype() async {
     await assertErrorsInCode(r'''
 class A {}
diff --git a/pkg/analyzer/test/src/lint/pub_test.dart b/pkg/analyzer/test/src/lint/pub_test.dart
index 3224300..da528d9 100644
--- a/pkg/analyzer/test/src/lint/pub_test.dart
+++ b/pkg/analyzer/test/src/lint/pub_test.dart
@@ -36,6 +36,8 @@
       url: git://github.com/munificent/kittens.git
       ref: some-branch
   foo: any
+  relative_path:
+    path: ../somewhere
 dev_dependencies:
   markdown: '>=0.7.1+2 <0.8.0'
   unittest: '>=0.11.0 <0.12.0'
@@ -89,6 +91,13 @@
         {'foo': '1.2.0'}
       ]);
 
+      group('path', () {
+        PSDependency dep =
+            findDependency(ps.dependencies, name: 'relative_path');
+        PSEntry depPath = dep.path;
+        testValue('path', depPath, equals('../somewhere'));
+      });
+
       group('hosted', () {
         PSDependency dep =
             findDependency(ps.dependencies, name: 'transmogrify');
diff --git a/pkg/analyzer/test/src/summary/resynthesize_common.dart b/pkg/analyzer/test/src/summary/resynthesize_common.dart
index 41522fd..dd8c042 100644
--- a/pkg/analyzer/test/src/summary/resynthesize_common.dart
+++ b/pkg/analyzer/test/src/summary/resynthesize_common.dart
@@ -4954,6 +4954,39 @@
 ''');
   }
 
+  test_defaultValue_eliminateTypeParameters() async {
+    featureSet = enableNnbd;
+    var library = await checkLibrary('''
+class A<T> {
+  const X({List<T> a = const []});
+}
+''');
+    checkElementText(
+        library,
+        r'''
+class A<T> {
+  dynamic X({List<T> a: const /*typeArgs=Never*/[]});
+}
+''',
+        withTypes: true);
+  }
+
+  test_defaultValue_eliminateTypeParameters_legacy() async {
+    var library = await checkLibrary('''
+class A<T> {
+  const X({List<T> a = const []});
+}
+''');
+    checkElementText(
+        library,
+        r'''
+class A<T> {
+  dynamic X({List<T> a: const /*typeArgs=Null*/[]});
+}
+''',
+        withTypes: true);
+  }
+
   test_defaultValue_genericFunction() async {
     var library = await checkLibrary('''
 typedef void F<T>(T v);
diff --git a/pkg/analyzer/test/src/task/strong/checker_test.dart b/pkg/analyzer/test/src/task/strong/checker_test.dart
index 8141c33..6d96e8d 100644
--- a/pkg/analyzer/test/src/task/strong/checker_test.dart
+++ b/pkg/analyzer/test/src/task/strong/checker_test.dart
@@ -2586,17 +2586,17 @@
 }
 
 class T1 extends Base {
-  B get /*error:INVALID_OVERRIDE, error:MISMATCHED_GETTER_AND_SETTER_TYPES*/f => null;
+  B get /*error:INVALID_OVERRIDE, error:GETTER_NOT_ASSIGNABLE_SETTER_TYPES*/f => null;
 }
 
 class T2 extends Base {
-  set /*error:INVALID_OVERRIDE, error:MISMATCHED_GETTER_AND_SETTER_TYPES*/f(
+  set /*error:INVALID_OVERRIDE, error:GETTER_NOT_ASSIGNABLE_SETTER_TYPES*/f(
       B b) => null;
 }
 
 class T3 extends Base {
   final B
-      /*error:FINAL_NOT_INITIALIZED, error:INVALID_OVERRIDE, error:MISMATCHED_GETTER_AND_SETTER_TYPES*/f;
+      /*error:FINAL_NOT_INITIALIZED, error:INVALID_OVERRIDE, error:GETTER_NOT_ASSIGNABLE_SETTER_TYPES*/f;
 }
 class T4 extends Base {
   // two: one for the getter one for the setter.
@@ -2604,15 +2604,15 @@
 }
 
 class /*error:NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER*/T5 implements Base {
-  /**/B get /*error:INVALID_OVERRIDE, error:MISMATCHED_GETTER_AND_SETTER_TYPES*/f => null;
+  /**/B get /*error:INVALID_OVERRIDE, error:GETTER_NOT_ASSIGNABLE_SETTER_TYPES*/f => null;
 }
 
 class /*error:NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER*/T6 implements Base {
-  set /*error:INVALID_OVERRIDE, error:MISMATCHED_GETTER_AND_SETTER_TYPES*/f(B b) => null;
+  set /*error:INVALID_OVERRIDE, error:GETTER_NOT_ASSIGNABLE_SETTER_TYPES*/f(B b) => null;
 }
 
 class /*error:NON_ABSTRACT_CLASS_INHERITS_ABSTRACT_MEMBER*/T7 implements Base {
-  final B /*error:INVALID_OVERRIDE, error:MISMATCHED_GETTER_AND_SETTER_TYPES*/f = null;
+  final B /*error:INVALID_OVERRIDE, error:GETTER_NOT_ASSIGNABLE_SETTER_TYPES*/f = null;
 }
 class T8 implements Base {
   // two: one for the getter one for the setter.
diff --git a/pkg/analyzer/tool/diagnostics/diagnostics.md b/pkg/analyzer/tool/diagnostics/diagnostics.md
index 04c9f2d..dd2c150 100644
--- a/pkg/analyzer/tool/diagnostics/diagnostics.md
+++ b/pkg/analyzer/tool/diagnostics/diagnostics.md
@@ -5822,7 +5822,7 @@
 
 ### undefined_getter
 
-_The getter '{0}' isn't defined for the class '{1}'._
+_The getter '{0}' isn't defined for the type '{1}'._
 
 #### Description
 
@@ -5914,7 +5914,7 @@
 
 ### undefined_method
 
-_The method '{0}' isn't defined for the class '{1}'._
+_The method '{0}' isn't defined for the type '{1}'._
 
 #### Description
 
@@ -6012,7 +6012,7 @@
 
 ### undefined_operator
 
-_The operator '{0}' isn't defined for the class '{1}'._
+_The operator '{0}' isn't defined for the type '{1}'._
 
 #### Description
 
@@ -6076,7 +6076,7 @@
 
 ### undefined_setter
 
-_The setter '{0}' isn't defined for the class '{1}'._
+_The setter '{0}' isn't defined for the type '{1}'._
 
 #### Description
 
diff --git a/pkg/compiler/lib/src/common/codegen.dart b/pkg/compiler/lib/src/common/codegen.dart
index e302fd1..992fbe3 100644
--- a/pkg/compiler/lib/src/common/codegen.dart
+++ b/pkg/compiler/lib/src/common/codegen.dart
@@ -958,7 +958,7 @@
     StringBuffer sb = new StringBuffer();
     sb.write('ModularExpression(kind=$kind,data=');
     if (data is ConstantValue) {
-      sb.write((data as ConstantValue).toStructuredText());
+      sb.write((data as ConstantValue).toStructuredText(null));
     } else {
       sb.write(data);
     }
diff --git a/pkg/compiler/lib/src/common_elements.dart b/pkg/compiler/lib/src/common_elements.dart
index ca2c98e..9ddd6dd 100644
--- a/pkg/compiler/lib/src/common_elements.dart
+++ b/pkg/compiler/lib/src/common_elements.dart
@@ -20,6 +20,8 @@
 
 /// The common elements and types in Dart.
 abstract class CommonElements {
+  DartTypes get dartTypes;
+
   /// The `Object` class defined in 'dart:core'.
   ClassEntity get objectClass;
 
@@ -658,10 +660,12 @@
 
 class CommonElementsImpl
     implements CommonElements, KCommonElements, JCommonElements {
+  @override
+  final DartTypes dartTypes;
   final ElementEnvironment _env;
   final CompilerOptions _options;
 
-  CommonElementsImpl(this._env, this._options);
+  CommonElementsImpl(this.dartTypes, this._env, this._options);
 
   ClassEntity _objectClass;
   @override
@@ -1025,7 +1029,7 @@
 
   @override
   InterfaceType getConstantListTypeFor(InterfaceType sourceType) =>
-      sourceType.treatAsRaw
+      dartTypes.treatAsRawType(sourceType)
           ? _env.getRawType(jsArrayClass)
           : _env.createInterfaceType(jsArrayClass, sourceType.typeArguments);
 
@@ -1036,7 +1040,7 @@
         ? (hasProtoKey ? constantProtoMapClass : constantStringMapClass)
         : generalConstantMapClass;
     List<DartType> typeArgument = sourceType.typeArguments;
-    if (sourceType.treatAsRaw) {
+    if (dartTypes.treatAsRawType(sourceType)) {
       return _env.getRawType(classElement);
     } else {
       return _env.createInterfaceType(classElement, typeArgument);
@@ -1045,7 +1049,7 @@
 
   @override
   InterfaceType getConstantSetTypeFor(InterfaceType sourceType) =>
-      sourceType.treatAsRaw
+      dartTypes.treatAsRawType(sourceType)
           ? _env.getRawType(constSetLiteralClass)
           : _env.createInterfaceType(
               constSetLiteralClass, sourceType.typeArguments);
diff --git a/pkg/compiler/lib/src/constants/constant_system.dart b/pkg/compiler/lib/src/constants/constant_system.dart
index 566c2b9..afbb8f4 100644
--- a/pkg/compiler/lib/src/constants/constant_system.dart
+++ b/pkg/compiler/lib/src/constants/constant_system.dart
@@ -173,7 +173,7 @@
 
   bool hasProtoKey = (protoValue != null);
   InterfaceType keysType;
-  if (sourceType.treatAsRaw) {
+  if (commonElements.dartTypes.treatAsRawType(sourceType)) {
     keysType = commonElements.listType();
   } else {
     keysType = commonElements.listType(sourceType.typeArguments.first);
diff --git a/pkg/compiler/lib/src/constants/values.dart b/pkg/compiler/lib/src/constants/values.dart
index 67b4c3f..76c3302 100644
--- a/pkg/compiler/lib/src/constants/values.dart
+++ b/pkg/compiler/lib/src/constants/values.dart
@@ -114,10 +114,10 @@
   /// For the synthetic constants, [DeferredConstantValue],
   /// [DeferredGlobalConstantValue], [SyntheticConstantValue],
   /// [InterceptorConstantValue] the unparse is descriptive only.
-  String toDartText();
+  String toDartText(DartTypes dartTypes);
 
   /// Returns a structured representation of this constant suited for debugging.
-  String toStructuredText();
+  String toStructuredText(DartTypes dartTypes);
 
   ConstantValueKind get kind;
 
@@ -126,7 +126,7 @@
     assertDebugMode("Use ConstantValue.toDartText() or "
         "ConstantValue.toStructuredText() "
         "instead of ConstantValue.toString().");
-    return toStructuredText();
+    return toStructuredText(null);
   }
 }
 
@@ -162,7 +162,7 @@
   ConstantValueKind get kind => ConstantValueKind.FUNCTION;
 
   @override
-  String toDartText() {
+  String toDartText(DartTypes dartTypes) {
     if (element.enclosingClass != null) {
       return '${element.enclosingClass.name}.${element.name}';
     } else {
@@ -171,8 +171,8 @@
   }
 
   @override
-  String toStructuredText() {
-    return 'FunctionConstant(${toDartText()})';
+  String toStructuredText(DartTypes dartTypes) {
+    return 'FunctionConstant(${toDartText(dartTypes)})';
   }
 }
 
@@ -224,10 +224,10 @@
   ConstantValueKind get kind => ConstantValueKind.NULL;
 
   @override
-  String toStructuredText() => 'NullConstant';
+  String toStructuredText(DartTypes dartTypes) => 'NullConstant';
 
   @override
-  String toDartText() => 'null';
+  String toDartText(DartTypes dartTypes) => 'null';
 }
 
 abstract class NumConstantValue extends PrimitiveConstantValue {
@@ -298,10 +298,11 @@
   ConstantValueKind get kind => ConstantValueKind.INT;
 
   @override
-  String toStructuredText() => 'IntConstant(${toDartText()})';
+  String toStructuredText(DartTypes dartTypes) =>
+      'IntConstant(${toDartText(dartTypes)})';
 
   @override
-  String toDartText() => intValue.toString();
+  String toDartText(DartTypes dartTypes) => intValue.toString();
 }
 
 class DoubleConstantValue extends NumConstantValue {
@@ -375,10 +376,11 @@
   ConstantValueKind get kind => ConstantValueKind.DOUBLE;
 
   @override
-  String toStructuredText() => 'DoubleConstant(${toDartText()})';
+  String toStructuredText(DartTypes dartTypes) =>
+      'DoubleConstant(${toDartText(dartTypes)})';
 
   @override
-  String toDartText() => doubleValue.toString();
+  String toDartText(DartTypes dartTypes) => doubleValue.toString();
 }
 
 abstract class BoolConstantValue extends PrimitiveConstantValue {
@@ -405,7 +407,8 @@
   ConstantValueKind get kind => ConstantValueKind.BOOL;
 
   @override
-  String toStructuredText() => 'BoolConstant(${toDartText()})';
+  String toStructuredText(DartTypes dartTypes) =>
+      'BoolConstant(${toDartText(dartTypes)})';
 }
 
 class TrueConstantValue extends BoolConstantValue {
@@ -431,7 +434,7 @@
   int get hashCode => 499;
 
   @override
-  String toDartText() => boolValue.toString();
+  String toDartText(DartTypes dartTypes) => boolValue.toString();
 }
 
 class FalseConstantValue extends BoolConstantValue {
@@ -457,7 +460,7 @@
   int get hashCode => 536555975;
 
   @override
-  String toDartText() => boolValue.toString();
+  String toDartText(DartTypes dartTypes) => boolValue.toString();
 }
 
 class StringConstantValue extends PrimitiveConstantValue {
@@ -498,10 +501,11 @@
 
   // TODO(johnniwinther): Ensure correct escaping.
   @override
-  String toDartText() => '"${stringValue}"';
+  String toDartText(DartTypes dartTypes) => '"${stringValue}"';
 
   @override
-  String toStructuredText() => 'StringConstant(${toDartText()})';
+  String toStructuredText(DartTypes dartTypes) =>
+      'StringConstant(${toDartText(dartTypes)})';
 }
 
 abstract class ObjectConstantValue extends ConstantValue {
@@ -515,8 +519,8 @@
   @override
   DartType getType(CommonElements types) => type;
 
-  void _unparseTypeArguments(StringBuffer sb) {
-    if (!type.treatAsRaw) {
+  void _unparseTypeArguments(DartTypes dartTypes, StringBuffer sb) {
+    if (dartTypes == null || !dartTypes.treatAsRawType(type)) {
       sb.write('<');
       sb.write(type.typeArguments.join(', '));
       sb.write('>');
@@ -552,10 +556,11 @@
   ConstantValueKind get kind => ConstantValueKind.TYPE;
 
   @override
-  String toDartText() => '$representedType';
+  String toDartText(DartTypes dartTypes) => '$representedType';
 
   @override
-  String toStructuredText() => 'TypeConstant(${representedType})';
+  String toStructuredText(DartTypes dartTypes) =>
+      'TypeConstant(${representedType})';
 }
 
 class ListConstantValue extends ObjectConstantValue {
@@ -597,27 +602,27 @@
   ConstantValueKind get kind => ConstantValueKind.LIST;
 
   @override
-  String toDartText() {
+  String toDartText(DartTypes dartTypes) {
     StringBuffer sb = new StringBuffer();
-    _unparseTypeArguments(sb);
+    _unparseTypeArguments(dartTypes, sb);
     sb.write('[');
     for (int i = 0; i < length; i++) {
       if (i > 0) sb.write(',');
-      sb.write(entries[i].toDartText());
+      sb.write(entries[i].toDartText(dartTypes));
     }
     sb.write(']');
     return sb.toString();
   }
 
   @override
-  String toStructuredText() {
+  String toStructuredText(DartTypes dartTypes) {
     StringBuffer sb = new StringBuffer();
     sb.write('ListConstant(');
-    _unparseTypeArguments(sb);
+    _unparseTypeArguments(dartTypes, sb);
     sb.write('[');
     for (int i = 0; i < length; i++) {
       if (i > 0) sb.write(', ');
-      sb.write(entries[i].toStructuredText());
+      sb.write(entries[i].toStructuredText(dartTypes));
     }
     sb.write('])');
     return sb.toString();
@@ -660,22 +665,26 @@
   accept(ConstantValueVisitor visitor, arg) => visitor.visitSet(this, arg);
 
   @override
-  String toDartText() {
+  String toDartText(DartTypes dartTypes) {
     StringBuffer sb = new StringBuffer();
-    _unparseTypeArguments(sb);
+    _unparseTypeArguments(dartTypes, sb);
     sb.write('{');
-    sb.writeAll(values.map((v) => v.toDartText()), ',');
+    sb.writeAll(values.map((v) => v.toDartText(dartTypes)), ',');
     sb.write('}');
     return sb.toString();
   }
 
   @override
-  String toStructuredText() {
+  String toStructuredText(DartTypes dartTypes) {
     StringBuffer sb = new StringBuffer();
     sb.write('SetConstant(');
-    _unparseTypeArguments(sb);
+    _unparseTypeArguments(dartTypes, sb);
     sb.write('{');
-    sb.writeAll(values.map((v) => v.toStructuredText()), ', ');
+    sb.writeAll(
+        values.map((v) => v.toStructuredText(
+              dartTypes,
+            )),
+        ', ');
     sb.write('})');
     return sb.toString();
   }
@@ -742,31 +751,31 @@
   ConstantValueKind get kind => ConstantValueKind.MAP;
 
   @override
-  String toDartText() {
+  String toDartText(DartTypes dartTypes) {
     StringBuffer sb = new StringBuffer();
-    _unparseTypeArguments(sb);
+    _unparseTypeArguments(dartTypes, sb);
     sb.write('{');
     for (int i = 0; i < length; i++) {
       if (i > 0) sb.write(',');
-      sb.write(keys[i].toDartText());
+      sb.write(keys[i].toDartText(dartTypes));
       sb.write(':');
-      sb.write(values[i].toDartText());
+      sb.write(values[i].toDartText(dartTypes));
     }
     sb.write('}');
     return sb.toString();
   }
 
   @override
-  String toStructuredText() {
+  String toStructuredText(DartTypes dartTypes) {
     StringBuffer sb = new StringBuffer();
     sb.write('MapConstant(');
-    _unparseTypeArguments(sb);
+    _unparseTypeArguments(dartTypes, sb);
     sb.write('{');
     for (int i = 0; i < length; i++) {
       if (i > 0) sb.write(', ');
-      sb.write(keys[i].toStructuredText());
+      sb.write(keys[i].toStructuredText(dartTypes));
       sb.write(': ');
-      sb.write(values[i].toStructuredText());
+      sb.write(values[i].toStructuredText(dartTypes));
     }
     sb.write('})');
     return sb.toString();
@@ -806,12 +815,12 @@
   ConstantValueKind get kind => ConstantValueKind.INTERCEPTOR;
 
   @override
-  String toDartText() {
+  String toDartText(DartTypes dartTypes) {
     return 'interceptor($cls)';
   }
 
   @override
-  String toStructuredText() {
+  String toStructuredText(DartTypes dartTypes) {
     return 'InterceptorConstant(${cls.name})';
   }
 }
@@ -847,10 +856,10 @@
   ConstantValueKind get kind => ConstantValueKind.JS_NAME;
 
   @override
-  String toDartText() => 'js_name(${name})';
+  String toDartText(DartTypes dartTypes) => 'js_name(${name})';
 
   @override
-  String toStructuredText() => 'JsNameConstant(${name})';
+  String toStructuredText(DartTypes dartTypes) => 'JsNameConstant(${name})';
 }
 
 /// A constant used as the dummy interceptor value for intercepted calls with
@@ -887,10 +896,11 @@
   ConstantValueKind get kind => ConstantValueKind.DUMMY_INTERCEPTOR;
 
   @override
-  String toDartText() => 'dummy_interceptor($abstractValue)';
+  String toDartText(DartTypes dartTypes) => 'dummy_interceptor($abstractValue)';
 
   @override
-  String toStructuredText() => 'DummyInterceptorConstant($abstractValue)';
+  String toStructuredText(DartTypes dartTypes) =>
+      'DummyInterceptorConstant($abstractValue)';
 }
 
 // A constant with an empty type used in [HInstruction]s of an expression
@@ -916,10 +926,10 @@
   ConstantValueKind get kind => ConstantValueKind.UNREACHABLE;
 
   @override
-  String toDartText() => 'unreachable()';
+  String toDartText(DartTypes dartTypes) => 'unreachable()';
 
   @override
-  String toStructuredText() => 'UnreachableConstant()';
+  String toStructuredText(DartTypes dartTypes) => 'UnreachableConstant()';
 }
 
 class ConstructedConstantValue extends ObjectConstantValue {
@@ -972,10 +982,10 @@
   }
 
   @override
-  String toDartText() {
+  String toDartText(DartTypes dartTypes) {
     StringBuffer sb = new StringBuffer();
     sb.write(type.element.name);
-    _unparseTypeArguments(sb);
+    _unparseTypeArguments(dartTypes, sb);
     sb.write('(');
     int i = 0;
     for (FieldEntity field in _fieldsSortedByName) {
@@ -983,7 +993,7 @@
       if (i > 0) sb.write(',');
       sb.write(field.name);
       sb.write('=');
-      sb.write(value.toDartText());
+      sb.write(value.toDartText(dartTypes));
       i++;
     }
     sb.write(')');
@@ -991,7 +1001,7 @@
   }
 
   @override
-  String toStructuredText() {
+  String toStructuredText(DartTypes dartTypes) {
     StringBuffer sb = new StringBuffer();
     sb.write('ConstructedConstant(');
     sb.write(type);
@@ -1002,7 +1012,7 @@
       if (i > 0) sb.write(',');
       sb.write(field.name);
       sb.write('=');
-      sb.write(value.toStructuredText());
+      sb.write(value.toStructuredText(dartTypes));
       i++;
     }
     sb.write('))');
@@ -1046,13 +1056,13 @@
   ConstantValueKind get kind => ConstantValueKind.INSTANTIATION;
 
   @override
-  String toDartText() =>
-      '<${typeArguments.join(', ')}>(${function.toDartText()})';
+  String toDartText(DartTypes dartTypes) =>
+      '<${typeArguments.join(', ')}>(${function.toDartText(dartTypes)})';
 
   @override
-  String toStructuredText() {
+  String toStructuredText(DartTypes dartTypes) {
     return 'InstantiationConstant($typeArguments,'
-        '${function.toStructuredText()})';
+        '${function.toStructuredText(dartTypes)})';
   }
 }
 
@@ -1100,11 +1110,12 @@
   ConstantValueKind get kind => ConstantValueKind.DEFERRED_GLOBAL;
 
   @override
-  String toDartText() => 'deferred_global(${referenced.toDartText()})';
+  String toDartText(DartTypes dartTypes) =>
+      'deferred_global(${referenced.toDartText(dartTypes)})';
 
   @override
-  String toStructuredText() {
-    return 'DeferredGlobalConstant(${referenced.toStructuredText()})';
+  String toStructuredText(DartTypes dartTypes) {
+    return 'DeferredGlobalConstant(${referenced.toStructuredText(dartTypes)})';
   }
 }
 
@@ -1130,8 +1141,8 @@
   ConstantValueKind get kind => ConstantValueKind.NON_CONSTANT;
 
   @override
-  String toStructuredText() => 'NonConstant';
+  String toStructuredText(DartTypes dartTypes) => 'NonConstant';
 
   @override
-  String toDartText() => '>>non-constant<<';
+  String toDartText(DartTypes dartTypes) => '>>non-constant<<';
 }
diff --git a/pkg/compiler/lib/src/deferred_load.dart b/pkg/compiler/lib/src/deferred_load.dart
index 3823270..42aa893 100644
--- a/pkg/compiler/lib/src/deferred_load.dart
+++ b/pkg/compiler/lib/src/deferred_load.dart
@@ -148,6 +148,7 @@
       compiler.frontendStrategy.elementEnvironment;
 
   CommonElements get commonElements => compiler.frontendStrategy.commonElements;
+  DartTypes get dartTypes => commonElements.dartTypes;
 
   DiagnosticReporter get reporter => compiler.reporter;
 
@@ -416,8 +417,8 @@
           newSet != importSets.mainSet || oldSet != null,
           failedAt(
               NO_LOCATION_SPANNABLE,
-              "Tried to assign ${constant.toDartText()} to the main output "
-              "unit, but it was assigned to $currentSet."));
+              "Tried to assign ${constant.toDartText(closedWorld.dartTypes)} "
+              "to the main output unit, but it was assigned to $currentSet."));
       queue.addConstant(constant, newSet);
     }
   }
@@ -915,7 +916,7 @@
       if (value.isPrimitive) return;
       constantMap
           .putIfAbsent(importSet.unit, () => <String>[])
-          .add(value.toStructuredText());
+          .add(value.toStructuredText(dartTypes));
     });
 
     Map<OutputUnit, String> text = {};
diff --git a/pkg/compiler/lib/src/elements/types.dart b/pkg/compiler/lib/src/elements/types.dart
index 72df23f..efc2f70 100644
--- a/pkg/compiler/lib/src/elements/types.dart
+++ b/pkg/compiler/lib/src/elements/types.dart
@@ -36,11 +36,10 @@
   DartType get unaliased => this;
 
   /// Is `true` if this type is a top type.
-  // TODO(fishythefish): Update this for NNBD.
-  bool get isTop => false;
+  bool _isTop(bool isLegacy) => false;
 
   /// Is `true` if this type has no non-top type arguments.
-  bool get treatAsRaw => true;
+  bool _treatAsRaw(bool isLegacy) => true;
 
   /// Whether this type contains a type variable.
   bool get containsTypeVariables => false;
@@ -83,21 +82,6 @@
 
   bool _equals(DartType other, _Assumptions assumptions);
 
-  /// Returns `true` if `this` is structurally equal to [other] up to renaming
-  /// of bound type variables (trivially true) and equating all top types.
-  ///
-  /// This method handles the common cases of identity and top types. Types
-  /// should add any additional logic by implementing
-  /// [_equalsModuloTopInternal].
-  bool _equalsModuloTop(DartType other) {
-    other = other.unaliased;
-    if (identical(this, other)) return true;
-    if (isTop) return other.isTop;
-    return _equalsModuloTopInternal(other);
-  }
-
-  bool _equalsModuloTopInternal(DartType other);
-
   @override
   String toString() => _DartTypeToStringVisitor().run(this);
 }
@@ -195,14 +179,6 @@
 
   bool _equalsInternal(LegacyType other, _Assumptions assumptions) =>
       baseType._equals(other.baseType, assumptions);
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) {
-    if (other is LegacyType) {
-      return baseType._equalsModuloTop(other.baseType);
-    }
-    return false;
-  }
 }
 
 class NullableType extends DartType {
@@ -211,6 +187,9 @@
   NullableType(this.baseType);
 
   @override
+  bool _isTop(bool isLegacy) => isLegacy ? false : baseType.isObject;
+
+  @override
   bool get containsTypeVariables => baseType.containsTypeVariables;
 
   @override
@@ -241,14 +220,6 @@
 
   bool _equalsInternal(NullableType other, _Assumptions assumptions) =>
       baseType._equals(other.baseType, assumptions);
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) {
-    if (other is NullableType) {
-      return baseType._equalsModuloTop(other.baseType);
-    }
-    return false;
-  }
 }
 
 class InterfaceType extends DartType {
@@ -259,7 +230,7 @@
       : assert(typeArguments.every((e) => e != null));
 
   @override
-  bool get isTop => isObject;
+  bool _isTop(bool isLegacy) => isLegacy ? isObject : false;
 
   @override
   bool get isObject =>
@@ -280,9 +251,9 @@
   }
 
   @override
-  bool get treatAsRaw {
+  bool _treatAsRaw(bool isLegacy) {
     for (DartType type in typeArguments) {
-      if (!type.isTop) return false;
+      if (!type._isTop(isLegacy)) return false;
     }
     return true;
   }
@@ -319,15 +290,6 @@
     return identical(element, other.element) &&
         _equalTypes(typeArguments, other.typeArguments, assumptions);
   }
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) {
-    if (other is InterfaceType) {
-      return identical(element, other.element) &&
-          _equalTypesModuloTop(typeArguments, other.typeArguments);
-    }
-    return false;
-  }
 }
 
 class TypedefType extends DartType {
@@ -339,7 +301,7 @@
   TypedefType(this.element, this.typeArguments, this.unaliased);
 
   @override
-  bool get isTop => unaliased.isTop;
+  bool _isTop(bool isLegacy) => unaliased._isTop(isLegacy);
 
   @override
   bool get containsTypeVariables =>
@@ -351,9 +313,9 @@
   }
 
   @override
-  bool get treatAsRaw {
+  bool _treatAsRaw(bool isLegacy) {
     for (DartType type in typeArguments) {
-      if (!type.isTop) return false;
+      if (!type._isTop(isLegacy)) return false;
     }
     return true;
   }
@@ -390,12 +352,6 @@
     return identical(element, other.element) &&
         _equalTypes(typeArguments, other.typeArguments, assumptions);
   }
-
-  @override
-  bool _equalsModuloTop(DartType other) => unaliased._equalsModuloTop(other);
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) => false;
 }
 
 class TypeVariableType extends DartType {
@@ -431,14 +387,6 @@
     }
     return false;
   }
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) {
-    if (other is TypeVariableType) {
-      return identical(other.element, element);
-    }
-    return false;
-  }
 }
 
 /// A type variable declared on a function type.
@@ -489,14 +437,6 @@
   }
 
   @override
-  bool _equalsModuloTopInternal(DartType other) {
-    if (other is FunctionTypeVariable) {
-      return index == other.index;
-    }
-    return false;
-  }
-
-  @override
   R accept<R, A>(DartTypeVisitor<R, A> visitor, A argument) =>
       visitor.visitFunctionTypeVariable(this, argument);
 }
@@ -516,9 +456,6 @@
   @override
   bool _equals(DartType other, _Assumptions assumptions) =>
       identical(this, other);
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) => false;
 }
 
 class VoidType extends DartType {
@@ -527,7 +464,7 @@
   factory VoidType() => const VoidType._();
 
   @override
-  bool get isTop => true;
+  bool _isTop(bool isLegacy) => true;
 
   @override
   R accept<R, A>(DartTypeVisitor<R, A> visitor, A argument) =>
@@ -540,9 +477,6 @@
   bool _equals(DartType other, _Assumptions assumptions) {
     return identical(this, other);
   }
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) => false;
 }
 
 class DynamicType extends DartType {
@@ -551,7 +485,7 @@
   factory DynamicType() => const DynamicType._();
 
   @override
-  bool get isTop => true;
+  bool _isTop(bool isLegacy) => true;
 
   @override
   R accept<R, A>(DartTypeVisitor<R, A> visitor, A argument) =>
@@ -564,9 +498,6 @@
   bool _equals(DartType other, _Assumptions assumptions) {
     return identical(this, other);
   }
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) => false;
 }
 
 class ErasedType extends DartType {
@@ -575,7 +506,7 @@
   factory ErasedType() => const ErasedType._();
 
   @override
-  bool get isTop => true;
+  bool _isTop(bool isLegacy) => true;
 
   @override
   R accept<R, A>(DartTypeVisitor<R, A> visitor, A argument) =>
@@ -587,9 +518,6 @@
   @override
   bool _equals(DartType other, _Assumptions assumptions) =>
       identical(this, other);
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) => false;
 }
 
 /// Represents a type which is simultaneously top and bottom.
@@ -609,7 +537,7 @@
   factory AnyType() => const AnyType._();
 
   @override
-  bool get isTop => true;
+  bool _isTop(bool isLegacy) => true;
 
   @override
   R accept<R, A>(DartTypeVisitor<R, A> visitor, A argument) =>
@@ -621,9 +549,6 @@
   @override
   bool _equals(DartType other, _Assumptions assumptions) =>
       identical(this, other);
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) => false;
 }
 
 class FunctionType extends DartType {
@@ -750,21 +675,6 @@
     }
     return result;
   }
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) {
-    if (other is FunctionType) {
-      return returnType._equalsModuloTop(other.returnType) &&
-          _equalTypesModuloTop(parameterTypes, other.parameterTypes) &&
-          _equalTypesModuloTop(
-              optionalParameterTypes, other.optionalParameterTypes) &&
-          equalElements(namedParameters, other.namedParameters) &&
-          _equalTypesModuloTop(
-              namedParameterTypes, other.namedParameterTypes) &&
-          _equalTypesModuloTop(typeVariableBounds, other.typeVariableBounds);
-    }
-    return false;
-  }
 }
 
 class FutureOrType extends DartType {
@@ -773,7 +683,7 @@
   FutureOrType(this.typeArgument);
 
   @override
-  bool get isTop => typeArgument.isTop;
+  bool _isTop(bool isLegacy) => typeArgument._isTop(isLegacy);
 
   @override
   bool get containsTypeVariables => typeArgument.containsTypeVariables;
@@ -807,14 +717,6 @@
   bool _equalsInternal(FutureOrType other, _Assumptions assumptions) {
     return typeArgument._equals(other.typeArgument, assumptions);
   }
-
-  @override
-  bool _equalsModuloTopInternal(DartType other) {
-    if (other is FutureOrType) {
-      return typeArgument._equalsModuloTop(other.typeArgument);
-    }
-    return false;
-  }
 }
 
 bool _equalTypes(List<DartType> a, List<DartType> b, _Assumptions assumptions) {
@@ -827,14 +729,6 @@
   return true;
 }
 
-bool _equalTypesModuloTop(List<DartType> a, List<DartType> b) {
-  if (a.length != b.length) return false;
-  for (int i = 0; i < a.length; i++) {
-    if (!a[i]._equalsModuloTop(b[i])) return false;
-  }
-  return true;
-}
-
 abstract class DartTypeVisitor<R, A> {
   const DartTypeVisitor();
 
@@ -1590,6 +1484,16 @@
   /// The types defined in 'dart:core'.
   CommonElements get commonElements;
 
+  bool get useLegacySubtyping;
+
+  /// Returns `true` if every type argument of [t] is a top type.
+  // TODO(fishythefish): Should we instead check if each type argument is at its
+  // bound?
+  bool treatAsRawType(DartType t) => t._treatAsRaw(useLegacySubtyping);
+
+  /// Returns `true` if [t] is a top type, that is, a supertype of every type.
+  bool isTopType(DartType t) => t._isTop(useLegacySubtyping);
+
   /// Returns `true` if [s] is a subtype of [t].
   bool isSubtype(DartType s, DartType t) => _subtypeHelper(s, t);
 
@@ -1627,7 +1531,7 @@
           s.index == t.index) return true;
 
       // Right Top:
-      if (t.isTop) return true;
+      if (isTopType(t)) return true;
 
       if (s is AnyType) return true;
       if (allowPotentialSubtypes &&
@@ -1636,12 +1540,14 @@
           (s is FunctionTypeVariable || t is FunctionTypeVariable)) return true;
 
       // Left Top:
-      if (s.isTop) return false;
+      if (isTopType(s)) return false;
 
       // Left Bottom:
-      // TODO(fishythefish): Update for NNBD - check for `Never` instead of
-      // `Null`.
-      if (s.isNull) return true;
+      if (useLegacySubtyping) {
+        if (s.isNull) return true;
+      } else {
+        if (s is NeverType) return true;
+      }
 
       // Left Type Variable Bound 1:
       if (s is TypeVariableType) {
@@ -1655,7 +1561,7 @@
       // Left Null:
       // Note: Interchanging the Left Null and Right Object rules allows us to
       // reduce casework.
-      if (s.isNull) {
+      if (!useLegacySubtyping && s.isNull) {
         if (t is FutureOrType) {
           return _isSubtype(s, sEnv, t.typeArgument, tEnv);
         }
@@ -1663,7 +1569,7 @@
       }
 
       // Right Object:
-      if (t.isObject) {
+      if (!useLegacySubtyping && t.isObject) {
         if (s is FutureOrType) {
           return _isSubtype(s.typeArgument, sEnv, t, tEnv);
         }
@@ -1680,7 +1586,8 @@
 
       // Right Legacy:
       if (t is LegacyType) {
-        return _isSubtype(s, sEnv, NullableType(t.baseType), tEnv);
+        return _isSubtype(s, sEnv,
+            useLegacySubtyping ? t.baseType : NullableType(t.baseType), tEnv);
       }
 
       // Left FutureOr:
@@ -1692,7 +1599,8 @@
 
       // Left Nullable:
       if (s is NullableType) {
-        return _isSubtype(commonElements.nullType, sEnv, t, tEnv) &&
+        return (useLegacySubtyping ||
+                _isSubtype(commonElements.nullType, sEnv, t, tEnv)) &&
             _isSubtype(s.baseType, sEnv, t, tEnv);
       }
 
@@ -1712,7 +1620,8 @@
 
       // Right Nullable:
       if (t is NullableType) {
-        return _isSubtype(s, sEnv, commonElements.nullType, tEnv) ||
+        return (!useLegacySubtyping &&
+                _isSubtype(s, sEnv, commonElements.nullType, tEnv)) ||
             _isSubtype(s, sEnv, t.baseType, tEnv);
       }
 
@@ -1736,10 +1645,18 @@
         if (s is FunctionType) {
           if (t.isGeneric) {
             if (!s.isGeneric) return false;
-            if (!_equalTypesModuloTop(
-                s.typeVariableBounds, t.typeVariableBounds)) {
+            List<DartType> sBounds = s.typeVariableBounds;
+            List<DartType> tBounds = t.typeVariableBounds;
+            int length = sBounds.length;
+            if (length != tBounds.length) {
               return false;
             }
+            for (int i = 0; i < length; i++) {
+              if (!_isSubtype(sBounds[i], sEnv, tBounds[i], tEnv) ||
+                  !_isSubtype(tBounds[i], tEnv, sBounds[i], sEnv)) {
+                return false;
+              }
+            }
             sEnv = sEnv.toSet()..addAll(s.typeVariables);
             tEnv = tEnv.toSet()..addAll(t.typeVariables);
           }
diff --git a/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart b/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
index 3cbac15..5dbcf12 100644
--- a/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
+++ b/pkg/compiler/lib/src/inferrer/type_graph_nodes.dart
@@ -2253,7 +2253,7 @@
     {bool isNullable: true}) {
   AbstractValueDomain abstractValueDomain = closedWorld.abstractValueDomain;
   AbstractValue otherType;
-  if (annotation.isTop) {
+  if (closedWorld.dartTypes.isTopType(annotation)) {
     return type;
   } else if (annotation is InterfaceType) {
     if (annotation.element == closedWorld.commonElements.objectClass) {
diff --git a/pkg/compiler/lib/src/inferrer/type_system.dart b/pkg/compiler/lib/src/inferrer/type_system.dart
index accf437..cec794d 100644
--- a/pkg/compiler/lib/src/inferrer/type_system.dart
+++ b/pkg/compiler/lib/src/inferrer/type_system.dart
@@ -319,7 +319,7 @@
       {bool isNullable: true}) {
     AbstractValue otherType;
     if (annotation is VoidType) return type;
-    if (annotation.isTop) {
+    if (_closedWorld.dartTypes.isTopType(annotation)) {
       if (isNullable) return type;
       // If the input is already narrowed to be not-null, there is no value
       // in adding another narrowing node.
diff --git a/pkg/compiler/lib/src/inferrer/typemasks/masks.dart b/pkg/compiler/lib/src/inferrer/typemasks/masks.dart
index b14ebae..fdfb99e 100644
--- a/pkg/compiler/lib/src/inferrer/typemasks/masks.dart
+++ b/pkg/compiler/lib/src/inferrer/typemasks/masks.dart
@@ -43,6 +43,7 @@
   CommonMasks(this._closedWorld);
 
   CommonElements get commonElements => _closedWorld.commonElements;
+  DartTypes get dartTypes => _closedWorld.dartTypes;
 
   TypeMask _dynamicType;
   TypeMask _nonNullType;
@@ -883,7 +884,7 @@
 
   @override
   String getCompactText(AbstractValue value) {
-    return formatType(value);
+    return formatType(dartTypes, value);
   }
 
   @override
@@ -903,7 +904,7 @@
 ///
 /// The default format is too verbose for the graph format since long strings
 /// create oblong nodes that obstruct the graph layout.
-String formatType(TypeMask type) {
+String formatType(DartTypes dartTypes, TypeMask type) {
   if (type is FlatTypeMask) {
     // TODO(asgerf): Disambiguate classes whose name is not unique. Using the
     //     library name for all classes is not a good idea, since library names
@@ -916,22 +917,22 @@
     return '${type.base.name}$nullFlag$subFlag';
   }
   if (type is UnionTypeMask) {
-    return type.disjointMasks.map(formatType).join(' | ');
+    return type.disjointMasks.map((m) => formatType(dartTypes, m)).join(' | ');
   }
   if (type is ContainerTypeMask) {
-    String container = formatType(type.forwardTo);
-    String member = formatType(type.elementType);
+    String container = formatType(dartTypes, type.forwardTo);
+    String member = formatType(dartTypes, type.elementType);
     return '$container<$member>';
   }
   if (type is MapTypeMask) {
-    String container = formatType(type.forwardTo);
-    String key = formatType(type.keyType);
-    String value = formatType(type.valueType);
+    String container = formatType(dartTypes, type.forwardTo);
+    String key = formatType(dartTypes, type.keyType);
+    String value = formatType(dartTypes, type.valueType);
     return '$container<$key,$value>';
   }
   if (type is ValueTypeMask) {
-    String baseType = formatType(type.forwardTo);
-    String value = type.value.toStructuredText();
+    String baseType = formatType(dartTypes, type.forwardTo);
+    String value = type.value.toStructuredText(dartTypes);
     return '$baseType=$value';
   }
   return '$type'; // Fall back on toString if not supported here.
diff --git a/pkg/compiler/lib/src/inferrer/typemasks/value_type_mask.dart b/pkg/compiler/lib/src/inferrer/typemasks/value_type_mask.dart
index 1c965dc..fb475be 100644
--- a/pkg/compiler/lib/src/inferrer/typemasks/value_type_mask.dart
+++ b/pkg/compiler/lib/src/inferrer/typemasks/value_type_mask.dart
@@ -73,6 +73,6 @@
 
   @override
   String toString() {
-    return 'Value($forwardTo, value: ${value.toDartText()})';
+    return 'Value($forwardTo, value: ${value.toDartText(null)})';
   }
 }
diff --git a/pkg/compiler/lib/src/ir/types.dart b/pkg/compiler/lib/src/ir/types.dart
index cbaf115..f2b01cb 100644
--- a/pkg/compiler/lib/src/ir/types.dart
+++ b/pkg/compiler/lib/src/ir/types.dart
@@ -11,8 +11,10 @@
 /// Support for subtype checks of kernel based [DartType]s.
 class KernelDartTypes extends DartTypes {
   final IrToElementMap elementMap;
+  @override
+  final bool useLegacySubtyping;
 
-  KernelDartTypes(this.elementMap);
+  KernelDartTypes(this.elementMap, this.useLegacySubtyping);
 
   @override
   InterfaceType getThisType(ClassEntity cls) {
diff --git a/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart b/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
index 46b78b2..966e8a7 100644
--- a/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
+++ b/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
@@ -205,6 +205,8 @@
       {bool typeCast, bool nativeCheckOnly}) {
     assert(type is! TypedefType);
 
+    DartTypes dartTypes = commonElements.dartTypes;
+
     if (type is TypeVariableType) {
       return typeCast
           ? 'subtypeOfRuntimeTypeCast'
@@ -275,16 +277,17 @@
 
     if ((element == commonElements.listClass ||
             element == commonElements.jsArrayClass) &&
-        type.treatAsRaw) {
+        dartTypes.treatAsRawType(type)) {
       if (nativeCheckOnly) return null;
       return 'list$suffix';
     }
 
-    if (commonElements.isListSupertype(element) && type.treatAsRaw) {
+    if (commonElements.isListSupertype(element) &&
+        dartTypes.treatAsRawType(type)) {
       return nativeCheck ? 'listSuperNative$suffix' : 'listSuper$suffix';
     }
 
-    if (type is InterfaceType && !type.treatAsRaw) {
+    if (type is InterfaceType && !dartTypes.treatAsRawType(type)) {
       return typeCast ? 'subtypeCast' : 'assertSubtype';
     }
 
diff --git a/pkg/compiler/lib/src/js_backend/constant_emitter.dart b/pkg/compiler/lib/src/js_backend/constant_emitter.dart
index 2146a2c..9a89069 100644
--- a/pkg/compiler/lib/src/js_backend/constant_emitter.dart
+++ b/pkg/compiler/lib/src/js_backend/constant_emitter.dart
@@ -392,7 +392,7 @@
         throw failedAt(
             NO_LOCATION_SPANNABLE,
             "Unexpected type variable '${variable}'"
-            " in constant '${constant.toDartText()}'");
+            " in constant '${constant.toDartText(_commonElements.dartTypes)}'");
       }
 
       jsAst.Expression rti =
@@ -463,7 +463,7 @@
   jsAst.Expression maybeAddTypeArguments(
       ConstantValue constant, InterfaceType type, jsAst.Expression value) {
     if (type is InterfaceType &&
-        !type.treatAsRaw &&
+        !_commonElements.dartTypes.treatAsRawType(type) &&
         _rtiNeed.classNeedsTypeArguments(type.element)) {
       return new jsAst.Call(
           getHelperProperty(_commonElements.setRuntimeTypeInfo),
@@ -490,7 +490,7 @@
       throw failedAt(
           NO_LOCATION_SPANNABLE,
           "Unexpected type variable '${variable}'"
-          " in constant '${constant.toDartText()}'");
+          " in constant '${constant.toDartText(_commonElements.dartTypes)}'");
     }
 
     List<jsAst.Expression> arguments = <jsAst.Expression>[];
diff --git a/pkg/compiler/lib/src/js_backend/field_analysis.dart b/pkg/compiler/lib/src/js_backend/field_analysis.dart
index 766013e..a40b882 100644
--- a/pkg/compiler/lib/src/js_backend/field_analysis.dart
+++ b/pkg/compiler/lib/src/js_backend/field_analysis.dart
@@ -9,6 +9,7 @@
 import '../constants/values.dart';
 import '../elements/entities.dart';
 import '../elements/entity_utils.dart';
+import '../elements/types.dart';
 import '../ir/scope_visitor.dart';
 import '../js_model/elements.dart' show JField;
 import '../js_model/js_world_builder.dart';
@@ -170,7 +171,7 @@
 
   @override
   String toString() =>
-      'AllocatorData(initialValue=${initialValue?.toStructuredText()},'
+      'AllocatorData(initialValue=${initialValue?.toStructuredText(null)},'
       'initializers=$initializers)';
 }
 
@@ -206,14 +207,14 @@
         name = null,
         value = null;
 
-  String get shortText {
+  String shortText(DartTypes dartTypes) {
     switch (kind) {
       case InitializerKind.direct:
-        return value.toStructuredText();
+        return value.toStructuredText(dartTypes);
       case InitializerKind.positional:
-        return '$index:${value.toStructuredText()}';
+        return '$index:${value.toStructuredText(dartTypes)}';
       case InitializerKind.named:
-        return '$name:${value.toStructuredText()}';
+        return '$name:${value.toStructuredText(dartTypes)}';
       case InitializerKind.complex:
         return '?';
     }
@@ -221,7 +222,7 @@
   }
 
   @override
-  String toString() => shortText;
+  String toString() => shortText(null);
 }
 
 class JFieldAnalysis {
@@ -631,7 +632,7 @@
 
   @override
   String toString() =>
-      'FieldAnalysisData(initialValue=${initialValue?.toStructuredText()},'
+      'FieldAnalysisData(initialValue=${initialValue?.toStructuredText(null)},'
       'isInitializedInAllocator=$isInitializedInAllocator,'
       'isEffectivelyFinal=$isEffectivelyFinal,isElided=$isElided,'
       'isEager=$isEager,eagerCreationIndex=$eagerCreationIndex,'
diff --git a/pkg/compiler/lib/src/js_backend/impact_transformer.dart b/pkg/compiler/lib/src/js_backend/impact_transformer.dart
index 9562b9f..5ccffe9 100644
--- a/pkg/compiler/lib/src/js_backend/impact_transformer.dart
+++ b/pkg/compiler/lib/src/js_backend/impact_transformer.dart
@@ -58,6 +58,8 @@
       this._classHierarchyBuilder,
       this._annotationsData);
 
+  DartTypes get _dartTypes => _commonElements.dartTypes;
+
   @override
   WorldImpact transformResolutionImpact(ResolutionImpact worldImpact) {
     TransformedWorldImpact transformed =
@@ -330,7 +332,7 @@
     type = _elementEnvironment.getUnaliasedType(type);
     registerImpact(_impacts.typeCheck);
 
-    if (!type.treatAsRaw ||
+    if (!_dartTypes.treatAsRawType(type) ||
         type.containsTypeVariables ||
         type is FunctionType) {
       registerImpact(_impacts.genericTypeCheck);
@@ -382,7 +384,8 @@
     type = type.unaliased;
     _impacts.typeCheck.registerImpact(transformed, _elementEnvironment);
 
-    if (!type.treatAsRaw || type.containsTypeVariables) {
+    if (!_closedWorld.dartTypes.treatAsRawType(type) ||
+        type.containsTypeVariables) {
       _impacts.genericIsCheck.registerImpact(transformed, _elementEnvironment);
     }
     if (type is InterfaceType && _nativeData.isNativeClass(type.element)) {
diff --git a/pkg/compiler/lib/src/js_backend/interceptor_data.dart b/pkg/compiler/lib/src/js_backend/interceptor_data.dart
index 867c379..e92b0ce 100644
--- a/pkg/compiler/lib/src/js_backend/interceptor_data.dart
+++ b/pkg/compiler/lib/src/js_backend/interceptor_data.dart
@@ -277,7 +277,7 @@
     // We can use an instanceof check for raw types that have no subclass that
     // is mixed-in or in an implements clause.
 
-    if (!type.treatAsRaw) return false;
+    if (!closedWorld.dartTypes.treatAsRawType(type)) return false;
     if (type is FutureOrType) return false;
     InterfaceType interfaceType = type;
     ClassEntity classElement = interfaceType.element;
diff --git a/pkg/compiler/lib/src/js_backend/runtime_types.dart b/pkg/compiler/lib/src/js_backend/runtime_types.dart
index 16a3050..e397bab 100644
--- a/pkg/compiler/lib/src/js_backend/runtime_types.dart
+++ b/pkg/compiler/lib/src/js_backend/runtime_types.dart
@@ -832,8 +832,8 @@
 
   RuntimeTypesEncoderImpl(this.rtiTags, NativeBasicData nativeData,
       this._elementEnvironment, this.commonElements, this._rtiNeed)
-      : _representationGenerator =
-            new TypeRepresentationGenerator(rtiTags, nativeData);
+      : _representationGenerator = new TypeRepresentationGenerator(
+            commonElements.dartTypes, rtiTags, nativeData);
 
   /// Returns the JavaScript template to determine at runtime if a type object
   /// is a function type.
@@ -969,6 +969,7 @@
 
 class TypeRepresentationGenerator
     implements DartTypeVisitor<jsAst.Expression, ModularEmitter> {
+  final DartTypes _dartTypes;
   final RuntimeTypeTags _rtiTags;
   final NativeBasicData _nativeData;
 
@@ -977,7 +978,7 @@
   Map<TypeVariableType, jsAst.Expression> typedefBindings;
   List<FunctionTypeVariable> functionTypeVariables = <FunctionTypeVariable>[];
 
-  TypeRepresentationGenerator(this._rtiTags, this._nativeData);
+  TypeRepresentationGenerator(this._dartTypes, this._rtiTags, this._nativeData);
 
   /// Creates a type representation for [type]. [onVariable] is called to
   /// provide the type representation for type variables.
@@ -1245,7 +1246,7 @@
       jsAst.ObjectInitializer initializer = visit(unaliasedType, emitter);
       // We have to encode the aliased type.
       jsAst.Expression name = getJavaScriptClassName(type.element, emitter);
-      jsAst.Expression encodedTypedef = type.treatAsRaw
+      jsAst.Expression encodedTypedef = _dartTypes.treatAsRawType(type)
           ? name
           : visitList(type.typeArguments, emitter, head: name);
 
diff --git a/pkg/compiler/lib/src/js_backend/runtime_types_codegen.dart b/pkg/compiler/lib/src/js_backend/runtime_types_codegen.dart
index 982e018..ce9fd1d 100644
--- a/pkg/compiler/lib/src/js_backend/runtime_types_codegen.dart
+++ b/pkg/compiler/lib/src/js_backend/runtime_types_codegen.dart
@@ -130,10 +130,10 @@
 
   Set<ClassEntity> getClassesUsedInSubstitutions(TypeChecks checks);
 
-  static bool hasTypeArguments(DartType type) {
+  static bool hasTypeArguments(DartTypes dartTypes, DartType type) {
     if (type is InterfaceType) {
       InterfaceType interfaceType = type;
-      return !interfaceType.treatAsRaw;
+      return !dartTypes.treatAsRawType(interfaceType);
     }
     return false;
   }
diff --git a/pkg/compiler/lib/src/js_backend/runtime_types_resolution.dart b/pkg/compiler/lib/src/js_backend/runtime_types_resolution.dart
index a303026..4f62071 100644
--- a/pkg/compiler/lib/src/js_backend/runtime_types_resolution.dart
+++ b/pkg/compiler/lib/src/js_backend/runtime_types_resolution.dart
@@ -1057,7 +1057,7 @@
       checks.forEach((DartType type) {
         if (type is InterfaceType) {
           InterfaceType itf = type;
-          if (!itf.treatAsRaw) {
+          if (!closedWorld.dartTypes.treatAsRawType(itf)) {
             potentiallyNeedTypeArguments(itf.element);
           }
         } else {
diff --git a/pkg/compiler/lib/src/js_emitter/model.dart b/pkg/compiler/lib/src/js_emitter/model.dart
index fc87346..5008ebd 100644
--- a/pkg/compiler/lib/src/js_emitter/model.dart
+++ b/pkg/compiler/lib/src/js_emitter/model.dart
@@ -182,7 +182,7 @@
 
   @override
   String toString() {
-    return 'Constant(name=${name.key},value=${value.toStructuredText()})';
+    return 'Constant(name=${name.key},value=${value.toStructuredText(null)})';
   }
 }
 
diff --git a/pkg/compiler/lib/src/js_emitter/program_builder/field_visitor.dart b/pkg/compiler/lib/src/js_emitter/program_builder/field_visitor.dart
index 3ec4b45..240cb55 100644
--- a/pkg/compiler/lib/src/js_emitter/program_builder/field_visitor.dart
+++ b/pkg/compiler/lib/src/js_emitter/program_builder/field_visitor.dart
@@ -158,6 +158,6 @@
     // We never generate accessors for top-level/static fields.
     if (!member.isInstanceMember) return true;
     DartType type = _elementEnvironment.getFieldType(member);
-    return type.isTop;
+    return _closedWorld.dartTypes.isTopType(type);
   }
 }
diff --git a/pkg/compiler/lib/src/js_model/element_map_impl.dart b/pkg/compiler/lib/src/js_model/element_map_impl.dart
index 41c8758..dcbbbf2 100644
--- a/pkg/compiler/lib/src/js_model/element_map_impl.dart
+++ b/pkg/compiler/lib/src/js_model/element_map_impl.dart
@@ -141,10 +141,10 @@
       AnnotationsData annotations)
       : this.options = _elementMap.options {
     _elementEnvironment = new JsElementEnvironment(this);
-    _commonElements =
-        new CommonElementsImpl(_elementEnvironment, _elementMap.options);
     _typeConverter = new DartTypeConverter(this);
-    _types = new KernelDartTypes(this);
+    _types = new KernelDartTypes(this, options.useLegacySubtyping);
+    _commonElements = new CommonElementsImpl(
+        _types, _elementEnvironment, _elementMap.options);
     _constantValuefier = new ConstantValuefier(this);
 
     programEnv = _elementMap.env.convert();
@@ -321,9 +321,10 @@
   JsKernelToElementMap.readFromDataSource(this.options, this.reporter,
       this._environment, ir.Component component, DataSource source) {
     _elementEnvironment = new JsElementEnvironment(this);
-    _commonElements = new CommonElementsImpl(_elementEnvironment, options);
     _typeConverter = new DartTypeConverter(this);
-    _types = new KernelDartTypes(this);
+    _types = new KernelDartTypes(this, options.useLegacySubtyping);
+    _commonElements =
+        new CommonElementsImpl(_types, _elementEnvironment, options);
     _constantValuefier = new ConstantValuefier(this);
 
     source.registerComponentLookup(new ComponentLookup(component));
@@ -1816,7 +1817,7 @@
           new RecordContainerDefinition(getMemberDefinition(member).location),
           thisType,
           supertype,
-          getOrderedTypeSet(supertype.element).extendClass(thisType));
+          getOrderedTypeSet(supertype.element).extendClass(_types, thisType));
       classes.register(container, containerData, new RecordEnv(memberMap));
 
       InterfaceType memberThisType = member.enclosingClass != null
@@ -1878,7 +1879,7 @@
         new ClosureClassDefinition(location),
         thisType,
         supertype,
-        getOrderedTypeSet(supertype.element).extendClass(thisType));
+        getOrderedTypeSet(supertype.element).extendClass(_types, thisType));
     classes.register(classEntity, closureData, new ClosureClassEnv(memberMap));
 
     Local closureEntity;
diff --git a/pkg/compiler/lib/src/js_model/js_world_builder.dart b/pkg/compiler/lib/src/js_model/js_world_builder.dart
index 4382db5..0eec8fd 100644
--- a/pkg/compiler/lib/src/js_model/js_world_builder.dart
+++ b/pkg/compiler/lib/src/js_model/js_world_builder.dart
@@ -729,7 +729,8 @@
       }
       return null;
     }
-    return constant.accept(new _ConstantConverter(toBackendEntity), null);
+    return constant.accept(
+        new _ConstantConverter(_backend.types, toBackendEntity), null);
   }
 }
 
@@ -853,10 +854,11 @@
 }
 
 class _ConstantConverter implements ConstantValueVisitor<ConstantValue, Null> {
+  final DartTypes _dartTypes;
   final Entity Function(Entity) toBackendEntity;
   final _TypeConverter typeConverter;
 
-  _ConstantConverter(this.toBackendEntity)
+  _ConstantConverter(this._dartTypes, this.toBackendEntity)
       : typeConverter = new _TypeConverter();
 
   @override
@@ -952,14 +954,14 @@
   ConstantValue visitInterceptor(InterceptorConstantValue constant, _) {
     // Interceptor constants are only created in the SSA graph builder.
     throw new UnsupportedError(
-        "Unexpected visitInterceptor ${constant.toStructuredText()}");
+        "Unexpected visitInterceptor ${constant.toStructuredText(_dartTypes)}");
   }
 
   @override
   ConstantValue visitDeferredGlobal(DeferredGlobalConstantValue constant, _) {
     // Deferred global constants are only created in the SSA graph builder.
     throw new UnsupportedError(
-        "Unexpected DeferredGlobalConstantValue ${constant.toStructuredText()}");
+        "Unexpected DeferredGlobalConstantValue ${constant.toStructuredText(_dartTypes)}");
   }
 
   @override
diff --git a/pkg/compiler/lib/src/kernel/dart2js_target.dart b/pkg/compiler/lib/src/kernel/dart2js_target.dart
index 6c99e09..c91a030 100644
--- a/pkg/compiler/lib/src/kernel/dart2js_target.dart
+++ b/pkg/compiler/lib/src/kernel/dart2js_target.dart
@@ -6,11 +6,16 @@
 // on the dart2js internals.
 library compiler.src.kernel.dart2js_target;
 
+import 'package:_fe_analyzer_shared/src/messages/codes.dart'
+    show Message, LocatedMessage;
+import 'package:_js_interop_checks/js_interop_checks.dart';
 import 'package:kernel/ast.dart' as ir;
-import 'package:kernel/core_types.dart';
 import 'package:kernel/class_hierarchy.dart';
+import 'package:kernel/core_types.dart';
 import 'package:kernel/reference_from_index.dart';
+import 'package:kernel/target/changed_structure_notifier.dart';
 import 'package:kernel/target/targets.dart';
+
 import 'invocation_mirror_constants.dart';
 
 const Iterable<String> _allowedDartSchemePaths = const <String>[
@@ -88,7 +93,14 @@
       Map<String, String> environmentDefines,
       DiagnosticReporter diagnosticReporter,
       ReferenceFromIndex referenceFromIndex,
-      {void logger(String msg)}) {}
+      {void logger(String msg),
+      ChangedStructureNotifier changedStructureNotifier}) {
+    for (var library in libraries) {
+      JsInteropChecks(
+              diagnosticReporter as DiagnosticReporter<Message, LocatedMessage>)
+          .visitLibrary(library);
+    }
+  }
 
   @override
   ir.Expression instantiateInvocation(
diff --git a/pkg/compiler/lib/src/kernel/element_map_impl.dart b/pkg/compiler/lib/src/kernel/element_map_impl.dart
index e4a858b..d2559b7 100644
--- a/pkg/compiler/lib/src/kernel/element_map_impl.dart
+++ b/pkg/compiler/lib/src/kernel/element_map_impl.dart
@@ -119,9 +119,10 @@
   KernelToElementMapImpl(
       this.reporter, this._environment, this._frontendStrategy, this.options) {
     _elementEnvironment = new KernelElementEnvironment(this);
-    _commonElements = new CommonElementsImpl(_elementEnvironment, options);
     _typeConverter = new DartTypeConverter(this);
-    _types = new KernelDartTypes(this);
+    _types = new KernelDartTypes(this, options.useLegacySubtyping);
+    _commonElements =
+        new CommonElementsImpl(_types, _elementEnvironment, options);
     _constantValuefier = new ConstantValuefier(this);
   }
 
diff --git a/pkg/compiler/lib/src/kernel/kernel_impact.dart b/pkg/compiler/lib/src/kernel/kernel_impact.dart
index 315f648..1a75ffd 100644
--- a/pkg/compiler/lib/src/kernel/kernel_impact.dart
+++ b/pkg/compiler/lib/src/kernel/kernel_impact.dart
@@ -58,7 +58,8 @@
       VariableScopeModel variableScopeModel,
       this._annotations,
       this._constantValuefier)
-      : this.impactBuilder = new ResolutionWorldImpactBuilder(currentMember),
+      : this.impactBuilder = new ResolutionWorldImpactBuilder(
+            elementMap.commonElements.dartTypes, currentMember),
         super(staticTypeContext, elementMap.classHierarchy, variableScopeModel);
 
   @override
@@ -95,7 +96,8 @@
 
   KernelImpactConverter(this.elementMap, this.currentMember, this.reporter,
       this._options, this._constantValuefier, this.staticTypeContext)
-      : this.impactBuilder = new ResolutionWorldImpactBuilder(currentMember);
+      : this.impactBuilder = new ResolutionWorldImpactBuilder(
+            elementMap.commonElements.dartTypes, currentMember);
 
   @override
   ir.TypeEnvironment get typeEnvironment => elementMap.typeEnvironment;
@@ -124,6 +126,7 @@
   ResolutionWorldImpactBuilder get impactBuilder;
   ir.TypeEnvironment get typeEnvironment;
   CommonElements get commonElements;
+  DartTypes get dartTypes => commonElements.dartTypes;
   NativeBasicData get _nativeBasicData;
   ConstantValuefier get _constantValuefier;
   ir.StaticTypeContext get staticTypeContext;
@@ -171,9 +174,9 @@
       List<ConstantValue> metadata =
           elementMap.elementEnvironment.getMemberMetadata(member);
       Iterable<String> createsAnnotations =
-          getCreatesAnnotations(reporter, commonElements, metadata);
+          getCreatesAnnotations(dartTypes, reporter, commonElements, metadata);
       Iterable<String> returnsAnnotations =
-          getReturnsAnnotations(reporter, commonElements, metadata);
+          getReturnsAnnotations(dartTypes, reporter, commonElements, metadata);
       impactBuilder.registerNativeData(elementMap.getNativeBehaviorForFieldLoad(
           field, createsAnnotations, returnsAnnotations,
           isJsInterop: isJsInterop));
@@ -192,9 +195,9 @@
       List<ConstantValue> metadata =
           elementMap.elementEnvironment.getMemberMetadata(member);
       Iterable<String> createsAnnotations =
-          getCreatesAnnotations(reporter, commonElements, metadata);
+          getCreatesAnnotations(dartTypes, reporter, commonElements, metadata);
       Iterable<String> returnsAnnotations =
-          getReturnsAnnotations(reporter, commonElements, metadata);
+          getReturnsAnnotations(dartTypes, reporter, commonElements, metadata);
       impactBuilder.registerNativeData(elementMap.getNativeBehaviorForMethod(
           constructor, createsAnnotations, returnsAnnotations,
           isJsInterop: isJsInterop));
@@ -238,9 +241,9 @@
       List<ConstantValue> metadata =
           elementMap.elementEnvironment.getMemberMetadata(member);
       Iterable<String> createsAnnotations =
-          getCreatesAnnotations(reporter, commonElements, metadata);
+          getCreatesAnnotations(dartTypes, reporter, commonElements, metadata);
       Iterable<String> returnsAnnotations =
-          getReturnsAnnotations(reporter, commonElements, metadata);
+          getReturnsAnnotations(dartTypes, reporter, commonElements, metadata);
       impactBuilder.registerNativeData(elementMap.getNativeBehaviorForMethod(
           procedure, createsAnnotations, returnsAnnotations,
           isJsInterop: isJsInterop));
diff --git a/pkg/compiler/lib/src/kernel/native_basic_data.dart b/pkg/compiler/lib/src/kernel/native_basic_data.dart
index 5cc8d55..98a9541 100644
--- a/pkg/compiler/lib/src/kernel/native_basic_data.dart
+++ b/pkg/compiler/lib/src/kernel/native_basic_data.dart
@@ -32,8 +32,8 @@
     KCommonElements commonElements = elementMap.commonElements;
     String annotationName;
     for (ConstantValue value in metadata) {
-      String name = readAnnotationName(
-          spannable, value, commonElements.jsAnnotationClass,
+      String name = readAnnotationName(commonElements.dartTypes, spannable,
+          value, commonElements.jsAnnotationClass,
           defaultValue: '');
       if (annotationName == null) {
         annotationName = name;
diff --git a/pkg/compiler/lib/src/native/behavior.dart b/pkg/compiler/lib/src/native/behavior.dart
index 4329315..e02b89d 100644
--- a/pkg/compiler/lib/src/native/behavior.dart
+++ b/pkg/compiler/lib/src/native/behavior.dart
@@ -912,7 +912,7 @@
   }
 }
 
-List<String> _getAnnotations(DiagnosticReporter reporter,
+List<String> _getAnnotations(DartTypes dartTypes, DiagnosticReporter reporter,
     Iterable<ConstantValue> metadata, ClassEntity cls) {
   List<String> annotations = [];
   for (ConstantValue value in metadata) {
@@ -924,7 +924,7 @@
     // TODO(sra): Better validation of the constant.
     if (fields.length != 1 || !fields.single.isString) {
       reporter.internalError(CURRENT_ELEMENT_SPANNABLE,
-          'Annotations needs one string: ${value.toStructuredText()}');
+          'Annotations needs one string: ${value.toStructuredText(dartTypes)}');
     }
     StringConstantValue specStringConstant = fields.single;
     String specString = specStringConstant.stringValue;
@@ -933,14 +933,20 @@
   return annotations;
 }
 
-List<String> getCreatesAnnotations(DiagnosticReporter reporter,
-    CommonElements commonElements, Iterable<ConstantValue> metadata) {
+List<String> getCreatesAnnotations(
+    DartTypes dartTypes,
+    DiagnosticReporter reporter,
+    CommonElements commonElements,
+    Iterable<ConstantValue> metadata) {
   return _getAnnotations(
-      reporter, metadata, commonElements.annotationCreatesClass);
+      dartTypes, reporter, metadata, commonElements.annotationCreatesClass);
 }
 
-List<String> getReturnsAnnotations(DiagnosticReporter reporter,
-    CommonElements commonElements, Iterable<ConstantValue> metadata) {
+List<String> getReturnsAnnotations(
+    DartTypes dartTypes,
+    DiagnosticReporter reporter,
+    CommonElements commonElements,
+    Iterable<ConstantValue> metadata) {
   return _getAnnotations(
-      reporter, metadata, commonElements.annotationReturnsClass);
+      dartTypes, reporter, metadata, commonElements.annotationReturnsClass);
 }
diff --git a/pkg/compiler/lib/src/native/resolver.dart b/pkg/compiler/lib/src/native/resolver.dart
index e72f3ab..10b0f3f 100644
--- a/pkg/compiler/lib/src/native/resolver.dart
+++ b/pkg/compiler/lib/src/native/resolver.dart
@@ -8,6 +8,7 @@
 import '../common_elements.dart' show KElementEnvironment;
 import '../constants/values.dart';
 import '../elements/entities.dart';
+import '../elements/types.dart';
 import '../ir/annotations.dart';
 import '../js_backend/native_data.dart';
 
@@ -143,8 +144,8 @@
 
 /// Extracts the name if [value] is a named annotation based on
 /// [annotationClass], otherwise returns `null`.
-String readAnnotationName(
-    Spannable spannable, ConstantValue value, ClassEntity annotationClass,
+String readAnnotationName(DartTypes dartTypes, Spannable spannable,
+    ConstantValue value, ClassEntity annotationClass,
     {String defaultValue}) {
   if (!value.isConstructedObject) return null;
   ConstructedConstantValue constructedObject = value;
@@ -153,8 +154,8 @@
   Iterable<ConstantValue> fields = constructedObject.fields.values;
   // TODO(sra): Better validation of the constant.
   if (fields.length != 1) {
-    failedAt(
-        spannable, 'Annotations needs one string: ${value.toStructuredText()}');
+    failedAt(spannable,
+        'Annotations needs one string: ${value.toStructuredText(dartTypes)}');
     return null;
   } else if (fields.single is StringConstantValue) {
     StringConstantValue specStringConstant = fields.single;
@@ -162,8 +163,8 @@
   } else if (defaultValue != null && fields.single is NullConstantValue) {
     return defaultValue;
   } else {
-    failedAt(
-        spannable, 'Annotations needs one string: ${value.toStructuredText()}');
+    failedAt(spannable,
+        'Annotations needs one string: ${value.toStructuredText(dartTypes)}');
     return null;
   }
 }
diff --git a/pkg/compiler/lib/src/options.dart b/pkg/compiler/lib/src/options.dart
index 7abc5d5..99c5833 100644
--- a/pkg/compiler/lib/src/options.dart
+++ b/pkg/compiler/lib/src/options.dart
@@ -334,6 +334,12 @@
   /// weak or strong semantics.
   bool useWeakNullSafetySemantics = false;
 
+  /// Whether to use legacy subtype semantics rather than null-safe semantics.
+  /// This is `true` if null-safety is disabled, i.e. all code is legacy code,
+  /// or if weak null-safety semantics are being used, since we do not emit
+  /// warnings.
+  bool get useLegacySubtyping => !useNullSafety || useWeakNullSafetySemantics;
+
   /// The path to the file that contains the profiled allocations.
   ///
   /// The file must contain the Map that was produced by using
diff --git a/pkg/compiler/lib/src/ordered_typeset.dart b/pkg/compiler/lib/src/ordered_typeset.dart
index ce4ff17..d732744 100644
--- a/pkg/compiler/lib/src/ordered_typeset.dart
+++ b/pkg/compiler/lib/src/ordered_typeset.dart
@@ -98,9 +98,9 @@
   /// Creates a new [OrderedTypeSet] for [type] when it directly extends the
   /// class which this set represents. This is for instance used to create the
   /// type set for [ClosureClassElement] which extends [Closure].
-  OrderedTypeSet extendClass(InterfaceType type) {
+  OrderedTypeSet extendClass(DartTypes dartTypes, InterfaceType type) {
     assert(
-        types.head.treatAsRaw,
+        dartTypes.treatAsRawType(types.head),
         failedAt(
             type.element,
             'Cannot extend generic class ${types.head} using '
diff --git a/pkg/compiler/lib/src/resolution/registry.dart b/pkg/compiler/lib/src/resolution/registry.dart
index a7f9fa0..ff64822 100644
--- a/pkg/compiler/lib/src/resolution/registry.dart
+++ b/pkg/compiler/lib/src/resolution/registry.dart
@@ -7,6 +7,7 @@
 import '../common/resolution.dart' show ResolutionImpact;
 import '../constants/values.dart';
 import '../elements/entities.dart' show ClassEntity, MemberEntity;
+import '../elements/types.dart';
 import '../universe/feature.dart';
 import '../universe/world_impact.dart' show WorldImpact, WorldImpactBuilderImpl;
 import '../util/enumset.dart' show EnumSet;
@@ -14,6 +15,7 @@
 
 class ResolutionWorldImpactBuilder extends WorldImpactBuilderImpl
     implements ResolutionImpact {
+  final DartTypes _dartTypes;
   @override
   final MemberEntity member;
   EnumSet<Feature> _features;
@@ -27,7 +29,7 @@
   Set<RuntimeTypeUse> _runtimeTypeUses;
   Set<GenericInstantiation> _genericInstantiations;
 
-  ResolutionWorldImpactBuilder(this.member);
+  ResolutionWorldImpactBuilder(this._dartTypes, this.member);
 
   @override
   bool get isEmpty => false;
@@ -174,7 +176,7 @@
     if (_constantLiterals != null) {
       sb.write('\n const-literals:');
       for (ConstantValue constant in _constantLiterals) {
-        sb.write('\n  ${constant.toDartText()}');
+        sb.write('\n  ${constant.toDartText(_dartTypes)}');
       }
     }
     if (_constSymbolNames != null) {
diff --git a/pkg/compiler/lib/src/ssa/builder_kernel.dart b/pkg/compiler/lib/src/ssa/builder_kernel.dart
index 409aac3..87c7c5a 100644
--- a/pkg/compiler/lib/src/ssa/builder_kernel.dart
+++ b/pkg/compiler/lib/src/ssa/builder_kernel.dart
@@ -217,7 +217,7 @@
 
   InferredData get _inferredData => globalInferenceResults.inferredData;
 
-  DartTypes get types => closedWorld.dartTypes;
+  DartTypes get dartTypes => closedWorld.dartTypes;
 
   void push(HInstruction instruction) {
     add(instruction);
@@ -387,6 +387,8 @@
         return options.useNewRti;
       case 'VARIANCE':
         return options.enableVariance;
+      case 'LEGACY':
+        return options.useLegacySubtyping;
       default:
         return null;
     }
@@ -602,7 +604,7 @@
       // Use dynamic type because the type computed by the inferrer is
       // narrowed to the type annotation.
       HInstruction parameter =
-          new HParameterValue(field, _abstractValueDomain.dynamicType);
+          HParameterValue(field, _abstractValueDomain.dynamicType);
       // Add the parameter as the last instruction of the entry block.
       // If the method is intercepted, we want the actual receiver
       // to be the first parameter.
@@ -615,7 +617,7 @@
       // possibly its type but not the initializer.
       value.sourceInformation ??= _sourceInformationBuilder.buildSet(node);
       if (!_fieldAnalysis.getFieldData(field).isElided) {
-        add(new HFieldSet(_abstractValueDomain, field, thisInstruction, value));
+        add(HFieldSet(_abstractValueDomain, field, thisInstruction, value));
       }
     } else {
       if (node.initializer != null) {
@@ -629,7 +631,7 @@
         stack.add(graph.addConstantNull(closedWorld));
       }
       HInstruction value = pop();
-      _closeAndGotoExit(new HReturn(_abstractValueDomain, value,
+      _closeAndGotoExit(HReturn(_abstractValueDomain, value,
           _sourceInformationBuilder.buildReturn(node)));
     }
     _closeFunction();
@@ -1266,7 +1268,7 @@
         _elementMap.getFunctionType(originalClosureNode);
     HInstruction rti =
         _typeBuilder.analyzeTypeArgumentNewRti(functionType, sourceElement);
-    close(new HReturn(_abstractValueDomain, rti,
+    close(HReturn(_abstractValueDomain, rti,
             _sourceInformationBuilder.buildReturn(originalClosureNode)))
         .addSuccessor(graph.exit);
     _closeFunction();
@@ -1310,7 +1312,7 @@
                   null, _abstractValueDomain.boolType));
             },
             visitThen: () {
-              _closeAndGotoExit(new HReturn(
+              _closeAndGotoExit(HReturn(
                   _abstractValueDomain,
                   graph.addConstantBool(false, closedWorld),
                   _sourceInformationBuilder.buildReturn(functionNode)));
@@ -1416,8 +1418,7 @@
         _abstractValueDomain.dynamicType, // TODO: better type.
         sourceInformation));
 
-    _closeAndGotoExit(
-        new HReturn(_abstractValueDomain, pop(), sourceInformation));
+    _closeAndGotoExit(HReturn(_abstractValueDomain, pop(), sourceInformation));
 
     _closeFunction();
   }
@@ -1527,43 +1528,34 @@
     }
   }
 
-  /// Builds a SSA graph for FunctionNodes of external methods.
+  /// Builds a SSA graph for FunctionNodes of external methods. This produces a
+  /// graph for a method with Dart calling conventions that forwards to the
+  /// actual external method.
   void _buildExternalFunctionNode(
       FunctionEntity function, ir.FunctionNode functionNode) {
-    // TODO(johnniwinther): Non-js-interop external functions should
-    // throw a runtime error.
     assert(functionNode.body == null);
+
+    bool isJsInterop = closedWorld.nativeData.isJsInteropMember(function);
+
     _openFunction(function,
         functionNode: functionNode,
         parameterStructure: function.parameterStructure,
         checks: _checksForFunction(function));
 
     if (closedWorld.nativeData.isNativeMember(targetElement)) {
-      registry.registerNativeMethod(targetElement);
-      String nativeName;
-      if (closedWorld.nativeData.hasFixedBackendName(targetElement)) {
-        nativeName = closedWorld.nativeData.getFixedBackendName(targetElement);
-      } else {
-        nativeName = targetElement.name;
-      }
-
-      String templateReceiver = '';
-      List<String> templateArguments = <String>[];
-      List<HInstruction> inputs = <HInstruction>[];
+      List<HInstruction> inputs = [];
       if (targetElement.isInstanceMember) {
-        templateReceiver = '#.';
         inputs.add(localsHandler.readThis(
             sourceInformation:
                 _sourceInformationBuilder.buildGet(functionNode)));
       }
 
       void handleParameter(ir.VariableDeclaration param) {
-        templateArguments.add('#');
         Local local = _localsMap.getLocalVariable(param);
         // Convert Dart function to JavaScript function.
         HInstruction argument = localsHandler.readLocal(local);
         ir.DartType type = param.type;
-        if (type is ir.FunctionType) {
+        if (!isJsInterop && type is ir.FunctionType) {
           int arity = type.positionalParameters.length;
           _pushStaticInvocation(
               _commonElements.closureConverter,
@@ -1593,32 +1585,22 @@
         namedParameters.forEach(handleParameter);
       }
 
-      String arguments = templateArguments.join(',');
+      NativeBehavior nativeBehavior =
+          _nativeData.getNativeMethodBehavior(function);
+      AbstractValue returnType =
+          _typeInferenceMap.typeFromNativeBehavior(nativeBehavior, closedWorld);
 
-      // TODO(sra): Use declared type or NativeBehavior type.
-      AbstractValue typeMask = _abstractValueDomain.dynamicType;
-      String template;
-      if (targetElement.isGetter) {
-        template = '${templateReceiver}$nativeName';
-      } else if (targetElement.isSetter) {
-        template = '${templateReceiver}$nativeName = ${arguments}';
-      } else {
-        template = '${templateReceiver}$nativeName(${arguments})';
-      }
-
-      push(new HForeignCode(
-          js.js.uncachedExpressionTemplate(template), typeMask, inputs,
-          effects: new SideEffects()));
+      push(HInvokeExternal(targetElement, inputs, returnType, nativeBehavior,
+          sourceInformation: null));
       // TODO(johnniwinther): Provide source information.
       HInstruction value = pop();
       if (targetElement.isSetter) {
-        value = graph.addConstantNull(closedWorld);
+        _closeAndGotoExit(HGoto(_abstractValueDomain));
+      } else {
+        _emitReturn(value, _sourceInformationBuilder.buildReturn(functionNode));
       }
-      close(new HReturn(_abstractValueDomain, value,
-              _sourceInformationBuilder.buildReturn(functionNode)))
-          .addSuccessor(graph.exit);
     }
-    // TODO(sra): Handle JS-interop methods.
+
     _closeFunction();
   }
 
@@ -1824,10 +1806,8 @@
   void visitReturnStatement(ir.ReturnStatement node) {
     SourceInformation sourceInformation =
         _sourceInformationBuilder.buildReturn(node);
-    HInstruction value;
-    if (node.expression == null) {
-      value = graph.addConstantNull(closedWorld);
-    } else {
+    HInstruction value = null;
+    if (node.expression != null) {
       node.expression.accept(this);
       value = pop();
       if (_currentFrame.asyncMarker == AsyncMarker.ASYNC) {
@@ -3128,7 +3108,8 @@
   /// Set the runtime type information if necessary.
   HInstruction _setListRuntimeTypeInfoIfNeeded(HInstruction object,
       InterfaceType type, SourceInformation sourceInformation) {
-    if (!_rtiNeed.classNeedsTypeArguments(type.element) || type.treatAsRaw) {
+    if (!_rtiNeed.classNeedsTypeArguments(type.element) ||
+        dartTypes.treatAsRawType(type)) {
       return object;
     }
     if (options.useNewRti) {
@@ -4065,7 +4046,7 @@
         localsHandler.substInContext(_elementMap.getDartType(type));
     if (typeValue is! InterfaceType) return false;
     InterfaceType interfaceType = typeValue;
-    if (!interfaceType.treatAsRaw) return false;
+    if (!dartTypes.treatAsRawType(interfaceType)) return false;
 
     ClassEntity cls = interfaceType.element;
     InterfaceType thisType = _elementEnvironment.getThisType(cls);
@@ -4853,21 +4834,21 @@
       return;
     }
 
-    var instruction;
     if (closedWorld.nativeData.isJsInteropMember(target)) {
-      instruction = _invokeJsInteropFunction(target, arguments);
-    } else {
-      instruction = new HInvokeStatic(
-          target, arguments, typeMask, typeArguments,
-          targetCanThrow: !_inferredData.getCannotThrow(target))
-        ..sourceInformation = sourceInformation;
-
-      if (_currentImplicitInstantiations.isNotEmpty) {
-        instruction.instantiatedTypes =
-            new List<InterfaceType>.from(_currentImplicitInstantiations);
-      }
-      instruction.sideEffects = _inferredData.getSideEffectsOfElement(target);
+      push(_invokeJsInteropFunction(target, arguments));
+      return;
     }
+
+    HInvokeStatic instruction = new HInvokeStatic(
+        target, arguments, typeMask, typeArguments,
+        targetCanThrow: !_inferredData.getCannotThrow(target))
+      ..sourceInformation = sourceInformation;
+
+    if (_currentImplicitInstantiations.isNotEmpty) {
+      instruction.instantiatedTypes =
+          new List<InterfaceType>.from(_currentImplicitInstantiations);
+    }
+    instruction.sideEffects = _inferredData.getSideEffectsOfElement(target);
     push(instruction);
   }
 
@@ -4968,10 +4949,9 @@
     }
   }
 
-  HForeignCode _invokeJsInteropFunction(
+  HInstruction _invokeJsInteropFunction(
       FunctionEntity element, List<HInstruction> arguments) {
     assert(closedWorld.nativeData.isJsInteropMember(element));
-    registry.registerNativeMethod(element);
 
     if (element is ConstructorEntity &&
         element.isFactoryConstructor &&
@@ -5014,25 +4994,18 @@
             _elementEnvironment.getThisType(constructor.enclosingClass);
         nativeBehavior.typesReturned.add(thisType);
       }
+      registry.registerNativeMethod(element);
       // TODO(efortuna): Source information.
       return new HForeignCode(
           codeTemplate, _abstractValueDomain.dynamicType, filteredArguments,
           nativeBehavior: nativeBehavior);
     }
 
-    var target = new HForeignCode(
-        js.js
-            .parseForeignJS("${_nativeData.getFixedBackendMethodPath(element)}."
-                "${_nativeData.getFixedBackendName(element)}"),
-        _abstractValueDomain.dynamicType,
-        <HInstruction>[]);
-    add(target);
     // Strip off trailing arguments that were not specified.
     // we could assert that the trailing arguments are all null.
     // TODO(jacobr): rewrite named arguments to an object literal matching
     // the factory constructor case.
-    arguments = arguments.where((arg) => arg != null).toList();
-    var inputs = <HInstruction>[target]..addAll(arguments);
+    List<HInstruction> inputs = arguments.where((arg) => arg != null).toList();
 
     var nativeBehavior = new NativeBehavior()..sideEffects.setAllSideEffects();
 
@@ -5060,22 +5033,12 @@
           .getThisType(_commonElements.jsJavaScriptObjectClass));
     }
 
-    String template;
-    if (element.isGetter) {
-      template = '#';
-    } else if (element.isSetter) {
-      template = '# = #';
-    } else {
-      var args = new List.filled(arguments.length, '#').join(',');
-      template = element.isConstructor ? "new #($args)" : "#($args)";
-    }
-    js.Template codeTemplate = js.js.parseForeignJS(template);
-    nativeBehavior.codeTemplate = codeTemplate;
+    AbstractValue instructionType =
+        _typeInferenceMap.typeFromNativeBehavior(nativeBehavior, closedWorld);
 
     // TODO(efortuna): Add source information.
-    return new HForeignCode(
-        codeTemplate, _abstractValueDomain.dynamicType, inputs,
-        nativeBehavior: nativeBehavior);
+    return HInvokeExternal(element, inputs, instructionType, nativeBehavior,
+        sourceInformation: null);
   }
 
   @override
@@ -5471,7 +5434,7 @@
     DartType typeValue =
         localsHandler.substInContext(_elementMap.getDartType(type));
 
-    if (typeValue.isTop) {
+    if (dartTypes.isTopType(typeValue)) {
       stack.add(graph.addConstantBool(true, closedWorld));
       return;
     }
@@ -5604,7 +5567,7 @@
     List<DartType> bounds = thisType.typeArguments;
     for (int i = 0; i < bounds.length; i++) {
       DartType arg = type.typeArguments[i];
-      if (arg.isTop) continue;
+      if (dartTypes.isTopType(arg)) continue;
       TypeVariableType typeVariable = bounds[i];
       DartType bound =
           _elementEnvironment.getTypeVariableBound(typeVariable.element);
@@ -6268,11 +6231,13 @@
     return currentNode is ir.ForInStatement;
   }
 
-  void _emitReturn(HInstruction value, SourceInformation sourceInformation) {
+  void _emitReturn(
+      HInstruction /*?*/ value, SourceInformation sourceInformation) {
     if (_inliningStack.isEmpty) {
       _closeAndGotoExit(
-          new HReturn(_abstractValueDomain, value, sourceInformation));
+          HReturn(_abstractValueDomain, value, sourceInformation));
     } else {
+      value ??= graph.addConstantNull(closedWorld);
       localsHandler.updateLocal(_returnLocal, value);
     }
   }
diff --git a/pkg/compiler/lib/src/ssa/codegen.dart b/pkg/compiler/lib/src/ssa/codegen.dart
index faa0413..0bef2b6 100644
--- a/pkg/compiler/lib/src/ssa/codegen.dart
+++ b/pkg/compiler/lib/src/ssa/codegen.dart
@@ -736,17 +736,36 @@
     }
   }
 
+  HInstruction skipGenerateAtUseCheckInputs(HCheck check) {
+    HInstruction input = check.checkedInput;
+    if (input is HCheck && isGenerateAtUseSite(input)) {
+      return skipGenerateAtUseCheckInputs(input);
+    }
+    return input;
+  }
+
   void use(HInstruction argument) {
     if (isGenerateAtUseSite(argument)) {
       visitExpression(argument);
     } else if (argument is HCheck && !variableNames.hasName(argument)) {
+      // We have a check that is not generate-at-use and has no name, yet is a
+      // subexpression (we are in 'use'). This happens when we have a chain of
+      // checks on an available unnamed value (e.g. a constant). The checks are
+      // generated as a statement, so we need to skip the generate-at-use check
+      // tree to find the underlying value.
+
+      // TODO(sra): We should ensure that this invariant holds: "every
+      // instruction has a name or is generate-at-use". This would require
+      // naming the input or output of the chain-of-checks.
+
       HCheck check = argument;
-      // This can only happen if the checked node does not have a name.
+      // This can only happen if the checked node also does not have a name.
       assert(!variableNames.hasName(check.checkedInput));
-      use(check.checkedInput);
+
+      use(skipGenerateAtUseCheckInputs(check));
     } else {
       assert(variableNames.hasName(argument));
-      push(new js.VariableUse(variableNames.getName(argument)));
+      push(js.VariableUse(variableNames.getName(argument)));
     }
   }
 
@@ -1861,13 +1880,6 @@
         _registry
             // ignore:deprecated_member_use_from_same_package
             .registerInstantiatedClass(_commonElements.listClass);
-      } else if (_nativeData.isNativeMember(target) &&
-          target.isFunction &&
-          !node.isInterceptedCall) {
-        // A direct (i.e. non-interceptor) native call is the result of
-        // optimization.  The optimization ensures any type checks or
-        // conversions have been satisfied.
-        methodName = _nativeData.getFixedBackendName(target);
       }
     }
 
@@ -2284,6 +2296,88 @@
         variableNames.getName(node.receiver), pop(), node.sourceInformation);
   }
 
+  @override
+  visitInvokeExternal(HInvokeExternal node) {
+    FunctionEntity target = node.element;
+    List<HInstruction> inputs = node.inputs;
+
+    assert(_nativeData.isNativeMember(target), 'non-native target: $node');
+
+    String targetName = _nativeData.hasFixedBackendName(target)
+        ? _nativeData.getFixedBackendName(target)
+        : target.name;
+
+    void invokeWithJavaScriptReceiver(js.Expression receiverExpression) {
+      // JS-interop target names can be paths ("a.b"), so we parse them to
+      // re-associate the property accesses ("#.a.b" is `dot(dot(#,'a'),'b')`).
+      //
+      // Native target names are simple identifiers, so re-parsing is not
+      // necessary, but it is simpler to use the same code.
+      String template;
+      List templateInputs;
+      if (target.isGetter) {
+        template = '#.$targetName';
+        templateInputs = [receiverExpression];
+      } else if (target.isSetter) {
+        assert(inputs.length == (target.isInstanceMember ? 2 : 1));
+        use(inputs.last);
+        template = '#.$targetName = #';
+        templateInputs = [receiverExpression, pop()];
+      } else {
+        var arguments =
+            visitArguments(inputs, start: target.isInstanceMember ? 1 : 0);
+        template =
+            target.isConstructor ? 'new #.$targetName(#)' : '#.$targetName(#)';
+        templateInputs = [receiverExpression, arguments];
+      }
+      js.Expression expression = js.js
+          .uncachedExpressionTemplate(template)
+          .instantiate(templateInputs);
+      push(expression.withSourceInformation(node.sourceInformation));
+      _registry.registerNativeMethod(target);
+    }
+
+    if (_nativeData.isJsInteropMember(target)) {
+      if (target.isStatic || target.isTopLevel || target.isConstructor) {
+        String path = _nativeData.getFixedBackendMethodPath(target);
+        js.Expression pathExpression =
+            js.js.uncachedExpressionTemplate(path).instantiate([]);
+        invokeWithJavaScriptReceiver(pathExpression);
+        return;
+      }
+    }
+
+    if (_nativeData.isNativeMember(target)) {
+      _registry.registerNativeBehavior(node.nativeBehavior);
+      if (target.isInstanceMember) {
+        HInstruction receiver = inputs.first;
+        use(receiver);
+        invokeWithJavaScriptReceiver(pop());
+        return;
+      }
+      if (target.isStatic || target.isTopLevel) {
+        var arguments = visitArguments(inputs, start: 0);
+        js.Expression targeExpression =
+            js.js.uncachedExpressionTemplate(targetName).instantiate([]);
+        js.Expression expression;
+        if (target.isGetter) {
+          expression = targeExpression;
+        } else if (target.isSetter) {
+          expression = js.js('# = #', [targeExpression, inputs.single]);
+        } else {
+          assert(target.isFunction);
+          expression = js.js('#(#)', [targeExpression, arguments]);
+        }
+        push(expression.withSourceInformation(node.sourceInformation));
+        _registry.registerNativeMethod(target);
+        return;
+      }
+
+      failedAt(node, 'codegen not implemented (non-instance-member): $node');
+    }
+    failedAt(node, 'unexpected target: $node');
+  }
+
   void registerForeignTypes(HForeign node) {
     NativeBehavior nativeBehavior = node.nativeBehavior;
     if (nativeBehavior == null) return;
@@ -2499,15 +2593,12 @@
 
   @override
   visitReturn(HReturn node) {
-    assert(node.inputs.length == 1);
-    HInstruction input = node.inputs[0];
-    if (input.isConstantNull()) {
-      pushStatement(
-          new js.Return().withSourceInformation(node.sourceInformation));
+    if (node.inputs.isEmpty) {
+      pushStatement(js.Return().withSourceInformation(node.sourceInformation));
     } else {
-      use(node.inputs[0]);
+      use(node.inputs.single);
       pushStatement(
-          new js.Return(pop()).withSourceInformation(node.sourceInformation));
+          js.Return(pop()).withSourceInformation(node.sourceInformation));
     }
   }
 
diff --git a/pkg/compiler/lib/src/ssa/codegen_helpers.dart b/pkg/compiler/lib/src/ssa/codegen_helpers.dart
index 5283f94..071c7fb 100644
--- a/pkg/compiler/lib/src/ssa/codegen_helpers.dart
+++ b/pkg/compiler/lib/src/ssa/codegen_helpers.dart
@@ -120,6 +120,9 @@
         }
       }
 
+      if (current is HInvokeExternal) {
+        if (current.isNullGuardFor(nullCheck)) return current;
+      }
       if (current is HForeignCode) {
         if (current.isNullGuardFor(nullCheck)) return current;
       }
@@ -602,7 +605,7 @@
           continue;
         }
       } else if (current is HReturn) {
-        if (current.inputs.single == value) {
+        if (current.inputs.isNotEmpty && current.inputs.single == value) {
           current.changeUse(value, chain);
           return current.next;
         }
@@ -1312,11 +1315,9 @@
 
       if (instruction is HInvoke) return true;
       if (instruction is HCreate) return true;
+      if (instruction is HReturn) return true;
       if (instruction is HPhi) return true;
 
-      // We return `null` by removing the return expression or statement.
-      if (instruction is HReturn) return false;
-
       // JavaScript `x == null` is more efficient than `x == _null`.
       if (instruction is HIdentity) return false;
 
diff --git a/pkg/compiler/lib/src/ssa/logging.dart b/pkg/compiler/lib/src/ssa/logging.dart
index 5fc74e2..c60de58 100644
--- a/pkg/compiler/lib/src/ssa/logging.dart
+++ b/pkg/compiler/lib/src/ssa/logging.dart
@@ -3,11 +3,16 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import '../elements/entities.dart';
+import '../elements/types.dart';
 import 'package:_fe_analyzer_shared/src/testing/features.dart';
 import 'nodes.dart';
 
 /// Log used for unit testing optimizations.
 class OptimizationTestLog {
+  final DartTypes _dartTypes;
+
+  OptimizationTestLog(this._dartTypes);
+
   List<OptimizationLogEntry> entries = [];
 
   Map<String, Set<HInstruction>> _unconverted;
@@ -76,7 +81,7 @@
       HInvokeDynamicGetter original, FieldEntity field, HConstant converted) {
     Features features = new Features();
     features['name'] = '${field.enclosingClass.name}.${field.name}';
-    features['value'] = converted.constant.toStructuredText();
+    features['value'] = converted.constant.toStructuredText(_dartTypes);
     entries.add(new OptimizationLogEntry('ConstantFieldGet', features));
   }
 
@@ -84,7 +89,7 @@
       HInvokeDynamicMethod original, FieldEntity field, HConstant converted) {
     Features features = new Features();
     features['name'] = '${field.enclosingClass.name}.${field.name}';
-    features['value'] = converted.constant.toStructuredText();
+    features['value'] = converted.constant.toStructuredText(_dartTypes);
     entries.add(new OptimizationLogEntry('ConstantFieldCall', features));
   }
 
@@ -202,7 +207,7 @@
   void registerCompareTo(HInvokeDynamic original, [HConstant converted]) {
     Features features = new Features();
     if (converted != null) {
-      features['constant'] = converted.constant.toDartText();
+      features['constant'] = converted.constant.toDartText(_dartTypes);
     }
     entries.add(new OptimizationLogEntry('CompareTo', features));
   }
diff --git a/pkg/compiler/lib/src/ssa/nodes.dart b/pkg/compiler/lib/src/ssa/nodes.dart
index 3cad724..0dbb1eb 100644
--- a/pkg/compiler/lib/src/ssa/nodes.dart
+++ b/pkg/compiler/lib/src/ssa/nodes.dart
@@ -45,6 +45,7 @@
   R visitExitTry(HExitTry node);
   R visitFieldGet(HFieldGet node);
   R visitFieldSet(HFieldSet node);
+  R visitInvokeExternal(HInvokeExternal node);
   R visitForeignCode(HForeignCode node);
   R visitGetLength(HGetLength node);
   R visitGoto(HGoto node);
@@ -470,6 +471,8 @@
   @override
   visitFieldSet(HFieldSet node) => visitFieldAccess(node);
   @override
+  visitInvokeExternal(HInvokeExternal node) => visitInstruction(node);
+  @override
   visitForeignCode(HForeignCode node) => visitInstruction(node);
   @override
   visitGetLength(HGetLength node) => visitInstruction(node);
@@ -1042,11 +1045,11 @@
   Entity sourceElement;
   SourceInformation sourceInformation;
 
-  final int id;
+  final int id = idCounter++;
   static int idCounter;
 
   final List<HInstruction> inputs;
-  final List<HInstruction> usedBy;
+  final List<HInstruction> usedBy = [];
 
   HBasicBlock block;
   HInstruction previous = null;
@@ -1095,27 +1098,26 @@
   static const int TYPE_INFO_READ_VARIABLE_TYPECODE = 39;
   static const int TYPE_INFO_EXPRESSION_TYPECODE = 40;
 
-  static const int FOREIGN_CODE_TYPECODE = 41;
-  static const int REMAINDER_TYPECODE = 42;
-  static const int GET_LENGTH_TYPECODE = 43;
-  static const int ABS_TYPECODE = 44;
-  static const int BOOL_CONVERSION_TYPECODE = 45;
-  static const int NULL_CHECK_TYPECODE = 46;
-  static const int PRIMITIVE_CHECK_TYPECODE = 47;
+  static const int INVOKE_EXTERNAL_TYPECODE = 41;
+  static const int FOREIGN_CODE_TYPECODE = 42;
+  static const int REMAINDER_TYPECODE = 43;
+  static const int GET_LENGTH_TYPECODE = 44;
+  static const int ABS_TYPECODE = 45;
+  static const int BOOL_CONVERSION_TYPECODE = 46;
+  static const int NULL_CHECK_TYPECODE = 47;
+  static const int PRIMITIVE_CHECK_TYPECODE = 48;
 
-  static const int IS_TEST_TYPECODE = 48;
-  static const int IS_TEST_SIMPLE_TYPECODE = 49;
-  static const int AS_CHECK_TYPECODE = 50;
-  static const int AS_CHECK_SIMPLE_TYPECODE = 51;
-  static const int SUBTYPE_CHECK_TYPECODE = 52;
-  static const int LOAD_TYPE_TYPECODE = 53;
-  static const int INSTANCE_ENVIRONMENT_TYPECODE = 54;
-  static const int TYPE_EVAL_TYPECODE = 55;
-  static const int TYPE_BIND_TYPECODE = 56;
+  static const int IS_TEST_TYPECODE = 49;
+  static const int IS_TEST_SIMPLE_TYPECODE = 50;
+  static const int AS_CHECK_TYPECODE = 51;
+  static const int AS_CHECK_SIMPLE_TYPECODE = 52;
+  static const int SUBTYPE_CHECK_TYPECODE = 53;
+  static const int LOAD_TYPE_TYPECODE = 54;
+  static const int INSTANCE_ENVIRONMENT_TYPECODE = 55;
+  static const int TYPE_EVAL_TYPECODE = 56;
+  static const int TYPE_BIND_TYPECODE = 57;
 
-  HInstruction(this.inputs, this.instructionType)
-      : id = idCounter++,
-        usedBy = <HInstruction>[] {
+  HInstruction(this.inputs, this.instructionType) {
     assert(inputs.every((e) => e != null), "inputs: $inputs");
   }
 
@@ -1408,7 +1410,7 @@
     // instructions with generics. It has the generic type context
     // available.
     assert(type is! TypeVariableType);
-    assert(type.treatAsRaw || type is FunctionType);
+    assert(closedWorld.dartTypes.treatAsRawType(type) || type is FunctionType);
     if (type is DynamicType) return this;
     if (type is VoidType) return this;
     if (type == closedWorld.commonElements.objectType) return this;
@@ -1417,7 +1419,8 @@
           closedWorld.abstractValueDomain.dynamicType, this, sourceInformation);
     }
     assert(type is InterfaceType);
-    if (kind == HTypeConversion.TYPE_CHECK && !type.treatAsRaw) {
+    if (kind == HTypeConversion.TYPE_CHECK &&
+        !closedWorld.dartTypes.treatAsRawType(type)) {
       throw 'creating compound check to $type (this = ${this})';
     } else {
       InterfaceType interfaceType = type;
@@ -1829,6 +1832,8 @@
     // Use the name and the kind instead of [Selector.operator==]
     // because we don't need to check the arity (already checked in
     // [gvnEquals]), and the receiver types may not be in sync.
+    // TODO(sra): If we GVN calls with named (optional) arguments then the
+    // selector needs a deeper check for the same subset of named arguments.
     return selector.name == other.selector.name &&
         selector.kind == other.selector.kind;
   }
@@ -2297,6 +2302,100 @@
   bool isJsStatement() => true;
 }
 
+/// Invocation of a native or JS-interop method.
+///
+/// Includes various invocations where the JavaScript form is similar to the
+/// Dart form:
+///
+///     receiver.property          // An instance getter
+///     receiver.property = value  // An instance setter
+///     receiver.method(arg)       // An instance method
+///
+///     Class.property             // A static getter
+///     Class.property = value     // A static setter
+///     Class.method(arg)          // A static method
+///     new Class(arg)             // A constructor
+///
+/// HInvokeDynamicMethod can be lowered to HInvokeExternal with the same
+/// [element]. The difference is a HInvokeDynamicMethod is a call to a
+/// Dart-calling-convention stub identifed by [element] that contains a call to
+/// the external method, whereas a HInvokeExternal instruction is a direct
+/// JavaScript call to the external method identified by [element].
+class HInvokeExternal extends HInvoke {
+  final FunctionEntity element;
+
+  // The following fields are functions of [element] that are extracted for
+  // convenience.
+  final NativeBehavior nativeBehavior;
+  final NativeThrowBehavior throwBehavior;
+
+  HInvokeExternal(this.element, List<HInstruction> inputs, AbstractValue type,
+      this.nativeBehavior,
+      {SourceInformation sourceInformation})
+      : throwBehavior =
+            nativeBehavior?.throwBehavior ?? NativeThrowBehavior.MAY,
+        super(inputs, type) {
+    if (nativeBehavior == null) {
+      sideEffects.setAllSideEffects();
+      sideEffects.setDependsOnSomething();
+    } else {
+      sideEffects.add(nativeBehavior.sideEffects);
+    }
+    if (nativeBehavior != null && nativeBehavior.useGvn) {
+      setUseGvn();
+    }
+    this.sourceInformation = sourceInformation;
+  }
+
+  @override
+  accept(HVisitor visitor) => visitor.visitInvokeExternal(this);
+
+  @override
+  bool isJsStatement() => false;
+
+  @override
+  bool canThrow(AbstractValueDomain domain) {
+    if (element.isInstanceMember) {
+      if (inputs.length > 0) {
+        return inputs.first.isNull(domain).isPotentiallyTrue
+            ? throwBehavior.canThrow
+            : throwBehavior.onNonNull.canThrow;
+      }
+    }
+    return throwBehavior.canThrow;
+  }
+
+  @override
+  bool onlyThrowsNSM() => throwBehavior.isOnlyNullNSMGuard;
+
+  @override
+  bool isAllocation(AbstractValueDomain domain) =>
+      nativeBehavior != null &&
+      nativeBehavior.isAllocation &&
+      this.isNull(domain).isDefinitelyFalse;
+
+  /// Returns `true` if the call will throw an NoSuchMethod error if [receiver]
+  /// is `null` before having any other side-effects.
+  bool isNullGuardFor(HInstruction receiver) {
+    if (!element.isInstanceMember) return false;
+    if (inputs.length < 1) return false;
+    if (inputs.first.nonCheck() != receiver.nonCheck()) return false;
+    return true;
+  }
+
+  @override
+  int typeCode() => HInstruction.INVOKE_EXTERNAL_TYPECODE;
+  @override
+  bool typeEquals(other) => other is HInvokeExternal;
+  @override
+  bool dataEquals(HInvokeExternal other) {
+    return element == other.element;
+  }
+
+  @override
+  String toString() => 'HInvokeExternal($element)';
+}
+
 abstract class HForeign extends HInstruction {
   HForeign(AbstractValue type, List<HInstruction> inputs) : super(inputs, type);
 
@@ -2842,7 +2941,7 @@
       : super(<HInstruction>[], constantType);
 
   @override
-  toString() => 'literal: ${constant.toStructuredText()}';
+  toString() => 'literal: ${constant.toStructuredText(null)}';
   @override
   accept(HVisitor visitor) => visitor.visitConstant(this);
 
@@ -3093,10 +3192,11 @@
   bool dataEquals(HInstruction other) => true;
 }
 
+/// Return statement, either with or without a value.
 class HReturn extends HControlFlow {
-  HReturn(AbstractValueDomain domain, HInstruction value,
+  HReturn(AbstractValueDomain domain, HInstruction /*?*/ value,
       SourceInformation sourceInformation)
-      : super(domain, <HInstruction>[value]) {
+      : super(domain, [if (value != null) value]) {
     this.sourceInformation = sourceInformation;
   }
   @override
@@ -3659,7 +3759,7 @@
         // TODO(johnniwinther): Optimize FutureOr type conversions.
         return false;
       }
-      if (!type.treatAsRaw) {
+      if (!closedWorld.dartTypes.treatAsRawType(type)) {
         // `null` always passes type conversion.
         if (checkedInput.isNull(abstractValueDomain).isDefinitelyTrue) {
           return true;
@@ -4513,7 +4613,7 @@
   // Currently, the abstract value domain cannot (soundly) state that an is-test
   // is definitely false, so we reuse some of the case-by-case logic from the
   // old [HIs] optimization.
-  if (dartType.isTop) return AbstractBool.True;
+  if (closedWorld.dartTypes.isTopType(dartType)) return AbstractBool.True;
   if (dartType is! InterfaceType) return AbstractBool.Maybe;
   InterfaceType type = dartType;
   ClassEntity element = type.element;
@@ -4562,7 +4662,7 @@
   // We need the raw check because we don't have the notion of generics in the
   // backend. For example, `this` in a class `A<T>` is currently always
   // considered to have the raw type.
-  if (type.treatAsRaw) {
+  if (closedWorld.dartTypes.treatAsRawType(type)) {
     return abstractValueDomain.isInstanceOf(subsetType, element);
   }
   return AbstractBool.Maybe;
diff --git a/pkg/compiler/lib/src/ssa/optimize.dart b/pkg/compiler/lib/src/ssa/optimize.dart
index fb94984..c9a80b9 100644
--- a/pkg/compiler/lib/src/ssa/optimize.dart
+++ b/pkg/compiler/lib/src/ssa/optimize.dart
@@ -81,7 +81,8 @@
     OptimizationTestLog log;
     if (retainDataForTesting) {
       loggersForTesting ??= {};
-      loggersForTesting[member] = log = new OptimizationTestLog();
+      loggersForTesting[member] =
+          log = new OptimizationTestLog(closedWorld.dartTypes);
     }
 
     measure(() {
@@ -738,26 +739,26 @@
     AbstractValue receiverType = receiver.instructionType;
     MemberEntity element =
         _closedWorld.locateSingleMember(node.selector, receiverType);
+    if (element == null) return node;
+
     // TODO(ngeoffray): Also fold if it's a getter or variable.
-    if (element != null &&
-        element.isFunction &&
+    if (element.isFunction &&
         // If we found out that the only target is an implicitly called
-        // [:noSuchMethod:] we just ignore it.
+        // `noSuchMethod` we just ignore it.
         node.selector.applies(element)) {
       FunctionEntity method = element;
 
       if (_nativeData.isNativeMember(method)) {
-        HInstruction folded = tryInlineNativeMethod(node, method);
-        if (folded != null) return folded;
-      } else {
-        // TODO(ngeoffray): If the method has optional parameters,
-        // we should pass the default values.
-        ParameterStructure parameters = method.parameterStructure;
-        if (parameters.totalParameters == node.selector.argumentCount &&
-            parameters.typeParameters ==
-                node.selector.callStructure.typeArgumentCount) {
-          node.element = method;
-        }
+        return tryInlineNativeMethod(node, method) ?? node;
+      }
+
+      // TODO(ngeoffray): If the method has optional parameters, we should pass
+      // the default values.
+      ParameterStructure parameters = method.parameterStructure;
+      if (parameters.totalParameters == node.selector.argumentCount &&
+          parameters.typeParameters ==
+              node.selector.callStructure.typeArgumentCount) {
+        node.element = method;
       }
       return node;
     }
@@ -766,9 +767,7 @@
     // the field. This usually removes the demand for the call-through stub and
     // makes the field load available to further optimization, e.g. LICM.
 
-    if (element != null &&
-        element.isField &&
-        element.name == node.selector.name) {
+    if (element.isField && element.name == node.selector.name) {
       FieldEntity field = element;
       if (!_nativeData.isNativeMember(field) &&
           !node.isCallOnInterceptor(_closedWorld)) {
@@ -825,22 +824,120 @@
     return node;
   }
 
-  HInstruction tryInlineNativeMethod(
-      HInvokeDynamicMethod node, FunctionEntity method) {
-    // We can replace the call to the native class interceptor method (target)
-    // if the target does no conversions or useful type checks.
-    if (_options.disableInlining) return null;
+  bool _avoidInliningNativeMethod(HInvokeDynamic node, FunctionEntity method) {
+    assert(_nativeData.isNativeMember(method));
+    if (_options.disableInlining) return true;
     if (_closedWorld.annotationsData.hasNoInline(method)) {
+      return true;
+    }
+    return false;
+  }
+
+  // Try to 'inline' an instance getter call to a known native or js-interop
+  // getter. This replaces the call to the getter on the Dart interceptor with a
+  // direct call to the external method.
+  HInstruction tryInlineNativeGetter(
+      HInvokeDynamicGetter node, FunctionEntity method) {
+    if (_avoidInliningNativeMethod(node, method)) return null;
+
+    // Strengthen instruction type from annotations to help optimize dependent
+    // instructions.
+    NativeBehavior nativeBehavior = _nativeData.getNativeMethodBehavior(method);
+    AbstractValue returnType =
+        AbstractValueFactory.fromNativeBehavior(nativeBehavior, _closedWorld);
+    HInstruction receiver = node.inputs.last; // Drop interceptor.
+    receiver = maybeGuardWithNullCheck(receiver, node, null);
+    HInvokeExternal result = HInvokeExternal(
+        method, [receiver], returnType, nativeBehavior,
+        sourceInformation: node.sourceInformation);
+    _registry.registerStaticUse(StaticUse.methodInlining(method, null));
+    // Assume Native getters effect-free as an approximantion to being
+    // idempotent.
+    // TODO(sra): [native.BehaviorBuilder.buildMethodBehavior] should do this
+    // for us.
+    result.sideEffects.setDependsOnSomething();
+    result.sideEffects.clearAllSideEffects();
+    result.setUseGvn();
+    return result;
+  }
+
+  // Try to 'inline' an instance setter call to a known native or js-interop
+  // getter. This replaces the call to the setter on the Dart interceptor with a
+  // direct call to the external method.
+  HInstruction tryInlineNativeSetter(
+      HInvokeDynamicSetter node, FunctionEntity method) {
+    if (_avoidInliningNativeMethod(node, method)) return null;
+
+    assert(node.inputs.length == 3);
+    HInstruction receiver = node.inputs[1];
+    HInstruction value = node.inputs[2];
+    FunctionType type = _closedWorld.elementEnvironment.getFunctionType(method);
+    assert(type.optionalParameterTypes.isEmpty);
+    assert(type.namedParameterTypes.isEmpty);
+    DartType parameterType = type.parameterTypes.single;
+    if (_nativeArgumentNeedsCheckOrConversion(method, parameterType, value)) {
       return null;
     }
-    if (!node.isInterceptedCall) return null;
+
+    NativeBehavior nativeBehavior = _nativeData.getNativeMethodBehavior(method);
+    receiver = maybeGuardWithNullCheck(receiver, node, null);
+    HInvokeExternal result = HInvokeExternal(
+        method, [receiver, value], value.instructionType, nativeBehavior,
+        sourceInformation: node.sourceInformation);
+    _registry.registerStaticUse(StaticUse.methodInlining(method, null));
+    return result;
+  }
+
+  // TODO(sra): Refactor this code so that we can decide to inline the method
+  // with a few checks or conversions. We would want to do this if there was a
+  // single call site to [method], or most arguments do not require a check.
+  bool _nativeArgumentNeedsCheckOrConversion(
+      FunctionEntity method, DartType parameterType, HInstruction argument) {
+    // TODO(sra): JS-interop *instance* methods don't check their arguments
+    // since the forwarding stub is shared by all JS-interop methods with the
+    // same name, regardless of parameter types. We could 'inline' js-interop
+    // calls even when the types of the arguments are incorrect.
+
+    if (!_nativeData.isJsInteropMember(method)) {
+      // @Native methods have conversion code for function arguments. Rather
+      // than insert that code at the inlined call site, call the target on the
+      // interceptor.
+      if (parameterType.unaliased is FunctionType) return true;
+    }
+
+    if (!_closedWorld.annotationsData
+        .getParameterCheckPolicy(method)
+        .isEmitted) {
+      // If the target has no checks we can inline.
+      return false;
+    }
+
+    AbstractValue parameterAbstractValue = _abstractValueDomain
+        .getAbstractValueForNativeMethodParameterType(parameterType);
+
+    if (parameterAbstractValue == null ||
+        _abstractValueDomain
+            .isIn(argument.instructionType, parameterAbstractValue)
+            .isPotentiallyFalse) {
+      return true;
+    }
+    return false;
+  }
+
+  // Try to 'inline' an instance method call to a known native or js-interop
+  // method. This replaces the call to the method on the Dart interceptor with a
+  // direct call to the external method.
+  HInstruction tryInlineNativeMethod(
+      HInvokeDynamicMethod node, FunctionEntity method) {
+    if (_avoidInliningNativeMethod(node, method)) return null;
+    // We can replace the call to the native class interceptor method (target)
+    // if the target does no conversions or useful type checks.
 
     FunctionType type = _closedWorld.elementEnvironment.getFunctionType(method);
     if (type.namedParameters.isNotEmpty) return null;
 
     // The call site might omit optional arguments. The inlined code must
     // preserve the number of arguments, so check only the actual arguments.
-
     bool canInline = true;
     List<HInstruction> inputs = node.inputs;
     int inputPosition = 2; // Skip interceptor and receiver.
@@ -849,28 +946,8 @@
       if (!canInline) return;
       if (inputPosition >= inputs.length) return;
       HInstruction input = inputs[inputPosition++];
-      if (parameterType.unaliased is FunctionType) {
-        // Must call the target since it contains a function conversion.
+      if (_nativeArgumentNeedsCheckOrConversion(method, parameterType, input)) {
         canInline = false;
-        return;
-      }
-
-      // If the target has no checks don't let a bad type stop us inlining.
-      if (!_closedWorld.annotationsData
-          .getParameterCheckPolicy(method)
-          .isEmitted) {
-        return;
-      }
-
-      AbstractValue parameterAbstractValue = _abstractValueDomain
-          .getAbstractValueForNativeMethodParameterType(parameterType);
-
-      if (parameterAbstractValue == null ||
-          _abstractValueDomain
-              .isIn(input.instructionType, parameterAbstractValue)
-              .isPotentiallyFalse) {
-        canInline = false;
-        return;
       }
     }
 
@@ -885,15 +962,15 @@
     NativeBehavior nativeBehavior = _nativeData.getNativeMethodBehavior(method);
     AbstractValue returnType =
         AbstractValueFactory.fromNativeBehavior(nativeBehavior, _closedWorld);
-    HInvokeDynamicMethod result = new HInvokeDynamicMethod(
-        node.selector,
-        node.receiverType,
-        inputs.sublist(1), // Drop interceptor.
+    HInstruction receiver = inputs[1];
+    receiver = maybeGuardWithNullCheck(receiver, node, null);
+    HInvokeExternal result = HInvokeExternal(
+        method,
+        [receiver, ...inputs.skip(2)], // '2': Drop interceptor and receiver.
         returnType,
-        node.typeArguments,
-        node.sourceInformation);
-    result.element = method;
-    _registry.registerStaticUse(new StaticUse.methodInlining(method, null));
+        nativeBehavior,
+        sourceInformation: node.sourceInformation);
+    _registry.registerStaticUse(StaticUse.methodInlining(method, null));
     return result;
   }
 
@@ -1098,7 +1175,7 @@
       return node;
     }
 
-    if (type.isTop) {
+    if (_closedWorld.dartTypes.isTopType(type)) {
       return _graph.addConstantBool(true, _closedWorld);
     }
     InterfaceType interfaceType = type;
@@ -1146,7 +1223,8 @@
       // the notion of generics in the backend. For example, [:this:] in
       // a class [:A<T>:], is currently always considered to have the
       // raw type.
-    } else if (!RuntimeTypesSubstitutions.hasTypeArguments(type)) {
+    } else if (!RuntimeTypesSubstitutions.hasTypeArguments(
+        _closedWorld.dartTypes, type)) {
       AbstractValue expressionMask = expression.instructionType;
       AbstractBool isInstanceOf =
           _abstractValueDomain.isInstanceOf(expressionMask, element);
@@ -1171,7 +1249,8 @@
           rep.kind == TypeInfoExpressionKind.COMPLETE &&
           rep.inputs.isEmpty) {
         DartType type = rep.dartType;
-        if (type is InterfaceType && type.treatAsRaw) {
+        if (type is InterfaceType &&
+            _closedWorld.dartTypes.treatAsRawType(type)) {
           return node.checkedInput.convertType(_closedWorld, type, node.kind)
             ..sourceInformation = node.sourceInformation;
         }
@@ -1204,15 +1283,6 @@
     return node.isRedundant(_closedWorld) ? node.checkedInput : node;
   }
 
-  FieldEntity findConcreteFieldForDynamicAccess(
-      HInvokeDynamicField node, HInstruction receiver) {
-    AbstractValue receiverType = receiver.instructionType;
-    MemberEntity member = node.element is FieldEntity
-        ? node.element
-        : _closedWorld.locateSingleMember(node.selector, receiverType);
-    return member is FieldEntity ? member : null;
-  }
-
   @override
   HInstruction visitFieldGet(HFieldGet node) {
     var receiver = node.receiver;
@@ -1297,6 +1367,23 @@
     return node;
   }
 
+  /// Returns the guarded receiver.
+  HInstruction maybeGuardWithNullCheck(
+      HInstruction receiver, HInvokeDynamic node, FieldEntity /*?*/ field) {
+    AbstractValue receiverType = receiver.instructionType;
+    if (_abstractValueDomain.isNull(receiverType).isPotentiallyTrue) {
+      HNullCheck check =
+          HNullCheck(receiver, _abstractValueDomain.excludeNull(receiverType))
+            ..selector = node.selector
+            ..field = field
+            ..sourceInformation = node.sourceInformation;
+      _log?.registerNullCheck(node, check);
+      node.block.addBefore(node, check);
+      return check;
+    }
+    return receiver;
+  }
+
   @override
   HInstruction visitInvokeDynamicGetter(HInvokeDynamicGetter node) {
     propagateConstantValueToUses(node);
@@ -1306,53 +1393,46 @@
     }
     HInstruction receiver = node.getDartReceiver(_closedWorld);
     AbstractValue receiverType = receiver.instructionType;
-    FieldEntity field = node.element is FieldEntity
-        ? node.element
-        : findConcreteFieldForDynamicAccess(node, receiver);
-    if (field != null) {
+
+    Selector selector = node.selector;
+    MemberEntity member =
+        node.element ?? _closedWorld.locateSingleMember(selector, receiverType);
+    if (member == null) return node;
+
+    if (member is FieldEntity) {
+      FieldEntity field = member;
       FieldAnalysisData fieldData =
           _closedWorld.fieldAnalysis.getFieldData(field);
       if (fieldData.isEffectivelyConstant) {
         // The field is elided and replace it with its constant value.
-        if (_abstractValueDomain.isNull(receiverType).isPotentiallyTrue) {
-          // The receiver is potentially `null` so we insert a null receiver
-          // check to trigger a null pointer exception.  Insert check
-          // conditionally to avoid the work of removing it later.
-          HNullCheck check = HNullCheck(
-              receiver, _abstractValueDomain.excludeNull(receiverType))
-            ..selector = node.selector
-            ..sourceInformation = node.sourceInformation;
-          _log?.registerNullCheck(node, check);
-          node.block.addBefore(node, check);
-        }
+        maybeGuardWithNullCheck(receiver, node, null);
         ConstantValue constant = fieldData.constantValue;
         HConstant result = _graph.addConstant(constant, _closedWorld,
             sourceInformation: node.sourceInformation);
         _log?.registerConstantFieldGet(node, field, result);
         return result;
       } else {
-        if (_abstractValueDomain.isNull(receiverType).isPotentiallyTrue) {
-          HNullCheck check = HNullCheck(
-              receiver, _abstractValueDomain.excludeNull(receiverType))
-            ..selector = node.selector
-            ..field = field
-            ..sourceInformation = node.sourceInformation;
-          _log?.registerNullCheck(node, check);
-          node.block.addBefore(node, check);
-          receiver = check;
-        }
+        receiver = maybeGuardWithNullCheck(receiver, node, field);
         HFieldGet result = _directFieldGet(receiver, field, node);
         _log?.registerFieldGet(node, result);
         return result;
       }
     }
 
-    node.element ??=
-        _closedWorld.locateSingleMember(node.selector, receiverType);
-    if (node.element != null &&
-        node.element.name == node.selector.name &&
-        node.element.isFunction) {
+    if (member is FunctionEntity) {
+      // If the member is not a getter, this could be a property extraction
+      // getter or legacy `noSuchMethod`.
+      if (member.isGetter && member.name == selector.name) {
+        node.element = member;
+        if (_nativeData.isNativeMember(member)) {
+          return tryInlineNativeGetter(node, member) ?? node;
+        }
+      }
+    }
+
+    if (member.isFunction && member.name == selector.name) {
       // A property extraction getter, aka a tear-off.
+      node.element = member;
       node.sideEffects.clearAllDependencies();
       node.sideEffects.clearAllSideEffects();
       node.setUseGvn(); // We don't care about identity of tear-offs.
@@ -1391,69 +1471,87 @@
     }
 
     HInstruction receiver = node.getDartReceiver(_closedWorld);
-    FieldEntity field = findConcreteFieldForDynamicAccess(node, receiver);
-    if (field == null || !field.isAssignable) return node;
-    // Use `node.inputs.last` in case the call follows the interceptor calling
-    // convention, but is not a call on an interceptor.
-    HInstruction value = node.inputs.last;
+    AbstractValue receiverType = receiver.instructionType;
+    MemberEntity member = node.element ??=
+        _closedWorld.locateSingleMember(node.selector, receiverType);
+    if (member == null) return node;
 
-    HInstruction assignField() {
-      if (_closedWorld.fieldAnalysis.getFieldData(field).isElided) {
-        _log?.registerFieldSet(node);
-        return value;
-      } else {
-        HFieldSet result =
-            HFieldSet(_abstractValueDomain, field, receiver, value)
-              ..sourceInformation = node.sourceInformation;
-        _log?.registerFieldSet(node, result);
-        return result;
+    if (member is FieldEntity) {
+      FieldEntity field = member;
+      if (field == null || !field.isAssignable) return node;
+      // Use `node.inputs.last` in case the call follows the interceptor calling
+      // convention, but is not a call on an interceptor.
+      HInstruction value = node.inputs.last;
+
+      HInstruction assignField() {
+        if (_closedWorld.fieldAnalysis.getFieldData(field).isElided) {
+          _log?.registerFieldSet(node);
+          return value;
+        } else {
+          HFieldSet result =
+              HFieldSet(_abstractValueDomain, field, receiver, value)
+                ..sourceInformation = node.sourceInformation;
+          _log?.registerFieldSet(node, result);
+          return result;
+        }
       }
-    }
 
-    if (!_closedWorld.annotationsData
-        .getParameterCheckPolicy(field)
-        .isEmitted) {
+      if (!_closedWorld.annotationsData
+          .getParameterCheckPolicy(field)
+          .isEmitted) {
+        return assignField();
+      }
+
+      DartType fieldType = _closedWorld.elementEnvironment.getFieldType(field);
+
+      if (_options.useNewRti) {
+        AbstractValueWithPrecision checkedType = _abstractValueDomain
+            .createFromStaticType(fieldType, nullable: true);
+        if (checkedType.isPrecise &&
+            _abstractValueDomain
+                .isIn(value.instructionType, checkedType.abstractValue)
+                .isDefinitelyTrue) {
+          return assignField();
+        }
+        // TODO(sra): Implement inlining of setters with checks for new rti. The
+        // check and field assignment for the setter should inlined if this is
+        // the only call to the setter, or the current function already computes
+        // the type of the field.
+        node.needsCheck = true;
+        return node;
+      }
+
+      if (!_closedWorld.dartTypes.treatAsRawType(fieldType) ||
+          fieldType is TypeVariableType ||
+          fieldType.unaliased is FunctionType ||
+          fieldType.unaliased is FutureOrType) {
+        // We cannot generate the correct type representation here, so don't
+        // inline this access.
+        // TODO(sra): If the input is such that we don't need a type check, we
+        // can skip the test an generate the HFieldSet.
+        node.needsCheck = true;
+        return node;
+      }
+      HInstruction other = value.convertType(
+          _closedWorld, fieldType, HTypeConversion.TYPE_CHECK);
+      if (other != value) {
+        node.block.addBefore(node, other);
+        value = other;
+      }
+
       return assignField();
     }
 
-    DartType fieldType = _closedWorld.elementEnvironment.getFieldType(field);
-
-    if (_options.useNewRti) {
-      AbstractValueWithPrecision checkedType =
-          _abstractValueDomain.createFromStaticType(fieldType, nullable: true);
-      if (checkedType.isPrecise &&
-          _abstractValueDomain
-              .isIn(value.instructionType, checkedType.abstractValue)
-              .isDefinitelyTrue) {
-        return assignField();
+    if (member is FunctionEntity) {
+      // If the member is not a setter is could be legacy `noSuchMethod`.
+      if (member.isSetter && member.name == node.selector.name) {
+        if (_nativeData.isNativeMember(member)) {
+          return tryInlineNativeSetter(node, member) ?? node;
+        }
       }
-      // TODO(sra): Implement inlining of setters with checks for new rti. The
-      // check and field assignment for the setter should inlined if this is the
-      // only call to the setter, or the current function already computes the
-      // type of the field.
-      node.needsCheck = true;
-      return node;
     }
 
-    if (!fieldType.treatAsRaw ||
-        fieldType is TypeVariableType ||
-        fieldType.unaliased is FunctionType ||
-        fieldType.unaliased is FutureOrType) {
-      // We cannot generate the correct type representation here, so don't
-      // inline this access.
-      // TODO(sra): If the input is such that we don't need a type check, we
-      // can skip the test an generate the HFieldSet.
-      node.needsCheck = true;
-      return node;
-    }
-    HInstruction other =
-        value.convertType(_closedWorld, fieldType, HTypeConversion.TYPE_CHECK);
-    if (other != value) {
-      node.block.addBefore(node, other);
-      value = other;
-    }
-
-    return assignField();
+    return node;
   }
 
   @override
@@ -1542,6 +1640,11 @@
       }
     }
 
+    // TODO(sra): [element] could be a native or js-interop method, in which
+    // case we could 'inline' the call to the Dart-convention wrapper code,
+    // replacing it with a HInvokeExternal instruction. Many of these static
+    // methods are already 'inlined' by the CFG builder.
+
     return node;
   }
 
@@ -2036,7 +2139,7 @@
         return HAsCheckSimple(node.checkedInput, dartType, checkedType,
             node.isTypeError, specializedCheck, node.instructionType);
       }
-      if (dartType.isTop) {
+      if (_closedWorld.dartTypes.isTopType(dartType)) {
         return node.checkedInput;
       }
     }
@@ -2063,7 +2166,7 @@
     if (typeInput is HLoadType) {
       TypeExpressionRecipe recipe = typeInput.typeExpression;
       DartType dartType = recipe.type;
-      if (dartType.isTop) {
+      if (_closedWorld.dartTypes.isTopType(dartType)) {
         return _graph.addConstantBool(true, _closedWorld);
       }
 
@@ -2891,6 +2994,10 @@
       HInstruction next = instruction.next;
       int flags = instruction.sideEffects.getChangesFlags();
       assert(flags == 0 || !instruction.useGvn());
+      // TODO(sra): Is the above assertion too strong? We should be able to
+      // reuse the values generated by idempotent operations that have
+      // effects. Would it be correct to make the kill below be conditional on
+      // not replacing the instruction?
       values.kill(flags);
       if (instruction.useGvn()) {
         HInstruction other = values.lookup(instruction);
diff --git a/pkg/compiler/lib/src/ssa/ssa_tracer.dart b/pkg/compiler/lib/src/ssa/ssa_tracer.dart
index f525185..5bfb428 100644
--- a/pkg/compiler/lib/src/ssa/ssa_tracer.dart
+++ b/pkg/compiler/lib/src/ssa/ssa_tracer.dart
@@ -402,6 +402,20 @@
   }
 
   @override
+  String visitInvokeExternal(HInvokeExternal node) {
+    var target = node.element;
+    var inputs = node.inputs;
+    String targetString;
+    if (target.isInstanceMember) {
+      targetString = temporaryId(inputs.first) + '.${target.name}';
+      inputs = inputs.sublist(1);
+    } else {
+      targetString = target.name;
+    }
+    return handleGenericInvoke('InvokeExternal', targetString, inputs);
+  }
+
+  @override
   String visitForeignCode(HForeignCode node) {
     var template = node.codeTemplate;
     String code = '${template.ast}';
@@ -472,7 +486,10 @@
   }
 
   @override
-  String visitReturn(HReturn node) => "Return: ${temporaryId(node.inputs[0])}";
+  String visitReturn(HReturn node) {
+    if (node.inputs.isEmpty) return "Return";
+    return "Return: ${temporaryId(node.inputs.single)}";
+  }
 
   @override
   String visitShiftLeft(HShiftLeft node) =>
diff --git a/pkg/compiler/lib/src/ssa/type_builder.dart b/pkg/compiler/lib/src/ssa/type_builder.dart
index bd064b1..86b26e8 100644
--- a/pkg/compiler/lib/src/ssa/type_builder.dart
+++ b/pkg/compiler/lib/src/ssa/type_builder.dart
@@ -433,7 +433,7 @@
 
     if (type == null) return original;
     type = type.unaliased;
-    if (type is InterfaceType && !type.treatAsRaw) {
+    if (type is InterfaceType && !_closedWorld.dartTypes.treatAsRawType(type)) {
       InterfaceType interfaceType = type;
       AbstractValue subtype =
           _abstractValueDomain.createNullableSubtype(interfaceType.element);
diff --git a/pkg/compiler/lib/src/ssa/types.dart b/pkg/compiler/lib/src/ssa/types.dart
index fb648c4..0d1a3b8 100644
--- a/pkg/compiler/lib/src/ssa/types.dart
+++ b/pkg/compiler/lib/src/ssa/types.dart
@@ -52,7 +52,7 @@
             .createNonNullExact(commonElements.objectClass);
       } else if (type is VoidType) {
         return abstractValueDomain.nullType;
-      } else if (type.isTop) {
+      } else if (closedWorld.dartTypes.isTopType(type)) {
         return abstractValueDomain.dynamicType;
       } else if (type == commonElements.nullType) {
         return abstractValueDomain.nullType;
diff --git a/pkg/compiler/lib/src/universe/member_usage.dart b/pkg/compiler/lib/src/universe/member_usage.dart
index a322bc3..5fae2da 100644
--- a/pkg/compiler/lib/src/universe/member_usage.dart
+++ b/pkg/compiler/lib/src/universe/member_usage.dart
@@ -356,7 +356,7 @@
       'potentialWrites=${potentialWrites.iterable(Access.values)},'
       'potentialInvokes=${potentialInvokes.iterable(Access.values)},'
       'pendingUse=${_pendingUse.iterable(MemberUse.values)},'
-      'initialConstants=${initialConstants?.map((c) => c.toStructuredText())})';
+      'initialConstants=${initialConstants?.map((c) => c.toStructuredText(null))})';
 }
 
 /// Member usage tracking for a field.
@@ -492,7 +492,7 @@
       'potentialWrites=${potentialWrites.iterable(Access.values)},'
       'potentialInvokes=${potentialInvokes.iterable(Access.values)},'
       'pendingUse=${_pendingUse.iterable(MemberUse.values)},'
-      'initialConstants=${initialConstants.map((c) => c.toStructuredText())})';
+      'initialConstants=${initialConstants.map((c) => c.toStructuredText(null))})';
 }
 
 /// Member usage tracking for a constructor or method.
diff --git a/pkg/compiler/lib/src/universe/use.dart b/pkg/compiler/lib/src/universe/use.dart
index f735707..cfc28bd 100644
--- a/pkg/compiler/lib/src/universe/use.dart
+++ b/pkg/compiler/lib/src/universe/use.dart
@@ -293,7 +293,7 @@
     }
     if (constant != null) {
       sb.write('=');
-      sb.write(constant.toStructuredText());
+      sb.write(constant.toStructuredText(null));
     }
     return sb.toString();
   }
@@ -908,7 +908,7 @@
 
   /// Short textual representation use for testing.
   String get shortText {
-    return value.toDartText();
+    return value.toDartText(null);
   }
 
   /// Constant used as the initial value of a field.
@@ -934,5 +934,5 @@
   int get hashCode => value.hashCode;
 
   @override
-  String toString() => 'ConstantUse(${value.toStructuredText()})';
+  String toString() => 'ConstantUse(${value.toStructuredText(null)})';
 }
diff --git a/pkg/dartdev/.gitignore b/pkg/dartdev/.gitignore
index 96cf44b..0bd726b 100644
--- a/pkg/dartdev/.gitignore
+++ b/pkg/dartdev/.gitignore
@@ -8,3 +8,6 @@
 
 # Directory created by dartdoc
 doc/api/
+
+# Directory created by pub
+.dart_tool/
diff --git a/pkg/dartdev/README.md b/pkg/dartdev/README.md
index c1aeeeb..3d88cff 100644
--- a/pkg/dartdev/README.md
+++ b/pkg/dartdev/README.md
@@ -4,4 +4,4 @@
 
 ## Docs
 
-This tool is currently under active development.
\ No newline at end of file
+This tool is currently under active development.
diff --git a/pkg/dartdev/bin/dartdev.dart b/pkg/dartdev/bin/dartdev.dart
index db84729..7968056 100644
--- a/pkg/dartdev/bin/dartdev.dart
+++ b/pkg/dartdev/bin/dartdev.dart
@@ -9,7 +9,7 @@
 
 /// The entry point for dartdev.
 main(List<String> args) async {
-  final runner = DartdevRunner();
+  final runner = DartdevRunner(args);
   try {
     dynamic result = await runner.run(args);
     exit(result is int ? result : 0);
diff --git a/pkg/dartdev/lib/dartdev.dart b/pkg/dartdev/lib/dartdev.dart
index 8422799..e073464 100644
--- a/pkg/dartdev/lib/dartdev.dart
+++ b/pkg/dartdev/lib/dartdev.dart
@@ -6,25 +6,29 @@
 import 'package:args/command_runner.dart';
 import 'package:cli_util/cli_logging.dart';
 
+import 'src/commands/create.dart';
 import 'src/commands/format.dart';
 import 'src/core.dart';
 
-class DartdevRunner extends CommandRunner {
+class DartdevRunner<int> extends CommandRunner {
   static const String dartdevDescription =
       'A command-line utility for Dart development';
 
-  DartdevRunner() : super('dartdev', '$dartdevDescription.') {
+  DartdevRunner(List<String> args) : super('dartdev', '$dartdevDescription.') {
+    final bool verbose = args.contains('-v') || args.contains('--verbose');
+
     argParser.addFlag('verbose',
         abbr: 'v', negatable: false, help: 'Show verbose output.');
 
-    // The list of currently supported commands:
-    addCommand(FormatCommand());
+    addCommand(CreateCommand(verbose: verbose));
+    addCommand(FormatCommand(verbose: verbose));
   }
 
   @override
-  Future runCommand(ArgResults results) async {
+  Future<int> runCommand(ArgResults results) async {
     isVerbose = results['verbose'];
 
+    final Ansi ansi = Ansi(Ansi.terminalSupportsAnsi);
     log = isVerbose ? Logger.verbose(ansi: ansi) : Logger.standard(ansi: ansi);
 
     return await super.runCommand(results);
diff --git a/pkg/dartdev/lib/src/commands/create.dart b/pkg/dartdev/lib/src/commands/create.dart
new file mode 100644
index 0000000..513bf65
--- /dev/null
+++ b/pkg/dartdev/lib/src/commands/create.dart
@@ -0,0 +1,180 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io' as io;
+import 'dart:math' as math;
+
+import 'package:path/path.dart' as path;
+import 'package:stagehand/stagehand.dart' as stagehand;
+
+import '../core.dart';
+import '../sdk.dart';
+
+/// A command to create a new project from a set of templates.
+class CreateCommand extends DartdevCommand {
+  static String defaultTemplateId = 'console-full';
+
+  static List<String> legalTemplateIds = [
+    'console-full',
+    'package-simple',
+    'web-simple'
+  ];
+
+  static Iterable<stagehand.Generator> get generators =>
+      stagehand.generators.where((g) => legalTemplateIds.contains(g.id));
+
+  static stagehand.Generator retrieveTemplateGenerator(String templateId) =>
+      stagehand.getGenerator(templateId);
+
+  CreateCommand({bool verbose = false})
+      : super('create', 'Create a new project.') {
+    argParser.addOption(
+      'template',
+      allowed: legalTemplateIds,
+      help: 'The project template to use.',
+      defaultsTo: defaultTemplateId,
+    );
+    argParser.addFlag('pub',
+        defaultsTo: true,
+        help: "Whether to run 'pub get' after the project has been created.");
+    argParser.addFlag(
+      'list-templates',
+      negatable: false,
+      hide: !verbose,
+      help: 'List the available templates in JSON format.',
+    );
+    argParser.addFlag(
+      'force',
+      negatable: false,
+      help:
+          'Force project generation, even if the target directory already exists.',
+    );
+  }
+
+  @override
+  String get invocation => '${super.invocation} <directory>';
+
+  @override
+  FutureOr<int> run() async {
+    if (argResults['list-templates']) {
+      log.stdout(_availableTemplatesJson());
+      return 0;
+    }
+
+    if (argResults.rest.isEmpty) {
+      printUsage();
+      return 1;
+    }
+
+    String templateId = argResults['template'];
+
+    String dir = argResults.rest.first;
+    var targetDir = io.Directory(dir);
+    if (targetDir.existsSync() && !(argResults['force'])) {
+      log.stderr(
+          "Directory '$dir' already exists (use '--force' to force project generation).");
+      return 73;
+    }
+
+    log.stdout(
+        'Creating ${log.ansi.emphasized(path.absolute(dir))} using template $templateId...');
+    log.stdout('');
+
+    var generator = retrieveTemplateGenerator(templateId);
+    await generator.generate(
+      path.basename(dir),
+      DirectoryGeneratorTarget(generator, io.Directory(dir)),
+    );
+
+    if (argResults['pub']) {
+      log.stdout('');
+      var progress = log.progress('Running pub get');
+      var process = await startProcess(
+        sdk.pub,
+        ['get', '--no-precompile'],
+        cwd: dir,
+      );
+
+      // Run 'pub get'. We display output from the pub command, but keep the
+      // output terse. This is to give the user a sense of the work that pub
+      // did without scrolling the previous stdout sections off the screen.
+      var buffer = StringBuffer();
+      routeToStdout(
+        process,
+        logToTrace: true,
+        listener: (str) {
+          // Filter lines like '+ multi_server_socket 1.0.2'.
+          if (!str.startsWith('+ ')) {
+            buffer.writeln('  $str');
+          }
+        },
+      );
+      int code = await process.exitCode;
+      if (code != 0) return code;
+      progress.finish(showTiming: true);
+      log.stdout(buffer.toString().trimRight());
+    }
+
+    log.stdout('');
+    log.stdout('Created project $dir! In order to get started, type:');
+    log.stdout('');
+    log.stdout(log.ansi.emphasized('  cd ${path.relative(dir)}'));
+    // TODO(devoncarew): Once we have a 'run' command, print out here how to run
+    // the app.
+    log.stdout('');
+
+    return 0;
+  }
+
+  @override
+  String get usageFooter {
+    int width = legalTemplateIds.map((s) => s.length).reduce(math.max);
+    String desc = generators
+        .map((g) => '  ${g.id.padLeft(width)}: ${g.description}')
+        .join('\n');
+    return '\nAvailable templates:\n$desc';
+  }
+
+  String _availableTemplatesJson() {
+    var items = generators.map((stagehand.Generator generator) {
+      var m = {
+        'name': generator.id,
+        'label': generator.label,
+        'description': generator.description,
+        'categories': generator.categories
+      };
+
+      if (generator.entrypoint != null) {
+        m['entrypoint'] = generator.entrypoint.path;
+      }
+
+      return m;
+    });
+
+    JsonEncoder encoder = JsonEncoder.withIndent('  ');
+    return encoder.convert(items.toList());
+  }
+}
+
+class DirectoryGeneratorTarget extends stagehand.GeneratorTarget {
+  final stagehand.Generator generator;
+  final io.Directory dir;
+
+  DirectoryGeneratorTarget(this.generator, this.dir) {
+    dir.createSync();
+  }
+
+  @override
+  Future createFile(String filePath, List<int> contents) async {
+    io.File file = io.File(path.join(dir.path, filePath));
+
+    String name = path.relative(file.path, from: dir.path);
+    log.stdout('  $name');
+
+    await file.create(recursive: true);
+    await file.writeAsBytes(contents);
+  }
+}
diff --git a/pkg/dartdev/lib/src/commands/format.dart b/pkg/dartdev/lib/src/commands/format.dart
index 97c2d7d..32f0206 100644
--- a/pkg/dartdev/lib/src/commands/format.dart
+++ b/pkg/dartdev/lib/src/commands/format.dart
@@ -2,16 +2,19 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'dart:async';
+
 import '../core.dart';
 import '../sdk.dart';
 
 class FormatCommand extends DartdevCommand {
-  FormatCommand() : super('format', 'Format one or more Dart files.') {
+  FormatCommand({bool verbose = false})
+      : super('format', 'Format one or more Dart files.') {
     // TODO(jwren) add all options and flags
   }
 
   @override
-  run() async {
+  FutureOr<int> run() async {
     // TODO(jwren) implement verbose in dart_style
     // dartfmt doesn't have '-v' or '--verbose', so remove from the argument list
     var args = List.from(argResults.arguments)
diff --git a/pkg/dartdev/lib/src/core.dart b/pkg/dartdev/lib/src/core.dart
index b937f19..8e0e3d8 100644
--- a/pkg/dartdev/lib/src/core.dart
+++ b/pkg/dartdev/lib/src/core.dart
@@ -8,11 +8,10 @@
 import 'package:args/command_runner.dart';
 import 'package:cli_util/cli_logging.dart';
 
-Ansi ansi = Ansi(Ansi.terminalSupportsAnsi);
 Logger log;
 bool isVerbose = false;
 
-abstract class DartdevCommand extends Command {
+abstract class DartdevCommand<int> extends Command {
   final String _name;
   final String _description;
 
diff --git a/pkg/dartdev/pubspec.yaml b/pkg/dartdev/pubspec.yaml
index 65aaee2..57ba7ac 100644
--- a/pkg/dartdev/pubspec.yaml
+++ b/pkg/dartdev/pubspec.yaml
@@ -10,9 +10,10 @@
   cli_util: ^0.1.0
   intl: ^0.16.0
   path: ^1.6.2
+  stagehand: 3.3.6
   watcher: ^0.9.7+13
   yaml: ^2.2.0
 
 dev_dependencies:
   test: ^1.0.0
-  pedantic: ^1.8.0
\ No newline at end of file
+  pedantic: ^1.8.0
diff --git a/pkg/dartdev/test/commands/create_test.dart b/pkg/dartdev/test/commands/create_test.dart
new file mode 100644
index 0000000..6a63cf7
--- /dev/null
+++ b/pkg/dartdev/test/commands/create_test.dart
@@ -0,0 +1,97 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:dartdev/src/commands/create.dart';
+import 'package:path/path.dart' as path;
+import 'package:test/test.dart';
+
+import '../utils.dart';
+
+void main() {
+  group('create', defineCreate);
+}
+
+void defineCreate() {
+  TestProject p;
+
+  setUp(() => p = null);
+
+  tearDown(() => p?.dispose());
+
+  test('default template exists', () {
+    expect(CreateCommand.legalTemplateIds,
+        contains(CreateCommand.defaultTemplateId));
+  });
+
+  test('all templates exist', () {
+    for (String templateId in CreateCommand.legalTemplateIds) {
+      expect(CreateCommand.legalTemplateIds, contains(templateId));
+    }
+  });
+
+  test('list templates', () {
+    p = project();
+
+    ProcessResult result = p.runSync('create', ['--list-templates']);
+    expect(result.exitCode, 0);
+
+    String output = result.stdout.toString();
+    var parsedResult = jsonDecode(output);
+    expect(parsedResult, hasLength(CreateCommand.legalTemplateIds.length));
+    expect(parsedResult[0]['name'], isNotNull);
+    expect(parsedResult[0]['label'], isNotNull);
+    expect(parsedResult[0]['description'], isNotNull);
+  });
+
+  test('no directory given', () {
+    p = project();
+
+    ProcessResult result = p.runSync('create');
+    expect(result.exitCode, 1);
+  });
+
+  test('directory already exists', () {
+    p = project();
+
+    ProcessResult result = p.runSync('create', [
+      '--no-pub',
+      '--template',
+      CreateCommand.defaultTemplateId,
+      p.dir.path
+    ]);
+    expect(result.exitCode, 73);
+  });
+
+  test('bad template id', () {
+    p = project();
+
+    ProcessResult result =
+        p.runSync('create', ['--no-pub', '--template', 'foo-bar', p.dir.path]);
+    expect(result.exitCode, isNot(0));
+  });
+
+  // Create tests for each template.
+  for (String templateId in CreateCommand.legalTemplateIds) {
+    test('create $templateId', () {
+      p = project();
+
+      ProcessResult result = p.runSync('create',
+          ['--force', '--no-pub', '--template', templateId, p.dir.path]);
+      expect(result.exitCode, 0);
+
+      String projectName = path.basename(p.dir.path);
+
+      String entry =
+          CreateCommand.retrieveTemplateGenerator(templateId).entrypoint.path;
+      entry = entry.replaceAll('__projectName__', projectName);
+      File entryFile = File(path.join(p.dir.path, entry));
+
+      expect(entryFile.existsSync(), true,
+          reason: 'File not found: ${entryFile.path}');
+    });
+  }
+}
diff --git a/pkg/dartdev/test/commands/flag_test.dart b/pkg/dartdev/test/commands/flag_test.dart
index 1e6cadd..809f3e9 100644
--- a/pkg/dartdev/test/commands/flag_test.dart
+++ b/pkg/dartdev/test/commands/flag_test.dart
@@ -13,7 +13,9 @@
 
 void help() {
   TestProject p;
+
   tearDown(() => p?.dispose());
+
   test('--help', () {
     p = project();
 
diff --git a/pkg/dartdev/test/test_all.dart b/pkg/dartdev/test/test_all.dart
index 9cef9d3..9b3a5d9 100644
--- a/pkg/dartdev/test/test_all.dart
+++ b/pkg/dartdev/test/test_all.dart
@@ -4,12 +4,14 @@
 
 import 'package:test/test.dart';
 
+import 'commands/create_test.dart' as create;
 import 'commands/flag_test.dart' as flag;
 import 'commands/format_test.dart' as format;
 import 'utils_test.dart' as utils;
 
 main() {
   group('dartdev', () {
+    create.main();
     flag.main();
     format.main();
     utils.main();
diff --git a/pkg/dev_compiler/analysis_options.yaml b/pkg/dev_compiler/analysis_options.yaml
index ed8ddc4..e4c5083 100644
--- a/pkg/dev_compiler/analysis_options.yaml
+++ b/pkg/dev_compiler/analysis_options.yaml
@@ -15,10 +15,21 @@
 
 linter:
   rules:
+    # Enforced by pedantic v1.9.0.
+    - always_declare_return_types
+    - always_require_non_null_named_parameters
     - annotate_overrides
+    - avoid_null_checks_in_equality_operators
+    - camel_case_extensions
+    - prefer_adjacent_string_concatenation
+    - prefer_collection_literals
     - prefer_conditional_assignment
-    - prefer_null_aware_operators
+    - prefer_final_fields
+    - prefer_for_elements_to_map_fromIterable
+    - prefer_if_null_operators
     - prefer_single_quotes
-    # Not enforced by pedantic at any version
+    - prefer_spread_collections
+    # Not enforced by pedantic at any version.
     - directives_ordering
+    - prefer_null_aware_operators
     - prefer_typing_uninitialized_variables
diff --git a/pkg/dev_compiler/lib/src/compiler/js_metalet.dart b/pkg/dev_compiler/lib/src/compiler/js_metalet.dart
index 2799afd..4f569a1 100644
--- a/pkg/dev_compiler/lib/src/compiler/js_metalet.dart
+++ b/pkg/dev_compiler/lib/src/compiler/js_metalet.dart
@@ -278,7 +278,7 @@
       }
 
       assert(body.isNotEmpty);
-      var newBody = Expression.binary([assign]..addAll(body), ',') as Binary;
+      var newBody = Expression.binary([assign, ...body], ',') as Binary;
       newBody = _substitute(newBody, {result: left});
       return MetaLet(vars, newBody.commaToExpressionList(),
           statelessResult: statelessResult);
@@ -296,9 +296,8 @@
       generator.analysis.containsInterpolatedNode.whereType<MetaLetVariable>());
   if (nodes.isEmpty) return tree;
 
-  return instantiator(Map.fromIterable(nodes,
-      key: (v) => (v as MetaLetVariable).nameOrPosition,
-      value: (v) => substitutions[v] ?? v)) as T;
+  return instantiator(
+      {for (var v in nodes) v.nameOrPosition: substitutions[v] ?? v}) as T;
 }
 
 /// A temporary variable used in a [MetaLet].
diff --git a/pkg/dev_compiler/lib/src/compiler/js_names.dart b/pkg/dev_compiler/lib/src/compiler/js_names.dart
index d9814cc..0e3192c 100644
--- a/pkg/dev_compiler/lib/src/compiler/js_names.dart
+++ b/pkg/dev_compiler/lib/src/compiler/js_names.dart
@@ -123,7 +123,7 @@
 
   /// Nested scopes, these are visited after everything else so the names
   /// they might need are in scope.
-  final childScopes = Map<Node, _FunctionScope>();
+  final childScopes = <Node, _FunctionScope>{};
 
   /// New names assigned for temps and identifiers.
   final renames = HashMap<Object, String>();
@@ -133,7 +133,7 @@
 
 /// Collects all names used in the visited tree.
 class _RenameVisitor extends VariableDeclarationVisitor {
-  final pendingRenames = Map<Object, Set<_FunctionScope>>();
+  final pendingRenames = <Object, Set<_FunctionScope>>{};
 
   final _FunctionScope globalScope = _FunctionScope(null);
   final _FunctionScope rootScope = _FunctionScope(null);
@@ -343,7 +343,7 @@
 ///
 /// http://www.ecma-international.org/ecma-262/6.0/#sec-properties-of-the-object-prototype-object
 /// http://www.ecma-international.org/ecma-262/6.0/#sec-additional-properties-of-the-object.prototype-object
-final objectProperties = <String>[
+final objectProperties = <String>{
   'constructor',
   'toString',
   'toLocaleString',
@@ -356,7 +356,7 @@
   '__defineSetter__',
   '__lookupSetter__',
   '__proto__'
-].toSet();
+};
 
 /// Returns the JS member name for a public Dart instance member, before it
 /// is symbolized; generally you should use [_emitMemberName] or
diff --git a/pkg/dev_compiler/lib/src/compiler/js_utils.dart b/pkg/dev_compiler/lib/src/compiler/js_utils.dart
index 5b5971e..8b936e7 100644
--- a/pkg/dev_compiler/lib/src/compiler/js_utils.dart
+++ b/pkg/dev_compiler/lib/src/compiler/js_utils.dart
@@ -34,7 +34,7 @@
 class MutationVisitor extends BaseVisitor<void> {
   /// Using Identifier names instead of a more precise key may result in
   /// mutations being imprecisely reported when variables shadow each other.
-  final mutated = Set<String>();
+  final mutated = <String>{};
   @override
   void visitAssignment(node) {
     var id = node.leftHandSide;
diff --git a/pkg/dev_compiler/lib/src/compiler/shared_compiler.dart b/pkg/dev_compiler/lib/src/compiler/shared_compiler.dart
index 4121fe5..70224ce 100644
--- a/pkg/dev_compiler/lib/src/compiler/shared_compiler.dart
+++ b/pkg/dev_compiler/lib/src/compiler/shared_compiler.dart
@@ -262,7 +262,9 @@
       var idName = name.endsWith('=') ? name.replaceAll('=', '_') : name;
       idName = idName.replaceAll(js_ast.invalidCharInIdentifier, '_');
       id ??= js_ast.TemporaryId(idName);
-      moduleItems.add(js.statement('const # = #.privateName(#, #)',
+      // TODO(vsm): Change back to `const`.
+      // See https://github.com/dart-lang/sdk/issues/40380.
+      moduleItems.add(js.statement('var # = #.privateName(#, #)',
           [id, runtimeModule, emitLibraryName(library), js.string(name)]));
       return id;
     }
@@ -417,8 +419,10 @@
       var alias = jsLibraryAlias(library);
       var aliasId = alias == null ? null : js_ast.TemporaryId(alias);
 
+      // TODO(vsm): Change back to `const`.
+      // See https://github.com/dart-lang/sdk/issues/40380.
       items.add(js.statement(
-          'const # = Object.create(#.library)', [libraryId, runtimeModule]));
+          'var # = Object.create(#.library)', [libraryId, runtimeModule]));
       exports.add(js_ast.NameSpecifier(libraryId, asName: aliasId));
     }
 
@@ -426,8 +430,10 @@
     // TODO(jmesserly): find a cleaner design for this.
     if (isBuildingSdk) {
       var id = extensionSymbolsModule;
-      items.add(js.statement(
-          'const # = Object.create(#.library)', [id, runtimeModule]));
+      // TODO(vsm): Change back to `const`.
+      // See https://github.com/dart-lang/sdk/issues/40380.
+      items.add(js
+          .statement('var # = Object.create(#.library)', [id, runtimeModule]));
       exports.add(js_ast.NameSpecifier(id));
     }
 
@@ -468,7 +474,7 @@
   /// Emits imports and extension methods into [items].
   @protected
   void emitImportsAndExtensionSymbols(List<js_ast.ModuleItem> items) {
-    var modules = Map<String, List<Library>>();
+    var modules = <String, List<Library>>{};
 
     for (var import in _imports.keys) {
       modules.putIfAbsent(libraryToModule(import), () => []).add(import);
@@ -512,7 +518,9 @@
       if (isBuildingSdk) {
         value = js.call('# = Symbol(#)', [value, js.string('dartx.$name')]);
       }
-      items.add(js.statement('const # = #;', [id, value]));
+      // TODO(vsm): Change back to `const`.
+      // See https://github.com/dart-lang/sdk/issues/40380.
+      items.add(js.statement('var # = #;', [id, value]));
     });
   }
 
diff --git a/pkg/dev_compiler/lib/src/js_ast/builder.dart b/pkg/dev_compiler/lib/src/js_ast/builder.dart
index 3bdf602..9b2105f 100644
--- a/pkg/dev_compiler/lib/src/js_ast/builder.dart
+++ b/pkg/dev_compiler/lib/src/js_ast/builder.dart
@@ -3,7 +3,8 @@
 // BSD-style license that can be found in the LICENSE file.
 
 // ignore_for_file: slash_for_doc_comments, unnecessary_new
-// ignore_for_file: prefer_single_quotes
+// ignore_for_file: always_declare_return_types, prefer_single_quotes
+// ignore_for_file: prefer_collection_literals
 
 // Utilities for building JS ASTs at runtime.  Contains a builder class
 // and a parser that parses part of the language.
diff --git a/pkg/dev_compiler/lib/src/js_ast/nodes.dart b/pkg/dev_compiler/lib/src/js_ast/nodes.dart
index 74b6f9a..bed1271 100644
--- a/pkg/dev_compiler/lib/src/js_ast/nodes.dart
+++ b/pkg/dev_compiler/lib/src/js_ast/nodes.dart
@@ -3,6 +3,8 @@
 // BSD-style license that can be found in the LICENSE file.
 
 // ignore_for_file: slash_for_doc_comments, prefer_single_quotes
+// ignore_for_file: always_declare_return_types, prefer_final_fields
+// ignore_for_file: always_require_non_null_named_parameters
 
 part of js_ast;
 
diff --git a/pkg/dev_compiler/lib/src/js_ast/printer.dart b/pkg/dev_compiler/lib/src/js_ast/printer.dart
index 918cd1f..df80ee1 100644
--- a/pkg/dev_compiler/lib/src/js_ast/printer.dart
+++ b/pkg/dev_compiler/lib/src/js_ast/printer.dart
@@ -3,7 +3,8 @@
 // BSD-style license that can be found in the LICENSE file.
 
 // ignore_for_file: slash_for_doc_comments, unnecessary_const
-// ignore_for_file: prefer_single_quotes
+// ignore_for_file: always_declare_return_types, prefer_single_quotes
+// ignore_for_file: prefer_collection_literals, prefer_final_fields
 
 part of js_ast;
 
diff --git a/pkg/dev_compiler/lib/src/js_ast/source_map_printer.dart b/pkg/dev_compiler/lib/src/js_ast/source_map_printer.dart
index d9e7da8..867e905 100644
--- a/pkg/dev_compiler/lib/src/js_ast/source_map_printer.dart
+++ b/pkg/dev_compiler/lib/src/js_ast/source_map_printer.dart
@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// ignore_for_file: always_declare_return_types
+
 import 'package:source_maps/source_maps.dart' hide Printer;
 import 'package:source_span/source_span.dart' show SourceLocation;
 import 'js_ast.dart';
diff --git a/pkg/dev_compiler/lib/src/js_ast/template.dart b/pkg/dev_compiler/lib/src/js_ast/template.dart
index c985574..733b786 100644
--- a/pkg/dev_compiler/lib/src/js_ast/template.dart
+++ b/pkg/dev_compiler/lib/src/js_ast/template.dart
@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 // ignore_for_file: slash_for_doc_comments, prefer_single_quotes
+// ignore_for_file: always_declare_return_types, prefer_collection_literals
 
 part of js_ast;
 
diff --git a/pkg/dev_compiler/lib/src/kernel/command.dart b/pkg/dev_compiler/lib/src/kernel/command.dart
index 654d5a8..080d830 100644
--- a/pkg/dev_compiler/lib/src/kernel/command.dart
+++ b/pkg/dev_compiler/lib/src/kernel/command.dart
@@ -429,7 +429,7 @@
   }
 
   if (recordUsedInputs) {
-    Set<Uri> usedOutlines = Set<Uri>();
+    Set<Uri> usedOutlines = <Uri>{};
     if (useIncrementalCompiler) {
       compilerState.incrementalCompiler
           .updateNeededDillLibrariesWithHierarchy(result.classHierarchy, null);
diff --git a/pkg/dev_compiler/lib/src/kernel/compiler.dart b/pkg/dev_compiler/lib/src/kernel/compiler.dart
index c4205b1..f46dcd5 100644
--- a/pkg/dev_compiler/lib/src/kernel/compiler.dart
+++ b/pkg/dev_compiler/lib/src/kernel/compiler.dart
@@ -68,7 +68,7 @@
   final _constTable = _emitTemporaryId('CT');
 
   // Constant getters used to populate the constant table.
-  final _constLazyAccessors = List<js_ast.Method>();
+  final _constLazyAccessors = <js_ast.Method>[];
 
   /// Tracks the index in [moduleItems] where the const table must be inserted.
   /// Required for SDK builds due to internal circular dependencies.
@@ -131,7 +131,7 @@
 
   bool _superAllowed = true;
 
-  final _superHelpers = Map<String, js_ast.Method>();
+  final _superHelpers = <String, js_ast.Method>{};
 
   // Compilation of Kernel's [BreakStatement].
   //
@@ -232,8 +232,7 @@
     coreTypes ??= CoreTypes(component);
     var types = TypeEnvironment(coreTypes, hierarchy);
     var constants = DevCompilerConstants();
-    var nativeTypes = NativeTypeSet(coreTypes, constants,
-        enableNullSafety: options.enableNullSafety);
+    var nativeTypes = NativeTypeSet(coreTypes, constants);
     var jsTypeRep = JSTypeRep(types, hierarchy);
     var staticTypeContext = StatefulStaticTypeContext.stacked(types);
     return ProgramCompiler._(
@@ -753,7 +752,7 @@
     }
 
     bool shouldDefer(InterfaceType t) {
-      var visited = Set<DartType>();
+      var visited = <DartType>{};
       bool defer(DartType t) {
         if (t is InterfaceType) {
           var tc = t.classNode;
@@ -1670,8 +1669,8 @@
       }
     }
 
-    var getters = Map<String, Procedure>();
-    var setters = Map<String, Procedure>();
+    var getters = <String, Procedure>{};
+    var setters = <String, Procedure>{};
     for (var m in c.procedures) {
       if (m.isAbstract) continue;
       if (m.isGetter) {
@@ -2299,7 +2298,7 @@
     return _extensionTypes.isNativeInterface(c);
   }
 
-  var _forwardingCache = HashMap<Class, Map<String, Member>>();
+  final _forwardingCache = HashMap<Class, Map<String, Member>>();
 
   Member _lookupForwardedMember(Class c, String name) {
     // We only care about public methods.
@@ -2820,8 +2819,10 @@
       // TODO(jmesserly): should we disable source info for annotations?
       var savedUri = _currentUri;
       _currentUri = member.enclosingClass.fileUri;
-      result = js_ast.ArrayInitializer(
-          [result]..addAll(annotations.map(_instantiateAnnotation)));
+      result = js_ast.ArrayInitializer([
+        result,
+        for (var annotation in annotations) _instantiateAnnotation(annotation)
+      ]);
       _currentUri = savedUri;
     }
     return result;
@@ -2854,7 +2855,7 @@
       var savedUri = _currentUri;
       _currentUri = member.enclosingClass.fileUri;
       result = js_ast.ArrayInitializer(
-          [result]..addAll(metadata.map(_instantiateAnnotation)));
+          [result, for (var value in metadata) _instantiateAnnotation(value)]);
       _currentUri = savedUri;
     }
     return result;
@@ -4838,12 +4839,16 @@
         else
           _visitExpression(arg),
       if (node.named.isNotEmpty)
-        js_ast.ObjectInitializer(node.named.map(_emitNamedExpression).toList()),
+        js_ast.ObjectInitializer([
+          for (var arg in node.named) _emitNamedExpression(arg, isJsInterop)
+        ]),
     ];
   }
 
-  js_ast.Property _emitNamedExpression(NamedExpression arg) {
-    return js_ast.Property(propertyName(arg.name), _visitExpression(arg.value));
+  js_ast.Property _emitNamedExpression(NamedExpression arg,
+      [bool isJsInterop = false]) {
+    var value = isJsInterop ? _assertInterop(arg.value) : arg.value;
+    return js_ast.Property(propertyName(arg.name), _visitExpression(value));
   }
 
   /// Emits code for the `JS(...)` macro.
@@ -4958,9 +4963,9 @@
     var ctor = node.target;
     var ctorClass = ctor.enclosingClass;
     var args = node.arguments;
-    if (isJSAnonymousType(ctorClass)) return _emitObjectLiteral(args);
+    if (isJSAnonymousType(ctorClass)) return _emitObjectLiteral(args, ctor);
     var result = js_ast.New(_emitConstructorName(node.constructedType, ctor),
-        _emitArgumentList(args, types: false));
+        _emitArgumentList(args, types: false, target: ctor));
 
     return node.isConst ? canonicalizeConstObject(result) : result;
   }
@@ -5025,10 +5030,10 @@
 
   js_ast.Expression _emitJSInteropNew(Member ctor, Arguments args) {
     var ctorClass = ctor.enclosingClass;
-    if (isJSAnonymousType(ctorClass)) return _emitObjectLiteral(args);
+    if (isJSAnonymousType(ctorClass)) return _emitObjectLiteral(args, ctor);
     return js_ast.New(
         _emitConstructorName(_coreTypes.legacyRawType(ctorClass), ctor),
-        _emitArgumentList(args, types: false));
+        _emitArgumentList(args, types: false, target: ctor));
   }
 
   js_ast.Expression _emitMapImplType(InterfaceType type, {bool identity}) {
@@ -5053,8 +5058,8 @@
         emitNullability: false);
   }
 
-  js_ast.Expression _emitObjectLiteral(Arguments node) {
-    var args = _emitArgumentList(node, types: false);
+  js_ast.Expression _emitObjectLiteral(Arguments node, Member ctor) {
+    var args = _emitArgumentList(node, types: false, target: ctor);
     if (args.isEmpty) return js.call('{}');
     assert(args.single is js_ast.ObjectInitializer);
     return args.single;
@@ -5536,7 +5541,9 @@
         js.call('# || #.#', [constAliasId, _constTable, constAliasProperty]);
     constAliasCache[node] = constAccessor;
     var constJs = super.visitConstant(node);
-    moduleItems.add(js.statement('let #;', [constAliasId]));
+    // TODO(vsm): Change back to `let`.
+    // See https://github.com/dart-lang/sdk/issues/40380.
+    moduleItems.add(js.statement('var #;', [constAliasId]));
 
     var func = js_ast.Fun(
         [],
diff --git a/pkg/dev_compiler/lib/src/kernel/native_types.dart b/pkg/dev_compiler/lib/src/kernel/native_types.dart
index ab1d626..162c50b 100644
--- a/pkg/dev_compiler/lib/src/kernel/native_types.dart
+++ b/pkg/dev_compiler/lib/src/kernel/native_types.dart
@@ -37,8 +37,7 @@
   final _nativeTypes = HashSet<Class>.identity();
   final _pendingLibraries = HashSet<Library>.identity();
 
-  NativeTypeSet(this.coreTypes, this.constants,
-      {bool enableNullSafety = false}) {
+  NativeTypeSet(this.coreTypes, this.constants) {
     // First, core types:
     // TODO(vsm): If we're analyzing against the main SDK, those
     // types are not explicitly annotated.
@@ -62,16 +61,12 @@
     // listed below).
 
     // Second, html types - these are only searched if we use dart:html, etc.:
-    // TODO(39698) Remove this check and the named parameter once we don't have
-    // to exclude libraries from the forked NNBD sdk.
-    if (!enableNullSafety) {
-      _addPendingExtensionTypes(sdk.getLibrary('dart:html'));
-      _addPendingExtensionTypes(sdk.getLibrary('dart:indexed_db'));
-      _addPendingExtensionTypes(sdk.getLibrary('dart:svg'));
-      _addPendingExtensionTypes(sdk.getLibrary('dart:web_audio'));
-      _addPendingExtensionTypes(sdk.getLibrary('dart:web_gl'));
-      _addPendingExtensionTypes(sdk.getLibrary('dart:web_sql'));
-    }
+    _addPendingExtensionTypes(sdk.getLibrary('dart:html'));
+    _addPendingExtensionTypes(sdk.getLibrary('dart:indexed_db'));
+    _addPendingExtensionTypes(sdk.getLibrary('dart:svg'));
+    _addPendingExtensionTypes(sdk.getLibrary('dart:web_audio'));
+    _addPendingExtensionTypes(sdk.getLibrary('dart:web_gl'));
+    _addPendingExtensionTypes(sdk.getLibrary('dart:web_sql'));
   }
 
   void _addExtensionType(Class c, [bool mustBeNative = false]) {
diff --git a/pkg/dev_compiler/lib/src/kernel/property_model.dart b/pkg/dev_compiler/lib/src/kernel/property_model.dart
index fe3e379..a0d28e0 100644
--- a/pkg/dev_compiler/lib/src/kernel/property_model.dart
+++ b/pkg/dev_compiler/lib/src/kernel/property_model.dart
@@ -113,7 +113,7 @@
         }
 
         if (superclasses == null) {
-          superclasses = Set();
+          superclasses = <Class>{};
           void collectSupertypes(Class c) {
             if (!superclasses.add(c)) return;
             var s = c.superclass;
@@ -197,9 +197,9 @@
   /// super.
   final inheritedSetters = HashSet<String>();
 
-  final extensionMethods = Set<String>();
+  final extensionMethods = <String>{};
 
-  final extensionAccessors = Set<String>();
+  final extensionAccessors = <String>{};
 
   ClassPropertyModel.build(this.types, this.extensionTypes,
       VirtualFieldModel fieldModel, Class class_) {
diff --git a/pkg/dev_compiler/lib/src/kernel/target.dart b/pkg/dev_compiler/lib/src/kernel/target.dart
index 949004d..5ab0178 100644
--- a/pkg/dev_compiler/lib/src/kernel/target.dart
+++ b/pkg/dev_compiler/lib/src/kernel/target.dart
@@ -5,73 +5,23 @@
 import 'dart:collection';
 import 'dart:core' hide MapEntry;
 
+import 'package:_fe_analyzer_shared/src/messages/codes.dart'
+    show Message, LocatedMessage;
 import 'package:kernel/class_hierarchy.dart';
 import 'package:kernel/core_types.dart';
 import 'package:kernel/kernel.dart';
 import 'package:kernel/reference_from_index.dart';
+import 'package:kernel/target/changed_structure_notifier.dart';
 import 'package:kernel/target/targets.dart';
 import 'package:kernel/transformations/track_widget_constructor_locations.dart';
+import 'package:_js_interop_checks/js_interop_checks.dart';
 
 import 'constants.dart' show DevCompilerConstantsBackend;
 import 'kernel_helpers.dart';
 
 /// A kernel [Target] to configure the Dart Front End for dartdevc.
 class DevCompilerTarget extends Target {
-  // TODO(39698) Turn these back into const lists returned from the getters
-  // once we don't have to exclude libraries from the forked NNBD sdk.
-  List<String> _extraRequiredLibraries;
-  List<String> _extraIndexedLibraries;
-
-  DevCompilerTarget(this.flags)
-      : _extraRequiredLibraries = [
-          'dart:_runtime',
-          'dart:_debugger',
-          'dart:_foreign_helper',
-          'dart:_interceptors',
-          'dart:_internal',
-          'dart:_isolate_helper',
-          'dart:_js_helper',
-          'dart:_js_mirrors',
-          'dart:_js_primitives',
-          'dart:_metadata',
-          'dart:_native_typed_data',
-          'dart:async',
-          'dart:collection',
-          'dart:convert',
-          'dart:developer',
-          if (!flags.enableNullSafety) 'dart:io',
-          'dart:isolate',
-          'dart:js',
-          'dart:js_util',
-          'dart:math',
-          'dart:mirrors',
-          'dart:typed_data',
-          if (!flags.enableNullSafety) ...[
-            'dart:indexed_db',
-            'dart:html',
-            'dart:html_common',
-            'dart:svg',
-            'dart:web_audio',
-            'dart:web_gl',
-            'dart:web_sql'
-          ]
-        ],
-        _extraIndexedLibraries = [
-          'dart:async',
-          'dart:collection',
-          if (!flags.enableNullSafety) ...['dart:html', 'dart:indexed_db'],
-          'dart:math',
-          if (!flags.enableNullSafety) ...[
-            'dart:svg',
-            'dart:web_audio',
-            'dart:web_gl',
-            'dart:web_sql'
-          ],
-          'dart:_interceptors',
-          'dart:_js_helper',
-          'dart:_native_typed_data',
-          'dart:_runtime',
-        ];
+  DevCompilerTarget(this.flags);
 
   final TargetFlags flags;
 
@@ -87,11 +37,55 @@
   String get name => 'dartdevc';
 
   @override
-  List<String> get extraRequiredLibraries => _extraRequiredLibraries;
+  List<String> get extraRequiredLibraries => const [
+        'dart:_runtime',
+        'dart:_debugger',
+        'dart:_foreign_helper',
+        'dart:_interceptors',
+        'dart:_internal',
+        'dart:_isolate_helper',
+        'dart:_js_helper',
+        'dart:_js_mirrors',
+        'dart:_js_primitives',
+        'dart:_metadata',
+        'dart:_native_typed_data',
+        'dart:async',
+        'dart:collection',
+        'dart:convert',
+        'dart:developer',
+        'dart:io',
+        'dart:isolate',
+        'dart:js',
+        'dart:js_util',
+        'dart:math',
+        'dart:mirrors',
+        'dart:typed_data',
+        'dart:indexed_db',
+        'dart:html',
+        'dart:html_common',
+        'dart:svg',
+        'dart:web_audio',
+        'dart:web_gl',
+        'dart:web_sql'
+      ];
 
   // The libraries required to be indexed via CoreTypes.
   @override
-  List<String> get extraIndexedLibraries => _extraIndexedLibraries;
+  List<String> get extraIndexedLibraries => const [
+        'dart:async',
+        'dart:collection',
+        'dart:html',
+        'dart:indexed_db',
+        'dart:math',
+        'dart:svg',
+        'dart:web_audio',
+        'dart:web_gl',
+        'dart:web_sql',
+        'dart:_interceptors',
+        'dart:_js_helper',
+        'dart:_native_typed_data',
+        'dart:_runtime',
+      ];
 
   @override
   bool mayDefineRestrictedType(Uri uri) =>
@@ -141,9 +135,13 @@
       Map<String, String> environmentDefines,
       DiagnosticReporter diagnosticReporter,
       ReferenceFromIndex referenceFromIndex,
-      {void logger(String msg)}) {
+      {void logger(String msg),
+      ChangedStructureNotifier changedStructureNotifier}) {
     for (var library in libraries) {
       _CovarianceTransformer(library).transform();
+      JsInteropChecks(
+              diagnosticReporter as DiagnosticReporter<Message, LocatedMessage>)
+          .visitLibrary(library);
     }
   }
 
@@ -153,7 +151,8 @@
       CoreTypes coreTypes,
       List<Library> libraries,
       DiagnosticReporter diagnosticReporter,
-      {void logger(String msg)}) {
+      {void logger(String msg),
+      ChangedStructureNotifier changedStructureNotifier}) {
     if (flags.trackWidgetCreation) {
       _widgetTracker ??= WidgetCreatorTracker();
       _widgetTracker.transform(component, libraries);
@@ -244,13 +243,13 @@
   ///
   /// [transform] uses this list to eliminate covariance flags for members that
   /// aren't in [_checkedMembers].
-  final _privateProcedures = List<Procedure>();
+  final _privateProcedures = <Procedure>[];
 
   /// List of private instance fields.
   ///
   /// [transform] uses this list to eliminate covariance flags for members that
   /// aren't in [_checkedMembers].
-  final _privateFields = List<Field>();
+  final _privateFields = <Field>[];
 
   final Library _library;
 
diff --git a/pkg/dev_compiler/lib/src/kernel/type_table.dart b/pkg/dev_compiler/lib/src/kernel/type_table.dart
index 6721e0a..bb751d1 100644
--- a/pkg/dev_compiler/lib/src/kernel/type_table.dart
+++ b/pkg/dev_compiler/lib/src/kernel/type_table.dart
@@ -9,7 +9,7 @@
 import '../js_ast/js_ast.dart' show js;
 
 Set<TypeParameter> freeTypeParameters(DartType t) {
-  var result = Set<TypeParameter>();
+  var result = <TypeParameter>{};
   void find(DartType t) {
     if (t is TypeParameterType) {
       result.add(t.parameter);
@@ -122,7 +122,9 @@
     if (name != null) {
       js_ast.Expression init = _defs.remove(t);
       assert(init != null);
-      return js.statement('let # = () => ((# = #.constFn(#))());',
+      // TODO(vsm): Change back to `let`.
+      // See https://github.com/dart-lang/sdk/issues/40380.
+      return js.statement('var # = () => ((# = #.constFn(#))());',
           [name, name, _runtimeModule, init]);
     }
     return null;
diff --git a/pkg/dev_compiler/test/js/builder_test.dart b/pkg/dev_compiler/test/js/builder_test.dart
index 0dfae14..9a1ac18 100644
--- a/pkg/dev_compiler/test/js/builder_test.dart
+++ b/pkg/dev_compiler/test/js/builder_test.dart
@@ -6,12 +6,13 @@
 MiniJsParser _parser(String src) =>
     MiniJsParser(src.replaceAll(_prenumberedPlaceholders, '#'));
 
-_check(Node node, String expected) =>
+void _check(Node node, String expected) =>
     expect(node.toString(), 'js_ast `$expected`');
 
-_checkStatement(String src) => _check(_parser(src).parseStatement(), src);
+void _checkStatement(String src) => _check(_parser(src).parseStatement(), src);
 
-_checkExpression(String src) => _check(_parser(src).parseExpression(), src);
+void _checkExpression(String src) =>
+    _check(_parser(src).parseExpression(), src);
 
 void main() {
   group('MiniJsParser', () {
diff --git a/pkg/dev_compiler/test/modular_suite.dart b/pkg/dev_compiler/test/modular_suite.dart
index f5f85b3..e76144a 100644
--- a/pkg/dev_compiler/test/modular_suite.dart
+++ b/pkg/dev_compiler/test/modular_suite.dart
@@ -16,7 +16,8 @@
 Options _options;
 String _dartdevcScript;
 String _kernelWorkerScript;
-main(List<String> args) async {
+
+void main(List<String> args) async {
   _options = Options.parse(args);
   await _resolveScripts();
   await runSuite(
diff --git a/pkg/dev_compiler/test/modular_suite_nnbd.dart b/pkg/dev_compiler/test/modular_suite_nnbd.dart
index a8eae18..716d3db 100644
--- a/pkg/dev_compiler/test/modular_suite_nnbd.dart
+++ b/pkg/dev_compiler/test/modular_suite_nnbd.dart
@@ -16,7 +16,8 @@
 Options _options;
 String _dartdevcScript;
 String _kernelWorkerScript;
-main(List<String> args) async {
+
+void main(List<String> args) async {
   _options = Options.parse(args);
   await _resolveScripts();
   await runSuite(
diff --git a/pkg/dev_compiler/test/nullable_inference_test.dart b/pkg/dev_compiler/test/nullable_inference_test.dart
index 185899c..2b1d6e0 100644
--- a/pkg/dev_compiler/test/nullable_inference_test.dart
+++ b/pkg/dev_compiler/test/nullable_inference_test.dart
@@ -534,7 +534,7 @@
   _TestRecursiveVisitor(this.librariesFromDill);
 
   @override
-  visitComponent(Component node) {
+  void visitComponent(Component node) {
     var coreTypes = CoreTypes(node);
     var hierarchy = ClassHierarchy(node, coreTypes);
     var jsTypeRep = JSTypeRep(
@@ -553,7 +553,7 @@
   }
 
   @override
-  visitLibrary(Library node) {
+  void visitLibrary(Library node) {
     _staticTypeContext.enterLibrary(node);
     if (librariesFromDill.contains(node) ||
         node.importUri.scheme == 'package' &&
@@ -565,28 +565,28 @@
   }
 
   @override
-  visitField(Field node) {
+  void visitField(Field node) {
     _staticTypeContext.enterMember(node);
     super.visitField(node);
     _staticTypeContext.leaveMember(node);
   }
 
   @override
-  visitConstructor(Constructor node) {
+  void visitConstructor(Constructor node) {
     _staticTypeContext.enterMember(node);
     super.visitConstructor(node);
     _staticTypeContext.leaveMember(node);
   }
 
   @override
-  visitProcedure(Procedure node) {
+  void visitProcedure(Procedure node) {
     _staticTypeContext.enterMember(node);
     super.visitProcedure(node);
     _staticTypeContext.leaveMember(node);
   }
 
   @override
-  visitFunctionNode(FunctionNode node) {
+  void visitFunctionNode(FunctionNode node) {
     _functionNesting++;
     if (_functionNesting == 1) {
       inference.enterFunction(node);
@@ -603,7 +603,7 @@
   NotNullCollector(Set<Library> librariesFromDill) : super(librariesFromDill);
 
   @override
-  defaultExpression(Expression node) {
+  void defaultExpression(Expression node) {
     if (!inference.isNullable(node)) {
       notNullExpressions.add(node);
     }
@@ -615,7 +615,7 @@
   ExpectAllNotNull(Set<Library> librariesFromDill) : super(librariesFromDill);
 
   @override
-  defaultExpression(Expression node) {
+  void defaultExpression(Expression node) {
     expect(inference.isNullable(node), false,
         reason: 'expression `$node` should be inferred as not-null');
     super.defaultExpression(node);
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/null_instance_field.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/null_instance_field.dart
index c04266c..2a36f88 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/null_instance_field.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/null_instance_field.dart
@@ -6,7 +6,7 @@
   /*1:main*/ test(Class());
 }
 
-test(c) {
+void test(c) {
   /*ddc.2:test*/ c.field. /*ddk.2:test*/ method();
 }
 
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/null_interceptor_field.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/null_interceptor_field.dart
index beec13d..d43b10b 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/null_interceptor_field.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/null_interceptor_field.dart
@@ -3,7 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 class MyType {
-  get length => 3; // ensures we build an interceptor for `.length`
+  int get length => 3; // ensures we build an interceptor for `.length`
 }
 
 void main() {
@@ -13,4 +13,4 @@
   confuse(null). /*1:main*/ length; // called through the interceptor
 }
 
-confuse(x) => x;
+dynamic confuse(x) => x;
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/rethrow.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/rethrow.dart
index 82a3819..908eb8f 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/rethrow.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/rethrow.dart
@@ -6,7 +6,7 @@
   /*1:main*/ test();
 }
 
-test() {
+void test() {
   try {
     /*2:test*/ throw '>ExceptionMarker<';
     // ignore: UNUSED_CATCH_CLAUSE
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_async.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_async.dart
index ea6ab10..e1e10f8 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_async.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_async.dart
@@ -6,6 +6,6 @@
   /*1:main*/ test();
 }
 
-test /*ddk.2:test*/ () /*ddc.2:test*/ async {
+void test /*ddk.2:test*/ () /*ddc.2:test*/ async {
   /*3:test*/ throw '>ExceptionMarker<';
 }
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_awaited_async.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_awaited_async.dart
index 5e4721a..0458fc9 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_awaited_async.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_awaited_async.dart
@@ -6,10 +6,10 @@
   /*1:main*/ test1();
 }
 
-test1 /*ddk.2:test1*/ () /*ddc.2:test1*/ async {
+Future<void> test1 /*ddk.2:test1*/ () /*ddc.2:test1*/ async {
   await /*3:test1*/ test2();
 }
 
-test2 /*ddk.4:test2*/ () /*ddc.4:test2*/ async {
+Future<void> test2 /*ddk.4:test2*/ () /*ddc.4:test2*/ async {
   /*5:test2*/ throw '>ExceptionMarker<';
 }
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_constructor_from_async.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_constructor_from_async.dart
index 6d251e8..37467ae 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_constructor_from_async.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_constructor_from_async.dart
@@ -7,7 +7,7 @@
   /*1:main*/ test();
 }
 
-test /*ddk.2:test*/ () /*ddc.2:test*/ async {
+void test /*ddk.2:test*/ () /*ddc.2:test*/ async {
   // ignore: UNUSED_LOCAL_VARIABLE
   var c = /*3:test*/ Class();
 }
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_instance_method.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_instance_method.dart
index 2fbc97f..84dac4e3 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_instance_method.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_instance_method.dart
@@ -8,7 +8,7 @@
 }
 
 class Class {
-  test() {
+  void test() {
     /*2:Class.new.test*/ throw '>ExceptionMarker<';
   }
 }
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_static_method.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_static_method.dart
index 658db6a..e0b974c 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_static_method.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_static_method.dart
@@ -7,7 +7,7 @@
 }
 
 class Class {
-  static test() {
+  static void test() {
     /*2:Function.test*/ throw '>ExceptionMarker<';
   }
 }
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_top_level_method.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_top_level_method.dart
index d03d29a..799c9c0 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_top_level_method.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_top_level_method.dart
@@ -6,6 +6,6 @@
   /*1:main*/ test();
 }
 
-test() {
+void test() {
   /*2:test*/ throw 'throw me';
 }
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_top_level_method_from_async.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_top_level_method_from_async.dart
index f5240ee..06ec99f 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_top_level_method_from_async.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_top_level_method_from_async.dart
@@ -6,10 +6,10 @@
   /*1:main*/ test1();
 }
 
-test1 /*ddk.2:test1*/ () /*ddc.2:test1*/ async {
+Future<void> test1 /*ddk.2:test1*/ () /*ddc.2:test1*/ async {
   /*3:test1*/ test2();
 }
 
-test2() {
+void test2() {
   /*4:test2*/ throw '>ExceptionMarker<';
 }
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_try_catch.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_try_catch.dart
index 7effa59..d02b31b 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_try_catch.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_try_catch.dart
@@ -6,7 +6,7 @@
   /*1:main*/ test();
 }
 
-test() {
+void test() {
   try {
     /*2:test*/ throw '>ExceptionMarker<';
     // ignore: UNUSED_CATCH_CLAUSE
diff --git a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_try_finally.dart b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_try_finally.dart
index 7bfcd1a..211f9ed 100644
--- a/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_try_finally.dart
+++ b/pkg/dev_compiler/test/sourcemap/stacktrace_testfiles/throw_in_try_finally.dart
@@ -6,7 +6,7 @@
   /*1:main*/ test();
 }
 
-test() {
+void test() {
   try {
     /*2:test*/ throw '>ExceptionMarker<';
   } finally {}
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/breakpoint_on_function_line_breaks_in_body.dart b/pkg/dev_compiler/test/sourcemap/testfiles/breakpoint_on_function_line_breaks_in_body.dart
index efcab4c..b38f0821 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/breakpoint_on_function_line_breaks_in_body.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/breakpoint_on_function_line_breaks_in_body.dart
@@ -6,6 +6,6 @@
   foo();
 }
 
-/*bl*/ /*nb*/ foo() {
+/*bl*/ /*nb*/ void foo() {
   /*s:1*/ print('hello');
 }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/hello_async.dart b/pkg/dev_compiler/test/sourcemap/testfiles/hello_async.dart
index 52a6c72..62fba8c 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/hello_async.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/hello_async.dart
@@ -8,7 +8,7 @@
   /*s:4*/
 }
 
-foo() /*sl:2*/ async {
+Future<void> foo() /*sl:2*/ async {
   print('hello from foo');
 /*s:3*/
 }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/hello_call.dart b/pkg/dev_compiler/test/sourcemap/testfiles/hello_call.dart
index c22f9c1..1f28925 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/hello_call.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/hello_call.dart
@@ -7,6 +7,6 @@
   /*s:1*/ foo();
 }
 
-foo() {
+void foo() {
   /*s:2*/ print('hello from foo');
 }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/hello_class_call.dart b/pkg/dev_compiler/test/sourcemap/testfiles/hello_class_call.dart
index de068a9..53a6943 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/hello_class_call.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/hello_class_call.dart
@@ -10,17 +10,17 @@
 }
 
 class Foo {
-  foo() {
+  int foo() {
     return /*bc:1*/ bar() + /*bc:2*/ baz /*nbc*/ ();
     /*nbb:0:1*/
   }
 
-  bar() {
+  int bar() {
     return 42;
     /*nbb:0:1*/
   }
 
-  baz() {
+  int baz() {
     return 42;
     /*nbb:0:1*/
   }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/hello_sane_column_on_print_return_value.dart b/pkg/dev_compiler/test/sourcemap/testfiles/hello_sane_column_on_print_return_value.dart
index 2478dfa..2f1663c 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/hello_sane_column_on_print_return_value.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/hello_sane_column_on_print_return_value.dart
@@ -6,6 +6,6 @@
   /*bc:3*/ print(/*bc:1*/ foo());
 }
 
-foo() {
+String foo() {
   return /*bc:2*/ 'foo!';
 }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/method_call_with_named_parameters.dart b/pkg/dev_compiler/test/sourcemap/testfiles/method_call_with_named_parameters.dart
index 6eb9919..2ea7844 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/method_call_with_named_parameters.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/method_call_with_named_parameters.dart
@@ -7,7 +7,7 @@
   /*nbb:0:4*/
 }
 
-foo(int bar, {int /*bc:3*/ baz}) {
+void foo(int bar, {int /*bc:3*/ baz}) {
   /*bc:4*/ print('foo!');
 }
 
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/method_call_with_named_parameters_no_given.dart b/pkg/dev_compiler/test/sourcemap/testfiles/method_call_with_named_parameters_no_given.dart
index acbfdba..4f5ee7d 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/method_call_with_named_parameters_no_given.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/method_call_with_named_parameters_no_given.dart
@@ -7,7 +7,7 @@
   /*nbb:0:3*/
 }
 
-foo(int bar, {int /*bc:2*/ baz}) {
+void foo(int bar, {int /*bc:2*/ baz}) {
   /*bc:3*/ print('foo!');
 }
 
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/next_through_is_and_as_test.dart b/pkg/dev_compiler/test/sourcemap/testfiles/next_through_is_and_as_test.dart
index 406b49b..45de474 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/next_through_is_and_as_test.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/next_through_is_and_as_test.dart
@@ -32,4 +32,4 @@
   }
 }
 
-foo() => 42;
+dynamic foo() => 42;
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_on_super_test.dart b/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_on_super_test.dart
index de8c40d..801b41e 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_on_super_test.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_on_super_test.dart
@@ -5,9 +5,9 @@
 /*Debugger:stepOver*/
 
 class Class2 {
-  operator [](index) => index;
+  dynamic operator [](index) => index;
 
-  code() {
+  dynamic code() {
     this[42];
     return this[42];
   }
@@ -15,7 +15,7 @@
 
 class Class3 extends Class2 {
   @override
-  code() {
+  dynamic code() {
     /*bl*/ /*sl:1*/ super[42];
     /*sl:2*/ return super[42];
   }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_on_this_test.dart b/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_on_this_test.dart
index f0f1130..d6c74bf 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_on_this_test.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_on_this_test.dart
@@ -5,9 +5,9 @@
 /*Debugger:stepOver*/
 
 class Class2 {
-  operator [](index) => index;
+  dynamic operator [](index) => index;
 
-  code() {
+  dynamic code() {
     /*bl*/ /*sl:1*/ this[42]; // DDK fails to hover on `this`
     return /*sl:2*/ this[42];
   }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_test.dart b/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_test.dart
index 90fa680..23c41eb 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_test.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/next_through_operator_bracket_test.dart
@@ -5,9 +5,9 @@
 /*Debugger:stepOver*/
 
 class Class2 {
-  operator [](index) => index;
+  dynamic operator [](index) => index;
 
-  code() {
+  dynamic code() {
     this[42];
     return this[42];
   }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/next_through_throw.dart b/pkg/dev_compiler/test/sourcemap/testfiles/next_through_throw.dart
index 1d7b275..d62bd94 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/next_through_throw.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/next_through_throw.dart
@@ -12,6 +12,6 @@
   }
 }
 
-foo() {
+int foo() {
   return 42;
 }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/no_mapping_on_function_line.dart b/pkg/dev_compiler/test/sourcemap/testfiles/no_mapping_on_function_line.dart
index 9534d13..4683e61 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/no_mapping_on_function_line.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/no_mapping_on_function_line.dart
@@ -7,6 +7,6 @@
   foo();
 }
 
-foo() {
+void foo() {
   print('hello');
 }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/step_through_async_star_yield.dart b/pkg/dev_compiler/test/sourcemap/testfiles/step_through_async_star_yield.dart
index bb17afc..cef8d5a 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/step_through_async_star_yield.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/step_through_async_star_yield.dart
@@ -9,15 +9,15 @@
   print('Done!');
 }
 
-foobar() async* {
+dynamic foobar() async* {
   /*bc:4*/ yield /*bc:1*/ foo() /*bc:3*/ + /*bc:2*/ bar();
   /*bc:8*/ yield /*bc:5*/ bar() /*bc:7*/ * /*bc:6*/ foo();
 }
 
-foo() {
+dynamic foo() {
   return 42;
 }
 
-bar() {
+dynamic bar() {
   return 3;
 }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/step_through_await_for.dart b/pkg/dev_compiler/test/sourcemap/testfiles/step_through_await_for.dart
index a217330..20fc828 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/step_through_await_for.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/step_through_await_for.dart
@@ -13,7 +13,7 @@
   /*s:8*/
 }
 
-foobar() async* {
+Stream<int> foobar() async* {
   // The testing framework should not step into the 'real body' at all.
   /*nb*/
   yield 1;
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/step_through_conditional_expression.dart b/pkg/dev_compiler/test/sourcemap/testfiles/step_through_conditional_expression.dart
index c756961..519529c 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/step_through_conditional_expression.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/step_through_conditional_expression.dart
@@ -13,10 +13,10 @@
   return false;
 }
 
-bar() {
+String bar() {
   return 'bar';
 }
 
-baz() {
+String baz() {
   return 'baz';
 }
diff --git a/pkg/dev_compiler/test/sourcemap/testfiles/step_through_if_and_identical.dart b/pkg/dev_compiler/test/sourcemap/testfiles/step_through_if_and_identical.dart
index 76049d5..33e7273 100644
--- a/pkg/dev_compiler/test/sourcemap/testfiles/step_through_if_and_identical.dart
+++ b/pkg/dev_compiler/test/sourcemap/testfiles/step_through_if_and_identical.dart
@@ -13,10 +13,10 @@
   }
 }
 
-foo() {
+dynamic foo() {
   return 42;
 }
 
-bar() {
+dynamic bar() {
   return 43;
 }
diff --git a/pkg/dev_compiler/tool/check_nnbd_sdk.dart b/pkg/dev_compiler/tool/check_nnbd_sdk.dart
index ae9941c..9b52d5f 100644
--- a/pkg/dev_compiler/tool/check_nnbd_sdk.dart
+++ b/pkg/dev_compiler/tool/check_nnbd_sdk.dart
@@ -50,6 +50,7 @@
   File.fromUri(emptyProgramUri).writeAsStringSync('''
 import 'dart:js';
 import 'dart:js_util';
+import 'dart:html';
 
 main() {}
 ''');
@@ -101,11 +102,40 @@
     } else {
       // Fail.
       print('Golden file does not match.');
-      var diff = Process.runSync('diff', [goldenFile.path, errorFile.path]);
-      print(diff.stdout);
       print('\nTo update the golden file, run:'
           '\n  ${Platform.executable} ${Platform.script} '
           '${argv.join(' ')} --update-golden');
+
+      // Compare the two sorted lists to show what errors changed.  Note, we
+      // don't use `diff` as an external tool because it is not available on
+      // windows bots.
+      var toAdd = <String>[];
+      var toRemove = <String>[];
+      var goldenList = golden.trim().split('\n');
+      int i = 0, j = 0;
+      for (; i < errorList.length && j < goldenList.length;) {
+        int compare = errorList[i].compareTo(goldenList[j]);
+        if (compare == 0) {
+          i++;
+          j++;
+        } else if (compare < 0) {
+          toAdd.add(errorList[i]);
+          i++;
+        } else {
+          toRemove.add(goldenList[j]);
+          j++;
+        }
+      }
+      for (; i < errorList.length; i++) {
+        toAdd.add(errorList[i]);
+      }
+      for (; j < goldenList.length; j++) {
+        toRemove.add(goldenList[j]);
+      }
+      print('\nNew errors:');
+      print(toAdd.join('\n'));
+      print('\nErrors that can be removed from the golden file:');
+      print(toRemove.join('\n'));
       exit(1);
     }
   }
diff --git a/pkg/dev_compiler/tool/compile_dartdevc_sdk.dart b/pkg/dev_compiler/tool/compile_dartdevc_sdk.dart
index 097a40a..f24c12e 100644
--- a/pkg/dev_compiler/tool/compile_dartdevc_sdk.dart
+++ b/pkg/dev_compiler/tool/compile_dartdevc_sdk.dart
@@ -9,7 +9,7 @@
 import 'dart:io';
 import 'package:dev_compiler/src/kernel/command.dart';
 
-main(List<String> args) async {
+void main(List<String> args) async {
   var result = await compileSdkFromDill(args);
   exitCode = result.exitCode;
 }
diff --git a/pkg/dev_compiler/tool/dart2js_nnbd_sdk_error_golden.txt b/pkg/dev_compiler/tool/dart2js_nnbd_sdk_error_golden.txt
new file mode 100644
index 0000000..62cba23
--- /dev/null
+++ b/pkg/dev_compiler/tool/dart2js_nnbd_sdk_error_golden.txt
@@ -0,0 +1,104 @@
+ERROR|COMPILE_TIME_ERROR|INCONSISTENT_INHERITANCE|lib/_internal/js_runtime/lib/interceptors.dart|1655|7|5|Superinterfaces don't have a valid override for '&': int.& (&), JSNumber.& (&).
+ERROR|COMPILE_TIME_ERROR|INCONSISTENT_INHERITANCE|lib/_internal/js_runtime/lib/interceptors.dart|1655|7|5|Superinterfaces don't have a valid override for '<<': int.<< (<<), JSNumber.<< (<<).
+ERROR|COMPILE_TIME_ERROR|INCONSISTENT_INHERITANCE|lib/_internal/js_runtime/lib/interceptors.dart|1655|7|5|Superinterfaces don't have a valid override for '>>': int.>> (>>), JSNumber.>> (>>).
+ERROR|COMPILE_TIME_ERROR|INCONSISTENT_INHERITANCE|lib/_internal/js_runtime/lib/interceptors.dart|1655|7|5|Superinterfaces don't have a valid override for '\|': int.\| (\|), JSNumber.\| (\|).
+ERROR|COMPILE_TIME_ERROR|INCONSISTENT_INHERITANCE|lib/_internal/js_runtime/lib/interceptors.dart|1655|7|5|Superinterfaces don't have a valid override for '^': int.^ (^), JSNumber.^ (^).
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/_internal/js_runtime/lib/interceptors.dart|1153|7|14|'JSArray.[]=' ('void Function(int, E)') isn't a valid override of 'JSMutableIndexable.[]=' ('void Function(int, dynamic)').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/_internal/js_runtime/lib/interceptors.dart|1155|7|12|'JSArray.[]=' ('void Function(int, E)') isn't a valid override of 'JSMutableIndexable.[]=' ('void Function(int, dynamic)').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/_internal/js_runtime/lib/interceptors.dart|1157|7|17|'JSArray.[]=' ('void Function(int, E)') isn't a valid override of 'JSMutableIndexable.[]=' ('void Function(int, dynamic)').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/_internal/js_runtime/lib/native_typed_data.dart|708|17|3|'NativeTypedArrayOfDouble.[]=' ('void Function(int, double)') isn't a valid override of 'JSMutableIndexable.[]=' ('void Function(int, dynamic)').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/_internal/js_runtime/lib/native_typed_data.dart|729|17|3|'NativeTypedArrayOfInt.[]=' ('void Function(int, int)') isn't a valid override of 'JSMutableIndexable.[]=' ('void Function(int, dynamic)').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/js/js.dart|351|17|3|'JsArray.[]=' ('void Function(dynamic, E)') isn't a valid override of 'JsObject.[]=' ('void Function(dynamic, dynamic)').
+ERROR|STATIC_TYPE_WARNING|UNDEFINED_OPERATOR|lib/_internal/js_runtime/lib/interceptors.dart|1672|28|1|The operator '&' isn't defined for the type 'JSInt'.
+ERROR|STATIC_TYPE_WARNING|UNDEFINED_OPERATOR|lib/_internal/js_runtime/lib/interceptors.dart|1674|27|1|The operator '&' isn't defined for the type 'JSInt'.
+ERROR|STATIC_TYPE_WARNING|UNDEFINED_OPERATOR|lib/_internal/js_runtime/lib/interceptors.dart|1677|17|1|The operator '&' isn't defined for the type 'JSInt'.
+ERROR|STATIC_TYPE_WARNING|UNDEFINED_OPERATOR|lib/_internal/js_runtime/lib/interceptors.dart|1682|18|1|The operator '&' isn't defined for the type 'JSInt'.
+ERROR|STATIC_TYPE_WARNING|UNDEFINED_OPERATOR|lib/_internal/js_runtime/lib/interceptors.dart|1682|44|1|The operator '&' isn't defined for the type 'JSInt'.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|12140|3|7|All final variables must be initialized, but '_attributes', '_childElementCount', and 21 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|15319|3|15|All final variables must be initialized, but 'elements', 'form', and 4 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|15992|3|11|All final variables must be initialized, but 'length' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|1760|3|13|All final variables must be initialized, but 'form', 'labels', and 3 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|17995|3|13|All final variables must be initialized, but '_get_contentWindow' and 'sandbox' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|18185|3|12|All final variables must be initialized, but 'complete', 'currentSrc', and 2 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|18294|3|12|All final variables must be initialized, but '_get_valueAsDate', 'entries', and 6 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|19245|3|12|All final variables must be initialized, but 'control' and 'form' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|19274|3|13|All final variables must be initialized, but 'form' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|19324|3|11|All final variables must be initialized, but 'import', 'relList', and 2 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|19455|3|10|All final variables must be initialized, but 'areas' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|19559|3|12|All final variables must be initialized, but 'audioDecodedByteCount', 'audioTracks', and 18 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|20673|3|12|All final variables must be initialized, but 'labels' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|22075|3|4|All final variables must be initialized, but 'baseUri', 'childNodes', and 11 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|22804|3|13|All final variables must be initialized, but '_get_contentWindow', 'form', and 3 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|23190|3|13|All final variables must be initialized, but 'form' and 'index' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|23241|3|13|All final variables must be initialized, but 'form', 'htmlFor', and 5 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|24751|3|15|All final variables must be initialized, but 'labels' and 'position' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|26240|3|13|All final variables must be initialized, but 'form', 'labels', and 4 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|27806|3|12|All final variables must be initialized, but 'sheet' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|27976|3|16|All final variables must be initialized, but 'cellIndex' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|28075|3|12|All final variables must be initialized, but '_rows' and '_tBodies' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|28161|3|15|All final variables must be initialized, but '_cells', 'rowIndex', and 1 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|28217|3|19|All final variables must be initialized, but '_rows' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|28271|3|15|All final variables must be initialized, but 'content' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|28344|3|15|All final variables must be initialized, but 'form', 'labels', and 5 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|29082|3|12|All final variables must be initialized, but 'readyState' and 'track' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|29888|3|12|All final variables must be initialized, but 'decodedFrameCount', 'droppedFrameCount', and 2 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|38892|3|8|All final variables must be initialized, but 'sourceCapabilities' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|453|3|13|All final variables must be initialized, but 'origin' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|8511|3|15|All final variables must be initialized, but 'options' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|972|3|11|All final variables must be initialized, but 'origin' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1031|3|14|All final variables must be initialized, but 'height', 'result', and 3 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1194|3|21|All final variables must be initialized, but 'height', 'in1', and 6 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1245|3|14|All final variables must be initialized, but 'height', 'href', and 5 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1294|3|14|All final variables must be initialized, but 'height', 'result', and 3 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1336|3|18|All final variables must be initialized, but 'in1' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1366|3|19|All final variables must be initialized, but 'height', 'in1', and 7 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1418|3|15|All final variables must be initialized, but 'dx', 'dy', and 6 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1466|3|19|All final variables must be initialized, but 'x', 'y', and 1 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1503|3|25|All final variables must be initialized, but 'height', 'in1', and 9 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1557|3|18|All final variables must be initialized, but 'limitingConeAngle', 'pointsAtX', and 6 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1604|3|13|All final variables must be initialized, but 'height', 'in1', and 4 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1649|3|19|All final variables must be initialized, but 'baseFrequencyX', 'baseFrequencyY', and 9 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1715|3|13|All final variables must be initialized, but 'filterUnits', 'height', and 5 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1796|3|20|All final variables must be initialized, but 'height', 'width', and 2 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1846|3|15|All final variables must be initialized, but 'pathLength' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1873|3|15|All final variables must be initialized, but 'farthestViewportElement', 'nearestViewportElement', and 3 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|1914|3|12|All final variables must be initialized, but 'height', 'href', and 4 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2076|3|11|All final variables must be initialized, but 'x1', 'x2', and 2 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2105|3|21|All final variables must be initialized, but 'x1', 'x2', and 2 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2134|3|13|All final variables must be initialized, but 'markerHeight', 'markerUnits', and 7 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2191|3|11|All final variables must be initialized, but 'height', 'maskContentUnits', and 6 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2407|3|14|All final variables must be initialized, but 'height', 'href', and 10 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2508|3|14|All final variables must be initialized, but 'animatedPoints' and 'points' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2533|3|15|All final variables must be initialized, but 'animatedPoints' and 'points' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2602|3|21|All final variables must be initialized, but 'cx', 'cy', and 4 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2655|3|11|All final variables must be initialized, but 'height', 'rx', and 4 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2688|3|13|All final variables must be initialized, but 'href' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2744|3|11|All final variables must be initialized, but 'gradientOffset' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|2844|3|12|All final variables must be initialized, but 'sheet' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3181|3|10|All final variables must be initialized, but 'ownerSvgElement' and 'viewportElement' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3354|3|13|All final variables must be initialized, but 'currentTranslate', 'height', and 5 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3476|3|13|All final variables must be initialized, but 'preserveAspectRatio' and 'viewBox' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3536|3|18|All final variables must be initialized, but 'lengthAdjust' and 'textLength' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3603|3|15|All final variables must be initialized, but 'href', 'method', and 2 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3643|3|22|All final variables must be initialized, but 'dx', 'dy', and 3 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3852|3|10|All final variables must be initialized, but 'height', 'href', and 3 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3885|3|11|All final variables must be initialized, but 'preserveAspectRatio' and 'viewBox' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3932|3|16|All final variables must be initialized, but 'gradientTransform', 'gradientUnits', and 2 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|396|3|16|All final variables must be initialized, but 'requiredExtensions', 'systemLanguage', and 1 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|439|3|13|All final variables must be initialized, but 'cx', 'cy', and 1 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|466|3|15|All final variables must be initialized, but 'clipPathUnits' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|548|3|14|All final variables must be initialized, but 'cx', 'cy', and 2 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|56|3|8|All final variables must be initialized, but 'href' and 'target' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|582|3|14|All final variables must be initialized, but 'height', 'in1', and 6 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|643|3|20|All final variables must be initialized, but 'height', 'in1', and 6 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|702|3|26|All final variables must be initialized, but 'height', 'in1', and 4 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|740|3|18|All final variables must be initialized, but 'height', 'in1', and 10 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|806|3|23|All final variables must be initialized, but 'bias', 'divisor', and 15 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|881|3|24|All final variables must be initialized, but 'diffuseConstant', 'height', and 8 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|934|3|24|All final variables must be initialized, but 'height', 'in1', and 8 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|996|3|21|All final variables must be initialized, but 'azimuth' and 'elevation' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED|lib/_internal/js_runtime/lib/native_typed_data.dart|31|13|13|The final variable 'lengthInBytes' must be initialized.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED|lib/_internal/js_runtime/lib/native_typed_data.dart|320|20|6|The final variable 'buffer' must be initialized.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED|lib/_internal/js_runtime/lib/native_typed_data.dart|324|13|13|The final variable 'lengthInBytes' must be initialized.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED|lib/_internal/js_runtime/lib/native_typed_data.dart|328|13|13|The final variable 'offsetInBytes' must be initialized.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED|lib/_internal/js_runtime/lib/native_typed_data.dart|333|13|18|The final variable 'elementSizeInBytes' must be initialized.
diff --git a/pkg/dev_compiler/tool/dart2js_server_nnbd_sdk_error_golden.txt b/pkg/dev_compiler/tool/dart2js_server_nnbd_sdk_error_golden.txt
deleted file mode 100644
index c4026f3..0000000
--- a/pkg/dev_compiler/tool/dart2js_server_nnbd_sdk_error_golden.txt
+++ /dev/null
@@ -1,21 +0,0 @@
-ERROR|COMPILE_TIME_ERROR|INCONSISTENT_INHERITANCE|lib/_internal/js_runtime/lib/interceptors.dart|1655|7|5|Superinterfaces don't have a valid override for '&': int.& (&), JSNumber.& (&).
-ERROR|COMPILE_TIME_ERROR|INCONSISTENT_INHERITANCE|lib/_internal/js_runtime/lib/interceptors.dart|1655|7|5|Superinterfaces don't have a valid override for '<<': int.<< (<<), JSNumber.<< (<<).
-ERROR|COMPILE_TIME_ERROR|INCONSISTENT_INHERITANCE|lib/_internal/js_runtime/lib/interceptors.dart|1655|7|5|Superinterfaces don't have a valid override for '>>': int.>> (>>), JSNumber.>> (>>).
-ERROR|COMPILE_TIME_ERROR|INCONSISTENT_INHERITANCE|lib/_internal/js_runtime/lib/interceptors.dart|1655|7|5|Superinterfaces don't have a valid override for '\|': int.\| (\|), JSNumber.\| (\|).
-ERROR|COMPILE_TIME_ERROR|INCONSISTENT_INHERITANCE|lib/_internal/js_runtime/lib/interceptors.dart|1655|7|5|Superinterfaces don't have a valid override for '^': int.^ (^), JSNumber.^ (^).
-ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/_internal/js_runtime/lib/interceptors.dart|1153|7|14|'JSMutableIndexable.[]=' ('void Function(int, dynamic)') isn't a valid override of 'JSArray.[]=' ('void Function(int, E)').
-ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/_internal/js_runtime/lib/interceptors.dart|1155|7|12|'JSMutableIndexable.[]=' ('void Function(int, dynamic)') isn't a valid override of 'JSArray.[]=' ('void Function(int, E)').
-ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/_internal/js_runtime/lib/interceptors.dart|1157|7|17|'JSMutableIndexable.[]=' ('void Function(int, dynamic)') isn't a valid override of 'JSArray.[]=' ('void Function(int, E)').
-ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/_internal/js_runtime/lib/native_typed_data.dart|708|17|3|'NativeTypedArrayOfDouble.[]=' ('void Function(int, double)') isn't a valid override of 'JSMutableIndexable.[]=' ('void Function(int, dynamic)').
-ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/_internal/js_runtime/lib/native_typed_data.dart|729|17|3|'NativeTypedArrayOfInt.[]=' ('void Function(int, int)') isn't a valid override of 'JSMutableIndexable.[]=' ('void Function(int, dynamic)').
-ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/js/js.dart|351|17|3|'JsArray.[]=' ('void Function(dynamic, E)') isn't a valid override of 'JsObject.[]=' ('void Function(dynamic, dynamic)').
-ERROR|STATIC_TYPE_WARNING|UNDEFINED_OPERATOR|lib/_internal/js_runtime/lib/interceptors.dart|1672|28|1|The operator '&' isn't defined for the class 'JSInt'.
-ERROR|STATIC_TYPE_WARNING|UNDEFINED_OPERATOR|lib/_internal/js_runtime/lib/interceptors.dart|1674|27|1|The operator '&' isn't defined for the class 'JSInt'.
-ERROR|STATIC_TYPE_WARNING|UNDEFINED_OPERATOR|lib/_internal/js_runtime/lib/interceptors.dart|1677|17|1|The operator '&' isn't defined for the class 'JSInt'.
-ERROR|STATIC_TYPE_WARNING|UNDEFINED_OPERATOR|lib/_internal/js_runtime/lib/interceptors.dart|1682|18|1|The operator '&' isn't defined for the class 'JSInt'.
-ERROR|STATIC_TYPE_WARNING|UNDEFINED_OPERATOR|lib/_internal/js_runtime/lib/interceptors.dart|1682|44|1|The operator '&' isn't defined for the class 'JSInt'.
-ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED|lib/_internal/js_runtime/lib/native_typed_data.dart|31|13|13|The final variable 'lengthInBytes' must be initialized.
-ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED|lib/_internal/js_runtime/lib/native_typed_data.dart|320|20|6|The final variable 'buffer' must be initialized.
-ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED|lib/_internal/js_runtime/lib/native_typed_data.dart|324|13|13|The final variable 'lengthInBytes' must be initialized.
-ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED|lib/_internal/js_runtime/lib/native_typed_data.dart|328|13|13|The final variable 'offsetInBytes' must be initialized.
-ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED|lib/_internal/js_runtime/lib/native_typed_data.dart|333|13|18|The final variable 'elementSizeInBytes' must be initialized.
diff --git a/pkg/dev_compiler/tool/dartdevc_nnbd_sdk_error_golden.txt b/pkg/dev_compiler/tool/dartdevc_nnbd_sdk_error_golden.txt
index 8b13789..7ac9295 100644
--- a/pkg/dev_compiler/tool/dartdevc_nnbd_sdk_error_golden.txt
+++ b/pkg/dev_compiler/tool/dartdevc_nnbd_sdk_error_golden.txt
@@ -1 +1,387 @@
-
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|10434|18|18|'DocumentFragment._firstElementChild' ('Element? Function()') isn't a valid override of 'ParentNode._firstElementChild' ('Element Function()').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|10437|18|17|'DocumentFragment._lastElementChild' ('Element? Function()') isn't a valid override of 'ParentNode._lastElementChild' ('Element Function()').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|14819|18|18|'Element._firstElementChild' ('Element? Function()') isn't a valid override of 'ParentNode._firstElementChild' ('Element Function()').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|14822|18|17|'Element._lastElementChild' ('Element? Function()') isn't a valid override of 'ParentNode._lastElementChild' ('Element Function()').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|17761|12|16|'HtmlDocument.registerElement2' ('Function Function(String, [Map<dynamic, dynamic>])') isn't a valid override of 'Document.registerElement2' ('Function Function(String, [Map<dynamic, dynamic>?])').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|19243|15|5|'InputElement.files' ('List<File>? Function()') isn't a valid override of 'FileUploadInputElement.files' ('List<File> Function()').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|19361|11|18|'InputElement.selectionDirection' ('String? Function()') isn't a valid override of 'TextInputElementBase.selectionDirection' ('String Function()').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|19363|8|12|'InputElement.selectionEnd' ('int? Function()') isn't a valid override of 'TextInputElementBase.selectionEnd' ('int Function()').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|19365|8|14|'InputElement.selectionStart' ('int? Function()') isn't a valid override of 'TextInputElementBase.selectionStart' ('int Function()').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|33119|19|6|'Window.opener' ('WindowBase? Function()') isn't a valid override of 'WindowBase.opener' ('WindowBase Function()').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|33191|19|6|'Window.parent' ('WindowBase? Function()') isn't a valid override of 'WindowBase.parent' ('WindowBase Function()').
+ERROR|COMPILE_TIME_ERROR|INVALID_OVERRIDE|lib/html/dart2js/html_dart2js.dart|33378|19|3|'Window.top' ('WindowBase? Function()') isn't a valid override of 'WindowBase.top' ('WindowBase Function()').
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10275|15|10|The parameter 'extendsTag' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10281|49|13|The parameter 'typeExtension' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10298|15|13|The parameter 'typeExtension' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10305|16|10|The parameter 'whatToShow' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10305|39|6|The parameter 'filter' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10310|16|10|The parameter 'whatToShow' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10310|39|6|The parameter 'filter' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10336|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10336|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10342|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10342|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10395|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10395|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10414|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|10414|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|1179|32|3|The parameter 'src' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|12604|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|12604|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|12653|43|13|The parameter 'typeExtention' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|13055|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|13055|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|13208|40|9|The parameter 'alignment' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|13303|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|13303|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|13558|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|13558|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|13693|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|13693|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|15730|13|10|The parameter 'useCapture' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|15740|13|10|The parameter 'useCapture' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|1586|40|4|The parameter 'type' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|1586|53|7|The parameter 'endings' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|17389|14|6|The parameter 'oldUrl' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|17390|14|6|The parameter 'newUrl' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|17761|46|7|The parameter 'options' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|17767|62|10|The parameter 'extendsTag' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|17811|60|10|The parameter 'extendsTag' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18045|13|15|The parameter 'withCredentials' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18046|14|12|The parameter 'responseType' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18047|27|14|The parameter 'requestHeaders' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18048|12|10|The parameter 'onProgress' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18126|15|6|The parameter 'method' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18127|12|15|The parameter 'withCredentials' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18128|14|12|The parameter 'responseType' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18129|14|8|The parameter 'mimeType' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18130|27|14|The parameter 'requestHeaders' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18132|12|10|The parameter 'onProgress' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18236|15|6|The parameter 'method' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|18236|30|8|The parameter 'sendData' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|20074|15|4|The parameter 'view' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|20077|11|8|The parameter 'location' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|20078|11|11|The parameter 'keyLocation' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|21667|14|4|The parameter 'data' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|21668|14|6|The parameter 'origin' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|21669|14|11|The parameter 'lastEventId' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|21670|14|6|The parameter 'source' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|21764|13|10|The parameter 'useCapture' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|22344|15|4|The parameter 'view' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|22357|19|13|The parameter 'relatedTarget' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|22652|13|9|The parameter 'childList' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|22653|12|10|The parameter 'attributes' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|22654|12|13|The parameter 'characterData' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|22655|12|7|The parameter 'subtree' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|22656|12|17|The parameter 'attributeOldValue' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|22657|12|21|The parameter 'characterDataOldValue' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|2269|52|7|The parameter 'quality' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|25265|66|7|The parameter 'options' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|27107|53|16|The parameter 'mediaConstraints' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|27149|61|8|The parameter 'selector' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|2845|18|10|The parameter 'sourceRect' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29465|14|3|The parameter 'key' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29466|14|8|The parameter 'oldValue' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29467|14|8|The parameter 'newValue' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29468|14|3|The parameter 'url' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29469|15|11|The parameter 'storageArea' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29835|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29835|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29919|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29919|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29982|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|29982|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|30077|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|30077|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|30306|14|4|The parameter 'view' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|30307|14|4|The parameter 'data' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|3035|49|8|The parameter 'maxWidth' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|31175|15|4|The parameter 'view' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|3213|27|4|The parameter 'data' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|3233|14|4|The parameter 'view' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|3234|14|4|The parameter 'data' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|32354|15|4|The parameter 'view' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|3235|14|6|The parameter 'locale' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|32371|19|13|The parameter 'relatedTarget' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|32606|52|7|The parameter 'options' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|34231|25|16|The parameter 'creationCallback' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|39886|35|9|The parameter 'uriPolicy' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|39899|31|9|The parameter 'uriPolicy' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|39940|34|7|The parameter 'tagName' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|39958|30|9|The parameter 'uriPolicy' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|39977|18|9|The parameter 'uriPolicy' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|39979|24|13|The parameter 'uriAttributes' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40002|18|9|The parameter 'uriPolicy' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40003|24|10|The parameter 'attributes' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40004|24|13|The parameter 'uriAttributes' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40020|18|9|The parameter 'uriPolicy' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40021|24|10|The parameter 'attributes' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40022|24|13|The parameter 'uriAttributes' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40139|25|15|The parameter 'allowedElements' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40140|24|17|The parameter 'allowedAttributes' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40141|24|20|The parameter 'allowedUriAttributes' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40667|69|7|The parameter 'options' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40882|17|10|The parameter 'useCapture' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|40895|17|10|The parameter 'useCapture' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|41038|15|4|The parameter 'view' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|41048|19|13|The parameter 'currentTarget' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|4113|63|8|The parameter 'priority' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|41377|36|9|The parameter 'uriPolicy' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|5292|63|8|The parameter 'priority' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/html/dart2js/html_dart2js.dart|8836|60|6|The parameter 'detail' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|234|21|3|The parameter 'key' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|308|61|13|The parameter 'autoIncrement' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|473|12|7|The parameter 'version' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|474|12|15|The parameter 'onUpgradeNeeded' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|475|12|9|The parameter 'onBlocked' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|500|56|9|The parameter 'onBlocked' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|604|22|5|The parameter 'range' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|604|36|9|The parameter 'direction' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|604|52|11|The parameter 'autoAdvance' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|632|22|5|The parameter 'range' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|632|36|9|The parameter 'direction' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|632|52|11|The parameter 'autoAdvance' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|847|22|5|The parameter 'range' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|847|36|9|The parameter 'direction' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|847|52|11|The parameter 'autoAdvance' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|868|49|6|The parameter 'unique' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/indexed_db/dart2js/indexed_db_dart2js.dart|868|62|10|The parameter 'multiEntry' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/svg/dart2js/svg_dart2js.dart|3109|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/svg/dart2js/svg_dart2js.dart|3109|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/svg/dart2js/svg_dart2js.dart|3155|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/svg/dart2js/svg_dart2js.dart|3155|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/svg/dart2js/svg_dart2js.dart|3184|22|9|The parameter 'validator' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|MISSING_DEFAULT_VALUE_FOR_PARAMETER|lib/svg/dart2js/svg_dart2js.dart|3184|51|13|The parameter 'treeSanitizer' can't have a value of 'null' because of its type, so it must either be a required parameter or have a default value.
+ERROR|COMPILE_TIME_ERROR|NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE|lib/html/dart2js/html_dart2js.dart|16895|18|7|The non-nullable local variable 'watchId' must be assigned before it can be used.
+ERROR|COMPILE_TIME_ERROR|NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE|lib/html/dart2js/html_dart2js.dart|16897|13|10|The non-nullable local variable 'controller' must be assigned before it can be used.
+ERROR|COMPILE_TIME_ERROR|NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE|lib/html/dart2js/html_dart2js.dart|16899|13|10|The non-nullable local variable 'controller' must be assigned before it can be used.
+ERROR|COMPILE_TIME_ERROR|NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE|lib/html/dart2js/html_dart2js.dart|16903|18|7|The non-nullable local variable 'watchId' must be assigned before it can be used.
+ERROR|COMPILE_TIME_ERROR|NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE|lib/html/dart2js/html_dart2js.dart|16904|23|7|The non-nullable local variable 'watchId' must be assigned before it can be used.
+ERROR|COMPILE_TIME_ERROR|NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE|lib/html/dart2js/html_dart2js.dart|40689|60|4|The non-nullable local variable 'type' must be assigned before it can be used.
+ERROR|COMPILE_TIME_ERROR|NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE|lib/html/dart2js/html_dart2js.dart|40691|29|4|The non-nullable local variable 'type' must be assigned before it can be used.
+ERROR|COMPILE_TIME_ERROR|NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE|lib/html/dart2js/html_dart2js.dart|40696|58|4|The non-nullable local variable 'type' must be assigned before it can be used.
+ERROR|COMPILE_TIME_ERROR|NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE|lib/html/dart2js/html_dart2js.dart|40698|31|4|The non-nullable local variable 'type' must be assigned before it can be used.
+ERROR|COMPILE_TIME_ERROR|NOT_ASSIGNED_POTENTIALLY_NON_NULLABLE_LOCAL_VARIABLE|lib/html/dart2js/html_dart2js.dart|40707|29|4|The non-nullable local variable 'type' must be assigned before it can be used.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|115|3|11|Non-nullable instance field 'nonce' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|12627|3|7|Non-nullable instance field '_defaultSanitizer' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|12627|3|7|Non-nullable instance field '_defaultValidator' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|12627|3|7|Non-nullable instance field '_parseDocument' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|12627|3|7|Non-nullable instance field '_parseRange' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|12627|3|7|Non-nullable instance field 'innerText' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|34280|3|18|Non-nullable instance field '_returnValue' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|36952|3|19|Non-nullable instance field '_elementList' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|37563|3|9|Non-nullable instance field '_unit' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|37563|3|9|Non-nullable instance field '_value' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|37923|3|22|Non-nullable instance field '_streamController' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|37923|3|22|Non-nullable instance field '_type' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|37977|3|11|Non-nullable instance field '_controller' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|39520|3|21|Non-nullable instance field '_stream' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|40430|3|21|Non-nullable instance field '_current' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|40456|3|25|Non-nullable instance field '_current' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|41028|3|8|Non-nullable instance field '_currentTarget' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|41028|3|8|Non-nullable instance field '_parent' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|41028|3|8|Non-nullable instance field '_shadowAltKey' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|41028|3|8|Non-nullable instance field '_shadowCharCode' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|41028|3|8|Non-nullable instance field '_shadowKeyCode' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|41218|3|13|Non-nullable instance field '_selector' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|5283|3|23|Non-nullable instance field '_elementCssStyleDeclarationSetIterable' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19472|8|9|Non-nullable instance field 'autofocus' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19474|8|8|Non-nullable instance field 'disabled' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19476|8|11|Non-nullable instance field 'incremental' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19478|8|13|Non-nullable instance field 'indeterminate' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19482|10|4|Non-nullable instance field 'name' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19488|10|5|Non-nullable instance field 'value' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19508|10|12|Non-nullable instance field 'autocomplete' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19510|7|9|Non-nullable instance field 'maxLength' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19512|10|7|Non-nullable instance field 'pattern' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19514|10|11|Non-nullable instance field 'placeholder' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19516|8|8|Non-nullable instance field 'readOnly' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19518|8|8|Non-nullable instance field 'required' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19520|7|4|Non-nullable instance field 'size' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19524|10|18|Non-nullable instance field 'selectionDirection' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19526|7|12|Non-nullable instance field 'selectionEnd' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19528|7|14|Non-nullable instance field 'selectionStart' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19661|10|3|Non-nullable instance field 'max' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19663|10|3|Non-nullable instance field 'min' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19665|10|4|Non-nullable instance field 'step' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD|lib/html/dart2js/html_dart2js.dart|19667|7|13|Non-nullable instance field 'valueAsNumber' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_VARIABLE|lib/html/dart2js/html_dart2js.dart|13532|23|14|The non-nullable variable '_parseDocument' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_VARIABLE|lib/html/dart2js/html_dart2js.dart|13533|16|11|The non-nullable variable '_parseRange' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_VARIABLE|lib/html/dart2js/html_dart2js.dart|13534|31|17|The non-nullable variable '_defaultValidator' must be initialized.
+ERROR|COMPILE_TIME_ERROR|NOT_INITIALIZED_NON_NULLABLE_VARIABLE|lib/html/dart2js/html_dart2js.dart|13535|35|17|The non-nullable variable '_defaultSanitizer' must be initialized.
+ERROR|STATIC_TYPE_WARNING|FOR_IN_OF_INVALID_ELEMENT_TYPE|lib/html/dart2js/html_dart2js.dart|37442|26|8|The type 'Iterable<Object>' used in the 'for' loop must implement Iterable with a type argument that can be assigned to 'String'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|11762|22|27|A value of type 'Element?' can't be assigned to a variable of type 'Element'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|11768|22|26|A value of type 'Element?' can't be assigned to a variable of type 'Element'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|12817|25|10|A value of type 'String?' can't be assigned to a variable of type 'String'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|12991|19|10|A value of type 'String?' can't be assigned to a variable of type 'String'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|13383|14|11|A value of type 'Element?' can't be assigned to a variable of type 'Element'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|13590|29|36|A value of type 'Element' can't be assigned to a variable of type 'BodyElement'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|15453|29|18|A value of type 'EventTarget?' can't be assigned to a variable of type 'Element'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|15454|22|11|A value of type 'EventTarget?' can't be assigned to a variable of type 'Element'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|15458|16|13|A value of type 'Element?' can't be assigned to a variable of type 'Element'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|19154|22|31|A value of type 'Element' can't be assigned to a variable of type 'InputElement'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|20087|23|38|A value of type 'Event' can't be assigned to a variable of type 'KeyboardEvent'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|21690|26|37|A value of type 'Event' can't be assigned to a variable of type 'MessageEvent'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|22361|24|35|A value of type 'Event' can't be assigned to a variable of type 'MouseEvent'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|22543|24|11|A value of type 'EventTarget?' can't be assigned to a variable of type 'Element'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|23270|18|16|A value of type 'Node?' can't be assigned to a variable of type 'Node'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|23272|24|14|A value of type 'Node?' can't be assigned to a variable of type 'Node'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|23367|27|15|A value of type 'Node?' can't be assigned to a variable of type 'Node'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|23377|27|15|A value of type 'Node?' can't be assigned to a variable of type 'Node'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|23419|20|9|A value of type 'String?' can't be assigned to a variable of type 'String'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|23863|20|4|A value of type 'Null' can't be assigned to a variable of type 'String'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|23864|20|4|A value of type 'Null' can't be assigned to a variable of type 'String'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|23865|20|4|A value of type 'Null' can't be assigned to a variable of type 'String'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|23866|19|4|A value of type 'Null' can't be assigned to a variable of type 'String'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|23867|20|4|A value of type 'Null' can't be assigned to a variable of type 'String'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|29470|22|37|A value of type 'Event' can't be assigned to a variable of type 'StorageEvent'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|30311|19|34|A value of type 'Event' can't be assigned to a variable of type 'TextEvent'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|31182|17|32|A value of type 'Event' can't be assigned to a variable of type 'UIEvent'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|3239|26|41|A value of type 'Event' can't be assigned to a variable of type 'CompositionEvent'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|36328|20|13|A value of type 'Node' can't be assigned to a variable of type '_Attr'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|36341|20|13|A value of type 'Node' can't be assigned to a variable of type '_Attr'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|37843|15|4|A value of type 'Null' can't be assigned to a variable of type 'EventTarget'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|37844|15|4|A value of type 'Null' can't be assigned to a variable of type 'dynamic Function(Event)'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|37856|15|95|A value of type 'void Function(Event)?' can't be assigned to a variable of type 'dynamic Function(Event)'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|39773|26|38|A value of type 'int?' can't be assigned to a variable of type 'int'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|39782|30|4|A value of type 'Null' can't be assigned to a variable of type 'KeyboardEvent'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|40442|16|4|A value of type 'Null' can't be assigned to a variable of type 'T'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|40467|16|4|A value of type 'Null' can't be assigned to a variable of type 'T'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|40844|28|4|A value of type 'Null' can't be assigned to a variable of type 'List<dynamic>'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|41033|22|21|A value of type 'EventTarget?' can't be assigned to a variable of type 'EventTarget'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|41268|29|18|A value of type 'EventTarget' can't be assigned to a variable of type 'Element'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|41269|22|11|A value of type 'EventTarget' can't be assigned to a variable of type 'Element'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|41273|16|13|A value of type 'Element?' can't be assigned to a variable of type 'Element'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/html/dart2js/html_dart2js.dart|8837|27|36|A value of type 'Event' can't be assigned to a variable of type 'CustomEvent'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/svg/dart2js/svg_dart2js.dart|3138|31|16|A value of type 'Node' can't be assigned to a variable of type 'SvgElement'.
+ERROR|STATIC_TYPE_WARNING|INVALID_ASSIGNMENT|lib/svg/dart2js/svg_dart2js.dart|3145|31|16|A value of type 'Node' can't be assigned to a variable of type 'SvgElement'.
+ERROR|STATIC_TYPE_WARNING|NON_BOOL_CONDITION|lib/html/dart2js/html_dart2js.dart|15464|7|36|Conditions must have a static type of 'bool'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE_FROM_CLOSURE|lib/html/dart2js/html_dart2js.dart|30825|26|4|The return type 'Null' isn't a 'TouchList', as required by the closure's context.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE_FROM_CLOSURE|lib/svg/dart2js/svg_dart2js.dart|3557|12|2|The return type 'SvgElement' isn't a 'SvgSvgElement', as required by the closure's context.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|10582|12|9|A value of type 'Object?' can't be returned from function 'name' because it has a return type of 'String'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|11395|12|4|A value of type 'Null' can't be returned from method 'intersection' because it has a return type of 'Rectangle<num>'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|11643|12|21|A value of type 'Node' can't be returned from method '[]' because it has a return type of 'Element'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|12174|31|16|A value of type 'Node' can't be returned from method '[]' because it has a return type of 'E'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|12192|18|15|A value of type 'Node' can't be returned from function 'first' because it has a return type of 'E'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|12194|17|14|A value of type 'Node' can't be returned from function 'last' because it has a return type of 'E'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|12196|19|16|A value of type 'Node' can't be returned from function 'single' because it has a return type of 'E'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|12608|12|48|A value of type 'Node' can't be returned from function 'html' because it has a return type of 'Element'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|13180|30|13|A value of type 'String?' can't be returned from function 'namespaceUri' because it has a return type of 'String'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|16127|12|3|A value of type 'Object?' can't be returned from function 'result' because it has a return type of 'Object'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|17681|27|5|A value of type 'HeadElement?' can't be returned from function 'head' because it has a return type of 'HeadElement'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|17685|40|23|A value of type 'String?' can't be returned from function 'preferredStylesheetSet' because it has a return type of 'String'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|17689|39|22|A value of type 'String?' can't be returned from function 'selectedStylesheetSet' because it has a return type of 'String'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|2225|12|7|A value of type 'Object' can't be returned from method 'getContext3d' because it has a return type of 'RenderingContext'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|29386|12|9|A value of type 'String?' can't be returned from method 'putIfAbsent' because it has a return type of 'String'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|29828|12|5|A value of type 'Element' can't be returned from method '_createTBody' because it has a return type of 'TableSectionElement'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|29916|45|18|A value of type 'HtmlElement' can't be returned from method 'insertCell' because it has a return type of 'TableCellElement'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|29979|43|17|A value of type 'HtmlElement' can't be returned from method 'insertRow' because it has a return type of 'TableRowElement'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|35143|12|4|A value of type 'Null' can't be returned from method 'intersection' because it has a return type of 'Rectangle<num>'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|36307|12|9|A value of type 'String?' can't be returned from method 'putIfAbsent' because it has a return type of 'String'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|37188|12|4|A value of type 'Null' can't be returned from method 'intersection' because it has a return type of 'Rectangle<num>'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|37839|27|4|A value of type 'Null' can't be returned from method 'cancel' because it has a return type of 'Future<dynamic>'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|37845|12|4|A value of type 'Null' can't be returned from method 'cancel' because it has a return type of 'Future<dynamic>'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|40338|31|12|A value of type 'Node' can't be returned from method '[]' because it has a return type of 'E'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|40360|28|21|A value of type 'Node' can't be returned from method 'removeAt' because it has a return type of 'E'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|40485|7|68|A value of type 'MemoryInfo?' can't be returned from function 'memory' because it has a return type of 'MemoryInfo'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|40565|27|4|A value of type 'Null' can't be returned from function '_convertNativeToDart_Window' because it has a return type of 'WindowBase'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|40571|12|4|A value of type 'Null' can't be returned from function '_convertNativeToDart_EventTarget' because it has a return type of 'EventTarget'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|40582|12|4|A value of type 'Null' can't be returned from function '_convertNativeToDart_EventTarget' because it has a return type of 'EventTarget'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|41149|22|12|A value of type 'WindowBase?' can't be returned from function 'view' because it has a return type of 'Window'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|41226|36|21|A value of type 'EventTarget?' can't be returned from function 'currentTarget' because it has a return type of 'EventTarget'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|41234|29|14|A value of type 'EventTarget?' can't be returned from function 'target' because it has a return type of 'EventTarget'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|41236|27|17|A value of type 'num' can't be returned from function 'timeStamp' because it has a return type of 'double'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|41288|26|12|A value of type 'List<EventTarget>' can't be returned from function 'path' because it has a return type of 'List<Node>'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|41301|32|4|A value of type 'Null' can't be returned from function '_wrapZone' because it has a return type of 'void Function(T)'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/html/dart2js/html_dart2js.dart|41308|32|4|A value of type 'Null' can't be returned from function '_wrapBinaryZone' because it has a return type of 'void Function(T1, T2)'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/svg/dart2js/svg_dart2js.dart|3107|7|59|A value of type 'Element' can't be returned from function 'tag' because it has a return type of 'SvgElement'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/svg/dart2js/svg_dart2js.dart|33|12|4|A value of type 'Element' can't be returned from method 'createSvgElement_tag' because it has a return type of 'SvgElement'.
+ERROR|STATIC_TYPE_WARNING|RETURN_OF_INVALID_TYPE|lib/web_audio/dart2js/web_audio_dart2js.dart|249|14|59|A value of type 'Future<dynamic>' can't be returned from method 'decodeAudioData' because it has a return type of 'Future<AudioBuffer>'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/_internal/js_dev_runtime/private/interceptors.dart|689|52|1|The argument type 'Object?' can't be assigned to the parameter type 'Comparable<dynamic>'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/_internal/js_dev_runtime/private/interceptors.dart|689|55|1|The argument type 'Object?' can't be assigned to the parameter type 'Comparable<dynamic>'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|13066|60|4|The argument type 'Null' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|13498|40|24|The argument type 'Element?' can't be assigned to the parameter type 'Element'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|16933|48|13|The argument type 'void Function(PositionError)?' can't be assigned to the parameter type 'void Function(PositionError)'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|16960|50|13|The argument type 'void Function(PositionError)?' can't be assigned to the parameter type 'void Function(PositionError)'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|18015|13|32|The argument type 'bool?' can't be assigned to the parameter type 'bool'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|18015|47|22|The argument type 'void Function(ProgressEvent)?' can't be assigned to the parameter type 'void Function(ProgressEvent)'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|18254|30|8|The argument type 'Object?' can't be assigned to the parameter type 'FutureOr<String>?'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|22537|24|1|The argument type 'Object?' can't be assigned to the parameter type 'num'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|22537|27|1|The argument type 'Object?' can't be assigned to the parameter type 'num'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|23208|24|26|The argument type 'Node?' can't be assigned to the parameter type 'Node'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|23400|27|26|The argument type 'Node?' can't be assigned to the parameter type 'Node'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|23411|20|10|The argument type 'Node?' can't be assigned to the parameter type 'Node'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|23728|59|4|The argument type 'Null' can't be assigned to the parameter type 'NodeFilter'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|26570|37|7|The argument type 'num' can't be assigned to the parameter type 'int'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|26570|46|7|The argument type 'num' can't be assigned to the parameter type 'int'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|29376|45|3|The argument type 'Object?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|29391|17|3|The argument type 'Object?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|29402|14|9|The argument type 'String?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|31084|57|4|The argument type 'Null' can't be assigned to the parameter type 'NodeFilter'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|34222|13|3|The argument type 'num' can't be assigned to the parameter type 'int'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|34222|18|3|The argument type 'num' can't be assigned to the parameter type 'int'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|36319|14|5|The argument type 'String?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|36374|35|3|The argument type 'Object?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|36378|34|3|The argument type 'Object?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|36422|49|3|The argument type 'Object?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|36426|48|3|The argument type 'Object?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|36485|66|3|The argument type 'Object?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|36487|57|3|The argument type 'Object?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|36496|59|3|The argument type 'Object?' can't be assigned to the parameter type 'String'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|37348|32|5|The argument type 'Object?' can't be assigned to the parameter type 'Object'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|37368|26|8|The argument type 'Iterable<Object?>' can't be assigned to the parameter type 'Iterable<Object>'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|37736|40|6|The argument type 'void Function(T)?' can't be assigned to the parameter type 'void Function(T)'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|39946|34|4|The argument type 'Null' can't be assigned to the parameter type 'UriPolicy'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|39990|36|5|The argument type 'Iterable<String>?' can't be assigned to the parameter type 'Iterable<String>'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|39990|43|8|The argument type 'Iterable<String>?' can't be assigned to the parameter type 'Iterable<String>'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|40016|40|5|The argument type 'Iterable<String>?' can't be assigned to the parameter type 'Iterable<String>'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|40016|47|8|The argument type 'Iterable<String>?' can't be assigned to the parameter type 'Iterable<String>'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|40112|37|4|The argument type 'Null' can't be assigned to the parameter type 'UriPolicy'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|40233|15|4|The argument type 'Null' can't be assigned to the parameter type 'UriPolicy'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|40350|44|1|The argument type 'Node' can't be assigned to the parameter type 'E'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|40350|47|1|The argument type 'Node' can't be assigned to the parameter type 'E'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|40353|65|7|The argument type 'Object' can't be assigned to the parameter type 'Node'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|40356|25|7|The argument type 'Object' can't be assigned to the parameter type 'Node'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|41540|16|4|The argument type 'Null' can't be assigned to the parameter type 'Node'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|9520|41|15|The argument type 'void Function(Entry)?' can't be assigned to the parameter type 'void Function(Entry)'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|9564|36|15|The argument type 'void Function(Entry)?' can't be assigned to the parameter type 'void Function(Entry)'.
+ERROR|STATIC_WARNING|ARGUMENT_TYPE_NOT_ASSIGNABLE|lib/svg/dart2js/svg_dart2js.dart|3172|26|15|The argument type 'Node?' can't be assigned to the parameter type 'Node'.
+ERROR|STATIC_WARNING|FIELD_INITIALIZER_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|11629|26|17|The initializer type 'List<Node>' can't be assigned to the field type 'HtmlCollection'.
+ERROR|STATIC_WARNING|FIELD_INITIALIZER_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|37832|19|95|The initializer type 'void Function(Event)?' can't be assigned to the field type 'dynamic Function(Event)'.
+ERROR|STATIC_WARNING|FIELD_INITIALIZER_NOT_ASSIGNABLE|lib/html/dart2js/html_dart2js.dart|39513|19|4|The initializer type 'Null' can't be assigned to the field type 'EventTarget'.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|12627|3|7|All final variables must be initialized, but '_firstElementChild', '_lastElementChild', and 8 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|15934|3|15|All final variables must be initialized, but 'form' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|18791|3|13|All final variables must be initialized, but '_get_contentWindow' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|19173|3|12|All final variables must be initialized, but '_get_valueAsDate', 'form', and 1 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|1919|3|13|All final variables must be initialized, but 'form' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|20284|3|12|All final variables must be initialized, but 'control' and 'form' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|20317|3|13|All final variables must be initialized, but 'form' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|20367|3|11|All final variables must be initialized, but 'import' and 'sheet' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|20686|3|12|All final variables must be initialized, but 'error' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|23341|3|4|All final variables must be initialized, but 'childNodes', 'firstChild', and 7 others are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|24089|3|13|All final variables must be initialized, but '_get_contentWindow' and 'form' are not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|24597|3|13|All final variables must be initialized, but 'form' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|24668|3|13|All final variables must be initialized, but 'form' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|27859|3|13|All final variables must be initialized, but 'form' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|29564|3|12|All final variables must be initialized, but 'sheet' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|30135|3|15|All final variables must be initialized, but 'form' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/html/dart2js/html_dart2js.dart|41028|3|8|All final variables must be initialized, but 'sourceCapabilities' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3043|3|12|All final variables must be initialized, but 'sheet' is not.
+ERROR|STATIC_WARNING|FINAL_NOT_INITIALIZED_CONSTRUCTOR|lib/svg/dart2js/svg_dart2js.dart|3392|3|10|All final variables must be initialized, but 'ownerSvgElement' and 'viewportElement' are not.
+ERROR|STATIC_WARNING|GETTER_NOT_SUBTYPE_SETTER_TYPES|lib/html/dart2js/html_dart2js.dart|33119|19|6|The return type of getter 'opener' is 'WindowBase?' which isn't a subtype of the type 'Window' of its setter 'opener'.
+ERROR|STATIC_WARNING|UNCHECKED_USE_OF_NULLABLE_VALUE|lib/html/dart2js/html_dart2js.dart|13342|9|15|The expression is nullable and must be null-checked before it can be used.
+ERROR|STATIC_WARNING|UNCHECKED_USE_OF_NULLABLE_VALUE|lib/html/dart2js/html_dart2js.dart|13352|9|15|The expression is nullable and must be null-checked before it can be used.
+ERROR|STATIC_WARNING|UNCHECKED_USE_OF_NULLABLE_VALUE|lib/html/dart2js/html_dart2js.dart|23368|7|10|The expression is nullable and must be null-checked before it can be used.
+ERROR|STATIC_WARNING|UNCHECKED_USE_OF_NULLABLE_VALUE|lib/html/dart2js/html_dart2js.dart|34260|9|24|The expression is nullable and must be null-checked before it can be used.
+ERROR|STATIC_WARNING|UNCHECKED_USE_OF_NULLABLE_VALUE|lib/html/dart2js/html_dart2js.dart|34274|9|24|The expression is nullable and must be null-checked before it can be used.
+ERROR|STATIC_WARNING|UNCHECKED_USE_OF_NULLABLE_VALUE|lib/html/dart2js/html_dart2js.dart|40350|36|7|The expression is nullable and must be null-checked before it can be used.
+ERROR|STATIC_WARNING|UNCHECKED_USE_OF_NULLABLE_VALUE|lib/svg/dart2js/svg_dart2js.dart|3116|26|14|The expression is nullable and must be null-checked before it can be used.
+WARNING|STATIC_WARNING|INVALID_OVERRIDE_DIFFERENT_DEFAULT_VALUES_NAMED|lib/html/html_common/html_common_dart2js.dart|224|24|19|Parameters can't override default values, this method overrides 'Iterable.toList' where 'growable' has a different value.
+WARNING|STATIC_WARNING|INVALID_OVERRIDE_DIFFERENT_DEFAULT_VALUES_NAMED|lib/html/html_common/html_common_dart2js.dart|224|24|19|Parameters can't override default values, this method overrides 'SetMixin.toList' where 'growable' has a different value.
+WARNING|STATIC_WARNING|INVALID_OVERRIDE_DIFFERENT_DEFAULT_VALUES_POSITIONAL|lib/html/html_common/html_common_dart2js.dart|90|16|21|Parameters can't override default values, this method overrides 'Iterable.join' where this positional parameter has a different value.
+WARNING|STATIC_WARNING|INVALID_OVERRIDE_DIFFERENT_DEFAULT_VALUES_POSITIONAL|lib/html/html_common/html_common_dart2js.dart|90|16|21|Parameters can't override default values, this method overrides 'SetMixin.join' where this positional parameter has a different value.
+WARNING|STATIC_WARNING|INVALID_OVERRIDE_DIFFERENT_DEFAULT_VALUES_POSITIONAL|lib/html/html_common/html_common_dart2js.dart|962|8|17|Parameters can't override default values, this method overrides 'List.setRange' where this positional parameter has a different value.
+WARNING|STATIC_WARNING|INVALID_OVERRIDE_DIFFERENT_DEFAULT_VALUES_POSITIONAL|lib/html/html_common/html_common_dart2js.dart|962|8|17|Parameters can't override default values, this method overrides 'ListMixin.setRange' where this positional parameter has a different value.
+WARNING|STATIC_WARNING|UNNECESSARY_NULL_AWARE_CALL|lib/html/dart2js/html_dart2js.dart|39984|9|2|The target expression can't be null, and so '?.' isn't necessary.
+WARNING|STATIC_WARNING|UNNECESSARY_NULL_AWARE_CALL|lib/html/dart2js/html_dart2js.dart|40008|9|2|The target expression can't be null, and so '?.' isn't necessary.
+WARNING|STATIC_WARNING|UNNECESSARY_NULL_AWARE_CALL|lib/html/dart2js/html_dart2js.dart|40010|9|2|The target expression can't be null, and so '?.' isn't necessary.
diff --git a/pkg/dev_compiler/tool/patch_sdk.dart b/pkg/dev_compiler/tool/patch_sdk.dart
index 755de10..3dcb32b 100755
--- a/pkg/dev_compiler/tool/patch_sdk.dart
+++ b/pkg/dev_compiler/tool/patch_sdk.dart
@@ -180,7 +180,7 @@
 }
 
 /// Merge `@patch` declarations into `external` declarations.
-class PatchApplier extends GeneralizingAstVisitor {
+class PatchApplier extends GeneralizingAstVisitor<void> {
   final StringEditBuffer edits;
   final PatchFinder patch;
 
@@ -190,7 +190,7 @@
   PatchApplier(this.edits, this.patch);
 
   @override
-  visitCompilationUnit(CompilationUnit node) {
+  void visitCompilationUnit(CompilationUnit node) {
     super.visitCompilationUnit(node);
     if (_isLibrary) _mergeUnpatched(node);
   }
@@ -227,18 +227,18 @@
   }
 
   @override
-  visitPartOfDirective(PartOfDirective node) {
+  void visitPartOfDirective(PartOfDirective node) {
     _isLibrary = false;
   }
 
   @override
-  visitFunctionDeclaration(FunctionDeclaration node) {
+  void visitFunctionDeclaration(FunctionDeclaration node) {
     _maybePatch(node);
   }
 
   /// Merge patches and extensions into the class
   @override
-  visitClassDeclaration(ClassDeclaration node) {
+  void visitClassDeclaration(ClassDeclaration node) {
     node.members.forEach(_maybePatch);
 
     var mergeMembers = patch.mergeMembers[_qualifiedName(node)];
@@ -294,7 +294,7 @@
   }
 }
 
-class PatchFinder extends GeneralizingAstVisitor {
+class PatchFinder extends GeneralizingAstVisitor<void> {
   final String contents;
   final CompilationUnit unit;
 
@@ -309,12 +309,12 @@
   }
 
   @override
-  visitCompilationUnitMember(CompilationUnitMember node) {
+  void visitCompilationUnitMember(CompilationUnitMember node) {
     mergeDeclarations.add(node);
   }
 
   @override
-  visitClassDeclaration(ClassDeclaration node) {
+  void visitClassDeclaration(ClassDeclaration node) {
     if (_isPatch(node)) {
       var members = <ClassMember>[];
       for (var member in node.members) {
@@ -333,7 +333,7 @@
   }
 
   @override
-  visitFunctionDeclaration(FunctionDeclaration node) {
+  void visitFunctionDeclaration(FunctionDeclaration node) {
     if (_isPatch(node)) {
       patches[_qualifiedName(node)] = node;
     } else {
@@ -342,7 +342,7 @@
   }
 
   @override
-  visitFunctionBody(node) {} // skip method bodies
+  void visitFunctionBody(node) {} // skip method bodies
 }
 
 String _qualifiedName(Declaration node) {
diff --git a/pkg/dev_compiler/web/source_map_stack_trace.dart b/pkg/dev_compiler/web/source_map_stack_trace.dart
index 817adc0..4617b80 100644
--- a/pkg/dev_compiler/web/source_map_stack_trace.dart
+++ b/pkg/dev_compiler/web/source_map_stack_trace.dart
@@ -29,7 +29,7 @@
     if (frame.line == null) return null;
 
     // If there's no column, try using the first column of the line.
-    var column = frame.column == null ? 0 : frame.column;
+    var column = frame.column ?? 0;
 
     // Subtract 1 because stack traces use 1-indexed lines and columns and
     // source maps uses 0-indexed.
diff --git a/pkg/dev_compiler/web/stack_trace_mapper.dart b/pkg/dev_compiler/web/stack_trace_mapper.dart
index fa74c34..e10e6f3 100644
--- a/pkg/dev_compiler/web/stack_trace_mapper.dart
+++ b/pkg/dev_compiler/web/stack_trace_mapper.dart
@@ -60,8 +60,8 @@
 /// The unparsed data for the source maps must still be loaded before
 /// LazyMapping is used.
 class LazyMapping extends Mapping {
-  MappingBundle _bundle = MappingBundle();
-  SourceMapProvider _provider;
+  final MappingBundle _bundle = MappingBundle();
+  final SourceMapProvider _provider;
 
   LazyMapping(this._provider);
 
diff --git a/pkg/front_end/lib/src/base/libraries_specification.dart b/pkg/front_end/lib/src/base/libraries_specification.dart
index 9dc212a..52a18dc 100644
--- a/pkg/front_end/lib/src/base/libraries_specification.dart
+++ b/pkg/front_end/lib/src/base/libraries_specification.dart
@@ -256,6 +256,9 @@
 
   const LibraryInfo(this.name, this.uri, this.patches,
       {this.isSupported: true});
+
+  /// The import uri for the defined library.
+  Uri get importUri => Uri.parse('dart:${name}');
 }
 
 class LibrariesSpecificationException {
diff --git a/pkg/front_end/lib/src/fasta/builder/class_builder.dart b/pkg/front_end/lib/src/fasta/builder/class_builder.dart
index 42b36d0..6dd7e15 100644
--- a/pkg/front_end/lib/src/fasta/builder/class_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/class_builder.dart
@@ -210,9 +210,6 @@
   bool hasUserDefinedNoSuchMethod(
       Class klass, ClassHierarchy hierarchy, Class objectClass);
 
-  void transformProcedureToNoSuchMethodForwarder(
-      Member noSuchMethodInterface, KernelTarget target, Procedure procedure);
-
   /// Returns whether a covariant parameter was seen and more methods thus have
   /// to be checked.
   bool checkMethodOverride(Types types, Procedure declaredMember,
@@ -1006,7 +1003,6 @@
     return noSuchMethod != null && noSuchMethod.enclosingClass != objectClass;
   }
 
-  @override
   void transformProcedureToNoSuchMethodForwarder(
       Member noSuchMethodInterface, KernelTarget target, Procedure procedure) {
     String prefix =
@@ -1024,6 +1020,8 @@
     if (procedure.function.returnType is! VoidType) {
       result = new AsExpression(result, procedure.function.returnType)
         ..isTypeError = true
+        ..isForDynamic = true
+        ..isForNonNullableByDefault = library.isNonNullableByDefault
         ..fileOffset = procedure.fileOffset;
     }
     procedure.function.body = new ReturnStatement(result)
diff --git a/pkg/front_end/lib/src/fasta/builder/field_builder.dart b/pkg/front_end/lib/src/fasta/builder/field_builder.dart
index d9ea01c..571ef94 100644
--- a/pkg/front_end/lib/src/fasta/builder/field_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/field_builder.dart
@@ -375,11 +375,9 @@
     if (fieldType is ImplicitFieldType) {
       // `fieldType` may have changed if a circularity was detected when
       // [inferredType] was computed.
-      if (library.loader.target.enableNonNullable) {
-        if (!library.isNonNullableByDefault) {
-          inferredType = legacyErasure(
-              library.loader.typeInferenceEngine.coreTypes, inferredType);
-        }
+      if (!library.isNonNullableByDefault) {
+        inferredType = legacyErasure(
+            library.loader.typeInferenceEngine.coreTypes, inferredType);
       }
       fieldType = inferredType;
 
diff --git a/pkg/front_end/lib/src/fasta/builder/member_builder.dart b/pkg/front_end/lib/src/fasta/builder/member_builder.dart
index 5c024a7..5f0aff0 100644
--- a/pkg/front_end/lib/src/fasta/builder/member_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/member_builder.dart
@@ -143,6 +143,16 @@
   String get fullNameForErrors => name;
 
   @override
+  StringBuffer printOn(StringBuffer buffer) {
+    if (isClassMember) {
+      buffer.write(classBuilder.name);
+      buffer.write('.');
+    }
+    buffer.write(name);
+    return buffer;
+  }
+
+  @override
   ClassBuilder get classBuilder => parent is ClassBuilder ? parent : null;
 }
 
diff --git a/pkg/front_end/lib/src/fasta/builder/type_alias_builder.dart b/pkg/front_end/lib/src/fasta/builder/type_alias_builder.dart
index 94edb1e..28d20c0 100644
--- a/pkg/front_end/lib/src/fasta/builder/type_alias_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/type_alias_builder.dart
@@ -41,7 +41,7 @@
 class TypeAliasBuilder extends TypeDeclarationBuilderImpl {
   final TypeBuilder type;
 
-  final List<TypeVariableBuilder> typeVariables;
+  final List<TypeVariableBuilder> _typeVariables;
 
   /// The [Typedef] built by this builder.
   final Typedef typedef;
@@ -49,12 +49,12 @@
   DartType thisType;
 
   TypeAliasBuilder(List<MetadataBuilder> metadata, String name,
-      this.typeVariables, this.type, LibraryBuilder parent, int charOffset,
+      this._typeVariables, this.type, LibraryBuilder parent, int charOffset,
       {Typedef typedef, Typedef referenceFrom})
       : typedef = typedef ??
             (new Typedef(name, null,
                 typeParameters: TypeVariableBuilder.typeParametersFromBuilders(
-                    typeVariables),
+                    _typeVariables),
                 fileUri: parent.library.fileUri,
                 reference: referenceFrom?.reference)
               ..fileOffset = charOffset),
@@ -64,6 +64,11 @@
 
   LibraryBuilder get parent => super.parent;
 
+  // TODO(CFE TEAM): Some of this is a temporary workaround.
+  List<TypeVariableBuilder> get typeVariables => _typeVariables;
+  int varianceAt(int index) => typeVariables[index].parameter.variance;
+  bool get fromDill => false;
+
   Typedef build(SourceLibraryBuilder libraryBuilder) {
     typedef..type ??= buildThisType(libraryBuilder);
 
diff --git a/pkg/front_end/lib/src/fasta/builder_graph.dart b/pkg/front_end/lib/src/fasta/builder_graph.dart
index 48cb623..f917b93 100644
--- a/pkg/front_end/lib/src/fasta/builder_graph.dart
+++ b/pkg/front_end/lib/src/fasta/builder_graph.dart
@@ -18,6 +18,8 @@
 
 import 'source/source_library_builder.dart' show SourceLibraryBuilder;
 
+import 'incremental_compiler.dart' show getPartUri;
+
 class BuilderGraph implements Graph<Uri> {
   final Map<Uri, LibraryBuilder> builders;
 
@@ -63,7 +65,7 @@
 
       // Parts
       for (LibraryPart part in library.library.parts) {
-        Uri uri = library.uri.resolve(part.partUri);
+        Uri uri = getPartUri(library.uri, part);
         if (builders.containsKey(uri)) {
           yield uri;
         }
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart b/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
index 18cdf42..fa463de 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_library_builder.dart
@@ -9,6 +9,7 @@
 import 'package:kernel/ast.dart'
     show
         Class,
+        ConstantExpression,
         DartType,
         DynamicType,
         Extension,
@@ -23,12 +24,14 @@
         Procedure,
         Reference,
         StaticGet,
+        StringConstant,
         StringLiteral,
         Typedef;
 
 import '../builder/builder.dart';
 import '../builder/class_builder.dart';
 import '../builder/dynamic_type_builder.dart';
+import '../builder/extension_builder.dart';
 import '../builder/never_type_builder.dart';
 import '../builder/invalid_type_declaration_builder.dart';
 import '../builder/library_builder.dart';
@@ -90,6 +93,7 @@
   // state field.
   bool isReadyToBuild = false;
   bool isReadyToFinalizeExports = false;
+  bool suppressFinalizationErrors = false;
   bool isBuilt = false;
   bool isBuiltAndMarked = false;
 
@@ -182,8 +186,16 @@
     String name = member.name.name;
     if (name == "_exports#") {
       Field field = member;
-      StringLiteral string = field.initializer;
-      Map<dynamic, dynamic> json = jsonDecode(string.value);
+      String stringValue;
+      if (field.initializer is ConstantExpression) {
+        ConstantExpression constantExpression = field.initializer;
+        StringConstant string = constantExpression.constant;
+        stringValue = string.value;
+      } else {
+        StringLiteral string = field.initializer;
+        stringValue = string.value;
+      }
+      Map<dynamic, dynamic> json = jsonDecode(stringValue);
       unserializableExports =
           json != null ? new Map<String, String>.from(json) : null;
     } else {
@@ -200,6 +212,9 @@
     } else {
       scopeBuilder.addMember(name, declaration);
     }
+    if (declaration.isExtension) {
+      scopeBuilder.addExtension(declaration);
+    }
     if (!name.startsWith("_")) {
       if (isSetter) {
         exportScopeBuilder.addSetter(name, declaration);
@@ -250,8 +265,9 @@
     isReadyToBuild = true;
   }
 
-  void markAsReadyToFinalizeExports() {
+  void markAsReadyToFinalizeExports({bool suppressFinalizationErrors: false}) {
     isReadyToFinalizeExports = true;
+    this.suppressFinalizationErrors = suppressFinalizationErrors;
   }
 
   void finalizeExports() {
@@ -269,7 +285,9 @@
           Message message = messageText == null
               ? templateTypeNotFound.withArguments(name)
               : templateUnspecified.withArguments(messageText);
-          addProblem(message, -1, noLength, null);
+          if (!suppressFinalizationErrors) {
+            addProblem(message, -1, noLength, null);
+          }
           declaration = new InvalidTypeDeclarationBuilder(
               name, message.withoutLocation());
       }
@@ -323,9 +341,15 @@
             -1,
             fileUri);
       }
-      assert((declaration is ClassBuilder && node == declaration.cls) ||
-          (declaration is TypeAliasBuilder && node == declaration.typedef) ||
-          (declaration is MemberBuilder && node == declaration.member));
+      assert(
+          (declaration is ClassBuilder && node == declaration.cls) ||
+              (declaration is TypeAliasBuilder &&
+                  node == declaration.typedef) ||
+              (declaration is MemberBuilder && node == declaration.member) ||
+              (declaration is ExtensionBuilder &&
+                  node == declaration.extension),
+          "Unexpected declaration ${declaration} (${declaration.runtimeType}) "
+          "for node ${node} (${node.runtimeType}).");
     }
   }
 }
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_loader.dart b/pkg/front_end/lib/src/fasta/dill/dill_loader.dart
index 0e2d670..3d91dbd 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_loader.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_loader.dart
@@ -58,6 +58,24 @@
     return result;
   }
 
+  /// Append single compiled library.
+  ///
+  /// Note that as this only takes a library, no new sources is added to the
+  /// uriToSource map.
+  DillLibraryBuilder appendLibrary(Library library) {
+    // Add to list of libraries in the loader, used for e.g. linking.
+    libraries.add(library);
+
+    // Weird interaction begins.
+    DillTarget target = this.target;
+    // Create dill library builder (adds it to a map where it's fetched
+    // again momentarily).
+    target.addLibrary(library);
+    // Set up the dill library builder (fetch it from the map again, add it to
+    // another map and setup some auxiliary things).
+    return read(library.importUri, -1, fileUri: library.fileUri);
+  }
+
   Future<Null> buildOutline(DillLibraryBuilder builder) async {
     if (builder.library == null) {
       unhandled("null", "builder.library", 0, builder.fileUri);
@@ -69,10 +87,11 @@
     return buildOutline(builder);
   }
 
-  void finalizeExports() {
+  void finalizeExports({bool suppressFinalizationErrors: false}) {
     builders.forEach((Uri uri, LibraryBuilder builder) {
       DillLibraryBuilder library = builder;
-      library.markAsReadyToFinalizeExports();
+      library.markAsReadyToFinalizeExports(
+          suppressFinalizationErrors: suppressFinalizationErrors);
     });
   }
 
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_target.dart b/pkg/front_end/lib/src/fasta/dill/dill_target.dart
index 7f8ddd0..2a60636 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_target.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_target.dart
@@ -52,10 +52,11 @@
   }
 
   @override
-  Future<Null> buildOutlines() async {
+  Future<Null> buildOutlines({bool suppressFinalizationErrors: false}) async {
     if (loader.libraries.isNotEmpty) {
       await loader.buildOutlines();
-      loader.finalizeExports();
+      loader.finalizeExports(
+          suppressFinalizationErrors: suppressFinalizationErrors);
     }
     isLoaded = true;
   }
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_type_alias_builder.dart b/pkg/front_end/lib/src/fasta/dill/dill_type_alias_builder.dart
index 618d677..5849465 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_type_alias_builder.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_type_alias_builder.dart
@@ -11,6 +11,7 @@
 import '../builder/metadata_builder.dart';
 import '../builder/type_alias_builder.dart';
 import '../builder/type_builder.dart';
+import '../builder/type_variable_builder.dart';
 
 import '../problems.dart' show unimplemented;
 
@@ -25,6 +26,16 @@
     return unimplemented("metadata", -1, null);
   }
 
+  List<TypeVariableBuilder> get typeVariables {
+    return unimplemented("typeVariables", -1, null);
+  }
+
+  int varianceAt(int index) {
+    return typedef.typeParameters[index].variance;
+  }
+
+  bool get fromDill => true;
+
   @override
   int get typeVariablesCount => typedef.typeParameters.length;
 
diff --git a/pkg/front_end/lib/src/fasta/incremental_compiler.dart b/pkg/front_end/lib/src/fasta/incremental_compiler.dart
index d2a091b..dad13e9 100644
--- a/pkg/front_end/lib/src/fasta/incremental_compiler.dart
+++ b/pkg/front_end/lib/src/fasta/incremental_compiler.dart
@@ -40,7 +40,10 @@
 
 import 'package:kernel/kernel.dart' as kernel show Combinator;
 
-import '../api_prototype/file_system.dart' show FileSystemEntity;
+import 'package:kernel/target/changed_structure_notifier.dart'
+    show ChangedStructureNotifier;
+
+import '../api_prototype/file_system.dart' show FileSystem, FileSystemEntity;
 
 import '../api_prototype/incremental_kernel_generator.dart'
     show IncrementalKernelGenerator, isLegalIdentifier;
@@ -142,10 +145,11 @@
   static final Uri debugExprUri =
       new Uri(scheme: "org-dartlang-debug", path: "synthetic_debug_expression");
 
-  KernelTarget userCode;
+  IncrementalKernelTarget userCode;
+  Set<Library> previousSourceBuilders;
 
   IncrementalCompiler.fromComponent(
-      this.context, Component this.componentToInitializeFrom,
+      this.context, this.componentToInitializeFrom,
       [bool outlineOnly, IncrementalSerializer incrementalSerializer])
       : ticker = context.options.ticker,
         initializeFromDillUri = null,
@@ -231,6 +235,10 @@
             await userCode.buildComponent(verify: c.options.verify);
       }
       hierarchy ??= userCode.loader.hierarchy;
+      if (hierarchy != null && userCode.classesChangedStructure != null) {
+        hierarchy.applyMemberChanges(userCode.classesChangedStructure,
+            findDescendants: true);
+      }
       recordNonFullComponentForTesting(componentWithDill);
 
       // Perform actual dill usage tracking.
@@ -269,6 +277,8 @@
       if (componentWithDill == null) {
         userCode.loader.builders.clear();
         userCode = userCodeOld;
+      } else {
+        previousSourceBuilders = await convertSourceLibraryBuildersToDill();
       }
 
       // Output result.
@@ -282,6 +292,35 @@
     });
   }
 
+  /// Convert every SourceLibraryBuilder to a DillLibraryBuilder.
+  /// As we always do this, this will only be the new ones.
+  ///
+  /// Returns the set of Libraries that now has new (dill) builders.
+  Future<Set<Library>> convertSourceLibraryBuildersToDill() async {
+    bool changed = false;
+    Set<Library> newDillLibraryBuilders = new Set<Library>();
+    userBuilders ??= <Uri, LibraryBuilder>{};
+    for (MapEntry<Uri, LibraryBuilder> entry
+        in userCode.loader.builders.entries) {
+      if (entry.value is SourceLibraryBuilder) {
+        SourceLibraryBuilder builder = entry.value;
+        DillLibraryBuilder dillBuilder =
+            dillLoadedData.loader.appendLibrary(builder.library);
+        userCode.loader.builders[entry.key] = dillBuilder;
+        userBuilders[entry.key] = dillBuilder;
+        newDillLibraryBuilders.add(builder.library);
+        changed = true;
+      }
+    }
+    if (changed) {
+      // We suppress finalization errors because they have already been
+      // reported.
+      await dillLoadedData.buildOutlines(suppressFinalizationErrors: true);
+    }
+    if (userBuilders.isEmpty) userBuilders = null;
+    return newDillLibraryBuilders;
+  }
+
   /// Compute which libraries to output and which (previous) errors/warnings we
   /// have to reissue. In the process do some cleanup too.
   List<Library> calculateOutputLibrariesAndIssueLibraryProblems(
@@ -432,7 +471,7 @@
           // overwrite correctly, but the library itself should  not be
           // over written as the library for parts are temporary "fake"
           // libraries.
-          Uri partUri = library.uri.resolve(part.partUri);
+          Uri partUri = getPartUri(library.uri, part);
           Uri fileUri =
               getPartFileUri(library.library.fileUri, part, uriTranslator);
           LibraryBuilder newPartBuilder = userCode.loader.read(partUri, -1,
@@ -532,7 +571,7 @@
       List<LibraryBuilder> reusedLibraries,
       ExperimentalInvalidation experimentalInvalidation,
       Uri firstEntryPoint) {
-    userCode = new KernelTarget(
+    userCode = new IncrementalKernelTarget(
         new HybridFileSystem(
             new MemoryFileSystem(
                 new Uri(scheme: "org-dartlang-debug", path: "/")),
@@ -690,10 +729,7 @@
     }
 
     if (removedDillBuilders) {
-      dillLoadedData.loader.libraries.clear();
-      for (LibraryBuilder builder in dillLoadedData.loader.builders.values) {
-        dillLoadedData.loader.libraries.add(builder.library);
-      }
+      makeDillLoaderLibrariesUpToDateWithBuildersMap();
     }
   }
 
@@ -877,7 +913,9 @@
       }
       appendLibraries(data, bytesLength);
 
-      await dillLoadedData.buildOutlines();
+      // We suppress finalization errors because they will reported via
+      // problemsAsJson fields (with better precision).
+      await dillLoadedData.buildOutlines(suppressFinalizationErrors: true);
       userBuilders = <Uri, LibraryBuilder>{};
       platformBuilders = <LibraryBuilder>[];
       dillLoadedData.loader.builders.forEach((uri, builder) {
@@ -972,17 +1010,23 @@
       // used class.
       for (Class c in classes) {
         Library library = c.enclosingLibrary;
-        // Only add if loaded from a dill file.
-        if (dillLoadedData.loader.builders.containsKey(library.importUri)) {
+        // Only add if loaded from a dill file (and wasn't a 'dill' that was
+        // converted from source builders to dill builders).
+        if (dillLoadedData.loader.builders.containsKey(library.importUri) &&
+            (previousSourceBuilders == null ||
+                !previousSourceBuilders.contains(library))) {
           neededDillLibraries.add(library);
         }
       }
     } else {
       // Cannot track in other kernel class hierarchies or
-      // if all bets are off: Add everything.
+      // if all bets are off: Add everything (except for the libraries we just
+      // converted from source builders to dill builders).
       neededDillLibraries = new Set<Library>();
       for (LibraryBuilder builder in dillLoadedData.loader.builders.values) {
-        if (builder is DillLibraryBuilder) {
+        if (builder is DillLibraryBuilder &&
+            (previousSourceBuilders == null ||
+                !previousSourceBuilders.contains(builder.library))) {
           neededDillLibraries.add(builder.library);
         }
       }
@@ -1026,7 +1070,9 @@
         }
       }
       if (loadedAnything) {
-        await dillLoadedData.buildOutlines();
+        // We suppress finalization errors because they will reported via
+        // problemsAsJson fields (with better precision).
+        await dillLoadedData.buildOutlines(suppressFinalizationErrors: true);
         userBuilders = <Uri, LibraryBuilder>{};
         platformBuilders = <LibraryBuilder>[];
         dillLoadedData.loader.builders.forEach((uri, builder) {
@@ -1102,14 +1148,7 @@
   /// Internal method.
   Uri getPartFileUri(
       Uri parentFileUri, LibraryPart part, UriTranslator uriTranslator) {
-    Uri fileUri;
-    try {
-      fileUri = parentFileUri.resolve(part.partUri);
-    } on FormatException {
-      return new Uri(
-          scheme: SourceLibraryBuilder.MALFORMED_URI_SCHEME,
-          query: Uri.encodeQueryComponent(part.partUri));
-    }
+    Uri fileUri = getPartUri(parentFileUri, part);
     if (fileUri.scheme == "package") {
       // Part was specified via package URI and the resolve above thus
       // did not go as expected. Translate the package URI to get the
@@ -1184,13 +1223,16 @@
     }
 
     List<Library> removedLibraries = new List<Library>();
+    bool removedDillBuilders = false;
     for (Uri uri in potentiallyReferencedLibraries.keys) {
       if (uri.scheme == "package") continue;
       LibraryBuilder builder = userCode.loader.builders.remove(uri);
       if (builder != null) {
         Library lib = builder.library;
         removedLibraries.add(lib);
-        dillLoadedData.loader.builders.remove(uri);
+        if (dillLoadedData.loader.builders.remove(uri) != null) {
+          removedDillBuilders = true;
+        }
         cleanupSourcesForBuilder(builder, uriTranslator,
             CompilerContext.current.uriToSource, uriToSource, partsUsed);
         userBuilders?.remove(uri);
@@ -1202,10 +1244,25 @@
       }
     }
     hierarchy?.applyTreeChanges(removedLibraries, const []);
+    if (removedDillBuilders) {
+      makeDillLoaderLibrariesUpToDateWithBuildersMap();
+    }
 
     return result;
   }
 
+  /// If builders was removed from the [dillLoadedData.loader.builders] map
+  /// the loaders [libraries] list has to be updated too, or those libraries
+  /// will still hang around and be linked into the Component created internally
+  /// in the compilation process.
+  /// This method syncs the [libraries] list with the data in [builders].
+  void makeDillLoaderLibrariesUpToDateWithBuildersMap() {
+    dillLoadedData.loader.libraries.clear();
+    for (LibraryBuilder builder in dillLoadedData.loader.builders.values) {
+      dillLoadedData.loader.libraries.add(builder.library);
+    }
+  }
+
   /// Internal method.
   ///
   /// [partsUsed] indicates part uris that are used by (other/alive) libraries.
@@ -1481,8 +1538,13 @@
   /// Internal method.
   ReusageResult computeReusedLibraries(
       Set<Uri> invalidatedUris, UriTranslator uriTranslator) {
+    Set<Uri> seenUris = new Set<Uri>();
     List<LibraryBuilder> reusedLibraries = <LibraryBuilder>[];
-    reusedLibraries.addAll(platformBuilders);
+    for (int i = 0; i < platformBuilders.length; i++) {
+      LibraryBuilder builder = platformBuilders[i];
+      if (!seenUris.add(builder.uri)) continue;
+      reusedLibraries.add(builder);
+    }
     if (userCode == null && userBuilders == null) {
       return new ReusageResult({}, [], false, reusedLibraries);
     }
@@ -1525,7 +1587,9 @@
 
     addBuilderAndInvalidateUris(Uri uri, LibraryBuilder libraryBuilder) {
       if (uri.scheme == "dart" && !libraryBuilder.isSynthetic) {
-        reusedLibraries.add(libraryBuilder);
+        if (seenUris.add(libraryBuilder.uri)) {
+          reusedLibraries.add(libraryBuilder);
+        }
         return;
       }
       builders[uri] = libraryBuilder;
@@ -1541,7 +1605,7 @@
         }
       } else if (libraryBuilder is DillLibraryBuilder) {
         for (LibraryPart part in libraryBuilder.library.parts) {
-          Uri partUri = libraryBuilder.uri.resolve(part.partUri);
+          Uri partUri = getPartUri(libraryBuilder.uri, part);
           Uri fileUri = getPartFileUri(
               libraryBuilder.library.fileUri, part, uriTranslator);
 
@@ -1607,7 +1671,6 @@
 
     // Builders contain mappings from part uri to builder, meaning the same
     // builder can exist multiple times in the values list.
-    Set<Uri> seenUris = new Set<Uri>();
     for (LibraryBuilder builder in builders.values) {
       if (builder.isPart) continue;
       // TODO(jensj/ahe): This line can probably go away once
@@ -1631,6 +1694,11 @@
     if (userCode != null) {
       Set<Uri> uris = new Set<Uri>.from(userCode.loader.builders.keys);
       uris.removeAll(dillLoadedData.loader.builders.keys);
+      if (previousSourceBuilders != null) {
+        for (Library library in previousSourceBuilders) {
+          uris.add(library.importUri);
+        }
+      }
       invalidatedUris.addAll(uris);
     }
   }
@@ -1653,6 +1721,18 @@
   void recordTemporaryFileForTesting(Uri uri) {}
 }
 
+/// Translate a parts "partUri" to an actual uri with handling of invalid uris.
+Uri getPartUri(Uri parentUri, LibraryPart part) {
+  try {
+    return parentUri.resolve(part.partUri);
+  } on FormatException {
+    // This is also done in [SourceLibraryBuilder.resolve]
+    return new Uri(
+        scheme: SourceLibraryBuilder.MALFORMED_URI_SCHEME,
+        query: Uri.encodeQueryComponent(part.partUri));
+  }
+}
+
 class PackageChangedError {
   const PackageChangedError();
 }
@@ -1696,3 +1776,19 @@
         assert(originalNotReusedLibraries != null),
         assert(missingSources != null);
 }
+
+class IncrementalKernelTarget extends KernelTarget
+    implements ChangedStructureNotifier {
+  Set<Class> classesChangedStructure;
+  IncrementalKernelTarget(FileSystem fileSystem, bool includeComments,
+      DillTarget dillTarget, UriTranslator uriTranslator)
+      : super(fileSystem, includeComments, dillTarget, uriTranslator);
+
+  ChangedStructureNotifier get changedStructureNotifier => this;
+
+  @override
+  void forClass(Class c) {
+    classesChangedStructure ??= new Set<Class>();
+    classesChangedStructure.add(c);
+  }
+}
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index 7aba059..39f4308 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -3174,8 +3174,9 @@
     libraryBuilder.checkBoundsInType(
         type, typeEnvironment, uri, operator.charOffset);
     Expression expression = popForValue();
-    Expression asExpression =
-        forest.createAsExpression(offsetForToken(operator), expression, type);
+    Expression asExpression = forest.createAsExpression(
+        offsetForToken(operator), expression, type,
+        forNonNullableByDefault: libraryBuilder.isNonNullableByDefault);
     push(asExpression);
   }
 
@@ -3187,6 +3188,7 @@
     bool isInverted = not != null;
     Expression isExpression = forest.createIsExpression(
         offsetForToken(isOperator), operand, type,
+        forNonNullableByDefault: libraryBuilder.isNonNullableByDefault,
         notFileOffset: not != null ? offsetForToken(not) : null);
     libraryBuilder.checkBoundsInType(
         type, typeEnvironment, uri, isOperator.charOffset);
diff --git a/pkg/front_end/lib/src/fasta/kernel/class_hierarchy_builder.dart b/pkg/front_end/lib/src/fasta/kernel/class_hierarchy_builder.dart
index 8949530..441fc5b 100644
--- a/pkg/front_end/lib/src/fasta/kernel/class_hierarchy_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/class_hierarchy_builder.dart
@@ -240,9 +240,8 @@
   }
 
   ClassHierarchyNode getNodeFromClassBuilder(ClassBuilder classBuilder) {
-    return nodes[classBuilder.cls] ??= new ClassHierarchyNodeBuilder(
-            this, classBuilder, loader.target.enableNonNullable)
-        .build();
+    return nodes[classBuilder.cls] ??=
+        new ClassHierarchyNodeBuilder(this, classBuilder).build();
   }
 
   ClassHierarchyNode getNodeFromTypeBuilder(TypeBuilder type) {
@@ -409,9 +408,8 @@
     for (int i = 0; i < classes.length; i++) {
       ClassBuilder classBuilder = classes[i];
       if (!classBuilder.isPatch) {
-        hierarchy.nodes[classBuilder.cls] = new ClassHierarchyNodeBuilder(
-                hierarchy, classBuilder, loader.target.enableNonNullable)
-            .build();
+        hierarchy.nodes[classBuilder.cls] =
+            new ClassHierarchyNodeBuilder(hierarchy, classBuilder).build();
       } else {
         // TODO(ahe): Merge the injected members of patch into the hierarchy
         // node of `cls.origin`.
@@ -426,15 +424,11 @@
 
   final ClassBuilder classBuilder;
 
-  /// Whether non-nullable types are supported.
-  final bool enableNonNullable;
-
   bool hasNoSuchMethod = false;
 
   List<ClassMember> abstractMembers = null;
 
-  ClassHierarchyNodeBuilder(
-      this.hierarchy, this.classBuilder, this.enableNonNullable);
+  ClassHierarchyNodeBuilder(this.hierarchy, this.classBuilder);
 
   ClassBuilder get objectClass => hierarchy.objectClassBuilder;
 
@@ -736,8 +730,16 @@
       if (substitution != null) {
         bType = substitution.substituteType(bType);
       }
+      if (hierarchy
+              .coreTypes.objectClass.enclosingLibrary.isNonNullableByDefault &&
+          !a.classBuilder.library.isNonNullableByDefault &&
+          b.member == hierarchy.coreTypes.objectEquals) {
+        // In legacy code we special case `Object.==` to infer `dynamic` instead
+        // `Object!`.
+        bType = const DynamicType();
+      }
       if (aType != bType) {
-        if (a.parent == classBuilder && a.formals[i].type == null) {
+        if (a.classBuilder == classBuilder && a.formals[i].type == null) {
           result = inferParameterType(classBuilder, a, a.formals[i], bType,
               hadTypesInferred, hierarchy);
         } else {
@@ -1177,13 +1179,13 @@
       member = delayedMember.withParent(classBuilder);
       hierarchy.delayedMemberChecks.add(member);
     }
-    if (mergeKind.intoCurrentClass &&
-        hierarchy.loader.target.enableNonNullable) {
+    if (mergeKind.intoCurrentClass) {
       if (member.classBuilder.library.isNonNullableByDefault &&
           !classBuilder.library.isNonNullableByDefault) {
         if (member is! DelayedMember) {
           member = new InterfaceConflict(
-              classBuilder, [member], mergeKind.forSetters, shouldModifyKernel);
+              classBuilder, [member], mergeKind.forSetters, shouldModifyKernel,
+              isAbstract: isAbstract(member));
           hierarchy.delayedMemberChecks.add(member);
         }
       }
@@ -1288,6 +1290,11 @@
 
       superclasses = new List<DartType>(supernode.superclasses.length + 1);
       DartType supertype = classBuilder.supertype.build(classBuilder.library);
+      if (supertype is! InterfaceType) {
+        // If the superclass is not an interface type we use Object instead.
+        // A similar normalization is performed on [supernode] above.
+        supertype = hierarchy.coreTypes.objectNonNullableRawType;
+      }
       superclasses.setRange(0, superclasses.length - 1,
           substSupertypes(supertype, supernode.superclasses));
       superclasses[superclasses.length - 1] = recordSupertype(supertype);
@@ -1499,8 +1506,7 @@
 
   DartType addInterface(
       List<DartType> interfaces, List<DartType> superclasses, DartType type) {
-    if (hierarchy.loader.target.enableNonNullable &&
-        !classBuilder.library.isNonNullableByDefault) {
+    if (!classBuilder.library.isNonNullableByDefault) {
       type = legacyErasure(hierarchy.coreTypes, type);
     }
     if (type is InterfaceType) {
@@ -1511,18 +1517,16 @@
       DartType superclass = depth < myDepth ? superclasses[depth] : null;
       if (superclass is InterfaceType &&
           superclass.classNode == type.classNode) {
-        if (hierarchy.loader.target.enableNonNullable) {
-          // This is a potential conflict.
-          if (classBuilder.library.isNonNullableByDefault) {
-            superclass = nnbdTopMerge(hierarchy.coreTypes, superclass, type);
-            if (superclass == null) {
-              // This is a conflict.
-              // TODO(johnniwinther): Report errors here instead of through
-              // the computation of the [ClassHierarchy].
-              superclass = superclasses[depth];
-            } else {
-              superclasses[depth] = superclass;
-            }
+        // This is a potential conflict.
+        if (classBuilder.library.isNonNullableByDefault) {
+          superclass = nnbdTopMerge(hierarchy.coreTypes, superclass, type);
+          if (superclass == null) {
+            // This is a conflict.
+            // TODO(johnniwinther): Report errors here instead of through
+            // the computation of the [ClassHierarchy].
+            superclass = superclasses[depth];
+          } else {
+            superclasses[depth] = superclass;
           }
         }
         return superclass;
@@ -1533,18 +1537,16 @@
           DartType interface = interfaces[i];
           if (interface is InterfaceType &&
               interface.classNode == type.classNode) {
-            if (hierarchy.loader.target.enableNonNullable) {
-              // This is a potential conflict.
-              if (classBuilder.library.isNonNullableByDefault) {
-                interface = nnbdTopMerge(hierarchy.coreTypes, interface, type);
-                if (interface == null) {
-                  // This is a conflict.
-                  // TODO(johnniwinther): Report errors here instead of through
-                  // the computation of the [ClassHierarchy].
-                  interface = interfaces[i];
-                } else {
-                  interfaces[i] = interface;
-                }
+            // This is a potential conflict.
+            if (classBuilder.library.isNonNullableByDefault) {
+              interface = nnbdTopMerge(hierarchy.coreTypes, interface, type);
+              if (interface == null) {
+                // This is a conflict.
+                // TODO(johnniwinther): Report errors here instead of through
+                // the computation of the [ClassHierarchy].
+                interface = interfaces[i];
+              } else {
+                interfaces[i] = interface;
               }
             }
             return interface;
@@ -2462,8 +2464,11 @@
 }
 
 class InterfaceConflict extends DelayedMember {
+  bool isAbstract;
+
   InterfaceConflict(ClassBuilder parent, List<ClassMember> declarations,
-      bool isSetter, bool modifyKernel)
+      bool isSetter, bool modifyKernel,
+      {this.isAbstract: true})
       : super(parent, declarations, isSetter, modifyKernel);
 
   Member combinedMemberSignatureResult;
@@ -2710,6 +2715,8 @@
   static ClassMember selectConcrete(ClassMember declaration) {
     if (declaration is AbstractMemberOverridingImplementation) {
       return declaration.concreteImplementation;
+    } else if (declaration is InterfaceConflict && !declaration.isAbstract) {
+      return selectConcrete(declaration.declarations.single);
     } else {
       return declaration;
     }
@@ -2751,7 +2758,8 @@
 }
 
 bool isAbstract(ClassMember declaration) {
-  return declaration.member.isAbstract || declaration is InterfaceConflict;
+  return declaration.member.isAbstract ||
+      (declaration is InterfaceConflict && declaration.isAbstract);
 }
 
 bool inferParameterType(
@@ -2762,6 +2770,22 @@
     bool hadTypesInferred,
     ClassHierarchyBuilder hierarchy) {
   debug?.log("Inferred type ${type} for ${parameterBuilder}");
+
+  if (classBuilder.library.isNonNullableByDefault) {
+    if (hadTypesInferred) {
+      type = nnbdTopMerge(
+          hierarchy.coreTypes, parameterBuilder.variable.type, type);
+      if (type != null) {
+        // The nnbd top merge exists so [type] is the inferred type.
+        parameterBuilder.variable.type = type;
+        return true;
+      }
+      // The nnbd top merge doesn't exist. An error will be reported below.
+    }
+  } else {
+    type = legacyErasure(hierarchy.coreTypes, type);
+  }
+
   if (type == parameterBuilder.variable.type) return true;
   bool result = true;
   if (hadTypesInferred) {
diff --git a/pkg/front_end/lib/src/fasta/kernel/constant_evaluator.dart b/pkg/front_end/lib/src/fasta/kernel/constant_evaluator.dart
index 6e99f5d..430f0f2 100644
--- a/pkg/front_end/lib/src/fasta/kernel/constant_evaluator.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/constant_evaluator.dart
@@ -1791,8 +1791,11 @@
   Constant visitAsExpression(AsExpression node) {
     final Constant constant = _evaluateSubexpression(node.operand);
     if (shouldBeUnevaluated) {
-      return unevaluated(node,
-          new AsExpression(extract(constant), env.substituteType(node.type)));
+      return unevaluated(
+          node,
+          new AsExpression(extract(constant), env.substituteType(node.type))
+            ..isForNonNullableByDefault =
+                _staticTypeContext.isNonNullableByDefault);
     }
     return ensureIsSubtype(constant, evaluateDartType(node, node.type), node);
   }
@@ -1801,7 +1804,11 @@
   Constant visitIsExpression(IsExpression node) {
     final Constant constant = node.operand.accept(this);
     if (shouldBeUnevaluated) {
-      return unevaluated(node, new IsExpression(extract(constant), node.type));
+      return unevaluated(
+          node,
+          new IsExpression(extract(constant), node.type)
+            ..fileOffset = node.fileOffset
+            ..flags = node.flags);
     }
     if (constant is NullConstant) {
       DartType nodeType = node.type;
diff --git a/pkg/front_end/lib/src/fasta/kernel/forest.dart b/pkg/front_end/lib/src/fasta/kernel/forest.dart
index ce53e3d..c1104f7 100644
--- a/pkg/front_end/lib/src/fasta/kernel/forest.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/forest.dart
@@ -201,9 +201,13 @@
   }
 
   Expression createAsExpression(
-      int fileOffset, Expression expression, DartType type) {
+      int fileOffset, Expression expression, DartType type,
+      {bool forNonNullableByDefault}) {
+    assert(forNonNullableByDefault != null);
     assert(fileOffset != null);
-    return new AsExpression(expression, type)..fileOffset = fileOffset;
+    return new AsExpression(expression, type)
+      ..fileOffset = fileOffset
+      ..isForNonNullableByDefault = forNonNullableByDefault;
   }
 
   Expression createSpreadElement(int fileOffset, Expression expression,
@@ -406,10 +410,12 @@
   /// is non-null the test is negated the that file offset.
   Expression createIsExpression(
       int fileOffset, Expression operand, DartType type,
-      {int notFileOffset}) {
+      {bool forNonNullableByDefault, int notFileOffset}) {
+    assert(forNonNullableByDefault != null);
     assert(fileOffset != null);
     Expression result = new IsExpression(operand, type)
-      ..fileOffset = fileOffset;
+      ..fileOffset = fileOffset
+      ..isForNonNullableByDefault = forNonNullableByDefault;
     if (notFileOffset != null) {
       result = createNot(notFileOffset, result);
     }
diff --git a/pkg/front_end/lib/src/fasta/kernel/forwarding_node.dart b/pkg/front_end/lib/src/fasta/kernel/forwarding_node.dart
index 8c564b9..6b03c5b 100644
--- a/pkg/front_end/lib/src/fasta/kernel/forwarding_node.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/forwarding_node.dart
@@ -47,7 +47,7 @@
 class ForwardingNode {
   final ClassHierarchyBuilder hierarchy;
 
-  final SourceClassBuilder parent;
+  final SourceClassBuilder classBuilder;
 
   final ClassMember combinedMemberSignatureResult;
 
@@ -57,12 +57,12 @@
   /// procedures of the class in question.
   final List<ClassMember> _candidates;
 
-  ForwardingNode(this.hierarchy, this.parent,
+  ForwardingNode(this.hierarchy, this.classBuilder,
       this.combinedMemberSignatureResult, this._candidates, this.kind);
 
   Name get name => combinedMemberSignatureResult.member.name;
 
-  Class get enclosingClass => parent.cls;
+  Class get enclosingClass => classBuilder.cls;
 
   /// Finishes handling of this node by propagating covariance and creating
   /// forwarding stubs if necessary.
@@ -169,12 +169,9 @@
     bool needsCheck(DartType type) => needsCheckVisitor == null
         ? false
         : substitution.substituteType(type).accept(needsCheckVisitor);
-    bool enableNonNullable = hierarchy.loader.target.enableNonNullable;
-    bool isNonNullableByDefault =
-        enableNonNullable && parent.library.isNonNullableByDefault;
+    bool isNonNullableByDefault = classBuilder.library.isNonNullableByDefault;
 
     DartType initialType(DartType a) {
-      if (!enableNonNullable) return null;
       if (!isNonNullableByDefault) {
         a = legacyErasure(hierarchy.coreTypes, a);
       }
@@ -191,8 +188,8 @@
 
     for (int i = 0; i < interfacePositionalParameters.length; i++) {
       VariableDeclaration parameter = interfacePositionalParameters[i];
-      DartType parameterType = parameter.type;
-      DartType type = initialType(substitution.substituteType(parameterType));
+      DartType parameterType = substitution.substituteType(parameter.type);
+      DartType type = initialType(parameterType);
       bool isGenericCovariantImpl =
           parameter.isGenericCovariantImpl || needsCheck(parameter.type);
       bool isCovariant = parameter.isCovariant;
@@ -232,19 +229,17 @@
           stub.function.positionalParameters[i].isCovariant = true;
         }
       }
-      if (enableNonNullable) {
-        if (type != null && type != parameterType) {
-          // TODO(johnniwinther): Report an error when [type] is null; this
-          // means that nnbd-top-merge was not defined.
-          createStubIfNeeded(forMemberSignature: true);
-          stub.function.positionalParameters[i].type = type;
-        }
+      if (type != null && type != parameterType) {
+        // TODO(johnniwinther): Report an error when [type] is null; this
+        // means that nnbd-top-merge was not defined.
+        createStubIfNeeded(forMemberSignature: true);
+        stub.function.positionalParameters[i].type = type;
       }
     }
     for (int i = 0; i < interfaceNamedParameters.length; i++) {
       VariableDeclaration parameter = interfaceNamedParameters[i];
-      DartType parameterType = parameter.type;
-      DartType type = initialType(substitution.substituteType(parameterType));
+      DartType parameterType = substitution.substituteType(parameter.type);
+      DartType type = initialType(parameterType);
       bool isGenericCovariantImpl =
           parameter.isGenericCovariantImpl || needsCheck(parameter.type);
       bool isCovariant = parameter.isCovariant;
@@ -284,13 +279,11 @@
           stub.function.namedParameters[i].isCovariant = true;
         }
       }
-      if (enableNonNullable) {
-        if (type != null && type != parameterType) {
-          // TODO(johnniwinther): Report an error when [type] is null; this
-          // means that nnbd-top-merge was not defined.
-          createStubIfNeeded(forMemberSignature: true);
-          stub.function.namedParameters[i].type = type;
-        }
+      if (type != null && type != parameterType) {
+        // TODO(johnniwinther): Report an error when [type] is null; this
+        // means that nnbd-top-merge was not defined.
+        createStubIfNeeded(forMemberSignature: true);
+        stub.function.namedParameters[i].type = type;
       }
     }
     for (int i = 0; i < interfaceTypeParameters.length; i++) {
@@ -321,21 +314,19 @@
         }
       }
     }
-    if (enableNonNullable) {
-      DartType returnType =
-          substitution.substituteType(getReturnType(interfaceMember));
-      DartType type = initialType(returnType);
-      for (int j = 0; j < _candidates.length; j++) {
-        Member otherMember = getCandidateAt(j);
-        type = mergeTypes(
-            type, substitutions[j].substituteType(getReturnType(otherMember)));
-      }
-      if (type != null && type != returnType) {
-        // TODO(johnniwinther): Report an error when [type] is null; this
-        // means that nnbd-top-merge was not defined.
-        createStubIfNeeded(forMemberSignature: true);
-        stub.function.returnType = type;
-      }
+    DartType returnType =
+        substitution.substituteType(getReturnType(interfaceMember));
+    DartType type = initialType(returnType);
+    for (int j = 0; j < _candidates.length; j++) {
+      Member otherMember = getCandidateAt(j);
+      type = mergeTypes(
+          type, substitutions[j].substituteType(getReturnType(otherMember)));
+    }
+    if (type != null && type != returnType) {
+      // TODO(johnniwinther): Report an error when [type] is null; this
+      // means that nnbd-top-merge was not defined.
+      createStubIfNeeded(forMemberSignature: true);
+      stub.function.returnType = type;
     }
     return stub;
   }
@@ -447,13 +438,13 @@
       finalTarget = target;
     }
     Procedure referenceFrom;
-    if (parent.referencesFromIndexed != null) {
+    if (classBuilder.referencesFromIndexed != null) {
       if (kind == ProcedureKind.Setter) {
         referenceFrom =
-            parent.referencesFromIndexed.lookupProcedureSetter(name.name);
+            classBuilder.referencesFromIndexed.lookupProcedureSetter(name.name);
       } else {
-        referenceFrom =
-            parent.referencesFromIndexed.lookupProcedureNotSetter(name.name);
+        referenceFrom = classBuilder.referencesFromIndexed
+            .lookupProcedureNotSetter(name.name);
       }
     }
     return new Procedure(name, kind, function,
diff --git a/pkg/front_end/lib/src/fasta/kernel/implicit_field_type.dart b/pkg/front_end/lib/src/fasta/kernel/implicit_field_type.dart
index a437394a..589e3a7 100644
--- a/pkg/front_end/lib/src/fasta/kernel/implicit_field_type.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/implicit_field_type.dart
@@ -106,11 +106,8 @@
 
   DartType inferType() {
     DartType type = _root.inferType();
-    if (_targetFieldBuilder.library.loader.target.enableNonNullable) {
-      if (!_targetFieldBuilder.library.isNonNullableByDefault) {
-        type =
-            legacyErasure(_targetFieldBuilder.library.loader.coreTypes, type);
-      }
+    if (!_targetFieldBuilder.library.isNonNullableByDefault) {
+      type = legacyErasure(_targetFieldBuilder.library.loader.coreTypes, type);
     }
     return _targetFieldBuilder.fieldType = type;
   }
diff --git a/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart b/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
index 070a818..c5e3e53 100644
--- a/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
@@ -3531,6 +3531,8 @@
         }
         binary = new AsExpression(binary, binaryType)
           ..isTypeError = true
+          ..isCovarianceCheck = true
+          ..isForNonNullableByDefault = inferrer.isNonNullableByDefault
           ..fileOffset = fileOffset;
       }
     }
@@ -3616,6 +3618,8 @@
         }
         unary = new AsExpression(unary, unaryType)
           ..isTypeError = true
+          ..isCovarianceCheck = true
+          ..isForNonNullableByDefault = inferrer.isNonNullableByDefault
           ..fileOffset = fileOffset;
       }
     }
@@ -3693,6 +3697,8 @@
         }
         read = new AsExpression(read, readType)
           ..isTypeError = true
+          ..isCovarianceCheck = true
+          ..isForNonNullableByDefault = inferrer.isNonNullableByDefault
           ..fileOffset = fileOffset;
       }
     }
@@ -3867,6 +3873,8 @@
         }
         read = new AsExpression(read, readType)
           ..isTypeError = true
+          ..isCovarianceCheck = true
+          ..isForNonNullableByDefault = inferrer.isNonNullableByDefault
           ..fileOffset = fileOffset;
       }
       Member member = readTarget.member;
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_target.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_target.dart
index c5cd908..292505e 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_target.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_target.dart
@@ -45,6 +45,8 @@
 import 'package:kernel/reference_from_index.dart' show IndexedClass;
 
 import 'package:kernel/type_algebra.dart' show substitute;
+import 'package:kernel/target/changed_structure_notifier.dart'
+    show ChangedStructureNotifier;
 import 'package:kernel/target/targets.dart' show DiagnosticReporter;
 import 'package:kernel/type_environment.dart' show TypeEnvironment;
 import 'package:kernel/verifier.dart' show verifyGetStaticType;
@@ -890,9 +892,12 @@
         environmentDefines,
         new KernelDiagnosticReporter(loader),
         loader.referenceFromIndex,
-        logger: (String msg) => ticker.logMs(msg));
+        logger: (String msg) => ticker.logMs(msg),
+        changedStructureNotifier: changedStructureNotifier);
   }
 
+  ChangedStructureNotifier get changedStructureNotifier => null;
+
   void runProcedureTransformations(Procedure procedure) {
     backendTarget.performTransformationsOnProcedure(
         loader.coreTypes, loader.hierarchy, procedure,
diff --git a/pkg/front_end/lib/src/fasta/kernel/transform_collections.dart b/pkg/front_end/lib/src/fasta/kernel/transform_collections.dart
index b9f0955..c35373e 100644
--- a/pkg/front_end/lib/src/fasta/kernel/transform_collections.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/transform_collections.dart
@@ -776,6 +776,7 @@
     assert(fileOffset != TreeNode.noOffset);
     return new AsExpression(expression, type)
       ..isTypeError = true
+      ..isForNonNullableByDefault = _currentLibrary.isNonNullableByDefault
       ..fileOffset = fileOffset;
   }
 
diff --git a/pkg/front_end/lib/src/fasta/kernel/type_algorithms.dart b/pkg/front_end/lib/src/fasta/kernel/type_algorithms.dart
index 658de83..30af5bc 100644
--- a/pkg/front_end/lib/src/fasta/kernel/type_algorithms.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/type_algorithms.dart
@@ -91,15 +91,20 @@
           for (int i = 0; i < type.arguments.length; ++i) {
             const int visitMarker = -2;
 
-            TypeVariableBuilder declarationTypeVariable =
-                declaration.typeVariables[i];
-
-            if (declarationTypeVariable.variance == pendingVariance) {
+            int declarationTypeVariableVariance = declaration.varianceAt(i);
+            if (declarationTypeVariableVariance == pendingVariance) {
+              assert(!declaration.fromDill);
+              TypeVariableBuilder declarationTypeVariable =
+                  declaration.typeVariables[i];
               declarationTypeVariable.variance = visitMarker;
               int computedVariance = computeVariance(
                   declarationTypeVariable, declaration.type, libraryBuilder);
-              declarationTypeVariable.variance = computedVariance;
-            } else if (declarationTypeVariable.variance == visitMarker) {
+              declarationTypeVariableVariance =
+                  declarationTypeVariable.variance = computedVariance;
+            } else if (declarationTypeVariableVariance == visitMarker) {
+              assert(!declaration.fromDill);
+              TypeVariableBuilder declarationTypeVariable =
+                  declaration.typeVariables[i];
               libraryBuilder.addProblem(
                   templateCyclicTypedef.withArguments(declaration.name),
                   declaration.charOffset,
@@ -108,7 +113,8 @@
               // Use [Variance.unrelated] for recovery.  The type with the
               // cyclic dependency will be replaced with an [InvalidType]
               // elsewhere.
-              declarationTypeVariable.variance = Variance.unrelated;
+              declarationTypeVariableVariance =
+                  declarationTypeVariable.variance = Variance.unrelated;
             }
 
             result = Variance.meet(
@@ -116,7 +122,7 @@
                 Variance.combine(
                     computeVariance(
                         variable, type.arguments[i], libraryBuilder),
-                    declarationTypeVariable.variance));
+                    declarationTypeVariableVariance));
           }
         }
         return result;
diff --git a/pkg/front_end/lib/src/fasta/library_graph.dart b/pkg/front_end/lib/src/fasta/library_graph.dart
index ddbf967..5a75f85 100644
--- a/pkg/front_end/lib/src/fasta/library_graph.dart
+++ b/pkg/front_end/lib/src/fasta/library_graph.dart
@@ -4,14 +4,13 @@
 
 library fasta.library_graph;
 
-import 'package:front_end/src/fasta/source/source_library_builder.dart'
-    show SourceLibraryBuilder;
-
 import 'package:kernel/kernel.dart'
     show Library, LibraryDependency, LibraryPart;
 
 import 'package:kernel/util/graph.dart' show Graph;
 
+import 'incremental_compiler.dart' show getPartUri;
+
 class LibraryGraph implements Graph<Uri> {
   final Map<Uri, Library> libraries;
 
@@ -42,8 +41,8 @@
     // Normally there won't be libraries for these, but if, for instance,
     // the part didn't exist there will be a synthetic library.
     for (LibraryPart part in library.parts) {
-      Uri partUri = getPartUri(library.importUri, part.partUri);
-      Uri fileUri = getPartUri(library.fileUri, part.partUri);
+      Uri partUri = getPartUri(library.importUri, part);
+      Uri fileUri = getPartUri(library.fileUri, part);
       if (libraries.containsKey(partUri)) {
         yield partUri;
       } else if (fileUri != partUri && libraries.containsKey(fileUri)) {
@@ -51,15 +50,4 @@
       }
     }
   }
-
-  Uri getPartUri(Uri base, String part) {
-    try {
-      return base.resolve(part);
-    } on FormatException {
-      // This is also done in [SourceLibraryBuilder.resolve]
-      return new Uri(
-          scheme: SourceLibraryBuilder.MALFORMED_URI_SCHEME,
-          query: Uri.encodeQueryComponent(part));
-    }
-  }
 }
diff --git a/pkg/front_end/lib/src/fasta/source/outline_builder.dart b/pkg/front_end/lib/src/fasta/source/outline_builder.dart
index 59bbed4..f79ddbe 100644
--- a/pkg/front_end/lib/src/fasta/source/outline_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/outline_builder.dart
@@ -1049,6 +1049,11 @@
           }
         }
       }
+      if (typeVariables != null) {
+        TypeVariableBuilder typeVariableBuilder = typeVariables.first;
+        addProblem(messageOperatorWithTypeParameters,
+            typeVariableBuilder.charOffset, typeVariableBuilder.name.length);
+      }
     } else {
       name = nameOrOperator;
       kind = computeProcedureKind(getOrSet);
diff --git a/pkg/front_end/lib/src/fasta/source/source_class_builder.dart b/pkg/front_end/lib/src/fasta/source/source_class_builder.dart
index f8e8790..6940aaa 100644
--- a/pkg/front_end/lib/src/fasta/source/source_class_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_class_builder.dart
@@ -422,7 +422,6 @@
     cls.procedures.add(cloned);
     cloned.parent = cls;
 
-    SourceLibraryBuilder library = this.library;
     library.forwardersOrigins.add(cloned);
     library.forwardersOrigins.add(procedure);
   }
diff --git a/pkg/front_end/lib/src/fasta/source/source_library_builder.dart b/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
index 11ef3f6..0c4dfb2 100644
--- a/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
@@ -569,7 +569,7 @@
 
   Uri resolve(Uri baseUri, String uri, int uriOffset, {isPart: false}) {
     if (uri == null) {
-      addProblem(messageExpectedUri, uriOffset, noLength, this.uri);
+      addProblem(messageExpectedUri, uriOffset, noLength, fileUri);
       return new Uri(scheme: MALFORMED_URI_SCHEME);
     }
     Uri parsedUri;
@@ -580,7 +580,7 @@
       // or to the initial quote if no position is given.
       // (Assumes the directive is using a single-line string.)
       addProblem(templateCouldNotParseUri.withArguments(uri, e.message),
-          uriOffset + 1 + (e.offset ?? -1), 1, this.uri);
+          uriOffset + 1 + (e.offset ?? -1), 1, fileUri);
       return new Uri(
           scheme: MALFORMED_URI_SCHEME, query: Uri.encodeQueryComponent(uri));
     }
@@ -3081,7 +3081,7 @@
                   formal.name, formal.variable.type, isNonNullableByDefault),
               formal.charOffset,
               formal.name.length,
-              uri);
+              fileUri);
         } else {
           addProblem(
               templateOptionalNonNullableWithoutInitializerWarning
@@ -3089,7 +3089,7 @@
                       isNonNullableByDefault),
               formal.charOffset,
               formal.name.length,
-              uri);
+              fileUri);
         }
       }
     }
diff --git a/pkg/front_end/lib/src/fasta/source/source_loader.dart b/pkg/front_end/lib/src/fasta/source/source_loader.dart
index d0a8f91..087edf8 100644
--- a/pkg/front_end/lib/src/fasta/source/source_loader.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_loader.dart
@@ -911,6 +911,7 @@
     } else {
       hierarchy.onAmbiguousSupertypes = onAmbiguousSupertypes;
       Component component = computeFullComponent();
+      hierarchy.coreTypes = coreTypes;
       hierarchy.applyTreeChanges(const [], component.libraries,
           reissueAmbiguousSupertypesFor: component);
     }
diff --git a/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart b/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
index f1d7ed6..91e493c 100644
--- a/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
+++ b/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
@@ -703,6 +703,8 @@
         // Insert an implicit downcast.
         result = new AsExpression(expression, initialContextType)
           ..isTypeError = true
+          ..isForNonNullableByDefault = isNonNullableByDefault
+          ..isForDynamic = expressionType is DynamicType
           ..fileOffset = fileOffset;
         break;
       case AssignabilityKind.assignableTearoff:
@@ -713,6 +715,7 @@
             _tearOffCall(expression, expressionType, fileOffset).tearoff,
             initialContextType)
           ..isTypeError = true
+          ..isForNonNullableByDefault = isNonNullableByDefault
           ..fileOffset = fileOffset;
         break;
       case AssignabilityKind.unassignable:
@@ -740,6 +743,16 @@
         result = _wrapUnassignableExpression(typedTearoff.tearoff,
             typedTearoff.tearoffType, contextType, errorTemplate);
         break;
+      case AssignabilityKind.unassignableCantTearoff:
+        // The first call to _computeAssignabilityKind is done for the purpose
+        // of code generation, and the inability to tear off from a
+        // potentially nullable receiver shouldn't arise as an issue in any
+        // mode other than the strong mode.
+        assert(isNonNullableByDefault && performNnbdChecks && nnbdStrongMode);
+
+        result = _wrapTearoffErrorExpression(
+            expression, contextType, templateNullableTearoffError);
+        break;
       default:
         return unhandled("${kind}", "ensureAssignable", fileOffset, helper.uri);
     }
@@ -787,6 +800,11 @@
         case AssignabilityKind.unassignableTearoff:
           // Don't report the same problem twice.
           if (kind == AssignabilityKind.unassignableTearoff) break;
+
+          // The first handling of the error should have happened in the strong
+          // mode.
+          assert(!nnbdStrongMode);
+
           if (contextType is! InvalidType && expressionType is! InvalidType) {
             TypedTearoff typedTearoff =
                 _tearOffCall(expression, expressionType, fileOffset);
@@ -798,6 +816,19 @@
                 noLength);
           }
           break;
+        case AssignabilityKind.unassignableCantTearoff:
+          // Don't report the same problem twice.
+          if (kind == AssignabilityKind.unassignableCantTearoff) break;
+
+          // The first handling of the error should have happened in the strong
+          // mode.
+          assert(!nnbdStrongMode);
+
+          if (isNonNullableByDefault && performNnbdChecks) {
+            result = _wrapTearoffErrorExpression(
+                expression, contextType, templateNullableTearoffWarning);
+          }
+          break;
         default:
           return unhandled(
               "${kind}", "ensureAssignable:weak", fileOffset, helper.uri);
@@ -807,6 +838,25 @@
     return result;
   }
 
+  Expression _wrapTearoffErrorExpression(Expression expression,
+      DartType contextType, Template<Message Function(String)> template) {
+    assert(template != null);
+    Expression errorNode = new AsExpression(
+        expression,
+        // TODO(ahe): The outline phase doesn't correctly remove invalid
+        // uses of type variables, for example, on static members. Once
+        // that has been fixed, we should always be able to use
+        // [contextType] directly here.
+        hasAnyTypeVariables(contextType) ? const BottomType() : contextType)
+      ..isTypeError = true
+      ..fileOffset = expression.fileOffset;
+    if (contextType is! InvalidType) {
+      errorNode = helper.wrapInProblem(
+          errorNode, template.withArguments(callName.name), noLength);
+    }
+    return errorNode;
+  }
+
   Expression _wrapUnassignableExpression(
       Expression expression,
       DartType expressionType,
@@ -817,9 +867,10 @@
         // TODO(ahe): The outline phase doesn't correctly remove invalid
         // uses of type variables, for example, on static members. Once
         // that has been fixed, we should always be able to use
-        // [expectedType] directly here.
+        // [contextType] directly here.
         hasAnyTypeVariables(contextType) ? const BottomType() : contextType)
       ..isTypeError = true
+      ..isForNonNullableByDefault = isNonNullableByDefault
       ..fileOffset = expression.fileOffset;
     if (contextType is! InvalidType && expressionType is! InvalidType) {
       errorNode = helper.wrapInProblem(
@@ -880,6 +931,9 @@
       if (callMember is Procedure && callMember.kind == ProcedureKind.Method) {
         if (_shouldTearOffCall(contextType, expressionType)) {
           needsTearoff = true;
+          if (isStrongNullabilityMode && expressionType.isPotentiallyNullable) {
+            return AssignabilityKind.unassignableCantTearoff;
+          }
           expressionType =
               getGetterTypeForMemberTarget(callMember, expressionType)
                   .withNullability(expressionType.nullability);
@@ -1747,6 +1801,8 @@
       case MethodContravarianceCheckKind.checkMethodReturn:
         AsExpression replacement = new AsExpression(expression, inferredType)
           ..isTypeError = true
+          ..isCovarianceCheck = true
+          ..isForNonNullableByDefault = isNonNullableByDefault
           ..fileOffset = fileOffset;
         if (instrumentation != null) {
           int offset = arguments.fileOffset == -1
@@ -1761,6 +1817,8 @@
             desugaredInvocation.name, desugaredInvocation.interfaceTarget);
         AsExpression asExpression = new AsExpression(propertyGet, functionType)
           ..isTypeError = true
+          ..isCovarianceCheck = true
+          ..isForNonNullableByDefault = isNonNullableByDefault
           ..fileOffset = fileOffset;
         MethodInvocation replacement = new MethodInvocation(
             asExpression, callName, desugaredInvocation.arguments);
@@ -1792,7 +1850,7 @@
       // not spec'ed anywhere.
       return const DynamicType();
     }
-    return initializerType;
+    return demoteType(initializerType);
   }
 
   void inferSyntheticVariable(VariableDeclarationImpl variable) {
@@ -2732,6 +2790,8 @@
             ..fileOffset = fileOffset,
           result.inferredType)
         ..isTypeError = true
+        ..isCovarianceCheck = true
+        ..isForNonNullableByDefault = isNonNullableByDefault
         ..fileOffset = fileOffset;
       if (instrumentation != null) {
         int offset =
@@ -2826,6 +2886,8 @@
       PropertyGet propertyGet = new PropertyGet(receiver, getter.name, getter);
       AsExpression asExpression = new AsExpression(propertyGet, functionType)
         ..isTypeError = true
+        ..isCovarianceCheck = true
+        ..isForNonNullableByDefault = isNonNullableByDefault
         ..fileOffset = fileOffset;
       replacement = new MethodInvocation(asExpression, callName, arguments);
       if (instrumentation != null) {
@@ -2901,6 +2963,8 @@
       PropertyGet propertyGet = new PropertyGet(receiver, field.name, field);
       AsExpression asExpression = new AsExpression(propertyGet, functionType)
         ..isTypeError = true
+        ..isCovarianceCheck = true
+        ..isForNonNullableByDefault = isNonNullableByDefault
         ..fileOffset = fileOffset;
       replacement = new MethodInvocation(asExpression, callName, arguments);
       if (instrumentation != null) {
@@ -3324,16 +3388,16 @@
     return null;
   }
 
-  bool _shouldTearOffCall(DartType expectedType, DartType actualType) {
-    if (expectedType is InterfaceType &&
-        expectedType.classNode == typeSchemaEnvironment.futureOrClass) {
-      expectedType = (expectedType as InterfaceType).typeArguments[0];
+  bool _shouldTearOffCall(DartType contextType, DartType expressionType) {
+    if (contextType is InterfaceType &&
+        contextType.classNode == typeSchemaEnvironment.futureOrClass) {
+      contextType = (contextType as InterfaceType).typeArguments[0];
     }
-    if (expectedType is FunctionType) return true;
-    if (expectedType is InterfaceType &&
-        expectedType.classNode == typeSchemaEnvironment.functionClass) {
-      if (!typeSchemaEnvironment.isSubtypeOf(
-          actualType, expectedType, SubtypeCheckMode.ignoringNullabilities)) {
+    if (contextType is FunctionType) return true;
+    if (contextType is InterfaceType &&
+        contextType.classNode == typeSchemaEnvironment.functionClass) {
+      if (!typeSchemaEnvironment.isSubtypeOf(expressionType, contextType,
+          SubtypeCheckMode.ignoringNullabilities)) {
         return true;
       }
     }
@@ -4054,6 +4118,9 @@
 
   /// Unassignable, but needs a tearoff of "call" for better error reporting.
   unassignableTearoff,
+
+  /// Unassignable because the tear-off can't be done on the nullable receiver.
+  unassignableCantTearoff,
 }
 
 /// Convenient way to return both a tear-off expression and its type.
diff --git a/pkg/front_end/lib/src/testing/id_testing_helper.dart b/pkg/front_end/lib/src/testing/id_testing_helper.dart
index 5b58808..0b35379 100644
--- a/pkg/front_end/lib/src/testing/id_testing_helper.dart
+++ b/pkg/front_end/lib/src/testing/id_testing_helper.dart
@@ -42,9 +42,14 @@
   final String name;
   final Map<ExperimentalFlag, bool> experimentalFlags;
   final Uri librariesSpecificationUri;
+  // TODO(johnniwinther): Tailor support to redefine selected platform
+  // classes/members only.
+  final bool compileSdk;
 
   const TestConfig(this.marker, this.name,
-      {this.experimentalFlags = const {}, this.librariesSpecificationUri});
+      {this.experimentalFlags = const {},
+      this.librariesSpecificationUri,
+      this.compileSdk: false});
 
   void customizeCompilerOptions(CompilerOptions options) {}
 }
@@ -273,6 +278,7 @@
         testData.memorySourceFiles.keys.map(createUriForFileName).toSet();
     if (testFiles.contains(config.librariesSpecificationUri)) {
       options.librariesSpecificationUri = config.librariesSpecificationUri;
+      options.compileSdk = config.compileSdk;
     }
   }
   config.customizeCompilerOptions(options);
diff --git a/pkg/front_end/messages.status b/pkg/front_end/messages.status
index b5e8ccf..e7fbe16 100644
--- a/pkg/front_end/messages.status
+++ b/pkg/front_end/messages.status
@@ -387,6 +387,8 @@
 InvalidVoid/part_wrapped_script2: Fail
 InvalidVoid/script1: Fail
 InvalidVoid/script2: Fail
+JsInteropIndexNotSupported/analyzerCode: Fail # Web compiler specific
+JsInteropIndexNotSupported/example: Fail # Web compiler specific
 LanguageVersionInvalidInDotPackages/analyzerCode: Fail
 LanguageVersionInvalidInDotPackages/part_wrapped_script: Fail # Importing file in the (now) part.
 LanguageVersionMismatchInPart/analyzerCode: Fail
@@ -485,6 +487,10 @@
 NullableSuperclassError/example: Fail
 NullableSuperclassWarning/analyzerCode: Fail
 NullableSuperclassWarning/example: Fail
+NullableTearoffError/analyzerCode: Fail
+NullableTearoffError/example: Fail
+NullableTearoffWarning/analyzerCode: Fail
+NullableTearoffWarning/example: Fail
 OperatorMinusParameterMismatch/example: Fail
 OperatorParameterMismatch0/analyzerCode: Fail
 OperatorParameterMismatch0/example: Fail
diff --git a/pkg/front_end/messages.yaml b/pkg/front_end/messages.yaml
index 48c9bee..1ff32f8 100644
--- a/pkg/front_end/messages.yaml
+++ b/pkg/front_end/messages.yaml
@@ -2131,6 +2131,13 @@
 OperatorWithOptionalFormals:
   template: "An operator can't have optional parameters."
 
+OperatorWithTypeParameters:
+  template: "Types parameters aren't allowed when defining an operator."
+  tip: "Try removing the type parameters."
+  analyzerCode: TYPE_PARAMETER_ON_OPERATOR
+  script:
+    - "class C { operator []<T>(T t) => null; }"
+
 PlatformPrivateLibraryAccess:
   template: "Can't access platform private library."
   analyzerCode: IMPORT_INTERNAL_LIBRARY
@@ -3791,6 +3798,13 @@
   template: "Operator '#name' is called on '#type' which is potentially null."
   severity: WARNING
 
+NullableTearoffError:
+  template: "Can't tear off method '#name' from a potentially null value."
+
+NullableTearoffWarning:
+  template: "Tearing off method '#name' from a potentially null value."
+  severity: WARNING
+
 ThrowingNotAssignableToObjectError:
   template: "Can't throw a value of '#type' since it is neither dynamic nor non-nullable."
 
@@ -3850,3 +3864,7 @@
 NullableMixinWarning:
   template: "Mixing in '#name' marked with '?'."
   severity: WARNING
+
+JsInteropIndexNotSupported:
+  template: "JS interop classes do not support [] and []= operator methods."
+  tip: "Try replacing with a normal method."
diff --git a/pkg/front_end/test/fasta/testing/suite.dart b/pkg/front_end/test/fasta/testing/suite.dart
index 0e54fb3..84f0b1c 100644
--- a/pkg/front_end/test/fasta/testing/suite.dart
+++ b/pkg/front_end/test/fasta/testing/suite.dart
@@ -29,7 +29,7 @@
     show StandardFileSystem;
 
 import 'package:front_end/src/base/libraries_specification.dart'
-    show TargetLibrariesSpecification;
+    show LibraryInfo;
 
 import 'package:front_end/src/base/processed_options.dart'
     show ProcessedOptions;
@@ -67,6 +67,9 @@
 
 import 'package:kernel/reference_from_index.dart' show ReferenceFromIndex;
 
+import 'package:kernel/target/changed_structure_notifier.dart'
+    show ChangedStructureNotifier;
+
 import 'package:kernel/target/targets.dart'
     show TargetFlags, DiagnosticReporter;
 
@@ -85,6 +88,7 @@
 
 import '../../utils/kernel_chain.dart'
     show
+        ComponentResult,
         KernelTextSerialization,
         MatchContext,
         MatchExpectation,
@@ -149,7 +153,7 @@
   final bool forceNnbdChecks;
 
   TestOptions(this.experimentalFlags,
-      {this.forceLateLowering, this.forceNnbdChecks})
+      {this.forceLateLowering: false, this.forceNnbdChecks: false})
       : assert(forceLateLowering != null),
         assert(forceNnbdChecks != null);
 
@@ -170,7 +174,7 @@
 }
 
 class FastaContext extends ChainContext with MatchContext {
-  final UriTranslator uriTranslator;
+  final Uri baseUri;
   final List<Step> steps;
   final Uri vm;
   final bool onlyCrashes;
@@ -183,8 +187,10 @@
   final Map<Component, StringBuffer> componentToDiagnostics =
       <Component, StringBuffer>{};
   final Uri platformBinaries;
+  final Map<Uri, UriTranslator> _uriTranslators = {};
   final Map<Uri, TestOptions> _testOptions = {};
   final Map<Uri, LinkDependenciesOptions> _linkDependencies = {};
+  final Map<Uri, Uri> _librariesJson = {};
 
   @override
   final bool updateExpectations;
@@ -198,6 +204,7 @@
   Component platform;
 
   FastaContext(
+      this.baseUri,
       this.vm,
       this.platformBinaries,
       this.onlyCrashes,
@@ -207,7 +214,6 @@
       bool updateComments,
       this.skipVm,
       bool kernelTextSerialization,
-      this.uriTranslator,
       bool fullCompile,
       this.verify,
       this.weak)
@@ -264,45 +270,84 @@
     }
   }
 
+  TestOptions _computeTestOptionsForDirectory(Directory directory) {
+    TestOptions testOptions = _testOptions[directory.uri];
+    if (testOptions == null) {
+      if (directory.uri == baseUri) {
+        testOptions = new TestOptions({},
+            forceLateLowering: false, forceNnbdChecks: false);
+      } else {
+        File optionsFile =
+            new File.fromUri(directory.uri.resolve('test.options'));
+        if (optionsFile.existsSync()) {
+          bool forceLateLowering = false;
+          bool forceNnbdChecks = false;
+          List<String> experimentalFlagsArguments = [];
+          for (String line in optionsFile.readAsStringSync().split('\n')) {
+            line = line.trim();
+            if (line.startsWith(experimentalFlagOptions)) {
+              experimentalFlagsArguments =
+                  line.substring(experimentalFlagOptions.length).split('\n');
+            } else if (line.startsWith(Flags.forceLateLowering)) {
+              forceLateLowering = true;
+            } else if (line.startsWith(Flags.forceNnbdChecks)) {
+              forceNnbdChecks = true;
+            } else if (line.isNotEmpty) {
+              throw new UnsupportedError("Unsupported test option '$line'");
+            }
+          }
+
+          testOptions = new TestOptions(
+              parseExperimentalFlags(
+                  parseExperimentalArguments(experimentalFlagsArguments),
+                  onError: (String message) => throw new ArgumentError(message),
+                  onWarning: (String message) =>
+                      throw new ArgumentError(message)),
+              forceLateLowering: forceLateLowering,
+              forceNnbdChecks: forceNnbdChecks);
+        } else {
+          testOptions = _computeTestOptionsForDirectory(directory.parent);
+        }
+      }
+      _testOptions[directory.uri] = testOptions;
+    }
+    return testOptions;
+  }
+
   /// Computes the experimental flag for [description].
   ///
   /// [forcedExperimentalFlags] is used to override the default flags for
   /// [description].
   TestOptions computeTestOptions(TestDescription description) {
     Directory directory = new File.fromUri(description.uri).parent;
-    // TODO(johnniwinther): Support nested test folders?
-    TestOptions testOptions = _testOptions[directory.uri];
-    if (testOptions == null) {
-      bool forceLateLowering = false;
-      bool forceNnbdChecks = false;
-      List<String> experimentalFlagsArguments = [];
-      File optionsFile =
-          new File.fromUri(directory.uri.resolve('test.options'));
-      if (optionsFile.existsSync()) {
-        for (String line in optionsFile.readAsStringSync().split('\n')) {
-          line = line.trim();
-          if (line.startsWith(experimentalFlagOptions)) {
-            experimentalFlagsArguments =
-                line.substring(experimentalFlagOptions.length).split('\n');
-          } else if (line.startsWith(Flags.forceLateLowering)) {
-            forceLateLowering = true;
-          } else if (line.startsWith(Flags.forceNnbdChecks)) {
-            forceNnbdChecks = true;
-          } else if (line.isNotEmpty) {
-            throw new UnsupportedError("Unsupported test option '$line'");
-          }
-        }
-      }
-      testOptions = new TestOptions(
-          parseExperimentalFlags(
-              parseExperimentalArguments(experimentalFlagsArguments),
-              onError: (String message) => throw new ArgumentError(message),
-              onWarning: (String message) => throw new ArgumentError(message)),
-          forceLateLowering: forceLateLowering,
-          forceNnbdChecks: forceNnbdChecks);
-      _testOptions[directory.uri] = testOptions;
+    return _computeTestOptionsForDirectory(directory);
+  }
+
+  Future<UriTranslator> computeUriTranslator(
+      TestDescription description) async {
+    Uri librariesSpecificationUri =
+        computeLibrariesSpecificationUri(description);
+    UriTranslator uriTranslator = _uriTranslators[librariesSpecificationUri];
+    if (uriTranslator == null) {
+      Uri sdk = Uri.base.resolve("sdk/");
+      Uri packages = Uri.base.resolve(".packages");
+      TestOptions testOptions = computeTestOptions(description);
+      ProcessedOptions options = new ProcessedOptions(
+          options: new CompilerOptions()
+            ..onDiagnostic = (DiagnosticMessage message) {
+              throw message.plainTextFormatted.join("\n");
+            }
+            ..sdkRoot = sdk
+            ..packagesFileUri = packages
+            ..environmentDefines = {}
+            ..experimentalFlags =
+                testOptions.computeExperimentalFlags(experimentalFlags)
+            ..nnbdStrongMode = !weak
+            ..librariesSpecificationUri = librariesSpecificationUri);
+      uriTranslator = await options.getUriTranslator();
+      _uriTranslators[librariesSpecificationUri] = uriTranslator;
     }
-    return testOptions;
+    return uriTranslator;
   }
 
   /// Computes the link dependencies for [description].
@@ -332,6 +377,21 @@
     return linkDependenciesOptions;
   }
 
+  /// Libraries json for [description].
+  Uri computeLibrariesSpecificationUri(TestDescription description) {
+    Directory directory = new File.fromUri(description.uri).parent;
+    if (_librariesJson.containsKey(directory.uri)) {
+      return _librariesJson[directory.uri];
+    } else {
+      Uri librariesJson;
+      File jsonFile = new File.fromUri(directory.uri.resolve('libraries.json'));
+      if (jsonFile.existsSync()) {
+        librariesJson = jsonFile.uri;
+      }
+      return _librariesJson[directory.uri] = librariesJson;
+    }
+  }
+
   Expectation get verificationError => expectationSet["VerificationError"];
 
   Future ensurePlatformUris() async {
@@ -374,9 +434,7 @@
 
   static Future<FastaContext> create(
       Chain suite, Map<String, String> environment) async {
-    Uri sdk = Uri.base.resolve("sdk/");
     Uri vm = Uri.base.resolveUri(new Uri.file(Platform.resolvedExecutable));
-    Uri packages = Uri.base.resolve(".packages");
     Map<ExperimentalFlag, bool> experimentalFlags = <ExperimentalFlag, bool>{};
 
     void addForcedExperimentalFlag(String name, ExperimentalFlag flag) {
@@ -391,17 +449,6 @@
         "enableNonNullable", ExperimentalFlag.nonNullable);
 
     bool weak = environment["weak"] == "true";
-    var options = new ProcessedOptions(
-        options: new CompilerOptions()
-          ..onDiagnostic = (DiagnosticMessage message) {
-            throw message.plainTextFormatted.join("\n");
-          }
-          ..sdkRoot = sdk
-          ..packagesFileUri = packages
-          ..environmentDefines = {}
-          ..experimentalFlags = experimentalFlags
-          ..nnbdStrongMode = !weak);
-    UriTranslator uriTranslator = await options.getUriTranslator();
     bool onlyCrashes = environment["onlyCrashes"] == "true";
     bool ignoreExpectations = environment["ignoreExpectations"] == "true";
     bool updateExpectations = environment["updateExpectations"] == "true";
@@ -415,6 +462,7 @@
       platformBinaries = '$platformBinaries/';
     }
     return new FastaContext(
+        suite.uri,
         vm,
         platformBinaries == null
             ? computePlatformBinariesLocation(forceBuildDir: true)
@@ -426,7 +474,6 @@
         updateComments,
         skipVm,
         kernelTextSerialization,
-        uriTranslator,
         environment.containsKey(ENABLE_FULL_COMPILE),
         verify,
         weak);
@@ -460,7 +507,7 @@
   }
 }
 
-class Outline extends Step<TestDescription, Component, FastaContext> {
+class Outline extends Step<TestDescription, ComponentResult, FastaContext> {
   final bool fullCompile;
 
   const Outline(this.fullCompile, {this.updateComments: false});
@@ -473,9 +520,12 @@
 
   bool get isCompiler => fullCompile;
 
-  Future<Result<Component>> run(
+  Future<Result<ComponentResult>> run(
       TestDescription description, FastaContext context) async {
     StringBuffer errors = new StringBuffer();
+
+    Uri librariesSpecificationUri =
+        context.computeLibrariesSpecificationUri(description);
     LinkDependenciesOptions linkDependenciesOptions =
         context.computeLinkDependenciesOptions(description);
     TestOptions testOptions = context.computeTestOptions(description);
@@ -491,7 +541,8 @@
           ..experimentalFlags =
               testOptions.computeExperimentalFlags(context.experimentalFlags)
           ..performNnbdChecks = testOptions.forceNnbdChecks
-          ..nnbdStrongMode = !context.weak,
+          ..nnbdStrongMode = !context.weak
+          ..librariesSpecificationUri = librariesSpecificationUri,
         inputs: <Uri>[description.uri]);
 
     // Disable colors to ensure that expectation files are the same across
@@ -502,8 +553,8 @@
         linkDependenciesOptions.component == null) {
       // Compile linked dependency.
       await CompilerContext.runWithOptions(options, (_) async {
-        KernelTarget sourceTarget = await outlineInitialization(
-            context, testOptions, linkDependenciesOptions.content.toList());
+        KernelTarget sourceTarget = await outlineInitialization(context,
+            description, testOptions, linkDependenciesOptions.content.toList());
         if (linkDependenciesOptions.errors != null) {
           errors.write(linkDependenciesOptions.errors);
         }
@@ -527,7 +578,7 @@
 
     return await CompilerContext.runWithOptions(options, (_) async {
       KernelTarget sourceTarget = await outlineInitialization(
-          context, testOptions, <Uri>[description.uri],
+          context, description, testOptions, <Uri>[description.uri],
           alsoAppend: linkDependenciesOptions.component);
       ValidatingInstrumentation instrumentation =
           new ValidatingInstrumentation();
@@ -538,6 +589,17 @@
       context.componentToTarget[p] = sourceTarget;
       context.componentToDiagnostics.clear();
       context.componentToDiagnostics[p] = errors;
+      Set<Uri> userLibraries = p.libraries
+          .where((Library library) =>
+              library.importUri.scheme != 'dart' &&
+              library.importUri.scheme != 'package')
+          .map((Library library) => library.importUri)
+          .toSet();
+      // Mark custom dart: libraries defined in the test-specific libraries.json
+      // file as user libraries.
+      UriTranslator uriTranslator = sourceTarget.uriTranslator;
+      userLibraries.addAll(uriTranslator.dartLibraries.allLibraries
+          .map((LibraryInfo info) => info.importUri));
       if (fullCompile) {
         p = await sourceTarget.buildComponent(verify: context.verify);
         instrumentation.finish();
@@ -545,26 +607,31 @@
           if (updateComments) {
             await instrumentation.fixSource(description.uri, false);
           } else {
-            return new Result<Component>(
-                p,
+            return new Result<ComponentResult>(
+                new ComponentResult(p, userLibraries),
                 context.expectationSet["InstrumentationMismatch"],
                 instrumentation.problemsAsString,
                 null);
           }
         }
       }
-      return pass(p);
+      return pass(new ComponentResult(p, userLibraries));
     });
   }
 
   Future<KernelTarget> outlineInitialization(
-      FastaContext context, TestOptions testOptions, List<Uri> entryPoints,
+      FastaContext context,
+      TestDescription description,
+      TestOptions testOptions,
+      List<Uri> entryPoints,
       {Component alsoAppend}) async {
     Component platform = await context.loadPlatform();
     Ticker ticker = new Ticker();
+    UriTranslator uriTranslator =
+        await context.computeUriTranslator(description);
     DillTarget dillTarget = new DillTarget(
       ticker,
-      context.uriTranslator,
+      uriTranslator,
       new TestVmTarget(new TargetFlags(
           forceLateLoweringForTesting: testOptions.forceLateLowering)),
     );
@@ -572,11 +639,6 @@
     if (alsoAppend != null) {
       dillTarget.loader.appendLibraries(alsoAppend);
     }
-    // We create a new URI translator to avoid reading platform libraries
-    // from file system.
-    UriTranslator uriTranslator = new UriTranslator(
-        const TargetLibrariesSpecification('vm'),
-        context.uriTranslator.packages);
     KernelTarget sourceTarget = new KernelTarget(
         StandardFileSystem.instance, false, dillTarget, uriTranslator);
 
@@ -586,13 +648,14 @@
   }
 }
 
-class Transform extends Step<Component, Component, FastaContext> {
+class Transform extends Step<ComponentResult, ComponentResult, FastaContext> {
   const Transform();
 
   String get name => "transform component";
 
-  Future<Result<Component>> run(
-      Component component, FastaContext context) async {
+  Future<Result<ComponentResult>> run(
+      ComponentResult result, FastaContext context) async {
+    Component component = result.component;
     KernelTarget sourceTarget = context.componentToTarget[component];
     context.componentToTarget.remove(component);
     TestVmTarget backendTarget = sourceTarget.backendTarget;
@@ -606,13 +669,13 @@
     }
     List<String> errors = VerifyTransformed.verify(component);
     if (errors.isNotEmpty) {
-      return new Result<Component>(
-          component,
+      return new Result<ComponentResult>(
+          result,
           context.expectationSet["TransformVerificationError"],
           errors.join('\n'),
           null);
     }
-    return pass(component);
+    return pass(result);
   }
 }
 
@@ -655,7 +718,8 @@
       Map<String, String> environmentDefines,
       DiagnosticReporter diagnosticReporter,
       ReferenceFromIndex referenceFromIndex,
-      {void logger(String msg)}) {
+      {void logger(String msg),
+      ChangedStructureNotifier changedStructureNotifier}) {
     if (enabled) {
       super.performModularTransformationsOnLibraries(
           component,
@@ -670,27 +734,30 @@
   }
 }
 
-class EnsureNoErrors extends Step<Component, Component, FastaContext> {
+class EnsureNoErrors
+    extends Step<ComponentResult, ComponentResult, FastaContext> {
   const EnsureNoErrors();
 
   String get name => "check errors";
 
-  Future<Result<Component>> run(
-      Component component, FastaContext context) async {
-    StringBuffer buffer = context.componentToDiagnostics[component];
+  Future<Result<ComponentResult>> run(
+      ComponentResult result, FastaContext context) async {
+    StringBuffer buffer = context.componentToDiagnostics[result.component];
     return buffer.isEmpty
-        ? pass(component)
-        : fail(component, """Unexpected errors:\n$buffer""");
+        ? pass(result)
+        : fail(result, """Unexpected errors:\n$buffer""");
   }
 }
 
-class MatchHierarchy extends Step<Component, Component, FastaContext> {
+class MatchHierarchy
+    extends Step<ComponentResult, ComponentResult, FastaContext> {
   const MatchHierarchy();
 
   String get name => "check hierarchy";
 
-  Future<Result<Component>> run(
-      Component component, FastaContext context) async {
+  Future<Result<ComponentResult>> run(
+      ComponentResult result, FastaContext context) async {
+    Component component = result.component;
     Uri uri =
         component.uriToSource.keys.firstWhere((uri) => uri?.scheme == "file");
     KernelTarget target = context.componentToTarget[component];
@@ -699,6 +766,7 @@
     for (ClassHierarchyNode node in hierarchy.nodes.values) {
       sb.writeln(node);
     }
-    return context.match<Component>(".hierarchy.expect", "$sb", uri, component);
+    return context.match<ComponentResult>(
+        ".hierarchy.expect", "$sb", uri, result);
   }
 }
diff --git a/pkg/front_end/test/id_tests/inheritance_test.dart b/pkg/front_end/test/id_tests/inheritance_test.dart
index f5534d1..542d5ab 100644
--- a/pkg/front_end/test/id_tests/inheritance_test.dart
+++ b/pkg/front_end/test/id_tests/inheritance_test.dart
@@ -15,10 +15,6 @@
 
 const String cfeFromBuilderMarker = 'cfe:builder';
 
-const TestConfig cfeFromBuilder = const TestConfig(
-    cfeFromBuilderMarker, 'cfe from builder',
-    experimentalFlags: const {ExperimentalFlag.nonNullable: true});
-
 main(List<String> args) async {
   Directory dataDir = new Directory.fromUri(Platform.script
       .resolve('../../../_fe_analyzer_shared/test/inheritance/data'));
@@ -27,8 +23,17 @@
       supportedMarkers: [cfeMarker, cfeFromBuilderMarker],
       createUriForFileName: createUriForFileName,
       onFailure: onFailure,
-      runTest: runTestFor(const InheritanceDataComputer(),
-          [cfeNonNullableOnlyConfig, cfeFromBuilder]));
+      runTest: runTestFor(const InheritanceDataComputer(), [
+        new TestConfig(cfeMarker, 'cfe with nnbd',
+            experimentalFlags: const {ExperimentalFlag.nonNullable: true},
+            librariesSpecificationUri: createUriForFileName('libraries.json'),
+            compileSdk: true),
+        new TestConfig(
+            cfeFromBuilderMarker, 'cfe from builder',
+            experimentalFlags: const {ExperimentalFlag.nonNullable: true},
+            librariesSpecificationUri: createUriForFileName('libraries.json'),
+            compileSdk: true)
+      ]));
 }
 
 class InheritanceDataComputer extends DataComputer<String> {
diff --git a/pkg/front_end/test/incremental_dart2js_tester.dart b/pkg/front_end/test/incremental_dart2js_tester.dart
index 086c390..0eb21c7 100644
--- a/pkg/front_end/test/incremental_dart2js_tester.dart
+++ b/pkg/front_end/test/incremental_dart2js_tester.dart
@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import "dart:developer";
 import 'dart:io' show Platform;
 
 import 'package:front_end/src/api_prototype/compiler_options.dart';
@@ -17,11 +18,14 @@
 main(List<String> args) async {
   bool fast = false;
   bool useExperimentalInvalidation = false;
+  bool addDebugBreaks = false;
   for (String arg in args) {
     if (arg == "--fast") {
       fast = true;
     } else if (arg == "--experimental") {
       useExperimentalInvalidation = true;
+    } else if (arg == "--addDebugBreaks") {
+      addDebugBreaks = true;
     } else {
       throw "Unsupported argument: $arg";
     }
@@ -158,6 +162,9 @@
         print("=====");
       }
     }
+    if (addDebugBreaks) {
+      debugger();
+    }
     print("-----");
   }
 
diff --git a/pkg/front_end/test/incremental_load_from_dill_suite.dart b/pkg/front_end/test/incremental_load_from_dill_suite.dart
index 0f7194b..79b25aa 100644
--- a/pkg/front_end/test/incremental_load_from_dill_suite.dart
+++ b/pkg/front_end/test/incremental_load_from_dill_suite.dart
@@ -40,12 +40,14 @@
 
 import 'package:front_end/src/fasta/incremental_serializer.dart'
     show IncrementalSerializer;
+import 'package:front_end/src/fasta/kernel/kernel_api.dart';
 
 import 'package:front_end/src/fasta/kernel/utils.dart' show ByteSink;
 
 import 'package:kernel/binary/ast_from_binary.dart' show BinaryBuilder;
 
 import 'package:kernel/binary/ast_to_binary.dart' show BinaryPrinter;
+import 'package:kernel/class_hierarchy.dart';
 
 import 'package:kernel/kernel.dart'
     show
@@ -55,6 +57,7 @@
         Field,
         Library,
         LibraryDependency,
+        Member,
         Name,
         Procedure;
 
@@ -608,25 +611,8 @@
       }
     }
 
-    Uri uri = data.loadedFrom
-        .resolve(data.loadedFrom.pathSegments.last + ".world.$worldNum.expect");
-    String expected;
-    File file = new File.fromUri(uri);
-    if (context.updateExpectations) {
-      file.writeAsStringSync(actualSerialized);
-    }
-    if (file.existsSync()) {
-      expected = file.readAsStringSync();
-    }
-    if (context.updateExpectations) {
-      file.writeAsStringSync(actualSerialized);
-    } else if (expected != actualSerialized) {
-      String extra = "";
-      if (expected == null) extra = "Expect file did not exist.\n";
-      throw "${extra}Unexpected serialized representation. "
-          "Fix or update $uri to contain the below:\n\n"
-          "$actualSerialized";
-    }
+    checkExpectFile(data, worldNum, context, actualSerialized);
+    checkClassHierarchy(compiler, component, data, worldNum, context);
 
     int nonSyntheticLibraries = countNonSyntheticLibraries(component);
     int nonSyntheticPlatformLibraries =
@@ -750,9 +736,31 @@
     }
 
     if (world["expressionCompilation"] != null) {
-      Uri uri = base.resolve(world["expressionCompilation"]["uri"]);
-      String expression = world["expressionCompilation"]["expression"];
-      await compiler.compileExpression(expression, {}, [], "debugExpr", uri);
+      List compilations;
+      if (world["expressionCompilation"] is List) {
+        compilations = world["expressionCompilation"];
+      } else {
+        compilations = [world["expressionCompilation"]];
+      }
+      for (Map compilation in compilations) {
+        clearPrevErrorsEtc();
+        bool expectErrors = compilation["errors"] ?? false;
+        bool expectWarnings = compilation["warnings"] ?? false;
+        Uri uri = base.resolve(compilation["uri"]);
+        String expression = compilation["expression"];
+        await compiler.compileExpression(expression, {}, [], "debugExpr", uri);
+        if (gotError && !expectErrors) {
+          throw "Got error(s) on expression compilation: ${formattedErrors}.";
+        } else if (!gotError && expectErrors) {
+          throw "Didn't get any errors.";
+        }
+        if (gotWarning && !expectWarnings) {
+          throw "Got warning(s) on expression compilation: "
+              "${formattedWarnings}.";
+        } else if (!gotWarning && expectWarnings) {
+          throw "Didn't get any warnings.";
+        }
+      }
     }
 
     if (!noFullComponent && incrementalSerialization == true) {
@@ -826,6 +834,166 @@
   }
 }
 
+void checkExpectFile(
+    TestData data, int worldNum, Context context, String actualSerialized) {
+  Uri uri = data.loadedFrom
+      .resolve(data.loadedFrom.pathSegments.last + ".world.$worldNum.expect");
+  String expected;
+  File file = new File.fromUri(uri);
+  if (file.existsSync()) {
+    expected = file.readAsStringSync();
+  }
+  if (expected != actualSerialized) {
+    if (context.updateExpectations) {
+      file.writeAsStringSync(actualSerialized);
+    } else {
+      String extra = "";
+      if (expected == null) extra = "Expect file did not exist.\n";
+      throw "${extra}Unexpected serialized representation. "
+          "Fix or update $uri to contain the below:\n\n"
+          "$actualSerialized";
+    }
+  }
+}
+
+/// Check that the class hierarchy is up-to-date with reality.
+///
+/// This has the option to do expect files, but it's disabled by default
+/// while we're trying to figure out if it's useful or not.
+void checkClassHierarchy(TestIncrementalCompiler compiler, Component component,
+    TestData data, int worldNum, Context context,
+    {bool checkExpectFile: false}) {
+  ClassHierarchy classHierarchy = compiler.getClassHierarchy();
+  if (classHierarchy is! ClosedWorldClassHierarchy) {
+    throw "Expected the class hierarchy to be ClosedWorldClassHierarchy "
+        "but it wasn't. It was ${classHierarchy.runtimeType}";
+  }
+  List<ForTestingClassInfo> classHierarchyData =
+      (classHierarchy as ClosedWorldClassHierarchy).getTestingClassInfo();
+  Map<Class, ForTestingClassInfo> classHierarchyMap =
+      new Map<Class, ForTestingClassInfo>();
+  for (ForTestingClassInfo info in classHierarchyData) {
+    if (classHierarchyMap[info.classNode] != null) {
+      throw "Two entries for ${info.classNode}";
+    }
+    classHierarchyMap[info.classNode] = info;
+  }
+
+  StringBuffer sb = new StringBuffer();
+  for (Library library in component.libraries) {
+    if (library.importUri.scheme == "dart") continue;
+    sb.writeln("Library ${library.importUri}");
+    for (Class c in library.classes) {
+      sb.writeln("  - Class ${c.name}");
+      ForTestingClassInfo info = classHierarchyMap[c];
+      if (info == null) {
+        throw "Didn't find any class hierarchy info for $c";
+      }
+      if (info.lazyDeclaredGettersAndCalls != null) {
+        sb.writeln("    - lazyDeclaredGettersAndCalls:");
+        for (Member member in info.lazyDeclaredGettersAndCalls) {
+          sb.writeln("      - ${member.name.name}");
+        }
+
+        // Expect these to be the same as in the class.
+        Set<Member> members = info.lazyDeclaredGettersAndCalls.toSet();
+        for (Field f in c.fields) {
+          if (f.isStatic) continue;
+          if (!f.hasImplicitGetter) continue;
+          if (!members.remove(f)) {
+            throw "Didn't find ${f.name.name} in lazyDeclaredGettersAndCalls "
+                "for ${c.name} in ${library.importUri}";
+          }
+        }
+        for (Procedure p in c.procedures) {
+          if (p.isStatic) continue;
+          if (p.isSetter) continue;
+          if (!members.remove(p)) {
+            throw "Didn't find ${p.name.name} in lazyDeclaredGettersAndCalls "
+                "for ${c.name} in ${library.importUri}";
+          }
+        }
+        if (members.isNotEmpty) {
+          throw "Still have ${members.map((m) => m.name.name)} left "
+              "for ${c.name} in ${library.importUri}";
+        }
+      }
+      if (info.lazyDeclaredSetters != null) {
+        sb.writeln("    - lazyDeclaredSetters:");
+        for (Member member in info.lazyDeclaredSetters) {
+          sb.writeln("      - ${member.name.name}");
+        }
+
+        // Expect these to be the same as in the class.
+        Set<Member> members = info.lazyDeclaredSetters.toSet();
+        for (Field f in c.fields) {
+          if (f.isStatic) continue;
+          if (!f.hasImplicitSetter) continue;
+          if (!members.remove(f)) {
+            throw "Didn't find $f in lazyDeclaredSetters for $c";
+          }
+        }
+        for (Procedure p in c.procedures) {
+          if (p.isStatic) continue;
+          if (!p.isSetter) continue;
+          if (!members.remove(p)) {
+            throw "Didn't find $p in lazyDeclaredSetters for $c";
+          }
+        }
+        if (members.isNotEmpty) {
+          throw "Still have ${members.map((m) => m.name.name)} left "
+              "for ${c.name} in ${library.importUri}";
+        }
+      }
+      if (info.lazyImplementedGettersAndCalls != null) {
+        sb.writeln("    - lazyImplementedGettersAndCalls:");
+        for (Member member in info.lazyImplementedGettersAndCalls) {
+          sb.writeln("      - ${member.name.name}");
+        }
+      }
+      if (info.lazyImplementedSetters != null) {
+        sb.writeln("    - lazyImplementedSetters:");
+        for (Member member in info.lazyImplementedSetters) {
+          sb.writeln("      - ${member.name.name}");
+        }
+      }
+      if (info.lazyInterfaceGettersAndCalls != null) {
+        sb.writeln("    - lazyInterfaceGettersAndCalls:");
+        for (Member member in info.lazyInterfaceGettersAndCalls) {
+          sb.writeln("      - ${member.name.name}");
+        }
+      }
+      if (info.lazyInterfaceSetters != null) {
+        sb.writeln("    - lazyInterfaceSetters:");
+        for (Member member in info.lazyInterfaceSetters) {
+          sb.writeln("      - ${member.name.name}");
+        }
+      }
+    }
+  }
+  if (checkExpectFile) {
+    String actualClassHierarchy = sb.toString();
+    Uri uri = data.loadedFrom.resolve(data.loadedFrom.pathSegments.last +
+        ".world.$worldNum.class_hierarchy.expect");
+    String expected;
+    File file = new File.fromUri(uri);
+    if (file.existsSync()) {
+      expected = file.readAsStringSync();
+    }
+    if (expected != actualClassHierarchy) {
+      if (context.updateExpectations) {
+        file.writeAsStringSync(actualClassHierarchy);
+      } else {
+        String extra = "";
+        if (expected == null) extra = "Expect file did not exist.\n";
+        throw "${extra}Unexpected serialized representation. "
+            "Fix or update $uri to contain the below:\n\n"
+            "$actualClassHierarchy";
+      }
+    }
+  }
+}
+
 void checkErrorsAndWarnings(
     Set<String> prevFormattedErrors,
     Set<String> formattedErrors,
@@ -877,14 +1045,14 @@
       throw "Incremental serialization didn't remove any libraries!";
     }
     if (librariesAfter < librariesBefore && sink.builder.isEmpty) {
-      throw "Incremental serialization din't output any bytes, "
+      throw "Incremental serialization didn't output any bytes, "
           "but did remove libraries";
     } else if (librariesAfter == librariesBefore && !sink.builder.isEmpty) {
       throw "Incremental serialization did output bytes, "
           "but didn't remove libraries";
     }
     if (librariesAfter < librariesBefore) {
-      // If we actually did incremenally serialize anything, check the output!
+      // If we actually did incrementally serialize anything, check the output!
       BinaryPrinter printer = new BinaryPrinter(sink);
       printer.writeComponentFile(c);
       List<int> bytes = sink.builder.takeBytes();
@@ -1367,10 +1535,10 @@
 void doSimulateTransformer(Component c) {
   for (Library lib in c.libraries) {
     if (lib.fields
-        .where((f) => f.name.name == "lalala_SimulateTransformer")
+        .where((f) => f.name.name == "unique_SimulateTransformer")
         .toList()
         .isNotEmpty) continue;
-    Name fieldName = new Name("lalala_SimulateTransformer");
+    Name fieldName = new Name("unique_SimulateTransformer");
     Field field = new Field(fieldName,
         isFinal: true,
         reference: lib.reference.canonicalName
@@ -1379,10 +1547,10 @@
     lib.addMember(field);
     for (Class c in lib.classes) {
       if (c.fields
-          .where((f) => f.name.name == "lalala_SimulateTransformer")
+          .where((f) => f.name.name == "unique_SimulateTransformer")
           .toList()
           .isNotEmpty) continue;
-      fieldName = new Name("lalala_SimulateTransformer");
+      fieldName = new Name("unique_SimulateTransformer");
       field = new Field(fieldName,
           isFinal: true,
           reference: c.reference.canonicalName
diff --git a/pkg/front_end/test/spell_checking_list_code.txt b/pkg/front_end/test/spell_checking_list_code.txt
index 5796688..9cad39e 100644
--- a/pkg/front_end/test/spell_checking_list_code.txt
+++ b/pkg/front_end/test/spell_checking_list_code.txt
@@ -64,6 +64,7 @@
 atoms
 attributes
 automagically
+auxiliary
 awaiting
 b
 b0i
@@ -357,6 +358,7 @@
 fcov
 fe
 feff
+fetched
 ff
 fff
 ffff
@@ -422,6 +424,7 @@
 gzipped
 h
 hadn't
+hang
 harness
 hashes
 hashing
@@ -606,6 +609,7 @@
 mm
 mn
 mockito
+momentarily
 monomorphic
 morebottom
 moretop
@@ -634,10 +638,14 @@
 nnbd
 node's
 nonimplementation
+normalization
+notifier
+notifying
 notion
 nr
 ns
 nsm
+nt
 nth
 nullabilities
 nullability
@@ -796,6 +804,7 @@
 recursion
 red
 redeclared
+redefine
 redirectee
 redirector
 reexports
@@ -966,11 +975,13 @@
 swapped
 sweep
 synchronously
+syncs
 synth
 t
 tagged
 tagger
 tags
+tailor
 taking
 talks
 tb
diff --git a/pkg/front_end/test/spell_checking_list_common.txt b/pkg/front_end/test/spell_checking_list_common.txt
index 25c78da..26cf233 100644
--- a/pkg/front_end/test/spell_checking_list_common.txt
+++ b/pkg/front_end/test/spell_checking_list_common.txt
@@ -1380,6 +1380,7 @@
 improve
 improved
 in
+inability
 inappropriate
 inbound
 include
@@ -2662,6 +2663,7 @@
 sorts
 sought
 sound
+soundness
 source
 sources
 space
@@ -2842,6 +2844,8 @@
 targeting
 targets
 task
+tear
+tearing
 technically
 technique
 template
diff --git a/pkg/front_end/test/spell_checking_list_messages.txt b/pkg/front_end/test/spell_checking_list_messages.txt
index 888bc3d..31322a38 100644
--- a/pkg/front_end/test/spell_checking_list_messages.txt
+++ b/pkg/front_end/test/spell_checking_list_messages.txt
@@ -30,8 +30,10 @@
 flutter_runner
 futureor
 h
+interop
 libraries.json
 loadlibrary
+JS
 name.#name
 name.stack
 native('native
diff --git a/pkg/front_end/test/spell_checking_list_tests.txt b/pkg/front_end/test/spell_checking_list_tests.txt
index 8a63992..468adfa 100644
--- a/pkg/front_end/test/spell_checking_list_tests.txt
+++ b/pkg/front_end/test/spell_checking_list_tests.txt
@@ -57,6 +57,7 @@
 bootstrap
 bots
 bowtie
+brand
 brave
 brown
 builddir
@@ -111,6 +112,7 @@
 dashes
 day
 db
+debugger
 decrease
 decrements
 def
@@ -190,6 +192,7 @@
 futures
 gallery
 gamma
+gave
 gc
 gen
 generators
@@ -201,6 +204,7 @@
 gunk
 hackish
 harness
+helper2
 hest
 heuristics
 hi
@@ -276,6 +280,8 @@
 mx
 mysdk
 negatable
+newest
+newworld
 ninja
 nonexisting
 noo
@@ -359,6 +365,8 @@
 shortest
 shot
 signalled
+slight
+smoke
 somehow
 spans
 spell
@@ -398,6 +406,7 @@
 title
 tpt
 transitively
+translators
 triangle
 trigger
 triggers
@@ -434,6 +443,7 @@
 whitelisting
 wins
 workflow
+worlds
 ws
 x's
 xxx
diff --git a/pkg/front_end/test/utils/kernel_chain.dart b/pkg/front_end/test/utils/kernel_chain.dart
index b6de873..da0ab76 100644
--- a/pkg/front_end/test/utils/kernel_chain.dart
+++ b/pkg/front_end/test/utils/kernel_chain.dart
@@ -125,39 +125,41 @@
   }
 }
 
-class Print extends Step<Component, Component, ChainContext> {
+class Print extends Step<ComponentResult, ComponentResult, ChainContext> {
   const Print();
 
   String get name => "print";
 
-  Future<Result<Component>> run(Component component, _) async {
+  Future<Result<ComponentResult>> run(ComponentResult result, _) async {
+    Component component = result.component;
+
     StringBuffer sb = new StringBuffer();
     await CompilerContext.runWithDefaultOptions((compilerContext) async {
       compilerContext.uriToSource.addAll(component.uriToSource);
 
       Printer printer = new Printer(sb);
       for (Library library in component.libraries) {
-        if (library.importUri.scheme != "dart" &&
-            library.importUri.scheme != "package") {
+        if (result.userLibraries.contains(library.importUri)) {
           printer.writeLibraryFile(library);
         }
       }
       printer.writeConstantTable(component);
     });
     print("$sb");
-    return pass(component);
+    return pass(result);
   }
 }
 
-class Verify extends Step<Component, Component, ChainContext> {
+class Verify extends Step<ComponentResult, ComponentResult, ChainContext> {
   final bool fullCompile;
 
   const Verify(this.fullCompile);
 
   String get name => "verify";
 
-  Future<Result<Component>> run(
-      Component component, ChainContext context) async {
+  Future<Result<ComponentResult>> run(
+      ComponentResult result, ChainContext context) async {
+    Component component = result.component;
     StringBuffer messages = new StringBuffer();
     ProcessedOptions options = new ProcessedOptions(
         options: new CompilerOptions()
@@ -174,32 +176,33 @@
           isOutline: !fullCompile, skipPlatform: true);
       assert(verificationErrors.isEmpty || messages.isNotEmpty);
       if (messages.isEmpty) {
-        return pass(component);
+        return pass(result);
       } else {
-        return new Result<Component>(null,
+        return new Result<ComponentResult>(null,
             context.expectationSet["VerificationError"], "$messages", null);
       }
     }, errorOnMissingInput: false);
   }
 }
 
-class TypeCheck extends Step<Component, Component, ChainContext> {
+class TypeCheck extends Step<ComponentResult, ComponentResult, ChainContext> {
   const TypeCheck();
 
   String get name => "typeCheck";
 
-  Future<Result<Component>> run(
-      Component component, ChainContext context) async {
+  Future<Result<ComponentResult>> run(
+      ComponentResult result, ChainContext context) async {
+    Component component = result.component;
     ErrorFormatter errorFormatter = new ErrorFormatter();
     NaiveTypeChecker checker =
         new NaiveTypeChecker(errorFormatter, component, ignoreSdk: true);
     checker.checkComponent(component);
     if (errorFormatter.numberOfFailures == 0) {
-      return pass(component);
+      return pass(result);
     } else {
       errorFormatter.failures.forEach(print);
       print('------- Found ${errorFormatter.numberOfFailures} errors -------');
-      return new Result<Component>(
+      return new Result<ComponentResult>(
           null,
           context.expectationSet["TypeCheckError"],
           '${errorFormatter.numberOfFailures} type errors',
@@ -208,7 +211,8 @@
   }
 }
 
-class MatchExpectation extends Step<Component, Component, MatchContext> {
+class MatchExpectation
+    extends Step<ComponentResult, ComponentResult, MatchContext> {
   final String suffix;
   final bool serializeFirst;
 
@@ -220,19 +224,19 @@
 
   String get name => "match expectations";
 
-  Future<Result<Component>> run(Component component, MatchContext context) {
+  Future<Result<ComponentResult>> run(
+      ComponentResult result, MatchContext context) {
+    Component component = result.component;
+
     Component componentToText = component;
     if (serializeFirst) {
       component.computeCanonicalNames();
-      List<Library> sdkLibraries = component.libraries
-          .where((l) => l.importUri.scheme == "dart")
-          .toList();
+      List<Library> sdkLibraries =
+          component.libraries.where((l) => !result.isUserLibrary(l)).toList();
 
       ByteSink sink = new ByteSink();
       Component writeMe = new Component(
-          libraries: component.libraries
-              .where((l) => l.importUri.scheme != "dart")
-              .toList());
+          libraries: component.libraries.where(result.isUserLibrary).toList());
       writeMe.uriToSource.addAll(component.uriToSource);
       if (component.problemsAsJson != null) {
         writeMe.problemsAsJson =
@@ -252,10 +256,8 @@
         (context as dynamic).componentToDiagnostics[component];
     Uri uri =
         component.uriToSource.keys.firstWhere((uri) => uri?.scheme == "file");
-    Iterable<Library> libraries = componentToText.libraries.where(
-        ((Library library) =>
-            library.importUri.scheme != "dart" &&
-            library.importUri.scheme != "package"));
+    Iterable<Library> libraries =
+        componentToText.libraries.where(result.isUserLibrary);
     Uri base = uri.resolve(".");
     Uri dartBase = Uri.base;
     StringBuffer buffer = new StringBuffer();
@@ -281,20 +283,22 @@
     actual = actual.replaceAll("$base", "org-dartlang-testcase:///");
     actual = actual.replaceAll("$dartBase", "org-dartlang-testcase-sdk:///");
     actual = actual.replaceAll("\\n", "\n");
-    return context.match<Component>(suffix, actual, uri, component,
+    return context.match<ComponentResult>(suffix, actual, uri, result,
         onMismatch: serializeFirst
             ? context.expectationFileMismatchSerialized
             : context.expectationFileMismatch);
   }
 }
 
-class KernelTextSerialization extends Step<Component, Component, ChainContext> {
+class KernelTextSerialization
+    extends Step<ComponentResult, ComponentResult, ChainContext> {
   const KernelTextSerialization();
 
   String get name => "kernel text serialization";
 
-  Future<Result<Component>> run(
-      Component component, ChainContext context) async {
+  Future<Result<ComponentResult>> run(
+      ComponentResult result, ChainContext context) async {
+    Component component = result.component;
     StringBuffer messages = new StringBuffer();
     ProcessedOptions options = new ProcessedOptions(
         options: new CompilerOptions()
@@ -347,23 +351,24 @@
       }
 
       if (verifier.failures.isNotEmpty) {
-        return new Result<Component>(
+        return new Result<ComponentResult>(
             null,
             context.expectationSet["TextSerializationFailure"],
             "$messages",
             null);
       }
-      return pass(component);
+      return pass(result);
     });
   }
 }
 
-class WriteDill extends Step<Component, Uri, ChainContext> {
+class WriteDill extends Step<ComponentResult, Uri, ChainContext> {
   const WriteDill();
 
   String get name => "write .dill";
 
-  Future<Result<Uri>> run(Component component, _) async {
+  Future<Result<Uri>> run(ComponentResult result, _) async {
+    Component component = result.component;
     Directory tmp = await Directory.systemTemp.createTemp();
     Uri uri = tmp.uri.resolve("generated.dill");
     File generated = new File.fromUri(uri);
@@ -457,3 +462,14 @@
   }
   print("Wrote $uri");
 }
+
+class ComponentResult {
+  final Component component;
+  final Set<Uri> userLibraries;
+
+  ComponentResult(this.component, this.userLibraries);
+
+  bool isUserLibrary(Library library) {
+    return userLibraries.contains(library.importUri);
+  }
+}
diff --git a/pkg/front_end/test/vm_service_for_leak_detection.dart b/pkg/front_end/test/vm_service_for_leak_detection.dart
index c1819e2..7d3c6ba 100644
--- a/pkg/front_end/test/vm_service_for_leak_detection.dart
+++ b/pkg/front_end/test/vm_service_for_leak_detection.dart
@@ -14,6 +14,8 @@
           "package:front_end/src/fasta/source/source_extension_builder.dart"),
       "SourceExtensionBuilder",
       ["_extension"]));
+  interests.add(new helper.Interest(
+      Uri.parse("package:kernel/ast.dart"), "Library", ["fileUri"]));
   helper.VMServiceHeapHelper heapHelper = new helper.VMServiceHeapHelper(
       interests,
       [
@@ -25,15 +27,10 @@
         new helper.Interest(Uri.parse("package:kernel/ast.dart"), "Extension",
             ["name", "fileUri"]),
       ],
-      false);
+      true);
   heapHelper.start([
-    Platform.script.resolve("incremental_load_from_dill_suite.dart").toString(),
-    "-DaddDebugBreaks=true",
-    // "--",
-    // "incremental_load_from_dill/no_outline_change_34"
-    // "incremental_load_from_dill/no_outline_change_10"
-    "incremental_load_from_dill/deleting_file"
-    // "incremental_load_from_dill/no_outline_change_2"
-    // "incremental_load_from_dill/incremental_serialization_1"
+    Platform.script.resolve("incremental_dart2js_tester.dart").toString(),
+    "--fast",
+    "--addDebugBreaks",
   ]);
 }
diff --git a/pkg/front_end/test/vm_service_heap_helper.dart b/pkg/front_end/test/vm_service_heap_helper.dart
index 56cb578..b4a80f1 100644
--- a/pkg/front_end/test/vm_service_heap_helper.dart
+++ b/pkg/front_end/test/vm_service_heap_helper.dart
@@ -126,7 +126,6 @@
                 }
               }
               String sbToString = sb.toString();
-              print(sbToString);
               if (!seenPrints.add(sbToString)) {
                 duplicatePrints.add(sbToString);
               }
@@ -142,7 +141,8 @@
         print("This might be a memory leak!");
         print("");
         for (String s in duplicatePrints) {
-          print("$s");
+          int count = groupedByToString[s].length;
+          print("$s ($count)");
           print("");
         }
         print("======================================");
diff --git a/pkg/front_end/testcases/expression/class_static3.expression.yaml.expect b/pkg/front_end/testcases/expression/class_static3.expression.yaml.expect
index 65d8f24..b00f945 100644
--- a/pkg/front_end/testcases/expression/class_static3.expression.yaml.expect
+++ b/pkg/front_end/testcases/expression/class_static3.expression.yaml.expect
@@ -4,7 +4,7 @@
               ^^^^^^^^^
 }
 method /* from org-dartlang-debug:synthetic_debug_expression */ debugExpr() → dynamic
-  return #lib1::globalVar.{dart.core::num::+}(invalid-expression "org-dartlang-debug:synthetic_debug_expression:1:13: Error: Getter not found: 'staticVar'.\nglobalVar + staticVar + 5\n            ^^^^^^^^^" as{TypeError} dart.core::num*).{dart.core::num::+}(5);
+  return #lib1::globalVar.{dart.core::num::+}(invalid-expression "org-dartlang-debug:synthetic_debug_expression:1:13: Error: Getter not found: 'staticVar'.\nglobalVar + staticVar + 5\n            ^^^^^^^^^" as{TypeError,ForDynamic} dart.core::num*).{dart.core::num::+}(5);
 Errors: {
 }
 static method /* from org-dartlang-debug:synthetic_debug_expression */ debugExpr() → dynamic
diff --git a/pkg/front_end/testcases/expression/class_type_param_reference_arg.expression.yaml.expect b/pkg/front_end/testcases/expression/class_type_param_reference_arg.expression.yaml.expect
index 2cb613c..d89f1f9 100644
--- a/pkg/front_end/testcases/expression/class_type_param_reference_arg.expression.yaml.expect
+++ b/pkg/front_end/testcases/expression/class_type_param_reference_arg.expression.yaml.expect
@@ -1,4 +1,4 @@
 Errors: {
 }
 method /* from org-dartlang-debug:synthetic_debug_expression */ debugExpr(dynamic x) → dynamic
-  return main::id<main::A::T*>(x as{TypeError} main::A::T*);
+  return main::id<main::A::T*>(x as{TypeError,ForDynamic} main::A::T*);
diff --git a/pkg/front_end/testcases/expression/from_vm_cc_linked_hash_map.expression.yaml.expect b/pkg/front_end/testcases/expression/from_vm_cc_linked_hash_map.expression.yaml.expect
index 4436d62..7cde4b9 100644
--- a/pkg/front_end/testcases/expression/from_vm_cc_linked_hash_map.expression.yaml.expect
+++ b/pkg/front_end/testcases/expression/from_vm_cc_linked_hash_map.expression.yaml.expect
@@ -5,12 +5,12 @@
     if(!a._usedData.{dart.core::Object::==}(b._usedData) || !a._deletedKeys.{dart.core::Object::==}(b._deletedKeys) || !a._hashMask.{dart.core::Object::==}(b._hashMask) || !a._index.length.{dart.core::Object::==}(b._index.length) || !a._data.length.{dart.core::Object::==}(b._data.length)) {
       return false;
     }
-    for (dart.core::int* i = 0; i.{dart.core::num::<}(a._index.length as{TypeError} dart.core::num*); i = i.{dart.core::num::+}(1)) {
+    for (dart.core::int* i = 0; i.{dart.core::num::<}(a._index.length as{TypeError,ForDynamic} dart.core::num*); i = i.{dart.core::num::+}(1)) {
       if(!a._index.[](i).{dart.core::Object::==}(b._index.[](i))) {
         return false;
       }
     }
-    for (dart.core::int* i = 0; i.{dart.core::num::<}(a._data.length as{TypeError} dart.core::num*); i = i.{dart.core::num::+}(1)) {
+    for (dart.core::int* i = 0; i.{dart.core::num::<}(a._data.length as{TypeError,ForDynamic} dart.core::num*); i = i.{dart.core::num::+}(1)) {
       dynamic ad = a._data.[](i);
       dynamic bd = b._data.[](i);
       if(!dart.core::identical(ad, bd) && !(ad.{dart.core::Object::==}(a) && bd.{dart.core::Object::==}(b))) {
diff --git a/pkg/front_end/testcases/expression/type_param_shadow_arg.expression.yaml.expect b/pkg/front_end/testcases/expression/type_param_shadow_arg.expression.yaml.expect
index 5b54940..66d7a12 100644
--- a/pkg/front_end/testcases/expression/type_param_shadow_arg.expression.yaml.expect
+++ b/pkg/front_end/testcases/expression/type_param_shadow_arg.expression.yaml.expect
@@ -1,4 +1,4 @@
 Errors: {
 }
 method /* from org-dartlang-debug:synthetic_debug_expression */ debugExpr<T extends dynamic>(dynamic x) → dynamic
-  return main::id<main::A::debugExpr::T*>(x as{TypeError} main::A::debugExpr::T*);
+  return main::id<main::A::debugExpr::T*>(x as{TypeError,ForDynamic} main::A::debugExpr::T*);
diff --git a/pkg/front_end/testcases/extensions/compounds.dart.strong.expect b/pkg/front_end/testcases/extensions/compounds.dart.strong.expect
index 24d7f52..c2f32b4 100644
--- a/pkg/front_end/testcases/extensions/compounds.dart.strong.expect
+++ b/pkg/front_end/testcases/extensions/compounds.dart.strong.expect
@@ -474,7 +474,7 @@
   self::expect(n0, let final self::IntClass* #t372 = v in #t372.{core::Object::==}(null) ?{core::int*} null : self::IntClassExtension|get#property(#t372), v.{core::Object::==}(null));
 }
 static method expect(dynamic expected, dynamic actual, [dynamic expectNull = #C1]) → dynamic {
-  if(expectNull as{TypeError} core::bool*) {
+  if(expectNull as{TypeError,ForDynamic} core::bool*) {
     expected = null;
   }
   if(!expected.{core::Object::==}(actual)) {
diff --git a/pkg/front_end/testcases/extensions/compounds.dart.strong.transformed.expect b/pkg/front_end/testcases/extensions/compounds.dart.strong.transformed.expect
index 24d7f52..c2f32b4 100644
--- a/pkg/front_end/testcases/extensions/compounds.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/extensions/compounds.dart.strong.transformed.expect
@@ -474,7 +474,7 @@
   self::expect(n0, let final self::IntClass* #t372 = v in #t372.{core::Object::==}(null) ?{core::int*} null : self::IntClassExtension|get#property(#t372), v.{core::Object::==}(null));
 }
 static method expect(dynamic expected, dynamic actual, [dynamic expectNull = #C1]) → dynamic {
-  if(expectNull as{TypeError} core::bool*) {
+  if(expectNull as{TypeError,ForDynamic} core::bool*) {
     expected = null;
   }
   if(!expected.{core::Object::==}(actual)) {
diff --git a/pkg/front_end/testcases/extensions/extension_setter.dart.strong.expect b/pkg/front_end/testcases/extensions/extension_setter.dart.strong.expect
index bcdd19f..f4366a8 100644
--- a/pkg/front_end/testcases/extensions/extension_setter.dart.strong.expect
+++ b/pkg/front_end/testcases/extensions/extension_setter.dart.strong.expect
@@ -52,9 +52,9 @@
   return #this.{self::Class::field};
 static method Extension|set#setterWithClosure(final self::Class* #this, core::int* value) → void {
   function abs(dynamic value) → dynamic {
-    return value.<(0) as{TypeError} core::bool* ?{dynamic} value.unary-() : value;
+    return value.<(0) as{TypeError,ForDynamic} core::bool* ?{dynamic} value.unary-() : value;
   }
-  #this.{self::Class::field} = abs.call(value) as{TypeError} core::int*;
+  #this.{self::Class::field} = abs.call(value) as{TypeError,ForDynamic} core::int*;
 }
 static method Extension|testInternal(final self::Class* #this) → dynamic {
   self::expect(null, #this.{self::Class::field});
diff --git a/pkg/front_end/testcases/extensions/extension_setter.dart.strong.transformed.expect b/pkg/front_end/testcases/extensions/extension_setter.dart.strong.transformed.expect
index bcdd19f..f4366a8 100644
--- a/pkg/front_end/testcases/extensions/extension_setter.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/extensions/extension_setter.dart.strong.transformed.expect
@@ -52,9 +52,9 @@
   return #this.{self::Class::field};
 static method Extension|set#setterWithClosure(final self::Class* #this, core::int* value) → void {
   function abs(dynamic value) → dynamic {
-    return value.<(0) as{TypeError} core::bool* ?{dynamic} value.unary-() : value;
+    return value.<(0) as{TypeError,ForDynamic} core::bool* ?{dynamic} value.unary-() : value;
   }
-  #this.{self::Class::field} = abs.call(value) as{TypeError} core::int*;
+  #this.{self::Class::field} = abs.call(value) as{TypeError,ForDynamic} core::int*;
 }
 static method Extension|testInternal(final self::Class* #this) → dynamic {
   self::expect(null, #this.{self::Class::field});
diff --git a/pkg/front_end/testcases/extensions/missing_toplevel.dart.strong.expect b/pkg/front_end/testcases/extensions/missing_toplevel.dart.strong.expect
index 65f4bbd..b9ec15a 100644
--- a/pkg/front_end/testcases/extensions/missing_toplevel.dart.strong.expect
+++ b/pkg/front_end/testcases/extensions/missing_toplevel.dart.strong.expect
@@ -24,6 +24,6 @@
  - 'Class' is from 'pkg/front_end/testcases/extensions/missing_toplevel.dart'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'setter'.
 var missingGetter = c.setter += 42;
-                      ^^^^^^".+(42) as{TypeError} core::int* in let final void #t3 = self::Extension|set#setter(#t1, #t2) in #t2;
+                      ^^^^^^".+(42) as{TypeError,ForDynamic} core::int* in let final void #t3 = self::Extension|set#setter(#t1, #t2) in #t2;
 static method Extension|set#setter(final self::Class* #this, core::int* value) → void {}
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/extensions/missing_toplevel.dart.strong.transformed.expect b/pkg/front_end/testcases/extensions/missing_toplevel.dart.strong.transformed.expect
index d5c36de..355e22c 100644
--- a/pkg/front_end/testcases/extensions/missing_toplevel.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/extensions/missing_toplevel.dart.strong.transformed.expect
@@ -24,6 +24,6 @@
  - 'Class' is from 'pkg/front_end/testcases/extensions/missing_toplevel.dart'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'setter'.
 var missingGetter = c.setter += 42;
-                      ^^^^^^".+(42) as{TypeError} core::int* in let final void #t3 = self::Extension|set#setter(#t1, #t2) in #t2;
+                      ^^^^^^".+(42) as{TypeError,ForDynamic} core::int* in let final void #t3 = self::Extension|set#setter(#t1, #t2) in #t2;
 static method Extension|set#setter(final self::Class* #this, core::int* value) → void {}
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/general/DeltaBlue.dart.strong.expect b/pkg/front_end/testcases/general/DeltaBlue.dart.strong.expect
index 4a77a26..2a91755 100644
--- a/pkg/front_end/testcases/general/DeltaBlue.dart.strong.expect
+++ b/pkg/front_end/testcases/general/DeltaBlue.dart.strong.expect
@@ -52,22 +52,22 @@
     self::planner.{self::Planner::incrementalAdd}(this);
   }
   method satisfy(dynamic mark) → self::Constraint* {
-    this.{self::Constraint::chooseMethod}(mark as{TypeError} core::int*);
+    this.{self::Constraint::chooseMethod}(mark as{TypeError,ForDynamic} core::int*);
     if(!this.{self::Constraint::isSatisfied}()) {
       if(this.{self::Constraint::strength}.{core::Object::==}(#C22)) {
         core::print("Could not satisfy a required constraint!");
       }
       return null;
     }
-    this.{self::Constraint::markInputs}(mark as{TypeError} core::int*);
+    this.{self::Constraint::markInputs}(mark as{TypeError,ForDynamic} core::int*);
     self::Variable* out = this.{self::Constraint::output}();
     self::Constraint* overridden = out.{self::Variable::determinedBy};
     if(!overridden.{core::Object::==}(null))
       overridden.{self::Constraint::markUnsatisfied}();
     out.{self::Variable::determinedBy} = this;
-    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError} core::int*))
+    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError,ForDynamic} core::int*))
       core::print("Cycle encountered");
-    out.{self::Variable::mark} = mark as{TypeError} core::int*;
+    out.{self::Variable::mark} = mark as{TypeError,ForDynamic} core::int*;
     return overridden;
   }
   method destroyConstraint() → void {
diff --git a/pkg/front_end/testcases/general/DeltaBlue.dart.strong.transformed.expect b/pkg/front_end/testcases/general/DeltaBlue.dart.strong.transformed.expect
index 4a77a26..2a91755 100644
--- a/pkg/front_end/testcases/general/DeltaBlue.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/DeltaBlue.dart.strong.transformed.expect
@@ -52,22 +52,22 @@
     self::planner.{self::Planner::incrementalAdd}(this);
   }
   method satisfy(dynamic mark) → self::Constraint* {
-    this.{self::Constraint::chooseMethod}(mark as{TypeError} core::int*);
+    this.{self::Constraint::chooseMethod}(mark as{TypeError,ForDynamic} core::int*);
     if(!this.{self::Constraint::isSatisfied}()) {
       if(this.{self::Constraint::strength}.{core::Object::==}(#C22)) {
         core::print("Could not satisfy a required constraint!");
       }
       return null;
     }
-    this.{self::Constraint::markInputs}(mark as{TypeError} core::int*);
+    this.{self::Constraint::markInputs}(mark as{TypeError,ForDynamic} core::int*);
     self::Variable* out = this.{self::Constraint::output}();
     self::Constraint* overridden = out.{self::Variable::determinedBy};
     if(!overridden.{core::Object::==}(null))
       overridden.{self::Constraint::markUnsatisfied}();
     out.{self::Variable::determinedBy} = this;
-    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError} core::int*))
+    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError,ForDynamic} core::int*))
       core::print("Cycle encountered");
-    out.{self::Variable::mark} = mark as{TypeError} core::int*;
+    out.{self::Variable::mark} = mark as{TypeError,ForDynamic} core::int*;
     return overridden;
   }
   method destroyConstraint() → void {
diff --git a/pkg/front_end/testcases/general/abstract_members.dart.outline.expect b/pkg/front_end/testcases/general/abstract_members.dart.outline.expect
index acc5dad..841c0e0 100644
--- a/pkg/front_end/testcases/general/abstract_members.dart.outline.expect
+++ b/pkg/front_end/testcases/general/abstract_members.dart.outline.expect
@@ -186,7 +186,7 @@
   method cMethod() → dynamic
     ;
   no-such-method-forwarder get interfaceMethod1() → dynamic
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod1, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} dynamic;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod1, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder set property3(dynamic _) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#property3=, 2, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[_]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
   no-such-method-forwarder set interfaceMethod1(dynamic value) → void
@@ -202,7 +202,7 @@
   no-such-method-forwarder method interfaceMethod2() → void
     return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod2, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
   no-such-method-forwarder method abstractMethod() → dynamic
-    return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#abstractMethod, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} dynamic;
+    return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#abstractMethod, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder method interfaceMethod1() → void
     return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod1, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
   no-such-method-forwarder method interfaceMethod3() → void
@@ -226,7 +226,7 @@
     ;
   abstract method noSuchMethod(core::Invocation* _) → dynamic;
   no-such-method-forwarder get interfaceMethod1() → dynamic
-    return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod1, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} dynamic;
+    return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod1, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder set property3(dynamic _) → void
     return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#property3=, 2, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[_]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
   no-such-method-forwarder set interfaceMethod1(dynamic value) → void
diff --git a/pkg/front_end/testcases/general/abstract_members.dart.strong.expect b/pkg/front_end/testcases/general/abstract_members.dart.strong.expect
index ec953d2..3192669 100644
--- a/pkg/front_end/testcases/general/abstract_members.dart.strong.expect
+++ b/pkg/front_end/testcases/general/abstract_members.dart.strong.expect
@@ -182,7 +182,7 @@
   method bMethod() → dynamic {}
   method cMethod() → dynamic {}
   no-such-method-forwarder get interfaceMethod1() → dynamic
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder set property3(dynamic _) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[_]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder set interfaceMethod1(dynamic value) → void
@@ -199,7 +199,7 @@
   no-such-method-forwarder method interfaceMethod2() → void
     return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder method abstractMethod() → dynamic
-    return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C9, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C9, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder method interfaceMethod1() → void
     return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder method interfaceMethod3() → void
@@ -225,7 +225,7 @@
     ;
   abstract method noSuchMethod(core::Invocation* _) → dynamic;
   no-such-method-forwarder get interfaceMethod1() → dynamic
-    return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder set property3(dynamic _) → void
     return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[_]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder set interfaceMethod1(dynamic value) → void
diff --git a/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.outline.expect b/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.outline.expect
index 7200a65..f027a20 100644
--- a/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.outline.expect
+++ b/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.outline.expect
@@ -23,7 +23,7 @@
   synthetic constructor •() → self::D*
     ;
   no-such-method-forwarder method foo() → self::B*
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} self::B*;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} self::B*;
 }
 static method main() → dynamic
   ;
diff --git a/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.strong.expect b/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.strong.expect
index 8482063..df623b2 100644
--- a/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.strong.expect
+++ b/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.strong.expect
@@ -27,7 +27,7 @@
     : super self::C::•()
     ;
   no-such-method-forwarder method foo() → self::B*
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} self::B*;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} self::B*;
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.strong.transformed.expect b/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.strong.transformed.expect
index 8482063..df623b2 100644
--- a/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/abstract_overrides_concrete_with_no_such_method.dart.strong.transformed.expect
@@ -27,7 +27,7 @@
     : super self::C::•()
     ;
   no-such-method-forwarder method foo() → self::B*
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} self::B*;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} self::B*;
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/general/async_nested.dart.strong.expect b/pkg/front_end/testcases/general/async_nested.dart.strong.expect
index 5c3da0c..6916565 100644
--- a/pkg/front_end/testcases/general/async_nested.dart.strong.expect
+++ b/pkg/front_end/testcases/general/async_nested.dart.strong.expect
@@ -20,7 +20,7 @@
 static method main() → void async {
   core::String* expected = "1 2 3 4 5 6 7 8 9 10";
   self::Node* node = new self::Node::•("1", <self::Node*>[new self::Node::•("2", <self::Node*>[]), await asy::Future::value<self::Node*>(new self::Node::•("3", <self::Node*>[await asy::Future::value<self::Node*>(new self::Node::•("4", <self::Node*>[new self::Node::•("5", <self::Node*>[await asy::Future::value<self::Node*>(new self::Node::•("6", <self::Node*>[await asy::Future::value<self::Node*>(new self::Node::•("7", <self::Node*>[]))])), await asy::Future::value<self::Node*>(new self::Node::•("8", <self::Node*>[])), await asy::Future::value<self::Node*>(new self::Node::•("9", <self::Node*>[]))])]))])), await asy::Future::value<self::Node*>(new self::Node::•("10", <self::Node*>[]))]);
-  core::String* actual = node.{self::Node::toSimpleString}() as{TypeError} core::String*;
+  core::String* actual = node.{self::Node::toSimpleString}() as{TypeError,ForDynamic} core::String*;
   core::print(actual);
   if(!actual.{core::String::==}(expected)) {
     throw "Expected '${expected}' but got '${actual}'";
diff --git a/pkg/front_end/testcases/general/async_nested.dart.strong.transformed.expect b/pkg/front_end/testcases/general/async_nested.dart.strong.transformed.expect
index 27b7653..2fe75da 100644
--- a/pkg/front_end/testcases/general/async_nested.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/async_nested.dart.strong.transformed.expect
@@ -47,7 +47,7 @@
         :async_temporary_0 = _in::unsafeCast<self::Node*>(:result);
         [yield] let dynamic #t10 = asy::_awaitHelper(asy::Future::value<self::Node*>(new self::Node::•("10", <self::Node*>[])), :async_op_then, :async_op_error, :async_op) in null;
         self::Node* node = new self::Node::•("1", <self::Node*>[:async_temporary_2, :async_temporary_0, _in::unsafeCast<self::Node*>(:result)]);
-        core::String* actual = node.{self::Node::toSimpleString}() as{TypeError} core::String*;
+        core::String* actual = node.{self::Node::toSimpleString}() as{TypeError,ForDynamic} core::String*;
         core::print(actual);
         if(!actual.{core::String::==}(expected)) {
           throw "Expected '${expected}' but got '${actual}'";
diff --git a/pkg/front_end/testcases/general/await_complex.dart.strong.expect b/pkg/front_end/testcases/general/await_complex.dart.strong.expect
index 9cf401a..a0b6fdd 100644
--- a/pkg/front_end/testcases/general/await_complex.dart.strong.expect
+++ b/pkg/front_end/testcases/general/await_complex.dart.strong.expect
@@ -14,14 +14,14 @@
   static get staticGetter() → core::int*
     return self::C::staticField;
   static set staticSetter(dynamic val) → void {
-    self::C::staticField = val as{TypeError} core::int*;
+    self::C::staticField = val as{TypeError,ForDynamic} core::int*;
   }
   static method staticFoo(core::int* param) → core::int*
     return param;
   get getter() → core::int*
     return this.{self::C::field};
   set setter(dynamic val) → void {
-    this.{self::C::field} = val as{TypeError} core::int*;
+    this.{self::C::field} = val as{TypeError,ForDynamic} core::int*;
   }
   method foo(core::int* param) → core::int*
     return param;
@@ -41,65 +41,65 @@
 static get topLevelGetter() → core::int*
   return self::globalVariable;
 static set topLevelSetter(dynamic val) → void {
-  self::globalVariable = val as{TypeError} core::int*;
+  self::globalVariable = val as{TypeError,ForDynamic} core::int*;
 }
 static method dummy() → dynamic
   return 1;
 static method staticMembers() → dynamic async {
-  core::num* a = self::C::staticField.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* a = self::C::staticField.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, a);
-  core::num* f = (self::C::staticField = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* f = (self::C::staticField = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, f);
-  core::num* b = self::C::staticGetter.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* b = self::C::staticGetter.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, b);
-  core::num* c = (self::C::staticSetter = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* c = (self::C::staticSetter = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, c);
-  core::num* d = self::C::staticFoo(2).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = self::C::staticFoo(2).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(3, d);
-  core::num* e = self::C::staticField.{core::num::+}(self::C::staticGetter).{core::num::+}(self::C::staticSetter = 1).{core::num::+}(self::C::staticFoo(1)).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = self::C::staticField.{core::num::+}(self::C::staticGetter).{core::num::+}(self::C::staticSetter = 1).{core::num::+}(self::C::staticFoo(1)).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(5, e);
 }
 static method topLevelMembers() → dynamic async {
-  core::num* a = self::globalVariable.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* a = self::globalVariable.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, a);
-  core::num* b = self::topLevelGetter.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* b = self::topLevelGetter.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, b);
-  core::num* c = (self::topLevelSetter = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* c = (self::topLevelSetter = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, c);
-  core::num* d = self::topLevelFoo(1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = self::topLevelFoo(1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, d);
-  core::num* e = self::globalVariable.{core::num::+}(self::topLevelGetter).{core::num::+}(self::topLevelSetter = 1).{core::num::+}(self::topLevelFoo(1)).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = self::globalVariable.{core::num::+}(self::topLevelGetter).{core::num::+}(self::topLevelSetter = 1).{core::num::+}(self::topLevelFoo(1)).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(5, e);
 }
 static method instanceMembers() → dynamic async {
   self::C* inst = new self::C::•();
-  core::num* a = inst.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* a = inst.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, a);
-  core::num* b = inst.{self::C::getter}.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* b = inst.{self::C::getter}.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, b);
-  core::num* c = (inst.{self::C::setter} = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* c = (inst.{self::C::setter} = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, c);
-  core::num* d = inst.{self::C::foo}(1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = inst.{self::C::foo}(1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, d);
-  core::num* e = inst.{self::C::field}.{core::num::+}(inst.{self::C::getter}).{core::num::+}(inst.{self::C::setter} = 1).{core::num::+}(inst.{self::C::foo}(1)).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = inst.{self::C::field}.{core::num::+}(inst.{self::C::getter}).{core::num::+}(inst.{self::C::setter} = 1).{core::num::+}(inst.{self::C::foo}(1)).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(5, e);
 }
 static method others() → dynamic async {
   core::String* a = "${self::globalVariable} ${await self::dummy()} ".{core::String::+}(await "someString");
   self::expect("1 1 someString", a);
   self::C* c = new self::C::•();
-  core::num* d = c.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = c.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   core::int* cnt = 2;
   core::List<core::int*>* b = <core::int*>[1, 2, 3];
-  b.{core::List::[]=}(cnt, await self::dummy() as{TypeError} core::int*);
+  b.{core::List::[]=}(cnt, await self::dummy() as{TypeError,ForDynamic} core::int*);
   self::expect(1, b.{core::List::[]}(cnt));
-  core::num* e = b.{core::List::[]}(0).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = b.{core::List::[]}(0).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, e);
 }
 static method conditionals() → dynamic async {
   core::bool* a = false;
   core::bool* b = true;
-  core::bool* c = a || b || await self::dummy() as{TypeError} core::bool*;
+  core::bool* c = a || b || await self::dummy() as{TypeError,ForDynamic} core::bool*;
   self::expect(true, c);
   dynamic d = a || b ?{dynamic} a : await self::dummy();
   self::expect(false, d);
diff --git a/pkg/front_end/testcases/general/await_complex.dart.strong.transformed.expect b/pkg/front_end/testcases/general/await_complex.dart.strong.transformed.expect
index b6697d5..3840565 100644
--- a/pkg/front_end/testcases/general/await_complex.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/await_complex.dart.strong.transformed.expect
@@ -15,14 +15,14 @@
   static get staticGetter() → core::int*
     return self::C::staticField;
   static set staticSetter(dynamic val) → void {
-    self::C::staticField = val as{TypeError} core::int*;
+    self::C::staticField = val as{TypeError,ForDynamic} core::int*;
   }
   static method staticFoo(core::int* param) → core::int*
     return param;
   get getter() → core::int*
     return this.{self::C::field};
   set setter(dynamic val) → void {
-    this.{self::C::field} = val as{TypeError} core::int*;
+    this.{self::C::field} = val as{TypeError,ForDynamic} core::int*;
   }
   method foo(core::int* param) → core::int*
     return param;
@@ -42,7 +42,7 @@
 static get topLevelGetter() → core::int*
   return self::globalVariable;
 static set topLevelSetter(dynamic val) → void {
-  self::globalVariable = val as{TypeError} core::int*;
+  self::globalVariable = val as{TypeError,ForDynamic} core::int*;
 }
 static method dummy() → dynamic
   return 1;
@@ -67,27 +67,27 @@
       {
         :async_temporary_0 = self::C::staticField;
         [yield] let dynamic #t1 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, a);
         :async_temporary_1 = self::C::staticField = 1;
         [yield] let dynamic #t2 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* f = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* f = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, f);
         :async_temporary_2 = self::C::staticGetter;
         [yield] let dynamic #t3 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* b = :async_temporary_2.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* b = :async_temporary_2.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, b);
         :async_temporary_3 = self::C::staticSetter = 1;
         [yield] let dynamic #t4 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* c = :async_temporary_3.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* c = :async_temporary_3.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, c);
         :async_temporary_4 = self::C::staticFoo(2);
         [yield] let dynamic #t5 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(3, d);
         :async_temporary_5 = self::C::staticField.{core::num::+}(self::C::staticGetter).{core::num::+}(self::C::staticSetter = 1).{core::num::+}(self::C::staticFoo(1));
         [yield] let dynamic #t6 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_5.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_5.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(5, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -122,23 +122,23 @@
       {
         :async_temporary_0 = self::globalVariable;
         [yield] let dynamic #t7 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, a);
         :async_temporary_1 = self::topLevelGetter;
         [yield] let dynamic #t8 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, b);
         :async_temporary_2 = self::topLevelSetter = 1;
         [yield] let dynamic #t9 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, c);
         :async_temporary_3 = self::topLevelFoo(1);
         [yield] let dynamic #t10 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, d);
         :async_temporary_4 = self::globalVariable.{core::num::+}(self::topLevelGetter).{core::num::+}(self::topLevelSetter = 1).{core::num::+}(self::topLevelFoo(1));
         [yield] let dynamic #t11 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(5, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -174,23 +174,23 @@
         self::C* inst = new self::C::•();
         :async_temporary_0 = inst.{self::C::field};
         [yield] let dynamic #t12 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, a);
         :async_temporary_1 = inst.{self::C::getter};
         [yield] let dynamic #t13 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, b);
         :async_temporary_2 = inst.{self::C::setter} = 1;
         [yield] let dynamic #t14 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, c);
         :async_temporary_3 = inst.{self::C::foo}(1);
         [yield] let dynamic #t15 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, d);
         :async_temporary_4 = inst.{self::C::field}.{core::num::+}(inst.{self::C::getter}).{core::num::+}(inst.{self::C::setter} = 1).{core::num::+}(inst.{self::C::foo}(1));
         [yield] let dynamic #t16 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(5, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -232,17 +232,17 @@
         self::C* c = new self::C::•();
         :async_temporary_1 = c.{self::C::field};
         [yield] let dynamic #t19 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         core::int* cnt = 2;
         core::List<core::int*>* b = <core::int*>[1, 2, 3];
         :async_temporary_3 = b;
         :async_temporary_2 = cnt;
         [yield] let dynamic #t20 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        :async_temporary_3.{core::List::[]=}(:async_temporary_2, :result as{TypeError} core::int*);
+        :async_temporary_3.{core::List::[]=}(:async_temporary_2, :result as{TypeError,ForDynamic} core::int*);
         self::expect(1, b.{core::List::[]}(cnt));
         :async_temporary_4 = b.{core::List::[]}(0);
         [yield] let dynamic #t21 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -282,7 +282,7 @@
           ;
         else {
           [yield] let dynamic #t22 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-          :async_temporary_0 = (:result as{TypeError} core::bool*).==(true);
+          :async_temporary_0 = (:result as{TypeError,ForDynamic} core::bool*).==(true);
         }
         core::bool* c = :async_temporary_0;
         self::expect(true, c);
diff --git a/pkg/front_end/testcases/general/bug37476.dart.strong.expect b/pkg/front_end/testcases/general/bug37476.dart.strong.expect
index cd1a2ae..657464a 100644
--- a/pkg/front_end/testcases/general/bug37476.dart.strong.expect
+++ b/pkg/front_end/testcases/general/bug37476.dart.strong.expect
@@ -24,14 +24,14 @@
 static field self::B<core::num*>* b = new self::B::•<core::int*>();
 static method main() → dynamic {
   try {
-    self::a.{self::A::foo}() as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    self::a.{self::A::foo}() as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    self::b.{self::B::foo}() as{TypeError} (core::num*) →* void;
+    self::b.{self::B::foo}() as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general/bug37476.dart.strong.transformed.expect b/pkg/front_end/testcases/general/bug37476.dart.strong.transformed.expect
index cd1a2ae..657464a 100644
--- a/pkg/front_end/testcases/general/bug37476.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/bug37476.dart.strong.transformed.expect
@@ -24,14 +24,14 @@
 static field self::B<core::num*>* b = new self::B::•<core::int*>();
 static method main() → dynamic {
   try {
-    self::a.{self::A::foo}() as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    self::a.{self::A::foo}() as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    self::b.{self::B::foo}() as{TypeError} (core::num*) →* void;
+    self::b.{self::B::foo}() as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general/check_deferred_before_args.dart.strong.expect b/pkg/front_end/testcases/general/check_deferred_before_args.dart.strong.expect
index 92d9353..5c59c15 100644
--- a/pkg/front_end/testcases/general/check_deferred_before_args.dart.strong.expect
+++ b/pkg/front_end/testcases/general/check_deferred_before_args.dart.strong.expect
@@ -7,7 +7,7 @@
 
 static method main() → dynamic {}
 static method test() → dynamic {
-  let final dynamic #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError} core::int*;
+  let final dynamic #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError,ForDynamic} core::int*;
   let final dynamic #t2 = CheckLibraryIsLoaded(lib) in def::m(self::m2());
 }
 static method m2() → dynamic
diff --git a/pkg/front_end/testcases/general/check_deferred_before_args.dart.strong.transformed.expect b/pkg/front_end/testcases/general/check_deferred_before_args.dart.strong.transformed.expect
index 6da0135..441b505 100644
--- a/pkg/front_end/testcases/general/check_deferred_before_args.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/check_deferred_before_args.dart.strong.transformed.expect
@@ -7,7 +7,7 @@
 
 static method main() → dynamic {}
 static method test() → dynamic {
-  let final core::Object* #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError} core::int*;
+  let final core::Object* #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError,ForDynamic} core::int*;
   let final core::Object* #t2 = CheckLibraryIsLoaded(lib) in def::m(self::m2());
 }
 static method m2() → dynamic
diff --git a/pkg/front_end/testcases/general/classes.dart.strong.expect b/pkg/front_end/testcases/general/classes.dart.strong.expect
index 454a0a4..5e9a421 100644
--- a/pkg/front_end/testcases/general/classes.dart.strong.expect
+++ b/pkg/front_end/testcases/general/classes.dart.strong.expect
@@ -16,7 +16,7 @@
 }
 class B extends self::A {
   constructor •(dynamic x) → self::B*
-    : super self::A::•(x as{TypeError} core::int*)
+    : super self::A::•(x as{TypeError,ForDynamic} core::int*)
     ;
   method method() → dynamic {
     core::print("B.method x: ${this.{self::A::x}} y: ${this.{self::A::y}}");
diff --git a/pkg/front_end/testcases/general/classes.dart.strong.transformed.expect b/pkg/front_end/testcases/general/classes.dart.strong.transformed.expect
index 454a0a4..5e9a421 100644
--- a/pkg/front_end/testcases/general/classes.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/classes.dart.strong.transformed.expect
@@ -16,7 +16,7 @@
 }
 class B extends self::A {
   constructor •(dynamic x) → self::B*
-    : super self::A::•(x as{TypeError} core::int*)
+    : super self::A::•(x as{TypeError,ForDynamic} core::int*)
     ;
   method method() → dynamic {
     core::print("B.method x: ${this.{self::A::x}} y: ${this.{self::A::y}}");
diff --git a/pkg/front_end/testcases/general/constructor_initializer_invalid.dart.strong.expect b/pkg/front_end/testcases/general/constructor_initializer_invalid.dart.strong.expect
index 7cf2d27..62aa508 100644
--- a/pkg/front_end/testcases/general/constructor_initializer_invalid.dart.strong.expect
+++ b/pkg/front_end/testcases/general/constructor_initializer_invalid.dart.strong.expect
@@ -36,7 +36,7 @@
   constructor •() → self::C2*
     : self::C2::f = invalid-expression "pkg/front_end/testcases/general/constructor_initializer_invalid.dart:6:27: Error: This couldn't be parsed.
 class C2 { int f; C2() : f; }
-                          ^" as{TypeError} core::int*, super core::Object::•()
+                          ^" as{TypeError,ForDynamic} core::int*, super core::Object::•()
     ;
 }
 class C3 extends core::Object {
diff --git a/pkg/front_end/testcases/general/constructor_initializer_invalid.dart.strong.transformed.expect b/pkg/front_end/testcases/general/constructor_initializer_invalid.dart.strong.transformed.expect
index 7cf2d27..62aa508 100644
--- a/pkg/front_end/testcases/general/constructor_initializer_invalid.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/constructor_initializer_invalid.dart.strong.transformed.expect
@@ -36,7 +36,7 @@
   constructor •() → self::C2*
     : self::C2::f = invalid-expression "pkg/front_end/testcases/general/constructor_initializer_invalid.dart:6:27: Error: This couldn't be parsed.
 class C2 { int f; C2() : f; }
-                          ^" as{TypeError} core::int*, super core::Object::•()
+                          ^" as{TypeError,ForDynamic} core::int*, super core::Object::•()
     ;
 }
 class C3 extends core::Object {
diff --git a/pkg/front_end/testcases/general/control_flow_collection.dart.strong.expect b/pkg/front_end/testcases/general/control_flow_collection.dart.strong.expect
index f133a9d..3044135 100644
--- a/pkg/front_end/testcases/general/control_flow_collection.dart.strong.expect
+++ b/pkg/front_end/testcases/general/control_flow_collection.dart.strong.expect
@@ -7,19 +7,19 @@
   final core::List<core::int*>* aList = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
     #t1.{core::List::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(3);
     else
       #t1.{core::List::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t1.{core::List::add}(4);
     for (core::int* i in <core::int*>[5, 6, 7])
       #t1.{core::List::add}(i);
     for (core::int* i in <core::int*>[8, 9, 10])
-      if(self::oracle() as{TypeError} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t1.{core::List::add}(i);
     for (core::int* i = 11; i.{core::num::<=}(14); i = i.{core::num::+}(1))
       #t1.{core::List::add}(i);
@@ -27,19 +27,19 @@
   final core::Set<core::int*>* aSet = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
     #t2.{core::Set::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(3);
     else
       #t2.{core::Set::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t2.{core::Set::add}(4);
     for (core::int* i in <core::int*>[5, 6, 7])
       #t2.{core::Set::add}(i);
     for (core::int* i in <core::int*>[8, 9, 10])
-      if(self::oracle() as{TypeError} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t2.{core::Set::add}(i);
     for (core::int* i = 11; i.{core::num::<=}(14); i = i.{core::num::+}(1))
       #t2.{core::Set::add}(i);
@@ -47,19 +47,19 @@
   final core::Map<core::int*, core::int*>* aMap = block {
     final core::Map<core::int*, core::int*>* #t3 = <core::int*, core::int*>{};
     #t3.{core::Map::[]=}(1, 1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(2, 2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(3, 3);
     else
       #t3.{core::Map::[]=}(1.{core::int::unary-}(), 1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t3.{core::Map::[]=}(4, 4);
     for (core::int* i in <core::int*>[5, 6, 7])
       #t3.{core::Map::[]=}(i, i);
     for (core::int* i in <core::int*>[8, 9, 10])
-      if(self::oracle() as{TypeError} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t3.{core::Map::[]=}(i, i);
     for (core::int* i = 11; i.{core::num::<=}(14); i = i.{core::num::+}(1))
       #t3.{core::Map::[]=}(i, i);
diff --git a/pkg/front_end/testcases/general/control_flow_collection.dart.strong.transformed.expect b/pkg/front_end/testcases/general/control_flow_collection.dart.strong.transformed.expect
index ac4ad8d..7bd3d63 100644
--- a/pkg/front_end/testcases/general/control_flow_collection.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/control_flow_collection.dart.strong.transformed.expect
@@ -8,14 +8,14 @@
   final core::List<core::int*>* aList = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
     #t1.{core::List::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(3);
     else
       #t1.{core::List::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t1.{core::List::add}(4);
     {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[5, 6, 7]).{core::Iterable::iterator};
@@ -28,7 +28,7 @@
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[8, 9, 10]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int* i = :sync-for-iterator.{core::Iterator::current};
-        if(self::oracle() as{TypeError} core::bool*)
+        if(self::oracle() as{TypeError,ForDynamic} core::bool*)
           #t1.{core::List::add}(i);
       }
     }
@@ -38,14 +38,14 @@
   final core::Set<core::int*>* aSet = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
     #t2.{core::Set::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(3);
     else
       #t2.{core::Set::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t2.{core::Set::add}(4);
     {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[5, 6, 7]).{core::Iterable::iterator};
@@ -58,7 +58,7 @@
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[8, 9, 10]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int* i = :sync-for-iterator.{core::Iterator::current};
-        if(self::oracle() as{TypeError} core::bool*)
+        if(self::oracle() as{TypeError,ForDynamic} core::bool*)
           #t2.{core::Set::add}(i);
       }
     }
@@ -68,14 +68,14 @@
   final core::Map<core::int*, core::int*>* aMap = block {
     final core::Map<core::int*, core::int*>* #t3 = <core::int*, core::int*>{};
     #t3.{core::Map::[]=}(1, 1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(2, 2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(3, 3);
     else
       #t3.{core::Map::[]=}(1.{core::int::unary-}(), 1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t3.{core::Map::[]=}(4, 4);
     {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[5, 6, 7]).{core::Iterable::iterator};
@@ -88,7 +88,7 @@
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[8, 9, 10]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int* i = :sync-for-iterator.{core::Iterator::current};
-        if(self::oracle() as{TypeError} core::bool*)
+        if(self::oracle() as{TypeError,ForDynamic} core::bool*)
           #t3.{core::Map::[]=}(i, i);
       }
     }
diff --git a/pkg/front_end/testcases/general/control_flow_collection_inference.dart.strong.expect b/pkg/front_end/testcases/general/control_flow_collection_inference.dart.strong.expect
index c865110..70902fb 100644
--- a/pkg/front_end/testcases/general/control_flow_collection_inference.dart.strong.expect
+++ b/pkg/front_end/testcases/general/control_flow_collection_inference.dart.strong.expect
@@ -443,193 +443,193 @@
 static method testIfElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::Map<core::String*, core::int*>* mapToInt, core::Map<core::String*, core::double*>* mapToDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(42);
   } =>#t1;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(42);
     #t2.{core::Set::add}(null);
   } =>#t2;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t3 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}("bar", 42);
     #t3.{core::Map::[]=}("baz", null);
   } =>#t3;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t4 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t4.{core::List::add}(dynVar);
   } =>#t4;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t5 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t5.{core::Set::add}(dynVar);
     #t5.{core::Set::add}(null);
   } =>#t5;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t6 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t6.{core::Map::[]=}("bar", dynVar);
     #t6.{core::Map::[]=}("baz", null);
   } =>#t6;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t7 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t7.{core::List::add}(<core::int*>[42]);
   } =>#t7;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t8 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t8.{core::Set::add}(<core::int*>[42]);
     #t8.{core::Set::add}(null);
   } =>#t8;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t9 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t9.{core::Map::[]=}("bar", <core::int*>[42]);
     #t9.{core::Map::[]=}("baz", null);
   } =>#t9;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t10 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t11 in <core::int*>[42])
         #t10.{core::List::add}(#t11);
   } =>#t10;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t12 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t13 in <core::int*>[42])
         #t12.{core::Set::add}(#t13);
     #t12.{core::Set::add}(null);
   } =>#t12;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t14 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::int*>* #t15 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
         #t14.{core::Map::[]=}(#t15.{core::MapEntry::key}, #t15.{core::MapEntry::value});
     #t14.{core::Map::[]=}("baz", null);
   } =>#t14;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t16 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t17 in <dynamic>[dynVar])
         #t16.{core::List::add}(#t17);
   } =>#t16;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t18 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t19 in <dynamic>[dynVar])
         #t18.{core::Set::add}(#t19);
     #t18.{core::Set::add}(null);
   } =>#t18;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t20 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, dynamic>* #t21 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
         #t20.{core::Map::[]=}(#t21.{core::MapEntry::key}, #t21.{core::MapEntry::value});
     #t20.{core::Map::[]=}("baz", null);
   } =>#t20;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t22 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t23 in <core::List<core::int*>*>[<core::int*>[42]])
         #t22.{core::List::add}(#t23);
   } =>#t22;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t24 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t25 in <core::List<core::int*>*>[<core::int*>[42]])
         #t24.{core::Set::add}(#t25);
     #t24.{core::Set::add}(null);
   } =>#t24;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t26 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t27 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
         #t26.{core::Map::[]=}(#t27.{core::MapEntry::key}, #t27.{core::MapEntry::value});
     #t26.{core::Map::[]=}("baz", null);
   } =>#t26;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t28 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t29 in <core::int*>[42])
           #t28.{core::List::add}(#t29);
   } =>#t28;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t30 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t31 in <core::int*>[42])
           #t30.{core::Set::add}(#t31);
     #t30.{core::Set::add}(null);
   } =>#t30;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t32 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::int*>* #t33 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
           #t32.{core::Map::[]=}(#t33.{core::MapEntry::key}, #t33.{core::MapEntry::value});
     #t32.{core::Map::[]=}("baz", null);
   } =>#t32;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t34 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t35 in <dynamic>[dynVar])
           #t34.{core::List::add}(#t35);
   } =>#t34;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t36 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t37 in <dynamic>[dynVar])
           #t36.{core::Set::add}(#t37);
     #t36.{core::Set::add}(null);
   } =>#t36;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t38 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, dynamic>* #t39 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
           #t38.{core::Map::[]=}(#t39.{core::MapEntry::key}, #t39.{core::MapEntry::value});
     #t38.{core::Map::[]=}("baz", null);
   } =>#t38;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t40 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t41 in <core::List<core::int*>*>[<core::int*>[42]])
           #t40.{core::List::add}(#t41);
   } =>#t40;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t42 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t43 in <core::List<core::int*>*>[<core::int*>[42]])
           #t42.{core::Set::add}(#t43);
     #t42.{core::Set::add}(null);
   } =>#t42;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t44 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t45 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
           #t44.{core::Map::[]=}(#t45.{core::MapEntry::key}, #t45.{core::MapEntry::value});
     #t44.{core::Map::[]=}("baz", null);
   } =>#t44;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t46 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t47 in <core::List<core::int*>*>[<core::int*>[]])
         #t46.{core::List::add}(#t47);
   } =>#t46;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t48 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t49 in <core::List<core::int*>*>[<core::int*>[]])
         #t48.{core::Set::add}(#t49);
     #t48.{core::Set::add}(null);
@@ -639,173 +639,173 @@
                                  ^";
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t50 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t51 in let final core::Set<core::List<core::int*>*>* #t52 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t53 = #t52.{core::Set::add}(<core::int*>[]) in #t52)
         #t50.{core::List::add}(#t51);
   } =>#t50;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t54 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t55 in let final core::Set<core::List<core::int*>*>* #t56 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t57 = #t56.{core::Set::add}(<core::int*>[]) in #t56)
         #t54.{core::Set::add}(#t55);
     #t54.{core::Set::add}(null);
   } =>#t54;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t58 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t59 in <core::List<core::int*>*>[<core::int*>[]])
           #t58.{core::List::add}(#t59);
   } =>#t58;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t60 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t61 in <core::List<core::int*>*>[<core::int*>[]])
           #t60.{core::Set::add}(#t61);
     #t60.{core::Set::add}(null);
   } =>#t60;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t62 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t63 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t62.{core::Map::[]=}(#t63.{core::MapEntry::key}, #t63.{core::MapEntry::value});
     #t62.{core::Map::[]=}("baz", null);
   } =>#t62;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t64 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t65 in <core::int*>[])
         #t64.{core::List::add}(#t65);
   } =>#t64;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t67 in <core::int*>[])
         #t66.{core::Set::add}(#t67);
     #t66.{core::Set::add}(null);
   } =>#t66;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t68 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::int*>* #t69 in <core::String*, core::int*>{}.{core::Map::entries})
         #t68.{core::Map::[]=}(#t69.{core::MapEntry::key}, #t69.{core::MapEntry::value});
     #t68.{core::Map::[]=}("baz", null);
   } =>#t68;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t70 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t71 in let final core::Set<core::int*>* #t72 = col::LinkedHashSet::•<core::int*>() in #t72)
         #t70.{core::List::add}(#t71);
   } =>#t70;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t73 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t74 in let final core::Set<core::int*>* #t75 = col::LinkedHashSet::•<core::int*>() in #t75)
         #t73.{core::Set::add}(#t74);
     #t73.{core::Set::add}(null);
   } =>#t73;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t76 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t77 in <core::int*>[])
           #t76.{core::List::add}(#t77);
   } =>#t76;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t78 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t79 in <core::int*>[])
           #t78.{core::Set::add}(#t79);
     #t78.{core::Set::add}(null);
   } =>#t78;
   core::Map<core::String*, core::int*>* map52 = block {
     final core::Map<core::String*, core::int*>* #t80 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::int*>* #t81 in <core::String*, core::int*>{}.{core::Map::entries})
           #t80.{core::Map::[]=}(#t81.{core::MapEntry::key}, #t81.{core::MapEntry::value});
     #t80.{core::Map::[]=}("baz", null);
   } =>#t80;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t82 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t83 in <core::List<core::int*>*>[<core::int*>[]])
         #t82.{core::List::add}(#t83);
   } =>#t82;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t84 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t85 in <core::List<core::int*>*>[<core::int*>[]])
         #t84.{core::Set::add}(#t85);
     #t84.{core::Set::add}(null);
   } =>#t84;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t86 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t87 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
         #t86.{core::Map::[]=}(#t87.{core::MapEntry::key}, #t87.{core::MapEntry::value});
     #t86.{core::Map::[]=}("baz", null);
   } =>#t86;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t88 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t89 in <core::List<core::int*>*>[<core::int*>[]])
           #t88.{core::List::add}(#t89);
   } =>#t88;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t90 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t91 in <core::List<core::int*>*>[<core::int*>[]])
           #t90.{core::Set::add}(#t91);
     #t90.{core::Set::add}(null);
   } =>#t90;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t92 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t93 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t92.{core::Map::[]=}(#t93.{core::MapEntry::key}, #t93.{core::MapEntry::value});
     #t92.{core::Map::[]=}("baz", null);
   } =>#t92;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t94 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t94.{core::List::add}(<core::int*>[]);
   } =>#t94;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t95 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t95.{core::Set::add}(<core::int*>[]);
     #t95.{core::Set::add}(null);
   } =>#t95;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t96 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t96.{core::List::add}(<core::int*>[]);
   } =>#t96;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t97 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t97.{core::Set::add}(<core::int*>[]);
     #t97.{core::Set::add}(null);
   } =>#t97;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t98 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t98.{core::List::add}(42);
     else
       #t98.{core::List::add}(3.14);
   } =>#t98;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t99 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t99.{core::Set::add}(42);
     else
       #t99.{core::Set::add}(3.14);
@@ -813,7 +813,7 @@
   } =>#t99;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t100 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t100.{core::Map::[]=}("bar", 42);
     else
       #t100.{core::Map::[]=}("bar", 3.14);
@@ -821,7 +821,7 @@
   } =>#t100;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t101 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::num* #t102 in listInt)
         #t101.{core::List::add}(#t102);
     else
@@ -830,7 +830,7 @@
   } =>#t101;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t104 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::num* #t105 in listInt)
         #t104.{core::Set::add}(#t105);
     else
@@ -840,7 +840,7 @@
   } =>#t104;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t107 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::num*>* #t108 in mapToInt.{core::Map::entries})
         #t107.{core::Map::[]=}(#t108.{core::MapEntry::key}, #t108.{core::MapEntry::value});
     else
@@ -850,38 +850,38 @@
   } =>#t107;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t110 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t111 in listInt)
         #t110.{core::List::add}(#t111);
     else
-      for (final dynamic #t112 in dynVar as{TypeError} core::Iterable<dynamic>*)
+      for (final dynamic #t112 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
         #t110.{core::List::add}(#t112);
   } =>#t110;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t113 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t114 in listInt)
         #t113.{core::Set::add}(#t114);
     else
-      for (final dynamic #t115 in dynVar as{TypeError} core::Iterable<dynamic>*)
+      for (final dynamic #t115 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
         #t113.{core::Set::add}(#t115);
     #t113.{core::Set::add}(null);
   } =>#t113;
   core::Set<dynamic>* map82 = block {
     final core::Set<dynamic>* #t116 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t116.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:71:38: Error: Unexpected type 'Map<String, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   var map82 = {if (oracle(\"foo\")) ...mapToInt else ...dynVar, null};
                                      ^");
     else
-      for (final dynamic #t117 in dynVar as{TypeError} core::Iterable<dynamic>*)
+      for (final dynamic #t117 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
         #t116.{core::Set::add}(#t117);
     #t116.{core::Set::add}(null);
   } =>#t116;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t118 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t118.{core::List::add}(42);
     else
       for (final core::num* #t119 in listDouble)
@@ -889,7 +889,7 @@
   } =>#t118;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t120 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::num* #t121 in listInt)
         #t120.{core::Set::add}(#t121);
     else
@@ -898,7 +898,7 @@
   } =>#t120;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t122 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::num*>* #t123 in mapToInt.{core::Map::entries})
         #t122.{core::Map::[]=}(#t123.{core::MapEntry::key}, #t123.{core::MapEntry::value});
     else
@@ -907,33 +907,33 @@
   } =>#t122;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t124 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t124.{core::List::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t124.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t124;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t125 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t125.{core::Set::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t125.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t125.{core::Set::add}(null);
   } =>#t125;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t126 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t126.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t126.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t126.{core::Map::[]=}("baz", null);
   } =>#t126;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t127 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      for (final dynamic #t128 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      for (final dynamic #t128 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t129 = #t128 as{TypeError} core::int*;
         #t127.{core::List::add}(#t129);
       }
   } =>#t127;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t130 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      for (final dynamic #t131 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      for (final dynamic #t131 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t132 = #t131 as{TypeError} core::int*;
         #t130.{core::Set::add}(#t132);
       }
@@ -941,8 +941,8 @@
   } =>#t130;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t133 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      for (final core::MapEntry<dynamic, dynamic>* #t134 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      for (final core::MapEntry<dynamic, dynamic>* #t134 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
         final core::String* #t135 = #t134.{core::MapEntry::key} as{TypeError} core::String*;
         final core::int* #t136 = #t134.{core::MapEntry::value} as{TypeError} core::int*;
         #t133.{core::Map::[]=}(#t135, #t136);
@@ -951,31 +951,31 @@
   } =>#t133;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t137 = <core::int*>[];
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t137.{core::List::add}(42);
   } =>#t137;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t138 = col::LinkedHashSet::•<core::int*>();
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t138.{core::Set::add}(42);
   } =>#t138;
   core::Map<core::int*, core::int*>* map100 = block {
     final core::Map<core::int*, core::int*>* #t139 = <core::int*, core::int*>{};
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t139.{core::Map::[]=}(42, 42);
   } =>#t139;
 }
 static method testIfElementErrors(core::Map<core::int*, core::int*>* map) → dynamic {
   block {
     final core::List<core::int*>* #t140 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t140.{core::List::add}(let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:87:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) \"bar\"];
                            ^" in "bar" as{TypeError} core::int*);
   } =>#t140;
   block {
     final core::Set<core::int*>* #t142 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t142.{core::Set::add}(let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:88:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) \"bar\", null};
                            ^" in "bar" as{TypeError} core::int*);
@@ -983,7 +983,7 @@
   } =>#t142;
   block {
     final core::Map<core::String*, core::int*>* #t144 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t144.{core::Map::[]=}("bar", let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:89:43: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) \"bar\": \"bar\", \"baz\": null};
                                           ^" in "bar" as{TypeError} core::int*);
@@ -991,7 +991,7 @@
   } =>#t144;
   block {
     final core::List<core::int*>* #t146 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t147 in <core::int*>[let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:90:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) ...[\"bar\"]];
                                ^" in "bar" as{TypeError} core::int*])
@@ -999,7 +999,7 @@
   } =>#t146;
   block {
     final core::Set<core::int*>* #t149 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t150 in <core::int*>[let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:91:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) ...[\"bar\"], null};
                                ^" in "bar" as{TypeError} core::int*])
@@ -1008,7 +1008,7 @@
   } =>#t149;
   block {
     final core::Map<core::String*, core::int*>* #t152 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::int*>* #t153 in <core::String*, core::int*>{"bar": let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:92:47: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) ...{\"bar\": \"bar\"}, \"baz\": null};
                                               ^" in "bar" as{TypeError} core::int*}.{core::Map::entries})
@@ -1017,7 +1017,7 @@
   } =>#t152;
   block {
     final core::List<core::int*>* #t155 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t155.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:93:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map];
@@ -1025,7 +1025,7 @@
   } =>#t155;
   block {
     final core::Set<core::int*>* #t156 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t156.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:94:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map, null};
@@ -1041,7 +1041,7 @@
                                       ^": null};
   block {
     final core::List<core::String*>* #t157 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t157.{core::List::add}(let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:96:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[if (oracle(\"foo\")) 42 else 3.14];
                               ^" in 42 as{TypeError} core::String*);
@@ -1052,7 +1052,7 @@
   } =>#t157;
   block {
     final core::Set<core::String*>* #t160 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t160.{core::Set::add}(let final<BottomType> #t161 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:97:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{if (oracle(\"foo\")) 42 else 3.14, null};
                               ^" in 42 as{TypeError} core::String*);
@@ -1064,7 +1064,7 @@
   } =>#t160;
   block {
     final core::Map<core::String*, core::String*>* #t163 = <core::String*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t163.{core::Map::[]=}("bar", let final<BottomType> #t164 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:98:46: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{if (oracle(\"foo\")) \"bar\": 42 else \"baz\": 3.14, \"baz\": null};
                                              ^" in 42 as{TypeError} core::String*);
@@ -1076,7 +1076,7 @@
   } =>#t163;
   block {
     final core::List<core::int*>* #t166 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t166.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:99:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map else 42];
@@ -1086,7 +1086,7 @@
   } =>#t166;
   block {
     final core::Set<core::int*>* #t167 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t167.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:100:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1104,7 +1104,7 @@
                                       ^": null};
   block {
     final core::List<core::int*>* #t168 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t168.{core::List::add}(42);
     else
       #t168.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:102:39: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -1114,7 +1114,7 @@
   } =>#t168;
   block {
     final core::Set<core::int*>* #t169 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t169.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:103:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1171,7 +1171,7 @@
   } =>#t174;
   core::List<core::String*>* list40 = block {
     final core::List<core::String*>* #t176 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t176.{core::List::add}(let final<BottomType> #t177 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:115:53: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   List<String> list40 = <String>[if (oracle(\"foo\")) true else 42];
                                                     ^" in true as{TypeError} core::String*);
@@ -1182,7 +1182,7 @@
   } =>#t176;
   core::Set<core::String*>* set40 = block {
     final core::Set<core::String*>* #t179 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t179.{core::Set::add}(let final<BottomType> #t180 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:116:51: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Set<String> set40 = <String>{if (oracle(\"foo\")) true else 42};
                                                   ^" in true as{TypeError} core::String*);
@@ -1193,7 +1193,7 @@
   } =>#t179;
   core::Map<core::String*, core::int*>* map40 = block {
     final core::Map<core::String*, core::int*>* #t182 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t182.{core::Map::[]=}(let final<BottomType> #t183 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:117:61: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<String, int> map40 = <String, int>{if (oracle(\"foo\")) true: 42 else 42: 42};
                                                             ^" in true as{TypeError} core::String*, 42);
@@ -1204,7 +1204,7 @@
   } =>#t182;
   core::Map<core::int*, core::String*>* map41 = block {
     final core::Map<core::int*, core::String*>* #t185 = <core::int*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t185.{core::Map::[]=}(42, let final<BottomType> #t186 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:118:65: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<int, String> map41 = <int, String>{if (oracle(\"foo\")) 42: true else 42: 42};
                                                                 ^" in true as{TypeError} core::String*);
@@ -1217,380 +1217,380 @@
 static method testForElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::int* index, core::Map<core::String*, core::int*>* mapStringInt, core::Map<core::String*, core::double*>* mapStringDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t188 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t188.{core::List::add}(42);
   } =>#t188;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t189 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t189.{core::Set::add}(42);
     #t189.{core::Set::add}(null);
   } =>#t189;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t190 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t190.{core::Map::[]=}("bar", 42);
     #t190.{core::Map::[]=}("baz", null);
   } =>#t190;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t191 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t191.{core::List::add}(dynVar);
   } =>#t191;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t192 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t192.{core::Set::add}(dynVar);
     #t192.{core::Set::add}(null);
   } =>#t192;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t193 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t193.{core::Map::[]=}("bar", dynVar);
     #t193.{core::Map::[]=}("baz", null);
   } =>#t193;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t194 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t194.{core::List::add}(<core::int*>[42]);
   } =>#t194;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t195 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t195.{core::Set::add}(<core::int*>[42]);
     #t195.{core::Set::add}(null);
   } =>#t195;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t196 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t196.{core::Map::[]=}("bar", <core::int*>[42]);
     #t196.{core::Map::[]=}("baz", null);
   } =>#t196;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t197 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t198 in <core::int*>[42])
         #t197.{core::List::add}(#t198);
   } =>#t197;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t199 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t200 in <core::int*>[42])
         #t199.{core::Set::add}(#t200);
     #t199.{core::Set::add}(null);
   } =>#t199;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t201 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::int*>* #t202 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
         #t201.{core::Map::[]=}(#t202.{core::MapEntry::key}, #t202.{core::MapEntry::value});
     #t201.{core::Map::[]=}("baz", null);
   } =>#t201;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t203 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final dynamic #t204 in <dynamic>[dynVar])
         #t203.{core::List::add}(#t204);
   } =>#t203;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t205 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final dynamic #t206 in <dynamic>[dynVar])
         #t205.{core::Set::add}(#t206);
     #t205.{core::Set::add}(null);
   } =>#t205;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t207 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, dynamic>* #t208 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
         #t207.{core::Map::[]=}(#t208.{core::MapEntry::key}, #t208.{core::MapEntry::value});
     #t207.{core::Map::[]=}("baz", null);
   } =>#t207;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t209 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t210 in <core::List<core::int*>*>[<core::int*>[42]])
         #t209.{core::List::add}(#t210);
   } =>#t209;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t211 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t212 in <core::List<core::int*>*>[<core::int*>[42]])
         #t211.{core::Set::add}(#t212);
     #t211.{core::Set::add}(null);
   } =>#t211;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t213 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t214 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
         #t213.{core::Map::[]=}(#t214.{core::MapEntry::key}, #t214.{core::MapEntry::value});
     #t213.{core::Map::[]=}("baz", null);
   } =>#t213;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t215 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t216 in <core::int*>[42])
           #t215.{core::List::add}(#t216);
   } =>#t215;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t217 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t218 in <core::int*>[42])
           #t217.{core::Set::add}(#t218);
     #t217.{core::Set::add}(null);
   } =>#t217;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t219 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::int*>* #t220 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
           #t219.{core::Map::[]=}(#t220.{core::MapEntry::key}, #t220.{core::MapEntry::value});
     #t219.{core::Map::[]=}("baz", null);
   } =>#t219;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t221 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t222 in <dynamic>[dynVar])
           #t221.{core::List::add}(#t222);
   } =>#t221;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t223 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t224 in <dynamic>[dynVar])
           #t223.{core::Set::add}(#t224);
     #t223.{core::Set::add}(null);
   } =>#t223;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t225 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, dynamic>* #t226 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
           #t225.{core::Map::[]=}(#t226.{core::MapEntry::key}, #t226.{core::MapEntry::value});
     #t225.{core::Map::[]=}("baz", null);
   } =>#t225;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t227 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t228 in <core::List<core::int*>*>[<core::int*>[42]])
           #t227.{core::List::add}(#t228);
   } =>#t227;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t229 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t230 in <core::List<core::int*>*>[<core::int*>[42]])
           #t229.{core::Set::add}(#t230);
     #t229.{core::Set::add}(null);
   } =>#t229;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t231 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t232 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
           #t231.{core::Map::[]=}(#t232.{core::MapEntry::key}, #t232.{core::MapEntry::value});
     #t231.{core::Map::[]=}("baz", null);
   } =>#t231;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t233 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t234 in <core::List<core::int*>*>[<core::int*>[]])
         #t233.{core::List::add}(#t234);
   } =>#t233;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t235 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t236 in <core::List<core::int*>*>[<core::int*>[]])
         #t235.{core::Set::add}(#t236);
     #t235.{core::Set::add}(null);
   } =>#t235;
   core::Map<core::String*, core::List<core::int*>*>* map40 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t237 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t238 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
         #t237.{core::Map::[]=}(#t238.{core::MapEntry::key}, #t238.{core::MapEntry::value});
     #t237.{core::Map::[]=}("baz", null);
   } =>#t237;
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t239 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t240 in let final core::Set<core::List<core::int*>*>* #t241 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t242 = #t241.{core::Set::add}(<core::int*>[]) in #t241)
         #t239.{core::List::add}(#t240);
   } =>#t239;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t243 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t244 in let final core::Set<core::List<core::int*>*>* #t245 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t246 = #t245.{core::Set::add}(<core::int*>[]) in #t245)
         #t243.{core::Set::add}(#t244);
     #t243.{core::Set::add}(null);
   } =>#t243;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t247 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t248 in <core::List<core::int*>*>[<core::int*>[]])
           #t247.{core::List::add}(#t248);
   } =>#t247;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t249 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t250 in <core::List<core::int*>*>[<core::int*>[]])
           #t249.{core::Set::add}(#t250);
     #t249.{core::Set::add}(null);
   } =>#t249;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t251 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t252 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t251.{core::Map::[]=}(#t252.{core::MapEntry::key}, #t252.{core::MapEntry::value});
     #t251.{core::Map::[]=}("baz", null);
   } =>#t251;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t253 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t254 in <core::int*>[])
         #t253.{core::List::add}(#t254);
   } =>#t253;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t255 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t256 in <core::int*>[])
         #t255.{core::Set::add}(#t256);
     #t255.{core::Set::add}(null);
   } =>#t255;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t257 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::int*>* #t258 in <core::String*, core::int*>{}.{core::Map::entries})
         #t257.{core::Map::[]=}(#t258.{core::MapEntry::key}, #t258.{core::MapEntry::value});
     #t257.{core::Map::[]=}("baz", null);
   } =>#t257;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t259 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t260 in let final core::Set<core::int*>* #t261 = col::LinkedHashSet::•<core::int*>() in #t261)
         #t259.{core::List::add}(#t260);
   } =>#t259;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t262 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t263 in let final core::Set<core::int*>* #t264 = col::LinkedHashSet::•<core::int*>() in #t264)
         #t262.{core::Set::add}(#t263);
     #t262.{core::Set::add}(null);
   } =>#t262;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t265 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t266 in <core::int*>[])
           #t265.{core::List::add}(#t266);
   } =>#t265;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t267 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t268 in <core::int*>[])
           #t267.{core::Set::add}(#t268);
     #t267.{core::Set::add}(null);
   } =>#t267;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t269 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t270 in <core::List<core::int*>*>[<core::int*>[]])
         #t269.{core::List::add}(#t270);
   } =>#t269;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t271 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t272 in <core::List<core::int*>*>[<core::int*>[]])
         #t271.{core::Set::add}(#t272);
     #t271.{core::Set::add}(null);
   } =>#t271;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t273 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t274 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
         #t273.{core::Map::[]=}(#t274.{core::MapEntry::key}, #t274.{core::MapEntry::value});
     #t273.{core::Map::[]=}("baz", null);
   } =>#t273;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t275 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t276 in <core::List<core::int*>*>[<core::int*>[]])
           #t275.{core::List::add}(#t276);
   } =>#t275;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t277 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t278 in <core::List<core::int*>*>[<core::int*>[]])
           #t277.{core::Set::add}(#t278);
     #t277.{core::Set::add}(null);
   } =>#t277;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t279 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t280 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t279.{core::Map::[]=}(#t280.{core::MapEntry::key}, #t280.{core::MapEntry::value});
     #t279.{core::Map::[]=}("baz", null);
   } =>#t279;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t281 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t281.{core::List::add}(<core::int*>[]);
   } =>#t281;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t282 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t282.{core::Set::add}(<core::int*>[]);
     #t282.{core::Set::add}(null);
   } =>#t282;
   core::Map<core::String*, core::List<core::int*>*>* map70 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t283 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t283.{core::Map::[]=}("bar", <core::int*>[]);
     #t283.{core::Map::[]=}("baz", null);
   } =>#t283;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t284 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t284.{core::List::add}(<core::int*>[]);
   } =>#t284;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t285 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t285.{core::Set::add}(<core::int*>[]);
     #t285.{core::Set::add}(null);
   } =>#t285;
   core::Map<core::String*, core::List<core::int*>*>* map71 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t286 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t286.{core::Map::[]=}("bar", <core::int*>[]);
     #t286.{core::Map::[]=}("baz", null);
   } =>#t286;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t287 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t287.{core::List::add}(42);
       else
         #t287.{core::List::add}(3.14);
   } =>#t287;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t288 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t288.{core::Set::add}(42);
       else
         #t288.{core::Set::add}(3.14);
@@ -1598,8 +1598,8 @@
   } =>#t288;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t289 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t289.{core::Map::[]=}("bar", 42);
       else
         #t289.{core::Map::[]=}("bar", 3.14);
@@ -1607,8 +1607,8 @@
   } =>#t289;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t290 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::num* #t291 in listInt)
           #t290.{core::List::add}(#t291);
       else
@@ -1617,8 +1617,8 @@
   } =>#t290;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t293 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::num* #t294 in listInt)
           #t293.{core::Set::add}(#t294);
       else
@@ -1628,8 +1628,8 @@
   } =>#t293;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t296 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::num*>* #t297 in mapStringInt.{core::Map::entries})
           #t296.{core::Map::[]=}(#t297.{core::MapEntry::key}, #t297.{core::MapEntry::value});
       else
@@ -1639,40 +1639,40 @@
   } =>#t296;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t299 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t300 in listInt)
           #t299.{core::List::add}(#t300);
       else
-        for (final dynamic #t301 in dynVar as{TypeError} core::Iterable<dynamic>*)
+        for (final dynamic #t301 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
           #t299.{core::List::add}(#t301);
   } =>#t299;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t302 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t303 in listInt)
           #t302.{core::Set::add}(#t303);
       else
-        for (final dynamic #t304 in dynVar as{TypeError} core::Iterable<dynamic>*)
+        for (final dynamic #t304 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
           #t302.{core::Set::add}(#t304);
     #t302.{core::Set::add}(null);
   } =>#t302;
   core::Map<dynamic, dynamic>* map82 = block {
     final core::Map<dynamic, dynamic>* #t305 = <dynamic, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<dynamic, dynamic>* #t306 in mapStringInt.{core::Map::entries})
           #t305.{core::Map::[]=}(#t306.{core::MapEntry::key}, #t306.{core::MapEntry::value});
       else
-        for (final core::MapEntry<dynamic, dynamic>* #t307 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries})
+        for (final core::MapEntry<dynamic, dynamic>* #t307 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries})
           #t305.{core::Map::[]=}(#t307.{core::MapEntry::key}, #t307.{core::MapEntry::value});
     #t305.{core::Map::[]=}("baz", null);
   } =>#t305;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t308 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t308.{core::List::add}(42);
       else
         for (final core::num* #t309 in listDouble)
@@ -1680,8 +1680,8 @@
   } =>#t308;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t310 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::num* #t311 in listInt)
           #t310.{core::Set::add}(#t311);
       else
@@ -1690,8 +1690,8 @@
   } =>#t310;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t312 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::num*>* #t313 in mapStringInt.{core::Map::entries})
           #t312.{core::Map::[]=}(#t313.{core::MapEntry::key}, #t313.{core::MapEntry::value});
       else
@@ -1700,33 +1700,33 @@
   } =>#t312;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t314 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t314.{core::List::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t314.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t314;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t315 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t315.{core::Set::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t315.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t315.{core::Set::add}(null);
   } =>#t315;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t316 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t316.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t316.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t316.{core::Map::[]=}("baz", null);
   } =>#t316;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t317 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      for (final dynamic #t318 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      for (final dynamic #t318 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t319 = #t318 as{TypeError} core::int*;
         #t317.{core::List::add}(#t319);
       }
   } =>#t317;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t320 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      for (final dynamic #t321 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      for (final dynamic #t321 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t322 = #t321 as{TypeError} core::int*;
         #t320.{core::Set::add}(#t322);
       }
@@ -1734,8 +1734,8 @@
   } =>#t320;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t323 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      for (final core::MapEntry<dynamic, dynamic>* #t324 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      for (final core::MapEntry<dynamic, dynamic>* #t324 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
         final core::String* #t325 = #t324.{core::MapEntry::key} as{TypeError} core::String*;
         final core::int* #t326 = #t324.{core::MapEntry::value} as{TypeError} core::int*;
         #t323.{core::Map::[]=}(#t325, #t326);
@@ -1744,17 +1744,17 @@
   } =>#t323;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t327 = <core::int*>[];
-    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t327.{core::List::add}(42);
   } =>#t327;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t329 = col::LinkedHashSet::•<core::int*>();
-    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t329.{core::Set::add}(42);
   } =>#t329;
   core::Map<core::String*, core::int*>* map100 = block {
     final core::Map<core::String*, core::int*>* #t331 = <core::String*, core::int*>{};
-    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t331.{core::Map::[]=}("bar", 42);
   } =>#t331;
   core::List<core::int*>* list110 = block {
@@ -1776,19 +1776,19 @@
   } =>#t335;
   core::List<core::int*>* list120 = block {
     final core::List<core::int*>* #t336 = <core::int*>[];
-    for (dynamic i in dynVar as{TypeError} core::Iterable<dynamic>*)
-      #t336.{core::List::add}(i as{TypeError} core::int*);
+    for (dynamic i in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
+      #t336.{core::List::add}(i as{TypeError,ForDynamic} core::int*);
   } =>#t336;
   core::Set<core::int*>* set120 = block {
     final core::Set<core::int*>* #t337 = col::LinkedHashSet::•<core::int*>();
-    for (dynamic i in dynVar as{TypeError} core::Iterable<dynamic>*)
-      #t337.{core::Set::add}(i as{TypeError} core::int*);
+    for (dynamic i in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
+      #t337.{core::Set::add}(i as{TypeError,ForDynamic} core::int*);
     #t337.{core::Set::add}(null);
   } =>#t337;
   core::Map<core::String*, core::int*>* map120 = block {
     final core::Map<core::String*, core::int*>* #t338 = <core::String*, core::int*>{};
-    for (dynamic i in dynVar as{TypeError} core::Iterable<dynamic>*)
-      #t338.{core::Map::[]=}("bar", i as{TypeError} core::int*);
+    for (dynamic i in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
+      #t338.{core::Map::[]=}("bar", i as{TypeError,ForDynamic} core::int*);
     #t338.{core::Map::[]=}("baz", null);
   } =>#t338;
   core::List<core::int*>* list130 = block {
@@ -1810,14 +1810,14 @@
 static method testForElementErrors(core::Map<core::int*, core::int*>* map, core::List<core::int*>* list) → dynamic async {
   block {
     final core::List<core::int*>* #t342 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t342.{core::List::add}(let final<BottomType> #t343 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:210:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) \"bar\"];
                                             ^" in "bar" as{TypeError} core::int*);
   } =>#t342;
   block {
     final core::Set<core::int*>* #t344 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t344.{core::Set::add}(let final<BottomType> #t345 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:211:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\", null};
                                             ^" in "bar" as{TypeError} core::int*);
@@ -1825,7 +1825,7 @@
   } =>#t344;
   block {
     final core::Map<core::int*, core::int*>* #t346 = <core::int*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t346.{core::Map::[]=}(let final<BottomType> #t347 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:212:50: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\": \"bar\", \"baz\": null};
                                                  ^" in "bar" as{TypeError} core::int*, let final<BottomType> #t348 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:212:57: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -1837,7 +1837,7 @@
   } =>#t346;
   block {
     final core::List<core::int*>* #t350 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t351 in <core::int*>[let final<BottomType> #t352 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:213:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"]];
                                                 ^" in "bar" as{TypeError} core::int*])
@@ -1845,7 +1845,7 @@
   } =>#t350;
   block {
     final core::Set<core::int*>* #t353 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t354 in <core::int*>[let final<BottomType> #t355 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:214:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"], null};
                                                 ^" in "bar" as{TypeError} core::int*])
@@ -1854,7 +1854,7 @@
   } =>#t353;
   block {
     final core::Map<core::int*, core::int*>* #t356 = <core::int*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::int*, core::int*>* #t357 in <core::int*, core::int*>{let final<BottomType> #t358 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:215:54: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) ...{\"bar\": \"bar\"}, \"baz\": null};
                                                      ^" in "bar" as{TypeError} core::int*: let final<BottomType> #t359 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:215:61: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -1867,7 +1867,7 @@
   } =>#t356;
   block {
     final core::List<core::int*>* #t361 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t361.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:216:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...map];
@@ -1875,7 +1875,7 @@
   } =>#t361;
   block {
     final core::Set<core::int*>* #t362 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t362.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:217:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...map, null};
@@ -1891,8 +1891,8 @@
                                                     ^": null};
   block {
     final core::List<core::String*>* #t363 = <core::String*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t363.{core::List::add}(let final<BottomType> #t364 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:219:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14];
                                                              ^" in 42 as{TypeError} core::String*);
@@ -1903,8 +1903,8 @@
   } =>#t363;
   block {
     final core::Set<core::String*>* #t366 = col::LinkedHashSet::•<core::String*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t366.{core::Set::add}(let final<BottomType> #t367 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:220:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14, null};
                                                              ^" in 42 as{TypeError} core::String*);
@@ -1916,8 +1916,8 @@
   } =>#t366;
   block {
     final core::Map<core::String*, core::String*>* #t369 = <core::String*, core::String*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t369.{core::Map::[]=}("bar", let final<BottomType> #t370 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:221:77: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) \"bar\": 42 else \"bar\": 3.14, \"baz\": null};
                                                                             ^" in 42 as{TypeError} core::String*);
@@ -1929,8 +1929,8 @@
   } =>#t369;
   block {
     final core::List<core::int*>* #t372 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t372.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:222:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42];
@@ -1940,8 +1940,8 @@
   } =>#t372;
   block {
     final core::Set<core::int*>* #t373 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t373.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:223:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42, null};
@@ -1959,8 +1959,8 @@
                                                                      ^": null};
   block {
     final core::List<core::int*>* #t374 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t374.{core::List::add}(42);
       else
         #t374.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:225:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -1970,8 +1970,8 @@
   } =>#t374;
   block {
     final core::Set<core::int*>* #t375 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t375.{core::Set::add}(42);
       else
         #t375.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:226:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
diff --git a/pkg/front_end/testcases/general/control_flow_collection_inference.dart.strong.transformed.expect b/pkg/front_end/testcases/general/control_flow_collection_inference.dart.strong.transformed.expect
index 82dc289..6dbb29f 100644
--- a/pkg/front_end/testcases/general/control_flow_collection_inference.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/control_flow_collection_inference.dart.strong.transformed.expect
@@ -444,58 +444,58 @@
 static method testIfElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::Map<core::String*, core::int*>* mapToInt, core::Map<core::String*, core::double*>* mapToDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(42);
   } =>#t1;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(42);
     #t2.{core::Set::add}(null);
   } =>#t2;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t3 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}("bar", 42);
     #t3.{core::Map::[]=}("baz", null);
   } =>#t3;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t4 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t4.{core::List::add}(dynVar);
   } =>#t4;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t5 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t5.{core::Set::add}(dynVar);
     #t5.{core::Set::add}(null);
   } =>#t5;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t6 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t6.{core::Map::[]=}("bar", dynVar);
     #t6.{core::Map::[]=}("baz", null);
   } =>#t6;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t7 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t7.{core::List::add}(<core::int*>[42]);
   } =>#t7;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t8 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t8.{core::Set::add}(<core::int*>[42]);
     #t8.{core::Set::add}(null);
   } =>#t8;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t9 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t9.{core::Map::[]=}("bar", <core::int*>[42]);
     #t9.{core::Map::[]=}("baz", null);
   } =>#t9;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t10 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t11 = :sync-for-iterator.{core::Iterator::current};
@@ -505,7 +505,7 @@
   } =>#t10;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t12 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t13 = :sync-for-iterator.{core::Iterator::current};
@@ -516,7 +516,7 @@
   } =>#t12;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t14 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t15 = :sync-for-iterator.{core::Iterator::current};
@@ -527,7 +527,7 @@
   } =>#t14;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t16 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t17 = :sync-for-iterator.{core::Iterator::current};
@@ -537,7 +537,7 @@
   } =>#t16;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t18 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t19 = :sync-for-iterator.{core::Iterator::current};
@@ -548,7 +548,7 @@
   } =>#t18;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t20 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, dynamic>* #t21 = :sync-for-iterator.{core::Iterator::current};
@@ -559,7 +559,7 @@
   } =>#t20;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t22 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t23 = :sync-for-iterator.{core::Iterator::current};
@@ -569,7 +569,7 @@
   } =>#t22;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t24 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t25 = :sync-for-iterator.{core::Iterator::current};
@@ -580,7 +580,7 @@
   } =>#t24;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t26 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t27 = :sync-for-iterator.{core::Iterator::current};
@@ -591,8 +591,8 @@
   } =>#t26;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t28 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t29 = :sync-for-iterator.{core::Iterator::current};
@@ -602,8 +602,8 @@
   } =>#t28;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t30 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t31 = :sync-for-iterator.{core::Iterator::current};
@@ -614,8 +614,8 @@
   } =>#t30;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t32 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::int*>* #t33 = :sync-for-iterator.{core::Iterator::current};
@@ -626,8 +626,8 @@
   } =>#t32;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t34 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t35 = :sync-for-iterator.{core::Iterator::current};
@@ -637,8 +637,8 @@
   } =>#t34;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t36 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t37 = :sync-for-iterator.{core::Iterator::current};
@@ -649,8 +649,8 @@
   } =>#t36;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t38 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, dynamic>* #t39 = :sync-for-iterator.{core::Iterator::current};
@@ -661,8 +661,8 @@
   } =>#t38;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t40 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t41 = :sync-for-iterator.{core::Iterator::current};
@@ -672,8 +672,8 @@
   } =>#t40;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t42 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t43 = :sync-for-iterator.{core::Iterator::current};
@@ -684,8 +684,8 @@
   } =>#t42;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t44 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t45 = :sync-for-iterator.{core::Iterator::current};
@@ -696,7 +696,7 @@
   } =>#t44;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t46 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t47 = :sync-for-iterator.{core::Iterator::current};
@@ -706,7 +706,7 @@
   } =>#t46;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t48 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t49 = :sync-for-iterator.{core::Iterator::current};
@@ -720,7 +720,7 @@
                                  ^";
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t50 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t51 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t52 = #t51.{core::Set::add}(<core::int*>[]) in #t51).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t53 = :sync-for-iterator.{core::Iterator::current};
@@ -730,7 +730,7 @@
   } =>#t50;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t54 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t55 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t56 = #t55.{core::Set::add}(<core::int*>[]) in #t55).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t57 = :sync-for-iterator.{core::Iterator::current};
@@ -741,8 +741,8 @@
   } =>#t54;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t58 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t59 = :sync-for-iterator.{core::Iterator::current};
@@ -752,8 +752,8 @@
   } =>#t58;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t60 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t61 = :sync-for-iterator.{core::Iterator::current};
@@ -764,8 +764,8 @@
   } =>#t60;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t62 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t63 = :sync-for-iterator.{core::Iterator::current};
@@ -776,7 +776,7 @@
   } =>#t62;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t64 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t65 = :sync-for-iterator.{core::Iterator::current};
@@ -786,7 +786,7 @@
   } =>#t64;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t67 = :sync-for-iterator.{core::Iterator::current};
@@ -797,7 +797,7 @@
   } =>#t66;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t68 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t69 = :sync-for-iterator.{core::Iterator::current};
@@ -808,7 +808,7 @@
   } =>#t68;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t70 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t71 = col::LinkedHashSet::•<core::int*>() in #t71).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t72 = :sync-for-iterator.{core::Iterator::current};
@@ -818,7 +818,7 @@
   } =>#t70;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t73 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t74 = col::LinkedHashSet::•<core::int*>() in #t74).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t75 = :sync-for-iterator.{core::Iterator::current};
@@ -829,8 +829,8 @@
   } =>#t73;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t76 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t77 = :sync-for-iterator.{core::Iterator::current};
@@ -840,8 +840,8 @@
   } =>#t76;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t78 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t79 = :sync-for-iterator.{core::Iterator::current};
@@ -852,8 +852,8 @@
   } =>#t78;
   core::Map<core::String*, core::int*>* map52 = block {
     final core::Map<core::String*, core::int*>* #t80 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::int*>* #t81 = :sync-for-iterator.{core::Iterator::current};
@@ -864,7 +864,7 @@
   } =>#t80;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t82 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t83 = :sync-for-iterator.{core::Iterator::current};
@@ -874,7 +874,7 @@
   } =>#t82;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t84 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t85 = :sync-for-iterator.{core::Iterator::current};
@@ -885,7 +885,7 @@
   } =>#t84;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t86 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t87 = :sync-for-iterator.{core::Iterator::current};
@@ -896,8 +896,8 @@
   } =>#t86;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t88 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t89 = :sync-for-iterator.{core::Iterator::current};
@@ -907,8 +907,8 @@
   } =>#t88;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t90 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t91 = :sync-for-iterator.{core::Iterator::current};
@@ -919,8 +919,8 @@
   } =>#t90;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t92 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t93 = :sync-for-iterator.{core::Iterator::current};
@@ -931,38 +931,38 @@
   } =>#t92;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t94 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t94.{core::List::add}(<core::int*>[]);
   } =>#t94;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t95 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t95.{core::Set::add}(<core::int*>[]);
     #t95.{core::Set::add}(null);
   } =>#t95;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t96 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t96.{core::List::add}(<core::int*>[]);
   } =>#t96;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t97 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t97.{core::Set::add}(<core::int*>[]);
     #t97.{core::Set::add}(null);
   } =>#t97;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t98 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t98.{core::List::add}(42);
     else
       #t98.{core::List::add}(3.14);
   } =>#t98;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t99 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t99.{core::Set::add}(42);
     else
       #t99.{core::Set::add}(3.14);
@@ -970,7 +970,7 @@
   } =>#t99;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t100 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t100.{core::Map::[]=}("bar", 42);
     else
       #t100.{core::Map::[]=}("bar", 3.14);
@@ -978,7 +978,7 @@
   } =>#t100;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t101 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::num* #t102 = :sync-for-iterator.{core::Iterator::current};
@@ -995,7 +995,7 @@
   } =>#t101;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t104 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::num* #t105 = :sync-for-iterator.{core::Iterator::current};
@@ -1013,7 +1013,7 @@
   } =>#t104;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t107 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapToInt.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::num*>* #t108 = :sync-for-iterator.{core::Iterator::current};
@@ -1031,7 +1031,7 @@
   } =>#t107;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t110 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t111 = :sync-for-iterator.{core::Iterator::current};
@@ -1039,7 +1039,7 @@
       }
     }
     else {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t112 = :sync-for-iterator.{core::Iterator::current};
         #t110.{core::List::add}(#t112);
@@ -1048,7 +1048,7 @@
   } =>#t110;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t113 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t114 = :sync-for-iterator.{core::Iterator::current};
@@ -1056,7 +1056,7 @@
       }
     }
     else {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t115 = :sync-for-iterator.{core::Iterator::current};
         #t113.{core::Set::add}(#t115);
@@ -1066,13 +1066,13 @@
   } =>#t113;
   core::Set<dynamic>* map82 = block {
     final core::Set<dynamic>* #t116 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t116.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:71:38: Error: Unexpected type 'Map<String, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   var map82 = {if (oracle(\"foo\")) ...mapToInt else ...dynVar, null};
                                      ^");
     else {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t117 = :sync-for-iterator.{core::Iterator::current};
         #t116.{core::Set::add}(#t117);
@@ -1082,7 +1082,7 @@
   } =>#t116;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t118 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t118.{core::List::add}(42);
     else {
       core::Iterator<core::double*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::double*>*>(listDouble).{core::Iterable::iterator};
@@ -1094,7 +1094,7 @@
   } =>#t118;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t120 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::num* #t121 = :sync-for-iterator.{core::Iterator::current};
@@ -1107,7 +1107,7 @@
   } =>#t120;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t122 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapToInt.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::num*>* #t123 = :sync-for-iterator.{core::Iterator::current};
@@ -1120,25 +1120,25 @@
   } =>#t122;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t124 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t124.{core::List::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t124.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t124;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t125 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t125.{core::Set::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t125.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t125.{core::Set::add}(null);
   } =>#t125;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t126 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t126.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t126.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t126.{core::Map::[]=}("baz", null);
   } =>#t126;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t127 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t128 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -1150,8 +1150,8 @@
   } =>#t127;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t130 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t131 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -1164,8 +1164,8 @@
   } =>#t130;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t133 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t134 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -1179,31 +1179,31 @@
   } =>#t133;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t137 = <core::int*>[];
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t137.{core::List::add}(42);
   } =>#t137;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t138 = col::LinkedHashSet::•<core::int*>();
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t138.{core::Set::add}(42);
   } =>#t138;
   core::Map<core::int*, core::int*>* map100 = block {
     final core::Map<core::int*, core::int*>* #t139 = <core::int*, core::int*>{};
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t139.{core::Map::[]=}(42, 42);
   } =>#t139;
 }
 static method testIfElementErrors(core::Map<core::int*, core::int*>* map) → dynamic {
   block {
     final core::List<core::int*>* #t140 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t140.{core::List::add}(let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:87:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) \"bar\"];
                            ^" in "bar" as{TypeError} core::int*);
   } =>#t140;
   block {
     final core::Set<core::int*>* #t142 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t142.{core::Set::add}(let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:88:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) \"bar\", null};
                            ^" in "bar" as{TypeError} core::int*);
@@ -1211,7 +1211,7 @@
   } =>#t142;
   block {
     final core::Map<core::String*, core::int*>* #t144 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t144.{core::Map::[]=}("bar", let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:89:43: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) \"bar\": \"bar\", \"baz\": null};
                                           ^" in "bar" as{TypeError} core::int*);
@@ -1219,7 +1219,7 @@
   } =>#t144;
   block {
     final core::List<core::int*>* #t146 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:90:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) ...[\"bar\"]];
                                ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -1231,7 +1231,7 @@
   } =>#t146;
   block {
     final core::Set<core::int*>* #t149 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:91:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) ...[\"bar\"], null};
                                ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -1244,7 +1244,7 @@
   } =>#t149;
   block {
     final core::Map<core::String*, core::int*>* #t152 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:92:47: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) ...{\"bar\": \"bar\"}, \"baz\": null};
                                               ^" in "bar" as{TypeError} core::int*}.{core::Map::entries}).{core::Iterable::iterator};
@@ -1257,7 +1257,7 @@
   } =>#t152;
   block {
     final core::List<core::int*>* #t155 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t155.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:93:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map];
@@ -1265,7 +1265,7 @@
   } =>#t155;
   block {
     final core::Set<core::int*>* #t156 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t156.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:94:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map, null};
@@ -1281,7 +1281,7 @@
                                       ^": null};
   block {
     final core::List<core::String*>* #t157 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t157.{core::List::add}(let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:96:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[if (oracle(\"foo\")) 42 else 3.14];
                               ^" in 42 as{TypeError} core::String*);
@@ -1292,7 +1292,7 @@
   } =>#t157;
   block {
     final core::Set<core::String*>* #t160 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t160.{core::Set::add}(let final<BottomType> #t161 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:97:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{if (oracle(\"foo\")) 42 else 3.14, null};
                               ^" in 42 as{TypeError} core::String*);
@@ -1304,7 +1304,7 @@
   } =>#t160;
   block {
     final core::Map<core::String*, core::String*>* #t163 = <core::String*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t163.{core::Map::[]=}("bar", let final<BottomType> #t164 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:98:46: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{if (oracle(\"foo\")) \"bar\": 42 else \"baz\": 3.14, \"baz\": null};
                                              ^" in 42 as{TypeError} core::String*);
@@ -1316,7 +1316,7 @@
   } =>#t163;
   block {
     final core::List<core::int*>* #t166 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t166.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:99:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map else 42];
@@ -1326,7 +1326,7 @@
   } =>#t166;
   block {
     final core::Set<core::int*>* #t167 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t167.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:100:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1344,7 +1344,7 @@
                                       ^": null};
   block {
     final core::List<core::int*>* #t168 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t168.{core::List::add}(42);
     else
       #t168.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:102:39: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -1354,7 +1354,7 @@
   } =>#t168;
   block {
     final core::Set<core::int*>* #t169 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t169.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:103:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1411,7 +1411,7 @@
   } =>#t174;
   core::List<core::String*>* list40 = block {
     final core::List<core::String*>* #t176 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t176.{core::List::add}(let final<BottomType> #t177 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:115:53: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   List<String> list40 = <String>[if (oracle(\"foo\")) true else 42];
                                                     ^" in true as{TypeError} core::String*);
@@ -1422,7 +1422,7 @@
   } =>#t176;
   core::Set<core::String*>* set40 = block {
     final core::Set<core::String*>* #t179 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t179.{core::Set::add}(let final<BottomType> #t180 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:116:51: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Set<String> set40 = <String>{if (oracle(\"foo\")) true else 42};
                                                   ^" in true as{TypeError} core::String*);
@@ -1433,7 +1433,7 @@
   } =>#t179;
   core::Map<core::String*, core::int*>* map40 = block {
     final core::Map<core::String*, core::int*>* #t182 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t182.{core::Map::[]=}(let final<BottomType> #t183 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:117:61: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<String, int> map40 = <String, int>{if (oracle(\"foo\")) true: 42 else 42: 42};
                                                             ^" in true as{TypeError} core::String*, 42);
@@ -1444,7 +1444,7 @@
   } =>#t182;
   core::Map<core::int*, core::String*>* map41 = block {
     final core::Map<core::int*, core::String*>* #t185 = <core::int*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t185.{core::Map::[]=}(42, let final<BottomType> #t186 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:118:65: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<int, String> map41 = <int, String>{if (oracle(\"foo\")) 42: true else 42: 42};
                                                                 ^" in true as{TypeError} core::String*);
@@ -1457,58 +1457,58 @@
 static method testForElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::int* index, core::Map<core::String*, core::int*>* mapStringInt, core::Map<core::String*, core::double*>* mapStringDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t188 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t188.{core::List::add}(42);
   } =>#t188;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t189 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t189.{core::Set::add}(42);
     #t189.{core::Set::add}(null);
   } =>#t189;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t190 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t190.{core::Map::[]=}("bar", 42);
     #t190.{core::Map::[]=}("baz", null);
   } =>#t190;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t191 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t191.{core::List::add}(dynVar);
   } =>#t191;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t192 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t192.{core::Set::add}(dynVar);
     #t192.{core::Set::add}(null);
   } =>#t192;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t193 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t193.{core::Map::[]=}("bar", dynVar);
     #t193.{core::Map::[]=}("baz", null);
   } =>#t193;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t194 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t194.{core::List::add}(<core::int*>[42]);
   } =>#t194;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t195 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t195.{core::Set::add}(<core::int*>[42]);
     #t195.{core::Set::add}(null);
   } =>#t195;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t196 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t196.{core::Map::[]=}("bar", <core::int*>[42]);
     #t196.{core::Map::[]=}("baz", null);
   } =>#t196;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t197 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t198 = :sync-for-iterator.{core::Iterator::current};
@@ -1518,7 +1518,7 @@
   } =>#t197;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t199 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t200 = :sync-for-iterator.{core::Iterator::current};
@@ -1529,7 +1529,7 @@
   } =>#t199;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t201 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t202 = :sync-for-iterator.{core::Iterator::current};
@@ -1540,7 +1540,7 @@
   } =>#t201;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t203 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t204 = :sync-for-iterator.{core::Iterator::current};
@@ -1550,7 +1550,7 @@
   } =>#t203;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t205 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t206 = :sync-for-iterator.{core::Iterator::current};
@@ -1561,7 +1561,7 @@
   } =>#t205;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t207 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, dynamic>* #t208 = :sync-for-iterator.{core::Iterator::current};
@@ -1572,7 +1572,7 @@
   } =>#t207;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t209 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t210 = :sync-for-iterator.{core::Iterator::current};
@@ -1582,7 +1582,7 @@
   } =>#t209;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t211 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t212 = :sync-for-iterator.{core::Iterator::current};
@@ -1593,7 +1593,7 @@
   } =>#t211;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t213 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t214 = :sync-for-iterator.{core::Iterator::current};
@@ -1604,8 +1604,8 @@
   } =>#t213;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t215 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t216 = :sync-for-iterator.{core::Iterator::current};
@@ -1615,8 +1615,8 @@
   } =>#t215;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t217 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t218 = :sync-for-iterator.{core::Iterator::current};
@@ -1627,8 +1627,8 @@
   } =>#t217;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t219 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::int*>* #t220 = :sync-for-iterator.{core::Iterator::current};
@@ -1639,8 +1639,8 @@
   } =>#t219;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t221 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t222 = :sync-for-iterator.{core::Iterator::current};
@@ -1650,8 +1650,8 @@
   } =>#t221;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t223 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t224 = :sync-for-iterator.{core::Iterator::current};
@@ -1662,8 +1662,8 @@
   } =>#t223;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t225 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, dynamic>* #t226 = :sync-for-iterator.{core::Iterator::current};
@@ -1674,8 +1674,8 @@
   } =>#t225;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t227 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t228 = :sync-for-iterator.{core::Iterator::current};
@@ -1685,8 +1685,8 @@
   } =>#t227;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t229 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t230 = :sync-for-iterator.{core::Iterator::current};
@@ -1697,8 +1697,8 @@
   } =>#t229;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t231 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t232 = :sync-for-iterator.{core::Iterator::current};
@@ -1709,7 +1709,7 @@
   } =>#t231;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t233 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t234 = :sync-for-iterator.{core::Iterator::current};
@@ -1719,7 +1719,7 @@
   } =>#t233;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t235 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t236 = :sync-for-iterator.{core::Iterator::current};
@@ -1730,7 +1730,7 @@
   } =>#t235;
   core::Map<core::String*, core::List<core::int*>*>* map40 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t237 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t238 = :sync-for-iterator.{core::Iterator::current};
@@ -1741,7 +1741,7 @@
   } =>#t237;
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t239 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t240 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t241 = #t240.{core::Set::add}(<core::int*>[]) in #t240).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t242 = :sync-for-iterator.{core::Iterator::current};
@@ -1751,7 +1751,7 @@
   } =>#t239;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t243 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t244 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t245 = #t244.{core::Set::add}(<core::int*>[]) in #t244).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t246 = :sync-for-iterator.{core::Iterator::current};
@@ -1762,8 +1762,8 @@
   } =>#t243;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t247 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t248 = :sync-for-iterator.{core::Iterator::current};
@@ -1773,8 +1773,8 @@
   } =>#t247;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t249 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t250 = :sync-for-iterator.{core::Iterator::current};
@@ -1785,8 +1785,8 @@
   } =>#t249;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t251 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t252 = :sync-for-iterator.{core::Iterator::current};
@@ -1797,7 +1797,7 @@
   } =>#t251;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t253 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t254 = :sync-for-iterator.{core::Iterator::current};
@@ -1807,7 +1807,7 @@
   } =>#t253;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t255 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t256 = :sync-for-iterator.{core::Iterator::current};
@@ -1818,7 +1818,7 @@
   } =>#t255;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t257 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t258 = :sync-for-iterator.{core::Iterator::current};
@@ -1829,7 +1829,7 @@
   } =>#t257;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t259 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t260 = col::LinkedHashSet::•<core::int*>() in #t260).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t261 = :sync-for-iterator.{core::Iterator::current};
@@ -1839,7 +1839,7 @@
   } =>#t259;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t262 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t263 = col::LinkedHashSet::•<core::int*>() in #t263).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t264 = :sync-for-iterator.{core::Iterator::current};
@@ -1850,8 +1850,8 @@
   } =>#t262;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t265 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t266 = :sync-for-iterator.{core::Iterator::current};
@@ -1861,8 +1861,8 @@
   } =>#t265;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t267 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t268 = :sync-for-iterator.{core::Iterator::current};
@@ -1873,7 +1873,7 @@
   } =>#t267;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t269 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t270 = :sync-for-iterator.{core::Iterator::current};
@@ -1883,7 +1883,7 @@
   } =>#t269;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t271 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t272 = :sync-for-iterator.{core::Iterator::current};
@@ -1894,7 +1894,7 @@
   } =>#t271;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t273 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t274 = :sync-for-iterator.{core::Iterator::current};
@@ -1905,8 +1905,8 @@
   } =>#t273;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t275 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t276 = :sync-for-iterator.{core::Iterator::current};
@@ -1916,8 +1916,8 @@
   } =>#t275;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t277 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t278 = :sync-for-iterator.{core::Iterator::current};
@@ -1928,8 +1928,8 @@
   } =>#t277;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t279 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t280 = :sync-for-iterator.{core::Iterator::current};
@@ -1940,53 +1940,53 @@
   } =>#t279;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t281 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t281.{core::List::add}(<core::int*>[]);
   } =>#t281;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t282 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t282.{core::Set::add}(<core::int*>[]);
     #t282.{core::Set::add}(null);
   } =>#t282;
   core::Map<core::String*, core::List<core::int*>*>* map70 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t283 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t283.{core::Map::[]=}("bar", <core::int*>[]);
     #t283.{core::Map::[]=}("baz", null);
   } =>#t283;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t284 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t284.{core::List::add}(<core::int*>[]);
   } =>#t284;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t285 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t285.{core::Set::add}(<core::int*>[]);
     #t285.{core::Set::add}(null);
   } =>#t285;
   core::Map<core::String*, core::List<core::int*>*>* map71 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t286 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t286.{core::Map::[]=}("bar", <core::int*>[]);
     #t286.{core::Map::[]=}("baz", null);
   } =>#t286;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t287 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t287.{core::List::add}(42);
       else
         #t287.{core::List::add}(3.14);
   } =>#t287;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t288 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t288.{core::Set::add}(42);
       else
         #t288.{core::Set::add}(3.14);
@@ -1994,8 +1994,8 @@
   } =>#t288;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t289 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t289.{core::Map::[]=}("bar", 42);
       else
         #t289.{core::Map::[]=}("bar", 3.14);
@@ -2003,8 +2003,8 @@
   } =>#t289;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t290 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::num* #t291 = :sync-for-iterator.{core::Iterator::current};
@@ -2021,8 +2021,8 @@
   } =>#t290;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t293 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::num* #t294 = :sync-for-iterator.{core::Iterator::current};
@@ -2040,8 +2040,8 @@
   } =>#t293;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t296 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapStringInt.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::num*>* #t297 = :sync-for-iterator.{core::Iterator::current};
@@ -2059,8 +2059,8 @@
   } =>#t296;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t299 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t300 = :sync-for-iterator.{core::Iterator::current};
@@ -2068,7 +2068,7 @@
         }
       }
       else {
-        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t301 = :sync-for-iterator.{core::Iterator::current};
           #t299.{core::List::add}(#t301);
@@ -2077,8 +2077,8 @@
   } =>#t299;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t302 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t303 = :sync-for-iterator.{core::Iterator::current};
@@ -2086,7 +2086,7 @@
         }
       }
       else {
-        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t304 = :sync-for-iterator.{core::Iterator::current};
           #t302.{core::Set::add}(#t304);
@@ -2096,8 +2096,8 @@
   } =>#t302;
   core::Map<dynamic, dynamic>* map82 = block {
     final core::Map<dynamic, dynamic>* #t305 = <dynamic, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapStringInt.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<dynamic, dynamic>* #t306 = :sync-for-iterator.{core::Iterator::current};
@@ -2105,7 +2105,7 @@
         }
       }
       else {
-        core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+        core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<dynamic, dynamic>* #t307 = :sync-for-iterator.{core::Iterator::current};
           #t305.{core::Map::[]=}(#t307.{core::MapEntry::key}, #t307.{core::MapEntry::value});
@@ -2115,8 +2115,8 @@
   } =>#t305;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t308 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t308.{core::List::add}(42);
       else {
         core::Iterator<core::double*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::double*>*>(listDouble).{core::Iterable::iterator};
@@ -2128,8 +2128,8 @@
   } =>#t308;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t310 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::num* #t311 = :sync-for-iterator.{core::Iterator::current};
@@ -2142,8 +2142,8 @@
   } =>#t310;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t312 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapStringInt.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::num*>* #t313 = :sync-for-iterator.{core::Iterator::current};
@@ -2156,25 +2156,25 @@
   } =>#t312;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t314 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t314.{core::List::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t314.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t314;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t315 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t315.{core::Set::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t315.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t315.{core::Set::add}(null);
   } =>#t315;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t316 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t316.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t316.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t316.{core::Map::[]=}("baz", null);
   } =>#t316;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t317 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t318 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -2186,8 +2186,8 @@
   } =>#t317;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t320 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t321 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -2200,8 +2200,8 @@
   } =>#t320;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t323 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t324 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -2215,17 +2215,17 @@
   } =>#t323;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t327 = <core::int*>[];
-    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t327.{core::List::add}(42);
   } =>#t327;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t329 = col::LinkedHashSet::•<core::int*>();
-    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t329.{core::Set::add}(42);
   } =>#t329;
   core::Map<core::String*, core::int*>* map100 = block {
     final core::Map<core::String*, core::int*>* #t331 = <core::String*, core::int*>{};
-    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t331.{core::Map::[]=}("bar", 42);
   } =>#t331;
   core::List<core::int*>* list110 = block {
@@ -2263,20 +2263,20 @@
   core::List<core::int*>* list120 = block {
     final core::List<core::int*>* #t336 = <core::int*>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         dynamic i = :sync-for-iterator.{core::Iterator::current};
-        #t336.{core::List::add}(i as{TypeError} core::int*);
+        #t336.{core::List::add}(i as{TypeError,ForDynamic} core::int*);
       }
     }
   } =>#t336;
   core::Set<core::int*>* set120 = block {
     final core::Set<core::int*>* #t337 = col::LinkedHashSet::•<core::int*>();
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         dynamic i = :sync-for-iterator.{core::Iterator::current};
-        #t337.{core::Set::add}(i as{TypeError} core::int*);
+        #t337.{core::Set::add}(i as{TypeError,ForDynamic} core::int*);
       }
     }
     #t337.{core::Set::add}(null);
@@ -2284,10 +2284,10 @@
   core::Map<core::String*, core::int*>* map120 = block {
     final core::Map<core::String*, core::int*>* #t338 = <core::String*, core::int*>{};
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         dynamic i = :sync-for-iterator.{core::Iterator::current};
-        #t338.{core::Map::[]=}("bar", i as{TypeError} core::int*);
+        #t338.{core::Map::[]=}("bar", i as{TypeError,ForDynamic} core::int*);
       }
     }
     #t338.{core::Map::[]=}("baz", null);
@@ -2326,14 +2326,14 @@
       {
         block {
           final core::List<core::int*>* #t342 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t342.{core::List::add}(let final<BottomType> #t343 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:210:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) \"bar\"];
                                             ^" in "bar" as{TypeError} core::int*);
         } =>#t342;
         block {
           final core::Set<core::int*>* #t344 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t344.{core::Set::add}(let final<BottomType> #t345 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:211:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\", null};
                                             ^" in "bar" as{TypeError} core::int*);
@@ -2341,7 +2341,7 @@
         } =>#t344;
         block {
           final core::Map<core::int*, core::int*>* #t346 = <core::int*, core::int*>{};
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t346.{core::Map::[]=}(let final<BottomType> #t347 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:212:50: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\": \"bar\", \"baz\": null};
                                                  ^" in "bar" as{TypeError} core::int*, let final<BottomType> #t348 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:212:57: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -2353,7 +2353,7 @@
         } =>#t346;
         block {
           final core::List<core::int*>* #t350 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
             core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t351 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:213:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"]];
                                                 ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -2365,7 +2365,7 @@
         } =>#t350;
         block {
           final core::Set<core::int*>* #t353 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
             core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t354 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:214:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"], null};
                                                 ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -2378,7 +2378,7 @@
         } =>#t353;
         block {
           final core::Map<core::int*, core::int*>* #t356 = <core::int*, core::int*>{};
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
             core::Iterator<core::MapEntry<core::int*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::int*, core::int*>*>*>(<core::int*, core::int*>{let final<BottomType> #t357 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:215:54: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) ...{\"bar\": \"bar\"}, \"baz\": null};
                                                      ^" in "bar" as{TypeError} core::int*: let final<BottomType> #t358 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:215:61: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -2395,7 +2395,7 @@
         } =>#t356;
         block {
           final core::List<core::int*>* #t361 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t361.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:216:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...map];
@@ -2403,7 +2403,7 @@
         } =>#t361;
         block {
           final core::Set<core::int*>* #t362 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t362.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:217:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...map, null};
@@ -2419,8 +2419,8 @@
                                                     ^": null};
         block {
           final core::List<core::String*>* #t363 = <core::String*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t363.{core::List::add}(let final<BottomType> #t364 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:219:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14];
                                                              ^" in 42 as{TypeError} core::String*);
@@ -2431,8 +2431,8 @@
         } =>#t363;
         block {
           final core::Set<core::String*>* #t366 = col::LinkedHashSet::•<core::String*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t366.{core::Set::add}(let final<BottomType> #t367 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:220:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14, null};
                                                              ^" in 42 as{TypeError} core::String*);
@@ -2444,8 +2444,8 @@
         } =>#t366;
         block {
           final core::Map<core::String*, core::String*>* #t369 = <core::String*, core::String*>{};
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t369.{core::Map::[]=}("bar", let final<BottomType> #t370 = invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:221:77: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) \"bar\": 42 else \"bar\": 3.14, \"baz\": null};
                                                                             ^" in 42 as{TypeError} core::String*);
@@ -2457,8 +2457,8 @@
         } =>#t369;
         block {
           final core::List<core::int*>* #t372 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t372.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:222:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42];
@@ -2468,8 +2468,8 @@
         } =>#t372;
         block {
           final core::Set<core::int*>* #t373 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t373.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:223:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42, null};
@@ -2487,8 +2487,8 @@
                                                                      ^": null};
         block {
           final core::List<core::int*>* #t374 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t374.{core::List::add}(42);
             else
               #t374.{core::List::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:225:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -2498,8 +2498,8 @@
         } =>#t374;
         block {
           final core::Set<core::int*>* #t375 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t375.{core::Set::add}(42);
             else
               #t375.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general/control_flow_collection_inference.dart:226:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
diff --git a/pkg/front_end/testcases/general/covariant_generic.dart.strong.expect b/pkg/front_end/testcases/general/covariant_generic.dart.strong.expect
index d794499..4a73a4f 100644
--- a/pkg/front_end/testcases/general/covariant_generic.dart.strong.expect
+++ b/pkg/front_end/testcases/general/covariant_generic.dart.strong.expect
@@ -33,7 +33,7 @@
   fooNum.{self::Foo::withCallback}((core::num* x) → core::Null? {});
   fooNum.{self::Foo::mutableField} = 3;
   fooNum.{self::Foo::mutableField} = 2.5;
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(3);
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(2.5);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(3);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(2.5);
   fooNum.{self::Foo::mutableCallbackField} = (core::num* x) → core::Null? {};
 }
diff --git a/pkg/front_end/testcases/general/covariant_generic.dart.strong.transformed.expect b/pkg/front_end/testcases/general/covariant_generic.dart.strong.transformed.expect
index d794499..4a73a4f 100644
--- a/pkg/front_end/testcases/general/covariant_generic.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/covariant_generic.dart.strong.transformed.expect
@@ -33,7 +33,7 @@
   fooNum.{self::Foo::withCallback}((core::num* x) → core::Null? {});
   fooNum.{self::Foo::mutableField} = 3;
   fooNum.{self::Foo::mutableField} = 2.5;
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(3);
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(2.5);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(3);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(2.5);
   fooNum.{self::Foo::mutableCallbackField} = (core::num* x) → core::Null? {};
 }
diff --git a/pkg/front_end/testcases/general/invalid_operator.dart b/pkg/front_end/testcases/general/invalid_operator.dart
new file mode 100644
index 0000000..609f1b0
--- /dev/null
+++ b/pkg/front_end/testcases/general/invalid_operator.dart
@@ -0,0 +1,158 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class Operators1 {
+  operator ==() => true;
+  operator <() => true;
+  operator >() => true;
+  operator <=() => true;
+  operator >=() => true;
+  operator +() => true;
+  operator /() => true;
+  operator ~/() => true;
+  operator *() => true;
+  operator %() => true;
+  operator |() => true;
+  operator ^() => true;
+  operator &() => true;
+  operator <<() => true;
+  operator >>() => true;
+  operator []=(a, b, c) => true;
+  operator []() => true;
+  operator ~(a) => true;
+}
+
+class Operators2 {
+  operator ==(a, b) => true;
+  operator <(a, b) => true;
+  operator >(a, b) => true;
+  operator <=(a, b) => true;
+  operator >=(a, b) => true;
+  operator -(a, b) => true;
+  operator +(a, b) => true;
+  operator /(a, b) => true;
+  operator ~/(a, b) => true;
+  operator *(a, b) => true;
+  operator %(a, b) => true;
+  operator |(a, b) => true;
+  operator ^(a, b) => true;
+  operator &(a, b) => true;
+  operator <<(a, b) => true;
+  operator >>(a, b) => true;
+  operator []=(a, b, c) => true;
+  operator [](a, b) => true;
+  operator ~(a, b) => true;
+}
+
+class Operators3 {
+  operator ==([a]) => true;
+  operator <([a]) => true;
+  operator >([a]) => true;
+  operator <=([a]) => true;
+  operator >=([a]) => true;
+  operator -([a]) => true;
+  operator +([a]) => true;
+  operator /([a]) => true;
+  operator ~/([a]) => true;
+  operator *([a]) => true;
+  operator %([a]) => true;
+  operator |([a]) => true;
+  operator ^([a]) => true;
+  operator &([a]) => true;
+  operator <<([a]) => true;
+  operator >>([a]) => true;
+  operator []=([a, b]) => true;
+  operator []([a]) => true;
+  operator ~([a]) => true;
+}
+
+class Operators4 {
+  operator ==({a}) => true;
+  operator <({a}) => true;
+  operator >({a}) => true;
+  operator <=({a}) => true;
+  operator >=({a}) => true;
+  operator -({a}) => true;
+  operator +({a}) => true;
+  operator /({a}) => true;
+  operator ~/({a}) => true;
+  operator *({a}) => true;
+  operator %({a}) => true;
+  operator |({a}) => true;
+  operator ^({a}) => true;
+  operator &({a}) => true;
+  operator <<({a}) => true;
+  operator >>({a}) => true;
+  operator []=({a, b}) => true;
+  operator []({a}) => true;
+  operator ~({a}) => true;
+}
+
+class Operators5 {
+  operator ==(a, [b]) => true;
+  operator <(a, [b]) => true;
+  operator >(a, [b]) => true;
+  operator <=(a, [b]) => true;
+  operator >=(a, [b]) => true;
+  operator -(a, [b]) => true;
+  operator +(a, [b]) => true;
+  operator /(a, [b]) => true;
+  operator ~/(a, [b]) => true;
+  operator *(a, [b]) => true;
+  operator %(a, [b]) => true;
+  operator |(a, [b]) => true;
+  operator ^(a, [b]) => true;
+  operator &(a, [b]) => true;
+  operator <<(a, [b]) => true;
+  operator >>(a, [b]) => true;
+  operator []=(a, b, [c]) => true;
+  operator [](a, [b]) => true;
+  operator ~(a, [b]) => true;
+}
+
+class Operators6 {
+  operator ==(a, {b}) => true;
+  operator <(a, {b}) => true;
+  operator >(a, {b}) => true;
+  operator <=(a, {b}) => true;
+  operator >=(a, {b}) => true;
+  operator -(a, {b}) => true;
+  operator +(a, {b}) => true;
+  operator /(a, {b}) => true;
+  operator ~/(a, {b}) => true;
+  operator *(a, {b}) => true;
+  operator %(a, {b}) => true;
+  operator |(a, {b}) => true;
+  operator ^(a, {b}) => true;
+  operator &(a, {b}) => true;
+  operator <<(a, {b}) => true;
+  operator >>(a, {b}) => true;
+  operator []=(a, b, {c}) => true;
+  operator [](a, {b}) => true;
+  operator ~(a, {b}) => true;
+}
+
+class Operators7 {
+  operator ==<T>(a) => true;
+  operator ><T>(a) => true;
+  operator <=<T>(a) => true;
+  operator >=<T>(a) => true;
+  operator -<T>() => true;
+  operator -<T>(a) => true;
+  operator +<T>(a) => true;
+  operator /<T>(a) => true;
+  operator ~/<T>(a) => true;
+  operator *<T>(a) => true;
+  operator %<T>(a) => true;
+  operator |<T>(a) => true;
+  operator ^<T>(a) => true;
+  operator &<T>(a) => true;
+  operator <<<T>(a) => true;
+  operator >><T>(a) => true;
+  operator []=<T>(a, b) => true;
+  operator []<T>(a) => true;
+  operator ~<T>() => true;
+}
+
+main() {}
diff --git a/pkg/front_end/testcases/general/invalid_operator.dart.outline.expect b/pkg/front_end/testcases/general/invalid_operator.dart.outline.expect
new file mode 100644
index 0000000..fc36801
--- /dev/null
+++ b/pkg/front_end/testcases/general/invalid_operator.dart.outline.expect
@@ -0,0 +1,859 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:6:12: Error: Operator '==' should have exactly one parameter.
+//   operator ==() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:7:12: Error: Operator '<' should have exactly one parameter.
+//   operator <() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:8:12: Error: Operator '>' should have exactly one parameter.
+//   operator >() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:9:12: Error: Operator '<=' should have exactly one parameter.
+//   operator <=() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:10:12: Error: Operator '>=' should have exactly one parameter.
+//   operator >=() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:11:12: Error: Operator '+' should have exactly one parameter.
+//   operator +() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:12:12: Error: Operator '/' should have exactly one parameter.
+//   operator /() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:13:12: Error: Operator '~/' should have exactly one parameter.
+//   operator ~/() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:14:12: Error: Operator '*' should have exactly one parameter.
+//   operator *() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:15:12: Error: Operator '%' should have exactly one parameter.
+//   operator %() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:16:12: Error: Operator '|' should have exactly one parameter.
+//   operator |() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:17:12: Error: Operator '^' should have exactly one parameter.
+//   operator ^() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:18:12: Error: Operator '&' should have exactly one parameter.
+//   operator &() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:19:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:20:12: Error: Operator '>>' should have exactly one parameter.
+//   operator >>() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:21:12: Error: Operator '[]=' should have exactly two parameters.
+//   operator []=(a, b, c) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:22:12: Error: Operator '[]' should have exactly one parameter.
+//   operator []() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:23:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~(a) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:27:12: Error: Operator '==' should have exactly one parameter.
+//   operator ==(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:28:12: Error: Operator '<' should have exactly one parameter.
+//   operator <(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:29:12: Error: Operator '>' should have exactly one parameter.
+//   operator >(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:30:12: Error: Operator '<=' should have exactly one parameter.
+//   operator <=(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:31:12: Error: Operator '>=' should have exactly one parameter.
+//   operator >=(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:32:12: Error: Operator '-' should have zero or one parameter.
+// With zero parameters, it has the syntactic form '-a', formally known as 'unary-'. With one parameter, it has the syntactic form 'a - b', formally known as '-'.
+//   operator -(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:33:12: Error: Operator '+' should have exactly one parameter.
+//   operator +(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:34:12: Error: Operator '/' should have exactly one parameter.
+//   operator /(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:35:12: Error: Operator '~/' should have exactly one parameter.
+//   operator ~/(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:36:12: Error: Operator '*' should have exactly one parameter.
+//   operator *(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:37:12: Error: Operator '%' should have exactly one parameter.
+//   operator %(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:38:12: Error: Operator '|' should have exactly one parameter.
+//   operator |(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:39:12: Error: Operator '^' should have exactly one parameter.
+//   operator ^(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:40:12: Error: Operator '&' should have exactly one parameter.
+//   operator &(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:41:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:42:12: Error: Operator '>>' should have exactly one parameter.
+//   operator >>(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:43:12: Error: Operator '[]=' should have exactly two parameters.
+//   operator []=(a, b, c) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:44:12: Error: Operator '[]' should have exactly one parameter.
+//   operator [](a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:45:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:49:16: Error: An operator can't have optional parameters.
+//   operator ==([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:50:15: Error: An operator can't have optional parameters.
+//   operator <([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:51:15: Error: An operator can't have optional parameters.
+//   operator >([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:52:16: Error: An operator can't have optional parameters.
+//   operator <=([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:53:16: Error: An operator can't have optional parameters.
+//   operator >=([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:54:15: Error: An operator can't have optional parameters.
+//   operator -([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:55:15: Error: An operator can't have optional parameters.
+//   operator +([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:56:15: Error: An operator can't have optional parameters.
+//   operator /([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:57:16: Error: An operator can't have optional parameters.
+//   operator ~/([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:58:15: Error: An operator can't have optional parameters.
+//   operator *([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:59:15: Error: An operator can't have optional parameters.
+//   operator %([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:60:15: Error: An operator can't have optional parameters.
+//   operator |([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:61:15: Error: An operator can't have optional parameters.
+//   operator ^([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:62:15: Error: An operator can't have optional parameters.
+//   operator &([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:63:16: Error: An operator can't have optional parameters.
+//   operator <<([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:64:16: Error: An operator can't have optional parameters.
+//   operator >>([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:65:17: Error: An operator can't have optional parameters.
+//   operator []=([a, b]) => true;
+//                 ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:65:20: Error: An operator can't have optional parameters.
+//   operator []=([a, b]) => true;
+//                    ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:66:16: Error: An operator can't have optional parameters.
+//   operator []([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:67:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~([a]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:71:16: Error: An operator can't have optional parameters.
+//   operator ==({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:72:15: Error: An operator can't have optional parameters.
+//   operator <({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:73:15: Error: An operator can't have optional parameters.
+//   operator >({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:74:16: Error: An operator can't have optional parameters.
+//   operator <=({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:75:16: Error: An operator can't have optional parameters.
+//   operator >=({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:76:15: Error: An operator can't have optional parameters.
+//   operator -({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:77:15: Error: An operator can't have optional parameters.
+//   operator +({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:78:15: Error: An operator can't have optional parameters.
+//   operator /({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:79:16: Error: An operator can't have optional parameters.
+//   operator ~/({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:80:15: Error: An operator can't have optional parameters.
+//   operator *({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:81:15: Error: An operator can't have optional parameters.
+//   operator %({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:82:15: Error: An operator can't have optional parameters.
+//   operator |({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:83:15: Error: An operator can't have optional parameters.
+//   operator ^({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:84:15: Error: An operator can't have optional parameters.
+//   operator &({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:85:16: Error: An operator can't have optional parameters.
+//   operator <<({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:86:16: Error: An operator can't have optional parameters.
+//   operator >>({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:87:17: Error: An operator can't have optional parameters.
+//   operator []=({a, b}) => true;
+//                 ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:87:20: Error: An operator can't have optional parameters.
+//   operator []=({a, b}) => true;
+//                    ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:88:16: Error: An operator can't have optional parameters.
+//   operator []({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:89:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~({a}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:93:12: Error: Operator '==' should have exactly one parameter.
+//   operator ==(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:94:12: Error: Operator '<' should have exactly one parameter.
+//   operator <(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:95:12: Error: Operator '>' should have exactly one parameter.
+//   operator >(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:96:12: Error: Operator '<=' should have exactly one parameter.
+//   operator <=(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:97:12: Error: Operator '>=' should have exactly one parameter.
+//   operator >=(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:98:12: Error: Operator '-' should have zero or one parameter.
+// With zero parameters, it has the syntactic form '-a', formally known as 'unary-'. With one parameter, it has the syntactic form 'a - b', formally known as '-'.
+//   operator -(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:99:12: Error: Operator '+' should have exactly one parameter.
+//   operator +(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:100:12: Error: Operator '/' should have exactly one parameter.
+//   operator /(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:101:12: Error: Operator '~/' should have exactly one parameter.
+//   operator ~/(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:102:12: Error: Operator '*' should have exactly one parameter.
+//   operator *(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:103:12: Error: Operator '%' should have exactly one parameter.
+//   operator %(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:104:12: Error: Operator '|' should have exactly one parameter.
+//   operator |(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:105:12: Error: Operator '^' should have exactly one parameter.
+//   operator ^(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:106:12: Error: Operator '&' should have exactly one parameter.
+//   operator &(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:107:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:108:12: Error: Operator '>>' should have exactly one parameter.
+//   operator >>(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:109:12: Error: Operator '[]=' should have exactly two parameters.
+//   operator []=(a, b, [c]) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:110:12: Error: Operator '[]' should have exactly one parameter.
+//   operator [](a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:111:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:115:12: Error: Operator '==' should have exactly one parameter.
+//   operator ==(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:116:12: Error: Operator '<' should have exactly one parameter.
+//   operator <(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:117:12: Error: Operator '>' should have exactly one parameter.
+//   operator >(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:118:12: Error: Operator '<=' should have exactly one parameter.
+//   operator <=(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:119:12: Error: Operator '>=' should have exactly one parameter.
+//   operator >=(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:120:12: Error: Operator '-' should have zero or one parameter.
+// With zero parameters, it has the syntactic form '-a', formally known as 'unary-'. With one parameter, it has the syntactic form 'a - b', formally known as '-'.
+//   operator -(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:121:12: Error: Operator '+' should have exactly one parameter.
+//   operator +(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:122:12: Error: Operator '/' should have exactly one parameter.
+//   operator /(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:123:12: Error: Operator '~/' should have exactly one parameter.
+//   operator ~/(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:124:12: Error: Operator '*' should have exactly one parameter.
+//   operator *(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:125:12: Error: Operator '%' should have exactly one parameter.
+//   operator %(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:126:12: Error: Operator '|' should have exactly one parameter.
+//   operator |(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:127:12: Error: Operator '^' should have exactly one parameter.
+//   operator ^(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:128:12: Error: Operator '&' should have exactly one parameter.
+//   operator &(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:129:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:130:12: Error: Operator '>>' should have exactly one parameter.
+//   operator >>(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:131:12: Error: Operator '[]=' should have exactly two parameters.
+//   operator []=(a, b, {c}) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:132:12: Error: Operator '[]' should have exactly one parameter.
+//   operator [](a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:133:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:137:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator ==<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:138:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator ><T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:139:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator <=<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:140:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator >=<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:141:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator -<T>() => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:142:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator -<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:143:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator +<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:144:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator /<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:145:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator ~/<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:146:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator *<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:147:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator %<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:148:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator |<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:149:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator ^<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:150:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator &<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:151:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator <<<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:152:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator >><T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:153:16: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator []=<T>(a, b) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:154:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator []<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:155:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator ~<T>() => true;
+//              ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Operators1 extends core::Object {
+  synthetic constructor •() → self::Operators1*
+    ;
+  operator ==() → dynamic
+    ;
+  operator <() → dynamic
+    ;
+  operator >() → dynamic
+    ;
+  operator <=() → dynamic
+    ;
+  operator >=() → dynamic
+    ;
+  operator +() → dynamic
+    ;
+  operator /() → dynamic
+    ;
+  operator ~/() → dynamic
+    ;
+  operator *() → dynamic
+    ;
+  operator %() → dynamic
+    ;
+  operator |() → dynamic
+    ;
+  operator ^() → dynamic
+    ;
+  operator &() → dynamic
+    ;
+  operator <<() → dynamic
+    ;
+  operator >>() → dynamic
+    ;
+  operator []=(dynamic a, dynamic b, dynamic c) → void
+    ;
+  operator []() → dynamic
+    ;
+  operator ~(dynamic a) → dynamic
+    ;
+}
+class Operators2 extends core::Object {
+  synthetic constructor •() → self::Operators2*
+    ;
+  operator ==(dynamic a, dynamic b) → dynamic
+    ;
+  operator <(dynamic a, dynamic b) → dynamic
+    ;
+  operator >(dynamic a, dynamic b) → dynamic
+    ;
+  operator <=(dynamic a, dynamic b) → dynamic
+    ;
+  operator >=(dynamic a, dynamic b) → dynamic
+    ;
+  operator -(dynamic a, dynamic b) → dynamic
+    ;
+  operator +(dynamic a, dynamic b) → dynamic
+    ;
+  operator /(dynamic a, dynamic b) → dynamic
+    ;
+  operator ~/(dynamic a, dynamic b) → dynamic
+    ;
+  operator *(dynamic a, dynamic b) → dynamic
+    ;
+  operator %(dynamic a, dynamic b) → dynamic
+    ;
+  operator |(dynamic a, dynamic b) → dynamic
+    ;
+  operator ^(dynamic a, dynamic b) → dynamic
+    ;
+  operator &(dynamic a, dynamic b) → dynamic
+    ;
+  operator <<(dynamic a, dynamic b) → dynamic
+    ;
+  operator >>(dynamic a, dynamic b) → dynamic
+    ;
+  operator []=(dynamic a, dynamic b, dynamic c) → void
+    ;
+  operator [](dynamic a, dynamic b) → dynamic
+    ;
+  operator ~(dynamic a, dynamic b) → dynamic
+    ;
+}
+class Operators3 extends core::Object {
+  synthetic constructor •() → self::Operators3*
+    ;
+  operator ==([dynamic a]) → core::bool*
+    ;
+  operator <([dynamic a]) → dynamic
+    ;
+  operator >([dynamic a]) → dynamic
+    ;
+  operator <=([dynamic a]) → dynamic
+    ;
+  operator >=([dynamic a]) → dynamic
+    ;
+  operator -([dynamic a]) → dynamic
+    ;
+  operator +([dynamic a]) → dynamic
+    ;
+  operator /([dynamic a]) → dynamic
+    ;
+  operator ~/([dynamic a]) → dynamic
+    ;
+  operator *([dynamic a]) → dynamic
+    ;
+  operator %([dynamic a]) → dynamic
+    ;
+  operator |([dynamic a]) → dynamic
+    ;
+  operator ^([dynamic a]) → dynamic
+    ;
+  operator &([dynamic a]) → dynamic
+    ;
+  operator <<([dynamic a]) → dynamic
+    ;
+  operator >>([dynamic a]) → dynamic
+    ;
+  operator []=([dynamic a, dynamic b]) → void
+    ;
+  operator []([dynamic a]) → dynamic
+    ;
+  operator ~([dynamic a]) → dynamic
+    ;
+}
+class Operators4 extends core::Object {
+  synthetic constructor •() → self::Operators4*
+    ;
+  operator ==({dynamic a}) → dynamic
+    ;
+  operator <({dynamic a}) → dynamic
+    ;
+  operator >({dynamic a}) → dynamic
+    ;
+  operator <=({dynamic a}) → dynamic
+    ;
+  operator >=({dynamic a}) → dynamic
+    ;
+  operator -({dynamic a}) → dynamic
+    ;
+  operator +({dynamic a}) → dynamic
+    ;
+  operator /({dynamic a}) → dynamic
+    ;
+  operator ~/({dynamic a}) → dynamic
+    ;
+  operator *({dynamic a}) → dynamic
+    ;
+  operator %({dynamic a}) → dynamic
+    ;
+  operator |({dynamic a}) → dynamic
+    ;
+  operator ^({dynamic a}) → dynamic
+    ;
+  operator &({dynamic a}) → dynamic
+    ;
+  operator <<({dynamic a}) → dynamic
+    ;
+  operator >>({dynamic a}) → dynamic
+    ;
+  operator []=({dynamic a, dynamic b}) → void
+    ;
+  operator []({dynamic a}) → dynamic
+    ;
+  operator ~({dynamic a}) → dynamic
+    ;
+}
+class Operators5 extends core::Object {
+  synthetic constructor •() → self::Operators5*
+    ;
+  operator ==(dynamic a, [dynamic b]) → core::bool*
+    ;
+  operator <(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator >(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator <=(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator >=(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator -(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator +(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator /(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator ~/(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator *(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator %(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator |(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator ^(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator &(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator <<(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator >>(dynamic a, [dynamic b]) → dynamic
+    ;
+  operator []=(dynamic a, dynamic b, [dynamic c]) → void
+    ;
+  operator [](dynamic a, [dynamic b]) → dynamic
+    ;
+  operator ~(dynamic a, [dynamic b]) → dynamic
+    ;
+}
+class Operators6 extends core::Object {
+  synthetic constructor •() → self::Operators6*
+    ;
+  operator ==(dynamic a, {dynamic b}) → core::bool*
+    ;
+  operator <(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator >(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator <=(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator >=(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator -(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator +(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator /(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator ~/(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator *(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator %(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator |(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator ^(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator &(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator <<(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator >>(dynamic a, {dynamic b}) → dynamic
+    ;
+  operator []=(dynamic a, dynamic b, {dynamic c}) → void
+    ;
+  operator [](dynamic a, {dynamic b}) → dynamic
+    ;
+  operator ~(dynamic a, {dynamic b}) → dynamic
+    ;
+}
+class Operators7 extends core::Object {
+  synthetic constructor •() → self::Operators7*
+    ;
+  operator ==<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator ><T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator <=<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator >=<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator unary-<T extends core::Object* = dynamic>() → dynamic
+    ;
+  operator -<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator +<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator /<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator ~/<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator *<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator %<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator |<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator ^<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator &<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator <<<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator >><T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator []=<T extends core::Object* = dynamic>(dynamic a, dynamic b) → void
+    ;
+  operator []<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+  operator ~<T extends core::Object* = dynamic>() → dynamic
+    ;
+}
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/general/invalid_operator.dart.strong.expect b/pkg/front_end/testcases/general/invalid_operator.dart.strong.expect
new file mode 100644
index 0000000..e36b062
--- /dev/null
+++ b/pkg/front_end/testcases/general/invalid_operator.dart.strong.expect
@@ -0,0 +1,869 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:6:12: Error: Operator '==' should have exactly one parameter.
+//   operator ==() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:7:12: Error: Operator '<' should have exactly one parameter.
+//   operator <() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:8:12: Error: Operator '>' should have exactly one parameter.
+//   operator >() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:9:12: Error: Operator '<=' should have exactly one parameter.
+//   operator <=() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:10:12: Error: Operator '>=' should have exactly one parameter.
+//   operator >=() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:11:12: Error: Operator '+' should have exactly one parameter.
+//   operator +() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:12:12: Error: Operator '/' should have exactly one parameter.
+//   operator /() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:13:12: Error: Operator '~/' should have exactly one parameter.
+//   operator ~/() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:14:12: Error: Operator '*' should have exactly one parameter.
+//   operator *() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:15:12: Error: Operator '%' should have exactly one parameter.
+//   operator %() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:16:12: Error: Operator '|' should have exactly one parameter.
+//   operator |() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:17:12: Error: Operator '^' should have exactly one parameter.
+//   operator ^() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:18:12: Error: Operator '&' should have exactly one parameter.
+//   operator &() => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:19:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:20:12: Error: Operator '>>' should have exactly one parameter.
+//   operator >>() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:21:12: Error: Operator '[]=' should have exactly two parameters.
+//   operator []=(a, b, c) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:22:12: Error: Operator '[]' should have exactly one parameter.
+//   operator []() => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:23:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~(a) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:27:12: Error: Operator '==' should have exactly one parameter.
+//   operator ==(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:28:12: Error: Operator '<' should have exactly one parameter.
+//   operator <(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:29:12: Error: Operator '>' should have exactly one parameter.
+//   operator >(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:30:12: Error: Operator '<=' should have exactly one parameter.
+//   operator <=(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:31:12: Error: Operator '>=' should have exactly one parameter.
+//   operator >=(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:32:12: Error: Operator '-' should have zero or one parameter.
+// With zero parameters, it has the syntactic form '-a', formally known as 'unary-'. With one parameter, it has the syntactic form 'a - b', formally known as '-'.
+//   operator -(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:33:12: Error: Operator '+' should have exactly one parameter.
+//   operator +(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:34:12: Error: Operator '/' should have exactly one parameter.
+//   operator /(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:35:12: Error: Operator '~/' should have exactly one parameter.
+//   operator ~/(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:36:12: Error: Operator '*' should have exactly one parameter.
+//   operator *(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:37:12: Error: Operator '%' should have exactly one parameter.
+//   operator %(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:38:12: Error: Operator '|' should have exactly one parameter.
+//   operator |(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:39:12: Error: Operator '^' should have exactly one parameter.
+//   operator ^(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:40:12: Error: Operator '&' should have exactly one parameter.
+//   operator &(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:41:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:42:12: Error: Operator '>>' should have exactly one parameter.
+//   operator >>(a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:43:12: Error: Operator '[]=' should have exactly two parameters.
+//   operator []=(a, b, c) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:44:12: Error: Operator '[]' should have exactly one parameter.
+//   operator [](a, b) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:45:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~(a, b) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:49:16: Error: An operator can't have optional parameters.
+//   operator ==([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:50:15: Error: An operator can't have optional parameters.
+//   operator <([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:51:15: Error: An operator can't have optional parameters.
+//   operator >([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:52:16: Error: An operator can't have optional parameters.
+//   operator <=([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:53:16: Error: An operator can't have optional parameters.
+//   operator >=([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:54:15: Error: An operator can't have optional parameters.
+//   operator -([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:55:15: Error: An operator can't have optional parameters.
+//   operator +([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:56:15: Error: An operator can't have optional parameters.
+//   operator /([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:57:16: Error: An operator can't have optional parameters.
+//   operator ~/([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:58:15: Error: An operator can't have optional parameters.
+//   operator *([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:59:15: Error: An operator can't have optional parameters.
+//   operator %([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:60:15: Error: An operator can't have optional parameters.
+//   operator |([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:61:15: Error: An operator can't have optional parameters.
+//   operator ^([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:62:15: Error: An operator can't have optional parameters.
+//   operator &([a]) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:63:16: Error: An operator can't have optional parameters.
+//   operator <<([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:64:16: Error: An operator can't have optional parameters.
+//   operator >>([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:65:17: Error: An operator can't have optional parameters.
+//   operator []=([a, b]) => true;
+//                 ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:65:20: Error: An operator can't have optional parameters.
+//   operator []=([a, b]) => true;
+//                    ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:66:16: Error: An operator can't have optional parameters.
+//   operator []([a]) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:67:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~([a]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:71:16: Error: An operator can't have optional parameters.
+//   operator ==({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:72:15: Error: An operator can't have optional parameters.
+//   operator <({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:73:15: Error: An operator can't have optional parameters.
+//   operator >({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:74:16: Error: An operator can't have optional parameters.
+//   operator <=({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:75:16: Error: An operator can't have optional parameters.
+//   operator >=({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:76:15: Error: An operator can't have optional parameters.
+//   operator -({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:77:15: Error: An operator can't have optional parameters.
+//   operator +({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:78:15: Error: An operator can't have optional parameters.
+//   operator /({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:79:16: Error: An operator can't have optional parameters.
+//   operator ~/({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:80:15: Error: An operator can't have optional parameters.
+//   operator *({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:81:15: Error: An operator can't have optional parameters.
+//   operator %({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:82:15: Error: An operator can't have optional parameters.
+//   operator |({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:83:15: Error: An operator can't have optional parameters.
+//   operator ^({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:84:15: Error: An operator can't have optional parameters.
+//   operator &({a}) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:85:16: Error: An operator can't have optional parameters.
+//   operator <<({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:86:16: Error: An operator can't have optional parameters.
+//   operator >>({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:87:17: Error: An operator can't have optional parameters.
+//   operator []=({a, b}) => true;
+//                 ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:87:20: Error: An operator can't have optional parameters.
+//   operator []=({a, b}) => true;
+//                    ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:88:16: Error: An operator can't have optional parameters.
+//   operator []({a}) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:89:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~({a}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:93:12: Error: Operator '==' should have exactly one parameter.
+//   operator ==(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:94:12: Error: Operator '<' should have exactly one parameter.
+//   operator <(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:95:12: Error: Operator '>' should have exactly one parameter.
+//   operator >(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:96:12: Error: Operator '<=' should have exactly one parameter.
+//   operator <=(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:97:12: Error: Operator '>=' should have exactly one parameter.
+//   operator >=(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:98:12: Error: Operator '-' should have zero or one parameter.
+// With zero parameters, it has the syntactic form '-a', formally known as 'unary-'. With one parameter, it has the syntactic form 'a - b', formally known as '-'.
+//   operator -(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:99:12: Error: Operator '+' should have exactly one parameter.
+//   operator +(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:100:12: Error: Operator '/' should have exactly one parameter.
+//   operator /(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:101:12: Error: Operator '~/' should have exactly one parameter.
+//   operator ~/(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:102:12: Error: Operator '*' should have exactly one parameter.
+//   operator *(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:103:12: Error: Operator '%' should have exactly one parameter.
+//   operator %(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:104:12: Error: Operator '|' should have exactly one parameter.
+//   operator |(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:105:12: Error: Operator '^' should have exactly one parameter.
+//   operator ^(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:106:12: Error: Operator '&' should have exactly one parameter.
+//   operator &(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:107:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:108:12: Error: Operator '>>' should have exactly one parameter.
+//   operator >>(a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:109:12: Error: Operator '[]=' should have exactly two parameters.
+//   operator []=(a, b, [c]) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:110:12: Error: Operator '[]' should have exactly one parameter.
+//   operator [](a, [b]) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:111:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~(a, [b]) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:115:12: Error: Operator '==' should have exactly one parameter.
+//   operator ==(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:116:12: Error: Operator '<' should have exactly one parameter.
+//   operator <(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:117:12: Error: Operator '>' should have exactly one parameter.
+//   operator >(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:118:12: Error: Operator '<=' should have exactly one parameter.
+//   operator <=(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:119:12: Error: Operator '>=' should have exactly one parameter.
+//   operator >=(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:120:12: Error: Operator '-' should have zero or one parameter.
+// With zero parameters, it has the syntactic form '-a', formally known as 'unary-'. With one parameter, it has the syntactic form 'a - b', formally known as '-'.
+//   operator -(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:121:12: Error: Operator '+' should have exactly one parameter.
+//   operator +(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:122:12: Error: Operator '/' should have exactly one parameter.
+//   operator /(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:123:12: Error: Operator '~/' should have exactly one parameter.
+//   operator ~/(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:124:12: Error: Operator '*' should have exactly one parameter.
+//   operator *(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:125:12: Error: Operator '%' should have exactly one parameter.
+//   operator %(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:126:12: Error: Operator '|' should have exactly one parameter.
+//   operator |(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:127:12: Error: Operator '^' should have exactly one parameter.
+//   operator ^(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:128:12: Error: Operator '&' should have exactly one parameter.
+//   operator &(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:129:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:130:12: Error: Operator '>>' should have exactly one parameter.
+//   operator >>(a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:131:12: Error: Operator '[]=' should have exactly two parameters.
+//   operator []=(a, b, {c}) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:132:12: Error: Operator '[]' should have exactly one parameter.
+//   operator [](a, {b}) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:133:12: Error: Operator '~' shouldn't have any parameters.
+//   operator ~(a, {b}) => true;
+//            ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:137:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator ==<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:138:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator ><T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:139:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator <=<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:140:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator >=<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:141:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator -<T>() => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:142:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator -<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:143:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator +<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:144:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator /<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:145:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator ~/<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:146:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator *<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:147:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator %<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:148:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator |<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:149:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator ^<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:150:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator &<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:151:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator <<<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:152:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator >><T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:153:16: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator []=<T>(a, b) => true;
+//                ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:154:15: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator []<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator.dart:155:14: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator ~<T>() => true;
+//              ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Operators1 extends core::Object {
+  synthetic constructor •() → self::Operators1*
+    : super core::Object::•()
+    ;
+  operator ==() → dynamic
+    return true;
+  operator <() → dynamic
+    return true;
+  operator >() → dynamic
+    return true;
+  operator <=() → dynamic
+    return true;
+  operator >=() → dynamic
+    return true;
+  operator +() → dynamic
+    return true;
+  operator /() → dynamic
+    return true;
+  operator ~/() → dynamic
+    return true;
+  operator *() → dynamic
+    return true;
+  operator %() → dynamic
+    return true;
+  operator |() → dynamic
+    return true;
+  operator ^() → dynamic
+    return true;
+  operator &() → dynamic
+    return true;
+  operator <<() → dynamic
+    return true;
+  operator >>() → dynamic
+    return true;
+  operator []=(dynamic a, dynamic b, dynamic c) → void
+    return true;
+  operator []() → dynamic
+    return true;
+  operator ~(dynamic a) → dynamic
+    return true;
+}
+class Operators2 extends core::Object {
+  synthetic constructor •() → self::Operators2*
+    : super core::Object::•()
+    ;
+  operator ==(dynamic a, dynamic b) → dynamic
+    return true;
+  operator <(dynamic a, dynamic b) → dynamic
+    return true;
+  operator >(dynamic a, dynamic b) → dynamic
+    return true;
+  operator <=(dynamic a, dynamic b) → dynamic
+    return true;
+  operator >=(dynamic a, dynamic b) → dynamic
+    return true;
+  operator -(dynamic a, dynamic b) → dynamic
+    return true;
+  operator +(dynamic a, dynamic b) → dynamic
+    return true;
+  operator /(dynamic a, dynamic b) → dynamic
+    return true;
+  operator ~/(dynamic a, dynamic b) → dynamic
+    return true;
+  operator *(dynamic a, dynamic b) → dynamic
+    return true;
+  operator %(dynamic a, dynamic b) → dynamic
+    return true;
+  operator |(dynamic a, dynamic b) → dynamic
+    return true;
+  operator ^(dynamic a, dynamic b) → dynamic
+    return true;
+  operator &(dynamic a, dynamic b) → dynamic
+    return true;
+  operator <<(dynamic a, dynamic b) → dynamic
+    return true;
+  operator >>(dynamic a, dynamic b) → dynamic
+    return true;
+  operator []=(dynamic a, dynamic b, dynamic c) → void
+    return true;
+  operator [](dynamic a, dynamic b) → dynamic
+    return true;
+  operator ~(dynamic a, dynamic b) → dynamic
+    return true;
+}
+class Operators3 extends core::Object {
+  synthetic constructor •() → self::Operators3*
+    : super core::Object::•()
+    ;
+  operator ==([dynamic a = #C1]) → core::bool*
+    return true;
+  operator <([dynamic a = #C1]) → dynamic
+    return true;
+  operator >([dynamic a = #C1]) → dynamic
+    return true;
+  operator <=([dynamic a = #C1]) → dynamic
+    return true;
+  operator >=([dynamic a = #C1]) → dynamic
+    return true;
+  operator -([dynamic a = #C1]) → dynamic
+    return true;
+  operator +([dynamic a = #C1]) → dynamic
+    return true;
+  operator /([dynamic a = #C1]) → dynamic
+    return true;
+  operator ~/([dynamic a = #C1]) → dynamic
+    return true;
+  operator *([dynamic a = #C1]) → dynamic
+    return true;
+  operator %([dynamic a = #C1]) → dynamic
+    return true;
+  operator |([dynamic a = #C1]) → dynamic
+    return true;
+  operator ^([dynamic a = #C1]) → dynamic
+    return true;
+  operator &([dynamic a = #C1]) → dynamic
+    return true;
+  operator <<([dynamic a = #C1]) → dynamic
+    return true;
+  operator >>([dynamic a = #C1]) → dynamic
+    return true;
+  operator []=([dynamic a = #C1, dynamic b = #C1]) → void
+    return true;
+  operator []([dynamic a = #C1]) → dynamic
+    return true;
+  operator ~([dynamic a = #C1]) → dynamic
+    return true;
+}
+class Operators4 extends core::Object {
+  synthetic constructor •() → self::Operators4*
+    : super core::Object::•()
+    ;
+  operator ==({dynamic a = #C1}) → dynamic
+    return true;
+  operator <({dynamic a = #C1}) → dynamic
+    return true;
+  operator >({dynamic a = #C1}) → dynamic
+    return true;
+  operator <=({dynamic a = #C1}) → dynamic
+    return true;
+  operator >=({dynamic a = #C1}) → dynamic
+    return true;
+  operator -({dynamic a = #C1}) → dynamic
+    return true;
+  operator +({dynamic a = #C1}) → dynamic
+    return true;
+  operator /({dynamic a = #C1}) → dynamic
+    return true;
+  operator ~/({dynamic a = #C1}) → dynamic
+    return true;
+  operator *({dynamic a = #C1}) → dynamic
+    return true;
+  operator %({dynamic a = #C1}) → dynamic
+    return true;
+  operator |({dynamic a = #C1}) → dynamic
+    return true;
+  operator ^({dynamic a = #C1}) → dynamic
+    return true;
+  operator &({dynamic a = #C1}) → dynamic
+    return true;
+  operator <<({dynamic a = #C1}) → dynamic
+    return true;
+  operator >>({dynamic a = #C1}) → dynamic
+    return true;
+  operator []=({dynamic a = #C1, dynamic b = #C1}) → void
+    return true;
+  operator []({dynamic a = #C1}) → dynamic
+    return true;
+  operator ~({dynamic a = #C1}) → dynamic
+    return true;
+}
+class Operators5 extends core::Object {
+  synthetic constructor •() → self::Operators5*
+    : super core::Object::•()
+    ;
+  operator ==(dynamic a, [dynamic b = #C1]) → core::bool*
+    return true;
+  operator <(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator >(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator <=(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator >=(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator -(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator +(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator /(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator ~/(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator *(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator %(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator |(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator ^(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator &(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator <<(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator >>(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator []=(dynamic a, dynamic b, [dynamic c = #C1]) → void
+    return true;
+  operator [](dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+  operator ~(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+}
+class Operators6 extends core::Object {
+  synthetic constructor •() → self::Operators6*
+    : super core::Object::•()
+    ;
+  operator ==(dynamic a, {dynamic b = #C1}) → core::bool*
+    return true;
+  operator <(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator >(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator <=(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator >=(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator -(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator +(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator /(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator ~/(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator *(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator %(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator |(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator ^(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator &(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator <<(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator >>(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator []=(dynamic a, dynamic b, {dynamic c = #C1}) → void
+    return true;
+  operator [](dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+  operator ~(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+}
+class Operators7 extends core::Object {
+  synthetic constructor •() → self::Operators7*
+    : super core::Object::•()
+    ;
+  operator ==<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator ><T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator <=<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator >=<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator unary-<T extends core::Object* = dynamic>() → dynamic
+    return true;
+  operator -<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator +<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator /<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator ~/<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator *<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator %<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator |<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator ^<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator &<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator <<<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator >><T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator []=<T extends core::Object* = dynamic>(dynamic a, dynamic b) → void
+    return true;
+  operator []<T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+  operator ~<T extends core::Object* = dynamic>() → dynamic
+    return true;
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = null
+}
diff --git a/pkg/front_end/testcases/general/invalid_operator2.dart b/pkg/front_end/testcases/general/invalid_operator2.dart
new file mode 100644
index 0000000..8c6f693
--- /dev/null
+++ b/pkg/front_end/testcases/general/invalid_operator2.dart
@@ -0,0 +1,9 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class Operators7 {
+  operator <<T>(a) => true;
+}
+
+main() {}
diff --git a/pkg/front_end/testcases/general/invalid_operator2.dart.outline.expect b/pkg/front_end/testcases/general/invalid_operator2.dart.outline.expect
new file mode 100644
index 0000000..59cdc77
--- /dev/null
+++ b/pkg/front_end/testcases/general/invalid_operator2.dart.outline.expect
@@ -0,0 +1,39 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:12: Error: A method declaration needs an explicit list of parameters.
+// Try adding a parameter list to the method declaration.
+//   operator <<T>(a) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:14: Error: Expected '{' before this.
+//   operator <<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<T>(a) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:15: Error: Operator declarations must be preceded by the keyword 'operator'.
+// Try adding the keyword 'operator'.
+//   operator <<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:14: Error: Type 'T' not found.
+//   operator <<T>(a) => true;
+//              ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Operators7 extends core::Object {
+  synthetic constructor •() → self::Operators7*
+    ;
+  operator <<() → dynamic
+    ;
+  operator >(dynamic a) → invalid-type
+    ;
+}
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/general/invalid_operator2.dart.strong.expect b/pkg/front_end/testcases/general/invalid_operator2.dart.strong.expect
new file mode 100644
index 0000000..ada9780
--- /dev/null
+++ b/pkg/front_end/testcases/general/invalid_operator2.dart.strong.expect
@@ -0,0 +1,38 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:12: Error: A method declaration needs an explicit list of parameters.
+// Try adding a parameter list to the method declaration.
+//   operator <<T>(a) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:14: Error: Expected '{' before this.
+//   operator <<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<T>(a) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:15: Error: Operator declarations must be preceded by the keyword 'operator'.
+// Try adding the keyword 'operator'.
+//   operator <<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:14: Error: Type 'T' not found.
+//   operator <<T>(a) => true;
+//              ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Operators7 extends core::Object {
+  synthetic constructor •() → self::Operators7*
+    : super core::Object::•()
+    ;
+  operator <<() → dynamic {}
+  operator >(dynamic a) → invalid-type
+    return true as{TypeError} invalid-type;
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/general/invalid_operator2.dart.strong.transformed.expect b/pkg/front_end/testcases/general/invalid_operator2.dart.strong.transformed.expect
new file mode 100644
index 0000000..ada9780
--- /dev/null
+++ b/pkg/front_end/testcases/general/invalid_operator2.dart.strong.transformed.expect
@@ -0,0 +1,38 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:12: Error: A method declaration needs an explicit list of parameters.
+// Try adding a parameter list to the method declaration.
+//   operator <<T>(a) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:14: Error: Expected '{' before this.
+//   operator <<T>(a) => true;
+//              ^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:12: Error: Operator '<<' should have exactly one parameter.
+//   operator <<T>(a) => true;
+//            ^^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:15: Error: Operator declarations must be preceded by the keyword 'operator'.
+// Try adding the keyword 'operator'.
+//   operator <<T>(a) => true;
+//               ^
+//
+// pkg/front_end/testcases/general/invalid_operator2.dart:6:14: Error: Type 'T' not found.
+//   operator <<T>(a) => true;
+//              ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Operators7 extends core::Object {
+  synthetic constructor •() → self::Operators7*
+    : super core::Object::•()
+    ;
+  operator <<() → dynamic {}
+  operator >(dynamic a) → invalid-type
+    return true as{TypeError} invalid-type;
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/general/invocations.dart.strong.expect b/pkg/front_end/testcases/general/invocations.dart.strong.expect
index 390dc20..2e5cbcb 100644
--- a/pkg/front_end/testcases/general/invocations.dart.strong.expect
+++ b/pkg/front_end/testcases/general/invocations.dart.strong.expect
@@ -59,11 +59,11 @@
       print(\"Hello, World!\") +
       ^" in core::print("Hello, World!")).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:14:7: Error: Method not found: 'z'.
       z(\"Hello, World!\") +
-      ^" as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:15:7: Error: Getter not found: 'z'.
+      ^" as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:15:7: Error: Getter not found: 'z'.
       z.print(\"Hello, World!\") +
-      ^".print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:16:7: Error: Getter not found: 'y'.
+      ^".print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:16:7: Error: Getter not found: 'y'.
       y.z.print(\"Hello, World!\") +
-      ^".z.print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:17:7: Error: Getter not found: 'x'.
+      ^".z.print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:17:7: Error: Getter not found: 'x'.
       x.y.z.print(\"Hello, World!\");
-      ^".y.z.print("Hello, World!") as{TypeError} core::num*);
+      ^".y.z.print("Hello, World!") as{TypeError,ForDynamic} core::num*);
 }
diff --git a/pkg/front_end/testcases/general/invocations.dart.strong.transformed.expect b/pkg/front_end/testcases/general/invocations.dart.strong.transformed.expect
index 390dc20..2e5cbcb 100644
--- a/pkg/front_end/testcases/general/invocations.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/invocations.dart.strong.transformed.expect
@@ -59,11 +59,11 @@
       print(\"Hello, World!\") +
       ^" in core::print("Hello, World!")).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:14:7: Error: Method not found: 'z'.
       z(\"Hello, World!\") +
-      ^" as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:15:7: Error: Getter not found: 'z'.
+      ^" as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:15:7: Error: Getter not found: 'z'.
       z.print(\"Hello, World!\") +
-      ^".print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:16:7: Error: Getter not found: 'y'.
+      ^".print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:16:7: Error: Getter not found: 'y'.
       y.z.print(\"Hello, World!\") +
-      ^".z.print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:17:7: Error: Getter not found: 'x'.
+      ^".z.print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general/invocations.dart:17:7: Error: Getter not found: 'x'.
       x.y.z.print(\"Hello, World!\");
-      ^".y.z.print("Hello, World!") as{TypeError} core::num*);
+      ^".y.z.print("Hello, World!") as{TypeError,ForDynamic} core::num*);
 }
diff --git a/pkg/front_end/testcases/general/issue39344.dart.strong.expect b/pkg/front_end/testcases/general/issue39344.dart.strong.expect
index 8c367fc..bca8a50 100644
--- a/pkg/front_end/testcases/general/issue39344.dart.strong.expect
+++ b/pkg/front_end/testcases/general/issue39344.dart.strong.expect
@@ -56,7 +56,7 @@
     if(t is self::B*) {
       core::List<self::Class::T*>* ys = <self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}];
       alias = ys;
-      self::xs = alias as{TypeError} core::List<self::B*>*;
+      self::xs = alias as{TypeError,ForDynamic} core::List<self::B*>*;
     }
   }
   method method2b(generic-covariant-impl self::Class::T* t) → void {
@@ -64,7 +64,7 @@
     if(t is self::B*) {
       core::List<core::List<self::Class::T*>*>* yss = <core::List<self::Class::T*>*>[<self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}]];
       alias = yss;
-      self::xss = alias as{TypeError} core::List<core::List<self::B*>*>*;
+      self::xss = alias as{TypeError,ForDynamic} core::List<core::List<self::B*>*>*;
     }
   }
 }
diff --git a/pkg/front_end/testcases/general/issue39344.dart.strong.transformed.expect b/pkg/front_end/testcases/general/issue39344.dart.strong.transformed.expect
index 8c367fc..bca8a50 100644
--- a/pkg/front_end/testcases/general/issue39344.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/issue39344.dart.strong.transformed.expect
@@ -56,7 +56,7 @@
     if(t is self::B*) {
       core::List<self::Class::T*>* ys = <self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}];
       alias = ys;
-      self::xs = alias as{TypeError} core::List<self::B*>*;
+      self::xs = alias as{TypeError,ForDynamic} core::List<self::B*>*;
     }
   }
   method method2b(generic-covariant-impl self::Class::T* t) → void {
@@ -64,7 +64,7 @@
     if(t is self::B*) {
       core::List<core::List<self::Class::T*>*>* yss = <core::List<self::Class::T*>*>[<self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}]];
       alias = yss;
-      self::xss = alias as{TypeError} core::List<core::List<self::B*>*>*;
+      self::xss = alias as{TypeError,ForDynamic} core::List<core::List<self::B*>*>*;
     }
   }
 }
diff --git a/pkg/front_end/testcases/general/missing_toplevel.dart.strong.expect b/pkg/front_end/testcases/general/missing_toplevel.dart.strong.expect
index f1b93c3..51f556d 100644
--- a/pkg/front_end/testcases/general/missing_toplevel.dart.strong.expect
+++ b/pkg/front_end/testcases/general/missing_toplevel.dart.strong.expect
@@ -67,7 +67,7 @@
  - 'EmptyClass' is from 'pkg/front_end/testcases/general/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '+'.
 var missingBinary = classWithProperty.property += 2;
-                                               ^" as{TypeError} self::EmptyClass*;
+                                               ^" as{TypeError,ForDynamic} self::EmptyClass*;
 static field dynamic missingIndexGet = let final self::ClassWithIndexSet* #t2 = self::classWithIndexSet in let final core::int* #t3 = 0 in let final dynamic #t4 = invalid-expression "pkg/front_end/testcases/general/missing_toplevel.dart:28:40: Error: The method '[]' isn't defined for the class 'ClassWithIndexSet'.
  - 'ClassWithIndexSet' is from 'pkg/front_end/testcases/general/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '[]'.
diff --git a/pkg/front_end/testcases/general/missing_toplevel.dart.strong.transformed.expect b/pkg/front_end/testcases/general/missing_toplevel.dart.strong.transformed.expect
index f1b93c3..51f556d 100644
--- a/pkg/front_end/testcases/general/missing_toplevel.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/missing_toplevel.dart.strong.transformed.expect
@@ -67,7 +67,7 @@
  - 'EmptyClass' is from 'pkg/front_end/testcases/general/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '+'.
 var missingBinary = classWithProperty.property += 2;
-                                               ^" as{TypeError} self::EmptyClass*;
+                                               ^" as{TypeError,ForDynamic} self::EmptyClass*;
 static field dynamic missingIndexGet = let final self::ClassWithIndexSet* #t2 = self::classWithIndexSet in let final core::int* #t3 = 0 in let final dynamic #t4 = invalid-expression "pkg/front_end/testcases/general/missing_toplevel.dart:28:40: Error: The method '[]' isn't defined for the class 'ClassWithIndexSet'.
  - 'ClassWithIndexSet' is from 'pkg/front_end/testcases/general/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '[]'.
diff --git a/pkg/front_end/testcases/general/named_function_scope.dart.strong.expect b/pkg/front_end/testcases/general/named_function_scope.dart.strong.expect
index d20dd45..f5c5171 100644
--- a/pkg/front_end/testcases/general/named_function_scope.dart.strong.expect
+++ b/pkg/front_end/testcases/general/named_function_scope.dart.strong.expect
@@ -127,7 +127,7 @@
   {
     self::V* V = invalid-expression "pkg/front_end/testcases/general/named_function_scope.dart:47:7: Error: Can't declare 'V' because it was already used in this scope.
     V V;
-      ^" as{TypeError} self::V*;
+      ^" as{TypeError,ForDynamic} self::V*;
   }
   {
     <T extends core::Object* = dynamic>() →* core::Null? x = let final dynamic #t3 = invalid-expression "pkg/front_end/testcases/general/named_function_scope.dart:52:13: Error: 'T' is already declared in this scope.
diff --git a/pkg/front_end/testcases/general/named_function_scope.dart.strong.transformed.expect b/pkg/front_end/testcases/general/named_function_scope.dart.strong.transformed.expect
index d20dd45..f5c5171 100644
--- a/pkg/front_end/testcases/general/named_function_scope.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/named_function_scope.dart.strong.transformed.expect
@@ -127,7 +127,7 @@
   {
     self::V* V = invalid-expression "pkg/front_end/testcases/general/named_function_scope.dart:47:7: Error: Can't declare 'V' because it was already used in this scope.
     V V;
-      ^" as{TypeError} self::V*;
+      ^" as{TypeError,ForDynamic} self::V*;
   }
   {
     <T extends core::Object* = dynamic>() →* core::Null? x = let final dynamic #t3 = invalid-expression "pkg/front_end/testcases/general/named_function_scope.dart:52:13: Error: 'T' is already declared in this scope.
diff --git a/pkg/front_end/testcases/general/no_such_method_private_setter.dart.outline.expect b/pkg/front_end/testcases/general/no_such_method_private_setter.dart.outline.expect
index ea56f3e..fa9a400 100644
--- a/pkg/front_end/testcases/general/no_such_method_private_setter.dart.outline.expect
+++ b/pkg/front_end/testcases/general/no_such_method_private_setter.dart.outline.expect
@@ -9,7 +9,7 @@
   synthetic constructor •() → self::Foo*
     ;
   no-such-method-forwarder get /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x() → core::int*
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#_x, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} core::int*;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#_x, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x(core::int* value) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#_x=, 2, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
 }
diff --git a/pkg/front_end/testcases/general/no_such_method_private_setter.dart.strong.expect b/pkg/front_end/testcases/general/no_such_method_private_setter.dart.strong.expect
index 3fa5d56..b80b9e5 100644
--- a/pkg/front_end/testcases/general/no_such_method_private_setter.dart.strong.expect
+++ b/pkg/front_end/testcases/general/no_such_method_private_setter.dart.strong.expect
@@ -10,7 +10,7 @@
     : super core::Object::•()
     ;
   no-such-method-forwarder get /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x() → core::int*
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x(core::int* value) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/general/no_such_method_private_setter.dart.strong.transformed.expect b/pkg/front_end/testcases/general/no_such_method_private_setter.dart.strong.transformed.expect
index 3fa5d56..b80b9e5 100644
--- a/pkg/front_end/testcases/general/no_such_method_private_setter.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/no_such_method_private_setter.dart.strong.transformed.expect
@@ -10,7 +10,7 @@
     : super core::Object::•()
     ;
   no-such-method-forwarder get /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x() → core::int*
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x(core::int* value) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/general/non_covariant_checks.dart.strong.expect b/pkg/front_end/testcases/general/non_covariant_checks.dart.strong.expect
index 17ac3e7..6116ad1 100644
--- a/pkg/front_end/testcases/general/non_covariant_checks.dart.strong.expect
+++ b/pkg/front_end/testcases/general/non_covariant_checks.dart.strong.expect
@@ -147,14 +147,14 @@
   c.{self::C::field1};
   c.{self::C::field2};
   try {
-    c.{self::C::field3} as{TypeError} (core::num*) →* void;
+    c.{self::C::field3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::field4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -162,14 +162,14 @@
   }
   c.{self::C::field5};
   try {
-    c.{self::C::field6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::field6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::field7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -178,42 +178,42 @@
   c.{self::C::field8};
   c.{self::C::field9};
   try {
-    c.{self::C::field10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::field10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::field11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::field12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::field13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::field14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::field15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -222,14 +222,14 @@
   c.{self::C::getter1};
   c.{self::C::getter2};
   try {
-    c.{self::C::getter3} as{TypeError} (core::num*) →* void;
+    c.{self::C::getter3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::getter4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -237,14 +237,14 @@
   }
   c.{self::C::getter5};
   try {
-    c.{self::C::getter6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::getter6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::getter7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -253,42 +253,42 @@
   c.{self::C::getter8};
   c.{self::C::getter9};
   try {
-    c.{self::C::getter10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::getter10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::getter11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::getter12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::getter13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::getter14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::getter15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general/non_covariant_checks.dart.strong.transformed.expect b/pkg/front_end/testcases/general/non_covariant_checks.dart.strong.transformed.expect
index 17ac3e7..6116ad1 100644
--- a/pkg/front_end/testcases/general/non_covariant_checks.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/non_covariant_checks.dart.strong.transformed.expect
@@ -147,14 +147,14 @@
   c.{self::C::field1};
   c.{self::C::field2};
   try {
-    c.{self::C::field3} as{TypeError} (core::num*) →* void;
+    c.{self::C::field3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::field4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -162,14 +162,14 @@
   }
   c.{self::C::field5};
   try {
-    c.{self::C::field6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::field6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::field7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -178,42 +178,42 @@
   c.{self::C::field8};
   c.{self::C::field9};
   try {
-    c.{self::C::field10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::field10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::field11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::field12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::field13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::field14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::field15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -222,14 +222,14 @@
   c.{self::C::getter1};
   c.{self::C::getter2};
   try {
-    c.{self::C::getter3} as{TypeError} (core::num*) →* void;
+    c.{self::C::getter3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::getter4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -237,14 +237,14 @@
   }
   c.{self::C::getter5};
   try {
-    c.{self::C::getter6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::getter6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::getter7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -253,42 +253,42 @@
   c.{self::C::getter8};
   c.{self::C::getter9};
   try {
-    c.{self::C::getter10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::getter10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::getter11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::getter12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::getter13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::getter14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::getter15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general/null_aware_for_in.dart.strong.expect b/pkg/front_end/testcases/general/null_aware_for_in.dart.strong.expect
index 18203ab..5d3f769 100644
--- a/pkg/front_end/testcases/general/null_aware_for_in.dart.strong.expect
+++ b/pkg/front_end/testcases/general/null_aware_for_in.dart.strong.expect
@@ -10,8 +10,8 @@
 static method main() → dynamic {
   dynamic o;
   if(false) {
-    for (final dynamic #t1 in (let final dynamic #t2 = o in #t2.{core::Object::==}(null) ?{dynamic} null : #t2.iterable) as{TypeError} core::Iterable<dynamic>*) {
-      self::Class* c = #t1 as{TypeError} self::Class*;
+    for (final dynamic #t1 in (let final dynamic #t2 = o in #t2.{core::Object::==}(null) ?{dynamic} null : #t2.iterable) as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
+      self::Class* c = #t1 as{TypeError,ForDynamic} self::Class*;
     }
   }
 }
diff --git a/pkg/front_end/testcases/general/null_aware_for_in.dart.strong.transformed.expect b/pkg/front_end/testcases/general/null_aware_for_in.dart.strong.transformed.expect
index f6157cd..eb4e616 100644
--- a/pkg/front_end/testcases/general/null_aware_for_in.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/null_aware_for_in.dart.strong.transformed.expect
@@ -12,11 +12,11 @@
   dynamic o;
   if(false) {
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((let final dynamic #t1 = o in #t1.{core::Object::==}(null) ?{dynamic} null : #t1.iterable) as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((let final dynamic #t1 = o in #t1.{core::Object::==}(null) ?{dynamic} null : #t1.iterable) as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t2 = :sync-for-iterator.{core::Iterator::current};
         {
-          self::Class* c = #t2 as{TypeError} self::Class*;
+          self::Class* c = #t2 as{TypeError,ForDynamic} self::Class*;
         }
       }
     }
diff --git a/pkg/front_end/testcases/general/platform_invalid_uris/libraries.json b/pkg/front_end/testcases/general/platform_invalid_uris/libraries.json
new file mode 100644
index 0000000..154c73c
--- /dev/null
+++ b/pkg/front_end/testcases/general/platform_invalid_uris/libraries.json
@@ -0,0 +1,12 @@
+{
+  "none": {
+    "libraries": {
+      "test": {
+        "patches": [
+          "patch_lib.dart"
+        ],
+        "uri": "origin_lib.dart"
+      }
+    }
+  }
+}
diff --git a/pkg/front_end/testcases/general/platform_invalid_uris/main.dart b/pkg/front_end/testcases/general/platform_invalid_uris/main.dart
new file mode 100644
index 0000000..6e0cb95
--- /dev/null
+++ b/pkg/front_end/testcases/general/platform_invalid_uris/main.dart
@@ -0,0 +1,9 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:test';
+
+main() {
+  new Class();
+}
diff --git a/pkg/front_end/testcases/general/platform_invalid_uris/main.dart.outline.expect b/pkg/front_end/testcases/general/platform_invalid_uris/main.dart.outline.expect
new file mode 100644
index 0000000..5212d00
--- /dev/null
+++ b/pkg/front_end/testcases/general/platform_invalid_uris/main.dart.outline.expect
@@ -0,0 +1,62 @@
+library;
+import self as self;
+
+import "dart:test";
+
+static method main() → dynamic
+  ;
+
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/patch_lib.dart:8:9: Error: Couldn't parse URI ':c':
+//   Invalid empty scheme.
+// import ':c';
+//         ^
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/patch_lib.dart:9:9: Error: Couldn't parse URI ':d':
+//   Invalid empty scheme.
+// export ':d';
+//         ^
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/origin_lib.dart:5:9: Error: Couldn't parse URI ':a':
+//   Invalid empty scheme.
+// import ':a';
+//         ^
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/origin_lib.dart:6:9: Error: Couldn't parse URI ':b':
+//   Invalid empty scheme.
+// export ':b';
+//         ^
+//
+import self as self2;
+import "dart:_internal" as _in;
+import "dart:core" as core;
+
+import "dart:_internal";
+import "org-dartlang-malformed-uri:?%3Ac";
+export "org-dartlang-malformed-uri:?%3Ad";
+import "org-dartlang-malformed-uri:?%3Aa";
+export "org-dartlang-malformed-uri:?%3Ab";
+
+@_in::patch
+class Class extends core::Object {
+  synthetic constructor •() → self2::Class*
+    ;
+}
+
+library;
+import self as self3;
+
+
+library;
+import self as self4;
+
+
+library;
+import self as self5;
+
+
+library;
+import self as self6;
diff --git a/pkg/front_end/testcases/general/platform_invalid_uris/main.dart.strong.expect b/pkg/front_end/testcases/general/platform_invalid_uris/main.dart.strong.expect
new file mode 100644
index 0000000..3bb4f07
--- /dev/null
+++ b/pkg/front_end/testcases/general/platform_invalid_uris/main.dart.strong.expect
@@ -0,0 +1,70 @@
+library;
+import self as self;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  new test::Class::•();
+}
+
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/patch_lib.dart:8:9: Error: Couldn't parse URI ':c':
+//   Invalid empty scheme.
+// import ':c';
+//         ^
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/patch_lib.dart:9:9: Error: Couldn't parse URI ':d':
+//   Invalid empty scheme.
+// export ':d';
+//         ^
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/origin_lib.dart:5:9: Error: Couldn't parse URI ':a':
+//   Invalid empty scheme.
+// import ':a';
+//         ^
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/origin_lib.dart:6:9: Error: Couldn't parse URI ':b':
+//   Invalid empty scheme.
+// export ':b';
+//         ^
+//
+import self as test;
+import "dart:_internal" as _in;
+import "dart:core" as core;
+
+import "dart:_internal";
+import "org-dartlang-malformed-uri:?%3Ac";
+export "org-dartlang-malformed-uri:?%3Ad";
+import "org-dartlang-malformed-uri:?%3Aa";
+export "org-dartlang-malformed-uri:?%3Ab";
+
+@#C1
+class Class extends core::Object {
+  synthetic constructor •() → test::Class*
+    : super core::Object::•()
+    ;
+}
+
+library;
+import self as self2;
+
+
+library;
+import self as self3;
+
+
+library;
+import self as self4;
+
+
+library;
+import self as self5;
+
+
+constants  {
+  #C1 = _in::_Patch {}
+}
diff --git a/pkg/front_end/testcases/general/platform_invalid_uris/main.dart.strong.transformed.expect b/pkg/front_end/testcases/general/platform_invalid_uris/main.dart.strong.transformed.expect
new file mode 100644
index 0000000..3bb4f07
--- /dev/null
+++ b/pkg/front_end/testcases/general/platform_invalid_uris/main.dart.strong.transformed.expect
@@ -0,0 +1,70 @@
+library;
+import self as self;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  new test::Class::•();
+}
+
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/patch_lib.dart:8:9: Error: Couldn't parse URI ':c':
+//   Invalid empty scheme.
+// import ':c';
+//         ^
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/patch_lib.dart:9:9: Error: Couldn't parse URI ':d':
+//   Invalid empty scheme.
+// export ':d';
+//         ^
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/origin_lib.dart:5:9: Error: Couldn't parse URI ':a':
+//   Invalid empty scheme.
+// import ':a';
+//         ^
+//
+// pkg/front_end/testcases/general/platform_invalid_uris/origin_lib.dart:6:9: Error: Couldn't parse URI ':b':
+//   Invalid empty scheme.
+// export ':b';
+//         ^
+//
+import self as test;
+import "dart:_internal" as _in;
+import "dart:core" as core;
+
+import "dart:_internal";
+import "org-dartlang-malformed-uri:?%3Ac";
+export "org-dartlang-malformed-uri:?%3Ad";
+import "org-dartlang-malformed-uri:?%3Aa";
+export "org-dartlang-malformed-uri:?%3Ab";
+
+@#C1
+class Class extends core::Object {
+  synthetic constructor •() → test::Class*
+    : super core::Object::•()
+    ;
+}
+
+library;
+import self as self2;
+
+
+library;
+import self as self3;
+
+
+library;
+import self as self4;
+
+
+library;
+import self as self5;
+
+
+constants  {
+  #C1 = _in::_Patch {}
+}
diff --git a/pkg/front_end/testcases/general/platform_invalid_uris/origin_lib.dart b/pkg/front_end/testcases/general/platform_invalid_uris/origin_lib.dart
new file mode 100644
index 0000000..5db6a48
--- /dev/null
+++ b/pkg/front_end/testcases/general/platform_invalid_uris/origin_lib.dart
@@ -0,0 +1,8 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import ':a';
+export ':b';
+
+class Class {}
diff --git a/pkg/front_end/testcases/general/platform_invalid_uris/patch_lib.dart b/pkg/front_end/testcases/general/platform_invalid_uris/patch_lib.dart
new file mode 100644
index 0000000..b898ab1
--- /dev/null
+++ b/pkg/front_end/testcases/general/platform_invalid_uris/patch_lib.dart
@@ -0,0 +1,12 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// ignore: import_internal_library
+import 'dart:_internal';
+
+import ':c';
+export ':d';
+
+@patch
+class Class {}
diff --git a/pkg/front_end/testcases/general/return_with_unknown_type_in_context.dart.strong.expect b/pkg/front_end/testcases/general/return_with_unknown_type_in_context.dart.strong.expect
index 18814f3..4bfac34 100644
--- a/pkg/front_end/testcases/general/return_with_unknown_type_in_context.dart.strong.expect
+++ b/pkg/front_end/testcases/general/return_with_unknown_type_in_context.dart.strong.expect
@@ -4,7 +4,7 @@
 
 static method f(core::List<dynamic>* x) → core::bool* {
   return x.{core::Iterable::expand}<dynamic>((dynamic y) → core::Iterable<dynamic>* {
-    return y.split(",") as{TypeError} core::Iterable<dynamic>*;
+    return y.split(",") as{TypeError,ForDynamic} core::Iterable<dynamic>*;
   }).{core::Iterable::any}((dynamic y) → core::bool* => y.{core::Object::==}("z"));
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/general/return_with_unknown_type_in_context.dart.strong.transformed.expect b/pkg/front_end/testcases/general/return_with_unknown_type_in_context.dart.strong.transformed.expect
index 18814f3..4bfac34 100644
--- a/pkg/front_end/testcases/general/return_with_unknown_type_in_context.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/return_with_unknown_type_in_context.dart.strong.transformed.expect
@@ -4,7 +4,7 @@
 
 static method f(core::List<dynamic>* x) → core::bool* {
   return x.{core::Iterable::expand}<dynamic>((dynamic y) → core::Iterable<dynamic>* {
-    return y.split(",") as{TypeError} core::Iterable<dynamic>*;
+    return y.split(",") as{TypeError,ForDynamic} core::Iterable<dynamic>*;
   }).{core::Iterable::any}((dynamic y) → core::bool* => y.{core::Object::==}("z"));
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.expect b/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.expect
index 2a7da3d..48f5952 100644
--- a/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.expect
+++ b/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.expect
@@ -160,18 +160,18 @@
   } =>#t18;
   core::List<dynamic>* lhs21 = block {
     final core::List<dynamic>* #t20 = <dynamic>[];
-    for (final dynamic #t21 in (spread as dynamic) as{TypeError} core::Iterable<dynamic>*)
+    for (final dynamic #t21 in (spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*)
       #t20.{core::List::add}(#t21);
   } =>#t20;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t22 = col::LinkedHashSet::•<dynamic>();
-    for (final dynamic #t23 in (spread as dynamic) as{TypeError} core::Iterable<dynamic>*)
+    for (final dynamic #t23 in (spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*)
       #t22.{core::Set::add}(#t23);
     #t22.{core::Set::add}(42);
   } =>#t22;
   core::Map<dynamic, dynamic>* map21 = block {
     final core::Map<dynamic, dynamic>* #t24 = <dynamic, dynamic>{};
-    for (final core::MapEntry<dynamic, dynamic>* #t25 in ((mapSpread as dynamic) as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries})
+    for (final core::MapEntry<dynamic, dynamic>* #t25 in ((mapSpread as dynamic) as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries})
       #t24.{core::Map::[]=}(#t25.{core::MapEntry::key}, #t25.{core::MapEntry::value});
     #t24.{core::Map::[]=}("baz", 42);
   } =>#t24;
@@ -377,14 +377,14 @@
   } =>#t91;
   core::List<core::int*>* list110 = block {
     final core::List<core::int*>* #t95 = <core::int*>[];
-    for (final dynamic #t96 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    for (final dynamic #t96 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
       final core::int* #t97 = #t96 as{TypeError} core::int*;
       #t95.{core::List::add}(#t97);
     }
   } =>#t95;
   core::Map<core::num*, core::int*>* map110 = block {
     final core::Map<core::num*, core::int*>* #t98 = <core::num*, core::int*>{};
-    for (final core::MapEntry<dynamic, dynamic>* #t99 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
+    for (final core::MapEntry<dynamic, dynamic>* #t99 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
       final core::num* #t100 = #t99.{core::MapEntry::key} as{TypeError} core::num*;
       final core::int* #t101 = #t99.{core::MapEntry::value} as{TypeError} core::int*;
       #t98.{core::Map::[]=}(#t100, #t101);
diff --git a/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.transformed.expect b/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.transformed.expect
index aac1419..22a6806 100644
--- a/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/spread_collection_inference.dart.strong.transformed.expect
@@ -208,7 +208,7 @@
   core::List<dynamic>* lhs21 = block {
     final core::List<dynamic>* #t20 = <dynamic>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t21 = :sync-for-iterator.{core::Iterator::current};
         #t20.{core::List::add}(#t21);
@@ -218,7 +218,7 @@
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t22 = col::LinkedHashSet::•<dynamic>();
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t23 = :sync-for-iterator.{core::Iterator::current};
         #t22.{core::Set::add}(#t23);
@@ -229,7 +229,7 @@
   core::Map<dynamic, dynamic>* map21 = block {
     final core::Map<dynamic, dynamic>* #t24 = <dynamic, dynamic>{};
     {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>(((mapSpread as dynamic) as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>(((mapSpread as dynamic) as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t25 = :sync-for-iterator.{core::Iterator::current};
         #t24.{core::Map::[]=}(#t25.{core::MapEntry::key}, #t25.{core::MapEntry::value});
@@ -554,7 +554,7 @@
   core::List<core::int*>* list110 = block {
     final core::List<core::int*>* #t95 = <core::int*>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t96 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -567,7 +567,7 @@
   core::Map<core::num*, core::int*>* map110 = block {
     final core::Map<core::num*, core::int*>* #t98 = <core::num*, core::int*>{};
     {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t99 = :sync-for-iterator.{core::Iterator::current};
         {
diff --git a/pkg/front_end/testcases/general/super_call.dart.strong.expect b/pkg/front_end/testcases/general/super_call.dart.strong.expect
index a56e117..7ef570e 100644
--- a/pkg/front_end/testcases/general/super_call.dart.strong.expect
+++ b/pkg/front_end/testcases/general/super_call.dart.strong.expect
@@ -27,7 +27,7 @@
     return invalid-expression "pkg/front_end/testcases/general/super_call.dart:14:12: Error: Can't use 'super' as an expression.
 To delegate a constructor to a super constructor, put the super call as an initializer.
     return super(5);
-           ^" as{TypeError} core::int*;
+           ^" as{TypeError,ForDynamic} core::int*;
   }
 }
 static method main() → dynamic {
diff --git a/pkg/front_end/testcases/general/super_call.dart.strong.transformed.expect b/pkg/front_end/testcases/general/super_call.dart.strong.transformed.expect
index a56e117..7ef570e 100644
--- a/pkg/front_end/testcases/general/super_call.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/super_call.dart.strong.transformed.expect
@@ -27,7 +27,7 @@
     return invalid-expression "pkg/front_end/testcases/general/super_call.dart:14:12: Error: Can't use 'super' as an expression.
 To delegate a constructor to a super constructor, put the super call as an initializer.
     return super(5);
-           ^" as{TypeError} core::int*;
+           ^" as{TypeError,ForDynamic} core::int*;
   }
 }
 static method main() → dynamic {
diff --git a/pkg/front_end/testcases/general/super_nsm.dart.outline.expect b/pkg/front_end/testcases/general/super_nsm.dart.outline.expect
index 2da773b..4f2eabf 100644
--- a/pkg/front_end/testcases/general/super_nsm.dart.outline.expect
+++ b/pkg/front_end/testcases/general/super_nsm.dart.outline.expect
@@ -13,7 +13,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     ;
   no-such-method-forwarder method interfaceMethod() → dynamic
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} dynamic;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} dynamic;
 }
 class D extends self::C {
   synthetic constructor •() → self::D*
diff --git a/pkg/front_end/testcases/general/super_nsm.dart.strong.expect b/pkg/front_end/testcases/general/super_nsm.dart.strong.expect
index 69a6257..f804c1f 100644
--- a/pkg/front_end/testcases/general/super_nsm.dart.strong.expect
+++ b/pkg/front_end/testcases/general/super_nsm.dart.strong.expect
@@ -15,7 +15,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     return "C";
   no-such-method-forwarder method interfaceMethod() → dynamic
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
 }
 class D extends self::C {
   synthetic constructor •() → self::D*
diff --git a/pkg/front_end/testcases/general/super_nsm.dart.strong.transformed.expect b/pkg/front_end/testcases/general/super_nsm.dart.strong.transformed.expect
index 69a6257..f804c1f 100644
--- a/pkg/front_end/testcases/general/super_nsm.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/super_nsm.dart.strong.transformed.expect
@@ -15,7 +15,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     return "C";
   no-such-method-forwarder method interfaceMethod() → dynamic
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
 }
 class D extends self::C {
   synthetic constructor •() → self::D*
diff --git a/pkg/front_end/testcases/general/type_variable_bound_access.dart.strong.expect b/pkg/front_end/testcases/general/type_variable_bound_access.dart.strong.expect
index 79514a6..09551dc 100644
--- a/pkg/front_end/testcases/general/type_variable_bound_access.dart.strong.expect
+++ b/pkg/front_end/testcases/general/type_variable_bound_access.dart.strong.expect
@@ -31,7 +31,7 @@
     return this.{self::NumClass::field1}.{core::num::+}(invalid-expression "pkg/front_end/testcases/general/type_variable_bound_access.dart:22:36: Error: The getter 'length' isn't defined for the class 'num'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'length'.
   num method2() => field1 + field2.length;
-                                   ^^^^^^" as{TypeError} core::num*);
+                                   ^^^^^^" as{TypeError,ForDynamic} core::num*);
 }
 static method main() → dynamic {
   new self::DynamicClass::•<core::num*, core::int*>(0.5, 2).{self::DynamicClass::method}();
diff --git a/pkg/front_end/testcases/general/void_methods.dart.strong.expect b/pkg/front_end/testcases/general/void_methods.dart.strong.expect
index 3bde972..c503392 100644
--- a/pkg/front_end/testcases/general/void_methods.dart.strong.expect
+++ b/pkg/front_end/testcases/general/void_methods.dart.strong.expect
@@ -10,7 +10,7 @@
   set first(dynamic x) → void
     return let final core::List<dynamic>* #t1 = this.{self::Foo::list} in let final core::int* #t2 = 0 in let final dynamic #t3 = x in let final void #t4 = #t1.{core::List::[]=}(#t2, #t3) in #t3;
   operator []=(dynamic x, dynamic y) → void
-    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final dynamic #t6 = x as{TypeError} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
+    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final dynamic #t6 = x as{TypeError,ForDynamic} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
   method clear() → void
     return this.{self::Foo::list}.{core::List::clear}();
 }
diff --git a/pkg/front_end/testcases/general/void_methods.dart.strong.transformed.expect b/pkg/front_end/testcases/general/void_methods.dart.strong.transformed.expect
index 9f36d60..739251d 100644
--- a/pkg/front_end/testcases/general/void_methods.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/void_methods.dart.strong.transformed.expect
@@ -10,7 +10,7 @@
   set first(dynamic x) → void
     return let final core::List<dynamic>* #t1 = this.{self::Foo::list} in let final core::int* #t2 = 0 in let final dynamic #t3 = x in let final void #t4 = #t1.{core::List::[]=}(#t2, #t3) in #t3;
   operator []=(dynamic x, dynamic y) → void
-    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final core::int* #t6 = x as{TypeError} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
+    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final core::int* #t6 = x as{TypeError,ForDynamic} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
   method clear() → void
     return this.{self::Foo::list}.{core::List::clear}();
 }
diff --git a/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill.dart b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill.dart
new file mode 100644
index 0000000..f678004
--- /dev/null
+++ b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill.dart
@@ -0,0 +1,9 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'extension_from_dill_lib.dart';
+
+main() {
+  "".foo();
+}
diff --git a/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart
new file mode 100644
index 0000000..8d058b3
--- /dev/null
+++ b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart
@@ -0,0 +1,5 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+export 'extension_from_dill_lib2.dart';
diff --git a/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart.outline.expect b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart.outline.expect
new file mode 100644
index 0000000..f307bb3
--- /dev/null
+++ b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart.outline.expect
@@ -0,0 +1,28 @@
+library;
+import self as self;
+
+import "org-dartlang-testcase:///extension_from_dill_lib.dart";
+
+static method main() → dynamic
+  ;
+
+library;
+import self as self2;
+import "extension_from_dill_lib2.dart" as ext;
+additionalExports = (ext::Extension)
+
+export "org-dartlang-testcase:///extension_from_dill_lib2.dart";
+
+
+library;
+import self as ext;
+import "dart:core" as core;
+
+extension Extension on core::String* {
+  method foo = ext::Extension|foo;
+  tearoff foo = ext::Extension|get#foo;
+}
+static method Extension|foo(final core::String* #this) → dynamic
+  ;
+static method Extension|get#foo(final core::String* #this) → () →* dynamic
+  return () → dynamic => ext::Extension|foo(#this);
diff --git a/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart.strong.expect b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart.strong.expect
new file mode 100644
index 0000000..01e6ac2
--- /dev/null
+++ b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart.strong.expect
@@ -0,0 +1,30 @@
+library;
+import self as self;
+import "extension_from_dill_lib2.dart" as ext;
+
+import "org-dartlang-testcase:///extension_from_dill_lib.dart";
+
+static method main() → dynamic {
+  ext::Extension|foo("");
+}
+
+library;
+import self as self2;
+import "extension_from_dill_lib2.dart" as ext;
+additionalExports = (ext::Extension)
+
+export "org-dartlang-testcase:///extension_from_dill_lib2.dart";
+
+
+library;
+import self as ext;
+import "dart:core" as core;
+
+extension Extension on core::String* {
+  method foo = ext::Extension|foo;
+  tearoff foo = ext::Extension|get#foo;
+}
+static method Extension|foo(final core::String* #this) → dynamic
+  return 42;
+static method Extension|get#foo(final core::String* #this) → () →* dynamic
+  return () → dynamic => ext::Extension|foo(#this);
diff --git a/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart.strong.transformed.expect b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart.strong.transformed.expect
new file mode 100644
index 0000000..01e6ac2
--- /dev/null
+++ b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib.dart.strong.transformed.expect
@@ -0,0 +1,30 @@
+library;
+import self as self;
+import "extension_from_dill_lib2.dart" as ext;
+
+import "org-dartlang-testcase:///extension_from_dill_lib.dart";
+
+static method main() → dynamic {
+  ext::Extension|foo("");
+}
+
+library;
+import self as self2;
+import "extension_from_dill_lib2.dart" as ext;
+additionalExports = (ext::Extension)
+
+export "org-dartlang-testcase:///extension_from_dill_lib2.dart";
+
+
+library;
+import self as ext;
+import "dart:core" as core;
+
+extension Extension on core::String* {
+  method foo = ext::Extension|foo;
+  tearoff foo = ext::Extension|get#foo;
+}
+static method Extension|foo(final core::String* #this) → dynamic
+  return 42;
+static method Extension|get#foo(final core::String* #this) → () →* dynamic
+  return () → dynamic => ext::Extension|foo(#this);
diff --git a/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib2.dart b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib2.dart
new file mode 100644
index 0000000..baf81eb
--- /dev/null
+++ b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/extension_from_dill_lib2.dart
@@ -0,0 +1,7 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+extension Extension on String {
+  foo() => 42;
+}
diff --git a/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/link.options b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/link.options
new file mode 100644
index 0000000..51b39bc
--- /dev/null
+++ b/pkg/front_end/testcases/general/with_dependencies/extension_from_dill/link.options
@@ -0,0 +1,2 @@
+extension_from_dill_lib.dart
+extension_from_dill_lib2.dart
\ No newline at end of file
diff --git a/pkg/front_end/testcases/general/with_dependencies/variance_from_dill/variance_from_dill_lib.dart.outline.expect b/pkg/front_end/testcases/general/with_dependencies/variance_from_dill/variance_from_dill_lib.dart.outline.expect
new file mode 100644
index 0000000..ffc3306
--- /dev/null
+++ b/pkg/front_end/testcases/general/with_dependencies/variance_from_dill/variance_from_dill_lib.dart.outline.expect
@@ -0,0 +1,15 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///variance_from_dill_lib.dart";
+
+typedef G<unrelated T extends core::Object* = dynamic> = (() →* dynamic) →* dynamic;
+static method main() → dynamic
+  ;
+
+library;
+import self as self2;
+import "dart:core" as core;
+
+typedef F<unrelated T extends core::Object* = dynamic> = () →* dynamic;
diff --git a/pkg/front_end/testcases/general/with_dependencies/variance_from_dill/variance_from_dill_lib.dart.strong.expect b/pkg/front_end/testcases/general/with_dependencies/variance_from_dill/variance_from_dill_lib.dart.strong.expect
new file mode 100644
index 0000000..663835f
--- /dev/null
+++ b/pkg/front_end/testcases/general/with_dependencies/variance_from_dill/variance_from_dill_lib.dart.strong.expect
@@ -0,0 +1,16 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///variance_from_dill_lib.dart";
+
+typedef G<unrelated T extends core::Object* = dynamic> = (() →* dynamic) →* dynamic;
+static method main() → dynamic {
+  core::print((() →* dynamic) →* dynamic);
+}
+
+library;
+import self as self2;
+import "dart:core" as core;
+
+typedef F<unrelated T extends core::Object* = dynamic> = () →* dynamic;
diff --git a/pkg/front_end/testcases/general/with_dependencies/variance_from_dill/variance_from_dill_lib.dart.strong.transformed.expect b/pkg/front_end/testcases/general/with_dependencies/variance_from_dill/variance_from_dill_lib.dart.strong.transformed.expect
new file mode 100644
index 0000000..663835f
--- /dev/null
+++ b/pkg/front_end/testcases/general/with_dependencies/variance_from_dill/variance_from_dill_lib.dart.strong.transformed.expect
@@ -0,0 +1,16 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///variance_from_dill_lib.dart";
+
+typedef G<unrelated T extends core::Object* = dynamic> = (() →* dynamic) →* dynamic;
+static method main() → dynamic {
+  core::print((() →* dynamic) →* dynamic);
+}
+
+library;
+import self as self2;
+import "dart:core" as core;
+
+typedef F<unrelated T extends core::Object* = dynamic> = () →* dynamic;
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.strong.expect
index 4a77a26..2a91755 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.strong.expect
@@ -52,22 +52,22 @@
     self::planner.{self::Planner::incrementalAdd}(this);
   }
   method satisfy(dynamic mark) → self::Constraint* {
-    this.{self::Constraint::chooseMethod}(mark as{TypeError} core::int*);
+    this.{self::Constraint::chooseMethod}(mark as{TypeError,ForDynamic} core::int*);
     if(!this.{self::Constraint::isSatisfied}()) {
       if(this.{self::Constraint::strength}.{core::Object::==}(#C22)) {
         core::print("Could not satisfy a required constraint!");
       }
       return null;
     }
-    this.{self::Constraint::markInputs}(mark as{TypeError} core::int*);
+    this.{self::Constraint::markInputs}(mark as{TypeError,ForDynamic} core::int*);
     self::Variable* out = this.{self::Constraint::output}();
     self::Constraint* overridden = out.{self::Variable::determinedBy};
     if(!overridden.{core::Object::==}(null))
       overridden.{self::Constraint::markUnsatisfied}();
     out.{self::Variable::determinedBy} = this;
-    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError} core::int*))
+    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError,ForDynamic} core::int*))
       core::print("Cycle encountered");
-    out.{self::Variable::mark} = mark as{TypeError} core::int*;
+    out.{self::Variable::mark} = mark as{TypeError,ForDynamic} core::int*;
     return overridden;
   }
   method destroyConstraint() → void {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.strong.transformed.expect
index 4a77a26..2a91755 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.strong.transformed.expect
@@ -52,22 +52,22 @@
     self::planner.{self::Planner::incrementalAdd}(this);
   }
   method satisfy(dynamic mark) → self::Constraint* {
-    this.{self::Constraint::chooseMethod}(mark as{TypeError} core::int*);
+    this.{self::Constraint::chooseMethod}(mark as{TypeError,ForDynamic} core::int*);
     if(!this.{self::Constraint::isSatisfied}()) {
       if(this.{self::Constraint::strength}.{core::Object::==}(#C22)) {
         core::print("Could not satisfy a required constraint!");
       }
       return null;
     }
-    this.{self::Constraint::markInputs}(mark as{TypeError} core::int*);
+    this.{self::Constraint::markInputs}(mark as{TypeError,ForDynamic} core::int*);
     self::Variable* out = this.{self::Constraint::output}();
     self::Constraint* overridden = out.{self::Variable::determinedBy};
     if(!overridden.{core::Object::==}(null))
       overridden.{self::Constraint::markUnsatisfied}();
     out.{self::Variable::determinedBy} = this;
-    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError} core::int*))
+    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError,ForDynamic} core::int*))
       core::print("Cycle encountered");
-    out.{self::Variable::mark} = mark as{TypeError} core::int*;
+    out.{self::Variable::mark} = mark as{TypeError,ForDynamic} core::int*;
     return overridden;
   }
   method destroyConstraint() → void {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.weak.expect
index 4a77a26..2a91755 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.weak.expect
@@ -52,22 +52,22 @@
     self::planner.{self::Planner::incrementalAdd}(this);
   }
   method satisfy(dynamic mark) → self::Constraint* {
-    this.{self::Constraint::chooseMethod}(mark as{TypeError} core::int*);
+    this.{self::Constraint::chooseMethod}(mark as{TypeError,ForDynamic} core::int*);
     if(!this.{self::Constraint::isSatisfied}()) {
       if(this.{self::Constraint::strength}.{core::Object::==}(#C22)) {
         core::print("Could not satisfy a required constraint!");
       }
       return null;
     }
-    this.{self::Constraint::markInputs}(mark as{TypeError} core::int*);
+    this.{self::Constraint::markInputs}(mark as{TypeError,ForDynamic} core::int*);
     self::Variable* out = this.{self::Constraint::output}();
     self::Constraint* overridden = out.{self::Variable::determinedBy};
     if(!overridden.{core::Object::==}(null))
       overridden.{self::Constraint::markUnsatisfied}();
     out.{self::Variable::determinedBy} = this;
-    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError} core::int*))
+    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError,ForDynamic} core::int*))
       core::print("Cycle encountered");
-    out.{self::Variable::mark} = mark as{TypeError} core::int*;
+    out.{self::Variable::mark} = mark as{TypeError,ForDynamic} core::int*;
     return overridden;
   }
   method destroyConstraint() → void {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.weak.transformed.expect
index 4a77a26..2a91755 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/DeltaBlue.dart.weak.transformed.expect
@@ -52,22 +52,22 @@
     self::planner.{self::Planner::incrementalAdd}(this);
   }
   method satisfy(dynamic mark) → self::Constraint* {
-    this.{self::Constraint::chooseMethod}(mark as{TypeError} core::int*);
+    this.{self::Constraint::chooseMethod}(mark as{TypeError,ForDynamic} core::int*);
     if(!this.{self::Constraint::isSatisfied}()) {
       if(this.{self::Constraint::strength}.{core::Object::==}(#C22)) {
         core::print("Could not satisfy a required constraint!");
       }
       return null;
     }
-    this.{self::Constraint::markInputs}(mark as{TypeError} core::int*);
+    this.{self::Constraint::markInputs}(mark as{TypeError,ForDynamic} core::int*);
     self::Variable* out = this.{self::Constraint::output}();
     self::Constraint* overridden = out.{self::Variable::determinedBy};
     if(!overridden.{core::Object::==}(null))
       overridden.{self::Constraint::markUnsatisfied}();
     out.{self::Variable::determinedBy} = this;
-    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError} core::int*))
+    if(!self::planner.{self::Planner::addPropagate}(this, mark as{TypeError,ForDynamic} core::int*))
       core::print("Cycle encountered");
-    out.{self::Variable::mark} = mark as{TypeError} core::int*;
+    out.{self::Variable::mark} = mark as{TypeError,ForDynamic} core::int*;
     return overridden;
   }
   method destroyConstraint() → void {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.outline.expect b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.outline.expect
index 9febcbc1..0f02aec 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.outline.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.outline.expect
@@ -186,7 +186,7 @@
   method cMethod() → dynamic
     ;
   no-such-method-forwarder get interfaceMethod1() → dynamic
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod1, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} dynamic;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod1, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder set property3(dynamic _) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#property3=, 2, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[_]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
   no-such-method-forwarder set interfaceMethod1(dynamic value) → void
@@ -202,7 +202,7 @@
   no-such-method-forwarder method interfaceMethod2() → void
     return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod2, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
   no-such-method-forwarder method abstractMethod() → dynamic
-    return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#abstractMethod, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} dynamic;
+    return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#abstractMethod, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder method interfaceMethod1() → void
     return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod1, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
   no-such-method-forwarder method interfaceMethod3() → void
@@ -226,7 +226,7 @@
     ;
   abstract method noSuchMethod(core::Invocation* _) → dynamic;
   no-such-method-forwarder get interfaceMethod1() → dynamic
-    return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod1, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} dynamic;
+    return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod1, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder set property3(dynamic _) → void
     return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#property3=, 2, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[_]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
   no-such-method-forwarder set interfaceMethod1(dynamic value) → void
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.strong.expect
index eca4d92..4d04d03 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.strong.expect
@@ -182,7 +182,7 @@
   method bMethod() → dynamic {}
   method cMethod() → dynamic {}
   no-such-method-forwarder get interfaceMethod1() → dynamic
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder set property3(dynamic _) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[_]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder set interfaceMethod1(dynamic value) → void
@@ -199,7 +199,7 @@
   no-such-method-forwarder method interfaceMethod2() → void
     return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder method abstractMethod() → dynamic
-    return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C9, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C9, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder method interfaceMethod1() → void
     return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder method interfaceMethod3() → void
@@ -225,7 +225,7 @@
     ;
   abstract method noSuchMethod(core::Invocation* _) → dynamic;
   no-such-method-forwarder get interfaceMethod1() → dynamic
-    return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder set property3(dynamic _) → void
     return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[_]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder set interfaceMethod1(dynamic value) → void
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.weak.expect
index eca4d92..4d04d03 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_members.dart.weak.expect
@@ -182,7 +182,7 @@
   method bMethod() → dynamic {}
   method cMethod() → dynamic {}
   no-such-method-forwarder get interfaceMethod1() → dynamic
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder set property3(dynamic _) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[_]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder set interfaceMethod1(dynamic value) → void
@@ -199,7 +199,7 @@
   no-such-method-forwarder method interfaceMethod2() → void
     return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder method abstractMethod() → dynamic
-    return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C9, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C9, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder method interfaceMethod1() → void
     return this.{self::MyMock1::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder method interfaceMethod3() → void
@@ -225,7 +225,7 @@
     ;
   abstract method noSuchMethod(core::Invocation* _) → dynamic;
   no-such-method-forwarder get interfaceMethod1() → dynamic
-    return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
   no-such-method-forwarder set property3(dynamic _) → void
     return this.{self::MyMock3::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[_]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
   no-such-method-forwarder set interfaceMethod1(dynamic value) → void
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.outline.expect b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.outline.expect
index 7200a65..f027a20 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.outline.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.outline.expect
@@ -23,7 +23,7 @@
   synthetic constructor •() → self::D*
     ;
   no-such-method-forwarder method foo() → self::B*
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} self::B*;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} self::B*;
 }
 static method main() → dynamic
   ;
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.strong.expect
index 8482063..df623b2 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.strong.expect
@@ -27,7 +27,7 @@
     : super self::C::•()
     ;
   no-such-method-forwarder method foo() → self::B*
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} self::B*;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} self::B*;
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.strong.transformed.expect
index 8482063..df623b2 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.strong.transformed.expect
@@ -27,7 +27,7 @@
     : super self::C::•()
     ;
   no-such-method-forwarder method foo() → self::B*
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} self::B*;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} self::B*;
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.weak.expect
index 8482063..df623b2 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.weak.expect
@@ -27,7 +27,7 @@
     : super self::C::•()
     ;
   no-such-method-forwarder method foo() → self::B*
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} self::B*;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} self::B*;
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.weak.transformed.expect
index 8482063..df623b2 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method.dart.weak.transformed.expect
@@ -27,7 +27,7 @@
     : super self::C::•()
     ;
   no-such-method-forwarder method foo() → self::B*
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} self::B*;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} self::B*;
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.strong.expect
index 5c3da0c..6916565 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.strong.expect
@@ -20,7 +20,7 @@
 static method main() → void async {
   core::String* expected = "1 2 3 4 5 6 7 8 9 10";
   self::Node* node = new self::Node::•("1", <self::Node*>[new self::Node::•("2", <self::Node*>[]), await asy::Future::value<self::Node*>(new self::Node::•("3", <self::Node*>[await asy::Future::value<self::Node*>(new self::Node::•("4", <self::Node*>[new self::Node::•("5", <self::Node*>[await asy::Future::value<self::Node*>(new self::Node::•("6", <self::Node*>[await asy::Future::value<self::Node*>(new self::Node::•("7", <self::Node*>[]))])), await asy::Future::value<self::Node*>(new self::Node::•("8", <self::Node*>[])), await asy::Future::value<self::Node*>(new self::Node::•("9", <self::Node*>[]))])]))])), await asy::Future::value<self::Node*>(new self::Node::•("10", <self::Node*>[]))]);
-  core::String* actual = node.{self::Node::toSimpleString}() as{TypeError} core::String*;
+  core::String* actual = node.{self::Node::toSimpleString}() as{TypeError,ForDynamic} core::String*;
   core::print(actual);
   if(!actual.{core::String::==}(expected)) {
     throw "Expected '${expected}' but got '${actual}'";
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.strong.transformed.expect
index 27b7653..2fe75da 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.strong.transformed.expect
@@ -47,7 +47,7 @@
         :async_temporary_0 = _in::unsafeCast<self::Node*>(:result);
         [yield] let dynamic #t10 = asy::_awaitHelper(asy::Future::value<self::Node*>(new self::Node::•("10", <self::Node*>[])), :async_op_then, :async_op_error, :async_op) in null;
         self::Node* node = new self::Node::•("1", <self::Node*>[:async_temporary_2, :async_temporary_0, _in::unsafeCast<self::Node*>(:result)]);
-        core::String* actual = node.{self::Node::toSimpleString}() as{TypeError} core::String*;
+        core::String* actual = node.{self::Node::toSimpleString}() as{TypeError,ForDynamic} core::String*;
         core::print(actual);
         if(!actual.{core::String::==}(expected)) {
           throw "Expected '${expected}' but got '${actual}'";
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.weak.expect
index 5c3da0c..6916565 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.weak.expect
@@ -20,7 +20,7 @@
 static method main() → void async {
   core::String* expected = "1 2 3 4 5 6 7 8 9 10";
   self::Node* node = new self::Node::•("1", <self::Node*>[new self::Node::•("2", <self::Node*>[]), await asy::Future::value<self::Node*>(new self::Node::•("3", <self::Node*>[await asy::Future::value<self::Node*>(new self::Node::•("4", <self::Node*>[new self::Node::•("5", <self::Node*>[await asy::Future::value<self::Node*>(new self::Node::•("6", <self::Node*>[await asy::Future::value<self::Node*>(new self::Node::•("7", <self::Node*>[]))])), await asy::Future::value<self::Node*>(new self::Node::•("8", <self::Node*>[])), await asy::Future::value<self::Node*>(new self::Node::•("9", <self::Node*>[]))])]))])), await asy::Future::value<self::Node*>(new self::Node::•("10", <self::Node*>[]))]);
-  core::String* actual = node.{self::Node::toSimpleString}() as{TypeError} core::String*;
+  core::String* actual = node.{self::Node::toSimpleString}() as{TypeError,ForDynamic} core::String*;
   core::print(actual);
   if(!actual.{core::String::==}(expected)) {
     throw "Expected '${expected}' but got '${actual}'";
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.weak.transformed.expect
index 27b7653..2fe75da 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/async_nested.dart.weak.transformed.expect
@@ -47,7 +47,7 @@
         :async_temporary_0 = _in::unsafeCast<self::Node*>(:result);
         [yield] let dynamic #t10 = asy::_awaitHelper(asy::Future::value<self::Node*>(new self::Node::•("10", <self::Node*>[])), :async_op_then, :async_op_error, :async_op) in null;
         self::Node* node = new self::Node::•("1", <self::Node*>[:async_temporary_2, :async_temporary_0, _in::unsafeCast<self::Node*>(:result)]);
-        core::String* actual = node.{self::Node::toSimpleString}() as{TypeError} core::String*;
+        core::String* actual = node.{self::Node::toSimpleString}() as{TypeError,ForDynamic} core::String*;
         core::print(actual);
         if(!actual.{core::String::==}(expected)) {
           throw "Expected '${expected}' but got '${actual}'";
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.strong.expect
index 9cf401a..a0b6fdd 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.strong.expect
@@ -14,14 +14,14 @@
   static get staticGetter() → core::int*
     return self::C::staticField;
   static set staticSetter(dynamic val) → void {
-    self::C::staticField = val as{TypeError} core::int*;
+    self::C::staticField = val as{TypeError,ForDynamic} core::int*;
   }
   static method staticFoo(core::int* param) → core::int*
     return param;
   get getter() → core::int*
     return this.{self::C::field};
   set setter(dynamic val) → void {
-    this.{self::C::field} = val as{TypeError} core::int*;
+    this.{self::C::field} = val as{TypeError,ForDynamic} core::int*;
   }
   method foo(core::int* param) → core::int*
     return param;
@@ -41,65 +41,65 @@
 static get topLevelGetter() → core::int*
   return self::globalVariable;
 static set topLevelSetter(dynamic val) → void {
-  self::globalVariable = val as{TypeError} core::int*;
+  self::globalVariable = val as{TypeError,ForDynamic} core::int*;
 }
 static method dummy() → dynamic
   return 1;
 static method staticMembers() → dynamic async {
-  core::num* a = self::C::staticField.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* a = self::C::staticField.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, a);
-  core::num* f = (self::C::staticField = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* f = (self::C::staticField = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, f);
-  core::num* b = self::C::staticGetter.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* b = self::C::staticGetter.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, b);
-  core::num* c = (self::C::staticSetter = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* c = (self::C::staticSetter = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, c);
-  core::num* d = self::C::staticFoo(2).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = self::C::staticFoo(2).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(3, d);
-  core::num* e = self::C::staticField.{core::num::+}(self::C::staticGetter).{core::num::+}(self::C::staticSetter = 1).{core::num::+}(self::C::staticFoo(1)).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = self::C::staticField.{core::num::+}(self::C::staticGetter).{core::num::+}(self::C::staticSetter = 1).{core::num::+}(self::C::staticFoo(1)).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(5, e);
 }
 static method topLevelMembers() → dynamic async {
-  core::num* a = self::globalVariable.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* a = self::globalVariable.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, a);
-  core::num* b = self::topLevelGetter.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* b = self::topLevelGetter.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, b);
-  core::num* c = (self::topLevelSetter = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* c = (self::topLevelSetter = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, c);
-  core::num* d = self::topLevelFoo(1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = self::topLevelFoo(1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, d);
-  core::num* e = self::globalVariable.{core::num::+}(self::topLevelGetter).{core::num::+}(self::topLevelSetter = 1).{core::num::+}(self::topLevelFoo(1)).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = self::globalVariable.{core::num::+}(self::topLevelGetter).{core::num::+}(self::topLevelSetter = 1).{core::num::+}(self::topLevelFoo(1)).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(5, e);
 }
 static method instanceMembers() → dynamic async {
   self::C* inst = new self::C::•();
-  core::num* a = inst.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* a = inst.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, a);
-  core::num* b = inst.{self::C::getter}.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* b = inst.{self::C::getter}.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, b);
-  core::num* c = (inst.{self::C::setter} = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* c = (inst.{self::C::setter} = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, c);
-  core::num* d = inst.{self::C::foo}(1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = inst.{self::C::foo}(1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, d);
-  core::num* e = inst.{self::C::field}.{core::num::+}(inst.{self::C::getter}).{core::num::+}(inst.{self::C::setter} = 1).{core::num::+}(inst.{self::C::foo}(1)).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = inst.{self::C::field}.{core::num::+}(inst.{self::C::getter}).{core::num::+}(inst.{self::C::setter} = 1).{core::num::+}(inst.{self::C::foo}(1)).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(5, e);
 }
 static method others() → dynamic async {
   core::String* a = "${self::globalVariable} ${await self::dummy()} ".{core::String::+}(await "someString");
   self::expect("1 1 someString", a);
   self::C* c = new self::C::•();
-  core::num* d = c.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = c.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   core::int* cnt = 2;
   core::List<core::int*>* b = <core::int*>[1, 2, 3];
-  b.{core::List::[]=}(cnt, await self::dummy() as{TypeError} core::int*);
+  b.{core::List::[]=}(cnt, await self::dummy() as{TypeError,ForDynamic} core::int*);
   self::expect(1, b.{core::List::[]}(cnt));
-  core::num* e = b.{core::List::[]}(0).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = b.{core::List::[]}(0).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, e);
 }
 static method conditionals() → dynamic async {
   core::bool* a = false;
   core::bool* b = true;
-  core::bool* c = a || b || await self::dummy() as{TypeError} core::bool*;
+  core::bool* c = a || b || await self::dummy() as{TypeError,ForDynamic} core::bool*;
   self::expect(true, c);
   dynamic d = a || b ?{dynamic} a : await self::dummy();
   self::expect(false, d);
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.strong.transformed.expect
index b6697d5..3840565 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.strong.transformed.expect
@@ -15,14 +15,14 @@
   static get staticGetter() → core::int*
     return self::C::staticField;
   static set staticSetter(dynamic val) → void {
-    self::C::staticField = val as{TypeError} core::int*;
+    self::C::staticField = val as{TypeError,ForDynamic} core::int*;
   }
   static method staticFoo(core::int* param) → core::int*
     return param;
   get getter() → core::int*
     return this.{self::C::field};
   set setter(dynamic val) → void {
-    this.{self::C::field} = val as{TypeError} core::int*;
+    this.{self::C::field} = val as{TypeError,ForDynamic} core::int*;
   }
   method foo(core::int* param) → core::int*
     return param;
@@ -42,7 +42,7 @@
 static get topLevelGetter() → core::int*
   return self::globalVariable;
 static set topLevelSetter(dynamic val) → void {
-  self::globalVariable = val as{TypeError} core::int*;
+  self::globalVariable = val as{TypeError,ForDynamic} core::int*;
 }
 static method dummy() → dynamic
   return 1;
@@ -67,27 +67,27 @@
       {
         :async_temporary_0 = self::C::staticField;
         [yield] let dynamic #t1 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, a);
         :async_temporary_1 = self::C::staticField = 1;
         [yield] let dynamic #t2 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* f = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* f = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, f);
         :async_temporary_2 = self::C::staticGetter;
         [yield] let dynamic #t3 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* b = :async_temporary_2.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* b = :async_temporary_2.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, b);
         :async_temporary_3 = self::C::staticSetter = 1;
         [yield] let dynamic #t4 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* c = :async_temporary_3.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* c = :async_temporary_3.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, c);
         :async_temporary_4 = self::C::staticFoo(2);
         [yield] let dynamic #t5 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(3, d);
         :async_temporary_5 = self::C::staticField.{core::num::+}(self::C::staticGetter).{core::num::+}(self::C::staticSetter = 1).{core::num::+}(self::C::staticFoo(1));
         [yield] let dynamic #t6 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_5.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_5.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(5, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -122,23 +122,23 @@
       {
         :async_temporary_0 = self::globalVariable;
         [yield] let dynamic #t7 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, a);
         :async_temporary_1 = self::topLevelGetter;
         [yield] let dynamic #t8 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, b);
         :async_temporary_2 = self::topLevelSetter = 1;
         [yield] let dynamic #t9 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, c);
         :async_temporary_3 = self::topLevelFoo(1);
         [yield] let dynamic #t10 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, d);
         :async_temporary_4 = self::globalVariable.{core::num::+}(self::topLevelGetter).{core::num::+}(self::topLevelSetter = 1).{core::num::+}(self::topLevelFoo(1));
         [yield] let dynamic #t11 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(5, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -174,23 +174,23 @@
         self::C* inst = new self::C::•();
         :async_temporary_0 = inst.{self::C::field};
         [yield] let dynamic #t12 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, a);
         :async_temporary_1 = inst.{self::C::getter};
         [yield] let dynamic #t13 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, b);
         :async_temporary_2 = inst.{self::C::setter} = 1;
         [yield] let dynamic #t14 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, c);
         :async_temporary_3 = inst.{self::C::foo}(1);
         [yield] let dynamic #t15 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, d);
         :async_temporary_4 = inst.{self::C::field}.{core::num::+}(inst.{self::C::getter}).{core::num::+}(inst.{self::C::setter} = 1).{core::num::+}(inst.{self::C::foo}(1));
         [yield] let dynamic #t16 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(5, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -232,17 +232,17 @@
         self::C* c = new self::C::•();
         :async_temporary_1 = c.{self::C::field};
         [yield] let dynamic #t19 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         core::int* cnt = 2;
         core::List<core::int*>* b = <core::int*>[1, 2, 3];
         :async_temporary_3 = b;
         :async_temporary_2 = cnt;
         [yield] let dynamic #t20 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        :async_temporary_3.{core::List::[]=}(:async_temporary_2, :result as{TypeError} core::int*);
+        :async_temporary_3.{core::List::[]=}(:async_temporary_2, :result as{TypeError,ForDynamic} core::int*);
         self::expect(1, b.{core::List::[]}(cnt));
         :async_temporary_4 = b.{core::List::[]}(0);
         [yield] let dynamic #t21 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -282,7 +282,7 @@
           ;
         else {
           [yield] let dynamic #t22 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-          :async_temporary_0 = (:result as{TypeError} core::bool*).==(true);
+          :async_temporary_0 = (:result as{TypeError,ForDynamic} core::bool*).==(true);
         }
         core::bool* c = :async_temporary_0;
         self::expect(true, c);
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.weak.expect
index 9cf401a..a0b6fdd 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.weak.expect
@@ -14,14 +14,14 @@
   static get staticGetter() → core::int*
     return self::C::staticField;
   static set staticSetter(dynamic val) → void {
-    self::C::staticField = val as{TypeError} core::int*;
+    self::C::staticField = val as{TypeError,ForDynamic} core::int*;
   }
   static method staticFoo(core::int* param) → core::int*
     return param;
   get getter() → core::int*
     return this.{self::C::field};
   set setter(dynamic val) → void {
-    this.{self::C::field} = val as{TypeError} core::int*;
+    this.{self::C::field} = val as{TypeError,ForDynamic} core::int*;
   }
   method foo(core::int* param) → core::int*
     return param;
@@ -41,65 +41,65 @@
 static get topLevelGetter() → core::int*
   return self::globalVariable;
 static set topLevelSetter(dynamic val) → void {
-  self::globalVariable = val as{TypeError} core::int*;
+  self::globalVariable = val as{TypeError,ForDynamic} core::int*;
 }
 static method dummy() → dynamic
   return 1;
 static method staticMembers() → dynamic async {
-  core::num* a = self::C::staticField.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* a = self::C::staticField.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, a);
-  core::num* f = (self::C::staticField = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* f = (self::C::staticField = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, f);
-  core::num* b = self::C::staticGetter.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* b = self::C::staticGetter.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, b);
-  core::num* c = (self::C::staticSetter = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* c = (self::C::staticSetter = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, c);
-  core::num* d = self::C::staticFoo(2).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = self::C::staticFoo(2).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(3, d);
-  core::num* e = self::C::staticField.{core::num::+}(self::C::staticGetter).{core::num::+}(self::C::staticSetter = 1).{core::num::+}(self::C::staticFoo(1)).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = self::C::staticField.{core::num::+}(self::C::staticGetter).{core::num::+}(self::C::staticSetter = 1).{core::num::+}(self::C::staticFoo(1)).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(5, e);
 }
 static method topLevelMembers() → dynamic async {
-  core::num* a = self::globalVariable.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* a = self::globalVariable.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, a);
-  core::num* b = self::topLevelGetter.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* b = self::topLevelGetter.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, b);
-  core::num* c = (self::topLevelSetter = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* c = (self::topLevelSetter = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, c);
-  core::num* d = self::topLevelFoo(1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = self::topLevelFoo(1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, d);
-  core::num* e = self::globalVariable.{core::num::+}(self::topLevelGetter).{core::num::+}(self::topLevelSetter = 1).{core::num::+}(self::topLevelFoo(1)).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = self::globalVariable.{core::num::+}(self::topLevelGetter).{core::num::+}(self::topLevelSetter = 1).{core::num::+}(self::topLevelFoo(1)).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(5, e);
 }
 static method instanceMembers() → dynamic async {
   self::C* inst = new self::C::•();
-  core::num* a = inst.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* a = inst.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, a);
-  core::num* b = inst.{self::C::getter}.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* b = inst.{self::C::getter}.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, b);
-  core::num* c = (inst.{self::C::setter} = 1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* c = (inst.{self::C::setter} = 1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, c);
-  core::num* d = inst.{self::C::foo}(1).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = inst.{self::C::foo}(1).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, d);
-  core::num* e = inst.{self::C::field}.{core::num::+}(inst.{self::C::getter}).{core::num::+}(inst.{self::C::setter} = 1).{core::num::+}(inst.{self::C::foo}(1)).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = inst.{self::C::field}.{core::num::+}(inst.{self::C::getter}).{core::num::+}(inst.{self::C::setter} = 1).{core::num::+}(inst.{self::C::foo}(1)).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(5, e);
 }
 static method others() → dynamic async {
   core::String* a = "${self::globalVariable} ${await self::dummy()} ".{core::String::+}(await "someString");
   self::expect("1 1 someString", a);
   self::C* c = new self::C::•();
-  core::num* d = c.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* d = c.{self::C::field}.{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   core::int* cnt = 2;
   core::List<core::int*>* b = <core::int*>[1, 2, 3];
-  b.{core::List::[]=}(cnt, await self::dummy() as{TypeError} core::int*);
+  b.{core::List::[]=}(cnt, await self::dummy() as{TypeError,ForDynamic} core::int*);
   self::expect(1, b.{core::List::[]}(cnt));
-  core::num* e = b.{core::List::[]}(0).{core::num::+}(await self::dummy() as{TypeError} core::num*);
+  core::num* e = b.{core::List::[]}(0).{core::num::+}(await self::dummy() as{TypeError,ForDynamic} core::num*);
   self::expect(2, e);
 }
 static method conditionals() → dynamic async {
   core::bool* a = false;
   core::bool* b = true;
-  core::bool* c = a || b || await self::dummy() as{TypeError} core::bool*;
+  core::bool* c = a || b || await self::dummy() as{TypeError,ForDynamic} core::bool*;
   self::expect(true, c);
   dynamic d = a || b ?{dynamic} a : await self::dummy();
   self::expect(false, d);
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.weak.transformed.expect
index b6697d5..3840565 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/await_complex.dart.weak.transformed.expect
@@ -15,14 +15,14 @@
   static get staticGetter() → core::int*
     return self::C::staticField;
   static set staticSetter(dynamic val) → void {
-    self::C::staticField = val as{TypeError} core::int*;
+    self::C::staticField = val as{TypeError,ForDynamic} core::int*;
   }
   static method staticFoo(core::int* param) → core::int*
     return param;
   get getter() → core::int*
     return this.{self::C::field};
   set setter(dynamic val) → void {
-    this.{self::C::field} = val as{TypeError} core::int*;
+    this.{self::C::field} = val as{TypeError,ForDynamic} core::int*;
   }
   method foo(core::int* param) → core::int*
     return param;
@@ -42,7 +42,7 @@
 static get topLevelGetter() → core::int*
   return self::globalVariable;
 static set topLevelSetter(dynamic val) → void {
-  self::globalVariable = val as{TypeError} core::int*;
+  self::globalVariable = val as{TypeError,ForDynamic} core::int*;
 }
 static method dummy() → dynamic
   return 1;
@@ -67,27 +67,27 @@
       {
         :async_temporary_0 = self::C::staticField;
         [yield] let dynamic #t1 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, a);
         :async_temporary_1 = self::C::staticField = 1;
         [yield] let dynamic #t2 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* f = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* f = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, f);
         :async_temporary_2 = self::C::staticGetter;
         [yield] let dynamic #t3 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* b = :async_temporary_2.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* b = :async_temporary_2.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, b);
         :async_temporary_3 = self::C::staticSetter = 1;
         [yield] let dynamic #t4 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* c = :async_temporary_3.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* c = :async_temporary_3.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, c);
         :async_temporary_4 = self::C::staticFoo(2);
         [yield] let dynamic #t5 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(3, d);
         :async_temporary_5 = self::C::staticField.{core::num::+}(self::C::staticGetter).{core::num::+}(self::C::staticSetter = 1).{core::num::+}(self::C::staticFoo(1));
         [yield] let dynamic #t6 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_5.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_5.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(5, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -122,23 +122,23 @@
       {
         :async_temporary_0 = self::globalVariable;
         [yield] let dynamic #t7 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, a);
         :async_temporary_1 = self::topLevelGetter;
         [yield] let dynamic #t8 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, b);
         :async_temporary_2 = self::topLevelSetter = 1;
         [yield] let dynamic #t9 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, c);
         :async_temporary_3 = self::topLevelFoo(1);
         [yield] let dynamic #t10 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, d);
         :async_temporary_4 = self::globalVariable.{core::num::+}(self::topLevelGetter).{core::num::+}(self::topLevelSetter = 1).{core::num::+}(self::topLevelFoo(1));
         [yield] let dynamic #t11 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(5, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -174,23 +174,23 @@
         self::C* inst = new self::C::•();
         :async_temporary_0 = inst.{self::C::field};
         [yield] let dynamic #t12 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* a = :async_temporary_0.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, a);
         :async_temporary_1 = inst.{self::C::getter};
         [yield] let dynamic #t13 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* b = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, b);
         :async_temporary_2 = inst.{self::C::setter} = 1;
         [yield] let dynamic #t14 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* c = :async_temporary_2.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, c);
         :async_temporary_3 = inst.{self::C::foo}(1);
         [yield] let dynamic #t15 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_3.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, d);
         :async_temporary_4 = inst.{self::C::field}.{core::num::+}(inst.{self::C::getter}).{core::num::+}(inst.{self::C::setter} = 1).{core::num::+}(inst.{self::C::foo}(1));
         [yield] let dynamic #t16 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(5, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -232,17 +232,17 @@
         self::C* c = new self::C::•();
         :async_temporary_1 = c.{self::C::field};
         [yield] let dynamic #t19 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* d = :async_temporary_1.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* d = :async_temporary_1.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         core::int* cnt = 2;
         core::List<core::int*>* b = <core::int*>[1, 2, 3];
         :async_temporary_3 = b;
         :async_temporary_2 = cnt;
         [yield] let dynamic #t20 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        :async_temporary_3.{core::List::[]=}(:async_temporary_2, :result as{TypeError} core::int*);
+        :async_temporary_3.{core::List::[]=}(:async_temporary_2, :result as{TypeError,ForDynamic} core::int*);
         self::expect(1, b.{core::List::[]}(cnt));
         :async_temporary_4 = b.{core::List::[]}(0);
         [yield] let dynamic #t21 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError} core::num*);
+        core::num* e = :async_temporary_4.{core::num::+}(:result as{TypeError,ForDynamic} core::num*);
         self::expect(2, e);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
@@ -282,7 +282,7 @@
           ;
         else {
           [yield] let dynamic #t22 = asy::_awaitHelper(self::dummy(), :async_op_then, :async_op_error, :async_op) in null;
-          :async_temporary_0 = (:result as{TypeError} core::bool*).==(true);
+          :async_temporary_0 = (:result as{TypeError,ForDynamic} core::bool*).==(true);
         }
         core::bool* c = :async_temporary_0;
         self::expect(true, c);
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.strong.expect
index cd1a2ae..657464a 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.strong.expect
@@ -24,14 +24,14 @@
 static field self::B<core::num*>* b = new self::B::•<core::int*>();
 static method main() → dynamic {
   try {
-    self::a.{self::A::foo}() as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    self::a.{self::A::foo}() as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    self::b.{self::B::foo}() as{TypeError} (core::num*) →* void;
+    self::b.{self::B::foo}() as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.strong.transformed.expect
index cd1a2ae..657464a 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.strong.transformed.expect
@@ -24,14 +24,14 @@
 static field self::B<core::num*>* b = new self::B::•<core::int*>();
 static method main() → dynamic {
   try {
-    self::a.{self::A::foo}() as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    self::a.{self::A::foo}() as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    self::b.{self::B::foo}() as{TypeError} (core::num*) →* void;
+    self::b.{self::B::foo}() as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.weak.expect
index cd1a2ae..657464a 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.weak.expect
@@ -24,14 +24,14 @@
 static field self::B<core::num*>* b = new self::B::•<core::int*>();
 static method main() → dynamic {
   try {
-    self::a.{self::A::foo}() as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    self::a.{self::A::foo}() as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    self::b.{self::B::foo}() as{TypeError} (core::num*) →* void;
+    self::b.{self::B::foo}() as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.weak.transformed.expect
index cd1a2ae..657464a 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/bug37476.dart.weak.transformed.expect
@@ -24,14 +24,14 @@
 static field self::B<core::num*>* b = new self::B::•<core::int*>();
 static method main() → dynamic {
   try {
-    self::a.{self::A::foo}() as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    self::a.{self::A::foo}() as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    self::b.{self::B::foo}() as{TypeError} (core::num*) →* void;
+    self::b.{self::B::foo}() as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "Expected TypeError";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.strong.expect
index 92d9353..5c59c15 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.strong.expect
@@ -7,7 +7,7 @@
 
 static method main() → dynamic {}
 static method test() → dynamic {
-  let final dynamic #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError} core::int*;
+  let final dynamic #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError,ForDynamic} core::int*;
   let final dynamic #t2 = CheckLibraryIsLoaded(lib) in def::m(self::m2());
 }
 static method m2() → dynamic
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.strong.transformed.expect
index 6da0135..441b505 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.strong.transformed.expect
@@ -7,7 +7,7 @@
 
 static method main() → dynamic {}
 static method test() → dynamic {
-  let final core::Object* #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError} core::int*;
+  let final core::Object* #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError,ForDynamic} core::int*;
   let final core::Object* #t2 = CheckLibraryIsLoaded(lib) in def::m(self::m2());
 }
 static method m2() → dynamic
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.weak.expect
index 92d9353..5c59c15 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.weak.expect
@@ -7,7 +7,7 @@
 
 static method main() → dynamic {}
 static method test() → dynamic {
-  let final dynamic #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError} core::int*;
+  let final dynamic #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError,ForDynamic} core::int*;
   let final dynamic #t2 = CheckLibraryIsLoaded(lib) in def::m(self::m2());
 }
 static method m2() → dynamic
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.weak.transformed.expect
index 6da0135..441b505 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/check_deferred_before_args.dart.weak.transformed.expect
@@ -7,7 +7,7 @@
 
 static method main() → dynamic {}
 static method test() → dynamic {
-  let final core::Object* #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError} core::int*;
+  let final core::Object* #t1 = CheckLibraryIsLoaded(lib) in def::x = self::m2() as{TypeError,ForDynamic} core::int*;
   let final core::Object* #t2 = CheckLibraryIsLoaded(lib) in def::m(self::m2());
 }
 static method m2() → dynamic
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.strong.expect
index 454a0a4..5e9a421 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.strong.expect
@@ -16,7 +16,7 @@
 }
 class B extends self::A {
   constructor •(dynamic x) → self::B*
-    : super self::A::•(x as{TypeError} core::int*)
+    : super self::A::•(x as{TypeError,ForDynamic} core::int*)
     ;
   method method() → dynamic {
     core::print("B.method x: ${this.{self::A::x}} y: ${this.{self::A::y}}");
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.strong.transformed.expect
index 454a0a4..5e9a421 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.strong.transformed.expect
@@ -16,7 +16,7 @@
 }
 class B extends self::A {
   constructor •(dynamic x) → self::B*
-    : super self::A::•(x as{TypeError} core::int*)
+    : super self::A::•(x as{TypeError,ForDynamic} core::int*)
     ;
   method method() → dynamic {
     core::print("B.method x: ${this.{self::A::x}} y: ${this.{self::A::y}}");
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.weak.expect
index 454a0a4..5e9a421 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.weak.expect
@@ -16,7 +16,7 @@
 }
 class B extends self::A {
   constructor •(dynamic x) → self::B*
-    : super self::A::•(x as{TypeError} core::int*)
+    : super self::A::•(x as{TypeError,ForDynamic} core::int*)
     ;
   method method() → dynamic {
     core::print("B.method x: ${this.{self::A::x}} y: ${this.{self::A::y}}");
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.weak.transformed.expect
index 454a0a4..5e9a421 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/classes.dart.weak.transformed.expect
@@ -16,7 +16,7 @@
 }
 class B extends self::A {
   constructor •(dynamic x) → self::B*
-    : super self::A::•(x as{TypeError} core::int*)
+    : super self::A::•(x as{TypeError,ForDynamic} core::int*)
     ;
   method method() → dynamic {
     core::print("B.method x: ${this.{self::A::x}} y: ${this.{self::A::y}}");
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.strong.expect
index 27979ba..34fc7a1 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.strong.expect
@@ -36,7 +36,7 @@
   constructor •() → self::C2*
     : self::C2::f = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart:8:27: Error: This couldn't be parsed.
 class C2 { int f; C2() : f; }
-                          ^" as{TypeError} core::int*, super core::Object::•()
+                          ^" as{TypeError,ForDynamic} core::int*, super core::Object::•()
     ;
 }
 class C3 extends core::Object {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.strong.transformed.expect
index 27979ba..34fc7a1 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.strong.transformed.expect
@@ -36,7 +36,7 @@
   constructor •() → self::C2*
     : self::C2::f = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart:8:27: Error: This couldn't be parsed.
 class C2 { int f; C2() : f; }
-                          ^" as{TypeError} core::int*, super core::Object::•()
+                          ^" as{TypeError,ForDynamic} core::int*, super core::Object::•()
     ;
 }
 class C3 extends core::Object {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.weak.expect
index 27979ba..34fc7a1 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.weak.expect
@@ -36,7 +36,7 @@
   constructor •() → self::C2*
     : self::C2::f = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart:8:27: Error: This couldn't be parsed.
 class C2 { int f; C2() : f; }
-                          ^" as{TypeError} core::int*, super core::Object::•()
+                          ^" as{TypeError,ForDynamic} core::int*, super core::Object::•()
     ;
 }
 class C3 extends core::Object {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.weak.transformed.expect
index 27979ba..34fc7a1 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart.weak.transformed.expect
@@ -36,7 +36,7 @@
   constructor •() → self::C2*
     : self::C2::f = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/constructor_initializer_invalid.dart:8:27: Error: This couldn't be parsed.
 class C2 { int f; C2() : f; }
-                          ^" as{TypeError} core::int*, super core::Object::•()
+                          ^" as{TypeError,ForDynamic} core::int*, super core::Object::•()
     ;
 }
 class C3 extends core::Object {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.strong.expect
index f133a9d..3044135 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.strong.expect
@@ -7,19 +7,19 @@
   final core::List<core::int*>* aList = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
     #t1.{core::List::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(3);
     else
       #t1.{core::List::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t1.{core::List::add}(4);
     for (core::int* i in <core::int*>[5, 6, 7])
       #t1.{core::List::add}(i);
     for (core::int* i in <core::int*>[8, 9, 10])
-      if(self::oracle() as{TypeError} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t1.{core::List::add}(i);
     for (core::int* i = 11; i.{core::num::<=}(14); i = i.{core::num::+}(1))
       #t1.{core::List::add}(i);
@@ -27,19 +27,19 @@
   final core::Set<core::int*>* aSet = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
     #t2.{core::Set::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(3);
     else
       #t2.{core::Set::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t2.{core::Set::add}(4);
     for (core::int* i in <core::int*>[5, 6, 7])
       #t2.{core::Set::add}(i);
     for (core::int* i in <core::int*>[8, 9, 10])
-      if(self::oracle() as{TypeError} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t2.{core::Set::add}(i);
     for (core::int* i = 11; i.{core::num::<=}(14); i = i.{core::num::+}(1))
       #t2.{core::Set::add}(i);
@@ -47,19 +47,19 @@
   final core::Map<core::int*, core::int*>* aMap = block {
     final core::Map<core::int*, core::int*>* #t3 = <core::int*, core::int*>{};
     #t3.{core::Map::[]=}(1, 1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(2, 2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(3, 3);
     else
       #t3.{core::Map::[]=}(1.{core::int::unary-}(), 1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t3.{core::Map::[]=}(4, 4);
     for (core::int* i in <core::int*>[5, 6, 7])
       #t3.{core::Map::[]=}(i, i);
     for (core::int* i in <core::int*>[8, 9, 10])
-      if(self::oracle() as{TypeError} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t3.{core::Map::[]=}(i, i);
     for (core::int* i = 11; i.{core::num::<=}(14); i = i.{core::num::+}(1))
       #t3.{core::Map::[]=}(i, i);
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.strong.transformed.expect
index ac4ad8d..7bd3d63 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.strong.transformed.expect
@@ -8,14 +8,14 @@
   final core::List<core::int*>* aList = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
     #t1.{core::List::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(3);
     else
       #t1.{core::List::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t1.{core::List::add}(4);
     {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[5, 6, 7]).{core::Iterable::iterator};
@@ -28,7 +28,7 @@
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[8, 9, 10]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int* i = :sync-for-iterator.{core::Iterator::current};
-        if(self::oracle() as{TypeError} core::bool*)
+        if(self::oracle() as{TypeError,ForDynamic} core::bool*)
           #t1.{core::List::add}(i);
       }
     }
@@ -38,14 +38,14 @@
   final core::Set<core::int*>* aSet = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
     #t2.{core::Set::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(3);
     else
       #t2.{core::Set::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t2.{core::Set::add}(4);
     {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[5, 6, 7]).{core::Iterable::iterator};
@@ -58,7 +58,7 @@
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[8, 9, 10]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int* i = :sync-for-iterator.{core::Iterator::current};
-        if(self::oracle() as{TypeError} core::bool*)
+        if(self::oracle() as{TypeError,ForDynamic} core::bool*)
           #t2.{core::Set::add}(i);
       }
     }
@@ -68,14 +68,14 @@
   final core::Map<core::int*, core::int*>* aMap = block {
     final core::Map<core::int*, core::int*>* #t3 = <core::int*, core::int*>{};
     #t3.{core::Map::[]=}(1, 1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(2, 2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(3, 3);
     else
       #t3.{core::Map::[]=}(1.{core::int::unary-}(), 1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t3.{core::Map::[]=}(4, 4);
     {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[5, 6, 7]).{core::Iterable::iterator};
@@ -88,7 +88,7 @@
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[8, 9, 10]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int* i = :sync-for-iterator.{core::Iterator::current};
-        if(self::oracle() as{TypeError} core::bool*)
+        if(self::oracle() as{TypeError,ForDynamic} core::bool*)
           #t3.{core::Map::[]=}(i, i);
       }
     }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.weak.expect
index f133a9d..3044135 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.weak.expect
@@ -7,19 +7,19 @@
   final core::List<core::int*>* aList = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
     #t1.{core::List::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(3);
     else
       #t1.{core::List::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t1.{core::List::add}(4);
     for (core::int* i in <core::int*>[5, 6, 7])
       #t1.{core::List::add}(i);
     for (core::int* i in <core::int*>[8, 9, 10])
-      if(self::oracle() as{TypeError} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t1.{core::List::add}(i);
     for (core::int* i = 11; i.{core::num::<=}(14); i = i.{core::num::+}(1))
       #t1.{core::List::add}(i);
@@ -27,19 +27,19 @@
   final core::Set<core::int*>* aSet = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
     #t2.{core::Set::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(3);
     else
       #t2.{core::Set::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t2.{core::Set::add}(4);
     for (core::int* i in <core::int*>[5, 6, 7])
       #t2.{core::Set::add}(i);
     for (core::int* i in <core::int*>[8, 9, 10])
-      if(self::oracle() as{TypeError} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t2.{core::Set::add}(i);
     for (core::int* i = 11; i.{core::num::<=}(14); i = i.{core::num::+}(1))
       #t2.{core::Set::add}(i);
@@ -47,19 +47,19 @@
   final core::Map<core::int*, core::int*>* aMap = block {
     final core::Map<core::int*, core::int*>* #t3 = <core::int*, core::int*>{};
     #t3.{core::Map::[]=}(1, 1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(2, 2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(3, 3);
     else
       #t3.{core::Map::[]=}(1.{core::int::unary-}(), 1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t3.{core::Map::[]=}(4, 4);
     for (core::int* i in <core::int*>[5, 6, 7])
       #t3.{core::Map::[]=}(i, i);
     for (core::int* i in <core::int*>[8, 9, 10])
-      if(self::oracle() as{TypeError} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t3.{core::Map::[]=}(i, i);
     for (core::int* i = 11; i.{core::num::<=}(14); i = i.{core::num::+}(1))
       #t3.{core::Map::[]=}(i, i);
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.weak.transformed.expect
index ac4ad8d..7bd3d63 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection.dart.weak.transformed.expect
@@ -8,14 +8,14 @@
   final core::List<core::int*>* aList = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
     #t1.{core::List::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(3);
     else
       #t1.{core::List::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t1.{core::List::add}(4);
     {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[5, 6, 7]).{core::Iterable::iterator};
@@ -28,7 +28,7 @@
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[8, 9, 10]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int* i = :sync-for-iterator.{core::Iterator::current};
-        if(self::oracle() as{TypeError} core::bool*)
+        if(self::oracle() as{TypeError,ForDynamic} core::bool*)
           #t1.{core::List::add}(i);
       }
     }
@@ -38,14 +38,14 @@
   final core::Set<core::int*>* aSet = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
     #t2.{core::Set::add}(1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(3);
     else
       #t2.{core::Set::add}(1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t2.{core::Set::add}(4);
     {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[5, 6, 7]).{core::Iterable::iterator};
@@ -58,7 +58,7 @@
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[8, 9, 10]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int* i = :sync-for-iterator.{core::Iterator::current};
-        if(self::oracle() as{TypeError} core::bool*)
+        if(self::oracle() as{TypeError,ForDynamic} core::bool*)
           #t2.{core::Set::add}(i);
       }
     }
@@ -68,14 +68,14 @@
   final core::Map<core::int*, core::int*>* aMap = block {
     final core::Map<core::int*, core::int*>* #t3 = <core::int*, core::int*>{};
     #t3.{core::Map::[]=}(1, 1);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(2, 2);
-    if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}(3, 3);
     else
       #t3.{core::Map::[]=}(1.{core::int::unary-}(), 1.{core::int::unary-}());
-    if(self::oracle() as{TypeError} core::bool*)
-      if(self::oracle() as{TypeError} core::bool*)
+    if(self::oracle() as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle() as{TypeError,ForDynamic} core::bool*)
         #t3.{core::Map::[]=}(4, 4);
     {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[5, 6, 7]).{core::Iterable::iterator};
@@ -88,7 +88,7 @@
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[8, 9, 10]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int* i = :sync-for-iterator.{core::Iterator::current};
-        if(self::oracle() as{TypeError} core::bool*)
+        if(self::oracle() as{TypeError,ForDynamic} core::bool*)
           #t3.{core::Map::[]=}(i, i);
       }
     }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.strong.expect
index 384c9be..2c46fb9 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.strong.expect
@@ -443,193 +443,193 @@
 static method testIfElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::Map<core::String*, core::int*>* mapToInt, core::Map<core::String*, core::double*>* mapToDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(42);
   } =>#t1;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(42);
     #t2.{core::Set::add}(null);
   } =>#t2;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t3 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}("bar", 42);
     #t3.{core::Map::[]=}("baz", null);
   } =>#t3;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t4 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t4.{core::List::add}(dynVar);
   } =>#t4;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t5 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t5.{core::Set::add}(dynVar);
     #t5.{core::Set::add}(null);
   } =>#t5;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t6 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t6.{core::Map::[]=}("bar", dynVar);
     #t6.{core::Map::[]=}("baz", null);
   } =>#t6;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t7 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t7.{core::List::add}(<core::int*>[42]);
   } =>#t7;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t8 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t8.{core::Set::add}(<core::int*>[42]);
     #t8.{core::Set::add}(null);
   } =>#t8;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t9 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t9.{core::Map::[]=}("bar", <core::int*>[42]);
     #t9.{core::Map::[]=}("baz", null);
   } =>#t9;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t10 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t11 in <core::int*>[42])
         #t10.{core::List::add}(#t11);
   } =>#t10;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t12 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t13 in <core::int*>[42])
         #t12.{core::Set::add}(#t13);
     #t12.{core::Set::add}(null);
   } =>#t12;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t14 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::int*>* #t15 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
         #t14.{core::Map::[]=}(#t15.{core::MapEntry::key}, #t15.{core::MapEntry::value});
     #t14.{core::Map::[]=}("baz", null);
   } =>#t14;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t16 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t17 in <dynamic>[dynVar])
         #t16.{core::List::add}(#t17);
   } =>#t16;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t18 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t19 in <dynamic>[dynVar])
         #t18.{core::Set::add}(#t19);
     #t18.{core::Set::add}(null);
   } =>#t18;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t20 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, dynamic>* #t21 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
         #t20.{core::Map::[]=}(#t21.{core::MapEntry::key}, #t21.{core::MapEntry::value});
     #t20.{core::Map::[]=}("baz", null);
   } =>#t20;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t22 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t23 in <core::List<core::int*>*>[<core::int*>[42]])
         #t22.{core::List::add}(#t23);
   } =>#t22;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t24 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t25 in <core::List<core::int*>*>[<core::int*>[42]])
         #t24.{core::Set::add}(#t25);
     #t24.{core::Set::add}(null);
   } =>#t24;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t26 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t27 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
         #t26.{core::Map::[]=}(#t27.{core::MapEntry::key}, #t27.{core::MapEntry::value});
     #t26.{core::Map::[]=}("baz", null);
   } =>#t26;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t28 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t29 in <core::int*>[42])
           #t28.{core::List::add}(#t29);
   } =>#t28;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t30 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t31 in <core::int*>[42])
           #t30.{core::Set::add}(#t31);
     #t30.{core::Set::add}(null);
   } =>#t30;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t32 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::int*>* #t33 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
           #t32.{core::Map::[]=}(#t33.{core::MapEntry::key}, #t33.{core::MapEntry::value});
     #t32.{core::Map::[]=}("baz", null);
   } =>#t32;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t34 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t35 in <dynamic>[dynVar])
           #t34.{core::List::add}(#t35);
   } =>#t34;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t36 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t37 in <dynamic>[dynVar])
           #t36.{core::Set::add}(#t37);
     #t36.{core::Set::add}(null);
   } =>#t36;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t38 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, dynamic>* #t39 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
           #t38.{core::Map::[]=}(#t39.{core::MapEntry::key}, #t39.{core::MapEntry::value});
     #t38.{core::Map::[]=}("baz", null);
   } =>#t38;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t40 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t41 in <core::List<core::int*>*>[<core::int*>[42]])
           #t40.{core::List::add}(#t41);
   } =>#t40;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t42 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t43 in <core::List<core::int*>*>[<core::int*>[42]])
           #t42.{core::Set::add}(#t43);
     #t42.{core::Set::add}(null);
   } =>#t42;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t44 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t45 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
           #t44.{core::Map::[]=}(#t45.{core::MapEntry::key}, #t45.{core::MapEntry::value});
     #t44.{core::Map::[]=}("baz", null);
   } =>#t44;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t46 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t47 in <core::List<core::int*>*>[<core::int*>[]])
         #t46.{core::List::add}(#t47);
   } =>#t46;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t48 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t49 in <core::List<core::int*>*>[<core::int*>[]])
         #t48.{core::Set::add}(#t49);
     #t48.{core::Set::add}(null);
@@ -639,173 +639,173 @@
                                  ^";
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t50 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t51 in let final core::Set<core::List<core::int*>*>* #t52 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t53 = #t52.{core::Set::add}(<core::int*>[]) in #t52)
         #t50.{core::List::add}(#t51);
   } =>#t50;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t54 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t55 in let final core::Set<core::List<core::int*>*>* #t56 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t57 = #t56.{core::Set::add}(<core::int*>[]) in #t56)
         #t54.{core::Set::add}(#t55);
     #t54.{core::Set::add}(null);
   } =>#t54;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t58 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t59 in <core::List<core::int*>*>[<core::int*>[]])
           #t58.{core::List::add}(#t59);
   } =>#t58;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t60 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t61 in <core::List<core::int*>*>[<core::int*>[]])
           #t60.{core::Set::add}(#t61);
     #t60.{core::Set::add}(null);
   } =>#t60;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t62 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t63 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t62.{core::Map::[]=}(#t63.{core::MapEntry::key}, #t63.{core::MapEntry::value});
     #t62.{core::Map::[]=}("baz", null);
   } =>#t62;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t64 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t65 in <core::int*>[])
         #t64.{core::List::add}(#t65);
   } =>#t64;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t67 in <core::int*>[])
         #t66.{core::Set::add}(#t67);
     #t66.{core::Set::add}(null);
   } =>#t66;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t68 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::int*>* #t69 in <core::String*, core::int*>{}.{core::Map::entries})
         #t68.{core::Map::[]=}(#t69.{core::MapEntry::key}, #t69.{core::MapEntry::value});
     #t68.{core::Map::[]=}("baz", null);
   } =>#t68;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t70 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t71 in let final core::Set<core::int*>* #t72 = col::LinkedHashSet::•<core::int*>() in #t72)
         #t70.{core::List::add}(#t71);
   } =>#t70;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t73 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t74 in let final core::Set<core::int*>* #t75 = col::LinkedHashSet::•<core::int*>() in #t75)
         #t73.{core::Set::add}(#t74);
     #t73.{core::Set::add}(null);
   } =>#t73;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t76 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t77 in <core::int*>[])
           #t76.{core::List::add}(#t77);
   } =>#t76;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t78 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t79 in <core::int*>[])
           #t78.{core::Set::add}(#t79);
     #t78.{core::Set::add}(null);
   } =>#t78;
   core::Map<core::String*, core::int*>* map52 = block {
     final core::Map<core::String*, core::int*>* #t80 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::int*>* #t81 in <core::String*, core::int*>{}.{core::Map::entries})
           #t80.{core::Map::[]=}(#t81.{core::MapEntry::key}, #t81.{core::MapEntry::value});
     #t80.{core::Map::[]=}("baz", null);
   } =>#t80;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t82 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t83 in <core::List<core::int*>*>[<core::int*>[]])
         #t82.{core::List::add}(#t83);
   } =>#t82;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t84 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t85 in <core::List<core::int*>*>[<core::int*>[]])
         #t84.{core::Set::add}(#t85);
     #t84.{core::Set::add}(null);
   } =>#t84;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t86 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t87 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
         #t86.{core::Map::[]=}(#t87.{core::MapEntry::key}, #t87.{core::MapEntry::value});
     #t86.{core::Map::[]=}("baz", null);
   } =>#t86;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t88 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t89 in <core::List<core::int*>*>[<core::int*>[]])
           #t88.{core::List::add}(#t89);
   } =>#t88;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t90 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t91 in <core::List<core::int*>*>[<core::int*>[]])
           #t90.{core::Set::add}(#t91);
     #t90.{core::Set::add}(null);
   } =>#t90;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t92 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t93 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t92.{core::Map::[]=}(#t93.{core::MapEntry::key}, #t93.{core::MapEntry::value});
     #t92.{core::Map::[]=}("baz", null);
   } =>#t92;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t94 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t94.{core::List::add}(<core::int*>[]);
   } =>#t94;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t95 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t95.{core::Set::add}(<core::int*>[]);
     #t95.{core::Set::add}(null);
   } =>#t95;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t96 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t96.{core::List::add}(<core::int*>[]);
   } =>#t96;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t97 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t97.{core::Set::add}(<core::int*>[]);
     #t97.{core::Set::add}(null);
   } =>#t97;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t98 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t98.{core::List::add}(42);
     else
       #t98.{core::List::add}(3.14);
   } =>#t98;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t99 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t99.{core::Set::add}(42);
     else
       #t99.{core::Set::add}(3.14);
@@ -813,7 +813,7 @@
   } =>#t99;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t100 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t100.{core::Map::[]=}("bar", 42);
     else
       #t100.{core::Map::[]=}("bar", 3.14);
@@ -821,7 +821,7 @@
   } =>#t100;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t101 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::num* #t102 in listInt)
         #t101.{core::List::add}(#t102);
     else
@@ -830,7 +830,7 @@
   } =>#t101;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t104 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::num* #t105 in listInt)
         #t104.{core::Set::add}(#t105);
     else
@@ -840,7 +840,7 @@
   } =>#t104;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t107 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::num*>* #t108 in mapToInt.{core::Map::entries})
         #t107.{core::Map::[]=}(#t108.{core::MapEntry::key}, #t108.{core::MapEntry::value});
     else
@@ -850,38 +850,38 @@
   } =>#t107;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t110 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t111 in listInt)
         #t110.{core::List::add}(#t111);
     else
-      for (final dynamic #t112 in dynVar as{TypeError} core::Iterable<dynamic>*)
+      for (final dynamic #t112 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
         #t110.{core::List::add}(#t112);
   } =>#t110;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t113 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t114 in listInt)
         #t113.{core::Set::add}(#t114);
     else
-      for (final dynamic #t115 in dynVar as{TypeError} core::Iterable<dynamic>*)
+      for (final dynamic #t115 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
         #t113.{core::Set::add}(#t115);
     #t113.{core::Set::add}(null);
   } =>#t113;
   core::Set<dynamic>* map82 = block {
     final core::Set<dynamic>* #t116 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t116.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:73:38: Error: Unexpected type 'Map<String, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   var map82 = {if (oracle(\"foo\")) ...mapToInt else ...dynVar, null};
                                      ^");
     else
-      for (final dynamic #t117 in dynVar as{TypeError} core::Iterable<dynamic>*)
+      for (final dynamic #t117 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
         #t116.{core::Set::add}(#t117);
     #t116.{core::Set::add}(null);
   } =>#t116;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t118 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t118.{core::List::add}(42);
     else
       for (final core::num* #t119 in listDouble)
@@ -889,7 +889,7 @@
   } =>#t118;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t120 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::num* #t121 in listInt)
         #t120.{core::Set::add}(#t121);
     else
@@ -898,7 +898,7 @@
   } =>#t120;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t122 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::num*>* #t123 in mapToInt.{core::Map::entries})
         #t122.{core::Map::[]=}(#t123.{core::MapEntry::key}, #t123.{core::MapEntry::value});
     else
@@ -907,33 +907,33 @@
   } =>#t122;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t124 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t124.{core::List::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t124.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t124;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t125 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t125.{core::Set::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t125.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t125.{core::Set::add}(null);
   } =>#t125;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t126 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t126.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t126.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t126.{core::Map::[]=}("baz", null);
   } =>#t126;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t127 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      for (final dynamic #t128 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      for (final dynamic #t128 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t129 = #t128 as{TypeError} core::int*;
         #t127.{core::List::add}(#t129);
       }
   } =>#t127;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t130 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      for (final dynamic #t131 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      for (final dynamic #t131 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t132 = #t131 as{TypeError} core::int*;
         #t130.{core::Set::add}(#t132);
       }
@@ -941,8 +941,8 @@
   } =>#t130;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t133 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      for (final core::MapEntry<dynamic, dynamic>* #t134 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      for (final core::MapEntry<dynamic, dynamic>* #t134 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
         final core::String* #t135 = #t134.{core::MapEntry::key} as{TypeError} core::String*;
         final core::int* #t136 = #t134.{core::MapEntry::value} as{TypeError} core::int*;
         #t133.{core::Map::[]=}(#t135, #t136);
@@ -951,31 +951,31 @@
   } =>#t133;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t137 = <core::int*>[];
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t137.{core::List::add}(42);
   } =>#t137;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t138 = col::LinkedHashSet::•<core::int*>();
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t138.{core::Set::add}(42);
   } =>#t138;
   core::Map<core::int*, core::int*>* map100 = block {
     final core::Map<core::int*, core::int*>* #t139 = <core::int*, core::int*>{};
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t139.{core::Map::[]=}(42, 42);
   } =>#t139;
 }
 static method testIfElementErrors(core::Map<core::int*, core::int*>* map) → dynamic {
   block {
     final core::List<core::int*>* #t140 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t140.{core::List::add}(let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:89:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) \"bar\"];
                            ^" in "bar" as{TypeError} core::int*);
   } =>#t140;
   block {
     final core::Set<core::int*>* #t142 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t142.{core::Set::add}(let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:90:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) \"bar\", null};
                            ^" in "bar" as{TypeError} core::int*);
@@ -983,7 +983,7 @@
   } =>#t142;
   block {
     final core::Map<core::String*, core::int*>* #t144 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t144.{core::Map::[]=}("bar", let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:91:43: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) \"bar\": \"bar\", \"baz\": null};
                                           ^" in "bar" as{TypeError} core::int*);
@@ -991,7 +991,7 @@
   } =>#t144;
   block {
     final core::List<core::int*>* #t146 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t147 in <core::int*>[let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:92:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) ...[\"bar\"]];
                                ^" in "bar" as{TypeError} core::int*])
@@ -999,7 +999,7 @@
   } =>#t146;
   block {
     final core::Set<core::int*>* #t149 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t150 in <core::int*>[let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:93:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) ...[\"bar\"], null};
                                ^" in "bar" as{TypeError} core::int*])
@@ -1008,7 +1008,7 @@
   } =>#t149;
   block {
     final core::Map<core::String*, core::int*>* #t152 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::int*>* #t153 in <core::String*, core::int*>{"bar": let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:94:47: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) ...{\"bar\": \"bar\"}, \"baz\": null};
                                               ^" in "bar" as{TypeError} core::int*}.{core::Map::entries})
@@ -1017,7 +1017,7 @@
   } =>#t152;
   block {
     final core::List<core::int*>* #t155 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t155.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:95:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map];
@@ -1025,7 +1025,7 @@
   } =>#t155;
   block {
     final core::Set<core::int*>* #t156 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t156.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:96:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map, null};
@@ -1041,7 +1041,7 @@
                                       ^": null};
   block {
     final core::List<core::String*>* #t157 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t157.{core::List::add}(let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:98:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[if (oracle(\"foo\")) 42 else 3.14];
                               ^" in 42 as{TypeError} core::String*);
@@ -1052,7 +1052,7 @@
   } =>#t157;
   block {
     final core::Set<core::String*>* #t160 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t160.{core::Set::add}(let final<BottomType> #t161 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:99:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{if (oracle(\"foo\")) 42 else 3.14, null};
                               ^" in 42 as{TypeError} core::String*);
@@ -1064,7 +1064,7 @@
   } =>#t160;
   block {
     final core::Map<core::String*, core::String*>* #t163 = <core::String*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t163.{core::Map::[]=}("bar", let final<BottomType> #t164 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:100:46: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{if (oracle(\"foo\")) \"bar\": 42 else \"baz\": 3.14, \"baz\": null};
                                              ^" in 42 as{TypeError} core::String*);
@@ -1076,7 +1076,7 @@
   } =>#t163;
   block {
     final core::List<core::int*>* #t166 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t166.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:101:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map else 42];
@@ -1086,7 +1086,7 @@
   } =>#t166;
   block {
     final core::Set<core::int*>* #t167 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t167.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:102:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1104,7 +1104,7 @@
                                       ^": null};
   block {
     final core::List<core::int*>* #t168 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t168.{core::List::add}(42);
     else
       #t168.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:104:39: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -1114,7 +1114,7 @@
   } =>#t168;
   block {
     final core::Set<core::int*>* #t169 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t169.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:105:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1171,7 +1171,7 @@
   } =>#t174;
   core::List<core::String*>* list40 = block {
     final core::List<core::String*>* #t176 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t176.{core::List::add}(let final<BottomType> #t177 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:117:53: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   List<String> list40 = <String>[if (oracle(\"foo\")) true else 42];
                                                     ^" in true as{TypeError} core::String*);
@@ -1182,7 +1182,7 @@
   } =>#t176;
   core::Set<core::String*>* set40 = block {
     final core::Set<core::String*>* #t179 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t179.{core::Set::add}(let final<BottomType> #t180 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:118:51: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Set<String> set40 = <String>{if (oracle(\"foo\")) true else 42};
                                                   ^" in true as{TypeError} core::String*);
@@ -1193,7 +1193,7 @@
   } =>#t179;
   core::Map<core::String*, core::int*>* map40 = block {
     final core::Map<core::String*, core::int*>* #t182 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t182.{core::Map::[]=}(let final<BottomType> #t183 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:119:61: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<String, int> map40 = <String, int>{if (oracle(\"foo\")) true: 42 else 42: 42};
                                                             ^" in true as{TypeError} core::String*, 42);
@@ -1204,7 +1204,7 @@
   } =>#t182;
   core::Map<core::int*, core::String*>* map41 = block {
     final core::Map<core::int*, core::String*>* #t185 = <core::int*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t185.{core::Map::[]=}(42, let final<BottomType> #t186 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:120:65: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<int, String> map41 = <int, String>{if (oracle(\"foo\")) 42: true else 42: 42};
                                                                 ^" in true as{TypeError} core::String*);
@@ -1217,380 +1217,380 @@
 static method testForElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::int* index, core::Map<core::String*, core::int*>* mapStringInt, core::Map<core::String*, core::double*>* mapStringDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t188 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t188.{core::List::add}(42);
   } =>#t188;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t189 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t189.{core::Set::add}(42);
     #t189.{core::Set::add}(null);
   } =>#t189;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t190 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t190.{core::Map::[]=}("bar", 42);
     #t190.{core::Map::[]=}("baz", null);
   } =>#t190;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t191 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t191.{core::List::add}(dynVar);
   } =>#t191;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t192 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t192.{core::Set::add}(dynVar);
     #t192.{core::Set::add}(null);
   } =>#t192;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t193 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t193.{core::Map::[]=}("bar", dynVar);
     #t193.{core::Map::[]=}("baz", null);
   } =>#t193;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t194 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t194.{core::List::add}(<core::int*>[42]);
   } =>#t194;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t195 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t195.{core::Set::add}(<core::int*>[42]);
     #t195.{core::Set::add}(null);
   } =>#t195;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t196 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t196.{core::Map::[]=}("bar", <core::int*>[42]);
     #t196.{core::Map::[]=}("baz", null);
   } =>#t196;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t197 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t198 in <core::int*>[42])
         #t197.{core::List::add}(#t198);
   } =>#t197;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t199 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t200 in <core::int*>[42])
         #t199.{core::Set::add}(#t200);
     #t199.{core::Set::add}(null);
   } =>#t199;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t201 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::int*>* #t202 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
         #t201.{core::Map::[]=}(#t202.{core::MapEntry::key}, #t202.{core::MapEntry::value});
     #t201.{core::Map::[]=}("baz", null);
   } =>#t201;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t203 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final dynamic #t204 in <dynamic>[dynVar])
         #t203.{core::List::add}(#t204);
   } =>#t203;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t205 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final dynamic #t206 in <dynamic>[dynVar])
         #t205.{core::Set::add}(#t206);
     #t205.{core::Set::add}(null);
   } =>#t205;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t207 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, dynamic>* #t208 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
         #t207.{core::Map::[]=}(#t208.{core::MapEntry::key}, #t208.{core::MapEntry::value});
     #t207.{core::Map::[]=}("baz", null);
   } =>#t207;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t209 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t210 in <core::List<core::int*>*>[<core::int*>[42]])
         #t209.{core::List::add}(#t210);
   } =>#t209;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t211 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t212 in <core::List<core::int*>*>[<core::int*>[42]])
         #t211.{core::Set::add}(#t212);
     #t211.{core::Set::add}(null);
   } =>#t211;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t213 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t214 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
         #t213.{core::Map::[]=}(#t214.{core::MapEntry::key}, #t214.{core::MapEntry::value});
     #t213.{core::Map::[]=}("baz", null);
   } =>#t213;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t215 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t216 in <core::int*>[42])
           #t215.{core::List::add}(#t216);
   } =>#t215;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t217 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t218 in <core::int*>[42])
           #t217.{core::Set::add}(#t218);
     #t217.{core::Set::add}(null);
   } =>#t217;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t219 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::int*>* #t220 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
           #t219.{core::Map::[]=}(#t220.{core::MapEntry::key}, #t220.{core::MapEntry::value});
     #t219.{core::Map::[]=}("baz", null);
   } =>#t219;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t221 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t222 in <dynamic>[dynVar])
           #t221.{core::List::add}(#t222);
   } =>#t221;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t223 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t224 in <dynamic>[dynVar])
           #t223.{core::Set::add}(#t224);
     #t223.{core::Set::add}(null);
   } =>#t223;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t225 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, dynamic>* #t226 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
           #t225.{core::Map::[]=}(#t226.{core::MapEntry::key}, #t226.{core::MapEntry::value});
     #t225.{core::Map::[]=}("baz", null);
   } =>#t225;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t227 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t228 in <core::List<core::int*>*>[<core::int*>[42]])
           #t227.{core::List::add}(#t228);
   } =>#t227;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t229 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t230 in <core::List<core::int*>*>[<core::int*>[42]])
           #t229.{core::Set::add}(#t230);
     #t229.{core::Set::add}(null);
   } =>#t229;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t231 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t232 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
           #t231.{core::Map::[]=}(#t232.{core::MapEntry::key}, #t232.{core::MapEntry::value});
     #t231.{core::Map::[]=}("baz", null);
   } =>#t231;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t233 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t234 in <core::List<core::int*>*>[<core::int*>[]])
         #t233.{core::List::add}(#t234);
   } =>#t233;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t235 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t236 in <core::List<core::int*>*>[<core::int*>[]])
         #t235.{core::Set::add}(#t236);
     #t235.{core::Set::add}(null);
   } =>#t235;
   core::Map<core::String*, core::List<core::int*>*>* map40 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t237 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t238 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
         #t237.{core::Map::[]=}(#t238.{core::MapEntry::key}, #t238.{core::MapEntry::value});
     #t237.{core::Map::[]=}("baz", null);
   } =>#t237;
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t239 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t240 in let final core::Set<core::List<core::int*>*>* #t241 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t242 = #t241.{core::Set::add}(<core::int*>[]) in #t241)
         #t239.{core::List::add}(#t240);
   } =>#t239;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t243 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t244 in let final core::Set<core::List<core::int*>*>* #t245 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t246 = #t245.{core::Set::add}(<core::int*>[]) in #t245)
         #t243.{core::Set::add}(#t244);
     #t243.{core::Set::add}(null);
   } =>#t243;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t247 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t248 in <core::List<core::int*>*>[<core::int*>[]])
           #t247.{core::List::add}(#t248);
   } =>#t247;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t249 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t250 in <core::List<core::int*>*>[<core::int*>[]])
           #t249.{core::Set::add}(#t250);
     #t249.{core::Set::add}(null);
   } =>#t249;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t251 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t252 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t251.{core::Map::[]=}(#t252.{core::MapEntry::key}, #t252.{core::MapEntry::value});
     #t251.{core::Map::[]=}("baz", null);
   } =>#t251;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t253 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t254 in <core::int*>[])
         #t253.{core::List::add}(#t254);
   } =>#t253;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t255 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t256 in <core::int*>[])
         #t255.{core::Set::add}(#t256);
     #t255.{core::Set::add}(null);
   } =>#t255;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t257 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::int*>* #t258 in <core::String*, core::int*>{}.{core::Map::entries})
         #t257.{core::Map::[]=}(#t258.{core::MapEntry::key}, #t258.{core::MapEntry::value});
     #t257.{core::Map::[]=}("baz", null);
   } =>#t257;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t259 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t260 in let final core::Set<core::int*>* #t261 = col::LinkedHashSet::•<core::int*>() in #t261)
         #t259.{core::List::add}(#t260);
   } =>#t259;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t262 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t263 in let final core::Set<core::int*>* #t264 = col::LinkedHashSet::•<core::int*>() in #t264)
         #t262.{core::Set::add}(#t263);
     #t262.{core::Set::add}(null);
   } =>#t262;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t265 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t266 in <core::int*>[])
           #t265.{core::List::add}(#t266);
   } =>#t265;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t267 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t268 in <core::int*>[])
           #t267.{core::Set::add}(#t268);
     #t267.{core::Set::add}(null);
   } =>#t267;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t269 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t270 in <core::List<core::int*>*>[<core::int*>[]])
         #t269.{core::List::add}(#t270);
   } =>#t269;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t271 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t272 in <core::List<core::int*>*>[<core::int*>[]])
         #t271.{core::Set::add}(#t272);
     #t271.{core::Set::add}(null);
   } =>#t271;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t273 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t274 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
         #t273.{core::Map::[]=}(#t274.{core::MapEntry::key}, #t274.{core::MapEntry::value});
     #t273.{core::Map::[]=}("baz", null);
   } =>#t273;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t275 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t276 in <core::List<core::int*>*>[<core::int*>[]])
           #t275.{core::List::add}(#t276);
   } =>#t275;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t277 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t278 in <core::List<core::int*>*>[<core::int*>[]])
           #t277.{core::Set::add}(#t278);
     #t277.{core::Set::add}(null);
   } =>#t277;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t279 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t280 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t279.{core::Map::[]=}(#t280.{core::MapEntry::key}, #t280.{core::MapEntry::value});
     #t279.{core::Map::[]=}("baz", null);
   } =>#t279;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t281 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t281.{core::List::add}(<core::int*>[]);
   } =>#t281;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t282 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t282.{core::Set::add}(<core::int*>[]);
     #t282.{core::Set::add}(null);
   } =>#t282;
   core::Map<core::String*, core::List<core::int*>*>* map70 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t283 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t283.{core::Map::[]=}("bar", <core::int*>[]);
     #t283.{core::Map::[]=}("baz", null);
   } =>#t283;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t284 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t284.{core::List::add}(<core::int*>[]);
   } =>#t284;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t285 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t285.{core::Set::add}(<core::int*>[]);
     #t285.{core::Set::add}(null);
   } =>#t285;
   core::Map<core::String*, core::List<core::int*>*>* map71 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t286 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t286.{core::Map::[]=}("bar", <core::int*>[]);
     #t286.{core::Map::[]=}("baz", null);
   } =>#t286;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t287 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t287.{core::List::add}(42);
       else
         #t287.{core::List::add}(3.14);
   } =>#t287;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t288 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t288.{core::Set::add}(42);
       else
         #t288.{core::Set::add}(3.14);
@@ -1598,8 +1598,8 @@
   } =>#t288;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t289 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t289.{core::Map::[]=}("bar", 42);
       else
         #t289.{core::Map::[]=}("bar", 3.14);
@@ -1607,8 +1607,8 @@
   } =>#t289;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t290 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::num* #t291 in listInt)
           #t290.{core::List::add}(#t291);
       else
@@ -1617,8 +1617,8 @@
   } =>#t290;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t293 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::num* #t294 in listInt)
           #t293.{core::Set::add}(#t294);
       else
@@ -1628,8 +1628,8 @@
   } =>#t293;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t296 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::num*>* #t297 in mapStringInt.{core::Map::entries})
           #t296.{core::Map::[]=}(#t297.{core::MapEntry::key}, #t297.{core::MapEntry::value});
       else
@@ -1639,40 +1639,40 @@
   } =>#t296;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t299 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t300 in listInt)
           #t299.{core::List::add}(#t300);
       else
-        for (final dynamic #t301 in dynVar as{TypeError} core::Iterable<dynamic>*)
+        for (final dynamic #t301 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
           #t299.{core::List::add}(#t301);
   } =>#t299;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t302 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t303 in listInt)
           #t302.{core::Set::add}(#t303);
       else
-        for (final dynamic #t304 in dynVar as{TypeError} core::Iterable<dynamic>*)
+        for (final dynamic #t304 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
           #t302.{core::Set::add}(#t304);
     #t302.{core::Set::add}(null);
   } =>#t302;
   core::Map<dynamic, dynamic>* map82 = block {
     final core::Map<dynamic, dynamic>* #t305 = <dynamic, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<dynamic, dynamic>* #t306 in mapStringInt.{core::Map::entries})
           #t305.{core::Map::[]=}(#t306.{core::MapEntry::key}, #t306.{core::MapEntry::value});
       else
-        for (final core::MapEntry<dynamic, dynamic>* #t307 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries})
+        for (final core::MapEntry<dynamic, dynamic>* #t307 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries})
           #t305.{core::Map::[]=}(#t307.{core::MapEntry::key}, #t307.{core::MapEntry::value});
     #t305.{core::Map::[]=}("baz", null);
   } =>#t305;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t308 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t308.{core::List::add}(42);
       else
         for (final core::num* #t309 in listDouble)
@@ -1680,8 +1680,8 @@
   } =>#t308;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t310 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::num* #t311 in listInt)
           #t310.{core::Set::add}(#t311);
       else
@@ -1690,8 +1690,8 @@
   } =>#t310;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t312 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::num*>* #t313 in mapStringInt.{core::Map::entries})
           #t312.{core::Map::[]=}(#t313.{core::MapEntry::key}, #t313.{core::MapEntry::value});
       else
@@ -1700,33 +1700,33 @@
   } =>#t312;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t314 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t314.{core::List::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t314.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t314;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t315 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t315.{core::Set::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t315.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t315.{core::Set::add}(null);
   } =>#t315;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t316 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t316.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t316.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t316.{core::Map::[]=}("baz", null);
   } =>#t316;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t317 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      for (final dynamic #t318 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      for (final dynamic #t318 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t319 = #t318 as{TypeError} core::int*;
         #t317.{core::List::add}(#t319);
       }
   } =>#t317;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t320 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      for (final dynamic #t321 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      for (final dynamic #t321 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t322 = #t321 as{TypeError} core::int*;
         #t320.{core::Set::add}(#t322);
       }
@@ -1734,8 +1734,8 @@
   } =>#t320;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t323 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      for (final core::MapEntry<dynamic, dynamic>* #t324 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      for (final core::MapEntry<dynamic, dynamic>* #t324 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
         final core::String* #t325 = #t324.{core::MapEntry::key} as{TypeError} core::String*;
         final core::int* #t326 = #t324.{core::MapEntry::value} as{TypeError} core::int*;
         #t323.{core::Map::[]=}(#t325, #t326);
@@ -1744,17 +1744,17 @@
   } =>#t323;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t327 = <core::int*>[];
-    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t327.{core::List::add}(42);
   } =>#t327;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t329 = col::LinkedHashSet::•<core::int*>();
-    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t329.{core::Set::add}(42);
   } =>#t329;
   core::Map<core::String*, core::int*>* map100 = block {
     final core::Map<core::String*, core::int*>* #t331 = <core::String*, core::int*>{};
-    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t331.{core::Map::[]=}("bar", 42);
   } =>#t331;
   core::List<core::int*>* list110 = block {
@@ -1776,19 +1776,19 @@
   } =>#t335;
   core::List<core::int*>* list120 = block {
     final core::List<core::int*>* #t336 = <core::int*>[];
-    for (dynamic i in dynVar as{TypeError} core::Iterable<dynamic>*)
-      #t336.{core::List::add}(i as{TypeError} core::int*);
+    for (dynamic i in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
+      #t336.{core::List::add}(i as{TypeError,ForDynamic} core::int*);
   } =>#t336;
   core::Set<core::int*>* set120 = block {
     final core::Set<core::int*>* #t337 = col::LinkedHashSet::•<core::int*>();
-    for (dynamic i in dynVar as{TypeError} core::Iterable<dynamic>*)
-      #t337.{core::Set::add}(i as{TypeError} core::int*);
+    for (dynamic i in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
+      #t337.{core::Set::add}(i as{TypeError,ForDynamic} core::int*);
     #t337.{core::Set::add}(null);
   } =>#t337;
   core::Map<core::String*, core::int*>* map120 = block {
     final core::Map<core::String*, core::int*>* #t338 = <core::String*, core::int*>{};
-    for (dynamic i in dynVar as{TypeError} core::Iterable<dynamic>*)
-      #t338.{core::Map::[]=}("bar", i as{TypeError} core::int*);
+    for (dynamic i in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
+      #t338.{core::Map::[]=}("bar", i as{TypeError,ForDynamic} core::int*);
     #t338.{core::Map::[]=}("baz", null);
   } =>#t338;
   core::List<core::int*>* list130 = block {
@@ -1810,14 +1810,14 @@
 static method testForElementErrors(core::Map<core::int*, core::int*>* map, core::List<core::int*>* list) → dynamic async {
   block {
     final core::List<core::int*>* #t342 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t342.{core::List::add}(let final<BottomType> #t343 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:212:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) \"bar\"];
                                             ^" in "bar" as{TypeError} core::int*);
   } =>#t342;
   block {
     final core::Set<core::int*>* #t344 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t344.{core::Set::add}(let final<BottomType> #t345 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:213:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\", null};
                                             ^" in "bar" as{TypeError} core::int*);
@@ -1825,7 +1825,7 @@
   } =>#t344;
   block {
     final core::Map<core::int*, core::int*>* #t346 = <core::int*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t346.{core::Map::[]=}(let final<BottomType> #t347 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:214:50: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\": \"bar\", \"baz\": null};
                                                  ^" in "bar" as{TypeError} core::int*, let final<BottomType> #t348 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:214:57: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -1837,7 +1837,7 @@
   } =>#t346;
   block {
     final core::List<core::int*>* #t350 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t351 in <core::int*>[let final<BottomType> #t352 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:215:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"]];
                                                 ^" in "bar" as{TypeError} core::int*])
@@ -1845,7 +1845,7 @@
   } =>#t350;
   block {
     final core::Set<core::int*>* #t353 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t354 in <core::int*>[let final<BottomType> #t355 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:216:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"], null};
                                                 ^" in "bar" as{TypeError} core::int*])
@@ -1854,7 +1854,7 @@
   } =>#t353;
   block {
     final core::Map<core::int*, core::int*>* #t356 = <core::int*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::int*, core::int*>* #t357 in <core::int*, core::int*>{let final<BottomType> #t358 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:217:54: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) ...{\"bar\": \"bar\"}, \"baz\": null};
                                                      ^" in "bar" as{TypeError} core::int*: let final<BottomType> #t359 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:217:61: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -1867,7 +1867,7 @@
   } =>#t356;
   block {
     final core::List<core::int*>* #t361 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t361.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:218:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...map];
@@ -1875,7 +1875,7 @@
   } =>#t361;
   block {
     final core::Set<core::int*>* #t362 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t362.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:219:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...map, null};
@@ -1891,8 +1891,8 @@
                                                     ^": null};
   block {
     final core::List<core::String*>* #t363 = <core::String*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t363.{core::List::add}(let final<BottomType> #t364 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:221:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14];
                                                              ^" in 42 as{TypeError} core::String*);
@@ -1903,8 +1903,8 @@
   } =>#t363;
   block {
     final core::Set<core::String*>* #t366 = col::LinkedHashSet::•<core::String*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t366.{core::Set::add}(let final<BottomType> #t367 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:222:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14, null};
                                                              ^" in 42 as{TypeError} core::String*);
@@ -1916,8 +1916,8 @@
   } =>#t366;
   block {
     final core::Map<core::String*, core::String*>* #t369 = <core::String*, core::String*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t369.{core::Map::[]=}("bar", let final<BottomType> #t370 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:223:77: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) \"bar\": 42 else \"bar\": 3.14, \"baz\": null};
                                                                             ^" in 42 as{TypeError} core::String*);
@@ -1929,8 +1929,8 @@
   } =>#t369;
   block {
     final core::List<core::int*>* #t372 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t372.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:224:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42];
@@ -1940,8 +1940,8 @@
   } =>#t372;
   block {
     final core::Set<core::int*>* #t373 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t373.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:225:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42, null};
@@ -1959,8 +1959,8 @@
                                                                      ^": null};
   block {
     final core::List<core::int*>* #t374 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t374.{core::List::add}(42);
       else
         #t374.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:227:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -1970,8 +1970,8 @@
   } =>#t374;
   block {
     final core::Set<core::int*>* #t375 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t375.{core::Set::add}(42);
       else
         #t375.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:228:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.strong.transformed.expect
index 2901fae..dfec04b 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.strong.transformed.expect
@@ -444,58 +444,58 @@
 static method testIfElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::Map<core::String*, core::int*>* mapToInt, core::Map<core::String*, core::double*>* mapToDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(42);
   } =>#t1;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(42);
     #t2.{core::Set::add}(null);
   } =>#t2;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t3 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}("bar", 42);
     #t3.{core::Map::[]=}("baz", null);
   } =>#t3;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t4 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t4.{core::List::add}(dynVar);
   } =>#t4;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t5 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t5.{core::Set::add}(dynVar);
     #t5.{core::Set::add}(null);
   } =>#t5;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t6 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t6.{core::Map::[]=}("bar", dynVar);
     #t6.{core::Map::[]=}("baz", null);
   } =>#t6;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t7 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t7.{core::List::add}(<core::int*>[42]);
   } =>#t7;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t8 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t8.{core::Set::add}(<core::int*>[42]);
     #t8.{core::Set::add}(null);
   } =>#t8;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t9 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t9.{core::Map::[]=}("bar", <core::int*>[42]);
     #t9.{core::Map::[]=}("baz", null);
   } =>#t9;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t10 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t11 = :sync-for-iterator.{core::Iterator::current};
@@ -505,7 +505,7 @@
   } =>#t10;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t12 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t13 = :sync-for-iterator.{core::Iterator::current};
@@ -516,7 +516,7 @@
   } =>#t12;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t14 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t15 = :sync-for-iterator.{core::Iterator::current};
@@ -527,7 +527,7 @@
   } =>#t14;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t16 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t17 = :sync-for-iterator.{core::Iterator::current};
@@ -537,7 +537,7 @@
   } =>#t16;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t18 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t19 = :sync-for-iterator.{core::Iterator::current};
@@ -548,7 +548,7 @@
   } =>#t18;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t20 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, dynamic>* #t21 = :sync-for-iterator.{core::Iterator::current};
@@ -559,7 +559,7 @@
   } =>#t20;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t22 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t23 = :sync-for-iterator.{core::Iterator::current};
@@ -569,7 +569,7 @@
   } =>#t22;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t24 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t25 = :sync-for-iterator.{core::Iterator::current};
@@ -580,7 +580,7 @@
   } =>#t24;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t26 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t27 = :sync-for-iterator.{core::Iterator::current};
@@ -591,8 +591,8 @@
   } =>#t26;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t28 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t29 = :sync-for-iterator.{core::Iterator::current};
@@ -602,8 +602,8 @@
   } =>#t28;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t30 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t31 = :sync-for-iterator.{core::Iterator::current};
@@ -614,8 +614,8 @@
   } =>#t30;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t32 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::int*>* #t33 = :sync-for-iterator.{core::Iterator::current};
@@ -626,8 +626,8 @@
   } =>#t32;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t34 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t35 = :sync-for-iterator.{core::Iterator::current};
@@ -637,8 +637,8 @@
   } =>#t34;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t36 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t37 = :sync-for-iterator.{core::Iterator::current};
@@ -649,8 +649,8 @@
   } =>#t36;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t38 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, dynamic>* #t39 = :sync-for-iterator.{core::Iterator::current};
@@ -661,8 +661,8 @@
   } =>#t38;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t40 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t41 = :sync-for-iterator.{core::Iterator::current};
@@ -672,8 +672,8 @@
   } =>#t40;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t42 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t43 = :sync-for-iterator.{core::Iterator::current};
@@ -684,8 +684,8 @@
   } =>#t42;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t44 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t45 = :sync-for-iterator.{core::Iterator::current};
@@ -696,7 +696,7 @@
   } =>#t44;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t46 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t47 = :sync-for-iterator.{core::Iterator::current};
@@ -706,7 +706,7 @@
   } =>#t46;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t48 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t49 = :sync-for-iterator.{core::Iterator::current};
@@ -720,7 +720,7 @@
                                  ^";
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t50 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t51 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t52 = #t51.{core::Set::add}(<core::int*>[]) in #t51).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t53 = :sync-for-iterator.{core::Iterator::current};
@@ -730,7 +730,7 @@
   } =>#t50;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t54 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t55 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t56 = #t55.{core::Set::add}(<core::int*>[]) in #t55).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t57 = :sync-for-iterator.{core::Iterator::current};
@@ -741,8 +741,8 @@
   } =>#t54;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t58 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t59 = :sync-for-iterator.{core::Iterator::current};
@@ -752,8 +752,8 @@
   } =>#t58;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t60 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t61 = :sync-for-iterator.{core::Iterator::current};
@@ -764,8 +764,8 @@
   } =>#t60;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t62 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t63 = :sync-for-iterator.{core::Iterator::current};
@@ -776,7 +776,7 @@
   } =>#t62;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t64 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t65 = :sync-for-iterator.{core::Iterator::current};
@@ -786,7 +786,7 @@
   } =>#t64;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t67 = :sync-for-iterator.{core::Iterator::current};
@@ -797,7 +797,7 @@
   } =>#t66;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t68 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t69 = :sync-for-iterator.{core::Iterator::current};
@@ -808,7 +808,7 @@
   } =>#t68;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t70 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t71 = col::LinkedHashSet::•<core::int*>() in #t71).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t72 = :sync-for-iterator.{core::Iterator::current};
@@ -818,7 +818,7 @@
   } =>#t70;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t73 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t74 = col::LinkedHashSet::•<core::int*>() in #t74).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t75 = :sync-for-iterator.{core::Iterator::current};
@@ -829,8 +829,8 @@
   } =>#t73;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t76 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t77 = :sync-for-iterator.{core::Iterator::current};
@@ -840,8 +840,8 @@
   } =>#t76;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t78 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t79 = :sync-for-iterator.{core::Iterator::current};
@@ -852,8 +852,8 @@
   } =>#t78;
   core::Map<core::String*, core::int*>* map52 = block {
     final core::Map<core::String*, core::int*>* #t80 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::int*>* #t81 = :sync-for-iterator.{core::Iterator::current};
@@ -864,7 +864,7 @@
   } =>#t80;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t82 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t83 = :sync-for-iterator.{core::Iterator::current};
@@ -874,7 +874,7 @@
   } =>#t82;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t84 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t85 = :sync-for-iterator.{core::Iterator::current};
@@ -885,7 +885,7 @@
   } =>#t84;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t86 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t87 = :sync-for-iterator.{core::Iterator::current};
@@ -896,8 +896,8 @@
   } =>#t86;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t88 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t89 = :sync-for-iterator.{core::Iterator::current};
@@ -907,8 +907,8 @@
   } =>#t88;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t90 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t91 = :sync-for-iterator.{core::Iterator::current};
@@ -919,8 +919,8 @@
   } =>#t90;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t92 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t93 = :sync-for-iterator.{core::Iterator::current};
@@ -931,38 +931,38 @@
   } =>#t92;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t94 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t94.{core::List::add}(<core::int*>[]);
   } =>#t94;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t95 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t95.{core::Set::add}(<core::int*>[]);
     #t95.{core::Set::add}(null);
   } =>#t95;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t96 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t96.{core::List::add}(<core::int*>[]);
   } =>#t96;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t97 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t97.{core::Set::add}(<core::int*>[]);
     #t97.{core::Set::add}(null);
   } =>#t97;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t98 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t98.{core::List::add}(42);
     else
       #t98.{core::List::add}(3.14);
   } =>#t98;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t99 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t99.{core::Set::add}(42);
     else
       #t99.{core::Set::add}(3.14);
@@ -970,7 +970,7 @@
   } =>#t99;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t100 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t100.{core::Map::[]=}("bar", 42);
     else
       #t100.{core::Map::[]=}("bar", 3.14);
@@ -978,7 +978,7 @@
   } =>#t100;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t101 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::num* #t102 = :sync-for-iterator.{core::Iterator::current};
@@ -995,7 +995,7 @@
   } =>#t101;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t104 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::num* #t105 = :sync-for-iterator.{core::Iterator::current};
@@ -1013,7 +1013,7 @@
   } =>#t104;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t107 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapToInt.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::num*>* #t108 = :sync-for-iterator.{core::Iterator::current};
@@ -1031,7 +1031,7 @@
   } =>#t107;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t110 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t111 = :sync-for-iterator.{core::Iterator::current};
@@ -1039,7 +1039,7 @@
       }
     }
     else {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t112 = :sync-for-iterator.{core::Iterator::current};
         #t110.{core::List::add}(#t112);
@@ -1048,7 +1048,7 @@
   } =>#t110;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t113 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t114 = :sync-for-iterator.{core::Iterator::current};
@@ -1056,7 +1056,7 @@
       }
     }
     else {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t115 = :sync-for-iterator.{core::Iterator::current};
         #t113.{core::Set::add}(#t115);
@@ -1066,13 +1066,13 @@
   } =>#t113;
   core::Set<dynamic>* map82 = block {
     final core::Set<dynamic>* #t116 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t116.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:73:38: Error: Unexpected type 'Map<String, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   var map82 = {if (oracle(\"foo\")) ...mapToInt else ...dynVar, null};
                                      ^");
     else {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t117 = :sync-for-iterator.{core::Iterator::current};
         #t116.{core::Set::add}(#t117);
@@ -1082,7 +1082,7 @@
   } =>#t116;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t118 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t118.{core::List::add}(42);
     else {
       core::Iterator<core::double*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::double*>*>(listDouble).{core::Iterable::iterator};
@@ -1094,7 +1094,7 @@
   } =>#t118;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t120 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::num* #t121 = :sync-for-iterator.{core::Iterator::current};
@@ -1107,7 +1107,7 @@
   } =>#t120;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t122 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapToInt.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::num*>* #t123 = :sync-for-iterator.{core::Iterator::current};
@@ -1120,25 +1120,25 @@
   } =>#t122;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t124 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t124.{core::List::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t124.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t124;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t125 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t125.{core::Set::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t125.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t125.{core::Set::add}(null);
   } =>#t125;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t126 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t126.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t126.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t126.{core::Map::[]=}("baz", null);
   } =>#t126;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t127 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t128 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -1150,8 +1150,8 @@
   } =>#t127;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t130 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t131 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -1164,8 +1164,8 @@
   } =>#t130;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t133 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t134 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -1179,31 +1179,31 @@
   } =>#t133;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t137 = <core::int*>[];
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t137.{core::List::add}(42);
   } =>#t137;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t138 = col::LinkedHashSet::•<core::int*>();
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t138.{core::Set::add}(42);
   } =>#t138;
   core::Map<core::int*, core::int*>* map100 = block {
     final core::Map<core::int*, core::int*>* #t139 = <core::int*, core::int*>{};
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t139.{core::Map::[]=}(42, 42);
   } =>#t139;
 }
 static method testIfElementErrors(core::Map<core::int*, core::int*>* map) → dynamic {
   block {
     final core::List<core::int*>* #t140 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t140.{core::List::add}(let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:89:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) \"bar\"];
                            ^" in "bar" as{TypeError} core::int*);
   } =>#t140;
   block {
     final core::Set<core::int*>* #t142 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t142.{core::Set::add}(let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:90:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) \"bar\", null};
                            ^" in "bar" as{TypeError} core::int*);
@@ -1211,7 +1211,7 @@
   } =>#t142;
   block {
     final core::Map<core::String*, core::int*>* #t144 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t144.{core::Map::[]=}("bar", let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:91:43: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) \"bar\": \"bar\", \"baz\": null};
                                           ^" in "bar" as{TypeError} core::int*);
@@ -1219,7 +1219,7 @@
   } =>#t144;
   block {
     final core::List<core::int*>* #t146 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:92:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) ...[\"bar\"]];
                                ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -1231,7 +1231,7 @@
   } =>#t146;
   block {
     final core::Set<core::int*>* #t149 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:93:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) ...[\"bar\"], null};
                                ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -1244,7 +1244,7 @@
   } =>#t149;
   block {
     final core::Map<core::String*, core::int*>* #t152 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:94:47: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) ...{\"bar\": \"bar\"}, \"baz\": null};
                                               ^" in "bar" as{TypeError} core::int*}.{core::Map::entries}).{core::Iterable::iterator};
@@ -1257,7 +1257,7 @@
   } =>#t152;
   block {
     final core::List<core::int*>* #t155 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t155.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:95:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map];
@@ -1265,7 +1265,7 @@
   } =>#t155;
   block {
     final core::Set<core::int*>* #t156 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t156.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:96:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map, null};
@@ -1281,7 +1281,7 @@
                                       ^": null};
   block {
     final core::List<core::String*>* #t157 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t157.{core::List::add}(let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:98:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[if (oracle(\"foo\")) 42 else 3.14];
                               ^" in 42 as{TypeError} core::String*);
@@ -1292,7 +1292,7 @@
   } =>#t157;
   block {
     final core::Set<core::String*>* #t160 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t160.{core::Set::add}(let final<BottomType> #t161 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:99:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{if (oracle(\"foo\")) 42 else 3.14, null};
                               ^" in 42 as{TypeError} core::String*);
@@ -1304,7 +1304,7 @@
   } =>#t160;
   block {
     final core::Map<core::String*, core::String*>* #t163 = <core::String*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t163.{core::Map::[]=}("bar", let final<BottomType> #t164 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:100:46: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{if (oracle(\"foo\")) \"bar\": 42 else \"baz\": 3.14, \"baz\": null};
                                              ^" in 42 as{TypeError} core::String*);
@@ -1316,7 +1316,7 @@
   } =>#t163;
   block {
     final core::List<core::int*>* #t166 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t166.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:101:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map else 42];
@@ -1326,7 +1326,7 @@
   } =>#t166;
   block {
     final core::Set<core::int*>* #t167 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t167.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:102:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1344,7 +1344,7 @@
                                       ^": null};
   block {
     final core::List<core::int*>* #t168 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t168.{core::List::add}(42);
     else
       #t168.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:104:39: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -1354,7 +1354,7 @@
   } =>#t168;
   block {
     final core::Set<core::int*>* #t169 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t169.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:105:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1411,7 +1411,7 @@
   } =>#t174;
   core::List<core::String*>* list40 = block {
     final core::List<core::String*>* #t176 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t176.{core::List::add}(let final<BottomType> #t177 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:117:53: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   List<String> list40 = <String>[if (oracle(\"foo\")) true else 42];
                                                     ^" in true as{TypeError} core::String*);
@@ -1422,7 +1422,7 @@
   } =>#t176;
   core::Set<core::String*>* set40 = block {
     final core::Set<core::String*>* #t179 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t179.{core::Set::add}(let final<BottomType> #t180 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:118:51: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Set<String> set40 = <String>{if (oracle(\"foo\")) true else 42};
                                                   ^" in true as{TypeError} core::String*);
@@ -1433,7 +1433,7 @@
   } =>#t179;
   core::Map<core::String*, core::int*>* map40 = block {
     final core::Map<core::String*, core::int*>* #t182 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t182.{core::Map::[]=}(let final<BottomType> #t183 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:119:61: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<String, int> map40 = <String, int>{if (oracle(\"foo\")) true: 42 else 42: 42};
                                                             ^" in true as{TypeError} core::String*, 42);
@@ -1444,7 +1444,7 @@
   } =>#t182;
   core::Map<core::int*, core::String*>* map41 = block {
     final core::Map<core::int*, core::String*>* #t185 = <core::int*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t185.{core::Map::[]=}(42, let final<BottomType> #t186 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:120:65: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<int, String> map41 = <int, String>{if (oracle(\"foo\")) 42: true else 42: 42};
                                                                 ^" in true as{TypeError} core::String*);
@@ -1457,58 +1457,58 @@
 static method testForElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::int* index, core::Map<core::String*, core::int*>* mapStringInt, core::Map<core::String*, core::double*>* mapStringDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t188 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t188.{core::List::add}(42);
   } =>#t188;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t189 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t189.{core::Set::add}(42);
     #t189.{core::Set::add}(null);
   } =>#t189;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t190 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t190.{core::Map::[]=}("bar", 42);
     #t190.{core::Map::[]=}("baz", null);
   } =>#t190;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t191 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t191.{core::List::add}(dynVar);
   } =>#t191;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t192 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t192.{core::Set::add}(dynVar);
     #t192.{core::Set::add}(null);
   } =>#t192;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t193 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t193.{core::Map::[]=}("bar", dynVar);
     #t193.{core::Map::[]=}("baz", null);
   } =>#t193;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t194 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t194.{core::List::add}(<core::int*>[42]);
   } =>#t194;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t195 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t195.{core::Set::add}(<core::int*>[42]);
     #t195.{core::Set::add}(null);
   } =>#t195;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t196 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t196.{core::Map::[]=}("bar", <core::int*>[42]);
     #t196.{core::Map::[]=}("baz", null);
   } =>#t196;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t197 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t198 = :sync-for-iterator.{core::Iterator::current};
@@ -1518,7 +1518,7 @@
   } =>#t197;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t199 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t200 = :sync-for-iterator.{core::Iterator::current};
@@ -1529,7 +1529,7 @@
   } =>#t199;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t201 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t202 = :sync-for-iterator.{core::Iterator::current};
@@ -1540,7 +1540,7 @@
   } =>#t201;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t203 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t204 = :sync-for-iterator.{core::Iterator::current};
@@ -1550,7 +1550,7 @@
   } =>#t203;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t205 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t206 = :sync-for-iterator.{core::Iterator::current};
@@ -1561,7 +1561,7 @@
   } =>#t205;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t207 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, dynamic>* #t208 = :sync-for-iterator.{core::Iterator::current};
@@ -1572,7 +1572,7 @@
   } =>#t207;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t209 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t210 = :sync-for-iterator.{core::Iterator::current};
@@ -1582,7 +1582,7 @@
   } =>#t209;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t211 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t212 = :sync-for-iterator.{core::Iterator::current};
@@ -1593,7 +1593,7 @@
   } =>#t211;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t213 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t214 = :sync-for-iterator.{core::Iterator::current};
@@ -1604,8 +1604,8 @@
   } =>#t213;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t215 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t216 = :sync-for-iterator.{core::Iterator::current};
@@ -1615,8 +1615,8 @@
   } =>#t215;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t217 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t218 = :sync-for-iterator.{core::Iterator::current};
@@ -1627,8 +1627,8 @@
   } =>#t217;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t219 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::int*>* #t220 = :sync-for-iterator.{core::Iterator::current};
@@ -1639,8 +1639,8 @@
   } =>#t219;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t221 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t222 = :sync-for-iterator.{core::Iterator::current};
@@ -1650,8 +1650,8 @@
   } =>#t221;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t223 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t224 = :sync-for-iterator.{core::Iterator::current};
@@ -1662,8 +1662,8 @@
   } =>#t223;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t225 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, dynamic>* #t226 = :sync-for-iterator.{core::Iterator::current};
@@ -1674,8 +1674,8 @@
   } =>#t225;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t227 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t228 = :sync-for-iterator.{core::Iterator::current};
@@ -1685,8 +1685,8 @@
   } =>#t227;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t229 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t230 = :sync-for-iterator.{core::Iterator::current};
@@ -1697,8 +1697,8 @@
   } =>#t229;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t231 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t232 = :sync-for-iterator.{core::Iterator::current};
@@ -1709,7 +1709,7 @@
   } =>#t231;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t233 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t234 = :sync-for-iterator.{core::Iterator::current};
@@ -1719,7 +1719,7 @@
   } =>#t233;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t235 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t236 = :sync-for-iterator.{core::Iterator::current};
@@ -1730,7 +1730,7 @@
   } =>#t235;
   core::Map<core::String*, core::List<core::int*>*>* map40 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t237 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t238 = :sync-for-iterator.{core::Iterator::current};
@@ -1741,7 +1741,7 @@
   } =>#t237;
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t239 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t240 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t241 = #t240.{core::Set::add}(<core::int*>[]) in #t240).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t242 = :sync-for-iterator.{core::Iterator::current};
@@ -1751,7 +1751,7 @@
   } =>#t239;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t243 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t244 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t245 = #t244.{core::Set::add}(<core::int*>[]) in #t244).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t246 = :sync-for-iterator.{core::Iterator::current};
@@ -1762,8 +1762,8 @@
   } =>#t243;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t247 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t248 = :sync-for-iterator.{core::Iterator::current};
@@ -1773,8 +1773,8 @@
   } =>#t247;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t249 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t250 = :sync-for-iterator.{core::Iterator::current};
@@ -1785,8 +1785,8 @@
   } =>#t249;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t251 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t252 = :sync-for-iterator.{core::Iterator::current};
@@ -1797,7 +1797,7 @@
   } =>#t251;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t253 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t254 = :sync-for-iterator.{core::Iterator::current};
@@ -1807,7 +1807,7 @@
   } =>#t253;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t255 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t256 = :sync-for-iterator.{core::Iterator::current};
@@ -1818,7 +1818,7 @@
   } =>#t255;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t257 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t258 = :sync-for-iterator.{core::Iterator::current};
@@ -1829,7 +1829,7 @@
   } =>#t257;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t259 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t260 = col::LinkedHashSet::•<core::int*>() in #t260).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t261 = :sync-for-iterator.{core::Iterator::current};
@@ -1839,7 +1839,7 @@
   } =>#t259;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t262 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t263 = col::LinkedHashSet::•<core::int*>() in #t263).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t264 = :sync-for-iterator.{core::Iterator::current};
@@ -1850,8 +1850,8 @@
   } =>#t262;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t265 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t266 = :sync-for-iterator.{core::Iterator::current};
@@ -1861,8 +1861,8 @@
   } =>#t265;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t267 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t268 = :sync-for-iterator.{core::Iterator::current};
@@ -1873,7 +1873,7 @@
   } =>#t267;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t269 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t270 = :sync-for-iterator.{core::Iterator::current};
@@ -1883,7 +1883,7 @@
   } =>#t269;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t271 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t272 = :sync-for-iterator.{core::Iterator::current};
@@ -1894,7 +1894,7 @@
   } =>#t271;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t273 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t274 = :sync-for-iterator.{core::Iterator::current};
@@ -1905,8 +1905,8 @@
   } =>#t273;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t275 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t276 = :sync-for-iterator.{core::Iterator::current};
@@ -1916,8 +1916,8 @@
   } =>#t275;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t277 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t278 = :sync-for-iterator.{core::Iterator::current};
@@ -1928,8 +1928,8 @@
   } =>#t277;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t279 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t280 = :sync-for-iterator.{core::Iterator::current};
@@ -1940,53 +1940,53 @@
   } =>#t279;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t281 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t281.{core::List::add}(<core::int*>[]);
   } =>#t281;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t282 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t282.{core::Set::add}(<core::int*>[]);
     #t282.{core::Set::add}(null);
   } =>#t282;
   core::Map<core::String*, core::List<core::int*>*>* map70 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t283 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t283.{core::Map::[]=}("bar", <core::int*>[]);
     #t283.{core::Map::[]=}("baz", null);
   } =>#t283;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t284 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t284.{core::List::add}(<core::int*>[]);
   } =>#t284;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t285 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t285.{core::Set::add}(<core::int*>[]);
     #t285.{core::Set::add}(null);
   } =>#t285;
   core::Map<core::String*, core::List<core::int*>*>* map71 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t286 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t286.{core::Map::[]=}("bar", <core::int*>[]);
     #t286.{core::Map::[]=}("baz", null);
   } =>#t286;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t287 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t287.{core::List::add}(42);
       else
         #t287.{core::List::add}(3.14);
   } =>#t287;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t288 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t288.{core::Set::add}(42);
       else
         #t288.{core::Set::add}(3.14);
@@ -1994,8 +1994,8 @@
   } =>#t288;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t289 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t289.{core::Map::[]=}("bar", 42);
       else
         #t289.{core::Map::[]=}("bar", 3.14);
@@ -2003,8 +2003,8 @@
   } =>#t289;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t290 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::num* #t291 = :sync-for-iterator.{core::Iterator::current};
@@ -2021,8 +2021,8 @@
   } =>#t290;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t293 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::num* #t294 = :sync-for-iterator.{core::Iterator::current};
@@ -2040,8 +2040,8 @@
   } =>#t293;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t296 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapStringInt.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::num*>* #t297 = :sync-for-iterator.{core::Iterator::current};
@@ -2059,8 +2059,8 @@
   } =>#t296;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t299 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t300 = :sync-for-iterator.{core::Iterator::current};
@@ -2068,7 +2068,7 @@
         }
       }
       else {
-        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t301 = :sync-for-iterator.{core::Iterator::current};
           #t299.{core::List::add}(#t301);
@@ -2077,8 +2077,8 @@
   } =>#t299;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t302 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t303 = :sync-for-iterator.{core::Iterator::current};
@@ -2086,7 +2086,7 @@
         }
       }
       else {
-        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t304 = :sync-for-iterator.{core::Iterator::current};
           #t302.{core::Set::add}(#t304);
@@ -2096,8 +2096,8 @@
   } =>#t302;
   core::Map<dynamic, dynamic>* map82 = block {
     final core::Map<dynamic, dynamic>* #t305 = <dynamic, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapStringInt.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<dynamic, dynamic>* #t306 = :sync-for-iterator.{core::Iterator::current};
@@ -2105,7 +2105,7 @@
         }
       }
       else {
-        core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+        core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<dynamic, dynamic>* #t307 = :sync-for-iterator.{core::Iterator::current};
           #t305.{core::Map::[]=}(#t307.{core::MapEntry::key}, #t307.{core::MapEntry::value});
@@ -2115,8 +2115,8 @@
   } =>#t305;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t308 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t308.{core::List::add}(42);
       else {
         core::Iterator<core::double*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::double*>*>(listDouble).{core::Iterable::iterator};
@@ -2128,8 +2128,8 @@
   } =>#t308;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t310 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::num* #t311 = :sync-for-iterator.{core::Iterator::current};
@@ -2142,8 +2142,8 @@
   } =>#t310;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t312 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapStringInt.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::num*>* #t313 = :sync-for-iterator.{core::Iterator::current};
@@ -2156,25 +2156,25 @@
   } =>#t312;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t314 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t314.{core::List::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t314.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t314;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t315 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t315.{core::Set::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t315.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t315.{core::Set::add}(null);
   } =>#t315;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t316 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t316.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t316.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t316.{core::Map::[]=}("baz", null);
   } =>#t316;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t317 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t318 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -2186,8 +2186,8 @@
   } =>#t317;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t320 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t321 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -2200,8 +2200,8 @@
   } =>#t320;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t323 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t324 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -2215,17 +2215,17 @@
   } =>#t323;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t327 = <core::int*>[];
-    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t327.{core::List::add}(42);
   } =>#t327;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t329 = col::LinkedHashSet::•<core::int*>();
-    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t329.{core::Set::add}(42);
   } =>#t329;
   core::Map<core::String*, core::int*>* map100 = block {
     final core::Map<core::String*, core::int*>* #t331 = <core::String*, core::int*>{};
-    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t331.{core::Map::[]=}("bar", 42);
   } =>#t331;
   core::List<core::int*>* list110 = block {
@@ -2263,20 +2263,20 @@
   core::List<core::int*>* list120 = block {
     final core::List<core::int*>* #t336 = <core::int*>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         dynamic i = :sync-for-iterator.{core::Iterator::current};
-        #t336.{core::List::add}(i as{TypeError} core::int*);
+        #t336.{core::List::add}(i as{TypeError,ForDynamic} core::int*);
       }
     }
   } =>#t336;
   core::Set<core::int*>* set120 = block {
     final core::Set<core::int*>* #t337 = col::LinkedHashSet::•<core::int*>();
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         dynamic i = :sync-for-iterator.{core::Iterator::current};
-        #t337.{core::Set::add}(i as{TypeError} core::int*);
+        #t337.{core::Set::add}(i as{TypeError,ForDynamic} core::int*);
       }
     }
     #t337.{core::Set::add}(null);
@@ -2284,10 +2284,10 @@
   core::Map<core::String*, core::int*>* map120 = block {
     final core::Map<core::String*, core::int*>* #t338 = <core::String*, core::int*>{};
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         dynamic i = :sync-for-iterator.{core::Iterator::current};
-        #t338.{core::Map::[]=}("bar", i as{TypeError} core::int*);
+        #t338.{core::Map::[]=}("bar", i as{TypeError,ForDynamic} core::int*);
       }
     }
     #t338.{core::Map::[]=}("baz", null);
@@ -2326,14 +2326,14 @@
       {
         block {
           final core::List<core::int*>* #t342 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t342.{core::List::add}(let final<BottomType> #t343 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:212:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) \"bar\"];
                                             ^" in "bar" as{TypeError} core::int*);
         } =>#t342;
         block {
           final core::Set<core::int*>* #t344 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t344.{core::Set::add}(let final<BottomType> #t345 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:213:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\", null};
                                             ^" in "bar" as{TypeError} core::int*);
@@ -2341,7 +2341,7 @@
         } =>#t344;
         block {
           final core::Map<core::int*, core::int*>* #t346 = <core::int*, core::int*>{};
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t346.{core::Map::[]=}(let final<BottomType> #t347 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:214:50: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\": \"bar\", \"baz\": null};
                                                  ^" in "bar" as{TypeError} core::int*, let final<BottomType> #t348 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:214:57: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -2353,7 +2353,7 @@
         } =>#t346;
         block {
           final core::List<core::int*>* #t350 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
             core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t351 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:215:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"]];
                                                 ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -2365,7 +2365,7 @@
         } =>#t350;
         block {
           final core::Set<core::int*>* #t353 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
             core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t354 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:216:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"], null};
                                                 ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -2378,7 +2378,7 @@
         } =>#t353;
         block {
           final core::Map<core::int*, core::int*>* #t356 = <core::int*, core::int*>{};
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
             core::Iterator<core::MapEntry<core::int*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::int*, core::int*>*>*>(<core::int*, core::int*>{let final<BottomType> #t357 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:217:54: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) ...{\"bar\": \"bar\"}, \"baz\": null};
                                                      ^" in "bar" as{TypeError} core::int*: let final<BottomType> #t358 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:217:61: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -2395,7 +2395,7 @@
         } =>#t356;
         block {
           final core::List<core::int*>* #t361 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t361.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:218:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...map];
@@ -2403,7 +2403,7 @@
         } =>#t361;
         block {
           final core::Set<core::int*>* #t362 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t362.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:219:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...map, null};
@@ -2419,8 +2419,8 @@
                                                     ^": null};
         block {
           final core::List<core::String*>* #t363 = <core::String*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t363.{core::List::add}(let final<BottomType> #t364 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:221:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14];
                                                              ^" in 42 as{TypeError} core::String*);
@@ -2431,8 +2431,8 @@
         } =>#t363;
         block {
           final core::Set<core::String*>* #t366 = col::LinkedHashSet::•<core::String*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t366.{core::Set::add}(let final<BottomType> #t367 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:222:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14, null};
                                                              ^" in 42 as{TypeError} core::String*);
@@ -2444,8 +2444,8 @@
         } =>#t366;
         block {
           final core::Map<core::String*, core::String*>* #t369 = <core::String*, core::String*>{};
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t369.{core::Map::[]=}("bar", let final<BottomType> #t370 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:223:77: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) \"bar\": 42 else \"bar\": 3.14, \"baz\": null};
                                                                             ^" in 42 as{TypeError} core::String*);
@@ -2457,8 +2457,8 @@
         } =>#t369;
         block {
           final core::List<core::int*>* #t372 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t372.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:224:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42];
@@ -2468,8 +2468,8 @@
         } =>#t372;
         block {
           final core::Set<core::int*>* #t373 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t373.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:225:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42, null};
@@ -2487,8 +2487,8 @@
                                                                      ^": null};
         block {
           final core::List<core::int*>* #t374 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t374.{core::List::add}(42);
             else
               #t374.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:227:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -2498,8 +2498,8 @@
         } =>#t374;
         block {
           final core::Set<core::int*>* #t375 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t375.{core::Set::add}(42);
             else
               #t375.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:228:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.weak.expect
index 384c9be..2c46fb9 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.weak.expect
@@ -443,193 +443,193 @@
 static method testIfElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::Map<core::String*, core::int*>* mapToInt, core::Map<core::String*, core::double*>* mapToDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(42);
   } =>#t1;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(42);
     #t2.{core::Set::add}(null);
   } =>#t2;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t3 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}("bar", 42);
     #t3.{core::Map::[]=}("baz", null);
   } =>#t3;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t4 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t4.{core::List::add}(dynVar);
   } =>#t4;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t5 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t5.{core::Set::add}(dynVar);
     #t5.{core::Set::add}(null);
   } =>#t5;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t6 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t6.{core::Map::[]=}("bar", dynVar);
     #t6.{core::Map::[]=}("baz", null);
   } =>#t6;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t7 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t7.{core::List::add}(<core::int*>[42]);
   } =>#t7;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t8 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t8.{core::Set::add}(<core::int*>[42]);
     #t8.{core::Set::add}(null);
   } =>#t8;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t9 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t9.{core::Map::[]=}("bar", <core::int*>[42]);
     #t9.{core::Map::[]=}("baz", null);
   } =>#t9;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t10 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t11 in <core::int*>[42])
         #t10.{core::List::add}(#t11);
   } =>#t10;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t12 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t13 in <core::int*>[42])
         #t12.{core::Set::add}(#t13);
     #t12.{core::Set::add}(null);
   } =>#t12;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t14 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::int*>* #t15 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
         #t14.{core::Map::[]=}(#t15.{core::MapEntry::key}, #t15.{core::MapEntry::value});
     #t14.{core::Map::[]=}("baz", null);
   } =>#t14;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t16 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t17 in <dynamic>[dynVar])
         #t16.{core::List::add}(#t17);
   } =>#t16;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t18 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t19 in <dynamic>[dynVar])
         #t18.{core::Set::add}(#t19);
     #t18.{core::Set::add}(null);
   } =>#t18;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t20 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, dynamic>* #t21 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
         #t20.{core::Map::[]=}(#t21.{core::MapEntry::key}, #t21.{core::MapEntry::value});
     #t20.{core::Map::[]=}("baz", null);
   } =>#t20;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t22 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t23 in <core::List<core::int*>*>[<core::int*>[42]])
         #t22.{core::List::add}(#t23);
   } =>#t22;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t24 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t25 in <core::List<core::int*>*>[<core::int*>[42]])
         #t24.{core::Set::add}(#t25);
     #t24.{core::Set::add}(null);
   } =>#t24;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t26 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t27 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
         #t26.{core::Map::[]=}(#t27.{core::MapEntry::key}, #t27.{core::MapEntry::value});
     #t26.{core::Map::[]=}("baz", null);
   } =>#t26;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t28 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t29 in <core::int*>[42])
           #t28.{core::List::add}(#t29);
   } =>#t28;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t30 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t31 in <core::int*>[42])
           #t30.{core::Set::add}(#t31);
     #t30.{core::Set::add}(null);
   } =>#t30;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t32 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::int*>* #t33 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
           #t32.{core::Map::[]=}(#t33.{core::MapEntry::key}, #t33.{core::MapEntry::value});
     #t32.{core::Map::[]=}("baz", null);
   } =>#t32;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t34 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t35 in <dynamic>[dynVar])
           #t34.{core::List::add}(#t35);
   } =>#t34;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t36 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t37 in <dynamic>[dynVar])
           #t36.{core::Set::add}(#t37);
     #t36.{core::Set::add}(null);
   } =>#t36;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t38 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, dynamic>* #t39 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
           #t38.{core::Map::[]=}(#t39.{core::MapEntry::key}, #t39.{core::MapEntry::value});
     #t38.{core::Map::[]=}("baz", null);
   } =>#t38;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t40 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t41 in <core::List<core::int*>*>[<core::int*>[42]])
           #t40.{core::List::add}(#t41);
   } =>#t40;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t42 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t43 in <core::List<core::int*>*>[<core::int*>[42]])
           #t42.{core::Set::add}(#t43);
     #t42.{core::Set::add}(null);
   } =>#t42;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t44 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t45 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
           #t44.{core::Map::[]=}(#t45.{core::MapEntry::key}, #t45.{core::MapEntry::value});
     #t44.{core::Map::[]=}("baz", null);
   } =>#t44;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t46 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t47 in <core::List<core::int*>*>[<core::int*>[]])
         #t46.{core::List::add}(#t47);
   } =>#t46;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t48 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t49 in <core::List<core::int*>*>[<core::int*>[]])
         #t48.{core::Set::add}(#t49);
     #t48.{core::Set::add}(null);
@@ -639,173 +639,173 @@
                                  ^";
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t50 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t51 in let final core::Set<core::List<core::int*>*>* #t52 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t53 = #t52.{core::Set::add}(<core::int*>[]) in #t52)
         #t50.{core::List::add}(#t51);
   } =>#t50;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t54 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t55 in let final core::Set<core::List<core::int*>*>* #t56 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t57 = #t56.{core::Set::add}(<core::int*>[]) in #t56)
         #t54.{core::Set::add}(#t55);
     #t54.{core::Set::add}(null);
   } =>#t54;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t58 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t59 in <core::List<core::int*>*>[<core::int*>[]])
           #t58.{core::List::add}(#t59);
   } =>#t58;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t60 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t61 in <core::List<core::int*>*>[<core::int*>[]])
           #t60.{core::Set::add}(#t61);
     #t60.{core::Set::add}(null);
   } =>#t60;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t62 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t63 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t62.{core::Map::[]=}(#t63.{core::MapEntry::key}, #t63.{core::MapEntry::value});
     #t62.{core::Map::[]=}("baz", null);
   } =>#t62;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t64 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t65 in <core::int*>[])
         #t64.{core::List::add}(#t65);
   } =>#t64;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t67 in <core::int*>[])
         #t66.{core::Set::add}(#t67);
     #t66.{core::Set::add}(null);
   } =>#t66;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t68 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::int*>* #t69 in <core::String*, core::int*>{}.{core::Map::entries})
         #t68.{core::Map::[]=}(#t69.{core::MapEntry::key}, #t69.{core::MapEntry::value});
     #t68.{core::Map::[]=}("baz", null);
   } =>#t68;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t70 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t71 in let final core::Set<core::int*>* #t72 = col::LinkedHashSet::•<core::int*>() in #t72)
         #t70.{core::List::add}(#t71);
   } =>#t70;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t73 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t74 in let final core::Set<core::int*>* #t75 = col::LinkedHashSet::•<core::int*>() in #t75)
         #t73.{core::Set::add}(#t74);
     #t73.{core::Set::add}(null);
   } =>#t73;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t76 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t77 in <core::int*>[])
           #t76.{core::List::add}(#t77);
   } =>#t76;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t78 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t79 in <core::int*>[])
           #t78.{core::Set::add}(#t79);
     #t78.{core::Set::add}(null);
   } =>#t78;
   core::Map<core::String*, core::int*>* map52 = block {
     final core::Map<core::String*, core::int*>* #t80 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::int*>* #t81 in <core::String*, core::int*>{}.{core::Map::entries})
           #t80.{core::Map::[]=}(#t81.{core::MapEntry::key}, #t81.{core::MapEntry::value});
     #t80.{core::Map::[]=}("baz", null);
   } =>#t80;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t82 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t83 in <core::List<core::int*>*>[<core::int*>[]])
         #t82.{core::List::add}(#t83);
   } =>#t82;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t84 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::List<core::int*>* #t85 in <core::List<core::int*>*>[<core::int*>[]])
         #t84.{core::Set::add}(#t85);
     #t84.{core::Set::add}(null);
   } =>#t84;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t86 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t87 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
         #t86.{core::Map::[]=}(#t87.{core::MapEntry::key}, #t87.{core::MapEntry::value});
     #t86.{core::Map::[]=}("baz", null);
   } =>#t86;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t88 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t89 in <core::List<core::int*>*>[<core::int*>[]])
           #t88.{core::List::add}(#t89);
   } =>#t88;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t90 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t91 in <core::List<core::int*>*>[<core::int*>[]])
           #t90.{core::Set::add}(#t91);
     #t90.{core::Set::add}(null);
   } =>#t90;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t92 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t93 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t92.{core::Map::[]=}(#t93.{core::MapEntry::key}, #t93.{core::MapEntry::value});
     #t92.{core::Map::[]=}("baz", null);
   } =>#t92;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t94 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t94.{core::List::add}(<core::int*>[]);
   } =>#t94;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t95 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t95.{core::Set::add}(<core::int*>[]);
     #t95.{core::Set::add}(null);
   } =>#t95;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t96 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t96.{core::List::add}(<core::int*>[]);
   } =>#t96;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t97 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t97.{core::Set::add}(<core::int*>[]);
     #t97.{core::Set::add}(null);
   } =>#t97;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t98 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t98.{core::List::add}(42);
     else
       #t98.{core::List::add}(3.14);
   } =>#t98;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t99 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t99.{core::Set::add}(42);
     else
       #t99.{core::Set::add}(3.14);
@@ -813,7 +813,7 @@
   } =>#t99;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t100 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t100.{core::Map::[]=}("bar", 42);
     else
       #t100.{core::Map::[]=}("bar", 3.14);
@@ -821,7 +821,7 @@
   } =>#t100;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t101 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::num* #t102 in listInt)
         #t101.{core::List::add}(#t102);
     else
@@ -830,7 +830,7 @@
   } =>#t101;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t104 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::num* #t105 in listInt)
         #t104.{core::Set::add}(#t105);
     else
@@ -840,7 +840,7 @@
   } =>#t104;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t107 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::num*>* #t108 in mapToInt.{core::Map::entries})
         #t107.{core::Map::[]=}(#t108.{core::MapEntry::key}, #t108.{core::MapEntry::value});
     else
@@ -850,38 +850,38 @@
   } =>#t107;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t110 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t111 in listInt)
         #t110.{core::List::add}(#t111);
     else
-      for (final dynamic #t112 in dynVar as{TypeError} core::Iterable<dynamic>*)
+      for (final dynamic #t112 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
         #t110.{core::List::add}(#t112);
   } =>#t110;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t113 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final dynamic #t114 in listInt)
         #t113.{core::Set::add}(#t114);
     else
-      for (final dynamic #t115 in dynVar as{TypeError} core::Iterable<dynamic>*)
+      for (final dynamic #t115 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
         #t113.{core::Set::add}(#t115);
     #t113.{core::Set::add}(null);
   } =>#t113;
   core::Set<dynamic>* map82 = block {
     final core::Set<dynamic>* #t116 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t116.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:73:38: Error: Unexpected type 'Map<String, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   var map82 = {if (oracle(\"foo\")) ...mapToInt else ...dynVar, null};
                                      ^");
     else
-      for (final dynamic #t117 in dynVar as{TypeError} core::Iterable<dynamic>*)
+      for (final dynamic #t117 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
         #t116.{core::Set::add}(#t117);
     #t116.{core::Set::add}(null);
   } =>#t116;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t118 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t118.{core::List::add}(42);
     else
       for (final core::num* #t119 in listDouble)
@@ -889,7 +889,7 @@
   } =>#t118;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t120 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::num* #t121 in listInt)
         #t120.{core::Set::add}(#t121);
     else
@@ -898,7 +898,7 @@
   } =>#t120;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t122 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::num*>* #t123 in mapToInt.{core::Map::entries})
         #t122.{core::Map::[]=}(#t123.{core::MapEntry::key}, #t123.{core::MapEntry::value});
     else
@@ -907,33 +907,33 @@
   } =>#t122;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t124 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t124.{core::List::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t124.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t124;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t125 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t125.{core::Set::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t125.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t125.{core::Set::add}(null);
   } =>#t125;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t126 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t126.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t126.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t126.{core::Map::[]=}("baz", null);
   } =>#t126;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t127 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      for (final dynamic #t128 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      for (final dynamic #t128 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t129 = #t128 as{TypeError} core::int*;
         #t127.{core::List::add}(#t129);
       }
   } =>#t127;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t130 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      for (final dynamic #t131 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      for (final dynamic #t131 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t132 = #t131 as{TypeError} core::int*;
         #t130.{core::Set::add}(#t132);
       }
@@ -941,8 +941,8 @@
   } =>#t130;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t133 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      for (final core::MapEntry<dynamic, dynamic>* #t134 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      for (final core::MapEntry<dynamic, dynamic>* #t134 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
         final core::String* #t135 = #t134.{core::MapEntry::key} as{TypeError} core::String*;
         final core::int* #t136 = #t134.{core::MapEntry::value} as{TypeError} core::int*;
         #t133.{core::Map::[]=}(#t135, #t136);
@@ -951,31 +951,31 @@
   } =>#t133;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t137 = <core::int*>[];
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t137.{core::List::add}(42);
   } =>#t137;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t138 = col::LinkedHashSet::•<core::int*>();
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t138.{core::Set::add}(42);
   } =>#t138;
   core::Map<core::int*, core::int*>* map100 = block {
     final core::Map<core::int*, core::int*>* #t139 = <core::int*, core::int*>{};
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t139.{core::Map::[]=}(42, 42);
   } =>#t139;
 }
 static method testIfElementErrors(core::Map<core::int*, core::int*>* map) → dynamic {
   block {
     final core::List<core::int*>* #t140 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t140.{core::List::add}(let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:89:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) \"bar\"];
                            ^" in "bar" as{TypeError} core::int*);
   } =>#t140;
   block {
     final core::Set<core::int*>* #t142 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t142.{core::Set::add}(let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:90:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) \"bar\", null};
                            ^" in "bar" as{TypeError} core::int*);
@@ -983,7 +983,7 @@
   } =>#t142;
   block {
     final core::Map<core::String*, core::int*>* #t144 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t144.{core::Map::[]=}("bar", let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:91:43: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) \"bar\": \"bar\", \"baz\": null};
                                           ^" in "bar" as{TypeError} core::int*);
@@ -991,7 +991,7 @@
   } =>#t144;
   block {
     final core::List<core::int*>* #t146 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t147 in <core::int*>[let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:92:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) ...[\"bar\"]];
                                ^" in "bar" as{TypeError} core::int*])
@@ -999,7 +999,7 @@
   } =>#t146;
   block {
     final core::Set<core::int*>* #t149 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::int* #t150 in <core::int*>[let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:93:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) ...[\"bar\"], null};
                                ^" in "bar" as{TypeError} core::int*])
@@ -1008,7 +1008,7 @@
   } =>#t149;
   block {
     final core::Map<core::String*, core::int*>* #t152 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       for (final core::MapEntry<core::String*, core::int*>* #t153 in <core::String*, core::int*>{"bar": let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:94:47: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) ...{\"bar\": \"bar\"}, \"baz\": null};
                                               ^" in "bar" as{TypeError} core::int*}.{core::Map::entries})
@@ -1017,7 +1017,7 @@
   } =>#t152;
   block {
     final core::List<core::int*>* #t155 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t155.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:95:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map];
@@ -1025,7 +1025,7 @@
   } =>#t155;
   block {
     final core::Set<core::int*>* #t156 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t156.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:96:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map, null};
@@ -1041,7 +1041,7 @@
                                       ^": null};
   block {
     final core::List<core::String*>* #t157 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t157.{core::List::add}(let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:98:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[if (oracle(\"foo\")) 42 else 3.14];
                               ^" in 42 as{TypeError} core::String*);
@@ -1052,7 +1052,7 @@
   } =>#t157;
   block {
     final core::Set<core::String*>* #t160 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t160.{core::Set::add}(let final<BottomType> #t161 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:99:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{if (oracle(\"foo\")) 42 else 3.14, null};
                               ^" in 42 as{TypeError} core::String*);
@@ -1064,7 +1064,7 @@
   } =>#t160;
   block {
     final core::Map<core::String*, core::String*>* #t163 = <core::String*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t163.{core::Map::[]=}("bar", let final<BottomType> #t164 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:100:46: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{if (oracle(\"foo\")) \"bar\": 42 else \"baz\": 3.14, \"baz\": null};
                                              ^" in 42 as{TypeError} core::String*);
@@ -1076,7 +1076,7 @@
   } =>#t163;
   block {
     final core::List<core::int*>* #t166 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t166.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:101:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map else 42];
@@ -1086,7 +1086,7 @@
   } =>#t166;
   block {
     final core::Set<core::int*>* #t167 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t167.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:102:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1104,7 +1104,7 @@
                                       ^": null};
   block {
     final core::List<core::int*>* #t168 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t168.{core::List::add}(42);
     else
       #t168.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:104:39: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -1114,7 +1114,7 @@
   } =>#t168;
   block {
     final core::Set<core::int*>* #t169 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t169.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:105:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1171,7 +1171,7 @@
   } =>#t174;
   core::List<core::String*>* list40 = block {
     final core::List<core::String*>* #t176 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t176.{core::List::add}(let final<BottomType> #t177 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:117:53: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   List<String> list40 = <String>[if (oracle(\"foo\")) true else 42];
                                                     ^" in true as{TypeError} core::String*);
@@ -1182,7 +1182,7 @@
   } =>#t176;
   core::Set<core::String*>* set40 = block {
     final core::Set<core::String*>* #t179 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t179.{core::Set::add}(let final<BottomType> #t180 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:118:51: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Set<String> set40 = <String>{if (oracle(\"foo\")) true else 42};
                                                   ^" in true as{TypeError} core::String*);
@@ -1193,7 +1193,7 @@
   } =>#t179;
   core::Map<core::String*, core::int*>* map40 = block {
     final core::Map<core::String*, core::int*>* #t182 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t182.{core::Map::[]=}(let final<BottomType> #t183 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:119:61: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<String, int> map40 = <String, int>{if (oracle(\"foo\")) true: 42 else 42: 42};
                                                             ^" in true as{TypeError} core::String*, 42);
@@ -1204,7 +1204,7 @@
   } =>#t182;
   core::Map<core::int*, core::String*>* map41 = block {
     final core::Map<core::int*, core::String*>* #t185 = <core::int*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t185.{core::Map::[]=}(42, let final<BottomType> #t186 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:120:65: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<int, String> map41 = <int, String>{if (oracle(\"foo\")) 42: true else 42: 42};
                                                                 ^" in true as{TypeError} core::String*);
@@ -1217,380 +1217,380 @@
 static method testForElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::int* index, core::Map<core::String*, core::int*>* mapStringInt, core::Map<core::String*, core::double*>* mapStringDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t188 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t188.{core::List::add}(42);
   } =>#t188;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t189 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t189.{core::Set::add}(42);
     #t189.{core::Set::add}(null);
   } =>#t189;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t190 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t190.{core::Map::[]=}("bar", 42);
     #t190.{core::Map::[]=}("baz", null);
   } =>#t190;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t191 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t191.{core::List::add}(dynVar);
   } =>#t191;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t192 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t192.{core::Set::add}(dynVar);
     #t192.{core::Set::add}(null);
   } =>#t192;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t193 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t193.{core::Map::[]=}("bar", dynVar);
     #t193.{core::Map::[]=}("baz", null);
   } =>#t193;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t194 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t194.{core::List::add}(<core::int*>[42]);
   } =>#t194;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t195 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t195.{core::Set::add}(<core::int*>[42]);
     #t195.{core::Set::add}(null);
   } =>#t195;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t196 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t196.{core::Map::[]=}("bar", <core::int*>[42]);
     #t196.{core::Map::[]=}("baz", null);
   } =>#t196;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t197 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t198 in <core::int*>[42])
         #t197.{core::List::add}(#t198);
   } =>#t197;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t199 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t200 in <core::int*>[42])
         #t199.{core::Set::add}(#t200);
     #t199.{core::Set::add}(null);
   } =>#t199;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t201 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::int*>* #t202 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
         #t201.{core::Map::[]=}(#t202.{core::MapEntry::key}, #t202.{core::MapEntry::value});
     #t201.{core::Map::[]=}("baz", null);
   } =>#t201;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t203 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final dynamic #t204 in <dynamic>[dynVar])
         #t203.{core::List::add}(#t204);
   } =>#t203;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t205 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final dynamic #t206 in <dynamic>[dynVar])
         #t205.{core::Set::add}(#t206);
     #t205.{core::Set::add}(null);
   } =>#t205;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t207 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, dynamic>* #t208 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
         #t207.{core::Map::[]=}(#t208.{core::MapEntry::key}, #t208.{core::MapEntry::value});
     #t207.{core::Map::[]=}("baz", null);
   } =>#t207;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t209 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t210 in <core::List<core::int*>*>[<core::int*>[42]])
         #t209.{core::List::add}(#t210);
   } =>#t209;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t211 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t212 in <core::List<core::int*>*>[<core::int*>[42]])
         #t211.{core::Set::add}(#t212);
     #t211.{core::Set::add}(null);
   } =>#t211;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t213 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t214 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
         #t213.{core::Map::[]=}(#t214.{core::MapEntry::key}, #t214.{core::MapEntry::value});
     #t213.{core::Map::[]=}("baz", null);
   } =>#t213;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t215 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t216 in <core::int*>[42])
           #t215.{core::List::add}(#t216);
   } =>#t215;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t217 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t218 in <core::int*>[42])
           #t217.{core::Set::add}(#t218);
     #t217.{core::Set::add}(null);
   } =>#t217;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t219 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::int*>* #t220 in <core::String*, core::int*>{"bar": 42}.{core::Map::entries})
           #t219.{core::Map::[]=}(#t220.{core::MapEntry::key}, #t220.{core::MapEntry::value});
     #t219.{core::Map::[]=}("baz", null);
   } =>#t219;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t221 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t222 in <dynamic>[dynVar])
           #t221.{core::List::add}(#t222);
   } =>#t221;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t223 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t224 in <dynamic>[dynVar])
           #t223.{core::Set::add}(#t224);
     #t223.{core::Set::add}(null);
   } =>#t223;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t225 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, dynamic>* #t226 in <core::String*, dynamic>{"bar": dynVar}.{core::Map::entries})
           #t225.{core::Map::[]=}(#t226.{core::MapEntry::key}, #t226.{core::MapEntry::value});
     #t225.{core::Map::[]=}("baz", null);
   } =>#t225;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t227 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t228 in <core::List<core::int*>*>[<core::int*>[42]])
           #t227.{core::List::add}(#t228);
   } =>#t227;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t229 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t230 in <core::List<core::int*>*>[<core::int*>[42]])
           #t229.{core::Set::add}(#t230);
     #t229.{core::Set::add}(null);
   } =>#t229;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t231 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t232 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries})
           #t231.{core::Map::[]=}(#t232.{core::MapEntry::key}, #t232.{core::MapEntry::value});
     #t231.{core::Map::[]=}("baz", null);
   } =>#t231;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t233 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t234 in <core::List<core::int*>*>[<core::int*>[]])
         #t233.{core::List::add}(#t234);
   } =>#t233;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t235 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t236 in <core::List<core::int*>*>[<core::int*>[]])
         #t235.{core::Set::add}(#t236);
     #t235.{core::Set::add}(null);
   } =>#t235;
   core::Map<core::String*, core::List<core::int*>*>* map40 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t237 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t238 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
         #t237.{core::Map::[]=}(#t238.{core::MapEntry::key}, #t238.{core::MapEntry::value});
     #t237.{core::Map::[]=}("baz", null);
   } =>#t237;
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t239 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t240 in let final core::Set<core::List<core::int*>*>* #t241 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t242 = #t241.{core::Set::add}(<core::int*>[]) in #t241)
         #t239.{core::List::add}(#t240);
   } =>#t239;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t243 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t244 in let final core::Set<core::List<core::int*>*>* #t245 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final dynamic #t246 = #t245.{core::Set::add}(<core::int*>[]) in #t245)
         #t243.{core::Set::add}(#t244);
     #t243.{core::Set::add}(null);
   } =>#t243;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t247 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t248 in <core::List<core::int*>*>[<core::int*>[]])
           #t247.{core::List::add}(#t248);
   } =>#t247;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t249 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t250 in <core::List<core::int*>*>[<core::int*>[]])
           #t249.{core::Set::add}(#t250);
     #t249.{core::Set::add}(null);
   } =>#t249;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t251 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t252 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t251.{core::Map::[]=}(#t252.{core::MapEntry::key}, #t252.{core::MapEntry::value});
     #t251.{core::Map::[]=}("baz", null);
   } =>#t251;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t253 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t254 in <core::int*>[])
         #t253.{core::List::add}(#t254);
   } =>#t253;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t255 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t256 in <core::int*>[])
         #t255.{core::Set::add}(#t256);
     #t255.{core::Set::add}(null);
   } =>#t255;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t257 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::int*>* #t258 in <core::String*, core::int*>{}.{core::Map::entries})
         #t257.{core::Map::[]=}(#t258.{core::MapEntry::key}, #t258.{core::MapEntry::value});
     #t257.{core::Map::[]=}("baz", null);
   } =>#t257;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t259 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t260 in let final core::Set<core::int*>* #t261 = col::LinkedHashSet::•<core::int*>() in #t261)
         #t259.{core::List::add}(#t260);
   } =>#t259;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t262 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t263 in let final core::Set<core::int*>* #t264 = col::LinkedHashSet::•<core::int*>() in #t264)
         #t262.{core::Set::add}(#t263);
     #t262.{core::Set::add}(null);
   } =>#t262;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t265 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t266 in <core::int*>[])
           #t265.{core::List::add}(#t266);
   } =>#t265;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t267 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::int* #t268 in <core::int*>[])
           #t267.{core::Set::add}(#t268);
     #t267.{core::Set::add}(null);
   } =>#t267;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t269 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t270 in <core::List<core::int*>*>[<core::int*>[]])
         #t269.{core::List::add}(#t270);
   } =>#t269;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t271 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::List<core::int*>* #t272 in <core::List<core::int*>*>[<core::int*>[]])
         #t271.{core::Set::add}(#t272);
     #t271.{core::Set::add}(null);
   } =>#t271;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t273 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t274 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
         #t273.{core::Map::[]=}(#t274.{core::MapEntry::key}, #t274.{core::MapEntry::value});
     #t273.{core::Map::[]=}("baz", null);
   } =>#t273;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t275 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t276 in <core::List<core::int*>*>[<core::int*>[]])
           #t275.{core::List::add}(#t276);
   } =>#t275;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t277 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::List<core::int*>* #t278 in <core::List<core::int*>*>[<core::int*>[]])
           #t277.{core::Set::add}(#t278);
     #t277.{core::Set::add}(null);
   } =>#t277;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t279 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::List<core::int*>*>* #t280 in <core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries})
           #t279.{core::Map::[]=}(#t280.{core::MapEntry::key}, #t280.{core::MapEntry::value});
     #t279.{core::Map::[]=}("baz", null);
   } =>#t279;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t281 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t281.{core::List::add}(<core::int*>[]);
   } =>#t281;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t282 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t282.{core::Set::add}(<core::int*>[]);
     #t282.{core::Set::add}(null);
   } =>#t282;
   core::Map<core::String*, core::List<core::int*>*>* map70 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t283 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t283.{core::Map::[]=}("bar", <core::int*>[]);
     #t283.{core::Map::[]=}("baz", null);
   } =>#t283;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t284 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t284.{core::List::add}(<core::int*>[]);
   } =>#t284;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t285 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t285.{core::Set::add}(<core::int*>[]);
     #t285.{core::Set::add}(null);
   } =>#t285;
   core::Map<core::String*, core::List<core::int*>*>* map71 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t286 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t286.{core::Map::[]=}("bar", <core::int*>[]);
     #t286.{core::Map::[]=}("baz", null);
   } =>#t286;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t287 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t287.{core::List::add}(42);
       else
         #t287.{core::List::add}(3.14);
   } =>#t287;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t288 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t288.{core::Set::add}(42);
       else
         #t288.{core::Set::add}(3.14);
@@ -1598,8 +1598,8 @@
   } =>#t288;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t289 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t289.{core::Map::[]=}("bar", 42);
       else
         #t289.{core::Map::[]=}("bar", 3.14);
@@ -1607,8 +1607,8 @@
   } =>#t289;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t290 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::num* #t291 in listInt)
           #t290.{core::List::add}(#t291);
       else
@@ -1617,8 +1617,8 @@
   } =>#t290;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t293 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::num* #t294 in listInt)
           #t293.{core::Set::add}(#t294);
       else
@@ -1628,8 +1628,8 @@
   } =>#t293;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t296 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::num*>* #t297 in mapStringInt.{core::Map::entries})
           #t296.{core::Map::[]=}(#t297.{core::MapEntry::key}, #t297.{core::MapEntry::value});
       else
@@ -1639,40 +1639,40 @@
   } =>#t296;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t299 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t300 in listInt)
           #t299.{core::List::add}(#t300);
       else
-        for (final dynamic #t301 in dynVar as{TypeError} core::Iterable<dynamic>*)
+        for (final dynamic #t301 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
           #t299.{core::List::add}(#t301);
   } =>#t299;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t302 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final dynamic #t303 in listInt)
           #t302.{core::Set::add}(#t303);
       else
-        for (final dynamic #t304 in dynVar as{TypeError} core::Iterable<dynamic>*)
+        for (final dynamic #t304 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
           #t302.{core::Set::add}(#t304);
     #t302.{core::Set::add}(null);
   } =>#t302;
   core::Map<dynamic, dynamic>* map82 = block {
     final core::Map<dynamic, dynamic>* #t305 = <dynamic, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<dynamic, dynamic>* #t306 in mapStringInt.{core::Map::entries})
           #t305.{core::Map::[]=}(#t306.{core::MapEntry::key}, #t306.{core::MapEntry::value});
       else
-        for (final core::MapEntry<dynamic, dynamic>* #t307 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries})
+        for (final core::MapEntry<dynamic, dynamic>* #t307 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries})
           #t305.{core::Map::[]=}(#t307.{core::MapEntry::key}, #t307.{core::MapEntry::value});
     #t305.{core::Map::[]=}("baz", null);
   } =>#t305;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t308 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t308.{core::List::add}(42);
       else
         for (final core::num* #t309 in listDouble)
@@ -1680,8 +1680,8 @@
   } =>#t308;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t310 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::num* #t311 in listInt)
           #t310.{core::Set::add}(#t311);
       else
@@ -1690,8 +1690,8 @@
   } =>#t310;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t312 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         for (final core::MapEntry<core::String*, core::num*>* #t313 in mapStringInt.{core::Map::entries})
           #t312.{core::Map::[]=}(#t313.{core::MapEntry::key}, #t313.{core::MapEntry::value});
       else
@@ -1700,33 +1700,33 @@
   } =>#t312;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t314 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t314.{core::List::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t314.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t314;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t315 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t315.{core::Set::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t315.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t315.{core::Set::add}(null);
   } =>#t315;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t316 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t316.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t316.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t316.{core::Map::[]=}("baz", null);
   } =>#t316;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t317 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      for (final dynamic #t318 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      for (final dynamic #t318 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t319 = #t318 as{TypeError} core::int*;
         #t317.{core::List::add}(#t319);
       }
   } =>#t317;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t320 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      for (final dynamic #t321 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      for (final dynamic #t321 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         final core::int* #t322 = #t321 as{TypeError} core::int*;
         #t320.{core::Set::add}(#t322);
       }
@@ -1734,8 +1734,8 @@
   } =>#t320;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t323 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      for (final core::MapEntry<dynamic, dynamic>* #t324 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      for (final core::MapEntry<dynamic, dynamic>* #t324 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
         final core::String* #t325 = #t324.{core::MapEntry::key} as{TypeError} core::String*;
         final core::int* #t326 = #t324.{core::MapEntry::value} as{TypeError} core::int*;
         #t323.{core::Map::[]=}(#t325, #t326);
@@ -1744,17 +1744,17 @@
   } =>#t323;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t327 = <core::int*>[];
-    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t327.{core::List::add}(42);
   } =>#t327;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t329 = col::LinkedHashSet::•<core::int*>();
-    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t329.{core::Set::add}(42);
   } =>#t329;
   core::Map<core::String*, core::int*>* map100 = block {
     final core::Map<core::String*, core::int*>* #t331 = <core::String*, core::int*>{};
-    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t331.{core::Map::[]=}("bar", 42);
   } =>#t331;
   core::List<core::int*>* list110 = block {
@@ -1776,19 +1776,19 @@
   } =>#t335;
   core::List<core::int*>* list120 = block {
     final core::List<core::int*>* #t336 = <core::int*>[];
-    for (dynamic i in dynVar as{TypeError} core::Iterable<dynamic>*)
-      #t336.{core::List::add}(i as{TypeError} core::int*);
+    for (dynamic i in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
+      #t336.{core::List::add}(i as{TypeError,ForDynamic} core::int*);
   } =>#t336;
   core::Set<core::int*>* set120 = block {
     final core::Set<core::int*>* #t337 = col::LinkedHashSet::•<core::int*>();
-    for (dynamic i in dynVar as{TypeError} core::Iterable<dynamic>*)
-      #t337.{core::Set::add}(i as{TypeError} core::int*);
+    for (dynamic i in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
+      #t337.{core::Set::add}(i as{TypeError,ForDynamic} core::int*);
     #t337.{core::Set::add}(null);
   } =>#t337;
   core::Map<core::String*, core::int*>* map120 = block {
     final core::Map<core::String*, core::int*>* #t338 = <core::String*, core::int*>{};
-    for (dynamic i in dynVar as{TypeError} core::Iterable<dynamic>*)
-      #t338.{core::Map::[]=}("bar", i as{TypeError} core::int*);
+    for (dynamic i in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*)
+      #t338.{core::Map::[]=}("bar", i as{TypeError,ForDynamic} core::int*);
     #t338.{core::Map::[]=}("baz", null);
   } =>#t338;
   core::List<core::int*>* list130 = block {
@@ -1810,14 +1810,14 @@
 static method testForElementErrors(core::Map<core::int*, core::int*>* map, core::List<core::int*>* list) → dynamic async {
   block {
     final core::List<core::int*>* #t342 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t342.{core::List::add}(let final<BottomType> #t343 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:212:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) \"bar\"];
                                             ^" in "bar" as{TypeError} core::int*);
   } =>#t342;
   block {
     final core::Set<core::int*>* #t344 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t344.{core::Set::add}(let final<BottomType> #t345 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:213:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\", null};
                                             ^" in "bar" as{TypeError} core::int*);
@@ -1825,7 +1825,7 @@
   } =>#t344;
   block {
     final core::Map<core::int*, core::int*>* #t346 = <core::int*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t346.{core::Map::[]=}(let final<BottomType> #t347 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:214:50: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\": \"bar\", \"baz\": null};
                                                  ^" in "bar" as{TypeError} core::int*, let final<BottomType> #t348 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:214:57: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -1837,7 +1837,7 @@
   } =>#t346;
   block {
     final core::List<core::int*>* #t350 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t351 in <core::int*>[let final<BottomType> #t352 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:215:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"]];
                                                 ^" in "bar" as{TypeError} core::int*])
@@ -1845,7 +1845,7 @@
   } =>#t350;
   block {
     final core::Set<core::int*>* #t353 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::int* #t354 in <core::int*>[let final<BottomType> #t355 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:216:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"], null};
                                                 ^" in "bar" as{TypeError} core::int*])
@@ -1854,7 +1854,7 @@
   } =>#t353;
   block {
     final core::Map<core::int*, core::int*>* #t356 = <core::int*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       for (final core::MapEntry<core::int*, core::int*>* #t357 in <core::int*, core::int*>{let final<BottomType> #t358 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:217:54: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) ...{\"bar\": \"bar\"}, \"baz\": null};
                                                      ^" in "bar" as{TypeError} core::int*: let final<BottomType> #t359 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:217:61: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -1867,7 +1867,7 @@
   } =>#t356;
   block {
     final core::List<core::int*>* #t361 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t361.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:218:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...map];
@@ -1875,7 +1875,7 @@
   } =>#t361;
   block {
     final core::Set<core::int*>* #t362 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t362.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:219:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...map, null};
@@ -1891,8 +1891,8 @@
                                                     ^": null};
   block {
     final core::List<core::String*>* #t363 = <core::String*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t363.{core::List::add}(let final<BottomType> #t364 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:221:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14];
                                                              ^" in 42 as{TypeError} core::String*);
@@ -1903,8 +1903,8 @@
   } =>#t363;
   block {
     final core::Set<core::String*>* #t366 = col::LinkedHashSet::•<core::String*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t366.{core::Set::add}(let final<BottomType> #t367 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:222:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14, null};
                                                              ^" in 42 as{TypeError} core::String*);
@@ -1916,8 +1916,8 @@
   } =>#t366;
   block {
     final core::Map<core::String*, core::String*>* #t369 = <core::String*, core::String*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t369.{core::Map::[]=}("bar", let final<BottomType> #t370 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:223:77: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) \"bar\": 42 else \"bar\": 3.14, \"baz\": null};
                                                                             ^" in 42 as{TypeError} core::String*);
@@ -1929,8 +1929,8 @@
   } =>#t369;
   block {
     final core::List<core::int*>* #t372 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t372.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:224:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42];
@@ -1940,8 +1940,8 @@
   } =>#t372;
   block {
     final core::Set<core::int*>* #t373 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t373.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:225:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42, null};
@@ -1959,8 +1959,8 @@
                                                                      ^": null};
   block {
     final core::List<core::int*>* #t374 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t374.{core::List::add}(42);
       else
         #t374.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:227:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -1970,8 +1970,8 @@
   } =>#t374;
   block {
     final core::Set<core::int*>* #t375 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t375.{core::Set::add}(42);
       else
         #t375.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:228:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.weak.transformed.expect
index 2901fae..dfec04b 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart.weak.transformed.expect
@@ -444,58 +444,58 @@
 static method testIfElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::Map<core::String*, core::int*>* mapToInt, core::Map<core::String*, core::double*>* mapToDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t1 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t1.{core::List::add}(42);
   } =>#t1;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t2 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t2.{core::Set::add}(42);
     #t2.{core::Set::add}(null);
   } =>#t2;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t3 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t3.{core::Map::[]=}("bar", 42);
     #t3.{core::Map::[]=}("baz", null);
   } =>#t3;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t4 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t4.{core::List::add}(dynVar);
   } =>#t4;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t5 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t5.{core::Set::add}(dynVar);
     #t5.{core::Set::add}(null);
   } =>#t5;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t6 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t6.{core::Map::[]=}("bar", dynVar);
     #t6.{core::Map::[]=}("baz", null);
   } =>#t6;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t7 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t7.{core::List::add}(<core::int*>[42]);
   } =>#t7;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t8 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t8.{core::Set::add}(<core::int*>[42]);
     #t8.{core::Set::add}(null);
   } =>#t8;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t9 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t9.{core::Map::[]=}("bar", <core::int*>[42]);
     #t9.{core::Map::[]=}("baz", null);
   } =>#t9;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t10 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t11 = :sync-for-iterator.{core::Iterator::current};
@@ -505,7 +505,7 @@
   } =>#t10;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t12 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t13 = :sync-for-iterator.{core::Iterator::current};
@@ -516,7 +516,7 @@
   } =>#t12;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t14 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t15 = :sync-for-iterator.{core::Iterator::current};
@@ -527,7 +527,7 @@
   } =>#t14;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t16 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t17 = :sync-for-iterator.{core::Iterator::current};
@@ -537,7 +537,7 @@
   } =>#t16;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t18 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t19 = :sync-for-iterator.{core::Iterator::current};
@@ -548,7 +548,7 @@
   } =>#t18;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t20 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, dynamic>* #t21 = :sync-for-iterator.{core::Iterator::current};
@@ -559,7 +559,7 @@
   } =>#t20;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t22 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t23 = :sync-for-iterator.{core::Iterator::current};
@@ -569,7 +569,7 @@
   } =>#t22;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t24 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t25 = :sync-for-iterator.{core::Iterator::current};
@@ -580,7 +580,7 @@
   } =>#t24;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t26 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t27 = :sync-for-iterator.{core::Iterator::current};
@@ -591,8 +591,8 @@
   } =>#t26;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t28 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t29 = :sync-for-iterator.{core::Iterator::current};
@@ -602,8 +602,8 @@
   } =>#t28;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t30 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t31 = :sync-for-iterator.{core::Iterator::current};
@@ -614,8 +614,8 @@
   } =>#t30;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t32 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::int*>* #t33 = :sync-for-iterator.{core::Iterator::current};
@@ -626,8 +626,8 @@
   } =>#t32;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t34 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t35 = :sync-for-iterator.{core::Iterator::current};
@@ -637,8 +637,8 @@
   } =>#t34;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t36 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t37 = :sync-for-iterator.{core::Iterator::current};
@@ -649,8 +649,8 @@
   } =>#t36;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t38 = <core::String*, dynamic>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, dynamic>* #t39 = :sync-for-iterator.{core::Iterator::current};
@@ -661,8 +661,8 @@
   } =>#t38;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t40 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t41 = :sync-for-iterator.{core::Iterator::current};
@@ -672,8 +672,8 @@
   } =>#t40;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t42 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t43 = :sync-for-iterator.{core::Iterator::current};
@@ -684,8 +684,8 @@
   } =>#t42;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t44 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t45 = :sync-for-iterator.{core::Iterator::current};
@@ -696,7 +696,7 @@
   } =>#t44;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t46 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t47 = :sync-for-iterator.{core::Iterator::current};
@@ -706,7 +706,7 @@
   } =>#t46;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t48 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t49 = :sync-for-iterator.{core::Iterator::current};
@@ -720,7 +720,7 @@
                                  ^";
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t50 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t51 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t52 = #t51.{core::Set::add}(<core::int*>[]) in #t51).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t53 = :sync-for-iterator.{core::Iterator::current};
@@ -730,7 +730,7 @@
   } =>#t50;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t54 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t55 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t56 = #t55.{core::Set::add}(<core::int*>[]) in #t55).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t57 = :sync-for-iterator.{core::Iterator::current};
@@ -741,8 +741,8 @@
   } =>#t54;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t58 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t59 = :sync-for-iterator.{core::Iterator::current};
@@ -752,8 +752,8 @@
   } =>#t58;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t60 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t61 = :sync-for-iterator.{core::Iterator::current};
@@ -764,8 +764,8 @@
   } =>#t60;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t62 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t63 = :sync-for-iterator.{core::Iterator::current};
@@ -776,7 +776,7 @@
   } =>#t62;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t64 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t65 = :sync-for-iterator.{core::Iterator::current};
@@ -786,7 +786,7 @@
   } =>#t64;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t66 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t67 = :sync-for-iterator.{core::Iterator::current};
@@ -797,7 +797,7 @@
   } =>#t66;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t68 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t69 = :sync-for-iterator.{core::Iterator::current};
@@ -808,7 +808,7 @@
   } =>#t68;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t70 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t71 = col::LinkedHashSet::•<core::int*>() in #t71).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t72 = :sync-for-iterator.{core::Iterator::current};
@@ -818,7 +818,7 @@
   } =>#t70;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t73 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t74 = col::LinkedHashSet::•<core::int*>() in #t74).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t75 = :sync-for-iterator.{core::Iterator::current};
@@ -829,8 +829,8 @@
   } =>#t73;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t76 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t77 = :sync-for-iterator.{core::Iterator::current};
@@ -840,8 +840,8 @@
   } =>#t76;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t78 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t79 = :sync-for-iterator.{core::Iterator::current};
@@ -852,8 +852,8 @@
   } =>#t78;
   core::Map<core::String*, core::int*>* map52 = block {
     final core::Map<core::String*, core::int*>* #t80 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::int*>* #t81 = :sync-for-iterator.{core::Iterator::current};
@@ -864,7 +864,7 @@
   } =>#t80;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t82 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t83 = :sync-for-iterator.{core::Iterator::current};
@@ -874,7 +874,7 @@
   } =>#t82;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t84 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t85 = :sync-for-iterator.{core::Iterator::current};
@@ -885,7 +885,7 @@
   } =>#t84;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t86 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t87 = :sync-for-iterator.{core::Iterator::current};
@@ -896,8 +896,8 @@
   } =>#t86;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t88 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t89 = :sync-for-iterator.{core::Iterator::current};
@@ -907,8 +907,8 @@
   } =>#t88;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t90 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t91 = :sync-for-iterator.{core::Iterator::current};
@@ -919,8 +919,8 @@
   } =>#t90;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t92 = <core::String*, core::List<core::int*>*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t93 = :sync-for-iterator.{core::Iterator::current};
@@ -931,38 +931,38 @@
   } =>#t92;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t94 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t94.{core::List::add}(<core::int*>[]);
   } =>#t94;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t95 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t95.{core::Set::add}(<core::int*>[]);
     #t95.{core::Set::add}(null);
   } =>#t95;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t96 = <core::List<core::int*>*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t96.{core::List::add}(<core::int*>[]);
   } =>#t96;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t97 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t97.{core::Set::add}(<core::int*>[]);
     #t97.{core::Set::add}(null);
   } =>#t97;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t98 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t98.{core::List::add}(42);
     else
       #t98.{core::List::add}(3.14);
   } =>#t98;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t99 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t99.{core::Set::add}(42);
     else
       #t99.{core::Set::add}(3.14);
@@ -970,7 +970,7 @@
   } =>#t99;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t100 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t100.{core::Map::[]=}("bar", 42);
     else
       #t100.{core::Map::[]=}("bar", 3.14);
@@ -978,7 +978,7 @@
   } =>#t100;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t101 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::num* #t102 = :sync-for-iterator.{core::Iterator::current};
@@ -995,7 +995,7 @@
   } =>#t101;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t104 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::num* #t105 = :sync-for-iterator.{core::Iterator::current};
@@ -1013,7 +1013,7 @@
   } =>#t104;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t107 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapToInt.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::num*>* #t108 = :sync-for-iterator.{core::Iterator::current};
@@ -1031,7 +1031,7 @@
   } =>#t107;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t110 = <dynamic>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t111 = :sync-for-iterator.{core::Iterator::current};
@@ -1039,7 +1039,7 @@
       }
     }
     else {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t112 = :sync-for-iterator.{core::Iterator::current};
         #t110.{core::List::add}(#t112);
@@ -1048,7 +1048,7 @@
   } =>#t110;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t113 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t114 = :sync-for-iterator.{core::Iterator::current};
@@ -1056,7 +1056,7 @@
       }
     }
     else {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t115 = :sync-for-iterator.{core::Iterator::current};
         #t113.{core::Set::add}(#t115);
@@ -1066,13 +1066,13 @@
   } =>#t113;
   core::Set<dynamic>* map82 = block {
     final core::Set<dynamic>* #t116 = col::LinkedHashSet::•<dynamic>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t116.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:73:38: Error: Unexpected type 'Map<String, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   var map82 = {if (oracle(\"foo\")) ...mapToInt else ...dynVar, null};
                                      ^");
     else {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t117 = :sync-for-iterator.{core::Iterator::current};
         #t116.{core::Set::add}(#t117);
@@ -1082,7 +1082,7 @@
   } =>#t116;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t118 = <core::num*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t118.{core::List::add}(42);
     else {
       core::Iterator<core::double*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::double*>*>(listDouble).{core::Iterable::iterator};
@@ -1094,7 +1094,7 @@
   } =>#t118;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t120 = col::LinkedHashSet::•<core::num*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::num* #t121 = :sync-for-iterator.{core::Iterator::current};
@@ -1107,7 +1107,7 @@
   } =>#t120;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t122 = <core::String*, core::num*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapToInt.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::num*>* #t123 = :sync-for-iterator.{core::Iterator::current};
@@ -1120,25 +1120,25 @@
   } =>#t122;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t124 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t124.{core::List::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t124.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t124;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t125 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t125.{core::Set::add}(dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t125.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t125.{core::Set::add}(null);
   } =>#t125;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t126 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
-      #t126.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
+      #t126.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t126.{core::Map::[]=}("baz", null);
   } =>#t126;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t127 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t128 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -1150,8 +1150,8 @@
   } =>#t127;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t130 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t131 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -1164,8 +1164,8 @@
   } =>#t130;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t133 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t134 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -1179,31 +1179,31 @@
   } =>#t133;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t137 = <core::int*>[];
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t137.{core::List::add}(42);
   } =>#t137;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t138 = col::LinkedHashSet::•<core::int*>();
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t138.{core::Set::add}(42);
   } =>#t138;
   core::Map<core::int*, core::int*>* map100 = block {
     final core::Map<core::int*, core::int*>* #t139 = <core::int*, core::int*>{};
-    if(dynVar as{TypeError} core::bool*)
+    if(dynVar as{TypeError,ForDynamic} core::bool*)
       #t139.{core::Map::[]=}(42, 42);
   } =>#t139;
 }
 static method testIfElementErrors(core::Map<core::int*, core::int*>* map) → dynamic {
   block {
     final core::List<core::int*>* #t140 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t140.{core::List::add}(let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:89:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) \"bar\"];
                            ^" in "bar" as{TypeError} core::int*);
   } =>#t140;
   block {
     final core::Set<core::int*>* #t142 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t142.{core::Set::add}(let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:90:28: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) \"bar\", null};
                            ^" in "bar" as{TypeError} core::int*);
@@ -1211,7 +1211,7 @@
   } =>#t142;
   block {
     final core::Map<core::String*, core::int*>* #t144 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t144.{core::Map::[]=}("bar", let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:91:43: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) \"bar\": \"bar\", \"baz\": null};
                                           ^" in "bar" as{TypeError} core::int*);
@@ -1219,7 +1219,7 @@
   } =>#t144;
   block {
     final core::List<core::int*>* #t146 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:92:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[if (oracle(\"foo\")) ...[\"bar\"]];
                                ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -1231,7 +1231,7 @@
   } =>#t146;
   block {
     final core::Set<core::int*>* #t149 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:93:32: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{if (oracle(\"foo\")) ...[\"bar\"], null};
                                ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -1244,7 +1244,7 @@
   } =>#t149;
   block {
     final core::Map<core::String*, core::int*>* #t152 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*) {
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:94:47: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <String, int>{if (oracle(\"foo\")) ...{\"bar\": \"bar\"}, \"baz\": null};
                                               ^" in "bar" as{TypeError} core::int*}.{core::Map::entries}).{core::Iterable::iterator};
@@ -1257,7 +1257,7 @@
   } =>#t152;
   block {
     final core::List<core::int*>* #t155 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t155.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:95:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map];
@@ -1265,7 +1265,7 @@
   } =>#t155;
   block {
     final core::Set<core::int*>* #t156 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t156.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:96:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map, null};
@@ -1281,7 +1281,7 @@
                                       ^": null};
   block {
     final core::List<core::String*>* #t157 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t157.{core::List::add}(let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:98:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[if (oracle(\"foo\")) 42 else 3.14];
                               ^" in 42 as{TypeError} core::String*);
@@ -1292,7 +1292,7 @@
   } =>#t157;
   block {
     final core::Set<core::String*>* #t160 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t160.{core::Set::add}(let final<BottomType> #t161 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:99:31: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{if (oracle(\"foo\")) 42 else 3.14, null};
                               ^" in 42 as{TypeError} core::String*);
@@ -1304,7 +1304,7 @@
   } =>#t160;
   block {
     final core::Map<core::String*, core::String*>* #t163 = <core::String*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t163.{core::Map::[]=}("bar", let final<BottomType> #t164 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:100:46: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{if (oracle(\"foo\")) \"bar\": 42 else \"baz\": 3.14, \"baz\": null};
                                              ^" in 42 as{TypeError} core::String*);
@@ -1316,7 +1316,7 @@
   } =>#t163;
   block {
     final core::List<core::int*>* #t166 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t166.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:101:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[if (oracle(\"foo\")) ...map else 42];
@@ -1326,7 +1326,7 @@
   } =>#t166;
   block {
     final core::Set<core::int*>* #t167 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t167.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:102:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1344,7 +1344,7 @@
                                       ^": null};
   block {
     final core::List<core::int*>* #t168 = <core::int*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t168.{core::List::add}(42);
     else
       #t168.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:104:39: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -1354,7 +1354,7 @@
   } =>#t168;
   block {
     final core::Set<core::int*>* #t169 = col::LinkedHashSet::•<core::int*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t169.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:105:31: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{if (oracle(\"foo\")) ...map else 42, null};
@@ -1411,7 +1411,7 @@
   } =>#t174;
   core::List<core::String*>* list40 = block {
     final core::List<core::String*>* #t176 = <core::String*>[];
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t176.{core::List::add}(let final<BottomType> #t177 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:117:53: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   List<String> list40 = <String>[if (oracle(\"foo\")) true else 42];
                                                     ^" in true as{TypeError} core::String*);
@@ -1422,7 +1422,7 @@
   } =>#t176;
   core::Set<core::String*>* set40 = block {
     final core::Set<core::String*>* #t179 = col::LinkedHashSet::•<core::String*>();
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t179.{core::Set::add}(let final<BottomType> #t180 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:118:51: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Set<String> set40 = <String>{if (oracle(\"foo\")) true else 42};
                                                   ^" in true as{TypeError} core::String*);
@@ -1433,7 +1433,7 @@
   } =>#t179;
   core::Map<core::String*, core::int*>* map40 = block {
     final core::Map<core::String*, core::int*>* #t182 = <core::String*, core::int*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t182.{core::Map::[]=}(let final<BottomType> #t183 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:119:61: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<String, int> map40 = <String, int>{if (oracle(\"foo\")) true: 42 else 42: 42};
                                                             ^" in true as{TypeError} core::String*, 42);
@@ -1444,7 +1444,7 @@
   } =>#t182;
   core::Map<core::int*, core::String*>* map41 = block {
     final core::Map<core::int*, core::String*>* #t185 = <core::int*, core::String*>{};
-    if(self::oracle<core::String*>("foo") as{TypeError} core::bool*)
+    if(self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*)
       #t185.{core::Map::[]=}(42, let final<BottomType> #t186 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:120:65: Error: A value of type 'bool' can't be assigned to a variable of type 'String'.
   Map<int, String> map41 = <int, String>{if (oracle(\"foo\")) 42: true else 42: 42};
                                                                 ^" in true as{TypeError} core::String*);
@@ -1457,58 +1457,58 @@
 static method testForElement(dynamic dynVar, core::List<core::int*>* listInt, core::List<core::double*>* listDouble, core::int* index, core::Map<core::String*, core::int*>* mapStringInt, core::Map<core::String*, core::double*>* mapStringDouble) → dynamic {
   core::List<core::int*>* list10 = block {
     final core::List<core::int*>* #t188 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t188.{core::List::add}(42);
   } =>#t188;
   core::Set<core::int*>* set10 = block {
     final core::Set<core::int*>* #t189 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t189.{core::Set::add}(42);
     #t189.{core::Set::add}(null);
   } =>#t189;
   core::Map<core::String*, core::int*>* map10 = block {
     final core::Map<core::String*, core::int*>* #t190 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t190.{core::Map::[]=}("bar", 42);
     #t190.{core::Map::[]=}("baz", null);
   } =>#t190;
   core::List<dynamic>* list11 = block {
     final core::List<dynamic>* #t191 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t191.{core::List::add}(dynVar);
   } =>#t191;
   core::Set<dynamic>* set11 = block {
     final core::Set<dynamic>* #t192 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t192.{core::Set::add}(dynVar);
     #t192.{core::Set::add}(null);
   } =>#t192;
   core::Map<core::String*, dynamic>* map11 = block {
     final core::Map<core::String*, dynamic>* #t193 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t193.{core::Map::[]=}("bar", dynVar);
     #t193.{core::Map::[]=}("baz", null);
   } =>#t193;
   core::List<core::List<core::int*>*>* list12 = block {
     final core::List<core::List<core::int*>*>* #t194 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t194.{core::List::add}(<core::int*>[42]);
   } =>#t194;
   core::Set<core::List<core::int*>*>* set12 = block {
     final core::Set<core::List<core::int*>*>* #t195 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t195.{core::Set::add}(<core::int*>[42]);
     #t195.{core::Set::add}(null);
   } =>#t195;
   core::Map<core::String*, core::List<core::int*>*>* map12 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t196 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t196.{core::Map::[]=}("bar", <core::int*>[42]);
     #t196.{core::Map::[]=}("baz", null);
   } =>#t196;
   core::List<core::int*>* list20 = block {
     final core::List<core::int*>* #t197 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t198 = :sync-for-iterator.{core::Iterator::current};
@@ -1518,7 +1518,7 @@
   } =>#t197;
   core::Set<core::int*>* set20 = block {
     final core::Set<core::int*>* #t199 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t200 = :sync-for-iterator.{core::Iterator::current};
@@ -1529,7 +1529,7 @@
   } =>#t199;
   core::Map<core::String*, core::int*>* map20 = block {
     final core::Map<core::String*, core::int*>* #t201 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t202 = :sync-for-iterator.{core::Iterator::current};
@@ -1540,7 +1540,7 @@
   } =>#t201;
   core::List<dynamic>* list21 = block {
     final core::List<dynamic>* #t203 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t204 = :sync-for-iterator.{core::Iterator::current};
@@ -1550,7 +1550,7 @@
   } =>#t203;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t205 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t206 = :sync-for-iterator.{core::Iterator::current};
@@ -1561,7 +1561,7 @@
   } =>#t205;
   core::Map<core::String*, dynamic>* map21 = block {
     final core::Map<core::String*, dynamic>* #t207 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, dynamic>* #t208 = :sync-for-iterator.{core::Iterator::current};
@@ -1572,7 +1572,7 @@
   } =>#t207;
   core::List<core::List<core::int*>*>* list22 = block {
     final core::List<core::List<core::int*>*>* #t209 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t210 = :sync-for-iterator.{core::Iterator::current};
@@ -1582,7 +1582,7 @@
   } =>#t209;
   core::Set<core::List<core::int*>*>* set22 = block {
     final core::Set<core::List<core::int*>*>* #t211 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t212 = :sync-for-iterator.{core::Iterator::current};
@@ -1593,7 +1593,7 @@
   } =>#t211;
   core::Map<core::String*, core::List<core::int*>*>* map22 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t213 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t214 = :sync-for-iterator.{core::Iterator::current};
@@ -1604,8 +1604,8 @@
   } =>#t213;
   core::List<core::int*>* list30 = block {
     final core::List<core::int*>* #t215 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t216 = :sync-for-iterator.{core::Iterator::current};
@@ -1615,8 +1615,8 @@
   } =>#t215;
   core::Set<core::int*>* set30 = block {
     final core::Set<core::int*>* #t217 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[42]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t218 = :sync-for-iterator.{core::Iterator::current};
@@ -1627,8 +1627,8 @@
   } =>#t217;
   core::Map<core::String*, core::int*>* map30 = block {
     final core::Map<core::String*, core::int*>* #t219 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{"bar": 42}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::int*>* #t220 = :sync-for-iterator.{core::Iterator::current};
@@ -1639,8 +1639,8 @@
   } =>#t219;
   core::List<dynamic>* list31 = block {
     final core::List<dynamic>* #t221 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t222 = :sync-for-iterator.{core::Iterator::current};
@@ -1650,8 +1650,8 @@
   } =>#t221;
   core::Set<dynamic>* set31 = block {
     final core::Set<dynamic>* #t223 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(<dynamic>[dynVar]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t224 = :sync-for-iterator.{core::Iterator::current};
@@ -1662,8 +1662,8 @@
   } =>#t223;
   core::Map<core::String*, dynamic>* map31 = block {
     final core::Map<core::String*, dynamic>* #t225 = <core::String*, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, dynamic>*>*>(<core::String*, dynamic>{"bar": dynVar}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, dynamic>* #t226 = :sync-for-iterator.{core::Iterator::current};
@@ -1674,8 +1674,8 @@
   } =>#t225;
   core::List<core::List<core::int*>*>* list33 = block {
     final core::List<core::List<core::int*>*>* #t227 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t228 = :sync-for-iterator.{core::Iterator::current};
@@ -1685,8 +1685,8 @@
   } =>#t227;
   core::Set<core::List<core::int*>*>* set33 = block {
     final core::Set<core::List<core::int*>*>* #t229 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[42]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t230 = :sync-for-iterator.{core::Iterator::current};
@@ -1697,8 +1697,8 @@
   } =>#t229;
   core::Map<core::String*, core::List<core::int*>*>* map33 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t231 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[42]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t232 = :sync-for-iterator.{core::Iterator::current};
@@ -1709,7 +1709,7 @@
   } =>#t231;
   core::List<core::List<core::int*>*>* list40 = block {
     final core::List<core::List<core::int*>*>* #t233 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t234 = :sync-for-iterator.{core::Iterator::current};
@@ -1719,7 +1719,7 @@
   } =>#t233;
   core::Set<core::List<core::int*>*>* set40 = block {
     final core::Set<core::List<core::int*>*>* #t235 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t236 = :sync-for-iterator.{core::Iterator::current};
@@ -1730,7 +1730,7 @@
   } =>#t235;
   core::Map<core::String*, core::List<core::int*>*>* map40 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t237 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t238 = :sync-for-iterator.{core::Iterator::current};
@@ -1741,7 +1741,7 @@
   } =>#t237;
   core::List<core::List<core::int*>*>* list41 = block {
     final core::List<core::List<core::int*>*>* #t239 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t240 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t241 = #t240.{core::Set::add}(<core::int*>[]) in #t240).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t242 = :sync-for-iterator.{core::Iterator::current};
@@ -1751,7 +1751,7 @@
   } =>#t239;
   core::Set<core::List<core::int*>*>* set41 = block {
     final core::Set<core::List<core::int*>*>* #t243 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(let final core::Set<core::List<core::int*>*>* #t244 = col::LinkedHashSet::•<core::List<core::int*>*>() in let final core::bool* #t245 = #t244.{core::Set::add}(<core::int*>[]) in #t244).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t246 = :sync-for-iterator.{core::Iterator::current};
@@ -1762,8 +1762,8 @@
   } =>#t243;
   core::List<core::List<core::int*>*>* list42 = block {
     final core::List<core::List<core::int*>*>* #t247 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t248 = :sync-for-iterator.{core::Iterator::current};
@@ -1773,8 +1773,8 @@
   } =>#t247;
   core::Set<core::List<core::int*>*>* set42 = block {
     final core::Set<core::List<core::int*>*>* #t249 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t250 = :sync-for-iterator.{core::Iterator::current};
@@ -1785,8 +1785,8 @@
   } =>#t249;
   core::Map<core::String*, core::List<core::int*>*>* map42 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t251 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t252 = :sync-for-iterator.{core::Iterator::current};
@@ -1797,7 +1797,7 @@
   } =>#t251;
   core::List<core::int*>* list50 = block {
     final core::List<core::int*>* #t253 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t254 = :sync-for-iterator.{core::Iterator::current};
@@ -1807,7 +1807,7 @@
   } =>#t253;
   core::Set<core::int*>* set50 = block {
     final core::Set<core::int*>* #t255 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t256 = :sync-for-iterator.{core::Iterator::current};
@@ -1818,7 +1818,7 @@
   } =>#t255;
   core::Map<core::String*, core::int*>* map50 = block {
     final core::Map<core::String*, core::int*>* #t257 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(<core::String*, core::int*>{}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::int*>* #t258 = :sync-for-iterator.{core::Iterator::current};
@@ -1829,7 +1829,7 @@
   } =>#t257;
   core::List<core::int*>* list51 = block {
     final core::List<core::int*>* #t259 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t260 = col::LinkedHashSet::•<core::int*>() in #t260).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t261 = :sync-for-iterator.{core::Iterator::current};
@@ -1839,7 +1839,7 @@
   } =>#t259;
   core::Set<core::int*>* set51 = block {
     final core::Set<core::int*>* #t262 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(let final core::Set<core::int*>* #t263 = col::LinkedHashSet::•<core::int*>() in #t263).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::int* #t264 = :sync-for-iterator.{core::Iterator::current};
@@ -1850,8 +1850,8 @@
   } =>#t262;
   core::List<core::int*>* list52 = block {
     final core::List<core::int*>* #t265 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t266 = :sync-for-iterator.{core::Iterator::current};
@@ -1861,8 +1861,8 @@
   } =>#t265;
   core::Set<core::int*>* set52 = block {
     final core::Set<core::int*>* #t267 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::int* #t268 = :sync-for-iterator.{core::Iterator::current};
@@ -1873,7 +1873,7 @@
   } =>#t267;
   core::List<core::List<core::int*>*>* list60 = block {
     final core::List<core::List<core::int*>*>* #t269 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t270 = :sync-for-iterator.{core::Iterator::current};
@@ -1883,7 +1883,7 @@
   } =>#t269;
   core::Set<core::List<core::int*>*>* set60 = block {
     final core::Set<core::List<core::int*>*>* #t271 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::List<core::int*>* #t272 = :sync-for-iterator.{core::Iterator::current};
@@ -1894,7 +1894,7 @@
   } =>#t271;
   core::Map<core::String*, core::List<core::int*>*>* map60 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t273 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
       core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<core::String*, core::List<core::int*>*>* #t274 = :sync-for-iterator.{core::Iterator::current};
@@ -1905,8 +1905,8 @@
   } =>#t273;
   core::List<core::List<core::int*>*>* list61 = block {
     final core::List<core::List<core::int*>*>* #t275 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t276 = :sync-for-iterator.{core::Iterator::current};
@@ -1916,8 +1916,8 @@
   } =>#t275;
   core::Set<core::List<core::int*>*>* set61 = block {
     final core::Set<core::List<core::int*>*>* #t277 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::List<core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::List<core::int*>*>*>(<core::List<core::int*>*>[<core::int*>[]]).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::List<core::int*>* #t278 = :sync-for-iterator.{core::Iterator::current};
@@ -1928,8 +1928,8 @@
   } =>#t277;
   core::Map<core::String*, core::List<core::int*>*>* map61 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t279 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::List<core::int*>*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::List<core::int*>*>*>*>(<core::String*, core::List<core::int*>*>{"bar": <core::int*>[]}.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::List<core::int*>*>* #t280 = :sync-for-iterator.{core::Iterator::current};
@@ -1940,53 +1940,53 @@
   } =>#t279;
   core::List<core::List<core::int*>*>* list70 = block {
     final core::List<core::List<core::int*>*>* #t281 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t281.{core::List::add}(<core::int*>[]);
   } =>#t281;
   core::Set<core::List<core::int*>*>* set70 = block {
     final core::Set<core::List<core::int*>*>* #t282 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t282.{core::Set::add}(<core::int*>[]);
     #t282.{core::Set::add}(null);
   } =>#t282;
   core::Map<core::String*, core::List<core::int*>*>* map70 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t283 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
       #t283.{core::Map::[]=}("bar", <core::int*>[]);
     #t283.{core::Map::[]=}("baz", null);
   } =>#t283;
   core::List<core::List<core::int*>*>* list71 = block {
     final core::List<core::List<core::int*>*>* #t284 = <core::List<core::int*>*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t284.{core::List::add}(<core::int*>[]);
   } =>#t284;
   core::Set<core::List<core::int*>*>* set71 = block {
     final core::Set<core::List<core::int*>*>* #t285 = col::LinkedHashSet::•<core::List<core::int*>*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t285.{core::Set::add}(<core::int*>[]);
     #t285.{core::Set::add}(null);
   } =>#t285;
   core::Map<core::String*, core::List<core::int*>*>* map71 = block {
     final core::Map<core::String*, core::List<core::int*>*>* #t286 = <core::String*, core::List<core::int*>*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t286.{core::Map::[]=}("bar", <core::int*>[]);
     #t286.{core::Map::[]=}("baz", null);
   } =>#t286;
   core::List<core::num*>* list80 = block {
     final core::List<core::num*>* #t287 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t287.{core::List::add}(42);
       else
         #t287.{core::List::add}(3.14);
   } =>#t287;
   core::Set<core::num*>* set80 = block {
     final core::Set<core::num*>* #t288 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t288.{core::Set::add}(42);
       else
         #t288.{core::Set::add}(3.14);
@@ -1994,8 +1994,8 @@
   } =>#t288;
   core::Map<core::String*, core::num*>* map80 = block {
     final core::Map<core::String*, core::num*>* #t289 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t289.{core::Map::[]=}("bar", 42);
       else
         #t289.{core::Map::[]=}("bar", 3.14);
@@ -2003,8 +2003,8 @@
   } =>#t289;
   core::List<core::num*>* list81 = block {
     final core::List<core::num*>* #t290 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::num* #t291 = :sync-for-iterator.{core::Iterator::current};
@@ -2021,8 +2021,8 @@
   } =>#t290;
   core::Set<core::num*>* set81 = block {
     final core::Set<core::num*>* #t293 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::num* #t294 = :sync-for-iterator.{core::Iterator::current};
@@ -2040,8 +2040,8 @@
   } =>#t293;
   core::Map<core::String*, core::num*>* map81 = block {
     final core::Map<core::String*, core::num*>* #t296 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapStringInt.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::num*>* #t297 = :sync-for-iterator.{core::Iterator::current};
@@ -2059,8 +2059,8 @@
   } =>#t296;
   core::List<dynamic>* list82 = block {
     final core::List<dynamic>* #t299 = <dynamic>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t300 = :sync-for-iterator.{core::Iterator::current};
@@ -2068,7 +2068,7 @@
         }
       }
       else {
-        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t301 = :sync-for-iterator.{core::Iterator::current};
           #t299.{core::List::add}(#t301);
@@ -2077,8 +2077,8 @@
   } =>#t299;
   core::Set<dynamic>* set82 = block {
     final core::Set<dynamic>* #t302 = col::LinkedHashSet::•<dynamic>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t303 = :sync-for-iterator.{core::Iterator::current};
@@ -2086,7 +2086,7 @@
         }
       }
       else {
-        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t304 = :sync-for-iterator.{core::Iterator::current};
           #t302.{core::Set::add}(#t304);
@@ -2096,8 +2096,8 @@
   } =>#t302;
   core::Map<dynamic, dynamic>* map82 = block {
     final core::Map<dynamic, dynamic>* #t305 = <dynamic, dynamic>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapStringInt.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<dynamic, dynamic>* #t306 = :sync-for-iterator.{core::Iterator::current};
@@ -2105,7 +2105,7 @@
         }
       }
       else {
-        core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+        core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<dynamic, dynamic>* #t307 = :sync-for-iterator.{core::Iterator::current};
           #t305.{core::Map::[]=}(#t307.{core::MapEntry::key}, #t307.{core::MapEntry::value});
@@ -2115,8 +2115,8 @@
   } =>#t305;
   core::List<core::num*>* list83 = block {
     final core::List<core::num*>* #t308 = <core::num*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*)
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
         #t308.{core::List::add}(42);
       else {
         core::Iterator<core::double*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::double*>*>(listDouble).{core::Iterable::iterator};
@@ -2128,8 +2128,8 @@
   } =>#t308;
   core::Set<core::num*>* set83 = block {
     final core::Set<core::num*>* #t310 = col::LinkedHashSet::•<core::num*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(listInt).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::num* #t311 = :sync-for-iterator.{core::Iterator::current};
@@ -2142,8 +2142,8 @@
   } =>#t310;
   core::Map<core::String*, core::num*>* map83 = block {
     final core::Map<core::String*, core::num*>* #t312 = <core::String*, core::num*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      if(self::oracle<dynamic>() as{TypeError} core::bool*) {
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*) {
         core::Iterator<core::MapEntry<core::String*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::String*, core::int*>*>*>(mapStringInt.{core::Map::entries}).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final core::MapEntry<core::String*, core::num*>* #t313 = :sync-for-iterator.{core::Iterator::current};
@@ -2156,25 +2156,25 @@
   } =>#t312;
   core::List<core::int*>* list90 = block {
     final core::List<core::int*>* #t314 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t314.{core::List::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t314.{core::List::add}(dynVar as{TypeError,ForDynamic} core::int*);
   } =>#t314;
   core::Set<core::int*>* set90 = block {
     final core::Set<core::int*>* #t315 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t315.{core::Set::add}(dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t315.{core::Set::add}(dynVar as{TypeError,ForDynamic} core::int*);
     #t315.{core::Set::add}(null);
   } =>#t315;
   core::Map<core::String*, core::int*>* map90 = block {
     final core::Map<core::String*, core::int*>* #t316 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-      #t316.{core::Map::[]=}("bar", dynVar as{TypeError} core::int*);
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+      #t316.{core::Map::[]=}("bar", dynVar as{TypeError,ForDynamic} core::int*);
     #t316.{core::Map::[]=}("baz", null);
   } =>#t316;
   core::List<core::int*>* list91 = block {
     final core::List<core::int*>* #t317 = <core::int*>[];
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t318 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -2186,8 +2186,8 @@
   } =>#t317;
   core::Set<core::int*>* set91 = block {
     final core::Set<core::int*>* #t320 = col::LinkedHashSet::•<core::int*>();
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t321 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -2200,8 +2200,8 @@
   } =>#t320;
   core::Map<core::String*, core::int*>* map91 = block {
     final core::Map<core::String*, core::int*>* #t323 = <core::String*, core::int*>{};
-    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+    for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t324 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -2215,17 +2215,17 @@
   } =>#t323;
   core::List<core::int*>* list100 = block {
     final core::List<core::int*>* #t327 = <core::int*>[];
-    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t328 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t327.{core::List::add}(42);
   } =>#t327;
   core::Set<core::int*>* set100 = block {
     final core::Set<core::int*>* #t329 = col::LinkedHashSet::•<core::int*>();
-    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t330 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t329.{core::Set::add}(42);
   } =>#t329;
   core::Map<core::String*, core::int*>* map100 = block {
     final core::Map<core::String*, core::int*>* #t331 = <core::String*, core::int*>{};
-    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; index = index.{core::num::+}(1))
+    for (final core::int* #t332 = index = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; index = index.{core::num::+}(1))
       #t331.{core::Map::[]=}("bar", 42);
   } =>#t331;
   core::List<core::int*>* list110 = block {
@@ -2263,20 +2263,20 @@
   core::List<core::int*>* list120 = block {
     final core::List<core::int*>* #t336 = <core::int*>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         dynamic i = :sync-for-iterator.{core::Iterator::current};
-        #t336.{core::List::add}(i as{TypeError} core::int*);
+        #t336.{core::List::add}(i as{TypeError,ForDynamic} core::int*);
       }
     }
   } =>#t336;
   core::Set<core::int*>* set120 = block {
     final core::Set<core::int*>* #t337 = col::LinkedHashSet::•<core::int*>();
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         dynamic i = :sync-for-iterator.{core::Iterator::current};
-        #t337.{core::Set::add}(i as{TypeError} core::int*);
+        #t337.{core::Set::add}(i as{TypeError,ForDynamic} core::int*);
       }
     }
     #t337.{core::Set::add}(null);
@@ -2284,10 +2284,10 @@
   core::Map<core::String*, core::int*>* map120 = block {
     final core::Map<core::String*, core::int*>* #t338 = <core::String*, core::int*>{};
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         dynamic i = :sync-for-iterator.{core::Iterator::current};
-        #t338.{core::Map::[]=}("bar", i as{TypeError} core::int*);
+        #t338.{core::Map::[]=}("bar", i as{TypeError,ForDynamic} core::int*);
       }
     }
     #t338.{core::Map::[]=}("baz", null);
@@ -2326,14 +2326,14 @@
       {
         block {
           final core::List<core::int*>* #t342 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t342.{core::List::add}(let final<BottomType> #t343 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:212:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) \"bar\"];
                                             ^" in "bar" as{TypeError} core::int*);
         } =>#t342;
         block {
           final core::Set<core::int*>* #t344 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t344.{core::Set::add}(let final<BottomType> #t345 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:213:45: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\", null};
                                             ^" in "bar" as{TypeError} core::int*);
@@ -2341,7 +2341,7 @@
         } =>#t344;
         block {
           final core::Map<core::int*, core::int*>* #t346 = <core::int*, core::int*>{};
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t346.{core::Map::[]=}(let final<BottomType> #t347 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:214:50: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) \"bar\": \"bar\", \"baz\": null};
                                                  ^" in "bar" as{TypeError} core::int*, let final<BottomType> #t348 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:214:57: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -2353,7 +2353,7 @@
         } =>#t346;
         block {
           final core::List<core::int*>* #t350 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
             core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t351 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:215:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"]];
                                                 ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -2365,7 +2365,7 @@
         } =>#t350;
         block {
           final core::Set<core::int*>* #t353 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
             core::Iterator<core::int*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::int*>*>(<core::int*>[let final<BottomType> #t354 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:216:49: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...[\"bar\"], null};
                                                 ^" in "bar" as{TypeError} core::int*]).{core::Iterable::iterator};
@@ -2378,7 +2378,7 @@
         } =>#t353;
         block {
           final core::Map<core::int*, core::int*>* #t356 = <core::int*, core::int*>{};
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
             core::Iterator<core::MapEntry<core::int*, core::int*>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<core::int*, core::int*>*>*>(<core::int*, core::int*>{let final<BottomType> #t357 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:217:54: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   <int, int>{for (int i = 0; oracle(\"foo\"); i++) ...{\"bar\": \"bar\"}, \"baz\": null};
                                                      ^" in "bar" as{TypeError} core::int*: let final<BottomType> #t358 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:217:61: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
@@ -2395,7 +2395,7 @@
         } =>#t356;
         block {
           final core::List<core::int*>* #t361 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t361.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:218:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) ...map];
@@ -2403,7 +2403,7 @@
         } =>#t361;
         block {
           final core::Set<core::int*>* #t362 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
             #t362.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:219:48: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) ...map, null};
@@ -2419,8 +2419,8 @@
                                                     ^": null};
         block {
           final core::List<core::String*>* #t363 = <core::String*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t363.{core::List::add}(let final<BottomType> #t364 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:221:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14];
                                                              ^" in 42 as{TypeError} core::String*);
@@ -2431,8 +2431,8 @@
         } =>#t363;
         block {
           final core::Set<core::String*>* #t366 = col::LinkedHashSet::•<core::String*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t366.{core::Set::add}(let final<BottomType> #t367 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:222:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) 42 else 3.14, null};
                                                              ^" in 42 as{TypeError} core::String*);
@@ -2444,8 +2444,8 @@
         } =>#t366;
         block {
           final core::Map<core::String*, core::String*>* #t369 = <core::String*, core::String*>{};
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t369.{core::Map::[]=}("bar", let final<BottomType> #t370 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:223:77: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   <String, String>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) \"bar\": 42 else \"bar\": 3.14, \"baz\": null};
                                                                             ^" in 42 as{TypeError} core::String*);
@@ -2457,8 +2457,8 @@
         } =>#t369;
         block {
           final core::List<core::int*>* #t372 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t372.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:224:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>[for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42];
@@ -2468,8 +2468,8 @@
         } =>#t372;
         block {
           final core::Set<core::int*>* #t373 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t373.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:225:62: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
  - 'Map' is from 'dart:core'.
   <int>{for (int i = 0; oracle(\"foo\"); i++) if (oracle()) ...map else 42, null};
@@ -2487,8 +2487,8 @@
                                                                      ^": null};
         block {
           final core::List<core::int*>* #t374 = <core::int*>[];
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t374.{core::List::add}(42);
             else
               #t374.{core::List::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:227:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
@@ -2498,8 +2498,8 @@
         } =>#t374;
         block {
           final core::Set<core::int*>* #t375 = col::LinkedHashSet::•<core::int*>();
-          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError} core::bool*; i = i.{core::num::+}(1))
-            if(self::oracle<dynamic>() as{TypeError} core::bool*)
+          for (core::int* i = 0; self::oracle<core::String*>("foo") as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1))
+            if(self::oracle<dynamic>() as{TypeError,ForDynamic} core::bool*)
               #t375.{core::Set::add}(42);
             else
               #t375.{core::Set::add}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/control_flow_collection_inference.dart:228:70: Error: Unexpected type 'Map<int, int>' of a spread.  Expected 'dynamic' or an Iterable.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.strong.expect
index d794499..4a73a4f 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.strong.expect
@@ -33,7 +33,7 @@
   fooNum.{self::Foo::withCallback}((core::num* x) → core::Null? {});
   fooNum.{self::Foo::mutableField} = 3;
   fooNum.{self::Foo::mutableField} = 2.5;
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(3);
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(2.5);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(3);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(2.5);
   fooNum.{self::Foo::mutableCallbackField} = (core::num* x) → core::Null? {};
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.strong.transformed.expect
index d794499..4a73a4f 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.strong.transformed.expect
@@ -33,7 +33,7 @@
   fooNum.{self::Foo::withCallback}((core::num* x) → core::Null? {});
   fooNum.{self::Foo::mutableField} = 3;
   fooNum.{self::Foo::mutableField} = 2.5;
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(3);
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(2.5);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(3);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(2.5);
   fooNum.{self::Foo::mutableCallbackField} = (core::num* x) → core::Null? {};
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.weak.expect
index d794499..4a73a4f 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.weak.expect
@@ -33,7 +33,7 @@
   fooNum.{self::Foo::withCallback}((core::num* x) → core::Null? {});
   fooNum.{self::Foo::mutableField} = 3;
   fooNum.{self::Foo::mutableField} = 2.5;
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(3);
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(2.5);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(3);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(2.5);
   fooNum.{self::Foo::mutableCallbackField} = (core::num* x) → core::Null? {};
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.weak.transformed.expect
index d794499..4a73a4f 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/covariant_generic.dart.weak.transformed.expect
@@ -33,7 +33,7 @@
   fooNum.{self::Foo::withCallback}((core::num* x) → core::Null? {});
   fooNum.{self::Foo::mutableField} = 3;
   fooNum.{self::Foo::mutableField} = 2.5;
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(3);
-  (fooNum.{self::Foo::mutableCallbackField} as{TypeError} (core::num*) →* void).call(2.5);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(3);
+  (fooNum.{self::Foo::mutableCallbackField} as{TypeError,CovarianceCheck} (core::num*) →* void).call(2.5);
   fooNum.{self::Foo::mutableCallbackField} = (core::num* x) → core::Null? {};
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.strong.expect
index 0b20eef..6c22e73 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.strong.expect
@@ -59,11 +59,11 @@
       print(\"Hello, World!\") +
       ^" in core::print("Hello, World!")).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:16:7: Error: Method not found: 'z'.
       z(\"Hello, World!\") +
-      ^" as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:17:7: Error: Getter not found: 'z'.
+      ^" as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:17:7: Error: Getter not found: 'z'.
       z.print(\"Hello, World!\") +
-      ^".print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:18:7: Error: Getter not found: 'y'.
+      ^".print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:18:7: Error: Getter not found: 'y'.
       y.z.print(\"Hello, World!\") +
-      ^".z.print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:19:7: Error: Getter not found: 'x'.
+      ^".z.print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:19:7: Error: Getter not found: 'x'.
       x.y.z.print(\"Hello, World!\");
-      ^".y.z.print("Hello, World!") as{TypeError} core::num*);
+      ^".y.z.print("Hello, World!") as{TypeError,ForDynamic} core::num*);
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.strong.transformed.expect
index 0b20eef..6c22e73 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.strong.transformed.expect
@@ -59,11 +59,11 @@
       print(\"Hello, World!\") +
       ^" in core::print("Hello, World!")).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:16:7: Error: Method not found: 'z'.
       z(\"Hello, World!\") +
-      ^" as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:17:7: Error: Getter not found: 'z'.
+      ^" as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:17:7: Error: Getter not found: 'z'.
       z.print(\"Hello, World!\") +
-      ^".print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:18:7: Error: Getter not found: 'y'.
+      ^".print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:18:7: Error: Getter not found: 'y'.
       y.z.print(\"Hello, World!\") +
-      ^".z.print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:19:7: Error: Getter not found: 'x'.
+      ^".z.print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:19:7: Error: Getter not found: 'x'.
       x.y.z.print(\"Hello, World!\");
-      ^".y.z.print("Hello, World!") as{TypeError} core::num*);
+      ^".y.z.print("Hello, World!") as{TypeError,ForDynamic} core::num*);
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.weak.expect
index 0b20eef..6c22e73 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.weak.expect
@@ -59,11 +59,11 @@
       print(\"Hello, World!\") +
       ^" in core::print("Hello, World!")).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:16:7: Error: Method not found: 'z'.
       z(\"Hello, World!\") +
-      ^" as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:17:7: Error: Getter not found: 'z'.
+      ^" as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:17:7: Error: Getter not found: 'z'.
       z.print(\"Hello, World!\") +
-      ^".print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:18:7: Error: Getter not found: 'y'.
+      ^".print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:18:7: Error: Getter not found: 'y'.
       y.z.print(\"Hello, World!\") +
-      ^".z.print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:19:7: Error: Getter not found: 'x'.
+      ^".z.print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:19:7: Error: Getter not found: 'x'.
       x.y.z.print(\"Hello, World!\");
-      ^".y.z.print("Hello, World!") as{TypeError} core::num*);
+      ^".y.z.print("Hello, World!") as{TypeError,ForDynamic} core::num*);
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.weak.transformed.expect
index 0b20eef..6c22e73 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart.weak.transformed.expect
@@ -59,11 +59,11 @@
       print(\"Hello, World!\") +
       ^" in core::print("Hello, World!")).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:16:7: Error: Method not found: 'z'.
       z(\"Hello, World!\") +
-      ^" as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:17:7: Error: Getter not found: 'z'.
+      ^" as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:17:7: Error: Getter not found: 'z'.
       z.print(\"Hello, World!\") +
-      ^".print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:18:7: Error: Getter not found: 'y'.
+      ^".print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:18:7: Error: Getter not found: 'y'.
       y.z.print(\"Hello, World!\") +
-      ^".z.print("Hello, World!") as{TypeError} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:19:7: Error: Getter not found: 'x'.
+      ^".z.print("Hello, World!") as{TypeError,ForDynamic} core::num*).{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/invocations.dart:19:7: Error: Getter not found: 'x'.
       x.y.z.print(\"Hello, World!\");
-      ^".y.z.print("Hello, World!") as{TypeError} core::num*);
+      ^".y.z.print("Hello, World!") as{TypeError,ForDynamic} core::num*);
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.strong.expect
index d3cbeba..d362108 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.strong.expect
@@ -56,7 +56,7 @@
     if(t is self::B*) {
       core::List<self::Class::T*>* ys = <self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}];
       alias = ys;
-      self::xs = alias as{TypeError} core::List<self::B*>*;
+      self::xs = alias as{TypeError,ForDynamic} core::List<self::B*>*;
     }
   }
   method method2b(generic-covariant-impl self::Class::T* t) → void {
@@ -64,7 +64,7 @@
     if(t is self::B*) {
       core::List<core::List<self::Class::T*>*>* yss = <core::List<self::Class::T*>*>[<self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}]];
       alias = yss;
-      self::xss = alias as{TypeError} core::List<core::List<self::B*>*>*;
+      self::xss = alias as{TypeError,ForDynamic} core::List<core::List<self::B*>*>*;
     }
   }
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.strong.transformed.expect
index d3cbeba..d362108 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.strong.transformed.expect
@@ -56,7 +56,7 @@
     if(t is self::B*) {
       core::List<self::Class::T*>* ys = <self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}];
       alias = ys;
-      self::xs = alias as{TypeError} core::List<self::B*>*;
+      self::xs = alias as{TypeError,ForDynamic} core::List<self::B*>*;
     }
   }
   method method2b(generic-covariant-impl self::Class::T* t) → void {
@@ -64,7 +64,7 @@
     if(t is self::B*) {
       core::List<core::List<self::Class::T*>*>* yss = <core::List<self::Class::T*>*>[<self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}]];
       alias = yss;
-      self::xss = alias as{TypeError} core::List<core::List<self::B*>*>*;
+      self::xss = alias as{TypeError,ForDynamic} core::List<core::List<self::B*>*>*;
     }
   }
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.weak.expect
index d3cbeba..d362108 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.weak.expect
@@ -56,7 +56,7 @@
     if(t is self::B*) {
       core::List<self::Class::T*>* ys = <self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}];
       alias = ys;
-      self::xs = alias as{TypeError} core::List<self::B*>*;
+      self::xs = alias as{TypeError,ForDynamic} core::List<self::B*>*;
     }
   }
   method method2b(generic-covariant-impl self::Class::T* t) → void {
@@ -64,7 +64,7 @@
     if(t is self::B*) {
       core::List<core::List<self::Class::T*>*>* yss = <core::List<self::Class::T*>*>[<self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}]];
       alias = yss;
-      self::xss = alias as{TypeError} core::List<core::List<self::B*>*>*;
+      self::xss = alias as{TypeError,ForDynamic} core::List<core::List<self::B*>*>*;
     }
   }
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.weak.transformed.expect
index d3cbeba..d362108 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/issue39344.dart.weak.transformed.expect
@@ -56,7 +56,7 @@
     if(t is self::B*) {
       core::List<self::Class::T*>* ys = <self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}];
       alias = ys;
-      self::xs = alias as{TypeError} core::List<self::B*>*;
+      self::xs = alias as{TypeError,ForDynamic} core::List<self::B*>*;
     }
   }
   method method2b(generic-covariant-impl self::Class::T* t) → void {
@@ -64,7 +64,7 @@
     if(t is self::B*) {
       core::List<core::List<self::Class::T*>*>* yss = <core::List<self::Class::T*>*>[<self::Class::T*>[t{self::Class::T* & self::B* /* '*' & '*' = '*' */}]];
       alias = yss;
-      self::xss = alias as{TypeError} core::List<core::List<self::B*>*>*;
+      self::xss = alias as{TypeError,ForDynamic} core::List<core::List<self::B*>*>*;
     }
   }
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.strong.expect
index a68bf96..98ba00e 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.strong.expect
@@ -67,7 +67,7 @@
  - 'EmptyClass' is from 'pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '+'.
 var missingBinary = classWithProperty.property += 2;
-                                               ^" as{TypeError} self::EmptyClass*;
+                                               ^" as{TypeError,ForDynamic} self::EmptyClass*;
 static field dynamic missingIndexGet = let final self::ClassWithIndexSet* #t2 = self::classWithIndexSet in let final core::int* #t3 = 0 in let final dynamic #t4 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart:30:40: Error: The method '[]' isn't defined for the class 'ClassWithIndexSet'.
  - 'ClassWithIndexSet' is from 'pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '[]'.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.strong.transformed.expect
index a68bf96..98ba00e 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.strong.transformed.expect
@@ -67,7 +67,7 @@
  - 'EmptyClass' is from 'pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '+'.
 var missingBinary = classWithProperty.property += 2;
-                                               ^" as{TypeError} self::EmptyClass*;
+                                               ^" as{TypeError,ForDynamic} self::EmptyClass*;
 static field dynamic missingIndexGet = let final self::ClassWithIndexSet* #t2 = self::classWithIndexSet in let final core::int* #t3 = 0 in let final dynamic #t4 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart:30:40: Error: The method '[]' isn't defined for the class 'ClassWithIndexSet'.
  - 'ClassWithIndexSet' is from 'pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '[]'.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.weak.expect
index a68bf96..98ba00e 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.weak.expect
@@ -67,7 +67,7 @@
  - 'EmptyClass' is from 'pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '+'.
 var missingBinary = classWithProperty.property += 2;
-                                               ^" as{TypeError} self::EmptyClass*;
+                                               ^" as{TypeError,ForDynamic} self::EmptyClass*;
 static field dynamic missingIndexGet = let final self::ClassWithIndexSet* #t2 = self::classWithIndexSet in let final core::int* #t3 = 0 in let final dynamic #t4 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart:30:40: Error: The method '[]' isn't defined for the class 'ClassWithIndexSet'.
  - 'ClassWithIndexSet' is from 'pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '[]'.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.weak.transformed.expect
index a68bf96..98ba00e 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart.weak.transformed.expect
@@ -67,7 +67,7 @@
  - 'EmptyClass' is from 'pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '+'.
 var missingBinary = classWithProperty.property += 2;
-                                               ^" as{TypeError} self::EmptyClass*;
+                                               ^" as{TypeError,ForDynamic} self::EmptyClass*;
 static field dynamic missingIndexGet = let final self::ClassWithIndexSet* #t2 = self::classWithIndexSet in let final core::int* #t3 = 0 in let final dynamic #t4 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart:30:40: Error: The method '[]' isn't defined for the class 'ClassWithIndexSet'.
  - 'ClassWithIndexSet' is from 'pkg/front_end/testcases/general_nnbd_opt_out/missing_toplevel.dart'.
 Try correcting the name to the name of an existing method, or defining a method named '[]'.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.strong.expect
index cca2f0d..ea78a78 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.strong.expect
@@ -127,7 +127,7 @@
   {
     self::V* V = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart:49:7: Error: Can't declare 'V' because it was already used in this scope.
     V V;
-      ^" as{TypeError} self::V*;
+      ^" as{TypeError,ForDynamic} self::V*;
   }
   {
     <T extends core::Object* = dynamic>() →* core::Null? x = let final dynamic #t3 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart:54:13: Error: 'T' is already declared in this scope.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.strong.transformed.expect
index cca2f0d..ea78a78 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.strong.transformed.expect
@@ -127,7 +127,7 @@
   {
     self::V* V = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart:49:7: Error: Can't declare 'V' because it was already used in this scope.
     V V;
-      ^" as{TypeError} self::V*;
+      ^" as{TypeError,ForDynamic} self::V*;
   }
   {
     <T extends core::Object* = dynamic>() →* core::Null? x = let final dynamic #t3 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart:54:13: Error: 'T' is already declared in this scope.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.weak.expect
index cca2f0d..ea78a78 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.weak.expect
@@ -127,7 +127,7 @@
   {
     self::V* V = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart:49:7: Error: Can't declare 'V' because it was already used in this scope.
     V V;
-      ^" as{TypeError} self::V*;
+      ^" as{TypeError,ForDynamic} self::V*;
   }
   {
     <T extends core::Object* = dynamic>() →* core::Null? x = let final dynamic #t3 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart:54:13: Error: 'T' is already declared in this scope.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.weak.transformed.expect
index cca2f0d..ea78a78 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart.weak.transformed.expect
@@ -127,7 +127,7 @@
   {
     self::V* V = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart:49:7: Error: Can't declare 'V' because it was already used in this scope.
     V V;
-      ^" as{TypeError} self::V*;
+      ^" as{TypeError,ForDynamic} self::V*;
   }
   {
     <T extends core::Object* = dynamic>() →* core::Null? x = let final dynamic #t3 = invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/named_function_scope.dart:54:13: Error: 'T' is already declared in this scope.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.outline.expect b/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.outline.expect
index ea56f3e..fa9a400 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.outline.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.outline.expect
@@ -9,7 +9,7 @@
   synthetic constructor •() → self::Foo*
     ;
   no-such-method-forwarder get /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x() → core::int*
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#_x, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} core::int*;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#_x, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x(core::int* value) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#_x=, 2, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.strong.expect
index 3fa5d56..b80b9e5 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.strong.expect
@@ -10,7 +10,7 @@
     : super core::Object::•()
     ;
   no-such-method-forwarder get /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x() → core::int*
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x(core::int* value) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.strong.transformed.expect
index 3fa5d56..b80b9e5 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.strong.transformed.expect
@@ -10,7 +10,7 @@
     : super core::Object::•()
     ;
   no-such-method-forwarder get /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x() → core::int*
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x(core::int* value) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.weak.expect
index 3fa5d56..b80b9e5 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.weak.expect
@@ -10,7 +10,7 @@
     : super core::Object::•()
     ;
   no-such-method-forwarder get /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x() → core::int*
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x(core::int* value) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.weak.transformed.expect
index 3fa5d56..b80b9e5 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/no_such_method_private_setter.dart.weak.transformed.expect
@@ -10,7 +10,7 @@
     : super core::Object::•()
     ;
   no-such-method-forwarder get /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x() → core::int*
-    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set /* from org-dartlang-testcase:///no_such_method_private_setter_lib.dart */ _x(core::int* value) → void
     return this.{core::Object::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.strong.expect
index 17ac3e7..6116ad1 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.strong.expect
@@ -147,14 +147,14 @@
   c.{self::C::field1};
   c.{self::C::field2};
   try {
-    c.{self::C::field3} as{TypeError} (core::num*) →* void;
+    c.{self::C::field3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::field4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -162,14 +162,14 @@
   }
   c.{self::C::field5};
   try {
-    c.{self::C::field6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::field6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::field7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -178,42 +178,42 @@
   c.{self::C::field8};
   c.{self::C::field9};
   try {
-    c.{self::C::field10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::field10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::field11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::field12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::field13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::field14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::field15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -222,14 +222,14 @@
   c.{self::C::getter1};
   c.{self::C::getter2};
   try {
-    c.{self::C::getter3} as{TypeError} (core::num*) →* void;
+    c.{self::C::getter3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::getter4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -237,14 +237,14 @@
   }
   c.{self::C::getter5};
   try {
-    c.{self::C::getter6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::getter6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::getter7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -253,42 +253,42 @@
   c.{self::C::getter8};
   c.{self::C::getter9};
   try {
-    c.{self::C::getter10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::getter10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::getter11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::getter12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::getter13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::getter14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::getter15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.strong.transformed.expect
index 17ac3e7..6116ad1 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.strong.transformed.expect
@@ -147,14 +147,14 @@
   c.{self::C::field1};
   c.{self::C::field2};
   try {
-    c.{self::C::field3} as{TypeError} (core::num*) →* void;
+    c.{self::C::field3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::field4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -162,14 +162,14 @@
   }
   c.{self::C::field5};
   try {
-    c.{self::C::field6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::field6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::field7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -178,42 +178,42 @@
   c.{self::C::field8};
   c.{self::C::field9};
   try {
-    c.{self::C::field10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::field10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::field11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::field12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::field13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::field14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::field15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -222,14 +222,14 @@
   c.{self::C::getter1};
   c.{self::C::getter2};
   try {
-    c.{self::C::getter3} as{TypeError} (core::num*) →* void;
+    c.{self::C::getter3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::getter4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -237,14 +237,14 @@
   }
   c.{self::C::getter5};
   try {
-    c.{self::C::getter6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::getter6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::getter7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -253,42 +253,42 @@
   c.{self::C::getter8};
   c.{self::C::getter9};
   try {
-    c.{self::C::getter10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::getter10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::getter11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::getter12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::getter13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::getter14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::getter15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.weak.expect
index 17ac3e7..6116ad1 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.weak.expect
@@ -147,14 +147,14 @@
   c.{self::C::field1};
   c.{self::C::field2};
   try {
-    c.{self::C::field3} as{TypeError} (core::num*) →* void;
+    c.{self::C::field3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::field4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -162,14 +162,14 @@
   }
   c.{self::C::field5};
   try {
-    c.{self::C::field6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::field6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::field7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -178,42 +178,42 @@
   c.{self::C::field8};
   c.{self::C::field9};
   try {
-    c.{self::C::field10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::field10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::field11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::field12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::field13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::field14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::field15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -222,14 +222,14 @@
   c.{self::C::getter1};
   c.{self::C::getter2};
   try {
-    c.{self::C::getter3} as{TypeError} (core::num*) →* void;
+    c.{self::C::getter3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::getter4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -237,14 +237,14 @@
   }
   c.{self::C::getter5};
   try {
-    c.{self::C::getter6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::getter6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::getter7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -253,42 +253,42 @@
   c.{self::C::getter8};
   c.{self::C::getter9};
   try {
-    c.{self::C::getter10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::getter10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::getter11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::getter12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::getter13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::getter14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::getter15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.weak.transformed.expect
index 17ac3e7..6116ad1 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/non_covariant_checks.dart.weak.transformed.expect
@@ -147,14 +147,14 @@
   c.{self::C::field1};
   c.{self::C::field2};
   try {
-    c.{self::C::field3} as{TypeError} (core::num*) →* void;
+    c.{self::C::field3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::field4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -162,14 +162,14 @@
   }
   c.{self::C::field5};
   try {
-    c.{self::C::field6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::field6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::field7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -178,42 +178,42 @@
   c.{self::C::field8};
   c.{self::C::field9};
   try {
-    c.{self::C::field10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::field10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::field11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::field12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::field13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::field14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::field15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::field15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -222,14 +222,14 @@
   c.{self::C::getter1};
   c.{self::C::getter2};
   try {
-    c.{self::C::getter3} as{TypeError} (core::num*) →* void;
+    c.{self::C::getter3} as{TypeError,CovarianceCheck} (core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter4} as{TypeError} (core::num*) →* core::num*;
+    c.{self::C::getter4} as{TypeError,CovarianceCheck} (core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -237,14 +237,14 @@
   }
   c.{self::C::getter5};
   try {
-    c.{self::C::getter6} as{TypeError} (() →* core::num*) →* void;
+    c.{self::C::getter6} as{TypeError,CovarianceCheck} (() →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter7} as{TypeError} (() →* core::num*) →* core::num*;
+    c.{self::C::getter7} as{TypeError,CovarianceCheck} (() →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
@@ -253,42 +253,42 @@
   c.{self::C::getter8};
   c.{self::C::getter9};
   try {
-    c.{self::C::getter10} as{TypeError} ((core::num*) →* core::num*) →* void;
+    c.{self::C::getter10} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter11} as{TypeError} ((core::num*) →* core::num*) →* core::num*;
+    c.{self::C::getter11} as{TypeError,CovarianceCheck} ((core::num*) →* core::num*) →* core::num*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter12} as{TypeError} <S extends core::num* = dynamic>() →* S*;
+    c.{self::C::getter12} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>() →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter13} as{TypeError} <S extends core::num* = dynamic>(S*) →* void;
+    c.{self::C::getter13} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter14} as{TypeError} <S extends core::num* = dynamic>(S*) →* S*;
+    c.{self::C::getter14} as{TypeError,CovarianceCheck} <S extends core::num* = dynamic>(S*) →* S*;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
     core::print(e);
   }
   try {
-    c.{self::C::getter15} as{TypeError} (<S extends core::num* = dynamic>() →* S*) →* void;
+    c.{self::C::getter15} as{TypeError,CovarianceCheck} (<S extends core::num* = dynamic>() →* S*) →* void;
     throw "TypeError expected";
   }
   on core::TypeError* catch(final core::TypeError* e) {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.strong.expect
index 18203ab..5d3f769 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.strong.expect
@@ -10,8 +10,8 @@
 static method main() → dynamic {
   dynamic o;
   if(false) {
-    for (final dynamic #t1 in (let final dynamic #t2 = o in #t2.{core::Object::==}(null) ?{dynamic} null : #t2.iterable) as{TypeError} core::Iterable<dynamic>*) {
-      self::Class* c = #t1 as{TypeError} self::Class*;
+    for (final dynamic #t1 in (let final dynamic #t2 = o in #t2.{core::Object::==}(null) ?{dynamic} null : #t2.iterable) as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
+      self::Class* c = #t1 as{TypeError,ForDynamic} self::Class*;
     }
   }
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.strong.transformed.expect
index f6157cd..eb4e616 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.strong.transformed.expect
@@ -12,11 +12,11 @@
   dynamic o;
   if(false) {
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((let final dynamic #t1 = o in #t1.{core::Object::==}(null) ?{dynamic} null : #t1.iterable) as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((let final dynamic #t1 = o in #t1.{core::Object::==}(null) ?{dynamic} null : #t1.iterable) as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t2 = :sync-for-iterator.{core::Iterator::current};
         {
-          self::Class* c = #t2 as{TypeError} self::Class*;
+          self::Class* c = #t2 as{TypeError,ForDynamic} self::Class*;
         }
       }
     }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.weak.expect
index 18203ab..5d3f769 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.weak.expect
@@ -10,8 +10,8 @@
 static method main() → dynamic {
   dynamic o;
   if(false) {
-    for (final dynamic #t1 in (let final dynamic #t2 = o in #t2.{core::Object::==}(null) ?{dynamic} null : #t2.iterable) as{TypeError} core::Iterable<dynamic>*) {
-      self::Class* c = #t1 as{TypeError} self::Class*;
+    for (final dynamic #t1 in (let final dynamic #t2 = o in #t2.{core::Object::==}(null) ?{dynamic} null : #t2.iterable) as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
+      self::Class* c = #t1 as{TypeError,ForDynamic} self::Class*;
     }
   }
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.weak.transformed.expect
index f6157cd..eb4e616 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/null_aware_for_in.dart.weak.transformed.expect
@@ -12,11 +12,11 @@
   dynamic o;
   if(false) {
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((let final dynamic #t1 = o in #t1.{core::Object::==}(null) ?{dynamic} null : #t1.iterable) as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((let final dynamic #t1 = o in #t1.{core::Object::==}(null) ?{dynamic} null : #t1.iterable) as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t2 = :sync-for-iterator.{core::Iterator::current};
         {
-          self::Class* c = #t2 as{TypeError} self::Class*;
+          self::Class* c = #t2 as{TypeError,ForDynamic} self::Class*;
         }
       }
     }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.strong.expect
index 18814f3..4bfac34 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.strong.expect
@@ -4,7 +4,7 @@
 
 static method f(core::List<dynamic>* x) → core::bool* {
   return x.{core::Iterable::expand}<dynamic>((dynamic y) → core::Iterable<dynamic>* {
-    return y.split(",") as{TypeError} core::Iterable<dynamic>*;
+    return y.split(",") as{TypeError,ForDynamic} core::Iterable<dynamic>*;
   }).{core::Iterable::any}((dynamic y) → core::bool* => y.{core::Object::==}("z"));
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.strong.transformed.expect
index 18814f3..4bfac34 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.strong.transformed.expect
@@ -4,7 +4,7 @@
 
 static method f(core::List<dynamic>* x) → core::bool* {
   return x.{core::Iterable::expand}<dynamic>((dynamic y) → core::Iterable<dynamic>* {
-    return y.split(",") as{TypeError} core::Iterable<dynamic>*;
+    return y.split(",") as{TypeError,ForDynamic} core::Iterable<dynamic>*;
   }).{core::Iterable::any}((dynamic y) → core::bool* => y.{core::Object::==}("z"));
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.weak.expect
index 18814f3..4bfac34 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.weak.expect
@@ -4,7 +4,7 @@
 
 static method f(core::List<dynamic>* x) → core::bool* {
   return x.{core::Iterable::expand}<dynamic>((dynamic y) → core::Iterable<dynamic>* {
-    return y.split(",") as{TypeError} core::Iterable<dynamic>*;
+    return y.split(",") as{TypeError,ForDynamic} core::Iterable<dynamic>*;
   }).{core::Iterable::any}((dynamic y) → core::bool* => y.{core::Object::==}("z"));
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.weak.transformed.expect
index 18814f3..4bfac34 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/return_with_unknown_type_in_context.dart.weak.transformed.expect
@@ -4,7 +4,7 @@
 
 static method f(core::List<dynamic>* x) → core::bool* {
   return x.{core::Iterable::expand}<dynamic>((dynamic y) → core::Iterable<dynamic>* {
-    return y.split(",") as{TypeError} core::Iterable<dynamic>*;
+    return y.split(",") as{TypeError,ForDynamic} core::Iterable<dynamic>*;
   }).{core::Iterable::any}((dynamic y) → core::bool* => y.{core::Object::==}("z"));
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.strong.expect
index cfeeadc..5ff3546 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.strong.expect
@@ -160,18 +160,18 @@
   } =>#t18;
   core::List<dynamic>* lhs21 = block {
     final core::List<dynamic>* #t20 = <dynamic>[];
-    for (final dynamic #t21 in (spread as dynamic) as{TypeError} core::Iterable<dynamic>*)
+    for (final dynamic #t21 in (spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*)
       #t20.{core::List::add}(#t21);
   } =>#t20;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t22 = col::LinkedHashSet::•<dynamic>();
-    for (final dynamic #t23 in (spread as dynamic) as{TypeError} core::Iterable<dynamic>*)
+    for (final dynamic #t23 in (spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*)
       #t22.{core::Set::add}(#t23);
     #t22.{core::Set::add}(42);
   } =>#t22;
   core::Map<dynamic, dynamic>* map21 = block {
     final core::Map<dynamic, dynamic>* #t24 = <dynamic, dynamic>{};
-    for (final core::MapEntry<dynamic, dynamic>* #t25 in ((mapSpread as dynamic) as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries})
+    for (final core::MapEntry<dynamic, dynamic>* #t25 in ((mapSpread as dynamic) as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries})
       #t24.{core::Map::[]=}(#t25.{core::MapEntry::key}, #t25.{core::MapEntry::value});
     #t24.{core::Map::[]=}("baz", 42);
   } =>#t24;
@@ -377,14 +377,14 @@
   } =>#t91;
   core::List<core::int*>* list110 = block {
     final core::List<core::int*>* #t95 = <core::int*>[];
-    for (final dynamic #t96 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    for (final dynamic #t96 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
       final core::int* #t97 = #t96 as{TypeError} core::int*;
       #t95.{core::List::add}(#t97);
     }
   } =>#t95;
   core::Map<core::num*, core::int*>* map110 = block {
     final core::Map<core::num*, core::int*>* #t98 = <core::num*, core::int*>{};
-    for (final core::MapEntry<dynamic, dynamic>* #t99 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
+    for (final core::MapEntry<dynamic, dynamic>* #t99 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
       final core::num* #t100 = #t99.{core::MapEntry::key} as{TypeError} core::num*;
       final core::int* #t101 = #t99.{core::MapEntry::value} as{TypeError} core::int*;
       #t98.{core::Map::[]=}(#t100, #t101);
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.strong.transformed.expect
index 1cfb2b0..db8baa1 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.strong.transformed.expect
@@ -208,7 +208,7 @@
   core::List<dynamic>* lhs21 = block {
     final core::List<dynamic>* #t20 = <dynamic>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t21 = :sync-for-iterator.{core::Iterator::current};
         #t20.{core::List::add}(#t21);
@@ -218,7 +218,7 @@
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t22 = col::LinkedHashSet::•<dynamic>();
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t23 = :sync-for-iterator.{core::Iterator::current};
         #t22.{core::Set::add}(#t23);
@@ -229,7 +229,7 @@
   core::Map<dynamic, dynamic>* map21 = block {
     final core::Map<dynamic, dynamic>* #t24 = <dynamic, dynamic>{};
     {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>(((mapSpread as dynamic) as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>(((mapSpread as dynamic) as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t25 = :sync-for-iterator.{core::Iterator::current};
         #t24.{core::Map::[]=}(#t25.{core::MapEntry::key}, #t25.{core::MapEntry::value});
@@ -554,7 +554,7 @@
   core::List<core::int*>* list110 = block {
     final core::List<core::int*>* #t95 = <core::int*>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t96 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -567,7 +567,7 @@
   core::Map<core::num*, core::int*>* map110 = block {
     final core::Map<core::num*, core::int*>* #t98 = <core::num*, core::int*>{};
     {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t99 = :sync-for-iterator.{core::Iterator::current};
         {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.expect
index cfeeadc..5ff3546 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.expect
@@ -160,18 +160,18 @@
   } =>#t18;
   core::List<dynamic>* lhs21 = block {
     final core::List<dynamic>* #t20 = <dynamic>[];
-    for (final dynamic #t21 in (spread as dynamic) as{TypeError} core::Iterable<dynamic>*)
+    for (final dynamic #t21 in (spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*)
       #t20.{core::List::add}(#t21);
   } =>#t20;
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t22 = col::LinkedHashSet::•<dynamic>();
-    for (final dynamic #t23 in (spread as dynamic) as{TypeError} core::Iterable<dynamic>*)
+    for (final dynamic #t23 in (spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*)
       #t22.{core::Set::add}(#t23);
     #t22.{core::Set::add}(42);
   } =>#t22;
   core::Map<dynamic, dynamic>* map21 = block {
     final core::Map<dynamic, dynamic>* #t24 = <dynamic, dynamic>{};
-    for (final core::MapEntry<dynamic, dynamic>* #t25 in ((mapSpread as dynamic) as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries})
+    for (final core::MapEntry<dynamic, dynamic>* #t25 in ((mapSpread as dynamic) as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries})
       #t24.{core::Map::[]=}(#t25.{core::MapEntry::key}, #t25.{core::MapEntry::value});
     #t24.{core::Map::[]=}("baz", 42);
   } =>#t24;
@@ -377,14 +377,14 @@
   } =>#t91;
   core::List<core::int*>* list110 = block {
     final core::List<core::int*>* #t95 = <core::int*>[];
-    for (final dynamic #t96 in dynVar as{TypeError} core::Iterable<dynamic>*) {
+    for (final dynamic #t96 in dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
       final core::int* #t97 = #t96 as{TypeError} core::int*;
       #t95.{core::List::add}(#t97);
     }
   } =>#t95;
   core::Map<core::num*, core::int*>* map110 = block {
     final core::Map<core::num*, core::int*>* #t98 = <core::num*, core::int*>{};
-    for (final core::MapEntry<dynamic, dynamic>* #t99 in (dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
+    for (final core::MapEntry<dynamic, dynamic>* #t99 in (dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}) {
       final core::num* #t100 = #t99.{core::MapEntry::key} as{TypeError} core::num*;
       final core::int* #t101 = #t99.{core::MapEntry::value} as{TypeError} core::int*;
       #t98.{core::Map::[]=}(#t100, #t101);
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.transformed.expect
index 1cfb2b0..db8baa1 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/spread_collection_inference.dart.weak.transformed.expect
@@ -208,7 +208,7 @@
   core::List<dynamic>* lhs21 = block {
     final core::List<dynamic>* #t20 = <dynamic>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t21 = :sync-for-iterator.{core::Iterator::current};
         #t20.{core::List::add}(#t21);
@@ -218,7 +218,7 @@
   core::Set<dynamic>* set21 = block {
     final core::Set<dynamic>* #t22 = col::LinkedHashSet::•<dynamic>();
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((spread as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t23 = :sync-for-iterator.{core::Iterator::current};
         #t22.{core::Set::add}(#t23);
@@ -229,7 +229,7 @@
   core::Map<dynamic, dynamic>* map21 = block {
     final core::Map<dynamic, dynamic>* #t24 = <dynamic, dynamic>{};
     {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>(((mapSpread as dynamic) as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>(((mapSpread as dynamic) as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t25 = :sync-for-iterator.{core::Iterator::current};
         #t24.{core::Map::[]=}(#t25.{core::MapEntry::key}, #t25.{core::MapEntry::value});
@@ -554,7 +554,7 @@
   core::List<core::int*>* list110 = block {
     final core::List<core::int*>* #t95 = <core::int*>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(dynVar as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t96 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -567,7 +567,7 @@
   core::Map<core::num*, core::int*>* map110 = block {
     final core::Map<core::num*, core::int*>* #t98 = <core::num*, core::int*>{};
     {
-      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
+      core::Iterator<core::MapEntry<dynamic, dynamic>*>* :sync-for-iterator = _in::unsafeCast<core::Iterable<core::MapEntry<dynamic, dynamic>*>*>((dynVar as{TypeError,ForDynamic} core::Map<dynamic, dynamic>*).{core::Map::entries}).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final core::MapEntry<dynamic, dynamic>* #t99 = :sync-for-iterator.{core::Iterator::current};
         {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.strong.expect
index 42e644b..688bc83 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.strong.expect
@@ -27,7 +27,7 @@
     return invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart:17:12: Error: Can't use 'super' as an expression.
 To delegate a constructor to a super constructor, put the super call as an initializer.
     return super(5);
-           ^" as{TypeError} core::int*;
+           ^" as{TypeError,ForDynamic} core::int*;
   }
 }
 static method main() → dynamic {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.strong.transformed.expect
index 42e644b..688bc83 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.strong.transformed.expect
@@ -27,7 +27,7 @@
     return invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart:17:12: Error: Can't use 'super' as an expression.
 To delegate a constructor to a super constructor, put the super call as an initializer.
     return super(5);
-           ^" as{TypeError} core::int*;
+           ^" as{TypeError,ForDynamic} core::int*;
   }
 }
 static method main() → dynamic {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.weak.expect
index 42e644b..688bc83 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.weak.expect
@@ -27,7 +27,7 @@
     return invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart:17:12: Error: Can't use 'super' as an expression.
 To delegate a constructor to a super constructor, put the super call as an initializer.
     return super(5);
-           ^" as{TypeError} core::int*;
+           ^" as{TypeError,ForDynamic} core::int*;
   }
 }
 static method main() → dynamic {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.weak.transformed.expect
index 42e644b..688bc83 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart.weak.transformed.expect
@@ -27,7 +27,7 @@
     return invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/super_call.dart:17:12: Error: Can't use 'super' as an expression.
 To delegate a constructor to a super constructor, put the super call as an initializer.
     return super(5);
-           ^" as{TypeError} core::int*;
+           ^" as{TypeError,ForDynamic} core::int*;
   }
 }
 static method main() → dynamic {
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.outline.expect b/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.outline.expect
index 2da773b..4f2eabf 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.outline.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.outline.expect
@@ -13,7 +13,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     ;
   no-such-method-forwarder method interfaceMethod() → dynamic
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} dynamic;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#interfaceMethod, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} dynamic;
 }
 class D extends self::C {
   synthetic constructor •() → self::D*
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.strong.expect
index 69a6257..f804c1f 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.strong.expect
@@ -15,7 +15,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     return "C";
   no-such-method-forwarder method interfaceMethod() → dynamic
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
 }
 class D extends self::C {
   synthetic constructor •() → self::D*
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.strong.transformed.expect
index 69a6257..f804c1f 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.strong.transformed.expect
@@ -15,7 +15,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     return "C";
   no-such-method-forwarder method interfaceMethod() → dynamic
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
 }
 class D extends self::C {
   synthetic constructor •() → self::D*
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.weak.expect
index 69a6257..f804c1f 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.weak.expect
@@ -15,7 +15,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     return "C";
   no-such-method-forwarder method interfaceMethod() → dynamic
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
 }
 class D extends self::C {
   synthetic constructor •() → self::D*
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.weak.transformed.expect
index 69a6257..f804c1f 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/super_nsm.dart.weak.transformed.expect
@@ -15,7 +15,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     return "C";
   no-such-method-forwarder method interfaceMethod() → dynamic
-    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::C::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
 }
 class D extends self::C {
   synthetic constructor •() → self::D*
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/type_variable_bound_access.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/type_variable_bound_access.dart.strong.expect
index 8e4c18f..ae89f63 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/type_variable_bound_access.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/type_variable_bound_access.dart.strong.expect
@@ -31,7 +31,7 @@
     return this.{self::NumClass::field1}.{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/type_variable_bound_access.dart:24:36: Error: The getter 'length' isn't defined for the class 'num'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'length'.
   num method2() => field1 + field2.length;
-                                   ^^^^^^" as{TypeError} core::num*);
+                                   ^^^^^^" as{TypeError,ForDynamic} core::num*);
 }
 static method main() → dynamic {
   new self::DynamicClass::•<core::num*, core::int*>(0.5, 2).{self::DynamicClass::method}();
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/type_variable_bound_access.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/type_variable_bound_access.dart.weak.expect
index 8e4c18f..ae89f63 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/type_variable_bound_access.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/type_variable_bound_access.dart.weak.expect
@@ -31,7 +31,7 @@
     return this.{self::NumClass::field1}.{core::num::+}(invalid-expression "pkg/front_end/testcases/general_nnbd_opt_out/type_variable_bound_access.dart:24:36: Error: The getter 'length' isn't defined for the class 'num'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'length'.
   num method2() => field1 + field2.length;
-                                   ^^^^^^" as{TypeError} core::num*);
+                                   ^^^^^^" as{TypeError,ForDynamic} core::num*);
 }
 static method main() → dynamic {
   new self::DynamicClass::•<core::num*, core::int*>(0.5, 2).{self::DynamicClass::method}();
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.strong.expect b/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.strong.expect
index 3bde972..c503392 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.strong.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.strong.expect
@@ -10,7 +10,7 @@
   set first(dynamic x) → void
     return let final core::List<dynamic>* #t1 = this.{self::Foo::list} in let final core::int* #t2 = 0 in let final dynamic #t3 = x in let final void #t4 = #t1.{core::List::[]=}(#t2, #t3) in #t3;
   operator []=(dynamic x, dynamic y) → void
-    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final dynamic #t6 = x as{TypeError} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
+    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final dynamic #t6 = x as{TypeError,ForDynamic} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
   method clear() → void
     return this.{self::Foo::list}.{core::List::clear}();
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.strong.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.strong.transformed.expect
index 9f36d60..739251d 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.strong.transformed.expect
@@ -10,7 +10,7 @@
   set first(dynamic x) → void
     return let final core::List<dynamic>* #t1 = this.{self::Foo::list} in let final core::int* #t2 = 0 in let final dynamic #t3 = x in let final void #t4 = #t1.{core::List::[]=}(#t2, #t3) in #t3;
   operator []=(dynamic x, dynamic y) → void
-    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final core::int* #t6 = x as{TypeError} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
+    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final core::int* #t6 = x as{TypeError,ForDynamic} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
   method clear() → void
     return this.{self::Foo::list}.{core::List::clear}();
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.weak.expect b/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.weak.expect
index 3bde972..c503392 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.weak.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.weak.expect
@@ -10,7 +10,7 @@
   set first(dynamic x) → void
     return let final core::List<dynamic>* #t1 = this.{self::Foo::list} in let final core::int* #t2 = 0 in let final dynamic #t3 = x in let final void #t4 = #t1.{core::List::[]=}(#t2, #t3) in #t3;
   operator []=(dynamic x, dynamic y) → void
-    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final dynamic #t6 = x as{TypeError} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
+    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final dynamic #t6 = x as{TypeError,ForDynamic} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
   method clear() → void
     return this.{self::Foo::list}.{core::List::clear}();
 }
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.weak.transformed.expect
index 9f36d60..739251d 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/void_methods.dart.weak.transformed.expect
@@ -10,7 +10,7 @@
   set first(dynamic x) → void
     return let final core::List<dynamic>* #t1 = this.{self::Foo::list} in let final core::int* #t2 = 0 in let final dynamic #t3 = x in let final void #t4 = #t1.{core::List::[]=}(#t2, #t3) in #t3;
   operator []=(dynamic x, dynamic y) → void
-    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final core::int* #t6 = x as{TypeError} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
+    return let final core::List<dynamic>* #t5 = this.{self::Foo::list} in let final core::int* #t6 = x as{TypeError,ForDynamic} core::int* in let final dynamic #t7 = y in let final void #t8 = #t5.{core::List::[]=}(#t6, #t7) in #t7;
   method clear() → void
     return this.{self::Foo::list}.{core::List::clear}();
 }
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml b/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml
index a98a4f5..16093f7 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml
@@ -35,10 +35,10 @@
     expectedContent:
       org-dartlang-test:///main.dart:
         - Procedure main
-        - Field lalala_SimulateTransformer
+        - Field unique_SimulateTransformer
       package:foo/foo.dart:
         - Field foo
-        - Field lalala_SimulateTransformer
+        - Field unique_SimulateTransformer
     neededDillLibraries:
       - package:foo/foo.dart
   - entry: main.dart
@@ -61,7 +61,7 @@
     expectedContent:
       org-dartlang-test:///main.dart:
         - Procedure main
-        - Field lalala_SimulateTransformer
+        - Field unique_SimulateTransformer
       package:foo/foo.dart:
         - Field foo2
-        - Field lalala_SimulateTransformer
+        - Field unique_SimulateTransformer
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml.world.1.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml.world.1.expect
index 71e4ef1..6ece7a5 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml.world.1.expect
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml.world.1.expect
@@ -2,13 +2,13 @@
 library from "package:foo/foo.dart" as foo {
 
   static field dart.core::bool* foo = true;
-  final field dynamic lalala_SimulateTransformer /* from null */;
+  final field dynamic unique_SimulateTransformer /* from null */;
 }
 library from "org-dartlang-test:///main.dart" as main {
 
   import "package:foo/foo.dart";
 
-  final field dynamic lalala_SimulateTransformer /* from null */;
+  final field dynamic unique_SimulateTransformer /* from null */;
   static method main() → dynamic {
     dart.core::print(foo::foo);
   }
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml.world.2.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml.world.2.expect
index e13a156..90090ad 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml.world.2.expect
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/changing_modules_3.yaml.world.2.expect
@@ -2,13 +2,13 @@
 library from "package:foo/foo.dart" as foo {
 
   static field dart.core::bool* foo2 = true;
-  final field dynamic lalala_SimulateTransformer /* from null */;
+  final field dynamic unique_SimulateTransformer /* from null */;
 }
 library from "org-dartlang-test:///main.dart" as main {
 
   import "package:foo/foo.dart";
 
-  final field dynamic lalala_SimulateTransformer /* from null */;
+  final field dynamic unique_SimulateTransformer /* from null */;
   static method main() → dynamic {
     dart.core::print(foo::foo2);
   }
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/constant_exports_hash.yaml b/pkg/front_end/testcases/incremental_initialize_from_dill/constant_exports_hash.yaml
new file mode 100644
index 0000000..ae08c58
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/constant_exports_hash.yaml
@@ -0,0 +1,48 @@
+# Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE.md file.
+
+# Force creation of "_exports#" caused by unserializable exports. It becomes
+# constant. Initializing from it should still be possible.
+
+type: newworld
+worlds:
+  - entry: main.dart
+    errors: true
+    sources:
+      main.dart: |
+        export "lib1.dart" show x;
+        export "lib2.dart" show x;
+        main() {
+          print("exports");
+        }
+      lib1.dart: |
+        x() {
+          print("lib1.x!");
+        }
+      lib2.dart: |
+        x() {
+          print("lib2.x!");
+        }
+    expectedLibraryCount: 3
+  - entry: main.dart
+    errors: true
+    expectInitializeFromDill: true
+    invalidate:
+      - main.dart
+    sources:
+      main.dart: |
+        export "lib1.dart" show x;
+        export "lib2.dart" show x;
+        main() {
+          print("exports!");
+        }
+      lib1.dart: |
+        x() {
+          print("lib1.x!");
+        }
+      lib2.dart: |
+        x() {
+          print("lib2.x!");
+        }
+    expectedLibraryCount: 3
\ No newline at end of file
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/constant_exports_hash.yaml.world.1.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/constant_exports_hash.yaml.world.1.expect
new file mode 100644
index 0000000..dd112fb
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/constant_exports_hash.yaml.world.1.expect
@@ -0,0 +1,33 @@
+main = <No Member>;
+library from "org-dartlang-test:///lib1.dart" as lib1 {
+
+  static method x() → dynamic {
+    dart.core::print("lib1.x!");
+  }
+}
+library from "org-dartlang-test:///lib2.dart" as lib2 {
+
+  static method x() → dynamic {
+    dart.core::print("lib2.x!");
+  }
+}
+library from "org-dartlang-test:///main.dart" as main {
+//
+// Problems in library:
+//
+// org-dartlang-test:///main.dart:2:1: Error: 'x' is exported from both 'org-dartlang-test:///lib1.dart' and 'org-dartlang-test:///lib2.dart'.
+// export "lib2.dart" show x;
+// ^
+//
+
+  export "org-dartlang-test:///lib1.dart";
+  export "org-dartlang-test:///lib2.dart";
+
+  static const field dynamic _exports# = #C1 /* from null */;
+  static method main() → dynamic {
+    dart.core::print("exports");
+  }
+}
+constants  {
+  #C1 = "{\"x\":\"'x' is exported from both 'org-dartlang-test:///lib1.dart' and 'org-dartlang-test:///lib2.dart'.\"}"
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/constant_exports_hash.yaml.world.2.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/constant_exports_hash.yaml.world.2.expect
new file mode 100644
index 0000000..d8da84c
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/constant_exports_hash.yaml.world.2.expect
@@ -0,0 +1,33 @@
+main = <No Member>;
+library from "org-dartlang-test:///lib1.dart" as lib1 {
+
+  static method x() → dynamic {
+    dart.core::print("lib1.x!");
+  }
+}
+library from "org-dartlang-test:///lib2.dart" as lib2 {
+
+  static method x() → dynamic {
+    dart.core::print("lib2.x!");
+  }
+}
+library from "org-dartlang-test:///main.dart" as main {
+//
+// Problems in library:
+//
+// org-dartlang-test:///main.dart:2:1: Error: 'x' is exported from both 'org-dartlang-test:///lib1.dart' and 'org-dartlang-test:///lib2.dart'.
+// export "lib2.dart" show x;
+// ^
+//
+
+  export "org-dartlang-test:///lib1.dart";
+  export "org-dartlang-test:///lib2.dart";
+
+  static const field dynamic _exports# = #C1 /* from null */;
+  static method main() → dynamic {
+    dart.core::print("exports!");
+  }
+}
+constants  {
+  #C1 = "{\"x\":\"'x' is exported from both 'org-dartlang-test:///lib1.dart' and 'org-dartlang-test:///lib2.dart'.\"}"
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/expression_calculation_with_error.yaml b/pkg/front_end/testcases/incremental_initialize_from_dill/expression_calculation_with_error.yaml
index 9baf55e..51073a5 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/expression_calculation_with_error.yaml
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/expression_calculation_with_error.yaml
@@ -20,6 +20,7 @@
     expressionCompilation:
       uri: main.dart
       expression: foo()
+      errors: true
   - entry: main.dart
     expectInitializeFromDill: false
     worldType: updated
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/extension_expression_compilation_usage.yaml b/pkg/front_end/testcases/incremental_initialize_from_dill/extension_expression_compilation_usage.yaml
new file mode 100644
index 0000000..13a6a2e
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/extension_expression_compilation_usage.yaml
@@ -0,0 +1,20 @@
+# Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE.md file.
+
+# Test expression compilation using extension on String.
+
+type: newworld
+worlds:
+  - entry: main.dart
+    sources:
+      main.dart: |
+        extension NumberParsing on String {
+          int parseInt() {
+            return int.parse(this);
+          }
+        }
+    expectedLibraryCount: 1
+    expressionCompilation:
+      uri: main.dart
+      expression: print("1234".parseInt())
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/extension_expression_compilation_usage.yaml.world.1.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/extension_expression_compilation_usage.yaml.world.1.expect
new file mode 100644
index 0000000..73e7fda
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/extension_expression_compilation_usage.yaml.world.1.expect
@@ -0,0 +1,13 @@
+main = <No Member>;
+library from "org-dartlang-test:///main.dart" as main {
+
+  extension NumberParsing on dart.core::String* {
+    method parseInt = main::NumberParsing|parseInt;
+    tearoff parseInt = main::NumberParsing|get#parseInt;
+  }
+  static method NumberParsing|parseInt(final dart.core::String* #this) → dart.core::int* {
+    return dart.core::int::parse(#this);
+  }
+  static method NumberParsing|get#parseInt(final dart.core::String* #this) → () →* dart.core::int*
+    return () → dart.core::int* => main::NumberParsing|parseInt(#this);
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/extension_usage_from_dill.yaml b/pkg/front_end/testcases/incremental_initialize_from_dill/extension_usage_from_dill.yaml
new file mode 100644
index 0000000..fb17878
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/extension_usage_from_dill.yaml
@@ -0,0 +1,96 @@
+# Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE.md file.
+
+# Test extension on String from import from dill.
+
+type: newworld
+worlds:
+  - entry: main.dart
+    sources:
+      main.dart: |
+        import "lib1.dart";
+        import "lib2.dart";
+        import "lib3.dart";
+        main() {
+          "42".parseInt();
+          "42".fooMe1();
+          "42".fooMe2();
+        }
+      lib1.dart: |
+        extension NumberParsing on String {
+          int parseInt() {
+            return int.parse(this);
+          }
+        }
+      lib2.dart: |
+        extension DuplicateName on String {
+          String fooMe1() {
+            return "Foo1";
+          }
+        }
+      lib3.dart: |
+        extension DuplicateName on String {
+          String fooMe2() {
+            return "Foo2";
+          }
+        }
+    expectedLibraryCount: 4
+    expressionCompilation:
+      - uri: lib1.dart
+        expression: print("1234".parseInt())
+      - uri: lib2.dart
+        expression: print("1234".parseInt())
+        errors: true
+      - uri: lib3.dart
+        expression: print("1234".parseInt())
+        errors: true
+      - uri: main.dart
+        expression: print("1234".parseInt())
+      - uri: main.dart
+        expression: print("1234".fooMe1())
+  - entry: main.dart
+    invalidate:
+      - main.dart
+    sources:
+      main.dart: |
+        import "lib1.dart";
+        import "lib2.dart";
+        import "lib3.dart";
+        main() {
+          "42".parseInt();
+          "42".fooMe1();
+          "42".fooMe2();
+        }
+      lib1.dart: |
+        extension NumberParsing on String {
+          int parseInt() {
+            return int.parse(this);
+          }
+        }
+      lib2.dart: |
+        extension DuplicateName on String {
+          String fooMe1() {
+            return "Foo1";
+          }
+        }
+      lib3.dart: |
+        extension DuplicateName on String {
+          String fooMe2() {
+            return "Foo2";
+          }
+        }
+    expectedLibraryCount: 4
+    expressionCompilation:
+      - uri: lib1.dart
+        expression: print("1234".parseInt())
+      - uri: lib2.dart
+        expression: print("1234".parseInt())
+        errors: true
+      - uri: lib3.dart
+        expression: print("1234".parseInt())
+        errors: true
+      - uri: main.dart
+        expression: print("1234".parseInt())
+      - uri: main.dart
+        expression: print("1234".fooMe1())
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/extension_usage_from_dill.yaml.world.1.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/extension_usage_from_dill.yaml.world.1.expect
new file mode 100644
index 0000000..874b7c7
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/extension_usage_from_dill.yaml.world.1.expect
@@ -0,0 +1,49 @@
+main = <No Member>;
+library from "org-dartlang-test:///lib1.dart" as lib1 {
+
+  extension NumberParsing on dart.core::String* {
+    method parseInt = lib1::NumberParsing|parseInt;
+    tearoff parseInt = lib1::NumberParsing|get#parseInt;
+  }
+  static method NumberParsing|parseInt(final dart.core::String* #this) → dart.core::int* {
+    return dart.core::int::parse(#this);
+  }
+  static method NumberParsing|get#parseInt(final dart.core::String* #this) → () →* dart.core::int*
+    return () → dart.core::int* => lib1::NumberParsing|parseInt(#this);
+}
+library from "org-dartlang-test:///lib2.dart" as lib2 {
+
+  extension DuplicateName on dart.core::String* {
+    method fooMe1 = lib2::DuplicateName|fooMe1;
+    tearoff fooMe1 = lib2::DuplicateName|get#fooMe1;
+  }
+  static method DuplicateName|fooMe1(final dart.core::String* #this) → dart.core::String* {
+    return "Foo1";
+  }
+  static method DuplicateName|get#fooMe1(final dart.core::String* #this) → () →* dart.core::String*
+    return () → dart.core::String* => lib2::DuplicateName|fooMe1(#this);
+}
+library from "org-dartlang-test:///lib3.dart" as lib3 {
+
+  extension DuplicateName on dart.core::String* {
+    method fooMe2 = lib3::DuplicateName|fooMe2;
+    tearoff fooMe2 = lib3::DuplicateName|get#fooMe2;
+  }
+  static method DuplicateName|fooMe2(final dart.core::String* #this) → dart.core::String* {
+    return "Foo2";
+  }
+  static method DuplicateName|get#fooMe2(final dart.core::String* #this) → () →* dart.core::String*
+    return () → dart.core::String* => lib3::DuplicateName|fooMe2(#this);
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///lib1.dart";
+  import "org-dartlang-test:///lib2.dart";
+  import "org-dartlang-test:///lib3.dart";
+
+  static method main() → dynamic {
+    lib1::NumberParsing|parseInt("42");
+    lib2::DuplicateName|fooMe1("42");
+    lib3::DuplicateName|fooMe2("42");
+  }
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/extension_usage_from_dill.yaml.world.2.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/extension_usage_from_dill.yaml.world.2.expect
new file mode 100644
index 0000000..874b7c7
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/extension_usage_from_dill.yaml.world.2.expect
@@ -0,0 +1,49 @@
+main = <No Member>;
+library from "org-dartlang-test:///lib1.dart" as lib1 {
+
+  extension NumberParsing on dart.core::String* {
+    method parseInt = lib1::NumberParsing|parseInt;
+    tearoff parseInt = lib1::NumberParsing|get#parseInt;
+  }
+  static method NumberParsing|parseInt(final dart.core::String* #this) → dart.core::int* {
+    return dart.core::int::parse(#this);
+  }
+  static method NumberParsing|get#parseInt(final dart.core::String* #this) → () →* dart.core::int*
+    return () → dart.core::int* => lib1::NumberParsing|parseInt(#this);
+}
+library from "org-dartlang-test:///lib2.dart" as lib2 {
+
+  extension DuplicateName on dart.core::String* {
+    method fooMe1 = lib2::DuplicateName|fooMe1;
+    tearoff fooMe1 = lib2::DuplicateName|get#fooMe1;
+  }
+  static method DuplicateName|fooMe1(final dart.core::String* #this) → dart.core::String* {
+    return "Foo1";
+  }
+  static method DuplicateName|get#fooMe1(final dart.core::String* #this) → () →* dart.core::String*
+    return () → dart.core::String* => lib2::DuplicateName|fooMe1(#this);
+}
+library from "org-dartlang-test:///lib3.dart" as lib3 {
+
+  extension DuplicateName on dart.core::String* {
+    method fooMe2 = lib3::DuplicateName|fooMe2;
+    tearoff fooMe2 = lib3::DuplicateName|get#fooMe2;
+  }
+  static method DuplicateName|fooMe2(final dart.core::String* #this) → dart.core::String* {
+    return "Foo2";
+  }
+  static method DuplicateName|get#fooMe2(final dart.core::String* #this) → () →* dart.core::String*
+    return () → dart.core::String* => lib3::DuplicateName|fooMe2(#this);
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///lib1.dart";
+  import "org-dartlang-test:///lib2.dart";
+  import "org-dartlang-test:///lib3.dart";
+
+  static method main() → dynamic {
+    lib1::NumberParsing|parseInt("42");
+    lib2::DuplicateName|fooMe1("42");
+    lib3::DuplicateName|fooMe2("42");
+  }
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/ffi_01.yaml.world.2.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/ffi_01.yaml.world.2.expect
new file mode 100644
index 0000000..2fefb04
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/ffi_01.yaml.world.2.expect
@@ -0,0 +1,64 @@
+main = <No Member>;
+library from "org-dartlang-test:///lib.dart" as lib {
+
+  import "dart:ffi";
+
+  @#C3
+  class Coordinate extends dart.ffi::Struct {
+    @#C3
+    static final field dart.core::int* #sizeOf = (#C6).{dart.core::List::[]}(dart.ffi::_abi());
+    @#C3
+    constructor #fromPointer(dynamic #pointer) → dynamic
+      : super dart.ffi::Struct::_fromPointer(#pointer)
+      ;
+    static factory allocate(dart.core::double* x, dart.core::double* y, dart.ffi::Pointer<lib::Coordinate*>* next) → lib::Coordinate* {
+      return null;
+    }
+    get #_ptr_x() → dart.ffi::Pointer<dart.ffi::Double*>*
+      return this.{dart.ffi::Struct::_addressOf}.{dart.ffi::Pointer::cast}<dart.ffi::Double*>();
+    get x() → dart.core::double*
+      return dart.ffi::_loadDouble(this.{lib::Coordinate::#_ptr_x}, #C7);
+    set x(dart.core::double* #v) → void
+      return dart.ffi::_storeDouble(this.{lib::Coordinate::#_ptr_x}, #C7, #v);
+    get #_ptr_y() → dart.ffi::Pointer<dart.ffi::Double*>*
+      return this.{dart.ffi::Struct::_addressOf}.{dart.ffi::Pointer::_offsetBy}((#C9).{dart.core::List::[]}(dart.ffi::_abi())).{dart.ffi::Pointer::cast}<dart.ffi::Double*>();
+    get y() → dart.core::double*
+      return dart.ffi::_loadDouble(this.{lib::Coordinate::#_ptr_y}, #C7);
+    set y(dart.core::double* #v) → void
+      return dart.ffi::_storeDouble(this.{lib::Coordinate::#_ptr_y}, #C7, #v);
+    get #_ptr_next() → dart.ffi::Pointer<dart.ffi::Pointer<lib::Coordinate*>*>*
+      return this.{dart.ffi::Struct::_addressOf}.{dart.ffi::Pointer::_offsetBy}((#C11).{dart.core::List::[]}(dart.ffi::_abi())).{dart.ffi::Pointer::cast}<dart.ffi::Pointer<lib::Coordinate*>*>();
+    get next() → dart.ffi::Pointer<lib::Coordinate*>*
+      return dart.ffi::_loadPointer<dart.ffi::Pointer<lib::Coordinate*>*>(this.{lib::Coordinate::#_ptr_next}, #C7);
+    set next(dart.ffi::Pointer<lib::Coordinate*>* #v) → void
+      return dart.ffi::_storePointer<dart.ffi::Pointer<lib::Coordinate*>*>(this.{lib::Coordinate::#_ptr_next}, #C7, #v);
+  }
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///lib.dart";
+
+  static method main() → dynamic {
+    lib::Coordinate* coordinate = lib::Coordinate::allocate(42.0, 42.0, null);
+    dart.core::print(coordinate.{lib::Coordinate::x});
+    dart.core::print(coordinate.{lib::Coordinate::y});
+    dart.core::print(coordinate.{lib::Coordinate::next});
+    main::done();
+  }
+  static method done() → dynamic {
+    dart.core::print("Done!");
+  }
+}
+constants  {
+  #C1 = "vm:entry-point"
+  #C2 = null
+  #C3 = dart.core::pragma {name:#C1, options:#C2}
+  #C4 = 24
+  #C5 = 20
+  #C6 = <dart.core::int*>[#C4, #C5, #C4]
+  #C7 = 0
+  #C8 = 8
+  #C9 = <dart.core::int*>[#C8, #C8, #C8]
+  #C10 = 16
+  #C11 = <dart.core::int*>[#C10, #C10, #C10]
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/ffi_02.yaml b/pkg/front_end/testcases/incremental_initialize_from_dill/ffi_02.yaml
new file mode 100644
index 0000000..be678ed
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/ffi_02.yaml
@@ -0,0 +1,42 @@
+# Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE.md file.
+
+# Test FFI compilation. Do expression computation using a (converted to getter)
+# field in the FFI-struct class.
+
+type: newworld
+worlds:
+  - entry: main.dart
+    sources:
+      main.dart: |
+        import 'lib.dart';
+
+        Coordinate coordinate;
+
+        main() {
+          coordinate = new Coordinate.allocate(42.0, 42.0, null);
+          print(coordinate.x);
+          print(coordinate.y);
+          print(coordinate.next);
+        }
+      lib.dart: |
+        import 'dart:ffi';
+
+        class Coordinate extends Struct {
+          @Double()
+          double x;
+
+          @Double()
+          double y;
+
+          Pointer<Coordinate> next;
+
+          factory Coordinate.allocate(double x, double y, Pointer<Coordinate> next) {
+            return null;
+          }
+        }
+    expectedLibraryCount: 2
+    expressionCompilation:
+      uri: main.dart
+      expression: print(coordinate.x)
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/ffi_02.yaml.world.1.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/ffi_02.yaml.world.1.expect
new file mode 100644
index 0000000..51d68a9
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/ffi_02.yaml.world.1.expect
@@ -0,0 +1,61 @@
+main = <No Member>;
+library from "org-dartlang-test:///lib.dart" as lib {
+
+  import "dart:ffi";
+
+  @#C3
+  class Coordinate extends dart.ffi::Struct {
+    @#C3
+    static final field dart.core::int* #sizeOf = (#C6).{dart.core::List::[]}(dart.ffi::_abi());
+    @#C3
+    constructor #fromPointer(dynamic #pointer) → dynamic
+      : super dart.ffi::Struct::_fromPointer(#pointer)
+      ;
+    static factory allocate(dart.core::double* x, dart.core::double* y, dart.ffi::Pointer<lib::Coordinate*>* next) → lib::Coordinate* {
+      return null;
+    }
+    get #_ptr_x() → dart.ffi::Pointer<dart.ffi::Double*>*
+      return this.{dart.ffi::Struct::_addressOf}.{dart.ffi::Pointer::cast}<dart.ffi::Double*>();
+    get x() → dart.core::double*
+      return dart.ffi::_loadDouble(this.{lib::Coordinate::#_ptr_x}, #C7);
+    set x(dart.core::double* #v) → void
+      return dart.ffi::_storeDouble(this.{lib::Coordinate::#_ptr_x}, #C7, #v);
+    get #_ptr_y() → dart.ffi::Pointer<dart.ffi::Double*>*
+      return this.{dart.ffi::Struct::_addressOf}.{dart.ffi::Pointer::_offsetBy}((#C9).{dart.core::List::[]}(dart.ffi::_abi())).{dart.ffi::Pointer::cast}<dart.ffi::Double*>();
+    get y() → dart.core::double*
+      return dart.ffi::_loadDouble(this.{lib::Coordinate::#_ptr_y}, #C7);
+    set y(dart.core::double* #v) → void
+      return dart.ffi::_storeDouble(this.{lib::Coordinate::#_ptr_y}, #C7, #v);
+    get #_ptr_next() → dart.ffi::Pointer<dart.ffi::Pointer<lib::Coordinate*>*>*
+      return this.{dart.ffi::Struct::_addressOf}.{dart.ffi::Pointer::_offsetBy}((#C11).{dart.core::List::[]}(dart.ffi::_abi())).{dart.ffi::Pointer::cast}<dart.ffi::Pointer<lib::Coordinate*>*>();
+    get next() → dart.ffi::Pointer<lib::Coordinate*>*
+      return dart.ffi::_loadPointer<dart.ffi::Pointer<lib::Coordinate*>*>(this.{lib::Coordinate::#_ptr_next}, #C7);
+    set next(dart.ffi::Pointer<lib::Coordinate*>* #v) → void
+      return dart.ffi::_storePointer<dart.ffi::Pointer<lib::Coordinate*>*>(this.{lib::Coordinate::#_ptr_next}, #C7, #v);
+  }
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///lib.dart";
+
+  static field lib::Coordinate* coordinate;
+  static method main() → dynamic {
+    main::coordinate = lib::Coordinate::allocate(42.0, 42.0, null);
+    dart.core::print(main::coordinate.{lib::Coordinate::x});
+    dart.core::print(main::coordinate.{lib::Coordinate::y});
+    dart.core::print(main::coordinate.{lib::Coordinate::next});
+  }
+}
+constants  {
+  #C1 = "vm:entry-point"
+  #C2 = null
+  #C3 = dart.core::pragma {name:#C1, options:#C2}
+  #C4 = 24
+  #C5 = 20
+  #C6 = <dart.core::int*>[#C4, #C5, #C4]
+  #C7 = 0
+  #C8 = 8
+  #C9 = <dart.core::int*>[#C8, #C8, #C8]
+  #C10 = 16
+  #C11 = <dart.core::int*>[#C10, #C10, #C10]
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_16.yaml.world.1.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_16.yaml.world.1.expect
index 5b6d98f..e1e5ded 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_16.yaml.world.1.expect
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_16.yaml.world.1.expect
@@ -23,7 +23,7 @@
       dart.core::print("noSouchMethod!");
     }
     no-such-method-forwarder get /* from org-dartlang-test:///lib1.dart */ getter() → dart.core::bool*
-      return this.{main::Foo1::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError} dart.core::bool*;
+      return this.{main::Foo1::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dart.core::bool*;
     no-such-method-forwarder method /* from org-dartlang-test:///lib1.dart */ method() → void
       return this.{main::Foo1::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C5, 0, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4)));
     no-such-method-forwarder set /* from org-dartlang-test:///lib1.dart */ setter(dart.core::bool* b) → void
@@ -37,9 +37,9 @@
       dart.core::print("noSouchMethod!");
     }
     no-such-method-forwarder get /* from org-dartlang-test:///lib1.dart */ getter() → dart.core::bool*
-      return this.{main::Foo2::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError} dart.core::bool*;
+      return this.{main::Foo2::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dart.core::bool*;
     no-such-method-forwarder get /* from org-dartlang-test:///lib1.dart */ field() → dart.core::bool*
-      return this.{main::Foo2::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C7, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError} dart.core::bool*;
+      return this.{main::Foo2::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C7, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dart.core::bool*;
     no-such-method-forwarder method /* from org-dartlang-test:///lib1.dart */ method() → void
       return this.{main::Foo2::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C5, 0, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4)));
     no-such-method-forwarder set /* from org-dartlang-test:///lib1.dart */ setter(dart.core::bool* b) → void
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_16.yaml.world.2.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_16.yaml.world.2.expect
index 11a8f3e..1b65ff5 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_16.yaml.world.2.expect
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_16.yaml.world.2.expect
@@ -23,7 +23,7 @@
       dart.core::print("noSouchMethod!!");
     }
     no-such-method-forwarder get /* from org-dartlang-test:///lib1.dart */ getter() → dart.core::bool*
-      return this.{main::Foo1::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError} dart.core::bool*;
+      return this.{main::Foo1::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dart.core::bool*;
     no-such-method-forwarder method /* from org-dartlang-test:///lib1.dart */ method() → void
       return this.{main::Foo1::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C5, 0, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4)));
     no-such-method-forwarder set /* from org-dartlang-test:///lib1.dart */ setter(dart.core::bool* b) → void
@@ -37,9 +37,9 @@
       dart.core::print("noSouchMethod!!");
     }
     no-such-method-forwarder get /* from org-dartlang-test:///lib1.dart */ getter() → dart.core::bool*
-      return this.{main::Foo2::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError} dart.core::bool*;
+      return this.{main::Foo2::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dart.core::bool*;
     no-such-method-forwarder get /* from org-dartlang-test:///lib1.dart */ field() → dart.core::bool*
-      return this.{main::Foo2::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C7, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError} dart.core::bool*;
+      return this.{main::Foo2::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C7, 1, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dart.core::bool*;
     no-such-method-forwarder method /* from org-dartlang-test:///lib1.dart */ method() → void
       return this.{main::Foo2::noSuchMethod}(new dart.core::_InvocationMirror::_withType(#C5, 0, #C2, #C3, dart.core::Map::unmodifiable<dart.core::Symbol*, dynamic>(#C4)));
     no-such-method-forwarder set /* from org-dartlang-test:///lib1.dart */ setter(dart.core::bool* b) → void
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_22.yaml.world.1.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_22.yaml.world.1.expect
index 6d4a7d3..faa6a66 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_22.yaml.world.1.expect
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_22.yaml.world.1.expect
@@ -284,7 +284,7 @@
       dart._internal::Sort::sort<dart.core::int*>(this, let final (dart.core::int*, dart.core::int*) →* dart.core::int* #t7 = compare in #t7.{dart.core::Object::==}(null) ?{(dart.core::int*, dart.core::int*) →* dart.core::int*} #C6 : #t7);
     }
     static method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ _compareAny(dynamic a, dynamic b) → dart.core::int* {
-      return dart.core::Comparable::compare(a as{TypeError} dart.core::Comparable<dynamic>*, b as{TypeError} dart.core::Comparable<dynamic>*);
+      return dart.core::Comparable::compare(a as{TypeError,ForDynamic} dart.core::Comparable<dynamic>*, b as{TypeError,ForDynamic} dart.core::Comparable<dynamic>*);
     }
     method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ shuffle([dart.math::Random* random = #C2]) → void {
       random.{dart.core::Object::==}(null) ?{dart.math::Random*} random = dart.math::Random::•() : null;
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_22.yaml.world.2.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_22.yaml.world.2.expect
index 6d4a7d3..faa6a66 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_22.yaml.world.2.expect
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/no_outline_change_22.yaml.world.2.expect
@@ -284,7 +284,7 @@
       dart._internal::Sort::sort<dart.core::int*>(this, let final (dart.core::int*, dart.core::int*) →* dart.core::int* #t7 = compare in #t7.{dart.core::Object::==}(null) ?{(dart.core::int*, dart.core::int*) →* dart.core::int*} #C6 : #t7);
     }
     static method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ _compareAny(dynamic a, dynamic b) → dart.core::int* {
-      return dart.core::Comparable::compare(a as{TypeError} dart.core::Comparable<dynamic>*, b as{TypeError} dart.core::Comparable<dynamic>*);
+      return dart.core::Comparable::compare(a as{TypeError,ForDynamic} dart.core::Comparable<dynamic>*, b as{TypeError,ForDynamic} dart.core::Comparable<dynamic>*);
     }
     method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ shuffle([dart.math::Random* random = #C2]) → void {
       random.{dart.core::Object::==}(null) ?{dart.math::Random*} random = dart.math::Random::•() : null;
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/status.status b/pkg/front_end/testcases/incremental_initialize_from_dill/status.status
index 6807261..4874153 100644
--- a/pkg/front_end/testcases/incremental_initialize_from_dill/status.status
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/status.status
@@ -4,4 +4,18 @@
 
 # Status file for the test suite ../test/incremental_load_from_dill_test.dart.
 
-ffi_01: Crash # http://dartbug.com/39840
+no_outline_change_1: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_2: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_6: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_7: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_9: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_10: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_11: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_12: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_13: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_14: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_21: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_24: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_27: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_33: Crash # Doesn't work on DillLibraryBuilders.
+no_outline_change_34: Crash # Doesn't work on DillLibraryBuilders.
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/typedef_crash_01.yaml b/pkg/front_end/testcases/incremental_initialize_from_dill/typedef_crash_01.yaml
new file mode 100644
index 0000000..ca9f7f1
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/typedef_crash_01.yaml
@@ -0,0 +1,30 @@
+# Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE.md file.
+
+# Re-create https://github.com/flutter/flutter/issues/48804.
+
+type: newworld
+worlds:
+  - entry: main.dart
+    errors: false
+    sources:
+      main.dart: |
+        import "lib.dart";
+        typedef G<T> = Function(F<T>);
+      lib.dart: |
+        typedef F<T> = Function();
+    expectedLibraryCount: 2
+  - entry: main.dart
+    errors: false
+    expectInitializeFromDill: true
+    invalidate:
+      - main.dart
+    sources:
+      main.dart: |
+        import "lib.dart";
+        typedef G<T> = Function(F<T>);
+        main() {
+          print("Hello");
+        }
+    expectedLibraryCount: 2
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/typedef_crash_01.yaml.world.1.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/typedef_crash_01.yaml.world.1.expect
new file mode 100644
index 0000000..6b0429d
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/typedef_crash_01.yaml.world.1.expect
@@ -0,0 +1,11 @@
+main = <No Member>;
+library from "org-dartlang-test:///lib.dart" as lib {
+
+  typedef F<unrelated T extends dart.core::Object* = dynamic> = () →* dynamic;
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///lib.dart";
+
+  typedef G<unrelated T extends dart.core::Object* = dynamic> = (() →* dynamic) →* dynamic;
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/typedef_crash_01.yaml.world.2.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/typedef_crash_01.yaml.world.2.expect
new file mode 100644
index 0000000..30c96c7
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/typedef_crash_01.yaml.world.2.expect
@@ -0,0 +1,14 @@
+main = <No Member>;
+library from "org-dartlang-test:///lib.dart" as lib {
+
+  typedef F<unrelated T extends dart.core::Object* = dynamic> = () →* dynamic;
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///lib.dart";
+
+  typedef G<unrelated T extends dart.core::Object* = dynamic> = (() →* dynamic) →* dynamic;
+  static method main() → dynamic {
+    dart.core::print("Hello");
+  }
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml b/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml
new file mode 100644
index 0000000..22c9d3b
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml
@@ -0,0 +1,42 @@
+# Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE.md file.
+
+# Adopted from vm/cc/IRTest_TypedDataAOT_FunctionalIndexError.
+
+type: newworld
+worlds:
+  - entry: set-Uint8List.dart
+    sources:
+      set-Uint8List.dart: |
+        import 'dart:typed_data';
+        void setUint8List(Uint8List list, int index, int value) {
+          list[index] = value;
+        }
+    expectedLibraryCount: 1
+  - entry: set-Int8List.dart
+    worldType: updated
+    checkInvalidatedFiles: false
+    expectInitializeFromDill: false
+    invalidate:
+      - set-Int8List.dart
+    sources:
+      set-Int8List.dart: |
+        import 'dart:typed_data';
+        void setInt8List(Int8List list, int index, int value) {
+          list[index] = value;
+        }
+    expectedLibraryCount: 1
+  - entry: set-Uint8List.dart
+    worldType: updated
+    checkInvalidatedFiles: false
+    expectInitializeFromDill: false
+    invalidate:
+      - set-Uint8List.dart
+    sources:
+      set-Uint8List.dart: |
+        import 'dart:typed_data';
+        void setUint8List(Uint8List list, int index, int value) {
+          list[index] = value;
+        }
+    expectedLibraryCount: 1
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml.world.1.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml.world.1.expect
new file mode 100644
index 0000000..6c62e4d
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml.world.1.expect
@@ -0,0 +1,9 @@
+main = <No Member>;
+library from "org-dartlang-test:///set-Uint8List.dart" as set {
+
+  import "dart:typed_data";
+
+  static method setUint8List(dart.typed_data::Uint8List* list, dart.core::int* index, dart.core::int* value) → void {
+    list.{dart.core::List::[]=}(index, value);
+  }
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml.world.2.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml.world.2.expect
new file mode 100644
index 0000000..543a390
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml.world.2.expect
@@ -0,0 +1,9 @@
+main = <No Member>;
+library from "org-dartlang-test:///set-Int8List.dart" as set {
+
+  import "dart:typed_data";
+
+  static method setInt8List(dart.typed_data::Int8List* list, dart.core::int* index, dart.core::int* value) → void {
+    list.{dart.core::List::[]=}(index, value);
+  }
+}
diff --git a/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml.world.3.expect b/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml.world.3.expect
new file mode 100644
index 0000000..6c62e4d
--- /dev/null
+++ b/pkg/front_end/testcases/incremental_initialize_from_dill/vm_IRTest_TypedDataAOT_FunctionalIndexError.yaml.world.3.expect
@@ -0,0 +1,9 @@
+main = <No Member>;
+library from "org-dartlang-test:///set-Uint8List.dart" as set {
+
+  import "dart:typed_data";
+
+  static method setUint8List(dart.typed_data::Uint8List* list, dart.core::int* index, dart.core::int* value) → void {
+    list.{dart.core::List::[]=}(index, value);
+  }
+}
diff --git a/pkg/front_end/testcases/inference/bug33324.dart.strong.expect b/pkg/front_end/testcases/inference/bug33324.dart.strong.expect
index b1e4298..74b0bb6 100644
--- a/pkg/front_end/testcases/inference/bug33324.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/bug33324.dart.strong.expect
@@ -6,6 +6,6 @@
   core::Function* f = (dynamic x) → dynamic => x;
   core::List<dynamic>* l = <core::String*>["bar"].{core::Iterable::map}<dynamic>(f as{TypeError} (core::String*) →* dynamic).{core::Iterable::toList}();
   l.{core::List::add}(42);
-  return l.{core::Iterable::first}.length as{TypeError} core::int*;
+  return l.{core::Iterable::first}.length as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/bug33324.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/bug33324.dart.strong.transformed.expect
index b1e4298..74b0bb6 100644
--- a/pkg/front_end/testcases/inference/bug33324.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/bug33324.dart.strong.transformed.expect
@@ -6,6 +6,6 @@
   core::Function* f = (dynamic x) → dynamic => x;
   core::List<dynamic>* l = <core::String*>["bar"].{core::Iterable::map}<dynamic>(f as{TypeError} (core::String*) →* dynamic).{core::Iterable::toList}();
   l.{core::List::add}(42);
-  return l.{core::Iterable::first}.length as{TypeError} core::int*;
+  return l.{core::Iterable::first}.length as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/do_not_infer_overridden_fields_that_explicitly_say_dynamic_infer.dart.strong.expect b/pkg/front_end/testcases/inference/do_not_infer_overridden_fields_that_explicitly_say_dynamic_infer.dart.strong.expect
index 38a8a35..e095535 100644
--- a/pkg/front_end/testcases/inference/do_not_infer_overridden_fields_that_explicitly_say_dynamic_infer.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/do_not_infer_overridden_fields_that_explicitly_say_dynamic_infer.dart.strong.expect
@@ -27,8 +27,8 @@
     return 3;
 }
 static method foo() → dynamic {
-  core::String* y = new self::B::•().{self::B::x} as{TypeError} core::String*;
-  core::int* z = new self::B::•().{self::B::x} as{TypeError} core::int*;
+  core::String* y = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::String*;
+  core::int* z = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {
   self::foo();
diff --git a/pkg/front_end/testcases/inference/downward_inference_fixes_no_upwards_errors.dart.strong.expect b/pkg/front_end/testcases/inference/downward_inference_fixes_no_upwards_errors.dart.strong.expect
index 88d238f..c7d6e17 100644
--- a/pkg/front_end/testcases/inference/downward_inference_fixes_no_upwards_errors.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/downward_inference_fixes_no_upwards_errors.dart.strong.expect
@@ -21,8 +21,8 @@
 static method f() → dynamic {
   core::num* x;
   dynamic y;
-  core::num* a = math::max<core::num*>(x, y as{TypeError} core::num*);
-  core::Object* b = math::max<core::num*>(x, y as{TypeError} core::num*);
+  core::num* a = math::max<core::num*>(x, y as{TypeError,ForDynamic} core::num*);
+  core::Object* b = math::max<core::num*>(x, y as{TypeError,ForDynamic} core::num*);
   dynamic c = math::max<dynamic>(x, y);
   dynamic d = math::max<dynamic>(x, y);
 }
diff --git a/pkg/front_end/testcases/inference/downward_inference_fixes_no_upwards_errors.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/downward_inference_fixes_no_upwards_errors.dart.strong.transformed.expect
index 88d238f..c7d6e17 100644
--- a/pkg/front_end/testcases/inference/downward_inference_fixes_no_upwards_errors.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/downward_inference_fixes_no_upwards_errors.dart.strong.transformed.expect
@@ -21,8 +21,8 @@
 static method f() → dynamic {
   core::num* x;
   dynamic y;
-  core::num* a = math::max<core::num*>(x, y as{TypeError} core::num*);
-  core::Object* b = math::max<core::num*>(x, y as{TypeError} core::num*);
+  core::num* a = math::max<core::num*>(x, y as{TypeError,ForDynamic} core::num*);
+  core::Object* b = math::max<core::num*>(x, y as{TypeError,ForDynamic} core::num*);
   dynamic c = math::max<dynamic>(x, y);
   dynamic d = math::max<dynamic>(x, y);
 }
diff --git a/pkg/front_end/testcases/inference/downwards_inference_async_await.dart.strong.expect b/pkg/front_end/testcases/inference/downwards_inference_async_await.dart.strong.expect
index 360f7c7..1a5ac1a 100644
--- a/pkg/front_end/testcases/inference/downwards_inference_async_await.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/downwards_inference_async_await.dart.strong.expect
@@ -7,6 +7,6 @@
 
 static method main() → asy::Future<dynamic>* async {
   dynamic d;
-  core::List<core::int*>* l0 = await<core::int*>[d as{TypeError} core::int*];
-  core::List<core::int*>* l1 = await asy::Future::value<core::List<core::int*>*>(<core::int*>[d as{TypeError} core::int*]);
+  core::List<core::int*>* l0 = await<core::int*>[d as{TypeError,ForDynamic} core::int*];
+  core::List<core::int*>* l1 = await asy::Future::value<core::List<core::int*>*>(<core::int*>[d as{TypeError,ForDynamic} core::int*]);
 }
diff --git a/pkg/front_end/testcases/inference/downwards_inference_async_await.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/downwards_inference_async_await.dart.strong.transformed.expect
index 947d113..92361c9 100644
--- a/pkg/front_end/testcases/inference/downwards_inference_async_await.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/downwards_inference_async_await.dart.strong.transformed.expect
@@ -20,9 +20,9 @@
       #L1:
       {
         dynamic d;
-        [yield] let dynamic #t1 = asy::_awaitHelper(<core::int*>[d as{TypeError} core::int*], :async_op_then, :async_op_error, :async_op) in null;
+        [yield] let dynamic #t1 = asy::_awaitHelper(<core::int*>[d as{TypeError,ForDynamic} core::int*], :async_op_then, :async_op_error, :async_op) in null;
         core::List<core::int*>* l0 = _in::unsafeCast<core::List<core::int*>*>(:result);
-        [yield] let dynamic #t2 = asy::_awaitHelper(asy::Future::value<core::List<core::int*>*>(<core::int*>[d as{TypeError} core::int*]), :async_op_then, :async_op_error, :async_op) in null;
+        [yield] let dynamic #t2 = asy::_awaitHelper(asy::Future::value<core::List<core::int*>*>(<core::int*>[d as{TypeError,ForDynamic} core::int*]), :async_op_then, :async_op_error, :async_op) in null;
         core::List<core::int*>* l1 = _in::unsafeCast<core::List<core::int*>*>(:result);
       }
       asy::_completeOnAsyncReturn(:async_completer, :return_value);
diff --git a/pkg/front_end/testcases/inference/downwards_inference_on_function_expressions.dart.strong.expect b/pkg/front_end/testcases/inference/downwards_inference_on_function_expressions.dart.strong.expect
index e52fb83..55385e0 100644
--- a/pkg/front_end/testcases/inference/downwards_inference_on_function_expressions.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/downwards_inference_on_function_expressions.dart.strong.expect
@@ -110,7 +110,7 @@
     (core::int*) →* core::String* l3 = (core::int* x) → core::String* => invalid-expression "pkg/front_end/testcases/inference/downwards_inference_on_function_expressions.dart:63:14: Error: The method 'substring' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing method, or defining a method named 'substring'.
             .substring(3);
-             ^^^^^^^^^" as{TypeError} core::String*;
+             ^^^^^^^^^" as{TypeError,ForDynamic} core::String*;
     (core::String*) →* core::String* l4 = (core::String* x) → core::String* => x.{core::String::substring}(3);
   }
 }
diff --git a/pkg/front_end/testcases/inference/downwards_inference_on_function_expressions.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/downwards_inference_on_function_expressions.dart.strong.transformed.expect
index e52fb83..55385e0 100644
--- a/pkg/front_end/testcases/inference/downwards_inference_on_function_expressions.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/downwards_inference_on_function_expressions.dart.strong.transformed.expect
@@ -110,7 +110,7 @@
     (core::int*) →* core::String* l3 = (core::int* x) → core::String* => invalid-expression "pkg/front_end/testcases/inference/downwards_inference_on_function_expressions.dart:63:14: Error: The method 'substring' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing method, or defining a method named 'substring'.
             .substring(3);
-             ^^^^^^^^^" as{TypeError} core::String*;
+             ^^^^^^^^^" as{TypeError,ForDynamic} core::String*;
     (core::String*) →* core::String* l4 = (core::String* x) → core::String* => x.{core::String::substring}(3);
   }
 }
diff --git a/pkg/front_end/testcases/inference/downwards_inference_on_generic_function_expressions.dart.strong.expect b/pkg/front_end/testcases/inference/downwards_inference_on_generic_function_expressions.dart.strong.expect
index 40d578f..ee90542 100644
--- a/pkg/front_end/testcases/inference/downwards_inference_on_generic_function_expressions.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/downwards_inference_on_generic_function_expressions.dart.strong.expect
@@ -126,7 +126,7 @@
     y = <T extends core::Object* = dynamic>(core::int* x) → core::String* => invalid-expression "pkg/front_end/testcases/inference/downwards_inference_on_generic_function_expressions.dart:66:10: Error: The method 'substring' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing method, or defining a method named 'substring'.
         .substring(3);
-         ^^^^^^^^^" as{TypeError} core::String*;
+         ^^^^^^^^^" as{TypeError,ForDynamic} core::String*;
     <T extends core::Object* = dynamic>(core::String*) →* core::String* z = string2String;
     z = <T extends core::Object* = dynamic>(core::String* x) → core::String* => x.{core::String::substring}(3);
   }
diff --git a/pkg/front_end/testcases/inference/downwards_inference_on_generic_function_expressions.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/downwards_inference_on_generic_function_expressions.dart.strong.transformed.expect
index 40d578f..ee90542 100644
--- a/pkg/front_end/testcases/inference/downwards_inference_on_generic_function_expressions.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/downwards_inference_on_generic_function_expressions.dart.strong.transformed.expect
@@ -126,7 +126,7 @@
     y = <T extends core::Object* = dynamic>(core::int* x) → core::String* => invalid-expression "pkg/front_end/testcases/inference/downwards_inference_on_generic_function_expressions.dart:66:10: Error: The method 'substring' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing method, or defining a method named 'substring'.
         .substring(3);
-         ^^^^^^^^^" as{TypeError} core::String*;
+         ^^^^^^^^^" as{TypeError,ForDynamic} core::String*;
     <T extends core::Object* = dynamic>(core::String*) →* core::String* z = string2String;
     z = <T extends core::Object* = dynamic>(core::String* x) → core::String* => x.{core::String::substring}(3);
   }
diff --git a/pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.strong.expect b/pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.strong.expect
index 34a20de..93ecd39 100644
--- a/pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.strong.expect
@@ -11,10 +11,10 @@
   }
   core::int* y;
   for (final dynamic #t1 in o as{TypeError} core::Iterable<dynamic>*) {
-    y = #t1 as{TypeError} core::int*;
+    y = #t1 as{TypeError,ForDynamic} core::int*;
   }
   await for (final dynamic #t2 in o as{TypeError} asy::Stream<dynamic>*) {
-    y = #t2 as{TypeError} core::int*;
+    y = #t2 as{TypeError,ForDynamic} core::int*;
   }
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.strong.transformed.expect
index 6d20b98..2bc7b4c 100644
--- a/pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/for_each_downcast_iterable.dart.strong.transformed.expect
@@ -56,7 +56,7 @@
           for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
             final dynamic #t4 = :sync-for-iterator.{core::Iterator::current};
             {
-              y = #t4 as{TypeError} core::int*;
+              y = #t4 as{TypeError,ForDynamic} core::int*;
             }
           }
         }
@@ -72,7 +72,7 @@
               if(_in::unsafeCast<core::bool*>(:result)) {
                 final dynamic #t7 = :for-iterator.{asy::_StreamIterator::current};
                 {
-                  y = #t7 as{TypeError} core::int*;
+                  y = #t7 as{TypeError,ForDynamic} core::int*;
                 }
               }
               else
diff --git a/pkg/front_end/testcases/inference/future_then.dart.outline.expect b/pkg/front_end/testcases/inference/future_then.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then.dart.strong.expect b/pkg/front_end/testcases/inference/future_then.dart.strong.expect
index 65247cd..c72502ef 100644
--- a/pkg/front_end/testcases/inference/future_then.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then.dart.strong.transformed.expect
index 8aa7e82..48ef203 100644
--- a/pkg/front_end/testcases/inference/future_then.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_2.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_2.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_2.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_2.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_2.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_2.dart.strong.expect
index ae490fd762..7a95932 100644
--- a/pkg/front_end/testcases/inference/future_then_2.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_2.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_2.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_2.dart.strong.transformed.expect
index 1e87f8a..a340d04 100644
--- a/pkg/front_end/testcases/inference/future_then_2.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_2.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_3.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_3.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_3.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_3.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_3.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_3.dart.strong.expect
index 680db32..21c7bf4 100644
--- a/pkg/front_end/testcases/inference/future_then_3.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_3.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_3.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_3.dart.strong.transformed.expect
index df9aa51..61dc898 100644
--- a/pkg/front_end/testcases/inference/future_then_3.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_3.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_4.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_4.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_4.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_4.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_4.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_4.dart.strong.expect
index 0bfc7d0..f6f2fe5 100644
--- a/pkg/front_end/testcases/inference/future_then_4.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_4.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_4.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_4.dart.strong.transformed.expect
index c349f97..36e80aa 100644
--- a/pkg/front_end/testcases/inference/future_then_4.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_4.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_5.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_5.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_5.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_5.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_5.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_5.dart.strong.expect
index 0fc40e9..41e6861 100644
--- a/pkg/front_end/testcases/inference/future_then_5.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_5.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   asy::Future<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_5.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_5.dart.strong.transformed.expect
index 1afc871..9d8eb63 100644
--- a/pkg/front_end/testcases/inference/future_then_5.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_5.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   asy::Future<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_6.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_6.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_6.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_6.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_6.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_6.dart.strong.expect
index e7dfa46..de57433 100644
--- a/pkg/front_end/testcases/inference/future_then_6.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_6.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   asy::Future<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_6.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_6.dart.strong.transformed.expect
index 9731f3b..9efbea1 100644
--- a/pkg/front_end/testcases/inference/future_then_6.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_6.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   asy::Future<dynamic>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_conditional.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.expect
index 1ce4d6d..741316a 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.transformed.expect
index 5abd329..c53bad4 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_2.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_conditional_2.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_2.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_2.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.expect
index f386e01..c1241f0 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.transformed.expect
index 852ab83..20f8e91 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_2.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_3.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_conditional_3.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_3.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_3.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.expect
index 6d642c1..e223058 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.transformed.expect
index 56e7a58..2be73df 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_3.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_4.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_conditional_4.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_4.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_4.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.expect
index 37b74ef..c8a5337 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.transformed.expect
index 8009681..ab579f5 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_4.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_5.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_conditional_5.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_5.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_5.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.expect
index 28e6554..4e1ca61 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   asy::Future<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.transformed.expect
index 9cda589..f68b46e 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_5.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   asy::Future<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_6.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_conditional_6.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_6.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_6.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.expect
index da92218..b54dfc2 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   asy::Future<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.transformed.expect
index 50485af..a7f2f7a 100644
--- a/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_conditional_6.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   asy::Future<core::bool*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_ifNull.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_ifNull.dart.outline.expect
index 20ff134..723a215 100644
--- a/pkg/front_end/testcases/inference/future_then_ifNull.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_ifNull.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.expect
index 0bec8e6..87b52ee 100644
--- a/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<core::int*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.transformed.expect
index 760de92..9d9e7dc 100644
--- a/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_ifNull.dart.strong.transformed.expect
@@ -16,13 +16,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   self::MyFuture<core::int*>* f;
diff --git a/pkg/front_end/testcases/inference/future_then_upwards.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_upwards.dart.outline.expect
index c40bb55..d16cbdf 100644
--- a/pkg/front_end/testcases/inference/future_then_upwards.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method main() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.expect
index 3865a9a..3766778 100644
--- a/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.expect
@@ -24,13 +24,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method main() → void {
   self::MyFuture<core::double*>* f = self::foo().{self::MyFuture::then}<core::double*>((dynamic _) → core::double* => 2.3);
diff --git a/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.transformed.expect
index 3865a9a..3766778 100644
--- a/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards.dart.strong.transformed.expect
@@ -24,13 +24,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method main() → void {
   self::MyFuture<core::double*>* f = self::foo().{self::MyFuture::then}<core::double*>((dynamic _) → core::double* => 2.3);
diff --git a/pkg/front_end/testcases/inference/future_then_upwards_2.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_upwards_2.dart.outline.expect
index c40bb55..d16cbdf 100644
--- a/pkg/front_end/testcases/inference/future_then_upwards_2.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_2.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method main() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.expect
index ebacc67..a855441 100644
--- a/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.expect
@@ -23,13 +23,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method main() → void {
   self::MyFuture<core::double*>* f = self::foo().{self::MyFuture::then}<core::double*>((dynamic _) → core::double* => 2.3);
diff --git a/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.transformed.expect
index ebacc67..a855441 100644
--- a/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_2.dart.strong.transformed.expect
@@ -23,13 +23,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method main() → void {
   self::MyFuture<core::double*>* f = self::foo().{self::MyFuture::then}<core::double*>((dynamic _) → core::double* => 2.3);
diff --git a/pkg/front_end/testcases/inference/future_then_upwards_3.dart.outline.expect b/pkg/front_end/testcases/inference/future_then_upwards_3.dart.outline.expect
index f2d1f87..f7cb495 100644
--- a/pkg/front_end/testcases/inference/future_then_upwards_3.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_3.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void
   ;
diff --git a/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.expect b/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.expect
index e7c7bc4..ddb7194 100644
--- a/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.expect
@@ -23,13 +23,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   asy::Future<core::double*>* f = self::foo().{asy::Future::then}<core::double*>((dynamic _) → core::double* => 2.3);
diff --git a/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.transformed.expect
index e7c7bc4..ddb7194 100644
--- a/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_then_upwards_3.dart.strong.transformed.expect
@@ -23,13 +23,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method test() → void {
   asy::Future<core::double*>* f = self::foo().{asy::Future::then}<core::double*>((dynamic _) → core::double* => 2.3);
diff --git a/pkg/front_end/testcases/inference/future_union_async_conditional.dart.outline.expect b/pkg/front_end/testcases/inference/future_union_async_conditional.dart.outline.expect
index a8a37bc..ee3138c 100644
--- a/pkg/front_end/testcases/inference/future_union_async_conditional.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method g1(core::bool* x) → asy::Future<core::int*>*
   ;
diff --git a/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.expect b/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.expect
index 5b4785c..6f320ff 100644
--- a/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method g1(core::bool* x) → asy::Future<core::int*>* async {
   return (x ?{core::Object*} 42 : asy::Future::value<core::int*>(42)) as{TypeError} asy::FutureOr<core::int*>*;
diff --git a/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.transformed.expect
index 4f29e0f..0c1809a 100644
--- a/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional.dart.strong.transformed.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method g1(core::bool* x) → asy::Future<core::int*>* /* originally async */ {
   final asy::_AsyncAwaitCompleter<core::int*>* :async_completer = new asy::_AsyncAwaitCompleter::•<core::int*>();
diff --git a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.outline.expect b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.outline.expect
index a8a37bc..ee3138c 100644
--- a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method g1(core::bool* x) → asy::Future<core::int*>*
   ;
diff --git a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.expect b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.expect
index e226a22..3bcd4ca 100644
--- a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method g1(core::bool* x) → asy::Future<core::int*>* async {
   return (x ?{core::Object*} 42 : new self::MyFuture::value<core::int*>(42)) as{TypeError} asy::FutureOr<core::int*>*;
diff --git a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.transformed.expect
index 46ac20c..1812257 100644
--- a/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_union_async_conditional_2.dart.strong.transformed.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static method g1(core::bool* x) → asy::Future<core::int*>* /* originally async */ {
   final asy::_AsyncAwaitCompleter<core::int*>* :async_completer = new asy::_AsyncAwaitCompleter::•<core::int*>();
diff --git a/pkg/front_end/testcases/inference/future_union_downwards.dart.outline.expect b/pkg/front_end/testcases/inference/future_union_downwards.dart.outline.expect
index 1fefba5..9065bcf 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field self::MyFuture<dynamic>* f;
 static field asy::Future<core::int*>* t1;
diff --git a/pkg/front_end/testcases/inference/future_union_downwards.dart.strong.expect b/pkg/front_end/testcases/inference/future_union_downwards.dart.strong.expect
index 8c541ca..b1f9997 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards.dart.strong.expect
@@ -23,13 +23,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field self::MyFuture<dynamic>* f;
 static field asy::Future<core::int*>* t1 = self::f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* => asy::Future::value<core::int*>(let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/inference/future_union_downwards.dart:21:47: Error: The argument type 'String' can't be assigned to the parameter type 'FutureOr<int>'.
diff --git a/pkg/front_end/testcases/inference/future_union_downwards.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_union_downwards.dart.strong.transformed.expect
index 2819009..829fcb3 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards.dart.strong.transformed.expect
@@ -23,13 +23,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field self::MyFuture<dynamic>* f;
 static field asy::Future<core::int*>* t1 = self::f.{self::MyFuture::then}<core::int*>((dynamic _) → asy::Future<core::int*>* => asy::Future::value<core::int*>(let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/inference/future_union_downwards.dart:21:47: Error: The argument type 'String' can't be assigned to the parameter type 'FutureOr<int>'.
diff --git a/pkg/front_end/testcases/inference/future_union_downwards_2.dart.outline.expect b/pkg/front_end/testcases/inference/future_union_downwards_2.dart.outline.expect
index 1fefba5..9065bcf 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards_2.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards_2.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field self::MyFuture<dynamic>* f;
 static field asy::Future<core::int*>* t1;
diff --git a/pkg/front_end/testcases/inference/future_union_downwards_2.dart.strong.expect b/pkg/front_end/testcases/inference/future_union_downwards_2.dart.strong.expect
index 7b7bf16..2b84966 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards_2.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards_2.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field self::MyFuture<dynamic>* f;
 static field asy::Future<core::int*>* t1 = self::f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* => new self::MyFuture::value<core::int*>("hi"));
diff --git a/pkg/front_end/testcases/inference/future_union_downwards_2.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_union_downwards_2.dart.strong.transformed.expect
index e4688e7..a99851d 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards_2.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards_2.dart.strong.transformed.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field self::MyFuture<dynamic>* f;
 static field asy::Future<core::int*>* t1 = self::f.{self::MyFuture::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* => new self::MyFuture::value<core::int*>("hi"));
diff --git a/pkg/front_end/testcases/inference/future_union_downwards_3.dart.outline.expect b/pkg/front_end/testcases/inference/future_union_downwards_3.dart.outline.expect
index 239aaa9..ff2fae926 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards_3.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards_3.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field asy::Future<dynamic>* f;
 static field asy::Future<core::int*>* t1;
diff --git a/pkg/front_end/testcases/inference/future_union_downwards_3.dart.strong.expect b/pkg/front_end/testcases/inference/future_union_downwards_3.dart.strong.expect
index a309a4b..125547e 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards_3.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards_3.dart.strong.expect
@@ -23,13 +23,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field asy::Future<dynamic>* f;
 static field asy::Future<core::int*>* t1 = self::f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* => asy::Future::value<core::int*>(let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/inference/future_union_downwards_3.dart:21:47: Error: The argument type 'String' can't be assigned to the parameter type 'FutureOr<int>'.
diff --git a/pkg/front_end/testcases/inference/future_union_downwards_3.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_union_downwards_3.dart.strong.transformed.expect
index daeed90..585b9a59 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards_3.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards_3.dart.strong.transformed.expect
@@ -23,13 +23,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field asy::Future<dynamic>* f;
 static field asy::Future<core::int*>* t1 = self::f.{asy::Future::then}<core::int*>((dynamic _) → asy::Future<core::int*>* => asy::Future::value<core::int*>(let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/inference/future_union_downwards_3.dart:21:47: Error: The argument type 'String' can't be assigned to the parameter type 'FutureOr<int>'.
diff --git a/pkg/front_end/testcases/inference/future_union_downwards_4.dart.outline.expect b/pkg/front_end/testcases/inference/future_union_downwards_4.dart.outline.expect
index 239aaa9..ff2fae926 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards_4.dart.outline.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards_4.dart.outline.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError}) → self::MyFuture<self::MyFuture::then::S*>*
     ;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#catchError, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#test: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#whenComplete, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#timeout, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#onTimeout: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#asStream, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field asy::Future<dynamic>* f;
 static field asy::Future<core::int*>* t1;
diff --git a/pkg/front_end/testcases/inference/future_union_downwards_4.dart.strong.expect b/pkg/front_end/testcases/inference/future_union_downwards_4.dart.strong.expect
index 44c27d7..e4e496c 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards_4.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards_4.dart.strong.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field asy::Future<dynamic>* f;
 static field asy::Future<core::int*>* t1 = self::f.{asy::Future::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* => new self::MyFuture::value<core::int*>("hi"));
diff --git a/pkg/front_end/testcases/inference/future_union_downwards_4.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/future_union_downwards_4.dart.strong.transformed.expect
index 7bd9b40..7448b01 100644
--- a/pkg/front_end/testcases/inference/future_union_downwards_4.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/future_union_downwards_4.dart.strong.transformed.expect
@@ -15,13 +15,13 @@
   method then<S extends core::Object* = dynamic>((self::MyFuture::T*) →* asy::FutureOr<self::MyFuture::then::S*>* f, {core::Function* onError = #C1}) → self::MyFuture<self::MyFuture::then::S*>*
     return null;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ catchError(core::Function* onError, {(core::Object*) →* core::bool* test = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[onError]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C4: test}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ whenComplete(() →* asy::FutureOr<dynamic>* action) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[action]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ timeout(core::Duration* timeLimit, {generic-covariant-impl () →* asy::FutureOr<self::MyFuture::T*>* onTimeout = #C1}) → asy::Future<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError} asy::Future<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C8, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[timeLimit]), core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C9: onTimeout}))) as{TypeError,ForDynamic} asy::Future<self::MyFuture::T*>*;
   no-such-method-forwarder method /* from org-dartlang-sdk:///sdk/lib/async/future.dart */ asStream() → asy::Stream<self::MyFuture::T*>*
-    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError} asy::Stream<self::MyFuture::T*>*;
+    return this.{self::MyFuture::noSuchMethod}(new core::_InvocationMirror::_withType(#C10, 0, #C3, #C6, core::Map::unmodifiable<core::Symbol*, dynamic>(#C7))) as{TypeError,ForDynamic} asy::Stream<self::MyFuture::T*>*;
 }
 static field asy::Future<dynamic>* f;
 static field asy::Future<core::int*>* t1 = self::f.{asy::Future::then}<core::int*>((dynamic _) → self::MyFuture<core::int*>* => new self::MyFuture::value<core::int*>("hi"));
diff --git a/pkg/front_end/testcases/inference/generic_methods_do_not_infer_invalid_override_of_generic_method.dart.strong.expect b/pkg/front_end/testcases/inference/generic_methods_do_not_infer_invalid_override_of_generic_method.dart.strong.expect
index 4bc55c2..b4da5d7 100644
--- a/pkg/front_end/testcases/inference/generic_methods_do_not_infer_invalid_override_of_generic_method.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/generic_methods_do_not_infer_invalid_override_of_generic_method.dart.strong.expect
@@ -39,6 +39,6 @@
     return x;
 }
 static method main() → dynamic {
-  core::int* y = new self::D::•().{self::D::m}<core::int*>(42) as{TypeError} core::int*;
+  core::int* y = new self::D::•().{self::D::m}<core::int*>(42) as{TypeError,ForDynamic} core::int*;
   core::print(y);
 }
diff --git a/pkg/front_end/testcases/inference/generic_methods_downwards_inference_fold.dart.strong.expect b/pkg/front_end/testcases/inference/generic_methods_downwards_inference_fold.dart.strong.expect
index 7eb5d33..dcb7d1d 100644
--- a/pkg/front_end/testcases/inference/generic_methods_downwards_inference_fold.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/generic_methods_downwards_inference_fold.dart.strong.expect
@@ -6,12 +6,12 @@
   core::List<core::int*>* o;
   core::int* y = o.{core::Iterable::fold}<core::int*>(0, (core::int* x, core::int* y) → core::int* => x.{core::num::+}(y));
   dynamic z = o.{core::Iterable::fold}<dynamic>(0, (dynamic x, core::int* y) → dynamic => x.+(y));
-  y = z as{TypeError} core::int*;
+  y = z as{TypeError,ForDynamic} core::int*;
 }
 static method functionExpressionInvocation() → void {
   core::List<core::int*>* o;
   core::int* y = o.{core::Iterable::fold}.call<core::int*>(0, (core::int* x, core::int* y) → core::int* => x.{core::num::+}(y));
   dynamic z = o.{core::Iterable::fold}.call<dynamic>(0, (dynamic x, core::int* y) → dynamic => x.+(y));
-  y = z as{TypeError} core::int*;
+  y = z as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/generic_methods_downwards_inference_fold.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/generic_methods_downwards_inference_fold.dart.strong.transformed.expect
index 7eb5d33..dcb7d1d 100644
--- a/pkg/front_end/testcases/inference/generic_methods_downwards_inference_fold.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/generic_methods_downwards_inference_fold.dart.strong.transformed.expect
@@ -6,12 +6,12 @@
   core::List<core::int*>* o;
   core::int* y = o.{core::Iterable::fold}<core::int*>(0, (core::int* x, core::int* y) → core::int* => x.{core::num::+}(y));
   dynamic z = o.{core::Iterable::fold}<dynamic>(0, (dynamic x, core::int* y) → dynamic => x.+(y));
-  y = z as{TypeError} core::int*;
+  y = z as{TypeError,ForDynamic} core::int*;
 }
 static method functionExpressionInvocation() → void {
   core::List<core::int*>* o;
   core::int* y = o.{core::Iterable::fold}.call<core::int*>(0, (core::int* x, core::int* y) → core::int* => x.{core::num::+}(y));
   dynamic z = o.{core::Iterable::fold}.call<dynamic>(0, (dynamic x, core::int* y) → dynamic => x.+(y));
-  y = z as{TypeError} core::int*;
+  y = z as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/generic_methods_handle_override_of_non_generic_with_generic.dart.strong.expect b/pkg/front_end/testcases/inference/generic_methods_handle_override_of_non_generic_with_generic.dart.strong.expect
index dffe5df..1988b92 100644
--- a/pkg/front_end/testcases/inference/generic_methods_handle_override_of_non_generic_with_generic.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/generic_methods_handle_override_of_non_generic_with_generic.dart.strong.expect
@@ -54,6 +54,6 @@
     return x;
 }
 static method main() → dynamic {
-  core::int* y = (new self::D::•() as self::C*).{self::C::m}(42) as{TypeError} core::int*;
+  core::int* y = (new self::D::•() as self::C*).{self::C::m}(42) as{TypeError,ForDynamic} core::int*;
   core::print(y);
 }
diff --git a/pkg/front_end/testcases/inference/generic_methods_iterable_and_future.dart.strong.expect b/pkg/front_end/testcases/inference/generic_methods_iterable_and_future.dart.strong.expect
index 7967409..05abfab 100644
--- a/pkg/front_end/testcases/inference/generic_methods_iterable_and_future.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/generic_methods_iterable_and_future.dart.strong.expect
@@ -28,7 +28,7 @@
  - 'FutureOr' is from 'dart:async'.
 Try correcting the name to the name of an existing method, or defining a method named '+'.
                           /*@ type=int* */ y) => /*info:DYNAMIC_CAST,info:DYNAMIC_INVOKE*/ x /*error:UNDEFINED_OPERATOR*/ +
-                                                                                                                          ^" as{TypeError} asy::FutureOr<core::String*>*));
+                                                                                                                          ^" as{TypeError,ForDynamic} asy::FutureOr<core::String*>*));
   asy::Future<core::String*>* results3 = results.{asy::Future::then}<core::String*>((core::List<core::int*>* list) → asy::FutureOr<core::String*>* => list.{core::Iterable::fold}<asy::FutureOr<core::String*>*>("", let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/inference/generic_methods_iterable_and_future.dart:31:111: Error: The argument type 'String Function(String, int)' can't be assigned to the parameter type 'FutureOr<String> Function(FutureOr<String>, int)'.
  - 'FutureOr' is from 'dart:async'.
                   /*info:INFERRED_TYPE_CLOSURE,error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/ /*@ returnType=String* */ (String
diff --git a/pkg/front_end/testcases/inference/generic_methods_iterable_and_future.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/generic_methods_iterable_and_future.dart.strong.transformed.expect
index 7967409..05abfab 100644
--- a/pkg/front_end/testcases/inference/generic_methods_iterable_and_future.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/generic_methods_iterable_and_future.dart.strong.transformed.expect
@@ -28,7 +28,7 @@
  - 'FutureOr' is from 'dart:async'.
 Try correcting the name to the name of an existing method, or defining a method named '+'.
                           /*@ type=int* */ y) => /*info:DYNAMIC_CAST,info:DYNAMIC_INVOKE*/ x /*error:UNDEFINED_OPERATOR*/ +
-                                                                                                                          ^" as{TypeError} asy::FutureOr<core::String*>*));
+                                                                                                                          ^" as{TypeError,ForDynamic} asy::FutureOr<core::String*>*));
   asy::Future<core::String*>* results3 = results.{asy::Future::then}<core::String*>((core::List<core::int*>* list) → asy::FutureOr<core::String*>* => list.{core::Iterable::fold}<asy::FutureOr<core::String*>*>("", let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/inference/generic_methods_iterable_and_future.dart:31:111: Error: The argument type 'String Function(String, int)' can't be assigned to the parameter type 'FutureOr<String> Function(FutureOr<String>, int)'.
  - 'FutureOr' is from 'dart:async'.
                   /*info:INFERRED_TYPE_CLOSURE,error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/ /*@ returnType=String* */ (String
diff --git a/pkg/front_end/testcases/inference/infer_accessor_from_later_inferred_field.dart.strong.expect b/pkg/front_end/testcases/inference/infer_accessor_from_later_inferred_field.dart.strong.expect
index 1abf208..e2271dd 100644
--- a/pkg/front_end/testcases/inference/infer_accessor_from_later_inferred_field.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/infer_accessor_from_later_inferred_field.dart.strong.expect
@@ -7,7 +7,7 @@
     : super core::Object::•()
     ;
   get x() → core::int*
-    return self::f() as{TypeError} core::int*;
+    return self::f() as{TypeError,ForDynamic} core::int*;
   set x(core::int* value) → void {}
 }
 class B extends core::Object {
diff --git a/pkg/front_end/testcases/inference/infer_accessor_from_later_inferred_field.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/infer_accessor_from_later_inferred_field.dart.strong.transformed.expect
index 1abf208..e2271dd 100644
--- a/pkg/front_end/testcases/inference/infer_accessor_from_later_inferred_field.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/infer_accessor_from_later_inferred_field.dart.strong.transformed.expect
@@ -7,7 +7,7 @@
     : super core::Object::•()
     ;
   get x() → core::int*
-    return self::f() as{TypeError} core::int*;
+    return self::f() as{TypeError,ForDynamic} core::int*;
   set x(core::int* value) → void {}
 }
 class B extends core::Object {
diff --git a/pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart.strong.expect b/pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart.strong.expect
index bb7d545..93b3edc 100644
--- a/pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart.strong.expect
@@ -37,7 +37,7 @@
 static method foo() → dynamic {
   core::String* s;
   core::int* i;
-  s = new self::B::•().{self::B::x} as{TypeError} core::String*;
+  s = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::String*;
   s = let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart:21:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   s = /*error:INVALID_ASSIGNMENT*/ new B(). /*@target=B::y*/ y;
                                                              ^" in new self::B::•().{self::B::y} as{TypeError} core::String*;
@@ -45,7 +45,7 @@
   s = let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart:23:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   s = /*error:INVALID_ASSIGNMENT*/ new B(). /*@target=B::w*/ w;
                                                              ^" in new self::B::•().{self::B::w} as{TypeError} core::String*;
-  i = new self::B::•().{self::B::x} as{TypeError} core::int*;
+  i = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::int*;
   i = new self::B::•().{self::B::y};
   i = let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart:27:62: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   i = /*error:INVALID_ASSIGNMENT*/ new B(). /*@target=B::z*/ z;
diff --git a/pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart.strong.transformed.expect
index bb7d545..93b3edc 100644
--- a/pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart.strong.transformed.expect
@@ -37,7 +37,7 @@
 static method foo() → dynamic {
   core::String* s;
   core::int* i;
-  s = new self::B::•().{self::B::x} as{TypeError} core::String*;
+  s = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::String*;
   s = let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart:21:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   s = /*error:INVALID_ASSIGNMENT*/ new B(). /*@target=B::y*/ y;
                                                              ^" in new self::B::•().{self::B::y} as{TypeError} core::String*;
@@ -45,7 +45,7 @@
   s = let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart:23:62: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
   s = /*error:INVALID_ASSIGNMENT*/ new B(). /*@target=B::w*/ w;
                                                              ^" in new self::B::•().{self::B::w} as{TypeError} core::String*;
-  i = new self::B::•().{self::B::x} as{TypeError} core::int*;
+  i = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::int*;
   i = new self::B::•().{self::B::y};
   i = let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/inference/infer_correctly_on_multiple_variables_declared_together.dart:27:62: Error: A value of type 'String' can't be assigned to a variable of type 'int'.
   i = /*error:INVALID_ASSIGNMENT*/ new B(). /*@target=B::z*/ z;
diff --git a/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields.dart.strong.expect b/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields.dart.strong.expect
index 077060d..0b8b396 100644
--- a/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields.dart.strong.expect
@@ -15,7 +15,7 @@
     ;
 }
 static method foo() → dynamic {
-  core::String* y = new self::B::•().{self::B::x} as{TypeError} core::String*;
-  core::int* z = new self::B::•().{self::B::x} as{TypeError} core::int*;
+  core::String* y = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::String*;
+  core::int* z = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields.dart.strong.transformed.expect
index 077060d..0b8b396 100644
--- a/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields.dart.strong.transformed.expect
@@ -15,7 +15,7 @@
     ;
 }
 static method foo() → dynamic {
-  core::String* y = new self::B::•().{self::B::x} as{TypeError} core::String*;
-  core::int* z = new self::B::•().{self::B::x} as{TypeError} core::int*;
+  core::String* y = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::String*;
+  core::int* z = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields2.dart.strong.expect b/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields2.dart.strong.expect
index 43604a1..3a5f33d 100644
--- a/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields2.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields2.dart.strong.expect
@@ -15,7 +15,7 @@
     ;
 }
 static method foo() → dynamic {
-  core::String* y = new self::B::•().{self::B::x} as{TypeError} core::String*;
-  core::int* z = new self::B::•().{self::B::x} as{TypeError} core::int*;
+  core::String* y = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::String*;
+  core::int* z = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields2.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields2.dart.strong.transformed.expect
index 43604a1..3a5f33d 100644
--- a/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields2.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/infer_from_rhs_only_if_it_wont_conflict_with_overridden_fields2.dart.strong.transformed.expect
@@ -15,7 +15,7 @@
     ;
 }
 static method foo() → dynamic {
-  core::String* y = new self::B::•().{self::B::x} as{TypeError} core::String*;
-  core::int* z = new self::B::•().{self::B::x} as{TypeError} core::int*;
+  core::String* y = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::String*;
+  core::int* z = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/infer_getter_from_later_inferred_getter.dart.strong.expect b/pkg/front_end/testcases/inference/infer_getter_from_later_inferred_getter.dart.strong.expect
index 0ab7323..1611ea4 100644
--- a/pkg/front_end/testcases/inference/infer_getter_from_later_inferred_getter.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/infer_getter_from_later_inferred_getter.dart.strong.expect
@@ -7,7 +7,7 @@
     : super core::Object::•()
     ;
   get x() → core::int*
-    return self::f() as{TypeError} core::int*;
+    return self::f() as{TypeError,ForDynamic} core::int*;
 }
 abstract class B extends core::Object implements self::C {
   synthetic constructor •() → self::B*
diff --git a/pkg/front_end/testcases/inference/infer_getter_from_later_inferred_getter.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/infer_getter_from_later_inferred_getter.dart.strong.transformed.expect
index 0ab7323..1611ea4 100644
--- a/pkg/front_end/testcases/inference/infer_getter_from_later_inferred_getter.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/infer_getter_from_later_inferred_getter.dart.strong.transformed.expect
@@ -7,7 +7,7 @@
     : super core::Object::•()
     ;
   get x() → core::int*
-    return self::f() as{TypeError} core::int*;
+    return self::f() as{TypeError,ForDynamic} core::int*;
 }
 abstract class B extends core::Object implements self::C {
   synthetic constructor •() → self::B*
diff --git a/pkg/front_end/testcases/inference/infer_types_on_generic_instantiations_infer.dart.strong.expect b/pkg/front_end/testcases/inference/infer_types_on_generic_instantiations_infer.dart.strong.expect
index 8038d01..dc05112 100644
--- a/pkg/front_end/testcases/inference/infer_types_on_generic_instantiations_infer.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/infer_types_on_generic_instantiations_infer.dart.strong.expect
@@ -27,8 +27,8 @@
     return 3;
 }
 static method foo() → dynamic {
-  core::String* y = new self::B::•().{self::B::x} as{TypeError} core::String*;
-  core::int* z = new self::B::•().{self::B::x} as{TypeError} core::int*;
+  core::String* y = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::String*;
+  core::int* z = new self::B::•().{self::B::x} as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {
   self::foo();
diff --git a/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop.dart.strong.expect b/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop.dart.strong.expect
index 12a0f49..a073b10 100644
--- a/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop.dart.strong.expect
@@ -71,7 +71,7 @@
                                             ^" in x as{TypeError} core::String*;
   }
   for (dynamic x in list) {
-    core::String* y = x as{TypeError} core::String*;
+    core::String* y = x as{TypeError,ForDynamic} core::String*;
   }
   for (final self::Foo* #t4 in list) {
     core::String* x = let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop.dart:39:15: Error: A value of type 'Foo' can't be assigned to a variable of type 'String'.
@@ -84,16 +84,16 @@
   dynamic z;
   for (final self::Foo* #t6 in list) {
     z = #t6;
-    core::String* y = z as{TypeError} core::String*;
+    core::String* y = z as{TypeError,ForDynamic} core::String*;
   }
   core::Iterable<dynamic>* iter = list;
   for (final dynamic #t7 in iter) {
-    self::Foo* x = #t7 as{TypeError} self::Foo*;
+    self::Foo* x = #t7 as{TypeError,ForDynamic} self::Foo*;
     self::Foo* y = x;
   }
   dynamic iter2 = list;
-  for (final dynamic #t8 in iter2 as{TypeError} core::Iterable<dynamic>*) {
-    self::Foo* x = #t8 as{TypeError} self::Foo*;
+  for (final dynamic #t8 in iter2 as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
+    self::Foo* x = #t8 as{TypeError,ForDynamic} self::Foo*;
     self::Foo* y = x;
   }
   core::Map<core::String*, self::Foo*>* map = <core::String*, self::Foo*>{};
@@ -103,7 +103,7 @@
  - 'Iterable' is from 'dart:core'.
   for (var /*@ type=dynamic */ x in /*error:FOR_IN_OF_INVALID_TYPE*/ map) {
                                                                      ^" in map as{TypeError} core::Iterable<dynamic>*) {
-    core::String* y = x as{TypeError} core::String*;
+    core::String* y = x as{TypeError,ForDynamic} core::String*;
   }
   for (core::String* x in map.{core::Map::keys}) {
     core::String* y = x;
diff --git a/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop.dart.strong.transformed.expect
index 67247a8..8b874fc 100644
--- a/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop.dart.strong.transformed.expect
@@ -94,7 +94,7 @@
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       dynamic x = :sync-for-iterator.{core::Iterator::current};
       {
-        core::String* y = x as{TypeError} core::String*;
+        core::String* y = x as{TypeError,ForDynamic} core::String*;
       }
     }
   }
@@ -119,7 +119,7 @@
       final self::Foo* #t6 = :sync-for-iterator.{core::Iterator::current};
       {
         z = #t6;
-        core::String* y = z as{TypeError} core::String*;
+        core::String* y = z as{TypeError,ForDynamic} core::String*;
       }
     }
   }
@@ -129,18 +129,18 @@
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t7 = :sync-for-iterator.{core::Iterator::current};
       {
-        self::Foo* x = #t7 as{TypeError} self::Foo*;
+        self::Foo* x = #t7 as{TypeError,ForDynamic} self::Foo*;
         self::Foo* y = x;
       }
     }
   }
   dynamic iter2 = list;
   {
-    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(iter2 as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(iter2 as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t8 = :sync-for-iterator.{core::Iterator::current};
       {
-        self::Foo* x = #t8 as{TypeError} self::Foo*;
+        self::Foo* x = #t8 as{TypeError,ForDynamic} self::Foo*;
         self::Foo* y = x;
       }
     }
@@ -156,7 +156,7 @@
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       dynamic x = :sync-for-iterator.{core::Iterator::current};
       {
-        core::String* y = x as{TypeError} core::String*;
+        core::String* y = x as{TypeError,ForDynamic} core::String*;
       }
     }
   }
diff --git a/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop_async.dart.strong.expect b/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop_async.dart.strong.expect
index ab6817c..ba99001 100644
--- a/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop_async.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop_async.dart.strong.expect
@@ -78,7 +78,7 @@
                                             ^" in x as{TypeError} core::String*;
   }
   await for (dynamic x in myStream) {
-    core::String* y = x as{TypeError} core::String*;
+    core::String* y = x as{TypeError,ForDynamic} core::String*;
   }
   await for (final self::Foo* #t4 in myStream) {
     core::String* x = let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop_async.dart:45:21: Error: A value of type 'Foo' can't be assigned to a variable of type 'String'.
@@ -91,16 +91,16 @@
   dynamic z;
   await for (final self::Foo* #t6 in myStream) {
     z = #t6;
-    core::String* y = z as{TypeError} core::String*;
+    core::String* y = z as{TypeError,ForDynamic} core::String*;
   }
   asy::Stream<dynamic>* stream = myStream;
   await for (final dynamic #t7 in stream) {
-    self::Foo* x = #t7 as{TypeError} self::Foo*;
+    self::Foo* x = #t7 as{TypeError,ForDynamic} self::Foo*;
     self::Foo* y = x;
   }
   dynamic stream2 = myStream;
-  await for (final dynamic #t8 in stream2 as{TypeError} asy::Stream<dynamic>*) {
-    self::Foo* x = #t8 as{TypeError} self::Foo*;
+  await for (final dynamic #t8 in stream2 as{TypeError,ForDynamic} asy::Stream<dynamic>*) {
+    self::Foo* x = #t8 as{TypeError,ForDynamic} self::Foo*;
     self::Foo* y = x;
   }
   core::Map<core::String*, self::Foo*>* map = <core::String*, self::Foo*>{};
@@ -110,7 +110,7 @@
  - 'Stream' is from 'dart:async'.
   await for (var /*@ type=dynamic */ x in /*error:FOR_IN_OF_INVALID_TYPE*/ map) {
                                                                            ^" in map as{TypeError} asy::Stream<dynamic>*) {
-    core::String* y = x as{TypeError} core::String*;
+    core::String* y = x as{TypeError,ForDynamic} core::String*;
   }
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop_async.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop_async.dart.strong.transformed.expect
index 7fe8c70..7f3335c 100644
--- a/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop_async.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/infer_types_on_loop_indices_for_each_loop_async.dart.strong.transformed.expect
@@ -222,7 +222,7 @@
               if(_in::unsafeCast<core::bool*>(:result)) {
                 dynamic x = :for-iterator.{asy::_StreamIterator::current};
                 {
-                  core::String* y = x as{TypeError} core::String*;
+                  core::String* y = x as{TypeError,ForDynamic} core::String*;
                 }
               }
               else
@@ -277,7 +277,7 @@
                 final self::Foo* #t23 = :for-iterator.{asy::_StreamIterator::current};
                 {
                   z = #t23;
-                  core::String* y = z as{TypeError} core::String*;
+                  core::String* y = z as{TypeError,ForDynamic} core::String*;
                 }
               }
               else
@@ -302,7 +302,7 @@
               if(_in::unsafeCast<core::bool*>(:result)) {
                 final dynamic #t27 = :for-iterator.{asy::_StreamIterator::current};
                 {
-                  self::Foo* x = #t27 as{TypeError} self::Foo*;
+                  self::Foo* x = #t27 as{TypeError,ForDynamic} self::Foo*;
                   self::Foo* y = x;
                 }
               }
@@ -317,7 +317,7 @@
         }
         dynamic stream2 = myStream;
         {
-          dynamic :stream = stream2 as{TypeError} asy::Stream<dynamic>*;
+          dynamic :stream = stream2 as{TypeError,ForDynamic} asy::Stream<dynamic>*;
           asy::_asyncStarListenHelper(:stream, :async_op);
           asy::_StreamIterator<dynamic>* :for-iterator = new asy::_StreamIterator::•<dynamic>(:stream);
           try
@@ -328,7 +328,7 @@
               if(_in::unsafeCast<core::bool*>(:result)) {
                 final dynamic #t31 = :for-iterator.{asy::_StreamIterator::current};
                 {
-                  self::Foo* x = #t31 as{TypeError} self::Foo*;
+                  self::Foo* x = #t31 as{TypeError,ForDynamic} self::Foo*;
                   self::Foo* y = x;
                 }
               }
@@ -359,7 +359,7 @@
               if(_in::unsafeCast<core::bool*>(:result)) {
                 dynamic x = :for-iterator.{asy::_StreamIterator::current};
                 {
-                  core::String* y = x as{TypeError} core::String*;
+                  core::String* y = x as{TypeError,ForDynamic} core::String*;
                 }
               }
               else
diff --git a/pkg/front_end/testcases/inference/instantiate_tearoff_after_contravariance_check.dart.strong.expect b/pkg/front_end/testcases/inference/instantiate_tearoff_after_contravariance_check.dart.strong.expect
index 4d47083..82851a6 100644
--- a/pkg/front_end/testcases/inference/instantiate_tearoff_after_contravariance_check.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/instantiate_tearoff_after_contravariance_check.dart.strong.expect
@@ -10,6 +10,6 @@
     return (self::C::T* y) → core::Null? {};
 }
 static method test(self::C<core::String*>* c) → void {
-  (core::int*) →* (core::String*) →* void tearoff = c.{self::C::f} as{TypeError} <U extends core::Object* = dynamic>(U*) →* (core::String*) →* void<core::int*>;
+  (core::int*) →* (core::String*) →* void tearoff = c.{self::C::f} as{TypeError,CovarianceCheck} <U extends core::Object* = dynamic>(U*) →* (core::String*) →* void<core::int*>;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/instantiate_tearoff_after_contravariance_check.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/instantiate_tearoff_after_contravariance_check.dart.strong.transformed.expect
index 4d47083..82851a6 100644
--- a/pkg/front_end/testcases/inference/instantiate_tearoff_after_contravariance_check.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/instantiate_tearoff_after_contravariance_check.dart.strong.transformed.expect
@@ -10,6 +10,6 @@
     return (self::C::T* y) → core::Null? {};
 }
 static method test(self::C<core::String*>* c) → void {
-  (core::int*) →* (core::String*) →* void tearoff = c.{self::C::f} as{TypeError} <U extends core::Object* = dynamic>(U*) →* (core::String*) →* void<core::int*>;
+  (core::int*) →* (core::String*) →* void tearoff = c.{self::C::f} as{TypeError,CovarianceCheck} <U extends core::Object* = dynamic>(U*) →* (core::String*) →* void<core::int*>;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class_dynamic_warnings.dart.strong.expect b/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class_dynamic_warnings.dart.strong.expect
index 29d7a60..8c5aa72 100644
--- a/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class_dynamic_warnings.dart.strong.expect
+++ b/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class_dynamic_warnings.dart.strong.expect
@@ -10,7 +10,7 @@
 }
 static method main() → dynamic {
   dynamic a = new self::A::•();
-  self::A* b = a as{TypeError} self::A*;
+  self::A* b = a as{TypeError,ForDynamic} self::A*;
   core::print(a.x);
   core::print(a.x.+(2));
 }
diff --git a/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class_dynamic_warnings.dart.strong.transformed.expect b/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class_dynamic_warnings.dart.strong.transformed.expect
index 29d7a60..8c5aa72 100644
--- a/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class_dynamic_warnings.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class_dynamic_warnings.dart.strong.transformed.expect
@@ -10,7 +10,7 @@
 }
 static method main() → dynamic {
   dynamic a = new self::A::•();
-  self::A* b = a as{TypeError} self::A*;
+  self::A* b = a as{TypeError,ForDynamic} self::A*;
   core::print(a.x);
   core::print(a.x.+(2));
 }
diff --git a/pkg/front_end/testcases/inference_new/dependency_only_if_overloaded.dart.strong.expect b/pkg/front_end/testcases/inference_new/dependency_only_if_overloaded.dart.strong.expect
index 3fb8cb6..2620e6d 100644
--- a/pkg/front_end/testcases/inference_new/dependency_only_if_overloaded.dart.strong.expect
+++ b/pkg/front_end/testcases/inference_new/dependency_only_if_overloaded.dart.strong.expect
@@ -13,7 +13,7 @@
 static field core::int* intValue = 0;
 static field core::num* numValue = 0;
 static field core::double* doubleValue = 0.0;
-static field invalid-type a = (() → core::num* => self::intValue.{core::num::+}(self::b as{TypeError} core::num*)) as{TypeError} invalid-type;
+static field invalid-type a = (() → core::num* => self::intValue.{core::num::+}(self::b as{TypeError,ForDynamic} core::num*)) as{TypeError} invalid-type;
 static field dynamic b = self::a.call();
 static field () →* core::num* c = () → core::num* => self::numValue.{core::num::+}(self::d);
 static field core::num* d = self::c.call();
diff --git a/pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart.strong.expect b/pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart.strong.expect
index 13e6c5e..970333f 100644
--- a/pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart.strong.expect
+++ b/pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart.strong.expect
@@ -32,26 +32,26 @@
  - 'Iterable' is from 'dart:core'.
   for (int x in s) {}
                 ^" in s as{TypeError} core::Iterable<dynamic>*) {
-    core::int* x = #t1 as{TypeError} core::int*;
+    core::int* x = #t1 as{TypeError,ForDynamic} core::int*;
   }
   await for (final dynamic #t3 in let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart:11:23: Error: The type 'String' used in the 'for' loop must implement 'Stream<dynamic>'.
  - 'Stream' is from 'dart:async'.
   await for (int x in s) {}
                       ^" in s as{TypeError} asy::Stream<dynamic>*) {
-    core::int* x = #t3 as{TypeError} core::int*;
+    core::int* x = #t3 as{TypeError,ForDynamic} core::int*;
   }
   core::int* y;
   for (final dynamic #t5 in let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart:13:13: Error: The type 'String' used in the 'for' loop must implement 'Iterable<dynamic>'.
  - 'Iterable' is from 'dart:core'.
   for (y in s) {}
             ^" in s as{TypeError} core::Iterable<dynamic>*) {
-    y = #t5 as{TypeError} core::int*;
+    y = #t5 as{TypeError,ForDynamic} core::int*;
   }
   await for (final dynamic #t7 in let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart:14:19: Error: The type 'String' used in the 'for' loop must implement 'Stream<dynamic>'.
  - 'Stream' is from 'dart:async'.
   await for (y in s) {}
                   ^" in s as{TypeError} asy::Stream<dynamic>*) {
-    y = #t7 as{TypeError} core::int*;
+    y = #t7 as{TypeError,ForDynamic} core::int*;
   }
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart.strong.transformed.expect b/pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart.strong.transformed.expect
index 367cb2e..796c34d 100644
--- a/pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/inference_new/for_each_invalid_iterable.dart.strong.transformed.expect
@@ -52,7 +52,7 @@
           for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
             final dynamic #t2 = :sync-for-iterator.{core::Iterator::current};
             {
-              core::int* x = #t2 as{TypeError} core::int*;
+              core::int* x = #t2 as{TypeError,ForDynamic} core::int*;
             }
           }
         }
@@ -71,7 +71,7 @@
               if(_in::unsafeCast<core::bool*>(:result)) {
                 final dynamic #t6 = :for-iterator.{asy::_StreamIterator::current};
                 {
-                  core::int* x = #t6 as{TypeError} core::int*;
+                  core::int* x = #t6 as{TypeError,ForDynamic} core::int*;
                 }
               }
               else
@@ -92,7 +92,7 @@
           for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
             final dynamic #t9 = :sync-for-iterator.{core::Iterator::current};
             {
-              y = #t9 as{TypeError} core::int*;
+              y = #t9 as{TypeError,ForDynamic} core::int*;
             }
           }
         }
@@ -111,7 +111,7 @@
               if(_in::unsafeCast<core::bool*>(:result)) {
                 final dynamic #t13 = :for-iterator.{asy::_StreamIterator::current};
                 {
-                  y = #t13 as{TypeError} core::int*;
+                  y = #t13 as{TypeError,ForDynamic} core::int*;
                 }
               }
               else
diff --git a/pkg/front_end/testcases/nnbd/assign_type_variable.dart b/pkg/front_end/testcases/nnbd/assign_type_variable.dart
new file mode 100644
index 0000000..e644495
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/assign_type_variable.dart
@@ -0,0 +1,21 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class Class<E> {
+  void method(E e) {
+    e = id(e);
+    e = id<E>(e);
+    if (e != null) {
+      var e2 = e;
+      e2 = id(e);
+      e2 = id<E>(e);
+      e2 = id(e2);
+      e2 = id<E>(e2);
+    }
+  }
+}
+
+T id<T>(T t) => t;
+
+main() {}
diff --git a/pkg/front_end/testcases/nnbd/assign_type_variable.dart.outline.expect b/pkg/front_end/testcases/nnbd/assign_type_variable.dart.outline.expect
new file mode 100644
index 0000000..0d12318
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/assign_type_variable.dart.outline.expect
@@ -0,0 +1,14 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class Class<E extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::Class<self::Class::E%>
+    ;
+  method method(generic-covariant-impl self::Class::E% e) → void
+    ;
+}
+static method id<T extends core::Object? = dynamic>(self::id::T% t) → self::id::T%
+  ;
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/nnbd/assign_type_variable.dart.strong.expect b/pkg/front_end/testcases/nnbd/assign_type_variable.dart.strong.expect
new file mode 100644
index 0000000..ee9e3f6
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/assign_type_variable.dart.strong.expect
@@ -0,0 +1,23 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class Class<E extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::Class<self::Class::E%>
+    : super core::Object::•()
+    ;
+  method method(generic-covariant-impl self::Class::E% e) → void {
+    e = self::id<self::Class::E%>(e);
+    e = self::id<self::Class::E%>(e);
+    if(!e.{core::Object::==}(null)) {
+      self::Class::E% e2 = e{self::Class::E% & core::Object /* '%' & '!' = '!' */};
+      e2 = self::id<self::Class::E%>(e{self::Class::E% & core::Object /* '%' & '!' = '!' */});
+      e2 = self::id<self::Class::E%>(e{self::Class::E% & core::Object /* '%' & '!' = '!' */});
+      e2 = self::id<self::Class::E%>(e2);
+      e2 = self::id<self::Class::E%>(e2);
+    }
+  }
+}
+static method id<T extends core::Object? = dynamic>(self::id::T% t) → self::id::T%
+  return t;
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/assign_type_variable.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/assign_type_variable.dart.strong.transformed.expect
new file mode 100644
index 0000000..ee9e3f6
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/assign_type_variable.dart.strong.transformed.expect
@@ -0,0 +1,23 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class Class<E extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::Class<self::Class::E%>
+    : super core::Object::•()
+    ;
+  method method(generic-covariant-impl self::Class::E% e) → void {
+    e = self::id<self::Class::E%>(e);
+    e = self::id<self::Class::E%>(e);
+    if(!e.{core::Object::==}(null)) {
+      self::Class::E% e2 = e{self::Class::E% & core::Object /* '%' & '!' = '!' */};
+      e2 = self::id<self::Class::E%>(e{self::Class::E% & core::Object /* '%' & '!' = '!' */});
+      e2 = self::id<self::Class::E%>(e{self::Class::E% & core::Object /* '%' & '!' = '!' */});
+      e2 = self::id<self::Class::E%>(e2);
+      e2 = self::id<self::Class::E%>(e2);
+    }
+  }
+}
+static method id<T extends core::Object? = dynamic>(self::id::T% t) → self::id::T%
+  return t;
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/assign_type_variable.dart.weak.expect b/pkg/front_end/testcases/nnbd/assign_type_variable.dart.weak.expect
new file mode 100644
index 0000000..ee9e3f6
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/assign_type_variable.dart.weak.expect
@@ -0,0 +1,23 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class Class<E extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::Class<self::Class::E%>
+    : super core::Object::•()
+    ;
+  method method(generic-covariant-impl self::Class::E% e) → void {
+    e = self::id<self::Class::E%>(e);
+    e = self::id<self::Class::E%>(e);
+    if(!e.{core::Object::==}(null)) {
+      self::Class::E% e2 = e{self::Class::E% & core::Object /* '%' & '!' = '!' */};
+      e2 = self::id<self::Class::E%>(e{self::Class::E% & core::Object /* '%' & '!' = '!' */});
+      e2 = self::id<self::Class::E%>(e{self::Class::E% & core::Object /* '%' & '!' = '!' */});
+      e2 = self::id<self::Class::E%>(e2);
+      e2 = self::id<self::Class::E%>(e2);
+    }
+  }
+}
+static method id<T extends core::Object? = dynamic>(self::id::T% t) → self::id::T%
+  return t;
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/assign_type_variable.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/assign_type_variable.dart.weak.transformed.expect
new file mode 100644
index 0000000..ee9e3f6
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/assign_type_variable.dart.weak.transformed.expect
@@ -0,0 +1,23 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class Class<E extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::Class<self::Class::E%>
+    : super core::Object::•()
+    ;
+  method method(generic-covariant-impl self::Class::E% e) → void {
+    e = self::id<self::Class::E%>(e);
+    e = self::id<self::Class::E%>(e);
+    if(!e.{core::Object::==}(null)) {
+      self::Class::E% e2 = e{self::Class::E% & core::Object /* '%' & '!' = '!' */};
+      e2 = self::id<self::Class::E%>(e{self::Class::E% & core::Object /* '%' & '!' = '!' */});
+      e2 = self::id<self::Class::E%>(e{self::Class::E% & core::Object /* '%' & '!' = '!' */});
+      e2 = self::id<self::Class::E%>(e2);
+      e2 = self::id<self::Class::E%>(e2);
+    }
+  }
+}
+static method id<T extends core::Object? = dynamic>(self::id::T% t) → self::id::T%
+  return t;
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/assignability.dart.strong.expect b/pkg/front_end/testcases/nnbd/assignability.dart.strong.expect
index 56f107d..803bc0a 100644
--- a/pkg/front_end/testcases/nnbd/assignability.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/assignability.dart.strong.expect
@@ -383,10 +383,9 @@
 //   functionVar = toVoidNullableArg;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/assignability.dart:202:3: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Function'.
-//  - 'Function' is from 'dart:core'.
+// pkg/front_end/testcases/nnbd/assignability.dart:202:17: Error: Can't tear off method 'call' from a potentially null value.
 //   functionVar = tearoffableNullableArg;
-//   ^
+//                 ^
 //
 // pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
 //  - 'Function' is from 'dart:core'.
@@ -476,9 +475,9 @@
 //   toVoidVar = toVoidNullableArg;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/assignability.dart:223:3: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
+// pkg/front_end/testcases/nnbd/assignability.dart:223:15: Error: Can't tear off method 'call' from a potentially null value.
 //   toVoidVar = tearoffableNullableArg;
-//   ^
+//               ^
 //
 // pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
 //   toVoidVar = xNonNullArg;
@@ -995,7 +994,7 @@
   dynamicVar = xPotentiallyNullArg;
   dynamicVar = yNonNullArg;
   dynamicVar = yPotentiallyNullArg;
-  core::Object objectVar = dynamicArg as{TypeError} core::Object;
+  core::Object objectVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::Object;
   objectVar = objectArg;
   objectVar = numArg;
   objectVar = intArg;
@@ -1004,789 +1003,788 @@
   objectVar = tearoffableArg;
   objectVar = xNonNullArg;
   objectVar = yNonNullArg;
-  core::num numVar = dynamicArg as{TypeError} core::num;
+  core::num numVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::num;
   numVar = numArg;
   numVar = intArg;
   numVar = doubleArg;
-  core::int intVar = dynamicArg as{TypeError} core::int;
+  core::int intVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
   intVar = intArg;
-  core::double doubleVar = dynamicArg as{TypeError} core::double;
+  core::double doubleVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::double;
   doubleVar = doubleArg;
-  core::Function functionVar = dynamicArg as{TypeError} core::Function;
+  core::Function functionVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::Function;
   functionVar = functionArg;
   functionVar = toVoidArg;
   functionVar = let final self::Tearoffable #t1 = tearoffableArg in #t1.==(null) ?{() → void} null : #t1.{self::Tearoffable::call};
-  () → void toVoidVar = dynamicArg as{TypeError} () → void;
+  () → void toVoidVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} () → void;
   toVoidVar = toVoidArg;
   toVoidVar = let final self::Tearoffable #t2 = tearoffableArg in #t2.==(null) ?{() → void} null : #t2.{self::Tearoffable::call};
-  self::Tearoffable tearoffableVar = dynamicArg as{TypeError} self::Tearoffable;
+  self::Tearoffable tearoffableVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::Tearoffable;
   tearoffableVar = tearoffableArg;
-  self::ok::XnonNull xNonNullVar = dynamicArg as{TypeError} self::ok::XnonNull;
+  self::ok::XnonNull xNonNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::XnonNull;
   xNonNullVar = xNonNullArg;
   xNonNullVar = yNonNullArg;
-  self::ok::YnonNull yNonNullVar = dynamicArg as{TypeError} self::ok::YnonNull;
+  self::ok::YnonNull yNonNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::YnonNull;
   yNonNullVar = yNonNullArg;
-  self::ok::XpotentiallyNull% xPotentiallyNullVar = dynamicArg as{TypeError} self::ok::XpotentiallyNull%;
+  self::ok::XpotentiallyNull% xPotentiallyNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::XpotentiallyNull%;
   xPotentiallyNullVar = xPotentiallyNullArg;
   xPotentiallyNullVar = yPotentiallyNullArg;
-  self::ok::YpotentiallyNull% yPotentiallyNullVar = dynamicArg as{TypeError} self::ok::YpotentiallyNull%;
+  self::ok::YpotentiallyNull% yPotentiallyNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::YpotentiallyNull%;
   yPotentiallyNullVar = yPotentiallyNullArg;
 }
 static method error<XnonNull extends core::Object = core::Object, YnonNull extends self::error::XnonNull = core::Object, XpotentiallyNull extends core::Object? = core::Object?, YpotentiallyNull extends self::error::XpotentiallyNull% = core::Object?>(core::Object objectArg, core::Object? objectNullableArg, core::num numArg, core::num? numNullableArg, core::int intArg, core::int? intNullableArg, core::double doubleArg, core::double? doubleNullableArg, core::Function functionArg, core::Function? functionNullableArg, () → void toVoidArg, () →? void toVoidNullableArg, self::Tearoffable tearoffableArg, self::Tearoffable? tearoffableNullableArg, self::error::XnonNull xNonNullArg, self::error::XnonNull? xNonNullNullableArg, self::error::XpotentiallyNull% xPotentiallyNullArg, self::error::XpotentiallyNull? xPotentiallyNullNullableArg, self::error::YnonNull yNonNullArg, self::error::YnonNull? yNonNullNullableArg, self::error::YpotentiallyNull% yPotentiallyNullArg, self::error::YpotentiallyNull? yPotentiallyNullNullableArg) → dynamic {
   core::Object objectVar = let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:114:22: Error: A value of type 'Object?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   Object objectVar = objectNullableArg;
-                     ^" in objectNullableArg as{TypeError} core::Object;
+                     ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:115:15: Error: A value of type 'num?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = numNullableArg;
-              ^" in numNullableArg as{TypeError} core::Object;
+              ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:116:15: Error: A value of type 'int?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = intNullableArg;
-              ^" in intNullableArg as{TypeError} core::Object;
+              ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:117:15: Error: A value of type 'double?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = doubleNullableArg;
-              ^" in doubleNullableArg as{TypeError} core::Object;
+              ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:118:15: Error: A value of type 'Function?' can't be assigned to a variable of type 'Object'.
  - 'Function' is from 'dart:core'.
  - 'Object' is from 'dart:core'.
   objectVar = functionNullableArg;
-              ^" in functionNullableArg as{TypeError} core::Object;
+              ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:119:15: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = toVoidNullableArg;
-              ^" in toVoidNullableArg as{TypeError} core::Object;
+              ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:120:15: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'Object'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
  - 'Object' is from 'dart:core'.
   objectVar = tearoffableNullableArg;
-              ^" in tearoffableNullableArg as{TypeError} core::Object;
+              ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:121:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = xNonNullNullableArg;
-              ^" in xNonNullNullableArg as{TypeError} core::Object;
+              ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:122:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = xPotentiallyNullArg;
-              ^" in xPotentiallyNullArg as{TypeError} core::Object;
+              ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:123:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = xPotentiallyNullNullableArg;
-              ^" in xPotentiallyNullNullableArg as{TypeError} core::Object;
+              ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t13 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:124:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = yNonNullNullableArg;
-              ^" in yNonNullNullableArg as{TypeError} core::Object;
+              ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t14 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:125:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = yPotentiallyNullArg;
-              ^" in yPotentiallyNullArg as{TypeError} core::Object;
+              ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t15 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:126:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = yPotentiallyNullNullableArg;
-              ^" in yPotentiallyNullNullableArg as{TypeError} core::Object;
+              ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   core::num numVar = let final<BottomType> #t16 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:128:16: Error: A value of type 'Object' can't be assigned to a variable of type 'num'.
  - 'Object' is from 'dart:core'.
   num numVar = objectArg;
-               ^" in objectArg as{TypeError} core::num;
+               ^" in objectArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t17 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:129:12: Error: A value of type 'Object?' can't be assigned to a variable of type 'num'.
  - 'Object' is from 'dart:core'.
   numVar = objectNullableArg;
-           ^" in objectNullableArg as{TypeError} core::num;
+           ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t18 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:130:12: Error: A value of type 'num?' can't be assigned to a variable of type 'num'.
   numVar = numNullableArg;
-           ^" in numNullableArg as{TypeError} core::num;
+           ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t19 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:131:12: Error: A value of type 'int?' can't be assigned to a variable of type 'num'.
   numVar = intNullableArg;
-           ^" in intNullableArg as{TypeError} core::num;
+           ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t20 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:132:12: Error: A value of type 'double?' can't be assigned to a variable of type 'num'.
   numVar = doubleNullableArg;
-           ^" in doubleNullableArg as{TypeError} core::num;
+           ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t21 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:133:12: Error: A value of type 'Function' can't be assigned to a variable of type 'num'.
  - 'Function' is from 'dart:core'.
   numVar = functionArg;
-           ^" in functionArg as{TypeError} core::num;
+           ^" in functionArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t22 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:134:12: Error: A value of type 'Function?' can't be assigned to a variable of type 'num'.
  - 'Function' is from 'dart:core'.
   numVar = functionNullableArg;
-           ^" in functionNullableArg as{TypeError} core::num;
+           ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t23 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:135:12: Error: A value of type 'void Function()' can't be assigned to a variable of type 'num'.
   numVar = toVoidArg;
-           ^" in toVoidArg as{TypeError} core::num;
+           ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t24 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:136:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'num'.
   numVar = toVoidNullableArg;
-           ^" in toVoidNullableArg as{TypeError} core::num;
+           ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t25 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:137:12: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'num'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   numVar = tearoffableArg;
-           ^" in tearoffableArg as{TypeError} core::num;
+           ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t26 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:138:12: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'num'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   numVar = tearoffableNullableArg;
-           ^" in tearoffableNullableArg as{TypeError} core::num;
+           ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t27 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:139:12: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'num'.
   numVar = xNonNullArg;
-           ^" in xNonNullArg as{TypeError} core::num;
+           ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t28 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:140:12: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'num'.
   numVar = xNonNullNullableArg;
-           ^" in xNonNullNullableArg as{TypeError} core::num;
+           ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t29 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:141:12: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'num'.
   numVar = xPotentiallyNullArg;
-           ^" in xPotentiallyNullArg as{TypeError} core::num;
+           ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t30 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:142:12: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'num'.
   numVar = xPotentiallyNullNullableArg;
-           ^" in xPotentiallyNullNullableArg as{TypeError} core::num;
+           ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t31 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:143:12: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'num'.
   numVar = yNonNullArg;
-           ^" in yNonNullArg as{TypeError} core::num;
+           ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t32 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:144:12: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'num'.
   numVar = yNonNullNullableArg;
-           ^" in yNonNullNullableArg as{TypeError} core::num;
+           ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t33 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:145:12: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'num'.
   numVar = yPotentiallyNullArg;
-           ^" in yPotentiallyNullArg as{TypeError} core::num;
+           ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t34 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:146:12: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'num'.
   numVar = yPotentiallyNullNullableArg;
-           ^" in yPotentiallyNullNullableArg as{TypeError} core::num;
+           ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   core::int intVar = let final<BottomType> #t35 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:148:16: Error: A value of type 'Object' can't be assigned to a variable of type 'int'.
  - 'Object' is from 'dart:core'.
   int intVar = objectArg;
-               ^" in objectArg as{TypeError} core::int;
+               ^" in objectArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t36 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:149:12: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
  - 'Object' is from 'dart:core'.
   intVar = objectNullableArg;
-           ^" in objectNullableArg as{TypeError} core::int;
+           ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t37 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:150:12: Error: A value of type 'num' can't be assigned to a variable of type 'int'.
   intVar = numArg;
-           ^" in numArg as{TypeError} core::int;
+           ^" in numArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t38 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:151:12: Error: A value of type 'num?' can't be assigned to a variable of type 'int'.
   intVar = numNullableArg;
-           ^" in numNullableArg as{TypeError} core::int;
+           ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t39 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:152:12: Error: A value of type 'int?' can't be assigned to a variable of type 'int'.
   intVar = intNullableArg;
-           ^" in intNullableArg as{TypeError} core::int;
+           ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t40 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:153:12: Error: A value of type 'double' can't be assigned to a variable of type 'int'.
   intVar = doubleArg;
-           ^" in doubleArg as{TypeError} core::int;
+           ^" in doubleArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t41 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:154:12: Error: A value of type 'double?' can't be assigned to a variable of type 'int'.
   intVar = doubleNullableArg;
-           ^" in doubleNullableArg as{TypeError} core::int;
+           ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t42 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:155:12: Error: A value of type 'Function' can't be assigned to a variable of type 'int'.
  - 'Function' is from 'dart:core'.
   intVar = functionArg;
-           ^" in functionArg as{TypeError} core::int;
+           ^" in functionArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t43 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:156:12: Error: A value of type 'Function?' can't be assigned to a variable of type 'int'.
  - 'Function' is from 'dart:core'.
   intVar = functionNullableArg;
-           ^" in functionNullableArg as{TypeError} core::int;
+           ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t44 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:157:12: Error: A value of type 'void Function()' can't be assigned to a variable of type 'int'.
   intVar = toVoidArg;
-           ^" in toVoidArg as{TypeError} core::int;
+           ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t45 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:158:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'int'.
   intVar = toVoidNullableArg;
-           ^" in toVoidNullableArg as{TypeError} core::int;
+           ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t46 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:159:12: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'int'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   intVar = tearoffableArg;
-           ^" in tearoffableArg as{TypeError} core::int;
+           ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t47 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:160:12: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'int'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   intVar = tearoffableNullableArg;
-           ^" in tearoffableNullableArg as{TypeError} core::int;
+           ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t48 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:161:12: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'int'.
   intVar = xNonNullArg;
-           ^" in xNonNullArg as{TypeError} core::int;
+           ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t49 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:162:12: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'int'.
   intVar = xNonNullNullableArg;
-           ^" in xNonNullNullableArg as{TypeError} core::int;
+           ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t50 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:163:12: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'int'.
   intVar = xPotentiallyNullArg;
-           ^" in xPotentiallyNullArg as{TypeError} core::int;
+           ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t51 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:164:12: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'int'.
   intVar = xPotentiallyNullNullableArg;
-           ^" in xPotentiallyNullNullableArg as{TypeError} core::int;
+           ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t52 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:165:12: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'int'.
   intVar = yNonNullArg;
-           ^" in yNonNullArg as{TypeError} core::int;
+           ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t53 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:166:12: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'int'.
   intVar = yNonNullNullableArg;
-           ^" in yNonNullNullableArg as{TypeError} core::int;
+           ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t54 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:167:12: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'int'.
   intVar = yPotentiallyNullArg;
-           ^" in yPotentiallyNullArg as{TypeError} core::int;
+           ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t55 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:168:12: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'int'.
   intVar = yPotentiallyNullNullableArg;
-           ^" in yPotentiallyNullNullableArg as{TypeError} core::int;
+           ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   core::double doubleVar = let final<BottomType> #t56 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:170:22: Error: A value of type 'Object' can't be assigned to a variable of type 'double'.
  - 'Object' is from 'dart:core'.
   double doubleVar = objectArg;
-                     ^" in objectArg as{TypeError} core::double;
+                     ^" in objectArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t57 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:171:15: Error: A value of type 'Object?' can't be assigned to a variable of type 'double'.
  - 'Object' is from 'dart:core'.
   doubleVar = objectNullableArg;
-              ^" in objectNullableArg as{TypeError} core::double;
+              ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t58 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:172:15: Error: A value of type 'num' can't be assigned to a variable of type 'double'.
   doubleVar = numArg;
-              ^" in numArg as{TypeError} core::double;
+              ^" in numArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t59 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:173:15: Error: A value of type 'num?' can't be assigned to a variable of type 'double'.
   doubleVar = numNullableArg;
-              ^" in numNullableArg as{TypeError} core::double;
+              ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t60 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:174:15: Error: A value of type 'int' can't be assigned to a variable of type 'double'.
   doubleVar = intArg;
-              ^" in intArg as{TypeError} core::double;
+              ^" in intArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t61 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:175:15: Error: A value of type 'int?' can't be assigned to a variable of type 'double'.
   doubleVar = intNullableArg;
-              ^" in intNullableArg as{TypeError} core::double;
+              ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t62 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:176:15: Error: A value of type 'double?' can't be assigned to a variable of type 'double'.
   doubleVar = doubleNullableArg;
-              ^" in doubleNullableArg as{TypeError} core::double;
+              ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t63 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:177:15: Error: A value of type 'Function' can't be assigned to a variable of type 'double'.
  - 'Function' is from 'dart:core'.
   doubleVar = functionArg;
-              ^" in functionArg as{TypeError} core::double;
+              ^" in functionArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t64 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:178:15: Error: A value of type 'Function?' can't be assigned to a variable of type 'double'.
  - 'Function' is from 'dart:core'.
   doubleVar = functionNullableArg;
-              ^" in functionNullableArg as{TypeError} core::double;
+              ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t65 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:179:15: Error: A value of type 'void Function()' can't be assigned to a variable of type 'double'.
   doubleVar = toVoidArg;
-              ^" in toVoidArg as{TypeError} core::double;
+              ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t66 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:180:15: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'double'.
   doubleVar = toVoidNullableArg;
-              ^" in toVoidNullableArg as{TypeError} core::double;
+              ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t67 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:181:15: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'double'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   doubleVar = tearoffableArg;
-              ^" in tearoffableArg as{TypeError} core::double;
+              ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t68 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:182:15: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'double'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   doubleVar = tearoffableNullableArg;
-              ^" in tearoffableNullableArg as{TypeError} core::double;
+              ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t69 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:183:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'double'.
   doubleVar = xNonNullArg;
-              ^" in xNonNullArg as{TypeError} core::double;
+              ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t70 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:184:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'double'.
   doubleVar = xNonNullNullableArg;
-              ^" in xNonNullNullableArg as{TypeError} core::double;
+              ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t71 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:185:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'double'.
   doubleVar = xPotentiallyNullArg;
-              ^" in xPotentiallyNullArg as{TypeError} core::double;
+              ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t72 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:186:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'double'.
   doubleVar = xPotentiallyNullNullableArg;
-              ^" in xPotentiallyNullNullableArg as{TypeError} core::double;
+              ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t73 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:187:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'double'.
   doubleVar = yNonNullArg;
-              ^" in yNonNullArg as{TypeError} core::double;
+              ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t74 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:188:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'double'.
   doubleVar = yNonNullNullableArg;
-              ^" in yNonNullNullableArg as{TypeError} core::double;
+              ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t75 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:189:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'double'.
   doubleVar = yPotentiallyNullArg;
-              ^" in yPotentiallyNullArg as{TypeError} core::double;
+              ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t76 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:190:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'double'.
   doubleVar = yPotentiallyNullNullableArg;
-              ^" in yPotentiallyNullNullableArg as{TypeError} core::double;
+              ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   core::Function functionVar = let final<BottomType> #t77 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:192:26: Error: A value of type 'Object' can't be assigned to a variable of type 'Function'.
  - 'Object' is from 'dart:core'.
  - 'Function' is from 'dart:core'.
   Function functionVar = objectArg;
-                         ^" in objectArg as{TypeError} core::Function;
+                         ^" in objectArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t78 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:193:17: Error: A value of type 'Object?' can't be assigned to a variable of type 'Function'.
  - 'Object' is from 'dart:core'.
  - 'Function' is from 'dart:core'.
   functionVar = objectNullableArg;
-                ^" in objectNullableArg as{TypeError} core::Function;
+                ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t79 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:194:17: Error: A value of type 'num' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = numArg;
-                ^" in numArg as{TypeError} core::Function;
+                ^" in numArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t80 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:195:17: Error: A value of type 'num?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} core::Function;
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t81 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:196:17: Error: A value of type 'int' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = intArg;
-                ^" in intArg as{TypeError} core::Function;
+                ^" in intArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t82 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:197:17: Error: A value of type 'int?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} core::Function;
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t83 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:198:17: Error: A value of type 'double' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = doubleArg;
-                ^" in doubleArg as{TypeError} core::Function;
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t84 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:199:17: Error: A value of type 'double?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} core::Function;
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t85 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:200:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = functionNullableArg;
-                ^" in functionNullableArg as{TypeError} core::Function;
+                ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t86 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:201:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = toVoidNullableArg;
-                ^" in toVoidNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t87 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:202:3: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Function'.
- - 'Function' is from 'dart:core'.
+                ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t87 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:202:17: Error: Can't tear off method 'call' from a potentially null value.
   functionVar = tearoffableNullableArg;
-  ^" in (let final self::Tearoffable? #t88 = tearoffableNullableArg in #t88.==(null) ?{() →? void} null : #t88.{self::Tearoffable::call}) as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t89 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
+                ^" in tearoffableNullableArg as{TypeError} core::Function;
+  functionVar = let final<BottomType> #t88 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xNonNullArg;
-                ^" in xNonNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t90 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:204:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Function'.
+                ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t89 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:204:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xNonNullNullableArg;
-                ^" in xNonNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t91 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:205:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Function'.
+                ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t90 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:205:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t92 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:206:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Function'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t91 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:206:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t93 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:207:17: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Function'.
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t92 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:207:17: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yNonNullArg;
-                ^" in yNonNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t94 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:208:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Function'.
+                ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t93 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:208:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yNonNullNullableArg;
-                ^" in yNonNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t95 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:209:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Function'.
+                ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t94 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:209:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t96 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:210:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Function'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t95 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:210:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} core::Function;
-  () → void toVoidVar = let final<BottomType> #t97 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:212:31: Error: A value of type 'Object' can't be assigned to a variable of type 'void Function()'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  () → void toVoidVar = let final<BottomType> #t96 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:212:31: Error: A value of type 'Object' can't be assigned to a variable of type 'void Function()'.
  - 'Object' is from 'dart:core'.
   void Function() toVoidVar = objectArg;
-                              ^" in objectArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t98 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:213:15: Error: A value of type 'Object?' can't be assigned to a variable of type 'void Function()'.
+                              ^" in objectArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t97 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:213:15: Error: A value of type 'Object?' can't be assigned to a variable of type 'void Function()'.
  - 'Object' is from 'dart:core'.
   toVoidVar = objectNullableArg;
-              ^" in objectNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t99 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:214:15: Error: A value of type 'num' can't be assigned to a variable of type 'void Function()'.
+              ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t98 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:214:15: Error: A value of type 'num' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = numArg;
-              ^" in numArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t100 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:215:15: Error: A value of type 'num?' can't be assigned to a variable of type 'void Function()'.
+              ^" in numArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t99 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:215:15: Error: A value of type 'num?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = numNullableArg;
-              ^" in numNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t101 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:216:15: Error: A value of type 'int' can't be assigned to a variable of type 'void Function()'.
+              ^" in numNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t100 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:216:15: Error: A value of type 'int' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = intArg;
-              ^" in intArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t102 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:217:15: Error: A value of type 'int?' can't be assigned to a variable of type 'void Function()'.
+              ^" in intArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t101 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:217:15: Error: A value of type 'int?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = intNullableArg;
-              ^" in intNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t103 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:218:15: Error: A value of type 'double' can't be assigned to a variable of type 'void Function()'.
+              ^" in intNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t102 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:218:15: Error: A value of type 'double' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = doubleArg;
-              ^" in doubleArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t104 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:219:15: Error: A value of type 'double?' can't be assigned to a variable of type 'void Function()'.
+              ^" in doubleArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t103 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:219:15: Error: A value of type 'double?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = doubleNullableArg;
-              ^" in doubleNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t105 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:220:15: Error: A value of type 'Function' can't be assigned to a variable of type 'void Function()'.
+              ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t104 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:220:15: Error: A value of type 'Function' can't be assigned to a variable of type 'void Function()'.
  - 'Function' is from 'dart:core'.
   toVoidVar = functionArg;
-              ^" in functionArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t106 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:221:15: Error: A value of type 'Function?' can't be assigned to a variable of type 'void Function()'.
+              ^" in functionArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t105 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:221:15: Error: A value of type 'Function?' can't be assigned to a variable of type 'void Function()'.
  - 'Function' is from 'dart:core'.
   toVoidVar = functionNullableArg;
-              ^" in functionNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t107 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:222:15: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
+              ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t106 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:222:15: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = toVoidNullableArg;
-              ^" in toVoidNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t108 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:223:3: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
+              ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t107 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:223:15: Error: Can't tear off method 'call' from a potentially null value.
   toVoidVar = tearoffableNullableArg;
-  ^" in (let final self::Tearoffable? #t109 = tearoffableNullableArg in #t109.==(null) ?{() →? void} null : #t109.{self::Tearoffable::call}) as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t110 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in tearoffableNullableArg as{TypeError} () → void;
+  toVoidVar = let final<BottomType> #t108 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xNonNullArg;
-              ^" in xNonNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t111 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:225:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t109 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:225:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xNonNullNullableArg;
-              ^" in xNonNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t112 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:226:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t110 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:226:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xPotentiallyNullArg;
-              ^" in xPotentiallyNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t113 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:227:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t111 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:227:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xPotentiallyNullNullableArg;
-              ^" in xPotentiallyNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t114 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:228:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t112 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:228:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yNonNullArg;
-              ^" in yNonNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t115 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:229:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t113 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:229:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yNonNullNullableArg;
-              ^" in yNonNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t116 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:230:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t114 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:230:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yPotentiallyNullArg;
-              ^" in yPotentiallyNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t117 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:231:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t115 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:231:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yPotentiallyNullNullableArg;
-              ^" in yPotentiallyNullNullableArg as{TypeError} () → void;
-  self::Tearoffable tearoffableVar = let final<BottomType> #t118 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:233:32: Error: A value of type 'Object' can't be assigned to a variable of type 'Tearoffable'.
+              ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  self::Tearoffable tearoffableVar = let final<BottomType> #t116 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:233:32: Error: A value of type 'Object' can't be assigned to a variable of type 'Tearoffable'.
  - 'Object' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   Tearoffable tearoffableVar = objectArg;
-                               ^" in objectArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t119 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:234:20: Error: A value of type 'Object?' can't be assigned to a variable of type 'Tearoffable'.
+                               ^" in objectArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t117 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:234:20: Error: A value of type 'Object?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Object' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = objectNullableArg;
-                   ^" in objectNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t120 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:235:20: Error: A value of type 'num' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t118 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:235:20: Error: A value of type 'num' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = numArg;
-                   ^" in numArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t121 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:236:20: Error: A value of type 'num?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in numArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t119 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:236:20: Error: A value of type 'num?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = numNullableArg;
-                   ^" in numNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t122 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:237:20: Error: A value of type 'int' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in numNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t120 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:237:20: Error: A value of type 'int' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = intArg;
-                   ^" in intArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t123 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:238:20: Error: A value of type 'int?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in intArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t121 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:238:20: Error: A value of type 'int?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = intNullableArg;
-                   ^" in intNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t124 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:239:20: Error: A value of type 'double' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in intNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t122 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:239:20: Error: A value of type 'double' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = doubleArg;
-                   ^" in doubleArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t125 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:240:20: Error: A value of type 'double?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in doubleArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t123 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:240:20: Error: A value of type 'double?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = doubleNullableArg;
-                   ^" in doubleNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t126 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:241:20: Error: A value of type 'Function' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t124 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:241:20: Error: A value of type 'Function' can't be assigned to a variable of type 'Tearoffable'.
  - 'Function' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = functionArg;
-                   ^" in functionArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t127 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:242:20: Error: A value of type 'Function?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in functionArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t125 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:242:20: Error: A value of type 'Function?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Function' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = functionNullableArg;
-                   ^" in functionNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t128 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:243:20: Error: A value of type 'void Function()' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t126 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:243:20: Error: A value of type 'void Function()' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = toVoidArg;
-                   ^" in toVoidArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t129 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:244:20: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in toVoidArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t127 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:244:20: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = toVoidNullableArg;
-                   ^" in toVoidNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t130 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:245:20: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t128 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:245:20: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = tearoffableNullableArg;
-                   ^" in tearoffableNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t131 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:246:20: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t129 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:246:20: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xNonNullArg;
-                   ^" in xNonNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t132 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:247:20: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t130 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:247:20: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xNonNullNullableArg;
-                   ^" in xNonNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t133 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:248:20: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t131 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:248:20: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xPotentiallyNullArg;
-                   ^" in xPotentiallyNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t134 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:249:20: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t132 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:249:20: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xPotentiallyNullNullableArg;
-                   ^" in xPotentiallyNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t135 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:250:20: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t133 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:250:20: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yNonNullArg;
-                   ^" in yNonNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t136 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:251:20: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t134 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:251:20: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yNonNullNullableArg;
-                   ^" in yNonNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t137 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:252:20: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t135 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:252:20: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yPotentiallyNullArg;
-                   ^" in yPotentiallyNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t138 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:253:20: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t136 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:253:20: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yPotentiallyNullNullableArg;
-                   ^" in yPotentiallyNullNullableArg as{TypeError} self::Tearoffable;
-  self::error::XnonNull xNonNullVar = let final<BottomType> #t139 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:255:26: Error: A value of type 'Object' can't be assigned to a variable of type 'XnonNull'.
+                   ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  self::error::XnonNull xNonNullVar = let final<BottomType> #t137 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:255:26: Error: A value of type 'Object' can't be assigned to a variable of type 'XnonNull'.
  - 'Object' is from 'dart:core'.
   XnonNull xNonNullVar = objectArg;
-                         ^" in objectArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t140 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:256:17: Error: A value of type 'Object?' can't be assigned to a variable of type 'XnonNull'.
+                         ^" in objectArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t138 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:256:17: Error: A value of type 'Object?' can't be assigned to a variable of type 'XnonNull'.
  - 'Object' is from 'dart:core'.
   xNonNullVar = objectNullableArg;
-                ^" in objectNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:257:17: Error: A value of type 'num' can't be assigned to a variable of type 'XnonNull'.
+                ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t139 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:257:17: Error: A value of type 'num' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = numArg;
-                ^" in numArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t142 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:258:17: Error: A value of type 'num?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t140 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:258:17: Error: A value of type 'num?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:259:17: Error: A value of type 'int' can't be assigned to a variable of type 'XnonNull'.
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:259:17: Error: A value of type 'int' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = intArg;
-                ^" in intArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t144 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:260:17: Error: A value of type 'int?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t142 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:260:17: Error: A value of type 'int?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:261:17: Error: A value of type 'double' can't be assigned to a variable of type 'XnonNull'.
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:261:17: Error: A value of type 'double' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = doubleArg;
-                ^" in doubleArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t146 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:262:17: Error: A value of type 'double?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t144 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:262:17: Error: A value of type 'double?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:263:17: Error: A value of type 'Function' can't be assigned to a variable of type 'XnonNull'.
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:263:17: Error: A value of type 'Function' can't be assigned to a variable of type 'XnonNull'.
  - 'Function' is from 'dart:core'.
   xNonNullVar = functionArg;
-                ^" in functionArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:264:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t146 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:264:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'XnonNull'.
  - 'Function' is from 'dart:core'.
   xNonNullVar = functionNullableArg;
-                ^" in functionNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t149 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:265:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XnonNull'.
+                ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:265:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = toVoidArg;
-                ^" in toVoidArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:266:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:266:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = toVoidNullableArg;
-                ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:267:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XnonNull'.
+                ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t149 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:267:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xNonNullVar = tearoffableArg;
-                ^" in tearoffableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t152 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:268:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:268:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xNonNullVar = tearoffableNullableArg;
-                ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:269:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:269:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = xNonNullNullableArg;
-                ^" in xNonNullNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:270:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
+                ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t152 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:270:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t155 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:271:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:271:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t156 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:272:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:272:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = yNonNullNullableArg;
-                ^" in yNonNullNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t157 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:273:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
+                ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t155 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:273:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:274:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t156 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:274:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  self::error::XpotentiallyNull% xPotentiallyNullVar = let final<BottomType> #t159 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:276:42: Error: A value of type 'Object' can't be assigned to a variable of type 'XpotentiallyNull'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  self::error::XpotentiallyNull% xPotentiallyNullVar = let final<BottomType> #t157 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:276:42: Error: A value of type 'Object' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Object' is from 'dart:core'.
   XpotentiallyNull xPotentiallyNullVar = objectArg;
-                                         ^" in objectArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t160 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:277:25: Error: A value of type 'Object?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                                         ^" in objectArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:277:25: Error: A value of type 'Object?' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Object' is from 'dart:core'.
   xPotentiallyNullVar = objectNullableArg;
-                        ^" in objectNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t161 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:278:25: Error: A value of type 'num' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t159 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:278:25: Error: A value of type 'num' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = numArg;
-                        ^" in numArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t162 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:279:25: Error: A value of type 'num?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t160 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:279:25: Error: A value of type 'num?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = numNullableArg;
-                        ^" in numNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t163 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:280:25: Error: A value of type 'int' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t161 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:280:25: Error: A value of type 'int' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = intArg;
-                        ^" in intArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t164 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:281:25: Error: A value of type 'int?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t162 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:281:25: Error: A value of type 'int?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = intNullableArg;
-                        ^" in intNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t165 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:282:25: Error: A value of type 'double' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t163 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:282:25: Error: A value of type 'double' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = doubleArg;
-                        ^" in doubleArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t166 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:283:25: Error: A value of type 'double?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t164 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:283:25: Error: A value of type 'double?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = doubleNullableArg;
-                        ^" in doubleNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t167 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:284:25: Error: A value of type 'Function' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t165 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:284:25: Error: A value of type 'Function' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   xPotentiallyNullVar = functionArg;
-                        ^" in functionArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t168 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:285:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t166 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:285:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   xPotentiallyNullVar = functionNullableArg;
-                        ^" in functionNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t169 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:286:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t167 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:286:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = toVoidArg;
-                        ^" in toVoidArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t170 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:287:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t168 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:287:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = toVoidNullableArg;
-                        ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t171 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:288:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t169 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:288:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xPotentiallyNullVar = tearoffableArg;
-                        ^" in tearoffableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t172 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:289:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t170 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:289:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xPotentiallyNullVar = tearoffableNullableArg;
-                        ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t173 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:290:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t171 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:290:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = xNonNullArg;
-                        ^" in xNonNullArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t174 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:291:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t172 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:291:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = xNonNullNullableArg;
-                        ^" in xNonNullNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t175 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:292:25: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t173 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:292:25: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = xPotentiallyNullNullableArg;
-                        ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t176 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:293:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t174 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:293:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = yNonNullArg;
-                        ^" in yNonNullArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t177 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:294:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t175 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:294:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = yNonNullNullableArg;
-                        ^" in yNonNullNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t178 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:295:25: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t176 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:295:25: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = yPotentiallyNullNullableArg;
-                        ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  self::error::YnonNull yNonNullVar = let final<BottomType> #t179 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:297:26: Error: A value of type 'Object' can't be assigned to a variable of type 'YnonNull'.
+                        ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  self::error::YnonNull yNonNullVar = let final<BottomType> #t177 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:297:26: Error: A value of type 'Object' can't be assigned to a variable of type 'YnonNull'.
  - 'Object' is from 'dart:core'.
   YnonNull yNonNullVar = objectArg;
-                         ^" in objectArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t180 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:298:17: Error: A value of type 'Object?' can't be assigned to a variable of type 'YnonNull'.
+                         ^" in objectArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t178 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:298:17: Error: A value of type 'Object?' can't be assigned to a variable of type 'YnonNull'.
  - 'Object' is from 'dart:core'.
   yNonNullVar = objectNullableArg;
-                ^" in objectNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t181 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:299:17: Error: A value of type 'num' can't be assigned to a variable of type 'YnonNull'.
+                ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t179 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:299:17: Error: A value of type 'num' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = numArg;
-                ^" in numArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t182 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:300:17: Error: A value of type 'num?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t180 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:300:17: Error: A value of type 'num?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t183 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:301:17: Error: A value of type 'int' can't be assigned to a variable of type 'YnonNull'.
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t181 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:301:17: Error: A value of type 'int' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = intArg;
-                ^" in intArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t184 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:302:17: Error: A value of type 'int?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t182 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:302:17: Error: A value of type 'int?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t185 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:303:17: Error: A value of type 'double' can't be assigned to a variable of type 'YnonNull'.
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t183 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:303:17: Error: A value of type 'double' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = doubleArg;
-                ^" in doubleArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t186 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:304:17: Error: A value of type 'double?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t184 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:304:17: Error: A value of type 'double?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t187 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:305:17: Error: A value of type 'Function' can't be assigned to a variable of type 'YnonNull'.
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t185 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:305:17: Error: A value of type 'Function' can't be assigned to a variable of type 'YnonNull'.
  - 'Function' is from 'dart:core'.
   yNonNullVar = functionArg;
-                ^" in functionArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t188 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:306:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t186 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:306:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'YnonNull'.
  - 'Function' is from 'dart:core'.
   yNonNullVar = functionNullableArg;
-                ^" in functionNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t189 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:307:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YnonNull'.
+                ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t187 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:307:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = toVoidArg;
-                ^" in toVoidArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t190 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:308:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t188 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:308:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = toVoidNullableArg;
-                ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t191 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:309:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YnonNull'.
+                ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t189 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:309:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yNonNullVar = tearoffableArg;
-                ^" in tearoffableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t192 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:310:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t190 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:310:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yNonNullVar = tearoffableNullableArg;
-                ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t193 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:311:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YnonNull'.
+                ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t191 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:311:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xNonNullArg;
-                ^" in xNonNullArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t194 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:312:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t192 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:312:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xNonNullNullableArg;
-                ^" in xNonNullNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t195 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:313:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
+                ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t193 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:313:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t196 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:314:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t194 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:314:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t197 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:315:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t195 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:315:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = yNonNullNullableArg;
-                ^" in yNonNullNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t198 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:316:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
+                ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t196 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:316:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t199 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:317:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t197 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:317:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  self::error::YpotentiallyNull% yPotentiallyNullVar = let final<BottomType> #t200 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:319:42: Error: A value of type 'Object' can't be assigned to a variable of type 'YpotentiallyNull'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  self::error::YpotentiallyNull% yPotentiallyNullVar = let final<BottomType> #t198 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:319:42: Error: A value of type 'Object' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Object' is from 'dart:core'.
   YpotentiallyNull yPotentiallyNullVar = objectArg;
-                                         ^" in objectArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t201 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:320:25: Error: A value of type 'Object?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                                         ^" in objectArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t199 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:320:25: Error: A value of type 'Object?' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Object' is from 'dart:core'.
   yPotentiallyNullVar = objectNullableArg;
-                        ^" in objectNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t202 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:321:25: Error: A value of type 'num' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t200 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:321:25: Error: A value of type 'num' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = numArg;
-                        ^" in numArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t203 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:322:25: Error: A value of type 'num?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t201 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:322:25: Error: A value of type 'num?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = numNullableArg;
-                        ^" in numNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t204 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:323:25: Error: A value of type 'int' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t202 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:323:25: Error: A value of type 'int' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = intArg;
-                        ^" in intArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t205 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:324:25: Error: A value of type 'int?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t203 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:324:25: Error: A value of type 'int?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = intNullableArg;
-                        ^" in intNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t206 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:325:25: Error: A value of type 'double' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t204 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:325:25: Error: A value of type 'double' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = doubleArg;
-                        ^" in doubleArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t207 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:326:25: Error: A value of type 'double?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t205 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:326:25: Error: A value of type 'double?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = doubleNullableArg;
-                        ^" in doubleNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t208 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:327:25: Error: A value of type 'Function' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t206 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:327:25: Error: A value of type 'Function' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   yPotentiallyNullVar = functionArg;
-                        ^" in functionArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t209 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:328:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t207 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:328:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   yPotentiallyNullVar = functionNullableArg;
-                        ^" in functionNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t210 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:329:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t208 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:329:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = toVoidArg;
-                        ^" in toVoidArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t211 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:330:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t209 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:330:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = toVoidNullableArg;
-                        ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t212 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:331:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t210 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:331:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yPotentiallyNullVar = tearoffableArg;
-                        ^" in tearoffableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t213 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:332:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t211 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:332:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yPotentiallyNullVar = tearoffableNullableArg;
-                        ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t214 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:333:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t212 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:333:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xNonNullArg;
-                        ^" in xNonNullArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t215 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:334:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t213 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:334:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xNonNullNullableArg;
-                        ^" in xNonNullNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t216 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:335:25: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t214 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:335:25: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xPotentiallyNullArg;
-                        ^" in xPotentiallyNullArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t217 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:336:25: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t215 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:336:25: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xPotentiallyNullNullableArg;
-                        ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t218 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:337:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t216 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:337:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = yNonNullArg;
-                        ^" in yNonNullArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t219 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:338:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t217 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:338:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = yNonNullNullableArg;
-                        ^" in yNonNullNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t220 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:339:25: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t218 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:339:25: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = yPotentiallyNullNullableArg;
-                        ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
+                        ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/assignability.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/assignability.dart.strong.transformed.expect
index 56f107d..803bc0a 100644
--- a/pkg/front_end/testcases/nnbd/assignability.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/assignability.dart.strong.transformed.expect
@@ -383,10 +383,9 @@
 //   functionVar = toVoidNullableArg;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/assignability.dart:202:3: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Function'.
-//  - 'Function' is from 'dart:core'.
+// pkg/front_end/testcases/nnbd/assignability.dart:202:17: Error: Can't tear off method 'call' from a potentially null value.
 //   functionVar = tearoffableNullableArg;
-//   ^
+//                 ^
 //
 // pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
 //  - 'Function' is from 'dart:core'.
@@ -476,9 +475,9 @@
 //   toVoidVar = toVoidNullableArg;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/assignability.dart:223:3: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
+// pkg/front_end/testcases/nnbd/assignability.dart:223:15: Error: Can't tear off method 'call' from a potentially null value.
 //   toVoidVar = tearoffableNullableArg;
-//   ^
+//               ^
 //
 // pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
 //   toVoidVar = xNonNullArg;
@@ -995,7 +994,7 @@
   dynamicVar = xPotentiallyNullArg;
   dynamicVar = yNonNullArg;
   dynamicVar = yPotentiallyNullArg;
-  core::Object objectVar = dynamicArg as{TypeError} core::Object;
+  core::Object objectVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::Object;
   objectVar = objectArg;
   objectVar = numArg;
   objectVar = intArg;
@@ -1004,789 +1003,788 @@
   objectVar = tearoffableArg;
   objectVar = xNonNullArg;
   objectVar = yNonNullArg;
-  core::num numVar = dynamicArg as{TypeError} core::num;
+  core::num numVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::num;
   numVar = numArg;
   numVar = intArg;
   numVar = doubleArg;
-  core::int intVar = dynamicArg as{TypeError} core::int;
+  core::int intVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
   intVar = intArg;
-  core::double doubleVar = dynamicArg as{TypeError} core::double;
+  core::double doubleVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::double;
   doubleVar = doubleArg;
-  core::Function functionVar = dynamicArg as{TypeError} core::Function;
+  core::Function functionVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::Function;
   functionVar = functionArg;
   functionVar = toVoidArg;
   functionVar = let final self::Tearoffable #t1 = tearoffableArg in #t1.==(null) ?{() → void} null : #t1.{self::Tearoffable::call};
-  () → void toVoidVar = dynamicArg as{TypeError} () → void;
+  () → void toVoidVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} () → void;
   toVoidVar = toVoidArg;
   toVoidVar = let final self::Tearoffable #t2 = tearoffableArg in #t2.==(null) ?{() → void} null : #t2.{self::Tearoffable::call};
-  self::Tearoffable tearoffableVar = dynamicArg as{TypeError} self::Tearoffable;
+  self::Tearoffable tearoffableVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::Tearoffable;
   tearoffableVar = tearoffableArg;
-  self::ok::XnonNull xNonNullVar = dynamicArg as{TypeError} self::ok::XnonNull;
+  self::ok::XnonNull xNonNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::XnonNull;
   xNonNullVar = xNonNullArg;
   xNonNullVar = yNonNullArg;
-  self::ok::YnonNull yNonNullVar = dynamicArg as{TypeError} self::ok::YnonNull;
+  self::ok::YnonNull yNonNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::YnonNull;
   yNonNullVar = yNonNullArg;
-  self::ok::XpotentiallyNull% xPotentiallyNullVar = dynamicArg as{TypeError} self::ok::XpotentiallyNull%;
+  self::ok::XpotentiallyNull% xPotentiallyNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::XpotentiallyNull%;
   xPotentiallyNullVar = xPotentiallyNullArg;
   xPotentiallyNullVar = yPotentiallyNullArg;
-  self::ok::YpotentiallyNull% yPotentiallyNullVar = dynamicArg as{TypeError} self::ok::YpotentiallyNull%;
+  self::ok::YpotentiallyNull% yPotentiallyNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::YpotentiallyNull%;
   yPotentiallyNullVar = yPotentiallyNullArg;
 }
 static method error<XnonNull extends core::Object = core::Object, YnonNull extends self::error::XnonNull = core::Object, XpotentiallyNull extends core::Object? = core::Object?, YpotentiallyNull extends self::error::XpotentiallyNull% = core::Object?>(core::Object objectArg, core::Object? objectNullableArg, core::num numArg, core::num? numNullableArg, core::int intArg, core::int? intNullableArg, core::double doubleArg, core::double? doubleNullableArg, core::Function functionArg, core::Function? functionNullableArg, () → void toVoidArg, () →? void toVoidNullableArg, self::Tearoffable tearoffableArg, self::Tearoffable? tearoffableNullableArg, self::error::XnonNull xNonNullArg, self::error::XnonNull? xNonNullNullableArg, self::error::XpotentiallyNull% xPotentiallyNullArg, self::error::XpotentiallyNull? xPotentiallyNullNullableArg, self::error::YnonNull yNonNullArg, self::error::YnonNull? yNonNullNullableArg, self::error::YpotentiallyNull% yPotentiallyNullArg, self::error::YpotentiallyNull? yPotentiallyNullNullableArg) → dynamic {
   core::Object objectVar = let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:114:22: Error: A value of type 'Object?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   Object objectVar = objectNullableArg;
-                     ^" in objectNullableArg as{TypeError} core::Object;
+                     ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:115:15: Error: A value of type 'num?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = numNullableArg;
-              ^" in numNullableArg as{TypeError} core::Object;
+              ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:116:15: Error: A value of type 'int?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = intNullableArg;
-              ^" in intNullableArg as{TypeError} core::Object;
+              ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:117:15: Error: A value of type 'double?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = doubleNullableArg;
-              ^" in doubleNullableArg as{TypeError} core::Object;
+              ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:118:15: Error: A value of type 'Function?' can't be assigned to a variable of type 'Object'.
  - 'Function' is from 'dart:core'.
  - 'Object' is from 'dart:core'.
   objectVar = functionNullableArg;
-              ^" in functionNullableArg as{TypeError} core::Object;
+              ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:119:15: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = toVoidNullableArg;
-              ^" in toVoidNullableArg as{TypeError} core::Object;
+              ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:120:15: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'Object'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
  - 'Object' is from 'dart:core'.
   objectVar = tearoffableNullableArg;
-              ^" in tearoffableNullableArg as{TypeError} core::Object;
+              ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:121:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = xNonNullNullableArg;
-              ^" in xNonNullNullableArg as{TypeError} core::Object;
+              ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:122:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = xPotentiallyNullArg;
-              ^" in xPotentiallyNullArg as{TypeError} core::Object;
+              ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:123:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = xPotentiallyNullNullableArg;
-              ^" in xPotentiallyNullNullableArg as{TypeError} core::Object;
+              ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t13 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:124:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = yNonNullNullableArg;
-              ^" in yNonNullNullableArg as{TypeError} core::Object;
+              ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t14 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:125:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = yPotentiallyNullArg;
-              ^" in yPotentiallyNullArg as{TypeError} core::Object;
+              ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Object;
   objectVar = let final<BottomType> #t15 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:126:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Object'.
  - 'Object' is from 'dart:core'.
   objectVar = yPotentiallyNullNullableArg;
-              ^" in yPotentiallyNullNullableArg as{TypeError} core::Object;
+              ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Object;
   core::num numVar = let final<BottomType> #t16 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:128:16: Error: A value of type 'Object' can't be assigned to a variable of type 'num'.
  - 'Object' is from 'dart:core'.
   num numVar = objectArg;
-               ^" in objectArg as{TypeError} core::num;
+               ^" in objectArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t17 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:129:12: Error: A value of type 'Object?' can't be assigned to a variable of type 'num'.
  - 'Object' is from 'dart:core'.
   numVar = objectNullableArg;
-           ^" in objectNullableArg as{TypeError} core::num;
+           ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t18 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:130:12: Error: A value of type 'num?' can't be assigned to a variable of type 'num'.
   numVar = numNullableArg;
-           ^" in numNullableArg as{TypeError} core::num;
+           ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t19 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:131:12: Error: A value of type 'int?' can't be assigned to a variable of type 'num'.
   numVar = intNullableArg;
-           ^" in intNullableArg as{TypeError} core::num;
+           ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t20 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:132:12: Error: A value of type 'double?' can't be assigned to a variable of type 'num'.
   numVar = doubleNullableArg;
-           ^" in doubleNullableArg as{TypeError} core::num;
+           ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t21 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:133:12: Error: A value of type 'Function' can't be assigned to a variable of type 'num'.
  - 'Function' is from 'dart:core'.
   numVar = functionArg;
-           ^" in functionArg as{TypeError} core::num;
+           ^" in functionArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t22 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:134:12: Error: A value of type 'Function?' can't be assigned to a variable of type 'num'.
  - 'Function' is from 'dart:core'.
   numVar = functionNullableArg;
-           ^" in functionNullableArg as{TypeError} core::num;
+           ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t23 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:135:12: Error: A value of type 'void Function()' can't be assigned to a variable of type 'num'.
   numVar = toVoidArg;
-           ^" in toVoidArg as{TypeError} core::num;
+           ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t24 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:136:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'num'.
   numVar = toVoidNullableArg;
-           ^" in toVoidNullableArg as{TypeError} core::num;
+           ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t25 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:137:12: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'num'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   numVar = tearoffableArg;
-           ^" in tearoffableArg as{TypeError} core::num;
+           ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t26 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:138:12: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'num'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   numVar = tearoffableNullableArg;
-           ^" in tearoffableNullableArg as{TypeError} core::num;
+           ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t27 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:139:12: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'num'.
   numVar = xNonNullArg;
-           ^" in xNonNullArg as{TypeError} core::num;
+           ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t28 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:140:12: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'num'.
   numVar = xNonNullNullableArg;
-           ^" in xNonNullNullableArg as{TypeError} core::num;
+           ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t29 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:141:12: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'num'.
   numVar = xPotentiallyNullArg;
-           ^" in xPotentiallyNullArg as{TypeError} core::num;
+           ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t30 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:142:12: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'num'.
   numVar = xPotentiallyNullNullableArg;
-           ^" in xPotentiallyNullNullableArg as{TypeError} core::num;
+           ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t31 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:143:12: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'num'.
   numVar = yNonNullArg;
-           ^" in yNonNullArg as{TypeError} core::num;
+           ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t32 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:144:12: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'num'.
   numVar = yNonNullNullableArg;
-           ^" in yNonNullNullableArg as{TypeError} core::num;
+           ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t33 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:145:12: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'num'.
   numVar = yPotentiallyNullArg;
-           ^" in yPotentiallyNullArg as{TypeError} core::num;
+           ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t34 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:146:12: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'num'.
   numVar = yPotentiallyNullNullableArg;
-           ^" in yPotentiallyNullNullableArg as{TypeError} core::num;
+           ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   core::int intVar = let final<BottomType> #t35 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:148:16: Error: A value of type 'Object' can't be assigned to a variable of type 'int'.
  - 'Object' is from 'dart:core'.
   int intVar = objectArg;
-               ^" in objectArg as{TypeError} core::int;
+               ^" in objectArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t36 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:149:12: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
  - 'Object' is from 'dart:core'.
   intVar = objectNullableArg;
-           ^" in objectNullableArg as{TypeError} core::int;
+           ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t37 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:150:12: Error: A value of type 'num' can't be assigned to a variable of type 'int'.
   intVar = numArg;
-           ^" in numArg as{TypeError} core::int;
+           ^" in numArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t38 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:151:12: Error: A value of type 'num?' can't be assigned to a variable of type 'int'.
   intVar = numNullableArg;
-           ^" in numNullableArg as{TypeError} core::int;
+           ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t39 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:152:12: Error: A value of type 'int?' can't be assigned to a variable of type 'int'.
   intVar = intNullableArg;
-           ^" in intNullableArg as{TypeError} core::int;
+           ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t40 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:153:12: Error: A value of type 'double' can't be assigned to a variable of type 'int'.
   intVar = doubleArg;
-           ^" in doubleArg as{TypeError} core::int;
+           ^" in doubleArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t41 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:154:12: Error: A value of type 'double?' can't be assigned to a variable of type 'int'.
   intVar = doubleNullableArg;
-           ^" in doubleNullableArg as{TypeError} core::int;
+           ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t42 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:155:12: Error: A value of type 'Function' can't be assigned to a variable of type 'int'.
  - 'Function' is from 'dart:core'.
   intVar = functionArg;
-           ^" in functionArg as{TypeError} core::int;
+           ^" in functionArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t43 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:156:12: Error: A value of type 'Function?' can't be assigned to a variable of type 'int'.
  - 'Function' is from 'dart:core'.
   intVar = functionNullableArg;
-           ^" in functionNullableArg as{TypeError} core::int;
+           ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t44 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:157:12: Error: A value of type 'void Function()' can't be assigned to a variable of type 'int'.
   intVar = toVoidArg;
-           ^" in toVoidArg as{TypeError} core::int;
+           ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t45 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:158:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'int'.
   intVar = toVoidNullableArg;
-           ^" in toVoidNullableArg as{TypeError} core::int;
+           ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t46 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:159:12: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'int'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   intVar = tearoffableArg;
-           ^" in tearoffableArg as{TypeError} core::int;
+           ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t47 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:160:12: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'int'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   intVar = tearoffableNullableArg;
-           ^" in tearoffableNullableArg as{TypeError} core::int;
+           ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t48 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:161:12: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'int'.
   intVar = xNonNullArg;
-           ^" in xNonNullArg as{TypeError} core::int;
+           ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t49 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:162:12: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'int'.
   intVar = xNonNullNullableArg;
-           ^" in xNonNullNullableArg as{TypeError} core::int;
+           ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t50 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:163:12: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'int'.
   intVar = xPotentiallyNullArg;
-           ^" in xPotentiallyNullArg as{TypeError} core::int;
+           ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t51 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:164:12: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'int'.
   intVar = xPotentiallyNullNullableArg;
-           ^" in xPotentiallyNullNullableArg as{TypeError} core::int;
+           ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t52 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:165:12: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'int'.
   intVar = yNonNullArg;
-           ^" in yNonNullArg as{TypeError} core::int;
+           ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t53 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:166:12: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'int'.
   intVar = yNonNullNullableArg;
-           ^" in yNonNullNullableArg as{TypeError} core::int;
+           ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t54 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:167:12: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'int'.
   intVar = yPotentiallyNullArg;
-           ^" in yPotentiallyNullArg as{TypeError} core::int;
+           ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t55 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:168:12: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'int'.
   intVar = yPotentiallyNullNullableArg;
-           ^" in yPotentiallyNullNullableArg as{TypeError} core::int;
+           ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   core::double doubleVar = let final<BottomType> #t56 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:170:22: Error: A value of type 'Object' can't be assigned to a variable of type 'double'.
  - 'Object' is from 'dart:core'.
   double doubleVar = objectArg;
-                     ^" in objectArg as{TypeError} core::double;
+                     ^" in objectArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t57 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:171:15: Error: A value of type 'Object?' can't be assigned to a variable of type 'double'.
  - 'Object' is from 'dart:core'.
   doubleVar = objectNullableArg;
-              ^" in objectNullableArg as{TypeError} core::double;
+              ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t58 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:172:15: Error: A value of type 'num' can't be assigned to a variable of type 'double'.
   doubleVar = numArg;
-              ^" in numArg as{TypeError} core::double;
+              ^" in numArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t59 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:173:15: Error: A value of type 'num?' can't be assigned to a variable of type 'double'.
   doubleVar = numNullableArg;
-              ^" in numNullableArg as{TypeError} core::double;
+              ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t60 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:174:15: Error: A value of type 'int' can't be assigned to a variable of type 'double'.
   doubleVar = intArg;
-              ^" in intArg as{TypeError} core::double;
+              ^" in intArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t61 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:175:15: Error: A value of type 'int?' can't be assigned to a variable of type 'double'.
   doubleVar = intNullableArg;
-              ^" in intNullableArg as{TypeError} core::double;
+              ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t62 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:176:15: Error: A value of type 'double?' can't be assigned to a variable of type 'double'.
   doubleVar = doubleNullableArg;
-              ^" in doubleNullableArg as{TypeError} core::double;
+              ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t63 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:177:15: Error: A value of type 'Function' can't be assigned to a variable of type 'double'.
  - 'Function' is from 'dart:core'.
   doubleVar = functionArg;
-              ^" in functionArg as{TypeError} core::double;
+              ^" in functionArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t64 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:178:15: Error: A value of type 'Function?' can't be assigned to a variable of type 'double'.
  - 'Function' is from 'dart:core'.
   doubleVar = functionNullableArg;
-              ^" in functionNullableArg as{TypeError} core::double;
+              ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t65 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:179:15: Error: A value of type 'void Function()' can't be assigned to a variable of type 'double'.
   doubleVar = toVoidArg;
-              ^" in toVoidArg as{TypeError} core::double;
+              ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t66 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:180:15: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'double'.
   doubleVar = toVoidNullableArg;
-              ^" in toVoidNullableArg as{TypeError} core::double;
+              ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t67 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:181:15: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'double'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   doubleVar = tearoffableArg;
-              ^" in tearoffableArg as{TypeError} core::double;
+              ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t68 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:182:15: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'double'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   doubleVar = tearoffableNullableArg;
-              ^" in tearoffableNullableArg as{TypeError} core::double;
+              ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t69 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:183:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'double'.
   doubleVar = xNonNullArg;
-              ^" in xNonNullArg as{TypeError} core::double;
+              ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t70 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:184:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'double'.
   doubleVar = xNonNullNullableArg;
-              ^" in xNonNullNullableArg as{TypeError} core::double;
+              ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t71 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:185:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'double'.
   doubleVar = xPotentiallyNullArg;
-              ^" in xPotentiallyNullArg as{TypeError} core::double;
+              ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t72 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:186:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'double'.
   doubleVar = xPotentiallyNullNullableArg;
-              ^" in xPotentiallyNullNullableArg as{TypeError} core::double;
+              ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t73 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:187:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'double'.
   doubleVar = yNonNullArg;
-              ^" in yNonNullArg as{TypeError} core::double;
+              ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t74 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:188:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'double'.
   doubleVar = yNonNullNullableArg;
-              ^" in yNonNullNullableArg as{TypeError} core::double;
+              ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t75 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:189:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'double'.
   doubleVar = yPotentiallyNullArg;
-              ^" in yPotentiallyNullArg as{TypeError} core::double;
+              ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t76 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:190:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'double'.
   doubleVar = yPotentiallyNullNullableArg;
-              ^" in yPotentiallyNullNullableArg as{TypeError} core::double;
+              ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   core::Function functionVar = let final<BottomType> #t77 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:192:26: Error: A value of type 'Object' can't be assigned to a variable of type 'Function'.
  - 'Object' is from 'dart:core'.
  - 'Function' is from 'dart:core'.
   Function functionVar = objectArg;
-                         ^" in objectArg as{TypeError} core::Function;
+                         ^" in objectArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t78 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:193:17: Error: A value of type 'Object?' can't be assigned to a variable of type 'Function'.
  - 'Object' is from 'dart:core'.
  - 'Function' is from 'dart:core'.
   functionVar = objectNullableArg;
-                ^" in objectNullableArg as{TypeError} core::Function;
+                ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t79 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:194:17: Error: A value of type 'num' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = numArg;
-                ^" in numArg as{TypeError} core::Function;
+                ^" in numArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t80 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:195:17: Error: A value of type 'num?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} core::Function;
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t81 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:196:17: Error: A value of type 'int' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = intArg;
-                ^" in intArg as{TypeError} core::Function;
+                ^" in intArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t82 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:197:17: Error: A value of type 'int?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} core::Function;
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t83 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:198:17: Error: A value of type 'double' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = doubleArg;
-                ^" in doubleArg as{TypeError} core::Function;
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t84 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:199:17: Error: A value of type 'double?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} core::Function;
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t85 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:200:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = functionNullableArg;
-                ^" in functionNullableArg as{TypeError} core::Function;
+                ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t86 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:201:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = toVoidNullableArg;
-                ^" in toVoidNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t87 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:202:3: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Function'.
- - 'Function' is from 'dart:core'.
+                ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t87 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:202:17: Error: Can't tear off method 'call' from a potentially null value.
   functionVar = tearoffableNullableArg;
-  ^" in (let final self::Tearoffable? #t88 = tearoffableNullableArg in #t88.==(null) ?{() →? void} null : #t88.{self::Tearoffable::call}) as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t89 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
+                ^" in tearoffableNullableArg as{TypeError} core::Function;
+  functionVar = let final<BottomType> #t88 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xNonNullArg;
-                ^" in xNonNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t90 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:204:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Function'.
+                ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t89 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:204:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xNonNullNullableArg;
-                ^" in xNonNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t91 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:205:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Function'.
+                ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t90 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:205:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t92 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:206:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Function'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t91 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:206:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t93 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:207:17: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Function'.
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t92 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:207:17: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yNonNullArg;
-                ^" in yNonNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t94 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:208:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Function'.
+                ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t93 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:208:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yNonNullNullableArg;
-                ^" in yNonNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t95 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:209:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Function'.
+                ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t94 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:209:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t96 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:210:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Function'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t95 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:210:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} core::Function;
-  () → void toVoidVar = let final<BottomType> #t97 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:212:31: Error: A value of type 'Object' can't be assigned to a variable of type 'void Function()'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  () → void toVoidVar = let final<BottomType> #t96 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:212:31: Error: A value of type 'Object' can't be assigned to a variable of type 'void Function()'.
  - 'Object' is from 'dart:core'.
   void Function() toVoidVar = objectArg;
-                              ^" in objectArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t98 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:213:15: Error: A value of type 'Object?' can't be assigned to a variable of type 'void Function()'.
+                              ^" in objectArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t97 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:213:15: Error: A value of type 'Object?' can't be assigned to a variable of type 'void Function()'.
  - 'Object' is from 'dart:core'.
   toVoidVar = objectNullableArg;
-              ^" in objectNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t99 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:214:15: Error: A value of type 'num' can't be assigned to a variable of type 'void Function()'.
+              ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t98 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:214:15: Error: A value of type 'num' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = numArg;
-              ^" in numArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t100 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:215:15: Error: A value of type 'num?' can't be assigned to a variable of type 'void Function()'.
+              ^" in numArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t99 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:215:15: Error: A value of type 'num?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = numNullableArg;
-              ^" in numNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t101 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:216:15: Error: A value of type 'int' can't be assigned to a variable of type 'void Function()'.
+              ^" in numNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t100 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:216:15: Error: A value of type 'int' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = intArg;
-              ^" in intArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t102 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:217:15: Error: A value of type 'int?' can't be assigned to a variable of type 'void Function()'.
+              ^" in intArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t101 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:217:15: Error: A value of type 'int?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = intNullableArg;
-              ^" in intNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t103 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:218:15: Error: A value of type 'double' can't be assigned to a variable of type 'void Function()'.
+              ^" in intNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t102 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:218:15: Error: A value of type 'double' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = doubleArg;
-              ^" in doubleArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t104 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:219:15: Error: A value of type 'double?' can't be assigned to a variable of type 'void Function()'.
+              ^" in doubleArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t103 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:219:15: Error: A value of type 'double?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = doubleNullableArg;
-              ^" in doubleNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t105 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:220:15: Error: A value of type 'Function' can't be assigned to a variable of type 'void Function()'.
+              ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t104 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:220:15: Error: A value of type 'Function' can't be assigned to a variable of type 'void Function()'.
  - 'Function' is from 'dart:core'.
   toVoidVar = functionArg;
-              ^" in functionArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t106 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:221:15: Error: A value of type 'Function?' can't be assigned to a variable of type 'void Function()'.
+              ^" in functionArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t105 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:221:15: Error: A value of type 'Function?' can't be assigned to a variable of type 'void Function()'.
  - 'Function' is from 'dart:core'.
   toVoidVar = functionNullableArg;
-              ^" in functionNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t107 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:222:15: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
+              ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t106 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:222:15: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = toVoidNullableArg;
-              ^" in toVoidNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t108 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:223:3: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
+              ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t107 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:223:15: Error: Can't tear off method 'call' from a potentially null value.
   toVoidVar = tearoffableNullableArg;
-  ^" in (let final self::Tearoffable? #t109 = tearoffableNullableArg in #t109.==(null) ?{() →? void} null : #t109.{self::Tearoffable::call}) as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t110 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in tearoffableNullableArg as{TypeError} () → void;
+  toVoidVar = let final<BottomType> #t108 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xNonNullArg;
-              ^" in xNonNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t111 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:225:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t109 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:225:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xNonNullNullableArg;
-              ^" in xNonNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t112 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:226:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t110 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:226:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xPotentiallyNullArg;
-              ^" in xPotentiallyNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t113 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:227:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t111 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:227:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xPotentiallyNullNullableArg;
-              ^" in xPotentiallyNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t114 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:228:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t112 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:228:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yNonNullArg;
-              ^" in yNonNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t115 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:229:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t113 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:229:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yNonNullNullableArg;
-              ^" in yNonNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t116 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:230:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t114 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:230:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yPotentiallyNullArg;
-              ^" in yPotentiallyNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t117 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:231:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t115 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:231:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yPotentiallyNullNullableArg;
-              ^" in yPotentiallyNullNullableArg as{TypeError} () → void;
-  self::Tearoffable tearoffableVar = let final<BottomType> #t118 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:233:32: Error: A value of type 'Object' can't be assigned to a variable of type 'Tearoffable'.
+              ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  self::Tearoffable tearoffableVar = let final<BottomType> #t116 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:233:32: Error: A value of type 'Object' can't be assigned to a variable of type 'Tearoffable'.
  - 'Object' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   Tearoffable tearoffableVar = objectArg;
-                               ^" in objectArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t119 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:234:20: Error: A value of type 'Object?' can't be assigned to a variable of type 'Tearoffable'.
+                               ^" in objectArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t117 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:234:20: Error: A value of type 'Object?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Object' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = objectNullableArg;
-                   ^" in objectNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t120 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:235:20: Error: A value of type 'num' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t118 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:235:20: Error: A value of type 'num' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = numArg;
-                   ^" in numArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t121 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:236:20: Error: A value of type 'num?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in numArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t119 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:236:20: Error: A value of type 'num?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = numNullableArg;
-                   ^" in numNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t122 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:237:20: Error: A value of type 'int' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in numNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t120 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:237:20: Error: A value of type 'int' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = intArg;
-                   ^" in intArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t123 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:238:20: Error: A value of type 'int?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in intArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t121 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:238:20: Error: A value of type 'int?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = intNullableArg;
-                   ^" in intNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t124 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:239:20: Error: A value of type 'double' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in intNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t122 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:239:20: Error: A value of type 'double' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = doubleArg;
-                   ^" in doubleArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t125 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:240:20: Error: A value of type 'double?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in doubleArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t123 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:240:20: Error: A value of type 'double?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = doubleNullableArg;
-                   ^" in doubleNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t126 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:241:20: Error: A value of type 'Function' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t124 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:241:20: Error: A value of type 'Function' can't be assigned to a variable of type 'Tearoffable'.
  - 'Function' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = functionArg;
-                   ^" in functionArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t127 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:242:20: Error: A value of type 'Function?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in functionArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t125 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:242:20: Error: A value of type 'Function?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Function' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = functionNullableArg;
-                   ^" in functionNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t128 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:243:20: Error: A value of type 'void Function()' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t126 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:243:20: Error: A value of type 'void Function()' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = toVoidArg;
-                   ^" in toVoidArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t129 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:244:20: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in toVoidArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t127 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:244:20: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = toVoidNullableArg;
-                   ^" in toVoidNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t130 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:245:20: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t128 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:245:20: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = tearoffableNullableArg;
-                   ^" in tearoffableNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t131 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:246:20: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t129 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:246:20: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xNonNullArg;
-                   ^" in xNonNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t132 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:247:20: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t130 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:247:20: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xNonNullNullableArg;
-                   ^" in xNonNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t133 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:248:20: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t131 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:248:20: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xPotentiallyNullArg;
-                   ^" in xPotentiallyNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t134 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:249:20: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t132 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:249:20: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xPotentiallyNullNullableArg;
-                   ^" in xPotentiallyNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t135 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:250:20: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t133 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:250:20: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yNonNullArg;
-                   ^" in yNonNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t136 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:251:20: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t134 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:251:20: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yNonNullNullableArg;
-                   ^" in yNonNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t137 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:252:20: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t135 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:252:20: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yPotentiallyNullArg;
-                   ^" in yPotentiallyNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t138 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:253:20: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t136 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:253:20: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yPotentiallyNullNullableArg;
-                   ^" in yPotentiallyNullNullableArg as{TypeError} self::Tearoffable;
-  self::error::XnonNull xNonNullVar = let final<BottomType> #t139 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:255:26: Error: A value of type 'Object' can't be assigned to a variable of type 'XnonNull'.
+                   ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  self::error::XnonNull xNonNullVar = let final<BottomType> #t137 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:255:26: Error: A value of type 'Object' can't be assigned to a variable of type 'XnonNull'.
  - 'Object' is from 'dart:core'.
   XnonNull xNonNullVar = objectArg;
-                         ^" in objectArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t140 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:256:17: Error: A value of type 'Object?' can't be assigned to a variable of type 'XnonNull'.
+                         ^" in objectArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t138 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:256:17: Error: A value of type 'Object?' can't be assigned to a variable of type 'XnonNull'.
  - 'Object' is from 'dart:core'.
   xNonNullVar = objectNullableArg;
-                ^" in objectNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:257:17: Error: A value of type 'num' can't be assigned to a variable of type 'XnonNull'.
+                ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t139 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:257:17: Error: A value of type 'num' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = numArg;
-                ^" in numArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t142 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:258:17: Error: A value of type 'num?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t140 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:258:17: Error: A value of type 'num?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:259:17: Error: A value of type 'int' can't be assigned to a variable of type 'XnonNull'.
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:259:17: Error: A value of type 'int' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = intArg;
-                ^" in intArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t144 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:260:17: Error: A value of type 'int?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t142 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:260:17: Error: A value of type 'int?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:261:17: Error: A value of type 'double' can't be assigned to a variable of type 'XnonNull'.
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:261:17: Error: A value of type 'double' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = doubleArg;
-                ^" in doubleArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t146 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:262:17: Error: A value of type 'double?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t144 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:262:17: Error: A value of type 'double?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:263:17: Error: A value of type 'Function' can't be assigned to a variable of type 'XnonNull'.
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:263:17: Error: A value of type 'Function' can't be assigned to a variable of type 'XnonNull'.
  - 'Function' is from 'dart:core'.
   xNonNullVar = functionArg;
-                ^" in functionArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:264:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t146 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:264:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'XnonNull'.
  - 'Function' is from 'dart:core'.
   xNonNullVar = functionNullableArg;
-                ^" in functionNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t149 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:265:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XnonNull'.
+                ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:265:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = toVoidArg;
-                ^" in toVoidArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:266:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:266:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = toVoidNullableArg;
-                ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:267:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XnonNull'.
+                ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t149 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:267:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xNonNullVar = tearoffableArg;
-                ^" in tearoffableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t152 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:268:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:268:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xNonNullVar = tearoffableNullableArg;
-                ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:269:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:269:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = xNonNullNullableArg;
-                ^" in xNonNullNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:270:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
+                ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t152 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:270:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t155 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:271:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:271:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t156 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:272:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:272:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = yNonNullNullableArg;
-                ^" in yNonNullNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t157 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:273:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
+                ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t155 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:273:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:274:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t156 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:274:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  self::error::XpotentiallyNull% xPotentiallyNullVar = let final<BottomType> #t159 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:276:42: Error: A value of type 'Object' can't be assigned to a variable of type 'XpotentiallyNull'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  self::error::XpotentiallyNull% xPotentiallyNullVar = let final<BottomType> #t157 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:276:42: Error: A value of type 'Object' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Object' is from 'dart:core'.
   XpotentiallyNull xPotentiallyNullVar = objectArg;
-                                         ^" in objectArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t160 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:277:25: Error: A value of type 'Object?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                                         ^" in objectArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:277:25: Error: A value of type 'Object?' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Object' is from 'dart:core'.
   xPotentiallyNullVar = objectNullableArg;
-                        ^" in objectNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t161 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:278:25: Error: A value of type 'num' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t159 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:278:25: Error: A value of type 'num' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = numArg;
-                        ^" in numArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t162 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:279:25: Error: A value of type 'num?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t160 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:279:25: Error: A value of type 'num?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = numNullableArg;
-                        ^" in numNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t163 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:280:25: Error: A value of type 'int' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t161 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:280:25: Error: A value of type 'int' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = intArg;
-                        ^" in intArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t164 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:281:25: Error: A value of type 'int?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t162 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:281:25: Error: A value of type 'int?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = intNullableArg;
-                        ^" in intNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t165 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:282:25: Error: A value of type 'double' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t163 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:282:25: Error: A value of type 'double' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = doubleArg;
-                        ^" in doubleArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t166 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:283:25: Error: A value of type 'double?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t164 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:283:25: Error: A value of type 'double?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = doubleNullableArg;
-                        ^" in doubleNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t167 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:284:25: Error: A value of type 'Function' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t165 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:284:25: Error: A value of type 'Function' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   xPotentiallyNullVar = functionArg;
-                        ^" in functionArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t168 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:285:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t166 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:285:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   xPotentiallyNullVar = functionNullableArg;
-                        ^" in functionNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t169 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:286:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t167 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:286:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = toVoidArg;
-                        ^" in toVoidArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t170 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:287:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t168 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:287:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = toVoidNullableArg;
-                        ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t171 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:288:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t169 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:288:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xPotentiallyNullVar = tearoffableArg;
-                        ^" in tearoffableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t172 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:289:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t170 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:289:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xPotentiallyNullVar = tearoffableNullableArg;
-                        ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t173 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:290:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t171 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:290:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = xNonNullArg;
-                        ^" in xNonNullArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t174 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:291:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t172 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:291:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = xNonNullNullableArg;
-                        ^" in xNonNullNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t175 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:292:25: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t173 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:292:25: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = xPotentiallyNullNullableArg;
-                        ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t176 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:293:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t174 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:293:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = yNonNullArg;
-                        ^" in yNonNullArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t177 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:294:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t175 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:294:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = yNonNullNullableArg;
-                        ^" in yNonNullNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t178 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:295:25: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t176 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:295:25: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = yPotentiallyNullNullableArg;
-                        ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  self::error::YnonNull yNonNullVar = let final<BottomType> #t179 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:297:26: Error: A value of type 'Object' can't be assigned to a variable of type 'YnonNull'.
+                        ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  self::error::YnonNull yNonNullVar = let final<BottomType> #t177 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:297:26: Error: A value of type 'Object' can't be assigned to a variable of type 'YnonNull'.
  - 'Object' is from 'dart:core'.
   YnonNull yNonNullVar = objectArg;
-                         ^" in objectArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t180 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:298:17: Error: A value of type 'Object?' can't be assigned to a variable of type 'YnonNull'.
+                         ^" in objectArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t178 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:298:17: Error: A value of type 'Object?' can't be assigned to a variable of type 'YnonNull'.
  - 'Object' is from 'dart:core'.
   yNonNullVar = objectNullableArg;
-                ^" in objectNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t181 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:299:17: Error: A value of type 'num' can't be assigned to a variable of type 'YnonNull'.
+                ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t179 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:299:17: Error: A value of type 'num' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = numArg;
-                ^" in numArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t182 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:300:17: Error: A value of type 'num?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t180 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:300:17: Error: A value of type 'num?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t183 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:301:17: Error: A value of type 'int' can't be assigned to a variable of type 'YnonNull'.
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t181 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:301:17: Error: A value of type 'int' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = intArg;
-                ^" in intArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t184 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:302:17: Error: A value of type 'int?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t182 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:302:17: Error: A value of type 'int?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t185 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:303:17: Error: A value of type 'double' can't be assigned to a variable of type 'YnonNull'.
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t183 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:303:17: Error: A value of type 'double' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = doubleArg;
-                ^" in doubleArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t186 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:304:17: Error: A value of type 'double?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t184 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:304:17: Error: A value of type 'double?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t187 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:305:17: Error: A value of type 'Function' can't be assigned to a variable of type 'YnonNull'.
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t185 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:305:17: Error: A value of type 'Function' can't be assigned to a variable of type 'YnonNull'.
  - 'Function' is from 'dart:core'.
   yNonNullVar = functionArg;
-                ^" in functionArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t188 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:306:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t186 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:306:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'YnonNull'.
  - 'Function' is from 'dart:core'.
   yNonNullVar = functionNullableArg;
-                ^" in functionNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t189 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:307:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YnonNull'.
+                ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t187 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:307:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = toVoidArg;
-                ^" in toVoidArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t190 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:308:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t188 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:308:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = toVoidNullableArg;
-                ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t191 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:309:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YnonNull'.
+                ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t189 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:309:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yNonNullVar = tearoffableArg;
-                ^" in tearoffableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t192 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:310:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t190 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:310:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yNonNullVar = tearoffableNullableArg;
-                ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t193 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:311:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YnonNull'.
+                ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t191 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:311:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xNonNullArg;
-                ^" in xNonNullArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t194 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:312:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t192 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:312:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xNonNullNullableArg;
-                ^" in xNonNullNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t195 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:313:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
+                ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t193 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:313:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t196 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:314:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t194 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:314:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t197 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:315:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t195 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:315:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = yNonNullNullableArg;
-                ^" in yNonNullNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t198 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:316:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
+                ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t196 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:316:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t199 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:317:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t197 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:317:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  self::error::YpotentiallyNull% yPotentiallyNullVar = let final<BottomType> #t200 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:319:42: Error: A value of type 'Object' can't be assigned to a variable of type 'YpotentiallyNull'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  self::error::YpotentiallyNull% yPotentiallyNullVar = let final<BottomType> #t198 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:319:42: Error: A value of type 'Object' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Object' is from 'dart:core'.
   YpotentiallyNull yPotentiallyNullVar = objectArg;
-                                         ^" in objectArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t201 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:320:25: Error: A value of type 'Object?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                                         ^" in objectArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t199 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:320:25: Error: A value of type 'Object?' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Object' is from 'dart:core'.
   yPotentiallyNullVar = objectNullableArg;
-                        ^" in objectNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t202 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:321:25: Error: A value of type 'num' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in objectNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t200 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:321:25: Error: A value of type 'num' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = numArg;
-                        ^" in numArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t203 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:322:25: Error: A value of type 'num?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t201 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:322:25: Error: A value of type 'num?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = numNullableArg;
-                        ^" in numNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t204 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:323:25: Error: A value of type 'int' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t202 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:323:25: Error: A value of type 'int' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = intArg;
-                        ^" in intArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t205 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:324:25: Error: A value of type 'int?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t203 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:324:25: Error: A value of type 'int?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = intNullableArg;
-                        ^" in intNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t206 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:325:25: Error: A value of type 'double' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t204 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:325:25: Error: A value of type 'double' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = doubleArg;
-                        ^" in doubleArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t207 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:326:25: Error: A value of type 'double?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t205 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:326:25: Error: A value of type 'double?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = doubleNullableArg;
-                        ^" in doubleNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t208 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:327:25: Error: A value of type 'Function' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t206 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:327:25: Error: A value of type 'Function' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   yPotentiallyNullVar = functionArg;
-                        ^" in functionArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t209 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:328:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t207 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:328:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   yPotentiallyNullVar = functionNullableArg;
-                        ^" in functionNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t210 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:329:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t208 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:329:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = toVoidArg;
-                        ^" in toVoidArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t211 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:330:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t209 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:330:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = toVoidNullableArg;
-                        ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t212 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:331:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t210 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:331:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yPotentiallyNullVar = tearoffableArg;
-                        ^" in tearoffableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t213 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:332:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t211 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:332:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yPotentiallyNullVar = tearoffableNullableArg;
-                        ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t214 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:333:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t212 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:333:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xNonNullArg;
-                        ^" in xNonNullArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t215 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:334:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t213 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:334:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xNonNullNullableArg;
-                        ^" in xNonNullNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t216 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:335:25: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t214 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:335:25: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xPotentiallyNullArg;
-                        ^" in xPotentiallyNullArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t217 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:336:25: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t215 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:336:25: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xPotentiallyNullNullableArg;
-                        ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t218 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:337:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t216 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:337:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = yNonNullArg;
-                        ^" in yNonNullArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t219 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:338:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t217 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:338:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = yNonNullNullableArg;
-                        ^" in yNonNullNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t220 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:339:25: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t218 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:339:25: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = yPotentiallyNullNullableArg;
-                        ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
+                        ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/assignability.dart.weak.expect b/pkg/front_end/testcases/nnbd/assignability.dart.weak.expect
index 8775e92..55036c6 100644
--- a/pkg/front_end/testcases/nnbd/assignability.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/assignability.dart.weak.expect
@@ -383,10 +383,9 @@
 //   functionVar = toVoidNullableArg;
 //   ^
 //
-// pkg/front_end/testcases/nnbd/assignability.dart:202:3: Warning: Assigning value of type 'void Function()?' to a variable of type 'Function'.
-//  - 'Function' is from 'dart:core'.
+// pkg/front_end/testcases/nnbd/assignability.dart:202:17: Warning: Tearing off method 'call' from a potentially null value.
 //   functionVar = tearoffableNullableArg;
-//   ^
+//                 ^
 //
 // pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
 //  - 'Function' is from 'dart:core'.
@@ -476,9 +475,9 @@
 //   toVoidVar = toVoidNullableArg;
 //   ^
 //
-// pkg/front_end/testcases/nnbd/assignability.dart:223:3: Warning: Assigning value of type 'void Function()?' to a variable of type 'void Function()'.
+// pkg/front_end/testcases/nnbd/assignability.dart:223:15: Warning: Tearing off method 'call' from a potentially null value.
 //   toVoidVar = tearoffableNullableArg;
-//   ^
+//               ^
 //
 // pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
 //   toVoidVar = xNonNullArg;
@@ -1004,32 +1003,32 @@
   objectVar = tearoffableArg;
   objectVar = xNonNullArg;
   objectVar = yNonNullArg;
-  core::num numVar = dynamicArg as{TypeError} core::num;
+  core::num numVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::num;
   numVar = numArg;
   numVar = intArg;
   numVar = doubleArg;
-  core::int intVar = dynamicArg as{TypeError} core::int;
+  core::int intVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
   intVar = intArg;
-  core::double doubleVar = dynamicArg as{TypeError} core::double;
+  core::double doubleVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::double;
   doubleVar = doubleArg;
-  core::Function functionVar = dynamicArg as{TypeError} core::Function;
+  core::Function functionVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::Function;
   functionVar = functionArg;
   functionVar = toVoidArg;
   functionVar = let final self::Tearoffable #t1 = tearoffableArg in #t1.==(null) ?{() → void} null : #t1.{self::Tearoffable::call};
-  () → void toVoidVar = dynamicArg as{TypeError} () → void;
+  () → void toVoidVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} () → void;
   toVoidVar = toVoidArg;
   toVoidVar = let final self::Tearoffable #t2 = tearoffableArg in #t2.==(null) ?{() → void} null : #t2.{self::Tearoffable::call};
-  self::Tearoffable tearoffableVar = dynamicArg as{TypeError} self::Tearoffable;
+  self::Tearoffable tearoffableVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::Tearoffable;
   tearoffableVar = tearoffableArg;
-  self::ok::XnonNull xNonNullVar = dynamicArg as{TypeError} self::ok::XnonNull;
+  self::ok::XnonNull xNonNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::XnonNull;
   xNonNullVar = xNonNullArg;
   xNonNullVar = yNonNullArg;
-  self::ok::YnonNull yNonNullVar = dynamicArg as{TypeError} self::ok::YnonNull;
+  self::ok::YnonNull yNonNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::YnonNull;
   yNonNullVar = yNonNullArg;
-  self::ok::XpotentiallyNull% xPotentiallyNullVar = dynamicArg as{TypeError} self::ok::XpotentiallyNull%;
+  self::ok::XpotentiallyNull% xPotentiallyNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::XpotentiallyNull%;
   xPotentiallyNullVar = xPotentiallyNullArg;
   xPotentiallyNullVar = yPotentiallyNullArg;
-  self::ok::YpotentiallyNull% yPotentiallyNullVar = dynamicArg as{TypeError} self::ok::YpotentiallyNull%;
+  self::ok::YpotentiallyNull% yPotentiallyNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::YpotentiallyNull%;
   yPotentiallyNullVar = yPotentiallyNullArg;
 }
 static method error<XnonNull extends core::Object = core::Object, YnonNull extends self::error::XnonNull = core::Object, XpotentiallyNull extends core::Object? = core::Object?, YpotentiallyNull extends self::error::XpotentiallyNull% = core::Object?>(core::Object objectArg, core::Object? objectNullableArg, core::num numArg, core::num? numNullableArg, core::int intArg, core::int? intNullableArg, core::double doubleArg, core::double? doubleNullableArg, core::Function functionArg, core::Function? functionNullableArg, () → void toVoidArg, () →? void toVoidNullableArg, self::Tearoffable tearoffableArg, self::Tearoffable? tearoffableNullableArg, self::error::XnonNull xNonNullArg, self::error::XnonNull? xNonNullNullableArg, self::error::XpotentiallyNull% xPotentiallyNullArg, self::error::XpotentiallyNull? xPotentiallyNullNullableArg, self::error::YnonNull yNonNullArg, self::error::YnonNull? yNonNullNullableArg, self::error::YpotentiallyNull% yPotentiallyNullArg, self::error::YpotentiallyNull? yPotentiallyNullNullableArg) → dynamic {
@@ -1046,582 +1045,582 @@
   objectVar = yNonNullNullableArg;
   objectVar = yPotentiallyNullArg;
   objectVar = yPotentiallyNullNullableArg;
-  core::num numVar = objectArg as{TypeError} core::num;
-  numVar = objectNullableArg as{TypeError} core::num;
+  core::num numVar = objectArg as{TypeError,ForNonNullableByDefault} core::num;
+  numVar = objectNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = numNullableArg;
   numVar = intNullableArg;
   numVar = doubleNullableArg;
   numVar = let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:133:12: Error: A value of type 'Function' can't be assigned to a variable of type 'num'.
  - 'Function' is from 'dart:core'.
   numVar = functionArg;
-           ^" in functionArg as{TypeError} core::num;
+           ^" in functionArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:134:12: Error: A value of type 'Function?' can't be assigned to a variable of type 'num'.
  - 'Function' is from 'dart:core'.
   numVar = functionNullableArg;
-           ^" in functionNullableArg as{TypeError} core::num;
+           ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:135:12: Error: A value of type 'void Function()' can't be assigned to a variable of type 'num'.
   numVar = toVoidArg;
-           ^" in toVoidArg as{TypeError} core::num;
+           ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:136:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'num'.
   numVar = toVoidNullableArg;
-           ^" in toVoidNullableArg as{TypeError} core::num;
+           ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:137:12: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'num'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   numVar = tearoffableArg;
-           ^" in tearoffableArg as{TypeError} core::num;
+           ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:138:12: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'num'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   numVar = tearoffableNullableArg;
-           ^" in tearoffableNullableArg as{TypeError} core::num;
+           ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:139:12: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'num'.
   numVar = xNonNullArg;
-           ^" in xNonNullArg as{TypeError} core::num;
+           ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:140:12: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'num'.
   numVar = xNonNullNullableArg;
-           ^" in xNonNullNullableArg as{TypeError} core::num;
+           ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:141:12: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'num'.
   numVar = xPotentiallyNullArg;
-           ^" in xPotentiallyNullArg as{TypeError} core::num;
+           ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:142:12: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'num'.
   numVar = xPotentiallyNullNullableArg;
-           ^" in xPotentiallyNullNullableArg as{TypeError} core::num;
+           ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t13 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:143:12: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'num'.
   numVar = yNonNullArg;
-           ^" in yNonNullArg as{TypeError} core::num;
+           ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t14 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:144:12: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'num'.
   numVar = yNonNullNullableArg;
-           ^" in yNonNullNullableArg as{TypeError} core::num;
+           ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t15 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:145:12: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'num'.
   numVar = yPotentiallyNullArg;
-           ^" in yPotentiallyNullArg as{TypeError} core::num;
+           ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t16 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:146:12: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'num'.
   numVar = yPotentiallyNullNullableArg;
-           ^" in yPotentiallyNullNullableArg as{TypeError} core::num;
-  core::int intVar = objectArg as{TypeError} core::int;
-  intVar = objectNullableArg as{TypeError} core::int;
-  intVar = numArg as{TypeError} core::int;
-  intVar = numNullableArg as{TypeError} core::int;
+           ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
+  core::int intVar = objectArg as{TypeError,ForNonNullableByDefault} core::int;
+  intVar = objectNullableArg as{TypeError,ForNonNullableByDefault} core::int;
+  intVar = numArg as{TypeError,ForNonNullableByDefault} core::int;
+  intVar = numNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = intNullableArg;
   intVar = let final<BottomType> #t17 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:153:12: Error: A value of type 'double' can't be assigned to a variable of type 'int'.
   intVar = doubleArg;
-           ^" in doubleArg as{TypeError} core::int;
+           ^" in doubleArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t18 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:154:12: Error: A value of type 'double?' can't be assigned to a variable of type 'int'.
   intVar = doubleNullableArg;
-           ^" in doubleNullableArg as{TypeError} core::int;
+           ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t19 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:155:12: Error: A value of type 'Function' can't be assigned to a variable of type 'int'.
  - 'Function' is from 'dart:core'.
   intVar = functionArg;
-           ^" in functionArg as{TypeError} core::int;
+           ^" in functionArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t20 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:156:12: Error: A value of type 'Function?' can't be assigned to a variable of type 'int'.
  - 'Function' is from 'dart:core'.
   intVar = functionNullableArg;
-           ^" in functionNullableArg as{TypeError} core::int;
+           ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t21 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:157:12: Error: A value of type 'void Function()' can't be assigned to a variable of type 'int'.
   intVar = toVoidArg;
-           ^" in toVoidArg as{TypeError} core::int;
+           ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t22 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:158:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'int'.
   intVar = toVoidNullableArg;
-           ^" in toVoidNullableArg as{TypeError} core::int;
+           ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t23 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:159:12: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'int'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   intVar = tearoffableArg;
-           ^" in tearoffableArg as{TypeError} core::int;
+           ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t24 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:160:12: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'int'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   intVar = tearoffableNullableArg;
-           ^" in tearoffableNullableArg as{TypeError} core::int;
+           ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t25 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:161:12: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'int'.
   intVar = xNonNullArg;
-           ^" in xNonNullArg as{TypeError} core::int;
+           ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t26 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:162:12: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'int'.
   intVar = xNonNullNullableArg;
-           ^" in xNonNullNullableArg as{TypeError} core::int;
+           ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t27 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:163:12: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'int'.
   intVar = xPotentiallyNullArg;
-           ^" in xPotentiallyNullArg as{TypeError} core::int;
+           ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t28 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:164:12: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'int'.
   intVar = xPotentiallyNullNullableArg;
-           ^" in xPotentiallyNullNullableArg as{TypeError} core::int;
+           ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t29 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:165:12: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'int'.
   intVar = yNonNullArg;
-           ^" in yNonNullArg as{TypeError} core::int;
+           ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t30 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:166:12: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'int'.
   intVar = yNonNullNullableArg;
-           ^" in yNonNullNullableArg as{TypeError} core::int;
+           ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t31 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:167:12: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'int'.
   intVar = yPotentiallyNullArg;
-           ^" in yPotentiallyNullArg as{TypeError} core::int;
+           ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t32 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:168:12: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'int'.
   intVar = yPotentiallyNullNullableArg;
-           ^" in yPotentiallyNullNullableArg as{TypeError} core::int;
-  core::double doubleVar = objectArg as{TypeError} core::double;
-  doubleVar = objectNullableArg as{TypeError} core::double;
-  doubleVar = numArg as{TypeError} core::double;
-  doubleVar = numNullableArg as{TypeError} core::double;
+           ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
+  core::double doubleVar = objectArg as{TypeError,ForNonNullableByDefault} core::double;
+  doubleVar = objectNullableArg as{TypeError,ForNonNullableByDefault} core::double;
+  doubleVar = numArg as{TypeError,ForNonNullableByDefault} core::double;
+  doubleVar = numNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t33 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:174:15: Error: A value of type 'int' can't be assigned to a variable of type 'double'.
   doubleVar = intArg;
-              ^" in intArg as{TypeError} core::double;
+              ^" in intArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t34 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:175:15: Error: A value of type 'int?' can't be assigned to a variable of type 'double'.
   doubleVar = intNullableArg;
-              ^" in intNullableArg as{TypeError} core::double;
+              ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = doubleNullableArg;
   doubleVar = let final<BottomType> #t35 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:177:15: Error: A value of type 'Function' can't be assigned to a variable of type 'double'.
  - 'Function' is from 'dart:core'.
   doubleVar = functionArg;
-              ^" in functionArg as{TypeError} core::double;
+              ^" in functionArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t36 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:178:15: Error: A value of type 'Function?' can't be assigned to a variable of type 'double'.
  - 'Function' is from 'dart:core'.
   doubleVar = functionNullableArg;
-              ^" in functionNullableArg as{TypeError} core::double;
+              ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t37 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:179:15: Error: A value of type 'void Function()' can't be assigned to a variable of type 'double'.
   doubleVar = toVoidArg;
-              ^" in toVoidArg as{TypeError} core::double;
+              ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t38 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:180:15: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'double'.
   doubleVar = toVoidNullableArg;
-              ^" in toVoidNullableArg as{TypeError} core::double;
+              ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t39 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:181:15: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'double'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   doubleVar = tearoffableArg;
-              ^" in tearoffableArg as{TypeError} core::double;
+              ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t40 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:182:15: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'double'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   doubleVar = tearoffableNullableArg;
-              ^" in tearoffableNullableArg as{TypeError} core::double;
+              ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t41 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:183:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'double'.
   doubleVar = xNonNullArg;
-              ^" in xNonNullArg as{TypeError} core::double;
+              ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t42 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:184:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'double'.
   doubleVar = xNonNullNullableArg;
-              ^" in xNonNullNullableArg as{TypeError} core::double;
+              ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t43 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:185:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'double'.
   doubleVar = xPotentiallyNullArg;
-              ^" in xPotentiallyNullArg as{TypeError} core::double;
+              ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t44 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:186:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'double'.
   doubleVar = xPotentiallyNullNullableArg;
-              ^" in xPotentiallyNullNullableArg as{TypeError} core::double;
+              ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t45 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:187:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'double'.
   doubleVar = yNonNullArg;
-              ^" in yNonNullArg as{TypeError} core::double;
+              ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t46 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:188:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'double'.
   doubleVar = yNonNullNullableArg;
-              ^" in yNonNullNullableArg as{TypeError} core::double;
+              ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t47 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:189:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'double'.
   doubleVar = yPotentiallyNullArg;
-              ^" in yPotentiallyNullArg as{TypeError} core::double;
+              ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t48 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:190:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'double'.
   doubleVar = yPotentiallyNullNullableArg;
-              ^" in yPotentiallyNullNullableArg as{TypeError} core::double;
-  core::Function functionVar = objectArg as{TypeError} core::Function;
-  functionVar = objectNullableArg as{TypeError} core::Function;
+              ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
+  core::Function functionVar = objectArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = objectNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t49 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:194:17: Error: A value of type 'num' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = numArg;
-                ^" in numArg as{TypeError} core::Function;
+                ^" in numArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t50 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:195:17: Error: A value of type 'num?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} core::Function;
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t51 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:196:17: Error: A value of type 'int' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = intArg;
-                ^" in intArg as{TypeError} core::Function;
+                ^" in intArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t52 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:197:17: Error: A value of type 'int?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} core::Function;
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t53 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:198:17: Error: A value of type 'double' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = doubleArg;
-                ^" in doubleArg as{TypeError} core::Function;
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t54 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:199:17: Error: A value of type 'double?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} core::Function;
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = functionNullableArg;
   functionVar = toVoidNullableArg;
-  functionVar = let final self::Tearoffable? #t55 = tearoffableNullableArg in #t55.==(null) ?{() →? void} null : #t55.{self::Tearoffable::call};
-  functionVar = let final<BottomType> #t56 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
+  functionVar = tearoffableNullableArg as{TypeError} core::Function;
+  functionVar = let final<BottomType> #t55 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xNonNullArg;
-                ^" in xNonNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t57 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:204:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Function'.
+                ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t56 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:204:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xNonNullNullableArg;
-                ^" in xNonNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t58 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:205:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Function'.
+                ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t57 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:205:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t59 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:206:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Function'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t58 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:206:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t60 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:207:17: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Function'.
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t59 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:207:17: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yNonNullArg;
-                ^" in yNonNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t61 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:208:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Function'.
+                ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t60 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:208:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yNonNullNullableArg;
-                ^" in yNonNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t62 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:209:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Function'.
+                ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t61 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:209:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t63 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:210:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Function'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t62 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:210:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} core::Function;
-  () → void toVoidVar = objectArg as{TypeError} () → void;
-  toVoidVar = objectNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t64 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:214:15: Error: A value of type 'num' can't be assigned to a variable of type 'void Function()'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  () → void toVoidVar = objectArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = objectNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t63 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:214:15: Error: A value of type 'num' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = numArg;
-              ^" in numArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t65 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:215:15: Error: A value of type 'num?' can't be assigned to a variable of type 'void Function()'.
+              ^" in numArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t64 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:215:15: Error: A value of type 'num?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = numNullableArg;
-              ^" in numNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t66 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:216:15: Error: A value of type 'int' can't be assigned to a variable of type 'void Function()'.
+              ^" in numNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t65 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:216:15: Error: A value of type 'int' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = intArg;
-              ^" in intArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t67 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:217:15: Error: A value of type 'int?' can't be assigned to a variable of type 'void Function()'.
+              ^" in intArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t66 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:217:15: Error: A value of type 'int?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = intNullableArg;
-              ^" in intNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t68 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:218:15: Error: A value of type 'double' can't be assigned to a variable of type 'void Function()'.
+              ^" in intNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t67 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:218:15: Error: A value of type 'double' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = doubleArg;
-              ^" in doubleArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t69 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:219:15: Error: A value of type 'double?' can't be assigned to a variable of type 'void Function()'.
+              ^" in doubleArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t68 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:219:15: Error: A value of type 'double?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = doubleNullableArg;
-              ^" in doubleNullableArg as{TypeError} () → void;
-  toVoidVar = functionArg as{TypeError} () → void;
-  toVoidVar = functionNullableArg as{TypeError} () → void;
+              ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = functionArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = functionNullableArg as{TypeError,ForNonNullableByDefault} () → void;
   toVoidVar = toVoidNullableArg;
-  toVoidVar = let final self::Tearoffable? #t70 = tearoffableNullableArg in #t70.==(null) ?{() →? void} null : #t70.{self::Tearoffable::call};
-  toVoidVar = let final<BottomType> #t71 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
+  toVoidVar = tearoffableNullableArg as{TypeError} () → void;
+  toVoidVar = let final<BottomType> #t69 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xNonNullArg;
-              ^" in xNonNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t72 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:225:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t70 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:225:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xNonNullNullableArg;
-              ^" in xNonNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t73 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:226:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t71 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:226:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xPotentiallyNullArg;
-              ^" in xPotentiallyNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t74 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:227:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t72 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:227:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xPotentiallyNullNullableArg;
-              ^" in xPotentiallyNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t75 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:228:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t73 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:228:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yNonNullArg;
-              ^" in yNonNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t76 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:229:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t74 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:229:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yNonNullNullableArg;
-              ^" in yNonNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t77 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:230:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t75 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:230:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yPotentiallyNullArg;
-              ^" in yPotentiallyNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t78 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:231:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t76 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:231:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yPotentiallyNullNullableArg;
-              ^" in yPotentiallyNullNullableArg as{TypeError} () → void;
-  self::Tearoffable tearoffableVar = objectArg as{TypeError} self::Tearoffable;
-  tearoffableVar = objectNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t79 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:235:20: Error: A value of type 'num' can't be assigned to a variable of type 'Tearoffable'.
+              ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  self::Tearoffable tearoffableVar = objectArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = objectNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t77 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:235:20: Error: A value of type 'num' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = numArg;
-                   ^" in numArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t80 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:236:20: Error: A value of type 'num?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in numArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t78 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:236:20: Error: A value of type 'num?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = numNullableArg;
-                   ^" in numNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t81 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:237:20: Error: A value of type 'int' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in numNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t79 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:237:20: Error: A value of type 'int' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = intArg;
-                   ^" in intArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t82 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:238:20: Error: A value of type 'int?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in intArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t80 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:238:20: Error: A value of type 'int?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = intNullableArg;
-                   ^" in intNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t83 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:239:20: Error: A value of type 'double' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in intNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t81 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:239:20: Error: A value of type 'double' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = doubleArg;
-                   ^" in doubleArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t84 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:240:20: Error: A value of type 'double?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in doubleArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t82 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:240:20: Error: A value of type 'double?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = doubleNullableArg;
-                   ^" in doubleNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t85 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:241:20: Error: A value of type 'Function' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t83 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:241:20: Error: A value of type 'Function' can't be assigned to a variable of type 'Tearoffable'.
  - 'Function' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = functionArg;
-                   ^" in functionArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t86 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:242:20: Error: A value of type 'Function?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in functionArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t84 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:242:20: Error: A value of type 'Function?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Function' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = functionNullableArg;
-                   ^" in functionNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t87 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:243:20: Error: A value of type 'void Function()' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t85 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:243:20: Error: A value of type 'void Function()' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = toVoidArg;
-                   ^" in toVoidArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t88 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:244:20: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in toVoidArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t86 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:244:20: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = toVoidNullableArg;
-                   ^" in toVoidNullableArg as{TypeError} self::Tearoffable;
+                   ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
   tearoffableVar = tearoffableNullableArg;
-  tearoffableVar = let final<BottomType> #t89 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:246:20: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Tearoffable'.
+  tearoffableVar = let final<BottomType> #t87 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:246:20: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xNonNullArg;
-                   ^" in xNonNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t90 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:247:20: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t88 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:247:20: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xNonNullNullableArg;
-                   ^" in xNonNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t91 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:248:20: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t89 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:248:20: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xPotentiallyNullArg;
-                   ^" in xPotentiallyNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t92 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:249:20: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t90 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:249:20: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xPotentiallyNullNullableArg;
-                   ^" in xPotentiallyNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t93 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:250:20: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t91 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:250:20: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yNonNullArg;
-                   ^" in yNonNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t94 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:251:20: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t92 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:251:20: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yNonNullNullableArg;
-                   ^" in yNonNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t95 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:252:20: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t93 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:252:20: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yPotentiallyNullArg;
-                   ^" in yPotentiallyNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t96 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:253:20: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t94 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:253:20: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yPotentiallyNullNullableArg;
-                   ^" in yPotentiallyNullNullableArg as{TypeError} self::Tearoffable;
-  self::error::XnonNull xNonNullVar = objectArg as{TypeError} self::error::XnonNull;
-  xNonNullVar = objectNullableArg as{TypeError} self::error::XnonNull;
-  xNonNullVar = let final<BottomType> #t97 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:257:17: Error: A value of type 'num' can't be assigned to a variable of type 'XnonNull'.
+                   ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  self::error::XnonNull xNonNullVar = objectArg as{TypeError,ForNonNullableByDefault} self::error::XnonNull;
+  xNonNullVar = objectNullableArg as{TypeError,ForNonNullableByDefault} self::error::XnonNull;
+  xNonNullVar = let final<BottomType> #t95 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:257:17: Error: A value of type 'num' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = numArg;
-                ^" in numArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t98 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:258:17: Error: A value of type 'num?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t96 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:258:17: Error: A value of type 'num?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t99 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:259:17: Error: A value of type 'int' can't be assigned to a variable of type 'XnonNull'.
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t97 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:259:17: Error: A value of type 'int' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = intArg;
-                ^" in intArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t100 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:260:17: Error: A value of type 'int?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t98 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:260:17: Error: A value of type 'int?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t101 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:261:17: Error: A value of type 'double' can't be assigned to a variable of type 'XnonNull'.
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t99 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:261:17: Error: A value of type 'double' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = doubleArg;
-                ^" in doubleArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t102 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:262:17: Error: A value of type 'double?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t100 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:262:17: Error: A value of type 'double?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t103 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:263:17: Error: A value of type 'Function' can't be assigned to a variable of type 'XnonNull'.
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t101 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:263:17: Error: A value of type 'Function' can't be assigned to a variable of type 'XnonNull'.
  - 'Function' is from 'dart:core'.
   xNonNullVar = functionArg;
-                ^" in functionArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t104 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:264:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t102 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:264:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'XnonNull'.
  - 'Function' is from 'dart:core'.
   xNonNullVar = functionNullableArg;
-                ^" in functionNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t105 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:265:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XnonNull'.
+                ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t103 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:265:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = toVoidArg;
-                ^" in toVoidArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t106 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:266:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t104 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:266:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = toVoidNullableArg;
-                ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t107 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:267:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XnonNull'.
+                ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t105 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:267:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xNonNullVar = tearoffableArg;
-                ^" in tearoffableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t108 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:268:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t106 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:268:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xNonNullVar = tearoffableNullableArg;
-                ^" in tearoffableNullableArg as{TypeError} <BottomType>;
+                ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   xNonNullVar = xNonNullNullableArg;
-  xNonNullVar = let final<BottomType> #t109 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:270:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
+  xNonNullVar = let final<BottomType> #t107 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:270:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t110 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:271:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t108 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:271:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   xNonNullVar = yNonNullNullableArg;
-  xNonNullVar = let final<BottomType> #t111 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:273:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
+  xNonNullVar = let final<BottomType> #t109 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:273:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t112 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:274:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t110 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:274:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  self::error::XpotentiallyNull% xPotentiallyNullVar = objectArg as{TypeError} self::error::XpotentiallyNull%;
-  xPotentiallyNullVar = objectNullableArg as{TypeError} self::error::XpotentiallyNull%;
-  xPotentiallyNullVar = let final<BottomType> #t113 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:278:25: Error: A value of type 'num' can't be assigned to a variable of type 'XpotentiallyNull'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  self::error::XpotentiallyNull% xPotentiallyNullVar = objectArg as{TypeError,ForNonNullableByDefault} self::error::XpotentiallyNull%;
+  xPotentiallyNullVar = objectNullableArg as{TypeError,ForNonNullableByDefault} self::error::XpotentiallyNull%;
+  xPotentiallyNullVar = let final<BottomType> #t111 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:278:25: Error: A value of type 'num' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = numArg;
-                        ^" in numArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t114 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:279:25: Error: A value of type 'num?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t112 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:279:25: Error: A value of type 'num?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = numNullableArg;
-                        ^" in numNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t115 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:280:25: Error: A value of type 'int' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t113 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:280:25: Error: A value of type 'int' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = intArg;
-                        ^" in intArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t116 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:281:25: Error: A value of type 'int?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t114 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:281:25: Error: A value of type 'int?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = intNullableArg;
-                        ^" in intNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t117 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:282:25: Error: A value of type 'double' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t115 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:282:25: Error: A value of type 'double' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = doubleArg;
-                        ^" in doubleArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t118 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:283:25: Error: A value of type 'double?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t116 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:283:25: Error: A value of type 'double?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = doubleNullableArg;
-                        ^" in doubleNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t119 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:284:25: Error: A value of type 'Function' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t117 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:284:25: Error: A value of type 'Function' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   xPotentiallyNullVar = functionArg;
-                        ^" in functionArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t120 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:285:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t118 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:285:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   xPotentiallyNullVar = functionNullableArg;
-                        ^" in functionNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t121 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:286:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t119 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:286:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = toVoidArg;
-                        ^" in toVoidArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t122 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:287:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t120 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:287:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = toVoidNullableArg;
-                        ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t123 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:288:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t121 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:288:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xPotentiallyNullVar = tearoffableArg;
-                        ^" in tearoffableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t124 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:289:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t122 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:289:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xPotentiallyNullVar = tearoffableNullableArg;
-                        ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t125 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:290:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t123 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:290:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = xNonNullArg;
-                        ^" in xNonNullArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t126 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:291:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t124 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:291:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = xNonNullNullableArg;
-                        ^" in xNonNullNullableArg as{TypeError} <BottomType>;
+                        ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   xPotentiallyNullVar = xPotentiallyNullNullableArg;
-  xPotentiallyNullVar = let final<BottomType> #t127 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:293:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
+  xPotentiallyNullVar = let final<BottomType> #t125 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:293:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = yNonNullArg;
-                        ^" in yNonNullArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t128 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:294:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t126 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:294:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = yNonNullNullableArg;
-                        ^" in yNonNullNullableArg as{TypeError} <BottomType>;
+                        ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   xPotentiallyNullVar = yPotentiallyNullNullableArg;
-  self::error::YnonNull yNonNullVar = objectArg as{TypeError} self::error::YnonNull;
-  yNonNullVar = objectNullableArg as{TypeError} self::error::YnonNull;
-  yNonNullVar = let final<BottomType> #t129 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:299:17: Error: A value of type 'num' can't be assigned to a variable of type 'YnonNull'.
+  self::error::YnonNull yNonNullVar = objectArg as{TypeError,ForNonNullableByDefault} self::error::YnonNull;
+  yNonNullVar = objectNullableArg as{TypeError,ForNonNullableByDefault} self::error::YnonNull;
+  yNonNullVar = let final<BottomType> #t127 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:299:17: Error: A value of type 'num' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = numArg;
-                ^" in numArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t130 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:300:17: Error: A value of type 'num?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t128 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:300:17: Error: A value of type 'num?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t131 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:301:17: Error: A value of type 'int' can't be assigned to a variable of type 'YnonNull'.
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t129 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:301:17: Error: A value of type 'int' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = intArg;
-                ^" in intArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t132 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:302:17: Error: A value of type 'int?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t130 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:302:17: Error: A value of type 'int?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t133 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:303:17: Error: A value of type 'double' can't be assigned to a variable of type 'YnonNull'.
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t131 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:303:17: Error: A value of type 'double' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = doubleArg;
-                ^" in doubleArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t134 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:304:17: Error: A value of type 'double?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t132 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:304:17: Error: A value of type 'double?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t135 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:305:17: Error: A value of type 'Function' can't be assigned to a variable of type 'YnonNull'.
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t133 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:305:17: Error: A value of type 'Function' can't be assigned to a variable of type 'YnonNull'.
  - 'Function' is from 'dart:core'.
   yNonNullVar = functionArg;
-                ^" in functionArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t136 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:306:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t134 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:306:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'YnonNull'.
  - 'Function' is from 'dart:core'.
   yNonNullVar = functionNullableArg;
-                ^" in functionNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t137 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:307:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YnonNull'.
+                ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t135 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:307:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = toVoidArg;
-                ^" in toVoidArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t138 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:308:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t136 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:308:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = toVoidNullableArg;
-                ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t139 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:309:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YnonNull'.
+                ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t137 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:309:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yNonNullVar = tearoffableArg;
-                ^" in tearoffableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t140 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:310:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t138 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:310:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yNonNullVar = tearoffableNullableArg;
-                ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = xNonNullArg as{TypeError} self::error::YnonNull;
-  yNonNullVar = xNonNullNullableArg as{TypeError} self::error::YnonNull;
-  yNonNullVar = let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:313:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
+                ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = xNonNullArg as{TypeError,ForNonNullableByDefault} self::error::YnonNull;
+  yNonNullVar = xNonNullNullableArg as{TypeError,ForNonNullableByDefault} self::error::YnonNull;
+  yNonNullVar = let final<BottomType> #t139 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:313:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t142 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:314:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t140 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:314:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   yNonNullVar = yNonNullNullableArg;
-  yNonNullVar = let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:316:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
+  yNonNullVar = let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:316:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t144 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:317:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t142 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:317:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  self::error::YpotentiallyNull% yPotentiallyNullVar = objectArg as{TypeError} self::error::YpotentiallyNull%;
-  yPotentiallyNullVar = objectNullableArg as{TypeError} self::error::YpotentiallyNull%;
-  yPotentiallyNullVar = let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:321:25: Error: A value of type 'num' can't be assigned to a variable of type 'YpotentiallyNull'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  self::error::YpotentiallyNull% yPotentiallyNullVar = objectArg as{TypeError,ForNonNullableByDefault} self::error::YpotentiallyNull%;
+  yPotentiallyNullVar = objectNullableArg as{TypeError,ForNonNullableByDefault} self::error::YpotentiallyNull%;
+  yPotentiallyNullVar = let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:321:25: Error: A value of type 'num' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = numArg;
-                        ^" in numArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t146 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:322:25: Error: A value of type 'num?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t144 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:322:25: Error: A value of type 'num?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = numNullableArg;
-                        ^" in numNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:323:25: Error: A value of type 'int' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:323:25: Error: A value of type 'int' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = intArg;
-                        ^" in intArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:324:25: Error: A value of type 'int?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t146 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:324:25: Error: A value of type 'int?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = intNullableArg;
-                        ^" in intNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t149 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:325:25: Error: A value of type 'double' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:325:25: Error: A value of type 'double' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = doubleArg;
-                        ^" in doubleArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:326:25: Error: A value of type 'double?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:326:25: Error: A value of type 'double?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = doubleNullableArg;
-                        ^" in doubleNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:327:25: Error: A value of type 'Function' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t149 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:327:25: Error: A value of type 'Function' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   yPotentiallyNullVar = functionArg;
-                        ^" in functionArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t152 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:328:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:328:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   yPotentiallyNullVar = functionNullableArg;
-                        ^" in functionNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:329:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:329:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = toVoidArg;
-                        ^" in toVoidArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:330:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t152 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:330:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = toVoidNullableArg;
-                        ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t155 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:331:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:331:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yPotentiallyNullVar = tearoffableArg;
-                        ^" in tearoffableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t156 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:332:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:332:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yPotentiallyNullVar = tearoffableNullableArg;
-                        ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t157 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:333:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t155 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:333:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xNonNullArg;
-                        ^" in xNonNullArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:334:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t156 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:334:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xNonNullNullableArg;
-                        ^" in xNonNullNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = xPotentiallyNullArg as{TypeError} self::error::YpotentiallyNull%;
-  yPotentiallyNullVar = xPotentiallyNullNullableArg as{TypeError} self::error::YpotentiallyNull%;
-  yPotentiallyNullVar = let final<BottomType> #t159 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:337:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} self::error::YpotentiallyNull%;
+  yPotentiallyNullVar = xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} self::error::YpotentiallyNull%;
+  yPotentiallyNullVar = let final<BottomType> #t157 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:337:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = yNonNullArg;
-                        ^" in yNonNullArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t160 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:338:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:338:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = yNonNullNullableArg;
-                        ^" in yNonNullNullableArg as{TypeError} <BottomType>;
+                        ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   yPotentiallyNullVar = yPotentiallyNullNullableArg;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/assignability.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/assignability.dart.weak.transformed.expect
index 8775e92..55036c6 100644
--- a/pkg/front_end/testcases/nnbd/assignability.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/assignability.dart.weak.transformed.expect
@@ -383,10 +383,9 @@
 //   functionVar = toVoidNullableArg;
 //   ^
 //
-// pkg/front_end/testcases/nnbd/assignability.dart:202:3: Warning: Assigning value of type 'void Function()?' to a variable of type 'Function'.
-//  - 'Function' is from 'dart:core'.
+// pkg/front_end/testcases/nnbd/assignability.dart:202:17: Warning: Tearing off method 'call' from a potentially null value.
 //   functionVar = tearoffableNullableArg;
-//   ^
+//                 ^
 //
 // pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
 //  - 'Function' is from 'dart:core'.
@@ -476,9 +475,9 @@
 //   toVoidVar = toVoidNullableArg;
 //   ^
 //
-// pkg/front_end/testcases/nnbd/assignability.dart:223:3: Warning: Assigning value of type 'void Function()?' to a variable of type 'void Function()'.
+// pkg/front_end/testcases/nnbd/assignability.dart:223:15: Warning: Tearing off method 'call' from a potentially null value.
 //   toVoidVar = tearoffableNullableArg;
-//   ^
+//               ^
 //
 // pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
 //   toVoidVar = xNonNullArg;
@@ -1004,32 +1003,32 @@
   objectVar = tearoffableArg;
   objectVar = xNonNullArg;
   objectVar = yNonNullArg;
-  core::num numVar = dynamicArg as{TypeError} core::num;
+  core::num numVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::num;
   numVar = numArg;
   numVar = intArg;
   numVar = doubleArg;
-  core::int intVar = dynamicArg as{TypeError} core::int;
+  core::int intVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
   intVar = intArg;
-  core::double doubleVar = dynamicArg as{TypeError} core::double;
+  core::double doubleVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::double;
   doubleVar = doubleArg;
-  core::Function functionVar = dynamicArg as{TypeError} core::Function;
+  core::Function functionVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} core::Function;
   functionVar = functionArg;
   functionVar = toVoidArg;
   functionVar = let final self::Tearoffable #t1 = tearoffableArg in #t1.==(null) ?{() → void} null : #t1.{self::Tearoffable::call};
-  () → void toVoidVar = dynamicArg as{TypeError} () → void;
+  () → void toVoidVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} () → void;
   toVoidVar = toVoidArg;
   toVoidVar = let final self::Tearoffable #t2 = tearoffableArg in #t2.==(null) ?{() → void} null : #t2.{self::Tearoffable::call};
-  self::Tearoffable tearoffableVar = dynamicArg as{TypeError} self::Tearoffable;
+  self::Tearoffable tearoffableVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::Tearoffable;
   tearoffableVar = tearoffableArg;
-  self::ok::XnonNull xNonNullVar = dynamicArg as{TypeError} self::ok::XnonNull;
+  self::ok::XnonNull xNonNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::XnonNull;
   xNonNullVar = xNonNullArg;
   xNonNullVar = yNonNullArg;
-  self::ok::YnonNull yNonNullVar = dynamicArg as{TypeError} self::ok::YnonNull;
+  self::ok::YnonNull yNonNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::YnonNull;
   yNonNullVar = yNonNullArg;
-  self::ok::XpotentiallyNull% xPotentiallyNullVar = dynamicArg as{TypeError} self::ok::XpotentiallyNull%;
+  self::ok::XpotentiallyNull% xPotentiallyNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::XpotentiallyNull%;
   xPotentiallyNullVar = xPotentiallyNullArg;
   xPotentiallyNullVar = yPotentiallyNullArg;
-  self::ok::YpotentiallyNull% yPotentiallyNullVar = dynamicArg as{TypeError} self::ok::YpotentiallyNull%;
+  self::ok::YpotentiallyNull% yPotentiallyNullVar = dynamicArg as{TypeError,ForDynamic,ForNonNullableByDefault} self::ok::YpotentiallyNull%;
   yPotentiallyNullVar = yPotentiallyNullArg;
 }
 static method error<XnonNull extends core::Object = core::Object, YnonNull extends self::error::XnonNull = core::Object, XpotentiallyNull extends core::Object? = core::Object?, YpotentiallyNull extends self::error::XpotentiallyNull% = core::Object?>(core::Object objectArg, core::Object? objectNullableArg, core::num numArg, core::num? numNullableArg, core::int intArg, core::int? intNullableArg, core::double doubleArg, core::double? doubleNullableArg, core::Function functionArg, core::Function? functionNullableArg, () → void toVoidArg, () →? void toVoidNullableArg, self::Tearoffable tearoffableArg, self::Tearoffable? tearoffableNullableArg, self::error::XnonNull xNonNullArg, self::error::XnonNull? xNonNullNullableArg, self::error::XpotentiallyNull% xPotentiallyNullArg, self::error::XpotentiallyNull? xPotentiallyNullNullableArg, self::error::YnonNull yNonNullArg, self::error::YnonNull? yNonNullNullableArg, self::error::YpotentiallyNull% yPotentiallyNullArg, self::error::YpotentiallyNull? yPotentiallyNullNullableArg) → dynamic {
@@ -1046,582 +1045,582 @@
   objectVar = yNonNullNullableArg;
   objectVar = yPotentiallyNullArg;
   objectVar = yPotentiallyNullNullableArg;
-  core::num numVar = objectArg as{TypeError} core::num;
-  numVar = objectNullableArg as{TypeError} core::num;
+  core::num numVar = objectArg as{TypeError,ForNonNullableByDefault} core::num;
+  numVar = objectNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = numNullableArg;
   numVar = intNullableArg;
   numVar = doubleNullableArg;
   numVar = let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:133:12: Error: A value of type 'Function' can't be assigned to a variable of type 'num'.
  - 'Function' is from 'dart:core'.
   numVar = functionArg;
-           ^" in functionArg as{TypeError} core::num;
+           ^" in functionArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:134:12: Error: A value of type 'Function?' can't be assigned to a variable of type 'num'.
  - 'Function' is from 'dart:core'.
   numVar = functionNullableArg;
-           ^" in functionNullableArg as{TypeError} core::num;
+           ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:135:12: Error: A value of type 'void Function()' can't be assigned to a variable of type 'num'.
   numVar = toVoidArg;
-           ^" in toVoidArg as{TypeError} core::num;
+           ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:136:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'num'.
   numVar = toVoidNullableArg;
-           ^" in toVoidNullableArg as{TypeError} core::num;
+           ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:137:12: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'num'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   numVar = tearoffableArg;
-           ^" in tearoffableArg as{TypeError} core::num;
+           ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:138:12: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'num'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   numVar = tearoffableNullableArg;
-           ^" in tearoffableNullableArg as{TypeError} core::num;
+           ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:139:12: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'num'.
   numVar = xNonNullArg;
-           ^" in xNonNullArg as{TypeError} core::num;
+           ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:140:12: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'num'.
   numVar = xNonNullNullableArg;
-           ^" in xNonNullNullableArg as{TypeError} core::num;
+           ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:141:12: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'num'.
   numVar = xPotentiallyNullArg;
-           ^" in xPotentiallyNullArg as{TypeError} core::num;
+           ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:142:12: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'num'.
   numVar = xPotentiallyNullNullableArg;
-           ^" in xPotentiallyNullNullableArg as{TypeError} core::num;
+           ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t13 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:143:12: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'num'.
   numVar = yNonNullArg;
-           ^" in yNonNullArg as{TypeError} core::num;
+           ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t14 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:144:12: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'num'.
   numVar = yNonNullNullableArg;
-           ^" in yNonNullNullableArg as{TypeError} core::num;
+           ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t15 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:145:12: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'num'.
   numVar = yPotentiallyNullArg;
-           ^" in yPotentiallyNullArg as{TypeError} core::num;
+           ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::num;
   numVar = let final<BottomType> #t16 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:146:12: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'num'.
   numVar = yPotentiallyNullNullableArg;
-           ^" in yPotentiallyNullNullableArg as{TypeError} core::num;
-  core::int intVar = objectArg as{TypeError} core::int;
-  intVar = objectNullableArg as{TypeError} core::int;
-  intVar = numArg as{TypeError} core::int;
-  intVar = numNullableArg as{TypeError} core::int;
+           ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::num;
+  core::int intVar = objectArg as{TypeError,ForNonNullableByDefault} core::int;
+  intVar = objectNullableArg as{TypeError,ForNonNullableByDefault} core::int;
+  intVar = numArg as{TypeError,ForNonNullableByDefault} core::int;
+  intVar = numNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = intNullableArg;
   intVar = let final<BottomType> #t17 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:153:12: Error: A value of type 'double' can't be assigned to a variable of type 'int'.
   intVar = doubleArg;
-           ^" in doubleArg as{TypeError} core::int;
+           ^" in doubleArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t18 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:154:12: Error: A value of type 'double?' can't be assigned to a variable of type 'int'.
   intVar = doubleNullableArg;
-           ^" in doubleNullableArg as{TypeError} core::int;
+           ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t19 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:155:12: Error: A value of type 'Function' can't be assigned to a variable of type 'int'.
  - 'Function' is from 'dart:core'.
   intVar = functionArg;
-           ^" in functionArg as{TypeError} core::int;
+           ^" in functionArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t20 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:156:12: Error: A value of type 'Function?' can't be assigned to a variable of type 'int'.
  - 'Function' is from 'dart:core'.
   intVar = functionNullableArg;
-           ^" in functionNullableArg as{TypeError} core::int;
+           ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t21 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:157:12: Error: A value of type 'void Function()' can't be assigned to a variable of type 'int'.
   intVar = toVoidArg;
-           ^" in toVoidArg as{TypeError} core::int;
+           ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t22 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:158:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'int'.
   intVar = toVoidNullableArg;
-           ^" in toVoidNullableArg as{TypeError} core::int;
+           ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t23 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:159:12: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'int'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   intVar = tearoffableArg;
-           ^" in tearoffableArg as{TypeError} core::int;
+           ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t24 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:160:12: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'int'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   intVar = tearoffableNullableArg;
-           ^" in tearoffableNullableArg as{TypeError} core::int;
+           ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t25 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:161:12: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'int'.
   intVar = xNonNullArg;
-           ^" in xNonNullArg as{TypeError} core::int;
+           ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t26 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:162:12: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'int'.
   intVar = xNonNullNullableArg;
-           ^" in xNonNullNullableArg as{TypeError} core::int;
+           ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t27 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:163:12: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'int'.
   intVar = xPotentiallyNullArg;
-           ^" in xPotentiallyNullArg as{TypeError} core::int;
+           ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t28 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:164:12: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'int'.
   intVar = xPotentiallyNullNullableArg;
-           ^" in xPotentiallyNullNullableArg as{TypeError} core::int;
+           ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t29 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:165:12: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'int'.
   intVar = yNonNullArg;
-           ^" in yNonNullArg as{TypeError} core::int;
+           ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t30 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:166:12: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'int'.
   intVar = yNonNullNullableArg;
-           ^" in yNonNullNullableArg as{TypeError} core::int;
+           ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t31 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:167:12: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'int'.
   intVar = yPotentiallyNullArg;
-           ^" in yPotentiallyNullArg as{TypeError} core::int;
+           ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::int;
   intVar = let final<BottomType> #t32 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:168:12: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'int'.
   intVar = yPotentiallyNullNullableArg;
-           ^" in yPotentiallyNullNullableArg as{TypeError} core::int;
-  core::double doubleVar = objectArg as{TypeError} core::double;
-  doubleVar = objectNullableArg as{TypeError} core::double;
-  doubleVar = numArg as{TypeError} core::double;
-  doubleVar = numNullableArg as{TypeError} core::double;
+           ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::int;
+  core::double doubleVar = objectArg as{TypeError,ForNonNullableByDefault} core::double;
+  doubleVar = objectNullableArg as{TypeError,ForNonNullableByDefault} core::double;
+  doubleVar = numArg as{TypeError,ForNonNullableByDefault} core::double;
+  doubleVar = numNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t33 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:174:15: Error: A value of type 'int' can't be assigned to a variable of type 'double'.
   doubleVar = intArg;
-              ^" in intArg as{TypeError} core::double;
+              ^" in intArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t34 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:175:15: Error: A value of type 'int?' can't be assigned to a variable of type 'double'.
   doubleVar = intNullableArg;
-              ^" in intNullableArg as{TypeError} core::double;
+              ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = doubleNullableArg;
   doubleVar = let final<BottomType> #t35 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:177:15: Error: A value of type 'Function' can't be assigned to a variable of type 'double'.
  - 'Function' is from 'dart:core'.
   doubleVar = functionArg;
-              ^" in functionArg as{TypeError} core::double;
+              ^" in functionArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t36 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:178:15: Error: A value of type 'Function?' can't be assigned to a variable of type 'double'.
  - 'Function' is from 'dart:core'.
   doubleVar = functionNullableArg;
-              ^" in functionNullableArg as{TypeError} core::double;
+              ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t37 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:179:15: Error: A value of type 'void Function()' can't be assigned to a variable of type 'double'.
   doubleVar = toVoidArg;
-              ^" in toVoidArg as{TypeError} core::double;
+              ^" in toVoidArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t38 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:180:15: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'double'.
   doubleVar = toVoidNullableArg;
-              ^" in toVoidNullableArg as{TypeError} core::double;
+              ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t39 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:181:15: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'double'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   doubleVar = tearoffableArg;
-              ^" in tearoffableArg as{TypeError} core::double;
+              ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t40 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:182:15: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'double'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   doubleVar = tearoffableNullableArg;
-              ^" in tearoffableNullableArg as{TypeError} core::double;
+              ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t41 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:183:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'double'.
   doubleVar = xNonNullArg;
-              ^" in xNonNullArg as{TypeError} core::double;
+              ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t42 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:184:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'double'.
   doubleVar = xNonNullNullableArg;
-              ^" in xNonNullNullableArg as{TypeError} core::double;
+              ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t43 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:185:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'double'.
   doubleVar = xPotentiallyNullArg;
-              ^" in xPotentiallyNullArg as{TypeError} core::double;
+              ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t44 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:186:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'double'.
   doubleVar = xPotentiallyNullNullableArg;
-              ^" in xPotentiallyNullNullableArg as{TypeError} core::double;
+              ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t45 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:187:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'double'.
   doubleVar = yNonNullArg;
-              ^" in yNonNullArg as{TypeError} core::double;
+              ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t46 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:188:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'double'.
   doubleVar = yNonNullNullableArg;
-              ^" in yNonNullNullableArg as{TypeError} core::double;
+              ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t47 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:189:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'double'.
   doubleVar = yPotentiallyNullArg;
-              ^" in yPotentiallyNullArg as{TypeError} core::double;
+              ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::double;
   doubleVar = let final<BottomType> #t48 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:190:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'double'.
   doubleVar = yPotentiallyNullNullableArg;
-              ^" in yPotentiallyNullNullableArg as{TypeError} core::double;
-  core::Function functionVar = objectArg as{TypeError} core::Function;
-  functionVar = objectNullableArg as{TypeError} core::Function;
+              ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::double;
+  core::Function functionVar = objectArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = objectNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t49 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:194:17: Error: A value of type 'num' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = numArg;
-                ^" in numArg as{TypeError} core::Function;
+                ^" in numArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t50 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:195:17: Error: A value of type 'num?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} core::Function;
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t51 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:196:17: Error: A value of type 'int' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = intArg;
-                ^" in intArg as{TypeError} core::Function;
+                ^" in intArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t52 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:197:17: Error: A value of type 'int?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} core::Function;
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t53 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:198:17: Error: A value of type 'double' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = doubleArg;
-                ^" in doubleArg as{TypeError} core::Function;
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = let final<BottomType> #t54 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:199:17: Error: A value of type 'double?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} core::Function;
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
   functionVar = functionNullableArg;
   functionVar = toVoidNullableArg;
-  functionVar = let final self::Tearoffable? #t55 = tearoffableNullableArg in #t55.==(null) ?{() →? void} null : #t55.{self::Tearoffable::call};
-  functionVar = let final<BottomType> #t56 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
+  functionVar = tearoffableNullableArg as{TypeError} core::Function;
+  functionVar = let final<BottomType> #t55 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:203:17: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xNonNullArg;
-                ^" in xNonNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t57 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:204:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Function'.
+                ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t56 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:204:17: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xNonNullNullableArg;
-                ^" in xNonNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t58 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:205:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Function'.
+                ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t57 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:205:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t59 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:206:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Function'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t58 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:206:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t60 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:207:17: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Function'.
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t59 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:207:17: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yNonNullArg;
-                ^" in yNonNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t61 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:208:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Function'.
+                ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t60 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:208:17: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yNonNullNullableArg;
-                ^" in yNonNullNullableArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t62 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:209:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Function'.
+                ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t61 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:209:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} core::Function;
-  functionVar = let final<BottomType> #t63 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:210:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Function'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} core::Function;
+  functionVar = let final<BottomType> #t62 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:210:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Function'.
  - 'Function' is from 'dart:core'.
   functionVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} core::Function;
-  () → void toVoidVar = objectArg as{TypeError} () → void;
-  toVoidVar = objectNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t64 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:214:15: Error: A value of type 'num' can't be assigned to a variable of type 'void Function()'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} core::Function;
+  () → void toVoidVar = objectArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = objectNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t63 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:214:15: Error: A value of type 'num' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = numArg;
-              ^" in numArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t65 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:215:15: Error: A value of type 'num?' can't be assigned to a variable of type 'void Function()'.
+              ^" in numArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t64 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:215:15: Error: A value of type 'num?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = numNullableArg;
-              ^" in numNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t66 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:216:15: Error: A value of type 'int' can't be assigned to a variable of type 'void Function()'.
+              ^" in numNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t65 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:216:15: Error: A value of type 'int' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = intArg;
-              ^" in intArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t67 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:217:15: Error: A value of type 'int?' can't be assigned to a variable of type 'void Function()'.
+              ^" in intArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t66 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:217:15: Error: A value of type 'int?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = intNullableArg;
-              ^" in intNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t68 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:218:15: Error: A value of type 'double' can't be assigned to a variable of type 'void Function()'.
+              ^" in intNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t67 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:218:15: Error: A value of type 'double' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = doubleArg;
-              ^" in doubleArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t69 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:219:15: Error: A value of type 'double?' can't be assigned to a variable of type 'void Function()'.
+              ^" in doubleArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t68 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:219:15: Error: A value of type 'double?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = doubleNullableArg;
-              ^" in doubleNullableArg as{TypeError} () → void;
-  toVoidVar = functionArg as{TypeError} () → void;
-  toVoidVar = functionNullableArg as{TypeError} () → void;
+              ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = functionArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = functionNullableArg as{TypeError,ForNonNullableByDefault} () → void;
   toVoidVar = toVoidNullableArg;
-  toVoidVar = let final self::Tearoffable? #t70 = tearoffableNullableArg in #t70.==(null) ?{() →? void} null : #t70.{self::Tearoffable::call};
-  toVoidVar = let final<BottomType> #t71 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
+  toVoidVar = tearoffableNullableArg as{TypeError} () → void;
+  toVoidVar = let final<BottomType> #t69 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:224:15: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xNonNullArg;
-              ^" in xNonNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t72 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:225:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t70 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:225:15: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xNonNullNullableArg;
-              ^" in xNonNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t73 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:226:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t71 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:226:15: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xPotentiallyNullArg;
-              ^" in xPotentiallyNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t74 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:227:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t72 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:227:15: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = xPotentiallyNullNullableArg;
-              ^" in xPotentiallyNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t75 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:228:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t73 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:228:15: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yNonNullArg;
-              ^" in yNonNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t76 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:229:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t74 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:229:15: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yNonNullNullableArg;
-              ^" in yNonNullNullableArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t77 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:230:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
+              ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t75 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:230:15: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yPotentiallyNullArg;
-              ^" in yPotentiallyNullArg as{TypeError} () → void;
-  toVoidVar = let final<BottomType> #t78 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:231:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
+              ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} () → void;
+  toVoidVar = let final<BottomType> #t76 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:231:15: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'void Function()'.
   toVoidVar = yPotentiallyNullNullableArg;
-              ^" in yPotentiallyNullNullableArg as{TypeError} () → void;
-  self::Tearoffable tearoffableVar = objectArg as{TypeError} self::Tearoffable;
-  tearoffableVar = objectNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t79 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:235:20: Error: A value of type 'num' can't be assigned to a variable of type 'Tearoffable'.
+              ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} () → void;
+  self::Tearoffable tearoffableVar = objectArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = objectNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t77 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:235:20: Error: A value of type 'num' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = numArg;
-                   ^" in numArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t80 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:236:20: Error: A value of type 'num?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in numArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t78 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:236:20: Error: A value of type 'num?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = numNullableArg;
-                   ^" in numNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t81 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:237:20: Error: A value of type 'int' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in numNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t79 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:237:20: Error: A value of type 'int' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = intArg;
-                   ^" in intArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t82 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:238:20: Error: A value of type 'int?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in intArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t80 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:238:20: Error: A value of type 'int?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = intNullableArg;
-                   ^" in intNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t83 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:239:20: Error: A value of type 'double' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in intNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t81 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:239:20: Error: A value of type 'double' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = doubleArg;
-                   ^" in doubleArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t84 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:240:20: Error: A value of type 'double?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in doubleArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t82 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:240:20: Error: A value of type 'double?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = doubleNullableArg;
-                   ^" in doubleNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t85 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:241:20: Error: A value of type 'Function' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t83 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:241:20: Error: A value of type 'Function' can't be assigned to a variable of type 'Tearoffable'.
  - 'Function' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = functionArg;
-                   ^" in functionArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t86 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:242:20: Error: A value of type 'Function?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in functionArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t84 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:242:20: Error: A value of type 'Function?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Function' is from 'dart:core'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = functionNullableArg;
-                   ^" in functionNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t87 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:243:20: Error: A value of type 'void Function()' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t85 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:243:20: Error: A value of type 'void Function()' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = toVoidArg;
-                   ^" in toVoidArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t88 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:244:20: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in toVoidArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t86 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:244:20: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = toVoidNullableArg;
-                   ^" in toVoidNullableArg as{TypeError} self::Tearoffable;
+                   ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
   tearoffableVar = tearoffableNullableArg;
-  tearoffableVar = let final<BottomType> #t89 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:246:20: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Tearoffable'.
+  tearoffableVar = let final<BottomType> #t87 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:246:20: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xNonNullArg;
-                   ^" in xNonNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t90 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:247:20: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t88 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:247:20: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xNonNullNullableArg;
-                   ^" in xNonNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t91 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:248:20: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t89 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:248:20: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xPotentiallyNullArg;
-                   ^" in xPotentiallyNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t92 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:249:20: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t90 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:249:20: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = xPotentiallyNullNullableArg;
-                   ^" in xPotentiallyNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t93 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:250:20: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t91 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:250:20: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yNonNullArg;
-                   ^" in yNonNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t94 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:251:20: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t92 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:251:20: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yNonNullNullableArg;
-                   ^" in yNonNullNullableArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t95 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:252:20: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t93 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:252:20: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yPotentiallyNullArg;
-                   ^" in yPotentiallyNullArg as{TypeError} self::Tearoffable;
-  tearoffableVar = let final<BottomType> #t96 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:253:20: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
+                   ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  tearoffableVar = let final<BottomType> #t94 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:253:20: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'Tearoffable'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   tearoffableVar = yPotentiallyNullNullableArg;
-                   ^" in yPotentiallyNullNullableArg as{TypeError} self::Tearoffable;
-  self::error::XnonNull xNonNullVar = objectArg as{TypeError} self::error::XnonNull;
-  xNonNullVar = objectNullableArg as{TypeError} self::error::XnonNull;
-  xNonNullVar = let final<BottomType> #t97 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:257:17: Error: A value of type 'num' can't be assigned to a variable of type 'XnonNull'.
+                   ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} self::Tearoffable;
+  self::error::XnonNull xNonNullVar = objectArg as{TypeError,ForNonNullableByDefault} self::error::XnonNull;
+  xNonNullVar = objectNullableArg as{TypeError,ForNonNullableByDefault} self::error::XnonNull;
+  xNonNullVar = let final<BottomType> #t95 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:257:17: Error: A value of type 'num' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = numArg;
-                ^" in numArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t98 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:258:17: Error: A value of type 'num?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t96 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:258:17: Error: A value of type 'num?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t99 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:259:17: Error: A value of type 'int' can't be assigned to a variable of type 'XnonNull'.
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t97 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:259:17: Error: A value of type 'int' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = intArg;
-                ^" in intArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t100 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:260:17: Error: A value of type 'int?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t98 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:260:17: Error: A value of type 'int?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t101 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:261:17: Error: A value of type 'double' can't be assigned to a variable of type 'XnonNull'.
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t99 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:261:17: Error: A value of type 'double' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = doubleArg;
-                ^" in doubleArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t102 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:262:17: Error: A value of type 'double?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t100 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:262:17: Error: A value of type 'double?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t103 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:263:17: Error: A value of type 'Function' can't be assigned to a variable of type 'XnonNull'.
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t101 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:263:17: Error: A value of type 'Function' can't be assigned to a variable of type 'XnonNull'.
  - 'Function' is from 'dart:core'.
   xNonNullVar = functionArg;
-                ^" in functionArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t104 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:264:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t102 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:264:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'XnonNull'.
  - 'Function' is from 'dart:core'.
   xNonNullVar = functionNullableArg;
-                ^" in functionNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t105 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:265:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XnonNull'.
+                ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t103 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:265:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = toVoidArg;
-                ^" in toVoidArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t106 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:266:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t104 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:266:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = toVoidNullableArg;
-                ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t107 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:267:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XnonNull'.
+                ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t105 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:267:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xNonNullVar = tearoffableArg;
-                ^" in tearoffableArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t108 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:268:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t106 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:268:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xNonNullVar = tearoffableNullableArg;
-                ^" in tearoffableNullableArg as{TypeError} <BottomType>;
+                ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   xNonNullVar = xNonNullNullableArg;
-  xNonNullVar = let final<BottomType> #t109 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:270:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
+  xNonNullVar = let final<BottomType> #t107 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:270:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t110 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:271:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t108 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:271:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   xNonNullVar = yNonNullNullableArg;
-  xNonNullVar = let final<BottomType> #t111 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:273:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
+  xNonNullVar = let final<BottomType> #t109 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:273:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} <BottomType>;
-  xNonNullVar = let final<BottomType> #t112 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:274:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xNonNullVar = let final<BottomType> #t110 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:274:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'XnonNull'.
   xNonNullVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  self::error::XpotentiallyNull% xPotentiallyNullVar = objectArg as{TypeError} self::error::XpotentiallyNull%;
-  xPotentiallyNullVar = objectNullableArg as{TypeError} self::error::XpotentiallyNull%;
-  xPotentiallyNullVar = let final<BottomType> #t113 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:278:25: Error: A value of type 'num' can't be assigned to a variable of type 'XpotentiallyNull'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  self::error::XpotentiallyNull% xPotentiallyNullVar = objectArg as{TypeError,ForNonNullableByDefault} self::error::XpotentiallyNull%;
+  xPotentiallyNullVar = objectNullableArg as{TypeError,ForNonNullableByDefault} self::error::XpotentiallyNull%;
+  xPotentiallyNullVar = let final<BottomType> #t111 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:278:25: Error: A value of type 'num' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = numArg;
-                        ^" in numArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t114 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:279:25: Error: A value of type 'num?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t112 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:279:25: Error: A value of type 'num?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = numNullableArg;
-                        ^" in numNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t115 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:280:25: Error: A value of type 'int' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t113 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:280:25: Error: A value of type 'int' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = intArg;
-                        ^" in intArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t116 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:281:25: Error: A value of type 'int?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t114 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:281:25: Error: A value of type 'int?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = intNullableArg;
-                        ^" in intNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t117 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:282:25: Error: A value of type 'double' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t115 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:282:25: Error: A value of type 'double' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = doubleArg;
-                        ^" in doubleArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t118 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:283:25: Error: A value of type 'double?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t116 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:283:25: Error: A value of type 'double?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = doubleNullableArg;
-                        ^" in doubleNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t119 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:284:25: Error: A value of type 'Function' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t117 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:284:25: Error: A value of type 'Function' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   xPotentiallyNullVar = functionArg;
-                        ^" in functionArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t120 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:285:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t118 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:285:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   xPotentiallyNullVar = functionNullableArg;
-                        ^" in functionNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t121 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:286:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t119 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:286:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = toVoidArg;
-                        ^" in toVoidArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t122 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:287:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t120 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:287:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = toVoidNullableArg;
-                        ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t123 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:288:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t121 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:288:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xPotentiallyNullVar = tearoffableArg;
-                        ^" in tearoffableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t124 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:289:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t122 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:289:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'XpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   xPotentiallyNullVar = tearoffableNullableArg;
-                        ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t125 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:290:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t123 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:290:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = xNonNullArg;
-                        ^" in xNonNullArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t126 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:291:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t124 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:291:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = xNonNullNullableArg;
-                        ^" in xNonNullNullableArg as{TypeError} <BottomType>;
+                        ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   xPotentiallyNullVar = xPotentiallyNullNullableArg;
-  xPotentiallyNullVar = let final<BottomType> #t127 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:293:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
+  xPotentiallyNullVar = let final<BottomType> #t125 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:293:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = yNonNullArg;
-                        ^" in yNonNullArg as{TypeError} <BottomType>;
-  xPotentiallyNullVar = let final<BottomType> #t128 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:294:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
+                        ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  xPotentiallyNullVar = let final<BottomType> #t126 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:294:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'XpotentiallyNull'.
   xPotentiallyNullVar = yNonNullNullableArg;
-                        ^" in yNonNullNullableArg as{TypeError} <BottomType>;
+                        ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   xPotentiallyNullVar = yPotentiallyNullNullableArg;
-  self::error::YnonNull yNonNullVar = objectArg as{TypeError} self::error::YnonNull;
-  yNonNullVar = objectNullableArg as{TypeError} self::error::YnonNull;
-  yNonNullVar = let final<BottomType> #t129 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:299:17: Error: A value of type 'num' can't be assigned to a variable of type 'YnonNull'.
+  self::error::YnonNull yNonNullVar = objectArg as{TypeError,ForNonNullableByDefault} self::error::YnonNull;
+  yNonNullVar = objectNullableArg as{TypeError,ForNonNullableByDefault} self::error::YnonNull;
+  yNonNullVar = let final<BottomType> #t127 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:299:17: Error: A value of type 'num' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = numArg;
-                ^" in numArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t130 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:300:17: Error: A value of type 'num?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t128 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:300:17: Error: A value of type 'num?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = numNullableArg;
-                ^" in numNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t131 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:301:17: Error: A value of type 'int' can't be assigned to a variable of type 'YnonNull'.
+                ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t129 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:301:17: Error: A value of type 'int' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = intArg;
-                ^" in intArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t132 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:302:17: Error: A value of type 'int?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t130 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:302:17: Error: A value of type 'int?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = intNullableArg;
-                ^" in intNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t133 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:303:17: Error: A value of type 'double' can't be assigned to a variable of type 'YnonNull'.
+                ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t131 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:303:17: Error: A value of type 'double' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = doubleArg;
-                ^" in doubleArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t134 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:304:17: Error: A value of type 'double?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t132 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:304:17: Error: A value of type 'double?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = doubleNullableArg;
-                ^" in doubleNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t135 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:305:17: Error: A value of type 'Function' can't be assigned to a variable of type 'YnonNull'.
+                ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t133 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:305:17: Error: A value of type 'Function' can't be assigned to a variable of type 'YnonNull'.
  - 'Function' is from 'dart:core'.
   yNonNullVar = functionArg;
-                ^" in functionArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t136 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:306:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t134 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:306:17: Error: A value of type 'Function?' can't be assigned to a variable of type 'YnonNull'.
  - 'Function' is from 'dart:core'.
   yNonNullVar = functionNullableArg;
-                ^" in functionNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t137 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:307:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YnonNull'.
+                ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t135 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:307:17: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = toVoidArg;
-                ^" in toVoidArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t138 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:308:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t136 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:308:17: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = toVoidNullableArg;
-                ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t139 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:309:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YnonNull'.
+                ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t137 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:309:17: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yNonNullVar = tearoffableArg;
-                ^" in tearoffableArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t140 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:310:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t138 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:310:17: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YnonNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yNonNullVar = tearoffableNullableArg;
-                ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  yNonNullVar = xNonNullArg as{TypeError} self::error::YnonNull;
-  yNonNullVar = xNonNullNullableArg as{TypeError} self::error::YnonNull;
-  yNonNullVar = let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:313:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
+                ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = xNonNullArg as{TypeError,ForNonNullableByDefault} self::error::YnonNull;
+  yNonNullVar = xNonNullNullableArg as{TypeError,ForNonNullableByDefault} self::error::YnonNull;
+  yNonNullVar = let final<BottomType> #t139 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:313:17: Error: A value of type 'XpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xPotentiallyNullArg;
-                ^" in xPotentiallyNullArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t142 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:314:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t140 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:314:17: Error: A value of type 'XpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = xPotentiallyNullNullableArg;
-                ^" in xPotentiallyNullNullableArg as{TypeError} <BottomType>;
+                ^" in xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   yNonNullVar = yNonNullNullableArg;
-  yNonNullVar = let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:316:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
+  yNonNullVar = let final<BottomType> #t141 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:316:17: Error: A value of type 'YpotentiallyNull' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = yPotentiallyNullArg;
-                ^" in yPotentiallyNullArg as{TypeError} <BottomType>;
-  yNonNullVar = let final<BottomType> #t144 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:317:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
+                ^" in yPotentiallyNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yNonNullVar = let final<BottomType> #t142 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:317:17: Error: A value of type 'YpotentiallyNull?' can't be assigned to a variable of type 'YnonNull'.
   yNonNullVar = yPotentiallyNullNullableArg;
-                ^" in yPotentiallyNullNullableArg as{TypeError} <BottomType>;
-  self::error::YpotentiallyNull% yPotentiallyNullVar = objectArg as{TypeError} self::error::YpotentiallyNull%;
-  yPotentiallyNullVar = objectNullableArg as{TypeError} self::error::YpotentiallyNull%;
-  yPotentiallyNullVar = let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:321:25: Error: A value of type 'num' can't be assigned to a variable of type 'YpotentiallyNull'.
+                ^" in yPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  self::error::YpotentiallyNull% yPotentiallyNullVar = objectArg as{TypeError,ForNonNullableByDefault} self::error::YpotentiallyNull%;
+  yPotentiallyNullVar = objectNullableArg as{TypeError,ForNonNullableByDefault} self::error::YpotentiallyNull%;
+  yPotentiallyNullVar = let final<BottomType> #t143 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:321:25: Error: A value of type 'num' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = numArg;
-                        ^" in numArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t146 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:322:25: Error: A value of type 'num?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in numArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t144 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:322:25: Error: A value of type 'num?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = numNullableArg;
-                        ^" in numNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:323:25: Error: A value of type 'int' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in numNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t145 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:323:25: Error: A value of type 'int' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = intArg;
-                        ^" in intArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:324:25: Error: A value of type 'int?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in intArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t146 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:324:25: Error: A value of type 'int?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = intNullableArg;
-                        ^" in intNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t149 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:325:25: Error: A value of type 'double' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in intNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t147 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:325:25: Error: A value of type 'double' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = doubleArg;
-                        ^" in doubleArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:326:25: Error: A value of type 'double?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in doubleArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t148 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:326:25: Error: A value of type 'double?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = doubleNullableArg;
-                        ^" in doubleNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:327:25: Error: A value of type 'Function' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in doubleNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t149 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:327:25: Error: A value of type 'Function' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   yPotentiallyNullVar = functionArg;
-                        ^" in functionArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t152 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:328:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in functionArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t150 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:328:25: Error: A value of type 'Function?' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Function' is from 'dart:core'.
   yPotentiallyNullVar = functionNullableArg;
-                        ^" in functionNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:329:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in functionNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t151 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:329:25: Error: A value of type 'void Function()' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = toVoidArg;
-                        ^" in toVoidArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:330:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in toVoidArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t152 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:330:25: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = toVoidNullableArg;
-                        ^" in toVoidNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t155 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:331:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in toVoidNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t153 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:331:25: Error: A value of type 'Tearoffable' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yPotentiallyNullVar = tearoffableArg;
-                        ^" in tearoffableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t156 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:332:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in tearoffableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t154 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:332:25: Error: A value of type 'Tearoffable?' can't be assigned to a variable of type 'YpotentiallyNull'.
  - 'Tearoffable' is from 'pkg/front_end/testcases/nnbd/assignability.dart'.
   yPotentiallyNullVar = tearoffableNullableArg;
-                        ^" in tearoffableNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t157 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:333:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in tearoffableNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t155 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:333:25: Error: A value of type 'XnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xNonNullArg;
-                        ^" in xNonNullArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:334:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t156 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:334:25: Error: A value of type 'XnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = xNonNullNullableArg;
-                        ^" in xNonNullNullableArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = xPotentiallyNullArg as{TypeError} self::error::YpotentiallyNull%;
-  yPotentiallyNullVar = xPotentiallyNullNullableArg as{TypeError} self::error::YpotentiallyNull%;
-  yPotentiallyNullVar = let final<BottomType> #t159 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:337:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in xNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = xPotentiallyNullArg as{TypeError,ForNonNullableByDefault} self::error::YpotentiallyNull%;
+  yPotentiallyNullVar = xPotentiallyNullNullableArg as{TypeError,ForNonNullableByDefault} self::error::YpotentiallyNull%;
+  yPotentiallyNullVar = let final<BottomType> #t157 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:337:25: Error: A value of type 'YnonNull' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = yNonNullArg;
-                        ^" in yNonNullArg as{TypeError} <BottomType>;
-  yPotentiallyNullVar = let final<BottomType> #t160 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:338:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
+                        ^" in yNonNullArg as{TypeError,ForNonNullableByDefault} <BottomType>;
+  yPotentiallyNullVar = let final<BottomType> #t158 = invalid-expression "pkg/front_end/testcases/nnbd/assignability.dart:338:25: Error: A value of type 'YnonNull?' can't be assigned to a variable of type 'YpotentiallyNull'.
   yPotentiallyNullVar = yNonNullNullableArg;
-                        ^" in yNonNullNullableArg as{TypeError} <BottomType>;
+                        ^" in yNonNullNullableArg as{TypeError,ForNonNullableByDefault} <BottomType>;
   yPotentiallyNullVar = yPotentiallyNullNullableArg;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/forin.dart.strong.expect b/pkg/front_end/testcases/nnbd/forin.dart.strong.expect
index dc3ec6b..0f795fe 100644
--- a/pkg/front_end/testcases/nnbd/forin.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/forin.dart.strong.expect
@@ -55,21 +55,21 @@
   for (core::int x in let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/forin.dart:9:17: Error: The type 'Iterable<int>?' used in the 'for' loop must implement 'Iterable<dynamic>'.
  - 'Iterable' is from 'dart:core'.
   for (int x in i2) x;
-                ^" in i2 as{TypeError} core::Iterable<dynamic>)
+                ^" in i2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>)
     x;
   block {
     final core::List<core::int> #t2 = <core::int>[];
     for (core::int x in let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/forin.dart:10:18: Error: The type 'Iterable<int>?' used in the 'for' loop must implement 'Iterable<dynamic>'.
  - 'Iterable' is from 'dart:core'.
   [for (int x in i2) x];
-                 ^" in i2 as{TypeError} core::Iterable<dynamic>)
+                 ^" in i2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>)
       #t2.{core::List::add}(x);
   } =>#t2;
   for (core::int x in let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/forin.dart:12:17: Error: The type 'List<int>?' used in the 'for' loop must implement 'Iterable<dynamic>'.
  - 'List' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   for (int x in l2) x;
-                ^" in l2 as{TypeError} core::Iterable<dynamic>)
+                ^" in l2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>)
     x;
   block {
     final core::List<core::int> #t5 = <core::int>[];
@@ -77,15 +77,15 @@
  - 'List' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   [for (int x in l2) x];
-                 ^" in l2 as{TypeError} core::Iterable<dynamic>)
+                 ^" in l2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>)
       #t5.{core::List::add}(x);
   } =>#t5;
   for (final dynamic #t7 in let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/forin.dart:15:17: Error: The type 'Object' used in the 'for' loop must implement 'Iterable<dynamic>'.
  - 'Object' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   for (int x in o1) x;
-                ^" in o1 as{TypeError} core::Iterable<dynamic>) {
-    core::int x = #t7 as{TypeError} core::int;
+                ^" in o1 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>) {
+    core::int x = #t7 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
     x;
   }
   block {
@@ -94,8 +94,8 @@
  - 'Object' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   [for (int x in o1) x];
-                 ^" in o1 as{TypeError} core::Iterable<dynamic>) {
-      core::int x = #t10 as{TypeError} core::int;
+                 ^" in o1 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>) {
+      core::int x = #t10 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
       #t9.{core::List::add}(x);
     }
   } =>#t9;
@@ -103,8 +103,8 @@
  - 'Object' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   for (int x in o2) x;
-                ^" in o2 as{TypeError} core::Iterable<dynamic>) {
-    core::int x = #t12 as{TypeError} core::int;
+                ^" in o2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>) {
+    core::int x = #t12 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
     x;
   }
   block {
@@ -113,8 +113,8 @@
  - 'Object' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   [for (int x in o2) x];
-                 ^" in o2 as{TypeError} core::Iterable<dynamic>) {
-      core::int x = #t15 as{TypeError} core::int;
+                 ^" in o2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>) {
+      core::int x = #t15 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
       #t14.{core::List::add}(x);
     }
   } =>#t14;
@@ -134,14 +134,14 @@
     for (core::int x in l1)
       #t18.{core::List::add}(x);
   } =>#t18;
-  for (final dynamic #t19 in d as{TypeError} core::Iterable<dynamic>) {
-    core::int x = #t19 as{TypeError} core::int;
+  for (final dynamic #t19 in d as{TypeError,ForDynamic,ForNonNullableByDefault} core::Iterable<dynamic>) {
+    core::int x = #t19 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
     x;
   }
   block {
     final core::List<core::int> #t20 = <core::int>[];
-    for (final dynamic #t21 in d as{TypeError} core::Iterable<dynamic>) {
-      core::int x = #t21 as{TypeError} core::int;
+    for (final dynamic #t21 in d as{TypeError,ForDynamic,ForNonNullableByDefault} core::Iterable<dynamic>) {
+      core::int x = #t21 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
       #t20.{core::List::add}(x);
     }
   } =>#t20;
diff --git a/pkg/front_end/testcases/nnbd/forin.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/forin.dart.strong.transformed.expect
index 04b46d0..ac3b55d 100644
--- a/pkg/front_end/testcases/nnbd/forin.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/forin.dart.strong.transformed.expect
@@ -57,7 +57,7 @@
     core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/forin.dart:9:17: Error: The type 'Iterable<int>?' used in the 'for' loop must implement 'Iterable<dynamic>'.
  - 'Iterable' is from 'dart:core'.
   for (int x in i2) x;
-                ^" in i2 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+                ^" in i2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       core::int x = :sync-for-iterator.{core::Iterator::current};
       x;
@@ -69,7 +69,7 @@
       core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/forin.dart:10:18: Error: The type 'Iterable<int>?' used in the 'for' loop must implement 'Iterable<dynamic>'.
  - 'Iterable' is from 'dart:core'.
   [for (int x in i2) x];
-                 ^" in i2 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+                 ^" in i2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int x = :sync-for-iterator.{core::Iterator::current};
         #t2.{core::List::add}(x);
@@ -81,7 +81,7 @@
  - 'List' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   for (int x in l2) x;
-                ^" in l2 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+                ^" in l2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       core::int x = :sync-for-iterator.{core::Iterator::current};
       x;
@@ -94,7 +94,7 @@
  - 'List' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   [for (int x in l2) x];
-                 ^" in l2 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+                 ^" in l2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         core::int x = :sync-for-iterator.{core::Iterator::current};
         #t5.{core::List::add}(x);
@@ -106,11 +106,11 @@
  - 'Object' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   for (int x in o1) x;
-                ^" in o1 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+                ^" in o1 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t8 = :sync-for-iterator.{core::Iterator::current};
       {
-        core::int x = #t8 as{TypeError} core::int;
+        core::int x = #t8 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
         x;
       }
     }
@@ -122,11 +122,11 @@
  - 'Object' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   [for (int x in o1) x];
-                 ^" in o1 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+                 ^" in o1 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t11 = :sync-for-iterator.{core::Iterator::current};
         {
-          core::int x = #t11 as{TypeError} core::int;
+          core::int x = #t11 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
           #t9.{core::List::add}(x);
         }
       }
@@ -137,11 +137,11 @@
  - 'Object' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   for (int x in o2) x;
-                ^" in o2 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+                ^" in o2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t13 = :sync-for-iterator.{core::Iterator::current};
       {
-        core::int x = #t13 as{TypeError} core::int;
+        core::int x = #t13 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
         x;
       }
     }
@@ -153,11 +153,11 @@
  - 'Object' is from 'dart:core'.
  - 'Iterable' is from 'dart:core'.
   [for (int x in o2) x];
-                 ^" in o2 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+                 ^" in o2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t16 = :sync-for-iterator.{core::Iterator::current};
         {
-          core::int x = #t16 as{TypeError} core::int;
+          core::int x = #t16 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
           #t14.{core::List::add}(x);
         }
       }
@@ -200,11 +200,11 @@
     }
   } =>#t18;
   {
-    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(d as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(d as{TypeError,ForDynamic,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t19 = :sync-for-iterator.{core::Iterator::current};
       {
-        core::int x = #t19 as{TypeError} core::int;
+        core::int x = #t19 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
         x;
       }
     }
@@ -212,11 +212,11 @@
   block {
     final core::List<core::int> #t20 = <core::int>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(d as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(d as{TypeError,ForDynamic,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t21 = :sync-for-iterator.{core::Iterator::current};
         {
-          core::int x = #t21 as{TypeError} core::int;
+          core::int x = #t21 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
           #t20.{core::List::add}(x);
         }
       }
diff --git a/pkg/front_end/testcases/nnbd/forin.dart.weak.expect b/pkg/front_end/testcases/nnbd/forin.dart.weak.expect
index 12c0f2c..7a50a15 100644
--- a/pkg/front_end/testcases/nnbd/forin.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/forin.dart.weak.expect
@@ -66,25 +66,25 @@
     for (core::int x in l2)
       #t2.{core::List::add}(x);
   } =>#t2;
-  for (final dynamic #t3 in o1 as{TypeError} core::Iterable<dynamic>) {
-    core::int x = #t3 as{TypeError} core::int;
+  for (final dynamic #t3 in o1 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>) {
+    core::int x = #t3 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
     x;
   }
   block {
     final core::List<core::int> #t4 = <core::int>[];
-    for (final dynamic #t5 in o1 as{TypeError} core::Iterable<dynamic>) {
-      core::int x = #t5 as{TypeError} core::int;
+    for (final dynamic #t5 in o1 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>) {
+      core::int x = #t5 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
       #t4.{core::List::add}(x);
     }
   } =>#t4;
-  for (final dynamic #t6 in o2 as{TypeError} core::Iterable<dynamic>) {
-    core::int x = #t6 as{TypeError} core::int;
+  for (final dynamic #t6 in o2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>) {
+    core::int x = #t6 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
     x;
   }
   block {
     final core::List<core::int> #t7 = <core::int>[];
-    for (final dynamic #t8 in o2 as{TypeError} core::Iterable<dynamic>) {
-      core::int x = #t8 as{TypeError} core::int;
+    for (final dynamic #t8 in o2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>) {
+      core::int x = #t8 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
       #t7.{core::List::add}(x);
     }
   } =>#t7;
@@ -104,14 +104,14 @@
     for (core::int x in l1)
       #t10.{core::List::add}(x);
   } =>#t10;
-  for (final dynamic #t11 in d as{TypeError} core::Iterable<dynamic>) {
-    core::int x = #t11 as{TypeError} core::int;
+  for (final dynamic #t11 in d as{TypeError,ForDynamic,ForNonNullableByDefault} core::Iterable<dynamic>) {
+    core::int x = #t11 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
     x;
   }
   block {
     final core::List<core::int> #t12 = <core::int>[];
-    for (final dynamic #t13 in d as{TypeError} core::Iterable<dynamic>) {
-      core::int x = #t13 as{TypeError} core::int;
+    for (final dynamic #t13 in d as{TypeError,ForDynamic,ForNonNullableByDefault} core::Iterable<dynamic>) {
+      core::int x = #t13 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
       #t12.{core::List::add}(x);
     }
   } =>#t12;
diff --git a/pkg/front_end/testcases/nnbd/forin.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/forin.dart.weak.transformed.expect
index 1cf6aaf..39aa91b 100644
--- a/pkg/front_end/testcases/nnbd/forin.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/forin.dart.weak.transformed.expect
@@ -88,11 +88,11 @@
     }
   } =>#t2;
   {
-    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(o1 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(o1 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t3 = :sync-for-iterator.{core::Iterator::current};
       {
-        core::int x = #t3 as{TypeError} core::int;
+        core::int x = #t3 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
         x;
       }
     }
@@ -100,22 +100,22 @@
   block {
     final core::List<core::int> #t4 = <core::int>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(o1 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(o1 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t5 = :sync-for-iterator.{core::Iterator::current};
         {
-          core::int x = #t5 as{TypeError} core::int;
+          core::int x = #t5 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
           #t4.{core::List::add}(x);
         }
       }
     }
   } =>#t4;
   {
-    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(o2 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(o2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t6 = :sync-for-iterator.{core::Iterator::current};
       {
-        core::int x = #t6 as{TypeError} core::int;
+        core::int x = #t6 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
         x;
       }
     }
@@ -123,11 +123,11 @@
   block {
     final core::List<core::int> #t7 = <core::int>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(o2 as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(o2 as{TypeError,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t8 = :sync-for-iterator.{core::Iterator::current};
         {
-          core::int x = #t8 as{TypeError} core::int;
+          core::int x = #t8 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
           #t7.{core::List::add}(x);
         }
       }
@@ -170,11 +170,11 @@
     }
   } =>#t10;
   {
-    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(d as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(d as{TypeError,ForDynamic,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t11 = :sync-for-iterator.{core::Iterator::current};
       {
-        core::int x = #t11 as{TypeError} core::int;
+        core::int x = #t11 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
         x;
       }
     }
@@ -182,11 +182,11 @@
   block {
     final core::List<core::int> #t12 = <core::int>[];
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(d as{TypeError} core::Iterable<dynamic>).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(d as{TypeError,ForDynamic,ForNonNullableByDefault} core::Iterable<dynamic>).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t13 = :sync-for-iterator.{core::Iterator::current};
         {
-          core::int x = #t13 as{TypeError} core::int;
+          core::int x = #t13 as{TypeError,ForDynamic,ForNonNullableByDefault} core::int;
           #t12.{core::List::add}(x);
         }
       }
diff --git a/pkg/front_end/testcases/nnbd/intersection_types.dart.strong.expect b/pkg/front_end/testcases/nnbd/intersection_types.dart.strong.expect
index 7facb01..977e568 100644
--- a/pkg/front_end/testcases/nnbd/intersection_types.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/intersection_types.dart.strong.expect
@@ -22,18 +22,18 @@
     : super core::Object::•()
     ;
   method doPromotionsToNullable(generic-covariant-impl self::Foo::T% t) → dynamic {
-    if(t is self::B?) {
-      self::Foo::T% & self::B? /* '%' & '?' = '%' */ bar = t{self::Foo::T% & self::B? /* '%' & '?' = '%' */};
-      if(t{self::Foo::T% & self::B? /* '%' & '?' = '%' */} is self::C?) {
-        self::Foo::T% & self::C? /* '%' & '?' = '%' */ baz = t{self::Foo::T% & self::C? /* '%' & '?' = '%' */};
+    if(t is{ForNonNullableByDefault} self::B?) {
+      self::Foo::T% bar = t{self::Foo::T% & self::B? /* '%' & '?' = '%' */};
+      if(t{self::Foo::T% & self::B? /* '%' & '?' = '%' */} is{ForNonNullableByDefault} self::C?) {
+        self::Foo::T% baz = t{self::Foo::T% & self::C? /* '%' & '?' = '%' */};
       }
     }
   }
   method doPromotionsToNonNullable(generic-covariant-impl self::Foo::T% t) → dynamic {
-    if(t is self::B) {
-      self::Foo::T% & self::B /* '%' & '!' = '!' */ bar = t{self::Foo::T% & self::B /* '%' & '!' = '!' */};
-      if(t{self::Foo::T% & self::B /* '%' & '!' = '!' */} is self::C) {
-        self::Foo::T & self::C /* '!' & '!' = '!' */ baz = t{self::Foo::T & self::C /* '!' & '!' = '!' */};
+    if(t is{ForNonNullableByDefault} self::B) {
+      self::Foo::T% bar = t{self::Foo::T% & self::B /* '%' & '!' = '!' */};
+      if(t{self::Foo::T% & self::B /* '%' & '!' = '!' */} is{ForNonNullableByDefault} self::C) {
+        self::Foo::T baz = t{self::Foo::T & self::C /* '!' & '!' = '!' */};
       }
     }
   }
diff --git a/pkg/front_end/testcases/nnbd/intersection_types.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/intersection_types.dart.strong.transformed.expect
index 7facb01..977e568 100644
--- a/pkg/front_end/testcases/nnbd/intersection_types.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/intersection_types.dart.strong.transformed.expect
@@ -22,18 +22,18 @@
     : super core::Object::•()
     ;
   method doPromotionsToNullable(generic-covariant-impl self::Foo::T% t) → dynamic {
-    if(t is self::B?) {
-      self::Foo::T% & self::B? /* '%' & '?' = '%' */ bar = t{self::Foo::T% & self::B? /* '%' & '?' = '%' */};
-      if(t{self::Foo::T% & self::B? /* '%' & '?' = '%' */} is self::C?) {
-        self::Foo::T% & self::C? /* '%' & '?' = '%' */ baz = t{self::Foo::T% & self::C? /* '%' & '?' = '%' */};
+    if(t is{ForNonNullableByDefault} self::B?) {
+      self::Foo::T% bar = t{self::Foo::T% & self::B? /* '%' & '?' = '%' */};
+      if(t{self::Foo::T% & self::B? /* '%' & '?' = '%' */} is{ForNonNullableByDefault} self::C?) {
+        self::Foo::T% baz = t{self::Foo::T% & self::C? /* '%' & '?' = '%' */};
       }
     }
   }
   method doPromotionsToNonNullable(generic-covariant-impl self::Foo::T% t) → dynamic {
-    if(t is self::B) {
-      self::Foo::T% & self::B /* '%' & '!' = '!' */ bar = t{self::Foo::T% & self::B /* '%' & '!' = '!' */};
-      if(t{self::Foo::T% & self::B /* '%' & '!' = '!' */} is self::C) {
-        self::Foo::T & self::C /* '!' & '!' = '!' */ baz = t{self::Foo::T & self::C /* '!' & '!' = '!' */};
+    if(t is{ForNonNullableByDefault} self::B) {
+      self::Foo::T% bar = t{self::Foo::T% & self::B /* '%' & '!' = '!' */};
+      if(t{self::Foo::T% & self::B /* '%' & '!' = '!' */} is{ForNonNullableByDefault} self::C) {
+        self::Foo::T baz = t{self::Foo::T & self::C /* '!' & '!' = '!' */};
       }
     }
   }
diff --git a/pkg/front_end/testcases/nnbd/intersection_types.dart.weak.expect b/pkg/front_end/testcases/nnbd/intersection_types.dart.weak.expect
index 7facb01..977e568 100644
--- a/pkg/front_end/testcases/nnbd/intersection_types.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/intersection_types.dart.weak.expect
@@ -22,18 +22,18 @@
     : super core::Object::•()
     ;
   method doPromotionsToNullable(generic-covariant-impl self::Foo::T% t) → dynamic {
-    if(t is self::B?) {
-      self::Foo::T% & self::B? /* '%' & '?' = '%' */ bar = t{self::Foo::T% & self::B? /* '%' & '?' = '%' */};
-      if(t{self::Foo::T% & self::B? /* '%' & '?' = '%' */} is self::C?) {
-        self::Foo::T% & self::C? /* '%' & '?' = '%' */ baz = t{self::Foo::T% & self::C? /* '%' & '?' = '%' */};
+    if(t is{ForNonNullableByDefault} self::B?) {
+      self::Foo::T% bar = t{self::Foo::T% & self::B? /* '%' & '?' = '%' */};
+      if(t{self::Foo::T% & self::B? /* '%' & '?' = '%' */} is{ForNonNullableByDefault} self::C?) {
+        self::Foo::T% baz = t{self::Foo::T% & self::C? /* '%' & '?' = '%' */};
       }
     }
   }
   method doPromotionsToNonNullable(generic-covariant-impl self::Foo::T% t) → dynamic {
-    if(t is self::B) {
-      self::Foo::T% & self::B /* '%' & '!' = '!' */ bar = t{self::Foo::T% & self::B /* '%' & '!' = '!' */};
-      if(t{self::Foo::T% & self::B /* '%' & '!' = '!' */} is self::C) {
-        self::Foo::T & self::C /* '!' & '!' = '!' */ baz = t{self::Foo::T & self::C /* '!' & '!' = '!' */};
+    if(t is{ForNonNullableByDefault} self::B) {
+      self::Foo::T% bar = t{self::Foo::T% & self::B /* '%' & '!' = '!' */};
+      if(t{self::Foo::T% & self::B /* '%' & '!' = '!' */} is{ForNonNullableByDefault} self::C) {
+        self::Foo::T baz = t{self::Foo::T & self::C /* '!' & '!' = '!' */};
       }
     }
   }
diff --git a/pkg/front_end/testcases/nnbd/intersection_types.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/intersection_types.dart.weak.transformed.expect
index 7facb01..977e568 100644
--- a/pkg/front_end/testcases/nnbd/intersection_types.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/intersection_types.dart.weak.transformed.expect
@@ -22,18 +22,18 @@
     : super core::Object::•()
     ;
   method doPromotionsToNullable(generic-covariant-impl self::Foo::T% t) → dynamic {
-    if(t is self::B?) {
-      self::Foo::T% & self::B? /* '%' & '?' = '%' */ bar = t{self::Foo::T% & self::B? /* '%' & '?' = '%' */};
-      if(t{self::Foo::T% & self::B? /* '%' & '?' = '%' */} is self::C?) {
-        self::Foo::T% & self::C? /* '%' & '?' = '%' */ baz = t{self::Foo::T% & self::C? /* '%' & '?' = '%' */};
+    if(t is{ForNonNullableByDefault} self::B?) {
+      self::Foo::T% bar = t{self::Foo::T% & self::B? /* '%' & '?' = '%' */};
+      if(t{self::Foo::T% & self::B? /* '%' & '?' = '%' */} is{ForNonNullableByDefault} self::C?) {
+        self::Foo::T% baz = t{self::Foo::T% & self::C? /* '%' & '?' = '%' */};
       }
     }
   }
   method doPromotionsToNonNullable(generic-covariant-impl self::Foo::T% t) → dynamic {
-    if(t is self::B) {
-      self::Foo::T% & self::B /* '%' & '!' = '!' */ bar = t{self::Foo::T% & self::B /* '%' & '!' = '!' */};
-      if(t{self::Foo::T% & self::B /* '%' & '!' = '!' */} is self::C) {
-        self::Foo::T & self::C /* '!' & '!' = '!' */ baz = t{self::Foo::T & self::C /* '!' & '!' = '!' */};
+    if(t is{ForNonNullableByDefault} self::B) {
+      self::Foo::T% bar = t{self::Foo::T% & self::B /* '%' & '!' = '!' */};
+      if(t{self::Foo::T% & self::B /* '%' & '!' = '!' */} is{ForNonNullableByDefault} self::C) {
+        self::Foo::T baz = t{self::Foo::T & self::C /* '!' & '!' = '!' */};
       }
     }
   }
diff --git a/pkg/front_end/testcases/nnbd/later.dart.strong.expect b/pkg/front_end/testcases/nnbd/later.dart.strong.expect
index 182f45e..3327046 100644
--- a/pkg/front_end/testcases/nnbd/later.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/later.dart.strong.expect
@@ -118,7 +118,7 @@
 static method fisk() → dynamic async {
   late core::String s1 = invalid-expression "pkg/front_end/testcases/nnbd/later.dart:38:20: Error: `await` expressions are not supported in late local initializers.
   late String s1 = await hest();
-                   ^^^^^" as{TypeError} core::String;
+                   ^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::String;
   late core::String s2 = "${#C1}${invalid-expression "pkg/front_end/testcases/nnbd/later.dart:39:30: Error: `await` expressions are not supported in late local initializers.
   late String s2 = '\${fisk}\${await hest()}\${fisk}';
                              ^^^^^"}${#C1}";
diff --git a/pkg/front_end/testcases/nnbd/later.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/later.dart.strong.transformed.expect
index b079c14..f87102a 100644
--- a/pkg/front_end/testcases/nnbd/later.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/later.dart.strong.transformed.expect
@@ -186,7 +186,7 @@
         function #s1#initializer() → core::String
           return invalid-expression "pkg/front_end/testcases/nnbd/later.dart:38:20: Error: `await` expressions are not supported in late local initializers.
   late String s1 = await hest();
-                   ^^^^^" as{TypeError} core::String;
+                   ^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::String;
         late core::String s1 = #s1#initializer.call();
         function #s2#initializer() → core::String
           return "${#C1}${invalid-expression "pkg/front_end/testcases/nnbd/later.dart:39:30: Error: `await` expressions are not supported in late local initializers.
diff --git a/pkg/front_end/testcases/nnbd/later.dart.weak.expect b/pkg/front_end/testcases/nnbd/later.dart.weak.expect
index 182f45e..3327046 100644
--- a/pkg/front_end/testcases/nnbd/later.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/later.dart.weak.expect
@@ -118,7 +118,7 @@
 static method fisk() → dynamic async {
   late core::String s1 = invalid-expression "pkg/front_end/testcases/nnbd/later.dart:38:20: Error: `await` expressions are not supported in late local initializers.
   late String s1 = await hest();
-                   ^^^^^" as{TypeError} core::String;
+                   ^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::String;
   late core::String s2 = "${#C1}${invalid-expression "pkg/front_end/testcases/nnbd/later.dart:39:30: Error: `await` expressions are not supported in late local initializers.
   late String s2 = '\${fisk}\${await hest()}\${fisk}';
                              ^^^^^"}${#C1}";
diff --git a/pkg/front_end/testcases/nnbd/later.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/later.dart.weak.transformed.expect
index b079c14..f87102a 100644
--- a/pkg/front_end/testcases/nnbd/later.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/later.dart.weak.transformed.expect
@@ -186,7 +186,7 @@
         function #s1#initializer() → core::String
           return invalid-expression "pkg/front_end/testcases/nnbd/later.dart:38:20: Error: `await` expressions are not supported in late local initializers.
   late String s1 = await hest();
-                   ^^^^^" as{TypeError} core::String;
+                   ^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::String;
         late core::String s1 = #s1#initializer.call();
         function #s2#initializer() → core::String
           return "${#C1}${invalid-expression "pkg/front_end/testcases/nnbd/later.dart:39:30: Error: `await` expressions are not supported in late local initializers.
diff --git a/pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart.strong.expect b/pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart.strong.expect
index 84b205c4..123a821 100644
--- a/pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart.strong.expect
@@ -108,22 +108,22 @@
 static method testOptIn() → dynamic {
   self::nullableVar = let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:32:17: Error: A value of type 'double' can't be assigned to a variable of type 'int Function()?'.
   nullableVar = nonNullableVar;
-                ^" in self::nonNullableVar as{TypeError} () →? core::int;
+                ^" in self::nonNullableVar as{TypeError,ForNonNullableByDefault} () →? core::int;
   self::nonNullableVar = let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:33:20: Error: A value of type 'int Function()?' can't be assigned to a variable of type 'double'.
   nonNullableVar = nullableVar;
-                   ^" in self::nullableVar as{TypeError} core::double;
+                   ^" in self::nullableVar as{TypeError,ForNonNullableByDefault} core::double;
   mes::legacyVar = let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:34:15: Error: A value of type 'int Function()?' can't be assigned to a variable of type 'String'.
   legacyVar = nullableVar;
-              ^" in self::nullableVar as{TypeError} core::String*;
+              ^" in self::nullableVar as{TypeError,ForNonNullableByDefault} core::String*;
   self::nullableVar = let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:35:17: Error: A value of type 'String' can't be assigned to a variable of type 'int Function()?'.
   nullableVar = legacyVar;
-                ^" in mes::legacyVar as{TypeError} () →? core::int;
+                ^" in mes::legacyVar as{TypeError,ForNonNullableByDefault} () →? core::int;
   self::nonNullableVar = let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:36:20: Error: A value of type 'String' can't be assigned to a variable of type 'double'.
   nonNullableVar = legacyVar;
-                   ^" in mes::legacyVar as{TypeError} core::double;
+                   ^" in mes::legacyVar as{TypeError,ForNonNullableByDefault} core::double;
   mes::legacyVar = let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:37:15: Error: A value of type 'double' can't be assigned to a variable of type 'String'.
   legacyVar = nonNullableVar;
-              ^" in self::nonNullableVar as{TypeError} core::String*;
+              ^" in self::nonNullableVar as{TypeError,ForNonNullableByDefault} core::String*;
 }
 
 library;
diff --git a/pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart.weak.expect b/pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart.weak.expect
index 84b205c4..123a821 100644
--- a/pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart.weak.expect
@@ -108,22 +108,22 @@
 static method testOptIn() → dynamic {
   self::nullableVar = let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:32:17: Error: A value of type 'double' can't be assigned to a variable of type 'int Function()?'.
   nullableVar = nonNullableVar;
-                ^" in self::nonNullableVar as{TypeError} () →? core::int;
+                ^" in self::nonNullableVar as{TypeError,ForNonNullableByDefault} () →? core::int;
   self::nonNullableVar = let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:33:20: Error: A value of type 'int Function()?' can't be assigned to a variable of type 'double'.
   nonNullableVar = nullableVar;
-                   ^" in self::nullableVar as{TypeError} core::double;
+                   ^" in self::nullableVar as{TypeError,ForNonNullableByDefault} core::double;
   mes::legacyVar = let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:34:15: Error: A value of type 'int Function()?' can't be assigned to a variable of type 'String'.
   legacyVar = nullableVar;
-              ^" in self::nullableVar as{TypeError} core::String*;
+              ^" in self::nullableVar as{TypeError,ForNonNullableByDefault} core::String*;
   self::nullableVar = let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:35:17: Error: A value of type 'String' can't be assigned to a variable of type 'int Function()?'.
   nullableVar = legacyVar;
-                ^" in mes::legacyVar as{TypeError} () →? core::int;
+                ^" in mes::legacyVar as{TypeError,ForNonNullableByDefault} () →? core::int;
   self::nonNullableVar = let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:36:20: Error: A value of type 'String' can't be assigned to a variable of type 'double'.
   nonNullableVar = legacyVar;
-                   ^" in mes::legacyVar as{TypeError} core::double;
+                   ^" in mes::legacyVar as{TypeError,ForNonNullableByDefault} core::double;
   mes::legacyVar = let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:37:15: Error: A value of type 'double' can't be assigned to a variable of type 'String'.
   legacyVar = nonNullableVar;
-              ^" in self::nonNullableVar as{TypeError} core::String*;
+              ^" in self::nonNullableVar as{TypeError,ForNonNullableByDefault} core::String*;
 }
 
 library;
diff --git a/pkg/front_end/testcases/nnbd/messages_with_types_opt_out.dart.strong.expect b/pkg/front_end/testcases/nnbd/messages_with_types_opt_out.dart.strong.expect
index 846f621..2b26e9b 100644
--- a/pkg/front_end/testcases/nnbd/messages_with_types_opt_out.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/messages_with_types_opt_out.dart.strong.expect
@@ -235,20 +235,20 @@
 static method testOptIn() → dynamic {
   mes::nullableVar = let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:32:17: Error: A value of type 'double' can't be assigned to a variable of type 'int Function()?'.
   nullableVar = nonNullableVar;
-                ^" in mes::nonNullableVar as{TypeError} () →? core::int;
+                ^" in mes::nonNullableVar as{TypeError,ForNonNullableByDefault} () →? core::int;
   mes::nonNullableVar = let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:33:20: Error: A value of type 'int Function()?' can't be assigned to a variable of type 'double'.
   nonNullableVar = nullableVar;
-                   ^" in mes::nullableVar as{TypeError} core::double;
+                   ^" in mes::nullableVar as{TypeError,ForNonNullableByDefault} core::double;
   self::legacyVar = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:34:15: Error: A value of type 'int Function()?' can't be assigned to a variable of type 'String'.
   legacyVar = nullableVar;
-              ^" in mes::nullableVar as{TypeError} core::String*;
+              ^" in mes::nullableVar as{TypeError,ForNonNullableByDefault} core::String*;
   mes::nullableVar = let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:35:17: Error: A value of type 'String' can't be assigned to a variable of type 'int Function()?'.
   nullableVar = legacyVar;
-                ^" in self::legacyVar as{TypeError} () →? core::int;
+                ^" in self::legacyVar as{TypeError,ForNonNullableByDefault} () →? core::int;
   mes::nonNullableVar = let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:36:20: Error: A value of type 'String' can't be assigned to a variable of type 'double'.
   nonNullableVar = legacyVar;
-                   ^" in self::legacyVar as{TypeError} core::double;
+                   ^" in self::legacyVar as{TypeError,ForNonNullableByDefault} core::double;
   self::legacyVar = let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:37:15: Error: A value of type 'double' can't be assigned to a variable of type 'String'.
   legacyVar = nonNullableVar;
-              ^" in mes::nonNullableVar as{TypeError} core::String*;
+              ^" in mes::nonNullableVar as{TypeError,ForNonNullableByDefault} core::String*;
 }
diff --git a/pkg/front_end/testcases/nnbd/messages_with_types_opt_out.dart.weak.expect b/pkg/front_end/testcases/nnbd/messages_with_types_opt_out.dart.weak.expect
index 846f621..2b26e9b 100644
--- a/pkg/front_end/testcases/nnbd/messages_with_types_opt_out.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/messages_with_types_opt_out.dart.weak.expect
@@ -235,20 +235,20 @@
 static method testOptIn() → dynamic {
   mes::nullableVar = let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:32:17: Error: A value of type 'double' can't be assigned to a variable of type 'int Function()?'.
   nullableVar = nonNullableVar;
-                ^" in mes::nonNullableVar as{TypeError} () →? core::int;
+                ^" in mes::nonNullableVar as{TypeError,ForNonNullableByDefault} () →? core::int;
   mes::nonNullableVar = let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:33:20: Error: A value of type 'int Function()?' can't be assigned to a variable of type 'double'.
   nonNullableVar = nullableVar;
-                   ^" in mes::nullableVar as{TypeError} core::double;
+                   ^" in mes::nullableVar as{TypeError,ForNonNullableByDefault} core::double;
   self::legacyVar = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:34:15: Error: A value of type 'int Function()?' can't be assigned to a variable of type 'String'.
   legacyVar = nullableVar;
-              ^" in mes::nullableVar as{TypeError} core::String*;
+              ^" in mes::nullableVar as{TypeError,ForNonNullableByDefault} core::String*;
   mes::nullableVar = let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:35:17: Error: A value of type 'String' can't be assigned to a variable of type 'int Function()?'.
   nullableVar = legacyVar;
-                ^" in self::legacyVar as{TypeError} () →? core::int;
+                ^" in self::legacyVar as{TypeError,ForNonNullableByDefault} () →? core::int;
   mes::nonNullableVar = let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:36:20: Error: A value of type 'String' can't be assigned to a variable of type 'double'.
   nonNullableVar = legacyVar;
-                   ^" in self::legacyVar as{TypeError} core::double;
+                   ^" in self::legacyVar as{TypeError,ForNonNullableByDefault} core::double;
   self::legacyVar = let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/messages_with_types_opt_in.dart:37:15: Error: A value of type 'double' can't be assigned to a variable of type 'String'.
   legacyVar = nonNullableVar;
-              ^" in mes::nonNullableVar as{TypeError} core::String*;
+              ^" in mes::nonNullableVar as{TypeError,ForNonNullableByDefault} core::String*;
 }
diff --git a/pkg/front_end/testcases/nnbd/nullable_receiver.dart.strong.expect b/pkg/front_end/testcases/nnbd/nullable_receiver.dart.strong.expect
index d981a0b..4572332 100644
--- a/pkg/front_end/testcases/nnbd/nullable_receiver.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/nullable_receiver.dart.strong.expect
@@ -48,14 +48,17 @@
 //   b.toString(0);
 //     ^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Function'.
-//  - 'Function' is from 'dart:core'.
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:17: Error: Can't tear off method 'call' from a potentially null value.
 //   Function f1 = a;
-//            ^
+//                 ^
 //
-// pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:19: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:24: Error: Can't tear off method 'call' from a potentially null value.
 //   void Function() f2 = a;
-//                   ^
+//                        ^
+//
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:31:25: Error: Can't tear off method 'call' from a potentially null value.
+//   void Function()? f3 = a;
+//                         ^
 //
 import self as self;
 import "dart:core" as core;
@@ -115,14 +118,15 @@
 Try calling using ?. instead.
   b.toString(0);
     ^^^^^^^^" in b.{self::B::toString}(0);
-  core::Function f1 = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Function'.
- - 'Function' is from 'dart:core'.
+  core::Function f1 = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:17: Error: Can't tear off method 'call' from a potentially null value.
   Function f1 = a;
-           ^" in (let final self::A? #t10 = a in #t10.==(null) ?{() →? void} null : #t10.{self::A::call}) as{TypeError} core::Function;
-  () → void f2 = let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:19: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
+                ^" in a as{TypeError} core::Function;
+  () → void f2 = let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:24: Error: Can't tear off method 'call' from a potentially null value.
   void Function() f2 = a;
-                  ^" in (let final self::A? #t12 = a in #t12.==(null) ?{() →? void} null : #t12.{self::A::call}) as{TypeError} () → void;
-  () →? void f3 = let final self::A? #t13 = a in #t13.==(null) ?{() →? void} null : #t13.{self::A::call};
+                       ^" in a as{TypeError} () → void;
+  () →? void f3 = let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/nullable_receiver.dart:31:25: Error: Can't tear off method 'call' from a potentially null value.
+  void Function()? f3 = a;
+                        ^" in a as{TypeError} () →? void;
 }
 static method ok<T extends core::Object? = core::Object?>(core::String? s, self::A? a, self::ok::T% t, self::B? b, core::Invocation i) → dynamic {
   s.{core::String::==}(s);
diff --git a/pkg/front_end/testcases/nnbd/nullable_receiver.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/nullable_receiver.dart.strong.transformed.expect
index d981a0b..4572332 100644
--- a/pkg/front_end/testcases/nnbd/nullable_receiver.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/nullable_receiver.dart.strong.transformed.expect
@@ -48,14 +48,17 @@
 //   b.toString(0);
 //     ^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Function'.
-//  - 'Function' is from 'dart:core'.
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:17: Error: Can't tear off method 'call' from a potentially null value.
 //   Function f1 = a;
-//            ^
+//                 ^
 //
-// pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:19: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:24: Error: Can't tear off method 'call' from a potentially null value.
 //   void Function() f2 = a;
-//                   ^
+//                        ^
+//
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:31:25: Error: Can't tear off method 'call' from a potentially null value.
+//   void Function()? f3 = a;
+//                         ^
 //
 import self as self;
 import "dart:core" as core;
@@ -115,14 +118,15 @@
 Try calling using ?. instead.
   b.toString(0);
     ^^^^^^^^" in b.{self::B::toString}(0);
-  core::Function f1 = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:12: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'Function'.
- - 'Function' is from 'dart:core'.
+  core::Function f1 = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:17: Error: Can't tear off method 'call' from a potentially null value.
   Function f1 = a;
-           ^" in (let final self::A? #t10 = a in #t10.==(null) ?{() →? void} null : #t10.{self::A::call}) as{TypeError} core::Function;
-  () → void f2 = let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:19: Error: A value of type 'void Function()?' can't be assigned to a variable of type 'void Function()'.
+                ^" in a as{TypeError} core::Function;
+  () → void f2 = let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:24: Error: Can't tear off method 'call' from a potentially null value.
   void Function() f2 = a;
-                  ^" in (let final self::A? #t12 = a in #t12.==(null) ?{() →? void} null : #t12.{self::A::call}) as{TypeError} () → void;
-  () →? void f3 = let final self::A? #t13 = a in #t13.==(null) ?{() →? void} null : #t13.{self::A::call};
+                       ^" in a as{TypeError} () → void;
+  () →? void f3 = let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/nullable_receiver.dart:31:25: Error: Can't tear off method 'call' from a potentially null value.
+  void Function()? f3 = a;
+                        ^" in a as{TypeError} () →? void;
 }
 static method ok<T extends core::Object? = core::Object?>(core::String? s, self::A? a, self::ok::T% t, self::B? b, core::Invocation i) → dynamic {
   s.{core::String::==}(s);
diff --git a/pkg/front_end/testcases/nnbd/nullable_receiver.dart.weak.expect b/pkg/front_end/testcases/nnbd/nullable_receiver.dart.weak.expect
index 54ee84d..cd79d91 100644
--- a/pkg/front_end/testcases/nnbd/nullable_receiver.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/nullable_receiver.dart.weak.expect
@@ -48,14 +48,17 @@
 //   b.toString(0);
 //     ^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:12: Warning: Assigning value of type 'void Function()?' to a variable of type 'Function'.
-//  - 'Function' is from 'dart:core'.
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:17: Warning: Tearing off method 'call' from a potentially null value.
 //   Function f1 = a;
-//            ^
+//                 ^
 //
-// pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:19: Warning: Assigning value of type 'void Function()?' to a variable of type 'void Function()'.
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:24: Warning: Tearing off method 'call' from a potentially null value.
 //   void Function() f2 = a;
-//                   ^
+//                        ^
+//
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:31:25: Warning: Tearing off method 'call' from a potentially null value.
+//   void Function()? f3 = a;
+//                         ^
 //
 import self as self;
 import "dart:core" as core;
@@ -85,9 +88,9 @@
   a.{self::A::baz} = 42;
   a.{self::A::call}();
   b.{self::B::toString}(0);
-  core::Function f1 = let final self::A? #t1 = a in #t1.==(null) ?{() →? void} null : #t1.{self::A::call};
-  () → void f2 = let final self::A? #t2 = a in #t2.==(null) ?{() →? void} null : #t2.{self::A::call};
-  () →? void f3 = let final self::A? #t3 = a in #t3.==(null) ?{() →? void} null : #t3.{self::A::call};
+  core::Function f1 = a as{TypeError} core::Function;
+  () → void f2 = a as{TypeError} () → void;
+  () →? void f3 = a as{TypeError} () →? void;
 }
 static method ok<T extends core::Object? = core::Object?>(core::String? s, self::A? a, self::ok::T% t, self::B? b, core::Invocation i) → dynamic {
   s.{core::String::==}(s);
diff --git a/pkg/front_end/testcases/nnbd/nullable_receiver.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/nullable_receiver.dart.weak.transformed.expect
index 54ee84d..cd79d91 100644
--- a/pkg/front_end/testcases/nnbd/nullable_receiver.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/nullable_receiver.dart.weak.transformed.expect
@@ -48,14 +48,17 @@
 //   b.toString(0);
 //     ^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:12: Warning: Assigning value of type 'void Function()?' to a variable of type 'Function'.
-//  - 'Function' is from 'dart:core'.
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:29:17: Warning: Tearing off method 'call' from a potentially null value.
 //   Function f1 = a;
-//            ^
+//                 ^
 //
-// pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:19: Warning: Assigning value of type 'void Function()?' to a variable of type 'void Function()'.
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:30:24: Warning: Tearing off method 'call' from a potentially null value.
 //   void Function() f2 = a;
-//                   ^
+//                        ^
+//
+// pkg/front_end/testcases/nnbd/nullable_receiver.dart:31:25: Warning: Tearing off method 'call' from a potentially null value.
+//   void Function()? f3 = a;
+//                         ^
 //
 import self as self;
 import "dart:core" as core;
@@ -85,9 +88,9 @@
   a.{self::A::baz} = 42;
   a.{self::A::call}();
   b.{self::B::toString}(0);
-  core::Function f1 = let final self::A? #t1 = a in #t1.==(null) ?{() →? void} null : #t1.{self::A::call};
-  () → void f2 = let final self::A? #t2 = a in #t2.==(null) ?{() →? void} null : #t2.{self::A::call};
-  () →? void f3 = let final self::A? #t3 = a in #t3.==(null) ?{() →? void} null : #t3.{self::A::call};
+  core::Function f1 = a as{TypeError} core::Function;
+  () → void f2 = a as{TypeError} () → void;
+  () →? void f3 = a as{TypeError} () →? void;
 }
 static method ok<T extends core::Object? = core::Object?>(core::String? s, self::A? a, self::ok::T% t, self::B? b, core::Invocation i) → dynamic {
   s.{core::String::==}(s);
diff --git a/pkg/front_end/testcases/nnbd/platform_optional_parameters/libraries.json b/pkg/front_end/testcases/nnbd/platform_optional_parameters/libraries.json
new file mode 100644
index 0000000..154c73c
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/platform_optional_parameters/libraries.json
@@ -0,0 +1,12 @@
+{
+  "none": {
+    "libraries": {
+      "test": {
+        "patches": [
+          "patch_lib.dart"
+        ],
+        "uri": "origin_lib.dart"
+      }
+    }
+  }
+}
diff --git a/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart
new file mode 100644
index 0000000..8610ab9
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart
@@ -0,0 +1,9 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:test';
+
+main() {
+  Class? c = new Class();
+}
diff --git a/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.outline.expect b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.outline.expect
new file mode 100644
index 0000000..ab6f690
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.outline.expect
@@ -0,0 +1,67 @@
+library;
+import self as self;
+
+import "dart:test";
+
+static method main() → dynamic
+  ;
+
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:11:27: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   void patchedMethod([int i]) {}
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:13:29: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   void _injectedMethod([int i]) {}
+//                             ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:17:25: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// void patchedMethod([int i]) {}
+//                         ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:19:27: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// void _injectedMethod([int i]) {}
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:6:20: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   void method([int i]) {}
+//                    ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:8:36: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   external void patchedMethod([int i]);
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:11:18: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// void method([int i]) {}
+//                  ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:13:34: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// external void patchedMethod([int i]);
+//                                  ^
+//
+import self as self2;
+import "dart:_internal" as _in;
+import "dart:core" as core;
+
+import "dart:_internal";
+
+@_in::patch
+class Class extends core::Object {
+  synthetic constructor •() → self2::Class
+    ;
+  method method([core::int i]) → void
+    ;
+  @_in::patch
+  external method patchedMethod([core::int i]) → void;
+  method /* from org-dartlang-testcase:///patch_lib.dart */ _injectedMethod([core::int i]) → void
+    ;
+}
+static method method([core::int i]) → void
+  ;
+@_in::patch
+external static abstract method patchedMethod([core::int i]) → void;
+static method /* from org-dartlang-testcase:///patch_lib.dart */ _injectedMethod([core::int i]) → void
+  ;
diff --git a/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.strong.expect b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.strong.expect
new file mode 100644
index 0000000..1f952a2
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.strong.expect
@@ -0,0 +1,71 @@
+library;
+import self as self;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  test::Class? c = new test::Class::•();
+}
+
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:11:27: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   void patchedMethod([int i]) {}
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:13:29: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   void _injectedMethod([int i]) {}
+//                             ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:17:25: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// void patchedMethod([int i]) {}
+//                         ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:19:27: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// void _injectedMethod([int i]) {}
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:6:20: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   void method([int i]) {}
+//                    ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:8:36: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   external void patchedMethod([int i]);
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:11:18: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// void method([int i]) {}
+//                  ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:13:34: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// external void patchedMethod([int i]);
+//                                  ^
+//
+import self as test;
+import "dart:_internal" as _in;
+import "dart:core" as core;
+
+import "dart:_internal";
+
+@#C1
+class Class extends core::Object {
+  synthetic constructor •() → test::Class
+    : super core::Object::•()
+    ;
+  method method([core::int i = #C2]) → void {}
+  @#C1
+  method /* from org-dartlang-testcase:///patch_lib.dart */ patchedMethod([core::int i = #C2]) → void {}
+  method /* from org-dartlang-testcase:///patch_lib.dart */ _injectedMethod([core::int i = #C2]) → void {}
+}
+static method method([core::int i = #C2]) → void {}
+@#C1
+static method /* from org-dartlang-testcase:///patch_lib.dart */ patchedMethod([core::int i = #C2]) → void {}
+static method /* from org-dartlang-testcase:///patch_lib.dart */ _injectedMethod([core::int i = #C2]) → void {}
+
+constants  {
+  #C1 = _in::_Patch {}
+  #C2 = null
+}
diff --git a/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.strong.transformed.expect
new file mode 100644
index 0000000..1f952a2
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.strong.transformed.expect
@@ -0,0 +1,71 @@
+library;
+import self as self;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  test::Class? c = new test::Class::•();
+}
+
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:11:27: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   void patchedMethod([int i]) {}
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:13:29: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   void _injectedMethod([int i]) {}
+//                             ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:17:25: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// void patchedMethod([int i]) {}
+//                         ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:19:27: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// void _injectedMethod([int i]) {}
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:6:20: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   void method([int i]) {}
+//                    ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:8:36: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+//   external void patchedMethod([int i]);
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:11:18: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// void method([int i]) {}
+//                  ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:13:34: Error: Optional parameter 'i' should have a default value because its type 'int' doesn't allow null.
+// external void patchedMethod([int i]);
+//                                  ^
+//
+import self as test;
+import "dart:_internal" as _in;
+import "dart:core" as core;
+
+import "dart:_internal";
+
+@#C1
+class Class extends core::Object {
+  synthetic constructor •() → test::Class
+    : super core::Object::•()
+    ;
+  method method([core::int i = #C2]) → void {}
+  @#C1
+  method /* from org-dartlang-testcase:///patch_lib.dart */ patchedMethod([core::int i = #C2]) → void {}
+  method /* from org-dartlang-testcase:///patch_lib.dart */ _injectedMethod([core::int i = #C2]) → void {}
+}
+static method method([core::int i = #C2]) → void {}
+@#C1
+static method /* from org-dartlang-testcase:///patch_lib.dart */ patchedMethod([core::int i = #C2]) → void {}
+static method /* from org-dartlang-testcase:///patch_lib.dart */ _injectedMethod([core::int i = #C2]) → void {}
+
+constants  {
+  #C1 = _in::_Patch {}
+  #C2 = null
+}
diff --git a/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.weak.expect b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.weak.expect
new file mode 100644
index 0000000..33e8f39
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.weak.expect
@@ -0,0 +1,71 @@
+library;
+import self as self;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  test::Class? c = new test::Class::•();
+}
+
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:11:27: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+//   void patchedMethod([int i]) {}
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:13:29: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+//   void _injectedMethod([int i]) {}
+//                             ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:17:25: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+// void patchedMethod([int i]) {}
+//                         ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:19:27: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+// void _injectedMethod([int i]) {}
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:6:20: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+//   void method([int i]) {}
+//                    ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:8:36: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+//   external void patchedMethod([int i]);
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:11:18: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+// void method([int i]) {}
+//                  ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:13:34: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+// external void patchedMethod([int i]);
+//                                  ^
+//
+import self as test;
+import "dart:_internal" as _in;
+import "dart:core" as core;
+
+import "dart:_internal";
+
+@#C1
+class Class extends core::Object {
+  synthetic constructor •() → test::Class
+    : super core::Object::•()
+    ;
+  method method([core::int i = #C2]) → void {}
+  @#C1
+  method /* from org-dartlang-testcase:///patch_lib.dart */ patchedMethod([core::int i = #C2]) → void {}
+  method /* from org-dartlang-testcase:///patch_lib.dart */ _injectedMethod([core::int i = #C2]) → void {}
+}
+static method method([core::int i = #C2]) → void {}
+@#C1
+static method /* from org-dartlang-testcase:///patch_lib.dart */ patchedMethod([core::int i = #C2]) → void {}
+static method /* from org-dartlang-testcase:///patch_lib.dart */ _injectedMethod([core::int i = #C2]) → void {}
+
+constants  {
+  #C1 = _in::_Patch {}
+  #C2 = null
+}
diff --git a/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.weak.transformed.expect
new file mode 100644
index 0000000..33e8f39
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/platform_optional_parameters/main.dart.weak.transformed.expect
@@ -0,0 +1,71 @@
+library;
+import self as self;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  test::Class? c = new test::Class::•();
+}
+
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:11:27: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+//   void patchedMethod([int i]) {}
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:13:29: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+//   void _injectedMethod([int i]) {}
+//                             ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:17:25: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+// void patchedMethod([int i]) {}
+//                         ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart:19:27: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+// void _injectedMethod([int i]) {}
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:6:20: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+//   void method([int i]) {}
+//                    ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:8:36: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+//   external void patchedMethod([int i]);
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:11:18: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+// void method([int i]) {}
+//                  ^
+//
+// pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart:13:34: Warning: Optional parameter 'i' doesn't have a default value and its type 'int' doesn't allow null.
+// external void patchedMethod([int i]);
+//                                  ^
+//
+import self as test;
+import "dart:_internal" as _in;
+import "dart:core" as core;
+
+import "dart:_internal";
+
+@#C1
+class Class extends core::Object {
+  synthetic constructor •() → test::Class
+    : super core::Object::•()
+    ;
+  method method([core::int i = #C2]) → void {}
+  @#C1
+  method /* from org-dartlang-testcase:///patch_lib.dart */ patchedMethod([core::int i = #C2]) → void {}
+  method /* from org-dartlang-testcase:///patch_lib.dart */ _injectedMethod([core::int i = #C2]) → void {}
+}
+static method method([core::int i = #C2]) → void {}
+@#C1
+static method /* from org-dartlang-testcase:///patch_lib.dart */ patchedMethod([core::int i = #C2]) → void {}
+static method /* from org-dartlang-testcase:///patch_lib.dart */ _injectedMethod([core::int i = #C2]) → void {}
+
+constants  {
+  #C1 = _in::_Patch {}
+  #C2 = null
+}
diff --git a/pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart b/pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart
new file mode 100644
index 0000000..afda628
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/platform_optional_parameters/origin_lib.dart
@@ -0,0 +1,13 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class Class {
+  void method([int i]) {}
+
+  external void patchedMethod([int i]);
+}
+
+void method([int i]) {}
+
+external void patchedMethod([int i]);
diff --git a/pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart b/pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart
new file mode 100644
index 0000000..74deeb3
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/platform_optional_parameters/patch_lib.dart
@@ -0,0 +1,19 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// ignore: import_internal_library
+import 'dart:_internal';
+
+@patch
+class Class {
+  @patch
+  void patchedMethod([int i]) {}
+
+  void _injectedMethod([int i]) {}
+}
+
+@patch
+void patchedMethod([int i]) {}
+
+void _injectedMethod([int i]) {}
diff --git a/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart
new file mode 100644
index 0000000..69083d2
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart
@@ -0,0 +1,31 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class C {
+  int call() => 0;
+}
+
+functionContext(int Function() f) {}
+
+nullableFunctionContext(int Function()? f) {}
+
+foo<T extends C?>(C? c, T t, T? nt) {
+  functionContext(null as C?); // Error.
+  nullableFunctionContext(null as C?); // Error.
+  functionContext(c); // Error.
+  nullableFunctionContext(c); // Error.
+  functionContext(t); // Error.
+  nullableFunctionContext(t); // Error.
+  functionContext(nt); // Error.
+  nullableFunctionContext(nt); // Error.
+}
+
+bar<T extends C>(C c, T t) {
+  functionContext(c); // Shouldn't result in a compile-time error.
+  nullableFunctionContext(c); // Shouldn't result in a compile-time error.
+  functionContext(t); // Shouldn't result in a compile-time error.
+  nullableFunctionContext(t); // Shouldn't result in a compile-time error.
+}
+
+main() {}
diff --git a/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.outline.expect b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.outline.expect
new file mode 100644
index 0000000..8f8831c
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.outline.expect
@@ -0,0 +1,20 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class C extends core::Object {
+  synthetic constructor •() → self::C
+    ;
+  method call() → core::int
+    ;
+}
+static method functionContext(() → core::int f) → dynamic
+  ;
+static method nullableFunctionContext(() →? core::int f) → dynamic
+  ;
+static method foo<T extends self::C? = self::C?>(self::C? c, self::foo::T% t, self::foo::T? nt) → dynamic
+  ;
+static method bar<T extends self::C = self::C>(self::C c, self::bar::T t) → dynamic
+  ;
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.strong.expect b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.strong.expect
new file mode 100644
index 0000000..249b918
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.strong.expect
@@ -0,0 +1,93 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:14:24: Error: Can't tear off method 'call' from a potentially null value.
+//   functionContext(null as C?); // Error.
+//                        ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:15:32: Error: Can't tear off method 'call' from a potentially null value.
+//   nullableFunctionContext(null as C?); // Error.
+//                                ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:16:19: Error: Can't tear off method 'call' from a potentially null value.
+//   functionContext(c); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:17:27: Error: Can't tear off method 'call' from a potentially null value.
+//   nullableFunctionContext(c); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:18:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(t); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:19:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(t); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:20:19: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(nt); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:21:27: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(nt); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:27:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(t); // Shouldn't result in a compile-time error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:28:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(t); // Shouldn't result in a compile-time error.
+//                           ^
+//
+import self as self;
+import "dart:core" as core;
+
+class C extends core::Object {
+  synthetic constructor •() → self::C
+    : super core::Object::•()
+    ;
+  method call() → core::int
+    return 0;
+}
+static method functionContext(() → core::int f) → dynamic {}
+static method nullableFunctionContext(() →? core::int f) → dynamic {}
+static method foo<T extends self::C? = self::C?>(self::C? c, self::foo::T% t, self::foo::T? nt) → dynamic {
+  self::functionContext(let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:14:24: Error: Can't tear off method 'call' from a potentially null value.
+  functionContext(null as C?); // Error.
+                       ^" in (null as{ForNonNullableByDefault} self::C?) as{TypeError} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:15:32: Error: Can't tear off method 'call' from a potentially null value.
+  nullableFunctionContext(null as C?); // Error.
+                               ^" in (null as{ForNonNullableByDefault} self::C?) as{TypeError} () →? core::int);
+  self::functionContext(let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:16:19: Error: Can't tear off method 'call' from a potentially null value.
+  functionContext(c); // Error.
+                  ^" in c as{TypeError} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:17:27: Error: Can't tear off method 'call' from a potentially null value.
+  nullableFunctionContext(c); // Error.
+                          ^" in c as{TypeError} () →? core::int);
+  self::functionContext(let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:18:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+  functionContext(t); // Error.
+                  ^" in t as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:19:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(t); // Error.
+                          ^" in t as{TypeError,ForNonNullableByDefault} () →? core::int);
+  self::functionContext(let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:20:19: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()'.
+  functionContext(nt); // Error.
+                  ^" in nt as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:21:27: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(nt); // Error.
+                          ^" in nt as{TypeError,ForNonNullableByDefault} () →? core::int);
+}
+static method bar<T extends self::C = self::C>(self::C c, self::bar::T t) → dynamic {
+  self::functionContext(let final self::C #t9 = c in #t9.==(null) ?{() → core::int} null : #t9.{self::C::call});
+  self::nullableFunctionContext(let final self::C #t10 = c in #t10.==(null) ?{() → core::int} null : #t10.{self::C::call});
+  self::functionContext(let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:27:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+  functionContext(t); // Shouldn't result in a compile-time error.
+                  ^" in t as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:28:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(t); // Shouldn't result in a compile-time error.
+                          ^" in t as{TypeError,ForNonNullableByDefault} () →? core::int);
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.strong.transformed.expect
new file mode 100644
index 0000000..249b918
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.strong.transformed.expect
@@ -0,0 +1,93 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:14:24: Error: Can't tear off method 'call' from a potentially null value.
+//   functionContext(null as C?); // Error.
+//                        ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:15:32: Error: Can't tear off method 'call' from a potentially null value.
+//   nullableFunctionContext(null as C?); // Error.
+//                                ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:16:19: Error: Can't tear off method 'call' from a potentially null value.
+//   functionContext(c); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:17:27: Error: Can't tear off method 'call' from a potentially null value.
+//   nullableFunctionContext(c); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:18:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(t); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:19:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(t); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:20:19: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(nt); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:21:27: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(nt); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:27:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(t); // Shouldn't result in a compile-time error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:28:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(t); // Shouldn't result in a compile-time error.
+//                           ^
+//
+import self as self;
+import "dart:core" as core;
+
+class C extends core::Object {
+  synthetic constructor •() → self::C
+    : super core::Object::•()
+    ;
+  method call() → core::int
+    return 0;
+}
+static method functionContext(() → core::int f) → dynamic {}
+static method nullableFunctionContext(() →? core::int f) → dynamic {}
+static method foo<T extends self::C? = self::C?>(self::C? c, self::foo::T% t, self::foo::T? nt) → dynamic {
+  self::functionContext(let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:14:24: Error: Can't tear off method 'call' from a potentially null value.
+  functionContext(null as C?); // Error.
+                       ^" in (null as{ForNonNullableByDefault} self::C?) as{TypeError} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:15:32: Error: Can't tear off method 'call' from a potentially null value.
+  nullableFunctionContext(null as C?); // Error.
+                               ^" in (null as{ForNonNullableByDefault} self::C?) as{TypeError} () →? core::int);
+  self::functionContext(let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:16:19: Error: Can't tear off method 'call' from a potentially null value.
+  functionContext(c); // Error.
+                  ^" in c as{TypeError} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:17:27: Error: Can't tear off method 'call' from a potentially null value.
+  nullableFunctionContext(c); // Error.
+                          ^" in c as{TypeError} () →? core::int);
+  self::functionContext(let final<BottomType> #t5 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:18:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+  functionContext(t); // Error.
+                  ^" in t as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:19:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(t); // Error.
+                          ^" in t as{TypeError,ForNonNullableByDefault} () →? core::int);
+  self::functionContext(let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:20:19: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()'.
+  functionContext(nt); // Error.
+                  ^" in nt as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:21:27: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(nt); // Error.
+                          ^" in nt as{TypeError,ForNonNullableByDefault} () →? core::int);
+}
+static method bar<T extends self::C = self::C>(self::C c, self::bar::T t) → dynamic {
+  self::functionContext(let final self::C #t9 = c in #t9.==(null) ?{() → core::int} null : #t9.{self::C::call});
+  self::nullableFunctionContext(let final self::C #t10 = c in #t10.==(null) ?{() → core::int} null : #t10.{self::C::call});
+  self::functionContext(let final<BottomType> #t11 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:27:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+  functionContext(t); // Shouldn't result in a compile-time error.
+                  ^" in t as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:28:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(t); // Shouldn't result in a compile-time error.
+                          ^" in t as{TypeError,ForNonNullableByDefault} () →? core::int);
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.weak.expect b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.weak.expect
new file mode 100644
index 0000000..c9f6d6a
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.weak.expect
@@ -0,0 +1,85 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:14:24: Warning: Tearing off method 'call' from a potentially null value.
+//   functionContext(null as C?); // Error.
+//                        ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:15:32: Warning: Tearing off method 'call' from a potentially null value.
+//   nullableFunctionContext(null as C?); // Error.
+//                                ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:16:19: Warning: Tearing off method 'call' from a potentially null value.
+//   functionContext(c); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:17:27: Warning: Tearing off method 'call' from a potentially null value.
+//   nullableFunctionContext(c); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:18:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(t); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:19:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(t); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:20:19: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(nt); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:21:27: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(nt); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:27:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(t); // Shouldn't result in a compile-time error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:28:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(t); // Shouldn't result in a compile-time error.
+//                           ^
+//
+import self as self;
+import "dart:core" as core;
+
+class C extends core::Object {
+  synthetic constructor •() → self::C
+    : super core::Object::•()
+    ;
+  method call() → core::int
+    return 0;
+}
+static method functionContext(() → core::int f) → dynamic {}
+static method nullableFunctionContext(() →? core::int f) → dynamic {}
+static method foo<T extends self::C? = self::C?>(self::C? c, self::foo::T% t, self::foo::T? nt) → dynamic {
+  self::functionContext((null as{ForNonNullableByDefault} self::C?) as{TypeError} () → core::int);
+  self::nullableFunctionContext((null as{ForNonNullableByDefault} self::C?) as{TypeError} () →? core::int);
+  self::functionContext(c as{TypeError} () → core::int);
+  self::nullableFunctionContext(c as{TypeError} () →? core::int);
+  self::functionContext(let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:18:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+  functionContext(t); // Error.
+                  ^" in t as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:19:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(t); // Error.
+                          ^" in t as{TypeError,ForNonNullableByDefault} () →? core::int);
+  self::functionContext(let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:20:19: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()'.
+  functionContext(nt); // Error.
+                  ^" in nt as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:21:27: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(nt); // Error.
+                          ^" in nt as{TypeError,ForNonNullableByDefault} () →? core::int);
+}
+static method bar<T extends self::C = self::C>(self::C c, self::bar::T t) → dynamic {
+  self::functionContext(let final self::C #t5 = c in #t5.==(null) ?{() → core::int} null : #t5.{self::C::call});
+  self::nullableFunctionContext(let final self::C #t6 = c in #t6.==(null) ?{() → core::int} null : #t6.{self::C::call});
+  self::functionContext(let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:27:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+  functionContext(t); // Shouldn't result in a compile-time error.
+                  ^" in t as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:28:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(t); // Shouldn't result in a compile-time error.
+                          ^" in t as{TypeError,ForNonNullableByDefault} () →? core::int);
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.weak.transformed.expect
new file mode 100644
index 0000000..c9f6d6a
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart.weak.transformed.expect
@@ -0,0 +1,85 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:14:24: Warning: Tearing off method 'call' from a potentially null value.
+//   functionContext(null as C?); // Error.
+//                        ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:15:32: Warning: Tearing off method 'call' from a potentially null value.
+//   nullableFunctionContext(null as C?); // Error.
+//                                ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:16:19: Warning: Tearing off method 'call' from a potentially null value.
+//   functionContext(c); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:17:27: Warning: Tearing off method 'call' from a potentially null value.
+//   nullableFunctionContext(c); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:18:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(t); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:19:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(t); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:20:19: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(nt); // Error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:21:27: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(nt); // Error.
+//                           ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:27:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+//   functionContext(t); // Shouldn't result in a compile-time error.
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:28:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+//   nullableFunctionContext(t); // Shouldn't result in a compile-time error.
+//                           ^
+//
+import self as self;
+import "dart:core" as core;
+
+class C extends core::Object {
+  synthetic constructor •() → self::C
+    : super core::Object::•()
+    ;
+  method call() → core::int
+    return 0;
+}
+static method functionContext(() → core::int f) → dynamic {}
+static method nullableFunctionContext(() →? core::int f) → dynamic {}
+static method foo<T extends self::C? = self::C?>(self::C? c, self::foo::T% t, self::foo::T? nt) → dynamic {
+  self::functionContext((null as{ForNonNullableByDefault} self::C?) as{TypeError} () → core::int);
+  self::nullableFunctionContext((null as{ForNonNullableByDefault} self::C?) as{TypeError} () →? core::int);
+  self::functionContext(c as{TypeError} () → core::int);
+  self::nullableFunctionContext(c as{TypeError} () →? core::int);
+  self::functionContext(let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:18:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+  functionContext(t); // Error.
+                  ^" in t as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:19:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(t); // Error.
+                          ^" in t as{TypeError,ForNonNullableByDefault} () →? core::int);
+  self::functionContext(let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:20:19: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()'.
+  functionContext(nt); // Error.
+                  ^" in nt as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:21:27: Error: The argument type 'T?' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(nt); // Error.
+                          ^" in nt as{TypeError,ForNonNullableByDefault} () →? core::int);
+}
+static method bar<T extends self::C = self::C>(self::C c, self::bar::T t) → dynamic {
+  self::functionContext(let final self::C #t5 = c in #t5.==(null) ?{() → core::int} null : #t5.{self::C::call});
+  self::nullableFunctionContext(let final self::C #t6 = c in #t6.==(null) ?{() → core::int} null : #t6.{self::C::call});
+  self::functionContext(let final<BottomType> #t7 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:27:19: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()'.
+  functionContext(t); // Shouldn't result in a compile-time error.
+                  ^" in t as{TypeError,ForNonNullableByDefault} () → core::int);
+  self::nullableFunctionContext(let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/tearoff_from_nullable_receiver.dart:28:27: Error: The argument type 'T' can't be assigned to the parameter type 'int Function()?'.
+  nullableFunctionContext(t); // Shouldn't result in a compile-time error.
+                          ^" in t as{TypeError,ForNonNullableByDefault} () →? core::int);
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.outline.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.outline.expect
index 249511a..3181c17 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.outline.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.outline.expect
@@ -13,7 +13,7 @@
   method noSuchMethod(core::Invocation* i) → dynamic
     ;
   no-such-method-forwarder get foo() → core::int*
-    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} core::int*;
+    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set foo(core::int* value) → void
     return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#foo=, 2, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
 }
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.strong.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.strong.expect
index d0abe78..40aaf93 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.strong.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.strong.expect
@@ -15,7 +15,7 @@
   method noSuchMethod(core::Invocation* i) → dynamic
     return "bar";
   no-such-method-forwarder get foo() → core::int*
-    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set foo(core::int* value) → void
     return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.strong.transformed.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.strong.transformed.expect
index d0abe78..40aaf93 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field.dart.strong.transformed.expect
@@ -15,7 +15,7 @@
   method noSuchMethod(core::Invocation* i) → dynamic
     return "bar";
   no-such-method-forwarder get foo() → core::int*
-    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set foo(core::int* value) → void
     return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.outline.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.outline.expect
index d24cfba..f84f93d 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.outline.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.outline.expect
@@ -13,7 +13,7 @@
   method noSuchMethod(core::Invocation* i) → dynamic
     ;
   no-such-method-forwarder get foo() → core::int*
-    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} core::int*;
+    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set foo(core::int* value) → void
     return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#foo=, 2, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
 }
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.strong.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.strong.expect
index e95119b..1f2525d 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.strong.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.strong.expect
@@ -17,7 +17,7 @@
     return null;
   }
   no-such-method-forwarder get foo() → core::int*
-    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set foo(core::int* value) → void
     return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.strong.transformed.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.strong.transformed.expect
index 8e06be7..da816df 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in.dart.strong.transformed.expect
@@ -17,7 +17,7 @@
     return null;
   }
   no-such-method-forwarder get foo() → core::int*
-    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
   no-such-method-forwarder set foo(core::int* value) → void
     return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.outline.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.outline.expect
index d228612..300cb94 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.outline.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.outline.expect
@@ -33,7 +33,7 @@
   synthetic constructor •() → self::E*
     ;
   no-such-method-forwarder get foo() → core::int*
-    return this.{self::D::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} core::int*;
+    return this.{self::D::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} core::int*;
 }
 static method expectTypeError(() →* dynamic callback) → void
   ;
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.strong.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.strong.expect
index 928ca75..b85a18a 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.strong.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.strong.expect
@@ -37,7 +37,7 @@
     : super self::D::•()
     ;
   no-such-method-forwarder get foo() → core::int*
-    return this.{self::D::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{self::D::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
 }
 static method expectTypeError(() →* dynamic callback) → void {
   try {
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.strong.transformed.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.strong.transformed.expect
index 928ca75..b85a18a 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_one_defined.dart.strong.transformed.expect
@@ -37,7 +37,7 @@
     : super self::D::•()
     ;
   no-such-method-forwarder get foo() → core::int*
-    return this.{self::D::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{self::D::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
 }
 static method expectTypeError(() →* dynamic callback) → void {
   try {
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.outline.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.outline.expect
index a96d89a..fc853fa 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.outline.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.outline.expect
@@ -13,7 +13,7 @@
   method noSuchMethod(core::Invocation* i) → dynamic
     ;
   no-such-method-forwarder get foo() → core::List<core::int*>*
-    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} core::List<core::int*>*;
+    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} core::List<core::int*>*;
   no-such-method-forwarder set foo(core::List<core::int*>* value) → void
     return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#foo=, 2, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
 }
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.strong.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.strong.expect
index 2291f79..375d95c 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.strong.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.strong.expect
@@ -15,7 +15,7 @@
   method noSuchMethod(core::Invocation* i) → dynamic
     return <dynamic>[];
   no-such-method-forwarder get foo() → core::List<core::int*>*
-    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::List<core::int*>*;
+    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::List<core::int*>*;
   no-such-method-forwarder set foo(core::List<core::int*>* value) → void
     return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.strong.transformed.expect b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.strong.transformed.expect
index 2291f79..375d95c 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/abstract_accessors_from_field_with_substitution.dart.strong.transformed.expect
@@ -15,7 +15,7 @@
   method noSuchMethod(core::Invocation* i) → dynamic
     return <dynamic>[];
   no-such-method-forwarder get foo() → core::List<core::int*>*
-    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::List<core::int*>*;
+    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 1, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::List<core::int*>*;
   no-such-method-forwarder set foo(core::List<core::int*>* value) → void
     return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C5, 2, #C2, core::List::unmodifiable<dynamic>(<dynamic>[value]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C4)));
 }
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.outline.expect b/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.outline.expect
index 2ad76c7..3adb9f5 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.outline.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.outline.expect
@@ -19,7 +19,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     ;
   no-such-method-forwarder method foo() → dynamic
-    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} dynamic;
+    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} dynamic;
 }
 abstract class _C&A&B = self::A with self::B {
   synthetic constructor •() → self::_C&A&B*
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.strong.expect b/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.strong.expect
index 80a80e1..ad2597a 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.strong.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.strong.expect
@@ -21,7 +21,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     return null;
   no-such-method-forwarder method foo() → dynamic
-    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
 }
 abstract class _C&A&B = self::A with self::B {
   synthetic constructor •() → self::_C&A&B*
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.strong.transformed.expect b/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.strong.transformed.expect
index 29e5abb..23455fe 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/concrete_method_over_forwarder_in_mixin_application.dart.strong.transformed.expect
@@ -21,7 +21,7 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     return null;
   no-such-method-forwarder method foo() → dynamic
-    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} dynamic;
+    return this.{self::B::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} dynamic;
 }
 abstract class _C&A&B extends self::A implements self::B {
   synthetic constructor •() → self::_C&A&B*
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.outline.expect b/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.outline.expect
index 235d557..d3a6abd 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.outline.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.outline.expect
@@ -14,9 +14,9 @@
   synthetic constructor •() → self::B*
     ;
   no-such-method-forwarder method foo({core::String* bar}) → core::String*
-    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#bar: bar}))) as{TypeError} core::String*;
+    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#bar: bar}))) as{TypeError,ForDynamic} core::String*;
   no-such-method-forwarder method hest([core::int* fisk]) → core::int*
-    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#hest, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[fisk]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} core::int*;
+    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#hest, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[fisk]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic
   ;
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.strong.expect b/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.strong.expect
index 860c12b..c1ba2a7 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.strong.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.strong.expect
@@ -24,9 +24,9 @@
     : super self::A::•()
     ;
   no-such-method-forwarder method foo({core::String* bar = #C4}) → core::String*
-    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C6, #C7, core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C2: bar}))) as{TypeError} core::String*;
+    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C6, #C7, core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C2: bar}))) as{TypeError,ForDynamic} core::String*;
   no-such-method-forwarder method hest([core::int* fisk = #C5]) → core::int*
-    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C3, 0, #C6, core::List::unmodifiable<dynamic>(<dynamic>[fisk]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C8))) as{TypeError} core::int*;
+    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C3, 0, #C6, core::List::unmodifiable<dynamic>(<dynamic>[fisk]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C8))) as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {
   self::B* b = new self::B::•();
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.strong.transformed.expect b/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.strong.transformed.expect
index 860c12b..c1ba2a7 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/default_argument_values.dart.strong.transformed.expect
@@ -24,9 +24,9 @@
     : super self::A::•()
     ;
   no-such-method-forwarder method foo({core::String* bar = #C4}) → core::String*
-    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C6, #C7, core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C2: bar}))) as{TypeError} core::String*;
+    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C6, #C7, core::Map::unmodifiable<core::Symbol*, dynamic>(<core::Symbol*, dynamic>{#C2: bar}))) as{TypeError,ForDynamic} core::String*;
   no-such-method-forwarder method hest([core::int* fisk = #C5]) → core::int*
-    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C3, 0, #C6, core::List::unmodifiable<dynamic>(<dynamic>[fisk]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C8))) as{TypeError} core::int*;
+    return this.{self::A::noSuchMethod}(new core::_InvocationMirror::_withType(#C3, 0, #C6, core::List::unmodifiable<dynamic>(<dynamic>[fisk]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C8))) as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {
   self::B* b = new self::B::•();
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.outline.expect b/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.outline.expect
index d332188..6983d47 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.outline.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.outline.expect
@@ -22,7 +22,7 @@
   synthetic constructor •() → self::A*
     ;
   no-such-method-forwarder method foo() → core::int*
-    return this.{self::M::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} core::int*;
+    return this.{self::M::noSuchMethod}(new core::_InvocationMirror::_withType(#foo, 0, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic
   ;
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.strong.expect b/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.strong.expect
index ab2e7eb..64693b8 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.strong.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.strong.expect
@@ -26,7 +26,7 @@
     : super self::_A&Object&M::•()
     ;
   no-such-method-forwarder method foo() → core::int*
-    return this.{self::M::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{self::M::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.strong.transformed.expect b/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.strong.transformed.expect
index daf083f..fe3fabb 100644
--- a/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/no_such_method_forwarders/subst_on_forwarder.dart.strong.transformed.expect
@@ -29,7 +29,7 @@
     : super self::_A&Object&M::•()
     ;
   no-such-method-forwarder method foo() → core::int*
-    return this.{self::M::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError} core::int*;
+    return this.{self::M::noSuchMethod}(new core::_InvocationMirror::_withType(#C1, 0, #C2, #C3, core::Map::unmodifiable<core::Symbol*, dynamic>(#C4))) as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/outline.status b/pkg/front_end/testcases/outline.status
index 9df9418..8875144 100644
--- a/pkg/front_end/testcases/outline.status
+++ b/pkg/front_end/testcases/outline.status
@@ -6,6 +6,7 @@
 general/bug30695: TypeCheckError
 general/bug30695: TypeCheckError
 general/ignore_function: TypeCheckError
+general/invalid_operator: TypeCheckError
 general/mixin_application_override: TypeCheckError
 general/override_check_accessor_after_inference: TypeCheckError
 general/override_check_accessor_basic: TypeCheckError
@@ -14,7 +15,6 @@
 general/override_check_basic: TypeCheckError
 general/override_check_with_covariant_modifier: TypeCheckError
 general/override_setter_with_field: TypeCheckError
-general/with_dependencies/variance_from_dill/variance_from_dill: Crash
 
 general_nnbd_opt_out/abstract_members: TypeCheckError
 general_nnbd_opt_out/bug30695: TypeCheckError
diff --git a/pkg/front_end/testcases/rasta/issue_000004.dart.strong.expect b/pkg/front_end/testcases/rasta/issue_000004.dart.strong.expect
index ee3a0ca..f7d1185 100644
--- a/pkg/front_end/testcases/rasta/issue_000004.dart.strong.expect
+++ b/pkg/front_end/testcases/rasta/issue_000004.dart.strong.expect
@@ -18,7 +18,7 @@
   dynamic n;
   for (final dynamic #t1 in <dynamic>[1, 2, 3, 4, 5]) {
     n = #t1;
-    f = f.{core::num::*}(n as{TypeError} core::num*) as{TypeError} core::int*;
+    f = f.{core::num::*}(n as{TypeError,ForDynamic} core::num*) as{TypeError} core::int*;
   }
   return f;
 }
@@ -26,7 +26,7 @@
   core::int* f = 1;
   for (final dynamic #t2 in <dynamic>[1, 2, 3, 4, 5, 6]) {
     self::global = #t2;
-    f = f.{core::num::*}(self::global as{TypeError} core::num*) as{TypeError} core::int*;
+    f = f.{core::num::*}(self::global as{TypeError,ForDynamic} core::num*) as{TypeError} core::int*;
   }
   return f;
 }
diff --git a/pkg/front_end/testcases/rasta/issue_000004.dart.strong.transformed.expect b/pkg/front_end/testcases/rasta/issue_000004.dart.strong.transformed.expect
index 024a770..b962902 100644
--- a/pkg/front_end/testcases/rasta/issue_000004.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/rasta/issue_000004.dart.strong.transformed.expect
@@ -29,7 +29,7 @@
       final dynamic #t1 = :sync-for-iterator.{core::Iterator::current};
       {
         n = #t1;
-        f = f.{core::num::*}(n as{TypeError} core::num*) as{TypeError} core::int*;
+        f = f.{core::num::*}(n as{TypeError,ForDynamic} core::num*) as{TypeError} core::int*;
       }
     }
   }
@@ -43,7 +43,7 @@
       final dynamic #t2 = :sync-for-iterator.{core::Iterator::current};
       {
         self::global = #t2;
-        f = f.{core::num::*}(self::global as{TypeError} core::num*) as{TypeError} core::int*;
+        f = f.{core::num::*}(self::global as{TypeError,ForDynamic} core::num*) as{TypeError} core::int*;
       }
     }
   }
diff --git a/pkg/front_end/testcases/rasta/issue_000044.dart.strong.expect b/pkg/front_end/testcases/rasta/issue_000044.dart.strong.expect
index c501ddc..9c3fa75 100644
--- a/pkg/front_end/testcases/rasta/issue_000044.dart.strong.expect
+++ b/pkg/front_end/testcases/rasta/issue_000044.dart.strong.expect
@@ -80,12 +80,12 @@
  - 'C' is from 'pkg/front_end/testcases/rasta/issue_000044.dart'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'h'.
   C notEvenAConstructor(a) = h;
-                             ^" as{TypeError} self::C*;
+                             ^" as{TypeError,ForDynamic} self::C*;
 }
 static method b(dynamic c) → invalid-type
   return invalid-expression "pkg/front_end/testcases/rasta/issue_000044.dart:7:10: Error: Getter not found: 'd'.
 a b(c) = d;
-         ^" as{TypeError} invalid-type;
+         ^" as{TypeError,ForDynamic} invalid-type;
 static method main() → dynamic {
   self::C* c = null;
   core::print(#C1);
diff --git a/pkg/front_end/testcases/rasta/issue_000044.dart.strong.transformed.expect b/pkg/front_end/testcases/rasta/issue_000044.dart.strong.transformed.expect
index 54451d2..e576061 100644
--- a/pkg/front_end/testcases/rasta/issue_000044.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/rasta/issue_000044.dart.strong.transformed.expect
@@ -80,12 +80,12 @@
  - 'C' is from 'pkg/front_end/testcases/rasta/issue_000044.dart'.
 Try correcting the name to the name of an existing getter, or defining a getter or field named 'h'.
   C notEvenAConstructor(a) = h;
-                             ^" as{TypeError} self::C*;
+                             ^" as{TypeError,ForDynamic} self::C*;
 }
 static method b(dynamic c) → invalid-type
   return invalid-expression "pkg/front_end/testcases/rasta/issue_000044.dart:7:10: Error: Getter not found: 'd'.
 a b(c) = d;
-         ^" as{TypeError} invalid-type;
+         ^" as{TypeError,ForDynamic} invalid-type;
 static method main() → dynamic {
   self::C* c = null;
   core::print(#C1);
diff --git a/pkg/front_end/testcases/rasta/parser_error.dart.strong.expect b/pkg/front_end/testcases/rasta/parser_error.dart.strong.expect
index d620e90..13f78fd 100644
--- a/pkg/front_end/testcases/rasta/parser_error.dart.strong.expect
+++ b/pkg/front_end/testcases/rasta/parser_error.dart.strong.expect
@@ -23,11 +23,11 @@
 static method test(dynamic a, {dynamic b = #C1, dynamic c = #C1}) → core::int* {
   if((invalid-expression "pkg/front_end/testcases/rasta/parser_error.dart:10:7: Error: This couldn't be parsed.
   if (?b) return b;  /// 01: compile-time error
-      ^" as{TypeError} core::bool* ?{dynamic} b : invalid-expression "pkg/front_end/testcases/rasta/parser_error.dart:10:9: Error: This couldn't be parsed.
+      ^" as{TypeError,ForDynamic} core::bool* ?{dynamic} b : invalid-expression "pkg/front_end/testcases/rasta/parser_error.dart:10:9: Error: This couldn't be parsed.
   if (?b) return b;  /// 01: compile-time error
-        ^") as{TypeError} core::bool*)
-    return b as{TypeError} core::int*;
-  return a.+(b).+(c) as{TypeError} core::int*;
+        ^") as{TypeError,ForDynamic} core::bool*)
+    return b as{TypeError,ForDynamic} core::int*;
+  return a.+(b).+(c) as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {
   exp::Expect::equals(6, self::test(1, b: 2, c: 3));
diff --git a/pkg/front_end/testcases/rasta/parser_error.dart.strong.transformed.expect b/pkg/front_end/testcases/rasta/parser_error.dart.strong.transformed.expect
index d620e90..13f78fd 100644
--- a/pkg/front_end/testcases/rasta/parser_error.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/rasta/parser_error.dart.strong.transformed.expect
@@ -23,11 +23,11 @@
 static method test(dynamic a, {dynamic b = #C1, dynamic c = #C1}) → core::int* {
   if((invalid-expression "pkg/front_end/testcases/rasta/parser_error.dart:10:7: Error: This couldn't be parsed.
   if (?b) return b;  /// 01: compile-time error
-      ^" as{TypeError} core::bool* ?{dynamic} b : invalid-expression "pkg/front_end/testcases/rasta/parser_error.dart:10:9: Error: This couldn't be parsed.
+      ^" as{TypeError,ForDynamic} core::bool* ?{dynamic} b : invalid-expression "pkg/front_end/testcases/rasta/parser_error.dart:10:9: Error: This couldn't be parsed.
   if (?b) return b;  /// 01: compile-time error
-        ^") as{TypeError} core::bool*)
-    return b as{TypeError} core::int*;
-  return a.+(b).+(c) as{TypeError} core::int*;
+        ^") as{TypeError,ForDynamic} core::bool*)
+    return b as{TypeError,ForDynamic} core::int*;
+  return a.+(b).+(c) as{TypeError,ForDynamic} core::int*;
 }
 static method main() → dynamic {
   exp::Expect::equals(6, self::test(1, b: 2, c: 3));
diff --git a/pkg/front_end/testcases/rasta/unresolved_for_in.dart.strong.expect b/pkg/front_end/testcases/rasta/unresolved_for_in.dart.strong.expect
index c41f760..4b6f9c8 100644
--- a/pkg/front_end/testcases/rasta/unresolved_for_in.dart.strong.expect
+++ b/pkg/front_end/testcases/rasta/unresolved_for_in.dart.strong.expect
@@ -91,7 +91,7 @@
     : super core::Object::•()
     ;
   method it1(dynamic x) → dynamic {
-    for (final dynamic #t1 in x as{TypeError} core::Iterable<dynamic>*) {
+    for (final dynamic #t1 in x as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
       invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:11:10: Error: The setter 'key' isn't defined for the class 'Fisk'.
  - 'Fisk' is from 'pkg/front_end/testcases/rasta/unresolved_for_in.dart'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'key'.
@@ -103,13 +103,13 @@
       print(key);
             ^^^");
     }
-    for (final dynamic #t2 in x as{TypeError} core::Iterable<dynamic>*) {
+    for (final dynamic #t2 in x as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
       invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:14:10: Error: Setter not found: 'Fisk'.
     for (Fisk in x) {
          ^^^^";
       core::print(self::Fisk*);
     }
-    for (final dynamic #t3 in x as{TypeError} core::Iterable<dynamic>*) {
+    for (final dynamic #t3 in x as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
       invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:17:10: Error: A prefix can't be used as an expression.
     for (collection in x) {
          ^^^^^^^^^^";
@@ -117,7 +117,7 @@
       print(collection);
             ^^^^^^^^^^");
     }
-    for (final dynamic #t4 in x as{TypeError} core::Iterable<dynamic>*) {
+    for (final dynamic #t4 in x as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
       invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:20:10: Error: Setter not found: 'VoidFunction'.
     for (VoidFunction in x) {
          ^^^^^^^^^^^^";
@@ -127,7 +127,7 @@
       invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:23:10: Error: Can't assign to this, so it can't be used in a for-in loop.
     for (1 in x) {
          ^";
-      for (final dynamic #t5 in x as{TypeError} core::Iterable<dynamic>*) {
+      for (final dynamic #t5 in x as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
         invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:23:10: Error: Can't assign to this, so it can't be used in a for-in loop.
     for (1 in x) {
          ^";
@@ -143,7 +143,7 @@
 }
 static method main(dynamic arguments) → dynamic {
   new self::Fisk::•();
-  for (final dynamic #t6 in arguments as{TypeError} core::Iterable<dynamic>*) {
+  for (final dynamic #t6 in arguments as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
     invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:31:8: Error: Setter not found: 'key'.
   for (key in arguments) {
        ^^^";
@@ -151,13 +151,13 @@
     print(key);
           ^^^");
   }
-  for (final dynamic #t7 in arguments as{TypeError} core::Iterable<dynamic>*) {
+  for (final dynamic #t7 in arguments as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
     invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:34:8: Error: Setter not found: 'Fisk'.
   for (Fisk in arguments) {
        ^^^^";
     core::print(self::Fisk*);
   }
-  for (final dynamic #t8 in arguments as{TypeError} core::Iterable<dynamic>*) {
+  for (final dynamic #t8 in arguments as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
     invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:37:8: Error: A prefix can't be used as an expression.
   for (collection in arguments) {
        ^^^^^^^^^^";
@@ -165,7 +165,7 @@
     print(collection);
           ^^^^^^^^^^");
   }
-  for (final dynamic #t9 in arguments as{TypeError} core::Iterable<dynamic>*) {
+  for (final dynamic #t9 in arguments as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
     invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:40:8: Error: Setter not found: 'VoidFunction'.
   for (VoidFunction in arguments) {
        ^^^^^^^^^^^^";
@@ -175,7 +175,7 @@
     invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:43:8: Error: Can't assign to this, so it can't be used in a for-in loop.
   for (1 in arguments) {
        ^";
-    for (final dynamic #t10 in arguments as{TypeError} core::Iterable<dynamic>*) {
+    for (final dynamic #t10 in arguments as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
       invalid-expression "pkg/front_end/testcases/rasta/unresolved_for_in.dart:43:8: Error: Can't assign to this, so it can't be used in a for-in loop.
   for (1 in arguments) {
        ^";
diff --git a/pkg/front_end/testcases/rasta/unresolved_for_in.dart.strong.transformed.expect b/pkg/front_end/testcases/rasta/unresolved_for_in.dart.strong.transformed.expect
index e5f407f..1cc912e 100644
--- a/pkg/front_end/testcases/rasta/unresolved_for_in.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/rasta/unresolved_for_in.dart.strong.transformed.expect
@@ -93,7 +93,7 @@
     ;
   method it1(dynamic x) → dynamic {
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(x as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(x as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t1 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -111,7 +111,7 @@
       }
     }
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(x as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(x as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t2 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -123,7 +123,7 @@
       }
     }
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(x as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(x as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t3 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -137,7 +137,7 @@
       }
     }
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(x as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(x as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t4 = :sync-for-iterator.{core::Iterator::current};
         {
@@ -153,7 +153,7 @@
     for (1 in x) {
          ^";
       {
-        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(x as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+        core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(x as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
         for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
           final dynamic #t5 = :sync-for-iterator.{core::Iterator::current};
           {
@@ -175,7 +175,7 @@
 static method main(dynamic arguments) → dynamic {
   new self::Fisk::•();
   {
-    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(arguments as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(arguments as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t6 = :sync-for-iterator.{core::Iterator::current};
       {
@@ -189,7 +189,7 @@
     }
   }
   {
-    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(arguments as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(arguments as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t7 = :sync-for-iterator.{core::Iterator::current};
       {
@@ -201,7 +201,7 @@
     }
   }
   {
-    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(arguments as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(arguments as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t8 = :sync-for-iterator.{core::Iterator::current};
       {
@@ -215,7 +215,7 @@
     }
   }
   {
-    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(arguments as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+    core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(arguments as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
     for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
       final dynamic #t9 = :sync-for-iterator.{core::Iterator::current};
       {
@@ -231,7 +231,7 @@
   for (1 in arguments) {
        ^";
     {
-      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(arguments as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+      core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>(arguments as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
       for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
         final dynamic #t10 = :sync-for-iterator.{core::Iterator::current};
         {
diff --git a/pkg/front_end/testcases/regress/issue_29984.dart.strong.expect b/pkg/front_end/testcases/regress/issue_29984.dart.strong.expect
index 4b691f5..7ababc1 100644
--- a/pkg/front_end/testcases/regress/issue_29984.dart.strong.expect
+++ b/pkg/front_end/testcases/regress/issue_29984.dart.strong.expect
@@ -21,7 +21,7 @@
   for (int i = i;; false) {}
            ^" in invalid-expression "pkg/front_end/testcases/regress/issue_29984.dart:6:16: Error: Getter not found: 'i'.
   for (int i = i;; false) {}
-               ^") as{TypeError} core::int*; ; false) {
+               ^") as{TypeError,ForDynamic} core::int*; ; false) {
   }
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/regress/issue_29984.dart.strong.transformed.expect b/pkg/front_end/testcases/regress/issue_29984.dart.strong.transformed.expect
index 4b691f5..7ababc1 100644
--- a/pkg/front_end/testcases/regress/issue_29984.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/regress/issue_29984.dart.strong.transformed.expect
@@ -21,7 +21,7 @@
   for (int i = i;; false) {}
            ^" in invalid-expression "pkg/front_end/testcases/regress/issue_29984.dart:6:16: Error: Getter not found: 'i'.
   for (int i = i;; false) {}
-               ^") as{TypeError} core::int*; ; false) {
+               ^") as{TypeError,ForDynamic} core::int*; ; false) {
   }
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/regress/issue_31184.dart.strong.expect b/pkg/front_end/testcases/regress/issue_31184.dart.strong.expect
index ffc6739..ed5c611 100644
--- a/pkg/front_end/testcases/regress/issue_31184.dart.strong.expect
+++ b/pkg/front_end/testcases/regress/issue_31184.dart.strong.expect
@@ -23,9 +23,9 @@
 static method bad() → dynamic {
   for (core::int* i = 0, core::int* i = invalid-expression "pkg/front_end/testcases/regress/issue_31184.dart:6:19: Error: 'i' is already declared in this scope.
   for (int i = 0, i > 10; i++) {}
-                  ^" as{TypeError} core::int*; invalid-expression "pkg/front_end/testcases/regress/issue_31184.dart:6:21: Error: This couldn't be parsed.
+                  ^" as{TypeError,ForDynamic} core::int*; invalid-expression "pkg/front_end/testcases/regress/issue_31184.dart:6:21: Error: This couldn't be parsed.
   for (int i = 0, i > 10; i++) {}
-                    ^".>(10) as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+                    ^".>(10) as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
   }
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/regress/issue_31184.dart.strong.transformed.expect b/pkg/front_end/testcases/regress/issue_31184.dart.strong.transformed.expect
index ffc6739..ed5c611 100644
--- a/pkg/front_end/testcases/regress/issue_31184.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/regress/issue_31184.dart.strong.transformed.expect
@@ -23,9 +23,9 @@
 static method bad() → dynamic {
   for (core::int* i = 0, core::int* i = invalid-expression "pkg/front_end/testcases/regress/issue_31184.dart:6:19: Error: 'i' is already declared in this scope.
   for (int i = 0, i > 10; i++) {}
-                  ^" as{TypeError} core::int*; invalid-expression "pkg/front_end/testcases/regress/issue_31184.dart:6:21: Error: This couldn't be parsed.
+                  ^" as{TypeError,ForDynamic} core::int*; invalid-expression "pkg/front_end/testcases/regress/issue_31184.dart:6:21: Error: This couldn't be parsed.
   for (int i = 0, i > 10; i++) {}
-                    ^".>(10) as{TypeError} core::bool*; i = i.{core::num::+}(1)) {
+                    ^".>(10) as{TypeError,ForDynamic} core::bool*; i = i.{core::num::+}(1)) {
   }
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/regress/issue_31185.dart.strong.expect b/pkg/front_end/testcases/regress/issue_31185.dart.strong.expect
index 4723bc6..b100603 100644
--- a/pkg/front_end/testcases/regress/issue_31185.dart.strong.expect
+++ b/pkg/front_end/testcases/regress/issue_31185.dart.strong.expect
@@ -25,7 +25,7 @@
 static method test2() → core::int* {
   return invalid-expression "pkg/front_end/testcases/regress/issue_31185.dart:12:12: Error: Can't assign to a parenthesized expression.
   return (i) ++ (i);
-           ^" as{TypeError} core::int*;
+           ^" as{TypeError,ForDynamic} core::int*;
   self::i;
 }
 static method main() → dynamic {
diff --git a/pkg/front_end/testcases/regress/issue_31185.dart.strong.transformed.expect b/pkg/front_end/testcases/regress/issue_31185.dart.strong.transformed.expect
index 4723bc6..b100603 100644
--- a/pkg/front_end/testcases/regress/issue_31185.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/regress/issue_31185.dart.strong.transformed.expect
@@ -25,7 +25,7 @@
 static method test2() → core::int* {
   return invalid-expression "pkg/front_end/testcases/regress/issue_31185.dart:12:12: Error: Can't assign to a parenthesized expression.
   return (i) ++ (i);
-           ^" as{TypeError} core::int*;
+           ^" as{TypeError,ForDynamic} core::int*;
   self::i;
 }
 static method main() → dynamic {
diff --git a/pkg/front_end/testcases/regress/issue_31188.dart.strong.expect b/pkg/front_end/testcases/regress/issue_31188.dart.strong.expect
index 57ea785..5874008 100644
--- a/pkg/front_end/testcases/regress/issue_31188.dart.strong.expect
+++ b/pkg/front_end/testcases/regress/issue_31188.dart.strong.expect
@@ -34,6 +34,6 @@
  - 'Type' is from 'dart:core'.
 Try correcting the name to the name of an existing method, or defining a method named '<'.
 type T = Map<A, B>
-            ^" as{TypeError} invalid-type;
+            ^" as{TypeError,ForDynamic} invalid-type;
 static field invalid-type B;
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/regress/issue_31188.dart.strong.transformed.expect b/pkg/front_end/testcases/regress/issue_31188.dart.strong.transformed.expect
index 57ea785..5874008 100644
--- a/pkg/front_end/testcases/regress/issue_31188.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/regress/issue_31188.dart.strong.transformed.expect
@@ -34,6 +34,6 @@
  - 'Type' is from 'dart:core'.
 Try correcting the name to the name of an existing method, or defining a method named '<'.
 type T = Map<A, B>
-            ^" as{TypeError} invalid-type;
+            ^" as{TypeError,ForDynamic} invalid-type;
 static field invalid-type B;
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/regress/issue_35260.dart.strong.expect b/pkg/front_end/testcases/regress/issue_35260.dart.strong.expect
index d7c940a..555c1a6 100644
--- a/pkg/front_end/testcases/regress/issue_35260.dart.strong.expect
+++ b/pkg/front_end/testcases/regress/issue_35260.dart.strong.expect
@@ -29,5 +29,5 @@
 static method main() → dynamic {
   self::X* x = invalid-expression "pkg/front_end/testcases/regress/issue_35260.dart:15:13: Error: Can't use 'Supertype' because it is declared more than once.
   X x = new Supertype();
-            ^" as{TypeError} self::X*;
+            ^" as{TypeError,ForDynamic} self::X*;
 }
diff --git a/pkg/front_end/testcases/regress/issue_35260.dart.strong.transformed.expect b/pkg/front_end/testcases/regress/issue_35260.dart.strong.transformed.expect
index a5bb9cf..a6de672 100644
--- a/pkg/front_end/testcases/regress/issue_35260.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/regress/issue_35260.dart.strong.transformed.expect
@@ -29,5 +29,5 @@
 static method main() → dynamic {
   self::X* x = invalid-expression "pkg/front_end/testcases/regress/issue_35260.dart:15:13: Error: Can't use 'Supertype' because it is declared more than once.
   X x = new Supertype();
-            ^" as{TypeError} self::X*;
+            ^" as{TypeError,ForDynamic} self::X*;
 }
diff --git a/pkg/front_end/testcases/regress/issue_37681.dart.strong.expect b/pkg/front_end/testcases/regress/issue_37681.dart.strong.expect
index 3166bc2..0ea7212 100644
--- a/pkg/front_end/testcases/regress/issue_37681.dart.strong.expect
+++ b/pkg/front_end/testcases/regress/issue_37681.dart.strong.expect
@@ -26,13 +26,13 @@
   function f_async_star() → core::int* async* {
     yield 42;
   }
-  await for (dynamic x in (f_async_star.call() as dynamic) as{TypeError} asy::Stream<dynamic>*) {
+  await for (dynamic x in (f_async_star.call() as dynamic) as{TypeError,ForDynamic} asy::Stream<dynamic>*) {
     core::print(x);
   }
   function f_sync_star() → core::int* sync* {
     yield 42;
   }
-  for (dynamic x in (f_sync_star.call() as dynamic) as{TypeError} core::Iterable<dynamic>*) {
+  for (dynamic x in (f_sync_star.call() as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*) {
     core::print(x);
   }
 }
diff --git a/pkg/front_end/testcases/regress/issue_37681.dart.strong.transformed.expect b/pkg/front_end/testcases/regress/issue_37681.dart.strong.transformed.expect
index 12c970e..79ba707 100644
--- a/pkg/front_end/testcases/regress/issue_37681.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/regress/issue_37681.dart.strong.transformed.expect
@@ -100,7 +100,7 @@
           return :controller_stream;
         }
         {
-          dynamic :stream = (f_async_star.call() as dynamic) as{TypeError} asy::Stream<dynamic>*;
+          dynamic :stream = (f_async_star.call() as dynamic) as{TypeError,ForDynamic} asy::Stream<dynamic>*;
           asy::_asyncStarListenHelper(:stream, :async_op);
           asy::_StreamIterator<dynamic>* :for-iterator = new asy::_StreamIterator::•<dynamic>(:stream);
           try
@@ -138,7 +138,7 @@
           return new core::_SyncIterable::•<dynamic>(:sync_op);
         }
         {
-          core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((f_sync_star.call() as dynamic) as{TypeError} core::Iterable<dynamic>*).{core::Iterable::iterator};
+          core::Iterator<dynamic>* :sync-for-iterator = _in::unsafeCast<core::Iterable<dynamic>*>((f_sync_star.call() as dynamic) as{TypeError,ForDynamic} core::Iterable<dynamic>*).{core::Iterable::iterator};
           for (; :sync-for-iterator.{core::Iterator::moveNext}(); ) {
             dynamic x = :sync-for-iterator.{core::Iterator::current};
             {
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_field.dart.strong.expect b/pkg/front_end/testcases/runtime_checks/contravariant_field.dart.strong.expect
index af9bd50..a71b9df 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_field.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_field.dart.strong.expect
@@ -13,6 +13,6 @@
   }
 }
 static method g(self::C<core::num*>* c) → void {
-  (core::num*) →* void x = c.{self::C::y} as{TypeError} (core::num*) →* void;
+  (core::num*) →* void x = c.{self::C::y} as{TypeError,CovarianceCheck} (core::num*) →* void;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_field.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks/contravariant_field.dart.strong.transformed.expect
index af9bd50..a71b9df 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_field.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_field.dart.strong.transformed.expect
@@ -13,6 +13,6 @@
   }
 }
 static method g(self::C<core::num*>* c) → void {
-  (core::num*) →* void x = c.{self::C::y} as{TypeError} (core::num*) →* void;
+  (core::num*) →* void x = c.{self::C::y} as{TypeError,CovarianceCheck} (core::num*) →* void;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return.dart.strong.expect b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return.dart.strong.expect
index 81ef72b..c3985a6 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return.dart.strong.expect
@@ -13,15 +13,15 @@
   }
 }
 static method g1(self::C<core::num*>* c) → void {
-  (core::num*) →* void x = c.{self::C::f1}() as{TypeError} (core::num*) →* void;
+  (core::num*) →* void x = c.{self::C::f1}() as{TypeError,CovarianceCheck} (core::num*) →* void;
   core::print("hello");
   x.call(1.5);
 }
 static method g2(self::C<core::num*>* c) → void {
-  (core::int*) →* void x = c.{self::C::f1}() as{TypeError} (core::num*) →* void;
+  (core::int*) →* void x = c.{self::C::f1}() as{TypeError,CovarianceCheck} (core::num*) →* void;
   x.call(1);
 }
 static method g3(self::C<core::num*>* c) → void {
-  core::List<(core::num*) →* void>* x = c.{self::C::f2}() as{TypeError} core::List<(core::num*) →* void>*;
+  core::List<(core::num*) →* void>* x = c.{self::C::f2}() as{TypeError,CovarianceCheck} core::List<(core::num*) →* void>*;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return.dart.strong.transformed.expect
index 81ef72b..c3985a6 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return.dart.strong.transformed.expect
@@ -13,15 +13,15 @@
   }
 }
 static method g1(self::C<core::num*>* c) → void {
-  (core::num*) →* void x = c.{self::C::f1}() as{TypeError} (core::num*) →* void;
+  (core::num*) →* void x = c.{self::C::f1}() as{TypeError,CovarianceCheck} (core::num*) →* void;
   core::print("hello");
   x.call(1.5);
 }
 static method g2(self::C<core::num*>* c) → void {
-  (core::int*) →* void x = c.{self::C::f1}() as{TypeError} (core::num*) →* void;
+  (core::int*) →* void x = c.{self::C::f1}() as{TypeError,CovarianceCheck} (core::num*) →* void;
   x.call(1);
 }
 static method g3(self::C<core::num*>* c) → void {
-  core::List<(core::num*) →* void>* x = c.{self::C::f2}() as{TypeError} core::List<(core::num*) →* void>*;
+  core::List<(core::num*) →* void>* x = c.{self::C::f2}() as{TypeError,CovarianceCheck} core::List<(core::num*) →* void>*;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_null_aware.dart.strong.expect b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_null_aware.dart.strong.expect
index 75a8771..55f630b 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_null_aware.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_null_aware.dart.strong.expect
@@ -13,15 +13,15 @@
   }
 }
 static method g1(self::C<core::num*>* c) → void {
-  (core::num*) →* void x = let final self::C<core::num*>* #t1 = c in #t1.{core::Object::==}(null) ?{(core::num*) →* void} null : #t1.{self::C::f1}() as{TypeError} (core::num*) →* void;
+  (core::num*) →* void x = let final self::C<core::num*>* #t1 = c in #t1.{core::Object::==}(null) ?{(core::num*) →* void} null : #t1.{self::C::f1}() as{TypeError,CovarianceCheck} (core::num*) →* void;
   core::print("hello");
   x.call(1.5);
 }
 static method g2(self::C<core::num*>* c) → void {
-  (core::int*) →* void x = let final self::C<core::num*>* #t2 = c in #t2.{core::Object::==}(null) ?{(core::num*) →* void} null : #t2.{self::C::f1}() as{TypeError} (core::num*) →* void;
+  (core::int*) →* void x = let final self::C<core::num*>* #t2 = c in #t2.{core::Object::==}(null) ?{(core::num*) →* void} null : #t2.{self::C::f1}() as{TypeError,CovarianceCheck} (core::num*) →* void;
   x.call(1);
 }
 static method g3(self::C<core::num*>* c) → void {
-  core::List<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in #t3.{core::Object::==}(null) ?{core::List<(core::num*) →* void>*} null : #t3.{self::C::f2}() as{TypeError} core::List<(core::num*) →* void>*;
+  core::List<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in #t3.{core::Object::==}(null) ?{core::List<(core::num*) →* void>*} null : #t3.{self::C::f2}() as{TypeError,CovarianceCheck} core::List<(core::num*) →* void>*;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_null_aware.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_null_aware.dart.strong.transformed.expect
index 75a8771..55f630b 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_null_aware.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_null_aware.dart.strong.transformed.expect
@@ -13,15 +13,15 @@
   }
 }
 static method g1(self::C<core::num*>* c) → void {
-  (core::num*) →* void x = let final self::C<core::num*>* #t1 = c in #t1.{core::Object::==}(null) ?{(core::num*) →* void} null : #t1.{self::C::f1}() as{TypeError} (core::num*) →* void;
+  (core::num*) →* void x = let final self::C<core::num*>* #t1 = c in #t1.{core::Object::==}(null) ?{(core::num*) →* void} null : #t1.{self::C::f1}() as{TypeError,CovarianceCheck} (core::num*) →* void;
   core::print("hello");
   x.call(1.5);
 }
 static method g2(self::C<core::num*>* c) → void {
-  (core::int*) →* void x = let final self::C<core::num*>* #t2 = c in #t2.{core::Object::==}(null) ?{(core::num*) →* void} null : #t2.{self::C::f1}() as{TypeError} (core::num*) →* void;
+  (core::int*) →* void x = let final self::C<core::num*>* #t2 = c in #t2.{core::Object::==}(null) ?{(core::num*) →* void} null : #t2.{self::C::f1}() as{TypeError,CovarianceCheck} (core::num*) →* void;
   x.call(1);
 }
 static method g3(self::C<core::num*>* c) → void {
-  core::List<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in #t3.{core::Object::==}(null) ?{core::List<(core::num*) →* void>*} null : #t3.{self::C::f2}() as{TypeError} core::List<(core::num*) →* void>*;
+  core::List<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in #t3.{core::Object::==}(null) ?{core::List<(core::num*) →* void>*} null : #t3.{self::C::f2}() as{TypeError,CovarianceCheck} core::List<(core::num*) →* void>*;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_tear_off.dart.strong.expect b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_tear_off.dart.strong.expect
index c0b0076..cbf825e 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_tear_off.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_tear_off.dart.strong.expect
@@ -13,7 +13,7 @@
     return this.{self::C::_x};
 }
 static method g(self::C<core::num*>* c) → () →* (core::num*) →* void {
-  return c.{self::C::f} as{TypeError} () →* (core::num*) →* void;
+  return c.{self::C::f} as{TypeError,CovarianceCheck} () →* (core::num*) →* void;
 }
 static method h(core::int* i) → void {
   core::print("${i}");
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_tear_off.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_tear_off.dart.strong.transformed.expect
index c0b0076..cbf825e 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_tear_off.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_generic_return_tear_off.dart.strong.transformed.expect
@@ -13,7 +13,7 @@
     return this.{self::C::_x};
 }
 static method g(self::C<core::num*>* c) → () →* (core::num*) →* void {
-  return c.{self::C::f} as{TypeError} () →* (core::num*) →* void;
+  return c.{self::C::f} as{TypeError,CovarianceCheck} () →* (core::num*) →* void;
 }
 static method h(core::int* i) → void {
   core::print("${i}");
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_getter.dart.strong.expect b/pkg/front_end/testcases/runtime_checks/contravariant_getter.dart.strong.expect
index 4fe5da3..6014e7af 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_getter.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_getter.dart.strong.expect
@@ -13,6 +13,6 @@
   }
 }
 static method g(self::C<core::num*>* c) → void {
-  (c.{self::C::y} as{TypeError} (core::num*) →* void).call(1.5);
+  (c.{self::C::y} as{TypeError,CovarianceCheck} (core::num*) →* void).call(1.5);
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_getter.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks/contravariant_getter.dart.strong.transformed.expect
index 4fe5da3..6014e7af 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_getter.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_getter.dart.strong.transformed.expect
@@ -13,6 +13,6 @@
   }
 }
 static method g(self::C<core::num*>* c) → void {
-  (c.{self::C::y} as{TypeError} (core::num*) →* void).call(1.5);
+  (c.{self::C::y} as{TypeError,CovarianceCheck} (core::num*) →* void).call(1.5);
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_getter_return.dart.strong.expect b/pkg/front_end/testcases/runtime_checks/contravariant_getter_return.dart.strong.expect
index 30b8696..77f902d 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_getter_return.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_getter_return.dart.strong.expect
@@ -14,15 +14,15 @@
   }
 }
 static method g1(self::C<core::num*>* c) → void {
-  (core::num*) →* void x = c.{self::C::f1} as{TypeError} (core::num*) →* void;
+  (core::num*) →* void x = c.{self::C::f1} as{TypeError,CovarianceCheck} (core::num*) →* void;
   core::print("hello");
   x.call(1.5);
 }
 static method g2(self::C<core::num*>* c) → void {
-  (core::int*) →* void x = c.{self::C::f1} as{TypeError} (core::num*) →* void;
+  (core::int*) →* void x = c.{self::C::f1} as{TypeError,CovarianceCheck} (core::num*) →* void;
   x.call(1);
 }
 static method g3(self::C<core::num*>* c) → void {
-  core::List<(core::num*) →* void>* x = c.{self::C::f2} as{TypeError} core::List<(core::num*) →* void>*;
+  core::List<(core::num*) →* void>* x = c.{self::C::f2} as{TypeError,CovarianceCheck} core::List<(core::num*) →* void>*;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_getter_return.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks/contravariant_getter_return.dart.strong.transformed.expect
index 30b8696..77f902d 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_getter_return.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_getter_return.dart.strong.transformed.expect
@@ -14,15 +14,15 @@
   }
 }
 static method g1(self::C<core::num*>* c) → void {
-  (core::num*) →* void x = c.{self::C::f1} as{TypeError} (core::num*) →* void;
+  (core::num*) →* void x = c.{self::C::f1} as{TypeError,CovarianceCheck} (core::num*) →* void;
   core::print("hello");
   x.call(1.5);
 }
 static method g2(self::C<core::num*>* c) → void {
-  (core::int*) →* void x = c.{self::C::f1} as{TypeError} (core::num*) →* void;
+  (core::int*) →* void x = c.{self::C::f1} as{TypeError,CovarianceCheck} (core::num*) →* void;
   x.call(1);
 }
 static method g3(self::C<core::num*>* c) → void {
-  core::List<(core::num*) →* void>* x = c.{self::C::f2} as{TypeError} core::List<(core::num*) →* void>*;
+  core::List<(core::num*) →* void>* x = c.{self::C::f2} as{TypeError,CovarianceCheck} core::List<(core::num*) →* void>*;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_getter_return_null_aware.dart.strong.expect b/pkg/front_end/testcases/runtime_checks/contravariant_getter_return_null_aware.dart.strong.expect
index 2e4bee0..974091e 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_getter_return_null_aware.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_getter_return_null_aware.dart.strong.expect
@@ -14,15 +14,15 @@
   }
 }
 static method g1(self::C<core::num*>* c) → void {
-  (core::num*) →* void x = let final self::C<core::num*>* #t1 = c in #t1.{core::Object::==}(null) ?{(core::num*) →* void} null : #t1.{self::C::f1} as{TypeError} (core::num*) →* void;
+  (core::num*) →* void x = let final self::C<core::num*>* #t1 = c in #t1.{core::Object::==}(null) ?{(core::num*) →* void} null : #t1.{self::C::f1} as{TypeError,CovarianceCheck} (core::num*) →* void;
   core::print("hello");
   x.call(1.5);
 }
 static method g2(self::C<core::num*>* c) → void {
-  (core::int*) →* void x = let final self::C<core::num*>* #t2 = c in #t2.{core::Object::==}(null) ?{(core::num*) →* void} null : #t2.{self::C::f1} as{TypeError} (core::num*) →* void;
+  (core::int*) →* void x = let final self::C<core::num*>* #t2 = c in #t2.{core::Object::==}(null) ?{(core::num*) →* void} null : #t2.{self::C::f1} as{TypeError,CovarianceCheck} (core::num*) →* void;
   x.call(1);
 }
 static method g3(self::C<core::num*>* c) → void {
-  core::List<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in #t3.{core::Object::==}(null) ?{core::List<(core::num*) →* void>*} null : #t3.{self::C::f2} as{TypeError} core::List<(core::num*) →* void>*;
+  core::List<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in #t3.{core::Object::==}(null) ?{core::List<(core::num*) →* void>*} null : #t3.{self::C::f2} as{TypeError,CovarianceCheck} core::List<(core::num*) →* void>*;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks/contravariant_getter_return_null_aware.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks/contravariant_getter_return_null_aware.dart.strong.transformed.expect
index 2e4bee0..974091e 100644
--- a/pkg/front_end/testcases/runtime_checks/contravariant_getter_return_null_aware.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks/contravariant_getter_return_null_aware.dart.strong.transformed.expect
@@ -14,15 +14,15 @@
   }
 }
 static method g1(self::C<core::num*>* c) → void {
-  (core::num*) →* void x = let final self::C<core::num*>* #t1 = c in #t1.{core::Object::==}(null) ?{(core::num*) →* void} null : #t1.{self::C::f1} as{TypeError} (core::num*) →* void;
+  (core::num*) →* void x = let final self::C<core::num*>* #t1 = c in #t1.{core::Object::==}(null) ?{(core::num*) →* void} null : #t1.{self::C::f1} as{TypeError,CovarianceCheck} (core::num*) →* void;
   core::print("hello");
   x.call(1.5);
 }
 static method g2(self::C<core::num*>* c) → void {
-  (core::int*) →* void x = let final self::C<core::num*>* #t2 = c in #t2.{core::Object::==}(null) ?{(core::num*) →* void} null : #t2.{self::C::f1} as{TypeError} (core::num*) →* void;
+  (core::int*) →* void x = let final self::C<core::num*>* #t2 = c in #t2.{core::Object::==}(null) ?{(core::num*) →* void} null : #t2.{self::C::f1} as{TypeError,CovarianceCheck} (core::num*) →* void;
   x.call(1);
 }
 static method g3(self::C<core::num*>* c) → void {
-  core::List<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in #t3.{core::Object::==}(null) ?{core::List<(core::num*) →* void>*} null : #t3.{self::C::f2} as{TypeError} core::List<(core::num*) →* void>*;
+  core::List<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in #t3.{core::Object::==}(null) ?{core::List<(core::num*) →* void>*} null : #t3.{self::C::f2} as{TypeError,CovarianceCheck} core::List<(core::num*) →* void>*;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks_new/call_through_this.dart.strong.expect b/pkg/front_end/testcases/runtime_checks_new/call_through_this.dart.strong.expect
index 023e6058..61cd6f8e1 100644
--- a/pkg/front_end/testcases/runtime_checks_new/call_through_this.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/call_through_this.dart.strong.expect
@@ -32,7 +32,7 @@
   method f(covariant generic-covariant-impl core::int* x) → void {}
 }
 static method test() → dynamic {
-  (core::Object*) →* dynamic x = (new self::D::•().{self::C::g4}() as{TypeError} (core::int*) →* dynamic) as (core::Object*) →* dynamic;
+  (core::Object*) →* dynamic x = (new self::D::•().{self::C::g4}() as{TypeError,CovarianceCheck} (core::int*) →* dynamic) as (core::Object*) →* dynamic;
   x.call("hi");
   new self::E::•().{self::C::g1}(1.5);
 }
diff --git a/pkg/front_end/testcases/runtime_checks_new/call_through_this.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks_new/call_through_this.dart.strong.transformed.expect
index 023e6058..61cd6f8e1 100644
--- a/pkg/front_end/testcases/runtime_checks_new/call_through_this.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/call_through_this.dart.strong.transformed.expect
@@ -32,7 +32,7 @@
   method f(covariant generic-covariant-impl core::int* x) → void {}
 }
 static method test() → dynamic {
-  (core::Object*) →* dynamic x = (new self::D::•().{self::C::g4}() as{TypeError} (core::int*) →* dynamic) as (core::Object*) →* dynamic;
+  (core::Object*) →* dynamic x = (new self::D::•().{self::C::g4}() as{TypeError,CovarianceCheck} (core::int*) →* dynamic) as (core::Object*) →* dynamic;
   x.call("hi");
   new self::E::•().{self::C::g1}(1.5);
 }
diff --git a/pkg/front_end/testcases/runtime_checks_new/contravariant_combiner.dart.strong.expect b/pkg/front_end/testcases/runtime_checks_new/contravariant_combiner.dart.strong.expect
index 873a975..55cc7d2 100644
--- a/pkg/front_end/testcases/runtime_checks_new/contravariant_combiner.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/contravariant_combiner.dart.strong.expect
@@ -21,19 +21,19 @@
   operator []=(core::int* i, self::B<core::num*, (core::num*) →* void>* v) → void {}
 }
 static method test1(self::B<core::num*, (core::num*) →* void>* b) → void {
-  b = b.{self::B::+}(1) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
-  self::B<core::num*, (core::num*) →* void>* x = b = b.{self::B::+}(2) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
+  b = b.{self::B::+}(1) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
+  self::B<core::num*, (core::num*) →* void>* x = b = b.{self::B::+}(2) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
 }
 static method test2(self::C* c) → void {
-  let final self::C* #t1 = c in let final core::int* #t2 = 0 in #t1.{self::C::[]=}(#t2, #t1.{self::C::[]}(#t2).{self::B::+}(1) as{TypeError} self::B<core::num*, (core::num*) →* void>*);
-  self::B<core::num*, (core::num*) →* void>* x = let final self::C* #t3 = c in let final core::int* #t4 = 0 in let final self::B<core::num*, (core::num*) →* void>* #t5 = #t3.{self::C::[]}(#t4).{self::B::+}(2) as{TypeError} self::B<core::num*, (core::num*) →* void>* in let final void #t6 = #t3.{self::C::[]=}(#t4, #t5) in #t5;
+  let final self::C* #t1 = c in let final core::int* #t2 = 0 in #t1.{self::C::[]=}(#t2, #t1.{self::C::[]}(#t2).{self::B::+}(1) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*);
+  self::B<core::num*, (core::num*) →* void>* x = let final self::C* #t3 = c in let final core::int* #t4 = 0 in let final self::B<core::num*, (core::num*) →* void>* #t5 = #t3.{self::C::[]}(#t4).{self::B::+}(2) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>* in let final void #t6 = #t3.{self::C::[]=}(#t4, #t5) in #t5;
 }
 static method test3(self::C* c) → void {
-  let final self::C* #t7 = c in #t7.{self::C::x} = #t7.{self::C::x}.{self::B::+}(1) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
-  self::B<core::num*, (core::num*) →* void>* x = let final self::C* #t8 = c in #t8.{self::C::x} = #t8.{self::C::x}.{self::B::+}(2) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
+  let final self::C* #t7 = c in #t7.{self::C::x} = #t7.{self::C::x}.{self::B::+}(1) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
+  self::B<core::num*, (core::num*) →* void>* x = let final self::C* #t8 = c in #t8.{self::C::x} = #t8.{self::C::x}.{self::B::+}(2) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
 }
 static method test4(self::C* c) → void {
-  self::C::y = self::C::y.{self::B::+}(1) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
-  self::B<core::num*, (core::num*) →* void>* x = self::C::y = self::C::y.{self::B::+}(2) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
+  self::C::y = self::C::y.{self::B::+}(1) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
+  self::B<core::num*, (core::num*) →* void>* x = self::C::y = self::C::y.{self::B::+}(2) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks_new/contravariant_combiner.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks_new/contravariant_combiner.dart.strong.transformed.expect
index 873a975..55cc7d2 100644
--- a/pkg/front_end/testcases/runtime_checks_new/contravariant_combiner.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/contravariant_combiner.dart.strong.transformed.expect
@@ -21,19 +21,19 @@
   operator []=(core::int* i, self::B<core::num*, (core::num*) →* void>* v) → void {}
 }
 static method test1(self::B<core::num*, (core::num*) →* void>* b) → void {
-  b = b.{self::B::+}(1) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
-  self::B<core::num*, (core::num*) →* void>* x = b = b.{self::B::+}(2) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
+  b = b.{self::B::+}(1) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
+  self::B<core::num*, (core::num*) →* void>* x = b = b.{self::B::+}(2) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
 }
 static method test2(self::C* c) → void {
-  let final self::C* #t1 = c in let final core::int* #t2 = 0 in #t1.{self::C::[]=}(#t2, #t1.{self::C::[]}(#t2).{self::B::+}(1) as{TypeError} self::B<core::num*, (core::num*) →* void>*);
-  self::B<core::num*, (core::num*) →* void>* x = let final self::C* #t3 = c in let final core::int* #t4 = 0 in let final self::B<core::num*, (core::num*) →* void>* #t5 = #t3.{self::C::[]}(#t4).{self::B::+}(2) as{TypeError} self::B<core::num*, (core::num*) →* void>* in let final void #t6 = #t3.{self::C::[]=}(#t4, #t5) in #t5;
+  let final self::C* #t1 = c in let final core::int* #t2 = 0 in #t1.{self::C::[]=}(#t2, #t1.{self::C::[]}(#t2).{self::B::+}(1) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*);
+  self::B<core::num*, (core::num*) →* void>* x = let final self::C* #t3 = c in let final core::int* #t4 = 0 in let final self::B<core::num*, (core::num*) →* void>* #t5 = #t3.{self::C::[]}(#t4).{self::B::+}(2) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>* in let final void #t6 = #t3.{self::C::[]=}(#t4, #t5) in #t5;
 }
 static method test3(self::C* c) → void {
-  let final self::C* #t7 = c in #t7.{self::C::x} = #t7.{self::C::x}.{self::B::+}(1) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
-  self::B<core::num*, (core::num*) →* void>* x = let final self::C* #t8 = c in #t8.{self::C::x} = #t8.{self::C::x}.{self::B::+}(2) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
+  let final self::C* #t7 = c in #t7.{self::C::x} = #t7.{self::C::x}.{self::B::+}(1) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
+  self::B<core::num*, (core::num*) →* void>* x = let final self::C* #t8 = c in #t8.{self::C::x} = #t8.{self::C::x}.{self::B::+}(2) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
 }
 static method test4(self::C* c) → void {
-  self::C::y = self::C::y.{self::B::+}(1) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
-  self::B<core::num*, (core::num*) →* void>* x = self::C::y = self::C::y.{self::B::+}(2) as{TypeError} self::B<core::num*, (core::num*) →* void>*;
+  self::C::y = self::C::y.{self::B::+}(1) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
+  self::B<core::num*, (core::num*) →* void>* x = self::C::y = self::C::y.{self::B::+}(2) as{TypeError,CovarianceCheck} self::B<core::num*, (core::num*) →* void>*;
 }
 static method main() → void {}
diff --git a/pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart.strong.expect b/pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart.strong.expect
index 1a716ef..d6df34f 100644
--- a/pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart.strong.expect
@@ -54,13 +54,13 @@
   self::D* d = new self::D::•(new self::C::•<core::num*>(#C1));
   let final self::D* #t1 = d in #t1.{self::D::value} = let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart:49:46: Error: A value of type 'num Function(num)' can't be assigned to a variable of type 'int Function(int)'.
   d.value /*@ checkReturn=(num*) ->* num* */ += 1;
-                                             ^" in (#t1.{self::D::value}.{self::C::+}(1) as{TypeError} (core::num*) →* core::num*) as{TypeError} (core::int*) →* core::int*;
+                                             ^" in (#t1.{self::D::value}.{self::C::+}(1) as{TypeError,CovarianceCheck} (core::num*) →* core::num*) as{TypeError} (core::int*) →* core::int*;
   self::expect(d.{self::D::setValue}(0), 1);
   d = new self::D::•(new self::C::•<core::num*>(#C2));
   self::expectTypeError(() → core::Null? {
     let final self::D* #t3 = d in #t3.{self::D::value} = let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart:53:48: Error: A value of type 'num Function(num)' can't be assigned to a variable of type 'int Function(int)'.
     d.value /*@ checkReturn=(num*) ->* num* */ += 1;
-                                               ^" in (#t3.{self::D::value}.{self::C::+}(1) as{TypeError} (core::num*) →* core::num*) as{TypeError} (core::int*) →* core::int*;
+                                               ^" in (#t3.{self::D::value}.{self::C::+}(1) as{TypeError,CovarianceCheck} (core::num*) →* core::num*) as{TypeError} (core::int*) →* core::int*;
   });
   self::expect(d.{self::D::setValue}, null);
 }
diff --git a/pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart.strong.transformed.expect
index 1a716ef..d6df34f 100644
--- a/pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart.strong.transformed.expect
@@ -54,13 +54,13 @@
   self::D* d = new self::D::•(new self::C::•<core::num*>(#C1));
   let final self::D* #t1 = d in #t1.{self::D::value} = let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart:49:46: Error: A value of type 'num Function(num)' can't be assigned to a variable of type 'int Function(int)'.
   d.value /*@ checkReturn=(num*) ->* num* */ += 1;
-                                             ^" in (#t1.{self::D::value}.{self::C::+}(1) as{TypeError} (core::num*) →* core::num*) as{TypeError} (core::int*) →* core::int*;
+                                             ^" in (#t1.{self::D::value}.{self::C::+}(1) as{TypeError,CovarianceCheck} (core::num*) →* core::num*) as{TypeError} (core::int*) →* core::int*;
   self::expect(d.{self::D::setValue}(0), 1);
   d = new self::D::•(new self::C::•<core::num*>(#C2));
   self::expectTypeError(() → core::Null? {
     let final self::D* #t3 = d in #t3.{self::D::value} = let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_generic_return_with_compound_assign_implicit_downcast.dart:53:48: Error: A value of type 'num Function(num)' can't be assigned to a variable of type 'int Function(int)'.
     d.value /*@ checkReturn=(num*) ->* num* */ += 1;
-                                               ^" in (#t3.{self::D::value}.{self::C::+}(1) as{TypeError} (core::num*) →* core::num*) as{TypeError} (core::int*) →* core::int*;
+                                               ^" in (#t3.{self::D::value}.{self::C::+}(1) as{TypeError,CovarianceCheck} (core::num*) →* core::num*) as{TypeError} (core::int*) →* core::int*;
   });
   self::expect(d.{self::D::setValue}, null);
 }
diff --git a/pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart.strong.expect b/pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart.strong.expect
index 8060719..2d0bf7f 100644
--- a/pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart.strong.expect
@@ -42,19 +42,19 @@
   set x(self::B<(self::C::T*) →* void>* value) → void {}
 }
 static method test(self::C<core::num*>* c) → void {
-  let final self::C<core::num*>* #t1 = c in #t1.{self::C::x} = (#t1.{self::C::x} as{TypeError} self::B<(core::num*) →* void>*).{self::B::+}(let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:20:54: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
+  let final self::C<core::num*>* #t1 = c in #t1.{self::C::x} = (#t1.{self::C::x} as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{self::B::+}(let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:20:54: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
  - 'B' is from 'pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart'.
   c. /*@ checkReturn=B<(num*) ->* void>* */ x += new B<num>();
                                                      ^" in new self::B::•<core::num*>() as{TypeError} self::B<(core::num*) →* void>*);
-  self::B<(core::num*) →* void>* y = let final self::C<core::num*>* #t3 = c in #t3.{self::C::x} = (#t3.{self::C::x} as{TypeError} self::B<(core::num*) →* void>*).{self::B::+}(let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:21:62: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
+  self::B<(core::num*) →* void>* y = let final self::C<core::num*>* #t3 = c in #t3.{self::C::x} = (#t3.{self::C::x} as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{self::B::+}(let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:21:62: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
  - 'B' is from 'pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart'.
   var y = c. /*@ checkReturn=B<(num*) ->* void>* */ x += new B<num>();
                                                              ^" in new self::B::•<core::num*>() as{TypeError} self::B<(core::num*) →* void>*);
-  let final self::C<core::num*>* #t5 = c in (#t5.{self::C::x} as{TypeError} self::B<(core::num*) →* void>*).{core::Object::==}(null) ?{self::B<core::Object*>*} #t5.{self::C::x} = let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:22:55: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
+  let final self::C<core::num*>* #t5 = c in (#t5.{self::C::x} as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{core::Object::==}(null) ?{self::B<core::Object*>*} #t5.{self::C::x} = let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:22:55: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
  - 'B' is from 'pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart'.
   c. /*@ checkReturn=B<(num*) ->* void>* */ x ??= new B<num>();
                                                       ^" in new self::B::•<core::num*>() as{TypeError} self::B<(core::num*) →* void>* : null;
-  self::B<core::Object*>* z = let final self::C<core::num*>* #t7 = c in let final self::B<(core::num*) →* void>* #t8 = #t7.{self::C::x} as{TypeError} self::B<(core::num*) →* void>* in #t8.{core::Object::==}(null) ?{self::B<core::Object*>*} #t7.{self::C::x} = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:23:63: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
+  self::B<core::Object*>* z = let final self::C<core::num*>* #t7 = c in let final self::B<(core::num*) →* void>* #t8 = #t7.{self::C::x} as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>* in #t8.{core::Object::==}(null) ?{self::B<core::Object*>*} #t7.{self::C::x} = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:23:63: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
  - 'B' is from 'pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart'.
   var z = c. /*@ checkReturn=B<(num*) ->* void>* */ x ??= new B<num>();
                                                               ^" in new self::B::•<core::num*>() as{TypeError} self::B<(core::num*) →* void>* : #t8;
diff --git a/pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart.strong.transformed.expect
index 8060719..2d0bf7f 100644
--- a/pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart.strong.transformed.expect
@@ -42,19 +42,19 @@
   set x(self::B<(self::C::T*) →* void>* value) → void {}
 }
 static method test(self::C<core::num*>* c) → void {
-  let final self::C<core::num*>* #t1 = c in #t1.{self::C::x} = (#t1.{self::C::x} as{TypeError} self::B<(core::num*) →* void>*).{self::B::+}(let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:20:54: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
+  let final self::C<core::num*>* #t1 = c in #t1.{self::C::x} = (#t1.{self::C::x} as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{self::B::+}(let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:20:54: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
  - 'B' is from 'pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart'.
   c. /*@ checkReturn=B<(num*) ->* void>* */ x += new B<num>();
                                                      ^" in new self::B::•<core::num*>() as{TypeError} self::B<(core::num*) →* void>*);
-  self::B<(core::num*) →* void>* y = let final self::C<core::num*>* #t3 = c in #t3.{self::C::x} = (#t3.{self::C::x} as{TypeError} self::B<(core::num*) →* void>*).{self::B::+}(let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:21:62: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
+  self::B<(core::num*) →* void>* y = let final self::C<core::num*>* #t3 = c in #t3.{self::C::x} = (#t3.{self::C::x} as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{self::B::+}(let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:21:62: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
  - 'B' is from 'pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart'.
   var y = c. /*@ checkReturn=B<(num*) ->* void>* */ x += new B<num>();
                                                              ^" in new self::B::•<core::num*>() as{TypeError} self::B<(core::num*) →* void>*);
-  let final self::C<core::num*>* #t5 = c in (#t5.{self::C::x} as{TypeError} self::B<(core::num*) →* void>*).{core::Object::==}(null) ?{self::B<core::Object*>*} #t5.{self::C::x} = let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:22:55: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
+  let final self::C<core::num*>* #t5 = c in (#t5.{self::C::x} as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{core::Object::==}(null) ?{self::B<core::Object*>*} #t5.{self::C::x} = let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:22:55: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
  - 'B' is from 'pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart'.
   c. /*@ checkReturn=B<(num*) ->* void>* */ x ??= new B<num>();
                                                       ^" in new self::B::•<core::num*>() as{TypeError} self::B<(core::num*) →* void>* : null;
-  self::B<core::Object*>* z = let final self::C<core::num*>* #t7 = c in let final self::B<(core::num*) →* void>* #t8 = #t7.{self::C::x} as{TypeError} self::B<(core::num*) →* void>* in #t8.{core::Object::==}(null) ?{self::B<core::Object*>*} #t7.{self::C::x} = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:23:63: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
+  self::B<core::Object*>* z = let final self::C<core::num*>* #t7 = c in let final self::B<(core::num*) →* void>* #t8 = #t7.{self::C::x} as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>* in #t8.{core::Object::==}(null) ?{self::B<core::Object*>*} #t7.{self::C::x} = let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart:23:63: Error: A value of type 'B<num>' can't be assigned to a variable of type 'B<void Function(num)>'.
  - 'B' is from 'pkg/front_end/testcases/runtime_checks_new/contravariant_getter_return_compound_assign.dart'.
   var z = c. /*@ checkReturn=B<(num*) ->* void>* */ x ??= new B<num>();
                                                               ^" in new self::B::•<core::num*>() as{TypeError} self::B<(core::num*) →* void>* : #t8;
diff --git a/pkg/front_end/testcases/runtime_checks_new/contravariant_index_assign.dart.strong.expect b/pkg/front_end/testcases/runtime_checks_new/contravariant_index_assign.dart.strong.expect
index 41e53d1..a93c374 100644
--- a/pkg/front_end/testcases/runtime_checks_new/contravariant_index_assign.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/contravariant_index_assign.dart.strong.expect
@@ -20,9 +20,9 @@
 }
 static method test(self::C<core::num*>* c) → void {
   c.{self::C::[]=}(0, new self::B::•<(core::num*) →* void>());
-  let final self::C<core::num*>* #t1 = c in let final core::int* #t2 = 0 in #t1.{self::C::[]=}(#t2, (#t1.{self::C::[]}(#t2) as{TypeError} self::B<(core::num*) →* void>*).{self::B::+}(new self::B::•<(core::num*) →* void>()));
-  self::B<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in let final core::int* #t4 = 0 in let final self::B<(core::num*) →* void>* #t5 = (#t3.{self::C::[]}(#t4) as{TypeError} self::B<(core::num*) →* void>*).{self::B::+}(new self::B::•<(core::num*) →* void>()) in let final void #t6 = #t3.{self::C::[]=}(#t4, #t5) in #t5;
-  let final self::C<core::num*>* #t7 = c in let final core::int* #t8 = 0 in (#t7.{self::C::[]}(#t8) as{TypeError} self::B<(core::num*) →* void>*).{core::Object::==}(null) ?{self::B<(core::num*) →* void>*} #t7.{self::C::[]=}(#t8, new self::B::•<(core::num*) →* void>()) : null;
-  self::B<(core::num*) →* void>* y = let final self::C<core::num*>* #t9 = c in let final core::int* #t10 = 0 in let final self::B<(core::num*) →* void>* #t11 = #t9.{self::C::[]}(#t10) as{TypeError} self::B<(core::num*) →* void>* in #t11.{core::Object::==}(null) ?{self::B<(core::num*) →* void>*} let final self::B<(core::num*) →* void>* #t12 = new self::B::•<(core::num*) →* void>() in let final void #t13 = #t9.{self::C::[]=}(#t10, #t12) in #t12 : #t11;
+  let final self::C<core::num*>* #t1 = c in let final core::int* #t2 = 0 in #t1.{self::C::[]=}(#t2, (#t1.{self::C::[]}(#t2) as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{self::B::+}(new self::B::•<(core::num*) →* void>()));
+  self::B<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in let final core::int* #t4 = 0 in let final self::B<(core::num*) →* void>* #t5 = (#t3.{self::C::[]}(#t4) as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{self::B::+}(new self::B::•<(core::num*) →* void>()) in let final void #t6 = #t3.{self::C::[]=}(#t4, #t5) in #t5;
+  let final self::C<core::num*>* #t7 = c in let final core::int* #t8 = 0 in (#t7.{self::C::[]}(#t8) as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{core::Object::==}(null) ?{self::B<(core::num*) →* void>*} #t7.{self::C::[]=}(#t8, new self::B::•<(core::num*) →* void>()) : null;
+  self::B<(core::num*) →* void>* y = let final self::C<core::num*>* #t9 = c in let final core::int* #t10 = 0 in let final self::B<(core::num*) →* void>* #t11 = #t9.{self::C::[]}(#t10) as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>* in #t11.{core::Object::==}(null) ?{self::B<(core::num*) →* void>*} let final self::B<(core::num*) →* void>* #t12 = new self::B::•<(core::num*) →* void>() in let final void #t13 = #t9.{self::C::[]=}(#t10, #t12) in #t12 : #t11;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/runtime_checks_new/contravariant_index_assign.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks_new/contravariant_index_assign.dart.strong.transformed.expect
index 41e53d1..a93c374 100644
--- a/pkg/front_end/testcases/runtime_checks_new/contravariant_index_assign.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/contravariant_index_assign.dart.strong.transformed.expect
@@ -20,9 +20,9 @@
 }
 static method test(self::C<core::num*>* c) → void {
   c.{self::C::[]=}(0, new self::B::•<(core::num*) →* void>());
-  let final self::C<core::num*>* #t1 = c in let final core::int* #t2 = 0 in #t1.{self::C::[]=}(#t2, (#t1.{self::C::[]}(#t2) as{TypeError} self::B<(core::num*) →* void>*).{self::B::+}(new self::B::•<(core::num*) →* void>()));
-  self::B<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in let final core::int* #t4 = 0 in let final self::B<(core::num*) →* void>* #t5 = (#t3.{self::C::[]}(#t4) as{TypeError} self::B<(core::num*) →* void>*).{self::B::+}(new self::B::•<(core::num*) →* void>()) in let final void #t6 = #t3.{self::C::[]=}(#t4, #t5) in #t5;
-  let final self::C<core::num*>* #t7 = c in let final core::int* #t8 = 0 in (#t7.{self::C::[]}(#t8) as{TypeError} self::B<(core::num*) →* void>*).{core::Object::==}(null) ?{self::B<(core::num*) →* void>*} #t7.{self::C::[]=}(#t8, new self::B::•<(core::num*) →* void>()) : null;
-  self::B<(core::num*) →* void>* y = let final self::C<core::num*>* #t9 = c in let final core::int* #t10 = 0 in let final self::B<(core::num*) →* void>* #t11 = #t9.{self::C::[]}(#t10) as{TypeError} self::B<(core::num*) →* void>* in #t11.{core::Object::==}(null) ?{self::B<(core::num*) →* void>*} let final self::B<(core::num*) →* void>* #t12 = new self::B::•<(core::num*) →* void>() in let final void #t13 = #t9.{self::C::[]=}(#t10, #t12) in #t12 : #t11;
+  let final self::C<core::num*>* #t1 = c in let final core::int* #t2 = 0 in #t1.{self::C::[]=}(#t2, (#t1.{self::C::[]}(#t2) as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{self::B::+}(new self::B::•<(core::num*) →* void>()));
+  self::B<(core::num*) →* void>* x = let final self::C<core::num*>* #t3 = c in let final core::int* #t4 = 0 in let final self::B<(core::num*) →* void>* #t5 = (#t3.{self::C::[]}(#t4) as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{self::B::+}(new self::B::•<(core::num*) →* void>()) in let final void #t6 = #t3.{self::C::[]=}(#t4, #t5) in #t5;
+  let final self::C<core::num*>* #t7 = c in let final core::int* #t8 = 0 in (#t7.{self::C::[]}(#t8) as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>*).{core::Object::==}(null) ?{self::B<(core::num*) →* void>*} #t7.{self::C::[]=}(#t8, new self::B::•<(core::num*) →* void>()) : null;
+  self::B<(core::num*) →* void>* y = let final self::C<core::num*>* #t9 = c in let final core::int* #t10 = 0 in let final self::B<(core::num*) →* void>* #t11 = #t9.{self::C::[]}(#t10) as{TypeError,CovarianceCheck} self::B<(core::num*) →* void>* in #t11.{core::Object::==}(null) ?{self::B<(core::num*) →* void>*} let final self::B<(core::num*) →* void>* #t12 = new self::B::•<(core::num*) →* void>() in let final void #t13 = #t9.{self::C::[]=}(#t10, #t12) in #t12 : #t11;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/runtime_checks_new/contravariant_index_get.dart.strong.expect b/pkg/front_end/testcases/runtime_checks_new/contravariant_index_get.dart.strong.expect
index a351f22..28a5438 100644
--- a/pkg/front_end/testcases/runtime_checks_new/contravariant_index_get.dart.strong.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/contravariant_index_get.dart.strong.expect
@@ -11,6 +11,6 @@
     return null;
 }
 static method test(self::C<core::num*>* c) → (core::num*) →* void {
-  return c.{self::C::[]}(0) as{TypeError} (core::num*) →* void;
+  return c.{self::C::[]}(0) as{TypeError,CovarianceCheck} (core::num*) →* void;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/runtime_checks_new/contravariant_index_get.dart.strong.transformed.expect b/pkg/front_end/testcases/runtime_checks_new/contravariant_index_get.dart.strong.transformed.expect
index a351f22..28a5438 100644
--- a/pkg/front_end/testcases/runtime_checks_new/contravariant_index_get.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks_new/contravariant_index_get.dart.strong.transformed.expect
@@ -11,6 +11,6 @@
     return null;
 }
 static method test(self::C<core::num*>* c) → (core::num*) →* void {
-  return c.{self::C::[]}(0) as{TypeError} (core::num*) →* void;
+  return c.{self::C::[]}(0) as{TypeError,CovarianceCheck} (core::num*) →* void;
 }
 static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/strong.status b/pkg/front_end/testcases/strong.status
index f05fdc6..743737c 100644
--- a/pkg/front_end/testcases/strong.status
+++ b/pkg/front_end/testcases/strong.status
@@ -37,6 +37,7 @@
 general/ignore_function: TypeCheckError
 general/incomplete_field_formal_parameter: RuntimeError
 general/invalid_type: TypeCheckError
+general/invalid_operator: TypeCheckError
 general/invocations: RuntimeError
 general/issue34899: TypeCheckError
 general/issue37776: RuntimeError
@@ -65,7 +66,6 @@
 general/unsound_promotion: TypeCheckError
 general/void_methods: RuntimeError
 general/warn_unresolved_sends: InstrumentationMismatch # Test assumes Dart 1.0 semantics
-general/with_dependencies/variance_from_dill/variance_from_dill: Crash
 general_nnbd_opt_out/abstract_members: TypeCheckError
 general_nnbd_opt_out/accessors: RuntimeError
 general_nnbd_opt_out/ambiguous_exports: RuntimeError # Expected, this file exports two main methods.
diff --git a/pkg/front_end/testcases/text_serialization.status b/pkg/front_end/testcases/text_serialization.status
index efca1d2..57367c1 100644
--- a/pkg/front_end/testcases/text_serialization.status
+++ b/pkg/front_end/testcases/text_serialization.status
@@ -207,6 +207,8 @@
 general/interface_covariantInterface_from_class: TextSerializationFailure
 general/invalid_assignment: TextSerializationFailure # Was: Pass
 general/invalid_cast: TextSerializationFailure # Was: Pass
+general/invalid_operator: TypeCheckError
+general/invalid_operator2: TextSerializationFailure
 general/invalid_type: TypeCheckError
 general/invocations: TextSerializationFailure # Was: RuntimeError
 general/issue129167943: TextSerializationFailure
@@ -281,6 +283,7 @@
 general/part_part_of_different_unnamed_library: TextSerializationFailure
 general/part_part_of_differently_named_library: TextSerializationFailure
 general/platform: TextSerializationFailure
+general/platform_invalid_uris/main: TextSerializationFailure
 general/prefer_baseclass: TextSerializationFailure # Was: Pass
 general/private_method_tearoff: TextSerializationFailure # Was: Pass
 general/private_method_tearoff_lib: TextSerializationFailure # Was: Pass
@@ -336,7 +339,8 @@
 general/var_as_type_name: TextSerializationFailure # Was: Pass
 general/void_methods: TextSerializationFailure
 general/warn_unresolved_sends: InstrumentationMismatch # Test assumes Dart 1.0 semantics
-general/with_dependencies/variance_from_dill/variance_from_dill: Crash
+general/with_dependencies/extension_from_dill/extension_from_dill: TextSerializationFailure
+general/with_dependencies/variance_from_dill/variance_from_dill: TextSerializationFailure
 general_nnbd_opt_out/DeltaBlue: TextSerializationFailure # Was: Pass
 general_nnbd_opt_out/abstract_members: TypeCheckError
 general_nnbd_opt_out/abstract_overrides_concrete_with_no_such_method: TextSerializationFailure
@@ -1199,6 +1203,7 @@
 late_lowering/override: TextSerializationFailure
 late_lowering/return_late: TextSerializationFailure
 new_const_insertion/simple: TextSerializationFailure # Was: Pass
+nnbd/assign_type_variable: TextSerializationFailure
 nnbd/assignability: TextSerializationFailure
 nnbd/call: TextSerializationFailure
 nnbd/definite_assignment_and_completion: TextSerializationFailure
@@ -1241,6 +1246,7 @@
 nnbd/nullable_param: TextSerializationFailure
 nnbd/nullable_receiver: TextSerializationFailure
 nnbd/opt_out: TextSerializationFailure
+nnbd/platform_optional_parameters/main: TextSerializationFailure
 nnbd/potentially_non_nullable_field: TextSerializationFailure
 nnbd/regress_null_aware: TextSerializationFailure
 nnbd/required: TextSerializationFailure
@@ -1251,6 +1257,7 @@
 nnbd/sink_hierarchy: TextSerializationFailure
 nnbd/strictly_non_nullable_warnings: TextSerializationFailure
 nnbd/substitution_in_inference: TextSerializationFailure
+nnbd/tearoff_from_nullable_receiver: TextSerializationFailure
 nnbd/type_parameter_types: TextSerializationFailure
 no_such_method_forwarders/abstract_accessors_from_field: TextSerializationFailure # Was: Pass
 no_such_method_forwarders/abstract_accessors_from_field_arent_mixed_in: TextSerializationFailure # Was: Pass
@@ -1515,6 +1522,7 @@
 runtime_checks_new/stub_from_interface_covariant_from_interface: TextSerializationFailure # Was: Pass
 runtime_checks_new/stub_from_interface_covariant_from_super: TextSerializationFailure # Was: Pass
 set_literals/disambiguation_rule: TextSerializationFailure # Was: RuntimeError
+triple_shift/invalid_operator: TextSerializationFailure
 top_level_variance_test: TextSerializationFailure
 unified_collections/mixed_entries: TextSerializationFailure
 unified_collections/string_concatenation: TextSerializationFailure
diff --git a/pkg/front_end/testcases/triple_shift/invalid_operator.dart b/pkg/front_end/testcases/triple_shift/invalid_operator.dart
new file mode 100644
index 0000000..97cbba7
--- /dev/null
+++ b/pkg/front_end/testcases/triple_shift/invalid_operator.dart
@@ -0,0 +1,33 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class Operators1 {
+  operator >>>() => true;
+}
+
+class Operators2 {
+  operator >>>(a, b) => true;
+}
+
+class Operators3 {
+  operator >>>([a]) => true;
+}
+
+class Operators4 {
+  operator >>>({a}) => true;
+}
+
+class Operators5 {
+  operator >>>(a, [b]) => true;
+}
+
+class Operators6 {
+  operator >>>(a, {b}) => true;
+}
+
+class Operators7 {
+  operator >>><T>(a) => true;
+}
+
+main() {}
diff --git a/pkg/front_end/testcases/triple_shift/invalid_operator.dart.outline.expect b/pkg/front_end/testcases/triple_shift/invalid_operator.dart.outline.expect
new file mode 100644
index 0000000..f27ac1c
--- /dev/null
+++ b/pkg/front_end/testcases/triple_shift/invalid_operator.dart.outline.expect
@@ -0,0 +1,80 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:6:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>() => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:10:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, b) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:14:17: Error: An operator can't have optional parameters.
+//   operator >>>([a]) => true;
+//                 ^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:18:17: Error: An operator can't have optional parameters.
+//   operator >>>({a}) => true;
+//                 ^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:22:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, [b]) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:26:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, {b}) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:30:16: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator >>><T>(a) => true;
+//                ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Operators1 extends core::Object {
+  synthetic constructor •() → self::Operators1*
+    ;
+  operator >>>() → dynamic
+    ;
+}
+class Operators2 extends core::Object {
+  synthetic constructor •() → self::Operators2*
+    ;
+  operator >>>(dynamic a, dynamic b) → dynamic
+    ;
+}
+class Operators3 extends core::Object {
+  synthetic constructor •() → self::Operators3*
+    ;
+  operator >>>([dynamic a]) → dynamic
+    ;
+}
+class Operators4 extends core::Object {
+  synthetic constructor •() → self::Operators4*
+    ;
+  operator >>>({dynamic a}) → dynamic
+    ;
+}
+class Operators5 extends core::Object {
+  synthetic constructor •() → self::Operators5*
+    ;
+  operator >>>(dynamic a, [dynamic b]) → dynamic
+    ;
+}
+class Operators6 extends core::Object {
+  synthetic constructor •() → self::Operators6*
+    ;
+  operator >>>(dynamic a, {dynamic b}) → dynamic
+    ;
+}
+class Operators7 extends core::Object {
+  synthetic constructor •() → self::Operators7*
+    ;
+  operator >>><T extends core::Object* = dynamic>(dynamic a) → dynamic
+    ;
+}
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/triple_shift/invalid_operator.dart.strong.expect b/pkg/front_end/testcases/triple_shift/invalid_operator.dart.strong.expect
new file mode 100644
index 0000000..a8d5e4d
--- /dev/null
+++ b/pkg/front_end/testcases/triple_shift/invalid_operator.dart.strong.expect
@@ -0,0 +1,90 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:6:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>() => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:10:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, b) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:14:17: Error: An operator can't have optional parameters.
+//   operator >>>([a]) => true;
+//                 ^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:18:17: Error: An operator can't have optional parameters.
+//   operator >>>({a}) => true;
+//                 ^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:22:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, [b]) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:26:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, {b}) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:30:16: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator >>><T>(a) => true;
+//                ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Operators1 extends core::Object {
+  synthetic constructor •() → self::Operators1*
+    : super core::Object::•()
+    ;
+  operator >>>() → dynamic
+    return true;
+}
+class Operators2 extends core::Object {
+  synthetic constructor •() → self::Operators2*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, dynamic b) → dynamic
+    return true;
+}
+class Operators3 extends core::Object {
+  synthetic constructor •() → self::Operators3*
+    : super core::Object::•()
+    ;
+  operator >>>([dynamic a = #C1]) → dynamic
+    return true;
+}
+class Operators4 extends core::Object {
+  synthetic constructor •() → self::Operators4*
+    : super core::Object::•()
+    ;
+  operator >>>({dynamic a = #C1}) → dynamic
+    return true;
+}
+class Operators5 extends core::Object {
+  synthetic constructor •() → self::Operators5*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+}
+class Operators6 extends core::Object {
+  synthetic constructor •() → self::Operators6*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+}
+class Operators7 extends core::Object {
+  synthetic constructor •() → self::Operators7*
+    : super core::Object::•()
+    ;
+  operator >>><T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = null
+}
diff --git a/pkg/front_end/testcases/triple_shift/invalid_operator.dart.strong.transformed.expect b/pkg/front_end/testcases/triple_shift/invalid_operator.dart.strong.transformed.expect
new file mode 100644
index 0000000..a8d5e4d
--- /dev/null
+++ b/pkg/front_end/testcases/triple_shift/invalid_operator.dart.strong.transformed.expect
@@ -0,0 +1,90 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:6:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>() => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:10:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, b) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:14:17: Error: An operator can't have optional parameters.
+//   operator >>>([a]) => true;
+//                 ^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:18:17: Error: An operator can't have optional parameters.
+//   operator >>>({a}) => true;
+//                 ^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:22:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, [b]) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:26:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, {b}) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:30:16: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator >>><T>(a) => true;
+//                ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Operators1 extends core::Object {
+  synthetic constructor •() → self::Operators1*
+    : super core::Object::•()
+    ;
+  operator >>>() → dynamic
+    return true;
+}
+class Operators2 extends core::Object {
+  synthetic constructor •() → self::Operators2*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, dynamic b) → dynamic
+    return true;
+}
+class Operators3 extends core::Object {
+  synthetic constructor •() → self::Operators3*
+    : super core::Object::•()
+    ;
+  operator >>>([dynamic a = #C1]) → dynamic
+    return true;
+}
+class Operators4 extends core::Object {
+  synthetic constructor •() → self::Operators4*
+    : super core::Object::•()
+    ;
+  operator >>>({dynamic a = #C1}) → dynamic
+    return true;
+}
+class Operators5 extends core::Object {
+  synthetic constructor •() → self::Operators5*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+}
+class Operators6 extends core::Object {
+  synthetic constructor •() → self::Operators6*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+}
+class Operators7 extends core::Object {
+  synthetic constructor •() → self::Operators7*
+    : super core::Object::•()
+    ;
+  operator >>><T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = null
+}
diff --git a/pkg/front_end/testcases/triple_shift/invalid_operator.dart.weak.expect b/pkg/front_end/testcases/triple_shift/invalid_operator.dart.weak.expect
new file mode 100644
index 0000000..a8d5e4d
--- /dev/null
+++ b/pkg/front_end/testcases/triple_shift/invalid_operator.dart.weak.expect
@@ -0,0 +1,90 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:6:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>() => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:10:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, b) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:14:17: Error: An operator can't have optional parameters.
+//   operator >>>([a]) => true;
+//                 ^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:18:17: Error: An operator can't have optional parameters.
+//   operator >>>({a}) => true;
+//                 ^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:22:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, [b]) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:26:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, {b}) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:30:16: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator >>><T>(a) => true;
+//                ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Operators1 extends core::Object {
+  synthetic constructor •() → self::Operators1*
+    : super core::Object::•()
+    ;
+  operator >>>() → dynamic
+    return true;
+}
+class Operators2 extends core::Object {
+  synthetic constructor •() → self::Operators2*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, dynamic b) → dynamic
+    return true;
+}
+class Operators3 extends core::Object {
+  synthetic constructor •() → self::Operators3*
+    : super core::Object::•()
+    ;
+  operator >>>([dynamic a = #C1]) → dynamic
+    return true;
+}
+class Operators4 extends core::Object {
+  synthetic constructor •() → self::Operators4*
+    : super core::Object::•()
+    ;
+  operator >>>({dynamic a = #C1}) → dynamic
+    return true;
+}
+class Operators5 extends core::Object {
+  synthetic constructor •() → self::Operators5*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+}
+class Operators6 extends core::Object {
+  synthetic constructor •() → self::Operators6*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+}
+class Operators7 extends core::Object {
+  synthetic constructor •() → self::Operators7*
+    : super core::Object::•()
+    ;
+  operator >>><T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = null
+}
diff --git a/pkg/front_end/testcases/triple_shift/invalid_operator.dart.weak.transformed.expect b/pkg/front_end/testcases/triple_shift/invalid_operator.dart.weak.transformed.expect
new file mode 100644
index 0000000..a8d5e4d
--- /dev/null
+++ b/pkg/front_end/testcases/triple_shift/invalid_operator.dart.weak.transformed.expect
@@ -0,0 +1,90 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:6:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>() => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:10:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, b) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:14:17: Error: An operator can't have optional parameters.
+//   operator >>>([a]) => true;
+//                 ^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:18:17: Error: An operator can't have optional parameters.
+//   operator >>>({a}) => true;
+//                 ^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:22:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, [b]) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:26:12: Error: Operator '>>>' should have exactly one parameter.
+//   operator >>>(a, {b}) => true;
+//            ^^^
+//
+// pkg/front_end/testcases/triple_shift/invalid_operator.dart:30:16: Error: Types parameters aren't allowed when defining an operator.
+// Try removing the type parameters.
+//   operator >>><T>(a) => true;
+//                ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Operators1 extends core::Object {
+  synthetic constructor •() → self::Operators1*
+    : super core::Object::•()
+    ;
+  operator >>>() → dynamic
+    return true;
+}
+class Operators2 extends core::Object {
+  synthetic constructor •() → self::Operators2*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, dynamic b) → dynamic
+    return true;
+}
+class Operators3 extends core::Object {
+  synthetic constructor •() → self::Operators3*
+    : super core::Object::•()
+    ;
+  operator >>>([dynamic a = #C1]) → dynamic
+    return true;
+}
+class Operators4 extends core::Object {
+  synthetic constructor •() → self::Operators4*
+    : super core::Object::•()
+    ;
+  operator >>>({dynamic a = #C1}) → dynamic
+    return true;
+}
+class Operators5 extends core::Object {
+  synthetic constructor •() → self::Operators5*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, [dynamic b = #C1]) → dynamic
+    return true;
+}
+class Operators6 extends core::Object {
+  synthetic constructor •() → self::Operators6*
+    : super core::Object::•()
+    ;
+  operator >>>(dynamic a, {dynamic b = #C1}) → dynamic
+    return true;
+}
+class Operators7 extends core::Object {
+  synthetic constructor •() → self::Operators7*
+    : super core::Object::•()
+    ;
+  operator >>><T extends core::Object* = dynamic>(dynamic a) → dynamic
+    return true;
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = null
+}
diff --git a/pkg/front_end/testcases/triple_shift/test.options b/pkg/front_end/testcases/triple_shift/test.options
new file mode 100644
index 0000000..55774c6
--- /dev/null
+++ b/pkg/front_end/testcases/triple_shift/test.options
@@ -0,0 +1 @@
+--enable-experiment=triple-shift
diff --git a/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.outline.expect b/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.outline.expect
index 7d0b0e0..0014b22 100644
--- a/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.outline.expect
+++ b/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.outline.expect
@@ -73,9 +73,9 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     ;
   no-such-method-forwarder get x() → self::NoSuchMethod::T*
-    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#x, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} self::NoSuchMethod::T*;
+    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#x, 1, const <core::Type*>[], const <dynamic>[], core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} self::NoSuchMethod::T*;
   no-such-method-forwarder method method(self::NoSuchMethod::T* x) → self::NoSuchMethod::T*
-    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#method, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[x]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError} self::NoSuchMethod::T*;
+    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#method, 0, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[x]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{}))) as{TypeError,ForDynamic} self::NoSuchMethod::T*;
   no-such-method-forwarder set y(self::NoSuchMethod::T* x) → void
     return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#y=, 2, const <core::Type*>[], core::List::unmodifiable<dynamic>(<dynamic>[x]), core::Map::unmodifiable<core::Symbol*, dynamic>(const <core::Symbol*, dynamic>{})));
   no-such-method-forwarder set x(self::NoSuchMethod::T* value) → void
diff --git a/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.strong.expect b/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.strong.expect
index fa18fb9..e28e55a 100644
--- a/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.strong.expect
+++ b/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.strong.expect
@@ -77,9 +77,9 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     return 3;
   no-such-method-forwarder get x() → self::NoSuchMethod::T*
-    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 1, #C3, #C4, core::Map::unmodifiable<core::Symbol*, dynamic>(#C5))) as{TypeError} self::NoSuchMethod::T*;
+    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 1, #C3, #C4, core::Map::unmodifiable<core::Symbol*, dynamic>(#C5))) as{TypeError,ForDynamic} self::NoSuchMethod::T*;
   no-such-method-forwarder method method(self::NoSuchMethod::T* x) → self::NoSuchMethod::T*
-    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#C6, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[x]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C5))) as{TypeError} self::NoSuchMethod::T*;
+    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#C6, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[x]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C5))) as{TypeError,ForDynamic} self::NoSuchMethod::T*;
   no-such-method-forwarder set y(self::NoSuchMethod::T* x) → void
     return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#C7, 2, #C3, core::List::unmodifiable<dynamic>(<dynamic>[x]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C5)));
   no-such-method-forwarder set x(self::NoSuchMethod::T* value) → void
@@ -91,10 +91,10 @@
   a.{self::A::method}(3, (core::num* num) → core::Null? {}, "test");
   a.{self::A::method2}(3);
   a.{self::A::x} = 3;
-  core::Map<core::num*, self::Contravariant<core::String*>*>* mapContra = a.{self::A::mapContra} as{TypeError} core::Map<core::num*, self::Contravariant<core::String*>*>*;
-  core::Map<core::num*, (core::String*) →* void>* mapContraFn = a.{self::A::mapContraFn} as{TypeError} core::Map<core::num*, (core::String*) →* void>*;
-  core::Map<core::num*, self::Invariant<core::String*>*>* mapInv = a.{self::A::mapInv} as{TypeError} core::Map<core::num*, self::Invariant<core::String*>*>*;
-  core::Map<core::num*, (core::String*) →* core::String*>* mapInvFn = a.{self::A::mapInvFn} as{TypeError} core::Map<core::num*, (core::String*) →* core::String*>*;
+  core::Map<core::num*, self::Contravariant<core::String*>*>* mapContra = a.{self::A::mapContra} as{TypeError,CovarianceCheck} core::Map<core::num*, self::Contravariant<core::String*>*>*;
+  core::Map<core::num*, (core::String*) →* void>* mapContraFn = a.{self::A::mapContraFn} as{TypeError,CovarianceCheck} core::Map<core::num*, (core::String*) →* void>*;
+  core::Map<core::num*, self::Invariant<core::String*>*>* mapInv = a.{self::A::mapInv} as{TypeError,CovarianceCheck} core::Map<core::num*, self::Invariant<core::String*>*>*;
+  core::Map<core::num*, (core::String*) →* core::String*>* mapInvFn = a.{self::A::mapInvFn} as{TypeError,CovarianceCheck} core::Map<core::num*, (core::String*) →* core::String*>*;
   self::B<core::int*>* b = new self::B::•<core::int*>();
   b.{self::B::x} = 3;
   self::expect(3, b.{self::B::x});
diff --git a/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.strong.transformed.expect b/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.strong.transformed.expect
index fa18fb9..e28e55a 100644
--- a/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/variance/generic_covariance_sound_variance.dart.strong.transformed.expect
@@ -77,9 +77,9 @@
   method noSuchMethod(core::Invocation* _) → dynamic
     return 3;
   no-such-method-forwarder get x() → self::NoSuchMethod::T*
-    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 1, #C3, #C4, core::Map::unmodifiable<core::Symbol*, dynamic>(#C5))) as{TypeError} self::NoSuchMethod::T*;
+    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#C2, 1, #C3, #C4, core::Map::unmodifiable<core::Symbol*, dynamic>(#C5))) as{TypeError,ForDynamic} self::NoSuchMethod::T*;
   no-such-method-forwarder method method(self::NoSuchMethod::T* x) → self::NoSuchMethod::T*
-    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#C6, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[x]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C5))) as{TypeError} self::NoSuchMethod::T*;
+    return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#C6, 0, #C3, core::List::unmodifiable<dynamic>(<dynamic>[x]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C5))) as{TypeError,ForDynamic} self::NoSuchMethod::T*;
   no-such-method-forwarder set y(self::NoSuchMethod::T* x) → void
     return this.{self::NoSuchMethod::noSuchMethod}(new core::_InvocationMirror::_withType(#C7, 2, #C3, core::List::unmodifiable<dynamic>(<dynamic>[x]), core::Map::unmodifiable<core::Symbol*, dynamic>(#C5)));
   no-such-method-forwarder set x(self::NoSuchMethod::T* value) → void
@@ -91,10 +91,10 @@
   a.{self::A::method}(3, (core::num* num) → core::Null? {}, "test");
   a.{self::A::method2}(3);
   a.{self::A::x} = 3;
-  core::Map<core::num*, self::Contravariant<core::String*>*>* mapContra = a.{self::A::mapContra} as{TypeError} core::Map<core::num*, self::Contravariant<core::String*>*>*;
-  core::Map<core::num*, (core::String*) →* void>* mapContraFn = a.{self::A::mapContraFn} as{TypeError} core::Map<core::num*, (core::String*) →* void>*;
-  core::Map<core::num*, self::Invariant<core::String*>*>* mapInv = a.{self::A::mapInv} as{TypeError} core::Map<core::num*, self::Invariant<core::String*>*>*;
-  core::Map<core::num*, (core::String*) →* core::String*>* mapInvFn = a.{self::A::mapInvFn} as{TypeError} core::Map<core::num*, (core::String*) →* core::String*>*;
+  core::Map<core::num*, self::Contravariant<core::String*>*>* mapContra = a.{self::A::mapContra} as{TypeError,CovarianceCheck} core::Map<core::num*, self::Contravariant<core::String*>*>*;
+  core::Map<core::num*, (core::String*) →* void>* mapContraFn = a.{self::A::mapContraFn} as{TypeError,CovarianceCheck} core::Map<core::num*, (core::String*) →* void>*;
+  core::Map<core::num*, self::Invariant<core::String*>*>* mapInv = a.{self::A::mapInv} as{TypeError,CovarianceCheck} core::Map<core::num*, self::Invariant<core::String*>*>*;
+  core::Map<core::num*, (core::String*) →* core::String*>* mapInvFn = a.{self::A::mapInvFn} as{TypeError,CovarianceCheck} core::Map<core::num*, (core::String*) →* core::String*>*;
   self::B<core::int*>* b = new self::B::•<core::int*>();
   b.{self::B::x} = 3;
   self::expect(3, b.{self::B::x});
diff --git a/pkg/front_end/testing.json b/pkg/front_end/testing.json
index afa117c..5032126 100644
--- a/pkg/front_end/testing.json
+++ b/pkg/front_end/testing.json
@@ -284,8 +284,6 @@
         "test/fasta/super_mixins_test\\.dart$",
         "test/fasta/types/subtypes_benchmark\\.dart$",
         "test/fasta/unlinked_scope_test\\.dart$",
-        "test/incremental_load_from_dill_suite\\.dart$",
-        "test/incremental_load_from_invalid_dill_test\\.dart$",
         "test/memory_file_system_test\\.dart$",
         "test/scanner_fasta_test\\.dart$",
         "test/scanner_test\\.dart$",
diff --git a/pkg/kernel/binary.md b/pkg/kernel/binary.md
index 12f3b1f..6c70435 100644
--- a/pkg/kernel/binary.md
+++ b/pkg/kernel/binary.md
@@ -143,7 +143,7 @@
 
 type ComponentFile {
   UInt32 magic = 0x90ABCDEF;
-  UInt32 formatVersion = 37;
+  UInt32 formatVersion = 38;
   List<String> problemsAsJson; // Described in problems.md.
   Library[] libraries;
   UriSource sourceMap;
@@ -776,6 +776,7 @@
 type IsExpression extends Expression {
   Byte tag = 37;
   FileOffset fileOffset;
+  Byte flags (isForNonNullableByDefault);
   Expression operand;
   DartType type;
 }
@@ -783,7 +784,7 @@
 type AsExpression extends Expression {
   Byte tag = 38;
   FileOffset fileOffset;
-  Byte flags (isTypeError);
+  Byte flags (isTypeError,isCovarianceCheck,isForDynamic,isForNonNullableByDefault);
   Expression operand;
   DartType type;
 }
diff --git a/pkg/kernel/lib/ast.dart b/pkg/kernel/lib/ast.dart
index 2e89ba6..1b452d2 100644
--- a/pkg/kernel/lib/ast.dart
+++ b/pkg/kernel/lib/ast.dart
@@ -3952,6 +3952,7 @@
 
 /// Expression of form `x is T`.
 class IsExpression extends Expression {
+  int flags = 0;
   Expression operand;
   DartType type;
 
@@ -3959,6 +3960,22 @@
     operand?.parent = this;
   }
 
+  // Must match serialized bit positions.
+  static const int FlagForNonNullableByDefault = 1 << 0;
+
+  /// If `true`, this test take the nullability of [type] into account.
+  ///
+  /// This is the case for is-tests written in libraries that are opted in to
+  /// the non nullable by default feature.
+  bool get isForNonNullableByDefault =>
+      flags & FlagForNonNullableByDefault != 0;
+
+  void set isForNonNullableByDefault(bool value) {
+    flags = value
+        ? (flags | FlagForNonNullableByDefault)
+        : (flags & ~FlagForNonNullableByDefault);
+  }
+
   DartType getStaticType(StaticTypeContext context) =>
       context.typeEnvironment.coreTypes.boolRawType(context.nonNullable);
 
@@ -3992,17 +4009,66 @@
 
   // Must match serialized bit positions.
   static const int FlagTypeError = 1 << 0;
+  static const int FlagCovarianceCheck = 1 << 1;
+  static const int FlagForDynamic = 1 << 2;
+  static const int FlagForNonNullableByDefault = 1 << 3;
 
-  /// Indicates the type of error that should be thrown if the check fails.
+  /// If `true`, this test is an implicit down cast.
   ///
-  /// `true` means that a TypeError should be thrown.  `false` means that a
-  /// CastError should be thrown.
+  /// If `true` a TypeError should be thrown. If `false` a CastError should be
+  /// thrown.
   bool get isTypeError => flags & FlagTypeError != 0;
 
   void set isTypeError(bool value) {
     flags = value ? (flags | FlagTypeError) : (flags & ~FlagTypeError);
   }
 
+  /// If `true`, this test is needed to ensure soundness of covariant type
+  /// variables using in contravariant positions.
+  ///
+  /// For instance
+  ///
+  ///    class Class<T> {
+  ///      void Function(T) field;
+  ///      Class(this.field);
+  ///    }
+  ///    main() {
+  ///      Class<num> c = new Class<int>((int i) {});
+  ///      void Function<num> field = c.field; // Check needed on `c.field`
+  ///      field(0.5);
+  ///    }
+  ///
+  /// Here a covariant check `c.field as void Function(num)` is needed because
+  /// the field could be (and indeed is) not a subtype of the static type of
+  /// the expression.
+  bool get isCovarianceCheck => flags & FlagCovarianceCheck != 0;
+
+  void set isCovarianceCheck(bool value) {
+    flags =
+        value ? (flags | FlagCovarianceCheck) : (flags & ~FlagCovarianceCheck);
+  }
+
+  /// If `true`, this is an implicit down cast from an expression of type
+  /// `dynamic`.
+  bool get isForDynamic => flags & FlagForDynamic != 0;
+
+  void set isForDynamic(bool value) {
+    flags = value ? (flags | FlagForDynamic) : (flags & ~FlagForDynamic);
+  }
+
+  /// If `true`, this test take the nullability of [type] into account.
+  ///
+  /// This is the case for is-tests written in libraries that are opted in to
+  /// the non nullable by default feature.
+  bool get isForNonNullableByDefault =>
+      flags & FlagForNonNullableByDefault != 0;
+
+  void set isForNonNullableByDefault(bool value) {
+    flags = value
+        ? (flags | FlagForNonNullableByDefault)
+        : (flags & ~FlagForNonNullableByDefault);
+  }
+
   DartType getStaticType(StaticTypeContext context) => type;
 
   R accept<R>(ExpressionVisitor<R> v) => v.visitAsExpression(this);
diff --git a/pkg/kernel/lib/binary/ast_from_binary.dart b/pkg/kernel/lib/binary/ast_from_binary.dart
index 4604782..aabfcf0 100644
--- a/pkg/kernel/lib/binary/ast_from_binary.dart
+++ b/pkg/kernel/lib/binary/ast_from_binary.dart
@@ -1726,8 +1726,10 @@
           ..fileOffset = offset;
       case Tag.IsExpression:
         int offset = readOffset();
+        int flags = readByte();
         return new IsExpression(readExpression(), readDartType())
-          ..fileOffset = offset;
+          ..fileOffset = offset
+          ..flags = flags;
       case Tag.AsExpression:
         int offset = readOffset();
         int flags = readByte();
diff --git a/pkg/kernel/lib/binary/ast_to_binary.dart b/pkg/kernel/lib/binary/ast_to_binary.dart
index 92ef6e8..3df06ad 100644
--- a/pkg/kernel/lib/binary/ast_to_binary.dart
+++ b/pkg/kernel/lib/binary/ast_to_binary.dart
@@ -1597,6 +1597,7 @@
   void visitIsExpression(IsExpression node) {
     writeByte(Tag.IsExpression);
     writeOffset(node.fileOffset);
+    writeByte(node.flags);
     writeNode(node.operand);
     writeNode(node.type);
   }
diff --git a/pkg/kernel/lib/binary/tag.dart b/pkg/kernel/lib/binary/tag.dart
index 9ed4051..f45810b 100644
--- a/pkg/kernel/lib/binary/tag.dart
+++ b/pkg/kernel/lib/binary/tag.dart
@@ -149,7 +149,7 @@
   /// Internal version of kernel binary format.
   /// Bump it when making incompatible changes in kernel binaries.
   /// Keep in sync with runtime/vm/kernel_binary.h, pkg/kernel/binary.md.
-  static const int BinaryFormatVersion = 37;
+  static const int BinaryFormatVersion = 38;
 }
 
 abstract class ConstantTag {
diff --git a/pkg/kernel/lib/class_hierarchy.dart b/pkg/kernel/lib/class_hierarchy.dart
index 977cd45..717f0a5 100644
--- a/pkg/kernel/lib/class_hierarchy.dart
+++ b/pkg/kernel/lib/class_hierarchy.dart
@@ -36,6 +36,8 @@
       .._initialize(component.libraries);
   }
 
+  void set coreTypes(CoreTypes coreTypes);
+
   void set onAmbiguousSupertypes(
       HandleAmbiguousSupertypes onAmbiguousSupertypes);
 
@@ -427,7 +429,7 @@
 
 /// Implementation of [ClassHierarchy] for closed world.
 class ClosedWorldClassHierarchy implements ClassHierarchy {
-  final CoreTypes coreTypes;
+  CoreTypes coreTypes;
   HandleAmbiguousSupertypes _onAmbiguousSupertypes;
   HandleAmbiguousSupertypes _onAmbiguousSupertypesNotWrapped;
   MixinInferrer mixinInferrer;
@@ -451,6 +453,14 @@
   final Map<Class, _ClassInfo> _infoMap =
       new LinkedHashMap<Class, _ClassInfo>();
 
+  List<ForTestingClassInfo> getTestingClassInfo() {
+    List<ForTestingClassInfo> result = new List<ForTestingClassInfo>();
+    for (_ClassInfo info in _infoMap.values) {
+      result.add(new ForTestingClassInfo._(info));
+    }
+    return result;
+  }
+
   _ClassInfo infoFor(Class c) {
     _ClassInfo info = _infoMap[c];
     info?.used = true;
@@ -797,8 +807,13 @@
         if (class_.mixedInType != null) {
           _infoMap[class_.mixedInType.classNode]?.directMixers?.remove(info);
         }
-        for (var supertype in class_.implementedTypes) {
+        for (Supertype supertype in class_.implementedTypes) {
           _infoMap[supertype.classNode]?.directImplementers?.remove(info);
+          // Remove from directMixers too as the mixin transformation will
+          // "move" the type here.
+          if (class_.isAnonymousMixin || class_.isEliminatedMixin) {
+            _infoMap[supertype.classNode]?.directMixers?.remove(info);
+          }
         }
 
         _infoMap.remove(class_);
@@ -914,6 +929,24 @@
         throw new StateError("Didn't know library of $c (from ${c.fileUri})");
       }
     }
+
+    for (_ClassInfo info in _infoMap.values) {
+      for (_ClassInfo subInfo in info.directExtenders) {
+        if (!_infoMap.containsKey(subInfo.classNode))
+          throw new StateError(
+              "Found $subInfo (${subInfo.classNode}) in directExtenders");
+      }
+      for (_ClassInfo subInfo in info.directMixers) {
+        if (!_infoMap.containsKey(subInfo.classNode))
+          throw new StateError(
+              "Found $subInfo (${subInfo.classNode}) in directMixers");
+      }
+      for (_ClassInfo subInfo in info.directImplementers) {
+        if (!_infoMap.containsKey(subInfo.classNode))
+          throw new StateError(
+              "Found $subInfo (${subInfo.classNode}) in directImplementers");
+      }
+    }
     return true;
   }
 
@@ -1444,6 +1477,25 @@
   return size;
 }
 
+class ForTestingClassInfo {
+  final Class classNode;
+  final List<Member> lazyDeclaredGettersAndCalls;
+  final List<Member> lazyDeclaredSetters;
+  final List<Member> lazyImplementedGettersAndCalls;
+  final List<Member> lazyImplementedSetters;
+  final List<Member> lazyInterfaceGettersAndCalls;
+  final List<Member> lazyInterfaceSetters;
+
+  ForTestingClassInfo._(_ClassInfo c)
+      : classNode = c.classNode,
+        lazyDeclaredGettersAndCalls = c.lazyDeclaredGettersAndCalls,
+        lazyDeclaredSetters = c.lazyDeclaredSetters,
+        lazyImplementedGettersAndCalls = c.lazyImplementedGettersAndCalls,
+        lazyImplementedSetters = c.lazyImplementedSetters,
+        lazyInterfaceGettersAndCalls = c.lazyInterfaceGettersAndCalls,
+        lazyInterfaceSetters = c.lazyInterfaceSetters;
+}
+
 class _ClassInfo {
   bool used = false;
   final Class classNode;
diff --git a/pkg/kernel/lib/clone.dart b/pkg/kernel/lib/clone.dart
index 122f956..6b4328a 100644
--- a/pkg/kernel/lib/clone.dart
+++ b/pkg/kernel/lib/clone.dart
@@ -248,7 +248,8 @@
   }
 
   visitIsExpression(IsExpression node) {
-    return new IsExpression(clone(node.operand), visitType(node.type));
+    return new IsExpression(clone(node.operand), visitType(node.type))
+      ..flags = node.flags;
   }
 
   visitAsExpression(AsExpression node) {
diff --git a/pkg/kernel/lib/target/changed_structure_notifier.dart b/pkg/kernel/lib/target/changed_structure_notifier.dart
new file mode 100644
index 0000000..d18c7de
--- /dev/null
+++ b/pkg/kernel/lib/target/changed_structure_notifier.dart
@@ -0,0 +1,12 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:kernel/ast.dart' show Class;
+
+/// Meant for notifying the backend (the compiler) that the structure has
+/// changed, in turn allowing it to update its internal model.
+abstract class ChangedStructureNotifier {
+  /// Mark the class [c] as having changed in that its members have changed.
+  void forClass(Class c);
+}
diff --git a/pkg/kernel/lib/target/targets.dart b/pkg/kernel/lib/target/targets.dart
index ca12325..05519e6 100644
--- a/pkg/kernel/lib/target/targets.dart
+++ b/pkg/kernel/lib/target/targets.dart
@@ -7,6 +7,7 @@
 import '../class_hierarchy.dart';
 import '../core_types.dart';
 import '../reference_from_index.dart';
+import 'changed_structure_notifier.dart';
 
 final List<String> targetNames = targets.keys.toList();
 
@@ -159,7 +160,8 @@
       CoreTypes coreTypes,
       List<Library> libraries,
       DiagnosticReporter diagnosticReporter,
-      {void logger(String msg)}) {}
+      {void logger(String msg),
+      ChangedStructureNotifier changedStructureNotifier}) {}
 
   /// Perform target-specific modular transformations on the given libraries.
   void performModularTransformationsOnLibraries(
@@ -172,7 +174,8 @@
       Map<String, String> environmentDefines,
       DiagnosticReporter diagnosticReporter,
       ReferenceFromIndex referenceFromIndex,
-      {void logger(String msg)});
+      {void logger(String msg),
+      ChangedStructureNotifier changedStructureNotifier});
 
   /// Perform target-specific modular transformations on the given program.
   ///
@@ -304,7 +307,8 @@
       Map<String, String> environmentDefines,
       DiagnosticReporter diagnosticReporter,
       ReferenceFromIndex referenceFromIndex,
-      {void logger(String msg)}) {}
+      {void logger(String msg),
+      ChangedStructureNotifier changedStructureNotifier}) {}
 
   @override
   Expression instantiateInvocation(CoreTypes coreTypes, Expression receiver,
diff --git a/pkg/kernel/lib/text/ast_to_text.dart b/pkg/kernel/lib/text/ast_to_text.dart
index 015b3b8..06bd220 100644
--- a/pkg/kernel/lib/text/ast_to_text.dart
+++ b/pkg/kernel/lib/text/ast_to_text.dart
@@ -1442,13 +1442,27 @@
 
   visitIsExpression(IsExpression node) {
     writeExpression(node.operand, Precedence.BITWISE_OR);
-    writeSpaced('is');
+    writeSpaced(
+        node.isForNonNullableByDefault ? 'is{ForNonNullableByDefault}' : 'is');
     writeType(node.type);
   }
 
   visitAsExpression(AsExpression node) {
     writeExpression(node.operand, Precedence.BITWISE_OR);
-    writeSpaced(node.isTypeError ? 'as{TypeError}' : 'as');
+    List<String> flags = <String>[];
+    if (node.isTypeError) {
+      flags.add('TypeError');
+    }
+    if (node.isCovarianceCheck) {
+      flags.add('CovarianceCheck');
+    }
+    if (node.isForDynamic) {
+      flags.add('ForDynamic');
+    }
+    if (node.isForNonNullableByDefault) {
+      flags.add('ForNonNullableByDefault');
+    }
+    writeSpaced(flags.isNotEmpty ? 'as{${flags.join(',')}}' : 'as');
     writeType(node.type);
   }
 
diff --git a/pkg/nnbd_migration/lib/instrumentation.dart b/pkg/nnbd_migration/lib/instrumentation.dart
index b623e3c..beda680 100644
--- a/pkg/nnbd_migration/lib/instrumentation.dart
+++ b/pkg/nnbd_migration/lib/instrumentation.dart
@@ -6,7 +6,6 @@
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/generated/source.dart';
-import 'package:nnbd_migration/nullability_state.dart';
 import 'package:nnbd_migration/src/edit_plan.dart';
 
 /// Information exposed to the migration client about the set of nullability
@@ -237,11 +236,6 @@
   /// Clear any data from the propagation step in preparation for that step
   /// being re-run.
   void prepareForUpdate();
-
-  /// Called whenever the migration engine performs a step in the propagation of
-  /// nullability information through the nullability graph, to report details
-  /// of the step that was performed and why.
-  void propagationStep(PropagationInfo info);
 }
 
 /// Information exposed to the migration client about a single node in the
@@ -271,65 +265,6 @@
   Iterable<EdgeInfo> get upstreamEdges;
 }
 
-/// Information exposed to the migration client about a single step in the
-/// nullability propagation algorithm, in which the nullability state of a
-/// single node was changed.
-abstract class PropagationInfo {
-  /// The edge that caused the nullability state of [node] to be set to
-  /// [newState], or `null` if the nullability state was changed for reasons
-  /// not associated with an edge.  Will be `null` when [reason] is
-  /// [StateChangeReason.substituteInner] or
-  /// [StateChangeReason.substituteOuter], non-null otherwise.
-  EdgeInfo get edge;
-
-  /// The new state that [node] was placed into.
-  NullabilityState get newState;
-
-  /// The nullability node whose state was changed.
-  NullabilityNodeInfo get node;
-
-  /// The reason the nullability node's state was changed.
-  StateChangeReason get reason;
-
-  /// The substitution node that caused the nullability state of [node] to be
-  /// set to [newState], or `null` if the nullability state was changed for
-  /// reasons not associated with a substitution node.  Will be non-null when
-  /// [reason] is [StateChangeReason.substituteInner] or
-  /// [StateChangeReason.substituteOuter], `null` otherwise.
-  SubstitutionNodeInfo get substitutionNode;
-}
-
-/// Enum representing the various reasons why a nullability node might change
-/// state during nullability propagation.
-enum StateChangeReason {
-  /// A union edge exists between this node and a node that is known a priori to
-  /// be nullable, so this node is being made nullable as well.
-  union,
-
-  /// A hard or union edge exists whose source is this node, and whose
-  /// destination is non-nullable, so this node is being made non-nullable as
-  /// well.
-  upstream,
-
-  /// An edge exists whose destination is this node, and whose source is
-  /// nullable, so this node is being made nullable as well.
-  downstream,
-
-  /// An edge exists whose source is this node, and whose destination is exact
-  /// nullable, so this node is being made exact nullable as well.
-  exactUpstream,
-
-  /// A substitution node exists whose inner node points to this node, and the
-  /// substitution node is nullable, so this node is being made nullable as
-  /// well.
-  substituteInner,
-
-  /// A substitution node exists whose outer node points to this node, and the
-  /// substitution node is nullable, so this node is being made nullable as
-  /// well.
-  substituteOuter,
-}
-
 /// Information exposed to the migration client about a node in the nullability
 /// graph resulting from a type substitution.
 abstract class SubstitutionNodeInfo extends NullabilityNodeInfo {
diff --git a/pkg/nnbd_migration/lib/nullability_state.dart b/pkg/nnbd_migration/lib/nullability_state.dart
index fdeda46..8e60367 100644
--- a/pkg/nnbd_migration/lib/nullability_state.dart
+++ b/pkg/nnbd_migration/lib/nullability_state.dart
@@ -2,22 +2,51 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-/// State of a nullability node.
-class NullabilityState {
-  /// State of a nullability node whose nullability hasn't been decided yet.
-  static const undetermined = NullabilityState._('undetermined', false);
+/// State representation used to determine whether a nullability node expresses
+/// non-null intent.
+class NonNullIntent {
+  /// State of a nullability node for which no non-null intent has been seen.
+  static const none = NonNullIntent._(false);
 
+  /// State of a nullability node for which indirect evidence of non-null intent
+  /// has been seen (e.g. an assertion or a use of a value in a non-null
+  /// context).
+  static const indirect = NonNullIntent._(true);
+
+  /// State of a nullability node for which direct evidence of non-null intent
+  /// has been seen (e.g. an explicit "/*!*/" on a type, or a non-nullable type
+  /// coming from a migrated library).
+  static const direct = NonNullIntent._(true, isDirect: true);
+
+  /// Indicates whether this state represents a determination that non-null
+  /// intent is present.
+  final bool isPresent;
+
+  /// Indicates whether this state represents a direct determination of non-null
+  /// intent (see [direct]).
+  final bool isDirect;
+
+  const NonNullIntent._(this.isPresent, {this.isDirect = false});
+
+  /// Returns a [NonNullIntent] object representing the result of adding
+  /// indirect non-null intent to `this`.
+  NonNullIntent addIndirect() => isPresent ? this : indirect;
+}
+
+/// State of a nullability node.
+class Nullability {
   /// State of a nullability node that has been determined to be non-nullable
   /// by propagating upstream.
-  static const nonNullable = NullabilityState._('non-nullable', false);
+  static const nonNullable = Nullability._('non-nullable', false);
 
   /// State of a nullability node that has been determined to be nullable by
   /// propagating downstream.
-  static const ordinaryNullable = NullabilityState._('ordinary nullable', true);
+  static const ordinaryNullable = Nullability._('ordinary nullable', true);
 
   /// State of a nullability node that has been determined to be nullable by
   /// propagating upstream from a contravariant use of a generic.
-  static const exactNullable = NullabilityState._('exact nullable', true);
+  static const exactNullable =
+      Nullability._('exact nullable', true, isExactNullable: true);
 
   /// Name of the state (for use in debugging).
   final String name;
@@ -29,7 +58,13 @@
   /// in that state.
   final bool isNullable;
 
-  const NullabilityState._(this.name, this.isNullable);
+  /// Indicates whether a node in this state is "exact nullable", meaning that
+  /// is needs to be nullable because it represents a type argument that will
+  /// later be used in a contravariant way that requires it to be nullable.
+  final bool isExactNullable;
+
+  const Nullability._(this.name, this.isNullable,
+      {this.isExactNullable = false});
 
   @override
   String toString() => name;
diff --git a/pkg/nnbd_migration/lib/src/already_migrated_code_decorator.dart b/pkg/nnbd_migration/lib/src/already_migrated_code_decorator.dart
index f5b3a96..5885679 100644
--- a/pkg/nnbd_migration/lib/src/already_migrated_code_decorator.dart
+++ b/pkg/nnbd_migration/lib/src/already_migrated_code_decorator.dart
@@ -36,7 +36,7 @@
       _graph.makeNullable(node, AlreadyMigratedTypeOrigin.forElement(element));
     } else {
       node = NullabilityNode.forAlreadyMigrated();
-      _graph.makeNonNullable(
+      _graph.makeNonNullableUnion(
           node, AlreadyMigratedTypeOrigin.forElement(element));
     }
     if (type is FunctionType) {
diff --git a/pkg/nnbd_migration/lib/src/decorated_type.dart b/pkg/nnbd_migration/lib/src/decorated_type.dart
index 618022f..5492a7e 100644
--- a/pkg/nnbd_migration/lib/src/decorated_type.dart
+++ b/pkg/nnbd_migration/lib/src/decorated_type.dart
@@ -11,6 +11,7 @@
 import 'package:analyzer/src/dart/element/type_algebra.dart';
 import 'package:analyzer/src/dart/element/type_algebra.dart' as type_algebra;
 import 'package:analyzer/src/generated/utilities_dart.dart';
+import 'package:meta/meta.dart';
 import 'package:nnbd_migration/instrumentation.dart';
 import 'package:nnbd_migration/src/nullability_node.dart';
 
@@ -121,25 +122,29 @@
   /// nodes can later be unioned with other nodes.
   factory DecoratedType.forImplicitFunction(TypeProvider typeProvider,
       FunctionType type, NullabilityNode node, NullabilityGraph graph,
-      {DecoratedType returnType}) {
+      {DecoratedType returnType, @required int offset}) {
     var positionalParameters = <DecoratedType>[];
     var namedParameters = <String, DecoratedType>{};
     for (var parameter in type.parameters) {
       if (parameter.isPositional) {
-        positionalParameters.add(
-            DecoratedType.forImplicitType(typeProvider, parameter.type, graph));
+        positionalParameters.add(DecoratedType.forImplicitType(
+            typeProvider, parameter.type, graph,
+            offset: offset));
       } else {
-        namedParameters[parameter.name] =
-            DecoratedType.forImplicitType(typeProvider, parameter.type, graph);
+        namedParameters[parameter.name] = DecoratedType.forImplicitType(
+            typeProvider, parameter.type, graph,
+            offset: offset);
       }
     }
     return DecoratedType(type, node,
         typeFormalBounds: type.typeFormals
             .map((e) => DecoratedType.forImplicitType(
-                typeProvider, e.bound ?? typeProvider.objectType, graph))
+                typeProvider, e.bound ?? typeProvider.objectType, graph,
+                offset: offset))
             .toList(),
         returnType: returnType ??
-            DecoratedType.forImplicitType(typeProvider, type.returnType, graph),
+            DecoratedType.forImplicitType(typeProvider, type.returnType, graph,
+                offset: offset),
         namedParameters: namedParameters,
         positionalParameters: positionalParameters);
   }
@@ -149,8 +154,8 @@
   /// nodes can later be unioned with other nodes.
   factory DecoratedType.forImplicitType(
       TypeProvider typeProvider, DartType type, NullabilityGraph graph,
-      {List<DecoratedType> typeArguments}) {
-    var nullabilityNode = NullabilityNode.forInferredType();
+      {List<DecoratedType> typeArguments, @required int offset}) {
+    var nullabilityNode = NullabilityNode.forInferredType(offset: offset);
     if (type is InterfaceType) {
       assert(() {
         if (typeArguments != null) {
@@ -163,7 +168,8 @@
       }());
 
       typeArguments ??= type.typeArguments
-          .map((t) => DecoratedType.forImplicitType(typeProvider, t, graph))
+          .map((t) => DecoratedType.forImplicitType(typeProvider, t, graph,
+              offset: offset))
           .toList();
       return DecoratedType(type, nullabilityNode, typeArguments: typeArguments);
     } else if (type is FunctionType) {
@@ -171,7 +177,8 @@
         throw "Not supported: implicit function type with explicit type arguments";
       }
       return DecoratedType.forImplicitFunction(
-          typeProvider, type, nullabilityNode, graph);
+          typeProvider, type, nullabilityNode, graph,
+          offset: offset);
     } else {
       assert(typeArguments == null);
       return DecoratedType(type, nullabilityNode);
@@ -333,9 +340,14 @@
             nullabilitySuffix: NullabilitySuffix.none);
       }
       for (int i = 0; i < newTypeFormals.length; i++) {
-        newTypeFormals[i].bound = type_algebra.substitute(
+        var bound = type_algebra.substitute(
             typeFormalBounds[i].toFinalType(typeProvider),
             typeFormalSubstitution);
+        if (!bound.isDynamic &&
+            !(bound.isDartCoreObject &&
+                bound.nullabilitySuffix == NullabilitySuffix.question)) {
+          newTypeFormals[i].bound = bound;
+        }
       }
       var parameters = <ParameterElement>[];
       for (int i = 0; i < type.parameters.length; i++) {
diff --git a/pkg/nnbd_migration/lib/src/edge_builder.dart b/pkg/nnbd_migration/lib/src/edge_builder.dart
index e4c3772..0f74586 100644
--- a/pkg/nnbd_migration/lib/src/edge_builder.dart
+++ b/pkg/nnbd_migration/lib/src/edge_builder.dart
@@ -71,8 +71,9 @@
   @override
   void _connect(
       NullabilityNode source, NullabilityNode destination, EdgeOrigin origin,
-      {bool hard = false}) {
-    _graph.connect(source, destination, origin, hard: hard);
+      {bool hard = false, bool checkable = true}) {
+    _graph.connect(source, destination, origin,
+        hard: hard, checkable: checkable);
   }
 
   @override
@@ -898,7 +899,8 @@
       if (staticType is InterfaceType) {
         typeArgumentTypes = staticType.typeArguments;
         decoratedTypeArguments = typeArgumentTypes
-            .map((t) => DecoratedType.forImplicitType(typeProvider, t, _graph))
+            .map((t) => DecoratedType.forImplicitType(typeProvider, t, _graph,
+                offset: node.offset))
             .toList();
         instrumentation?.implicitTypeArguments(
             source, node, decoratedTypeArguments);
@@ -916,7 +918,7 @@
           ListLengthConstructorOrigin(source, node));
     }
 
-    var nullabilityNode = NullabilityNode.forInferredType();
+    var nullabilityNode = NullabilityNode.forInferredType(offset: node.offset);
     _graph.makeNonNullable(
         nullabilityNode, InstanceCreationOrigin(source, node));
     var createdType = DecoratedType(node.staticType, nullabilityNode,
@@ -986,7 +988,8 @@
       var listType = node.staticType as InterfaceType;
       if (node.typeArguments == null) {
         var elementType = DecoratedType.forImplicitType(
-            typeProvider, listType.typeArguments[0], _graph);
+            typeProvider, listType.typeArguments[0], _graph,
+            offset: node.offset);
         instrumentation?.implicitTypeArguments(source, node, [elementType]);
         _currentLiteralElementType = elementType;
       } else {
@@ -1089,8 +1092,9 @@
   @override
   DecoratedType visitNullLiteral(NullLiteral node) {
     _flowAnalysis.nullLiteral(node);
-    var decoratedType =
-        DecoratedType.forImplicitType(typeProvider, node.staticType, _graph);
+    var decoratedType = DecoratedType.forImplicitType(
+        typeProvider, node.staticType, _graph,
+        offset: node.offset);
     _graph.makeNullable(decoratedType.node, LiteralOrigin(source, node));
     return decoratedType;
   }
@@ -1207,7 +1211,7 @@
   @override
   DecoratedType visitRethrowExpression(RethrowExpression node) {
     _flowAnalysis.handleExit();
-    var nullabilityNode = NullabilityNode.forInferredType();
+    var nullabilityNode = NullabilityNode.forInferredType(offset: node.offset);
     _graph.makeNonNullable(nullabilityNode, ThrowOrigin(source, node));
     return DecoratedType(node.staticType, nullabilityNode);
   }
@@ -1219,11 +1223,14 @@
     final isAsync = node.thisOrAncestorOfType<FunctionBody>().isAsynchronous;
     if (returnValue == null) {
       var implicitNullType = DecoratedType.forImplicitType(
-          typeProvider, typeProvider.nullType, _graph);
+          typeProvider, typeProvider.nullType, _graph,
+          offset: node.offset);
       _graph.makeNullable(
           implicitNullType.node, AlwaysNullableTypeOrigin(source, node));
       _checkAssignment(null,
-          source: isAsync ? _futureOf(implicitNullType) : implicitNullType,
+          source: isAsync
+              ? _futureOf(implicitNullType, offset: node.offset)
+              : implicitNullType,
           destination: returnType,
           hard: false);
     } else {
@@ -1251,7 +1258,8 @@
         if (typeArguments == null) {
           assert(setOrMapType.typeArguments.length == 1);
           var elementType = DecoratedType.forImplicitType(
-              typeProvider, setOrMapType.typeArguments[0], _graph);
+              typeProvider, setOrMapType.typeArguments[0], _graph,
+              offset: node.offset);
           instrumentation?.implicitTypeArguments(source, node, [elementType]);
           _currentLiteralElementType = elementType;
         } else {
@@ -1275,10 +1283,12 @@
         if (typeArguments == null) {
           assert(setOrMapType.typeArguments.length == 2);
           var keyType = DecoratedType.forImplicitType(
-              typeProvider, setOrMapType.typeArguments[0], _graph);
+              typeProvider, setOrMapType.typeArguments[0], _graph,
+              offset: node.offset);
           _currentMapKeyType = keyType;
           var valueType = DecoratedType.forImplicitType(
-              typeProvider, setOrMapType.typeArguments[1], _graph);
+              typeProvider, setOrMapType.typeArguments[1], _graph,
+              offset: node.offset);
           _currentMapValueType = valueType;
           instrumentation
               ?.implicitTypeArguments(source, node, [keyType, valueType]);
@@ -1337,6 +1347,7 @@
       return _makeNonNullLiteralType(node);
     } else if (staticElement == null) {
       assert(node.toString() == 'void');
+      return _makeNullableVoidType(node);
     } else if (staticElement.enclosingElement is ClassElement &&
         (staticElement.enclosingElement as ClassElement).isEnum) {
       return getOrComputeElementType(staticElement);
@@ -1357,7 +1368,8 @@
           _currentMapKeyType.type, _currentMapValueType.type);
       final expectedDecoratedType = DecoratedType.forImplicitType(
           typeProvider, expectedType, _graph,
-          typeArguments: [_currentMapKeyType, _currentMapValueType]);
+          typeArguments: [_currentMapKeyType, _currentMapValueType],
+          offset: node.offset);
 
       spreadTypeDecorated = _handleAssignment(node.expression,
           destinationType: expectedDecoratedType);
@@ -1368,7 +1380,7 @@
           typeProvider.iterableType2(_currentLiteralElementType.type);
       final expectedDecoratedType = DecoratedType.forImplicitType(
           typeProvider, expectedType, _graph,
-          typeArguments: [_currentLiteralElementType]);
+          typeArguments: [_currentLiteralElementType], offset: node.offset);
 
       spreadTypeDecorated = _handleAssignment(node.expression,
           destinationType: expectedDecoratedType);
@@ -1393,7 +1405,7 @@
   DecoratedType visitSuperConstructorInvocation(
       SuperConstructorInvocation node) {
     var callee = node.staticElement;
-    var nullabilityNode = NullabilityNode.forInferredType();
+    var nullabilityNode = NullabilityNode.forInferredType(offset: node.offset);
     var class_ = node.thisOrAncestorOfType<ClassDeclaration>();
     var decoratedSupertype = _decoratedClassHierarchy.getDecoratedSupertype(
         class_.declaredElement, callee.enclosingElement);
@@ -1458,7 +1470,7 @@
     node.expression.accept(this);
     // TODO(paulberry): do we need to check the expression type?  I think not.
     _flowAnalysis.handleExit();
-    var nullabilityNode = NullabilityNode.forInferredType();
+    var nullabilityNode = NullabilityNode.forInferredType(offset: node.offset);
     _graph.makeNonNullable(nullabilityNode, ThrowOrigin(source, node));
     return DecoratedType(node.staticType, nullabilityNode);
   }
@@ -1646,9 +1658,9 @@
   @override
   void _connect(
       NullabilityNode source, NullabilityNode destination, EdgeOrigin origin,
-      {bool hard = false}) {
+      {bool hard = false, bool checkable = true}) {
     var edge = _graph.connect(source, destination, origin,
-        hard: hard, guards: _guards);
+        hard: hard, checkable: checkable, guards: _guards);
     if (origin is ExpressionChecksOrigin) {
       origin.checks.edges.add(edge);
     }
@@ -1677,8 +1689,9 @@
     // expression, since all we are going to do is cause a single graph edge to
     // be built; it is sufficient to pass in any decorated type whose node is
     // non-nullable.  So we use `Object`.
-    var nullabilityNode = NullabilityNode.forInferredType();
-    _graph.makeNonNullable(
+    var nullabilityNode =
+        NullabilityNode.forInferredType(offset: expression.offset);
+    _graph.makeNonNullableUnion(
         nullabilityNode, NonNullableUsageOrigin(source, expression));
     return DecoratedType(typeProvider.objectType, nullabilityNode);
   }
@@ -1719,6 +1732,10 @@
 
     if (type.isDynamic || type.isVoid) {
       return DecoratedType(type, node);
+    } else if (leftType.isBottom) {
+      return right.withNode(node);
+    } else if (rightType.isBottom) {
+      return left.withNode(node);
     } else if (type is InterfaceType) {
       if (type.typeArguments.isEmpty) {
         return DecoratedType(type, node);
@@ -1848,9 +1865,10 @@
     }
   }
 
-  DecoratedType _futureOf(DecoratedType type) => DecoratedType.forImplicitType(
-      typeProvider, typeProvider.futureType2(type.type), _graph,
-      typeArguments: [type]);
+  DecoratedType _futureOf(DecoratedType type, {@required int offset}) =>
+      DecoratedType.forImplicitType(
+          typeProvider, typeProvider.futureType2(type.type), _graph,
+          typeArguments: [type], offset: offset);
 
   @override
   DecoratedType _getTypeParameterTypeBound(DecoratedType type) {
@@ -1904,7 +1922,7 @@
     try {
       sourceType = expression.accept(this);
       if (wrapFuture) {
-        sourceType = _wrapFuture(sourceType);
+        sourceType = _wrapFuture(sourceType, offset: expression.offset);
       }
       if (sourceType == null) {
         throw StateError('No type computed for ${expression.runtimeType} '
@@ -2135,7 +2153,8 @@
               _checkAssignment(origin,
                   source: overriddenParameterType,
                   destination: currentParameterType,
-                  hard: true);
+                  hard: false,
+                  checkable: false);
             }
           }
         }
@@ -2251,8 +2270,9 @@
       } else {
         if (invokeType is FunctionType) {
           var argumentTypes = typeArgumentTypes
-              .map((argType) =>
-                  DecoratedType.forImplicitType(typeProvider, argType, _graph))
+              .map((argType) => DecoratedType.forImplicitType(
+                  typeProvider, argType, _graph,
+                  offset: node.offset))
               .toList();
           instrumentation?.implicitTypeArguments(source, node, argumentTypes);
           calleeType = _handleInstantiation(calleeType, argumentTypes);
@@ -2438,23 +2458,36 @@
 
   DecoratedType _makeNonNullableBoolType(Expression expression) {
     assert(expression.staticType.isDartCoreBool);
-    var nullabilityNode = NullabilityNode.forInferredType();
-    _graph.makeNonNullable(
+    var nullabilityNode =
+        NullabilityNode.forInferredType(offset: expression.offset);
+    _graph.makeNonNullableUnion(
         nullabilityNode, NonNullableBoolTypeOrigin(source, expression));
     return DecoratedType(typeProvider.boolType, nullabilityNode);
   }
 
   DecoratedType _makeNonNullLiteralType(Expression expression,
       {List<DecoratedType> typeArguments = const []}) {
-    var nullabilityNode = NullabilityNode.forInferredType();
-    _graph.makeNonNullable(nullabilityNode, LiteralOrigin(source, expression));
+    var nullabilityNode =
+        NullabilityNode.forInferredType(offset: expression.offset);
+    _graph.makeNonNullableUnion(
+        nullabilityNode, LiteralOrigin(source, expression));
     return DecoratedType(expression.staticType, nullabilityNode,
         typeArguments: typeArguments);
   }
 
   DecoratedType _makeNullableDynamicType(AstNode astNode) {
     var decoratedType = DecoratedType.forImplicitType(
-        typeProvider, typeProvider.dynamicType, _graph);
+        typeProvider, typeProvider.dynamicType, _graph,
+        offset: astNode.offset);
+    _graph.makeNullable(
+        decoratedType.node, AlwaysNullableTypeOrigin(source, astNode));
+    return decoratedType;
+  }
+
+  DecoratedType _makeNullableVoidType(SimpleIdentifier astNode) {
+    var decoratedType = DecoratedType.forImplicitType(
+        typeProvider, typeProvider.voidType, _graph,
+        offset: astNode.offset);
     _graph.makeNullable(
         decoratedType.node, AlwaysNullableTypeOrigin(source, astNode));
     return decoratedType;
@@ -2476,8 +2509,10 @@
     }
 
     NullabilityNode makeNonNullableNode() {
-      var nullabilityNode = NullabilityNode.forInferredType();
-      _graph.makeNonNullable(nullabilityNode, ThisOrSuperOrigin(source, node));
+      var nullabilityNode =
+          NullabilityNode.forInferredType(offset: node.offset);
+      _graph.makeNonNullableUnion(
+          nullabilityNode, ThisOrSuperOrigin(source, node));
       return nullabilityNode;
     }
 
@@ -2498,9 +2533,11 @@
       final type = (_currentClassOrExtension as ExtensionElement).extendedType;
 
       if (type is InterfaceType) {
-        return DecoratedType(type, NullabilityNode.forInferredType(),
+        return DecoratedType(
+            type, NullabilityNode.forInferredType(offset: node.offset),
             typeArguments: type.typeArguments
-                .map((t) => DecoratedType(t, NullabilityNode.forInferredType()))
+                .map((t) => DecoratedType(
+                    t, NullabilityNode.forInferredType(offset: node.offset)))
                 .toList());
       } else {
         _unimplemented(node, 'extension of $type (${type.runtimeType}');
@@ -2526,9 +2563,9 @@
   /// Produce Future<flatten(T)> for some T, however, we would like to merely
   /// upcast T to that type if possible, skipping the flatten when not
   /// necessary.
-  DecoratedType _wrapFuture(DecoratedType type) {
+  DecoratedType _wrapFuture(DecoratedType type, {@required int offset}) {
     if (type.type.isDartCoreNull || type.type.isBottom) {
-      return _futureOf(type);
+      return _futureOf(type, offset: offset);
     }
 
     if (_typeSystem.isSubtypeOf(type.type, typeProvider.futureDynamicType)) {
@@ -2536,7 +2573,7 @@
           type, typeProvider.futureDynamicType.element);
     }
 
-    return _futureOf(type);
+    return _futureOf(type, offset: offset);
   }
 }
 
@@ -2557,7 +2594,8 @@
   void _checkAssignment(EdgeOrigin origin,
       {@required DecoratedType source,
       @required DecoratedType destination,
-      @required bool hard}) {
+      @required bool hard,
+      bool checkable = true}) {
     var sourceType = source.type;
     var destinationType = destination.type;
     if (!_typeSystem.isSubtypeOf(sourceType, destinationType)) {
@@ -2577,7 +2615,8 @@
       _connect(source.node, destination.node, origin, hard: hard);
       return;
     }
-    _connect(source.node, destination.node, origin, hard: hard);
+    _connect(source.node, destination.node, origin,
+        hard: hard, checkable: checkable);
     _checkAssignment_recursion(origin,
         source: source, destination: destination);
   }
@@ -2708,14 +2747,16 @@
         _checkAssignment(origin,
             source: destination.positionalParameters[i],
             destination: source.positionalParameters[i],
-            hard: false);
+            hard: false,
+            checkable: false);
       }
       for (var entry in destination.namedParameters.entries) {
         // Note: source and destination are swapped due to contravariance.
         _checkAssignment(origin,
             source: entry.value,
             destination: source.namedParameters[entry.key],
-            hard: false);
+            hard: false,
+            checkable: false);
       }
     } else if (destinationType.isDynamic || sourceType.isDynamic) {
       // ok; nothing further to do.
@@ -2760,6 +2801,26 @@
         // Nothing to do.
         return;
       }
+    } else if (source.type.isDartAsyncFutureOr) {
+      if (destination.type.isDartAsyncFuture) {
+        // FutureOr<T?> is nullable, so the Future<T> should be nullable too.
+        _connect(source.typeArguments[0].node, destination.node, origin,
+            hard: hard);
+        _checkDowncast(origin,
+            source: source.typeArguments[0],
+            destination: destination.typeArguments[0],
+            hard: false);
+      } else if (destination.type.isDartAsyncFutureOr) {
+        _checkDowncast(origin,
+            source: source.typeArguments[0],
+            destination: destination.typeArguments[0],
+            hard: false);
+      } else {
+        _checkDowncast(origin,
+            source: source.typeArguments[0],
+            destination: destination,
+            hard: false);
+      }
     } else if (destinationType is InterfaceType) {
       if (source.type is InterfaceType) {
         final target = _decoratedClassHierarchy.asInstanceOf(
@@ -2789,7 +2850,7 @@
 
   void _connect(
       NullabilityNode source, NullabilityNode destination, EdgeOrigin origin,
-      {bool hard = false});
+      {bool hard = false, bool checkable = true});
 
   /// Given a [type] representing a type parameter, retrieves the type's bound.
   DecoratedType _getTypeParameterTypeBound(DecoratedType type);
diff --git a/pkg/nnbd_migration/lib/src/edit_plan.dart b/pkg/nnbd_migration/lib/src/edit_plan.dart
index d844505..907e619 100644
--- a/pkg/nnbd_migration/lib/src/edit_plan.dart
+++ b/pkg/nnbd_migration/lib/src/edit_plan.dart
@@ -298,6 +298,17 @@
     return (plan as NodeProducingEditPlan)._getChanges(false);
   }
 
+  /// Creates a new edit plan that inserts the text indicated by [edits] at the
+  /// given [offset].
+  ///
+  /// The created edit will have the given [parentNode].  In general this should
+  /// be the innermost AST node containing the given [offset].
+  EditPlan insertText(AstNode parentNode, int offset, List<AtomicEdit> edits) {
+    assert(!edits.any((edit) => !edit.isInsertion),
+        'All edits should be insertions');
+    return _TokenChangePlan(parentNode, {offset: edits});
+  }
+
   /// Creates a new edit plan that consists of executing [innerPlan], and then
   /// appending a `?`, to make a type nullable.
   ///
@@ -421,64 +432,23 @@
 
   /// Creates a new edit plan that removes null awareness from [sourceNode].
   ///
-  /// Optional arguments [targetPlan], [methodNamePlan], [typeArgumentsPlan],
-  /// and [argumentListPlan] indicate what changes should be made to the node's
-  /// target, method name, type arguments, and argument list, respectively.
-  ///
-  /// Optional argument [info] contains information about why the change was
-  /// made.
-  NodeProducingEditPlan removeNullAwarenessFromMethodInvocation(
-      MethodInvocation sourceNode,
-      {NodeProducingEditPlan targetPlan,
-      NodeProducingEditPlan methodNamePlan,
-      NodeProducingEditPlan typeArgumentsPlan,
-      NodeProducingEditPlan argumentListPlan,
-      AtomicEditInfo info}) {
-    assert(sourceNode.operator.type == TokenType.QUESTION_PERIOD);
-    var builder = _PassThroughBuilderImpl(sourceNode);
-    if (targetPlan != null) {
-      builder._handleNodeProducingEditPlan(targetPlan);
+  /// The created edit plan should be inserted into the list of inner plans for
+  /// a pass-through plan targeted at the source node.  See [passThrough].
+  EditPlan removeNullAwareness(Expression sourceNode, {AtomicEditInfo info}) {
+    Token operator;
+    if (sourceNode is MethodInvocation) {
+      operator = sourceNode.operator;
+    } else if (sourceNode is PropertyAccess) {
+      operator = sourceNode.operator;
+    } else {
+      throw StateError(
+          'Tried to remove null awareness from an unexpected node type: '
+          '${sourceNode.runtimeType}');
     }
-    builder.changes += {
-      sourceNode.operator.offset: [AtomicEdit.delete(1, info: info)]
-    };
-    if (methodNamePlan != null) {
-      builder._handleNodeProducingEditPlan(methodNamePlan);
-    }
-    if (typeArgumentsPlan != null) {
-      builder._handleNodeProducingEditPlan(typeArgumentsPlan);
-    }
-    if (argumentListPlan != null) {
-      builder._handleNodeProducingEditPlan(argumentListPlan);
-    }
-    return builder.finish(this);
-  }
-
-  /// Creates a new edit plan that removes null awareness from [sourceNode].
-  ///
-  /// Optional arguments [targetPlan] and, [propertyNamePlan] indicate what
-  /// changes should be made to the node's target and property name,
-  /// respectively.
-  ///
-  /// Optional argument [info] contains information about why the change was
-  /// made.
-  NodeProducingEditPlan removeNullAwarenessFromPropertyAccess(
-      PropertyAccess sourceNode,
-      {NodeProducingEditPlan targetPlan,
-      NodeProducingEditPlan propertyNamePlan,
-      AtomicEditInfo info}) {
-    assert(sourceNode.operator.type == TokenType.QUESTION_PERIOD);
-    var builder = _PassThroughBuilderImpl(sourceNode);
-    if (targetPlan != null) {
-      builder._handleNodeProducingEditPlan(targetPlan);
-    }
-    builder.changes += {
-      sourceNode.operator.offset: [AtomicEdit.delete(1, info: info)]
-    };
-    if (propertyNamePlan != null) {
-      builder._handleNodeProducingEditPlan(propertyNamePlan);
-    }
-    return builder.finish(this);
+    assert(operator.type == TokenType.QUESTION_PERIOD);
+    return _TokenChangePlan(sourceNode, {
+      operator.offset: [AtomicEdit.delete(1, info: info)]
+    });
   }
 
   /// Creates a new edit plan that replaces the contents of [sourceNode] with
@@ -497,6 +467,8 @@
       {Precedence precedence = Precedence.primary,
       bool endsInCascade = false,
       AtomicEditInfo info}) {
+    assert(!replacement.any((edit) => !edit.isInsertion),
+        'All edits should be insertions');
     return _SimpleEditPlan(sourceNode, precedence, endsInCascade, {
       sourceNode.offset: [
         AtomicEdit.delete(sourceNode.length, info: info),
@@ -505,6 +477,23 @@
     });
   }
 
+  /// Creates a new edit plan that replaces [token] with the given [replacement]
+  /// text.
+  ///
+  /// [parentNode] should be the innermost AST node containing [token].
+  EditPlan replaceToken(
+      AstNode parentNode, Token token, List<AtomicEdit> replacement,
+      {AtomicEditInfo info}) {
+    assert(!replacement.any((edit) => !edit.isInsertion),
+        'All edits should be insertions');
+    return _TokenChangePlan(parentNode, {
+      token.offset: [
+        AtomicEdit.delete(token.length, info: info),
+        ...replacement
+      ]
+    });
+  }
+
   /// Creates a new edit plan that consists of executing [innerPlan], and then
   /// surrounding it with [prefix] and [suffix] text.  This could be used, for
   /// example, to add a cast.
@@ -1277,6 +1266,9 @@
         planIndex++;
       } else if (innerPlan is _RemoveEditPlan) {
         planIndex = _handleRemoveEditPlans(innerPlan, planIndex);
+      } else if (innerPlan is _TokenChangePlan) {
+        changes += innerPlan.changes;
+        planIndex++;
       } else {
         throw UnimplementedError('Unrecognized inner plan type');
       }
@@ -1453,6 +1445,21 @@
   }
 }
 
+/// [EditPlan] representing a change (or changes) to be made to a token in the
+/// [parentNode].
+///
+/// This is used, for example, to change the `?.` token of a [MethodInvocation]
+/// or [PropertyAccess] to `.`.
+class _TokenChangePlan extends EditPlan {
+  @override
+  final AstNode parentNode;
+
+  /// The changes to be made.
+  final Map<int, List<AtomicEdit>> changes;
+
+  _TokenChangePlan(this.parentNode, this.changes) : super._();
+}
+
 /// Extension containing useful operations on a list of [AtomicEdit]s.
 extension AtomicEditList on List<AtomicEdit> {
   /// Converts a list of [AtomicEdits] to a single [SourceEdit] by concatenating
diff --git a/pkg/nnbd_migration/lib/src/fantasyland/fantasy_repo.dart b/pkg/nnbd_migration/lib/src/fantasyland/fantasy_repo.dart
index f063abb..59f3d8e 100644
--- a/pkg/nnbd_migration/lib/src/fantasyland/fantasy_repo.dart
+++ b/pkg/nnbd_migration/lib/src/fantasyland/fantasy_repo.dart
@@ -4,29 +4,87 @@
 
 import 'dart:io';
 
+import 'package:nnbd_migration/src/utilities/subprocess_launcher.dart';
 import 'package:path/path.dart' as path;
 
 const _github = 'git@github.com';
+const _httpGithub = 'https://github.com';
+
+final Map<String, FantasyRepoSettings> _repoTable = {
+  'archive':
+      FantasyRepoSettings('archive', '$_github:brendan-duncan/archive.git'),
+  'build_verify': FantasyRepoSettings(
+      'build_verify', '$_github:brendan-duncan/build_verify.git'),
+  'build_version':
+      FantasyRepoSettings('build_version', '$_github:kevmoo/build_version.git'),
+  'csv': FantasyRepoSettings('csv', '$_github:close2/csv.git'),
+  'git': FantasyRepoSettings('git', '$_github:kevmoo/git.git'),
+  'node_interop': FantasyRepoSettings(
+      'node_interop', '$_github:pulyaevskiy/node-interop.git'),
+  'node_preamble': FantasyRepoSettings(
+      'package_config', '$_github:mbullington/node_preamble.dart.git'),
+  'package_config': FantasyRepoSettings(
+      'package_config', '$_github:dart-lang/package_config', 'master', '1.1.0'),
+  'source_gen_test': FantasyRepoSettings(
+      'source_gen_test', '$_github:kevmoo/source_gen_test.git'),
+  'quiver-dart':
+      FantasyRepoSettings('quiver-dart', '$_github:google/quiver-dart.git'),
+  'uuid': FantasyRepoSettings('uuid', '$_github:Daegalus/dart-uuid.git'),
+};
+
+class FantasyRepoCloneException extends FantasyRepoException {
+  FantasyRepoCloneException(String message) : super(message);
+
+  String toString() {
+    if (message == null) return "FantasyRepoCloneException";
+    return "FantasyRepoCloneException: $message";
+  }
+}
+
+class FantasyRepoUpdateException extends FantasyRepoException {
+  FantasyRepoUpdateException(String message) : super(message);
+
+  String toString() {
+    if (message == null) return "FantasyRepoUpdateException";
+    return "FantasyRepoUpdateException: $message";
+  }
+}
+
+class FantasyRepoException implements Exception {
+  final message;
+
+  FantasyRepoException(this.message);
+
+  String toString() {
+    if (message == null) return "FantasyRepoException";
+    return "FantasyRepoException: $message";
+  }
+}
 
 /// Data class to contain settings for a given repository.
 ///
 /// A repository can be referred to by one or more [FantasySubPackageSettings].
 class FantasyRepoSettings {
-  final String repoName;
+  final String name;
   final String clone;
   final String branch;
   final String revision;
 
-  FantasyRepoSettings(this.repoName, this.clone, this.branch, this.revision);
+  FantasyRepoSettings(this.name, this.clone,
+      [this.branch = 'master', this.revision = 'master']);
 
+  static RegExp _dotDart = RegExp(r'[.]dart$');
+
+  /// Build repository settings from a hard-coded repository name.
   factory FantasyRepoSettings.fromName(String repoName) {
-    switch (repoName) {
-
-      /// TODO(jcollins-g): Port table over from add_repo_to_workspace.
-      default:
-        return FantasyRepoSettings(
-            repoName, '$_github:dart-lang/$repoName.git', 'master', 'master');
+    if (_repoTable.containsKey(repoName)) {
+      return _repoTable[repoName];
     }
+    if (_dotDart.hasMatch(repoName)) {
+      return FantasyRepoSettings(repoName, '$_github:google/$repoName.git');
+    }
+    return FantasyRepoSettings(
+        repoName, '$_github:dart-lang/$repoName.git', 'master', 'master');
   }
 
   @override
@@ -35,7 +93,7 @@
   @override
   bool operator ==(other) {
     return other is FantasyRepoSettings &&
-        (other.repoName == repoName &&
+        (other.name == name &&
             other.clone == clone &&
             other.branch == branch &&
             other.revision == revision);
@@ -43,26 +101,129 @@
 
   @override
   String toString() =>
-      'FantasyRepoSettings("$repoName", "$clone", "$branch", "$revision")';
+      'FantasyRepoSettings("$name", "$clone", "$branch", "$revision")';
 }
 
-const _repoSubDir = '_repo';
-
 /// Represent a single git clone that may be referred to by one or more
 /// [FantasySubPackage]s.
 class FantasyRepo {
   final String name;
   final FantasyRepoSettings repoSettings;
   final Directory repoRoot;
+  final File Function(String) fileBuilder;
 
-  FantasyRepo._(this.name, this.repoSettings, this.repoRoot);
+  FantasyRepo._(this.repoSettings, this.repoRoot,
+      {File Function(String) fileBuilder})
+      : name = repoSettings.name,
+        fileBuilder = fileBuilder ?? ((s) => File(s));
 
   static Future<FantasyRepo> buildFrom(
-      String repoName, Directory workspaceRoot) async {
-    FantasyRepoSettings repoSettings = FantasyRepoSettings.fromName(repoName);
-    Directory repoRoot = Directory(path
-        .canonicalize(path.join(workspaceRoot.path, _repoSubDir, repoName)));
-    // TODO(jcollins-g): implement git operations, cloning, etc.
-    return FantasyRepo._(repoName, repoSettings, repoRoot);
+      FantasyRepoSettings repoSettings, Directory repoRoot,
+      {SubprocessLauncher launcher, File Function(String) fileBuilder}) async {
+    FantasyRepo newRepo =
+        FantasyRepo._(repoSettings, repoRoot, fileBuilder: fileBuilder);
+    if (launcher == null) {
+      launcher = SubprocessLauncher('FantasyRepo.buildFrom-${newRepo.name}');
+    }
+    await newRepo._init(launcher);
+    return newRepo;
+  }
+
+  bool _isInitialized = false;
+
+  /// Call exactly once per [FantasyRepo].
+  ///
+  /// May throw [FantasyRepoException] in the event of problems and does
+  /// not clean up filesystem state.
+  Future<void> _init(SubprocessLauncher launcher) async {
+    assert(_isInitialized == false);
+    if (await repoRoot.exists()) {
+      await _update(launcher);
+      // TODO(jcollins-g): handle "update" of pinned revision edge case
+    } else {
+      await _clone(launcher);
+    }
+    _isInitialized = true;
+    return;
+  }
+
+  /// Configure a git repository locally and initialize it.
+  ///
+  /// Throws [FantasyRepoCloneException] in the event we can not finish
+  /// initializing.
+  Future<void> _clone(SubprocessLauncher launcher) async {
+    assert(_isInitialized == false);
+    if (!await repoRoot.parent.exists()) {
+      await repoRoot.parent.create(recursive: true);
+    }
+    await launcher.runStreamed('git', ['init', repoRoot.path]);
+    await launcher.runStreamed(
+        'git',
+        [
+          'remote',
+          'add',
+          'origin',
+          '-t',
+          repoSettings.branch,
+          repoSettings.clone
+        ],
+        workingDirectory: repoRoot.path);
+
+    String cloneHttp =
+        repoSettings.clone.replaceFirst('$_github:', '$_httpGithub/');
+    await launcher.runStreamed('git',
+        ['remote', 'add', 'originHTTP', '-t', repoSettings.branch, cloneHttp],
+        workingDirectory: repoRoot.path);
+
+    // Do not get the working directory wrong on this command or it could
+    // alter a user's repository config based on the CWD, which is bad.  Other
+    // commands in [FantasyRepo] will not fail silently with permanent,
+    // confusing results, but this one can.
+    await launcher.runStreamed('git', ['config', 'core.sparsecheckout', 'true'],
+        workingDirectory: repoRoot.path);
+
+    File sparseCheckout = fileBuilder(
+        path.join(repoRoot.path, '.git', 'info', 'sparse-checkout'));
+    await sparseCheckout.writeAsString([
+      '**\n',
+      '!**/.packages\n',
+      '!**/pubspec.lock\n',
+      '!**/.dart_tool/package_config.json\n'
+    ].join());
+    try {
+      await _update(launcher);
+    } catch (e) {
+      if (e is FantasyRepoUpdateException) {
+        throw FantasyRepoCloneException(
+            'Unable to initialize clone for: $repoSettings');
+      }
+      // Other kinds of exceptions are not expected, so rethrow.
+      rethrow;
+    }
+  }
+
+  Future<void> _update(SubprocessLauncher launcher) async {
+    assert(_isInitialized == false);
+    try {
+      List<String> args;
+      if (repoSettings.branch == 'master') {
+        args = [
+          'pull',
+          '--depth=1',
+          '--rebase',
+          'originHTTP',
+          repoSettings.revision
+        ];
+      } else {
+        args = ['pull', '--rebase', 'originHTTP', repoSettings.revision];
+      }
+      await launcher.runStreamed('git', args, workingDirectory: repoRoot.path);
+    } catch (e) {
+      if (e is ProcessException) {
+        throw FantasyRepoUpdateException(
+            'Unable to update clone for: $repoSettings');
+      }
+      rethrow;
+    }
   }
 }
diff --git a/pkg/nnbd_migration/lib/src/fantasyland/fantasy_sub_package.dart b/pkg/nnbd_migration/lib/src/fantasyland/fantasy_sub_package.dart
index 0f12e7d..dcefdc9 100644
--- a/pkg/nnbd_migration/lib/src/fantasyland/fantasy_sub_package.dart
+++ b/pkg/nnbd_migration/lib/src/fantasyland/fantasy_sub_package.dart
@@ -2,26 +2,108 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'dart:io';
-
 import 'package:nnbd_migration/src/fantasyland/fantasy_repo.dart';
-import 'package:path/path.dart' as path;
+import 'package:nnbd_migration/src/fantasyland/fantasy_workspace.dart';
+
+final Map<String, FantasySubPackageSettings> _subPackageTable = {
+  '_fe_analyzer_shared': FantasySubPackageSettings('_fe_analyzer_shared',
+      FantasyRepoSettings.fromName('sdk'), 'pkg/_fe_analyzer_shared'),
+  'analysis_tool': FantasySubPackageSettings('analysis_tool',
+      FantasyRepoSettings.fromName('sdk'), 'pkg/analysis_tool'),
+  'analyzer': FantasySubPackageSettings(
+      'analyzer', FantasyRepoSettings.fromName('sdk'), 'pkg/analyzer'),
+  'build': FantasySubPackageSettings(
+      'build', FantasyRepoSettings.fromName('build'), 'build'),
+  'build_config': FantasySubPackageSettings(
+      'build_config', FantasyRepoSettings.fromName('build'), 'build_config'),
+  'build_daemon': FantasySubPackageSettings(
+      'build_daemon', FantasyRepoSettings.fromName('build'), 'build_daemon'),
+  'build_integration': FantasySubPackageSettings('build_integration',
+      FantasyRepoSettings.fromName('sdk'), 'pkg/build_integration'),
+  'build_modules': FantasySubPackageSettings(
+      'build_modules', FantasyRepoSettings.fromName('build'), 'build_modules'),
+  'build_node_compilers': FantasySubPackageSettings('build_node_compilers',
+      FantasyRepoSettings.fromName('node-interop'), 'build_node_compilers'),
+  'build_resolvers': FantasySubPackageSettings('build_resolvers',
+      FantasyRepoSettings.fromName('build'), 'build_resolvers'),
+  'build_runner': FantasySubPackageSettings(
+      'build_runner', FantasyRepoSettings.fromName('build'), 'build_runner'),
+  'build_runner_core': FantasySubPackageSettings('build_runner_core',
+      FantasyRepoSettings.fromName('build'), 'build_runner_core'),
+  'build_test': FantasySubPackageSettings(
+      'build_test', FantasyRepoSettings.fromName('build'), 'build_test'),
+  'build_vm_compilers': FantasySubPackageSettings('build_vm_compilers',
+      FantasyRepoSettings.fromName('build'), 'build_vm_compilers'),
+  'build_web_compilers': FantasySubPackageSettings('build_web_compilers',
+      FantasyRepoSettings.fromName('build'), 'build_web_compilers'),
+  'built_collection': FantasySubPackageSettings('built_collection',
+      FantasyRepoSettings.fromName('built_collection.dart'), '.'),
+  'built_value': FantasySubPackageSettings('built_value',
+      FantasyRepoSettings.fromName('built_value.dart'), 'built_value'),
+  'built_value_generator': FantasySubPackageSettings(
+      'built_value_generator',
+      FantasyRepoSettings.fromName('built_value.dart'),
+      'built_value_generator'),
+  'checked_yaml': FantasySubPackageSettings('checked_yaml',
+      FantasyRepoSettings.fromName('json_serializable'), 'checked_yaml'),
+  'expect': FantasySubPackageSettings(
+      'expect', FantasyRepoSettings.fromName('sdk'), 'pkg/expect'),
+  'front_end': FantasySubPackageSettings(
+      'front_end', FantasyRepoSettings.fromName('sdk'), 'pkg/front_end'),
+  'grinder': FantasySubPackageSettings(
+      'grinder', FantasyRepoSettings.fromName('grinder.dart'), '.'),
+  'kernel': FantasySubPackageSettings(
+      'kernel', FantasyRepoSettings.fromName('sdk'), 'pkg/kernel'),
+  'meta': FantasySubPackageSettings(
+      'meta', FantasyRepoSettings.fromName('sdk'), 'pkg/meta'),
+  'node_interop': FantasySubPackageSettings('node_interop',
+      FantasyRepoSettings.fromName('node-interop'), 'node_interop'),
+  'node_io': FantasySubPackageSettings(
+      'node_io', FantasyRepoSettings.fromName('node-interop'), 'node_io'),
+  'js': FantasySubPackageSettings(
+      'js', FantasyRepoSettings.fromName('sdk'), 'pkg/js'),
+  'json_annotation': FantasySubPackageSettings('json_annotation',
+      FantasyRepoSettings.fromName('json_serializable'), 'json_annotation'),
+  'json_serializable': FantasySubPackageSettings('json_serializable',
+      FantasyRepoSettings.fromName('json_serializable'), 'json_serializable'),
+  'package_config': FantasySubPackageSettings(
+      'package_config', FantasyRepoSettings.fromName('package_config'), '.'),
+  'protobuf': FantasySubPackageSettings(
+      'protobuf', FantasyRepoSettings.fromName('protobuf'), 'protobuf'),
+  'scratch_space': FantasySubPackageSettings(
+      'scratch_space', FantasyRepoSettings.fromName('build'), 'scratch_space'),
+  'source_gen': FantasySubPackageSettings(
+      'source_gen', FantasyRepoSettings.fromName('source_gen'), 'source_gen'),
+  'source_gen_test': FantasySubPackageSettings(
+      'source_gen_test', FantasyRepoSettings.fromName('source_gen_test'), '.'),
+  'test': FantasySubPackageSettings(
+      'test', FantasyRepoSettings.fromName('test'), 'pkgs/test'),
+  'test_api': FantasySubPackageSettings(
+      'test_api', FantasyRepoSettings.fromName('test'), 'pkgs/test_api'),
+  'test_core': FantasySubPackageSettings(
+      'test_core', FantasyRepoSettings.fromName('test'), 'pkgs/test_core'),
+  'testing': FantasySubPackageSettings(
+      'testing', FantasyRepoSettings.fromName('sdk'), 'pkg/testing'),
+  'vm_service': FantasySubPackageSettings(
+      'vm_service', FantasyRepoSettings.fromName('sdk'), 'pkg/vm_service'),
+  'quiver': FantasySubPackageSettings(
+      'quiver', FantasyRepoSettings.fromName('quiver-dart'), '.'),
+};
 
 /// Data class containing settings for a package within a [FantasyWorkspaceImpl].
 class FantasySubPackageSettings {
   final String name;
-  final String repoName;
+  final FantasyRepoSettings repoSettings;
   final String subDir;
 
-  FantasySubPackageSettings(this.name, this.repoName, this.subDir);
+  FantasySubPackageSettings(this.name, this.repoSettings, [this.subDir = '.']);
 
+  /// Build settings just from a name in a mostly-hardcoded table.
   factory FantasySubPackageSettings.fromName(String name) {
-    switch (name) {
-
-      /// TODO(jcollins-g): Port table over from add_package_to_workspace.
-      default:
-        return FantasySubPackageSettings(name, name, '.');
+    if (_subPackageTable.containsKey(name)) {
+      return _subPackageTable[name];
     }
+    return FantasySubPackageSettings(name, FantasyRepoSettings.fromName(name));
   }
 
   @override
@@ -31,13 +113,13 @@
   bool operator ==(other) {
     return other is FantasySubPackageSettings &&
         (other.name == name &&
-            other.repoName == repoName &&
-            other.subDir == other.subDir);
+            other.repoSettings == repoSettings &&
+            other.subDir == subDir);
   }
 
   @override
   String toString() =>
-      'FantasySubPackageSettings("$name", "$repoName", "$subDir")';
+      'FantasySubPackageSettings("$name", ${repoSettings.toString()}, "$subDir")';
 }
 
 /// Represents one package within a [FantasyWorkspaceImpl].
@@ -45,28 +127,12 @@
 /// A `FantasySubPackage` differs from a normal package in that Dart code within
 /// it depends on a global .packages file to resolve symbols.
 class FantasySubPackage {
-  final String name;
   final FantasyRepo containingRepo;
+  final FantasyWorkspace containingWorkspace;
+  final String name;
   final FantasySubPackageSettings packageSettings;
 
-  /// The symlink in the workspace directory whose [Link.target] is the root of
-  /// the package.
-  final Link packageSymlink;
-
-  FantasySubPackage._(this.name, this.containingRepo, this.packageSettings,
-      this.packageSymlink);
-
-  static Future<FantasySubPackage> buildFrom(String packageName,
-      FantasyRepo containingRepo, Directory workspaceRoot) async {
-    FantasySubPackageSettings packageSettings =
-        FantasySubPackageSettings.fromName(packageName);
-    Link packageSymlink = Link(path.join(workspaceRoot.path, packageName));
-    if (!await packageSymlink.exists()) {
-      await packageSymlink.create(path.canonicalize(
-          path.join(containingRepo.repoRoot.path, packageSettings.subDir)));
-    }
-    // TODO(jcollins-g): implement .packages file handling here
-    return FantasySubPackage._(
-        packageName, containingRepo, packageSettings, packageSymlink);
-  }
+  FantasySubPackage(
+      this.packageSettings, this.containingRepo, this.containingWorkspace)
+      : name = packageSettings.name;
 }
diff --git a/pkg/nnbd_migration/lib/src/fantasyland/fantasy_workspace.dart b/pkg/nnbd_migration/lib/src/fantasyland/fantasy_workspace.dart
index f93b888..d9ec224 100644
--- a/pkg/nnbd_migration/lib/src/fantasyland/fantasy_workspace.dart
+++ b/pkg/nnbd_migration/lib/src/fantasyland/fantasy_workspace.dart
@@ -5,33 +5,19 @@
 import 'dart:io';
 
 import 'package:nnbd_migration/src/fantasyland/fantasy_sub_package.dart';
-import 'package:nnbd_migration/src/fantasyland/fantasy_repo.dart';
 import 'package:nnbd_migration/src/fantasyland/fantasy_workspace_impl.dart';
 
+export 'package:nnbd_migration/src/fantasyland/fantasy_sub_package.dart';
+
 /// Represent a single [FantasyWorkspace].
 abstract class FantasyWorkspace {
   Directory get workspaceRoot;
 
   /// Fully initialized subpackages.
-  ///
-  /// This is fully populated once all [addPackageToWorkspace] futures are
-  /// complete.
-  Map<String, FantasySubPackage> subPackages = {};
-
-  /// Asynchronously add one package to the workspace.
-  ///
-  /// Completes when the given package and all its dependencies (implementation
-  /// dependent) are added to the workspace.
-  Future<void> addPackageToWorkspace(String packageName);
-
-  /// Asynchronously add one repository to the workspace.
-  ///
-  /// Completes when the repository is synced and cloned.
-  /// Completes immediately if the [repoName] is already added.
-  Future<FantasyRepo> addRepoToWorkspace(String repoName);
+  Map<String, FantasySubPackage> subPackages;
 }
 
-/// Build a "fantasyland"style repository structure suitable for applying
+/// Build a "fantasyland"-style repository structure suitable for applying
 /// a migration to.
 Future<FantasyWorkspace> buildFantasyLand(String topLevelPackage,
     List<String> extraPackages, Directory fantasyLandDir) {
diff --git a/pkg/nnbd_migration/lib/src/fantasyland/fantasy_workspace_impl.dart b/pkg/nnbd_migration/lib/src/fantasyland/fantasy_workspace_impl.dart
index 4f1eb20..9ee506c 100644
--- a/pkg/nnbd_migration/lib/src/fantasyland/fantasy_workspace_impl.dart
+++ b/pkg/nnbd_migration/lib/src/fantasyland/fantasy_workspace_impl.dart
@@ -7,6 +7,7 @@
 import 'package:nnbd_migration/src/fantasyland/fantasy_repo.dart';
 import 'package:nnbd_migration/src/fantasyland/fantasy_sub_package.dart';
 import 'package:nnbd_migration/src/fantasyland/fantasy_workspace.dart';
+import 'package:path/path.dart' as path;
 
 abstract class FantasyWorkspaceImpl extends FantasyWorkspace {
   @override
@@ -17,12 +18,12 @@
   /// Repositories on which [addRepoToWorkspace] has been called.
   Map<String, Future<FantasyRepo>> _repos = {};
 
-  /// Sub-packages on which [addPackageToWorkspace] has been called.
+  /// Sub-packages on which [addPackageNameToWorkspace] has been called.
   Map<String, Future<List<String>>> _packageDependencies = {};
 
   /// Fully initialized subpackages.
   ///
-  /// This is complete once all [addPackageToWorkspace] futures are complete.
+  /// This is complete once all [addPackageNameToWorkspace] futures are complete.
   /// futures are complete.
   Map<String, FantasySubPackage> subPackages = {};
 
@@ -40,24 +41,30 @@
   /// Returns a list of packageNames that needed to be added as dependencies.
   ///
   /// Which dependencies are automatically added is implementation dependent.
-  Future<List<String>> addPackageToWorkspaceInternal(String packageName);
+  Future<List<String>> addPackageNameToWorkspaceInternal(String packageName);
 
-  Future<void> addPackageToWorkspace(String packageName) async {
+  Future<void> addPackageNameToWorkspace(String packageName) async {
     if (_packageDependencies.containsKey(packageName)) return;
     _packageDependencies[packageName] =
-        addPackageToWorkspaceInternal(packageName);
-    return Future.wait((await _packageDependencies[packageName])
-        .map((n) => addPackageToWorkspace(n)));
+        addPackageNameToWorkspaceInternal(packageName);
+    return Future.wait([
+      for (var n in await _packageDependencies[packageName])
+        addPackageNameToWorkspace(n)
+    ]);
   }
 
+  static const _repoSubDir = '_repo';
+
   /// Asynchronously add one repository to the workspace.
   ///
   /// Completes when the repository is synced and cloned.
-  /// Completes immediately if the [repoName] is already added.
-  Future<FantasyRepo> addRepoToWorkspace(String repoName) {
-    if (_repos.containsKey(repoName)) return _repos[repoName];
-    _repos[repoName] = FantasyRepo.buildFrom(repoName, workspaceRoot);
-    return _repos[repoName];
+  /// Completes immediately if the [name] is already added.
+  Future<FantasyRepo> addRepoToWorkspace(FantasyRepoSettings repoSettings) {
+    if (_repos.containsKey(repoSettings.name)) return _repos[repoSettings.name];
+    Directory repoRoot = Directory(path.canonicalize(
+        path.join(workspaceRoot.path, _repoSubDir, repoSettings.name)));
+    _repos[repoSettings.name] = FantasyRepo.buildFrom(repoSettings, repoRoot);
+    return _repos[repoSettings.name];
   }
 }
 
@@ -79,20 +86,33 @@
         FantasyWorkspaceTopLevelDevDepsImpl._(topLevelPackage, workspaceRoot);
     await Future.wait([
       for (var n in [topLevelPackage, ...extraPackageNames])
-        workspace.addPackageToWorkspace(n)
+        workspace.addPackageNameToWorkspace(n)
     ]);
     return workspace;
   }
 
-  Future<List<String>> addPackageToWorkspaceInternal(String packageName) async {
+  Future<List<String>> addPackageNameToWorkspaceInternal(
+      String packageName) async {
     FantasySubPackageSettings packageSettings =
         FantasySubPackageSettings.fromName(packageName);
     FantasyRepo containingRepo =
-        await addRepoToWorkspace(packageSettings.repoName);
-    await FantasySubPackage.buildFrom(
-        packageName, containingRepo, workspaceRoot);
+        await addRepoToWorkspace(packageSettings.repoSettings);
+    FantasySubPackage fantasySubPackage =
+        FantasySubPackage(packageSettings, containingRepo, this);
+    subPackages[fantasySubPackage.name] = fantasySubPackage;
+
+    // Add a symlink to the top level directory.
+    Link packageSymlink =
+        Link(path.join(workspaceRoot.path, packageSettings.name));
+    if (!await packageSymlink.exists()) {
+      await packageSymlink.create(path.canonicalize(
+          path.join(containingRepo.repoRoot.path, packageSettings.subDir)));
+    }
+
+    // TODO(jcollins-g): Add to .packages / package_config.json
     if (packageName == topLevelPackage) {
-      throw UnimplementedError(); // TODO(jcollins-g): implement some dependency calculations.
+      throw UnimplementedError();
+      // TODO(jcollins-g): implement some dependency calculations inside FantasySubPackage.
     }
     return [];
   }
diff --git a/pkg/nnbd_migration/lib/src/fix_aggregator.dart b/pkg/nnbd_migration/lib/src/fix_aggregator.dart
index 2f4f372..6862421 100644
--- a/pkg/nnbd_migration/lib/src/fix_aggregator.dart
+++ b/pkg/nnbd_migration/lib/src/fix_aggregator.dart
@@ -5,101 +5,13 @@
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
+import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/src/dart/element/type.dart';
 import 'package:nnbd_migration/instrumentation.dart';
 import 'package:nnbd_migration/nnbd_migration.dart';
 import 'package:nnbd_migration/src/decorated_type.dart';
 import 'package:nnbd_migration/src/edit_plan.dart';
-
-/// Implementation of [NodeChange] representing the addition of the keyword
-/// `required` to a named parameter.
-class AddRequiredKeyword extends NestableChange {
-  /// Information about why the change should be made.
-  final AtomicEditInfo info;
-
-  const AddRequiredKeyword(this.info,
-      [NodeChange<NodeProducingEditPlan> inner = const NoChange()])
-      : super._(inner);
-
-  @override
-  EditPlan apply(AstNode node, FixAggregator aggregator) {
-    var innerPlan = inner.apply(node, aggregator);
-    return aggregator.planner.surround(innerPlan,
-        prefix: [AtomicEdit.insert('required ', info: info)]);
-  }
-}
-
-/// Implementation of [NodeChange] representing the removal of a dead branch
-/// because the conditional expression in an if statement, if element, or
-/// conditional expression has been determined to always evaluate to either
-/// `true` or `false`.
-class EliminateDeadIf extends NodeChange {
-  /// The value that the conditional expression has been determined to always
-  /// evaluate to
-  final bool conditionValue;
-
-  /// Reasons for the change.
-  final List<FixReasonInfo> reasons;
-
-  const EliminateDeadIf(this.conditionValue, {this.reasons = const []});
-
-  @override
-  EditPlan apply(AstNode node, FixAggregator aggregator) {
-    // TODO(paulberry): do we need to detect whether the condition has side
-    // effects?  For now, assuming no.
-    AstNode thenNode;
-    AstNode elseNode;
-    if (node is IfStatement) {
-      thenNode = node.thenStatement;
-      elseNode = node.elseStatement;
-    } else if (node is ConditionalExpression) {
-      thenNode = node.thenExpression;
-      elseNode = node.elseExpression;
-    } else if (node is IfElement) {
-      thenNode = node.thenElement;
-      elseNode = node.elseElement;
-    } else {
-      throw StateError(
-          "EliminateDeadIf applied to an AST node that's not an if");
-    }
-    AstNode nodeToKeep;
-    NullabilityFixDescription descriptionBefore, descriptionAfter;
-    if (conditionValue) {
-      nodeToKeep = thenNode;
-      descriptionBefore = NullabilityFixDescription.discardCondition;
-      if (elseNode == null) {
-        descriptionAfter = descriptionBefore;
-      } else {
-        descriptionAfter = NullabilityFixDescription.discardElse;
-      }
-    } else {
-      nodeToKeep = elseNode;
-      descriptionBefore =
-          descriptionAfter = NullabilityFixDescription.discardThen;
-    }
-    if (nodeToKeep == null ||
-        nodeToKeep is Block && nodeToKeep.statements.isEmpty) {
-      var info = AtomicEditInfo(NullabilityFixDescription.discardIf, reasons);
-      return aggregator.planner.removeNode(node, info: info);
-    }
-    var infoBefore = AtomicEditInfo(descriptionBefore, reasons);
-    var infoAfter = AtomicEditInfo(descriptionAfter, reasons);
-    if (nodeToKeep is Block && nodeToKeep.statements.length == 1) {
-      var singleStatement = (nodeToKeep as Block).statements[0];
-      if (singleStatement is VariableDeclarationStatement) {
-        // It's not safe to eliminate the {} because it increases the scope of
-        // the variable declarations
-      } else {
-        nodeToKeep = singleStatement;
-      }
-    }
-    return aggregator.planner.extract(
-        node, aggregator.innerPlanForNode(nodeToKeep),
-        infoBefore: infoBefore, infoAfter: infoAfter);
-  }
-
-  @override
-  String toString() => 'EliminateDeadIf($conditionValue)';
-}
+import 'package:nnbd_migration/src/fix_builder.dart';
 
 /// Visitor that combines together the changes produced by [FixBuilder] into a
 /// concrete set of source code edits using the infrastructure of [EditPlan].
@@ -117,8 +29,10 @@
 
   /// Gathers all the changes to nodes descended from [node] into a single
   /// [EditPlan].
-  NodeProducingEditPlan innerPlanForNode(AstNode node) =>
-      planner.passThrough(node, innerPlans: innerPlansForNode(node));
+  NodeProducingEditPlan innerPlanForNode(AstNode node) {
+    var innerPlans = innerPlansForNode(node);
+    return planner.passThrough(node, innerPlans: innerPlans);
+  }
 
   /// Gathers all the changes to nodes descended from [node] into a list of
   /// [EditPlan]s, one for each change.
@@ -133,11 +47,22 @@
     }
   }
 
+  /// Gathers all the changes to [node] and its descendants into a single
+  /// [EditPlan].
+  EditPlan planForNode(AstNode node) {
+    var change = _changes[node];
+    if (change != null) {
+      return change._apply(node, this);
+    } else {
+      return planner.passThrough(node, innerPlans: innerPlansForNode(node));
+    }
+  }
+
   @override
   void visitNode(AstNode node) {
     var change = _changes[node];
     if (change != null) {
-      var innerPlan = change.apply(node, this);
+      var innerPlan = change._apply(node, this);
       if (innerPlan != null) {
         _plans.add(innerPlan);
       }
@@ -165,71 +90,10 @@
   }
 }
 
-/// Implementation of [NodeChange] representing introduction of an explicit
-/// downcast.
-class IntroduceAs extends NestableChange {
-  /// TODO(paulberry): shouldn't be a String
-  final String type;
-
-  /// Information about why the change should be made.
-  final AtomicEditInfo info;
-
-  const IntroduceAs(this.type, this.info,
-      [NodeChange<NodeProducingEditPlan> inner = const NoChange()])
-      : super._(inner);
-
-  @override
-  EditPlan apply(AstNode node, FixAggregator aggregator) {
-    var innerPlan = inner.apply(node, aggregator);
-    return aggregator.planner.addBinaryPostfix(innerPlan, TokenType.AS, type);
-  }
-}
-
-/// Implementation of [NodeChange] representing the addition of a trailing `?`
-/// to a type.
-class MakeNullable extends NestableChange {
-  /// The decorated type to which a question mark is being added.
-  final DecoratedType decoratedType;
-
-  const MakeNullable(this.decoratedType,
-      [NodeChange<NodeProducingEditPlan> inner = const NoChange()])
-      : super._(inner);
-
-  @override
-  EditPlan apply(AstNode node, FixAggregator aggregator) {
-    var innerPlan = inner.apply(node, aggregator);
-    return aggregator.planner.makeNullable(innerPlan,
-        info: AtomicEditInfo(
-            NullabilityFixDescription.makeTypeNullable(
-                decoratedType.type.toString()),
-            [decoratedType.node]));
-  }
-}
-
-/// Shared base class for [NodeChange]s that are based on an [inner] change.
-abstract class NestableChange extends NodeChange {
-  /// The change that should be applied first, before applying this change.
-  final NodeChange<NodeProducingEditPlan> inner;
-
-  const NestableChange._(this.inner);
-}
-
-/// Implementation of [NodeChange] representing no change at all.  This class
-/// is intended to be used as a base class for changes that wrap around other
-/// changes.
-class NoChange extends NodeChange<NodeProducingEditPlan> {
-  const NoChange();
-
-  @override
-  NodeProducingEditPlan apply(AstNode node, FixAggregator aggregator) {
-    return aggregator.innerPlanForNode(node);
-  }
-}
-
-/// Base class representing a kind of change that [FixAggregator] might make to a
-/// particular AST node.
-abstract class NodeChange<P extends EditPlan> {
-  const NodeChange();
+/// Base class representing a kind of change that [FixAggregator] might make to
+/// a particular AST node.
+abstract class NodeChange<N extends AstNode> {
+  NodeChange._();
 
   /// Applies this change to the given [node], producing an [EditPlan].  The
   /// [aggregator] may be used to gather up any edits to the node's descendants
@@ -240,102 +104,34 @@
   /// below them (e.g. dropping an unnecessary cast), so those changes need to
   /// be able to call the appropriate [aggregator] methods just on the nodes
   /// they need.
-  P apply(AstNode node, FixAggregator aggregator);
+  ///
+  /// May return `null` if no changes need to be made.
+  EditPlan _apply(N node, FixAggregator aggregator);
+
+  /// Creates the appropriate specialized kind of [NodeChange] appropriate for
+  /// the given [node].
+  static NodeChange<AstNode> create(AstNode node) =>
+      node.accept(_NodeChangeVisitor._instance);
 }
 
-/// Implementation of [NodeChange] representing the addition of a null check to
-/// an expression.
-class NullCheck extends NestableChange {
-  /// Information about why the change should be made.
-  final AtomicEditInfo info;
+/// Implementation of [NodeChange] specialized for operating on [Annotation]
+/// nodes.
+class NodeChangeForAnnotation extends NodeChange<Annotation> {
+  /// Indicates whether the node should be changed into a `required` keyword.
+  bool changeToRequiredKeyword = false;
 
-  const NullCheck(this.info,
-      [NodeChange<NodeProducingEditPlan> inner = const NoChange()])
-      : super._(inner);
+  /// If [changeToRequiredKeyword] is `true`, the information that should be
+  /// contained in the edit.
+  AtomicEditInfo changeToRequiredKeywordInfo;
+
+  NodeChangeForAnnotation() : super._();
 
   @override
-  EditPlan apply(AstNode node, FixAggregator aggregator) {
-    var innerPlan = inner.apply(node, aggregator);
-    return aggregator.planner
-        .addUnaryPostfix(innerPlan, TokenType.BANG, info: info);
-  }
-}
-
-/// Implementation of [NodeChange] representing the removal of an unnecessary
-/// cast.
-class RemoveAs extends NestableChange {
-  const RemoveAs([NodeChange<NodeProducingEditPlan> inner = const NoChange()])
-      : super._(inner);
-
-  @override
-  EditPlan apply(AstNode node, FixAggregator aggregator) {
-    return aggregator.planner.extract(
-        node, inner.apply((node as AsExpression).expression, aggregator),
-        infoAfter:
-            AtomicEditInfo(NullabilityFixDescription.removeAs, const []));
-  }
-}
-
-/// Implementation of [NodeChange] representing the removal of `?` from a `?.`
-/// in a method invocation because the target is non-nullable, or because of
-/// null shorting.
-class RemoveNullAwarenessFromMethodInvocation
-    extends NodeChange<NodeProducingEditPlan> {
-  const RemoveNullAwarenessFromMethodInvocation();
-
-  @override
-  NodeProducingEditPlan apply(AstNode node, FixAggregator aggregator) {
-    var methodInvocation = node as MethodInvocation;
-    var typeArguments = methodInvocation.typeArguments;
-    return aggregator.planner.removeNullAwarenessFromMethodInvocation(
-        methodInvocation,
-        targetPlan: aggregator.innerPlanForNode(methodInvocation.target),
-        methodNamePlan:
-            aggregator.innerPlanForNode(methodInvocation.methodName),
-        typeArgumentsPlan: typeArguments == null
-            ? null
-            : aggregator.innerPlanForNode(typeArguments),
-        argumentListPlan:
-            aggregator.innerPlanForNode(methodInvocation.argumentList),
-        info:
-            AtomicEditInfo(NullabilityFixDescription.removeNullAwareness, []));
-  }
-}
-
-/// Implementation of [NodeChange] representing the removal of `?` from a `?.`
-/// in a property access because the target is non-nullable, or because of null
-/// shorting.
-class RemoveNullAwarenessFromPropertyAccess
-    extends NodeChange<NodeProducingEditPlan> {
-  const RemoveNullAwarenessFromPropertyAccess();
-
-  @override
-  NodeProducingEditPlan apply(AstNode node, FixAggregator aggregator) {
-    var propertyAccess = node as PropertyAccess;
-    return aggregator.planner.removeNullAwarenessFromPropertyAccess(
-        propertyAccess,
-        targetPlan: aggregator.innerPlanForNode(propertyAccess.target),
-        propertyNamePlan:
-            aggregator.innerPlanForNode(propertyAccess.propertyName),
-        info:
-            AtomicEditInfo(NullabilityFixDescription.removeNullAwareness, []));
-  }
-}
-
-/// Implementation of [NodeChange] that changes an `@required` annotation into
-/// a `required` keyword.
-class RequiredAnnotationToRequiredKeyword extends NestableChange {
-  /// Information about why the change should be made.
-  final AtomicEditInfo info;
-
-  const RequiredAnnotationToRequiredKeyword(this.info,
-      [NodeChange<NodeProducingEditPlan> inner = const NoChange()])
-      : super._(inner);
-
-  @override
-  EditPlan apply(AstNode node, FixAggregator aggregator) {
-    var annotation = node as Annotation;
-    var name = annotation.name;
+  EditPlan _apply(Annotation node, FixAggregator aggregator) {
+    if (!changeToRequiredKeyword) {
+      return aggregator.innerPlanForNode(node);
+    }
+    var name = node.name;
     if (name is PrefixedIdentifier) {
       name = (name as PrefixedIdentifier).identifier;
     }
@@ -344,11 +140,363 @@
             'required') {
       // The text `required` already exists in the annotation; we can just
       // extract it.
-      return aggregator.planner
-          .extract(node, inner.apply(name, aggregator), infoBefore: info);
+      return aggregator.planner.extract(
+          node, aggregator.planForNode(name) as NodeProducingEditPlan,
+          infoBefore: changeToRequiredKeywordInfo);
     } else {
-      return aggregator.planner
-          .replace(node, [AtomicEdit.insert('required', info: info)]);
+      return aggregator.planner.replace(node,
+          [AtomicEdit.insert('required', info: changeToRequiredKeywordInfo)]);
     }
   }
 }
+
+/// Implementation of [NodeChange] specialized for operating on [AsExpression]
+/// nodes.
+class NodeChangeForAsExpression extends NodeChangeForExpression<AsExpression> {
+  /// Indicates whether the cast should be removed.
+  bool removeAs = false;
+
+  @override
+  EditPlan _apply(AsExpression node, FixAggregator aggregator) {
+    if (removeAs) {
+      return aggregator.planner.extract(node,
+          aggregator.planForNode(node.expression) as NodeProducingEditPlan,
+          infoAfter:
+              AtomicEditInfo(NullabilityFixDescription.removeAs, const []));
+    } else {
+      return super._apply(node, aggregator);
+    }
+  }
+}
+
+/// Common infrastructure used by [NodeChange] objects that operate on AST nodes
+/// with conditional behavior (if statements, if elements, and conditional
+/// expressions).
+mixin NodeChangeForConditional<N extends AstNode> on NodeChange<N> {
+  /// If not `null`, indicates that the condition expression is known to
+  /// evaluate to either `true` or `false`, so the other branch of the
+  /// conditional is dead code and should be eliminated.
+  bool conditionValue;
+
+  /// If [conditionValue] is not `null`, the reasons that should be included in
+  /// the [AtomicEditInfo] for the edit that removes the dead code.
+  List<FixReasonInfo> conditionReasons;
+
+  /// If dead code removal is warranted for [node], returns an [EditPlan] that
+  /// removes the dead code (and performs appropriate updates within any
+  /// descendant AST nodes that remain).  Otherwise returns `null`.
+  EditPlan _applyConditional(
+      N node, FixAggregator aggregator, AstNode thenNode, AstNode elseNode) {
+    if (conditionValue == null) return null;
+    AstNode nodeToKeep;
+    NullabilityFixDescription descriptionBefore, descriptionAfter;
+    if (conditionValue) {
+      nodeToKeep = thenNode;
+      descriptionBefore = NullabilityFixDescription.discardCondition;
+      if (elseNode == null) {
+        descriptionAfter = descriptionBefore;
+      } else {
+        descriptionAfter = NullabilityFixDescription.discardElse;
+      }
+    } else {
+      nodeToKeep = elseNode;
+      descriptionBefore =
+          descriptionAfter = NullabilityFixDescription.discardThen;
+    }
+    if (nodeToKeep == null ||
+        nodeToKeep is Block && nodeToKeep.statements.isEmpty) {
+      var info =
+          AtomicEditInfo(NullabilityFixDescription.discardIf, conditionReasons);
+      return aggregator.planner.removeNode(node, info: info);
+    }
+    var infoBefore = AtomicEditInfo(descriptionBefore, conditionReasons);
+    var infoAfter = AtomicEditInfo(descriptionAfter, conditionReasons);
+    if (nodeToKeep is Block && nodeToKeep.statements.length == 1) {
+      var singleStatement = (nodeToKeep as Block).statements[0];
+      if (singleStatement is VariableDeclarationStatement) {
+        // It's not safe to eliminate the {} because it increases the scope of
+        // the variable declarations
+      } else {
+        nodeToKeep = singleStatement;
+      }
+    }
+    return aggregator.planner.extract(
+        node, aggregator.planForNode(nodeToKeep) as NodeProducingEditPlan,
+        infoBefore: infoBefore, infoAfter: infoAfter);
+  }
+}
+
+/// Implementation of [NodeChange] specialized for operating on
+/// [ConditionalExpression] nodes.
+class NodeChangeForConditionalExpression
+    extends NodeChangeForExpression<ConditionalExpression>
+    with NodeChangeForConditional {
+  @override
+  EditPlan _apply(ConditionalExpression node, FixAggregator aggregator) {
+    return _applyConditional(
+            node, aggregator, node.thenExpression, node.elseExpression) ??
+        super._apply(node, aggregator);
+  }
+}
+
+/// Implementation of [NodeChange] specialized for operating on
+/// [DefaultFormalParameter] nodes.
+class NodeChangeForDefaultFormalParameter
+    extends NodeChange<DefaultFormalParameter> {
+  /// Indicates whether a `required` keyword should be added to this node.
+  bool addRequiredKeyword = false;
+
+  /// If [addRequiredKeyword] is `true`, the information that should be
+  /// contained in the edit.
+  AtomicEditInfo addRequiredKeywordInfo;
+
+  NodeChangeForDefaultFormalParameter() : super._();
+
+  @override
+  EditPlan _apply(DefaultFormalParameter node, FixAggregator aggregator) {
+    var innerPlan = aggregator.innerPlanForNode(node);
+    if (!addRequiredKeyword) return innerPlan;
+    return aggregator.planner.surround(innerPlan,
+        prefix: [AtomicEdit.insert('required ', info: addRequiredKeywordInfo)]);
+  }
+}
+
+/// Implementation of [NodeChange] specialized for operating on [Expression]
+/// nodes.
+class NodeChangeForExpression<N extends Expression> extends NodeChange<N> {
+  /// Indicates whether the expression should be null checked.
+  bool addNullCheck = false;
+
+  /// If [addNullCheck] is `true`, the information that should be contained in
+  /// the edit that adds the null check.
+  AtomicEditInfo addNullCheckInfo;
+
+  /// Indicates whether the expression should be cast to a different type using
+  /// `as`.
+  String introduceAsType;
+
+  /// If [introduceAsType] is not `null`, the information that should be
+  /// contained in the edit that introduces the cast.
+  AtomicEditInfo introduceAsInfo;
+
+  NodeChangeForExpression() : super._();
+
+  @override
+  EditPlan _apply(N node, FixAggregator aggregator) {
+    var innerPlan = aggregator.innerPlanForNode(node);
+    return _applyExpression(aggregator, innerPlan);
+  }
+
+  /// If the expression needs to be wrapped in another expression (e.g. a null
+  /// check), wraps the given [innerPlan] to produce appropriate result.
+  /// Otherwise returns [innerPlan] unchanged.
+  NodeProducingEditPlan _applyExpression(
+      FixAggregator aggregator, NodeProducingEditPlan innerPlan) {
+    assert((introduceAsType == null) == (introduceAsInfo == null));
+    if (addNullCheck) {
+      assert(introduceAsInfo == null);
+      return aggregator.planner
+          .addUnaryPostfix(innerPlan, TokenType.BANG, info: addNullCheckInfo);
+    } else if (introduceAsInfo != null) {
+      return aggregator.planner
+          .addBinaryPostfix(innerPlan, TokenType.AS, introduceAsType);
+    } else {
+      return innerPlan;
+    }
+  }
+}
+
+/// Implementation of [NodeChange] specialized for operating on [IfElement]
+/// nodes.
+class NodeChangeForIfElement extends NodeChange<IfElement>
+    with NodeChangeForConditional {
+  NodeChangeForIfElement() : super._();
+
+  @override
+  EditPlan _apply(IfElement node, FixAggregator aggregator) {
+    return _applyConditional(
+            node, aggregator, node.thenElement, node.elseElement) ??
+        aggregator.innerPlanForNode(node);
+  }
+}
+
+/// Implementation of [NodeChange] specialized for operating on [IfStatement]
+/// nodes.
+class NodeChangeForIfStatement extends NodeChange<IfStatement>
+    with NodeChangeForConditional {
+  NodeChangeForIfStatement() : super._();
+
+  @override
+  EditPlan _apply(IfStatement node, FixAggregator aggregator) {
+    return _applyConditional(
+            node, aggregator, node.thenStatement, node.elseStatement) ??
+        aggregator.innerPlanForNode(node);
+  }
+}
+
+/// Implementation of [NodeChange] specialized for operating on
+/// [MethodInvocation] nodes.
+class NodeChangeForMethodInvocation
+    extends NodeChangeForExpression<MethodInvocation>
+    with NodeChangeForNullAware {
+  @override
+  NodeProducingEditPlan _apply(
+      MethodInvocation node, FixAggregator aggregator) {
+    var target = node.target;
+    var targetPlan = target == null ? null : aggregator.planForNode(target);
+    var nullAwarePlan = _applyNullAware(node, aggregator);
+    var methodNamePlan = aggregator.planForNode(node.methodName);
+    var typeArguments = node.typeArguments;
+    var typeArgumentsPlan =
+        typeArguments == null ? null : aggregator.planForNode(typeArguments);
+    var argumentListPlan = aggregator.planForNode(node.argumentList);
+    var innerPlans = [
+      if (targetPlan != null) targetPlan,
+      if (nullAwarePlan != null) nullAwarePlan,
+      if (methodNamePlan != null) methodNamePlan,
+      if (typeArgumentsPlan != null) typeArgumentsPlan,
+      if (argumentListPlan != null) argumentListPlan
+    ];
+    return _applyExpression(aggregator,
+        aggregator.planner.passThrough(node, innerPlans: innerPlans));
+  }
+}
+
+/// Common infrastructure used by [NodeChange] objects that operate on AST nodes
+/// with that can be null-aware (method invocations and propety accesses).
+mixin NodeChangeForNullAware<N extends Expression> on NodeChange<N> {
+  /// Indicates whether null-awareness should be removed.
+  bool removeNullAwareness = false;
+
+  /// Returns an [EditPlan] that removes null awareness, if appropriate.
+  /// Otherwise returns `null`.
+  EditPlan _applyNullAware(N node, FixAggregator aggregator) {
+    if (!removeNullAwareness) return null;
+    return aggregator.planner.removeNullAwareness(node,
+        info:
+            AtomicEditInfo(NullabilityFixDescription.removeNullAwareness, []));
+  }
+}
+
+/// Implementation of [NodeChange] specialized for operating on [PropertyAccess]
+/// nodes.
+class NodeChangeForPropertyAccess
+    extends NodeChangeForExpression<PropertyAccess>
+    with NodeChangeForNullAware {
+  @override
+  NodeProducingEditPlan _apply(PropertyAccess node, FixAggregator aggregator) {
+    var targetPlan = aggregator.planForNode(node.target);
+    var nullAwarePlan = _applyNullAware(node, aggregator);
+    var propertyNamePlan = aggregator.planForNode(node.propertyName);
+    var innerPlans = [
+      if (targetPlan != null) targetPlan,
+      if (nullAwarePlan != null) nullAwarePlan,
+      if (propertyNamePlan != null) propertyNamePlan
+    ];
+    return _applyExpression(aggregator,
+        aggregator.planner.passThrough(node, innerPlans: innerPlans));
+  }
+}
+
+/// Implementation of [NodeChange] specialized for operating on [TypeAnnotation]
+/// nodes.
+class NodeChangeForTypeAnnotation extends NodeChange<TypeAnnotation> {
+  /// Indicates whether the type should be made nullable by adding a `?`.
+  bool makeNullable = false;
+
+  /// If [makeNullable] is `true`, the decorated type that results.
+  DecoratedType makeNullableType;
+
+  NodeChangeForTypeAnnotation() : super._();
+
+  @override
+  EditPlan _apply(TypeAnnotation node, FixAggregator aggregator) {
+    var innerPlan = aggregator.innerPlanForNode(node);
+    if (!makeNullable) return innerPlan;
+    return aggregator.planner.makeNullable(innerPlan,
+        info: AtomicEditInfo(
+            NullabilityFixDescription.makeTypeNullable(
+                makeNullableType.type.toString()),
+            [makeNullableType.node]));
+  }
+}
+
+/// Implementation of [NodeChange] specialized for operating on
+/// [VariableDeclarationList] nodes.
+class NodeChangeForVariableDeclarationList
+    extends NodeChange<VariableDeclarationList> {
+  /// If an explicit type should be added to this variable declaration, the type
+  /// that should be added.  Otherwise `null`.
+  DartType addExplicitType;
+
+  NodeChangeForVariableDeclarationList() : super._();
+
+  @override
+  EditPlan _apply(VariableDeclarationList node, FixAggregator aggregator) {
+    List<EditPlan> innerPlans = [];
+    if (addExplicitType != null) {
+      var typeText =
+          (addExplicitType as TypeImpl).toString(withNullability: true);
+      if (node.keyword?.keyword == Keyword.VAR) {
+        innerPlans.add(aggregator.planner
+            .replaceToken(node, node.keyword, [AtomicEdit.insert(typeText)]));
+      } else {
+        innerPlans.add(aggregator.planner.insertText(
+            node,
+            node.variables.first.offset,
+            [AtomicEdit.insert(typeText), AtomicEdit.insert(' ')]));
+      }
+    }
+    innerPlans.addAll(aggregator.innerPlansForNode(node));
+    return aggregator.planner.passThrough(node, innerPlans: innerPlans);
+  }
+}
+
+/// Visitor that creates an appropriate [NodeChange] object for the node being
+/// visited.
+class _NodeChangeVisitor extends GeneralizingAstVisitor<NodeChange<AstNode>> {
+  static final _instance = _NodeChangeVisitor();
+
+  @override
+  NodeChange visitAnnotation(Annotation node) => NodeChangeForAnnotation();
+
+  @override
+  NodeChange visitAsExpression(AsExpression node) =>
+      NodeChangeForAsExpression();
+
+  @override
+  NodeChange visitDefaultFormalParameter(DefaultFormalParameter node) =>
+      NodeChangeForDefaultFormalParameter();
+
+  @override
+  NodeChange visitExpression(Expression node) => NodeChangeForExpression();
+
+  @override
+  NodeChange visitGenericFunctionType(GenericFunctionType node) =>
+      NodeChangeForTypeAnnotation();
+
+  @override
+  NodeChange visitIfElement(IfElement node) => NodeChangeForIfElement();
+
+  @override
+  NodeChange visitIfStatement(IfStatement node) => NodeChangeForIfStatement();
+
+  @override
+  NodeChange visitMethodInvocation(MethodInvocation node) =>
+      NodeChangeForMethodInvocation();
+
+  @override
+  NodeChange visitNode(AstNode node) =>
+      throw StateError('Unexpected node type: ${node.runtimeType}');
+
+  @override
+  NodeChange visitPropertyAccess(PropertyAccess node) =>
+      NodeChangeForPropertyAccess();
+
+  @override
+  NodeChange visitTypeName(TypeName node) => NodeChangeForTypeAnnotation();
+
+  @override
+  NodeChange visitVariableDeclarationList(VariableDeclarationList node) =>
+      NodeChangeForVariableDeclarationList();
+}
diff --git a/pkg/nnbd_migration/lib/src/fix_builder.dart b/pkg/nnbd_migration/lib/src/fix_builder.dart
index eddd920..33e1df8 100644
--- a/pkg/nnbd_migration/lib/src/fix_builder.dart
+++ b/pkg/nnbd_migration/lib/src/fix_builder.dart
@@ -155,20 +155,6 @@
     }
   }
 
-  /// Called whenever an AST node is found that needs to be changed.
-  ///
-  /// The [update] callback is passed whatever change had previously been
-  /// decided upon for this node, or an instance of [NoChange], if the node was
-  /// previously unchanged.
-  void _addChange(AstNode node,
-      NodeChange Function(NodeChange<NodeProducingEditPlan>) update) {
-    // The previous change had better be a NodeChange<NodeProducingEditPlan>
-    // because these are the only kinds of changes that are possible to stack
-    // on top of one another.
-    var previousChange = changes[node] as NodeChange<NodeProducingEditPlan>;
-    changes[node] = update(previousChange ?? const NoChange());
-  }
-
   /// Called whenever an AST node is found that can't be automatically fixed.
   void _addProblem(AstNode node, Problem problem) {
     var newlyAdded = (problems[node] ??= {}).add(problem);
@@ -211,28 +197,25 @@
     }
   }
 
+  /// Returns the [NodeChange] object accumulating changes for the given [node],
+  /// creating it if necessary.
+  NodeChange _getChange(AstNode node) =>
+      changes[node] ??= NodeChange.create(node);
+
   /// Determines whether the given [node], which is a null-aware method
   /// invocation, property access, or index expression, should remain null-aware
   /// after migration.
   bool _shouldStayNullAware(Expression node) {
     Expression target;
-    NodeChange<NodeProducingEditPlan> nodeChangeToUse;
     if (node is PropertyAccess) {
       target = node.target;
-      nodeChangeToUse = const RemoveNullAwarenessFromPropertyAccess();
     } else if (node is MethodInvocation) {
       target = node.target;
-      nodeChangeToUse = const RemoveNullAwarenessFromMethodInvocation();
     } else {
       throw StateError('Unexpected expression type: ${node.runtimeType}');
     }
     if (!_typeSystem.isPotentiallyNullable(target.staticType)) {
-      _addChange(node, (previousChange) {
-        // There should be no previous change because we decide what to do
-        // about `?.` before doing anything else.
-        assert(previousChange is NoChange);
-        return nodeChangeToUse;
-      });
+      (_getChange(node) as NodeChangeForNullAware).removeNullAwareness = true;
       return false;
     }
     return true;
@@ -277,13 +260,9 @@
             return null;
           }
           var conditionValue = conditionalDiscard.keepTrue;
-          _fixBuilder._addChange(node, (previousChange) {
-            // There shouldn't be a previous change for [node] because we
-            // check for dead code before making other modifications.
-            assert(previousChange is NoChange);
-            return EliminateDeadIf(conditionValue,
-                reasons: conditionalDiscard.reasons.toList());
-          });
+          (_fixBuilder._getChange(node) as NodeChangeForConditional)
+            ..conditionValue = conditionValue
+            ..conditionReasons = conditionalDiscard.reasons.toList();
           return conditionValue;
         }
       });
@@ -364,14 +343,21 @@
   DartType modifyExpressionType(Expression node, DartType type) =>
       _wrapExceptions(node, () => type, () {
         if (type.isDynamic) return type;
-        if (!_fixBuilder._typeSystem.isNullable(type)) return type;
         var ancestor = _findNullabilityContextAncestor(node);
-        if (_needsNullCheckDueToStructure(ancestor)) {
-          return _addNullCheck(node, type);
-        }
         var context =
             InferenceContext.getContext(ancestor) ?? DynamicTypeImpl.instance;
-        if (!_fixBuilder._typeSystem.isNullable(context)) {
+        if (!_fixBuilder._typeSystem.isSubtypeOf(type, context)) {
+          // Either a cast or a null check is needed.  We prefer to do a null
+          // check if we can.
+          var nonNullType = _fixBuilder._typeSystem.promoteToNonNull(type);
+          if (_fixBuilder._typeSystem.isSubtypeOf(nonNullType, context)) {
+            return _addNullCheck(node, type);
+          } else {
+            return _addCast(node, context);
+          }
+        }
+        if (!_fixBuilder._typeSystem.isNullable(type)) return type;
+        if (_needsNullCheckDueToStructure(ancestor)) {
           return _addNullCheck(node, type);
         }
         return type;
@@ -384,6 +370,21 @@
     _flowAnalysis = flowAnalysis;
   }
 
+  DartType _addCast(Expression node, DartType contextType) {
+    var checks =
+        _fixBuilder._variables.expressionChecks(_fixBuilder.source, node);
+    var info = checks != null
+        ? AtomicEditInfo(
+            NullabilityFixDescription.checkExpression, checks.edges)
+        : null;
+    (_fixBuilder._getChange(node) as NodeChangeForExpression)
+      ..introduceAsType =
+          (contextType as TypeImpl).toString(withNullability: true)
+      ..introduceAsInfo = info;
+    _flowAnalysis.asExpression_end(node, contextType);
+    return contextType;
+  }
+
   DartType _addNullCheck(Expression node, DartType type) {
     var checks =
         _fixBuilder._variables.expressionChecks(_fixBuilder.source, node);
@@ -391,8 +392,9 @@
         ? AtomicEditInfo(
             NullabilityFixDescription.checkExpression, checks.edges)
         : null;
-    _fixBuilder._addChange(
-        node, (previousChange) => NullCheck(info, previousChange));
+    (_fixBuilder._getChange(node) as NodeChangeForExpression)
+      ..addNullCheck = true
+      ..addNullCheckInfo = info;
     _flowAnalysis.nonNullAssert_end(node);
     return _fixBuilder._typeSystem.promoteToNonNull(type as TypeImpl);
   }
@@ -520,10 +522,42 @@
     if (!_fixBuilder._variables.wasUnnecessaryCast(_fixBuilder.source, node) &&
         BestPracticesVerifier.isUnnecessaryCast(
             node, _fixBuilder._typeSystem)) {
-      _fixBuilder._addChange(
-          node, (previousChange) => RemoveAs(previousChange));
+      (_fixBuilder._getChange(node) as NodeChangeForAsExpression).removeAs =
+          true;
     }
   }
+
+  @override
+  void visitVariableDeclarationList(VariableDeclarationList node) {
+    if (node.type == null) {
+      // TODO(paulberry): for fields, handle inference via override as well.
+      List<DartType> neededTypes = [];
+      List<DartType> inferredTypes = [];
+      bool explicitTypeNeeded = false;
+      for (var variableDeclaration in node.variables) {
+        var neededType = _fixBuilder
+            ._computeMigratedType(variableDeclaration.declaredElement);
+        neededTypes.add(neededType);
+        var inferredType = variableDeclaration.initializer?.staticType ??
+            _fixBuilder.typeProvider.dynamicType;
+        inferredTypes.add(inferredType);
+        if (neededType != inferredType) {
+          explicitTypeNeeded = true;
+        }
+      }
+      if (explicitTypeNeeded) {
+        var firstNeededType = neededTypes[0];
+        if (neededTypes.any((t) => t != firstNeededType)) {
+          throw UnimplementedError(
+              'Different explicit types needed in multi-variable declaration');
+        } else {
+          (_fixBuilder._getChange(node) as NodeChangeForVariableDeclarationList)
+              .addExplicitType = firstNeededType;
+        }
+      }
+    }
+    super.visitVariableDeclarationList(node);
+  }
 }
 
 /// Visitor that computes additional migrations on behalf of [FixBuilder] that
@@ -564,8 +598,9 @@
     var decoratedType = _fixBuilder._variables
         .decoratedTypeAnnotation(_fixBuilder.source, node);
     if (decoratedType.node.isNullable) {
-      _fixBuilder._addChange(node,
-          (previousChange) => MakeNullable(decoratedType, previousChange));
+      (_fixBuilder._getChange(node) as NodeChangeForTypeAnnotation)
+        ..makeNullable = true
+        ..makeNullableType = decoratedType;
     }
     (node as GenericFunctionTypeImpl).type =
         decoratedType.toFinalType(_fixBuilder.typeProvider);
@@ -578,8 +613,9 @@
         .decoratedTypeAnnotation(_fixBuilder.source, node);
     var type = decoratedType.type;
     if (!type.isDynamic && !type.isVoid && decoratedType.node.isNullable) {
-      _fixBuilder._addChange(node,
-          (previousChange) => MakeNullable(decoratedType, previousChange));
+      (_fixBuilder._getChange(node) as NodeChangeForTypeAnnotation)
+        ..makeNullable = true
+        ..makeNullableType = decoratedType;
     }
     node.type = decoratedType.toFinalType(_fixBuilder.typeProvider);
     super.visitTypeName(node);
@@ -601,15 +637,15 @@
       if (annotation.elementAnnotation.isRequired) {
         // TODO(paulberry): what if `@required` isn't the first annotation?
         // Will we produce something that isn't grammatical?
-        _fixBuilder._addChange(
-            annotation,
-            (previousChange) =>
-                RequiredAnnotationToRequiredKeyword(info, previousChange));
+        (_fixBuilder._getChange(annotation) as NodeChangeForAnnotation)
+          ..changeToRequiredKeyword = true
+          ..changeToRequiredKeywordInfo = info;
         return;
       }
     }
     // Otherwise create a new `required` keyword.
-    _fixBuilder._addChange(parameter,
-        (previousChange) => AddRequiredKeyword(info, previousChange));
+    (_fixBuilder._getChange(parameter) as NodeChangeForDefaultFormalParameter)
+      ..addRequiredKeyword = true
+      ..addRequiredKeywordInfo = info;
   }
 }
diff --git a/pkg/nnbd_migration/lib/src/node_builder.dart b/pkg/nnbd_migration/lib/src/node_builder.dart
index 3a23ae3..6aee695 100644
--- a/pkg/nnbd_migration/lib/src/node_builder.dart
+++ b/pkg/nnbd_migration/lib/src/node_builder.dart
@@ -74,7 +74,8 @@
       // If there is no `on Type` part of the catch clause, the type is dynamic.
       if (exceptionType == null) {
         exceptionType = DecoratedType.forImplicitType(
-            _typeProvider, _typeProvider.dynamicType, _graph);
+            _typeProvider, _typeProvider.dynamicType, _graph,
+            offset: node.offset);
         instrumentation?.implicitType(
             source, node.exceptionParameter, exceptionType);
       }
@@ -83,8 +84,9 @@
     }
     if (node.stackTraceParameter != null) {
       // The type of stack traces is always StackTrace (non-nullable).
-      var nullabilityNode = NullabilityNode.forInferredType();
-      _graph.makeNonNullable(nullabilityNode,
+      var nullabilityNode = NullabilityNode.forInferredType(
+          offset: node.stackTraceParameter.offset);
+      _graph.makeNonNullableUnion(nullabilityNode,
           StackTraceTypeOrigin(source, node.stackTraceParameter));
       var stackTraceType =
           DecoratedType(_typeProvider.stackTraceType, nullabilityNode);
@@ -139,7 +141,7 @@
           _createDecoratedTypeForClass(classElement, node);
       var functionType = DecoratedType.forImplicitFunction(
           _typeProvider, constructorElement.type, _graph.never, _graph,
-          returnType: decoratedReturnType);
+          returnType: decoratedReturnType, offset: node.offset);
       _variables.recordDecoratedElementType(constructorElement, functionType);
     }
     return null;
@@ -173,7 +175,8 @@
     if (node.identifier != null) {
       if (type == null) {
         type = DecoratedType.forImplicitType(
-            _typeProvider, node.declaredElement.type, _graph);
+            _typeProvider, node.declaredElement.type, _graph,
+            offset: node.offset);
         instrumentation?.implicitType(source, node, type);
       }
       _variables.recordDecoratedElementType(
@@ -210,8 +213,8 @@
 
     makeNonNullNode([AstNode forNode]) {
       forNode ??= node;
-      final graphNode = NullabilityNode.forInferredType();
-      _graph.makeNonNullable(graphNode, EnumValueOrigin(source, forNode));
+      final graphNode = NullabilityNode.forInferredType(offset: forNode.offset);
+      _graph.makeNonNullableUnion(graphNode, EnumValueOrigin(source, forNode));
       return graphNode;
     }
 
@@ -291,7 +294,8 @@
     } else {
       // Inferred return type.
       decoratedReturnType = DecoratedType.forImplicitType(
-          _typeProvider, functionType.returnType, _graph);
+          _typeProvider, functionType.returnType, _graph,
+          offset: node.offset);
       instrumentation?.implicitReturnType(source, node, decoratedReturnType);
     }
     var previousPositionalParameters = _positionalParameters;
@@ -397,8 +401,9 @@
       if (node is TypeName) {
         if (node.typeArguments == null) {
           typeArguments = type.typeArguments
-              .map((t) =>
-                  DecoratedType.forImplicitType(_typeProvider, t, _graph))
+              .map((t) => DecoratedType.forImplicitType(
+                  _typeProvider, t, _graph,
+                  offset: node.offset))
               .toList();
           instrumentation?.implicitTypeArguments(source, node, typeArguments);
         } else {
@@ -413,7 +418,8 @@
       var returnType = node.returnType;
       if (returnType == null) {
         decoratedReturnType = DecoratedType.forImplicitType(
-            _typeProvider, DynamicTypeImpl.instance, _graph);
+            _typeProvider, DynamicTypeImpl.instance, _graph,
+            offset: node.offset);
         instrumentation?.implicitReturnType(source, node, decoratedReturnType);
       } else {
         decoratedReturnType = returnType.accept(this);
@@ -454,7 +460,8 @@
       // synthesize new nodes for it).  These nodes will be unioned with the
       // typedef nodes by the edge builder.
       decoratedType = DecoratedType.forImplicitFunction(
-          _typeProvider, type, nullabilityNode, _graph);
+          _typeProvider, type, nullabilityNode, _graph,
+          offset: node.offset);
     } else {
       decoratedType = DecoratedType(type, nullabilityNode,
           typeArguments: typeArguments,
@@ -472,7 +479,7 @@
     var commentToken = node.endToken.next.precedingComments;
     switch (_classifyComment(commentToken)) {
       case _NullabilityComment.bang:
-        _graph.makeNonNullable(
+        _graph.makeNonNullableUnion(
             decoratedType.node, NullabilityCommentOrigin(source, node));
         break;
       case _NullabilityComment.question:
@@ -499,7 +506,8 @@
     if (bound != null) {
       decoratedBound = bound.accept(this);
     } else {
-      var nullabilityNode = NullabilityNode.forInferredType();
+      var nullabilityNode =
+          NullabilityNode.forInferredType(offset: node.offset);
       decoratedBound = DecoratedType(_typeProvider.objectType, nullabilityNode);
       _graph.connect(_graph.always, nullabilityNode,
           AlwaysNullableTypeOrigin.forElement(element));
@@ -519,7 +527,8 @@
       var declaredElement = variable.declaredElement;
       if (type == null) {
         type = DecoratedType.forImplicitType(
-            _typeProvider, declaredElement.type, _graph);
+            _typeProvider, declaredElement.type, _graph,
+            offset: variable.offset);
         instrumentation?.implicitType(source, node, type);
       }
       _variables.recordDecoratedElementType(declaredElement, type);
@@ -578,7 +587,8 @@
     } else {
       // Inferred return type.
       decoratedReturnType = DecoratedType.forImplicitType(
-          _typeProvider, functionType.returnType, _graph);
+          _typeProvider, functionType.returnType, _graph,
+          offset: node.offset);
       instrumentation?.implicitReturnType(source, node, decoratedReturnType);
     }
     var previousPositionalParameters = _positionalParameters;
@@ -621,14 +631,16 @@
         decoratedType = type.accept(this);
       } else {
         decoratedType = DecoratedType.forImplicitType(
-            _typeProvider, declaredElement.type, _graph);
+            _typeProvider, declaredElement.type, _graph,
+            offset: node.offset);
         instrumentation?.implicitType(source, node, decoratedType);
       }
     } else {
       DecoratedType decoratedReturnType;
       if (type == null) {
         decoratedReturnType = DecoratedType.forImplicitType(
-            _typeProvider, DynamicTypeImpl.instance, _graph);
+            _typeProvider, DynamicTypeImpl.instance, _graph,
+            offset: node.offset);
         instrumentation?.implicitReturnType(source, node, decoratedReturnType);
       } else {
         decoratedReturnType = type.accept(this);
@@ -687,8 +699,9 @@
     for (var supertype in supertypes) {
       DecoratedType decoratedSupertype;
       if (supertype == null) {
-        var nullabilityNode = NullabilityNode.forInferredType();
-        _graph.makeNonNullable(
+        var nullabilityNode =
+            NullabilityNode.forInferredType(offset: astNode.offset);
+        _graph.makeNonNullableUnion(
             nullabilityNode, NonNullableObjectSuperclass(source, astNode));
         decoratedSupertype =
             DecoratedType(_typeProvider.objectType, nullabilityNode);
diff --git a/pkg/nnbd_migration/lib/src/nullability_node.dart b/pkg/nnbd_migration/lib/src/nullability_node.dart
index 1acb613..ad77386 100644
--- a/pkg/nnbd_migration/lib/src/nullability_node.dart
+++ b/pkg/nnbd_migration/lib/src/nullability_node.dart
@@ -29,8 +29,15 @@
   @override
   Iterable<NullabilityNode> get guards => upstreamNodes.skip(1);
 
+  /// Indicates whether it's possible for migration to cope with this edge being
+  /// unsatisfied by inserting a null check.  Graph propagation favors
+  /// satisfying uncheckable edges over satisfying hard edges.
+  bool get isCheckable =>
+      _kind == _NullabilityEdgeKind.soft || _kind == _NullabilityEdgeKind.hard;
+
   @override
-  bool get isHard => _kind != _NullabilityEdgeKind.soft;
+  bool get isHard =>
+      _kind == _NullabilityEdgeKind.hard || _kind == _NullabilityEdgeKind.union;
 
   @override
   bool get isSatisfied {
@@ -52,8 +59,7 @@
   @override
   bool get isUpstreamTriggered {
     if (!isHard) return false;
-    if (destinationNode._state != NullabilityState.nonNullable) return false;
-    return true;
+    return destinationNode.nonNullIntent.isPresent;
   }
 
   @override
@@ -65,6 +71,9 @@
     switch (_kind) {
       case _NullabilityEdgeKind.soft:
         break;
+      case _NullabilityEdgeKind.uncheckable:
+        edgeDecorations.add('uncheckable');
+        break;
       case _NullabilityEdgeKind.hard:
         edgeDecorations.add('hard');
         break;
@@ -92,10 +101,6 @@
 
   final NullabilityMigrationInstrumentation /*?*/ instrumentation;
 
-  /// Set containing all [NullabilityNode]s that have been passed as the
-  /// `upstreamNode` argument to [connect].
-  final _allUpstreamNodes = Set<NullabilityNode>.identity();
-
   /// Returns a [NullabilityNode] that is a priori nullable.
   ///
   /// Propagation of nullability always proceeds downstream starting at this
@@ -114,45 +119,28 @@
   /// A set containing all of the nodes in the graph.
   final Set<NullabilityNode> nodes = {};
 
-  /// After execution of [_propagateAlways], a list of all nodes reachable from
-  /// [always] via zero or more edges of kind [_NullabilityEdgeKind.union].
-  final List<NullabilityNode> _unionedWithAlways = [];
-
-  /// During any given stage of nullability propagation, a list of all the edges
-  /// that need to be examined before the stage is complete.
-  final List<NullabilityEdge> _pendingEdges = [];
-
-  /// During and after nullability propagation, a list of all edges that
-  /// couldn't be satisfied.
-  final List<NullabilityEdge> _unsatisfiedEdges = [];
-
-  /// During and after nullability propagation, a list of all substitution nodes
-  /// that couldn't be satisfied.
-  final List<NullabilityNodeForSubstitution> _unsatisfiedSubstitutions = [];
-
-  /// During execution of [_propagateDownstream], a list of all the substitution
-  /// nodes that have not yet been resolved.
-  List<NullabilityNodeForSubstitution> _pendingSubstitutions = [];
-
   NullabilityGraph({this.instrumentation});
 
-  /// After calling [propagate], this getter may be queried to access the set of
-  /// edges that could not be satisfied.
-  Iterable<NullabilityEdge> get unsatisfiedEdges => _unsatisfiedEdges;
-
-  /// After calling [propagate], this getter may be queried to access the set of
-  /// substitution nodes that could not be satisfied.
-  Iterable<NullabilityNodeForSubstitution> get unsatisfiedSubstitutions =>
-      _unsatisfiedSubstitutions;
-
   /// Records that [sourceNode] is immediately upstream from [destinationNode].
   ///
   /// Returns the edge created by the connection.
   NullabilityEdge connect(NullabilityNode sourceNode,
       NullabilityNode destinationNode, EdgeOrigin origin,
-      {bool hard: false, List<NullabilityNode> guards: const []}) {
+      {bool hard: false,
+      bool checkable = true,
+      List<NullabilityNode> guards: const []}) {
+    // Hard nodes are always considered checkable, since the only time they
+    // arise is from an explicit use of an expression in a context that requires
+    // non-nullability (and hence, a null check could be added in that
+    // location).  Verify that the flags passed in by the caller are consistent
+    // with this.
+    assert(checkable || !hard);
     var upstreamNodes = [sourceNode]..addAll(guards);
-    var kind = hard ? _NullabilityEdgeKind.hard : _NullabilityEdgeKind.soft;
+    var kind = hard
+        ? _NullabilityEdgeKind.hard
+        : checkable
+            ? _NullabilityEdgeKind.soft
+            : _NullabilityEdgeKind.uncheckable;
     return _connect(upstreamNodes, destinationNode, kind, origin);
   }
 
@@ -168,6 +156,12 @@
     return connect(node, never, origin, hard: hard, guards: guards);
   }
 
+  /// Creates union edges that will guarantee that the given [node] is
+  /// non-nullable.
+  void makeNonNullableUnion(NullabilityNode node, EdgeOrigin origin) {
+    union(node, never, origin);
+  }
+
   /// Creates a graph edge that will try to force the given [node] to be
   /// nullable.
   void makeNullable(NullabilityNode node, EdgeOrigin origin,
@@ -189,12 +183,11 @@
 
   /// Determines the nullability of each node in the graph by propagating
   /// nullability information from one node to another.
-  void propagate() {
+  PropagationResult propagate() {
     if (_debugBeforePropagation) _debugDump();
-    _propagateAlways();
-    _propagateUpstream();
-    _propagateDownstream();
+    var propagationState = _PropagationState(always, never).result;
     if (_debugAfterPropagation) _debugDump();
+    return propagationState;
   }
 
   /// Records that nodes [x] and [y] should have exactly the same nullability.
@@ -215,7 +208,6 @@
     for (var node in nodes) {
       node.resetState();
     }
-    _unionedWithAlways.clear();
     //
     // Reset the state of the listener.
     //
@@ -243,7 +235,6 @@
   }
 
   void _connectDownstream(NullabilityNode upstreamNode, NullabilityEdge edge) {
-    _allUpstreamNodes.add(upstreamNode);
     upstreamNode._downstreamEdges.add(edge);
     if (upstreamNode is _NullabilityNodeCompound) {
       for (var component in upstreamNode._components) {
@@ -253,189 +244,68 @@
   }
 
   void _debugDump() {
-    for (var upstreamNode in _allUpstreamNodes) {
-      var edges = upstreamNode._downstreamEdges;
-      var destinations =
-          edges.where((edge) => edge.sourceNode == upstreamNode).map((edge) {
-        var suffixes = <Object>[];
+    Set<NullabilityNode> visitedNodes = {};
+    Map<NullabilityNode, String> shortNames = {};
+    int counter = 0;
+    String nameNode(NullabilityNode node) {
+      if (node.isImmutable) {
+        var name = 'n${counter++}';
+        print('  $name [label="$node" shape=none]');
+        return name;
+      }
+      var name = shortNames[node];
+      if (name == null) {
+        shortNames[node] = name = 'n${counter++}';
+        String styleSuffix = node.isNullable ? ' style=filled' : '';
+        String intentSuffix =
+            node.nonNullIntent.isPresent ? ', non-null intent' : '';
+        String label = '$node (${node._nullability}$intentSuffix)';
+        print('  $name [label="$label"$styleSuffix]');
+        if (node is _NullabilityNodeCompound) {
+          for (var component in node._components) {
+            print('  ${nameNode(component)} -> $name [style=dashed]');
+          }
+        }
+      }
+      return name;
+    }
+
+    void visitNode(NullabilityNode node) {
+      if (!visitedNodes.add(node)) return;
+      for (var edge in node._upstreamEdges) {
+        String suffix;
         if (edge.isUnion) {
-          suffixes.add('union');
+          suffix = ' [label="union"]';
         } else if (edge.isHard) {
-          suffixes.add('hard');
+          suffix = ' [label="hard"]';
+        } else if (edge.isCheckable) {
+          suffix = '';
+        } else {
+          suffix = ' [label="uncheckable"]';
         }
-        suffixes.addAll(edge.guards);
-        var suffix = suffixes.isNotEmpty ? ' (${suffixes.join(', ')})' : '';
-        return '${edge.destinationNode}$suffix';
-      });
-      var state = upstreamNode._state;
-      print('$upstreamNode ($state) -> ${destinations.join(', ')}');
-    }
-  }
-
-  /// Propagates nullability downstream along union edges from "always".
-  void _propagateAlways() {
-    _unionedWithAlways.add(always);
-    _pendingEdges.addAll(always._downstreamEdges);
-    while (_pendingEdges.isNotEmpty) {
-      var edge = _pendingEdges.removeLast();
-      if (!edge.isUnion) continue;
-      // Union edges always have exactly one upstream node, so we don't need to
-      // check whether all upstream nodes are nullable.
-      assert(edge.upstreamNodes.length == 1);
-      var node = edge.destinationNode;
-      if (node is NullabilityNodeMutable && !node.isNullable) {
-        _unionedWithAlways.add(node);
-        _setState(_PropagationStep(
-            node, NullabilityState.ordinaryNullable, StateChangeReason.union,
-            edge: edge));
-        // Was not previously nullable, so we need to propagate.
-        _pendingEdges.addAll(node._downstreamEdges);
-      }
-    }
-  }
-
-  /// Propagates nullability downstream.
-  void _propagateDownstream() {
-    assert(_pendingEdges.isEmpty);
-    for (var node in _unionedWithAlways) {
-      _pendingEdges.addAll(node._downstreamEdges);
-    }
-    while (true) {
-      while (_pendingEdges.isNotEmpty) {
-        var edge = _pendingEdges.removeLast();
-        if (!edge.isTriggered) continue;
-        var node = edge.destinationNode;
-        if (node._state == NullabilityState.nonNullable) {
-          // The node has already been marked as non-nullable, so the edge can't
-          // be satisfied.
-          _unsatisfiedEdges.add(edge);
-          continue;
-        }
-        if (node is NullabilityNodeMutable && !node.isNullable) {
-          _setNullable(_PropagationStep(node, NullabilityState.ordinaryNullable,
-              StateChangeReason.downstream,
-              edge: edge));
-        }
-      }
-      if (_pendingSubstitutions.isEmpty) break;
-      var oldPendingSubstitutions = _pendingSubstitutions;
-      _pendingSubstitutions = [];
-      for (var node in oldPendingSubstitutions) {
-        _resolvePendingSubstitution(node);
-      }
-    }
-  }
-
-  /// Propagates non-null intent upstream along unconditional control flow
-  /// lines.
-  void _propagateUpstream() {
-    assert(_pendingEdges.isEmpty);
-    _pendingEdges.addAll(never._upstreamEdges);
-    while (_pendingEdges.isNotEmpty) {
-      var edge = _pendingEdges.removeLast();
-      // We only propagate for nodes that are "upstream triggered".  At this
-      // point of propagation, a node is upstream triggered if it is hard.
-      assert(edge.isUpstreamTriggered == edge.isHard);
-      if (!edge.isHard) continue;
-      var node = edge.sourceNode;
-      if (node is NullabilityNodeMutable &&
-          node._state == NullabilityState.undetermined) {
-        _setState(_PropagationStep(
-            node, NullabilityState.nonNullable, StateChangeReason.upstream,
-            edge: edge));
-        // Was not previously in the set of non-null intent nodes, so we need to
-        // propagate.
-        _pendingEdges.addAll(node._upstreamEdges);
-      }
-    }
-  }
-
-  void _resolvePendingSubstitution(
-      NullabilityNodeForSubstitution substitutionNode) {
-    assert(substitutionNode._state.isNullable);
-    // If both nodes pointed to by the substitution node are in the non-nullable
-    // state, then no resolution is needed; the substitution node can’t be
-    // satisfied.
-    if (substitutionNode.innerNode._state == NullabilityState.nonNullable &&
-        substitutionNode.outerNode._state == NullabilityState.nonNullable) {
-      _unsatisfiedSubstitutions.add(substitutionNode);
-      return;
-    }
-
-    // Otherwise, if the outer node is in a nullable state, then no resolution
-    // is needed because the substitution node is already satisfied.
-    if (substitutionNode.outerNode.isNullable) {
-      return;
-    }
-
-    // Otherwise, if the inner node is in the non-nullable state, then we set
-    // the outer node to the ordinary nullable state.
-    if (substitutionNode.innerNode._state == NullabilityState.nonNullable) {
-      _setNullable(_PropagationStep(
-          substitutionNode.outerNode as NullabilityNodeMutable,
-          NullabilityState.ordinaryNullable,
-          StateChangeReason.substituteOuter,
-          substitutionNode: substitutionNode));
-      return;
-    }
-
-    // Otherwise, we set the inner node to the exact nullable state, and we
-    // propagate this state upstream as far as possible using the following
-    // rule: if there is an edge A → B, where A is in the undetermined or
-    // ordinary nullable state, and B is in the exact nullable state, then A’s
-    // state is changed to exact nullable.
-    var pendingEdges = <NullabilityEdge>[];
-    var node = substitutionNode.innerNode;
-    if (node is NullabilityNodeMutable) {
-      var oldState = _setNullable(_PropagationStep(node,
-          NullabilityState.exactNullable, StateChangeReason.substituteInner,
-          substitutionNode: substitutionNode));
-      if (oldState != NullabilityState.exactNullable) {
-        // Was not previously in the "exact nullable" state.  Need to
-        // propagate.
-        for (var edge in node._upstreamEdges) {
-          pendingEdges.add(edge);
-        }
-
-        // TODO(mfairhurst): should this propagate back up outerContainerNodes?
-      }
-    }
-    while (pendingEdges.isNotEmpty) {
-      var edge = pendingEdges.removeLast();
-      var node = edge.sourceNode;
-      if (node is NullabilityNodeMutable) {
-        var oldState = _setNullable(_PropagationStep(node,
-            NullabilityState.exactNullable, StateChangeReason.exactUpstream,
-            edge: edge));
-        if (oldState != NullabilityState.exactNullable) {
-          // Was not previously in the "exact nullable" state.  Need to
-          // propagate.
-          for (var edge in node._upstreamEdges) {
-            pendingEdges.add(edge);
+        var upstreamNodes = edge.upstreamNodes;
+        if (upstreamNodes.length == 1) {
+          print(
+              '  ${nameNode(upstreamNodes.single)} -> ${nameNode(node)}$suffix');
+        } else {
+          var tmpName = 'n${counter++}';
+          print('  $tmpName [label=""]');
+          print('  $tmpName -> ${nameNode(node)}$suffix}');
+          for (var upstreamNode in upstreamNodes) {
+            print('  ${nameNode(upstreamNode)} -> $tmpName');
           }
         }
       }
     }
-  }
 
-  NullabilityState _setNullable(_PropagationStep propagationStep) {
-    var node = propagationStep.node;
-    assert(propagationStep.newState.isNullable);
-    var oldState = node._state;
-    _setState(propagationStep);
-    if (!oldState.isNullable) {
-      // Was not previously nullable, so we need to propagate.
-      _pendingEdges.addAll(node._downstreamEdges);
-      if (node is NullabilityNodeForSubstitution) {
-        _pendingSubstitutions.add(node);
-      }
+    print('digraph G {');
+    print('  rankdir="LR"');
+    visitNode(always);
+    visitNode(never);
+    for (var node in nodes) {
+      visitNode(node);
     }
-    return oldState;
-  }
-
-  void _setState(_PropagationStep propagationStep) {
-    propagationStep.node._state = propagationStep.newState;
-    instrumentation?.propagationStep(propagationStep);
+    print('}');
   }
 }
 
@@ -520,8 +390,8 @@
 
   /// Creates a [NullabilityNode] representing the nullability of a variable
   /// whose type is determined by type inference.
-  factory NullabilityNode.forInferredType() =>
-      _NullabilityNodeSimple('inferred');
+  factory NullabilityNode.forInferredType({int offset}) =>
+      _NullabilityNodeSimple('inferred${offset == null ? '' : '($offset)'}');
 
   /// Creates a [NullabilityNode] representing the nullability of an
   /// expression which is nullable iff either [a] or [b] is nullable.
@@ -569,12 +439,16 @@
   /// nullability migration needs to decide whether it is optional or required.
   bool get isPossiblyOptional => _isPossiblyOptional;
 
+  /// After nullability propagation, this getter can be used to query the node's
+  /// non-null intent state.
+  NonNullIntent get nonNullIntent;
+
   @override
   Iterable<EdgeInfo> get upstreamEdges => _upstreamEdges;
 
   String get _debugPrefix;
 
-  NullabilityState get _state;
+  Nullability get _nullability;
 
   /// Records the fact that an invocation was made to a function with named
   /// parameters, and the named parameter associated with this node was not
@@ -678,33 +552,57 @@
 /// Nearly all nullability nodes derive from this class; the only exceptions are
 /// the fixed nodes "always "never".
 abstract class NullabilityNodeMutable extends NullabilityNode {
-  NullabilityState _state;
+  Nullability _nullability;
+
+  NonNullIntent _nonNullIntent;
 
   NullabilityNodeMutable._(
-      {NullabilityState initialState: NullabilityState.undetermined})
-      : _state = initialState,
+      {Nullability initialNullability = Nullability.nonNullable})
+      : _nullability = initialNullability,
+        _nonNullIntent = NonNullIntent.none,
         super._();
 
   @override
-  bool get isExactNullable => _state == NullabilityState.exactNullable;
+  bool get isExactNullable => _nullability.isExactNullable;
 
   @override
   bool get isImmutable => false;
 
   @override
-  bool get isNullable => _state.isNullable;
+  bool get isNullable => _nullability.isNullable;
+
+  @override
+  NonNullIntent get nonNullIntent => _nonNullIntent;
 
   @override
   void resetState() {
-    _state = NullabilityState.undetermined;
+    _nullability = Nullability.nonNullable;
+    _nonNullIntent = NonNullIntent.none;
   }
 }
 
+/// Information produced by [NullabilityGraph.propagate] about the results of
+/// graph propagation.
+class PropagationResult {
+  /// A list of all edges that couldn't be satisfied.
+  final List<NullabilityEdge> unsatisfiedEdges = [];
+
+  /// A list of all substitution nodes that couldn't be satisfied.
+  final List<NullabilityNodeForSubstitution> unsatisfiedSubstitutions = [];
+
+  PropagationResult._();
+}
+
 /// Kinds of nullability edges
 enum _NullabilityEdgeKind {
-  /// Soft edge.  Propagates nullability downstream only.
+  /// Soft edge.  Propagates nullability downstream only.  May be overridden by
+  /// suggestions that the user intends non-nullability.
   soft,
 
+  /// Uncheckable edge.  Propagates nullability downstream only.  May not be
+  /// overridden by suggestions that the user intends non-nullability.
+  uncheckable,
+
   /// Hard edge.  Propagates nullability downstream and non-nullability
   /// upstream.
   hard,
@@ -749,9 +647,12 @@
   bool get isImmutable => true;
 
   @override
-  NullabilityState get _state => isNullable
-      ? NullabilityState.ordinaryNullable
-      : NullabilityState.nonNullable;
+  NonNullIntent get nonNullIntent =>
+      isNullable ? NonNullIntent.none : NonNullIntent.direct;
+
+  @override
+  Nullability get _nullability =>
+      isNullable ? Nullability.ordinaryNullable : Nullability.nonNullable;
 
   @override
   void resetState() {
@@ -763,26 +664,175 @@
   @override
   final String _debugPrefix;
 
-  _NullabilityNodeSimple(this._debugPrefix)
-      : super._(initialState: NullabilityState.undetermined);
+  _NullabilityNodeSimple(this._debugPrefix) : super._();
 }
 
-class _PropagationStep implements PropagationInfo {
-  @override
-  final NullabilityNodeMutable node;
+/// Workspace for performing graph propagation.
+///
+/// Graph propagation is performed immediately upon construction, so as soon as
+/// the caller has constructed this object, the graph has been propagated and
+/// the results of propagation can be retrieved from [result].
+class _PropagationState {
+  /// The result of propagation, for sharing with the client.
+  final PropagationResult result = PropagationResult._();
 
-  @override
-  final NullabilityState newState;
+  /// The graph's one and only "always" node.
+  final NullabilityNode _always;
 
-  @override
-  final StateChangeReason reason;
+  /// The graph's one and only "never" node.
+  final NullabilityNode _never;
 
-  @override
-  final NullabilityEdge edge;
+  /// During any given stage of nullability propagation, a list of all the edges
+  /// that need to be examined before the stage is complete.
+  final List<NullabilityEdge> _pendingEdges = [];
 
-  @override
-  final NullabilityNodeForSubstitution substitutionNode;
+  /// During execution of [_propagateDownstream], a list of all the substitution
+  /// nodes that have not yet been resolved.
+  List<NullabilityNodeForSubstitution> _pendingSubstitutions = [];
 
-  _PropagationStep(this.node, this.newState, this.reason,
-      {this.edge, this.substitutionNode});
+  _PropagationState(this._always, this._never) {
+    _propagateUpstream();
+    _propagateDownstream();
+  }
+
+  /// Propagates nullability downstream.
+  void _propagateDownstream() {
+    assert(_pendingEdges.isEmpty);
+    _pendingEdges.addAll(_always._downstreamEdges);
+    while (true) {
+      while (_pendingEdges.isNotEmpty) {
+        var edge = _pendingEdges.removeLast();
+        if (!edge.isTriggered) continue;
+        var node = edge.destinationNode;
+        var nonNullIntent = node.nonNullIntent;
+        if (nonNullIntent.isPresent) {
+          if (edge.isCheckable) {
+            // The node has already been marked as having non-null intent, and
+            // the edge can be addressed by adding a null check, so we prefer to
+            // leave the edge unsatisfied and let the null check happen.
+            result.unsatisfiedEdges.add(edge);
+            continue;
+          }
+          if (nonNullIntent.isDirect) {
+            // The node has direct non-null intent so we aren't in a position to
+            // mark it as nullable.
+            result.unsatisfiedEdges.add(edge);
+            continue;
+          }
+        }
+        if (node is NullabilityNodeMutable && !node.isNullable) {
+          _setNullable(node, Nullability.ordinaryNullable);
+        }
+      }
+      if (_pendingSubstitutions.isEmpty) break;
+      var oldPendingSubstitutions = _pendingSubstitutions;
+      _pendingSubstitutions = [];
+      for (var node in oldPendingSubstitutions) {
+        _resolvePendingSubstitution(node);
+      }
+    }
+  }
+
+  /// Propagates non-null intent upstream along unconditional control flow
+  /// lines.
+  void _propagateUpstream() {
+    assert(_pendingEdges.isEmpty);
+    _pendingEdges.addAll(_never._upstreamEdges);
+    while (_pendingEdges.isNotEmpty) {
+      var edge = _pendingEdges.removeLast();
+      // We only propagate for nodes that are "upstream triggered".  At this
+      // point of propagation, a node is upstream triggered if it is hard.
+      assert(edge.isUpstreamTriggered == edge.isHard);
+      if (!edge.isHard) continue;
+      var node = edge.sourceNode;
+      if (node is NullabilityNodeMutable) {
+        var oldNonNullIntent = node._nonNullIntent;
+        if (edge.isUnion && edge.destinationNode == _never) {
+          // If a node is unioned with "never" then it's considered to have
+          // direct non-null intent.
+          node._nonNullIntent = NonNullIntent.direct;
+        } else {
+          node._nonNullIntent = oldNonNullIntent.addIndirect();
+        }
+        if (!oldNonNullIntent.isPresent) {
+          // We did not previously have non-null intent, so we need to
+          // propagate.
+          _pendingEdges.addAll(node._upstreamEdges);
+        }
+      }
+    }
+  }
+
+  void _resolvePendingSubstitution(
+      NullabilityNodeForSubstitution substitutionNode) {
+    assert(substitutionNode._nullability.isNullable);
+    // If both nodes pointed to by the substitution node have non-null intent,
+    // then no resolution is needed; the substitution node can’t be satisfied.
+    if (substitutionNode.innerNode.nonNullIntent.isPresent &&
+        substitutionNode.outerNode.nonNullIntent.isPresent) {
+      result.unsatisfiedSubstitutions.add(substitutionNode);
+      return;
+    }
+
+    // Otherwise, if the outer node is in a nullable state, then no resolution
+    // is needed because the substitution node is already satisfied.
+    if (substitutionNode.outerNode.isNullable) {
+      return;
+    }
+
+    // Otherwise, if the inner node has non-null intent, then we set the outer
+    // node to the ordinary nullable state.
+    if (substitutionNode.innerNode.nonNullIntent.isPresent) {
+      _setNullable(substitutionNode.outerNode as NullabilityNodeMutable,
+          Nullability.ordinaryNullable);
+      return;
+    }
+
+    // Otherwise, we set the inner node to the exact nullable state, and we
+    // propagate this state upstream as far as possible using the following
+    // rule: if there is an edge A → B, where A is in the undetermined or
+    // ordinary nullable state, and B is in the exact nullable state, then A’s
+    // state is changed to exact nullable.
+    var pendingEdges = <NullabilityEdge>[];
+    var node = substitutionNode.innerNode;
+    if (node is NullabilityNodeMutable) {
+      var oldNullability = _setNullable(node, Nullability.exactNullable);
+      if (!oldNullability.isExactNullable) {
+        // Was not previously in the "exact nullable" state.  Need to
+        // propagate.
+        for (var edge in node._upstreamEdges) {
+          pendingEdges.add(edge);
+        }
+
+        // TODO(mfairhurst): should this propagate back up outerContainerNodes?
+      }
+    }
+    while (pendingEdges.isNotEmpty) {
+      var edge = pendingEdges.removeLast();
+      var node = edge.sourceNode;
+      if (node is NullabilityNodeMutable) {
+        var oldNullability = _setNullable(node, Nullability.exactNullable);
+        if (!oldNullability.isExactNullable) {
+          // Was not previously in the "exact nullable" state.  Need to
+          // propagate.
+          for (var edge in node._upstreamEdges) {
+            pendingEdges.add(edge);
+          }
+        }
+      }
+    }
+  }
+
+  Nullability _setNullable(NullabilityNodeMutable node, Nullability newState) {
+    var oldState = node._nullability;
+    node._nullability = newState;
+    if (!oldState.isNullable) {
+      // Was not previously nullable, so we need to propagate.
+      _pendingEdges.addAll(node._downstreamEdges);
+      if (node is NullabilityNodeForSubstitution) {
+        _pendingSubstitutions.add(node);
+      }
+    }
+    return oldState;
+  }
 }
diff --git a/pkg/nnbd_migration/lib/src/utilities/subprocess_launcher.dart b/pkg/nnbd_migration/lib/src/utilities/subprocess_launcher.dart
index 80e3c6e..3ac4488 100644
--- a/pkg/nnbd_migration/lib/src/utilities/subprocess_launcher.dart
+++ b/pkg/nnbd_migration/lib/src/utilities/subprocess_launcher.dart
@@ -6,6 +6,8 @@
 // and extract into a separate package, generate testing and mirrors, and
 // reimport that into the SDK, before cut and paste gets out of hand.
 
+import 'dart:async';
+
 /// This is a modified version of dartdoc's
 /// SubprocessLauncher from test/src/utils.dart, for use with the
 /// nnbd_migration script.
@@ -56,6 +58,30 @@
   SubprocessLauncher(this.context, [Map<String, String> environment])
       : this.environmentDefaults = environment ?? <String, String>{};
 
+  /// Wraps [runStreamedImmediate] as a closure around
+  /// [maxParallel.addFutureFromClosure].
+  ///
+  /// This essentially implements a 'make -j N' limit for all subcommands.
+  Future<Iterable<Map>> runStreamed(String executable, List<String> arguments,
+      {String workingDirectory,
+      Map<String, String> environment,
+      bool includeParentEnvironment = true,
+      void Function(String) perLine}) async {
+    Completer<Future<Iterable<Map>>> startedProcess = Completer();
+
+    await maxParallel.addFutureFromClosure(() async {
+      Future<Iterable<Map>> runStreamedImmediateFuture;
+      runStreamedImmediateFuture = runStreamedImmediate(executable, arguments,
+          workingDirectory: workingDirectory,
+          environment: environment,
+          includeParentEnvironment: includeParentEnvironment,
+          perLine: perLine);
+      startedProcess.complete(runStreamedImmediateFuture);
+      return runStreamedImmediateFuture;
+    });
+    return await startedProcess.future;
+  }
+
   /// A wrapper around start/await process.exitCode that will display the
   /// output of the executable continuously and fail on non-zero exit codes.
   /// It will also parse any valid JSON objects (one per line) it encounters
@@ -66,7 +92,8 @@
   /// Windows (though some of the bashisms will no longer make sense).
   /// TODO(jcollins-g): refactor to return a stream of stderr/stdout lines
   ///                   and their associated JSON objects.
-  Future<Iterable<Map>> runStreamed(String executable, List<String> arguments,
+  Future<Iterable<Map>> runStreamedImmediate(
+      String executable, List<String> arguments,
       {String workingDirectory,
       Map<String, String> environment,
       bool includeParentEnvironment = true,
diff --git a/pkg/nnbd_migration/lib/src/variables.dart b/pkg/nnbd_migration/lib/src/variables.dart
index b433166..e626ca4 100644
--- a/pkg/nnbd_migration/lib/src/variables.dart
+++ b/pkg/nnbd_migration/lib/src/variables.dart
@@ -236,6 +236,14 @@
       element = element.declaration;
     }
 
+    if (element is FunctionTypeAliasElement) {
+      // For `typedef F<T> = Function(T)`, get the `function` which is (in this
+      // case) `Function(T)`. Without this we would get `Function<T>(T)` which
+      // is incorrect. This is a known issue with `.type` on typedefs in the
+      // analyzer.
+      element = (element as FunctionTypeAliasElement).function;
+    }
+
     if (element is FunctionTypedElement) {
       decoratedType =
           _alreadyMigratedCodeDecorator.decorate(element.type, element);
diff --git a/pkg/nnbd_migration/pubspec.yaml b/pkg/nnbd_migration/pubspec.yaml
index 6125049..47fa190 100644
--- a/pkg/nnbd_migration/pubspec.yaml
+++ b/pkg/nnbd_migration/pubspec.yaml
@@ -5,6 +5,7 @@
 dependencies:
   _fe_analyzer_shared: 1.0.0
   analyzer: ^0.37.0
+  path: ^1.6.2
 dev_dependencies:
   args: ^1.5.2
-  path: ^1.6.2
+  mockito: any
diff --git a/pkg/nnbd_migration/test/already_migrated_code_decorator_test.dart b/pkg/nnbd_migration/test/already_migrated_code_decorator_test.dart
index b5fda8f..e5a9edc 100644
--- a/pkg/nnbd_migration/test/already_migrated_code_decorator_test.dart
+++ b/pkg/nnbd_migration/test/already_migrated_code_decorator_test.dart
@@ -68,7 +68,7 @@
   }
 
   void checkExplicitlyNonNullable(NullabilityNode node) {
-    var edge = assertEdge(node, never, hard: true);
+    var edge = assertEdge(node, never, hard: true, checkable: false);
     var origin = graph.getEdgeOrigin(edge);
     expect(origin.kind, EdgeOriginKind.alreadyMigratedType);
     expect(origin.element, same(element));
diff --git a/pkg/nnbd_migration/test/api_test.dart b/pkg/nnbd_migration/test/api_test.dart
index 590477d..e20e529 100644
--- a/pkg/nnbd_migration/test/api_test.dart
+++ b/pkg/nnbd_migration/test/api_test.dart
@@ -40,7 +40,11 @@
   /// be removed in its entirety (the default) or removed by commenting it out.
   Future<void> _checkMultipleFileChanges(
       Map<String, String> input, Map<String, String> expectedOutput,
-      {bool removeViaComments = false}) async {
+      {Map<String, String> migratedInput = const {},
+      bool removeViaComments = false}) async {
+    for (var path in migratedInput.keys) {
+      driver.getFileSync(newFile(path, content: migratedInput[path]).path);
+    }
     for (var path in input.keys) {
       driver.getFileSync(newFile(path, content: input[path]).path);
     }
@@ -79,11 +83,12 @@
   /// Optional parameter [removeViaComments] indicates whether dead code should
   /// be removed in its entirety (the default) or removed by commenting it out.
   Future<void> _checkSingleFileChanges(String content, String expected,
-      {bool removeViaComments = false}) async {
+      {Map<String, String> migratedInput = const {},
+      bool removeViaComments = false}) async {
     var sourcePath = convertPath('/home/test/lib/test.dart');
     await _checkMultipleFileChanges(
         {sourcePath: content}, {sourcePath: expected},
-        removeViaComments: removeViaComments);
+        migratedInput: migratedInput, removeViaComments: removeViaComments);
   }
 }
 
@@ -473,10 +478,10 @@
 num f4<T extends num>(bool b, num x, T y) => b ? x : y;
 
 void main() {
-  int? x1 = f1<int?/*?*/>(true, 0, null);
-  int? x2 = f2<int/*!*/>(true, 0, null);
-  int? x3 = f3<int>(true, null, 0);
-  int x4 = f4<int>(true, 0, 0);
+  int? x1 = f1<int?/*?*/>(true, 0, null) as int?;
+  int? x2 = f2<int/*!*/>(true, 0, null) as int?;
+  int? x3 = f3<int>(true, null, 0) as int?;
+  int x4 = f4<int>(true, 0, 0) as int;
 }
 ''';
     await _checkSingleFileChanges(content, expected);
@@ -1100,9 +1105,9 @@
     // Don't assume any new nullabilities, but keep known nullabilities.
     var expected = '''
 void f(Function a) {
-  int Function<T>(String y) f1 = a;
+  int Function<T>(String y) f1 = a as int Function<T>(String);
   Function? b = null;
-  int Function<T>(String y)? f2 = b;
+  int Function<T>(String y)? f2 = b as int Function<T>(String)?;
 }
 ''';
     await _checkSingleFileChanges(content, expected);
@@ -1139,7 +1144,7 @@
 ''';
 
     var expected = '''
-List<int?> f(List a) => a;
+List<int?> f(List a) => a as List<int?>;
 void main() {
   f(<int?>[null]);
 }
@@ -1195,7 +1200,7 @@
 ''';
 
     var expected = '''
-List<int?> f(Iterable<num?> a) => a;
+List<int?> f(Iterable<num?> a) => a as List<int?>;
 void main() {
   f(<num?>[null]);
 }
@@ -1755,7 +1760,6 @@
     await _checkSingleFileChanges(content, expected);
   }
 
-  @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/39404')
   Future<void> test_field_type_inferred() async {
     var content = '''
 int f() => null;
@@ -1980,6 +1984,38 @@
     await _checkSingleFileChanges(content, expected);
   }
 
+  Future<void> test_future_or_t_downcast_to_t() async {
+    var content = '''
+import 'dart:async';
+void f(
+    FutureOr<int> foi1,
+    FutureOr<int/*?*/> foi2,
+    FutureOr<int>/*?*/ foi3,
+    FutureOr<int/*?*/>/*?*/ foi4
+) {
+  int i1 = foi1;
+  int i2 = foi2;
+  int i3 = foi3;
+  int i4 = foi4;
+}
+''';
+    var expected = '''
+import 'dart:async';
+void f(
+    FutureOr<int> foi1,
+    FutureOr<int?/*?*/> foi2,
+    FutureOr<int>?/*?*/ foi3,
+    FutureOr<int?/*?*/>?/*?*/ foi4
+) {
+  int i1 = foi1 as int;
+  int? i2 = foi2 as int?;
+  int? i3 = foi3 as int?;
+  int? i4 = foi4 as int?;
+}
+''';
+    await _checkSingleFileChanges(content, expected);
+  }
+
   Future<void> test_generic_exact_propagation() async {
     var content = '''
 class C<T> {
@@ -2574,6 +2610,12 @@
     await _checkSingleFileChanges(content, expected);
   }
 
+  Future<void> test_leave_downcast_from_dynamic_implicit() async {
+    var content = 'int f(dynamic n) => n;';
+    var expected = 'int f(dynamic n) => n;';
+    await _checkSingleFileChanges(content, expected);
+  }
+
   Future<void> test_libraryWithParts() async {
     var root = '/home/test/lib';
     var path1 = convertPath('$root/lib.dart');
@@ -2650,7 +2692,6 @@
     await _checkSingleFileChanges(content, expected);
   }
 
-  @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/39404')
   Future<void> test_localVariable_type_inferred() async {
     var content = '''
 int f() => null;
@@ -2671,10 +2712,13 @@
     await _checkSingleFileChanges(content, expected);
   }
 
-  @failingTest
+  Future<void> test_make_downcast_explicit() async {
+    var content = 'int f(num n) => n;';
+    var expected = 'int f(num n) => n as int;';
+    await _checkSingleFileChanges(content, expected);
+  }
+
   Future<void> test_map_nullable_input() async {
-    // TODO(paulberry): we're currently migrating this example incorrectly.
-    // See discussion at https://dart-review.googlesource.com/c/sdk/+/115766
     var content = '''
 Iterable<int> f(List<int> x) => x.map((y) => g(y));
 int g(int x) => x + 1;
@@ -2692,6 +2736,24 @@
     await _checkSingleFileChanges(content, expected);
   }
 
+  Future<void> test_map_nullable_input_tearoff() async {
+    var content = '''
+Iterable<int> f(List<int> x) => x.map(g);
+int g(int x) => x + 1;
+main() {
+  f([null]);
+}
+''';
+    var expected = '''
+Iterable<int> f(List<int?> x) => x.map(g);
+int g(int? x) => x! + 1;
+main() {
+  f([null]);
+}
+''';
+    await _checkSingleFileChanges(content, expected);
+  }
+
   Future<void> test_map_nullable_output() async {
     var content = '''
 Iterable<int> f(List<int> x) => x.map((y) => g(y));
@@ -3105,6 +3167,27 @@
     await _checkSingleFileChanges(content, expected);
   }
 
+  Future<void>
+      test_non_nullable_hint_comment_overrides_uncheckable_edge() async {
+    var content = '''
+Iterable<int> f(List<int> x) => x.map(g);
+int g(int/*!*/ x) => x + 1;
+main() {
+  f([null]);
+}
+''';
+    // TODO(paulberry): we should do something to flag the fact that g can't be
+    // safely passed to f.
+    var expected = '''
+Iterable<int> f(List<int?> x) => x.map(g as int Function(int?));
+int g(int/*!*/ x) => x + 1;
+main() {
+  f([null]);
+}
+''';
+    await _checkSingleFileChanges(content, expected);
+  }
+
   Future<void> test_not_definitely_assigned_value() async {
     var content = '''
 String f(bool b) {
@@ -3286,7 +3369,7 @@
 }
 class Derived extends Base {
   void f(int i) {
-    assert(i != null);
+    i + 1;
   }
 }
 void g(int i, bool b, Base base) {
@@ -3300,16 +3383,16 @@
 ''';
     var expected = '''
 abstract class Base {
-  void f(int i);
+  void f(int? i);
 }
 class Derived extends Base {
-  void f(int i) {
-    assert(i != null);
+  void f(int? i) {
+    i! + 1;
   }
 }
 void g(int? i, bool b, Base base) {
   if (b) {
-    base.f(i!);
+    base.f(i);
   }
 }
 void h(Base base) {
@@ -3753,6 +3836,36 @@
     await _checkSingleFileChanges(content, expected);
   }
 
+  Future<void> test_tearoff_parameter_matching_named() async {
+    var content = '''
+void f(int x, void Function({int x}) callback) {
+  callback(x: x);
+}
+void g({int x}) {
+  assert(x != null);
+}
+void h() {
+  f(null, g);
+}
+''';
+    // Normally the assertion in g would cause g's `x` argument to be
+    // non-nullable (and thus required).  However, since g is torn off and
+    // passed to f, which requires a callback that accepts null, g's `x`
+    // argument is nullable (and thus not required).
+    var expected = '''
+void f(int? x, void Function({int? x}) callback) {
+  callback(x: x);
+}
+void g({int? x}) {
+  assert(x != null);
+}
+void h() {
+  f(null, g);
+}
+''';
+    await _checkSingleFileChanges(content, expected);
+  }
+
   Future<void> test_topLevelFunction_parameterType_implicit_dynamic() async {
     var content = '''
 Object f(x) => x;
@@ -3779,7 +3892,6 @@
     await _checkSingleFileChanges(content, expected);
   }
 
-  @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/39404')
   Future<void> test_topLevelVariable_type_inferred() async {
     var content = '''
 int f() => null;
@@ -3888,6 +4000,79 @@
     await _checkSingleFileChanges(content, expected);
   }
 
+  Future<void> test_typedef_assign_null_migrated_lhs_parameters() async {
+    var content = '''
+import 'migrated_typedef.dart';
+void main(F<int> f) {
+  f(null);
+}
+''';
+    var expected = '''
+import 'migrated_typedef.dart';
+void main(F<int?> f) {
+  f(null);
+}
+''';
+    await _checkSingleFileChanges(content, expected, migratedInput: {
+      '/home/test/lib/migrated_typedef.dart': 'typedef F<R> = Function(R);'
+    });
+  }
+
+  Future<void> test_typedef_assign_null_migrated_lhs_rhs_parameters() async {
+    var content = '''
+import 'migrated_typedef.dart';
+void f1(F<int> f) {
+  f<int>(null, null);
+}
+void f2(F<int> f) {
+  f<int>(0, null);
+}
+void f3(F<int> f) {
+  f<int>(null, 1);
+}
+void f4(F<int> f) {
+  f<int>(0, 1);
+}
+''';
+    var expected = '''
+import 'migrated_typedef.dart';
+void f1(F<int?> f) {
+  f<int?>(null, null);
+}
+void f2(F<int> f) {
+  f<int?>(0, null);
+}
+void f3(F<int?> f) {
+  f<int>(null, 1);
+}
+void f4(F<int> f) {
+  f<int>(0, 1);
+}
+''';
+    await _checkSingleFileChanges(content, expected, migratedInput: {
+      '/home/test/lib/migrated_typedef.dart':
+          'typedef F<T> = Function<R>(T, R);'
+    });
+  }
+
+  Future<void> test_typedef_assign_null_migrated_rhs_parameters() async {
+    var content = '''
+import 'migrated_typedef.dart';
+void main(F f) {
+  f<int>(null);
+}
+''';
+    var expected = '''
+import 'migrated_typedef.dart';
+void main(F f) {
+  f<int?>(null);
+}
+''';
+    await _checkSingleFileChanges(content, expected, migratedInput: {
+      '/home/test/lib/migrated_typedef.dart': 'typedef F = Function<R>(R);'
+    });
+  }
+
   Future<void> test_typedef_assign_null_parameter() async {
     var content = '''
 typedef F = Function(int);
@@ -3924,6 +4109,7 @@
     await _checkSingleFileChanges(content, expected);
   }
 
+  @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/40388')
   Future<void> test_typedef_assign_null_return_type_formal() async {
     var content = '''
 typedef F = T Function<T>();
diff --git a/pkg/nnbd_migration/test/decorated_type_test.dart b/pkg/nnbd_migration/test/decorated_type_test.dart
index fd5c2c3..3a6a0e8 100644
--- a/pkg/nnbd_migration/test/decorated_type_test.dart
+++ b/pkg/nnbd_migration/test/decorated_type_test.dart
@@ -317,6 +317,30 @@
     assertDartType(type, 'dynamic');
   }
 
+  void test_toFinalType_function_generic_bound_dynamic() {
+    var t = typeParameter('T', dynamic_);
+    var type = function(dynamic_, typeFormals: [t], node: never)
+        .toFinalType(typeProvider) as FunctionType;
+    assertDartType(type, 'dynamic Function<T>()');
+    expect(type.typeFormals[0].bound, isNull);
+  }
+
+  void test_toFinalType_function_generic_bound_num_question() {
+    var t = typeParameter('T', num_(node: always));
+    var type = function(dynamic_, typeFormals: [t], node: never)
+        .toFinalType(typeProvider) as FunctionType;
+    assertDartType(type, 'dynamic Function<T extends num?>()');
+    assertDartType(type.typeFormals[0].bound, 'num?');
+  }
+
+  void test_toFinalType_function_generic_bound_object_question() {
+    var t = typeParameter('T', object(node: always));
+    var type = function(dynamic_, typeFormals: [t], node: never)
+        .toFinalType(typeProvider) as FunctionType;
+    assertDartType(type, 'dynamic Function<T>()');
+    expect(type.typeFormals[0].bound, isNull);
+  }
+
   void test_toFinalType_function_generic_substitute_bounds() {
     var u = typeParameter('U', object(node: never));
     var t = typeParameter(
diff --git a/pkg/nnbd_migration/test/edge_builder_test.dart b/pkg/nnbd_migration/test/edge_builder_test.dart
index d72d823..885513f 100644
--- a/pkg/nnbd_migration/test/edge_builder_test.dart
+++ b/pkg/nnbd_migration/test/edge_builder_test.dart
@@ -133,7 +133,7 @@
     assign(t1, t2, hard: true);
     // Note: t1 and t2 are swapped due to contravariance.
     assertEdge(t2.namedParameters['x'].node, t1.namedParameters['x'].node,
-        hard: false);
+        hard: false, checkable: false);
   }
 
   void test_function_type_named_to_no_parameter() {
@@ -149,7 +149,7 @@
     assign(t1, t2, hard: true);
     // Note: t1 and t2 are swapped due to contravariance.
     assertEdge(t2.positionalParameters[0].node, t1.positionalParameters[0].node,
-        hard: false);
+        hard: false, checkable: false);
   }
 
   void test_function_type_positional_to_no_parameter() {
@@ -165,7 +165,7 @@
     assign(t1, t2, hard: true);
     // Note: t1 and t2 are swapped due to contravariance.
     assertEdge(t2.positionalParameters[0].node, t1.positionalParameters[0].node,
-        hard: false);
+        hard: false, checkable: false);
   }
 
   void test_function_type_required_parameter() {
@@ -174,7 +174,7 @@
     assign(t1, t2);
     // Note: t1 and t2 are swapped due to contravariance.
     assertEdge(t2.positionalParameters[0].node, t1.positionalParameters[0].node,
-        hard: false);
+        hard: false, checkable: false);
   }
 
   void test_function_type_return_type() {
@@ -201,6 +201,47 @@
     assertEdge(t1.typeArguments[0].node, t2.typeArguments[0].node, hard: false);
   }
 
+  void test_future_or_int_to_future_int() {
+    var t1 = futureOr(int_());
+    var t2 = future(int_());
+    assign(t1, t2, hard: true);
+    // FutureOr<int>? is nullable, so Future<int>? should be.
+    assertEdge(t1.node, t2.node, hard: true);
+    // FutureOr<int?> is nullable, so Future<int>? should be.
+    assertEdge(t1.typeArguments[0].node, t2.node, hard: true);
+    // FutureOr<int?> may hold a Future<int?>, so carry that forward.
+    assertEdge(t1.typeArguments[0].node, t2.typeArguments[0].node, hard: false);
+    // FutureOr<int>? does not accept a Future<int?>, so don't draw this.
+    assertNoEdge(t1.node, t2.typeArguments[0].node);
+  }
+
+  void test_future_or_int_to_int() {
+    var t1 = futureOr(int_());
+    var t2 = int_();
+    assign(t1, t2, hard: true);
+    assertEdge(t1.node, t2.node, hard: true);
+    assertEdge(t1.typeArguments[0].node, t2.node, hard: false);
+  }
+
+  void test_future_or_list_object_to_list_int() {
+    var t1 = futureOr(list(object()));
+    var t2 = list(int_());
+    assign(t1, t2, hard: true);
+    assertEdge(t1.node, t2.node, hard: true);
+    assertEdge(t1.typeArguments[0].node, t2.node, hard: false);
+    assertEdge(
+        t1.typeArguments[0].typeArguments[0].node, t2.typeArguments[0].node,
+        hard: false);
+  }
+
+  void test_future_or_object_to_future_or_int() {
+    var t1 = futureOr(object());
+    var t2 = futureOr(int_());
+    assign(t1, t2, hard: true);
+    assertEdge(t1.node, t2.node, hard: true);
+    assertEdge(t1.typeArguments[0].node, t2.typeArguments[0].node, hard: false);
+  }
+
   void test_future_or_to_future_or() {
     var t1 = futureOr(int_());
     var t2 = futureOr(int_());
@@ -855,6 +896,16 @@
         hard: true);
   }
 
+  Future<void> test_assign_to_bound_in_return_type() async {
+    await analyze('''
+class C<T extends Object> {}
+C<int> f() => null;
+''');
+    assertEdge(decoratedTypeAnnotation('int').node,
+        decoratedTypeAnnotation('Object').node,
+        hard: true);
+  }
+
   Future<void> test_assign_to_bound_in_type_argument() async {
     await analyze('''
 class C<T extends Object> {}
@@ -868,16 +919,6 @@
         hard: true);
   }
 
-  Future<void> test_assign_to_bound_in_return_type() async {
-    await analyze('''
-class C<T extends Object> {}
-C<int> f() => null;
-''');
-    assertEdge(decoratedTypeAnnotation('int').node,
-        decoratedTypeAnnotation('Object').node,
-        hard: true);
-  }
-
   Future<void> test_assign_to_bound_instance_creation() async {
     await analyze('''
 class C<T extends Object> {}
@@ -1262,8 +1303,9 @@
     var yParamNullable = decoratedTypeAnnotation('int) y').node;
     var returnParamNullable = decoratedTypeAnnotation('int) f').node;
     assertEdge(xParamNullable, yParamNullable,
-        hard: false, guards: [xNullable]);
-    assertEdge(returnParamNullable, xParamNullable, hard: false);
+        hard: false, checkable: false, guards: [xNullable]);
+    assertEdge(returnParamNullable, xParamNullable,
+        hard: false, checkable: false);
   }
 
   Future<void> test_assignmentExpression_nullAware_complex_covariant() async {
@@ -1475,7 +1517,10 @@
 ''');
     var iNode = decoratedTypeAnnotation('int i').node;
     var jNode = decoratedTypeAnnotation('int j').node;
-    assertEdge(iNode, jNode, hard: false, guards: [alwaysPlus.toList()[1]]);
+    assertEdge(iNode, jNode,
+        hard: false,
+        guards: TypeMatcher<Iterable<NullabilityNode>>()
+            .having((g) => g.single, 'single value', isIn(alwaysPlus)));
   }
 
   Future<void> test_binaryExpression_equal_null_yoda_condition() async {
@@ -2119,6 +2164,21 @@
         bBound.typeArguments[0].node);
   }
 
+  Future<void> test_conditionalExpression_left_never() async {
+    await analyze('''
+List<int> f(bool b, List<int> i) {
+  return (b ? (throw i) : i);
+}
+''');
+
+    var nullable_i = decoratedTypeAnnotation('List<int> i').node;
+    var nullable_conditional =
+        decoratedExpressionType('(b ?').node as NullabilityNodeForLUB;
+    var nullable_throw = nullable_conditional.left;
+    assertNoUpstreamNullability(nullable_throw);
+    assertLUB(nullable_conditional, nullable_throw, nullable_i);
+  }
+
   Future<void> test_conditionalExpression_left_non_null() async {
     await analyze('''
 int f(bool b, int i) {
@@ -2213,6 +2273,21 @@
     assertLUB(nullable_conditional, nullable_x, nullable_y);
   }
 
+  Future<void> test_conditionalExpression_right_never() async {
+    await analyze('''
+List<int> f(bool b, List<int> i) {
+  return (b ? i : (throw i));
+}
+''');
+
+    var nullable_i = decoratedTypeAnnotation('List<int> i').node;
+    var nullable_conditional =
+        decoratedExpressionType('(b ?').node as NullabilityNodeForLUB;
+    var nullable_throw = nullable_conditional.right;
+    assertNoUpstreamNullability(nullable_throw);
+    assertLUB(nullable_conditional, nullable_i, nullable_throw);
+  }
+
   Future<void> test_conditionalExpression_right_non_null() async {
     await analyze('''
 int f(bool b, int i) {
@@ -2610,10 +2685,10 @@
         hard: false);
     assertEdge(fieldType.positionalParameters[0].node,
         ctorParamType.positionalParameters[0].node,
-        hard: false);
+        hard: false, checkable: false);
     assertEdge(fieldType.namedParameters['j'].node,
         ctorParamType.namedParameters['j'].node,
-        hard: false);
+        hard: false, checkable: false);
   }
 
   Future<void> test_fieldFormalParameter_typed() async {
@@ -4323,7 +4398,7 @@
         .decoratedElementType(addMethod.declaration)
         .positionalParameters[0]
         .node;
-    assertEdge(nullable_t, never, hard: true);
+    assertEdge(nullable_t, never, hard: true, checkable: false);
     var check_i = checkExpression('i/*check*/');
     var nullable_list_t_or_nullable_t = check_i
         .checks.edges.single.destinationNode as NullabilityNodeForSubstitution;
@@ -4683,7 +4758,7 @@
 ''');
     var int1 = decoratedTypeAnnotation('int/*1*/');
     var int2 = decoratedTypeAnnotation('int/*2*/');
-    assertEdge(int1.node, int2.node, hard: true);
+    assertEdge(int1.node, int2.node, hard: false, checkable: false);
   }
 
   Future<void> test_override_parameter_type_named_over_none() async {
@@ -4709,7 +4784,7 @@
 ''');
     var base1 = decoratedTypeAnnotation('Base/*1*/');
     var base2 = decoratedTypeAnnotation('Base/*2*/');
-    assertEdge(base1.node, base2.node, hard: true);
+    assertEdge(base1.node, base2.node, hard: false, checkable: false);
   }
 
   Future<void> test_override_parameter_type_optional() async {
@@ -4723,7 +4798,7 @@
 ''');
     var int1 = decoratedTypeAnnotation('int/*1*/');
     var int2 = decoratedTypeAnnotation('int/*2*/');
-    assertEdge(int1.node, int2.node, hard: true);
+    assertEdge(int1.node, int2.node, hard: false, checkable: false);
   }
 
   Future<void> test_override_parameter_type_optional_over_none() async {
@@ -4749,7 +4824,7 @@
 ''');
     var int1 = decoratedTypeAnnotation('int/*1*/');
     var int2 = decoratedTypeAnnotation('int/*2*/');
-    assertEdge(int1.node, int2.node, hard: true);
+    assertEdge(int1.node, int2.node, hard: false, checkable: false);
   }
 
   Future<void> test_override_parameter_type_required() async {
@@ -4763,7 +4838,7 @@
 ''');
     var int1 = decoratedTypeAnnotation('int/*1*/');
     var int2 = decoratedTypeAnnotation('int/*2*/');
-    assertEdge(int1.node, int2.node, hard: true);
+    assertEdge(int1.node, int2.node, hard: false, checkable: false);
   }
 
   Future<void> test_override_parameter_type_setter() async {
@@ -4777,7 +4852,7 @@
 ''');
     var int1 = decoratedTypeAnnotation('int/*1*/');
     var int2 = decoratedTypeAnnotation('int/*2*/');
-    assertEdge(int1.node, int2.node, hard: true);
+    assertEdge(int1.node, int2.node, hard: false, checkable: false);
   }
 
   Future<void> test_override_return_type_getter() async {
@@ -5694,7 +5769,7 @@
     assertEdge(fType.returnType.node, gReturnType.returnType.node, hard: false);
     assertEdge(gReturnType.positionalParameters[0].node,
         fType.positionalParameters[0].node,
-        hard: false);
+        hard: false, checkable: false);
   }
 
   Future<void> test_prefixExpression_bang() async {
@@ -6398,7 +6473,7 @@
     assertEdge(fType.returnType.node, gReturnType.returnType.node, hard: false);
     assertEdge(gReturnType.positionalParameters[0].node,
         fType.positionalParameters[0].node,
-        hard: false);
+        hard: false, checkable: false);
   }
 
   Future<void> test_simpleIdentifier_tearoff_method() async {
@@ -6414,7 +6489,7 @@
     assertEdge(fType.returnType.node, gReturnType.returnType.node, hard: false);
     assertEdge(gReturnType.positionalParameters[0].node,
         fType.positionalParameters[0].node,
-        hard: false);
+        hard: false, checkable: false);
   }
 
   Future<void> test_skipDirectives() async {
diff --git a/pkg/nnbd_migration/test/edit_plan_test.dart b/pkg/nnbd_migration/test/edit_plan_test.dart
index 8833866..401eb4d 100644
--- a/pkg/nnbd_migration/test/edit_plan_test.dart
+++ b/pkg/nnbd_migration/test/edit_plan_test.dart
@@ -361,6 +361,17 @@
         'var x = 0; var y = 0;');
   }
 
+  Future<void> test_insertText() async {
+    await analyze('final x = 1;');
+    var variableDeclarationList = findNode.variableDeclarationList('final');
+    checkPlan(
+        planner.insertText(
+            variableDeclarationList,
+            variableDeclarationList.variables.first.offset,
+            [AtomicEdit.insert('int ')]),
+        'final int x = 1;');
+  }
+
   Future<void> test_makeNullable() async {
     await analyze('int x = 0;');
     checkPlan(
@@ -952,34 +963,37 @@
     await analyze('f(x) => x?.m(0);');
     var methodInvocation = findNode.methodInvocation('?.');
     checkPlan(
-        planner.removeNullAwarenessFromMethodInvocation(methodInvocation,
-            argumentListPlan:
-                planner.passThrough(methodInvocation.argumentList, innerPlans: [
-              planner.replace(
-                  findNode.integerLiteral('0'), [AtomicEdit.insert('1')])
-            ])),
+        planner.passThrough(methodInvocation, innerPlans: [
+          planner.removeNullAwareness(methodInvocation),
+          planner.passThrough(methodInvocation.argumentList, innerPlans: [
+            planner
+                .replace(findNode.integerLiteral('0'), [AtomicEdit.insert('1')])
+          ])
+        ]),
         'f(x) => x.m(1);');
   }
 
   Future<void>
       test_removeNullAwarenessFromMethodInvocation_change_methodName() async {
     await analyze('f(x) => x?.m();');
+    var methodInvocation = findNode.methodInvocation('?.');
     checkPlan(
-        planner.removeNullAwarenessFromMethodInvocation(
-            findNode.methodInvocation('?.'),
-            methodNamePlan: planner
-                .replace(findNode.simple('m'), [AtomicEdit.insert('n')])),
+        planner.passThrough(methodInvocation, innerPlans: [
+          planner.removeNullAwareness(methodInvocation),
+          planner.replace(findNode.simple('m'), [AtomicEdit.insert('n')])
+        ]),
         'f(x) => x.n();');
   }
 
   Future<void>
       test_removeNullAwarenessFromMethodInvocation_change_target() async {
     await analyze('f(x) => x?.m();');
+    var methodInvocation = findNode.methodInvocation('?.');
     checkPlan(
-        planner.removeNullAwarenessFromMethodInvocation(
-            findNode.methodInvocation('?.'),
-            targetPlan: planner
-                .replace(findNode.simple('x?.'), [AtomicEdit.insert('y')])),
+        planner.passThrough(methodInvocation, innerPlans: [
+          planner.replace(findNode.simple('x?.'), [AtomicEdit.insert('y')]),
+          planner.removeNullAwareness(methodInvocation)
+        ]),
         'f(x) => y.m();');
   }
 
@@ -988,62 +1002,66 @@
     await analyze('f(x) => x?.m<int>();');
     var methodInvocation = findNode.methodInvocation('?.');
     checkPlan(
-        planner.removeNullAwarenessFromMethodInvocation(methodInvocation,
-            typeArgumentsPlan: planner
-                .passThrough(methodInvocation.typeArguments, innerPlans: [
-              planner
-                  .replace(findNode.simple('int'), [AtomicEdit.insert('num')])
-            ])),
+        planner.passThrough(methodInvocation, innerPlans: [
+          planner.removeNullAwareness(methodInvocation),
+          planner.passThrough(methodInvocation.typeArguments, innerPlans: [
+            planner.replace(findNode.simple('int'), [AtomicEdit.insert('num')])
+          ])
+        ]),
         'f(x) => x.m<num>();');
   }
 
   Future<void> test_removeNullAwarenessFromMethodInvocation_simple() async {
     await analyze('f(x) => x?.m();');
+    var methodInvocation = findNode.methodInvocation('?.');
     checkPlan(
-        planner.removeNullAwarenessFromMethodInvocation(
-            findNode.methodInvocation('?.')),
+        planner.passThrough(methodInvocation,
+            innerPlans: [planner.removeNullAwareness(methodInvocation)]),
         'f(x) => x.m();');
   }
 
   Future<void> test_removeNullAwarenessFromPropertyAccess_change_both() async {
     await analyze('f(x) => x?.y;');
+    var propertyAccess = findNode.propertyAccess('?.');
     checkPlan(
-        planner.removeNullAwarenessFromPropertyAccess(
-            findNode.propertyAccess('?.'),
-            targetPlan: planner
-                .replace(findNode.simple('x?.'), [AtomicEdit.insert('z')]),
-            propertyNamePlan: planner
-                .replace(findNode.simple('y'), [AtomicEdit.insert('w')])),
+        planner.passThrough(propertyAccess, innerPlans: [
+          (planner.replace(findNode.simple('x?.'), [AtomicEdit.insert('z')])),
+          planner.removeNullAwareness(propertyAccess),
+          planner.replace(findNode.simple('y'), [AtomicEdit.insert('w')])
+        ]),
         'f(x) => z.w;');
   }
 
   Future<void>
       test_removeNullAwarenessFromPropertyAccess_change_propertyName() async {
     await analyze('f(x) => x?.y;');
+    var propertyAccess = findNode.propertyAccess('?.');
     checkPlan(
-        planner.removeNullAwarenessFromPropertyAccess(
-            findNode.propertyAccess('?.'),
-            propertyNamePlan: planner
-                .replace(findNode.simple('y'), [AtomicEdit.insert('w')])),
+        planner.passThrough(propertyAccess, innerPlans: [
+          planner.removeNullAwareness(propertyAccess),
+          planner.replace(findNode.simple('y'), [AtomicEdit.insert('w')])
+        ]),
         'f(x) => x.w;');
   }
 
   Future<void>
       test_removeNullAwarenessFromPropertyAccess_change_target() async {
     await analyze('f(x) => x?.y;');
+    var propertyAccess = findNode.propertyAccess('?.');
     checkPlan(
-        planner.removeNullAwarenessFromPropertyAccess(
-            findNode.propertyAccess('?.'),
-            targetPlan: planner
-                .replace(findNode.simple('x?.'), [AtomicEdit.insert('z')])),
+        planner.passThrough(propertyAccess, innerPlans: [
+          planner.replace(findNode.simple('x?.'), [AtomicEdit.insert('z')]),
+          planner.removeNullAwareness(propertyAccess)
+        ]),
         'f(x) => z.y;');
   }
 
   Future<void> test_removeNullAwarenessFromPropertyAccess_simple() async {
     await analyze('f(x) => x?.y;');
+    var propertyAccess = findNode.propertyAccess('?.');
     checkPlan(
-        planner.removeNullAwarenessFromPropertyAccess(
-            findNode.propertyAccess('?.')),
+        planner.passThrough(propertyAccess,
+            innerPlans: [planner.removeNullAwareness(propertyAccess)]),
         'f(x) => x.y;');
   }
 
@@ -1069,6 +1087,15 @@
         'var x = 1 + (y = z);');
   }
 
+  Future<void> test_replaceToken() async {
+    await analyze('var x = 1;');
+    var variableDeclarationList = findNode.variableDeclarationList('var x');
+    checkPlan(
+        planner.replaceToken(variableDeclarationList,
+            variableDeclarationList.keyword, [AtomicEdit.insert('int')]),
+        'int x = 1;');
+  }
+
   Future<void> test_surround_allowCascade() async {
     await analyze('f(x) => 1..isEven;');
     checkPlan(
diff --git a/pkg/nnbd_migration/test/fantasyland/fantasy_repo_test.dart b/pkg/nnbd_migration/test/fantasyland/fantasy_repo_test.dart
new file mode 100644
index 0000000..9d64001
--- /dev/null
+++ b/pkg/nnbd_migration/test/fantasyland/fantasy_repo_test.dart
@@ -0,0 +1,228 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:io';
+
+import 'package:mockito/mockito.dart';
+import 'package:nnbd_migration/src/fantasyland/fantasy_repo.dart';
+import 'package:nnbd_migration/src/utilities/subprocess_launcher.dart';
+import 'package:path/path.dart' as path;
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(FantasyRepoSettingsTest);
+    defineReflectiveTests(FantasyRepoE2ETest);
+    defineReflectiveTests(FantasyRepoTest);
+  });
+}
+
+@reflectiveTest
+class FantasyRepoSettingsTest {
+  test_fromNameDefaultCase() {
+    FantasyRepoSettings settings = FantasyRepoSettings.fromName('defaultCase');
+
+    expect(settings.name, equals('defaultCase'));
+    expect(settings.clone, equals('git@github.com:dart-lang/defaultCase.git'));
+    expect(settings.branch, equals('master'));
+    expect(settings.revision, equals('master'));
+  }
+
+  test_fromNameDotDartCase() {
+    FantasyRepoSettings settings =
+        FantasyRepoSettings.fromName('somethingImportant.dart');
+
+    expect(settings.name, equals('somethingImportant.dart'));
+    expect(settings.clone,
+        equals('git@github.com:google/somethingImportant.dart.git'));
+    expect(settings.branch, equals('master'));
+    expect(settings.revision, equals('master'));
+  }
+
+  test_fromNameTableCase() {
+    FantasyRepoSettings settings = FantasyRepoSettings.fromName('git');
+
+    expect(settings.name, equals('git'));
+    expect(settings.clone, equals('git@github.com:kevmoo/git.git'));
+    expect(settings.branch, equals('master'));
+    expect(settings.revision, equals('master'));
+  }
+
+  test_equality() {
+    var test1 = FantasyRepoSettings('one', 'two', 'three', 'four');
+    var test2 = FantasyRepoSettings('one', 'two', 'three', 'four');
+    var test3 = FantasyRepoSettings('one', 'two', 'three', 'five');
+    var test4 = FantasyRepoSettings('one', 'two');
+
+    expect(test1, equals(test2));
+    expect(test1, isNot(equals(test3)));
+    expect(test1, isNot(equals(test4)));
+  }
+}
+
+@reflectiveTest
+class FantasyRepoE2ETest {
+  Directory tempDir;
+
+  setUp() async {
+    tempDir = await Directory.systemTemp.createTemp('FantasyRepoE2ETest');
+  }
+
+  test_fantasyRepoE2ETest() async {
+    // Only one of these, as they are slow due to the real fork/execs of 'git'.
+    // Check any important edge cases via unit tests and mocking.
+
+    // TODO(jcollins-g): This test is not fully isolated from the global git
+    // config.  Fix that.
+    SubprocessLauncher launcher = SubprocessLauncher('FantasyRepoE2ETest');
+    Directory origRepoDir = Directory(path.join(tempDir.path, 'origRepo'));
+
+    // Create and add a commit to origRepoDir that includes a file we should
+    // check out, and others we shouldn't.
+    await launcher.runStreamed('git', ['init', origRepoDir.path]);
+    File dotPackages = File(path.join(origRepoDir.path, '.packages'));
+    File pubspecLock = File(path.join(origRepoDir.path, 'pubspec.lock'));
+    File pubspecYaml = File(path.join(origRepoDir.path, 'pubspec.yaml'));
+    File packageConfigJson =
+        File(path.join(origRepoDir.path, '.dart_tool', 'package_config.json'));
+    List<File> allFiles = [
+      dotPackages,
+      pubspecLock,
+      pubspecYaml,
+      packageConfigJson
+    ];
+    await Future.wait([
+      for (var f in [dotPackages, pubspecLock, pubspecYaml, packageConfigJson])
+        f.create(recursive: true)
+    ]);
+    await launcher.runStreamed(
+        'git', ['add', '-f', ...allFiles.map((f) => path.canonicalize(f.path))],
+        workingDirectory: origRepoDir.path);
+    await launcher.runStreamed('git', ['commit', '-m', 'add some files'],
+        workingDirectory: origRepoDir.path);
+
+    // Use the repo builder to clone this and verify that the right files are
+    // checked out.
+    Directory repoRoot = Directory(path.join(tempDir.path, 'repoRoot'));
+    await FantasyRepo.buildFrom(
+        FantasyRepoSettings('repoE2Etest', origRepoDir.path), repoRoot,
+        launcher: launcher);
+
+    dotPackages = File(path.join(repoRoot.path, '.packages'));
+    pubspecLock = File(path.join(repoRoot.path, 'pubspec.lock'));
+    pubspecYaml = File(path.join(repoRoot.path, 'pubspec.yaml'));
+    packageConfigJson =
+        File(path.join(repoRoot.path, '.dart_tool', 'package_config.json'));
+
+    expect(await dotPackages.exists(), isFalse);
+    expect(await pubspecLock.exists(), isFalse);
+    expect(await pubspecYaml.exists(), isTrue);
+    expect(await packageConfigJson.exists(), isFalse);
+
+    // Update the original repository.
+    File aNewFile = File(path.join(origRepoDir.path, 'hello_new_file_here'));
+    await aNewFile.create(recursive: true);
+    await launcher.runStreamed(
+        'git', ['add', '-f', path.canonicalize(aNewFile.path)],
+        workingDirectory: origRepoDir.path);
+    await launcher.runStreamed('git', ['commit', '-m', 'add more files'],
+        workingDirectory: origRepoDir.path);
+
+    // Finally, use the repoBuilder to update a repository from head and verify
+    // we did it right.
+    await FantasyRepo.buildFrom(
+        FantasyRepoSettings('repoE2Etest', origRepoDir.path), repoRoot,
+        launcher: launcher);
+
+    aNewFile = File(path.join(repoRoot.path, 'hello_new_file_here'));
+
+    expect(await dotPackages.exists(), isFalse);
+    expect(await pubspecLock.exists(), isFalse);
+    expect(await pubspecYaml.exists(), isTrue);
+    expect(await packageConfigJson.exists(), isFalse);
+    expect(await aNewFile.exists(), isTrue);
+  }
+}
+
+class MockDirectory extends Mock implements Directory {}
+
+class MockFile extends Mock implements File {}
+
+class MockSubprocessLauncher extends Mock implements SubprocessLauncher {}
+
+@reflectiveTest
+class FantasyRepoTest {
+  // TODO(jcollins-g): extend MemoryResourceProvider and analyzer File
+  // implementations and port over, or add mock_filesystem to third_party.
+  Map<String, MockFile> mockFiles;
+  Map<String, MockDirectory> mockDirectories;
+  MockDirectory Function(String) directoryBuilder;
+  MockFile Function(String) fileBuilder;
+  MockSubprocessLauncher mockLauncher;
+  String parentPath;
+  String repoPath;
+
+  setUp() {
+    mockFiles = {};
+    mockDirectories = {};
+    fileBuilder = (String s) {
+      mockFiles[s] ??= MockFile();
+      return mockFiles[s];
+    };
+    directoryBuilder = (String s) {
+      mockDirectories[s] ??= MockDirectory();
+      return mockDirectories[s];
+    };
+    mockLauncher = MockSubprocessLauncher();
+    parentPath = 'parentdir';
+    repoPath = path.join(parentPath, 'subdir');
+    MockDirectory repoDir = directoryBuilder(repoPath);
+    MockDirectory parentDir = directoryBuilder('parentdir');
+    when(parentDir.exists()).thenAnswer((_) => Future.value(true));
+    when(repoDir.parent).thenReturn(parentDir);
+    when(repoDir.path).thenReturn(repoPath);
+  }
+
+  _setUpNewClone(String repoName) async {
+    FantasyRepoSettings settings = FantasyRepoSettings.fromName(repoName);
+    when(directoryBuilder(repoPath).exists())
+        .thenAnswer((_) => Future.value(false));
+    await FantasyRepo.buildFrom(settings, mockDirectories[repoPath],
+        launcher: mockLauncher, fileBuilder: fileBuilder);
+  }
+
+  test_checkHttpStringSubstitution() async {
+    await _setUpNewClone('defaultCase');
+    verify(mockLauncher.runStreamed(
+        'git',
+        [
+          'remote',
+          'add',
+          'origin',
+          '-t',
+          'master',
+          'git@github.com:dart-lang/defaultCase.git'
+        ],
+        workingDirectory: repoPath));
+    verify(mockLauncher.runStreamed(
+        'git',
+        [
+          'remote',
+          'add',
+          'originHTTP',
+          '-t',
+          'master',
+          'https://github.com/dart-lang/defaultCase.git'
+        ],
+        workingDirectory: repoPath));
+  }
+
+  test_verifyWorkingDirectoryForGitConfig() async {
+    await _setUpNewClone('defaultCase');
+    verify(mockLauncher.runStreamed(
+        'git', ['config', 'core.sparsecheckout', 'true'],
+        workingDirectory: repoPath));
+  }
+}
diff --git a/pkg/nnbd_migration/test/fantasyland/fantasy_sub_package_test.dart b/pkg/nnbd_migration/test/fantasyland/fantasy_sub_package_test.dart
new file mode 100644
index 0000000..3984c66
--- /dev/null
+++ b/pkg/nnbd_migration/test/fantasyland/fantasy_sub_package_test.dart
@@ -0,0 +1,49 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:nnbd_migration/src/fantasyland/fantasy_repo.dart';
+import 'package:nnbd_migration/src/fantasyland/fantasy_sub_package.dart';
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(FantasySubPackageSettingsTest);
+  });
+}
+
+@reflectiveTest
+class FantasySubPackageSettingsTest {
+  test_settingsFromTable() {
+    var subPackageSettings = FantasySubPackageSettings.fromName('vm_service');
+    expect(subPackageSettings.name, equals('vm_service'));
+    expect(subPackageSettings.repoSettings.name, equals('sdk'));
+    expect(subPackageSettings.subDir, equals('pkg/vm_service'));
+  }
+
+  test_settingsFromTableDefault() {
+    var subPackageSettings =
+        FantasySubPackageSettings.fromName('completely_unknown_package');
+    expect(subPackageSettings.name, equals('completely_unknown_package'));
+    expect(subPackageSettings.repoSettings.name,
+        equals('completely_unknown_package'));
+    expect(subPackageSettings.subDir, equals('.'));
+  }
+
+  test_settingsEqual() {
+    var repo1 = FantasyRepoSettings.fromName('some_repo_somewhere');
+    var repo2 = FantasyRepoSettings.fromName('another_repo_somewhere_else');
+    var test1 = FantasySubPackageSettings('foo', repo1, '.');
+    var test2 = FantasySubPackageSettings('foo', repo2, '.');
+    var test3 = FantasySubPackageSettings('foo', repo1, 'pkg/something');
+    var test4 = FantasySubPackageSettings('foobie', repo1, '.');
+    var test5 = FantasySubPackageSettings('foo', repo1, '.');
+
+    expect(test1, equals(test1));
+    expect(test1, isNot(equals(test2)));
+    expect(test1, isNot(equals(test3)));
+    expect(test1, isNot(equals(test4)));
+    expect(test1, equals(test5));
+  }
+}
diff --git a/pkg/nnbd_migration/test/fantasyland/test_all.dart b/pkg/nnbd_migration/test/fantasyland/test_all.dart
new file mode 100644
index 0000000..c4601ce
--- /dev/null
+++ b/pkg/nnbd_migration/test/fantasyland/test_all.dart
@@ -0,0 +1,15 @@
+// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import 'fantasy_repo_test.dart' as fantasy_repo_test;
+import 'fantasy_sub_package_test.dart' as fantasy_sub_package_test;
+
+main() {
+  defineReflectiveSuite(() {
+    fantasy_repo_test.main();
+    fantasy_sub_package_test.main();
+  });
+}
diff --git a/pkg/nnbd_migration/test/fix_aggregator_test.dart b/pkg/nnbd_migration/test/fix_aggregator_test.dart
index cea68fe..504375d 100644
--- a/pkg/nnbd_migration/test/fix_aggregator_test.dart
+++ b/pkg/nnbd_migration/test/fix_aggregator_test.dart
@@ -4,6 +4,7 @@
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/src/dart/element/type.dart';
 import 'package:nnbd_migration/src/decorated_type.dart';
 import 'package:nnbd_migration/src/edit_plan.dart';
 import 'package:nnbd_migration/src/fix_aggregator.dart';
@@ -23,8 +24,10 @@
 class FixAggregatorTest extends FixAggregatorTestBase {
   Future<void> test_addRequired() async {
     await analyze('f({int x}) => 0;');
-    var previewInfo = run(
-        {findNode.defaultParameter('int x'): const AddRequiredKeyword(null)});
+    var previewInfo = run({
+      findNode.defaultParameter('int x'): NodeChangeForDefaultFormalParameter()
+        ..addRequiredKeyword = true
+    });
     expect(previewInfo.applyTo(code), 'f({required int x}) => 0;');
   }
 
@@ -33,9 +36,9 @@
     var aRef = findNode.simple('a +');
     var bRef = findNode.simple('b;');
     var previewInfo = run({
-      aRef: const NullCheck(null),
-      bRef: const NullCheck(null),
-      findNode.binary('a + b'): const NullCheck(null)
+      aRef: NodeChangeForExpression()..addNullCheck = true,
+      bRef: NodeChangeForExpression()..addNullCheck = true,
+      findNode.binary('a + b'): NodeChangeForExpression()..addNullCheck = true
     });
     expect(previewInfo.applyTo(code), 'f(a, b) => (a! + b!)!;');
   }
@@ -47,8 +50,10 @@
 }
 ''');
     var previewInfo = run({
-      findNode.statement('if'): EliminateDeadIf(true),
-      findNode.simple('j.isEven'): const NullCheck(null)
+      findNode.statement('if'): NodeChangeForIfStatement()
+        ..conditionValue = true,
+      findNode.simple('j.isEven'): NodeChangeForExpression()
+        ..addNullCheck = true
     });
     expect(previewInfo.applyTo(code), '''
 f(int i, int/*?*/ j) {
@@ -66,8 +71,10 @@
 }
 ''');
     var previewInfo = run({
-      findNode.statement('if'): EliminateDeadIf(true),
-      findNode.simple('j.isEven'): const NullCheck(null)
+      findNode.statement('if'): NodeChangeForIfStatement()
+        ..conditionValue = true,
+      findNode.simple('j.isEven'): NodeChangeForExpression()
+        ..addNullCheck = true
     });
     expect(previewInfo.applyTo(code), '''
 f(int i, int/*?*/ j) {
@@ -82,7 +89,9 @@
   return [if (i == null) null];
 }
 ''');
-    var previewInfo = run({findNode.ifElement('=='): EliminateDeadIf(false)});
+    var previewInfo = run({
+      findNode.ifElement('=='): NodeChangeForIfElement()..conditionValue = false
+    });
     expect(previewInfo.applyTo(code), '''
 List<int> f(int i) {
   return [];
@@ -96,7 +105,9 @@
   return [if (i == null) null else i + 1];
 }
 ''');
-    var previewInfo = run({findNode.ifElement('=='): EliminateDeadIf(false)});
+    var previewInfo = run({
+      findNode.ifElement('=='): NodeChangeForIfElement()..conditionValue = false
+    });
     expect(previewInfo.applyTo(code), '''
 List<int> f(int i) {
   return [i + 1];
@@ -110,7 +121,9 @@
   return [if (i == null) null else i + 1];
 }
 ''');
-    var previewInfo = run({findNode.ifElement('=='): EliminateDeadIf(true)});
+    var previewInfo = run({
+      findNode.ifElement('=='): NodeChangeForIfElement()..conditionValue = true
+    });
     expect(previewInfo.applyTo(code), '''
 List<int> f(int i) {
   return [null];
@@ -124,8 +137,10 @@
   return i == null ? null : i + 1;
 }
 ''');
-    var previewInfo =
-        run({findNode.conditionalExpression('=='): EliminateDeadIf(false)});
+    var previewInfo = run({
+      findNode.conditionalExpression('=='): NodeChangeForConditionalExpression()
+        ..conditionValue = false
+    });
     expect(previewInfo.applyTo(code), '''
 int f(int i) {
   return i + 1;
@@ -139,8 +154,10 @@
   return i == null ? null : i + 1;
 }
 ''');
-    var previewInfo =
-        run({findNode.conditionalExpression('=='): EliminateDeadIf(true)});
+    var previewInfo = run({
+      findNode.conditionalExpression('=='): NodeChangeForConditionalExpression()
+        ..conditionValue = true
+    });
     expect(previewInfo.applyTo(code), '''
 int f(int i) {
   return null;
@@ -158,8 +175,10 @@
   }
 }
 ''');
-    var previewInfo = run({findNode.statement('if'): EliminateDeadIf(false)},
-        removeViaComments: true);
+    var previewInfo = run({
+      findNode.statement('if'): NodeChangeForIfStatement()
+        ..conditionValue = false
+    }, removeViaComments: true);
     expect(previewInfo.applyTo(code), '''
 int f(int i) {
   /* if (i == null) {
@@ -181,8 +200,10 @@
   }
 }
 ''');
-    var previewInfo = run({findNode.statement('if'): EliminateDeadIf(true)},
-        removeViaComments: true);
+    var previewInfo = run({
+      findNode.statement('if'): NodeChangeForIfStatement()
+        ..conditionValue = true
+    }, removeViaComments: true);
     expect(previewInfo.applyTo(code), '''
 int f(int i) {
   /* if (i == null) {
@@ -203,7 +224,10 @@
   }
 }
 ''');
-    var previewInfo = run({findNode.statement('if'): EliminateDeadIf(false)});
+    var previewInfo = run({
+      findNode.statement('if'): NodeChangeForIfStatement()
+        ..conditionValue = false
+    });
     expect(previewInfo.applyTo(code), '''
 void f(int i) {}
 ''');
@@ -218,7 +242,10 @@
   }
 }
 ''');
-    var previewInfo = run({findNode.statement('if'): EliminateDeadIf(true)});
+    var previewInfo = run({
+      findNode.statement('if'): NodeChangeForIfStatement()
+        ..conditionValue = true
+    });
     expect(previewInfo.applyTo(code), '''
 void f(int i) {}
 ''');
@@ -234,7 +261,10 @@
   }
 }
 ''');
-    var previewInfo = run({findNode.statement('if'): EliminateDeadIf(false)});
+    var previewInfo = run({
+      findNode.statement('if'): NodeChangeForIfStatement()
+        ..conditionValue = false
+    });
     expect(previewInfo.applyTo(code), '''
 int f(int i) {
   return i + 1;
@@ -252,7 +282,10 @@
   }
 }
 ''');
-    var previewInfo = run({findNode.statement('if'): EliminateDeadIf(true)});
+    var previewInfo = run({
+      findNode.statement('if'): NodeChangeForIfStatement()
+        ..conditionValue = true
+    });
     expect(previewInfo.applyTo(code), '''
 int f(int i) {
   return i + 1;
@@ -274,7 +307,10 @@
 ''');
     // In this case we have to keep the block so that the scope of `var i`
     // doesn't widen.
-    var previewInfo = run({findNode.statement('if'): EliminateDeadIf(true)});
+    var previewInfo = run({
+      findNode.statement('if'): NodeChangeForIfStatement()
+        ..conditionValue = true
+    });
     expect(previewInfo.applyTo(code), '''
 void f(int i, String callback()) {
   {
@@ -291,7 +327,11 @@
     // leave them.
     await analyze('f(a, c) => a..b = (throw c..d);');
     var cd = findNode.cascade('c..d');
-    var previewInfo = run({cd: const IntroduceAs('int', null)});
+    var previewInfo = run({
+      cd: NodeChangeForExpression()
+        ..introduceAsType = 'int'
+        ..introduceAsInfo = _MockInfo()
+    });
     expect(
         previewInfo.applyTo(code), 'f(a, c) => a..b = (throw (c..d) as int);');
   }
@@ -299,14 +339,22 @@
   Future<void> test_introduceAs_no_parens() async {
     await analyze('f(a, b) => a | b;');
     var expr = findNode.binary('a | b');
-    var previewInfo = run({expr: const IntroduceAs('int', null)});
+    var previewInfo = run({
+      expr: NodeChangeForExpression()
+        ..introduceAsType = 'int'
+        ..introduceAsInfo = _MockInfo()
+    });
     expect(previewInfo.applyTo(code), 'f(a, b) => a | b as int;');
   }
 
   Future<void> test_introduceAs_parens() async {
     await analyze('f(a, b) => a < b;');
     var expr = findNode.binary('a < b');
-    var previewInfo = run({expr: const IntroduceAs('bool', null)});
+    var previewInfo = run({
+      expr: NodeChangeForExpression()
+        ..introduceAsType = 'bool'
+        ..introduceAsInfo = _MockInfo()
+    });
     expect(previewInfo.applyTo(code), 'f(a, b) => (a < b) as bool;');
   }
 
@@ -319,22 +367,28 @@
   Future<void> test_makeNullable() async {
     await analyze('f(int x) {}');
     var typeName = findNode.typeName('int');
-    var previewInfo =
-        run({typeName: MakeNullable(MockDecoratedType(MockDartType()))});
+    var previewInfo = run({
+      typeName: NodeChangeForTypeAnnotation()
+        ..makeNullable = true
+        ..makeNullableType = MockDecoratedType(
+            MockDartType(toStringValueWithoutNullability: 'int'))
+    });
     expect(previewInfo.applyTo(code), 'f(int? x) {}');
   }
 
   Future<void> test_nullCheck_no_parens() async {
     await analyze('f(a) => a++;');
     var expr = findNode.postfix('a++');
-    var previewInfo = run({expr: const NullCheck(null)});
+    var previewInfo =
+        run({expr: NodeChangeForExpression()..addNullCheck = true});
     expect(previewInfo.applyTo(code), 'f(a) => a++!;');
   }
 
   Future<void> test_nullCheck_parens() async {
     await analyze('f(a) => -a;');
     var expr = findNode.prefix('-a');
-    var previewInfo = run({expr: const NullCheck(null)});
+    var previewInfo =
+        run({expr: NodeChangeForExpression()..addNullCheck = true});
     expect(previewInfo.applyTo(code), 'f(a) => (-a)!;');
   }
 
@@ -343,7 +397,7 @@
     await analyze('f(a) => ((a..b) as dynamic)..c;');
     var cascade = findNode.cascade('a..b');
     var cast = cascade.parent.parent;
-    var previewInfo = run({cast: const RemoveAs()});
+    var previewInfo = run({cast: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a) => a..b..c;');
   }
 
@@ -354,7 +408,7 @@
     await analyze('f(a, b, c) => ((a ? b : c) as dynamic)..d;');
     var conditional = findNode.conditionalExpression('a ? b : c');
     var cast = conditional.parent.parent;
-    var previewInfo = run({cast: const RemoveAs()});
+    var previewInfo = run({cast: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a, b, c) => a ? b : c..d;');
   }
 
@@ -363,7 +417,7 @@
     await analyze('f(a, b) => ((a = b) as dynamic)..c;');
     var assignment = findNode.assignment('a = b');
     var cast = assignment.parent.parent;
-    var previewInfo = run({cast: const RemoveAs()});
+    var previewInfo = run({cast: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a, b) => (a = b)..c;');
   }
 
@@ -371,7 +425,7 @@
     await analyze('f(a) => ((throw a) as dynamic)..b;');
     var throw_ = findNode.throw_('throw a');
     var cast = throw_.parent.parent;
-    var previewInfo = run({cast: const RemoveAs()});
+    var previewInfo = run({cast: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a) => (throw a)..b;');
   }
 
@@ -379,14 +433,16 @@
       test_removeAs_lower_precedence_do_not_remove_inner_parens() async {
     await analyze('f(a, b, c) => (a == b) as Null == c;');
     var expr = findNode.binary('a == b');
-    var previewInfo = run({expr.parent.parent: const RemoveAs()});
+    var previewInfo =
+        run({expr.parent.parent: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a, b, c) => (a == b) == c;');
   }
 
   Future<void> test_removeAs_lower_precedence_remove_inner_parens() async {
     await analyze('f(a, b) => (a == b) as Null;');
     var expr = findNode.binary('a == b');
-    var previewInfo = run({expr.parent.parent: const RemoveAs()});
+    var previewInfo =
+        run({expr.parent.parent: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a, b) => a == b;');
   }
 
@@ -404,7 +460,7 @@
     await analyze('f(a, c) => a..b = throw (c..d) as int;');
     var cd = findNode.cascade('c..d');
     var cast = cd.parent.parent;
-    var previewInfo = run({cast: const RemoveAs()});
+    var previewInfo = run({cast: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a, c) => a..b = (throw c..d);');
   }
 
@@ -413,7 +469,7 @@
     await analyze('f(a, b, c) => a ? b : (c..d) as int;');
     var cd = findNode.cascade('c..d');
     var cast = cd.parent.parent;
-    var previewInfo = run({cast: const RemoveAs()});
+    var previewInfo = run({cast: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a, b, c) => a ? b : (c..d);');
   }
 
@@ -422,36 +478,41 @@
     await analyze('f(a, b, d) => a ? (b..c) as int : d;');
     var bc = findNode.cascade('b..c');
     var cast = bc.parent.parent;
-    var previewInfo = run({cast: const RemoveAs()});
+    var previewInfo = run({cast: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a, b, d) => a ? (b..c) : d;');
   }
 
   Future<void> test_removeAs_raise_precedence_do_not_remove_parens() async {
     await analyze('f(a, b, c) => a | (b | c as int);');
     var expr = findNode.binary('b | c');
-    var previewInfo = run({expr.parent: const RemoveAs()});
+    var previewInfo =
+        run({expr.parent: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a, b, c) => a | (b | c);');
   }
 
   Future<void> test_removeAs_raise_precedence_no_parens_to_remove() async {
     await analyze('f(a, b, c) => a = b | c as int;');
     var expr = findNode.binary('b | c');
-    var previewInfo = run({expr.parent: const RemoveAs()});
+    var previewInfo =
+        run({expr.parent: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a, b, c) => a = b | c;');
   }
 
   Future<void> test_removeAs_raise_precedence_remove_parens() async {
     await analyze('f(a, b, c) => a < (b | c as int);');
     var expr = findNode.binary('b | c');
-    var previewInfo = run({expr.parent: const RemoveAs()});
+    var previewInfo =
+        run({expr.parent: NodeChangeForAsExpression()..removeAs = true});
     expect(previewInfo.applyTo(code), 'f(a, b, c) => a < b | c;');
   }
 
   Future<void> test_removeNullAwarenessFromMethodInvocation() async {
     await analyze('f(x) => x?.m();');
     var methodInvocation = findNode.methodInvocation('?.');
-    var previewInfo = run(
-        {methodInvocation: const RemoveNullAwarenessFromMethodInvocation()});
+    var previewInfo = run({
+      methodInvocation: NodeChangeForMethodInvocation()
+        ..removeNullAwareness = true
+    });
     expect(previewInfo.applyTo(code), 'f(x) => x.m();');
   }
 
@@ -461,8 +522,9 @@
     var methodInvocation = findNode.methodInvocation('?.');
     var argument = findNode.simple('x);');
     var previewInfo = run({
-      methodInvocation: const RemoveNullAwarenessFromMethodInvocation(),
-      argument: const NullCheck(null)
+      methodInvocation: NodeChangeForMethodInvocation()
+        ..removeNullAwareness = true,
+      argument: NodeChangeForExpression()..addNullCheck = true
     });
     expect(previewInfo.applyTo(code), 'f(x) => x.m(x!);');
   }
@@ -473,8 +535,9 @@
     var methodInvocation = findNode.methodInvocation('?.');
     var cast = findNode.as_('as');
     var previewInfo = run({
-      methodInvocation: const RemoveNullAwarenessFromMethodInvocation(),
-      cast: const RemoveAs()
+      methodInvocation: NodeChangeForMethodInvocation()
+        ..removeNullAwareness = true,
+      cast: NodeChangeForAsExpression()..removeAs = true
     });
     expect(previewInfo.applyTo(code), 'f(x) => x.m();');
   }
@@ -485,8 +548,12 @@
     var methodInvocation = findNode.methodInvocation('?.');
     var typeAnnotation = findNode.typeAnnotation('int');
     var previewInfo = run({
-      methodInvocation: const RemoveNullAwarenessFromMethodInvocation(),
-      typeAnnotation: const MakeNullable(MockDecoratedType(MockDartType()))
+      methodInvocation: NodeChangeForMethodInvocation()
+        ..removeNullAwareness = true,
+      typeAnnotation: NodeChangeForTypeAnnotation()
+        ..makeNullable = true
+        ..makeNullableType = MockDecoratedType(
+            MockDartType(toStringValueWithoutNullability: 'int'))
     });
     expect(previewInfo.applyTo(code), 'f(x) => x.m<int?>();');
   }
@@ -494,8 +561,9 @@
   Future<void> test_removeNullAwarenessFromPropertyAccess() async {
     await analyze('f(x) => x?.y;');
     var propertyAccess = findNode.propertyAccess('?.');
-    var previewInfo =
-        run({propertyAccess: const RemoveNullAwarenessFromPropertyAccess()});
+    var previewInfo = run({
+      propertyAccess: NodeChangeForPropertyAccess()..removeNullAwareness = true
+    });
     expect(previewInfo.applyTo(code), 'f(x) => x.y;');
   }
 
@@ -504,8 +572,8 @@
     var propertyAccess = findNode.propertyAccess('?.');
     var cast = findNode.as_('as');
     var previewInfo = run({
-      propertyAccess: const RemoveNullAwarenessFromPropertyAccess(),
-      cast: const RemoveAs()
+      propertyAccess: NodeChangeForPropertyAccess()..removeNullAwareness = true,
+      cast: NodeChangeForAsExpression()..removeAs = true
     });
     expect(previewInfo.applyTo(code), 'f(x) => x.y;');
   }
@@ -517,8 +585,9 @@
 f({@meta.required int x}) {}
 ''');
     var annotation = findNode.annotation('required');
-    var previewInfo =
-        run({annotation: const RequiredAnnotationToRequiredKeyword(null)});
+    var previewInfo = run({
+      annotation: NodeChangeForAnnotation()..changeToRequiredKeyword = true
+    });
     expect(previewInfo.applyTo(code), '''
 import 'package:meta/meta.dart' as meta;
 f({required int x}) {}
@@ -534,8 +603,9 @@
 f({@foo int x}) {}
 ''');
     var annotation = findNode.annotation('@foo');
-    var previewInfo =
-        run({annotation: const RequiredAnnotationToRequiredKeyword(null)});
+    var previewInfo = run({
+      annotation: NodeChangeForAnnotation()..changeToRequiredKeyword = true
+    });
     expect(previewInfo.applyTo(code), '''
 import 'package:meta/meta.dart';
 const foo = required;
@@ -550,14 +620,59 @@
 f({@required int x}) {}
 ''');
     var annotation = findNode.annotation('required');
-    var previewInfo =
-        run({annotation: const RequiredAnnotationToRequiredKeyword(null)});
+    var previewInfo = run({
+      annotation: NodeChangeForAnnotation()..changeToRequiredKeyword = true
+    });
     expect(previewInfo.applyTo(code), '''
 import 'package:meta/meta.dart';
 f({required int x}) {}
 ''');
     expect(previewInfo.values.single.single.isDeletion, true);
   }
+
+  Future<void> test_variableDeclarationList_addExplicitType_insert() async {
+    await analyze('final x = 0;');
+    var previewInfo = run({
+      findNode.variableDeclarationList('final'):
+          NodeChangeForVariableDeclarationList()
+            ..addExplicitType =
+                MockDartType(toStringValueWithNullability: 'int')
+    });
+    expect(previewInfo.applyTo(code), 'final int x = 0;');
+  }
+
+  Future<void> test_variableDeclarationList_addExplicitType_no() async {
+    await analyze('var x = 0;');
+    var previewInfo = run({
+      findNode.variableDeclarationList('var'):
+          NodeChangeForVariableDeclarationList()
+    });
+    expect(previewInfo, isNull);
+  }
+
+  Future<void> test_variableDeclarationList_addExplicitType_otherPlans() async {
+    await analyze('var x = 0;');
+    var previewInfo = run({
+      findNode.variableDeclarationList('var'):
+          NodeChangeForVariableDeclarationList()
+            ..addExplicitType =
+                MockDartType(toStringValueWithNullability: 'int'),
+      findNode.integerLiteral('0'): NodeChangeForExpression()
+        ..addNullCheck = true
+    });
+    expect(previewInfo.applyTo(code), 'int x = 0!;');
+  }
+
+  Future<void> test_variableDeclarationList_addExplicitType_replaceVar() async {
+    await analyze('var x = 0;');
+    var previewInfo = run({
+      findNode.variableDeclarationList('var'):
+          NodeChangeForVariableDeclarationList()
+            ..addExplicitType =
+                MockDartType(toStringValueWithNullability: 'int')
+    });
+    expect(previewInfo.applyTo(code), 'int x = 0;');
+  }
 }
 
 class FixAggregatorTestBase extends AbstractSingleUnitTest {
@@ -575,13 +690,28 @@
   }
 }
 
-class MockDartType implements DartType {
-  const MockDartType();
+class MockDartType implements TypeImpl {
+  final String toStringValueWithNullability;
+
+  final String toStringValueWithoutNullability;
+
+  const MockDartType(
+      {this.toStringValueWithNullability,
+      this.toStringValueWithoutNullability});
 
   @override
   noSuchMethod(Invocation invocation) {
     return super.noSuchMethod(invocation);
   }
+
+  @override
+  String toString({bool withNullability = false}) {
+    var result = withNullability
+        ? toStringValueWithNullability
+        : toStringValueWithoutNullability;
+    expect(result, isNotNull);
+    return result;
+  }
 }
 
 class MockDecoratedType implements DecoratedType {
@@ -598,3 +728,7 @@
     return super.noSuchMethod(invocation);
   }
 }
+
+class _MockInfo implements AtomicEditInfo {
+  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}
diff --git a/pkg/nnbd_migration/test/fix_builder_test.dart b/pkg/nnbd_migration/test/fix_builder_test.dart
index f33574c..19f863a 100644
--- a/pkg/nnbd_migration/test/fix_builder_test.dart
+++ b/pkg/nnbd_migration/test/fix_builder_test.dart
@@ -39,24 +39,25 @@
 @reflectiveTest
 class FixBuilderTest extends EdgeBuilderTestBase {
   static final isAddRequiredKeyword =
-      havingInnerMatcher(TypeMatcher<AddRequiredKeyword>(), isNoChange);
+      TypeMatcher<NodeChangeForDefaultFormalParameter>()
+          .having((c) => c.addRequiredKeyword, 'addRequiredKeyword', true);
 
-  static final isMakeNullable =
-      havingInnerMatcher(TypeMatcher<MakeNullable>(), isNoChange);
+  static final isMakeNullable = TypeMatcher<NodeChangeForTypeAnnotation>()
+      .having((c) => c.makeNullable, 'makeNullable', isNotNull);
 
-  static const isNoChange = TypeMatcher<NoChange>();
+  static final isNullCheck = TypeMatcher<NodeChangeForExpression>()
+      .having((c) => c.addNullCheck, 'addNullCheck', true);
 
-  static final isNullCheck =
-      havingInnerMatcher(TypeMatcher<NullCheck>(), isNoChange);
+  static final isRemoveNullAwareness =
+      TypeMatcher<NodeChangeForPropertyAccess>()
+          .having((c) => c.removeNullAwareness, 'removeNullAwareness', true);
 
-  static const isRemoveNullAwarenessFromPropertyAccess =
-      TypeMatcher<RemoveNullAwarenessFromPropertyAccess>();
+  static final isRemoveAs = TypeMatcher<NodeChangeForAsExpression>()
+      .having((c) => c.removeAs, 'removeAs', true);
 
-  static final isRemoveAs =
-      havingInnerMatcher(TypeMatcher<RemoveAs>(), isNoChange);
-
-  static final isRequiredAnnotationToRequiredKeyword = havingInnerMatcher(
-      TypeMatcher<RequiredAnnotationToRequiredKeyword>(), isNoChange);
+  static final isRequiredAnnotationToRequiredKeyword =
+      TypeMatcher<NodeChangeForAnnotation>().having(
+          (c) => c.changeToRequiredKeyword, 'changeToRequiredKeyword', true);
 
   DartType get dynamicType => postMigrationTypeProvider.dynamicType;
 
@@ -847,7 +848,7 @@
 
   Future<void> test_binaryExpression_bar_bar_nullChecked() async {
     await analyze('''
-_f(Object/*?*/ x, Object/*?*/ y) {
+_f(bool/*?*/ x, bool/*?*/ y) {
   return x || y;
 }
 ''');
@@ -2277,7 +2278,7 @@
     await analyze('_f(int/*!*/ i) => i?.isEven;');
     var propertyAccess = findNode.propertyAccess('?.');
     visitSubexpression(propertyAccess, 'bool',
-        changes: {propertyAccess: isRemoveNullAwarenessFromPropertyAccess});
+        changes: {propertyAccess: isRemoveNullAwareness});
   }
 
   Future<void>
@@ -2290,8 +2291,9 @@
 ''');
     var propertyAccess = findNode.propertyAccess('?.');
     visitSubexpression(propertyAccess, 'int', changes: {
-      propertyAccess: havingInnerMatcher(const TypeMatcher<NullCheck>(),
-          isRemoveNullAwarenessFromPropertyAccess)
+      propertyAccess: TypeMatcher<NodeChangeForPropertyAccess>()
+          .having((c) => c.addNullCheck, 'addNullCheck', true)
+          .having((c) => c.removeNullAwareness, 'removeNullAwareness', true)
     });
   }
 
@@ -2755,12 +2757,7 @@
         null;
   }
 
-  static TypeMatcher<NestableChange> havingInnerMatcher(
-          TypeMatcher<NestableChange> typeMatcher, Matcher innerMatcher) =>
-      typeMatcher.having(
-          (nullCheck) => nullCheck.inner, 'inner change', innerMatcher);
-
   static Matcher isEliminateDeadIf(bool knownValue) =>
-      TypeMatcher<EliminateDeadIf>()
+      TypeMatcher<NodeChangeForConditional>()
           .having((c) => c.conditionValue, 'conditionValue', knownValue);
 }
diff --git a/pkg/nnbd_migration/test/instrumentation_test.dart b/pkg/nnbd_migration/test/instrumentation_test.dart
index a99d220..82940fe 100644
--- a/pkg/nnbd_migration/test/instrumentation_test.dart
+++ b/pkg/nnbd_migration/test/instrumentation_test.dart
@@ -8,7 +8,6 @@
 import 'package:analyzer/src/test_utilities/find_node.dart';
 import 'package:nnbd_migration/instrumentation.dart';
 import 'package:nnbd_migration/nnbd_migration.dart';
-import 'package:nnbd_migration/nullability_state.dart';
 import 'package:nnbd_migration/src/edit_plan.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
@@ -95,12 +94,6 @@
   @override
   void prepareForUpdate() {
     test.changes = null;
-    test.propagationSteps.clear();
-  }
-
-  @override
-  void propagationStep(PropagationInfo info) {
-    test.propagationSteps.add(info);
   }
 }
 
@@ -129,8 +122,6 @@
 
   NullabilityNodeInfo never;
 
-  final List<PropagationInfo> propagationSteps = [];
-
   final Map<EdgeInfo, EdgeOriginInfo> edgeOrigin = {};
 
   FindNode findNode;
@@ -632,9 +623,7 @@
         .key;
     // Both assertEdge and unconditionalUsageEdge are upstream triggered because
     // either of them would have been sufficient to cause i to be marked as
-    // non-nullable, even though only one of them was actually reported to have
-    // done so via propagationStep.
-    expect(propagationSteps.where((s) => s.node == iNode), hasLength(1));
+    // non-nullable.
     expect(assertEdge.isUpstreamTriggered, true);
     expect(unconditionalUsageEdge.isUpstreamTriggered, true);
     // conditionalUsageEdge is not upstream triggered because it is a soft edge,
@@ -1205,32 +1194,6 @@
         hasLength(1));
   }
 
-  Future<void> test_propagationStep_downstream() async {
-    await analyze('''
-int x = null;
-''');
-    var xNode = explicitTypeNullability[findNode.typeAnnotation('int')];
-    var step = propagationSteps.where((s) => s.node == xNode).single;
-    expect(step.newState, NullabilityState.ordinaryNullable);
-    expect(step.reason, StateChangeReason.downstream);
-    expect(_isPointedToByAlways(step.edge.sourceNode), true);
-    expect(step.edge.destinationNode, xNode);
-  }
-
-  Future<void> test_propagationStep_upstream() async {
-    await analyze('''
-void f(int x) {
-  assert(x != null);
-}
-''');
-    var xNode = explicitTypeNullability[findNode.typeAnnotation('int')];
-    var step = propagationSteps.where((s) => s.node == xNode).single;
-    expect(step.newState, NullabilityState.nonNullable);
-    expect(step.reason, StateChangeReason.upstream);
-    expect(step.edge.sourceNode, xNode);
-    expect(step.edge.destinationNode, never);
-  }
-
   Future<void> test_substitutionNode() async {
     await analyze('''
 class C<T> {
diff --git a/pkg/nnbd_migration/test/migration_visitor_test_base.dart b/pkg/nnbd_migration/test/migration_visitor_test_base.dart
index e18d412..5b9f840 100644
--- a/pkg/nnbd_migration/test/migration_visitor_test_base.dart
+++ b/pkg/nnbd_migration/test/migration_visitor_test_base.dart
@@ -108,6 +108,9 @@
 
   NullabilityNode newNode() => NullabilityNode.forTypeAnnotation(_offset++);
 
+  DecoratedType num_({NullabilityNode node}) =>
+      DecoratedType(typeProvider.numType, node ?? newNode());
+
   DecoratedType object({NullabilityNode node}) =>
       DecoratedType(typeProvider.objectType, node ?? newNode());
 
@@ -198,7 +201,7 @@
   /// aren't already.  In practice this means that the caller can pass in either
   //  /// a [NodeMatcher] or a [NullabilityNode].
   NullabilityEdge assertEdge(Object source, Object destination,
-      {@required bool hard, List<NullabilityNode> guards = const []}) {
+      {@required bool hard, bool checkable = true, Object guards = isEmpty}) {
     var edges = getEdges(source, destination);
     if (edges.length == 0) {
       fail('Expected edge $source -> $destination, found none');
@@ -207,7 +210,8 @@
     } else {
       var edge = edges[0];
       expect(edge.isHard, hard);
-      expect(edge.guards, unorderedEquals(guards));
+      expect(edge.isCheckable, checkable);
+      expect(edge.guards, guards);
       return edge;
     }
   }
@@ -394,6 +398,12 @@
         testSource, findNode.typeAnnotation(text));
   }
 
+  /// Gets the [ConditionalDiscard] information associated with the collection
+  /// element whose text is [text].
+  ConditionalDiscard elementDiscard(String text) {
+    return variables.conditionalDiscard(findNode.collectionElement(text));
+  }
+
   NullabilityNode possiblyOptionalParameter(String text) {
     return variables.possiblyOptionalParameter(findNode.defaultParameter(text));
   }
@@ -403,12 +413,6 @@
   ConditionalDiscard statementDiscard(String text) {
     return variables.conditionalDiscard(findNode.statement(text));
   }
-
-  /// Gets the [ConditionalDiscard] information associated with the collection
-  /// element whose text is [text].
-  ConditionalDiscard elementDiscard(String text) {
-    return variables.conditionalDiscard(findNode.collectionElement(text));
-  }
 }
 
 /// Abstract base class representing a thing that can be matched against
diff --git a/pkg/nnbd_migration/test/node_builder_test.dart b/pkg/nnbd_migration/test/node_builder_test.dart
index ab73cca..d993021 100644
--- a/pkg/nnbd_migration/test/node_builder_test.dart
+++ b/pkg/nnbd_migration/test/node_builder_test.dart
@@ -39,7 +39,7 @@
     expect(exceptionType.node, TypeMatcher<NullabilityNodeMutable>());
     var stackTraceType =
         variables.decoratedElementType(findNode.simple('st').staticElement);
-    assertEdge(stackTraceType.node, never, hard: true);
+    assertEdge(stackTraceType.node, never, hard: true, checkable: false);
   }
 
   Future<void> test_catch_clause_with_stacktrace_without_on() async {
@@ -53,7 +53,7 @@
     expect(exceptionType.node.isImmutable, false);
     var stackTraceType =
         variables.decoratedElementType(findNode.simple('st').staticElement);
-    assertEdge(stackTraceType.node, never, hard: true);
+    assertEdge(stackTraceType.node, never, hard: true, checkable: false);
   }
 
   Future<void> test_catch_clause_without_catch() async {
@@ -313,7 +313,7 @@
     var types = decoratedDirectSupertypes('C');
     var decorated = types[typeProvider.objectType.element];
     expect(decorated.type.toString(), 'Object');
-    assertEdge(decorated.node, never, hard: true);
+    assertEdge(decorated.node, never, hard: true, checkable: false);
     expect(decorated.typeArguments, isEmpty);
   }
 
@@ -419,7 +419,7 @@
     var types = decoratedDirectSupertypes('C');
     var decorated = types[typeProvider.objectType.element];
     expect(decorated.type.toString(), 'Object');
-    assertEdge(decorated.node, never, hard: true);
+    assertEdge(decorated.node, never, hard: true, checkable: false);
     expect(decorated.typeArguments, isEmpty);
   }
 
@@ -1513,7 +1513,8 @@
     await analyze('''
 void f(int/*!*/ i) {}
 ''');
-    assertEdge(decoratedTypeAnnotation('int').node, never, hard: true);
+    assertEdge(decoratedTypeAnnotation('int').node, never,
+        hard: true, checkable: false);
   }
 
   Future<void> test_type_comment_question() async {
diff --git a/pkg/nnbd_migration/test/nullability_node_test.dart b/pkg/nnbd_migration/test/nullability_node_test.dart
index 39e24bb..7ac845b 100644
--- a/pkg/nnbd_migration/test/nullability_node_test.dart
+++ b/pkg/nnbd_migration/test/nullability_node_test.dart
@@ -43,9 +43,9 @@
       NullabilityNode.forTypeAnnotation(offset);
 
   void propagate() {
-    graph.propagate();
-    unsatisfiedEdges = graph.unsatisfiedEdges.toList();
-    unsatisfiedSubstitutions = graph.unsatisfiedSubstitutions.toList();
+    var propagationResult = graph.propagate();
+    unsatisfiedEdges = propagationResult.unsatisfiedEdges;
+    unsatisfiedSubstitutions = propagationResult.unsatisfiedSubstitutions;
   }
 
   NullabilityNode subst(NullabilityNode inner, NullabilityNode outer) {
diff --git a/pkg/nnbd_migration/test/test_all.dart b/pkg/nnbd_migration/test/test_all.dart
index 6b604595..cde6e0f 100644
--- a/pkg/nnbd_migration/test/test_all.dart
+++ b/pkg/nnbd_migration/test/test_all.dart
@@ -15,6 +15,7 @@
 import 'edit_plan_test.dart' as edit_plan_test;
 import 'edit_planner_pass_through_merging_test.dart'
     as edit_planner_pass_through_merging_test;
+import 'fantasyland/test_all.dart' as fantasyland;
 import 'fix_aggregator_test.dart' as fix_aggregator_test;
 import 'fix_builder_test.dart' as fix_builder_test;
 import 'instrumentation_test.dart' as instrumentation_test;
@@ -35,6 +36,7 @@
     edge_builder_test.main();
     edit_plan_test.main();
     edit_planner_pass_through_merging_test.main();
+    fantasyland.main();
     fix_aggregator_test.main();
     fix_builder_test.main();
     instrumentation_test.main();
diff --git a/pkg/nnbd_migration/test/utilities/subprocess_launcher_test.dart b/pkg/nnbd_migration/test/utilities/subprocess_launcher_test.dart
index aca5806..b1980da 100644
--- a/pkg/nnbd_migration/test/utilities/subprocess_launcher_test.dart
+++ b/pkg/nnbd_migration/test/utilities/subprocess_launcher_test.dart
@@ -31,11 +31,21 @@
     await tempDir.delete(recursive: true);
   }
 
+  Future<void> test_subprocessWorksViaParallelSubprocessLimit() async {
+    SubprocessLauncher launcher =
+        SubprocessLauncher('test_subprocessWorksViaParallelSubprocessLimit');
+
+    await launcher.runStreamed(Platform.resolvedExecutable, ['--version'],
+        perLine: outputCallback);
+    expect(output, anyElement(contains('Dart')));
+  }
+
   Future<void> test_subprocessRunsValidExecutable() async {
     SubprocessLauncher launcher =
         SubprocessLauncher('test_subprocessRunsValidExecutable');
 
-    await launcher.runStreamed(Platform.resolvedExecutable, ['--version'],
+    await launcher.runStreamedImmediate(
+        Platform.resolvedExecutable, ['--version'],
         perLine: outputCallback);
     expect(output, anyElement(contains('Dart')));
   }
@@ -52,7 +62,7 @@
         print('args: $args');
       }''');
 
-    await launcher.runStreamed(
+    await launcher.runStreamedImmediate(
         Platform.resolvedExecutable, [testScript.path, 'testArgument'],
         perLine: outputCallback);
     expect(output, anyElement(contains('args: [testArgument]')));
@@ -70,7 +80,8 @@
         print('environment: ${Platform.environment}');
       }''');
 
-    await launcher.runStreamed(Platform.resolvedExecutable, [testScript.path],
+    await launcher.runStreamedImmediate(
+        Platform.resolvedExecutable, [testScript.path],
         environment: {'__SUBPROCESS_PASSES_ENVIRONMENT_TEST': 'yes'},
         perLine: outputCallback);
     expect(
@@ -91,7 +102,8 @@
         print('working directory: ${Directory.current.path}');
       }''');
 
-    await launcher.runStreamed(Platform.resolvedExecutable, [testScript.path],
+    await launcher.runStreamedImmediate(
+        Platform.resolvedExecutable, [testScript.path],
         workingDirectory: tempDir.path, perLine: outputCallback);
     expect(
         output,
@@ -111,7 +123,7 @@
         exit(1);
       }''');
     await expectLater(
-        () async => await launcher.runStreamed(
+        () async => await launcher.runStreamedImmediate(
             Platform.resolvedExecutable, [testScript.path],
             perLine: outputCallback),
         throwsA(TypeMatcher<ProcessException>()));
diff --git a/pkg/nnbd_migration/tool/trial_migration.dart b/pkg/nnbd_migration/tool/trial_migration.dart
index f607a7b..878c024 100644
--- a/pkg/nnbd_migration/tool/trial_migration.dart
+++ b/pkg/nnbd_migration/tool/trial_migration.dart
@@ -17,7 +17,6 @@
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:args/args.dart';
 import 'package:nnbd_migration/nnbd_migration.dart';
-import 'package:nnbd_migration/src/utilities/multi_future_tracker.dart';
 import 'package:path/path.dart' as path;
 
 import 'src/package.dart';
@@ -40,17 +39,10 @@
       ManualPackage(package),
   ];
 
-  // Limit the number of simultaneous git/pub commands.
-  MultiFutureTracker futureTracker =
-      MultiFutureTracker(Platform.numberOfProcessors);
-
-  for (String package in parsedArgs['git_packages'] as Iterable<String>) {
-    await futureTracker.addFutureFromClosure(() async => packages.add(
-        await GitPackage.gitPackageFactory(
-            package, playground, parsedArgs['update'] as bool)));
-  }
-
-  await futureTracker.wait();
+  var packageNames = parsedArgs['git_packages'] as Iterable<String>;
+  await Future.wait(packageNames.map((n) async => packages.add(
+      await GitPackage.gitPackageFactory(
+          n, playground, parsedArgs['update'] as bool))));
 
   String categoryOfInterest =
       parsedArgs.rest.isEmpty ? null : parsedArgs.rest.single;
diff --git a/pkg/pkg.status b/pkg/pkg.status
index 32c34d5..53d5295 100644
--- a/pkg/pkg.status
+++ b/pkg/pkg.status
@@ -9,22 +9,22 @@
 */*/*/packages/*/*: Skip
 */*/packages/*/*: Skip
 */packages/*/*: Skip
-analyzer/test/generated/compile_time_error_code_driver_test: Slow
-analyzer/test/generated/compile_time_error_code_kernel_test: Slow
-analyzer/test/generated/compile_time_error_code_test: Slow
-analyzer/test/generated/hint_code_kernel_test: Slow
-analyzer/test/generated/non_error_resolver_driver_test: Slow
-analyzer/test/generated/non_error_resolver_kernel_test: Slow
-analyzer/test/generated/non_hint_code_kernel_test: Slow
-analyzer/test/generated/static_type_warning_code_kernel_test: Slow
-analyzer/test/generated/static_warning_code_driver_test: Slow
-analyzer/test/generated/static_warning_code_kernel_test: Slow
-analyzer/test/generated/strong_mode_kernel_test: Slow
-analyzer/test/src/dart/analysis/driver_kernel_test: Slow
-analyzer/test/src/summary/resynthesize_kernel_test: Slow
-analyzer/test/src/task/strong/checker_test: Slow
-analyzer_plugin/test/plugin/folding_mixin_test: Slow
-dev_compiler/test/modular/*: Slow
+analyzer/test/generated/compile_time_error_code_driver_test: Slow, Pass
+analyzer/test/generated/compile_time_error_code_kernel_test: Slow, Pass
+analyzer/test/generated/compile_time_error_code_test: Slow, Pass
+analyzer/test/generated/hint_code_kernel_test: Slow, Pass
+analyzer/test/generated/non_error_resolver_driver_test: Slow, Pass
+analyzer/test/generated/non_error_resolver_kernel_test: Slow, Pass
+analyzer/test/generated/non_hint_code_kernel_test: Slow, Pass
+analyzer/test/generated/static_type_warning_code_kernel_test: Slow, Pass
+analyzer/test/generated/static_warning_code_driver_test: Slow, Pass
+analyzer/test/generated/static_warning_code_kernel_test: Slow, Pass
+analyzer/test/generated/strong_mode_kernel_test: Slow, Pass
+analyzer/test/src/dart/analysis/driver_kernel_test: Slow, Pass
+analyzer/test/src/summary/resynthesize_kernel_test: Slow, Pass
+analyzer/test/src/task/strong/checker_test: Slow, Pass
+analyzer_plugin/test/plugin/folding_mixin_test: Slow, Pass
+dev_compiler/test/modular/*: Slow, Pass
 dev_compiler/test/options/*: Skip # test needs fixes
 dev_compiler/test/sourcemap/*: SkipByDesign # Skip sourcemap tests
 dev_compiler/test/sourcemap/testfiles/*: SkipByDesign # Skip dev_compiler codegen tests
@@ -50,10 +50,10 @@
 front_end/test/whole_program_test: Slow, Pass
 front_end/testcases/*: Skip # These are not tests but input for tests.
 front_end/tool/incremental_perf_test: Slow, Pass
-kernel/test/closures_test: Slow
+kernel/test/closures_test: Slow, Pass
 kernel/testcases/*: Skip # These are not tests but input for tests.
-vm/test/frontend_server_test: Slow
-vm/test/transformations/type_flow/transformer_test: Slow
+vm/test/frontend_server_test: Slow, Pass
+vm/test/transformations/type_flow/transformer_test: Slow, Pass
 vm/testcases/*: SkipByDesign # These are not tests but input for tests.
 
 [ $compiler == dart2analyzer ]
@@ -61,7 +61,7 @@
 testing/test/dart_sdk_negative_test: SkipByDesign
 
 [ $compiler != dart2analyzer ]
-analyzer/test/src/summary/summarize_fasta_test: Slow
+analyzer/test/src/summary/summarize_fasta_test: Slow, Pass
 
 [ $compiler == dart2js ]
 _fe_analyzer_shared/test/*: SkipByDesign # Only meant to run on vm
@@ -73,13 +73,13 @@
 analyzer_plugin/tool/*: SkipByDesign # Only meant to run on vm
 build_integration/test/*: SkipByDesign # Only meant to run on vm, most use dart:mirrors and dart:io
 compiler/tool/*: SkipByDesign # Only meant to run on vm
-dartdev/test/command_test: SkipByDesign # Only meant to run on vm (uses dart:io)
+dartdev/test/*: SkipByDesign # Only meant to run on vm
 dartfix/test/*: SkipByDesign # Only meant to run on vm
 front_end/test/*: SkipByDesign # Only meant to run on vm, most use dart:mirrors and dart:io
 front_end/tool/*: SkipByDesign # Only meant to run on vm
-modular_test/test/memory_pipeline_test: Slow
-modular_test/test/validate_pipeline_test: Slow
-modular_test/test/validate_suite_test: Slow
+modular_test/test/memory_pipeline_test: Slow, Pass
+modular_test/test/validate_pipeline_test: Slow, Pass
+modular_test/test/validate_suite_test: Slow, Pass
 nnbd_migration/test/*: SkipByDesign # Uses mirrors
 smith/test/*: SkipByDesign # Only meant to run on vm
 status_file/test/normalize_test: SkipByDesign # Uses dart:io
@@ -93,30 +93,30 @@
 *: SkipByDesign # The pkg test framework imports dart:mirrors.
 
 [ $runtime == vm ]
-analysis_server/test/benchmarks_test: Slow
-analysis_server/test/domain_completion_test: Slow
-analysis_server/test/edit/refactoring_test: Slow
-analysis_server/test/integration/*: Slow
-analysis_server/test/services/completion/dart/imported_reference_contributor_test: Slow
-analysis_server/test/services/completion/dart/keyword_contributor_test: Slow
-analysis_server/test/services/completion/dart/local_constructor_contributor_test: Slow
-analysis_server/test/services/completion/dart/local_reference_contributor_test: Slow
-analysis_server/test/services/completion/dart/type_member_contributor_test: Slow
-analysis_server/test/services/correction/assist_test: Slow
-analysis_server/test/services/refactoring/extract_method_test: Slow
-analysis_server/test/services/refactoring/inline_method_test: Slow
+analysis_server/test/benchmarks_test: Slow, Pass
+analysis_server/test/domain_completion_test: Slow, Pass
+analysis_server/test/edit/refactoring_test: Slow, Pass
+analysis_server/test/integration/*: Slow, Pass
+analysis_server/test/services/completion/dart/imported_reference_contributor_test: Slow, Pass
+analysis_server/test/services/completion/dart/keyword_contributor_test: Slow, Pass
+analysis_server/test/services/completion/dart/local_constructor_contributor_test: Slow, Pass
+analysis_server/test/services/completion/dart/local_reference_contributor_test: Slow, Pass
+analysis_server/test/services/completion/dart/type_member_contributor_test: Slow, Pass
+analysis_server/test/services/correction/assist_test: Slow, Pass
+analysis_server/test/services/refactoring/extract_method_test: Slow, Pass
+analysis_server/test/services/refactoring/inline_method_test: Slow, Pass
 analysis_server/test/socket_server_test: Skip # Pass, Slow
-analysis_server/test/src/plugin/plugin_manager_test: Slow
-analyzer/test/generated/hint_code_driver_test: Slow
-analyzer/test/generated/non_error_resolver_kernel_test: Slow
-analyzer/test/generated/strong_mode_driver_test: Slow
-analyzer/test/src/dart/analysis/driver_resolution_kernel_test: Slow
-analyzer/test/src/dart/analysis/driver_test: Slow
-analyzer/test/src/summary/resynthesize_ast_test: Slow
-analyzer/test/src/task/strong/front_end_inference_test: Slow
-analyzer/test/src/task/strong/inferred_type_test: Slow
-analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test: Slow
-analyzer_plugin/test/src/utilities/completion/optype_test: Slow
+analysis_server/test/src/plugin/plugin_manager_test: Slow, Pass
+analyzer/test/generated/hint_code_driver_test: Slow, Pass
+analyzer/test/generated/non_error_resolver_kernel_test: Slow, Pass
+analyzer/test/generated/strong_mode_driver_test: Slow, Pass
+analyzer/test/src/dart/analysis/driver_resolution_kernel_test: Slow, Pass
+analyzer/test/src/dart/analysis/driver_test: Slow, Pass
+analyzer/test/src/summary/resynthesize_ast_test: Slow, Pass
+analyzer/test/src/task/strong/front_end_inference_test: Slow, Pass
+analyzer/test/src/task/strong/inferred_type_test: Slow, Pass
+analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test: Slow, Pass
+analyzer_plugin/test/src/utilities/completion/optype_test: Slow, Pass
 mutation_observer: Skip # Skip tests on the VM if the package depends on dart:html
 
 [ $runtime != vm ]
@@ -155,7 +155,7 @@
 kernel/test/*: SkipByDesign # Uses dart:io and bigints.
 
 [ $arch == x64 && $runtime == vm && $system == windows && $checked ]
-analyzer/test/src/task/strong/inferred_type_test: Slow
+analyzer/test/src/task/strong/inferred_type_test: Slow, Pass
 
 [ $builder_tag != dart2js_analyzer && $compiler == dart2js ]
 analysis_server/test/*: Skip # Issue 26813
@@ -171,7 +171,7 @@
 modular_test/test/src/find_sdk_root2_test: SkipByDesign
 
 [ $compiler == dart2js && $runtime == chrome && $system == macos ]
-third_party/di_tests/di_test: Slow # Issue 22896
+third_party/di_tests/di_test: Slow, Pass # Issue 22896
 
 [ $compiler == dart2js && $runtime == d8 ]
 front_end/test/src/base/uri_resolver_test: SkipByDesign # Relies on access to file system
@@ -180,11 +180,11 @@
 front_end/test/mixin_export_test: RuntimeError # Issue 30576
 
 [ $compiler == dart2js && $browser ]
-crypto/test/sha1_test: Slow
-crypto/test/sha256_test: Slow
+crypto/test/sha1_test: Slow, Pass
+crypto/test/sha256_test: Slow, Pass
 
 [ $compiler == dart2js && $checked ]
-crypto/test/base64_test: Slow
+crypto/test/base64_test: Slow, Pass
 
 [ $compiler == dart2js && $csp ]
 mutation_observer: Skip # This test cannot run under CSP because it is injecting a JavaScript polyfill
@@ -199,21 +199,21 @@
 
 [ $runtime == vm && $system == windows ]
 analysis_server/test/analysis/get_errors_test: Skip # runtime error, Issue 22180
-analysis_server/test/src/plugin/plugin_manager_test: Slow # Issue 34231
-analyzer/test/src/task/strong/checker_test: Slow
-analyzer/tool/task_dependency_graph/check_test: Slow
+analysis_server/test/src/plugin/plugin_manager_test: Slow, Pass # Issue 34231
+analyzer/test/src/task/strong/checker_test: Slow, Pass
+analyzer/tool/task_dependency_graph/check_test: Slow, Pass
 
 [ $runtime == vm && $system == windows && $checked ]
 front_end/tool/perf_test: Slow, Pass
 
 [ $runtime == vm && $checked ]
-analysis_server/test/completion_test: Slow
-analysis_server/test/integration/edit/sort_members_test: Slow
-analysis_server/test/services/correction/fix_test: Slow
+analysis_server/test/completion_test: Slow, Pass
+analysis_server/test/integration/edit/sort_members_test: Slow, Pass
+analysis_server/test/services/correction/fix_test: Slow, Pass
 analysis_server/test/socket_server_test: Skip # Pass, Slow
-analyzer/test/generated/non_error_resolver_kernel_test: Slow
-analyzer/test/src/summary/resynthesize_ast_test: Slow
-analyzer/test/src/task/strong/front_end_inference_test: Slow
+analyzer/test/generated/non_error_resolver_kernel_test: Slow, Pass
+analyzer/test/src/summary/resynthesize_ast_test: Slow, Pass
+analyzer/test/src/task/strong/front_end_inference_test: Slow, Pass
 
 # Timeout. These tests do not run efficiently on our simulator or low-end
 # devices.
diff --git a/pkg/smith/lib/configuration.dart b/pkg/smith/lib/configuration.dart
index 719df1e..fdc14d2 100644
--- a/pkg/smith/lib/configuration.dart
+++ b/pkg/smith/lib/configuration.dart
@@ -263,7 +263,8 @@
         useElf: boolOption("use-elf"),
         useHotReload: boolOption("hot-reload"),
         useHotReloadRollback: boolOption("hot-reload-rollback"),
-        useSdk: boolOption("use-sdk"));
+        useSdk: boolOption("use-sdk"),
+        useQemu: boolOption("use-qemu"));
 
     // Should have consumed the whole map.
     if (optionsCopy.isNotEmpty) {
@@ -338,6 +339,8 @@
 
   final bool useSdk;
 
+  final bool useQemu;
+
   Configuration(this.name, this.architecture, this.compiler, this.mode,
       this.runtime, this.system,
       {NnbdMode nnbdMode,
@@ -360,7 +363,8 @@
       bool useElf,
       bool useHotReload,
       bool useHotReloadRollback,
-      bool useSdk})
+      bool useSdk,
+      bool useQemu})
       : nnbdMode = nnbdMode ?? NnbdMode.legacy,
         sanitizer = sanitizer ?? Sanitizer.none,
         babel = babel ?? "",
@@ -381,7 +385,8 @@
         useElf = useElf ?? false,
         useHotReload = useHotReload ?? false,
         useHotReloadRollback = useHotReloadRollback ?? false,
-        useSdk = useSdk ?? false;
+        useSdk = useSdk ?? false,
+        useQemu = useQemu ?? false;
 
   /// Returns `true` if this configuration's options all have the same values
   /// as [other].
@@ -411,7 +416,8 @@
       useElf == other.useElf &&
       useHotReload == other.useHotReload &&
       useHotReloadRollback == other.useHotReloadRollback &&
-      useSdk == other.useSdk;
+      useSdk == other.useSdk &&
+      useQemu == other.useQemu;
 
   /// Whether [a] and [b] contain the same strings, regardless of order.
   bool _listsEqual(List<String> a, List<String> b) {
@@ -460,7 +466,8 @@
         useElf,
         useHotReload,
         useHotReloadRollback,
-        useSdk
+        useSdk,
+        useQemu
       ]);
 
   String toString() {
@@ -500,6 +507,7 @@
     if (useHotReload) fields.add("hot-reload");
     if (useHotReloadRollback) fields.add("hot-reload-rollback");
     if (useSdk) fields.add("use-sdk");
+    if (useQemu) fields.add("use-qemu");
 
     buffer.write(fields.join(", "));
     buffer.write(")");
@@ -559,6 +567,7 @@
     boolField("hot-reload-rollback", useHotReloadRollback,
         other.useHotReloadRollback);
     boolField("use-sdk", useSdk, other.useSdk);
+    boolField("use-qemu", useQemu, other.useQemu);
 
     buffer.write(fields.join("\n   "));
     buffer.write("\n");
diff --git a/pkg/smith/lib/test_matrix.dart b/pkg/smith/lib/test_matrix.dart
index 0b8d003..5c8c35d 100644
--- a/pkg/smith/lib/test_matrix.dart
+++ b/pkg/smith/lib/test_matrix.dart
@@ -12,6 +12,7 @@
 class TestMatrix {
   final List<Configuration> configurations;
   final List<Builder> builders;
+  final List<String> branches;
 
   /// Reads a test matrix from the file at [path].
   static TestMatrix fromPath(String path) {
@@ -53,9 +54,10 @@
 
     var builderConfigurations = <Map>[...?json["builder_configurations"]];
     var builders = parseBuilders(builderConfigurations, configurations);
+    var branches = <String>[...?json["branches"]];
 
-    return TestMatrix._(configurations, builders);
+    return TestMatrix._(configurations, builders, branches);
   }
 
-  TestMatrix._(this.configurations, this.builders);
+  TestMatrix._(this.configurations, this.builders, this.branches);
 }
diff --git a/pkg/smith/test/test_matrix_test.dart b/pkg/smith/test/test_matrix_test.dart
index e4acbca..0884e67 100644
--- a/pkg/smith/test/test_matrix_test.dart
+++ b/pkg/smith/test/test_matrix_test.dart
@@ -121,6 +121,13 @@
       });
     });
   });
+
+  test("a list of branches is parsed", () {
+    var testMatrix = TestMatrix.fromJson({
+      "branches": ["master", "stable"]
+    });
+    expect(testMatrix.branches, unorderedEquals(["master", "stable"]));
+  });
 }
 
 void expectJsonError(String error, Map<String, dynamic> json) {
diff --git a/pkg/test_runner/lib/src/command.dart b/pkg/test_runner/lib/src/command.dart
index c03d4d2..938d48c 100644
--- a/pkg/test_runner/lib/src/command.dart
+++ b/pkg/test_runner/lib/src/command.dart
@@ -615,6 +615,7 @@
   AdbDartkCommand indexedCopy(int index) => AdbDartkCommand(
       buildPath, processTestFilename, kernelFile, arguments, extraLibraries,
       index: index);
+
   _buildHashCode(HashCodeBuilder builder) {
     super._buildHashCode(builder);
     builder.add(buildPath);
@@ -630,6 +631,11 @@
       extraLibraries == other.extraLibraries &&
       kernelFile == other.kernelFile;
 
+  VMCommandOutput createOutput(int exitCode, bool timedOut, List<int> stdout,
+          List<int> stderr, Duration time, bool compilationSkipped,
+          [int pid = 0]) =>
+      VMCommandOutput(this, exitCode, timedOut, stdout, stderr, time, pid);
+
   String toString() => 'Steps to push Dart VM and Dill file '
       'to an attached device. Uses (and requires) adb.';
 }
diff --git a/pkg/test_runner/lib/src/compiler_configuration.dart b/pkg/test_runner/lib/src/compiler_configuration.dart
index a73d480..462ccba 100644
--- a/pkg/test_runner/lib/src/compiler_configuration.dart
+++ b/pkg/test_runner/lib/src/compiler_configuration.dart
@@ -688,6 +688,10 @@
         }
       } else if (_configuration.builderTag == "crossword") {
         exec = "${buildDir}_X64/gen_snapshot";
+      } else if (_configuration.useQemu) {
+        // DebugXARM --> DebugSIMARM_X64
+        final simBuildDir = buildDir.replaceAll("XARM", "SIMARM_X64");
+        exec = "$simBuildDir/gen_snapshot";
       } else {
         exec = "$buildDir/gen_snapshot";
       }
@@ -706,7 +710,10 @@
       ],
       if (_isAndroid && _isArm) '--no-sim-use-hardfp',
       if (_configuration.isMinified) '--obfuscate',
-      ..._replaceDartFiles(arguments, tempKernelFile(tempDir))
+      // The SIMARM precompiler assumes support for integer division, but the
+      // Qemu arm cpus do not support integer division.
+      if (_configuration.useQemu) '--no-use-integer-division',
+      ..._replaceDartFiles(arguments, tempKernelFile(tempDir)),
     ];
 
     return CompilationCommand('precompiler', tempDir, bootstrapDependencies(),
@@ -729,7 +736,7 @@
           "$host-x86_64/bin/$abiTriple-gcc";
       shared = '-shared';
     } else if (Platform.isLinux) {
-      if (_isSimArm) {
+      if (_isSimArm || _configuration.useQemu) {
         cc = 'arm-linux-gnueabihf-gcc';
       } else {
         cc = 'gcc';
diff --git a/pkg/test_runner/lib/src/configuration.dart b/pkg/test_runner/lib/src/configuration.dart
index ba2f2da..4982613 100644
--- a/pkg/test_runner/lib/src/configuration.dart
+++ b/pkg/test_runner/lib/src/configuration.dart
@@ -68,8 +68,7 @@
       this.outputDirectory,
       this.reproducingArguments,
       this.fastTestsOnly,
-      this.printPassingStdout,
-      this.useQemu})
+      this.printPassingStdout})
       : _packages = packages;
 
   final Map<String, RegExp> selectors;
@@ -98,7 +97,6 @@
   final bool writeResults;
   final bool writeLogs;
   final bool printPassingStdout;
-  final bool useQemu;
 
   Architecture get architecture => configuration.architecture;
   Compiler get compiler => configuration.compiler;
@@ -121,6 +119,7 @@
   bool get useElf => configuration.useElf;
   bool get useSdk => configuration.useSdk;
   bool get enableAsserts => configuration.enableAsserts;
+  bool get useQemu => configuration.useQemu;
 
   // Various file paths.
 
diff --git a/pkg/test_runner/lib/src/options.dart b/pkg/test_runner/lib/src/options.dart
index cedfc85..09a824c 100644
--- a/pkg/test_runner/lib/src/options.dart
+++ b/pkg/test_runner/lib/src/options.dart
@@ -26,7 +26,7 @@
   'service',
   'kernel',
   'observatory_ui',
-  'ffi'
+  'ffi_2'
 ];
 
 /// Specifies a single command line option.
@@ -751,8 +751,7 @@
           reproducingArguments:
               _reproducingCommand(data, namedConfiguration != null),
           fastTestsOnly: data["fast_tests"] as bool,
-          printPassingStdout: data["print_passing_stdout"] as bool,
-          useQemu: data["use_qemu"] as bool);
+          printPassingStdout: data["print_passing_stdout"] as bool);
 
       if (configuration.validate()) {
         result.add(configuration);
@@ -829,7 +828,8 @@
                   dart2jsOptions: dart2jsOptions,
                   experiments: experiments,
                   babel: data['babel'] as String,
-                  builderTag: data["builder_tag"] as String);
+                  builderTag: data["builder_tag"] as String,
+                  useQemu: data["use_qemu"] as bool);
               addConfiguration(configuration);
             }
           }
diff --git a/pkg/test_runner/lib/src/runtime_configuration.dart b/pkg/test_runner/lib/src/runtime_configuration.dart
index b377f637..05fbe2b 100644
--- a/pkg/test_runner/lib/src/runtime_configuration.dart
+++ b/pkg/test_runner/lib/src/runtime_configuration.dart
@@ -300,9 +300,14 @@
       throw "dart_precompiled cannot run files of type '$type'.";
     }
 
-    return [
-      VMCommand(dartPrecompiledBinaryFileName, arguments, environmentOverrides)
-    ];
+    var executable = dartPrecompiledBinaryFileName;
+
+    if (_configuration.useQemu) {
+      arguments.insertAll(0, ['-L', '/usr/arm-linux-gnueabihf/', executable]);
+      executable = 'qemu-arm';
+    }
+
+    return [VMCommand(executable, arguments, environmentOverrides)];
   }
 }
 
diff --git a/pkg/test_runner/lib/src/test_configurations.dart b/pkg/test_runner/lib/src/test_configurations.dart
index 912bbb6..cce2e8d 100644
--- a/pkg/test_runner/lib/src/test_configurations.dart
+++ b/pkg/test_runner/lib/src/test_configurations.dart
@@ -45,6 +45,7 @@
   Path('tests/standalone'),
   Path('tests/standalone_2'),
   Path('tests/ffi'),
+  Path('tests/ffi_2'),
   Path('utils/tests/peg'),
 ];
 
diff --git a/pkg/vm/lib/target/flutter.dart b/pkg/vm/lib/target/flutter.dart
index 9d63c74..d95c679 100644
--- a/pkg/vm/lib/target/flutter.dart
+++ b/pkg/vm/lib/target/flutter.dart
@@ -5,6 +5,7 @@
 
 import 'package:kernel/ast.dart' show Component, Library;
 import 'package:kernel/core_types.dart' show CoreTypes;
+import 'package:kernel/target/changed_structure_notifier.dart';
 import 'package:kernel/target/targets.dart';
 import 'package:kernel/transformations/track_widget_constructor_locations.dart';
 import 'package:vm/target/vm.dart' show VmTarget;
@@ -56,7 +57,8 @@
       CoreTypes coreTypes,
       List<Library> libraries,
       DiagnosticReporter diagnosticReporter,
-      {void logger(String msg)}) {
+      {void logger(String msg),
+      ChangedStructureNotifier changedStructureNotifier}) {
     super.performPreConstantEvaluationTransformations(
         component, coreTypes, libraries, diagnosticReporter,
         logger: logger);
diff --git a/pkg/vm/lib/target/vm.dart b/pkg/vm/lib/target/vm.dart
index 837a242..66458c9 100644
--- a/pkg/vm/lib/target/vm.dart
+++ b/pkg/vm/lib/target/vm.dart
@@ -10,6 +10,7 @@
 import 'package:kernel/class_hierarchy.dart';
 import 'package:kernel/core_types.dart';
 import 'package:kernel/reference_from_index.dart';
+import 'package:kernel/target/changed_structure_notifier.dart';
 import 'package:kernel/target/targets.dart';
 import 'package:kernel/transformations/mixin_full_resolution.dart'
     as transformMixins show transformLibraries;
@@ -110,7 +111,8 @@
       CoreTypes coreTypes,
       List<Library> libraries,
       DiagnosticReporter diagnosticReporter,
-      {void logger(String msg)}) {
+      {void logger(String msg),
+      ChangedStructureNotifier changedStructureNotifier}) {
     super.performPreConstantEvaluationTransformations(
         component, coreTypes, libraries, diagnosticReporter,
         logger: logger);
@@ -140,15 +142,22 @@
       Map<String, String> environmentDefines,
       DiagnosticReporter diagnosticReporter,
       ReferenceFromIndex referenceFromIndex,
-      {void logger(String msg)}) {
+      {void logger(String msg),
+      ChangedStructureNotifier changedStructureNotifier}) {
     transformMixins.transformLibraries(
         this, coreTypes, hierarchy, libraries, referenceFromIndex,
         doSuperResolution: false /* resolution is done in Dart VM */);
     logger?.call("Transformed mixin applications");
 
     transformFfi.ReplacedMembers replacedFields =
-        transformFfiDefinitions.transformLibraries(component, coreTypes,
-            hierarchy, libraries, diagnosticReporter, referenceFromIndex);
+        transformFfiDefinitions.transformLibraries(
+            component,
+            coreTypes,
+            hierarchy,
+            libraries,
+            diagnosticReporter,
+            referenceFromIndex,
+            changedStructureNotifier);
     transformFfiUseSites.transformLibraries(component, coreTypes, hierarchy,
         libraries, diagnosticReporter, replacedFields, referenceFromIndex);
     logger?.call("Transformed ffi annotations");
diff --git a/pkg/vm/lib/transformations/ffi_definitions.dart b/pkg/vm/lib/transformations/ffi_definitions.dart
index 5c16d85..97aa087 100644
--- a/pkg/vm/lib/transformations/ffi_definitions.dart
+++ b/pkg/vm/lib/transformations/ffi_definitions.dart
@@ -19,6 +19,7 @@
 import 'package:kernel/core_types.dart';
 import 'package:kernel/library_index.dart' show LibraryIndex;
 import 'package:kernel/reference_from_index.dart';
+import 'package:kernel/target/changed_structure_notifier.dart';
 import 'package:kernel/target/targets.dart' show DiagnosticReporter;
 import 'package:kernel/type_environment.dart' show SubtypeCheckMode;
 
@@ -61,15 +62,16 @@
     ClassHierarchy hierarchy,
     List<Library> libraries,
     DiagnosticReporter diagnosticReporter,
-    ReferenceFromIndex referenceFromIndex) {
+    ReferenceFromIndex referenceFromIndex,
+    ChangedStructureNotifier changedStructureNotifier) {
   final LibraryIndex index =
       LibraryIndex(component, const ["dart:ffi", "dart:core"]);
   if (!index.containsLibrary("dart:ffi")) {
     // If dart:ffi is not loaded, do not do the transformation.
     return ReplacedMembers({}, {});
   }
-  final transformer = new _FfiDefinitionTransformer(
-      index, coreTypes, hierarchy, diagnosticReporter, referenceFromIndex);
+  final transformer = new _FfiDefinitionTransformer(index, coreTypes, hierarchy,
+      diagnosticReporter, referenceFromIndex, changedStructureNotifier);
   libraries.forEach(transformer.visitLibrary);
   return ReplacedMembers(
       transformer.replacedGetters, transformer.replacedSetters);
@@ -82,6 +84,8 @@
   Map<Field, Procedure> replacedGetters = {};
   Map<Field, Procedure> replacedSetters = {};
 
+  ChangedStructureNotifier changedStructureNotifier;
+
   IndexedLibrary currentLibraryIndex;
 
   _FfiDefinitionTransformer(
@@ -89,7 +93,8 @@
       CoreTypes coreTypes,
       ClassHierarchy hierarchy,
       DiagnosticReporter diagnosticReporter,
-      ReferenceFromIndex referenceFromIndex)
+      ReferenceFromIndex referenceFromIndex,
+      this.changedStructureNotifier)
       : super(index, coreTypes, hierarchy, diagnosticReporter,
             referenceFromIndex) {}
 
@@ -123,6 +128,7 @@
     if (fieldsValid) {
       final structSize = _replaceFields(node, indexedClass);
       _replaceSizeOfMethod(node, structSize, indexedClass);
+      changedStructureNotifier?.forClass(node);
     }
 
     return node;
diff --git a/pkg/vm/lib/transformations/type_flow/summary_collector.dart b/pkg/vm/lib/transformations/type_flow/summary_collector.dart
index 673264a..f0021f0 100644
--- a/pkg/vm/lib/transformations/type_flow/summary_collector.dart
+++ b/pkg/vm/lib/transformations/type_flow/summary_collector.dart
@@ -10,7 +10,8 @@
 import 'package:kernel/target/targets.dart';
 import 'package:kernel/ast.dart' hide Statement, StatementVisitor;
 import 'package:kernel/ast.dart' as ast show Statement, StatementVisitor;
-import 'package:kernel/class_hierarchy.dart' show ClosedWorldClassHierarchy;
+import 'package:kernel/class_hierarchy.dart'
+    show ClassHierarchy, ClosedWorldClassHierarchy;
 import 'package:kernel/type_environment.dart'
     show StaticTypeContext, SubtypeCheckMode, TypeEnvironment;
 import 'package:kernel/type_algebra.dart' show Substitution;
@@ -113,6 +114,13 @@
               }
             }
           }
+        } else if (st is Narrow) {
+          // This pattern may appear after approximations during summary
+          // normalization (so it's not enough to handle it in _makeNarrow).
+          final arg = st.arg;
+          if (arg is Type && st.type == const AnyType()) {
+            return (arg is NullableType) ? arg.baseType : arg;
+          }
         }
 
         _processed.add(st);
@@ -472,6 +480,12 @@
   }
 }
 
+Iterable<Name> getSelectors(ClassHierarchy hierarchy, Class cls,
+        {bool setters = false}) =>
+    hierarchy
+        .getInterfaceMembers(cls, setters: setters)
+        .map((Member m) => m.name);
+
 enum FieldSummaryType { kFieldGuard, kInitializer }
 
 /// Create a type flow summary for a member from the kernel AST.
@@ -488,6 +502,8 @@
   final Map<AsExpression, TypeCheck> explicitCasts =
       <AsExpression, TypeCheck>{};
   final _FallthroughDetector _fallthroughDetector = new _FallthroughDetector();
+  final Set<Name> _nullMethodsAndGetters = <Name>{};
+  final Set<Name> _nullSetters = <Name>{};
 
   Summary _summary;
   _VariablesInfoCollector _variablesInfo;
@@ -542,6 +558,12 @@
       this._genericInterfacesInfo) {
     assertx(_genericInterfacesInfo != null);
     constantAllocationCollector = new ConstantAllocationCollector(this);
+    _nullMethodsAndGetters.addAll(getSelectors(
+        _hierarchy, _environment.coreTypes.nullClass,
+        setters: false));
+    _nullSetters.addAll(getSelectors(
+        _hierarchy, _environment.coreTypes.nullClass,
+        setters: true));
   }
 
   Summary createSummary(Member member,
@@ -1041,6 +1063,9 @@
         return (arg is NullableType) ? arg.baseType : arg;
       }
     }
+    if (type is NullableType && type.baseType == const AnyType()) {
+      return arg;
+    }
     Narrow narrow = new Narrow(arg, type);
     _summary.add(narrow);
     return narrow;
@@ -1290,15 +1315,37 @@
     _variableValues = null;
   }
 
+  void _updateReceiverAfterCall(
+      TreeNode receiverNode, TypeExpr receiverValue, Name selector,
+      {bool isSetter = false}) {
+    if (receiverNode is VariableGet) {
+      final nullSelectors = isSetter ? _nullSetters : _nullMethodsAndGetters;
+      if (!nullSelectors.contains(selector)) {
+        final int varIndex = _variablesInfo.varIndex[receiverNode.variable];
+        if (_variableCells[varIndex] == null) {
+          _variableValues[varIndex] =
+              _makeNarrow(receiverValue, const AnyType());
+        }
+      }
+    }
+  }
+
   @override
   defaultTreeNode(TreeNode node) =>
       throw 'Unexpected node ${node.runtimeType}: $node at ${node.location}';
 
   @override
   TypeExpr visitAsExpression(AsExpression node) {
-    final TypeExpr operand = _visit(node.operand);
+    final operandNode = node.operand;
+    final TypeExpr operand = _visit(operandNode);
     final TypeExpr result = _typeCheck(operand, node.type, node);
     explicitCasts[node] = result;
+    if (operandNode is VariableGet) {
+      final int varIndex = _variablesInfo.varIndex[operandNode.variable];
+      if (_variableCells[varIndex] == null) {
+        _variableValues[varIndex] = result;
+      }
+    }
     return result;
   }
 
@@ -1485,6 +1532,7 @@
         return _handleIndexingIntoListConstant(constant);
       }
     }
+    TypeExpr result;
     if (target == null) {
       if (node.name.name == '==') {
         assertx(args.values.length == 2);
@@ -1502,32 +1550,35 @@
           return _staticType(node);
         }
       }
-      return _makeCall(
+      result = _makeCall(
           node, new DynamicSelector(CallKind.Method, node.name), args);
-    }
-    // TODO(dartbug.com/34497): Once front-end desugars calls via
-    // fields/getters, handling of field and getter targets here
-    // can be turned into assertions.
-    if ((target is Field) || ((target is Procedure) && target.isGetter)) {
-      // Call via field/getter.
-      final value = _makeCall(
-          null,
-          (node.receiver is ThisExpression)
-              ? new VirtualSelector(target, callKind: CallKind.PropertyGet)
-              : new InterfaceSelector(target, callKind: CallKind.PropertyGet),
-          new Args<TypeExpr>([receiver]));
-      _makeCall(
-          null, DynamicSelector.kCall, new Args.withReceiver(args, value));
-      return _staticType(node);
     } else {
-      // TODO(alexmarkov): overloaded arithmetic operators
-      return _makeCall(
-          node,
-          (node.receiver is ThisExpression)
-              ? new VirtualSelector(target)
-              : new InterfaceSelector(target),
-          args);
+      // TODO(dartbug.com/34497): Once front-end desugars calls via
+      // fields/getters, handling of field and getter targets here
+      // can be turned into assertions.
+      if ((target is Field) || ((target is Procedure) && target.isGetter)) {
+        // Call via field/getter.
+        final value = _makeCall(
+            null,
+            (receiverNode is ThisExpression)
+                ? new VirtualSelector(target, callKind: CallKind.PropertyGet)
+                : new InterfaceSelector(target, callKind: CallKind.PropertyGet),
+            new Args<TypeExpr>([receiver]));
+        _makeCall(
+            null, DynamicSelector.kCall, new Args.withReceiver(args, value));
+        result = _staticType(node);
+      } else {
+        // TODO(alexmarkov): overloaded arithmetic operators
+        result = _makeCall(
+            node,
+            (node.receiver is ThisExpression)
+                ? new VirtualSelector(target)
+                : new InterfaceSelector(target),
+            args);
+      }
     }
+    _updateReceiverAfterCall(receiverNode, receiver, node.name);
+    return result;
   }
 
   TypeExpr _handleIndexingIntoListConstant(ListConstant list) {
@@ -1553,16 +1604,20 @@
     var receiver = _visit(node.receiver);
     var args = new Args<TypeExpr>([receiver]);
     final target = node.interfaceTarget;
+    TypeExpr result;
     if (target == null) {
-      return _makeCall(
+      result = _makeCall(
           node, new DynamicSelector(CallKind.PropertyGet, node.name), args);
+    } else {
+      result = _makeCall(
+          node,
+          (node.receiver is ThisExpression)
+              ? new VirtualSelector(target, callKind: CallKind.PropertyGet)
+              : new InterfaceSelector(target, callKind: CallKind.PropertyGet),
+          args);
     }
-    return _makeCall(
-        node,
-        (node.receiver is ThisExpression)
-            ? new VirtualSelector(target, callKind: CallKind.PropertyGet)
-            : new InterfaceSelector(target, callKind: CallKind.PropertyGet),
-        args);
+    _updateReceiverAfterCall(node.receiver, receiver, node.name);
+    return result;
   }
 
   @override
@@ -1583,6 +1638,8 @@
               : new InterfaceSelector(target, callKind: CallKind.PropertySet),
           args);
     }
+    _updateReceiverAfterCall(node.receiver, receiver, node.name,
+        isSetter: true);
     return value;
   }
 
diff --git a/pkg/vm/testcases/bytecode/type_ops.dart.expect b/pkg/vm/testcases/bytecode/type_ops.dart.expect
index dd6936e..86e516b 100644
--- a/pkg/vm/testcases/bytecode/type_ops.dart.expect
+++ b/pkg/vm/testcases/bytecode/type_ops.dart.expect
@@ -692,7 +692,7 @@
   class D<P extends dart.core::Object* = dynamic, Q extends dart.core::Object* = dynamic> extends #lib::C<dart.core::int*, #lib::D::Q*, #lib::D::P*> {
     generic-covariant-impl field dart.core::Map<#lib::D::P*, #lib::D::Q*>* foo;
     constructor •(dynamic tt) → #lib::D<#lib::D::P*, #lib::D::Q*>*
-      : #lib::D::foo = tt as{TypeError} dart.core::Map<#lib::D::P*, #lib::D::Q*>*, super #lib::C::•()
+      : #lib::D::foo = tt as{TypeError,ForDynamic} dart.core::Map<#lib::D::P*, #lib::D::Q*>*, super #lib::C::•()
       ;
     method foo2(dynamic y) → dynamic {
       if(y is #lib::A<#lib::D::P*>*) {
@@ -701,7 +701,7 @@
       if(y is #lib::C<dynamic, #lib::D::Q*, dart.core::List<#lib::D::P*>*>*) {
         dart.core::print("22");
       }
-      [@vm.call-site-attributes.metadata=receiverType:#lib::D<#lib::D::P*, #lib::D::Q*>*] this.{#lib::D::foo} = y as{TypeError} dart.core::Map<#lib::D::P*, #lib::D::Q*>*;
+      [@vm.call-site-attributes.metadata=receiverType:#lib::D<#lib::D::P*, #lib::D::Q*>*] this.{#lib::D::foo} = y as{TypeError,ForDynamic} dart.core::Map<#lib::D::P*, #lib::D::Q*>*;
     }
     method foo3<T1 extends dart.core::Object* = dynamic, T2 extends dart.core::Object* = dynamic>(dynamic z) → dynamic {
       if(z is #lib::A<#lib::D::foo3::T1*>*) {
@@ -713,8 +713,8 @@
       return (z as dart.core::Map<#lib::D::foo3::T2*, #lib::D::Q*>*).{dart.core::Map::values};
     }
     method foo4(dynamic w) → dart.core::Map<#lib::D::P*, #lib::D::Q*>* {
-      dart.core::List<dart.core::Map<#lib::D::P*, #lib::D::Q*>*>* list = <dart.core::Map<#lib::D::P*, #lib::D::Q*>*>[w as{TypeError} dart.core::Map<#lib::D::P*, #lib::D::Q*>*];
-      return w as{TypeError} dart.core::Map<#lib::D::P*, #lib::D::Q*>*;
+      dart.core::List<dart.core::Map<#lib::D::P*, #lib::D::Q*>*>* list = <dart.core::Map<#lib::D::P*, #lib::D::Q*>*>[w as{TypeError,ForDynamic} dart.core::Map<#lib::D::P*, #lib::D::Q*>*];
+      return w as{TypeError,ForDynamic} dart.core::Map<#lib::D::P*, #lib::D::Q*>*;
     }
   }
   class E<P extends dart.core::String* = dart.core::String*> extends dart.core::Object {
@@ -754,7 +754,7 @@
     return x as #lib::A<dart.core::int*>*;
   }
   static method foo5(dynamic x) → void {
-    #lib::globalVar = x as{TypeError} dart.core::List<dart.core::Iterable<dynamic>*>*;
+    #lib::globalVar = x as{TypeError,ForDynamic} dart.core::List<dart.core::Iterable<dynamic>*>*;
   }
   static method main() → dynamic {}
 }
diff --git a/pkg/vm/testcases/transformations/type_flow/summary_collector/bool_expressions.dart.expect b/pkg/vm/testcases/transformations/type_flow/summary_collector/bool_expressions.dart.expect
index b206c1d..f99332f 100644
--- a/pkg/vm/testcases/transformations/type_flow/summary_collector/bool_expressions.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/summary_collector/bool_expressions.dart.expect
@@ -6,22 +6,21 @@
 RESULT: _T {}?
 ------------ #lib::bool_expressions ------------
 t0* = _Call direct [#lib::foo] ()
-t1 = _TypeCheck (t0 against dart.core::bool) (for #lib::foo() as{TypeError} dart.core::bool*)
+t1 = _TypeCheck (t0 against dart.core::bool) (for #lib::foo() as{TypeError,ForDynamic} dart.core::bool*)
 t2* = _Call direct [#lib::bar] ()
-t3* = _Call [dart.core::num::+] (_T (dart.core::int)+?, _T (dart.core::_Smi, 1))
+t3* = _Call [dart.core::num::+] (_T (dart.core::int)+, _T (dart.core::_Smi, 1))
 i_0 = _Join [dart.core::int*] (_T (dart.core::_Smi, 0), t3)
 t5* = _Call [dart.core::num::<] (i_0, _T (dart.core::_Smi, 10))
 t6* = _Call direct [#lib::bar] ()
 t7* = _Call direct [#lib::foo] ()
 t8 = _Join [dynamic] (_T (dart.core::bool, true), t7)
-t9 = _Narrow (t8 to _T ANY?)
-t10 = _TypeCheck (t9 against dart.core::bool) (for (x{dart.core::bool*} ?{dynamic} true : #lib::foo()) as{TypeError} dart.core::bool*)
+t9 = _TypeCheck (t8 against dart.core::bool) (for (x{dart.core::bool*} ?{dynamic} true : #lib::foo()) as{TypeError,ForDynamic} dart.core::bool*)
+t10* = _Call direct [#lib::bar] ()
 t11* = _Call direct [#lib::bar] ()
-t12* = _Call direct [#lib::bar] ()
-t13* = _Call direct [#lib::foo] ()
-t14 = _TypeCheck (t13 against dart.core::bool) (for #lib::foo() as{TypeError} dart.core::bool*)
-t15* = _Call direct [#lib::foo] ()
-t16 = _TypeCheck (t15 against dart.core::bool) (for #lib::foo() as{TypeError} dart.core::bool*)
+t12* = _Call direct [#lib::foo] ()
+t13 = _TypeCheck (t12 against dart.core::bool) (for #lib::foo() as{TypeError,ForDynamic} dart.core::bool*)
+t14* = _Call direct [#lib::foo] ()
+t15 = _TypeCheck (t14 against dart.core::bool) (for #lib::foo() as{TypeError,ForDynamic} dart.core::bool*)
 y_0 = _Join [dart.core::bool*] (_T (dart.core::bool), _T (dart.core::bool, true))
 RESULT: _T {}?
 ------------ #lib::main ------------
diff --git a/pkg/vm/testcases/transformations/type_flow/summary_collector/calls.dart.expect b/pkg/vm/testcases/transformations/type_flow/summary_collector/calls.dart.expect
index 19e394c..9b8e411 100644
--- a/pkg/vm/testcases/transformations/type_flow/summary_collector/calls.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/summary_collector/calls.dart.expect
@@ -36,12 +36,13 @@
 %a4 = _Parameter #4 [_T (dart.core::Object)+?]
 t5 = _Call direct [#lib::B::] (_T (#lib::B))
 t6 = _Call [#lib::A::foo1] (%aa, _T (#lib::B))
-t7* = _Call get [#lib::A::foo2] (%aa)
-t8 = _TypeCheck (t7 against dart.core::int) (for aa.{#lib::A::foo2} as{TypeError} dart.core::int*)
-t9 = _Call set [#lib::A::foo3] (%aa, t8)
-t10* = _Call get [#lib::A::foo1] (%aa)
-t11* = _Call get [#lib::A::foo2] (%aa)
-t12 = _Call dynamic [call] (t11, %a2, %a3, t10)
+t7 = _Narrow (%aa to _T ANY)
+t8* = _Call get [#lib::A::foo2] (t7)
+t9 = _TypeCheck (t8 against dart.core::int) (for aa.{#lib::A::foo2} as{TypeError,ForDynamic} dart.core::int*)
+t10 = _Call set [#lib::A::foo3] (t7, t9)
+t11* = _Call get [#lib::A::foo1] (t7)
+t12* = _Call get [#lib::A::foo2] (t7)
+t13 = _Call dynamic [call] (t12, %a2, %a3, t11)
 RESULT: _T ANY?
 ------------ #lib::C::dynamicCalls ------------
 %this = _Parameter #0 [_T (#lib::C)+]
@@ -51,11 +52,12 @@
 %a4 = _Parameter #4 [_T (dart.core::Object)+?]
 t5 = _Call direct [#lib::B::] (_T (#lib::B))
 t6 = _Call dynamic [foo1] (%aa, _T (#lib::B))
-t7* = _Call dynamic get [foo2] (%aa)
-t8 = _Call dynamic set [foo3] (%aa, t7)
-t9* = _Call dynamic get [foo1] (%aa)
-t10* = _Call dynamic [foo2] (%aa, %a2, %a3, t9)
-RESULT: t10
+t7 = _Narrow (%aa to _T ANY)
+t8* = _Call dynamic get [foo2] (t7)
+t9 = _Call dynamic set [foo3] (t7, t8)
+t10* = _Call dynamic get [foo1] (t7)
+t11* = _Call dynamic [foo2] (t7, %a2, %a3, t10)
+RESULT: t11
 ------------ #lib::D:: ------------
 %this = _Parameter #0 [_T (#lib::D)+]
 t1 = _Call direct [#lib::B::] (%this)
diff --git a/pkg/vm/testcases/transformations/type_flow/summary_collector/control_flow.dart b/pkg/vm/testcases/transformations/type_flow/summary_collector/control_flow.dart
index 6b1a2e9..9dda4a4 100644
--- a/pkg/vm/testcases/transformations/type_flow/summary_collector/control_flow.dart
+++ b/pkg/vm/testcases/transformations/type_flow/summary_collector/control_flow.dart
@@ -257,4 +257,9 @@
   return x;
 }
 
+void cast1(x) {
+  foo(x as C1);
+  bar(x);
+}
+
 main() {}
diff --git a/pkg/vm/testcases/transformations/type_flow/summary_collector/control_flow.dart.expect b/pkg/vm/testcases/transformations/type_flow/summary_collector/control_flow.dart.expect
index 88b429a..eba9380 100644
--- a/pkg/vm/testcases/transformations/type_flow/summary_collector/control_flow.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/summary_collector/control_flow.dart.expect
@@ -71,10 +71,10 @@
 t2 = _Call direct [#lib::C1::] (_T (#lib::C1))
 t3 = _Call direct [#lib::C2::] (_T (#lib::C2))
 t4* = _Call direct [#lib::foo] (_T (#lib::C2))
-t5 = _TypeCheck (t4 against dart.core::bool) (for #lib::foo(x = new #lib::C2::•()) as{TypeError} dart.core::bool*)
+t5 = _TypeCheck (t4 against dart.core::bool) (for #lib::foo(x = new #lib::C2::•()) as{TypeError,ForDynamic} dart.core::bool*)
 t6 = _Call direct [#lib::C3::] (_T (#lib::C3))
 t7* = _Call direct [#lib::foo] (_T (#lib::C3))
-t8 = _TypeCheck (t7 against dart.core::bool) (for #lib::foo(x = new #lib::C3::•()) as{TypeError} dart.core::bool*)
+t8 = _TypeCheck (t7 against dart.core::bool) (for #lib::foo(x = new #lib::C3::•()) as{TypeError,ForDynamic} dart.core::bool*)
 x_0 = _Join [dynamic] (_T (#lib::C2), _T (#lib::C3))
 t10 = _Call direct [#lib::bar] (x_0)
 RESULT: x_0
@@ -82,10 +82,10 @@
 t0 = _Call direct [#lib::C1::] (_T (#lib::C1))
 t1 = _Call direct [#lib::C2::] (_T (#lib::C2))
 t2* = _Call direct [#lib::foo] (_T (#lib::C2))
-t3 = _TypeCheck (t2 against dart.core::bool) (for #lib::foo(x = new #lib::C2::•()) as{TypeError} dart.core::bool*)
+t3 = _TypeCheck (t2 against dart.core::bool) (for #lib::foo(x = new #lib::C2::•()) as{TypeError,ForDynamic} dart.core::bool*)
 t4 = _Call direct [#lib::C3::] (_T (#lib::C3))
 t5* = _Call direct [#lib::foo] (_T (#lib::C3))
-t6 = _TypeCheck (t5 against dart.core::bool) (for #lib::foo(x = new #lib::C3::•()) as{TypeError} dart.core::bool*)
+t6 = _TypeCheck (t5 against dart.core::bool) (for #lib::foo(x = new #lib::C3::•()) as{TypeError,ForDynamic} dart.core::bool*)
 t7 = _Call direct [#lib::bar] (_T (#lib::C3))
 x_0 = _Join [dynamic] (_T (#lib::C2), _T (#lib::C3))
 RESULT: x_0
@@ -104,7 +104,7 @@
 RESULT: _T {}?
 ------------ #lib::if6b ------------
 %x = _Parameter #0 [_T ANY?]
-t1 = _TypeCheck (%x against dart.core::bool) (for x as{TypeError} dart.core::bool*)
+t1 = _TypeCheck (%x against dart.core::bool) (for x as{TypeError,ForDynamic} dart.core::bool*)
 t2 = _Call direct [#lib::foo] (_T (dart.core::bool, true))
 t3 = _Call direct [#lib::bar] (_T (dart.core::bool, false))
 x_0 = _Join [dynamic] (_T (dart.core::bool, true), _T (dart.core::bool, false))
@@ -138,7 +138,7 @@
 t2 = _Call direct [#lib::C1::] (_T (#lib::C1))
 t3 = _Call direct [#lib::C2::] (_T (#lib::C2))
 t4* = _Call direct [#lib::foo] (_T (#lib::C2))
-t5 = _TypeCheck (t4 against dart.core::bool) (for #lib::foo(x = new #lib::C2::•()) as{TypeError} dart.core::bool*)
+t5 = _TypeCheck (t4 against dart.core::bool) (for #lib::foo(x = new #lib::C2::•()) as{TypeError,ForDynamic} dart.core::bool*)
 t6 = _Call direct [#lib::C3::] (_T (#lib::C3))
 t7 = _Call direct [#lib::C4::] (_T (#lib::C4))
 x_0 = _Join [dynamic] (_T (#lib::C3), _T (#lib::C4))
@@ -153,20 +153,19 @@
 t2 = _Call direct [#lib::C1::] (_T (#lib::C1))
 t3 = _Call direct [#lib::C2::] (_T (#lib::C2))
 t4* = _Call direct [#lib::foo] (_T (#lib::C2))
-t5 = _TypeCheck (t4 against dart.core::bool) (for #lib::foo(x = new #lib::C2::•()) as{TypeError} dart.core::bool*)
+t5 = _TypeCheck (t4 against dart.core::bool) (for #lib::foo(x = new #lib::C2::•()) as{TypeError,ForDynamic} dart.core::bool*)
 t6 = _Call direct [#lib::C3::] (_T (#lib::C3))
 t7 = _Call direct [#lib::C4::] (_T (#lib::C4))
 t8* = _Call direct [#lib::foo] (_T (dart.core::_GrowableList<#lib::C4>))
 t9 = _Call direct [#lib::foo] (_T (#lib::C3))
 t10 = _Join [dynamic] (_T (#lib::C3), t8)
-t11 = _Narrow (t10 to _T ANY?)
-t12 = _Call direct [#lib::bar] (t11)
+t11 = _Call direct [#lib::bar] (t10)
 RESULT: _T {}?
 ------------ #lib::loop1 ------------
 t0 = _Call direct [#lib::C1::] (_T (#lib::C1))
 x_0 = _Join [dynamic] (_T (#lib::C1), _T (#lib::C2))
 t2* = _Call direct [#lib::foo] (x_0)
-t3 = _TypeCheck (t2 against dart.core::bool) (for #lib::foo(x) as{TypeError} dart.core::bool*)
+t3 = _TypeCheck (t2 against dart.core::bool) (for #lib::foo(x) as{TypeError,ForDynamic} dart.core::bool*)
 t4 = _Call direct [#lib::C2::] (_T (#lib::C2))
 t5 = _Call direct [#lib::bar] (x_0)
 RESULT: x_0
@@ -178,13 +177,13 @@
 t4 = _Call direct [#lib::bar] (_T (#lib::C2))
 t5 = _Call direct [#lib::C3::] (_T (#lib::C3))
 t6* = _Call direct [#lib::bar] (_T (#lib::C3))
-t7 = _TypeCheck (t6 against dart.core::bool) (for #lib::bar(x = new #lib::C3::•()) as{TypeError} dart.core::bool*)
+t7 = _TypeCheck (t6 against dart.core::bool) (for #lib::bar(x = new #lib::C3::•()) as{TypeError,ForDynamic} dart.core::bool*)
 RESULT: _T (#lib::C3)
 ------------ #lib::loop3 ------------
 t0 = _Call direct [#lib::C1::] (_T (#lib::C1))
 t1 = _Call direct [#lib::C2::] (_T (#lib::C2))
 t2* = _Call direct [#lib::foo] (_T (#lib::C2))
-t3 = _TypeCheck (t2 against dart.core::bool) (for #lib::foo(x = new #lib::C2::•()) as{TypeError} dart.core::bool*)
+t3 = _TypeCheck (t2 against dart.core::bool) (for #lib::foo(x = new #lib::C2::•()) as{TypeError,ForDynamic} dart.core::bool*)
 t4 = _Call direct [#lib::C3::] (_T (#lib::C3))
 t5 = _Call direct [#lib::bar] (_T (#lib::C2))
 RESULT: _T (#lib::C2)
@@ -195,19 +194,20 @@
 t3* = _Call direct [dart._internal::unsafeCast] (_T (dart.core::_GrowableList<dynamic>))
 t4* = _Call get [dart.core::Iterable::iterator] (t3)
 t5* = _Call [dart.core::Iterator::moveNext] (t4)
-t6 = _Call get [dart.core::Iterator::current] (t4)
+t6 = _Narrow (t4 to _T ANY)
+t7 = _Call get [dart.core::Iterator::current] (t6)
 x_0 = _Join [dynamic] (_T (#lib::C2), _T (#lib::C3))
-t8 = _Call direct [#lib::foo] (x_0)
-t9 = _Call direct [#lib::C3::] (_T (#lib::C3))
+t9 = _Call direct [#lib::foo] (x_0)
+t10 = _Call direct [#lib::C3::] (_T (#lib::C3))
 RESULT: x_0
 ------------ #lib::loop5 ------------
 t0 = _Call direct [#lib::C1::] (_T (#lib::C1))
 x_0 = _Join [dynamic] (_T (#lib::C1), _T (#lib::C3))
 t2* = _Call direct [#lib::foo] (x_0)
-t3 = _TypeCheck (t2 against dart.core::bool) (for #lib::foo(x) as{TypeError} dart.core::bool*)
+t3 = _TypeCheck (t2 against dart.core::bool) (for #lib::foo(x) as{TypeError,ForDynamic} dart.core::bool*)
 t4 = _Call direct [#lib::C2::] (_T (#lib::C2))
 t5* = _Call direct [#lib::bar] (_T (#lib::C2))
-t6 = _TypeCheck (t5 against dart.core::bool) (for #lib::bar(x) as{TypeError} dart.core::bool*)
+t6 = _TypeCheck (t5 against dart.core::bool) (for #lib::bar(x) as{TypeError,ForDynamic} dart.core::bool*)
 t7 = _Call direct [#lib::C3::] (_T (#lib::C3))
 x_1 = _Join [dynamic] (x_0, _T (#lib::C2))
 RESULT: x_1
@@ -216,10 +216,10 @@
 x_1 = _Join [dynamic] (_T (#lib::C3), _T (#lib::C2))
 x_0 = _Join [dynamic] (_T (#lib::C1), x_1)
 t3* = _Call direct [#lib::foo] (x_0)
-t4 = _TypeCheck (t3 against dart.core::bool) (for #lib::foo(x) as{TypeError} dart.core::bool*)
+t4 = _TypeCheck (t3 against dart.core::bool) (for #lib::foo(x) as{TypeError,ForDynamic} dart.core::bool*)
 t5 = _Call direct [#lib::C2::] (_T (#lib::C2))
 t6* = _Call direct [#lib::bar] (_T (#lib::C2))
-t7 = _TypeCheck (t6 against dart.core::bool) (for #lib::bar(x) as{TypeError} dart.core::bool*)
+t7 = _TypeCheck (t6 against dart.core::bool) (for #lib::bar(x) as{TypeError,ForDynamic} dart.core::bool*)
 t8 = _Call direct [#lib::C3::] (_T (#lib::C3))
 RESULT: x_0
 ------------ #lib::try1 ------------
@@ -270,6 +270,12 @@
 t5 = _Call direct [#lib::C3::] (_T (#lib::C3))
 x_2 = _Join [dynamic] (_T (#lib::C1), _T (#lib::C3))
 RESULT: x_2
+------------ #lib::cast1 ------------
+%x = _Parameter #0 [_T ANY?]
+t1 = _TypeCheck (%x against #lib::C1) (for x as #lib::C1*)
+t2 = _Call direct [#lib::foo] (t1)
+t3 = _Call direct [#lib::bar] (t1)
+RESULT: _T {}?
 ------------ #lib::main ------------
 
 RESULT: _T {}?
diff --git a/pkg/vm/testcases/transformations/type_flow/summary_collector/vars.dart.expect b/pkg/vm/testcases/transformations/type_flow/summary_collector/vars.dart.expect
index c85e5b1..2aff27c 100644
--- a/pkg/vm/testcases/transformations/type_flow/summary_collector/vars.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/summary_collector/vars.dart.expect
@@ -34,7 +34,7 @@
 RESULT: %a2
 ------------ #lib::loop2 ------------
 %x = _Parameter #0 [_T (dart.core::int)+?]
-t1* = _Call [dart.core::num::+] (_T (dart.core::int)+?, _T (dart.core::_Smi, 1))
+t1* = _Call [dart.core::num::+] (_T (dart.core::int)+, _T (dart.core::_Smi, 1))
 i_0 = _Join [dart.core::int*] (_T (dart.core::_Smi, 0), t1)
 t3* = _Call [dart.core::num::<] (i_0, _T (dart.core::_Smi, 5))
 t4* = _Call [dart.core::num::+] (_T (dart.core::int)+?, _T (dart.core::_Smi, 10))
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/bench_is_prime.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/bench_is_prime.dart.expect
index dae1516..d79868a 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/bench_is_prime.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/bench_is_prime.dart.expect
@@ -6,7 +6,7 @@
 static method isPrime([@vm.inferred-type.metadata=int] dynamic n) → core::bool* {
   if(_in::unsafeCast<core::bool*>([@vm.direct-call.metadata=dart.core::_IntegerImplementation::<] [@vm.inferred-type.metadata=dart.core::bool] n.<(2)))
     return false;
-  for (core::int* i = 2; [@vm.direct-call.metadata=dart.core::_IntegerImplementation::<=] [@vm.inferred-type.metadata=dart.core::bool (skip check)] [@vm.direct-call.metadata=dart.core::_IntegerImplementation::*] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::*}(i).{core::num::<=}(_in::unsafeCast<core::num*>(n)); i = [@vm.direct-call.metadata=dart.core::_IntegerImplementation::+??] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::+}(1)) {
+  for (core::int* i = 2; [@vm.direct-call.metadata=dart.core::_IntegerImplementation::<=] [@vm.inferred-type.metadata=dart.core::bool (skip check)] [@vm.direct-call.metadata=dart.core::_IntegerImplementation::*] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::*}(i).{core::num::<=}(_in::unsafeCast<core::num*>(n)); i = [@vm.direct-call.metadata=dart.core::_IntegerImplementation::+] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::+}(1)) {
     if([@vm.direct-call.metadata=dart.core::_IntegerImplementation::==] [@vm.inferred-type.metadata=dart.core::bool (skip check)] [@vm.direct-call.metadata=dart.core::_IntegerImplementation::%] [@vm.inferred-type.metadata=int] n.%(i).{core::Object::==}(0))
       return false;
   }
@@ -31,7 +31,7 @@
 }
 static method main(core::List<core::String*>* args) → dynamic {
   core::Stopwatch* timer = let final core::Stopwatch* #t1 = new core::Stopwatch::•() in let final void #t2 = [@vm.direct-call.metadata=dart.core::Stopwatch::start] [@vm.inferred-type.metadata=!? (skip check)] #t1.{core::Stopwatch::start}() in #t1;
-  for (core::int* i = 0; [@vm.direct-call.metadata=dart.core::_IntegerImplementation::<] [@vm.inferred-type.metadata=dart.core::bool (skip check)] i.{core::num::<}(100); i = [@vm.direct-call.metadata=dart.core::_IntegerImplementation::+??] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::+}(1)) {
+  for (core::int* i = 0; [@vm.direct-call.metadata=dart.core::_IntegerImplementation::<] [@vm.inferred-type.metadata=dart.core::bool (skip check)] i.{core::num::<}(100); i = [@vm.direct-call.metadata=dart.core::_IntegerImplementation::+] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::+}(1)) {
     self::run();
   }
   [@vm.direct-call.metadata=dart.core::Stopwatch::stop] [@vm.inferred-type.metadata=!? (skip check)] timer.{core::Stopwatch::stop}();
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/bench_vector.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/bench_vector.dart.expect
index 6efba39..f7c22d7 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/bench_vector.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/bench_vector.dart.expect
@@ -19,7 +19,7 @@
   }
 [@vm.procedure-attributes.metadata=hasDynamicUses:false,hasThisUses:false,hasTearOffUses:false]  operator *([@vm.inferred-type.metadata=#lib::_Vector?] self::_Vector* a) → core::double* {
     core::double* result = 0.0;
-    for (core::int* i = 0; [@vm.direct-call.metadata=dart.core::_IntegerImplementation::<] [@vm.inferred-type.metadata=dart.core::bool (skip check)] i.{core::num::<}([@vm.direct-call.metadata=#lib::_Vector::_length] [@vm.inferred-type.metadata=dart.core::_Smi (value: 10)] this.{self::_Vector::_length}); i = [@vm.direct-call.metadata=dart.core::_IntegerImplementation::+??] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::+}(1))
+    for (core::int* i = 0; [@vm.direct-call.metadata=dart.core::_IntegerImplementation::<] [@vm.inferred-type.metadata=dart.core::bool (skip check)] i.{core::num::<}([@vm.direct-call.metadata=#lib::_Vector::_length] [@vm.inferred-type.metadata=dart.core::_Smi (value: 10)] this.{self::_Vector::_length}); i = [@vm.direct-call.metadata=dart.core::_IntegerImplementation::+] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::+}(1))
       result = [@vm.direct-call.metadata=dart.core::_Double::+??] [@vm.inferred-type.metadata=dart.core::_Double (skip check)] result.{core::double::+}([@vm.direct-call.metadata=dart.core::_Double::*] [@vm.inferred-type.metadata=dart.core::_Double (skip check)] [@vm.direct-call.metadata=#lib::_Vector::[]] [@vm.inferred-type.metadata=dart.core::_Double (skip check)] this.{self::_Vector::[]}(i).{core::double::*}([@vm.direct-call.metadata=#lib::_Vector::[]??] [@vm.inferred-type.metadata=dart.core::_Double (skip check)] a.{self::_Vector::[]}(i)));
     return result;
   }
@@ -28,7 +28,7 @@
 [@vm.inferred-type.metadata=dart.core::_Double?]static field core::double* x = 0.0;
 static method main(core::List<core::String*>* args) → dynamic {
   core::Stopwatch* timer = let final core::Stopwatch* #t4 = new core::Stopwatch::•() in let final void #t5 = [@vm.direct-call.metadata=dart.core::Stopwatch::start] [@vm.inferred-type.metadata=!? (skip check)] #t4.{core::Stopwatch::start}() in #t4;
-  for (core::int* i = 0; [@vm.direct-call.metadata=dart.core::_IntegerImplementation::<] [@vm.inferred-type.metadata=dart.core::bool (skip check)] i.{core::num::<}(100000000); i = [@vm.direct-call.metadata=dart.core::_IntegerImplementation::+??] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::+}(1)) {
+  for (core::int* i = 0; [@vm.direct-call.metadata=dart.core::_IntegerImplementation::<] [@vm.inferred-type.metadata=dart.core::bool (skip check)] i.{core::num::<}(100000000); i = [@vm.direct-call.metadata=dart.core::_IntegerImplementation::+] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::+}(1)) {
     self::x = [@vm.direct-call.metadata=dart.core::_Double::+??] [@vm.inferred-type.metadata=dart.core::_Double (skip check)] [@vm.inferred-type.metadata=dart.core::_Double?] self::x.{core::double::+}([@vm.direct-call.metadata=#lib::_Vector::*??] [@vm.inferred-type.metadata=dart.core::_Double (skip check)] [@vm.inferred-type.metadata=#lib::_Vector?] self::v.{self::_Vector::*}([@vm.inferred-type.metadata=#lib::_Vector?] self::v));
   }
   [@vm.direct-call.metadata=dart.core::Stopwatch::stop] [@vm.inferred-type.metadata=!? (skip check)] timer.{core::Stopwatch::stop}();
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/future_or.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/future_or.dart.expect
index 2e9bc45..d7385b2 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/future_or.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/future_or.dart.expect
@@ -40,5 +40,5 @@
   return [@vm.call-site-attributes.metadata=receiverType:dart.core::Function*] self::unknown.call();
 static method main(core::List<core::String*>* args) → dynamic {
   self::foo1([@vm.inferred-type.metadata=dart.async::_Future<#lib::B*>] asy::Future::value<self::B*>(new self::B::•()), new self::B::•(), [@vm.inferred-type.metadata=dart.async::_Future<#lib::B*>] asy::Future::value<self::B*>(new self::B::•()), new self::B::•());
-  self::foo2(self::getDynamic() as{TypeError} asy::Future<self::A*>*, self::getDynamic() as{TypeError} self::A*, self::getDynamic() as{TypeError} asy::FutureOr<self::A*>*, self::getDynamic() as{TypeError} asy::FutureOr<self::A*>*);
+  self::foo2(self::getDynamic() as{TypeError,ForDynamic} asy::Future<self::A*>*, self::getDynamic() as{TypeError,ForDynamic} self::A*, self::getDynamic() as{TypeError,ForDynamic} asy::FutureOr<self::A*>*, self::getDynamic() as{TypeError,ForDynamic} asy::FutureOr<self::A*>*);
 }
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_field_initializer.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_field_initializer.dart.expect
index 21d4662..35e77bc 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_field_initializer.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_field_initializer.dart.expect
@@ -66,7 +66,7 @@
 static method getDynamic() → dynamic
   return [@vm.call-site-attributes.metadata=receiverType:dart.core::Function*] self::unknown.call();
 static method getValue() → core::Object* {
-  self::A* aa = self::getDynamic() as{TypeError} self::A*;
+  self::A* aa = self::getDynamic() as{TypeError,ForDynamic} self::A*;
   return [@vm.inferred-type.metadata=!] aa.{self::A::foo}();
 }
 static method use1([@vm.inferred-type.metadata=#lib::DeepCaller1] self::DeepCaller1* x) → dynamic
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_new_class1.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_new_class1.dart.expect
index 934ad1b..87ebd0c 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_new_class1.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_new_class1.dart.expect
@@ -38,7 +38,7 @@
   new self::B::•();
 }
 static method main(core::List<core::String*>* args) → dynamic {
-  self::use1(new self::Intermediate::•(), self::getDynamic() as{TypeError} self::A*);
+  self::use1(new self::Intermediate::•(), self::getDynamic() as{TypeError,ForDynamic} self::A*);
   self::allocateB();
-  self::use2(new self::Intermediate::•(), self::getDynamic() as{TypeError} self::A*);
+  self::use2(new self::Intermediate::•(), self::getDynamic() as{TypeError,ForDynamic} self::A*);
 }
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_new_class2.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_new_class2.dart.expect
index 7c66149..caa602a 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_new_class2.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_new_class2.dart.expect
@@ -67,9 +67,9 @@
   new self::E::•();
 }
 static method main(core::List<core::String*>* args) → dynamic {
-  self::use1(new self::Intermediate::•(), self::getDynamic() as{TypeError} self::A*);
+  self::use1(new self::Intermediate::•(), self::getDynamic() as{TypeError,ForDynamic} self::A*);
   self::allocateB();
-  self::use2(new self::Intermediate::•(), self::getDynamic() as{TypeError} self::A*);
+  self::use2(new self::Intermediate::•(), self::getDynamic() as{TypeError,ForDynamic} self::A*);
   self::allocateE();
-  self::use3(new self::Intermediate::•(), self::getDynamic() as{TypeError} self::A*);
+  self::use3(new self::Intermediate::•(), self::getDynamic() as{TypeError,ForDynamic} self::A*);
 }
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_set_field.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_set_field.dart.expect
index cd59c76..ccedd89 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_set_field.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/invalidation_set_field.dart.expect
@@ -59,7 +59,7 @@
   new self::A::•();
   new self::T1::•();
   new self::T2::•();
-  self::use1(new self::DeepCaller1::•(), self::getDynamic() as{TypeError} self::A*);
-  self::use2(new self::DeepCaller2::•(), self::getDynamic() as{TypeError} self::A*);
+  self::use1(new self::DeepCaller1::•(), self::getDynamic() as{TypeError,ForDynamic} self::A*);
+  self::use2(new self::DeepCaller2::•(), self::getDynamic() as{TypeError,ForDynamic} self::A*);
   self::setField2(new self::A::•(), new self::T2::•());
 }
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/no_such_method.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/no_such_method.dart.expect
index 062ebf9..4425a1c 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/no_such_method.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/no_such_method.dart.expect
@@ -123,7 +123,7 @@
   core::print([@vm.direct-call.metadata=#lib::D::bar??] [@vm.inferred-type.metadata=#lib::T2] [@vm.inferred-type.metadata=#lib::D?] self::dd.{self::A::bar});
   core::print([@vm.direct-call.metadata=#lib::D::bazz??] [@vm.inferred-type.metadata=#lib::T2 (skip check)] [@vm.inferred-type.metadata=#lib::D?] self::dd.{self::A::bazz}(1, 2, 3, 4));
   new self::E::•();
-  self::A* xx = self::getDynamic() as{TypeError} self::A*;
+  self::A* xx = self::getDynamic() as{TypeError,ForDynamic} self::A*;
   core::print([@vm.inferred-type.metadata=!] xx.{self::A::bar});
   dynamic yy = self::getDynamic();
   core::print([@vm.inferred-type.metadata=!] yy.twoArg(1, 2, 3));
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/param_types_before_strong_mode_checks.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/param_types_before_strong_mode_checks.dart.expect
index 9fbf8c0..8b68037 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/param_types_before_strong_mode_checks.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/param_types_before_strong_mode_checks.dart.expect
@@ -53,10 +53,10 @@
 static method use(dynamic x) → dynamic
   return [@vm.call-site-attributes.metadata=receiverType:dart.core::Function*] self::unknown.call(x);
 static method main(core::List<core::String*>* args) → dynamic {
-  self::func1(self::getDynamic() as{TypeError} self::T0*);
+  self::func1(self::getDynamic() as{TypeError,ForDynamic} self::T0*);
   self::use(#C1);
   self::use(new self::A::•().{self::A::method1});
-  self::B* bb = self::getDynamic() as{TypeError} self::B*;
+  self::B* bb = self::getDynamic() as{TypeError,ForDynamic} self::B*;
   [@vm.direct-call.metadata=#lib::C::method2??] [@vm.inferred-type.metadata=!? (skip check)] bb.{self::B::method2}(self::getDynamic());
   self::getDynamic().method3(self::getDynamic());
   new self::T2::•();
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/tear_off_dynamic_method.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/tear_off_dynamic_method.dart.expect
index 44110b0..02808ea 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/tear_off_dynamic_method.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/tear_off_dynamic_method.dart.expect
@@ -12,7 +12,7 @@
     : super self::A::•()
     ;
 [@vm.procedure-attributes.metadata=hasThisUses:false]  method foo() → core::int*
-    return [@vm.direct-call.metadata=dart.core::_IntegerImplementation::+] [@vm.inferred-type.metadata=! (skip check)] 1.{core::num::+}([@vm.direct-call.metadata=#lib::B::foo] [@vm.inferred-type.metadata=!? (receiver not int)] [@vm.inferred-type.metadata=#lib::B] self::knownResult().foo() as{TypeError} core::num*) as{TypeError} core::int*;
+    return [@vm.direct-call.metadata=dart.core::_IntegerImplementation::+] [@vm.inferred-type.metadata=! (skip check)] 1.{core::num::+}([@vm.direct-call.metadata=#lib::B::foo] [@vm.inferred-type.metadata=!? (receiver not int)] [@vm.inferred-type.metadata=#lib::B] self::knownResult().foo() as{TypeError,ForDynamic} core::num*) as{TypeError} core::int*;
 }
 class TearOffDynamicMethod extends core::Object {
 [@vm.procedure-attributes.metadata=hasDynamicUses:false,hasThisUses:false,hasNonThisUses:false,hasTearOffUses:false]  field dynamic bazz;
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/tear_off_super_method.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/tear_off_super_method.dart.expect
index b2c15f7..73eb1d5 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/tear_off_super_method.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/tear_off_super_method.dart.expect
@@ -23,7 +23,7 @@
 [@vm.procedure-attributes.metadata=hasDynamicUses:false,hasThisUses:false,hasNonThisUses:false]  method foo() → core::int*
     return _in::unsafeCast<core::int*>([@vm.direct-call.metadata=dart.core::_IntegerImplementation::+] [@vm.inferred-type.metadata=int (skip check)] 3.{core::num::+}(_in::unsafeCast<core::num*>([@vm.direct-call.metadata=#lib::B::foo] [@vm.inferred-type.metadata=int? (receiver not int)] [@vm.inferred-type.metadata=#lib::B] self::knownResult().foo())));
 [@vm.procedure-attributes.metadata=hasDynamicUses:false,hasNonThisUses:false,hasTearOffUses:false]  method doCall(dynamic x) → core::int*
-    return [@vm.call-site-attributes.metadata=receiverType:dynamic] x.call() as{TypeError} core::int*;
+    return [@vm.call-site-attributes.metadata=receiverType:dynamic] x.call() as{TypeError,ForDynamic} core::int*;
 }
 class TearOffSuperMethod extends self::Base {
   synthetic constructor •() → self::TearOffSuperMethod*
diff --git a/runtime/BUILD.gn b/runtime/BUILD.gn
index f07fdc6..a5bdc9c 100644
--- a/runtime/BUILD.gn
+++ b/runtime/BUILD.gn
@@ -140,6 +140,10 @@
     }
   }
 
+  if (use_nnbd) {
+    defines += [ "DART_BUILT_WITH_NNBD_FLAG" ]
+  }
+
   if (!is_win) {
     cflags = [
       "-Werror",
diff --git a/runtime/bin/dart_embedder_api_impl.cc b/runtime/bin/dart_embedder_api_impl.cc
index 6af5d82..73974ea 100644
--- a/runtime/bin/dart_embedder_api_impl.cc
+++ b/runtime/bin/dart_embedder_api_impl.cc
@@ -90,7 +90,8 @@
   if (!bin::VmService::Setup(config.ip, config.port, config.dev_mode,
                              config.disable_auth_codes,
                              config.write_service_info_filename,
-                             /*trace_loading=*/false, config.deterministic)) {
+                             /*trace_loading=*/false, config.deterministic,
+                             /*enable_service_port_fallback=*/false)) {
     *error = strdup(bin::VmService::GetErrorMessage());
     return nullptr;
   }
@@ -124,7 +125,8 @@
   if (!bin::VmService::Setup(config.ip, config.port, config.dev_mode,
                              config.disable_auth_codes,
                              config.write_service_info_filename,
-                             /*trace_loading=*/false, config.deterministic)) {
+                             /*trace_loading=*/false, config.deterministic,
+                             /*enable_service_port_fallback=*/false)) {
     *error = strdup(bin::VmService::GetErrorMessage());
     return nullptr;
   }
diff --git a/runtime/bin/file.cc b/runtime/bin/file.cc
index a72d807..0ac8065 100644
--- a/runtime/bin/file.cc
+++ b/runtime/bin/file.cc
@@ -713,7 +713,11 @@
   ASSERT((fd == STDIN_FILENO) || (fd == STDOUT_FILENO) ||
          (fd == STDERR_FILENO));
   File::StdioHandleType type = File::GetStdioHandleType(static_cast<int>(fd));
-  Dart_SetIntegerReturnValue(args, type);
+  if (type == File::StdioHandleType::kTypeError) {
+    Dart_SetReturnValue(args, DartUtils::NewDartOSError());
+  } else {
+    Dart_SetIntegerReturnValue(args, type);
+  }
 }
 
 void FUNCTION_NAME(File_GetType)(Dart_NativeArguments args) {
diff --git a/runtime/bin/file.h b/runtime/bin/file.h
index c0ab0fb..4255ba8 100644
--- a/runtime/bin/file.h
+++ b/runtime/bin/file.h
@@ -74,11 +74,13 @@
   enum Identical { kIdentical = 0, kDifferent = 1, kError = 2 };
 
   enum StdioHandleType {
+    // These match the constants in stdio.dart.
     kTerminal = 0,
     kPipe = 1,
     kFile = 2,
     kSocket = 3,
-    kOther = 4
+    kOther = 4,
+    kTypeError = 5
   };
 
   enum FileStat {
diff --git a/runtime/bin/file_android.cc b/runtime/bin/file_android.cc
index 59abc84..c79c1e0 100644
--- a/runtime/bin/file_android.cc
+++ b/runtime/bin/file_android.cc
@@ -669,7 +669,7 @@
   struct stat buf;
   int result = fstat(fd, &buf);
   if (result == -1) {
-    return kOther;
+    return kTypeError;
   }
   if (S_ISCHR(buf.st_mode)) {
     return kTerminal;
diff --git a/runtime/bin/file_fuchsia.cc b/runtime/bin/file_fuchsia.cc
index 98b6537..9445de6 100644
--- a/runtime/bin/file_fuchsia.cc
+++ b/runtime/bin/file_fuchsia.cc
@@ -622,7 +622,7 @@
     // fstat() on fds 0, 1, 2 on Fuchsia return -1 with errno ENOTSUP,
     // but if they are opened, then we can read/write them, so pretend they
     // are kPipe.
-    return ((errno == ENOTSUP) && fd_is_valid(fd)) ? kPipe : kOther;
+    return ((errno == ENOTSUP) && fd_is_valid(fd)) ? kPipe : kTypeError;
   }
   if (S_ISCHR(buf.st_mode)) {
     return kTerminal;
diff --git a/runtime/bin/file_linux.cc b/runtime/bin/file_linux.cc
index c012f8a..bd2f020 100644
--- a/runtime/bin/file_linux.cc
+++ b/runtime/bin/file_linux.cc
@@ -666,7 +666,7 @@
   struct stat64 buf;
   int result = TEMP_FAILURE_RETRY(fstat64(fd, &buf));
   if (result == -1) {
-    return kOther;
+    return kTypeError;
   }
   if (S_ISCHR(buf.st_mode)) {
     return kTerminal;
diff --git a/runtime/bin/file_macos.cc b/runtime/bin/file_macos.cc
index 456023c..25af65b9 100644
--- a/runtime/bin/file_macos.cc
+++ b/runtime/bin/file_macos.cc
@@ -585,7 +585,7 @@
   struct stat buf;
   int result = fstat(fd, &buf);
   if (result == -1) {
-    return kOther;
+    return kTypeError;
   }
   if (S_ISCHR(buf.st_mode)) {
     return kTerminal;
diff --git a/runtime/bin/main.cc b/runtime/bin/main.cc
index bd2df32..b98754b 100644
--- a/runtime/bin/main.cc
+++ b/runtime/bin/main.cc
@@ -565,7 +565,7 @@
           Options::vm_service_server_ip(), Options::vm_service_server_port(),
           Options::vm_service_dev_mode(), Options::vm_service_auth_disabled(),
           Options::vm_write_service_info_filename(), Options::trace_loading(),
-          Options::deterministic())) {
+          Options::deterministic(), Options::enable_service_port_fallback())) {
     *error = strdup(VmService::GetErrorMessage());
     return NULL;
   }
diff --git a/runtime/bin/main_options.cc b/runtime/bin/main_options.cc
index 05fbb2c..9eaf8c4 100644
--- a/runtime/bin/main_options.cc
+++ b/runtime/bin/main_options.cc
@@ -212,6 +212,10 @@
 "  so it is not recommended to disable them unless behind a firewall on a\n"
 "  secure device.\n"
 "\n"
+"--enable-service-port-fallback\n"
+"  When the VM service is told to bind to a particular port, fallback to 0 if\n"
+"  it fails to bind instead of failing to start.\n"
+"\n"
 "--root-certs-file=<path>\n"
 "  The path to a file containing the trusted root certificates to use for\n"
 "  secure socket connections.\n"
diff --git a/runtime/bin/main_options.h b/runtime/bin/main_options.h
index db7c0b7..3fe9f74 100644
--- a/runtime/bin/main_options.h
+++ b/runtime/bin/main_options.h
@@ -45,7 +45,8 @@
   V(short_socket_write, short_socket_write)                                    \
   V(disable_exit, exit_disabled)                                               \
   V(preview_dart_2, nop_option)                                                \
-  V(suppress_core_dump, suppress_core_dump)
+  V(suppress_core_dump, suppress_core_dump)                                    \
+  V(enable_service_port_fallback, enable_service_port_fallback)
 
 // Boolean flags that have a short form.
 #define SHORT_BOOL_OPTIONS_LIST(V)                                             \
diff --git a/runtime/bin/run_vm_tests.cc b/runtime/bin/run_vm_tests.cc
index 86c17f8..e99cd4e 100644
--- a/runtime/bin/run_vm_tests.cc
+++ b/runtime/bin/run_vm_tests.cc
@@ -148,7 +148,8 @@
   if (!bin::VmService::Setup("127.0.0.1", 0,
                              /*dev_mode=*/false, /*auth_disabled=*/true,
                              /*write_service_info_filename*/ "",
-                             /*trace_loading=*/false, /*deterministic=*/true)) {
+                             /*trace_loading=*/false, /*deterministic=*/true,
+                             /*enable_service_port_fallback=*/false)) {
     *error = strdup(bin::VmService::GetErrorMessage());
     return nullptr;
   }
diff --git a/runtime/bin/vmservice_impl.cc b/runtime/bin/vmservice_impl.cc
index 4c9c9a9..a3f4b00 100644
--- a/runtime/bin/vmservice_impl.cc
+++ b/runtime/bin/vmservice_impl.cc
@@ -116,7 +116,8 @@
                       bool auth_codes_disabled,
                       const char* write_service_info_filename,
                       bool trace_loading,
-                      bool deterministic) {
+                      bool deterministic,
+                      bool enable_service_port_fallback) {
   Dart_Isolate isolate = Dart_CurrentIsolate();
   ASSERT(isolate != NULL);
   SetServerAddress("");
@@ -177,6 +178,11 @@
                          Dart_NewBoolean(auth_codes_disabled));
   SHUTDOWN_ON_ERROR(result);
 
+  result =
+      Dart_SetField(library, DartUtils::NewString("_enableServicePortFallback"),
+                    Dart_NewBoolean(enable_service_port_fallback));
+  SHUTDOWN_ON_ERROR(result);
+
   if (write_service_info_filename != nullptr) {
     result = DartUtils::SetStringField(library, "_serviceInfoFilename",
                                        write_service_info_filename);
diff --git a/runtime/bin/vmservice_impl.h b/runtime/bin/vmservice_impl.h
index 17ec55a..4b5838b 100644
--- a/runtime/bin/vmservice_impl.h
+++ b/runtime/bin/vmservice_impl.h
@@ -20,7 +20,8 @@
                     bool auth_codes_disabled,
                     const char* write_service_info_filename,
                     bool trace_loading,
-                    bool deterministic);
+                    bool deterministic,
+                    bool enable_service_port_fallback);
 
   static void SetNativeResolver();
 
diff --git a/runtime/include/dart_api.h b/runtime/include/dart_api.h
index 6b5ccdf..c736f39 100644
--- a/runtime/include/dart_api.h
+++ b/runtime/include/dart_api.h
@@ -3211,6 +3211,27 @@
 DART_EXPORT bool Dart_IsKernelIsolate(Dart_Isolate isolate);
 DART_EXPORT bool Dart_KernelIsolateIsRunning();
 DART_EXPORT Dart_Port Dart_KernelPort();
+
+/**
+ * Compiles the given `script_uri` to a kernel file.
+ *
+ * \param platform_kernel A buffer containing the kernel of the platform (e.g.
+ * `vm_platform_strong.dill`). The VM does not take ownership of this memory.
+ *
+ * \param platform_kernel_size The length of the platform_kernel buffer.
+ *
+ * \return Returns the result of the compilation.
+ *
+ * On a successful compilation the returned [Dart_KernelCompilationResult] has
+ * a status of [Dart_KernelCompilationStatus_Ok] and the `kernel`/`kernel_size`
+ * fields are set. The caller takes ownership of the malloc()ed buffer.
+ *
+ * On a failed compilation the `error` might be set describing the reason for
+ * the failed compilation. The caller takes ownership of the malloc()ed
+ * error.
+ *
+ * Requires there to be a current isolate.
+ */
 DART_EXPORT Dart_KernelCompilationResult
 Dart_CompileToKernel(const char* script_uri,
                      const uint8_t* platform_kernel,
diff --git a/runtime/observatory/bin/heap_snapshot.dart b/runtime/observatory/bin/heap_snapshot.dart
index 6b7c0a7..ca0761a 100644
--- a/runtime/observatory/bin/heap_snapshot.dart
+++ b/runtime/observatory/bin/heap_snapshot.dart
@@ -2,8 +2,9 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// A way to test heap snapshot loading and analysis outside of Observatory.
-// Output is too noisy to be useful.
+// A way to test heap snapshot loading and analysis outside of Observatory, and
+// to handle snapshots that require more memory to analyze than is available in
+// a web browser.
 
 import 'dart:async';
 import 'dart:convert';
@@ -73,35 +74,355 @@
   return reader.done;
 }
 
-String size(SnapshotMergedDominator object) {
-  int s = object.retainedSize;
-  if (s < 1024) return '${s}B';
-  s = s ~/ 1024;
-  if (s < 1024) return '${s}kB';
-  s = s ~/ 1024;
-  if (s < 1024) return '${s}MB';
-  s = s ~/ 1024;
-  if (s < 1024) return '${s}GB';
-  s = s ~/ 1024;
-  return '${s}TB';
+String makeJson(root) {
+  // 'root' can be arbitrarily deep, so we need to use an explicit stack
+  // instead of the call stack. We also must avoid using a JSON expression to
+  // avoid stack overflow in the JS engine parser.
+  final ids = new Map<dynamic, int>();
+  final sb = new StringBuffer();
+  final worklist = new List<dynamic>();
+  worklist.add(root);
+
+  var id = 0;
+  while (id < worklist.length) {
+    var object = worklist[id];
+    ids[object] = id++;
+    worklist.addAll(object.children);
+  }
+
+  while (!worklist.isEmpty) {
+    var object = worklist.removeLast();
+    var id = ids[object];
+
+    sb.write('var node');
+    sb.write(id.toString());
+    sb.write(' = {"name":"');
+    sb.write(object.description);
+    sb.write('","type":"');
+    sb.write(object.klass.name);
+    sb.write('","size":');
+    sb.write(object.retainedSize.toString());
+    sb.write(',"children":[');
+
+    bool first = true;
+    for (var child in object.children) {
+      if (!first) {
+        sb.write(',');
+      }
+      first = false;
+      sb.write('node');
+      sb.write(ids[child].toString());
+    }
+
+    sb.write(']};\n');
+  }
+
+  return sb.toString();
 }
 
-void display(SnapshotMergedDominator object, int depth) {
-  if (object.retainedSize < 4096) return;
+var css = '''
+.treemapTile {
+    position: absolute;
+    box-sizing: border-box;
+    border: solid 1px;
+    font-size: 10;
+    text-align: center;
+    overflow: hidden;
+    white-space: nowrap;
+    cursor: default;
+}
+''';
 
-  var line = (' ' * (4 * depth)) + '[${size(object)}] ${object.description}';
-  print(line);
+var js = '''
+function hash(string) {
+  // Jenkin's one_at_a_time.
+  let h = string.length;
+  for (let i = 0; i < string.length; i++) {
+    h += string.charCodeAt(i);
+    h += h << 10;
+    h ^= h >> 6;
+  }
+  h += h << 3;
+  h ^= h >> 11;
+  h += h << 15;
+  return h;
+}
 
-  if (depth > 4) return;
+function color(string) {
+  let hue = hash(string) % 360;
+  return "hsl(" + hue + ",60%,60%)";
+}
 
-  var children = new List.from(object.children);
-  children.sort((a, b) => b.retainedSize - a.retainedSize);
-  for (var c in children) {
-    display(c, depth + 1);
+function prettySize(size) {
+  if (size < 1024) return size + "B";
+  size /= 1024;
+  if (size < 1024) return size.toFixed(1) + "KiB";
+  size /= 1024;
+  if (size < 1024) return size.toFixed(1) + "MiB";
+  size /= 1024;
+  return size.toFixed(1) + "GiB";
+}
+
+function prettyPercent(fraction) {
+  return (fraction * 100).toFixed(1);
+}
+
+function createTreemapTile(v, width, height, depth) {
+  let div = document.createElement("div");
+  div.className = "treemapTile";
+  div.style["background-color"] = color(v.type);
+  div.ondblclick = function(event) {
+    event.stopPropagation();
+    if (depth == 0) {
+      let dom = v.parent;
+      if (dom == undefined) {
+        // Already at root.
+      } else {
+        showDominatorTree(dom);  // Zoom out.
+      }
+    } else {
+      showDominatorTree(v);  // Zoom in.
+    }
+  };
+
+  let left = 0;
+  let top = 0;
+
+  const kPadding = 5;
+  const kBorder = 1;
+  left += kPadding - kBorder;
+  top += kPadding - kBorder;
+  width -= 2 * kPadding;
+  height -= 2 * kPadding;
+
+  let label = v.name + " [" + prettySize(v.size) + "]";
+  div.title = label;
+
+  if (width < 10 || height < 10) {
+    // Too small: don't render label or children.
+    return div;
+  }
+
+  div.appendChild(document.createTextNode(label));
+  const kLabelHeight = 9;
+  top += kLabelHeight;
+  height -= kLabelHeight;
+
+  if (depth > 2) {
+    // Too deep: don't render children.
+    return div;
+  }
+  if (width < 4 || height < 4) {
+    // Too small: don't render children.
+    return div;
+  }
+
+  let children = new Array();
+  v.children.forEach(function(c) {
+    // Size 0 children seem to confuse the layout algorithm (accumulating
+    // rounding errors?).
+    if (c.size > 0) {
+      children.push(c);
+    }
+  });
+  children.sort(function (a, b) {
+    return b.size - a.size;
+  });
+
+  const scale = width * height / v.size;
+
+  // Bruls M., Huizing K., van Wijk J.J. (2000) Squarified Treemaps. In: de
+  // Leeuw W.C., van Liere R. (eds) Data Visualization 2000. Eurographics.
+  // Springer, Vienna.
+  for (let rowStart = 0;  // Index of first child in the next row.
+       rowStart < children.length;) {
+    // Prefer wider rectangles, the better to fit text labels.
+    const GOLDEN_RATIO = 1.61803398875;
+    let verticalSplit = (width / height) > GOLDEN_RATIO;
+
+    let space;
+    if (verticalSplit) {
+      space = height;
+    } else {
+      space = width;
+    }
+
+    let rowMin = children[rowStart].size * scale;
+    let rowMax = rowMin;
+    let rowSum = 0;
+    let lastRatio = 0;
+
+    let rowEnd;  // One after index of last child in the next row.
+    for (rowEnd = rowStart; rowEnd < children.length; rowEnd++) {
+      let size = children[rowEnd].size * scale;
+      if (size < rowMin) rowMin = size;
+      if (size > rowMax) rowMax = size;
+      rowSum += size;
+
+      let ratio = Math.max((space * space * rowMax) / (rowSum * rowSum),
+                           (rowSum * rowSum) / (space * space * rowMin));
+      if ((lastRatio != 0) && (ratio > lastRatio)) {
+        // Adding the next child makes the aspect ratios worse: remove it and
+        // add the row.
+        rowSum -= size;
+        break;
+      }
+      lastRatio = ratio;
+    }
+
+    let rowLeft = left;
+    let rowTop = top;
+    let rowSpace = rowSum / space;
+
+    for (let i = rowStart; i < rowEnd; i++) {
+      let child = children[i];
+      let size = child.size * scale;
+
+      let childWidth;
+      let childHeight;
+      if (verticalSplit) {
+        childWidth = rowSpace;
+        childHeight = size / childWidth;
+      } else {
+        childHeight = rowSpace;
+        childWidth = size / childHeight;
+      }
+
+      let childDiv = createTreemapTile(child, childWidth, childHeight, depth + 1);
+      childDiv.style.left = rowLeft + "px";
+      childDiv.style.top = rowTop + "px";
+      // Oversize the final div by kBorder to make the borders overlap.
+      childDiv.style.width = (childWidth + kBorder) + "px";
+      childDiv.style.height = (childHeight + kBorder) + "px";
+      div.appendChild(childDiv);
+
+      if (verticalSplit)
+        rowTop += childHeight;
+      else
+        rowLeft += childWidth;
+    }
+
+    if (verticalSplit) {
+      left += rowSpace;
+      width -= rowSpace;
+    } else {
+      top += rowSpace;
+      height -= rowSpace;
+    }
+
+    rowStart = rowEnd;
+  }
+
+  return div;
+}
+
+function setBody(div) {
+  let body = document.body;
+  while (body.firstChild) {
+    body.removeChild(body.firstChild);
+  }
+  body.appendChild(div);
+}
+
+function showDominatorTree(v) {
+  let header = document.createElement("div");
+  header.textContent = "Dominator Tree";
+  header.title =
+    "Double click a box to zoom in.\\n" +
+    "Double click the outermost box to zoom out.";
+  header.className = "headerRow";
+  header.style["flex-grow"] = 0;
+  header.style["padding"] = "5px";
+  header.style["border-bottom"] = "solid 1px";
+
+  let content = document.createElement("div");
+  content.style["flex-basis"] = 0;
+  content.style["flex-grow"] = 1;
+
+  let column = document.createElement("div");
+  column.style["width"] = "100%";
+  column.style["height"] = "100%";
+  column.style["border"] = "solid 2px";
+  column.style["display"] = "flex";
+  column.style["flex-direction"] = "column";
+  column.appendChild(header);
+  column.appendChild(content);
+
+  setBody(column);
+
+  // Add the content div to the document first so the browser will calculate
+  // the available width and height.
+  let w = content.offsetWidth;
+  let h = content.offsetHeight;
+
+  let topTile = createTreemapTile(v, w, h, 0);
+  topTile.style.width = w;
+  topTile.style.height = h;
+  topTile.style.border = "none";
+  content.appendChild(topTile);
+}
+
+function linkParents(root) {
+  // 'root' can be arbitrarily deep, so we need to use an explicit stack
+  // instead of the call stack.
+  let worklist = new Array();
+  worklist.push(root);
+
+  while (worklist.length > 0) {
+    let node = worklist.pop();
+    node.children.forEach(function (child) {
+      child["parent"] = node;
+      worklist.push(child);
+    });
   }
 }
 
+var root = null;
+(function() {
+  __JSON__
+  root = node0;
+})();
+
+linkParents(root);
+showDominatorTree(root);
+''';
+
+var html = '''
+<html>
+  <head>
+    <title>Dart Heap Snapshot</title>
+    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
+    <style>$css</style>
+  </head>
+  <body>
+    <script>$js</script>
+  </body>
+</html>
+''';
+
 main(List<String> args) async {
-  final snapshot = await load(args[0]);
-  display(snapshot.mergedRoot, 0);
+  if (args.length < 1) {
+    print('Usage: heap_snapshot.dart <vm-service-uri>');
+    exitCode = 1;
+    return;
+  }
+
+  var uri = Uri.parse(args[0]);
+  if (uri.scheme == 'http') {
+    uri = uri.replace(scheme: 'ws');
+  } else if (uri.scheme == 'https') {
+    uri = uri.replace(scheme: 'wss');
+  }
+  if (!uri.path.endsWith('/ws')) {
+    uri = uri.resolve('ws');
+  }
+
+  final snapshot = await load(uri.toString());
+
+  final dir = await Directory.systemTemp.createTemp('heap-snapshot');
+  final path = dir.path + '/merged-dominator.html';
+  final file = await File(path).create();
+  final tree = makeJson(snapshot.mergedRoot);
+  await file.writeAsString(html.replaceAll('__JSON__', tree));
+  print('Wrote file://' + path);
 }
diff --git a/runtime/observatory/tests/service/dominator_tree_vm_with_double_field_test.dart b/runtime/observatory/tests/service/dominator_tree_vm_with_double_field_test.dart
new file mode 100644
index 0000000..9edaf23
--- /dev/null
+++ b/runtime/observatory/tests/service/dominator_tree_vm_with_double_field_test.dart
@@ -0,0 +1,151 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+// VMOptions=
+// VMOptions=--use_compactor
+// VMOptions=--use_compactor --force_evacuation
+
+import 'dart:typed_data';
+
+import 'package:observatory/service_io.dart';
+import 'package:unittest/unittest.dart';
+import 'test_helper.dart';
+
+double getDoubleWithHeapObjectTag() {
+  final bd = ByteData(8);
+  bd.setUint64(0, 0x8000000000000001, Endian.host);
+  final double v = bd.getFloat64(0, Endian.host);
+  return v;
+}
+
+// small example from [Lenguaer & Tarjan 1979]
+class R {
+  final double fld = getDoubleWithHeapObjectTag();
+  var x;
+  var y;
+  var z;
+}
+
+class A {
+  var x;
+}
+
+class B {
+  var x;
+  var y;
+  var z;
+}
+
+class C {
+  var x;
+  var y;
+}
+
+class D {
+  var x;
+}
+
+class E {
+  var x;
+}
+
+class F {
+  var x;
+}
+
+class G {
+  var x;
+  var y;
+}
+
+class H {
+  var x;
+  var y;
+}
+
+class I {
+  var x;
+}
+
+class J {
+  var x;
+}
+
+class K {
+  var x;
+  var y;
+}
+
+class L {
+  var x;
+}
+
+var r;
+
+buildGraph() {
+  r = new R();
+  var a = new A();
+  var b = new B();
+  var c = new C();
+  var d = new D();
+  var e = new E();
+  var f = new F();
+  var g = new G();
+  var h = new H();
+  var i = new I();
+  var j = new J();
+  var k = new K();
+  var l = new L();
+
+  r.x = a;
+  r.y = b;
+  r.z = c;
+  a.x = d;
+  b.x = a;
+  b.y = d;
+  b.z = e;
+  c.x = f;
+  c.y = g;
+  d.x = l;
+  e.x = h;
+  f.x = i;
+  g.x = i;
+  g.y = j;
+  h.x = e;
+  h.y = k;
+  i.x = k;
+  j.x = i;
+  k.x = i;
+  k.y = r;
+  l.x = h;
+
+  expect(r.fld, getDoubleWithHeapObjectTag());
+}
+
+var tests = <IsolateTest>[
+  (Isolate isolate) async {
+    final graph = await isolate.fetchHeapSnapshot().done;
+
+    node(String className) {
+      return graph.objects.singleWhere((v) => v.klass.name == className);
+    }
+
+    expect(node('I').parent, equals(node('R')));
+    expect(node('K').parent, equals(node('R')));
+    expect(node('C').parent, equals(node('R')));
+    expect(node('H').parent, equals(node('R')));
+    expect(node('E').parent, equals(node('R')));
+    expect(node('A').parent, equals(node('R')));
+    expect(node('D').parent, equals(node('R')));
+    expect(node('B').parent, equals(node('R')));
+
+    expect(node('F').parent, equals(node('C')));
+    expect(node('G').parent, equals(node('C')));
+    expect(node('J').parent, equals(node('G')));
+    expect(node('L').parent, equals(node('D')));
+
+    expect(node('R'), isNotNull); // The field.
+  },
+];
+
+main(args) => runIsolateTests(args, tests, testeeBefore: buildGraph);
diff --git a/runtime/observatory/tests/service/enable_service_port_fallback_positive_test.dart b/runtime/observatory/tests/service/enable_service_port_fallback_positive_test.dart
new file mode 100644
index 0000000..c2159eb
--- /dev/null
+++ b/runtime/observatory/tests/service/enable_service_port_fallback_positive_test.dart
@@ -0,0 +1,36 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:io';
+
+import 'package:observatory/service_io.dart';
+import 'package:unittest/unittest.dart';
+import 'test_helper.dart';
+
+// Tests that the --enable-service-port-fallback flag works correctly by trying to bind to
+// a port that is available.
+var tests = <VMTest>[
+  (VM vm) async {
+    // Correctly bound to provided port.
+    expect(Uri.parse(serviceHttpAddress).port == selectedPort, true);
+  }
+];
+
+int selectedPort = 0;
+
+main(args) async {
+  selectedPort = await _getUnusedPort();
+  await runVMTests(args, tests,
+      enable_service_port_fallback: true,
+      // Choose a port number that should always be open.
+      port: selectedPort,
+      extraArgs: []);
+}
+
+Future<int> _getUnusedPort() async {
+  var socket = await ServerSocket.bind(InternetAddress.anyIPv4, 0);
+  var port = socket.port;
+  await socket.close();
+  return port;
+}
diff --git a/runtime/observatory/tests/service/enable_service_port_fallback_test.dart b/runtime/observatory/tests/service/enable_service_port_fallback_test.dart
new file mode 100644
index 0000000..e5fdef0
--- /dev/null
+++ b/runtime/observatory/tests/service/enable_service_port_fallback_test.dart
@@ -0,0 +1,29 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:io';
+
+import 'package:observatory/service_io.dart';
+import 'package:unittest/unittest.dart';
+import 'test_helper.dart';
+
+// Tests that the --enable-service-port-fallback flag works correctly by trying to bind to
+// a port that is unsupported.
+var tests = <VMTest>[
+  (VM vm) async {
+    // Did not bind to provided port.
+    expect(Uri.parse(serviceHttpAddress).port != portNumber, true);
+    await socket.close();
+  }
+];
+
+ServerSocket socket;
+int portNumber = -1;
+
+main(args) async {
+  socket = await ServerSocket.bind(InternetAddress.loopbackIPv4, 0);
+  portNumber = socket.port;
+  return runVMTests(args, tests,
+      enable_service_port_fallback: true, port: portNumber, extraArgs: []);
+}
diff --git a/runtime/observatory/tests/service/get_object_rpc_test.dart b/runtime/observatory/tests/service/get_object_rpc_test.dart
index a19a869..7ebabac 100644
--- a/runtime/observatory/tests/service/get_object_rpc_test.dart
+++ b/runtime/observatory/tests/service/get_object_rpc_test.dart
@@ -762,7 +762,7 @@
     expect(result['name'], equals('_DummyClass'));
     expect(result['_vmName'], startsWith('_DummyClass@'));
     expect(result['abstract'], equals(false));
-    expect(result['const'], equals(false));
+    expect(result['const'], equals(true));
     expect(result['_finalized'], equals(true));
     expect(result['_implemented'], equals(false));
     expect(result['_patch'], equals(false));
diff --git a/runtime/observatory/tests/service/service.status b/runtime/observatory/tests/service/service.status
index f7857bc..4aa30d7 100644
--- a/runtime/observatory/tests/service/service.status
+++ b/runtime/observatory/tests/service/service.status
@@ -14,6 +14,11 @@
 [ $arch == arm ]
 process_service_test: Pass, Fail # Issue 24344
 
+# Test uses service API and relies on correct class names
+[ $builder_tag == obfuscated ]
+dominator_tree_vm_test: SkipByDesign
+dominator_tree_vm_with_double_field_test: SkipByDesign
+
 # Tests with known analyzer issues
 [ $compiler == dart2analyzer ]
 developer_extension_test: SkipByDesign
diff --git a/runtime/observatory/tests/service/test_helper.dart b/runtime/observatory/tests/service/test_helper.dart
index 745cba3..9060c00 100644
--- a/runtime/observatory/tests/service/test_helper.dart
+++ b/runtime/observatory/tests/service/test_helper.dart
@@ -105,8 +105,10 @@
       bool pause_on_start,
       bool pause_on_exit,
       bool pause_on_unhandled_exceptions,
+      bool enable_service_port_fallback,
       bool testeeControlsServer,
       Uri serviceInfoUri,
+      int port,
       List<String> extraArgs) {
     assert(pause_on_start != null);
     assert(pause_on_exit != null);
@@ -121,8 +123,10 @@
           pause_on_start,
           pause_on_exit,
           pause_on_unhandled_exceptions,
+          enable_service_port_fallback,
           testeeControlsServer,
           serviceInfoUri,
+          port,
           extraArgs);
     }
   }
@@ -131,8 +135,10 @@
       bool pause_on_start,
       bool pause_on_exit,
       bool pause_on_unhandled_exceptions,
+      bool enable_service_port_fallback,
       bool testeeControlsServer,
       Uri serviceInfoUri,
+      int port,
       List<String> extraArgs) {
     assert(!_shouldLaunchSkyShell());
 
@@ -145,6 +151,9 @@
     if (pause_on_exit) {
       fullArgs.add('--pause-isolates-on-exit');
     }
+    if (enable_service_port_fallback) {
+      fullArgs.add('--enable_service_port_fallback');
+    }
     fullArgs.add('--write-service-info=$serviceInfoUri');
 
     if (pause_on_unhandled_exceptions) {
@@ -157,7 +166,7 @@
 
     fullArgs.addAll(Platform.executableArguments);
     if (!testeeControlsServer) {
-      fullArgs.add('--enable-vm-service:0');
+      fullArgs.add('--enable-vm-service:$port');
     }
     fullArgs.addAll(args);
 
@@ -221,15 +230,24 @@
       bool pause_on_start,
       bool pause_on_exit,
       bool pause_on_unhandled_exceptions,
+      bool enable_service_port_fallback,
       bool testeeControlsServer,
+      int port,
       List<String> extraArgs) async {
     final completer = new Completer<Uri>();
     final serviceInfoDir =
         await Directory.systemTemp.createTemp('dart_service');
     final serviceInfoUri = serviceInfoDir.uri.resolve('service_info.json');
     final serviceInfoFile = await File.fromUri(serviceInfoUri).create();
-    _spawnProcess(pause_on_start, pause_on_exit, pause_on_unhandled_exceptions,
-            testeeControlsServer, serviceInfoUri, extraArgs)
+    _spawnProcess(
+            pause_on_start,
+            pause_on_exit,
+            pause_on_unhandled_exceptions,
+            enable_service_port_fallback,
+            testeeControlsServer,
+            serviceInfoUri,
+            port,
+            extraArgs)
         .then((p) async {
       process = p;
       Uri uri;
@@ -291,22 +309,31 @@
 }
 
 class _ServiceTesterRunner {
-  void run(
-      {List<String> mainArgs,
-      List<String> extraArgs,
-      List<VMTest> vmTests,
-      List<IsolateTest> isolateTests,
-      bool pause_on_start: false,
-      bool pause_on_exit: false,
-      bool verbose_vm: false,
-      bool pause_on_unhandled_exceptions: false,
-      bool testeeControlsServer: false}) {
+  void run({
+    List<String> mainArgs,
+    List<String> extraArgs,
+    List<VMTest> vmTests,
+    List<IsolateTest> isolateTests,
+    bool pause_on_start: false,
+    bool pause_on_exit: false,
+    bool verbose_vm: false,
+    bool pause_on_unhandled_exceptions: false,
+    bool enable_service_port_fallback: false,
+    bool testeeControlsServer: false,
+    int port = 0,
+  }) {
     var process = new _ServiceTesteeLauncher();
     bool testsDone = false;
     runZoned(() {
       process
-          .launch(pause_on_start, pause_on_exit, pause_on_unhandled_exceptions,
-              testeeControlsServer, extraArgs)
+          .launch(
+              pause_on_start,
+              pause_on_exit,
+              pause_on_unhandled_exceptions,
+              enable_service_port_fallback,
+              testeeControlsServer,
+              port,
+              extraArgs)
           .then((Uri serverAddress) async {
         if (mainArgs.contains("--gdb")) {
           var pid = process.process.pid;
@@ -486,6 +513,8 @@
     bool pause_on_exit: false,
     bool verbose_vm: false,
     bool pause_on_unhandled_exceptions: false,
+    bool enable_service_port_fallback: false,
+    int port = 0,
     List<String> extraArgs}) async {
   if (_isTestee()) {
     new _ServiceTesteeRunner().run(
@@ -495,12 +524,15 @@
         pause_on_exit: pause_on_exit);
   } else {
     new _ServiceTesterRunner().run(
-        mainArgs: mainArgs,
-        extraArgs: extraArgs,
-        vmTests: tests,
-        pause_on_start: pause_on_start,
-        pause_on_exit: pause_on_exit,
-        verbose_vm: verbose_vm,
-        pause_on_unhandled_exceptions: pause_on_unhandled_exceptions);
+      mainArgs: mainArgs,
+      extraArgs: extraArgs,
+      vmTests: tests,
+      pause_on_start: pause_on_start,
+      pause_on_exit: pause_on_exit,
+      verbose_vm: verbose_vm,
+      pause_on_unhandled_exceptions: pause_on_unhandled_exceptions,
+      enable_service_port_fallback: enable_service_port_fallback,
+      port: port,
+    );
   }
 }
diff --git a/runtime/platform/globals.h b/runtime/platform/globals.h
index 3e16778..26c981d 100644
--- a/runtime/platform/globals.h
+++ b/runtime/platform/globals.h
@@ -417,6 +417,10 @@
 #define DUAL_MAPPING_SUPPORTED 1
 #endif
 
+#if defined(DART_PRECOMPILED_RUNTIME) || defined(DART_PRECOMPILER)
+#define SUPPORT_UNBOXED_INSTANCE_FIELDS
+#endif
+
 // Short form printf format specifiers
 #define Pd PRIdPTR
 #define Pu PRIuPTR
diff --git a/runtime/platform/utils.h b/runtime/platform/utils.h
index ee24ad6..38d4d2f 100644
--- a/runtime/platform/utils.h
+++ b/runtime/platform/utils.h
@@ -21,7 +21,7 @@
   }
 
   template <typename T>
-  static inline T Maximum(T x, T y) {
+  static constexpr inline T Maximum(T x, T y) {
     return x > y ? x : y;
   }
 
@@ -352,12 +352,18 @@
     return bit_cast<word>(mask);
   }
 
-  static uword Bit(uint32_t n) {
-    ASSERT(n < kBitsPerWord);
-    uword bit = 1;
+  template <typename T = uword>
+  static T Bit(uint32_t n) {
+    ASSERT(n < sizeof(T) * kBitsPerByte);
+    T bit = 1;
     return bit << n;
   }
 
+  template <typename T>
+  DART_FORCE_INLINE static bool TestBit(T mask, intptr_t position) {
+    return ((mask >> position) & 1) != 0;
+  }
+
   // Decode integer in SLEB128 format from |data| and update |byte_index|.
   template <typename ValueType>
   static ValueType DecodeSLEB128(const uint8_t* data,
diff --git a/runtime/tests/vm/dart/causal_stacks/async_throws_stack_no_causal_test.dart b/runtime/tests/vm/dart/causal_stacks/async_throws_stack_no_causal_test.dart
index cb27690..7cc8cf0 100644
--- a/runtime/tests/vm/dart/causal_stacks/async_throws_stack_no_causal_test.dart
+++ b/runtime/tests/vm/dart/causal_stacks/async_throws_stack_no_causal_test.dart
@@ -8,4 +8,4 @@
 
 import 'utils.dart';
 
-Future<void> main(List<String> args) async => await doTestsNoCausal();
+Future<void> main(List<String> args) async => await doTestsNoCausalNoLazy();
diff --git a/runtime/tests/vm/dart/causal_stacks/utils.dart b/runtime/tests/vm/dart/causal_stacks/utils.dart
index 3fa25e4..8cca3e5 100644
--- a/runtime/tests/vm/dart/causal_stacks/utils.dart
+++ b/runtime/tests/vm/dart/causal_stacks/utils.dart
@@ -133,6 +133,22 @@
   await ss.asFuture();
 }
 
+// ----
+// Scenario: All async functions yielded and we run in a custom zone with a
+// custom error handler.
+// ----
+
+Future<void> customErrorZone() async {
+  final completer = Completer<void>();
+  runZoned(() async {
+    await allYield();
+    completer.complete(null);
+  }, onError: (e, s) {
+    completer.completeError(e, s);
+  });
+  return completer.future;
+}
+
 // Helpers:
 
 void assertStack(List<String> expects, StackTrace stackTrace) {
@@ -149,8 +165,8 @@
       // On failed expect, print full stack for reference.
       print('Actual stack:');
       print(stackTrace.toString());
-      print('Expected line ${i + 1} to match:');
-      print(expects[i]);
+      print('Expected line ${i + 1} to be `${expects[i]}` '
+          'but was `${frames[i]}`');
       rethrow;
     }
   }
@@ -522,10 +538,61 @@
             r'^#7      _RawReceivePortImpl._handleMessage \(.+\)$',
             r'^$',
           ]);
+  final customErrorZoneExpected = const <String>[
+    r'#0      throwSync \(.*/utils.dart:16(:3)?\)$',
+    r'#1      allYield3 \(.*/utils.dart:39(:3)?\)$',
+    r'<asynchronous suspension>$',
+    r'#2      allYield2 \(.*/utils.dart:34(:9)?\)$',
+    r'<asynchronous suspension>$',
+    r'#3      allYield \(.*/utils.dart:29(:9)?\)$',
+    r'<asynchronous suspension>$',
+    r'#4      customErrorZone.<anonymous closure> \(.*/utils.dart:144(:11)?\)$',
+    r'#5      _rootRun ',
+    r'#6      _CustomZone.run ',
+    r'#7      _runZoned ',
+    r'#8      runZoned ',
+    r'#9      customErrorZone \(.*/utils.dart:143(:3)?\)$',
+  ];
+  await doTestAwait(
+      customErrorZone,
+      customErrorZoneExpected +
+          const <String>[
+            r'#10     doTestAwait ',
+            r'#11     doTestsCausal ',
+            r'<asynchronous suspension>$',
+            r'#12     main \(.+\)$',
+            r'#13     _startIsolate.<anonymous closure> ',
+            r'#14     _RawReceivePortImpl._handleMessage ',
+            r'$',
+          ]);
+  await doTestAwaitThen(
+      customErrorZone,
+      customErrorZoneExpected +
+          const <String>[
+            r'#10     doTestAwaitThen ',
+            r'#11     doTestsCausal ',
+            r'<asynchronous suspension>$',
+            r'#12     main \(.+\)$',
+            r'#13     _startIsolate.<anonymous closure> ',
+            r'#14     _RawReceivePortImpl._handleMessage ',
+            r'$'
+          ]);
+  await doTestAwaitCatchError(
+      customErrorZone,
+      customErrorZoneExpected +
+          const <String>[
+            r'#10     doTestAwaitCatchError ',
+            r'#11     doTestsCausal ',
+            r'<asynchronous suspension>$',
+            r'#12     main \(.+\)$',
+            r'#13     _startIsolate.<anonymous closure> ',
+            r'#14     _RawReceivePortImpl._handleMessage ',
+            r'$'
+          ]);
 }
 
-// For: --no-causal-async-stacks
-Future<void> doTestsNoCausal() async {
+// For: --no-causal-async-stacks --no-lazy-async-stacks
+Future<void> doTestsNoCausalNoLazy() async {
   final allYieldExpected = const <String>[
     r'^#0      throwSync \(.*/utils.dart:16(:3)?\)$',
     r'^#1      allYield3 \(.*/utils.dart:39(:3)?\)$',
@@ -564,7 +631,7 @@
             r'^#10     doTestAwait ',
             r'^#11     _AsyncAwaitCompleter.start ',
             r'^#12     doTestAwait ',
-            r'^#13     doTestsNoCausal ',
+            r'^#13     doTestsNoCausalNoLazy ',
             r'^#14     _RootZone.runUnary ',
             r'^#15     _FutureListener.handleValue ',
             r'^#16     Future._propagateToListeners.handleValueCallback ',
@@ -615,7 +682,7 @@
             r'^#10     doTestAwaitThen ',
             r'^#11     _AsyncAwaitCompleter.start ',
             r'^#12     doTestAwaitThen ',
-            r'^#13     doTestsNoCausal ',
+            r'^#13     doTestsNoCausalNoLazy ',
             r'^#14     _RootZone.runUnary ',
             r'^#15     _FutureListener.handleValue ',
             r'^#16     Future._propagateToListeners.handleValueCallback ',
@@ -661,7 +728,7 @@
             r'^#10     doTestAwaitCatchError ',
             r'^#11     _AsyncAwaitCompleter.start ',
             r'^#12     doTestAwaitCatchError ',
-            r'^#13     doTestsNoCausal ',
+            r'^#13     doTestsNoCausalNoLazy ',
             r'^#14     _RootZone.runUnary ',
             r'^#15     _FutureListener.handleValue ',
             r'^#16     Future._propagateToListeners.handleValueCallback ',
@@ -814,6 +881,29 @@
   await doTestAwaitThen(listenAsyncStarThrowAsync, listenAsyncStartExpected);
   await doTestAwaitCatchError(
       listenAsyncStarThrowAsync, listenAsyncStartExpected);
+
+  final customErrorZoneExpected = const <String>[
+    r'#0      throwSync \(.*/utils.dart:16(:3)?\)$',
+    r'#1      allYield3 \(.*/utils.dart:39(:3)?\)$',
+    r'#2      _rootRunUnary ',
+    r'#3      _CustomZone.runUnary ',
+    r'#4      _FutureListener.handleValue ',
+    r'#5      Future._propagateToListeners.handleValueCallback ',
+    r'#6      Future._propagateToListeners ',
+    r'#7      Future.(_addListener|_prependListeners).<anonymous closure> ',
+    r'#8      _rootRun ',
+    r'#9      _CustomZone.run ',
+    r'#10     _CustomZone.runGuarded ',
+    r'#11     _CustomZone.bindCallbackGuarded.<anonymous closure> ',
+    r'#12     _microtaskLoop ',
+    r'#13     _startMicrotaskLoop ',
+    r'#14     _runPendingImmediateCallback ',
+    r'#15     _RawReceivePortImpl._handleMessage ',
+    r'$',
+  ];
+  await doTestAwait(customErrorZone, customErrorZoneExpected);
+  await doTestAwaitThen(customErrorZone, customErrorZoneExpected);
+  await doTestAwaitCatchError(customErrorZone, customErrorZoneExpected);
 }
 
 // For: --lazy-async-stacks
@@ -1094,4 +1184,20 @@
   await doTestAwaitThen(listenAsyncStarThrowAsync, listenAsyncStartExpected);
   await doTestAwaitCatchError(
       listenAsyncStarThrowAsync, listenAsyncStartExpected);
+
+  final customErrorZoneExpected = const <String>[
+    r'#0      throwSync \(.*/utils.dart:16(:3)?\)$',
+    r'#1      allYield3 \(.*/utils.dart:39(:3)?\)$',
+    r'<asynchronous suspension>$',
+    r'#2      allYield2 \(.*/utils.dart:34(:3)?\)$',
+    r'<asynchronous suspension>$',
+    r'#3      allYield \(.*/utils.dart:29(:3)?\)$',
+    r'<asynchronous suspension>$',
+    r'#4      customErrorZone.<anonymous closure> \(.*/utils.dart:144(:5)?\)$',
+    r'<asynchronous suspension>$',
+    r'^$',
+  ];
+  await doTestAwait(customErrorZone, customErrorZoneExpected);
+  await doTestAwaitThen(customErrorZone, customErrorZoneExpected);
+  await doTestAwaitCatchError(customErrorZone, customErrorZoneExpected);
 }
diff --git a/runtime/tests/vm/dart/isolate_send_function_types_test.dart b/runtime/tests/vm/dart/isolate_send_function_types_test.dart
new file mode 100644
index 0000000..e8fb8ff
--- /dev/null
+++ b/runtime/tests/vm/dart/isolate_send_function_types_test.dart
@@ -0,0 +1,47 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+import 'dart:async';
+import 'dart:isolate';
+
+import 'package:expect/expect.dart';
+
+class A<T> {}
+
+main(args) async {
+  final x = A<void Function()>();
+
+  {
+    final caughtErrorCompleter = Completer<String>();
+    await runZoned(() {
+      Isolate.spawn(isolate, x);
+    }, onError: (e) {
+      caughtErrorCompleter.complete(e.toString());
+    });
+    Expect.equals(
+        await caughtErrorCompleter.future,
+        "Invalid argument(s): Illegal argument in isolate message : "
+        "(function types are not supported yet)");
+  }
+
+  void genericFunc<T>() async {
+    final y = A<void Function(T)>();
+    final caughtErrorCompleter = Completer<String>();
+    await runZoned(() {
+      Isolate.spawn(isolate, y);
+    }, onError: (e) {
+      caughtErrorCompleter.complete(e.toString());
+    });
+    Expect.equals(
+        await caughtErrorCompleter.future,
+        "Invalid argument(s): Illegal argument in isolate message : "
+        "(function types are not supported yet)");
+  }
+
+  await genericFunc<int>();
+}
+
+void isolate(A foo) async {
+  print('Tick: ${foo}');
+}
diff --git a/runtime/tests/vm/dart/unboxed_fields_type_args_test.dart b/runtime/tests/vm/dart/unboxed_fields_type_args_test.dart
new file mode 100644
index 0000000..d19c5e9
--- /dev/null
+++ b/runtime/tests/vm/dart/unboxed_fields_type_args_test.dart
@@ -0,0 +1,59 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:typed_data';
+import 'dart:async';
+import 'dart:isolate';
+
+import "package:expect/expect.dart";
+
+double getDoubleWithHeapObjectTag() {
+  final bd = ByteData(8);
+  bd.setUint64(0, 0x8000000000000001, Endian.host);
+  final double v = bd.getFloat64(0, Endian.host);
+  return v;
+}
+
+class Foo {
+  final String clazz = "foo";
+  final double x = getDoubleWithHeapObjectTag();
+}
+
+// Here we ensure to have a GC pointer and a non-GC pointer field, and then a
+// type argument vector, so the offset in number of words for the type arguments
+// will be different between host and target when compiling from 64-bit to
+// 32-bit architectures.
+class Bar<T> extends Foo {
+  final String clazz = "bar";
+  final double y = getDoubleWithHeapObjectTag();
+  final T value;
+  Bar(T val) : value = val;
+}
+
+main() async {
+  final receivePort = new ReceivePort();
+  receivePort.sendPort.send(Foo());
+  receivePort.sendPort.send(Bar<String>("StringBar"));
+  receivePort.sendPort.send(Bar<double>(4.2));
+  final it = StreamIterator(receivePort);
+
+  Expect.isTrue(await it.moveNext());
+  final foo = it.current as Foo;
+
+  Expect.isTrue(await it.moveNext());
+  final string_bar = it.current as Bar<String>;
+
+  Expect.isTrue(await it.moveNext());
+  final double_bar = it.current as Bar<double>;
+
+  Expect.equals(string_bar.value, "StringBar");
+  Expect.equals(string_bar.clazz, "bar");
+  Expect.equals(string_bar.y, getDoubleWithHeapObjectTag());
+  Expect.equals(string_bar.x, getDoubleWithHeapObjectTag());
+  Expect.equals(double_bar.value, 4.2);
+  Expect.equals(foo.clazz, "foo");
+  Expect.equals(foo.x, getDoubleWithHeapObjectTag());
+
+  await it.cancel();
+}
diff --git a/runtime/tests/vm/vm.status b/runtime/tests/vm/vm.status
index 7f713cd..e2a4f25 100644
--- a/runtime/tests/vm/vm.status
+++ b/runtime/tests/vm/vm.status
@@ -77,7 +77,7 @@
 cc/GenKernelKernelMaxRSS: Skip # Issue 34393.
 cc/GenKernelKernelReadAllBytecode: Skip # Issue 34393.
 dart/appjit_bytecode_simple_test: Skip # Issue 34393.
-dart/disassemble_determinism_test: Slow # Times out on slower bots.
+dart/disassemble_determinism_test: Slow, Pass # Times out on slower bots.
 
 [ $arch == ia32 && $mode == debug && $system == windows ]
 dart/transferable_test: Skip # This is performance test and somehow debug win ia32 bot's performance is unpredictable
diff --git a/runtime/vm/BUILD.gn b/runtime/vm/BUILD.gn
index d0bcee0..50239a1 100644
--- a/runtime/vm/BUILD.gn
+++ b/runtime/vm/BUILD.gn
@@ -70,14 +70,16 @@
   if (is_fuchsia) {
     if (using_fuchsia_sdk) {
       extra_deps += [
-        "$fuchsia_sdk_root/fidl:fuchsia.intl",
+        "$fuchsia_sdk_root/fidl:fuchsia.deprecatedtimezone",
         "$fuchsia_sdk_root/pkg:sys_cpp",
         "$fuchsia_sdk_root/pkg:trace-engine",
       ]
     } else {
       extra_deps += [
-        "//sdk/fidl/fuchsia.intl",
+        # TODO(US-399): Remove time_service specific code when it is no longer
+        # necessary.
         "//sdk/lib/sys/cpp",
+        "//sdk/fidl/fuchsia.deprecatedtimezone",
 
         "//zircon/public/lib/fbl",
         "//zircon/public/lib/trace-engine",
diff --git a/runtime/vm/bootstrap.cc b/runtime/vm/bootstrap.cc
index 584baa3..ff1c7b7 100644
--- a/runtime/vm/bootstrap.cc
+++ b/runtime/vm/bootstrap.cc
@@ -71,17 +71,17 @@
   // Verify that closure field offsets are identical in Dart and C++.
   ASSERT(fields.Length() == 6);
   field ^= fields.At(0);
-  ASSERT(field.Offset() == Closure::instantiator_type_arguments_offset());
+  ASSERT(field.HostOffset() == Closure::instantiator_type_arguments_offset());
   field ^= fields.At(1);
-  ASSERT(field.Offset() == Closure::function_type_arguments_offset());
+  ASSERT(field.HostOffset() == Closure::function_type_arguments_offset());
   field ^= fields.At(2);
-  ASSERT(field.Offset() == Closure::delayed_type_arguments_offset());
+  ASSERT(field.HostOffset() == Closure::delayed_type_arguments_offset());
   field ^= fields.At(3);
-  ASSERT(field.Offset() == Closure::function_offset());
+  ASSERT(field.HostOffset() == Closure::function_offset());
   field ^= fields.At(4);
-  ASSERT(field.Offset() == Closure::context_offset());
+  ASSERT(field.HostOffset() == Closure::context_offset());
   field ^= fields.At(5);
-  ASSERT(field.Offset() == Closure::hash_offset());
+  ASSERT(field.HostOffset() == Closure::hash_offset());
 #endif  // defined(DEBUG)
 
   // Eagerly compile Bool class, bool constants are used from within compiler.
diff --git a/runtime/vm/class_finalizer.cc b/runtime/vm/class_finalizer.cc
index a7b520f..5f72da1 100644
--- a/runtime/vm/class_finalizer.cc
+++ b/runtime/vm/class_finalizer.cc
@@ -240,33 +240,33 @@
 #if defined(DEBUG)
   // Basic checking.
   cls = object_store->object_class();
-  ASSERT(Instance::InstanceSize() == cls.instance_size());
+  ASSERT(Instance::InstanceSize() == cls.host_instance_size());
   cls = object_store->integer_implementation_class();
-  ASSERT(Integer::InstanceSize() == cls.instance_size());
+  ASSERT(Integer::InstanceSize() == cls.host_instance_size());
   cls = object_store->smi_class();
-  ASSERT(Smi::InstanceSize() == cls.instance_size());
+  ASSERT(Smi::InstanceSize() == cls.host_instance_size());
   cls = object_store->mint_class();
-  ASSERT(Mint::InstanceSize() == cls.instance_size());
+  ASSERT(Mint::InstanceSize() == cls.host_instance_size());
   cls = object_store->one_byte_string_class();
-  ASSERT(OneByteString::InstanceSize() == cls.instance_size());
+  ASSERT(OneByteString::InstanceSize() == cls.host_instance_size());
   cls = object_store->two_byte_string_class();
-  ASSERT(TwoByteString::InstanceSize() == cls.instance_size());
+  ASSERT(TwoByteString::InstanceSize() == cls.host_instance_size());
   cls = object_store->external_one_byte_string_class();
-  ASSERT(ExternalOneByteString::InstanceSize() == cls.instance_size());
+  ASSERT(ExternalOneByteString::InstanceSize() == cls.host_instance_size());
   cls = object_store->external_two_byte_string_class();
-  ASSERT(ExternalTwoByteString::InstanceSize() == cls.instance_size());
+  ASSERT(ExternalTwoByteString::InstanceSize() == cls.host_instance_size());
   cls = object_store->double_class();
-  ASSERT(Double::InstanceSize() == cls.instance_size());
+  ASSERT(Double::InstanceSize() == cls.host_instance_size());
   cls = object_store->bool_class();
-  ASSERT(Bool::InstanceSize() == cls.instance_size());
+  ASSERT(Bool::InstanceSize() == cls.host_instance_size());
   cls = object_store->array_class();
-  ASSERT(Array::InstanceSize() == cls.instance_size());
+  ASSERT(Array::InstanceSize() == cls.host_instance_size());
   cls = object_store->immutable_array_class();
-  ASSERT(ImmutableArray::InstanceSize() == cls.instance_size());
+  ASSERT(ImmutableArray::InstanceSize() == cls.host_instance_size());
   cls = object_store->weak_property_class();
-  ASSERT(WeakProperty::InstanceSize() == cls.instance_size());
+  ASSERT(WeakProperty::InstanceSize() == cls.host_instance_size());
   cls = object_store->linked_hash_map_class();
-  ASSERT(LinkedHashMap::InstanceSize() == cls.instance_size());
+  ASSERT(LinkedHashMap::InstanceSize() == cls.host_instance_size());
 #endif  // defined(DEBUG)
 
   // Remember the currently pending classes.
@@ -1358,7 +1358,7 @@
   fields_array ^= cls.fields();
   ASSERT(fields_array.Length() == ByteBuffer::NumberOfFields());
   field ^= fields_array.At(0);
-  ASSERT(field.Offset() == ByteBuffer::data_offset());
+  ASSERT(field.HostOffset() == ByteBuffer::data_offset());
   name ^= field.name();
   expected_name ^= String::New("_data");
   ASSERT(String::EqualsIgnoringPrivateKey(name, expected_name));
diff --git a/runtime/vm/class_table.cc b/runtime/vm/class_table.cc
index 5722c74..e645df3 100644
--- a/runtime/vm/class_table.cc
+++ b/runtime/vm/class_table.cc
@@ -4,6 +4,8 @@
 
 #include "vm/class_table.h"
 
+#include <memory>
+
 #include "platform/atomic.h"
 #include "vm/flags.h"
 #include "vm/growable_array.h"
@@ -21,7 +23,9 @@
     : top_(kNumPredefinedCids),
       capacity_(0),
       table_(NULL),
-      old_tables_(new MallocGrowableArray<intptr_t*>()) {
+      old_tables_(new MallocGrowableArray<intptr_t*>()),
+      unboxed_fields_map_(nullptr),
+      old_unboxed_fields_maps_(new MallocGrowableArray<UnboxedFieldBitmap*>()) {
   if (Dart::vm_isolate() == NULL) {
     ASSERT(kInitialCapacity >= kNumPredefinedCids);
     capacity_ = kInitialCapacity;
@@ -47,6 +51,11 @@
     table_[kVoidCid] = vm_shared_class_table->SizeAt(kVoidCid);
     table_[kNeverCid] = vm_shared_class_table->SizeAt(kNeverCid);
   }
+#if defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
+  unboxed_fields_map_ = static_cast<UnboxedFieldBitmap*>(
+      malloc(capacity_ * sizeof(UnboxedFieldBitmap)));
+  memset(unboxed_fields_map_, 0, sizeof(UnboxedFieldBitmap) * capacity_);
+#endif  // defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
 #ifndef PRODUCT
   trace_allocation_table_ =
       static_cast<uint8_t*>(malloc(capacity_ * sizeof(uint8_t)));  // NOLINT
@@ -61,6 +70,16 @@
     delete old_tables_;
     free(table_);
   }
+
+  if (old_unboxed_fields_maps_ != nullptr) {
+    FreeOldUnboxedFieldsMaps();
+    delete old_unboxed_fields_maps_;
+  }
+
+  if (unboxed_fields_map_ != nullptr) {
+    free(unboxed_fields_map_);
+  }
+
   NOT_IN_PRODUCT(free(trace_allocation_table_));
 }
 
@@ -133,6 +152,12 @@
   }
 }
 
+void SharedClassTable::FreeOldUnboxedFieldsMaps() {
+  while (old_unboxed_fields_maps_->length() > 0) {
+    free(old_unboxed_fields_maps_->RemoveLast());
+  }
+}
+
 void ClassTable::Register(const Class& cls) {
   ASSERT(Thread::Current()->IsMutatorThread());
 
@@ -142,7 +167,7 @@
   // parallel to [ClassTable].
 
   const intptr_t instance_size =
-      cls.is_abstract() ? 0 : Class::instance_size(cls.raw());
+      cls.is_abstract() ? 0 : Class::host_instance_size(cls.raw());
 
   const intptr_t expected_cid =
       shared_class_table_->Register(index, instance_size);
@@ -239,6 +264,7 @@
 
   intptr_t* new_table = static_cast<intptr_t*>(
       malloc(new_capacity * sizeof(intptr_t)));  // NOLINT
+
   memmove(new_table, table_, top_ * sizeof(intptr_t));
   memset(new_table + top_, 0, (new_capacity - top_) * sizeof(intptr_t));
 #ifndef PRODUCT
@@ -250,10 +276,22 @@
     new_table[i] = 0;
     NOT_IN_PRODUCT(new_stats_table[i] = 0);
   }
+
   capacity_ = new_capacity;
   old_tables_->Add(table_);
   table_ = new_table;  // TODO(koda): This should use atomics.
   NOT_IN_PRODUCT(trace_allocation_table_ = new_stats_table);
+
+#if defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
+  auto new_unboxed_fields_map = static_cast<UnboxedFieldBitmap*>(
+      malloc(new_capacity * sizeof(UnboxedFieldBitmap)));
+  memmove(new_unboxed_fields_map, unboxed_fields_map_,
+          top_ * sizeof(UnboxedFieldBitmap));
+  memset(new_unboxed_fields_map + top_, 0,
+         (new_capacity - top_) * sizeof(UnboxedFieldBitmap));
+  old_unboxed_fields_maps_->Add(unboxed_fields_map_);
+  unboxed_fields_map_ = new_unboxed_fields_map;
+#endif  // defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
 }
 
 void ClassTable::Unregister(intptr_t index) {
@@ -263,6 +301,9 @@
 
 void SharedClassTable::Unregister(intptr_t index) {
   table_[index] = 0;
+#if defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
+  unboxed_fields_map_[index].Reset();
+#endif  // defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
 }
 
 void ClassTable::Remap(intptr_t* old_to_new_cid) {
@@ -281,14 +322,24 @@
 void SharedClassTable::Remap(intptr_t* old_to_new_cid) {
   ASSERT(Thread::Current()->IsAtSafepoint());
   const intptr_t num_cids = NumCids();
-  intptr_t* cls_by_old_cid = new intptr_t[num_cids];
+  std::unique_ptr<intptr_t[]> cls_by_old_cid(new intptr_t[num_cids]);
   for (intptr_t i = 0; i < num_cids; i++) {
     cls_by_old_cid[i] = table_[i];
   }
   for (intptr_t i = 0; i < num_cids; i++) {
     table_[old_to_new_cid[i]] = cls_by_old_cid[i];
   }
-  delete[] cls_by_old_cid;
+
+#if defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
+  std::unique_ptr<UnboxedFieldBitmap[]> unboxed_fields_by_old_cid(
+      new UnboxedFieldBitmap[num_cids]);
+  for (intptr_t i = 0; i < num_cids; i++) {
+    unboxed_fields_by_old_cid[i] = unboxed_fields_map_[i];
+  }
+  for (intptr_t i = 0; i < num_cids; i++) {
+    unboxed_fields_map_[old_to_new_cid[i]] = unboxed_fields_by_old_cid[i];
+  }
+#endif  // defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
 }
 
 void ClassTable::VisitObjectPointers(ObjectPointerVisitor* visitor) {
@@ -344,7 +395,8 @@
 void ClassTable::SetAt(intptr_t index, RawClass* raw_cls) {
   // This is called by snapshot reader and class finalizer.
   ASSERT(index < capacity_);
-  const intptr_t size = raw_cls == nullptr ? 0 : Class::instance_size(raw_cls);
+  const intptr_t size =
+      raw_cls == nullptr ? 0 : Class::host_instance_size(raw_cls);
   shared_class_table_->SetSizeAt(index, size);
   table_[index] = raw_cls;
 }
diff --git a/runtime/vm/class_table.h b/runtime/vm/class_table.h
index fb13d2e..62383d3 100644
--- a/runtime/vm/class_table.h
+++ b/runtime/vm/class_table.h
@@ -7,9 +7,11 @@
 
 #include "platform/assert.h"
 #include "platform/atomic.h"
+#include "platform/utils.h"
 
 #include "vm/bitfield.h"
 #include "vm/class_id.h"
+#include "vm/flags.h"
 #include "vm/globals.h"
 
 namespace dart {
@@ -28,6 +30,33 @@
 class ObjectPointerVisitor;
 class RawClass;
 
+// Wraps a 64-bit integer to represent the bitmap of unboxed fields
+// stored in the shared class table.
+class UnboxedFieldBitmap {
+ public:
+  UnboxedFieldBitmap() : bitmap_(0) {}
+  explicit UnboxedFieldBitmap(uint64_t bitmap) : bitmap_(bitmap) {}
+  UnboxedFieldBitmap(const UnboxedFieldBitmap&) = default;
+  UnboxedFieldBitmap& operator=(const UnboxedFieldBitmap&) = default;
+
+  DART_FORCE_INLINE bool Get(intptr_t position) const {
+    return Utils::TestBit(bitmap_, position);
+  }
+  DART_FORCE_INLINE void Set(intptr_t position) {
+    bitmap_ |= Utils::Bit<decltype(bitmap_)>(position);
+  }
+  DART_FORCE_INLINE uint64_t Value() const { return bitmap_; }
+  DART_FORCE_INLINE bool IsEmpty() const { return bitmap_ == 0; }
+  DART_FORCE_INLINE void Reset() { bitmap_ = 0; }
+
+  DART_FORCE_INLINE static constexpr intptr_t Length() {
+    return sizeof(decltype(bitmap_)) * kBitsPerByte;
+  }
+
+ private:
+  uint64_t bitmap_;
+};
+
 // Registry of all known classes and their sizes.
 //
 // The GC will only need the information in this shared class table to scan
@@ -62,6 +91,19 @@
   intptr_t NumCids() const { return top_; }
   intptr_t Capacity() const { return capacity_; }
 
+  UnboxedFieldBitmap GetUnboxedFieldsMapAt(intptr_t index) const {
+    ASSERT(IsValidIndex(index));
+    return FLAG_precompiled_mode ? unboxed_fields_map_[index]
+                                 : UnboxedFieldBitmap();
+  }
+
+  void SetUnboxedFieldsMapAt(intptr_t index,
+                             UnboxedFieldBitmap unboxed_fields_map) {
+    ASSERT(IsValidIndex(index));
+    ASSERT(unboxed_fields_map_[index].IsEmpty());
+    unboxed_fields_map_[index] = unboxed_fields_map;
+  }
+
   // Used to drop recently added classes.
   void SetNumCids(intptr_t num_cids) {
     ASSERT(num_cids <= top_);
@@ -117,6 +159,9 @@
   // Deallocates table copies. Do not call during concurrent access to table.
   void FreeOldTables();
 
+  // Deallocates bitmap copies. Do not call during concurrent access to table.
+  void FreeOldUnboxedFieldsMaps();
+
 #if !defined(DART_PRECOMPILED_RUNTIME)
   bool IsReloading() const { return reload_context_ != nullptr; }
 
@@ -171,6 +216,14 @@
 
   IsolateGroupReloadContext* reload_context_ = nullptr;
 
+  // Stores a 64-bit bitmap for each class. There is one bit for each word in an
+  // instance of the class. A 0 bit indicates that the word contains a pointer
+  // the GC has to scan, a 1 indicates that the word is part of e.g. an unboxed
+  // double and does not need to be scanned. (see Class::Calculate...() where
+  // the bitmap is constructed)
+  UnboxedFieldBitmap* unboxed_fields_map_;
+  MallocGrowableArray<UnboxedFieldBitmap*>* old_unboxed_fields_maps_;
+
   DISALLOW_COPY_AND_ASSIGN(SharedClassTable);
 };
 
diff --git a/runtime/vm/clustered_snapshot.cc b/runtime/vm/clustered_snapshot.cc
index 50410b4..9dddd4c 100644
--- a/runtime/vm/clustered_snapshot.cc
+++ b/runtime/vm/clustered_snapshot.cc
@@ -182,19 +182,57 @@
     if (s->kind() != Snapshot::kFullAOT) {
       s->Write<uint32_t>(cls->ptr()->binary_declaration_);
     }
-    s->Write<int32_t>(cls->ptr()->instance_size_in_words_);
-    s->Write<int32_t>(cls->ptr()->next_field_offset_in_words_);
-    s->Write<int32_t>(cls->ptr()->type_arguments_field_offset_in_words_);
+    s->Write<int32_t>(Class::target_instance_size_in_words(cls));
+    s->Write<int32_t>(Class::target_next_field_offset_in_words(cls));
+    s->Write<int32_t>(Class::target_type_arguments_field_offset_in_words(cls));
     s->Write<int16_t>(cls->ptr()->num_type_arguments_);
     s->Write<uint16_t>(cls->ptr()->num_native_fields_);
     s->WriteTokenPosition(cls->ptr()->token_pos_);
     s->WriteTokenPosition(cls->ptr()->end_token_pos_);
     s->Write<uint32_t>(cls->ptr()->state_bits_);
+
+    // In AOT, the bitmap of unboxed fields should also be serialized
+    if (FLAG_precompiled_mode) {
+      s->WriteUnsigned64(
+          CalculateTargetUnboxedFieldsBitmap(s, class_id).Value());
+    }
   }
 
  private:
   GrowableArray<RawClass*> predefined_;
   GrowableArray<RawClass*> objects_;
+
+  UnboxedFieldBitmap CalculateTargetUnboxedFieldsBitmap(Serializer* s,
+                                                        intptr_t class_id) {
+    const auto unboxed_fields_bitmap_host =
+        s->isolate()->shared_class_table()->GetUnboxedFieldsMapAt(class_id);
+
+    UnboxedFieldBitmap unboxed_fields_bitmap;
+    if (unboxed_fields_bitmap_host.IsEmpty() ||
+        kWordSize == compiler::target::kWordSize) {
+      unboxed_fields_bitmap = unboxed_fields_bitmap_host;
+    } else {
+      ASSERT(kWordSize == 8 && compiler::target::kWordSize == 4);
+      // A new bitmap is built if the word sizes in the target and
+      // host are different
+      unboxed_fields_bitmap.Reset();
+      intptr_t target_i = 0, host_i = 0;
+
+      while (host_i < UnboxedFieldBitmap::Length()) {
+        // Each unboxed field has constant length, therefore the number of
+        // words used by it should double when compiling from 64-bit to 32-bit.
+        if (unboxed_fields_bitmap_host.Get(host_i++)) {
+          unboxed_fields_bitmap.Set(target_i++);
+          unboxed_fields_bitmap.Set(target_i++);
+        } else {
+          // For object pointers, the field is always one word length
+          target_i++;
+        }
+      }
+    }
+
+    return unboxed_fields_bitmap;
+  }
 };
 #endif  // !DART_PRECOMPILED_RUNTIME
 
@@ -240,18 +278,35 @@
       }
 #endif
       if (!RawObject::IsInternalVMdefinedClassId(class_id)) {
-        cls->ptr()->instance_size_in_words_ = d->Read<int32_t>();
-        cls->ptr()->next_field_offset_in_words_ = d->Read<int32_t>();
+        cls->ptr()->host_instance_size_in_words_ = d->Read<int32_t>();
+        cls->ptr()->host_next_field_offset_in_words_ = d->Read<int32_t>();
+#if !defined(DART_PRECOMPILED_RUNTIME)
+        // Only one pair is serialized. The target field only exists when
+        // DART_PRECOMPILED_RUNTIME is not defined
+        cls->ptr()->target_instance_size_in_words_ =
+            cls->ptr()->host_instance_size_in_words_;
+        cls->ptr()->target_next_field_offset_in_words_ =
+            cls->ptr()->host_next_field_offset_in_words_;
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
       } else {
         d->Read<int32_t>();  // Skip.
         d->Read<int32_t>();  // Skip.
       }
-      cls->ptr()->type_arguments_field_offset_in_words_ = d->Read<int32_t>();
+      cls->ptr()->host_type_arguments_field_offset_in_words_ =
+          d->Read<int32_t>();
+#if !defined(DART_PRECOMPILED_RUNTIME)
+      cls->ptr()->target_type_arguments_field_offset_in_words_ =
+          cls->ptr()->host_type_arguments_field_offset_in_words_;
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
       cls->ptr()->num_type_arguments_ = d->Read<int16_t>();
       cls->ptr()->num_native_fields_ = d->Read<uint16_t>();
       cls->ptr()->token_pos_ = d->ReadTokenPosition();
       cls->ptr()->end_token_pos_ = d->ReadTokenPosition();
       cls->ptr()->state_bits_ = d->Read<uint32_t>();
+
+      if (FLAG_precompiled_mode) {
+        d->ReadUnsigned64();  // Skip unboxed fields bitmap.
+      }
     }
 
     for (intptr_t id = start_index_; id < stop_index_; id++) {
@@ -268,9 +323,18 @@
         cls->ptr()->binary_declaration_ = d->Read<uint32_t>();
       }
 #endif
-      cls->ptr()->instance_size_in_words_ = d->Read<int32_t>();
-      cls->ptr()->next_field_offset_in_words_ = d->Read<int32_t>();
-      cls->ptr()->type_arguments_field_offset_in_words_ = d->Read<int32_t>();
+      cls->ptr()->host_instance_size_in_words_ = d->Read<int32_t>();
+      cls->ptr()->host_next_field_offset_in_words_ = d->Read<int32_t>();
+      cls->ptr()->host_type_arguments_field_offset_in_words_ =
+          d->Read<int32_t>();
+#if !defined(DART_PRECOMPILED_RUNTIME)
+      cls->ptr()->target_instance_size_in_words_ =
+          cls->ptr()->host_instance_size_in_words_;
+      cls->ptr()->target_next_field_offset_in_words_ =
+          cls->ptr()->host_next_field_offset_in_words_;
+      cls->ptr()->target_type_arguments_field_offset_in_words_ =
+          cls->ptr()->host_type_arguments_field_offset_in_words_;
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
       cls->ptr()->num_type_arguments_ = d->Read<int16_t>();
       cls->ptr()->num_native_fields_ = d->Read<uint16_t>();
       cls->ptr()->token_pos_ = d->ReadTokenPosition();
@@ -279,6 +343,12 @@
 
       table->AllocateIndex(class_id);
       table->SetAt(class_id, cls);
+
+      if (FLAG_precompiled_mode) {
+        const UnboxedFieldBitmap unboxed_fields_map(d->ReadUnsigned64());
+        d->isolate()->shared_class_table()->SetUnboxedFieldsMapAt(
+            class_id, unboxed_fields_map);
+      }
     }
   }
 
@@ -935,13 +1005,13 @@
           kind == Snapshot::kFullAOT ||
           // Do not reset const fields.
           Field::ConstBit::decode(field->ptr()->kind_bits_)) {
-        s->Push(s->field_table()->At(field->ptr()->offset_or_field_id_));
+        s->Push(s->field_table()->At(field->ptr()->host_offset_or_field_id_));
       } else {
         // Otherwise, for static fields we write out the initial static value.
         s->Push(field->ptr()->saved_initial_value_);
       }
     } else {
-      s->Push(Smi::New(field->ptr()->offset_or_field_id_));
+      s->Push(Smi::New(Field::TargetOffsetOf(field)));
     }
   }
 
@@ -1001,14 +1071,14 @@
             Field::ConstBit::decode(field->ptr()->kind_bits_)) {
           WriteFieldValue(
               "static value",
-              s->field_table()->At(field->ptr()->offset_or_field_id_));
+              s->field_table()->At(field->ptr()->host_offset_or_field_id_));
         } else {
           // Otherwise, for static fields we write out the initial static value.
           WriteFieldValue("static value", field->ptr()->saved_initial_value_);
         }
-        s->WriteUnsigned(field->ptr()->offset_or_field_id_);
+        s->WriteUnsigned(field->ptr()->host_offset_or_field_id_);
       } else {
-        WriteFieldValue("offset", Smi::New(field->ptr()->offset_or_field_id_));
+        WriteFieldValue("offset", Smi::New(Field::TargetOffsetOf(field)));
       }
     }
   }
@@ -1057,10 +1127,13 @@
         intptr_t field_id = d->ReadUnsigned();
         d->field_table()->SetAt(
             field_id, reinterpret_cast<RawInstance*>(value_or_offset));
-        field->ptr()->offset_or_field_id_ = field_id;
+        field->ptr()->host_offset_or_field_id_ = field_id;
       } else {
-        field->ptr()->offset_or_field_id_ =
+        field->ptr()->host_offset_or_field_id_ =
             Smi::Value(Smi::RawCast(value_or_offset));
+#if !defined(DART_PRECOMPILED_RUNTIME)
+        field->ptr()->target_offset_ = field->ptr()->host_offset_or_field_id_;
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
       }
     }
   }
@@ -2722,23 +2795,34 @@
   explicit InstanceSerializationCluster(intptr_t cid)
       : SerializationCluster("Instance"), cid_(cid) {
     RawClass* cls = Isolate::Current()->class_table()->At(cid);
-    next_field_offset_in_words_ = cls->ptr()->next_field_offset_in_words_;
-    instance_size_in_words_ = cls->ptr()->instance_size_in_words_;
-    ASSERT(next_field_offset_in_words_ > 0);
-    ASSERT(instance_size_in_words_ > 0);
+    host_next_field_offset_in_words_ =
+        cls->ptr()->host_next_field_offset_in_words_;
+    ASSERT(host_next_field_offset_in_words_ > 0);
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    target_next_field_offset_in_words_ =
+        cls->ptr()->target_next_field_offset_in_words_;
+    target_instance_size_in_words_ = cls->ptr()->target_instance_size_in_words_;
+    ASSERT(target_next_field_offset_in_words_ > 0);
+    ASSERT(target_instance_size_in_words_ > 0);
+#endif  // !defined(DART_PRECOMPILED_RUNTIME)
   }
   ~InstanceSerializationCluster() {}
 
   void Trace(Serializer* s, RawObject* object) {
     RawInstance* instance = Instance::RawCast(object);
     objects_.Add(instance);
-
-    intptr_t next_field_offset = next_field_offset_in_words_ << kWordSizeLog2;
+    const intptr_t next_field_offset = host_next_field_offset_in_words_
+                                       << kWordSizeLog2;
+    const auto unboxed_fields_bitmap =
+        s->isolate()->shared_class_table()->GetUnboxedFieldsMapAt(cid_);
     intptr_t offset = Instance::NextFieldOffset();
     while (offset < next_field_offset) {
-      RawObject* raw_obj = *reinterpret_cast<RawObject**>(
-          reinterpret_cast<uword>(instance->ptr()) + offset);
-      s->Push(raw_obj);
+      // Skips unboxed fields
+      if (!unboxed_fields_bitmap.Get(offset / kWordSize)) {
+        RawObject* raw_obj = *reinterpret_cast<RawObject**>(
+            reinterpret_cast<uword>(instance->ptr()) + offset);
+        s->Push(raw_obj);
+      }
       offset += kWordSize;
     }
   }
@@ -2748,8 +2832,12 @@
     const intptr_t count = objects_.length();
     s->WriteUnsigned(count);
 
-    s->Write<int32_t>(next_field_offset_in_words_);
-    s->Write<int32_t>(instance_size_in_words_);
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    s->Write<int32_t>(target_next_field_offset_in_words_);
+    s->Write<int32_t>(target_instance_size_in_words_);
+#else
+    s->Write<int32_t>(host_next_field_offset_in_words_);
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
 
     for (intptr_t i = 0; i < count; i++) {
       RawInstance* instance = objects_[i];
@@ -2758,17 +2846,28 @@
   }
 
   void WriteFill(Serializer* s) {
-    intptr_t next_field_offset = next_field_offset_in_words_ << kWordSizeLog2;
+    intptr_t next_field_offset = host_next_field_offset_in_words_
+                                 << kWordSizeLog2;
     const intptr_t count = objects_.length();
+    const auto shared_class_table = s->isolate()->shared_class_table();
     for (intptr_t i = 0; i < count; i++) {
       RawInstance* instance = objects_[i];
       AutoTraceObject(instance);
       s->Write<bool>(instance->IsCanonical());
+      const auto unboxed_fields_bitmap =
+          shared_class_table->GetUnboxedFieldsMapAt(cid_);
       intptr_t offset = Instance::NextFieldOffset();
       while (offset < next_field_offset) {
-        RawObject* raw_obj = *reinterpret_cast<RawObject**>(
-            reinterpret_cast<uword>(instance->ptr()) + offset);
-        s->WriteElementRef(raw_obj, offset);
+        if (unboxed_fields_bitmap.Get(offset / kWordSize)) {
+          // Writes 32 bits of the unboxed value at a time
+          const uword value = *reinterpret_cast<uword*>(
+              reinterpret_cast<uword>(instance->ptr()) + offset);
+          s->WriteWordWith32BitWrites(value);
+        } else {
+          RawObject* raw_obj = *reinterpret_cast<RawObject**>(
+              reinterpret_cast<uword>(instance->ptr()) + offset);
+          s->WriteElementRef(raw_obj, offset);
+        }
         offset += kWordSize;
       }
     }
@@ -2776,8 +2875,11 @@
 
  private:
   const intptr_t cid_;
-  intptr_t next_field_offset_in_words_;
-  intptr_t instance_size_in_words_;
+  intptr_t host_next_field_offset_in_words_;
+#if !defined(DART_PRECOMPILED_RUNTIME)
+  intptr_t target_next_field_offset_in_words_;
+  intptr_t target_instance_size_in_words_;
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
   GrowableArray<RawInstance*> objects_;
 };
 #endif  // !DART_PRECOMPILED_RUNTIME
@@ -2806,16 +2908,26 @@
     intptr_t instance_size =
         Object::RoundedAllocationSize(instance_size_in_words_ * kWordSize);
 
+    const auto shared_class_table = d->isolate()->shared_class_table();
     for (intptr_t id = start_index_; id < stop_index_; id++) {
       RawInstance* instance = reinterpret_cast<RawInstance*>(d->Ref(id));
       bool is_canonical = d->Read<bool>();
       Deserializer::InitializeHeader(instance, cid_, instance_size,
                                      is_canonical);
+      const auto unboxed_fields_bitmap =
+          shared_class_table->GetUnboxedFieldsMapAt(cid_);
       intptr_t offset = Instance::NextFieldOffset();
       while (offset < next_field_offset) {
-        RawObject** p = reinterpret_cast<RawObject**>(
-            reinterpret_cast<uword>(instance->ptr()) + offset);
-        *p = d->ReadRef();
+        if (unboxed_fields_bitmap.Get(offset / kWordSize)) {
+          uword* p = reinterpret_cast<uword*>(
+              reinterpret_cast<uword>(instance->ptr()) + offset);
+          // Reads 32 bits of the unboxed value at a time
+          *p = d->ReadWordWith32BitReads();
+        } else {
+          RawObject** p = reinterpret_cast<RawObject**>(
+              reinterpret_cast<uword>(instance->ptr()) + offset);
+          *p = d->ReadRef();
+        }
         offset += kWordSize;
       }
       if (offset < instance_size) {
diff --git a/runtime/vm/clustered_snapshot.h b/runtime/vm/clustered_snapshot.h
index 7be84ef..ed8555f 100644
--- a/runtime/vm/clustered_snapshot.h
+++ b/runtime/vm/clustered_snapshot.h
@@ -234,6 +234,12 @@
     WriteStream::Raw<sizeof(T), T>::Write(&stream_, value);
   }
   void WriteUnsigned(intptr_t value) { stream_.WriteUnsigned(value); }
+  void WriteUnsigned64(uint64_t value) { stream_.WriteUnsigned(value); }
+
+  void WriteWordWith32BitWrites(uword value) {
+    stream_.WriteWordWith32BitWrites(value);
+  }
+
   void WriteBytes(const uint8_t* addr, intptr_t len) {
     stream_.WriteBytes(addr, len);
   }
@@ -496,8 +502,11 @@
     return ReadStream::Raw<sizeof(T), T>::Read(&stream_);
   }
   intptr_t ReadUnsigned() { return stream_.ReadUnsigned(); }
+  uint64_t ReadUnsigned64() { return stream_.ReadUnsigned<uint64_t>(); }
   void ReadBytes(uint8_t* addr, intptr_t len) { stream_.ReadBytes(addr, len); }
 
+  uword ReadWordWith32BitReads() { return stream_.ReadWordWith32BitReads(); }
+
   const uint8_t* CurrentBufferAddress() const {
     return stream_.AddressOfCurrentPosition();
   }
diff --git a/runtime/vm/compiler/backend/il.h b/runtime/vm/compiler/backend/il.h
index 377874f..4c6bd4e 100644
--- a/runtime/vm/compiler/backend/il.h
+++ b/runtime/vm/compiler/backend/il.h
@@ -511,6 +511,7 @@
 #undef FORWARD_DECLARATION
 
 #define DEFINE_INSTRUCTION_TYPE_CHECK(type)                                    \
+  virtual type##Instr* As##type() { return this; }                             \
   virtual const type##Instr* As##type() const { return this; }                 \
   virtual const char* DebugName() const { return #type; }
 
@@ -5497,7 +5498,7 @@
   }
 
   static bool WillAllocateNewOrRemembered(const Class& cls) {
-    return Heap::IsAllocatableInNewSpace(cls.instance_size());
+    return Heap::IsAllocatableInNewSpace(cls.target_instance_size());
   }
 
   PRINT_OPERANDS_TO_SUPPORT
@@ -6238,6 +6239,8 @@
 
   virtual void InferRange(RangeAnalysis* analysis, Range* range);
 
+  virtual SpeculativeMode speculative_mode() const { return kNotSpeculative; }
+
   virtual CompileType ComputeType() const;
   virtual bool RecomputeType();
 
diff --git a/runtime/vm/compiler/backend/il_arm.cc b/runtime/vm/compiler/backend/il_arm.cc
index 6c43554..235b683 100644
--- a/runtime/vm/compiler/backend/il_arm.cc
+++ b/runtime/vm/compiler/backend/il_arm.cc
@@ -2557,7 +2557,8 @@
                                                               bool opt) const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps =
-      ((IsUnboxedStore() && opt) ? 2 : ((IsPotentialUnboxedStore()) ? 3 : 0));
+      ((IsUnboxedStore() && opt) ? (FLAG_precompiled_mode ? 0 : 2)
+                                 : (IsPotentialUnboxedStore() ? 3 : 0));
   LocationSummary* summary = new (zone)
       LocationSummary(zone, kNumInputs, kNumTemps,
                       ((IsUnboxedStore() && opt && is_initialization()) ||
@@ -2568,8 +2569,10 @@
   summary->set_in(0, Location::RequiresRegister());
   if (IsUnboxedStore() && opt) {
     summary->set_in(1, Location::RequiresFpuRegister());
-    summary->set_temp(0, Location::RequiresRegister());
-    summary->set_temp(1, Location::RequiresRegister());
+    if (!FLAG_precompiled_mode) {
+      summary->set_temp(0, Location::RequiresRegister());
+      summary->set_temp(1, Location::RequiresRegister());
+    }
   } else if (IsPotentialUnboxedStore()) {
     summary->set_in(1, ShouldEmitStoreBarrier() ? Location::WritableRegister()
                                                 : Location::RequiresRegister());
@@ -2615,10 +2618,33 @@
   ASSERT(offset_in_bytes > 0);  // Field is finalized and points after header.
 
   if (IsUnboxedStore() && compiler->is_optimizing()) {
+    const intptr_t cid = slot().field().UnboxedFieldCid();
     const DRegister value = EvenDRegisterOf(locs()->in(1).fpu_reg());
+
+    if (FLAG_precompiled_mode) {
+      switch (cid) {
+        case kDoubleCid:
+          __ Comment("UnboxedDoubleStoreInstanceFieldInstr");
+          __ StoreDToOffset(value, instance_reg,
+                            offset_in_bytes - kHeapObjectTag);
+          return;
+        case kFloat32x4Cid:
+          __ Comment("UnboxedFloat32x4StoreInstanceFieldInstr");
+          __ StoreMultipleDToOffset(value, 2, instance_reg,
+                                    offset_in_bytes - kHeapObjectTag);
+          return;
+        case kFloat64x2Cid:
+          __ Comment("UnboxedFloat64x2StoreInstanceFieldInstr");
+          __ StoreMultipleDToOffset(value, 2, instance_reg,
+                                    offset_in_bytes - kHeapObjectTag);
+          return;
+        default:
+          UNREACHABLE();
+      }
+    }
+
     const Register temp = locs()->temp(0).reg();
     const Register temp2 = locs()->temp(1).reg();
-    const intptr_t cid = slot().field().UnboxedFieldCid();
 
     if (is_initialization()) {
       const Class* cls = NULL;
@@ -2963,8 +2989,9 @@
 LocationSummary* LoadFieldInstr::MakeLocationSummary(Zone* zone,
                                                      bool opt) const {
   const intptr_t kNumInputs = 1;
-  const intptr_t kNumTemps =
-      (IsUnboxedLoad() && opt) ? 1 : ((IsPotentialUnboxedLoad()) ? 3 : 0);
+  const intptr_t kNumTemps = (IsUnboxedLoad() && opt)
+                                 ? (FLAG_precompiled_mode ? 0 : 1)
+                                 : (IsPotentialUnboxedLoad() ? 3 : 0);
 
   LocationSummary* locs = new (zone) LocationSummary(
       zone, kNumInputs, kNumTemps,
@@ -2974,7 +3001,9 @@
   locs->set_in(0, Location::RequiresRegister());
 
   if (IsUnboxedLoad() && opt) {
-    locs->set_temp(0, Location::RequiresRegister());
+    if (!FLAG_precompiled_mode) {
+      locs->set_temp(0, Location::RequiresRegister());
+    }
   } else if (IsPotentialUnboxedLoad()) {
     locs->set_temp(0, opt ? Location::RequiresFpuRegister()
                           : Location::FpuRegisterLocation(Q1));
@@ -2990,10 +3019,33 @@
 
   const Register instance_reg = locs()->in(0).reg();
   if (IsUnboxedLoad() && compiler->is_optimizing()) {
+    const intptr_t cid = slot().field().UnboxedFieldCid();
     const DRegister result = EvenDRegisterOf(locs()->out(0).fpu_reg());
+
+    if (FLAG_precompiled_mode) {
+      switch (cid) {
+        case kDoubleCid:
+          __ Comment("UnboxedDoubleLoadFieldInstr");
+          __ LoadDFromOffset(result, instance_reg,
+                             OffsetInBytes() - kHeapObjectTag);
+          return;
+        case kFloat32x4Cid:
+          __ Comment("UnboxedFloat32x4LoadFieldInstr");
+          __ LoadMultipleDFromOffset(result, 2, instance_reg,
+                                     OffsetInBytes() - kHeapObjectTag);
+          return;
+        case kFloat64x2Cid:
+          __ Comment("UnboxedFloat64x2LoadFieldInstr");
+          __ LoadMultipleDFromOffset(result, 2, instance_reg,
+                                     OffsetInBytes() - kHeapObjectTag);
+          return;
+        default:
+          UNREACHABLE();
+      }
+    }
+
     const Register temp = locs()->temp(0).reg();
     __ LoadFieldFromOffset(kWord, temp, instance_reg, OffsetInBytes());
-    const intptr_t cid = slot().field().UnboxedFieldCid();
     switch (cid) {
       case kDoubleCid:
         __ Comment("UnboxedDoubleLoadFieldInstr");
@@ -3320,7 +3372,7 @@
   Register temp = locs()->temp(0).reg();
   compiler::Label no_call;
 
-  __ ldr(temp, compiler::FieldAddress(instance, field().Offset()));
+  __ ldr(temp, compiler::FieldAddress(instance, field().TargetOffset()));
   __ CompareObject(temp, Object::sentinel());
   __ b(&no_call, NE);
 
diff --git a/runtime/vm/compiler/backend/il_arm64.cc b/runtime/vm/compiler/backend/il_arm64.cc
index 405bc32..9894048 100644
--- a/runtime/vm/compiler/backend/il_arm64.cc
+++ b/runtime/vm/compiler/backend/il_arm64.cc
@@ -2158,8 +2158,9 @@
 LocationSummary* StoreInstanceFieldInstr::MakeLocationSummary(Zone* zone,
                                                               bool opt) const {
   const intptr_t kNumInputs = 2;
-  const intptr_t kNumTemps =
-      (IsUnboxedStore() && opt) ? 2 : ((IsPotentialUnboxedStore()) ? 2 : 0);
+  const intptr_t kNumTemps = (IsUnboxedStore() && opt)
+                                 ? (FLAG_precompiled_mode ? 0 : 2)
+                                 : (IsPotentialUnboxedStore() ? 2 : 0);
   LocationSummary* summary = new (zone)
       LocationSummary(zone, kNumInputs, kNumTemps,
                       ((IsUnboxedStore() && opt && is_initialization()) ||
@@ -2170,8 +2171,10 @@
   summary->set_in(0, Location::RequiresRegister());
   if (IsUnboxedStore() && opt) {
     summary->set_in(1, Location::RequiresFpuRegister());
-    summary->set_temp(0, Location::RequiresRegister());
-    summary->set_temp(1, Location::RequiresRegister());
+    if (!FLAG_precompiled_mode) {
+      summary->set_temp(0, Location::RequiresRegister());
+      summary->set_temp(1, Location::RequiresRegister());
+    }
   } else if (IsPotentialUnboxedStore()) {
     summary->set_in(1, ShouldEmitStoreBarrier() ? Location::WritableRegister()
                                                 : Location::RequiresRegister());
@@ -2195,9 +2198,29 @@
 
   if (IsUnboxedStore() && compiler->is_optimizing()) {
     const VRegister value = locs()->in(1).fpu_reg();
+    const intptr_t cid = slot().field().UnboxedFieldCid();
+
+    if (FLAG_precompiled_mode) {
+      switch (cid) {
+        case kDoubleCid:
+          __ Comment("UnboxedDoubleStoreInstanceFieldInstr");
+          __ StoreDFieldToOffset(value, instance_reg, offset_in_bytes);
+          return;
+        case kFloat32x4Cid:
+          __ Comment("UnboxedFloat32x4StoreInstanceFieldInstr");
+          __ StoreQFieldToOffset(value, instance_reg, offset_in_bytes);
+          return;
+        case kFloat64x2Cid:
+          __ Comment("UnboxedFloat64x2StoreInstanceFieldInstr");
+          __ StoreQFieldToOffset(value, instance_reg, offset_in_bytes);
+          return;
+        default:
+          UNREACHABLE();
+      }
+    }
+
     const Register temp = locs()->temp(0).reg();
     const Register temp2 = locs()->temp(1).reg();
-    const intptr_t cid = slot().field().UnboxedFieldCid();
 
     if (is_initialization()) {
       const Class* cls = NULL;
@@ -2534,8 +2557,9 @@
 LocationSummary* LoadFieldInstr::MakeLocationSummary(Zone* zone,
                                                      bool opt) const {
   const intptr_t kNumInputs = 1;
-  const intptr_t kNumTemps =
-      (IsUnboxedLoad() && opt) ? 1 : ((IsPotentialUnboxedLoad()) ? 1 : 0);
+  const intptr_t kNumTemps = (IsUnboxedLoad() && opt)
+                                 ? (FLAG_precompiled_mode ? 0 : 1)
+                                 : (IsPotentialUnboxedLoad() ? 1 : 0);
   LocationSummary* locs = new (zone) LocationSummary(
       zone, kNumInputs, kNumTemps,
       (opt && !IsPotentialUnboxedLoad()) ? LocationSummary::kNoCall
@@ -2544,7 +2568,9 @@
   locs->set_in(0, Location::RequiresRegister());
 
   if (IsUnboxedLoad() && opt) {
-    locs->set_temp(0, Location::RequiresRegister());
+    if (!FLAG_precompiled_mode) {
+      locs->set_temp(0, Location::RequiresRegister());
+    }
   } else if (IsPotentialUnboxedLoad()) {
     locs->set_temp(0, Location::RequiresRegister());
   }
@@ -2557,9 +2583,30 @@
   const Register instance_reg = locs()->in(0).reg();
   if (IsUnboxedLoad() && compiler->is_optimizing()) {
     const VRegister result = locs()->out(0).fpu_reg();
-    const Register temp = locs()->temp(0).reg();
-    __ LoadFieldFromOffset(temp, instance_reg, OffsetInBytes());
     const intptr_t cid = slot().field().UnboxedFieldCid();
+
+    if (FLAG_precompiled_mode) {
+      switch (cid) {
+        case kDoubleCid:
+          __ Comment("UnboxedDoubleLoadFieldInstr");
+          __ LoadDFieldFromOffset(result, instance_reg, OffsetInBytes());
+          return;
+        case kFloat32x4Cid:
+          __ Comment("UnboxedFloat32x4LoadFieldInstr");
+          __ LoadQFieldFromOffset(result, instance_reg, OffsetInBytes());
+          return;
+        case kFloat64x2Cid:
+          __ Comment("UnboxedFloat64x2LoadFieldInstr");
+          __ LoadQFieldFromOffset(result, instance_reg, OffsetInBytes());
+          return;
+        default:
+          UNREACHABLE();
+      }
+    }
+
+    const Register temp = locs()->temp(0).reg();
+
+    __ LoadFieldFromOffset(temp, instance_reg, OffsetInBytes());
     switch (cid) {
       case kDoubleCid:
         __ Comment("UnboxedDoubleLoadFieldInstr");
@@ -2875,7 +2922,7 @@
   Register temp = locs()->temp(0).reg();
   compiler::Label no_call;
 
-  __ ldr(temp, compiler::FieldAddress(instance, field().Offset()));
+  __ ldr(temp, compiler::FieldAddress(instance, field().TargetOffset()));
   __ CompareObject(temp, Object::sentinel());
   __ b(&no_call, NE);
 
diff --git a/runtime/vm/compiler/backend/il_ia32.cc b/runtime/vm/compiler/backend/il_ia32.cc
index c02b5e7..28a4d59 100644
--- a/runtime/vm/compiler/backend/il_ia32.cc
+++ b/runtime/vm/compiler/backend/il_ia32.cc
@@ -2753,7 +2753,7 @@
 
   compiler::Label no_call;
 
-  __ movl(temp, compiler::FieldAddress(instance, field().Offset()));
+  __ movl(temp, compiler::FieldAddress(instance, field().TargetOffset()));
   __ CompareObject(temp, Object::sentinel());
   __ j(NOT_EQUAL, &no_call, compiler::Assembler::kNearJump);
 
diff --git a/runtime/vm/compiler/backend/il_serializer.cc b/runtime/vm/compiler/backend/il_serializer.cc
index 2ec431ae..b873992 100644
--- a/runtime/vm/compiler/backend/il_serializer.cc
+++ b/runtime/vm/compiler/backend/il_serializer.cc
@@ -1308,7 +1308,7 @@
     SExpList* sexp,
     FlowGraphSerializer* s) const {
   Instruction::AddExtraInfoToSExpression(sexp, s);
-  s->AddExtraInteger(sexp, "size", cls().instance_size());
+  s->AddExtraInteger(sexp, "size", cls().target_instance_size());
   if (auto const closure = s->DartValueToSExp(closure_function())) {
     sexp->AddExtra("closure_function", closure);
   }
diff --git a/runtime/vm/compiler/backend/il_x64.cc b/runtime/vm/compiler/backend/il_x64.cc
index 4b9cfcd..9af1adc 100644
--- a/runtime/vm/compiler/backend/il_x64.cc
+++ b/runtime/vm/compiler/backend/il_x64.cc
@@ -2128,8 +2128,9 @@
 LocationSummary* StoreInstanceFieldInstr::MakeLocationSummary(Zone* zone,
                                                               bool opt) const {
   const intptr_t kNumInputs = 2;
-  const intptr_t kNumTemps =
-      (IsUnboxedStore() && opt) ? 2 : ((IsPotentialUnboxedStore()) ? 3 : 0);
+  const intptr_t kNumTemps = (IsUnboxedStore() && opt)
+                                 ? (FLAG_precompiled_mode ? 0 : 2)
+                                 : (IsPotentialUnboxedStore() ? 3 : 0);
   LocationSummary* summary = new (zone)
       LocationSummary(zone, kNumInputs, kNumTemps,
                       ((IsUnboxedStore() && opt && is_initialization()) ||
@@ -2140,8 +2141,10 @@
   summary->set_in(0, Location::RequiresRegister());
   if (IsUnboxedStore() && opt) {
     summary->set_in(1, Location::RequiresFpuRegister());
-    summary->set_temp(0, Location::RequiresRegister());
-    summary->set_temp(1, Location::RequiresRegister());
+    if (!FLAG_precompiled_mode) {
+      summary->set_temp(0, Location::RequiresRegister());
+      summary->set_temp(1, Location::RequiresRegister());
+    }
   } else if (IsPotentialUnboxedStore()) {
     summary->set_in(1, ShouldEmitStoreBarrier() ? Location::WritableRegister()
                                                 : Location::RequiresRegister());
@@ -2186,9 +2189,33 @@
 
   if (IsUnboxedStore() && compiler->is_optimizing()) {
     XmmRegister value = locs()->in(1).fpu_reg();
+    const intptr_t cid = slot().field().UnboxedFieldCid();
+
+    // Real unboxed field
+    if (FLAG_precompiled_mode) {
+      switch (cid) {
+        case kDoubleCid:
+          __ Comment("UnboxedDoubleStoreInstanceFieldInstr");
+          __ movsd(compiler::FieldAddress(instance_reg, offset_in_bytes),
+                   value);
+          return;
+        case kFloat32x4Cid:
+          __ Comment("UnboxedFloat32x4StoreInstanceFieldInstr");
+          __ movups(compiler::FieldAddress(instance_reg, offset_in_bytes),
+                    value);
+          return;
+        case kFloat64x2Cid:
+          __ Comment("UnboxedFloat64x2StoreInstanceFieldInstr");
+          __ movups(compiler::FieldAddress(instance_reg, offset_in_bytes),
+                    value);
+          return;
+        default:
+          UNREACHABLE();
+      }
+    }
+
     Register temp = locs()->temp(0).reg();
     Register temp2 = locs()->temp(1).reg();
-    const intptr_t cid = slot().field().UnboxedFieldCid();
 
     if (is_initialization()) {
       const Class* cls = NULL;
@@ -2533,8 +2560,9 @@
 LocationSummary* LoadFieldInstr::MakeLocationSummary(Zone* zone,
                                                      bool opt) const {
   const intptr_t kNumInputs = 1;
-  const intptr_t kNumTemps =
-      (IsUnboxedLoad() && opt) ? 1 : ((IsPotentialUnboxedLoad()) ? 2 : 0);
+  const intptr_t kNumTemps = (IsUnboxedLoad() && opt)
+                                 ? (FLAG_precompiled_mode ? 0 : 1)
+                                 : (IsPotentialUnboxedLoad() ? 2 : 0);
   LocationSummary* locs = new (zone) LocationSummary(
       zone, kNumInputs, kNumTemps,
       (opt && !IsPotentialUnboxedLoad()) ? LocationSummary::kNoCall
@@ -2543,7 +2571,9 @@
   locs->set_in(0, Location::RequiresRegister());
 
   if (IsUnboxedLoad() && opt) {
-    locs->set_temp(0, Location::RequiresRegister());
+    if (!FLAG_precompiled_mode) {
+      locs->set_temp(0, Location::RequiresRegister());
+    }
   } else if (IsPotentialUnboxedLoad()) {
     locs->set_temp(0, opt ? Location::RequiresFpuRegister()
                           : Location::FpuRegisterLocation(XMM1));
@@ -2558,9 +2588,34 @@
   Register instance_reg = locs()->in(0).reg();
   if (IsUnboxedLoad() && compiler->is_optimizing()) {
     XmmRegister result = locs()->out(0).fpu_reg();
+    const intptr_t cid = slot().field().UnboxedFieldCid();
+
+    // Real unboxed field
+    if (FLAG_precompiled_mode) {
+      switch (cid) {
+        case kDoubleCid:
+          __ Comment("UnboxedDoubleLoadFieldInstr");
+          __ movsd(result,
+                   compiler::FieldAddress(instance_reg, OffsetInBytes()));
+          break;
+        case kFloat32x4Cid:
+          __ Comment("UnboxedFloat32x4LoadFieldInstr");
+          __ movups(result,
+                    compiler::FieldAddress(instance_reg, OffsetInBytes()));
+          break;
+        case kFloat64x2Cid:
+          __ Comment("UnboxedFloat64x2LoadFieldInstr");
+          __ movups(result,
+                    compiler::FieldAddress(instance_reg, OffsetInBytes()));
+          break;
+        default:
+          UNREACHABLE();
+      }
+      return;
+    }
+
     Register temp = locs()->temp(0).reg();
     __ movq(temp, compiler::FieldAddress(instance_reg, OffsetInBytes()));
-    intptr_t cid = slot().field().UnboxedFieldCid();
     switch (cid) {
       case kDoubleCid:
         __ Comment("UnboxedDoubleLoadFieldInstr");
@@ -2890,7 +2945,7 @@
 
   compiler::Label no_call;
 
-  __ movq(temp, compiler::FieldAddress(instance, field().Offset()));
+  __ movq(temp, compiler::FieldAddress(instance, field().TargetOffset()));
   __ CompareObject(temp, Object::sentinel());
   __ j(NOT_EQUAL, &no_call, compiler::Assembler::kNearJump);
 
diff --git a/runtime/vm/compiler/backend/inliner.cc b/runtime/vm/compiler/backend/inliner.cc
index 91c1896..1baea96 100644
--- a/runtime/vm/compiler/backend/inliner.cc
+++ b/runtime/vm/compiler/backend/inliner.cc
@@ -3474,6 +3474,27 @@
   if (!ShouldInlineSimd()) {
     return false;
   }
+  bool is_dynamic_call = false;
+  if (auto instance_call = call->AsInstanceCallBase()) {
+    is_dynamic_call = Function::IsDynamicInvocationForwarderName(
+        instance_call->function_name());
+  } else if (auto static_call = call->AsStaticCall()) {
+    is_dynamic_call = static_call->function().IsDynamicInvocationForwarder();
+  }
+  if (is_dynamic_call && call->ArgumentCount() > 1) {
+    // Issue(dartbug.com/37737): Dynamic invocation forwarders have the
+    // same recognized kind as the method they are forwarding to.
+    // That causes us to inline the recognized method and not the
+    // dyn: forwarder itself.
+    // This is only safe if all arguments are checked in the flow graph we
+    // build.
+    // For double/int arguments speculative unboxing instructions should ensure
+    // to bailout in AOT (or deoptimize in JIT) if the incoming values are not
+    // correct. Though for user-implementable types, like
+    // operator+(Float32x4 other), this is not safe and we therefore bailout.
+    return false;
+  }
+
   *entry =
       new (Z) FunctionEntryInstr(graph_entry, flow_graph->allocate_block_id(),
                                  call->GetBlock()->try_index(), DeoptId::kNone);
@@ -3572,6 +3593,13 @@
   if (!CanUnboxDouble()) {
     return false;
   }
+
+  for (intptr_t i = 0; i < call->ArgumentCount(); i++) {
+    if (call->ArgumentAt(i)->Type()->ToCid() != kDoubleCid) {
+      return false;
+    }
+  }
+
   *entry =
       new (Z) FunctionEntryInstr(graph_entry, flow_graph->allocate_block_id(),
                                  call->GetBlock()->try_index(), DeoptId::kNone);
diff --git a/runtime/vm/compiler/frontend/bytecode_flow_graph_builder.cc b/runtime/vm/compiler/frontend/bytecode_flow_graph_builder.cc
index 42006a5..58641e6 100644
--- a/runtime/vm/compiler/frontend/bytecode_flow_graph_builder.cc
+++ b/runtime/vm/compiler/frontend/bytecode_flow_graph_builder.cc
@@ -1151,7 +1151,7 @@
 }
 
 const Slot& ClosureSlotByField(const Field& field) {
-  const intptr_t offset = field.Offset();
+  const intptr_t offset = field.HostOffset();
   if (offset == Closure::instantiator_type_arguments_offset()) {
     return Slot::Closure_instantiator_type_arguments();
   } else if (offset == Closure::function_type_arguments_offset()) {
@@ -1178,7 +1178,7 @@
 
   const Field& field = Field::Cast(ConstantAt(cp_index, 1).value());
   ASSERT(Smi::Cast(ConstantAt(cp_index).value()).Value() * kWordSize ==
-         field.Offset());
+         field.HostOffset());
 
   if (field.Owner() == isolate()->object_store()->closure_class()) {
     // Stores to _Closure fields are lower-level.
@@ -1204,7 +1204,7 @@
 
   const Field& field = Field::Cast(ConstantAt(cp_index, 1).value());
   ASSERT(Smi::Cast(ConstantAt(cp_index).value()).Value() * kWordSize ==
-         field.Offset());
+         field.HostOffset());
 
   if (field.Owner() == isolate()->object_store()->closure_class()) {
     // Loads from _Closure fields are lower-level.
@@ -1292,7 +1292,7 @@
 
   const Field& field = Field::Cast(ConstantAt(cp_index, 1).value());
   ASSERT(Smi::Cast(ConstantAt(cp_index).value()).Value() * kWordSize ==
-         field.Offset());
+         field.HostOffset());
 
   code_ += B->Constant(Object::sentinel());
   code_ += B->StoreInstanceField(
diff --git a/runtime/vm/compiler/frontend/bytecode_reader.cc b/runtime/vm/compiler/frontend/bytecode_reader.cc
index f14cd8b..616e9f3 100644
--- a/runtime/vm/compiler/frontend/bytecode_reader.cc
+++ b/runtime/vm/compiler/frontend/bytecode_reader.cc
@@ -748,7 +748,7 @@
         field ^= ReadObject();
         // InstanceField constant occupies 2 entries.
         // The first entry is used for field offset.
-        obj = Smi::New(field.Offset() / kWordSize);
+        obj = Smi::New(field.HostOffset() / kWordSize);
         pool.SetTypeAt(i, ObjectPool::EntryType::kTaggedObject,
                        ObjectPool::Patchability::kNotPatchable);
         pool.SetObjectAt(i, obj);
@@ -763,7 +763,7 @@
         break;
       case ConstantPoolTag::kTypeArgumentsField:
         cls ^= ReadObject();
-        obj = Smi::New(cls.type_arguments_field_offset() / kWordSize);
+        obj = Smi::New(cls.host_type_arguments_field_offset() / kWordSize);
         break;
       case ConstantPoolTag::kType:
         obj = ReadObject();
diff --git a/runtime/vm/compiler/frontend/bytecode_scope_builder.cc b/runtime/vm/compiler/frontend/bytecode_scope_builder.cc
index fbc39dd..bd0b3ec 100644
--- a/runtime/vm/compiler/frontend/bytecode_scope_builder.cc
+++ b/runtime/vm/compiler/frontend/bytecode_scope_builder.cc
@@ -82,6 +82,7 @@
     case RawFunction::kImplicitSetter: {
       const bool is_setter = function.IsImplicitSetterFunction();
       const bool is_method = !function.IsStaticFunction();
+      const Field& field = Field::Handle(Z, function.accessor_field());
       intptr_t pos = 0;
       if (is_method) {
         MakeReceiverVariable(/* is_parameter = */ true);
@@ -94,7 +95,6 @@
         scope_->InsertParameterAt(pos++, setter_value);
 
         if (is_method) {
-          const Field& field = Field::Handle(Z, function.accessor_field());
           if (field.is_covariant()) {
             setter_value->set_is_explicit_covariant_parameter();
           } else {
@@ -107,12 +107,24 @@
             }
           }
         }
+      } else {
+        if (field.is_late()) {
+          // LoadLateField uses expression_temp_var.
+          needs_expr_temp = true;
+        }
       }
       break;
     }
-    case RawFunction::kImplicitStaticGetter:
+    case RawFunction::kImplicitStaticGetter: {
       ASSERT(!IsStaticFieldGetterGeneratedAsInitializer(function, Z));
+      const Field& field = Field::Handle(Z, function.accessor_field());
+      const bool lib_is_nnbd = function.nnbd_mode() == NNBDMode::kOptedInLib;
+      if (field.is_late() || lib_is_nnbd) {
+        // LoadLateField uses expression_temp_var.
+        needs_expr_temp = true;
+      }
       break;
+    }
     case RawFunction::kDynamicInvocationForwarder: {
       // Create [this] variable.
       MakeReceiverVariable(/* is_parameter = */ true);
diff --git a/runtime/vm/compiler/frontend/constant_reader.cc b/runtime/vm/compiler/frontend/constant_reader.cc
index 9646b59..69a1e73 100644
--- a/runtime/vm/compiler/frontend/constant_reader.cc
+++ b/runtime/vm/compiler/frontend/constant_reader.cc
@@ -220,6 +220,7 @@
       }
       const auto& obj = Object::Handle(Z, klass.EnsureIsFinalized(H.thread()));
       ASSERT(obj.IsNull());
+      ASSERT(klass.is_const());
       instance = Instance::New(klass, Heap::kOld);
       // Build type from the raw bytes (needs temporary translator).
       TypeTranslator type_translator(&reader, active_class_, true);
diff --git a/runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc b/runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc
index 6441249..3db08e1 100644
--- a/runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc
+++ b/runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc
@@ -200,6 +200,10 @@
     }
     return Fragment();
   }
+  // Late fields are initialized to Object::sentinel, which is a flavor of null.
+  // So we need to record that store so that the field guard doesn't prematurely
+  // optimise out the late field's sentinel checking logic.
+  field.RecordStore(Object::null_object());
 
   Fragment instructions;
   instructions += LoadLocal(parsed_function()->receiver_var());
@@ -3568,6 +3572,11 @@
   TokenPosition position = ReadPosition();  // read position.
   if (p != NULL) *p = position;
 
+  if (translation_helper_.info().kernel_binary_version() >= 38) {
+    // TODO(alexmarkov): Handle flags.
+    ReadFlags();  // read flags.
+  }
+
   Fragment instructions = BuildExpression();  // read operand.
 
   const AbstractType& type = T.BuildType();  // read type.
@@ -3619,6 +3628,7 @@
   TokenPosition position = ReadPosition();  // read position.
   if (p != NULL) *p = position;
 
+  // TODO(alexmarkov): Handle new flags.
   const uint8_t flags = ReadFlags();  // read flags.
   const bool is_type_error = (flags & (1 << 0)) != 0;
 
diff --git a/runtime/vm/compiler/frontend/kernel_fingerprints.cc b/runtime/vm/compiler/frontend/kernel_fingerprints.cc
index cf6f13d..4247dae 100644
--- a/runtime/vm/compiler/frontend/kernel_fingerprints.cc
+++ b/runtime/vm/compiler/frontend/kernel_fingerprints.cc
@@ -464,6 +464,9 @@
       return;
     case kIsExpression:
       ReadPosition();                    // read position.
+      if (translation_helper_.info().kernel_binary_version() >= 38) {
+        BuildHash(ReadFlags());  // read flags.
+      }
       CalculateExpressionFingerprint();  // read operand.
       CalculateDartTypeFingerprint();    // read type.
       return;
diff --git a/runtime/vm/compiler/frontend/kernel_to_il.cc b/runtime/vm/compiler/frontend/kernel_to_il.cc
index c857a50..2a4574d 100644
--- a/runtime/vm/compiler/frontend/kernel_to_il.cc
+++ b/runtime/vm/compiler/frontend/kernel_to_il.cc
@@ -453,8 +453,9 @@
     instructions += LoadLocal(instance);
     instructions += LoadField(field);
   }
-  LocalVariable* temp = MakeTemporary();
-  instructions += LoadLocal(temp);
+
+  LocalVariable* temp = parsed_function_->expression_temp_var();
+  instructions += StoreLocal(position, temp);
   instructions += Constant(Object::sentinel());
   instructions += BranchIfStrictEqual(&is_uninitialized, &is_initialized);
 
@@ -496,7 +497,9 @@
   }
 
   // Now that the field has been initialized, load it.
-  return Fragment(instructions.entry, join);
+  instructions = Fragment(instructions.entry, join);
+  instructions += LoadLocal(temp);
+  return instructions;
 }
 
 Fragment FlowGraphBuilder::ThrowLateInitializationError(TokenPosition position,
diff --git a/runtime/vm/compiler/frontend/kernel_translation_helper.cc b/runtime/vm/compiler/frontend/kernel_translation_helper.cc
index 30f762e..9c916a1 100644
--- a/runtime/vm/compiler/frontend/kernel_translation_helper.cc
+++ b/runtime/vm/compiler/frontend/kernel_translation_helper.cc
@@ -2257,6 +2257,9 @@
       return;
     case kIsExpression:
       ReadPosition();    // read position.
+      if (translation_helper_.info().kernel_binary_version() >= 38) {
+        SkipFlags();  // read flags.
+      }
       SkipExpression();  // read operand.
       SkipDartType();    // read type.
       return;
@@ -2962,9 +2965,11 @@
   if (parameter_index < class_types.Length()) {
     // The index of the type parameter in [parameters] is
     // the same index into the `klass->type_parameters()` array.
-    result_ = class_types.TypeAt(parameter_index);
-    result_ =
-        TypeParameter::Cast(result_).ToNullability(nullability, Heap::kOld);
+    const auto& type_param =
+        TypeParameter::CheckedHandle(Z, class_types.TypeAt(parameter_index));
+    result_ = type_param.ToNullability(nullability, Heap::kOld);
+    active_class_->RecordDerivedTypeParameter(Z, type_param,
+                                              TypeParameter::Cast(result_));
     return;
   }
   parameter_index -= class_types.Length();
@@ -2989,9 +2994,11 @@
       //   }
       //
       if (class_types.Length() > parameter_index) {
-        result_ = class_types.TypeAt(parameter_index);
-        result_ =
-            TypeParameter::Cast(result_).ToNullability(nullability, Heap::kOld);
+        const auto& type_param = TypeParameter::CheckedHandle(
+            Z, class_types.TypeAt(parameter_index));
+        result_ = type_param.ToNullability(nullability, Heap::kOld);
+        active_class_->RecordDerivedTypeParameter(Z, type_param,
+                                                  TypeParameter::Cast(result_));
         return;
       }
       parameter_index -= class_types.Length();
@@ -3004,11 +3011,13 @@
             : 0;
     if (procedure_type_parameter_count > 0) {
       if (procedure_type_parameter_count > parameter_index) {
-        result_ =
+        const auto& type_param = TypeParameter::CheckedHandle(
+            Z,
             TypeArguments::Handle(Z, active_class_->member->type_parameters())
-                .TypeAt(parameter_index);
-        result_ =
-            TypeParameter::Cast(result_).ToNullability(nullability, Heap::kOld);
+                .TypeAt(parameter_index));
+        result_ = type_param.ToNullability(nullability, Heap::kOld);
+        active_class_->RecordDerivedTypeParameter(Z, type_param,
+                                                  TypeParameter::Cast(result_));
         if (finalize_) {
           result_ =
               ClassFinalizer::FinalizeType(*active_class_->klass, result_);
@@ -3021,9 +3030,11 @@
 
   if (active_class_->local_type_parameters != NULL) {
     if (parameter_index < active_class_->local_type_parameters->Length()) {
-      result_ = active_class_->local_type_parameters->TypeAt(parameter_index);
-      result_ =
-          TypeParameter::Cast(result_).ToNullability(nullability, Heap::kOld);
+      const auto& type_param = TypeParameter::CheckedHandle(
+          Z, active_class_->local_type_parameters->TypeAt(parameter_index));
+      result_ = type_param.ToNullability(nullability, Heap::kOld);
+      active_class_->RecordDerivedTypeParameter(Z, type_param,
+                                                TypeParameter::Cast(result_));
       if (finalize_) {
         result_ = ClassFinalizer::FinalizeType(*active_class_->klass, result_);
       }
@@ -3134,10 +3145,13 @@
     }
   }
 
+  NNBDMode nnbd_mode;
   if (set_on.IsClass()) {
     Class::Cast(set_on).set_type_parameters(type_parameters);
+    nnbd_mode = Class::Cast(set_on).nnbd_mode();
   } else {
     Function::Cast(set_on).set_type_parameters(type_parameters);
+    nnbd_mode = Function::Cast(set_on).nnbd_mode();
   }
 
   const Function* enclosing = NULL;
@@ -3158,13 +3172,39 @@
     if (tag == kDynamicType) {
       helper_->SkipDartType();  // read ith bound.
       parameter.set_bound(Type::Handle(Z, I->object_store()->object_type()));
+      if (nnbd_mode == NNBDMode::kOptedInLib) {
+        parameter.set_nullability(Nullability::kUndetermined);
+      }
     } else {
       AbstractType& bound = BuildTypeWithoutFinalization();  // read ith bound.
       parameter.set_bound(bound);
+      if (nnbd_mode == NNBDMode::kOptedInLib) {
+        parameter.set_nullability(bound.IsNullable()
+                                      ? Nullability::kUndetermined
+                                      : Nullability::kNonNullable);
+      }
     }
 
     helper.Finish();
   }
+
+  // Fix bounds in all derived type parameters (with different nullabilities).
+  if (active_class->derived_type_parameters != nullptr) {
+    auto& derived = TypeParameter::Handle(Z);
+    auto& bound = AbstractType::Handle(Z);
+    for (intptr_t i = 0, n = active_class->derived_type_parameters->Length();
+         i < n; ++i) {
+      derived ^= active_class->derived_type_parameters->At(i);
+      if (derived.bound() == AbstractType::null() &&
+          (derived.parameterized_class() == set_on.raw() ||
+           derived.parameterized_function() == set_on.raw())) {
+        ASSERT(!derived.IsFinalized());
+        parameter ^= type_parameters.TypeAt(derived.index());
+        bound = parameter.bound();
+        derived.set_bound(bound);
+      }
+    }
+  }
 }
 
 const Type& TypeTranslator::ReceiverType(const Class& klass) {
diff --git a/runtime/vm/compiler/frontend/kernel_translation_helper.h b/runtime/vm/compiler/frontend/kernel_translation_helper.h
index 375c171..3a717c7 100644
--- a/runtime/vm/compiler/frontend/kernel_translation_helper.h
+++ b/runtime/vm/compiler/frontend/kernel_translation_helper.h
@@ -1198,6 +1198,19 @@
     return klass->NumTypeArguments();
   }
 
+  void RecordDerivedTypeParameter(Zone* zone,
+                                  const TypeParameter& original,
+                                  const TypeParameter& derived) {
+    if (original.raw() != derived.raw() &&
+        original.bound() == AbstractType::null()) {
+      if (derived_type_parameters == nullptr) {
+        derived_type_parameters = &GrowableObjectArray::Handle(
+            zone, GrowableObjectArray::New(Heap::kOld));
+      }
+      derived_type_parameters->Add(derived);
+    }
+  }
+
   const char* ToCString() {
     return member != NULL ? member->ToCString() : klass->ToCString();
   }
@@ -1212,6 +1225,8 @@
   const Function* enclosing;
 
   const TypeArguments* local_type_parameters;
+
+  GrowableObjectArray* derived_type_parameters = nullptr;
 };
 
 class ActiveClassScope {
diff --git a/runtime/vm/compiler/frontend/scope_builder.cc b/runtime/vm/compiler/frontend/scope_builder.cc
index 2697f58..23885c3 100644
--- a/runtime/vm/compiler/frontend/scope_builder.cc
+++ b/runtime/vm/compiler/frontend/scope_builder.cc
@@ -277,6 +277,7 @@
       ASSERT(helper_.PeekTag() == kField);
       const bool is_setter = function.IsImplicitSetterFunction();
       const bool is_method = !function.IsStaticFunction();
+      const auto& field = Field::Handle(Z, function.accessor_field());
       intptr_t pos = 0;
       if (is_method) {
         Class& klass = Class::Handle(Z, function.Owner());
@@ -288,7 +289,6 @@
         parsed_function_->set_receiver_var(variable);
       }
       if (is_setter) {
-        const auto& field = Field::Handle(Z, function.accessor_field());
         if (FLAG_precompiled_mode) {
           const intptr_t kernel_offset = field.kernel_offset();
           const InferredTypeMetadata parameter_type =
@@ -316,18 +316,29 @@
                 LocalVariable::kTypeCheckedByCaller);
           }
         }
+      } else {
+        if (field.is_late()) {
+          // LoadLateField uses expression_temp_var.
+          needs_expr_temp_ = true;
+        }
       }
       break;
     }
     case RawFunction::kImplicitStaticGetter: {
       ASSERT(helper_.PeekTag() == kField);
       ASSERT(function.IsStaticFunction());
+      const auto& field = Field::Handle(Z, function.accessor_field());
       // In addition to static field initializers, scopes/local variables
       // are needed for implicit getters of static const fields, in order to
       // be able to evaluate their initializers in constant evaluator.
       if (Field::Handle(Z, function.accessor_field()).is_const()) {
         VisitNode();
       }
+      const bool lib_is_nnbd = function.nnbd_mode() == NNBDMode::kOptedInLib;
+      if (field.is_late() || lib_is_nnbd) {
+        // LoadLateField uses expression_temp_var.
+        needs_expr_temp_ = true;
+      }
       break;
     }
     case RawFunction::kFieldInitializer: {
@@ -803,6 +814,9 @@
     }
     case kIsExpression:
       helper_.ReadPosition();  // read position.
+      if (translation_helper_.info().kernel_binary_version() >= 38) {
+        helper_.ReadFlags();  // read flags.
+      }
       VisitExpression();       // read operand.
       VisitDartType();         // read type.
       return;
diff --git a/runtime/vm/compiler/recognized_methods_list.h b/runtime/vm/compiler/recognized_methods_list.h
index 54ef994..4d90982 100644
--- a/runtime/vm/compiler/recognized_methods_list.h
+++ b/runtime/vm/compiler/recognized_methods_list.h
@@ -63,14 +63,14 @@
   V(_Int32x4ArrayView, ._, TypedData_Int32x4ArrayView_factory, 0x9bfbd6d5)     \
   V(_Float64x2ArrayView, ._, TypedData_Float64x2ArrayView_factory, 0x1a383408) \
   V(::, _toClampedUint8, ConvertIntToClampedUint8, 0x59765a4a)                 \
-  V(_StringBase, _interpolate, StringBaseInterpolate, 0xe5a934d2)              \
+  V(_StringBase, _interpolate, StringBaseInterpolate, 0xc0a650e4)              \
   V(_IntegerImplementation, toDouble, IntegerToDouble, 0x22a26db3)             \
   V(_Double, _add, DoubleAdd, 0x2f5c036a)                                      \
   V(_Double, _sub, DoubleSub, 0x6d3cec71)                                      \
   V(_Double, _mul, DoubleMul, 0x648e67af)                                      \
   V(_Double, _div, DoubleDiv, 0x6d72d7d4)                                      \
-  V(::, min, MathMin, 0x07b1ad15)                                              \
-  V(::, max, MathMax, 0xa40283bc)                                              \
+  V(::, min, MathMin, 0x935b799b)                                              \
+  V(::, max, MathMax, 0xe188dec2)                                              \
   V(::, _doublePow, MathDoublePow, 0x5ae04e61)                                 \
   V(::, _intPow, MathIntPow, 0x569ffd3f)                                       \
   V(Float32x4, _Float32x4FromDoubles, Float32x4FromDoubles, 0xbe902b89)        \
@@ -191,7 +191,7 @@
   V(_Double, >=, Double_greaterEqualThan, 0x2961f8ee)                          \
   V(_Double, <, Double_lessThan, 0xcbff42e5)                                   \
   V(_Double, <=, Double_lessEqualThan, 0xd2253d90)                             \
-  V(_Double, ==, Double_equal, 0xa7dfa02b)                                     \
+  V(_Double, ==, Double_equal, 0x6a306911)                                     \
   V(_Double, +, Double_add, 0xf7d8da94)                                        \
   V(_Double, -, Double_sub, 0xc8dda725)                                        \
   V(_Double, *, Double_mul, 0x2dac85a2)                                        \
@@ -239,7 +239,7 @@
   V(_IntegerImplementation, *, Integer_mul, 0xefe7fbce)                        \
   V(_IntegerImplementation, _moduloFromInteger, Integer_moduloFromInteger,     \
     0xbc75fece)                                                                \
-  V(_IntegerImplementation, ~/, Integer_truncDivide, 0xfb066107)               \
+  V(_IntegerImplementation, ~/, Integer_truncDivide, 0x42d9b723)               \
   V(_IntegerImplementation, unary-, Integer_negate, 0xdb5f0d70)                \
   V(_IntegerImplementation, _bitAndFromInteger, Integer_bitAndFromInteger,     \
     0xb7e724d2)                                                                \
@@ -253,7 +253,7 @@
   V(_IntegerImplementation, _greaterThanFromInteger,                           \
     Integer_greaterThanFromInt, 0x3366ff66)                                    \
   V(_IntegerImplementation, >, Integer_greaterThan, 0xe74b678c)                \
-  V(_IntegerImplementation, ==, Integer_equal, 0xb6faea0e)                     \
+  V(_IntegerImplementation, ==, Integer_equal, 0xdf47652c)                     \
   V(_IntegerImplementation, _equalToInteger, Integer_equalToInteger,           \
     0x39d3cd05)                                                                \
   V(_IntegerImplementation, <, Integer_lessThan, 0xcbff42e5)                   \
diff --git a/runtime/vm/compiler/runtime_api.cc b/runtime/vm/compiler/runtime_api.cc
index d628ac8..d24699f 100644
--- a/runtime/vm/compiler/runtime_api.cc
+++ b/runtime/vm/compiler/runtime_api.cc
@@ -3,7 +3,6 @@
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/compiler/runtime_api.h"
-#include "platform/utils.h"
 
 namespace dart {
 namespace compiler {
@@ -199,7 +198,7 @@
 }
 
 word LookupFieldOffsetInBytes(const Field& field) {
-  return field.Offset();
+  return field.TargetOffset();
 }
 
 #if defined(TARGET_ARCH_IA32)
@@ -337,10 +336,10 @@
   case kExternalTypedData##clazz##Cid:
       CLASS_LIST_TYPED_DATA(HANDLE_CASE)
 #undef HANDLE_CASE
-      return TranslateOffsetInWords(handle.instance_size());
+      return handle.target_instance_size();
     default:
       if (handle.id() >= kNumPredefinedCids) {
-        return TranslateOffsetInWords(handle.instance_size());
+        return handle.target_instance_size();
       }
   }
   FATAL3("Unsupported class for size translation: %s (id=%" Pd
@@ -359,11 +358,12 @@
 }
 
 bool Class::HasTypeArgumentsField(const dart::Class& klass) {
-  return klass.type_arguments_field_offset() != dart::Class::kNoTypeArguments;
+  return klass.host_type_arguments_field_offset() !=
+         dart::Class::kNoTypeArguments;
 }
 
 intptr_t Class::TypeArgumentsFieldOffset(const dart::Class& klass) {
-  return TranslateOffsetInWords(klass.type_arguments_field_offset());
+  return klass.target_type_arguments_field_offset();
 }
 
 bool Class::TraceAllocation(const dart::Class& klass) {
@@ -643,7 +643,7 @@
 }
 
 word Field::OffsetOf(const dart::Field& field) {
-  return TranslateOffsetInWords(field.Offset());
+  return field.TargetOffset();
 }
 
 word FieldTable::OffsetOf(const dart::Field& field) {
@@ -651,6 +651,314 @@
       dart::FieldTable::FieldOffsetFor(field.field_id()));
 }
 
+word FreeListElement::FakeInstance::InstanceSize() {
+  return 0;
+}
+
+word ForwardingCorpse::FakeInstance::InstanceSize() {
+  return 0;
+}
+
+word Instance::NextFieldOffset() {
+  return TranslateOffsetInWords(dart::Instance::NextFieldOffset());
+}
+
+word Pointer::NextFieldOffset() {
+  return TranslateOffsetInWords(dart::Pointer::NextFieldOffset());
+}
+
+word ObjectPool::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Class::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Function::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ICData::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word MegamorphicCache::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word SingleTargetCache::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Array::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word GrowableObjectArray::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word TypedDataBase::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word TypedData::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ExternalTypedData::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word TypedDataView::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word LinkedHashMap::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Type::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word TypeRef::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Double::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Mint::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word String::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word OneByteString::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word TwoByteString::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ExternalOneByteString::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ExternalTwoByteString::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Int32x4::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Float32x4::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Float64x2::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word DynamicLibrary::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word PatchClass::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word SignatureData::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word RedirectionData::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word FfiTrampolineData::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Script::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Library::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Namespace::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word KernelProgramInfo::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Bytecode::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word PcDescriptors::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word CodeSourceMap::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word CompressedStackMaps::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word LocalVarDescriptors::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ExceptionHandlers::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ContextScope::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ParameterTypeCheck::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word UnlinkedCall::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ApiError::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word LanguageError::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word UnhandledException::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word UnwindError::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Bool::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word TypeParameter::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word LibraryPrefix::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Capability::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ReceivePort::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word SendPort::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word TransferableTypedData::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word StackTrace::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Integer::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Smi::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word WeakProperty::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word MirrorReference::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Number::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word MonomorphicSmiableCall::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Instructions::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Code::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word SubtypeTestCache::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Context::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Closure::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ClosureData::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word RegExp::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word UserTag::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word Field::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word TypeArguments::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word FreeListElement::FakeInstance::NextFieldOffset() {
+  return -kWordSize;
+}
+
+word ForwardingCorpse::FakeInstance::NextFieldOffset() {
+  return -kWordSize;
+}
+
 }  // namespace target
 }  // namespace compiler
 }  // namespace dart
diff --git a/runtime/vm/compiler/runtime_api.h b/runtime/vm/compiler/runtime_api.h
index c7d5b96..4c14afd 100644
--- a/runtime/vm/compiler/runtime_api.h
+++ b/runtime/vm/compiler/runtime_api.h
@@ -19,6 +19,7 @@
 // in compiler::target namespace.
 
 #include "platform/globals.h"
+#include "platform/utils.h"
 #include "vm/allocation.h"
 #include "vm/bitfield.h"
 #include "vm/bss_relocs.h"
@@ -285,6 +286,11 @@
 extern const word kPageSizeInWords;
 extern const word kPageMask;
 
+static constexpr intptr_t kObjectAlignment = ObjectAlignment::kObjectAlignment;
+
+inline intptr_t RoundedAllocationSize(intptr_t size) {
+  return Utils::RoundUp(size, kObjectAlignment);
+}
 // Information about frame_layout that compiler should be targeting.
 extern FrameLayout frame_layout;
 
@@ -376,11 +382,15 @@
  public:
   // Return offset to the element with the given [index] in the object pool.
   static word element_offset(intptr_t index);
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Class : public AllStatic {
  public:
-  static word type_arguments_field_offset_in_words_offset();
+  static word host_type_arguments_field_offset_in_words_offset();
+
+  static word target_type_arguments_field_offset_in_words_offset();
 
   static word declaration_type_offset();
 
@@ -392,6 +402,10 @@
   // The value used if no type arguments vector is present.
   static const word kNoTypeArguments;
 
+  static word InstanceSize();
+
+  static word NextFieldOffset();
+
   // Return class id of the given class on the target.
   static classid_t GetId(const dart::Class& handle);
 
@@ -418,6 +432,7 @@
   static word DataOffsetFor(intptr_t cid);
   static word ElementSizeFor(intptr_t cid);
   static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Function : public AllStatic {
@@ -425,6 +440,8 @@
   static word code_offset();
   static word entry_point_offset(CodeEntryKind kind = CodeEntryKind::kNormal);
   static word usage_counter_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class ICData : public AllStatic {
@@ -443,6 +460,8 @@
   static word EntryPointIndexFor(word num_args);
   static word NumArgsTestedShift();
   static word NumArgsTestedMask();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class MegamorphicCache : public AllStatic {
@@ -451,6 +470,8 @@
   static word mask_offset();
   static word buckets_offset();
   static word arguments_descriptor_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class SingleTargetCache : public AllStatic {
@@ -459,6 +480,8 @@
   static word upper_limit_offset();
   static word entry_point_offset();
   static word target_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Array : public AllStatic {
@@ -469,6 +492,8 @@
   static word type_arguments_offset();
   static word length_offset();
   static word element_offset(intptr_t index);
+  static word InstanceSize();
+  static word NextFieldOffset();
 
   static const word kMaxElements;
   static const word kMaxNewSpaceElements;
@@ -480,6 +505,7 @@
   static word type_arguments_offset();
   static word length_offset();
   static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class TypedDataBase : public AllStatic {
@@ -487,23 +513,29 @@
   static word data_field_offset();
   static word length_offset();
   static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class TypedData : public AllStatic {
  public:
   static word data_offset();
   static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class ExternalTypedData : public AllStatic {
  public:
   static word data_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class TypedDataView : public AllStatic {
  public:
   static word offset_in_bytes_offset();
   static word data_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class LinkedHashMap : public AllStatic {
@@ -513,7 +545,9 @@
   static word hash_mask_offset();
   static word used_data_offset();
   static word deleted_keys_offset();
+  static word type_arguments_offset();
   static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class ArgumentsDescriptor : public AllStatic {
@@ -530,6 +564,9 @@
 class Pointer : public AllStatic {
  public:
   static word c_memory_address_offset();
+  static word type_arguments_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class AbstractType : public AllStatic {
@@ -545,11 +582,15 @@
   static word signature_offset();
   static word type_class_id_offset();
   static word nullability_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class TypeRef : public AllStatic {
  public:
   static word type_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Nullability : public AllStatic {
@@ -564,12 +605,14 @@
  public:
   static word value_offset();
   static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Mint : public AllStatic {
  public:
   static word value_offset();
   static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class String : public AllStatic {
@@ -579,43 +622,265 @@
   static word hash_offset();
   static word length_offset();
   static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class OneByteString : public AllStatic {
  public:
   static word data_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class TwoByteString : public AllStatic {
  public:
   static word data_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class ExternalOneByteString : public AllStatic {
  public:
   static word external_data_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class ExternalTwoByteString : public AllStatic {
  public:
   static word external_data_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Int32x4 : public AllStatic {
  public:
   static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Float32x4 : public AllStatic {
  public:
   static word value_offset();
   static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Float64x2 : public AllStatic {
  public:
   static word value_offset();
   static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class DynamicLibrary : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class PatchClass : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class SignatureData : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class RedirectionData : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class FfiTrampolineData : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class Script : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class Library : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class Namespace : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class KernelProgramInfo : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class Bytecode : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class PcDescriptors : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class CodeSourceMap : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class CompressedStackMaps : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class LocalVarDescriptors : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class ExceptionHandlers : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class ContextScope : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class ParameterTypeCheck : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class UnlinkedCall : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class ApiError : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class LanguageError : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class UnhandledException : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class UnwindError : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class Bool : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class TypeParameter : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class LibraryPrefix : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class Capability : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class ReceivePort : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class SendPort : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class TransferableTypedData : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class StackTrace : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class Integer : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class Smi : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class WeakProperty : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class MirrorReference : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class Number : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class TimelineStream : public AllStatic {
@@ -633,6 +898,8 @@
   static word expected_cid_offset();
   static word entrypoint_offset();
   static word target_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Thread : public AllStatic {
@@ -803,6 +1070,8 @@
   static const word kPolymorphicEntryOffsetAOT;
   static word HeaderSize();
   static word UnalignedHeaderSize();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Code : public AllStatic {
@@ -815,6 +1084,8 @@
   static word entry_point_offset(CodeEntryKind kind = CodeEntryKind::kNormal);
   static word saved_instructions_offset();
   static word owner_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class SubtypeTestCache : public AllStatic {
@@ -829,6 +1100,8 @@
   static const word kInstanceParentFunctionTypeArguments;
   static const word kInstanceDelayedFunctionTypeArguments;
   static const word kTestResult;
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Context : public AllStatic {
@@ -838,6 +1111,8 @@
   static word num_variables_offset();
   static word variable_offset(word i);
   static word InstanceSize(word n);
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Closure : public AllStatic {
@@ -849,6 +1124,13 @@
   static word instantiator_type_arguments_offset();
   static word hash_offset();
   static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class ClosureData : public AllStatic {
+ public:
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class HeapPage : public AllStatic {
@@ -883,11 +1165,15 @@
 class RegExp : public AllStatic {
  public:
   static word function_offset(classid_t cid, bool sticky);
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class UserTag : public AllStatic {
  public:
   static word tag_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class Symbols : public AllStatic {
@@ -906,12 +1192,34 @@
   static word is_nullable_offset();
   static word static_value_offset();
   static word kind_bits_offset();
+  static word InstanceSize();
+  static word NextFieldOffset();
 };
 
 class TypeArguments : public AllStatic {
  public:
   static word instantiations_offset();
   static word type_at_offset(intptr_t i);
+  static word InstanceSize();
+  static word NextFieldOffset();
+};
+
+class FreeListElement : public AllStatic {
+ public:
+  class FakeInstance : public AllStatic {
+   public:
+    static word InstanceSize();
+    static word NextFieldOffset();
+  };
+};
+
+class ForwardingCorpse : public AllStatic {
+ public:
+  class FakeInstance : public AllStatic {
+   public:
+    static word InstanceSize();
+    static word NextFieldOffset();
+  };
 };
 
 class FieldTable : public AllStatic {
diff --git a/runtime/vm/compiler/runtime_offsets_extracted.h b/runtime/vm/compiler/runtime_offsets_extracted.h
index 5617457..8774638 100644
--- a/runtime/vm/compiler/runtime_offsets_extracted.h
+++ b/runtime/vm/compiler/runtime_offsets_extracted.h
@@ -74,10 +74,10 @@
 static constexpr dart::compiler::target::word Class_declaration_type_offset =
     56;
 static constexpr dart::compiler::target::word Class_num_type_arguments_offset =
-    102;
+    90;
 static constexpr dart::compiler::target::word Class_super_type_offset = 44;
 static constexpr dart::compiler::target::word
-    Class_type_arguments_field_offset_in_words_offset = 92;
+    Class_host_type_arguments_field_offset_in_words_offset = 104;
 static constexpr dart::compiler::target::word
     ClassTable_shared_class_table_offset = 16;
 static constexpr dart::compiler::target::word ClassTable_table_offset = 8;
@@ -111,7 +111,7 @@
 static constexpr dart::compiler::target::word Field_guarded_list_length_offset =
     24;
 static constexpr dart::compiler::target::word Field_is_nullable_offset = 46;
-static constexpr dart::compiler::target::word Field_kind_bits_offset = 60;
+static constexpr dart::compiler::target::word Field_kind_bits_offset = 54;
 static constexpr dart::compiler::target::word Function_code_offset = 44;
 static constexpr dart::compiler::target::word Function_entry_point_offset[] = {
     4, 8};
@@ -146,6 +146,8 @@
 static constexpr dart::compiler::target::word LinkedHashMap_hash_mask_offset =
     12;
 static constexpr dart::compiler::target::word LinkedHashMap_index_offset = 8;
+static constexpr dart::compiler::target::word
+    LinkedHashMap_type_arguments_offset = 4;
 static constexpr dart::compiler::target::word LinkedHashMap_used_data_offset =
     20;
 static constexpr dart::compiler::target::word
@@ -171,6 +173,7 @@
 static constexpr dart::compiler::target::word OneByteString_data_offset = 12;
 static constexpr dart::compiler::target::word Pointer_c_memory_address_offset =
     8;
+static constexpr dart::compiler::target::word Pointer_type_arguments_offset = 4;
 static constexpr dart::compiler::target::word
     SingleTargetCache_entry_point_offset = 8;
 static constexpr dart::compiler::target::word
@@ -371,25 +374,100 @@
     Thread_write_barrier_wrappers_thread_offset[] = {
         628, 632, 636, 640, 644, -1, 648, 652,
         656, 660, -1,  -1,  -1,  -1, -1,  -1};
+static constexpr dart::compiler::target::word ApiError_InstanceSize = 8;
+static constexpr dart::compiler::target::word Array_InstanceSize = 12;
 static constexpr dart::compiler::target::word Array_header_size = 12;
+static constexpr dart::compiler::target::word Bool_InstanceSize = 8;
+static constexpr dart::compiler::target::word Bytecode_InstanceSize = 48;
+static constexpr dart::compiler::target::word Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word Class_InstanceSize = 128;
+static constexpr dart::compiler::target::word Closure_InstanceSize = 28;
+static constexpr dart::compiler::target::word ClosureData_InstanceSize = 20;
+static constexpr dart::compiler::target::word Code_InstanceSize = 96;
+static constexpr dart::compiler::target::word CodeSourceMap_InstanceSize = 8;
+static constexpr dart::compiler::target::word CompressedStackMaps_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word Context_InstanceSize = 12;
 static constexpr dart::compiler::target::word Context_header_size = 12;
+static constexpr dart::compiler::target::word ContextScope_InstanceSize = 12;
 static constexpr dart::compiler::target::word Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word DynamicLibrary_InstanceSize = 8;
+static constexpr dart::compiler::target::word ExceptionHandlers_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word
+    ExternalOneByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word
+    ExternalTwoByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word ExternalTypedData_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word FfiTrampolineData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word Field_InstanceSize = 64;
 static constexpr dart::compiler::target::word Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word Function_InstanceSize = 88;
+static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word ICData_InstanceSize = 32;
+static constexpr dart::compiler::target::word Instance_InstanceSize = 4;
+static constexpr dart::compiler::target::word Instructions_InstanceSize = 8;
 static constexpr dart::compiler::target::word Instructions_UnalignedHeaderSize =
     8;
 static constexpr dart::compiler::target::word Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word NativeArguments_StructSize = 16;
-static constexpr dart::compiler::target::word String_InstanceSize = 12;
-static constexpr dart::compiler::target::word TypedData_InstanceSize = 12;
-static constexpr dart::compiler::target::word Object_InstanceSize = 4;
-static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 12;
-static constexpr dart::compiler::target::word Closure_InstanceSize = 28;
-static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
-    16;
-static constexpr dart::compiler::target::word Instance_InstanceSize = 4;
+static constexpr dart::compiler::target::word Integer_InstanceSize = 4;
+static constexpr dart::compiler::target::word KernelProgramInfo_InstanceSize =
+    64;
+static constexpr dart::compiler::target::word LanguageError_InstanceSize = 28;
+static constexpr dart::compiler::target::word Library_InstanceSize = 76;
+static constexpr dart::compiler::target::word LibraryPrefix_InstanceSize = 20;
 static constexpr dart::compiler::target::word LinkedHashMap_InstanceSize = 28;
+static constexpr dart::compiler::target::word LocalVarDescriptors_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word MegamorphicCache_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word MirrorReference_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    MonomorphicSmiableCall_InstanceSize = 16;
+static constexpr dart::compiler::target::word Namespace_InstanceSize = 20;
+static constexpr dart::compiler::target::word NativeArguments_StructSize = 16;
+static constexpr dart::compiler::target::word Number_InstanceSize = 4;
+static constexpr dart::compiler::target::word Object_InstanceSize = 4;
+static constexpr dart::compiler::target::word ObjectPool_InstanceSize = 8;
+static constexpr dart::compiler::target::word OneByteString_InstanceSize = 12;
+static constexpr dart::compiler::target::word ParameterTypeCheck_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word PatchClass_InstanceSize = 24;
+static constexpr dart::compiler::target::word PcDescriptors_InstanceSize = 8;
+static constexpr dart::compiler::target::word Pointer_InstanceSize = 12;
+static constexpr dart::compiler::target::word ReceivePort_InstanceSize = 12;
+static constexpr dart::compiler::target::word RedirectionData_InstanceSize = 16;
+static constexpr dart::compiler::target::word RegExp_InstanceSize = 60;
+static constexpr dart::compiler::target::word Script_InstanceSize = 56;
+static constexpr dart::compiler::target::word SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word SignatureData_InstanceSize = 12;
+static constexpr dart::compiler::target::word SingleTargetCache_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word Smi_InstanceSize = 4;
+static constexpr dart::compiler::target::word StackTrace_InstanceSize = 20;
+static constexpr dart::compiler::target::word String_InstanceSize = 12;
+static constexpr dart::compiler::target::word SubtypeTestCache_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    TransferableTypedData_InstanceSize = 4;
+static constexpr dart::compiler::target::word TwoByteString_InstanceSize = 12;
+static constexpr dart::compiler::target::word Type_InstanceSize = 36;
+static constexpr dart::compiler::target::word TypeArguments_InstanceSize = 16;
+static constexpr dart::compiler::target::word TypeParameter_InstanceSize = 40;
+static constexpr dart::compiler::target::word TypeRef_InstanceSize = 16;
+static constexpr dart::compiler::target::word TypedData_InstanceSize = 12;
+static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 12;
+static constexpr dart::compiler::target::word TypedDataView_InstanceSize = 20;
+static constexpr dart::compiler::target::word UnhandledException_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word UnlinkedCall_InstanceSize = 16;
+static constexpr dart::compiler::target::word UnwindError_InstanceSize = 12;
+static constexpr dart::compiler::target::word UserTag_InstanceSize = 12;
+static constexpr dart::compiler::target::word WeakProperty_InstanceSize = 16;
 #endif  // defined(TARGET_ARCH_ARM)
 
 #if defined(TARGET_ARCH_X64)
@@ -451,10 +529,10 @@
 static constexpr dart::compiler::target::word Class_declaration_type_offset =
     112;
 static constexpr dart::compiler::target::word Class_num_type_arguments_offset =
-    182;
+    170;
 static constexpr dart::compiler::target::word Class_super_type_offset = 88;
 static constexpr dart::compiler::target::word
-    Class_type_arguments_field_offset_in_words_offset = 172;
+    Class_host_type_arguments_field_offset_in_words_offset = 184;
 static constexpr dart::compiler::target::word
     ClassTable_shared_class_table_offset = 32;
 static constexpr dart::compiler::target::word ClassTable_table_offset = 16;
@@ -488,7 +566,7 @@
 static constexpr dart::compiler::target::word Field_guarded_list_length_offset =
     48;
 static constexpr dart::compiler::target::word Field_is_nullable_offset = 82;
-static constexpr dart::compiler::target::word Field_kind_bits_offset = 104;
+static constexpr dart::compiler::target::word Field_kind_bits_offset = 90;
 static constexpr dart::compiler::target::word Function_code_offset = 88;
 static constexpr dart::compiler::target::word Function_entry_point_offset[] = {
     8, 16};
@@ -523,6 +601,8 @@
 static constexpr dart::compiler::target::word LinkedHashMap_hash_mask_offset =
     24;
 static constexpr dart::compiler::target::word LinkedHashMap_index_offset = 16;
+static constexpr dart::compiler::target::word
+    LinkedHashMap_type_arguments_offset = 8;
 static constexpr dart::compiler::target::word LinkedHashMap_used_data_offset =
     40;
 static constexpr dart::compiler::target::word
@@ -548,6 +628,7 @@
 static constexpr dart::compiler::target::word OneByteString_data_offset = 16;
 static constexpr dart::compiler::target::word Pointer_c_memory_address_offset =
     16;
+static constexpr dart::compiler::target::word Pointer_type_arguments_offset = 8;
 static constexpr dart::compiler::target::word
     SingleTargetCache_entry_point_offset = 16;
 static constexpr dart::compiler::target::word
@@ -750,25 +831,101 @@
     Thread_write_barrier_wrappers_thread_offset[] = {
         1248, 1256, 1264, 1272, -1,   -1,   1280, 1288,
         1296, 1304, 1312, -1,   1320, 1328, -1,   -1};
+static constexpr dart::compiler::target::word ApiError_InstanceSize = 16;
+static constexpr dart::compiler::target::word Array_InstanceSize = 24;
 static constexpr dart::compiler::target::word Array_header_size = 24;
+static constexpr dart::compiler::target::word Bool_InstanceSize = 12;
+static constexpr dart::compiler::target::word Bytecode_InstanceSize = 88;
+static constexpr dart::compiler::target::word Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word Class_InstanceSize = 208;
+static constexpr dart::compiler::target::word Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word ClosureData_InstanceSize = 40;
+static constexpr dart::compiler::target::word Code_InstanceSize = 176;
+static constexpr dart::compiler::target::word CodeSourceMap_InstanceSize = 16;
+static constexpr dart::compiler::target::word CompressedStackMaps_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word Context_InstanceSize = 24;
 static constexpr dart::compiler::target::word Context_header_size = 24;
+static constexpr dart::compiler::target::word ContextScope_InstanceSize = 16;
 static constexpr dart::compiler::target::word Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word DynamicLibrary_InstanceSize = 16;
+static constexpr dart::compiler::target::word ExceptionHandlers_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word
+    ExternalOneByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    ExternalTwoByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word ExternalTypedData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word FfiTrampolineData_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word Field_InstanceSize = 112;
 static constexpr dart::compiler::target::word Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word Function_InstanceSize = 144;
+static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word ICData_InstanceSize = 56;
+static constexpr dart::compiler::target::word Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word Instructions_InstanceSize = 12;
 static constexpr dart::compiler::target::word Instructions_UnalignedHeaderSize =
     12;
 static constexpr dart::compiler::target::word Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word NativeArguments_StructSize = 32;
-static constexpr dart::compiler::target::word String_InstanceSize = 16;
-static constexpr dart::compiler::target::word TypedData_InstanceSize = 24;
-static constexpr dart::compiler::target::word Object_InstanceSize = 8;
-static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 24;
-static constexpr dart::compiler::target::word Closure_InstanceSize = 56;
-static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
-    32;
-static constexpr dart::compiler::target::word Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word Integer_InstanceSize = 8;
+static constexpr dart::compiler::target::word KernelProgramInfo_InstanceSize =
+    128;
+static constexpr dart::compiler::target::word LanguageError_InstanceSize = 48;
+static constexpr dart::compiler::target::word Library_InstanceSize = 144;
+static constexpr dart::compiler::target::word LibraryPrefix_InstanceSize = 40;
 static constexpr dart::compiler::target::word LinkedHashMap_InstanceSize = 56;
+static constexpr dart::compiler::target::word LocalVarDescriptors_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word MegamorphicCache_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word MirrorReference_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    MonomorphicSmiableCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word Namespace_InstanceSize = 40;
+static constexpr dart::compiler::target::word NativeArguments_StructSize = 32;
+static constexpr dart::compiler::target::word Number_InstanceSize = 8;
+static constexpr dart::compiler::target::word Object_InstanceSize = 8;
+static constexpr dart::compiler::target::word ObjectPool_InstanceSize = 16;
+static constexpr dart::compiler::target::word OneByteString_InstanceSize = 16;
+static constexpr dart::compiler::target::word ParameterTypeCheck_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word PatchClass_InstanceSize = 48;
+static constexpr dart::compiler::target::word PcDescriptors_InstanceSize = 16;
+static constexpr dart::compiler::target::word Pointer_InstanceSize = 24;
+static constexpr dart::compiler::target::word ReceivePort_InstanceSize = 24;
+static constexpr dart::compiler::target::word RedirectionData_InstanceSize = 32;
+static constexpr dart::compiler::target::word RegExp_InstanceSize = 120;
+static constexpr dart::compiler::target::word Script_InstanceSize = 96;
+static constexpr dart::compiler::target::word SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word SignatureData_InstanceSize = 24;
+static constexpr dart::compiler::target::word SingleTargetCache_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word Smi_InstanceSize = 8;
+static constexpr dart::compiler::target::word StackTrace_InstanceSize = 40;
+static constexpr dart::compiler::target::word String_InstanceSize = 16;
+static constexpr dart::compiler::target::word SubtypeTestCache_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    TransferableTypedData_InstanceSize = 8;
+static constexpr dart::compiler::target::word TwoByteString_InstanceSize = 16;
+static constexpr dart::compiler::target::word Type_InstanceSize = 64;
+static constexpr dart::compiler::target::word TypeArguments_InstanceSize = 32;
+static constexpr dart::compiler::target::word TypeParameter_InstanceSize = 72;
+static constexpr dart::compiler::target::word TypeRef_InstanceSize = 32;
+static constexpr dart::compiler::target::word TypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 24;
+static constexpr dart::compiler::target::word TypedDataView_InstanceSize = 40;
+static constexpr dart::compiler::target::word UnhandledException_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word UnlinkedCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word UnwindError_InstanceSize = 24;
+static constexpr dart::compiler::target::word UserTag_InstanceSize = 24;
+static constexpr dart::compiler::target::word WeakProperty_InstanceSize = 32;
 #endif  // defined(TARGET_ARCH_X64)
 
 #if defined(TARGET_ARCH_IA32)
@@ -828,10 +985,10 @@
 static constexpr dart::compiler::target::word Class_declaration_type_offset =
     56;
 static constexpr dart::compiler::target::word Class_num_type_arguments_offset =
-    102;
+    90;
 static constexpr dart::compiler::target::word Class_super_type_offset = 44;
 static constexpr dart::compiler::target::word
-    Class_type_arguments_field_offset_in_words_offset = 92;
+    Class_host_type_arguments_field_offset_in_words_offset = 104;
 static constexpr dart::compiler::target::word
     ClassTable_shared_class_table_offset = 16;
 static constexpr dart::compiler::target::word ClassTable_table_offset = 8;
@@ -865,7 +1022,7 @@
 static constexpr dart::compiler::target::word Field_guarded_list_length_offset =
     24;
 static constexpr dart::compiler::target::word Field_is_nullable_offset = 46;
-static constexpr dart::compiler::target::word Field_kind_bits_offset = 60;
+static constexpr dart::compiler::target::word Field_kind_bits_offset = 54;
 static constexpr dart::compiler::target::word Function_code_offset = 44;
 static constexpr dart::compiler::target::word Function_entry_point_offset[] = {
     4, 8};
@@ -900,6 +1057,8 @@
 static constexpr dart::compiler::target::word LinkedHashMap_hash_mask_offset =
     12;
 static constexpr dart::compiler::target::word LinkedHashMap_index_offset = 8;
+static constexpr dart::compiler::target::word
+    LinkedHashMap_type_arguments_offset = 4;
 static constexpr dart::compiler::target::word LinkedHashMap_used_data_offset =
     20;
 static constexpr dart::compiler::target::word
@@ -925,6 +1084,7 @@
 static constexpr dart::compiler::target::word OneByteString_data_offset = 12;
 static constexpr dart::compiler::target::word Pointer_c_memory_address_offset =
     8;
+static constexpr dart::compiler::target::word Pointer_type_arguments_offset = 4;
 static constexpr dart::compiler::target::word
     SingleTargetCache_entry_point_offset = 8;
 static constexpr dart::compiler::target::word
@@ -1121,25 +1281,100 @@
 static constexpr dart::compiler::target::word ClassTable_element_size = 1;
 static constexpr dart::compiler::target::word Code_entry_point_offset[] = {
     4, 12, 8, 16};
+static constexpr dart::compiler::target::word ApiError_InstanceSize = 8;
+static constexpr dart::compiler::target::word Array_InstanceSize = 12;
 static constexpr dart::compiler::target::word Array_header_size = 12;
+static constexpr dart::compiler::target::word Bool_InstanceSize = 8;
+static constexpr dart::compiler::target::word Bytecode_InstanceSize = 48;
+static constexpr dart::compiler::target::word Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word Class_InstanceSize = 128;
+static constexpr dart::compiler::target::word Closure_InstanceSize = 28;
+static constexpr dart::compiler::target::word ClosureData_InstanceSize = 20;
+static constexpr dart::compiler::target::word Code_InstanceSize = 96;
+static constexpr dart::compiler::target::word CodeSourceMap_InstanceSize = 8;
+static constexpr dart::compiler::target::word CompressedStackMaps_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word Context_InstanceSize = 12;
 static constexpr dart::compiler::target::word Context_header_size = 12;
+static constexpr dart::compiler::target::word ContextScope_InstanceSize = 12;
 static constexpr dart::compiler::target::word Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word DynamicLibrary_InstanceSize = 8;
+static constexpr dart::compiler::target::word ExceptionHandlers_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word
+    ExternalOneByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word
+    ExternalTwoByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word ExternalTypedData_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word FfiTrampolineData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word Field_InstanceSize = 64;
 static constexpr dart::compiler::target::word Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word Function_InstanceSize = 88;
+static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word ICData_InstanceSize = 32;
+static constexpr dart::compiler::target::word Instance_InstanceSize = 4;
+static constexpr dart::compiler::target::word Instructions_InstanceSize = 8;
 static constexpr dart::compiler::target::word Instructions_UnalignedHeaderSize =
     8;
 static constexpr dart::compiler::target::word Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word NativeArguments_StructSize = 16;
-static constexpr dart::compiler::target::word String_InstanceSize = 12;
-static constexpr dart::compiler::target::word TypedData_InstanceSize = 12;
-static constexpr dart::compiler::target::word Object_InstanceSize = 4;
-static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 12;
-static constexpr dart::compiler::target::word Closure_InstanceSize = 28;
-static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
-    16;
-static constexpr dart::compiler::target::word Instance_InstanceSize = 4;
+static constexpr dart::compiler::target::word Integer_InstanceSize = 4;
+static constexpr dart::compiler::target::word KernelProgramInfo_InstanceSize =
+    64;
+static constexpr dart::compiler::target::word LanguageError_InstanceSize = 28;
+static constexpr dart::compiler::target::word Library_InstanceSize = 76;
+static constexpr dart::compiler::target::word LibraryPrefix_InstanceSize = 20;
 static constexpr dart::compiler::target::word LinkedHashMap_InstanceSize = 28;
+static constexpr dart::compiler::target::word LocalVarDescriptors_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word MegamorphicCache_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word MirrorReference_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    MonomorphicSmiableCall_InstanceSize = 16;
+static constexpr dart::compiler::target::word Namespace_InstanceSize = 20;
+static constexpr dart::compiler::target::word NativeArguments_StructSize = 16;
+static constexpr dart::compiler::target::word Number_InstanceSize = 4;
+static constexpr dart::compiler::target::word Object_InstanceSize = 4;
+static constexpr dart::compiler::target::word ObjectPool_InstanceSize = 8;
+static constexpr dart::compiler::target::word OneByteString_InstanceSize = 12;
+static constexpr dart::compiler::target::word ParameterTypeCheck_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word PatchClass_InstanceSize = 24;
+static constexpr dart::compiler::target::word PcDescriptors_InstanceSize = 8;
+static constexpr dart::compiler::target::word Pointer_InstanceSize = 12;
+static constexpr dart::compiler::target::word ReceivePort_InstanceSize = 12;
+static constexpr dart::compiler::target::word RedirectionData_InstanceSize = 16;
+static constexpr dart::compiler::target::word RegExp_InstanceSize = 60;
+static constexpr dart::compiler::target::word Script_InstanceSize = 56;
+static constexpr dart::compiler::target::word SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word SignatureData_InstanceSize = 12;
+static constexpr dart::compiler::target::word SingleTargetCache_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word Smi_InstanceSize = 4;
+static constexpr dart::compiler::target::word StackTrace_InstanceSize = 20;
+static constexpr dart::compiler::target::word String_InstanceSize = 12;
+static constexpr dart::compiler::target::word SubtypeTestCache_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    TransferableTypedData_InstanceSize = 4;
+static constexpr dart::compiler::target::word TwoByteString_InstanceSize = 12;
+static constexpr dart::compiler::target::word Type_InstanceSize = 36;
+static constexpr dart::compiler::target::word TypeArguments_InstanceSize = 16;
+static constexpr dart::compiler::target::word TypeParameter_InstanceSize = 40;
+static constexpr dart::compiler::target::word TypeRef_InstanceSize = 16;
+static constexpr dart::compiler::target::word TypedData_InstanceSize = 12;
+static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 12;
+static constexpr dart::compiler::target::word TypedDataView_InstanceSize = 20;
+static constexpr dart::compiler::target::word UnhandledException_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word UnlinkedCall_InstanceSize = 16;
+static constexpr dart::compiler::target::word UnwindError_InstanceSize = 12;
+static constexpr dart::compiler::target::word UserTag_InstanceSize = 12;
+static constexpr dart::compiler::target::word WeakProperty_InstanceSize = 16;
 #endif  // defined(TARGET_ARCH_IA32)
 
 #if defined(TARGET_ARCH_ARM64)
@@ -1201,10 +1436,10 @@
 static constexpr dart::compiler::target::word Class_declaration_type_offset =
     112;
 static constexpr dart::compiler::target::word Class_num_type_arguments_offset =
-    182;
+    170;
 static constexpr dart::compiler::target::word Class_super_type_offset = 88;
 static constexpr dart::compiler::target::word
-    Class_type_arguments_field_offset_in_words_offset = 172;
+    Class_host_type_arguments_field_offset_in_words_offset = 184;
 static constexpr dart::compiler::target::word
     ClassTable_shared_class_table_offset = 32;
 static constexpr dart::compiler::target::word ClassTable_table_offset = 16;
@@ -1238,7 +1473,7 @@
 static constexpr dart::compiler::target::word Field_guarded_list_length_offset =
     48;
 static constexpr dart::compiler::target::word Field_is_nullable_offset = 82;
-static constexpr dart::compiler::target::word Field_kind_bits_offset = 104;
+static constexpr dart::compiler::target::word Field_kind_bits_offset = 90;
 static constexpr dart::compiler::target::word Function_code_offset = 88;
 static constexpr dart::compiler::target::word Function_entry_point_offset[] = {
     8, 16};
@@ -1273,6 +1508,8 @@
 static constexpr dart::compiler::target::word LinkedHashMap_hash_mask_offset =
     24;
 static constexpr dart::compiler::target::word LinkedHashMap_index_offset = 16;
+static constexpr dart::compiler::target::word
+    LinkedHashMap_type_arguments_offset = 8;
 static constexpr dart::compiler::target::word LinkedHashMap_used_data_offset =
     40;
 static constexpr dart::compiler::target::word
@@ -1298,6 +1535,7 @@
 static constexpr dart::compiler::target::word OneByteString_data_offset = 16;
 static constexpr dart::compiler::target::word Pointer_c_memory_address_offset =
     16;
+static constexpr dart::compiler::target::word Pointer_type_arguments_offset = 8;
 static constexpr dart::compiler::target::word
     SingleTargetCache_entry_point_offset = 16;
 static constexpr dart::compiler::target::word
@@ -1501,25 +1739,101 @@
         1248, 1256, 1264, 1272, 1280, 1288, 1296, 1304, 1312, 1320, 1328,
         1336, 1344, 1352, 1360, -1,   -1,   -1,   -1,   1368, 1376, 1384,
         -1,   1392, 1400, 1408, -1,   -1,   -1,   -1,   -1,   -1};
+static constexpr dart::compiler::target::word ApiError_InstanceSize = 16;
+static constexpr dart::compiler::target::word Array_InstanceSize = 24;
 static constexpr dart::compiler::target::word Array_header_size = 24;
+static constexpr dart::compiler::target::word Bool_InstanceSize = 12;
+static constexpr dart::compiler::target::word Bytecode_InstanceSize = 88;
+static constexpr dart::compiler::target::word Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word Class_InstanceSize = 208;
+static constexpr dart::compiler::target::word Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word ClosureData_InstanceSize = 40;
+static constexpr dart::compiler::target::word Code_InstanceSize = 176;
+static constexpr dart::compiler::target::word CodeSourceMap_InstanceSize = 16;
+static constexpr dart::compiler::target::word CompressedStackMaps_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word Context_InstanceSize = 24;
 static constexpr dart::compiler::target::word Context_header_size = 24;
+static constexpr dart::compiler::target::word ContextScope_InstanceSize = 16;
 static constexpr dart::compiler::target::word Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word DynamicLibrary_InstanceSize = 16;
+static constexpr dart::compiler::target::word ExceptionHandlers_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word
+    ExternalOneByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    ExternalTwoByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word ExternalTypedData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word FfiTrampolineData_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word Field_InstanceSize = 112;
 static constexpr dart::compiler::target::word Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word Function_InstanceSize = 144;
+static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word ICData_InstanceSize = 56;
+static constexpr dart::compiler::target::word Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word Instructions_InstanceSize = 12;
 static constexpr dart::compiler::target::word Instructions_UnalignedHeaderSize =
     12;
 static constexpr dart::compiler::target::word Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word NativeArguments_StructSize = 32;
-static constexpr dart::compiler::target::word String_InstanceSize = 16;
-static constexpr dart::compiler::target::word TypedData_InstanceSize = 24;
-static constexpr dart::compiler::target::word Object_InstanceSize = 8;
-static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 24;
-static constexpr dart::compiler::target::word Closure_InstanceSize = 56;
-static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
-    32;
-static constexpr dart::compiler::target::word Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word Integer_InstanceSize = 8;
+static constexpr dart::compiler::target::word KernelProgramInfo_InstanceSize =
+    128;
+static constexpr dart::compiler::target::word LanguageError_InstanceSize = 48;
+static constexpr dart::compiler::target::word Library_InstanceSize = 144;
+static constexpr dart::compiler::target::word LibraryPrefix_InstanceSize = 40;
 static constexpr dart::compiler::target::word LinkedHashMap_InstanceSize = 56;
+static constexpr dart::compiler::target::word LocalVarDescriptors_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word MegamorphicCache_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word MirrorReference_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    MonomorphicSmiableCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word Namespace_InstanceSize = 40;
+static constexpr dart::compiler::target::word NativeArguments_StructSize = 32;
+static constexpr dart::compiler::target::word Number_InstanceSize = 8;
+static constexpr dart::compiler::target::word Object_InstanceSize = 8;
+static constexpr dart::compiler::target::word ObjectPool_InstanceSize = 16;
+static constexpr dart::compiler::target::word OneByteString_InstanceSize = 16;
+static constexpr dart::compiler::target::word ParameterTypeCheck_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word PatchClass_InstanceSize = 48;
+static constexpr dart::compiler::target::word PcDescriptors_InstanceSize = 16;
+static constexpr dart::compiler::target::word Pointer_InstanceSize = 24;
+static constexpr dart::compiler::target::word ReceivePort_InstanceSize = 24;
+static constexpr dart::compiler::target::word RedirectionData_InstanceSize = 32;
+static constexpr dart::compiler::target::word RegExp_InstanceSize = 120;
+static constexpr dart::compiler::target::word Script_InstanceSize = 96;
+static constexpr dart::compiler::target::word SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word SignatureData_InstanceSize = 24;
+static constexpr dart::compiler::target::word SingleTargetCache_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word Smi_InstanceSize = 8;
+static constexpr dart::compiler::target::word StackTrace_InstanceSize = 40;
+static constexpr dart::compiler::target::word String_InstanceSize = 16;
+static constexpr dart::compiler::target::word SubtypeTestCache_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    TransferableTypedData_InstanceSize = 8;
+static constexpr dart::compiler::target::word TwoByteString_InstanceSize = 16;
+static constexpr dart::compiler::target::word Type_InstanceSize = 64;
+static constexpr dart::compiler::target::word TypeArguments_InstanceSize = 32;
+static constexpr dart::compiler::target::word TypeParameter_InstanceSize = 72;
+static constexpr dart::compiler::target::word TypeRef_InstanceSize = 32;
+static constexpr dart::compiler::target::word TypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 24;
+static constexpr dart::compiler::target::word TypedDataView_InstanceSize = 40;
+static constexpr dart::compiler::target::word UnhandledException_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word UnlinkedCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word UnwindError_InstanceSize = 24;
+static constexpr dart::compiler::target::word UserTag_InstanceSize = 24;
+static constexpr dart::compiler::target::word WeakProperty_InstanceSize = 32;
 #endif  // defined(TARGET_ARCH_ARM64)
 
 #else  // !defined(PRODUCT)
@@ -1581,10 +1895,10 @@
 static constexpr dart::compiler::target::word Class_declaration_type_offset =
     56;
 static constexpr dart::compiler::target::word Class_num_type_arguments_offset =
-    102;
+    90;
 static constexpr dart::compiler::target::word Class_super_type_offset = 44;
 static constexpr dart::compiler::target::word
-    Class_type_arguments_field_offset_in_words_offset = 92;
+    Class_host_type_arguments_field_offset_in_words_offset = 104;
 static constexpr dart::compiler::target::word
     ClassTable_shared_class_table_offset = 16;
 static constexpr dart::compiler::target::word ClassTable_table_offset = 8;
@@ -1616,7 +1930,7 @@
 static constexpr dart::compiler::target::word Field_guarded_list_length_offset =
     24;
 static constexpr dart::compiler::target::word Field_is_nullable_offset = 46;
-static constexpr dart::compiler::target::word Field_kind_bits_offset = 60;
+static constexpr dart::compiler::target::word Field_kind_bits_offset = 54;
 static constexpr dart::compiler::target::word Function_code_offset = 44;
 static constexpr dart::compiler::target::word Function_entry_point_offset[] = {
     4, 8};
@@ -1650,6 +1964,8 @@
 static constexpr dart::compiler::target::word LinkedHashMap_hash_mask_offset =
     12;
 static constexpr dart::compiler::target::word LinkedHashMap_index_offset = 8;
+static constexpr dart::compiler::target::word
+    LinkedHashMap_type_arguments_offset = 4;
 static constexpr dart::compiler::target::word LinkedHashMap_used_data_offset =
     20;
 static constexpr dart::compiler::target::word
@@ -1675,6 +1991,7 @@
 static constexpr dart::compiler::target::word OneByteString_data_offset = 12;
 static constexpr dart::compiler::target::word Pointer_c_memory_address_offset =
     8;
+static constexpr dart::compiler::target::word Pointer_type_arguments_offset = 4;
 static constexpr dart::compiler::target::word
     SingleTargetCache_entry_point_offset = 8;
 static constexpr dart::compiler::target::word
@@ -1872,25 +2189,100 @@
     Thread_write_barrier_wrappers_thread_offset[] = {
         628, 632, 636, 640, 644, -1, 648, 652,
         656, 660, -1,  -1,  -1,  -1, -1,  -1};
+static constexpr dart::compiler::target::word ApiError_InstanceSize = 8;
+static constexpr dart::compiler::target::word Array_InstanceSize = 12;
 static constexpr dart::compiler::target::word Array_header_size = 12;
+static constexpr dart::compiler::target::word Bool_InstanceSize = 8;
+static constexpr dart::compiler::target::word Bytecode_InstanceSize = 44;
+static constexpr dart::compiler::target::word Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word Class_InstanceSize = 128;
+static constexpr dart::compiler::target::word Closure_InstanceSize = 28;
+static constexpr dart::compiler::target::word ClosureData_InstanceSize = 20;
+static constexpr dart::compiler::target::word Code_InstanceSize = 76;
+static constexpr dart::compiler::target::word CodeSourceMap_InstanceSize = 8;
+static constexpr dart::compiler::target::word CompressedStackMaps_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word Context_InstanceSize = 12;
 static constexpr dart::compiler::target::word Context_header_size = 12;
+static constexpr dart::compiler::target::word ContextScope_InstanceSize = 12;
 static constexpr dart::compiler::target::word Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word DynamicLibrary_InstanceSize = 8;
+static constexpr dart::compiler::target::word ExceptionHandlers_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word
+    ExternalOneByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word
+    ExternalTwoByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word ExternalTypedData_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word FfiTrampolineData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word Field_InstanceSize = 64;
 static constexpr dart::compiler::target::word Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word Function_InstanceSize = 88;
+static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word ICData_InstanceSize = 32;
+static constexpr dart::compiler::target::word Instance_InstanceSize = 4;
+static constexpr dart::compiler::target::word Instructions_InstanceSize = 8;
 static constexpr dart::compiler::target::word Instructions_UnalignedHeaderSize =
     8;
 static constexpr dart::compiler::target::word Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word NativeArguments_StructSize = 16;
-static constexpr dart::compiler::target::word String_InstanceSize = 12;
-static constexpr dart::compiler::target::word TypedData_InstanceSize = 12;
-static constexpr dart::compiler::target::word Object_InstanceSize = 4;
-static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 12;
-static constexpr dart::compiler::target::word Closure_InstanceSize = 28;
-static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
-    16;
-static constexpr dart::compiler::target::word Instance_InstanceSize = 4;
+static constexpr dart::compiler::target::word Integer_InstanceSize = 4;
+static constexpr dart::compiler::target::word KernelProgramInfo_InstanceSize =
+    64;
+static constexpr dart::compiler::target::word LanguageError_InstanceSize = 28;
+static constexpr dart::compiler::target::word Library_InstanceSize = 76;
+static constexpr dart::compiler::target::word LibraryPrefix_InstanceSize = 20;
 static constexpr dart::compiler::target::word LinkedHashMap_InstanceSize = 28;
+static constexpr dart::compiler::target::word LocalVarDescriptors_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word MegamorphicCache_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word MirrorReference_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    MonomorphicSmiableCall_InstanceSize = 16;
+static constexpr dart::compiler::target::word Namespace_InstanceSize = 20;
+static constexpr dart::compiler::target::word NativeArguments_StructSize = 16;
+static constexpr dart::compiler::target::word Number_InstanceSize = 4;
+static constexpr dart::compiler::target::word Object_InstanceSize = 4;
+static constexpr dart::compiler::target::word ObjectPool_InstanceSize = 8;
+static constexpr dart::compiler::target::word OneByteString_InstanceSize = 12;
+static constexpr dart::compiler::target::word ParameterTypeCheck_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word PatchClass_InstanceSize = 24;
+static constexpr dart::compiler::target::word PcDescriptors_InstanceSize = 8;
+static constexpr dart::compiler::target::word Pointer_InstanceSize = 12;
+static constexpr dart::compiler::target::word ReceivePort_InstanceSize = 12;
+static constexpr dart::compiler::target::word RedirectionData_InstanceSize = 16;
+static constexpr dart::compiler::target::word RegExp_InstanceSize = 60;
+static constexpr dart::compiler::target::word Script_InstanceSize = 56;
+static constexpr dart::compiler::target::word SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word SignatureData_InstanceSize = 12;
+static constexpr dart::compiler::target::word SingleTargetCache_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word Smi_InstanceSize = 4;
+static constexpr dart::compiler::target::word StackTrace_InstanceSize = 20;
+static constexpr dart::compiler::target::word String_InstanceSize = 12;
+static constexpr dart::compiler::target::word SubtypeTestCache_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    TransferableTypedData_InstanceSize = 4;
+static constexpr dart::compiler::target::word TwoByteString_InstanceSize = 12;
+static constexpr dart::compiler::target::word Type_InstanceSize = 36;
+static constexpr dart::compiler::target::word TypeArguments_InstanceSize = 16;
+static constexpr dart::compiler::target::word TypeParameter_InstanceSize = 40;
+static constexpr dart::compiler::target::word TypeRef_InstanceSize = 16;
+static constexpr dart::compiler::target::word TypedData_InstanceSize = 12;
+static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 12;
+static constexpr dart::compiler::target::word TypedDataView_InstanceSize = 20;
+static constexpr dart::compiler::target::word UnhandledException_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word UnlinkedCall_InstanceSize = 16;
+static constexpr dart::compiler::target::word UnwindError_InstanceSize = 12;
+static constexpr dart::compiler::target::word UserTag_InstanceSize = 12;
+static constexpr dart::compiler::target::word WeakProperty_InstanceSize = 16;
 #endif  // defined(TARGET_ARCH_ARM)
 
 #if defined(TARGET_ARCH_X64)
@@ -1952,10 +2344,10 @@
 static constexpr dart::compiler::target::word Class_declaration_type_offset =
     112;
 static constexpr dart::compiler::target::word Class_num_type_arguments_offset =
-    182;
+    170;
 static constexpr dart::compiler::target::word Class_super_type_offset = 88;
 static constexpr dart::compiler::target::word
-    Class_type_arguments_field_offset_in_words_offset = 172;
+    Class_host_type_arguments_field_offset_in_words_offset = 184;
 static constexpr dart::compiler::target::word
     ClassTable_shared_class_table_offset = 32;
 static constexpr dart::compiler::target::word ClassTable_table_offset = 16;
@@ -1987,7 +2379,7 @@
 static constexpr dart::compiler::target::word Field_guarded_list_length_offset =
     48;
 static constexpr dart::compiler::target::word Field_is_nullable_offset = 82;
-static constexpr dart::compiler::target::word Field_kind_bits_offset = 104;
+static constexpr dart::compiler::target::word Field_kind_bits_offset = 90;
 static constexpr dart::compiler::target::word Function_code_offset = 88;
 static constexpr dart::compiler::target::word Function_entry_point_offset[] = {
     8, 16};
@@ -2021,6 +2413,8 @@
 static constexpr dart::compiler::target::word LinkedHashMap_hash_mask_offset =
     24;
 static constexpr dart::compiler::target::word LinkedHashMap_index_offset = 16;
+static constexpr dart::compiler::target::word
+    LinkedHashMap_type_arguments_offset = 8;
 static constexpr dart::compiler::target::word LinkedHashMap_used_data_offset =
     40;
 static constexpr dart::compiler::target::word
@@ -2046,6 +2440,7 @@
 static constexpr dart::compiler::target::word OneByteString_data_offset = 16;
 static constexpr dart::compiler::target::word Pointer_c_memory_address_offset =
     16;
+static constexpr dart::compiler::target::word Pointer_type_arguments_offset = 8;
 static constexpr dart::compiler::target::word
     SingleTargetCache_entry_point_offset = 16;
 static constexpr dart::compiler::target::word
@@ -2245,25 +2640,101 @@
     Thread_write_barrier_wrappers_thread_offset[] = {
         1248, 1256, 1264, 1272, -1,   -1,   1280, 1288,
         1296, 1304, 1312, -1,   1320, 1328, -1,   -1};
+static constexpr dart::compiler::target::word ApiError_InstanceSize = 16;
+static constexpr dart::compiler::target::word Array_InstanceSize = 24;
 static constexpr dart::compiler::target::word Array_header_size = 24;
+static constexpr dart::compiler::target::word Bool_InstanceSize = 12;
+static constexpr dart::compiler::target::word Bytecode_InstanceSize = 80;
+static constexpr dart::compiler::target::word Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word Class_InstanceSize = 208;
+static constexpr dart::compiler::target::word Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word ClosureData_InstanceSize = 40;
+static constexpr dart::compiler::target::word Code_InstanceSize = 144;
+static constexpr dart::compiler::target::word CodeSourceMap_InstanceSize = 16;
+static constexpr dart::compiler::target::word CompressedStackMaps_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word Context_InstanceSize = 24;
 static constexpr dart::compiler::target::word Context_header_size = 24;
+static constexpr dart::compiler::target::word ContextScope_InstanceSize = 16;
 static constexpr dart::compiler::target::word Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word DynamicLibrary_InstanceSize = 16;
+static constexpr dart::compiler::target::word ExceptionHandlers_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word
+    ExternalOneByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    ExternalTwoByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word ExternalTypedData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word FfiTrampolineData_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word Field_InstanceSize = 112;
 static constexpr dart::compiler::target::word Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word Function_InstanceSize = 144;
+static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word ICData_InstanceSize = 56;
+static constexpr dart::compiler::target::word Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word Instructions_InstanceSize = 12;
 static constexpr dart::compiler::target::word Instructions_UnalignedHeaderSize =
     12;
 static constexpr dart::compiler::target::word Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word NativeArguments_StructSize = 32;
-static constexpr dart::compiler::target::word String_InstanceSize = 16;
-static constexpr dart::compiler::target::word TypedData_InstanceSize = 24;
-static constexpr dart::compiler::target::word Object_InstanceSize = 8;
-static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 24;
-static constexpr dart::compiler::target::word Closure_InstanceSize = 56;
-static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
-    32;
-static constexpr dart::compiler::target::word Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word Integer_InstanceSize = 8;
+static constexpr dart::compiler::target::word KernelProgramInfo_InstanceSize =
+    128;
+static constexpr dart::compiler::target::word LanguageError_InstanceSize = 48;
+static constexpr dart::compiler::target::word Library_InstanceSize = 144;
+static constexpr dart::compiler::target::word LibraryPrefix_InstanceSize = 40;
 static constexpr dart::compiler::target::word LinkedHashMap_InstanceSize = 56;
+static constexpr dart::compiler::target::word LocalVarDescriptors_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word MegamorphicCache_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word MirrorReference_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    MonomorphicSmiableCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word Namespace_InstanceSize = 40;
+static constexpr dart::compiler::target::word NativeArguments_StructSize = 32;
+static constexpr dart::compiler::target::word Number_InstanceSize = 8;
+static constexpr dart::compiler::target::word Object_InstanceSize = 8;
+static constexpr dart::compiler::target::word ObjectPool_InstanceSize = 16;
+static constexpr dart::compiler::target::word OneByteString_InstanceSize = 16;
+static constexpr dart::compiler::target::word ParameterTypeCheck_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word PatchClass_InstanceSize = 48;
+static constexpr dart::compiler::target::word PcDescriptors_InstanceSize = 16;
+static constexpr dart::compiler::target::word Pointer_InstanceSize = 24;
+static constexpr dart::compiler::target::word ReceivePort_InstanceSize = 24;
+static constexpr dart::compiler::target::word RedirectionData_InstanceSize = 32;
+static constexpr dart::compiler::target::word RegExp_InstanceSize = 120;
+static constexpr dart::compiler::target::word Script_InstanceSize = 96;
+static constexpr dart::compiler::target::word SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word SignatureData_InstanceSize = 24;
+static constexpr dart::compiler::target::word SingleTargetCache_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word Smi_InstanceSize = 8;
+static constexpr dart::compiler::target::word StackTrace_InstanceSize = 40;
+static constexpr dart::compiler::target::word String_InstanceSize = 16;
+static constexpr dart::compiler::target::word SubtypeTestCache_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    TransferableTypedData_InstanceSize = 8;
+static constexpr dart::compiler::target::word TwoByteString_InstanceSize = 16;
+static constexpr dart::compiler::target::word Type_InstanceSize = 64;
+static constexpr dart::compiler::target::word TypeArguments_InstanceSize = 32;
+static constexpr dart::compiler::target::word TypeParameter_InstanceSize = 72;
+static constexpr dart::compiler::target::word TypeRef_InstanceSize = 32;
+static constexpr dart::compiler::target::word TypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 24;
+static constexpr dart::compiler::target::word TypedDataView_InstanceSize = 40;
+static constexpr dart::compiler::target::word UnhandledException_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word UnlinkedCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word UnwindError_InstanceSize = 24;
+static constexpr dart::compiler::target::word UserTag_InstanceSize = 24;
+static constexpr dart::compiler::target::word WeakProperty_InstanceSize = 32;
 #endif  // defined(TARGET_ARCH_X64)
 
 #if defined(TARGET_ARCH_IA32)
@@ -2323,10 +2794,10 @@
 static constexpr dart::compiler::target::word Class_declaration_type_offset =
     56;
 static constexpr dart::compiler::target::word Class_num_type_arguments_offset =
-    102;
+    90;
 static constexpr dart::compiler::target::word Class_super_type_offset = 44;
 static constexpr dart::compiler::target::word
-    Class_type_arguments_field_offset_in_words_offset = 92;
+    Class_host_type_arguments_field_offset_in_words_offset = 104;
 static constexpr dart::compiler::target::word
     ClassTable_shared_class_table_offset = 16;
 static constexpr dart::compiler::target::word ClassTable_table_offset = 8;
@@ -2358,7 +2829,7 @@
 static constexpr dart::compiler::target::word Field_guarded_list_length_offset =
     24;
 static constexpr dart::compiler::target::word Field_is_nullable_offset = 46;
-static constexpr dart::compiler::target::word Field_kind_bits_offset = 60;
+static constexpr dart::compiler::target::word Field_kind_bits_offset = 54;
 static constexpr dart::compiler::target::word Function_code_offset = 44;
 static constexpr dart::compiler::target::word Function_entry_point_offset[] = {
     4, 8};
@@ -2392,6 +2863,8 @@
 static constexpr dart::compiler::target::word LinkedHashMap_hash_mask_offset =
     12;
 static constexpr dart::compiler::target::word LinkedHashMap_index_offset = 8;
+static constexpr dart::compiler::target::word
+    LinkedHashMap_type_arguments_offset = 4;
 static constexpr dart::compiler::target::word LinkedHashMap_used_data_offset =
     20;
 static constexpr dart::compiler::target::word
@@ -2417,6 +2890,7 @@
 static constexpr dart::compiler::target::word OneByteString_data_offset = 12;
 static constexpr dart::compiler::target::word Pointer_c_memory_address_offset =
     8;
+static constexpr dart::compiler::target::word Pointer_type_arguments_offset = 4;
 static constexpr dart::compiler::target::word
     SingleTargetCache_entry_point_offset = 8;
 static constexpr dart::compiler::target::word
@@ -2610,25 +3084,100 @@
 static constexpr dart::compiler::target::word TypeArguments_element_size = 4;
 static constexpr dart::compiler::target::word Code_entry_point_offset[] = {
     4, 12, 8, 16};
+static constexpr dart::compiler::target::word ApiError_InstanceSize = 8;
+static constexpr dart::compiler::target::word Array_InstanceSize = 12;
 static constexpr dart::compiler::target::word Array_header_size = 12;
+static constexpr dart::compiler::target::word Bool_InstanceSize = 8;
+static constexpr dart::compiler::target::word Bytecode_InstanceSize = 44;
+static constexpr dart::compiler::target::word Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word Class_InstanceSize = 128;
+static constexpr dart::compiler::target::word Closure_InstanceSize = 28;
+static constexpr dart::compiler::target::word ClosureData_InstanceSize = 20;
+static constexpr dart::compiler::target::word Code_InstanceSize = 76;
+static constexpr dart::compiler::target::word CodeSourceMap_InstanceSize = 8;
+static constexpr dart::compiler::target::word CompressedStackMaps_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word Context_InstanceSize = 12;
 static constexpr dart::compiler::target::word Context_header_size = 12;
+static constexpr dart::compiler::target::word ContextScope_InstanceSize = 12;
 static constexpr dart::compiler::target::word Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word DynamicLibrary_InstanceSize = 8;
+static constexpr dart::compiler::target::word ExceptionHandlers_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word
+    ExternalOneByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word
+    ExternalTwoByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word ExternalTypedData_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word FfiTrampolineData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word Field_InstanceSize = 64;
 static constexpr dart::compiler::target::word Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word Function_InstanceSize = 88;
+static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word ICData_InstanceSize = 32;
+static constexpr dart::compiler::target::word Instance_InstanceSize = 4;
+static constexpr dart::compiler::target::word Instructions_InstanceSize = 8;
 static constexpr dart::compiler::target::word Instructions_UnalignedHeaderSize =
     8;
 static constexpr dart::compiler::target::word Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word NativeArguments_StructSize = 16;
-static constexpr dart::compiler::target::word String_InstanceSize = 12;
-static constexpr dart::compiler::target::word TypedData_InstanceSize = 12;
-static constexpr dart::compiler::target::word Object_InstanceSize = 4;
-static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 12;
-static constexpr dart::compiler::target::word Closure_InstanceSize = 28;
-static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
-    16;
-static constexpr dart::compiler::target::word Instance_InstanceSize = 4;
+static constexpr dart::compiler::target::word Integer_InstanceSize = 4;
+static constexpr dart::compiler::target::word KernelProgramInfo_InstanceSize =
+    64;
+static constexpr dart::compiler::target::word LanguageError_InstanceSize = 28;
+static constexpr dart::compiler::target::word Library_InstanceSize = 76;
+static constexpr dart::compiler::target::word LibraryPrefix_InstanceSize = 20;
 static constexpr dart::compiler::target::word LinkedHashMap_InstanceSize = 28;
+static constexpr dart::compiler::target::word LocalVarDescriptors_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word MegamorphicCache_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word MirrorReference_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    MonomorphicSmiableCall_InstanceSize = 16;
+static constexpr dart::compiler::target::word Namespace_InstanceSize = 20;
+static constexpr dart::compiler::target::word NativeArguments_StructSize = 16;
+static constexpr dart::compiler::target::word Number_InstanceSize = 4;
+static constexpr dart::compiler::target::word Object_InstanceSize = 4;
+static constexpr dart::compiler::target::word ObjectPool_InstanceSize = 8;
+static constexpr dart::compiler::target::word OneByteString_InstanceSize = 12;
+static constexpr dart::compiler::target::word ParameterTypeCheck_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word PatchClass_InstanceSize = 24;
+static constexpr dart::compiler::target::word PcDescriptors_InstanceSize = 8;
+static constexpr dart::compiler::target::word Pointer_InstanceSize = 12;
+static constexpr dart::compiler::target::word ReceivePort_InstanceSize = 12;
+static constexpr dart::compiler::target::word RedirectionData_InstanceSize = 16;
+static constexpr dart::compiler::target::word RegExp_InstanceSize = 60;
+static constexpr dart::compiler::target::word Script_InstanceSize = 56;
+static constexpr dart::compiler::target::word SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word SignatureData_InstanceSize = 12;
+static constexpr dart::compiler::target::word SingleTargetCache_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word Smi_InstanceSize = 4;
+static constexpr dart::compiler::target::word StackTrace_InstanceSize = 20;
+static constexpr dart::compiler::target::word String_InstanceSize = 12;
+static constexpr dart::compiler::target::word SubtypeTestCache_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    TransferableTypedData_InstanceSize = 4;
+static constexpr dart::compiler::target::word TwoByteString_InstanceSize = 12;
+static constexpr dart::compiler::target::word Type_InstanceSize = 36;
+static constexpr dart::compiler::target::word TypeArguments_InstanceSize = 16;
+static constexpr dart::compiler::target::word TypeParameter_InstanceSize = 40;
+static constexpr dart::compiler::target::word TypeRef_InstanceSize = 16;
+static constexpr dart::compiler::target::word TypedData_InstanceSize = 12;
+static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 12;
+static constexpr dart::compiler::target::word TypedDataView_InstanceSize = 20;
+static constexpr dart::compiler::target::word UnhandledException_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word UnlinkedCall_InstanceSize = 16;
+static constexpr dart::compiler::target::word UnwindError_InstanceSize = 12;
+static constexpr dart::compiler::target::word UserTag_InstanceSize = 12;
+static constexpr dart::compiler::target::word WeakProperty_InstanceSize = 16;
 #endif  // defined(TARGET_ARCH_IA32)
 
 #if defined(TARGET_ARCH_ARM64)
@@ -2690,10 +3239,10 @@
 static constexpr dart::compiler::target::word Class_declaration_type_offset =
     112;
 static constexpr dart::compiler::target::word Class_num_type_arguments_offset =
-    182;
+    170;
 static constexpr dart::compiler::target::word Class_super_type_offset = 88;
 static constexpr dart::compiler::target::word
-    Class_type_arguments_field_offset_in_words_offset = 172;
+    Class_host_type_arguments_field_offset_in_words_offset = 184;
 static constexpr dart::compiler::target::word
     ClassTable_shared_class_table_offset = 32;
 static constexpr dart::compiler::target::word ClassTable_table_offset = 16;
@@ -2725,7 +3274,7 @@
 static constexpr dart::compiler::target::word Field_guarded_list_length_offset =
     48;
 static constexpr dart::compiler::target::word Field_is_nullable_offset = 82;
-static constexpr dart::compiler::target::word Field_kind_bits_offset = 104;
+static constexpr dart::compiler::target::word Field_kind_bits_offset = 90;
 static constexpr dart::compiler::target::word Function_code_offset = 88;
 static constexpr dart::compiler::target::word Function_entry_point_offset[] = {
     8, 16};
@@ -2759,6 +3308,8 @@
 static constexpr dart::compiler::target::word LinkedHashMap_hash_mask_offset =
     24;
 static constexpr dart::compiler::target::word LinkedHashMap_index_offset = 16;
+static constexpr dart::compiler::target::word
+    LinkedHashMap_type_arguments_offset = 8;
 static constexpr dart::compiler::target::word LinkedHashMap_used_data_offset =
     40;
 static constexpr dart::compiler::target::word
@@ -2784,6 +3335,7 @@
 static constexpr dart::compiler::target::word OneByteString_data_offset = 16;
 static constexpr dart::compiler::target::word Pointer_c_memory_address_offset =
     16;
+static constexpr dart::compiler::target::word Pointer_type_arguments_offset = 8;
 static constexpr dart::compiler::target::word
     SingleTargetCache_entry_point_offset = 16;
 static constexpr dart::compiler::target::word
@@ -2984,25 +3536,101 @@
         1248, 1256, 1264, 1272, 1280, 1288, 1296, 1304, 1312, 1320, 1328,
         1336, 1344, 1352, 1360, -1,   -1,   -1,   -1,   1368, 1376, 1384,
         -1,   1392, 1400, 1408, -1,   -1,   -1,   -1,   -1,   -1};
+static constexpr dart::compiler::target::word ApiError_InstanceSize = 16;
+static constexpr dart::compiler::target::word Array_InstanceSize = 24;
 static constexpr dart::compiler::target::word Array_header_size = 24;
+static constexpr dart::compiler::target::word Bool_InstanceSize = 12;
+static constexpr dart::compiler::target::word Bytecode_InstanceSize = 80;
+static constexpr dart::compiler::target::word Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word Class_InstanceSize = 208;
+static constexpr dart::compiler::target::word Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word ClosureData_InstanceSize = 40;
+static constexpr dart::compiler::target::word Code_InstanceSize = 144;
+static constexpr dart::compiler::target::word CodeSourceMap_InstanceSize = 16;
+static constexpr dart::compiler::target::word CompressedStackMaps_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word Context_InstanceSize = 24;
 static constexpr dart::compiler::target::word Context_header_size = 24;
+static constexpr dart::compiler::target::word ContextScope_InstanceSize = 16;
 static constexpr dart::compiler::target::word Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word DynamicLibrary_InstanceSize = 16;
+static constexpr dart::compiler::target::word ExceptionHandlers_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word
+    ExternalOneByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    ExternalTwoByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word ExternalTypedData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word FfiTrampolineData_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word Field_InstanceSize = 112;
 static constexpr dart::compiler::target::word Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word Function_InstanceSize = 144;
+static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word ICData_InstanceSize = 56;
+static constexpr dart::compiler::target::word Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word Instructions_InstanceSize = 12;
 static constexpr dart::compiler::target::word Instructions_UnalignedHeaderSize =
     12;
 static constexpr dart::compiler::target::word Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word NativeArguments_StructSize = 32;
-static constexpr dart::compiler::target::word String_InstanceSize = 16;
-static constexpr dart::compiler::target::word TypedData_InstanceSize = 24;
-static constexpr dart::compiler::target::word Object_InstanceSize = 8;
-static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 24;
-static constexpr dart::compiler::target::word Closure_InstanceSize = 56;
-static constexpr dart::compiler::target::word GrowableObjectArray_InstanceSize =
-    32;
-static constexpr dart::compiler::target::word Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word Integer_InstanceSize = 8;
+static constexpr dart::compiler::target::word KernelProgramInfo_InstanceSize =
+    128;
+static constexpr dart::compiler::target::word LanguageError_InstanceSize = 48;
+static constexpr dart::compiler::target::word Library_InstanceSize = 144;
+static constexpr dart::compiler::target::word LibraryPrefix_InstanceSize = 40;
 static constexpr dart::compiler::target::word LinkedHashMap_InstanceSize = 56;
+static constexpr dart::compiler::target::word LocalVarDescriptors_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word MegamorphicCache_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word MirrorReference_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    MonomorphicSmiableCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word Namespace_InstanceSize = 40;
+static constexpr dart::compiler::target::word NativeArguments_StructSize = 32;
+static constexpr dart::compiler::target::word Number_InstanceSize = 8;
+static constexpr dart::compiler::target::word Object_InstanceSize = 8;
+static constexpr dart::compiler::target::word ObjectPool_InstanceSize = 16;
+static constexpr dart::compiler::target::word OneByteString_InstanceSize = 16;
+static constexpr dart::compiler::target::word ParameterTypeCheck_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word PatchClass_InstanceSize = 48;
+static constexpr dart::compiler::target::word PcDescriptors_InstanceSize = 16;
+static constexpr dart::compiler::target::word Pointer_InstanceSize = 24;
+static constexpr dart::compiler::target::word ReceivePort_InstanceSize = 24;
+static constexpr dart::compiler::target::word RedirectionData_InstanceSize = 32;
+static constexpr dart::compiler::target::word RegExp_InstanceSize = 120;
+static constexpr dart::compiler::target::word Script_InstanceSize = 96;
+static constexpr dart::compiler::target::word SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word SignatureData_InstanceSize = 24;
+static constexpr dart::compiler::target::word SingleTargetCache_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word Smi_InstanceSize = 8;
+static constexpr dart::compiler::target::word StackTrace_InstanceSize = 40;
+static constexpr dart::compiler::target::word String_InstanceSize = 16;
+static constexpr dart::compiler::target::word SubtypeTestCache_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    TransferableTypedData_InstanceSize = 8;
+static constexpr dart::compiler::target::word TwoByteString_InstanceSize = 16;
+static constexpr dart::compiler::target::word Type_InstanceSize = 64;
+static constexpr dart::compiler::target::word TypeArguments_InstanceSize = 32;
+static constexpr dart::compiler::target::word TypeParameter_InstanceSize = 72;
+static constexpr dart::compiler::target::word TypeRef_InstanceSize = 32;
+static constexpr dart::compiler::target::word TypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word TypedDataBase_InstanceSize = 24;
+static constexpr dart::compiler::target::word TypedDataView_InstanceSize = 40;
+static constexpr dart::compiler::target::word UnhandledException_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word UnlinkedCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word UnwindError_InstanceSize = 24;
+static constexpr dart::compiler::target::word UserTag_InstanceSize = 24;
+static constexpr dart::compiler::target::word WeakProperty_InstanceSize = 32;
 #endif  // defined(TARGET_ARCH_ARM64)
 
 #endif  // !defined(PRODUCT)
@@ -3071,10 +3699,10 @@
 static constexpr dart::compiler::target::word
     AOT_Class_declaration_type_offset = 56;
 static constexpr dart::compiler::target::word
-    AOT_Class_num_type_arguments_offset = 102;
+    AOT_Class_num_type_arguments_offset = 90;
 static constexpr dart::compiler::target::word AOT_Class_super_type_offset = 44;
 static constexpr dart::compiler::target::word
-    AOT_Class_type_arguments_field_offset_in_words_offset = 92;
+    AOT_Class_host_type_arguments_field_offset_in_words_offset = 104;
 static constexpr dart::compiler::target::word
     AOT_ClassTable_shared_class_table_offset = 16;
 static constexpr dart::compiler::target::word AOT_ClassTable_table_offset = 8;
@@ -3141,6 +3769,8 @@
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_index_offset =
     8;
 static constexpr dart::compiler::target::word
+    AOT_LinkedHashMap_type_arguments_offset = 4;
+static constexpr dart::compiler::target::word
     AOT_LinkedHashMap_used_data_offset = 20;
 static constexpr dart::compiler::target::word
     AOT_MarkingStackBlock_pointers_offset = 8;
@@ -3172,6 +3802,8 @@
 static constexpr dart::compiler::target::word
     AOT_Pointer_c_memory_address_offset = 8;
 static constexpr dart::compiler::target::word
+    AOT_Pointer_type_arguments_offset = 4;
+static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_entry_point_offset = 8;
 static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_lower_limit_offset = 12;
@@ -3387,28 +4019,120 @@
     AOT_Thread_write_barrier_wrappers_thread_offset[] = {
         628, 632, 636, 640, 644, -1, 648, 652,
         656, 660, -1,  -1,  -1,  -1, -1,  -1};
+static constexpr dart::compiler::target::word AOT_ApiError_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Array_InstanceSize = 12;
 static constexpr dart::compiler::target::word AOT_Array_header_size = 12;
+static constexpr dart::compiler::target::word AOT_Bool_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Bytecode_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Class_InstanceSize = 112;
+static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 28;
+static constexpr dart::compiler::target::word AOT_ClosureData_InstanceSize = 20;
+static constexpr dart::compiler::target::word AOT_Code_InstanceSize = 88;
+static constexpr dart::compiler::target::word AOT_CodeSourceMap_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word
+    AOT_CompressedStackMaps_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Context_InstanceSize = 12;
 static constexpr dart::compiler::target::word AOT_Context_header_size = 12;
+static constexpr dart::compiler::target::word AOT_ContextScope_InstanceSize =
+    12;
 static constexpr dart::compiler::target::word AOT_Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_DynamicLibrary_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word
+    AOT_ExceptionHandlers_InstanceSize = 12;
+static constexpr dart::compiler::target::word
+    AOT_ExternalOneByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTwoByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTypedData_InstanceSize = 12;
+static constexpr dart::compiler::target::word
+    AOT_FfiTrampolineData_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Field_InstanceSize = 48;
 static constexpr dart::compiler::target::word AOT_Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Function_InstanceSize = 56;
+static constexpr dart::compiler::target::word
+    AOT_GrowableObjectArray_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_ICData_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 4;
+static constexpr dart::compiler::target::word AOT_Instructions_InstanceSize = 8;
 static constexpr dart::compiler::target::word
     AOT_Instructions_UnalignedHeaderSize = 8;
 static constexpr dart::compiler::target::word AOT_Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
-    16;
-static constexpr dart::compiler::target::word AOT_String_InstanceSize = 12;
-static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 12;
-static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 4;
-static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
-    12;
-static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 28;
+static constexpr dart::compiler::target::word AOT_Integer_InstanceSize = 4;
 static constexpr dart::compiler::target::word
-    AOT_GrowableObjectArray_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 4;
+    AOT_KernelProgramInfo_InstanceSize = 64;
+static constexpr dart::compiler::target::word AOT_LanguageError_InstanceSize =
+    28;
+static constexpr dart::compiler::target::word AOT_Library_InstanceSize = 72;
+static constexpr dart::compiler::target::word AOT_LibraryPrefix_InstanceSize =
+    20;
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_InstanceSize =
     28;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    AOT_MegamorphicCache_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_MirrorReference_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word
+    AOT_MonomorphicSmiableCall_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Namespace_InstanceSize = 20;
+static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
+    16;
+static constexpr dart::compiler::target::word AOT_Number_InstanceSize = 4;
+static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 4;
+static constexpr dart::compiler::target::word AOT_ObjectPool_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_OneByteString_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word
+    AOT_ParameterTypeCheck_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_PatchClass_InstanceSize = 20;
+static constexpr dart::compiler::target::word AOT_PcDescriptors_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word AOT_Pointer_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_ReceivePort_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_RedirectionData_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_RegExp_InstanceSize = 60;
+static constexpr dart::compiler::target::word AOT_Script_InstanceSize = 56;
+static constexpr dart::compiler::target::word AOT_SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_SignatureData_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word
+    AOT_SingleTargetCache_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Smi_InstanceSize = 4;
+static constexpr dart::compiler::target::word AOT_StackTrace_InstanceSize = 20;
+static constexpr dart::compiler::target::word AOT_String_InstanceSize = 12;
+static constexpr dart::compiler::target::word
+    AOT_SubtypeTestCache_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    AOT_TransferableTypedData_InstanceSize = 4;
+static constexpr dart::compiler::target::word AOT_TwoByteString_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word AOT_Type_InstanceSize = 36;
+static constexpr dart::compiler::target::word AOT_TypeArguments_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_TypeParameter_InstanceSize =
+    40;
+static constexpr dart::compiler::target::word AOT_TypeRef_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word AOT_TypedDataView_InstanceSize =
+    20;
+static constexpr dart::compiler::target::word
+    AOT_UnhandledException_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_UnlinkedCall_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_UnwindError_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_UserTag_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_WeakProperty_InstanceSize =
+    16;
 #endif  // defined(TARGET_ARCH_ARM)
 
 #if defined(TARGET_ARCH_X64)
@@ -3473,10 +4197,10 @@
 static constexpr dart::compiler::target::word
     AOT_Class_declaration_type_offset = 112;
 static constexpr dart::compiler::target::word
-    AOT_Class_num_type_arguments_offset = 182;
+    AOT_Class_num_type_arguments_offset = 170;
 static constexpr dart::compiler::target::word AOT_Class_super_type_offset = 88;
 static constexpr dart::compiler::target::word
-    AOT_Class_type_arguments_field_offset_in_words_offset = 172;
+    AOT_Class_host_type_arguments_field_offset_in_words_offset = 184;
 static constexpr dart::compiler::target::word
     AOT_ClassTable_shared_class_table_offset = 32;
 static constexpr dart::compiler::target::word AOT_ClassTable_table_offset = 16;
@@ -3543,6 +4267,8 @@
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_index_offset =
     16;
 static constexpr dart::compiler::target::word
+    AOT_LinkedHashMap_type_arguments_offset = 8;
+static constexpr dart::compiler::target::word
     AOT_LinkedHashMap_used_data_offset = 40;
 static constexpr dart::compiler::target::word
     AOT_MarkingStackBlock_pointers_offset = 16;
@@ -3574,6 +4300,8 @@
 static constexpr dart::compiler::target::word
     AOT_Pointer_c_memory_address_offset = 16;
 static constexpr dart::compiler::target::word
+    AOT_Pointer_type_arguments_offset = 8;
+static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_entry_point_offset = 16;
 static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_lower_limit_offset = 24;
@@ -3790,28 +4518,121 @@
     AOT_Thread_write_barrier_wrappers_thread_offset[] = {
         1248, 1256, 1264, 1272, -1,   -1,   1280, 1288,
         1296, 1304, 1312, -1,   1320, 1328, -1,   -1};
+static constexpr dart::compiler::target::word AOT_ApiError_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Array_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Array_header_size = 24;
+static constexpr dart::compiler::target::word AOT_Bool_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_Bytecode_InstanceSize = 88;
+static constexpr dart::compiler::target::word AOT_Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Class_InstanceSize = 192;
+static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word AOT_ClosureData_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_Code_InstanceSize = 152;
+static constexpr dart::compiler::target::word AOT_CodeSourceMap_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_CompressedStackMaps_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_Context_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Context_header_size = 24;
+static constexpr dart::compiler::target::word AOT_ContextScope_InstanceSize =
+    16;
 static constexpr dart::compiler::target::word AOT_Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_DynamicLibrary_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_ExceptionHandlers_InstanceSize = 24;
+static constexpr dart::compiler::target::word
+    AOT_ExternalOneByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTwoByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word
+    AOT_FfiTrampolineData_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Field_InstanceSize = 80;
 static constexpr dart::compiler::target::word AOT_Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Function_InstanceSize = 104;
+static constexpr dart::compiler::target::word
+    AOT_GrowableObjectArray_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_ICData_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Instructions_InstanceSize =
+    12;
 static constexpr dart::compiler::target::word
     AOT_Instructions_UnalignedHeaderSize = 12;
 static constexpr dart::compiler::target::word AOT_Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
-    32;
-static constexpr dart::compiler::target::word AOT_String_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 24;
-static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 8;
-static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
-    24;
-static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word AOT_Integer_InstanceSize = 8;
 static constexpr dart::compiler::target::word
-    AOT_GrowableObjectArray_InstanceSize = 32;
-static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 8;
+    AOT_KernelProgramInfo_InstanceSize = 128;
+static constexpr dart::compiler::target::word AOT_LanguageError_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word AOT_Library_InstanceSize = 136;
+static constexpr dart::compiler::target::word AOT_LibraryPrefix_InstanceSize =
+    40;
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_InstanceSize =
     56;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_MegamorphicCache_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_MirrorReference_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_MonomorphicSmiableCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_Namespace_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
+    32;
+static constexpr dart::compiler::target::word AOT_Number_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_ObjectPool_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_OneByteString_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_ParameterTypeCheck_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_PatchClass_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_PcDescriptors_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_Pointer_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_ReceivePort_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_RedirectionData_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_RegExp_InstanceSize = 120;
+static constexpr dart::compiler::target::word AOT_Script_InstanceSize = 96;
+static constexpr dart::compiler::target::word AOT_SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_SignatureData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word
+    AOT_SingleTargetCache_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_Smi_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_StackTrace_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_String_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_SubtypeTestCache_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_TransferableTypedData_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_TwoByteString_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_Type_InstanceSize = 64;
+static constexpr dart::compiler::target::word AOT_TypeArguments_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_TypeParameter_InstanceSize =
+    72;
+static constexpr dart::compiler::target::word AOT_TypeRef_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word AOT_TypedDataView_InstanceSize =
+    40;
+static constexpr dart::compiler::target::word
+    AOT_UnhandledException_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_UnlinkedCall_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_UnwindError_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_UserTag_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_WeakProperty_InstanceSize =
+    32;
 #endif  // defined(TARGET_ARCH_X64)
 
 #if defined(TARGET_ARCH_IA32)
@@ -3879,10 +4700,10 @@
 static constexpr dart::compiler::target::word
     AOT_Class_declaration_type_offset = 112;
 static constexpr dart::compiler::target::word
-    AOT_Class_num_type_arguments_offset = 182;
+    AOT_Class_num_type_arguments_offset = 170;
 static constexpr dart::compiler::target::word AOT_Class_super_type_offset = 88;
 static constexpr dart::compiler::target::word
-    AOT_Class_type_arguments_field_offset_in_words_offset = 172;
+    AOT_Class_host_type_arguments_field_offset_in_words_offset = 184;
 static constexpr dart::compiler::target::word
     AOT_ClassTable_shared_class_table_offset = 32;
 static constexpr dart::compiler::target::word AOT_ClassTable_table_offset = 16;
@@ -3949,6 +4770,8 @@
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_index_offset =
     16;
 static constexpr dart::compiler::target::word
+    AOT_LinkedHashMap_type_arguments_offset = 8;
+static constexpr dart::compiler::target::word
     AOT_LinkedHashMap_used_data_offset = 40;
 static constexpr dart::compiler::target::word
     AOT_MarkingStackBlock_pointers_offset = 16;
@@ -3980,6 +4803,8 @@
 static constexpr dart::compiler::target::word
     AOT_Pointer_c_memory_address_offset = 16;
 static constexpr dart::compiler::target::word
+    AOT_Pointer_type_arguments_offset = 8;
+static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_entry_point_offset = 16;
 static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_lower_limit_offset = 24;
@@ -4197,28 +5022,121 @@
         1248, 1256, 1264, 1272, 1280, 1288, 1296, 1304, 1312, 1320, 1328,
         1336, 1344, 1352, 1360, -1,   -1,   -1,   -1,   1368, 1376, 1384,
         -1,   1392, 1400, 1408, -1,   -1,   -1,   -1,   -1,   -1};
+static constexpr dart::compiler::target::word AOT_ApiError_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Array_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Array_header_size = 24;
+static constexpr dart::compiler::target::word AOT_Bool_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_Bytecode_InstanceSize = 88;
+static constexpr dart::compiler::target::word AOT_Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Class_InstanceSize = 192;
+static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word AOT_ClosureData_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_Code_InstanceSize = 152;
+static constexpr dart::compiler::target::word AOT_CodeSourceMap_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_CompressedStackMaps_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_Context_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Context_header_size = 24;
+static constexpr dart::compiler::target::word AOT_ContextScope_InstanceSize =
+    16;
 static constexpr dart::compiler::target::word AOT_Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_DynamicLibrary_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_ExceptionHandlers_InstanceSize = 24;
+static constexpr dart::compiler::target::word
+    AOT_ExternalOneByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTwoByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word
+    AOT_FfiTrampolineData_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Field_InstanceSize = 80;
 static constexpr dart::compiler::target::word AOT_Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Function_InstanceSize = 104;
+static constexpr dart::compiler::target::word
+    AOT_GrowableObjectArray_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_ICData_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Instructions_InstanceSize =
+    12;
 static constexpr dart::compiler::target::word
     AOT_Instructions_UnalignedHeaderSize = 12;
 static constexpr dart::compiler::target::word AOT_Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
-    32;
-static constexpr dart::compiler::target::word AOT_String_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 24;
-static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 8;
-static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
-    24;
-static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word AOT_Integer_InstanceSize = 8;
 static constexpr dart::compiler::target::word
-    AOT_GrowableObjectArray_InstanceSize = 32;
-static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 8;
+    AOT_KernelProgramInfo_InstanceSize = 128;
+static constexpr dart::compiler::target::word AOT_LanguageError_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word AOT_Library_InstanceSize = 136;
+static constexpr dart::compiler::target::word AOT_LibraryPrefix_InstanceSize =
+    40;
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_InstanceSize =
     56;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_MegamorphicCache_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_MirrorReference_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_MonomorphicSmiableCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_Namespace_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
+    32;
+static constexpr dart::compiler::target::word AOT_Number_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_ObjectPool_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_OneByteString_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_ParameterTypeCheck_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_PatchClass_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_PcDescriptors_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_Pointer_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_ReceivePort_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_RedirectionData_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_RegExp_InstanceSize = 120;
+static constexpr dart::compiler::target::word AOT_Script_InstanceSize = 96;
+static constexpr dart::compiler::target::word AOT_SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_SignatureData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word
+    AOT_SingleTargetCache_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_Smi_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_StackTrace_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_String_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_SubtypeTestCache_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_TransferableTypedData_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_TwoByteString_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_Type_InstanceSize = 64;
+static constexpr dart::compiler::target::word AOT_TypeArguments_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_TypeParameter_InstanceSize =
+    72;
+static constexpr dart::compiler::target::word AOT_TypeRef_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word AOT_TypedDataView_InstanceSize =
+    40;
+static constexpr dart::compiler::target::word
+    AOT_UnhandledException_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_UnlinkedCall_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_UnwindError_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_UserTag_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_WeakProperty_InstanceSize =
+    32;
 #endif  // defined(TARGET_ARCH_ARM64)
 
 #else  // !defined(PRODUCT)
@@ -4285,10 +5203,10 @@
 static constexpr dart::compiler::target::word
     AOT_Class_declaration_type_offset = 56;
 static constexpr dart::compiler::target::word
-    AOT_Class_num_type_arguments_offset = 102;
+    AOT_Class_num_type_arguments_offset = 90;
 static constexpr dart::compiler::target::word AOT_Class_super_type_offset = 44;
 static constexpr dart::compiler::target::word
-    AOT_Class_type_arguments_field_offset_in_words_offset = 92;
+    AOT_Class_host_type_arguments_field_offset_in_words_offset = 104;
 static constexpr dart::compiler::target::word
     AOT_ClassTable_shared_class_table_offset = 16;
 static constexpr dart::compiler::target::word AOT_ClassTable_table_offset = 8;
@@ -4351,6 +5269,8 @@
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_index_offset =
     8;
 static constexpr dart::compiler::target::word
+    AOT_LinkedHashMap_type_arguments_offset = 4;
+static constexpr dart::compiler::target::word
     AOT_LinkedHashMap_used_data_offset = 20;
 static constexpr dart::compiler::target::word
     AOT_MarkingStackBlock_pointers_offset = 8;
@@ -4382,6 +5302,8 @@
 static constexpr dart::compiler::target::word
     AOT_Pointer_c_memory_address_offset = 8;
 static constexpr dart::compiler::target::word
+    AOT_Pointer_type_arguments_offset = 4;
+static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_entry_point_offset = 8;
 static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_lower_limit_offset = 12;
@@ -4594,28 +5516,120 @@
     AOT_Thread_write_barrier_wrappers_thread_offset[] = {
         628, 632, 636, 640, 644, -1, 648, 652,
         656, 660, -1,  -1,  -1,  -1, -1,  -1};
+static constexpr dart::compiler::target::word AOT_ApiError_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Array_InstanceSize = 12;
 static constexpr dart::compiler::target::word AOT_Array_header_size = 12;
+static constexpr dart::compiler::target::word AOT_Bool_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Bytecode_InstanceSize = 44;
+static constexpr dart::compiler::target::word AOT_Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Class_InstanceSize = 112;
+static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 28;
+static constexpr dart::compiler::target::word AOT_ClosureData_InstanceSize = 20;
+static constexpr dart::compiler::target::word AOT_Code_InstanceSize = 60;
+static constexpr dart::compiler::target::word AOT_CodeSourceMap_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word
+    AOT_CompressedStackMaps_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Context_InstanceSize = 12;
 static constexpr dart::compiler::target::word AOT_Context_header_size = 12;
+static constexpr dart::compiler::target::word AOT_ContextScope_InstanceSize =
+    12;
 static constexpr dart::compiler::target::word AOT_Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_DynamicLibrary_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word
+    AOT_ExceptionHandlers_InstanceSize = 12;
+static constexpr dart::compiler::target::word
+    AOT_ExternalOneByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTwoByteString_InstanceSize = 20;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTypedData_InstanceSize = 12;
+static constexpr dart::compiler::target::word
+    AOT_FfiTrampolineData_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Field_InstanceSize = 48;
 static constexpr dart::compiler::target::word AOT_Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Function_InstanceSize = 56;
+static constexpr dart::compiler::target::word
+    AOT_GrowableObjectArray_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_ICData_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 4;
+static constexpr dart::compiler::target::word AOT_Instructions_InstanceSize = 8;
 static constexpr dart::compiler::target::word
     AOT_Instructions_UnalignedHeaderSize = 8;
 static constexpr dart::compiler::target::word AOT_Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
-    16;
-static constexpr dart::compiler::target::word AOT_String_InstanceSize = 12;
-static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 12;
-static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 4;
-static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
-    12;
-static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 28;
+static constexpr dart::compiler::target::word AOT_Integer_InstanceSize = 4;
 static constexpr dart::compiler::target::word
-    AOT_GrowableObjectArray_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 4;
+    AOT_KernelProgramInfo_InstanceSize = 64;
+static constexpr dart::compiler::target::word AOT_LanguageError_InstanceSize =
+    28;
+static constexpr dart::compiler::target::word AOT_Library_InstanceSize = 72;
+static constexpr dart::compiler::target::word AOT_LibraryPrefix_InstanceSize =
+    20;
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_InstanceSize =
     28;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    AOT_MegamorphicCache_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_MirrorReference_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word
+    AOT_MonomorphicSmiableCall_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Namespace_InstanceSize = 20;
+static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
+    16;
+static constexpr dart::compiler::target::word AOT_Number_InstanceSize = 4;
+static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 4;
+static constexpr dart::compiler::target::word AOT_ObjectPool_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_OneByteString_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word
+    AOT_ParameterTypeCheck_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_PatchClass_InstanceSize = 20;
+static constexpr dart::compiler::target::word AOT_PcDescriptors_InstanceSize =
+    8;
+static constexpr dart::compiler::target::word AOT_Pointer_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_ReceivePort_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_RedirectionData_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_RegExp_InstanceSize = 60;
+static constexpr dart::compiler::target::word AOT_Script_InstanceSize = 56;
+static constexpr dart::compiler::target::word AOT_SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_SignatureData_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word
+    AOT_SingleTargetCache_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Smi_InstanceSize = 4;
+static constexpr dart::compiler::target::word AOT_StackTrace_InstanceSize = 20;
+static constexpr dart::compiler::target::word AOT_String_InstanceSize = 12;
+static constexpr dart::compiler::target::word
+    AOT_SubtypeTestCache_InstanceSize = 8;
+static constexpr dart::compiler::target::word
+    AOT_TransferableTypedData_InstanceSize = 4;
+static constexpr dart::compiler::target::word AOT_TwoByteString_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word AOT_Type_InstanceSize = 36;
+static constexpr dart::compiler::target::word AOT_TypeArguments_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_TypeParameter_InstanceSize =
+    40;
+static constexpr dart::compiler::target::word AOT_TypeRef_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
+    12;
+static constexpr dart::compiler::target::word AOT_TypedDataView_InstanceSize =
+    20;
+static constexpr dart::compiler::target::word
+    AOT_UnhandledException_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_UnlinkedCall_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_UnwindError_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_UserTag_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_WeakProperty_InstanceSize =
+    16;
 #endif  // defined(TARGET_ARCH_ARM)
 
 #if defined(TARGET_ARCH_X64)
@@ -4680,10 +5694,10 @@
 static constexpr dart::compiler::target::word
     AOT_Class_declaration_type_offset = 112;
 static constexpr dart::compiler::target::word
-    AOT_Class_num_type_arguments_offset = 182;
+    AOT_Class_num_type_arguments_offset = 170;
 static constexpr dart::compiler::target::word AOT_Class_super_type_offset = 88;
 static constexpr dart::compiler::target::word
-    AOT_Class_type_arguments_field_offset_in_words_offset = 172;
+    AOT_Class_host_type_arguments_field_offset_in_words_offset = 184;
 static constexpr dart::compiler::target::word
     AOT_ClassTable_shared_class_table_offset = 32;
 static constexpr dart::compiler::target::word AOT_ClassTable_table_offset = 16;
@@ -4746,6 +5760,8 @@
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_index_offset =
     16;
 static constexpr dart::compiler::target::word
+    AOT_LinkedHashMap_type_arguments_offset = 8;
+static constexpr dart::compiler::target::word
     AOT_LinkedHashMap_used_data_offset = 40;
 static constexpr dart::compiler::target::word
     AOT_MarkingStackBlock_pointers_offset = 16;
@@ -4777,6 +5793,8 @@
 static constexpr dart::compiler::target::word
     AOT_Pointer_c_memory_address_offset = 16;
 static constexpr dart::compiler::target::word
+    AOT_Pointer_type_arguments_offset = 8;
+static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_entry_point_offset = 16;
 static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_lower_limit_offset = 24;
@@ -4990,28 +6008,121 @@
     AOT_Thread_write_barrier_wrappers_thread_offset[] = {
         1248, 1256, 1264, 1272, -1,   -1,   1280, 1288,
         1296, 1304, 1312, -1,   1320, 1328, -1,   -1};
+static constexpr dart::compiler::target::word AOT_ApiError_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Array_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Array_header_size = 24;
+static constexpr dart::compiler::target::word AOT_Bool_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_Bytecode_InstanceSize = 80;
+static constexpr dart::compiler::target::word AOT_Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Class_InstanceSize = 192;
+static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word AOT_ClosureData_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_Code_InstanceSize = 120;
+static constexpr dart::compiler::target::word AOT_CodeSourceMap_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_CompressedStackMaps_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_Context_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Context_header_size = 24;
+static constexpr dart::compiler::target::word AOT_ContextScope_InstanceSize =
+    16;
 static constexpr dart::compiler::target::word AOT_Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_DynamicLibrary_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_ExceptionHandlers_InstanceSize = 24;
+static constexpr dart::compiler::target::word
+    AOT_ExternalOneByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTwoByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word
+    AOT_FfiTrampolineData_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Field_InstanceSize = 80;
 static constexpr dart::compiler::target::word AOT_Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Function_InstanceSize = 104;
+static constexpr dart::compiler::target::word
+    AOT_GrowableObjectArray_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_ICData_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Instructions_InstanceSize =
+    12;
 static constexpr dart::compiler::target::word
     AOT_Instructions_UnalignedHeaderSize = 12;
 static constexpr dart::compiler::target::word AOT_Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
-    32;
-static constexpr dart::compiler::target::word AOT_String_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 24;
-static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 8;
-static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
-    24;
-static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word AOT_Integer_InstanceSize = 8;
 static constexpr dart::compiler::target::word
-    AOT_GrowableObjectArray_InstanceSize = 32;
-static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 8;
+    AOT_KernelProgramInfo_InstanceSize = 128;
+static constexpr dart::compiler::target::word AOT_LanguageError_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word AOT_Library_InstanceSize = 136;
+static constexpr dart::compiler::target::word AOT_LibraryPrefix_InstanceSize =
+    40;
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_InstanceSize =
     56;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_MegamorphicCache_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_MirrorReference_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_MonomorphicSmiableCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_Namespace_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
+    32;
+static constexpr dart::compiler::target::word AOT_Number_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_ObjectPool_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_OneByteString_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_ParameterTypeCheck_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_PatchClass_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_PcDescriptors_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_Pointer_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_ReceivePort_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_RedirectionData_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_RegExp_InstanceSize = 120;
+static constexpr dart::compiler::target::word AOT_Script_InstanceSize = 96;
+static constexpr dart::compiler::target::word AOT_SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_SignatureData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word
+    AOT_SingleTargetCache_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_Smi_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_StackTrace_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_String_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_SubtypeTestCache_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_TransferableTypedData_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_TwoByteString_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_Type_InstanceSize = 64;
+static constexpr dart::compiler::target::word AOT_TypeArguments_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_TypeParameter_InstanceSize =
+    72;
+static constexpr dart::compiler::target::word AOT_TypeRef_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word AOT_TypedDataView_InstanceSize =
+    40;
+static constexpr dart::compiler::target::word
+    AOT_UnhandledException_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_UnlinkedCall_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_UnwindError_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_UserTag_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_WeakProperty_InstanceSize =
+    32;
 #endif  // defined(TARGET_ARCH_X64)
 
 #if defined(TARGET_ARCH_IA32)
@@ -5079,10 +6190,10 @@
 static constexpr dart::compiler::target::word
     AOT_Class_declaration_type_offset = 112;
 static constexpr dart::compiler::target::word
-    AOT_Class_num_type_arguments_offset = 182;
+    AOT_Class_num_type_arguments_offset = 170;
 static constexpr dart::compiler::target::word AOT_Class_super_type_offset = 88;
 static constexpr dart::compiler::target::word
-    AOT_Class_type_arguments_field_offset_in_words_offset = 172;
+    AOT_Class_host_type_arguments_field_offset_in_words_offset = 184;
 static constexpr dart::compiler::target::word
     AOT_ClassTable_shared_class_table_offset = 32;
 static constexpr dart::compiler::target::word AOT_ClassTable_table_offset = 16;
@@ -5145,6 +6256,8 @@
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_index_offset =
     16;
 static constexpr dart::compiler::target::word
+    AOT_LinkedHashMap_type_arguments_offset = 8;
+static constexpr dart::compiler::target::word
     AOT_LinkedHashMap_used_data_offset = 40;
 static constexpr dart::compiler::target::word
     AOT_MarkingStackBlock_pointers_offset = 16;
@@ -5176,6 +6289,8 @@
 static constexpr dart::compiler::target::word
     AOT_Pointer_c_memory_address_offset = 16;
 static constexpr dart::compiler::target::word
+    AOT_Pointer_type_arguments_offset = 8;
+static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_entry_point_offset = 16;
 static constexpr dart::compiler::target::word
     AOT_SingleTargetCache_lower_limit_offset = 24;
@@ -5390,28 +6505,121 @@
         1248, 1256, 1264, 1272, 1280, 1288, 1296, 1304, 1312, 1320, 1328,
         1336, 1344, 1352, 1360, -1,   -1,   -1,   -1,   1368, 1376, 1384,
         -1,   1392, 1400, 1408, -1,   -1,   -1,   -1,   -1,   -1};
+static constexpr dart::compiler::target::word AOT_ApiError_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Array_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Array_header_size = 24;
+static constexpr dart::compiler::target::word AOT_Bool_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_Bytecode_InstanceSize = 80;
+static constexpr dart::compiler::target::word AOT_Capability_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_Class_InstanceSize = 192;
+static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word AOT_ClosureData_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_Code_InstanceSize = 120;
+static constexpr dart::compiler::target::word AOT_CodeSourceMap_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_CompressedStackMaps_InstanceSize = 12;
+static constexpr dart::compiler::target::word AOT_Context_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Context_header_size = 24;
+static constexpr dart::compiler::target::word AOT_ContextScope_InstanceSize =
+    16;
 static constexpr dart::compiler::target::word AOT_Double_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_DynamicLibrary_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_ExceptionHandlers_InstanceSize = 24;
+static constexpr dart::compiler::target::word
+    AOT_ExternalOneByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTwoByteString_InstanceSize = 32;
+static constexpr dart::compiler::target::word
+    AOT_ExternalTypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word
+    AOT_FfiTrampolineData_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Field_InstanceSize = 80;
 static constexpr dart::compiler::target::word AOT_Float32x4_InstanceSize = 24;
 static constexpr dart::compiler::target::word AOT_Float64x2_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_Function_InstanceSize = 104;
+static constexpr dart::compiler::target::word
+    AOT_GrowableObjectArray_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_ICData_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Instructions_InstanceSize =
+    12;
 static constexpr dart::compiler::target::word
     AOT_Instructions_UnalignedHeaderSize = 12;
 static constexpr dart::compiler::target::word AOT_Int32x4_InstanceSize = 24;
-static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
-    32;
-static constexpr dart::compiler::target::word AOT_String_InstanceSize = 16;
-static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 24;
-static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 8;
-static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
-    24;
-static constexpr dart::compiler::target::word AOT_Closure_InstanceSize = 56;
+static constexpr dart::compiler::target::word AOT_Integer_InstanceSize = 8;
 static constexpr dart::compiler::target::word
-    AOT_GrowableObjectArray_InstanceSize = 32;
-static constexpr dart::compiler::target::word AOT_Instance_InstanceSize = 8;
+    AOT_KernelProgramInfo_InstanceSize = 128;
+static constexpr dart::compiler::target::word AOT_LanguageError_InstanceSize =
+    48;
+static constexpr dart::compiler::target::word AOT_Library_InstanceSize = 136;
+static constexpr dart::compiler::target::word AOT_LibraryPrefix_InstanceSize =
+    40;
 static constexpr dart::compiler::target::word AOT_LinkedHashMap_InstanceSize =
     56;
+static constexpr dart::compiler::target::word
+    AOT_LocalVarDescriptors_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_MegamorphicCache_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_Mint_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_MirrorReference_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_MonomorphicSmiableCall_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_Namespace_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_NativeArguments_StructSize =
+    32;
+static constexpr dart::compiler::target::word AOT_Number_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_Object_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_ObjectPool_InstanceSize = 16;
+static constexpr dart::compiler::target::word AOT_OneByteString_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word
+    AOT_ParameterTypeCheck_InstanceSize = 48;
+static constexpr dart::compiler::target::word AOT_PatchClass_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_PcDescriptors_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_Pointer_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_ReceivePort_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_RedirectionData_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_RegExp_InstanceSize = 120;
+static constexpr dart::compiler::target::word AOT_Script_InstanceSize = 96;
+static constexpr dart::compiler::target::word AOT_SendPort_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_SignatureData_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word
+    AOT_SingleTargetCache_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_Smi_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_StackTrace_InstanceSize = 40;
+static constexpr dart::compiler::target::word AOT_String_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_SubtypeTestCache_InstanceSize = 16;
+static constexpr dart::compiler::target::word
+    AOT_TransferableTypedData_InstanceSize = 8;
+static constexpr dart::compiler::target::word AOT_TwoByteString_InstanceSize =
+    16;
+static constexpr dart::compiler::target::word AOT_Type_InstanceSize = 64;
+static constexpr dart::compiler::target::word AOT_TypeArguments_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_TypeParameter_InstanceSize =
+    72;
+static constexpr dart::compiler::target::word AOT_TypeRef_InstanceSize = 32;
+static constexpr dart::compiler::target::word AOT_TypedData_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_TypedDataBase_InstanceSize =
+    24;
+static constexpr dart::compiler::target::word AOT_TypedDataView_InstanceSize =
+    40;
+static constexpr dart::compiler::target::word
+    AOT_UnhandledException_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_UnlinkedCall_InstanceSize =
+    32;
+static constexpr dart::compiler::target::word AOT_UnwindError_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_UserTag_InstanceSize = 24;
+static constexpr dart::compiler::target::word AOT_WeakProperty_InstanceSize =
+    32;
 #endif  // defined(TARGET_ARCH_ARM64)
 
 #endif  // !defined(PRODUCT)
diff --git a/runtime/vm/compiler/runtime_offsets_list.h b/runtime/vm/compiler/runtime_offsets_list.h
index 3c243bb..296daf4 100644
--- a/runtime/vm/compiler/runtime_offsets_list.h
+++ b/runtime/vm/compiler/runtime_offsets_list.h
@@ -64,7 +64,7 @@
   FIELD(Class, declaration_type_offset)                                        \
   FIELD(Class, num_type_arguments_offset)                                      \
   FIELD(Class, super_type_offset)                                              \
-  FIELD(Class, type_arguments_field_offset_in_words_offset)                    \
+  FIELD(Class, host_type_arguments_field_offset_in_words_offset)               \
   FIELD(ClassTable, shared_class_table_offset)                                 \
   FIELD(ClassTable, table_offset)                                              \
   NOT_IN_PRODUCT(FIELD(SharedClassTable, class_heap_stats_table_offset))       \
@@ -115,6 +115,7 @@
   FIELD(LinkedHashMap, deleted_keys_offset)                                    \
   FIELD(LinkedHashMap, hash_mask_offset)                                       \
   FIELD(LinkedHashMap, index_offset)                                           \
+  FIELD(LinkedHashMap, type_arguments_offset)                                  \
   FIELD(LinkedHashMap, used_data_offset)                                       \
   FIELD(MarkingStackBlock, pointers_offset)                                    \
   FIELD(MarkingStackBlock, top_offset)                                         \
@@ -131,6 +132,7 @@
   FIELD(ObjectStore, string_type_offset)                                       \
   FIELD(OneByteString, data_offset)                                            \
   FIELD(Pointer, c_memory_address_offset)                                      \
+  FIELD(Pointer, type_arguments_offset)                                        \
   FIELD(SingleTargetCache, entry_point_offset)                                 \
   FIELD(SingleTargetCache, lower_limit_offset)                                 \
   FIELD(SingleTargetCache, target_offset)                                      \
@@ -251,22 +253,84 @@
       Thread, write_barrier_wrappers_thread_offset, Register, 0,               \
       kNumberOfCpuRegisters - 1,                                               \
       [](Register reg) { return (kDartAvailableCpuRegs & (1 << reg)) != 0; })) \
+                                                                               \
+  SIZEOF(ApiError, InstanceSize, RawApiError)                                  \
+  SIZEOF(Array, InstanceSize, RawArray)                                        \
   SIZEOF(Array, header_size, RawArray)                                         \
+  SIZEOF(Bool, InstanceSize, RawBool)                                          \
+  SIZEOF(Bytecode, InstanceSize, RawBytecode)                                  \
+  SIZEOF(Capability, InstanceSize, RawCapability)                              \
+  SIZEOF(Class, InstanceSize, RawClass)                                        \
+  SIZEOF(Closure, InstanceSize, RawClosure)                                    \
+  SIZEOF(ClosureData, InstanceSize, RawClosureData)                            \
+  SIZEOF(Code, InstanceSize, RawCode)                                          \
+  SIZEOF(CodeSourceMap, InstanceSize, RawCodeSourceMap)                        \
+  SIZEOF(CompressedStackMaps, InstanceSize, RawCompressedStackMaps)            \
+  SIZEOF(Context, InstanceSize, RawContext)                                    \
   SIZEOF(Context, header_size, RawContext)                                     \
+  SIZEOF(ContextScope, InstanceSize, RawContextScope)                          \
   SIZEOF(Double, InstanceSize, RawDouble)                                      \
+  SIZEOF(DynamicLibrary, InstanceSize, RawDynamicLibrary)                      \
+  SIZEOF(ExceptionHandlers, InstanceSize, RawExceptionHandlers)                \
+  SIZEOF(ExternalOneByteString, InstanceSize, RawExternalOneByteString)        \
+  SIZEOF(ExternalTwoByteString, InstanceSize, RawExternalTwoByteString)        \
+  SIZEOF(ExternalTypedData, InstanceSize, RawExternalTypedData)                \
+  SIZEOF(FfiTrampolineData, InstanceSize, RawFfiTrampolineData)                \
+  SIZEOF(Field, InstanceSize, RawField)                                        \
   SIZEOF(Float32x4, InstanceSize, RawFloat32x4)                                \
   SIZEOF(Float64x2, InstanceSize, RawFloat64x2)                                \
+  SIZEOF(Function, InstanceSize, RawFunction)                                  \
+  SIZEOF(GrowableObjectArray, InstanceSize, RawGrowableObjectArray)            \
+  SIZEOF(ICData, InstanceSize, RawICData)                                      \
+  SIZEOF(Instance, InstanceSize, RawInstance)                                  \
+  SIZEOF(Instructions, InstanceSize, RawInstructions)                          \
   SIZEOF(Instructions, UnalignedHeaderSize, RawInstructions)                   \
   SIZEOF(Int32x4, InstanceSize, RawInt32x4)                                    \
+  SIZEOF(Integer, InstanceSize, RawInteger)                                    \
+  SIZEOF(KernelProgramInfo, InstanceSize, RawKernelProgramInfo)                \
+  SIZEOF(LanguageError, InstanceSize, RawLanguageError)                        \
+  SIZEOF(Library, InstanceSize, RawLibrary)                                    \
+  SIZEOF(LibraryPrefix, InstanceSize, RawLibraryPrefix)                        \
+  SIZEOF(LinkedHashMap, InstanceSize, RawLinkedHashMap)                        \
+  SIZEOF(LocalVarDescriptors, InstanceSize, RawLocalVarDescriptors)            \
+  SIZEOF(MegamorphicCache, InstanceSize, RawMegamorphicCache)                  \
   SIZEOF(Mint, InstanceSize, RawMint)                                          \
+  SIZEOF(MirrorReference, InstanceSize, RawMirrorReference)                    \
+  SIZEOF(MonomorphicSmiableCall, InstanceSize, RawMonomorphicSmiableCall)      \
+  SIZEOF(Namespace, InstanceSize, RawNamespace)                                \
   SIZEOF(NativeArguments, StructSize, NativeArguments)                         \
-  SIZEOF(String, InstanceSize, RawString)                                      \
-  SIZEOF(TypedData, InstanceSize, RawTypedData)                                \
+  SIZEOF(Number, InstanceSize, RawNumber)                                      \
   SIZEOF(Object, InstanceSize, RawObject)                                      \
+  SIZEOF(ObjectPool, InstanceSize, RawObjectPool)                              \
+  SIZEOF(OneByteString, InstanceSize, RawOneByteString)                        \
+  SIZEOF(ParameterTypeCheck, InstanceSize, RawParameterTypeCheck)              \
+  SIZEOF(PatchClass, InstanceSize, RawPatchClass)                              \
+  SIZEOF(PcDescriptors, InstanceSize, RawPcDescriptors)                        \
+  SIZEOF(Pointer, InstanceSize, RawPointer)                                    \
+  SIZEOF(ReceivePort, InstanceSize, RawReceivePort)                            \
+  SIZEOF(RedirectionData, InstanceSize, RawRedirectionData)                    \
+  SIZEOF(RegExp, InstanceSize, RawRegExp)                                      \
+  SIZEOF(Script, InstanceSize, RawScript)                                      \
+  SIZEOF(SendPort, InstanceSize, RawSendPort)                                  \
+  SIZEOF(SignatureData, InstanceSize, RawSignatureData)                        \
+  SIZEOF(SingleTargetCache, InstanceSize, RawSingleTargetCache)                \
+  SIZEOF(Smi, InstanceSize, RawSmi)                                            \
+  SIZEOF(StackTrace, InstanceSize, RawStackTrace)                              \
+  SIZEOF(String, InstanceSize, RawString)                                      \
+  SIZEOF(SubtypeTestCache, InstanceSize, RawSubtypeTestCache)                  \
+  SIZEOF(TransferableTypedData, InstanceSize, RawTransferableTypedData)        \
+  SIZEOF(TwoByteString, InstanceSize, RawTwoByteString)                        \
+  SIZEOF(Type, InstanceSize, RawType)                                          \
+  SIZEOF(TypeArguments, InstanceSize, RawTypeArguments)                        \
+  SIZEOF(TypeParameter, InstanceSize, RawTypeParameter)                        \
+  SIZEOF(TypeRef, InstanceSize, RawTypeRef)                                    \
+  SIZEOF(TypedData, InstanceSize, RawTypedData)                                \
   SIZEOF(TypedDataBase, InstanceSize, RawTypedDataBase)                        \
-  SIZEOF(Closure, InstanceSize, RawClosure)                                    \
-  SIZEOF(GrowableObjectArray, InstanceSize, RawGrowableObjectArray)            \
-  SIZEOF(Instance, InstanceSize, RawInstance)                                  \
-  SIZEOF(LinkedHashMap, InstanceSize, RawLinkedHashMap)
+  SIZEOF(TypedDataView, InstanceSize, RawTypedDataView)                        \
+  SIZEOF(UnhandledException, InstanceSize, RawUnhandledException)              \
+  SIZEOF(UnlinkedCall, InstanceSize, RawUnlinkedCall)                          \
+  SIZEOF(UnwindError, InstanceSize, RawUnwindError)                            \
+  SIZEOF(UserTag, InstanceSize, RawUserTag)                                    \
+  SIZEOF(WeakProperty, InstanceSize, RawWeakProperty)
 
 #endif  // RUNTIME_VM_COMPILER_RUNTIME_OFFSETS_LIST_H_
diff --git a/runtime/vm/compiler/stub_code_compiler_arm.cc b/runtime/vm/compiler/stub_code_compiler_arm.cc
index b6f3c2b..0fdf071 100644
--- a/runtime/vm/compiler/stub_code_compiler_arm.cc
+++ b/runtime/vm/compiler/stub_code_compiler_arm.cc
@@ -2726,8 +2726,8 @@
       __ mov(kInstanceInstantiatorTypeArgumentsReg, Operand(kNullReg));
       __ ldr(R9,
              FieldAddress(
-                 R9,
-                 target::Class::type_arguments_field_offset_in_words_offset()));
+                 R9, target::Class::
+                         host_type_arguments_field_offset_in_words_offset()));
       __ CompareImmediate(R9, target::Class::kNoTypeArguments);
       __ b(&has_no_type_arguments, EQ);
       __ add(R9, kInstanceReg, Operand(R9, LSL, 2));
diff --git a/runtime/vm/compiler/stub_code_compiler_arm64.cc b/runtime/vm/compiler/stub_code_compiler_arm64.cc
index cab25a1..34d927a 100644
--- a/runtime/vm/compiler/stub_code_compiler_arm64.cc
+++ b/runtime/vm/compiler/stub_code_compiler_arm64.cc
@@ -2851,7 +2851,8 @@
       __ LoadClassById(R5, kInstanceCidOrFunction);
       __ mov(kInstanceInstantiatorTypeArgumentsReg, kNullReg);
       __ LoadFieldFromOffset(
-          R5, R5, target::Class::type_arguments_field_offset_in_words_offset(),
+          R5, R5,
+          target::Class::host_type_arguments_field_offset_in_words_offset(),
           kWord);
       __ CompareImmediate(R5, target::Class::kNoTypeArguments);
       __ b(&has_no_type_arguments, EQ);
diff --git a/runtime/vm/compiler/stub_code_compiler_ia32.cc b/runtime/vm/compiler/stub_code_compiler_ia32.cc
index 6556b7d..6510cb5 100644
--- a/runtime/vm/compiler/stub_code_compiler_ia32.cc
+++ b/runtime/vm/compiler/stub_code_compiler_ia32.cc
@@ -2349,11 +2349,10 @@
       Label has_no_type_arguments;
       __ LoadClassById(EDI, kInstanceCidOrFunction);
       __ movl(kInstanceInstantiatorTypeArgumentsReg, raw_null);
-      __ movl(
-          EDI,
-          FieldAddress(
-              EDI,
-              target::Class::type_arguments_field_offset_in_words_offset()));
+      __ movl(EDI,
+              FieldAddress(
+                  EDI, target::Class::
+                           host_type_arguments_field_offset_in_words_offset()));
       __ cmpl(EDI, Immediate(target::Class::kNoTypeArguments));
       __ j(EQUAL, &has_no_type_arguments, Assembler::kNearJump);
       __ movl(kInstanceInstantiatorTypeArgumentsReg,
diff --git a/runtime/vm/compiler/stub_code_compiler_x64.cc b/runtime/vm/compiler/stub_code_compiler_x64.cc
index 3920de2..a8cf49d 100644
--- a/runtime/vm/compiler/stub_code_compiler_x64.cc
+++ b/runtime/vm/compiler/stub_code_compiler_x64.cc
@@ -2807,11 +2807,10 @@
       Label has_no_type_arguments;
       __ LoadClassById(RDI, kInstanceCidOrFunction);
       __ movq(kInstanceInstantiatorTypeArgumentsReg, kNullReg);
-      __ movl(
-          RDI,
-          FieldAddress(
-              RDI,
-              target::Class::type_arguments_field_offset_in_words_offset()));
+      __ movl(RDI,
+              FieldAddress(
+                  RDI, target::Class::
+                           host_type_arguments_field_offset_in_words_offset()));
       __ cmpl(RDI, Immediate(target::Class::kNoTypeArguments));
       __ j(EQUAL, &has_no_type_arguments, Assembler::kNearJump);
       __ movq(kInstanceInstantiatorTypeArgumentsReg,
diff --git a/runtime/vm/dart.h b/runtime/vm/dart.h
index 3399ca5..c44b0cc 100644
--- a/runtime/vm/dart.h
+++ b/runtime/vm/dart.h
@@ -123,8 +123,16 @@
   static Dart_EntropySource entropy_source_callback() {
     return entropy_source_callback_;
   }
+
+  // TODO(dartbug.com/40342): Delete these functions.
   static void set_non_nullable_flag(bool value) { non_nullable_flag_ = value; }
-  static bool non_nullable_flag() { return non_nullable_flag_; }
+  static bool non_nullable_flag() {
+#ifdef DART_BUILT_WITH_NNBD_FLAG
+    return true;
+#else
+    return non_nullable_flag_;
+#endif
+  }
 
  private:
   static void WaitForIsolateShutdown();
diff --git a/runtime/vm/dart_api_impl_test.cc b/runtime/vm/dart_api_impl_test.cc
index bc23cea..23a083a 100644
--- a/runtime/vm/dart_api_impl_test.cc
+++ b/runtime/vm/dart_api_impl_test.cc
@@ -4393,7 +4393,7 @@
   intptr_t header_size = sizeof(RawObject);
   EXPECT_EQ(
       Utils::RoundUp(((1 + 2) * kWordSize) + header_size, kObjectAlignment),
-      cls.instance_size());
+      cls.host_instance_size());
   EXPECT_EQ(kNumNativeFields, cls.num_native_fields());
 }
 
diff --git a/runtime/vm/datastream.h b/runtime/vm/datastream.h
index da4c450..77c74bc 100644
--- a/runtime/vm/datastream.h
+++ b/runtime/vm/datastream.h
@@ -72,7 +72,10 @@
     current_ += len;
   }
 
-  intptr_t ReadUnsigned() { return Read<intptr_t>(kEndUnsignedByteMarker); }
+  template <typename T = intptr_t>
+  T ReadUnsigned() {
+    return Read<T>(kEndUnsignedByteMarker);
+  }
 
   intptr_t Position() const { return current_ - buffer_; }
   void SetPosition(intptr_t value) {
@@ -103,6 +106,19 @@
     return Read<T>(kEndByteMarker);
   }
 
+  uword ReadWordWith32BitReads() {
+    constexpr intptr_t kNumBytesPerRead32 = sizeof(uint32_t);
+    constexpr intptr_t kNumRead32PerWord = sizeof(uword) / kNumBytesPerRead32;
+    constexpr intptr_t kNumBitsPerRead32 = kNumBytesPerRead32 * kBitsPerByte;
+
+    uword value = 0;
+    for (intptr_t j = 0; j < kNumRead32PerWord; j++) {
+      const auto partial_value = Raw<kNumBytesPerRead32, uint32_t>::Read(this);
+      value |= (static_cast<uword>(partial_value) << (j * kNumBitsPerRead32));
+    }
+    return value;
+  }
+
  private:
   int16_t Read16() { return Read16(kEndByteMarker); }
 
@@ -363,8 +379,21 @@
     }
   };
 
-  void WriteUnsigned(intptr_t value) {
-    ASSERT((value >= 0) && (value <= kIntptrMax));
+  void WriteWordWith32BitWrites(uword value) {
+    constexpr intptr_t kNumBytesPerWrite32 = sizeof(uint32_t);
+    constexpr intptr_t kNumWrite32PerWord = sizeof(uword) / kNumBytesPerWrite32;
+    constexpr intptr_t kNumBitsPerWrite32 = kNumBytesPerWrite32 * kBitsPerByte;
+
+    const uint32_t mask = Utils::NBitMask(kNumBitsPerWrite32);
+    for (intptr_t j = 0; j < kNumWrite32PerWord; j++) {
+      const uint32_t shifted_value = (value >> (j * kNumBitsPerWrite32));
+      Raw<kNumBytesPerWrite32, uint32_t>::Write(this, shifted_value & mask);
+    }
+  }
+
+  template <typename T>
+  void WriteUnsigned(T value) {
+    ASSERT(value >= 0);
     while (value > kMaxUnsignedDataPerByte) {
       WriteByte(static_cast<uint8_t>(value & kByteMask));
       value = value >> kDataBitsPerByte;
diff --git a/runtime/vm/deferred_objects.cc b/runtime/vm/deferred_objects.cc
index 7238899..2072c77 100644
--- a/runtime/vm/deferred_objects.cc
+++ b/runtime/vm/deferred_objects.cc
@@ -307,7 +307,7 @@
         // materialization of e.g. _ByteDataView objects which don't have
         // explicit fields in Dart (all accesses to the fields are done via
         // recognized native methods).
-        ASSERT(offset.Value() < cls.instance_size());
+        ASSERT(offset.Value() < cls.host_instance_size());
         obj.SetFieldAtOffset(offset.Value(), value);
         if (FLAG_trace_deoptimization_verbose) {
           OS::PrintErr("    null Field @ offset(%" Pd ") <- %s\n",
diff --git a/runtime/vm/fixed_cache.h b/runtime/vm/fixed_cache.h
index 1af3a93..0b2a5825 100644
--- a/runtime/vm/fixed_cache.h
+++ b/runtime/vm/fixed_cache.h
@@ -8,6 +8,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "vm/lockers.h"
+
 namespace dart {
 
 // A simple sorted fixed size Key-Value storage.
@@ -31,12 +33,16 @@
   ~FixedCache() { Clear(); }
 
   V* Lookup(K key) {
+    MutexLocker ml(&mutex_);
+
     intptr_t i = LowerBound(key);
     if (i != length_ && pairs_[i].key == key) return &pairs_[i].value;
     return NULL;
   }
 
   void Insert(K key, V value) {
+    MutexLocker ml(&mutex_);
+
     intptr_t i = LowerBound(key);
 
     if (length_ == kCapacity) {
@@ -53,7 +59,10 @@
     pairs_[i].value = value;
   }
 
-  void Clear() { length_ = 0; }
+  void Clear() {
+    MutexLocker ml(&mutex_);
+    length_ = 0;
+  }
 
  private:
   intptr_t LowerBound(K key) {
@@ -71,6 +80,10 @@
     return low;
   }
 
+  // We protect any operation on the [FixedCache] because multiple isolates from
+  // the same [IsolateGroup] can access this cache concurrently (as can the GC
+  // when it clears it).
+  Mutex mutex_;
   Entry pairs_[kCapacity];  // Sorted array of pairs.
   intptr_t length_;
 };
diff --git a/runtime/vm/heap/pages.cc b/runtime/vm/heap/pages.cc
index 0fc0a87..0f3be2e 100644
--- a/runtime/vm/heap/pages.cc
+++ b/runtime/vm/heap/pages.cc
@@ -1387,7 +1387,7 @@
 #else
   intptr_t headroom = heap_->new_space()->CapacityInWords();
 #endif
-  return after.CombinedCapacityInWords() > (gc_threshold_in_words_ + headroom);
+  return after.CombinedUsedInWords() > (gc_threshold_in_words_ + headroom);
 }
 
 bool PageSpaceController::AlmostNeedsGarbageCollection(SpaceUsage after) const {
@@ -1397,7 +1397,7 @@
   if (heap_growth_ratio_ == 100) {
     return false;
   }
-  return after.CombinedCapacityInWords() > gc_threshold_in_words_;
+  return after.CombinedUsedInWords() > gc_threshold_in_words_;
 }
 
 bool PageSpaceController::NeedsIdleGarbageCollection(SpaceUsage current) const {
@@ -1407,7 +1407,7 @@
   if (heap_growth_ratio_ == 100) {
     return false;
   }
-  return current.CombinedCapacityInWords() > idle_gc_threshold_in_words_;
+  return current.CombinedUsedInWords() > idle_gc_threshold_in_words_;
 }
 
 void PageSpaceController::EvaluateGarbageCollection(SpaceUsage before,
@@ -1446,9 +1446,9 @@
     // Number of pages we can allocate and still be within the desired growth
     // ratio.
     const intptr_t grow_pages =
-        (static_cast<intptr_t>(after.CombinedCapacityInWords() /
+        (static_cast<intptr_t>(after.CombinedUsedInWords() /
                                desired_utilization_) -
-         (after.CombinedCapacityInWords())) /
+         (after.CombinedUsedInWords())) /
         kPageSizeInWords;
     if (garbage_ratio == 0) {
       // No garbage in the previous cycle so it would be hard to compute a
@@ -1464,8 +1464,8 @@
       intptr_t local_grow_heap = 0;
       while (min < max) {
         local_grow_heap = (max + min) / 2;
-        const intptr_t limit = after.CombinedCapacityInWords() +
-                               (local_grow_heap * kPageSizeInWords);
+        const intptr_t limit =
+            after.CombinedUsedInWords() + (local_grow_heap * kPageSizeInWords);
         const intptr_t allocated_before_next_gc =
             limit - (after.CombinedUsedInWords());
         const double estimated_garbage = k * allocated_before_next_gc;
@@ -1492,7 +1492,7 @@
 
   // Limit shrinkage: allow growth by at least half the pages freed by GC.
   const intptr_t freed_pages =
-      (before.CombinedCapacityInWords() - after.CombinedCapacityInWords()) /
+      (before.CombinedUsedInWords() - after.CombinedUsedInWords()) /
       kPageSizeInWords;
   grow_heap = Utils::Maximum(grow_heap, freed_pages / 2);
   heap_->RecordData(PageSpace::kAllowedGrowth, grow_heap);
@@ -1500,11 +1500,11 @@
 
   // Save final threshold compared before growing.
   gc_threshold_in_words_ =
-      after.CombinedCapacityInWords() + (kPageSizeInWords * grow_heap);
+      after.CombinedUsedInWords() + (kPageSizeInWords * grow_heap);
 
   // Set a tight idle threshold.
   idle_gc_threshold_in_words_ =
-      after.CombinedCapacityInWords() + 2 * kPageSizeInWords;
+      after.CombinedUsedInWords() + (2 * kPageSizeInWords);
 
   RecordUpdate(before, after, "gc");
 }
@@ -1513,9 +1513,9 @@
   // Number of pages we can allocate and still be within the desired growth
   // ratio.
   intptr_t growth_in_pages =
-      (static_cast<intptr_t>(after.CombinedCapacityInWords() /
+      (static_cast<intptr_t>(after.CombinedUsedInWords() /
                              desired_utilization_) -
-       (after.CombinedCapacityInWords())) /
+       (after.CombinedUsedInWords())) /
       kPageSizeInWords;
 
   // Apply growth cap.
@@ -1524,11 +1524,11 @@
 
   // Save final threshold compared before growing.
   gc_threshold_in_words_ =
-      after.CombinedCapacityInWords() + (kPageSizeInWords * growth_in_pages);
+      after.CombinedUsedInWords() + (kPageSizeInWords * growth_in_pages);
 
   // Set a tight idle threshold.
   idle_gc_threshold_in_words_ =
-      after.CombinedCapacityInWords() + 2 * kPageSizeInWords;
+      after.CombinedUsedInWords() + (2 * kPageSizeInWords);
 
   RecordUpdate(after, after, "loaded");
 }
@@ -1540,10 +1540,10 @@
   TIMELINE_FUNCTION_GC_DURATION(Thread::Current(), "UpdateGrowthLimit");
   tbes.SetNumArguments(5);
   tbes.CopyArgument(0, "Reason", reason);
-  tbes.FormatArgument(1, "Before.CombinedCapacity (kB)", "%" Pd "",
-                      RoundWordsToKB(before.CombinedCapacityInWords()));
-  tbes.FormatArgument(2, "After.CombinedCapacity (kB)", "%" Pd "",
-                      RoundWordsToKB(after.CombinedCapacityInWords()));
+  tbes.FormatArgument(1, "Before.CombinedUsed (kB)", "%" Pd "",
+                      RoundWordsToKB(before.CombinedUsedInWords()));
+  tbes.FormatArgument(2, "After.CombinedUsed (kB)", "%" Pd "",
+                      RoundWordsToKB(after.CombinedUsedInWords()));
   tbes.FormatArgument(3, "Threshold (kB)", "%" Pd "",
                       RoundWordsToKB(gc_threshold_in_words_));
   tbes.FormatArgument(4, "Idle Threshold (kB)", "%" Pd "",
diff --git a/runtime/vm/heap/safepoint.h b/runtime/vm/heap/safepoint.h
index 4e677e7..8615b53 100644
--- a/runtime/vm/heap/safepoint.h
+++ b/runtime/vm/heap/safepoint.h
@@ -6,6 +6,7 @@
 #define RUNTIME_VM_HEAP_SAFEPOINT_H_
 
 #include "vm/globals.h"
+#include "vm/isolate.h"
 #include "vm/lockers.h"
 #include "vm/thread.h"
 #include "vm/thread_stack_resource.h"
diff --git a/runtime/vm/heap/scavenger.cc b/runtime/vm/heap/scavenger.cc
index 484821c..0c15bb8 100644
--- a/runtime/vm/heap/scavenger.cc
+++ b/runtime/vm/heap/scavenger.cc
@@ -137,7 +137,7 @@
     view->RecomputeDataFieldForInternalTypedData();
   }
 
-  void VisitPointers(RawObject** first, RawObject** last) {
+  virtual void VisitPointers(RawObject** first, RawObject** last) {
     ASSERT(Utils::IsAligned(first, sizeof(*first)));
     ASSERT(Utils::IsAligned(last, sizeof(*last)));
     for (RawObject** current = first; current <= last; current++) {
diff --git a/runtime/vm/interpreter.cc b/runtime/vm/interpreter.cc
index 7f2b3fb..d59dbfe 100644
--- a/runtime/vm/interpreter.cc
+++ b/runtime/vm/interpreter.cc
@@ -126,10 +126,9 @@
     RawClass* instance_class =
         thread->isolate()->class_table()->At(GetClassId(instance));
     return instance_class->ptr()->num_type_arguments_ > 0
-               ? reinterpret_cast<RawTypeArguments**>(
-                     instance
-                         ->ptr())[instance_class->ptr()
-                                      ->type_arguments_field_offset_in_words_]
+               ? reinterpret_cast<RawTypeArguments**>(instance->ptr())
+                     [instance_class->ptr()
+                          ->host_type_arguments_field_offset_in_words_]
                : TypeArguments::null();
   }
 
@@ -1205,7 +1204,7 @@
       } else if (instance_class->ptr()->num_type_arguments_ > 0) {
         instance_type_arguments = reinterpret_cast<RawTypeArguments**>(
             instance->ptr())[instance_class->ptr()
-                                 ->type_arguments_field_offset_in_words_];
+                                 ->host_type_arguments_field_offset_in_words_];
       }
       parent_function_type_arguments =
           static_cast<RawTypeArguments*>(null_value);
@@ -2333,7 +2332,7 @@
     BYTECODE(InitLateField, D);
     RawField* field = RAW_CAST(Field, LOAD_CONSTANT(rD + 1));
     RawInstance* instance = reinterpret_cast<RawInstance*>(SP[0]);
-    intptr_t offset_in_words = field->ptr()->offset_or_field_id_;
+    intptr_t offset_in_words = field->ptr()->host_offset_or_field_id_;
 
     instance->StorePointer(
         reinterpret_cast<RawObject**>(instance->ptr()) + offset_in_words,
@@ -2362,7 +2361,7 @@
     BYTECODE(StoreStaticTOS, D);
     RawField* field = reinterpret_cast<RawField*>(LOAD_CONSTANT(rD));
     RawInstance* value = static_cast<RawInstance*>(*SP--);
-    intptr_t field_id = field->ptr()->offset_or_field_id_;
+    intptr_t field_id = field->ptr()->host_offset_or_field_id_;
     thread->field_table_values()[field_id] = value;
     DISPATCH();
   }
@@ -2370,7 +2369,7 @@
   {
     BYTECODE(LoadStatic, D);
     RawField* field = reinterpret_cast<RawField*>(LOAD_CONSTANT(rD));
-    intptr_t field_id = field->ptr()->offset_or_field_id_;
+    intptr_t field_id = field->ptr()->host_offset_or_field_id_;
     RawInstance* value = thread->field_table_values()[field_id];
     ASSERT((value != Object::sentinel().raw()) &&
            (value != Object::transition_sentinel().raw()));
@@ -2383,7 +2382,7 @@
     RawField* field = RAW_CAST(Field, LOAD_CONSTANT(rD + 1));
     RawInstance* instance = reinterpret_cast<RawInstance*>(SP[-1]);
     RawObject* value = reinterpret_cast<RawObject*>(SP[0]);
-    intptr_t offset_in_words = field->ptr()->offset_or_field_id_;
+    intptr_t offset_in_words = field->ptr()->host_offset_or_field_id_;
 
     if (InterpreterHelpers::FieldNeedsGuardUpdate(field, value)) {
       SP[1] = 0;  // Unused result of runtime call.
@@ -2558,7 +2557,7 @@
     RawClass* cls = Class::RawCast(LOAD_CONSTANT(rD));
     if (LIKELY(InterpreterHelpers::IsFinalized(cls))) {
       const intptr_t class_id = cls->ptr()->id_;
-      const intptr_t instance_size = cls->ptr()->instance_size_in_words_
+      const intptr_t instance_size = cls->ptr()->host_instance_size_in_words_
                                      << kWordSizeLog2;
       RawObject* result;
       if (TryAllocate(thread, class_id, instance_size, &result)) {
@@ -2588,7 +2587,7 @@
     RawTypeArguments* type_args = TypeArguments::RawCast(SP[-1]);
     if (LIKELY(InterpreterHelpers::IsFinalized(cls))) {
       const intptr_t class_id = cls->ptr()->id_;
-      const intptr_t instance_size = cls->ptr()->instance_size_in_words_
+      const intptr_t instance_size = cls->ptr()->host_instance_size_in_words_
                                      << kWordSizeLog2;
       RawObject* result;
       if (TryAllocate(thread, class_id, instance_size, &result)) {
@@ -2598,7 +2597,8 @@
           *reinterpret_cast<RawObject**>(start + offset) = null_value;
         }
         const intptr_t type_args_offset =
-            cls->ptr()->type_arguments_field_offset_in_words_ << kWordSizeLog2;
+            cls->ptr()->host_type_arguments_field_offset_in_words_
+            << kWordSizeLog2;
         *reinterpret_cast<RawObject**>(start + type_args_offset) = type_args;
         *--SP = result;
         DISPATCH();
@@ -3168,7 +3168,7 @@
 
     // Field object is cached in function's data_.
     RawField* field = reinterpret_cast<RawField*>(function->ptr()->data_);
-    intptr_t offset_in_words = field->ptr()->offset_or_field_id_;
+    intptr_t offset_in_words = field->ptr()->host_offset_or_field_id_;
 
     const intptr_t kArgc = 1;
     RawInstance* instance =
@@ -3188,7 +3188,7 @@
       function = FrameFunction(FP);
       instance = reinterpret_cast<RawInstance*>(SP[2]);
       field = reinterpret_cast<RawField*>(SP[3]);
-      offset_in_words = field->ptr()->offset_or_field_id_;
+      offset_in_words = field->ptr()->host_offset_or_field_id_;
       value = reinterpret_cast<RawInstance**>(instance->ptr())[offset_in_words];
     }
 
@@ -3249,7 +3249,7 @@
 
     // Field object is cached in function's data_.
     RawField* field = reinterpret_cast<RawField*>(function->ptr()->data_);
-    intptr_t offset_in_words = field->ptr()->offset_or_field_id_;
+    intptr_t offset_in_words = field->ptr()->host_offset_or_field_id_;
     const intptr_t kArgc = 2;
     RawInstance* instance =
         reinterpret_cast<RawInstance*>(FrameArguments(FP, kArgc)[0]);
@@ -3329,7 +3329,7 @@
 
     // Field object is cached in function's data_.
     RawField* field = reinterpret_cast<RawField*>(function->ptr()->data_);
-    intptr_t field_id = field->ptr()->offset_or_field_id_;
+    intptr_t field_id = field->ptr()->host_offset_or_field_id_;
     RawInstance* value = thread->field_table_values()[field_id];
     if (value == Object::sentinel().raw() ||
         value == Object::transition_sentinel().raw()) {
@@ -3343,7 +3343,7 @@
       function = FrameFunction(FP);
       field = reinterpret_cast<RawField*>(function->ptr()->data_);
       // The field is initialized by the runtime call, but not returned.
-      intptr_t field_id = field->ptr()->offset_or_field_id_;
+      intptr_t field_id = field->ptr()->host_offset_or_field_id_;
       value = thread->field_table_values()[field_id];
     }
 
diff --git a/runtime/vm/isolate_reload.cc b/runtime/vm/isolate_reload.cc
index 6b7d268..4616efa 100644
--- a/runtime/vm/isolate_reload.cc
+++ b/runtime/vm/isolate_reload.cc
@@ -110,9 +110,9 @@
 
   if (from.NumTypeArguments() > 0) {
     // Add copying of the optional type argument field.
-    intptr_t from_offset = from.type_arguments_field_offset();
+    intptr_t from_offset = from.host_type_arguments_field_offset();
     ASSERT(from_offset != Class::kNoTypeArguments);
-    intptr_t to_offset = to.type_arguments_field_offset();
+    intptr_t to_offset = to.host_type_arguments_field_offset();
     ASSERT(to_offset != Class::kNoTypeArguments);
     mapping->Add(from_offset);
     mapping->Add(to_offset);
@@ -152,8 +152,8 @@
       from_name = from_field.name();
       if (from_name.Equals(to_name)) {
         // Success
-        mapping->Add(from_field.Offset());
-        mapping->Add(to_field.Offset());
+        mapping->Add(from_field.HostOffset());
+        mapping->Add(to_field.HostOffset());
         // Field did exist in old class deifnition.
         new_field = false;
       }
@@ -163,7 +163,7 @@
       const Field& field = Field::Handle(to_field.raw());
       field.set_needs_load_guard(true);
       field.set_is_unboxing_candidate(false);
-      new_fields_offsets->Add(field.Offset());
+      new_fields_offsets->Add(field.HostOffset());
     }
   }
 
@@ -193,9 +193,34 @@
 }
 
 RawInstance* InstanceMorpher::Morph(const Instance& instance) const {
+  // Code can reference constants / canonical objects either directly in the
+  // instruction stream (ia32) or via an object pool.
+  //
+  // We have the following invariants:
+  //
+  //    a) Those canonical objects don't change state (i.e. are not mutable):
+  //       our optimizer can e.g. execute loads of such constants at
+  //       compile-time.
+  //
+  //       => We ensure that const-classes with live constants cannot be
+  //          reloaded to become non-const classes (see Class::CheckReload).
+  //
+  //    b) Those canonical objects live in old space: e.g. on ia32 the scavenger
+  //       does not make the RX pages writable and therefore cannot update
+  //       pointers embedded in the instruction stream.
+  //
+  // In order to maintain these invariants we ensure to always morph canonical
+  // objects to old space.
+  const bool is_canonical = instance.IsCanonical();
+  const Heap::Space space = is_canonical ? Heap::kOld : Heap::kNew;
   const auto& result = Instance::Handle(
-      Z, Instance::NewFromCidAndSize(shared_class_table_, cid_));
+      Z, Instance::NewFromCidAndSize(shared_class_table_, cid_, space));
 
+  // We preserve the canonical bit of the object, since this object is present
+  // in the class's constants.
+  if (is_canonical) {
+    result.SetCanonical();
+  }
 #if defined(HASH_IN_OBJECT_HEADER)
   const uint32_t hash = Object::GetCachedHash(instance.raw());
   Object::SetCachedHash(result.raw(), hash);
@@ -1247,8 +1272,9 @@
       uri = script.url();
       const bool dart_scheme = uri.StartsWith(Symbols::DartScheme());
       if (dart_scheme) {
-        // If a user-defined class mixes in a mixin from dart:*, it's list of scripts will have
-        // a dart:* script as well. We don't consider those during reload.
+        // If a user-defined class mixes in a mixin from dart:*, it's list of
+        // scripts will have a dart:* script as well. We don't consider those
+        // during reload.
         continue;
       }
       if (ContainsScriptUri(modified_sources_uris, uri.ToCString())) {
diff --git a/runtime/vm/isolate_reload_test.cc b/runtime/vm/isolate_reload_test.cc
index b69cee3..ac5ae44 100644
--- a/runtime/vm/isolate_reload_test.cc
+++ b/runtime/vm/isolate_reload_test.cc
@@ -2973,6 +2973,92 @@
   EXPECT_STREQ("true", SimpleInvokeStr(lib, "main"));
 }
 
+TEST_CASE(IsolateReload_ShapeChangeConstReferencedByInstructions) {
+  // On IA32, instructions can contain direct pointers to const objects. We need
+  // to be careful that if the const objects are reallocated because of a shape
+  // change, they are allocated old. Because instructions normally contain
+  // pointers only to old objects, the scavenger does not bother to ensure code
+  // pages are writable when visiting the remembered set. Visiting the
+  // remembered involes writing to update the pointer for any target that gets
+  // promoted.
+  const char* kScript = R"(
+    import 'file:///test:isolate_reload_helper';
+    class A {
+      final x;
+      const A(this.x);
+    }
+    var a;
+    main() {
+      a = const A(1);
+      collectNewSpace();
+      return 'okay';
+    }
+  )";
+
+  Dart_Handle lib = TestCase::LoadTestScript(kScript, NULL);
+  EXPECT_VALID(lib);
+  EXPECT_STREQ("okay", SimpleInvokeStr(lib, "main"));
+
+  // Flip the size back and forth a few times.
+  for (intptr_t i = 0; i < 3; i++) {
+    const char* kReloadScript = R"(
+      import 'file:///test:isolate_reload_helper';
+      class A {
+        final x, y, z;
+        const A(this.x, this.y, this.z);
+      }
+      var a;
+      main() {
+        a = const A(1, null, null);
+        collectNewSpace();
+        return 'okay';
+      }
+    )";
+
+    lib = TestCase::ReloadTestScript(kReloadScript);
+    EXPECT_VALID(lib);
+    EXPECT_STREQ("okay", SimpleInvokeStr(lib, "main"));
+
+    lib = TestCase::ReloadTestScript(kScript);
+    EXPECT_VALID(lib);
+    EXPECT_STREQ("okay", SimpleInvokeStr(lib, "main"));
+  }
+}
+
+TEST_CASE(IsolateReload_ConstToNonConstClass) {
+  const char* kScript = R"(
+    class A {
+      final dynamic x;
+      const A(this.x);
+    }
+    dynamic a;
+    main() {
+      a = const A(1);
+      return 'okay';
+    }
+  )";
+
+  Dart_Handle lib = TestCase::LoadTestScript(kScript, NULL);
+  EXPECT_VALID(lib);
+  EXPECT_STREQ("okay", SimpleInvokeStr(lib, "main"));
+
+  const char* kReloadScript = R"(
+    class A {
+      dynamic x;
+      A(this.x);
+    }
+    dynamic a;
+    main() {
+      a.x = 10;
+    }
+  )";
+
+  lib = TestCase::ReloadTestScript(kReloadScript);
+  EXPECT_ERROR(lib,
+               "Const class cannot become non-const: "
+               "Library:'file:///test-lib' Class: A");
+}
+
 TEST_CASE(IsolateReload_StaticTearOffRetainsHash) {
   const char* kScript =
       "foo() {}\n"
diff --git a/runtime/vm/kernel_binary.h b/runtime/vm/kernel_binary.h
index 2061521..2a68fe5 100644
--- a/runtime/vm/kernel_binary.h
+++ b/runtime/vm/kernel_binary.h
@@ -20,7 +20,7 @@
 
 // Both version numbers are inclusive.
 static const uint32_t kMinSupportedKernelFormatVersion = 29;
-static const uint32_t kMaxSupportedKernelFormatVersion = 37;
+static const uint32_t kMaxSupportedKernelFormatVersion = 38;
 
 // Keep in sync with package:kernel/lib/binary/tag.dart
 #define KERNEL_TAG_LIST(V)                                                     \
diff --git a/runtime/vm/kernel_loader.cc b/runtime/vm/kernel_loader.cc
index 49ef53b..bd81e37 100644
--- a/runtime/vm/kernel_loader.cc
+++ b/runtime/vm/kernel_loader.cc
@@ -8,6 +8,7 @@
 
 #include <memory>
 
+#include "vm/compiler/backend/flow_graph_compiler.h"
 #include "vm/compiler/frontend/constant_reader.h"
 #include "vm/compiler/frontend/kernel_translation_helper.h"
 #include "vm/dart_api_impl.h"
@@ -948,6 +949,17 @@
   field.set_guarded_cid(type.cid);
   field.set_is_nullable(type.IsNullable());
   field.set_guarded_list_length(Field::kNoFixedLength);
+  if (FLAG_precompiled_mode) {
+    field.set_is_unboxing_candidate(
+        !field.is_late() && !field.is_static() &&
+        ((field.guarded_cid() == kDoubleCid &&
+          FlowGraphCompiler::SupportsUnboxedDoubles()) ||
+         (field.guarded_cid() == kFloat32x4Cid &&
+          FlowGraphCompiler::SupportsUnboxedSimd128()) ||
+         (field.guarded_cid() == kFloat64x2Cid &&
+          FlowGraphCompiler::SupportsUnboxedSimd128())) &&
+        !field.is_nullable());
+  }
 }
 
 void KernelLoader::CheckForInitializer(const Field& field) {
diff --git a/runtime/vm/lockers.h b/runtime/vm/lockers.h
index 3e81788..31ea517 100644
--- a/runtime/vm/lockers.h
+++ b/runtime/vm/lockers.h
@@ -8,8 +8,8 @@
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/globals.h"
-#include "vm/isolate.h"
 #include "vm/os_thread.h"
+#include "vm/thread.h"
 
 namespace dart {
 
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 1fb811b..f4e7894 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -693,14 +693,19 @@
     // to lookup class class in the class table where it is not registered yet.
     cls.raw_ = class_class_;
     ASSERT(builtin_vtables_[kClassCid] == fake.vtable());
-    cls.set_instance_size(Class::InstanceSize());
-    cls.set_next_field_offset(Class::NextFieldOffset());
+    cls.set_instance_size(
+        Class::InstanceSize(),
+        compiler::target::RoundedAllocationSize(RTN::Class::InstanceSize()));
+    const intptr_t host_next_field_offset = Class::NextFieldOffset();
+    const intptr_t target_next_field_offset = RTN::Class::NextFieldOffset();
+    cls.set_next_field_offset(host_next_field_offset, target_next_field_offset);
     cls.set_id(Class::kClassId);
     cls.set_state_bits(0);
     cls.set_is_finalized();
     cls.set_is_declaration_loaded();
     cls.set_is_type_finalized();
-    cls.set_type_arguments_field_offset_in_words(Class::kNoTypeArguments);
+    cls.set_type_arguments_field_offset_in_words(Class::kNoTypeArguments,
+                                                 RTN::Class::kNoTypeArguments);
     cls.set_num_type_arguments(0);
     cls.set_num_native_fields(0);
     cls.InitEmptyFields();
@@ -708,19 +713,23 @@
   }
 
   // Allocate and initialize the null class.
-  cls = Class::New<Instance>(kNullCid, isolate);
+  cls = Class::New<Instance, RTN::Instance>(kNullCid, isolate);
   cls.set_num_type_arguments(0);
   isolate->object_store()->set_null_class(cls);
 
   // Allocate and initialize the free list element class.
-  cls = Class::New<FreeListElement::FakeInstance>(kFreeListElement, isolate);
+  cls =
+      Class::New<FreeListElement::FakeInstance,
+                 RTN::FreeListElement::FakeInstance>(kFreeListElement, isolate);
   cls.set_num_type_arguments(0);
   cls.set_is_finalized();
   cls.set_is_declaration_loaded();
   cls.set_is_type_finalized();
 
   // Allocate and initialize the forwarding corpse class.
-  cls = Class::New<ForwardingCorpse::FakeInstance>(kForwardingCorpse, isolate);
+  cls = Class::New<ForwardingCorpse::FakeInstance,
+                   RTN::ForwardingCorpse::FakeInstance>(kForwardingCorpse,
+                                                        isolate);
   cls.set_num_type_arguments(0);
   cls.set_is_finalized();
   cls.set_is_declaration_loaded();
@@ -744,132 +753,136 @@
   }
 
   // Allocate the remaining VM internal classes.
-  cls = Class::New<TypeArguments>(isolate);
+  cls = Class::New<TypeArguments, RTN::TypeArguments>(isolate);
   type_arguments_class_ = cls.raw();
 
-  cls = Class::New<PatchClass>(isolate);
+  cls = Class::New<PatchClass, RTN::PatchClass>(isolate);
   patch_class_class_ = cls.raw();
 
-  cls = Class::New<Function>(isolate);
+  cls = Class::New<Function, RTN::Function>(isolate);
   function_class_ = cls.raw();
 
-  cls = Class::New<ClosureData>(isolate);
+  cls = Class::New<ClosureData, RTN::ClosureData>(isolate);
   closure_data_class_ = cls.raw();
 
-  cls = Class::New<SignatureData>(isolate);
+  cls = Class::New<SignatureData, RTN::SignatureData>(isolate);
   signature_data_class_ = cls.raw();
 
-  cls = Class::New<RedirectionData>(isolate);
+  cls = Class::New<RedirectionData, RTN::RedirectionData>(isolate);
   redirection_data_class_ = cls.raw();
 
-  cls = Class::New<FfiTrampolineData>(isolate);
+  cls = Class::New<FfiTrampolineData, RTN::FfiTrampolineData>(isolate);
   ffi_trampoline_data_class_ = cls.raw();
 
-  cls = Class::New<Field>(isolate);
+  cls = Class::New<Field, RTN::Field>(isolate);
   field_class_ = cls.raw();
 
-  cls = Class::New<Script>(isolate);
+  cls = Class::New<Script, RTN::Script>(isolate);
   script_class_ = cls.raw();
 
-  cls = Class::New<Library>(isolate);
+  cls = Class::New<Library, RTN::Library>(isolate);
   library_class_ = cls.raw();
 
-  cls = Class::New<Namespace>(isolate);
+  cls = Class::New<Namespace, RTN::Namespace>(isolate);
   namespace_class_ = cls.raw();
 
-  cls = Class::New<KernelProgramInfo>(isolate);
+  cls = Class::New<KernelProgramInfo, RTN::KernelProgramInfo>(isolate);
   kernel_program_info_class_ = cls.raw();
 
-  cls = Class::New<Code>(isolate);
+  cls = Class::New<Code, RTN::Code>(isolate);
   code_class_ = cls.raw();
 
-  cls = Class::New<Bytecode>(isolate);
+  cls = Class::New<Bytecode, RTN::Bytecode>(isolate);
   bytecode_class_ = cls.raw();
 
-  cls = Class::New<Instructions>(isolate);
+  cls = Class::New<Instructions, RTN::Instructions>(isolate);
   instructions_class_ = cls.raw();
 
-  cls = Class::New<ObjectPool>(isolate);
+  cls = Class::New<ObjectPool, RTN::ObjectPool>(isolate);
   object_pool_class_ = cls.raw();
 
-  cls = Class::New<PcDescriptors>(isolate);
+  cls = Class::New<PcDescriptors, RTN::PcDescriptors>(isolate);
   pc_descriptors_class_ = cls.raw();
 
-  cls = Class::New<CodeSourceMap>(isolate);
+  cls = Class::New<CodeSourceMap, RTN::CodeSourceMap>(isolate);
   code_source_map_class_ = cls.raw();
 
-  cls = Class::New<CompressedStackMaps>(isolate);
+  cls = Class::New<CompressedStackMaps, RTN::CompressedStackMaps>(isolate);
   compressed_stackmaps_class_ = cls.raw();
 
-  cls = Class::New<LocalVarDescriptors>(isolate);
+  cls = Class::New<LocalVarDescriptors, RTN::LocalVarDescriptors>(isolate);
   var_descriptors_class_ = cls.raw();
 
-  cls = Class::New<ExceptionHandlers>(isolate);
+  cls = Class::New<ExceptionHandlers, RTN::ExceptionHandlers>(isolate);
   exception_handlers_class_ = cls.raw();
 
-  cls = Class::New<Context>(isolate);
+  cls = Class::New<Context, RTN::Context>(isolate);
   context_class_ = cls.raw();
 
-  cls = Class::New<ContextScope>(isolate);
+  cls = Class::New<ContextScope, RTN::ContextScope>(isolate);
   context_scope_class_ = cls.raw();
 
-  cls = Class::New<ParameterTypeCheck>(isolate);
+  cls = Class::New<ParameterTypeCheck, RTN::ParameterTypeCheck>(isolate);
   dyncalltypecheck_class_ = cls.raw();
 
-  cls = Class::New<SingleTargetCache>(isolate);
+  cls = Class::New<SingleTargetCache, RTN::SingleTargetCache>(isolate);
   singletargetcache_class_ = cls.raw();
 
-  cls = Class::New<UnlinkedCall>(isolate);
+  cls = Class::New<UnlinkedCall, RTN::UnlinkedCall>(isolate);
   unlinkedcall_class_ = cls.raw();
 
-  cls = Class::New<MonomorphicSmiableCall>(isolate);
+  cls =
+      Class::New<MonomorphicSmiableCall, RTN::MonomorphicSmiableCall>(isolate);
   monomorphicsmiablecall_class_ = cls.raw();
 
-  cls = Class::New<ICData>(isolate);
+  cls = Class::New<ICData, RTN::ICData>(isolate);
   icdata_class_ = cls.raw();
 
-  cls = Class::New<MegamorphicCache>(isolate);
+  cls = Class::New<MegamorphicCache, RTN::MegamorphicCache>(isolate);
   megamorphic_cache_class_ = cls.raw();
 
-  cls = Class::New<SubtypeTestCache>(isolate);
+  cls = Class::New<SubtypeTestCache, RTN::SubtypeTestCache>(isolate);
   subtypetestcache_class_ = cls.raw();
 
-  cls = Class::New<ApiError>(isolate);
+  cls = Class::New<ApiError, RTN::ApiError>(isolate);
   api_error_class_ = cls.raw();
 
-  cls = Class::New<LanguageError>(isolate);
+  cls = Class::New<LanguageError, RTN::LanguageError>(isolate);
   language_error_class_ = cls.raw();
 
-  cls = Class::New<UnhandledException>(isolate);
+  cls = Class::New<UnhandledException, RTN::UnhandledException>(isolate);
   unhandled_exception_class_ = cls.raw();
 
-  cls = Class::New<UnwindError>(isolate);
+  cls = Class::New<UnwindError, RTN::UnwindError>(isolate);
   unwind_error_class_ = cls.raw();
 
   ASSERT(class_class() != null_);
 
   // Pre-allocate classes in the vm isolate so that we can for example create a
   // symbol table and populate it with some frequently used strings as symbols.
-  cls = Class::New<Array>(isolate);
+  cls = Class::New<Array, RTN::Array>(isolate);
   isolate->object_store()->set_array_class(cls);
-  cls.set_type_arguments_field_offset(Array::type_arguments_offset());
+  cls.set_type_arguments_field_offset(Array::type_arguments_offset(),
+                                      RTN::Array::type_arguments_offset());
   cls.set_num_type_arguments(1);
-  cls = Class::New<Array>(kImmutableArrayCid, isolate);
+  cls = Class::New<Array, RTN::Array>(kImmutableArrayCid, isolate);
   isolate->object_store()->set_immutable_array_class(cls);
-  cls.set_type_arguments_field_offset(Array::type_arguments_offset());
+  cls.set_type_arguments_field_offset(Array::type_arguments_offset(),
+                                      RTN::Array::type_arguments_offset());
   cls.set_num_type_arguments(1);
-  cls = Class::New<GrowableObjectArray>(isolate);
+  cls = Class::New<GrowableObjectArray, RTN::GrowableObjectArray>(isolate);
   isolate->object_store()->set_growable_object_array_class(cls);
   cls.set_type_arguments_field_offset(
-      GrowableObjectArray::type_arguments_offset());
+      GrowableObjectArray::type_arguments_offset(),
+      RTN::GrowableObjectArray::type_arguments_offset());
   cls.set_num_type_arguments(1);
   cls = Class::NewStringClass(kOneByteStringCid, isolate);
   isolate->object_store()->set_one_byte_string_class(cls);
   cls = Class::NewStringClass(kTwoByteStringCid, isolate);
   isolate->object_store()->set_two_byte_string_class(cls);
-  cls = Class::New<Mint>(isolate);
+  cls = Class::New<Mint, RTN::Mint>(isolate);
   isolate->object_store()->set_mint_class(cls);
-  cls = Class::New<Double>(isolate);
+  cls = Class::New<Double, RTN::Double>(isolate);
   isolate->object_store()->set_double_class(cls);
 
   // Ensure that class kExternalTypedDataUint8ArrayCid is registered as we
@@ -991,7 +1004,7 @@
   // as we do not have any VM isolate snapshot at this time.
   *vm_isolate_snapshot_object_table_ = Object::empty_array().raw();
 
-  cls = Class::New<Instance>(kDynamicCid, isolate);
+  cls = Class::New<Instance, RTN::Instance>(kDynamicCid, isolate);
   cls.set_is_abstract();
   cls.set_num_type_arguments(0);
   cls.set_is_finalized();
@@ -999,21 +1012,21 @@
   cls.set_is_type_finalized();
   dynamic_class_ = cls.raw();
 
-  cls = Class::New<Instance>(kVoidCid, isolate);
+  cls = Class::New<Instance, RTN::Instance>(kVoidCid, isolate);
   cls.set_num_type_arguments(0);
   cls.set_is_finalized();
   cls.set_is_declaration_loaded();
   cls.set_is_type_finalized();
   void_class_ = cls.raw();
 
-  cls = Class::New<Instance>(kNeverCid, isolate);
+  cls = Class::New<Instance, RTN::Instance>(kNeverCid, isolate);
   cls.set_num_type_arguments(0);
   cls.set_is_finalized();
   cls.set_is_declaration_loaded();
   cls.set_is_type_finalized();
   never_class_ = cls.raw();
 
-  cls = Class::New<Type>(isolate);
+  cls = Class::New<Type, RTN::Type>(isolate);
   cls.set_is_finalized();
   cls.set_is_declaration_loaded();
   cls.set_is_type_finalized();
@@ -1045,7 +1058,7 @@
   cls.SetFunctions(Object::empty_array());
 
   // Allocate and initialize singleton true and false boolean objects.
-  cls = Class::New<Bool>(isolate);
+  cls = Class::New<Bool, RTN::Bool>(isolate);
   isolate->object_store()->set_bool_class(cls);
   *bool_true_ = Bool::New(true);
   *bool_false_ = Bool::New(false);
@@ -1571,7 +1584,7 @@
 
     // All RawArray fields will be initialized to an empty array, therefore
     // initialize array class first.
-    cls = Class::New<Array>(isolate);
+    cls = Class::New<Array, RTN::Array>(isolate);
     object_store->set_array_class(cls);
 
     // VM classes that are parameterized (Array, ImmutableArray,
@@ -1579,15 +1592,17 @@
     // CalculateFieldOffsets() is not called, so we need to set the offset of
     // their type_arguments_ field, which is explicitly declared in their
     // respective Raw* classes.
-    cls.set_type_arguments_field_offset(Array::type_arguments_offset());
+    cls.set_type_arguments_field_offset(Array::type_arguments_offset(),
+                                        RTN::Array::type_arguments_offset());
     cls.set_num_type_arguments(1);
 
     // Set up the growable object array class (Has to be done after the array
     // class is setup as one of its field is an array object).
-    cls = Class::New<GrowableObjectArray>(isolate);
+    cls = Class::New<GrowableObjectArray, RTN::GrowableObjectArray>(isolate);
     object_store->set_growable_object_array_class(cls);
     cls.set_type_arguments_field_offset(
-        GrowableObjectArray::type_arguments_offset());
+        GrowableObjectArray::type_arguments_offset(),
+        RTN::GrowableObjectArray::type_arguments_offset());
     cls.set_num_type_arguments(1);
 
     // Initialize hash set for canonical types.
@@ -1603,13 +1618,14 @@
     object_store->set_canonical_type_arguments(array);
 
     // Setup type class early in the process.
-    const Class& type_cls = Class::Handle(zone, Class::New<Type>(isolate));
+    const Class& type_cls =
+        Class::Handle(zone, Class::New<Type, RTN::Type>(isolate));
     const Class& type_ref_cls =
-        Class::Handle(zone, Class::New<TypeRef>(isolate));
-    const Class& type_parameter_cls =
-        Class::Handle(zone, Class::New<TypeParameter>(isolate));
-    const Class& library_prefix_cls =
-        Class::Handle(zone, Class::New<LibraryPrefix>(isolate));
+        Class::Handle(zone, Class::New<TypeRef, RTN::TypeRef>(isolate));
+    const Class& type_parameter_cls = Class::Handle(
+        zone, Class::New<TypeParameter, RTN::TypeParameter>(isolate));
+    const Class& library_prefix_cls = Class::Handle(
+        zone, Class::New<LibraryPrefix, RTN::LibraryPrefix>(isolate));
 
     // Pre-allocate the OneByteString class needed by the symbol table.
     cls = Class::NewStringClass(kOneByteStringCid, isolate);
@@ -1666,9 +1682,10 @@
     RegisterPrivateClass(cls, Symbols::_GrowableList(), core_lib);
     pending_classes.Add(cls);
 
-    cls = Class::New<Array>(kImmutableArrayCid, isolate);
+    cls = Class::New<Array, RTN::Array>(kImmutableArrayCid, isolate);
     object_store->set_immutable_array_class(cls);
-    cls.set_type_arguments_field_offset(Array::type_arguments_offset());
+    cls.set_type_arguments_field_offset(Array::type_arguments_offset(),
+                                        RTN::Array::type_arguments_offset());
     cls.set_num_type_arguments(1);
     ASSERT(object_store->immutable_array_class() !=
            object_store->array_class());
@@ -1707,30 +1724,31 @@
     ASSERT(!isolate_lib.IsNull());
     ASSERT(isolate_lib.raw() == Library::IsolateLibrary());
 
-    cls = Class::New<Capability>(isolate);
+    cls = Class::New<Capability, RTN::Capability>(isolate);
     RegisterPrivateClass(cls, Symbols::_CapabilityImpl(), isolate_lib);
     pending_classes.Add(cls);
 
-    cls = Class::New<ReceivePort>(isolate);
+    cls = Class::New<ReceivePort, RTN::ReceivePort>(isolate);
     RegisterPrivateClass(cls, Symbols::_RawReceivePortImpl(), isolate_lib);
     pending_classes.Add(cls);
 
-    cls = Class::New<SendPort>(isolate);
+    cls = Class::New<SendPort, RTN::SendPort>(isolate);
     RegisterPrivateClass(cls, Symbols::_SendPortImpl(), isolate_lib);
     pending_classes.Add(cls);
 
-    cls = Class::New<TransferableTypedData>(isolate);
+    cls =
+        Class::New<TransferableTypedData, RTN::TransferableTypedData>(isolate);
     RegisterPrivateClass(cls, Symbols::_TransferableTypedDataImpl(),
                          isolate_lib);
     pending_classes.Add(cls);
 
     const Class& stacktrace_cls =
-        Class::Handle(zone, Class::New<StackTrace>(isolate));
+        Class::Handle(zone, Class::New<StackTrace, RTN::StackTrace>(isolate));
     RegisterPrivateClass(stacktrace_cls, Symbols::_StackTrace(), core_lib);
     pending_classes.Add(stacktrace_cls);
     // Super type set below, after Object is allocated.
 
-    cls = Class::New<RegExp>(isolate);
+    cls = Class::New<RegExp, RTN::RegExp>(isolate);
     RegisterPrivateClass(cls, Symbols::_RegExp(), core_lib);
     pending_classes.Add(cls);
 
@@ -1740,11 +1758,12 @@
     // The script and token index of these pre-allocated classes is set up in
     // the parser when the corelib script is compiled (see
     // Parser::ParseClassDefinition).
-    cls = Class::New<Instance>(kInstanceCid, isolate);
+    cls = Class::New<Instance, RTN::Instance>(kInstanceCid, isolate);
     object_store->set_object_class(cls);
     cls.set_name(Symbols::Object());
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
+    cls.set_is_const();
     core_lib.AddClass(cls);
     pending_classes.Add(cls);
     type = Type::NewNonParameterizedType(cls);
@@ -1754,12 +1773,12 @@
     type = type.ToNullability(Nullability::kNonNullable, Heap::kOld);
     object_store->set_non_nullable_object_type(type);
 
-    cls = Class::New<Bool>(isolate);
+    cls = Class::New<Bool, RTN::Bool>(isolate);
     object_store->set_bool_class(cls);
     RegisterClass(cls, Symbols::Bool(), core_lib);
     pending_classes.Add(cls);
 
-    cls = Class::New<Instance>(kNullCid, isolate);
+    cls = Class::New<Instance, RTN::Instance>(kNullCid, isolate);
     object_store->set_null_class(cls);
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
@@ -1781,33 +1800,33 @@
                          core_lib);
     pending_classes.Add(type_parameter_cls);
 
-    cls = Class::New<Integer>(isolate);
+    cls = Class::New<Integer, RTN::Integer>(isolate);
     object_store->set_integer_implementation_class(cls);
     RegisterPrivateClass(cls, Symbols::_IntegerImplementation(), core_lib);
     pending_classes.Add(cls);
 
-    cls = Class::New<Smi>(isolate);
+    cls = Class::New<Smi, RTN::Smi>(isolate);
     object_store->set_smi_class(cls);
     RegisterPrivateClass(cls, Symbols::_Smi(), core_lib);
     pending_classes.Add(cls);
 
-    cls = Class::New<Mint>(isolate);
+    cls = Class::New<Mint, RTN::Mint>(isolate);
     object_store->set_mint_class(cls);
     RegisterPrivateClass(cls, Symbols::_Mint(), core_lib);
     pending_classes.Add(cls);
 
-    cls = Class::New<Double>(isolate);
+    cls = Class::New<Double, RTN::Double>(isolate);
     object_store->set_double_class(cls);
     RegisterPrivateClass(cls, Symbols::_Double(), core_lib);
     pending_classes.Add(cls);
 
     // Class that represents the Dart class _Closure and C++ class Closure.
-    cls = Class::New<Closure>(isolate);
+    cls = Class::New<Closure, RTN::Closure>(isolate);
     object_store->set_closure_class(cls);
     RegisterPrivateClass(cls, Symbols::_Closure(), core_lib);
     pending_classes.Add(cls);
 
-    cls = Class::New<WeakProperty>(isolate);
+    cls = Class::New<WeakProperty, RTN::WeakProperty>(isolate);
     object_store->set_weak_property_class(cls);
     RegisterPrivateClass(cls, Symbols::_WeakProperty(), core_lib);
 
@@ -1824,7 +1843,7 @@
     ASSERT(!lib.IsNull());
     ASSERT(lib.raw() == Library::MirrorsLibrary());
 
-    cls = Class::New<MirrorReference>(isolate);
+    cls = Class::New<MirrorReference, RTN::MirrorReference>(isolate);
     RegisterPrivateClass(cls, Symbols::_MirrorReference(), lib);
 #endif
 
@@ -1840,9 +1859,11 @@
     object_store->set_bootstrap_library(ObjectStore::kCollection, lib);
     ASSERT(!lib.IsNull());
     ASSERT(lib.raw() == Library::CollectionLibrary());
-    cls = Class::New<LinkedHashMap>(isolate);
+    cls = Class::New<LinkedHashMap, RTN::LinkedHashMap>(isolate);
     object_store->set_linked_hash_map_class(cls);
-    cls.set_type_arguments_field_offset(LinkedHashMap::type_arguments_offset());
+    cls.set_type_arguments_field_offset(
+        LinkedHashMap::type_arguments_offset(),
+        RTN::LinkedHashMap::type_arguments_offset());
     cls.set_num_type_arguments(2);
     RegisterPrivateClass(cls, Symbols::_LinkedHashMap(), lib);
     pending_classes.Add(cls);
@@ -1858,7 +1879,7 @@
     object_store->set_bootstrap_library(ObjectStore::kDeveloper, lib);
     ASSERT(!lib.IsNull());
     ASSERT(lib.raw() == Library::DeveloperLibrary());
-    cls = Class::New<UserTag>(isolate);
+    cls = Class::New<UserTag, RTN::UserTag>(isolate);
     RegisterPrivateClass(cls, Symbols::_UserTag(), lib);
     pending_classes.Add(cls);
 
@@ -1901,10 +1922,10 @@
                                          isolate);                             \
   RegisterPrivateClass(cls, Symbols::_External##clazz(), lib);
 
-    cls =
-        Class::New<Instance>(kByteBufferCid, isolate, /*register_class=*/false);
-    cls.set_instance_size(0);
-    cls.set_next_field_offset(-kWordSize);
+    cls = Class::New<Instance, RTN::Instance>(kByteBufferCid, isolate,
+                                              /*register_class=*/false);
+    cls.set_instance_size(0, 0);
+    cls.set_next_field_offset(-kWordSize, -compiler::target::kWordSize);
     isolate->RegisterClass(cls);
     RegisterPrivateClass(cls, Symbols::_ByteBuffer(), lib);
     pending_classes.Add(cls);
@@ -1912,39 +1933,42 @@
     CLASS_LIST_TYPED_DATA(REGISTER_EXT_TYPED_DATA_CLASS);
 #undef REGISTER_EXT_TYPED_DATA_CLASS
     // Register Float32x4, Int32x4, and Float64x2 in the object store.
-    cls = Class::New<Float32x4>(isolate);
+    cls = Class::New<Float32x4, RTN::Float32x4>(isolate);
     RegisterPrivateClass(cls, Symbols::_Float32x4(), lib);
     pending_classes.Add(cls);
     object_store->set_float32x4_class(cls);
 
-    cls = Class::New<Instance>(kIllegalCid, isolate, /*register_class=*/true,
-                               /*is_abstract=*/true);
+    cls = Class::New<Instance, RTN::Instance>(kIllegalCid, isolate,
+                                              /*register_class=*/true,
+                                              /*is_abstract=*/true);
     RegisterClass(cls, Symbols::Float32x4(), lib);
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
     type = Type::NewNonParameterizedType(cls);
     object_store->set_float32x4_type(type);
 
-    cls = Class::New<Int32x4>(isolate);
+    cls = Class::New<Int32x4, RTN::Int32x4>(isolate);
     RegisterPrivateClass(cls, Symbols::_Int32x4(), lib);
     pending_classes.Add(cls);
     object_store->set_int32x4_class(cls);
 
-    cls = Class::New<Instance>(kIllegalCid, isolate, /*register_class=*/true,
-                               /*is_abstract=*/true);
+    cls = Class::New<Instance, RTN::Instance>(kIllegalCid, isolate,
+                                              /*register_class=*/true,
+                                              /*is_abstract=*/true);
     RegisterClass(cls, Symbols::Int32x4(), lib);
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
     type = Type::NewNonParameterizedType(cls);
     object_store->set_int32x4_type(type);
 
-    cls = Class::New<Float64x2>(isolate);
+    cls = Class::New<Float64x2, RTN::Float64x2>(isolate);
     RegisterPrivateClass(cls, Symbols::_Float64x2(), lib);
     pending_classes.Add(cls);
     object_store->set_float64x2_class(cls);
 
-    cls = Class::New<Instance>(kIllegalCid, isolate, /*register_class=*/true,
-                               /*is_abstract=*/true);
+    cls = Class::New<Instance, RTN::Instance>(kIllegalCid, isolate,
+                                              /*register_class=*/true,
+                                              /*is_abstract=*/true);
     RegisterClass(cls, Symbols::Float64x2(), lib);
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
@@ -1958,8 +1982,9 @@
 
     // Abstract class that represents the Dart class Type.
     // Note that this class is implemented by Dart class _AbstractType.
-    cls = Class::New<Instance>(kIllegalCid, isolate, /*register_class=*/true,
-                               /*is_abstract=*/true);
+    cls = Class::New<Instance, RTN::Instance>(kIllegalCid, isolate,
+                                              /*register_class=*/true,
+                                              /*is_abstract=*/true);
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
     RegisterClass(cls, Symbols::Type(), core_lib);
@@ -1968,8 +1993,9 @@
     object_store->set_type_type(type);
 
     // Abstract class that represents the Dart class Function.
-    cls = Class::New<Instance>(kIllegalCid, isolate, /*register_class=*/true,
-                               /*is_abstract=*/true);
+    cls = Class::New<Instance, RTN::Instance>(kIllegalCid, isolate,
+                                              /*register_class=*/true,
+                                              /*is_abstract=*/true);
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
     RegisterClass(cls, Symbols::Function(), core_lib);
@@ -1981,7 +2007,7 @@
     type = type.ToNullability(Nullability::kNonNullable, Heap::kOld);
     object_store->set_non_nullable_function_type(type);
 
-    cls = Class::New<Number>(isolate);
+    cls = Class::New<Number, RTN::Number>(isolate);
     RegisterClass(cls, Symbols::Number(), core_lib);
     pending_classes.Add(cls);
     type = Type::NewNonParameterizedType(cls);
@@ -1991,8 +2017,9 @@
     type = type.ToNullability(Nullability::kNonNullable, Heap::kOld);
     object_store->set_non_nullable_number_type(type);
 
-    cls = Class::New<Instance>(kIllegalCid, isolate, /*register_class=*/true,
-                               /*is_abstract=*/true);
+    cls = Class::New<Instance, RTN::Instance>(kIllegalCid, isolate,
+                                              /*register_class=*/true,
+                                              /*is_abstract=*/true);
     RegisterClass(cls, Symbols::Int(), core_lib);
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
@@ -2004,8 +2031,9 @@
     type = type.ToNullability(Nullability::kNonNullable, Heap::kOld);
     object_store->set_non_nullable_int_type(type);
 
-    cls = Class::New<Instance>(kIllegalCid, isolate, /*register_class=*/true,
-                               /*is_abstract=*/true);
+    cls = Class::New<Instance, RTN::Instance>(kIllegalCid, isolate,
+                                              /*register_class=*/true,
+                                              /*is_abstract=*/true);
     RegisterClass(cls, Symbols::Double(), core_lib);
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
@@ -2018,8 +2046,9 @@
     object_store->set_non_nullable_double_type(type);
 
     name = Symbols::_String().raw();
-    cls = Class::New<Instance>(kIllegalCid, isolate, /*register_class=*/true,
-                               /*is_abstract=*/true);
+    cls = Class::New<Instance, RTN::Instance>(kIllegalCid, isolate,
+                                              /*register_class=*/true,
+                                              /*is_abstract=*/true);
     RegisterClass(cls, name, core_lib);
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
@@ -2170,7 +2199,7 @@
     }
     object_store->set_bootstrap_library(ObjectStore::kFfi, lib);
 
-    cls = Class::New<Instance>(kFfiNativeTypeCid, isolate);
+    cls = Class::New<Instance, RTN::Instance>(kFfiNativeTypeCid, isolate);
     cls.set_num_type_arguments(0);
     cls.set_is_prefinalized();
     pending_classes.Add(cls);
@@ -2178,7 +2207,7 @@
     RegisterClass(cls, Symbols::FfiNativeType(), lib);
 
 #define REGISTER_FFI_TYPE_MARKER(clazz)                                        \
-  cls = Class::New<Instance>(kFfi##clazz##Cid, isolate);                       \
+  cls = Class::New<Instance, RTN::Instance>(kFfi##clazz##Cid, isolate);        \
   cls.set_num_type_arguments(0);                                               \
   cls.set_is_prefinalized();                                                   \
   pending_classes.Add(cls);                                                    \
@@ -2186,8 +2215,9 @@
     CLASS_LIST_FFI_TYPE_MARKER(REGISTER_FFI_TYPE_MARKER);
 #undef REGISTER_FFI_TYPE_MARKER
 
-    cls = Class::New<Instance>(kFfiNativeFunctionCid, isolate);
-    cls.set_type_arguments_field_offset(Pointer::type_arguments_offset());
+    cls = Class::New<Instance, RTN::Instance>(kFfiNativeFunctionCid, isolate);
+    cls.set_type_arguments_field_offset(Pointer::type_arguments_offset(),
+                                        RTN::Pointer::type_arguments_offset());
     cls.set_num_type_arguments(1);
     cls.set_is_prefinalized();
     pending_classes.Add(cls);
@@ -2198,8 +2228,11 @@
     pending_classes.Add(cls);
     RegisterClass(cls, Symbols::FfiPointer(), lib);
 
-    cls = Class::New<DynamicLibrary>(kFfiDynamicLibraryCid, isolate);
-    cls.set_instance_size(DynamicLibrary::InstanceSize());
+    cls = Class::New<DynamicLibrary, RTN::DynamicLibrary>(kFfiDynamicLibraryCid,
+                                                          isolate);
+    cls.set_instance_size(DynamicLibrary::InstanceSize(),
+                          compiler::target::RoundedAllocationSize(
+                              RTN::DynamicLibrary::InstanceSize()));
     cls.set_is_prefinalized();
     pending_classes.Add(cls);
     RegisterClass(cls, Symbols::FfiDynamicLibrary(), lib);
@@ -2213,7 +2246,7 @@
     object_store->set_bootstrap_library(ObjectStore::kWasm, lib);
 
 #define REGISTER_WASM_TYPE(clazz)                                              \
-  cls = Class::New<Instance>(k##clazz##Cid, isolate);                          \
+  cls = Class::New<Instance, RTN::Instance>(k##clazz##Cid, isolate);           \
   cls.set_num_type_arguments(0);                                               \
   cls.set_is_prefinalized();                                                   \
   pending_classes.Add(cls);                                                    \
@@ -2263,33 +2296,33 @@
     // stored in the object store. Yet we still need to create their Class
     // object so that they get put into the class_table (as a side effect of
     // Class::New()).
-    cls = Class::New<Instance>(kInstanceCid, isolate);
+    cls = Class::New<Instance, RTN::Instance>(kInstanceCid, isolate);
     object_store->set_object_class(cls);
 
-    cls = Class::New<LibraryPrefix>(isolate);
-    cls = Class::New<Type>(isolate);
-    cls = Class::New<TypeRef>(isolate);
-    cls = Class::New<TypeParameter>(isolate);
+    cls = Class::New<LibraryPrefix, RTN::LibraryPrefix>(isolate);
+    cls = Class::New<Type, RTN::Type>(isolate);
+    cls = Class::New<TypeRef, RTN::TypeRef>(isolate);
+    cls = Class::New<TypeParameter, RTN::TypeParameter>(isolate);
 
-    cls = Class::New<Array>(isolate);
+    cls = Class::New<Array, RTN::Array>(isolate);
     object_store->set_array_class(cls);
 
-    cls = Class::New<Array>(kImmutableArrayCid, isolate);
+    cls = Class::New<Array, RTN::Array>(kImmutableArrayCid, isolate);
     object_store->set_immutable_array_class(cls);
 
-    cls = Class::New<GrowableObjectArray>(isolate);
+    cls = Class::New<GrowableObjectArray, RTN::GrowableObjectArray>(isolate);
     object_store->set_growable_object_array_class(cls);
 
-    cls = Class::New<LinkedHashMap>(isolate);
+    cls = Class::New<LinkedHashMap, RTN::LinkedHashMap>(isolate);
     object_store->set_linked_hash_map_class(cls);
 
-    cls = Class::New<Float32x4>(isolate);
+    cls = Class::New<Float32x4, RTN::Float32x4>(isolate);
     object_store->set_float32x4_class(cls);
 
-    cls = Class::New<Int32x4>(isolate);
+    cls = Class::New<Int32x4, RTN::Int32x4>(isolate);
     object_store->set_int32x4_class(cls);
 
-    cls = Class::New<Float64x2>(isolate);
+    cls = Class::New<Float64x2, RTN::Float64x2>(isolate);
     object_store->set_float64x2_class(cls);
 
 #define REGISTER_TYPED_DATA_CLASS(clazz)                                       \
@@ -2307,44 +2340,45 @@
     CLASS_LIST_TYPED_DATA(REGISTER_EXT_TYPED_DATA_CLASS);
 #undef REGISTER_EXT_TYPED_DATA_CLASS
 
-    cls = Class::New<Instance>(kFfiNativeTypeCid, isolate);
+    cls = Class::New<Instance, RTN::Instance>(kFfiNativeTypeCid, isolate);
     object_store->set_ffi_native_type_class(cls);
 
 #define REGISTER_FFI_CLASS(clazz)                                              \
-  cls = Class::New<Instance>(kFfi##clazz##Cid, isolate);
+  cls = Class::New<Instance, RTN::Instance>(kFfi##clazz##Cid, isolate);
     CLASS_LIST_FFI_TYPE_MARKER(REGISTER_FFI_CLASS);
 #undef REGISTER_FFI_CLASS
 
 #define REGISTER_WASM_CLASS(clazz)                                             \
-  cls = Class::New<Instance>(k##clazz##Cid, isolate);
+  cls = Class::New<Instance, RTN::Instance>(k##clazz##Cid, isolate);
     CLASS_LIST_WASM(REGISTER_WASM_CLASS);
 #undef REGISTER_WASM_CLASS
 
-    cls = Class::New<Instance>(kFfiNativeFunctionCid, isolate);
+    cls = Class::New<Instance, RTN::Instance>(kFfiNativeFunctionCid, isolate);
 
     cls = Class::NewPointerClass(kFfiPointerCid, isolate);
     object_store->set_ffi_pointer_class(cls);
 
-    cls = Class::New<DynamicLibrary>(kFfiDynamicLibraryCid, isolate);
+    cls = Class::New<DynamicLibrary, RTN::DynamicLibrary>(kFfiDynamicLibraryCid,
+                                                          isolate);
 
-    cls = Class::New<Instance>(kByteBufferCid, isolate,
-                               /*register_isolate=*/false);
-    cls.set_instance_size_in_words(0);
+    cls = Class::New<Instance, RTN::Instance>(kByteBufferCid, isolate,
+                                              /*register_isolate=*/false);
+    cls.set_instance_size_in_words(0, 0);
     isolate->RegisterClass(cls);
 
-    cls = Class::New<Integer>(isolate);
+    cls = Class::New<Integer, RTN::Integer>(isolate);
     object_store->set_integer_implementation_class(cls);
 
-    cls = Class::New<Smi>(isolate);
+    cls = Class::New<Smi, RTN::Smi>(isolate);
     object_store->set_smi_class(cls);
 
-    cls = Class::New<Mint>(isolate);
+    cls = Class::New<Mint, RTN::Mint>(isolate);
     object_store->set_mint_class(cls);
 
-    cls = Class::New<Double>(isolate);
+    cls = Class::New<Double, RTN::Double>(isolate);
     object_store->set_double_class(cls);
 
-    cls = Class::New<Closure>(isolate);
+    cls = Class::New<Closure, RTN::Closure>(isolate);
     object_store->set_closure_class(cls);
 
     cls = Class::NewStringClass(kOneByteStringCid, isolate);
@@ -2359,26 +2393,27 @@
     cls = Class::NewStringClass(kExternalTwoByteStringCid, isolate);
     object_store->set_external_two_byte_string_class(cls);
 
-    cls = Class::New<Bool>(isolate);
+    cls = Class::New<Bool, RTN::Bool>(isolate);
     object_store->set_bool_class(cls);
 
-    cls = Class::New<Instance>(kNullCid, isolate);
+    cls = Class::New<Instance, RTN::Instance>(kNullCid, isolate);
     object_store->set_null_class(cls);
 
-    cls = Class::New<Capability>(isolate);
-    cls = Class::New<ReceivePort>(isolate);
-    cls = Class::New<SendPort>(isolate);
-    cls = Class::New<StackTrace>(isolate);
-    cls = Class::New<RegExp>(isolate);
-    cls = Class::New<Number>(isolate);
+    cls = Class::New<Capability, RTN::Capability>(isolate);
+    cls = Class::New<ReceivePort, RTN::ReceivePort>(isolate);
+    cls = Class::New<SendPort, RTN::SendPort>(isolate);
+    cls = Class::New<StackTrace, RTN::StackTrace>(isolate);
+    cls = Class::New<RegExp, RTN::RegExp>(isolate);
+    cls = Class::New<Number, RTN::Number>(isolate);
 
-    cls = Class::New<WeakProperty>(isolate);
+    cls = Class::New<WeakProperty, RTN::WeakProperty>(isolate);
     object_store->set_weak_property_class(cls);
 
-    cls = Class::New<MirrorReference>(isolate);
-    cls = Class::New<UserTag>(isolate);
+    cls = Class::New<MirrorReference, RTN::MirrorReference>(isolate);
+    cls = Class::New<UserTag, RTN::UserTag>(isolate);
 
-    cls = Class::New<TransferableTypedData>(isolate);
+    cls =
+        Class::New<TransferableTypedData, RTN::TransferableTypedData>(isolate);
   }
   return Error::null();
 }
@@ -2647,7 +2682,7 @@
   return ClassFinalizer::FinalizeType(*this, type);
 }
 
-template <class FakeObject>
+template <class FakeObject, class TargetFakeObject>
 RawClass* Class::New(Isolate* isolate, bool register_class) {
   ASSERT(Object::class_class() != Class::null());
   Class& result = Class::Handle();
@@ -2660,9 +2695,15 @@
   Object::VerifyBuiltinVtable<FakeObject>(FakeObject::kClassId);
   result.set_token_pos(TokenPosition::kNoSource);
   result.set_end_token_pos(TokenPosition::kNoSource);
-  result.set_instance_size(FakeObject::InstanceSize());
-  result.set_type_arguments_field_offset_in_words(kNoTypeArguments);
-  result.set_next_field_offset(FakeObject::NextFieldOffset());
+  result.set_instance_size(FakeObject::InstanceSize(),
+                           compiler::target::RoundedAllocationSize(
+                               TargetFakeObject::InstanceSize()));
+  result.set_type_arguments_field_offset_in_words(kNoTypeArguments,
+                                                  RTN::Class::kNoTypeArguments);
+  const intptr_t host_next_field_offset = FakeObject::NextFieldOffset();
+  const intptr_t target_next_field_offset = TargetFakeObject::NextFieldOffset();
+  result.set_next_field_offset(host_next_field_offset,
+                               target_next_field_offset);
   COMPILE_ASSERT((FakeObject::kClassId != kInstanceCid));
   result.set_id(FakeObject::kClassId);
   result.set_num_type_arguments(0);
@@ -2727,7 +2768,7 @@
   Array& array = Array::Handle(raw_ptr()->offset_in_words_to_field_);
   if (array.IsNull()) {
     ASSERT(is_finalized());
-    const intptr_t length = raw_ptr()->instance_size_in_words_;
+    const intptr_t length = raw_ptr()->host_instance_size_in_words_;
     array = Array::New(length, Heap::kOld);
     Class& cls = Class::Handle(this->raw());
     Array& fields = Array::Handle();
@@ -2737,7 +2778,7 @@
       for (intptr_t i = 0; i < fields.Length(); ++i) {
         f ^= fields.At(i);
         if (f.is_instance()) {
-          array.SetAt(f.Offset() >> kWordSizeLog2, f);
+          array.SetAt(f.HostOffset() >> kWordSizeLog2, f);
         }
       }
       cls = cls.SuperClass(original_classes);
@@ -3120,51 +3161,127 @@
   return TypeParameter::null();
 }
 
-void Class::CalculateFieldOffsets() const {
+UnboxedFieldBitmap Class::CalculateFieldOffsets() const {
   Array& flds = Array::Handle(fields());
   const Class& super = Class::Handle(SuperClass());
-  intptr_t offset = 0;
-  intptr_t type_args_field_offset = kNoTypeArguments;
+  intptr_t host_offset = 0;
+  UnboxedFieldBitmap host_bitmap{};
+  // Target offsets might differ if the word size are different
+  intptr_t target_offset = 0;
+  intptr_t host_type_args_field_offset = kNoTypeArguments;
+  intptr_t target_type_args_field_offset = RTN::Class::kNoTypeArguments;
   if (super.IsNull()) {
-    offset = Instance::NextFieldOffset();
-    ASSERT(offset > 0);
+    host_offset = Instance::NextFieldOffset();
+    target_offset = RTN::Instance::NextFieldOffset();
+    ASSERT(host_offset > 0);
+    ASSERT(target_offset > 0);
   } else {
     ASSERT(super.is_finalized() || super.is_prefinalized());
-    type_args_field_offset = super.type_arguments_field_offset();
-    offset = super.next_field_offset();
-    ASSERT(offset > 0);
+    host_type_args_field_offset = super.host_type_arguments_field_offset();
+    target_type_args_field_offset = super.target_type_arguments_field_offset();
+    host_offset = super.host_next_field_offset();
+    ASSERT(host_offset > 0);
+    target_offset = super.target_next_field_offset();
+    ASSERT(target_offset > 0);
     // We should never call CalculateFieldOffsets for native wrapper
     // classes, assert this.
     ASSERT(num_native_fields() == 0);
     set_num_native_fields(super.num_native_fields());
+
+    if (FLAG_precompiled_mode) {
+      host_bitmap =
+          Isolate::Current()->shared_class_table()->GetUnboxedFieldsMapAt(
+              super.id());
+    }
   }
   // If the super class is parameterized, use the same type_arguments field,
   // otherwise, if this class is the first in the super chain to be
   // parameterized, introduce a new type_arguments field.
-  if (type_args_field_offset == kNoTypeArguments) {
+  if (host_type_args_field_offset == kNoTypeArguments) {
+    ASSERT(target_type_args_field_offset == RTN::Class::kNoTypeArguments);
     const TypeArguments& type_params = TypeArguments::Handle(type_parameters());
     if (!type_params.IsNull()) {
       ASSERT(type_params.Length() > 0);
       // The instance needs a type_arguments field.
-      type_args_field_offset = offset;
-      offset += kWordSize;
+      host_type_args_field_offset = host_offset;
+      target_type_args_field_offset = target_offset;
+      host_offset += kWordSize;
+      target_offset += compiler::target::kWordSize;
     }
+  } else {
+    ASSERT(target_type_args_field_offset != RTN::Class::kNoTypeArguments);
   }
-  set_type_arguments_field_offset(type_args_field_offset);
-  ASSERT(offset > 0);
+
+  set_type_arguments_field_offset(host_type_args_field_offset,
+                                  target_type_args_field_offset);
+  ASSERT(host_offset > 0);
+  ASSERT(target_offset > 0);
   Field& field = Field::Handle();
-  intptr_t len = flds.Length();
+  const intptr_t len = flds.Length();
   for (intptr_t i = 0; i < len; i++) {
     field ^= flds.At(i);
     // Offset is computed only for instance fields.
     if (!field.is_static()) {
-      ASSERT(field.Offset() == 0);
-      field.SetOffset(offset);
-      offset += kWordSize;
+      ASSERT(field.HostOffset() == 0);
+      ASSERT(field.TargetOffset() == 0);
+      field.SetOffset(host_offset, target_offset);
+
+      if (FLAG_precompiled_mode && field.is_unboxing_candidate()) {
+        intptr_t field_size;
+        switch (field.guarded_cid()) {
+          case kDoubleCid:
+            field_size = sizeof(RawDouble::value_);
+            break;
+          case kFloat32x4Cid:
+            field_size = sizeof(RawFloat32x4::value_);
+            break;
+          case kFloat64x2Cid:
+            field_size = sizeof(RawFloat64x2::value_);
+            break;
+          default:
+            UNREACHABLE();
+            field_size = 0;
+            break;
+        }
+
+        const intptr_t host_num_words = field_size / kWordSize;
+        const intptr_t host_next_offset = host_offset + field_size;
+        const intptr_t host_next_position = host_next_offset / kWordSize;
+
+        const intptr_t target_next_offset = target_offset + field_size;
+        const intptr_t target_next_position =
+            target_next_offset / compiler::target::kWordSize;
+
+        // The bitmap has fixed length. Checks if the offset position is smaller
+        // than its length. If it is not, than the field should be boxed
+        if (host_next_position <= UnboxedFieldBitmap::Length() &&
+            target_next_position <= UnboxedFieldBitmap::Length()) {
+          for (intptr_t j = 0; j < host_num_words; j++) {
+            // Activate the respective bit in the bitmap, indicating that the
+            // content is not a pointer
+            host_bitmap.Set(host_offset / kWordSize);
+            host_offset += kWordSize;
+          }
+
+          ASSERT(host_offset == host_next_offset);
+          target_offset = target_next_offset;
+        } else {
+          // Make the field boxed
+          field.set_is_unboxing_candidate(false);
+          host_offset += kWordSize;
+          target_offset += compiler::target::kWordSize;
+        }
+      } else {
+        host_offset += kWordSize;
+        target_offset += compiler::target::kWordSize;
+      }
     }
   }
-  set_instance_size(RoundedAllocationSize(offset));
-  set_next_field_offset(offset);
+  set_instance_size(RoundedAllocationSize(host_offset),
+                    compiler::target::RoundedAllocationSize(target_offset));
+  set_next_field_offset(host_offset, target_offset);
+
+  return host_bitmap;
 }
 
 void Class::AddInvocationDispatcher(const String& target_name,
@@ -3519,20 +3636,44 @@
 }
 
 void Class::Finalize() const {
-  Isolate* isolate = Isolate::Current();
-  ASSERT(Thread::Current()->IsMutatorThread());
+  auto thread = Thread::Current();
+  auto Z = thread->zone();
+  Isolate* isolate = thread->isolate();
+  ASSERT(thread->IsMutatorThread());
   ASSERT(!isolate->all_classes_finalized());
   ASSERT(!is_finalized());
   // Prefinalized classes have a VM internal representation and no Dart fields.
   // Their instance size  is precomputed and field offsets are known.
   if (!is_prefinalized()) {
-    // Compute offsets of instance fields and instance size.
-    CalculateFieldOffsets();
+    // Compute offsets of instance fields, instance size and bitmap for unboxed
+    // fields.
+    const auto host_bitmap = CalculateFieldOffsets();
     if (raw() == isolate->class_table()->At(id())) {
       // Sets the new size in the class table.
       isolate->class_table()->SetAt(id(), raw());
+      if (FLAG_precompiled_mode) {
+        isolate->shared_class_table()->SetUnboxedFieldsMapAt(id(), host_bitmap);
+      }
     }
   }
+
+  if (SuperClass() == Class::null() ||
+      Class::Handle(Z, SuperClass()).is_const()) {
+    const auto& fields = Array::Handle(Z, this->fields());
+    auto& field = Field::Handle(Z);
+    bool is_const = true;
+    for (intptr_t i = 0; i < fields.Length(); ++i) {
+      field ^= fields.At(i);
+      if (!field.is_static() && !field.is_final()) {
+        is_const = false;
+        break;
+      }
+    }
+    if (is_const) {
+      set_is_const();
+    }
+  }
+
   set_is_finalized();
 }
 
@@ -4040,7 +4181,7 @@
   return true;
 }
 
-template <class FakeInstance>
+template <class FakeInstance, class TargetFakeInstance>
 RawClass* Class::NewCommon(intptr_t index) {
   ASSERT(Object::class_class() != Class::null());
   Class& result = Class::Handle();
@@ -4055,9 +4196,17 @@
                                                                  : index);
   result.set_token_pos(TokenPosition::kNoSource);
   result.set_end_token_pos(TokenPosition::kNoSource);
-  result.set_instance_size(FakeInstance::InstanceSize());
-  result.set_type_arguments_field_offset_in_words(kNoTypeArguments);
-  result.set_next_field_offset(FakeInstance::NextFieldOffset());
+  const intptr_t host_instance_size = FakeInstance::InstanceSize();
+  const intptr_t target_instance_size = compiler::target::RoundedAllocationSize(
+      TargetFakeInstance::InstanceSize());
+  result.set_instance_size(host_instance_size, target_instance_size);
+  result.set_type_arguments_field_offset_in_words(kNoTypeArguments,
+                                                  RTN::Class::kNoTypeArguments);
+  const intptr_t host_next_field_offset = FakeInstance::NextFieldOffset();
+  const intptr_t target_next_field_offset =
+      TargetFakeInstance::NextFieldOffset();
+  result.set_next_field_offset(host_next_field_offset,
+                               target_next_field_offset);
   result.set_id(index);
   result.set_num_type_arguments(kUnknownNumTypeArguments);
   result.set_num_native_fields(0);
@@ -4068,12 +4217,13 @@
   return result.raw();
 }
 
-template <class FakeInstance>
+template <class FakeInstance, class TargetFakeInstance>
 RawClass* Class::New(intptr_t index,
                      Isolate* isolate,
                      bool register_class,
                      bool is_abstract) {
-  Class& result = Class::Handle(NewCommon<FakeInstance>(index));
+  Class& result =
+      Class::Handle(NewCommon<FakeInstance, TargetFakeInstance>(index));
   if (is_abstract) {
     result.set_is_abstract();
   }
@@ -4088,7 +4238,8 @@
                      const Script& script,
                      TokenPosition token_pos,
                      bool register_class) {
-  Class& result = Class::Handle(NewCommon<Instance>(kIllegalCid));
+  Class& result =
+      Class::Handle(NewCommon<Instance, RTN::Instance>(kIllegalCid));
   result.set_library(lib);
   result.set_name(name);
   result.set_script(script);
@@ -4097,7 +4248,7 @@
   // The size gets initialized to 0. Once the class gets finalized the class
   // finalizer will set the correct size.
   ASSERT(!result.is_finalized() && !result.is_prefinalized());
-  result.set_instance_size_in_words(0);
+  result.set_instance_size_in_words(0, 0);
 
   if (register_class) {
     Isolate::Current()->RegisterClass(result);
@@ -4106,7 +4257,7 @@
 }
 
 RawClass* Class::NewInstanceClass() {
-  return Class::New<Instance>(kIllegalCid, Isolate::Current());
+  return Class::New<Instance, RTN::Instance>(kIllegalCid, Isolate::Current());
 }
 
 RawClass* Class::NewNativeWrapper(const Library& library,
@@ -4121,9 +4272,13 @@
     cls.set_super_type(Type::Handle(Type::ObjectType()));
     // Compute instance size. First word contains a pointer to a properly
     // sized typed array once the first native field has been set.
-    intptr_t instance_size = sizeof(RawInstance) + kWordSize;
-    cls.set_instance_size(RoundedAllocationSize(instance_size));
-    cls.set_next_field_offset(instance_size);
+    const intptr_t host_instance_size = sizeof(RawInstance) + kWordSize;
+    const intptr_t target_instance_size =
+        sizeof(RawInstance) + compiler::target::kWordSize;
+    cls.set_instance_size(
+        RoundedAllocationSize(host_instance_size),
+        compiler::target::RoundedAllocationSize(target_instance_size));
+    cls.set_next_field_offset(host_instance_size, target_instance_size);
     cls.set_num_native_fields(field_count);
     cls.set_is_finalized();
     cls.set_is_declaration_loaded();
@@ -4137,21 +4292,33 @@
 }
 
 RawClass* Class::NewStringClass(intptr_t class_id, Isolate* isolate) {
-  intptr_t instance_size;
+  intptr_t host_instance_size, target_instance_size;
   if (class_id == kOneByteStringCid) {
-    instance_size = OneByteString::InstanceSize();
+    host_instance_size = OneByteString::InstanceSize();
+    target_instance_size = compiler::target::RoundedAllocationSize(
+        RTN::OneByteString::InstanceSize());
   } else if (class_id == kTwoByteStringCid) {
-    instance_size = TwoByteString::InstanceSize();
+    host_instance_size = TwoByteString::InstanceSize();
+    target_instance_size = compiler::target::RoundedAllocationSize(
+        RTN::TwoByteString::InstanceSize());
   } else if (class_id == kExternalOneByteStringCid) {
-    instance_size = ExternalOneByteString::InstanceSize();
+    host_instance_size = ExternalOneByteString::InstanceSize();
+    target_instance_size = compiler::target::RoundedAllocationSize(
+        RTN::ExternalOneByteString::InstanceSize());
   } else {
     ASSERT(class_id == kExternalTwoByteStringCid);
-    instance_size = ExternalTwoByteString::InstanceSize();
+    host_instance_size = ExternalTwoByteString::InstanceSize();
+    target_instance_size = compiler::target::RoundedAllocationSize(
+        RTN::ExternalTwoByteString::InstanceSize());
   }
-  Class& result =
-      Class::Handle(New<String>(class_id, isolate, /*register_class=*/false));
-  result.set_instance_size(instance_size);
-  result.set_next_field_offset(String::NextFieldOffset());
+  Class& result = Class::Handle(
+      New<String, RTN::String>(class_id, isolate, /*register_class=*/false));
+  result.set_instance_size(host_instance_size, target_instance_size);
+
+  const intptr_t host_next_field_offset = String::NextFieldOffset();
+  const intptr_t target_next_field_offset = RTN::String::NextFieldOffset();
+  result.set_next_field_offset(host_next_field_offset,
+                               target_next_field_offset);
   result.set_is_prefinalized();
   isolate->RegisterClass(result);
   return result.raw();
@@ -4159,11 +4326,17 @@
 
 RawClass* Class::NewTypedDataClass(intptr_t class_id, Isolate* isolate) {
   ASSERT(RawObject::IsTypedDataClassId(class_id));
-  intptr_t instance_size = TypedData::InstanceSize();
-  Class& result = Class::Handle(
-      New<TypedData>(class_id, isolate, /*register_class=*/false));
-  result.set_instance_size(instance_size);
-  result.set_next_field_offset(TypedData::NextFieldOffset());
+  const intptr_t host_instance_size = TypedData::InstanceSize();
+  const intptr_t target_instance_size =
+      compiler::target::RoundedAllocationSize(RTN::TypedData::InstanceSize());
+  Class& result = Class::Handle(New<TypedData, RTN::TypedData>(
+      class_id, isolate, /*register_class=*/false));
+  result.set_instance_size(host_instance_size, target_instance_size);
+
+  const intptr_t host_next_field_offset = TypedData::NextFieldOffset();
+  const intptr_t target_next_field_offset = RTN::TypedData::NextFieldOffset();
+  result.set_next_field_offset(host_next_field_offset,
+                               target_next_field_offset);
   result.set_is_prefinalized();
   isolate->RegisterClass(result);
   return result.raw();
@@ -4171,11 +4344,18 @@
 
 RawClass* Class::NewTypedDataViewClass(intptr_t class_id, Isolate* isolate) {
   ASSERT(RawObject::IsTypedDataViewClassId(class_id));
-  const intptr_t instance_size = TypedDataView::InstanceSize();
-  Class& result = Class::Handle(
-      New<TypedDataView>(class_id, isolate, /*register_class=*/false));
-  result.set_instance_size(instance_size);
-  result.set_next_field_offset(TypedDataView::NextFieldOffset());
+  const intptr_t host_instance_size = TypedDataView::InstanceSize();
+  const intptr_t target_instance_size = compiler::target::RoundedAllocationSize(
+      RTN::TypedDataView::InstanceSize());
+  Class& result = Class::Handle(New<TypedDataView, RTN::TypedDataView>(
+      class_id, isolate, /*register_class=*/false));
+  result.set_instance_size(host_instance_size, target_instance_size);
+
+  const intptr_t host_next_field_offset = TypedDataView::NextFieldOffset();
+  const intptr_t target_next_field_offset =
+      RTN::TypedDataView::NextFieldOffset();
+  result.set_next_field_offset(host_next_field_offset,
+                               target_next_field_offset);
   result.set_is_prefinalized();
   isolate->RegisterClass(result);
   return result.raw();
@@ -4184,11 +4364,18 @@
 RawClass* Class::NewExternalTypedDataClass(intptr_t class_id,
                                            Isolate* isolate) {
   ASSERT(RawObject::IsExternalTypedDataClassId(class_id));
-  intptr_t instance_size = ExternalTypedData::InstanceSize();
-  Class& result = Class::Handle(
-      New<ExternalTypedData>(class_id, isolate, /*register_class=*/false));
-  result.set_instance_size(instance_size);
-  result.set_next_field_offset(ExternalTypedData::NextFieldOffset());
+  const intptr_t host_instance_size = ExternalTypedData::InstanceSize();
+  const intptr_t target_instance_size = compiler::target::RoundedAllocationSize(
+      RTN::ExternalTypedData::InstanceSize());
+  Class& result = Class::Handle(New<ExternalTypedData, RTN::ExternalTypedData>(
+      class_id, isolate, /*register_class=*/false));
+
+  const intptr_t host_next_field_offset = ExternalTypedData::NextFieldOffset();
+  const intptr_t target_next_field_offset =
+      RTN::ExternalTypedData::NextFieldOffset();
+  result.set_instance_size(host_instance_size, target_instance_size);
+  result.set_next_field_offset(host_next_field_offset,
+                               target_next_field_offset);
   result.set_is_prefinalized();
   isolate->RegisterClass(result);
   return result.raw();
@@ -4196,12 +4383,20 @@
 
 RawClass* Class::NewPointerClass(intptr_t class_id, Isolate* isolate) {
   ASSERT(RawObject::IsFfiPointerClassId(class_id));
-  intptr_t instance_size = Pointer::InstanceSize();
-  Class& result =
-      Class::Handle(New<Pointer>(class_id, isolate, /*register_class=*/false));
-  result.set_instance_size(instance_size);
-  result.set_type_arguments_field_offset(Pointer::type_arguments_offset());
-  result.set_next_field_offset(Pointer::NextFieldOffset());
+  intptr_t host_instance_size = Pointer::InstanceSize();
+  intptr_t target_instance_size =
+      compiler::target::RoundedAllocationSize(RTN::Pointer::InstanceSize());
+  Class& result = Class::Handle(
+      New<Pointer, RTN::Pointer>(class_id, isolate, /*register_class=*/false));
+  result.set_instance_size(host_instance_size, target_instance_size);
+  result.set_type_arguments_field_offset(Pointer::type_arguments_offset(),
+                                         RTN::Pointer::type_arguments_offset());
+
+  const intptr_t host_next_field_offset = Pointer::NextFieldOffset();
+  const intptr_t target_next_field_offset = RTN::Pointer::NextFieldOffset();
+
+  result.set_next_field_offset(host_next_field_offset,
+                               target_next_field_offset);
   result.set_is_prefinalized();
   isolate->RegisterClass(result);
   return result.raw();
@@ -8793,12 +8988,6 @@
   }
 }
 
-void Instance::SetField(const Field& field, const Object& value) const {
-  field.RecordStore(value);
-  const Object* stored_value = field.CloneForUnboxed(value);
-  StorePointer(FieldAddr(field), stored_value->raw());
-}
-
 const Object* Field::CloneForUnboxed(const Object& value) const {
   if (FLAG_unbox_numeric_fields && is_unboxing_candidate() && !is_nullable()) {
     switch (guarded_cid()) {
@@ -8993,7 +9182,7 @@
   result.set_name(name);
   result.set_is_static(is_static);
   if (!is_static) {
-    result.SetOffset(0);
+    result.SetOffset(0, 0);
   }
   result.set_is_final(is_final);
   result.set_is_const(is_const);
@@ -9005,7 +9194,12 @@
   result.set_end_token_pos(end_token_pos);
   result.set_has_nontrivial_initializer(false);
   result.set_has_initializer(false);
-  result.set_is_unboxing_candidate(!is_final && !is_late && !is_static);
+  if (FLAG_precompiled_mode) {
+    // May be updated by KernelLoader::ReadInferredType
+    result.set_is_unboxing_candidate(false);
+  } else {
+    result.set_is_unboxing_candidate(!is_final && !is_late && !is_static);
+  }
   result.set_initializer_changed_after_initialization(false);
   NOT_IN_PRECOMPILED(result.set_is_declared_in_bytecode(false));
   NOT_IN_PRECOMPILED(result.set_binary_declaration_offset(0));
@@ -9592,7 +9786,7 @@
 }
 
 static StaticTypeExactnessState TrivialTypeExactnessFor(const Class& cls) {
-  const intptr_t type_arguments_offset = cls.type_arguments_field_offset();
+  const intptr_t type_arguments_offset = cls.host_type_arguments_field_offset();
   ASSERT(type_arguments_offset != Class::kNoTypeArguments);
   if (StaticTypeExactnessState::CanRepresentAsTriviallyExact(
           type_arguments_offset / kWordSize)) {
@@ -16892,10 +17086,19 @@
   hash = instance_size / kWordSize;
   uword this_addr = reinterpret_cast<uword>(this->raw_ptr());
   Instance& member = Instance::Handle();
+  const auto unboxed_fields_bitmap =
+      thread->isolate()->shared_class_table()->GetUnboxedFieldsMapAt(
+          GetClassId());
+
   for (intptr_t offset = Instance::NextFieldOffset(); offset < instance_size;
        offset += kWordSize) {
-    member ^= *reinterpret_cast<RawObject**>(this_addr + offset);
-    hash = CombineHashes(hash, member.CanonicalizeHash());
+    if (unboxed_fields_bitmap.Get(offset / kWordSize)) {
+      hash =
+          CombineHashes(hash, *reinterpret_cast<intptr_t*>(this_addr + offset));
+    } else {
+      member ^= *reinterpret_cast<RawObject**>(this_addr + offset);
+      hash = CombineHashes(hash, member.CanonicalizeHash());
+    }
   }
   hash = FinalizeHash(hash, String::kHashBits);
   thread->heap()->SetCanonicalHash(raw(), hash);
@@ -16927,15 +17130,22 @@
                                           const char** error_str) const {
   ASSERT(error_str != NULL);
   ASSERT(*error_str == NULL);
-  if (GetClassId() >= kNumPredefinedCids) {
+  const intptr_t class_id = GetClassId();
+  if (class_id >= kNumPredefinedCids) {
     // Iterate over all fields, canonicalize numbers and strings, expect all
     // other instances to be canonical otherwise report error (return false).
     Zone* zone = thread->zone();
     Object& obj = Object::Handle(zone);
     const intptr_t instance_size = SizeFromClass();
     ASSERT(instance_size != 0);
+    const auto unboxed_fields_bitmap =
+        thread->isolate()->shared_class_table()->GetUnboxedFieldsMapAt(
+            GetClassId());
     for (intptr_t offset = Instance::NextFieldOffset(); offset < instance_size;
          offset += kWordSize) {
+      if (unboxed_fields_bitmap.Get(offset / kWordSize)) {
+        continue;
+      }
       obj = *this->FieldAddrAtOffset(offset);
       if (obj.IsInstance() && !obj.IsSmi() && !obj.IsCanonical()) {
         if (obj.IsNumber() || obj.IsString()) {
@@ -17014,6 +17224,53 @@
 }
 #endif  // DEBUG
 
+RawObject* Instance::GetField(const Field& field) const {
+  if (FLAG_precompiled_mode && field.is_unboxing_candidate()) {
+    switch (field.guarded_cid()) {
+      case kDoubleCid:
+        return Double::New(
+            LoadNonPointer(reinterpret_cast<double_t*>(FieldAddr(field))));
+      case kFloat32x4Cid:
+        return Float32x4::New(
+            *reinterpret_cast<simd128_value_t*>(FieldAddr(field)));
+      case kFloat64x2Cid:
+        return Float64x2::New(
+            *reinterpret_cast<simd128_value_t*>(FieldAddr(field)));
+      default:
+        UNREACHABLE();
+        return nullptr;
+    }
+  } else {
+    return *FieldAddr(field);
+  }
+}
+
+void Instance::SetField(const Field& field, const Object& value) const {
+  if (FLAG_precompiled_mode && field.is_unboxing_candidate()) {
+    switch (field.guarded_cid()) {
+      case kDoubleCid:
+        StoreNonPointer(reinterpret_cast<double_t*>(FieldAddr(field)),
+                        Double::Cast(value).value());
+        break;
+      case kFloat32x4Cid:
+        StoreNonPointer(reinterpret_cast<simd128_value_t*>(FieldAddr(field)),
+                        Float32x4::Cast(value).value());
+        break;
+      case kFloat64x2Cid:
+        StoreNonPointer(reinterpret_cast<simd128_value_t*>(FieldAddr(field)),
+                        Float64x2::Cast(value).value());
+        break;
+      default:
+        UNREACHABLE();
+        break;
+    }
+  } else {
+    field.RecordStore(value);
+    const Object* stored_value = field.CloneForUnboxed(value);
+    StorePointer(FieldAddr(field), stored_value->raw());
+  }
+}
+
 RawAbstractType* Instance::GetType(Heap::Space space) const {
   if (IsNull()) {
     return Type::NullType();
@@ -17058,7 +17315,7 @@
 RawTypeArguments* Instance::GetTypeArguments() const {
   ASSERT(!IsType());
   const Class& cls = Class::Handle(clazz());
-  intptr_t field_offset = cls.type_arguments_field_offset();
+  intptr_t field_offset = cls.host_type_arguments_field_offset();
   ASSERT(field_offset != Class::kNoTypeArguments);
   TypeArguments& type_arguments = TypeArguments::Handle();
   type_arguments ^= *FieldAddrAtOffset(field_offset);
@@ -17069,7 +17326,7 @@
   ASSERT(!IsType());
   ASSERT(value.IsNull() || value.IsCanonical());
   const Class& cls = Class::Handle(clazz());
-  intptr_t field_offset = cls.type_arguments_field_offset();
+  intptr_t field_offset = cls.host_type_arguments_field_offset();
   ASSERT(field_offset != Class::kNoTypeArguments);
   SetFieldAtOffset(field_offset, value);
 }
@@ -17436,17 +17693,18 @@
   if (cls.EnsureIsFinalized(thread) != Error::null()) {
     return Instance::null();
   }
-  intptr_t instance_size = cls.instance_size();
+  intptr_t instance_size = cls.host_instance_size();
   ASSERT(instance_size > 0);
   RawObject* raw = Object::Allocate(cls.id(), instance_size, space);
   return reinterpret_cast<RawInstance*>(raw);
 }
 
 RawInstance* Instance::NewFromCidAndSize(SharedClassTable* shared_class_table,
-                                         classid_t cid) {
+                                         classid_t cid,
+                                         Heap::Space heap) {
   const intptr_t instance_size = shared_class_table->SizeAt(cid);
   ASSERT(instance_size > 0);
-  RawObject* raw = Object::Allocate(cid, instance_size, Heap::kNew);
+  RawObject* raw = Object::Allocate(cid, instance_size, heap);
   return reinterpret_cast<RawInstance*>(raw);
 }
 
@@ -17455,7 +17713,7 @@
   REUSABLE_CLASS_HANDLESCOPE(thread);
   Class& cls = thread->ClassHandle();
   cls = clazz();
-  return (offset >= 0 && offset <= (cls.instance_size() - kWordSize));
+  return (offset >= 0 && offset <= (cls.host_instance_size() - kWordSize));
 }
 
 intptr_t Instance::ElementSizeFor(intptr_t cid) {
@@ -17618,7 +17876,9 @@
   }
   // TODO(regis): TypeRefs are problematic, since changing the nullability of
   // a type by cloning it may break the graph of a recursive type.
-  UNREACHABLE();
+  ASSERT(IsTypeRef());
+  return AbstractType::Handle(TypeRef::Cast(*this).type())
+      .CheckInstantiatedNullability(mode, type_param, space);
 }
 
 bool AbstractType::IsInstantiated(Genericity genericity,
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 2759213..ff4a902 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -266,6 +266,15 @@
 #define MINT_OBJECT_IMPLEMENTATION(object, rettype, super)                     \
   FINAL_HEAP_OBJECT_IMPLEMENTATION_HELPER(object, rettype, super)
 
+// In precompiled runtime, there is no access to runtime_api.cc since host
+// and target are the same. In those cases, the namespace dart is used to refer
+// to the target namespace
+#if defined(DART_PRECOMPILED_RUNTIME)
+namespace RTN = dart;
+#else
+namespace RTN = dart::compiler::target;
+#endif  //  defined(DART_PRECOMPILED_RUNTIME)
+
 class Object {
  public:
   using RawObjectType = RawObject;
@@ -885,36 +894,88 @@
     kInvocationDispatcherEntrySize,
   };
 
-  intptr_t instance_size() const {
+  intptr_t host_instance_size() const {
     ASSERT(is_finalized() || is_prefinalized());
-    return (raw_ptr()->instance_size_in_words_ * kWordSize);
+    return (raw_ptr()->host_instance_size_in_words_ * kWordSize);
   }
-  static intptr_t instance_size(RawClass* clazz) {
-    return (clazz->ptr()->instance_size_in_words_ * kWordSize);
+  intptr_t target_instance_size() const {
+    ASSERT(is_finalized() || is_prefinalized());
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    return (raw_ptr()->target_instance_size_in_words_ *
+            compiler::target::kWordSize);
+#else
+    return host_instance_size();
+#endif  // !defined(DART_PRECOMPILED_RUNTIME)
   }
-  void set_instance_size(intptr_t value_in_bytes) const {
+  static intptr_t host_instance_size(RawClass* clazz) {
+    return (clazz->ptr()->host_instance_size_in_words_ * kWordSize);
+  }
+  static intptr_t target_instance_size(RawClass* clazz) {
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    return (clazz->ptr()->target_instance_size_in_words_ *
+            compiler::target::kWordSize);
+#else
+    return host_instance_size(clazz);
+#endif  // !defined(DART_PRECOMPILED_RUNTIME)
+  }
+  void set_instance_size(intptr_t host_value_in_bytes,
+                         intptr_t target_value_in_bytes) const {
     ASSERT(kWordSize != 0);
-    set_instance_size_in_words(value_in_bytes / kWordSize);
+    set_instance_size_in_words(
+        host_value_in_bytes / kWordSize,
+        target_value_in_bytes / compiler::target::kWordSize);
   }
-  void set_instance_size_in_words(intptr_t value) const {
-    ASSERT(Utils::IsAligned((value * kWordSize), kObjectAlignment));
-    StoreNonPointer(&raw_ptr()->instance_size_in_words_, value);
+  void set_instance_size_in_words(intptr_t host_value,
+                                  intptr_t target_value) const {
+    ASSERT(Utils::IsAligned((host_value * kWordSize), kObjectAlignment));
+    StoreNonPointer(&raw_ptr()->host_instance_size_in_words_, host_value);
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    ASSERT(Utils::IsAligned((target_value * compiler::target::kWordSize),
+                            compiler::target::kObjectAlignment));
+    StoreNonPointer(&raw_ptr()->target_instance_size_in_words_, target_value);
+#else
+    ASSERT(host_value == target_value);
+#endif  // #!defined(DART_PRECOMPILED_RUNTIME)
   }
 
-  intptr_t next_field_offset() const {
-    return raw_ptr()->next_field_offset_in_words_ * kWordSize;
+  intptr_t host_next_field_offset() const {
+    return raw_ptr()->host_next_field_offset_in_words_ * kWordSize;
   }
-  void set_next_field_offset(intptr_t value_in_bytes) const {
-    ASSERT(kWordSize != 0);
-    set_next_field_offset_in_words(value_in_bytes / kWordSize);
+  intptr_t target_next_field_offset() const {
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    return raw_ptr()->target_next_field_offset_in_words_ *
+           compiler::target::kWordSize;
+#else
+    return host_next_field_offset();
+#endif  // #!defined(DART_PRECOMPILED_RUNTIME)
   }
-  void set_next_field_offset_in_words(intptr_t value) const {
-    ASSERT((value == -1) ||
-           (Utils::IsAligned((value * kWordSize), kObjectAlignment) &&
-            (value == raw_ptr()->instance_size_in_words_)) ||
-           (!Utils::IsAligned((value * kWordSize), kObjectAlignment) &&
-            ((value + 1) == raw_ptr()->instance_size_in_words_)));
-    StoreNonPointer(&raw_ptr()->next_field_offset_in_words_, value);
+  void set_next_field_offset(intptr_t host_value_in_bytes,
+                             intptr_t target_value_in_bytes) const {
+    set_next_field_offset_in_words(
+        host_value_in_bytes / kWordSize,
+        target_value_in_bytes / compiler::target::kWordSize);
+  }
+  void set_next_field_offset_in_words(intptr_t host_value,
+                                      intptr_t target_value) const {
+    ASSERT((host_value == -1) ||
+           (Utils::IsAligned((host_value * kWordSize), kObjectAlignment) &&
+            (host_value == raw_ptr()->host_instance_size_in_words_)) ||
+           (!Utils::IsAligned((host_value * kWordSize), kObjectAlignment) &&
+            ((host_value + 1) == raw_ptr()->host_instance_size_in_words_)));
+    StoreNonPointer(&raw_ptr()->host_next_field_offset_in_words_, host_value);
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    ASSERT((target_value == -1) ||
+           (Utils::IsAligned((target_value * compiler::target::kWordSize),
+                             compiler::target::kObjectAlignment) &&
+            (target_value == raw_ptr()->target_instance_size_in_words_)) ||
+           (!Utils::IsAligned((target_value * compiler::target::kWordSize),
+                              compiler::target::kObjectAlignment) &&
+            ((target_value + 1) == raw_ptr()->target_instance_size_in_words_)));
+    StoreNonPointer(&raw_ptr()->target_next_field_offset_in_words_,
+                    target_value);
+#else
+    ASSERT(host_value == target_value);
+#endif  // #!defined(DART_PRECOMPILED_RUNTIME)
   }
 
   static bool is_valid_id(intptr_t value) {
@@ -1013,28 +1074,64 @@
 
   // If this class is parameterized, each instance has a type_arguments field.
   static const intptr_t kNoTypeArguments = -1;
-  intptr_t type_arguments_field_offset() const {
+  intptr_t host_type_arguments_field_offset() const {
     ASSERT(is_type_finalized() || is_prefinalized());
-    if (raw_ptr()->type_arguments_field_offset_in_words_ == kNoTypeArguments) {
+    if (raw_ptr()->host_type_arguments_field_offset_in_words_ ==
+        kNoTypeArguments) {
       return kNoTypeArguments;
     }
-    return raw_ptr()->type_arguments_field_offset_in_words_ * kWordSize;
+    return raw_ptr()->host_type_arguments_field_offset_in_words_ * kWordSize;
   }
-  void set_type_arguments_field_offset(intptr_t value_in_bytes) const {
-    intptr_t value;
-    if (value_in_bytes == kNoTypeArguments) {
-      value = kNoTypeArguments;
-    } else {
-      ASSERT(kWordSize != 0);
-      value = value_in_bytes / kWordSize;
+  intptr_t target_type_arguments_field_offset() const {
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    ASSERT(is_type_finalized() || is_prefinalized());
+    if (raw_ptr()->target_type_arguments_field_offset_in_words_ ==
+        compiler::target::Class::kNoTypeArguments) {
+      return compiler::target::Class::kNoTypeArguments;
     }
-    set_type_arguments_field_offset_in_words(value);
+    return raw_ptr()->target_type_arguments_field_offset_in_words_ *
+           compiler::target::kWordSize;
+#else
+    return host_type_arguments_field_offset();
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
   }
-  void set_type_arguments_field_offset_in_words(intptr_t value) const {
-    StoreNonPointer(&raw_ptr()->type_arguments_field_offset_in_words_, value);
+  void set_type_arguments_field_offset(intptr_t host_value_in_bytes,
+                                       intptr_t target_value_in_bytes) const {
+    intptr_t host_value, target_value;
+    if (host_value_in_bytes == kNoTypeArguments ||
+        target_value_in_bytes == RTN::Class::kNoTypeArguments) {
+      ASSERT(host_value_in_bytes == kNoTypeArguments &&
+             target_value_in_bytes == RTN::Class::kNoTypeArguments);
+      host_value = kNoTypeArguments;
+      target_value = RTN::Class::kNoTypeArguments;
+    } else {
+      ASSERT(kWordSize != 0 && compiler::target::kWordSize);
+      host_value = host_value_in_bytes / kWordSize;
+      target_value = target_value_in_bytes / compiler::target::kWordSize;
+    }
+    set_type_arguments_field_offset_in_words(host_value, target_value);
   }
-  static intptr_t type_arguments_field_offset_in_words_offset() {
-    return OFFSET_OF(RawClass, type_arguments_field_offset_in_words_);
+  void set_type_arguments_field_offset_in_words(intptr_t host_value,
+                                                intptr_t target_value) const {
+    StoreNonPointer(&raw_ptr()->host_type_arguments_field_offset_in_words_,
+                    host_value);
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    StoreNonPointer(&raw_ptr()->target_type_arguments_field_offset_in_words_,
+                    target_value);
+#else
+    ASSERT(host_value == target_value);
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
+  }
+  static intptr_t host_type_arguments_field_offset_in_words_offset() {
+    return OFFSET_OF(RawClass, host_type_arguments_field_offset_in_words_);
+  }
+
+  static intptr_t target_type_arguments_field_offset_in_words_offset() {
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    return OFFSET_OF(RawClass, target_type_arguments_field_offset_in_words_);
+#else
+    return host_type_arguments_field_offset_in_words_offset();
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
   }
 
   // The super type of this class, Object type if not explicitly specified.
@@ -1395,7 +1492,7 @@
   RawError* EnsureIsFinalized(Thread* thread) const;
 
   // Allocate a class used for VM internal objects.
-  template <class FakeObject>
+  template <class FakeObject, class TargetFakeObject>
   static RawClass* New(Isolate* isolate, bool register_class = true);
 
   // Allocate instance classes.
@@ -1460,6 +1557,44 @@
                                const Array& args_desc,
                                const Function& dispatcher) const;
 
+  static int32_t host_instance_size_in_words(const RawClass* cls) {
+    return cls->ptr()->host_instance_size_in_words_;
+  }
+
+  static int32_t target_instance_size_in_words(const RawClass* cls) {
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    return cls->ptr()->target_instance_size_in_words_;
+#else
+    return host_instance_size_in_words(cls);
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
+  }
+
+  static int32_t host_next_field_offset_in_words(const RawClass* cls) {
+    return cls->ptr()->host_next_field_offset_in_words_;
+  }
+
+  static int32_t target_next_field_offset_in_words(const RawClass* cls) {
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    return cls->ptr()->target_next_field_offset_in_words_;
+#else
+    return host_next_field_offset_in_words(cls);
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
+  }
+
+  static int32_t host_type_arguments_field_offset_in_words(
+      const RawClass* cls) {
+    return cls->ptr()->host_type_arguments_field_offset_in_words_;
+  }
+
+  static int32_t target_type_arguments_field_offset_in_words(
+      const RawClass* cls) {
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    return cls->ptr()->target_type_arguments_field_offset_in_words_;
+#else
+    return host_type_arguments_field_offset_in_words(cls);
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
+  }
+
  private:
   RawType* declaration_type() const { return raw_ptr()->declaration_type_; }
 
@@ -1474,7 +1609,7 @@
   // Tells whether instances need morphing for reload.
   bool RequiresInstanceMorphing(const Class& replacement) const;
 
-  template <class FakeObject>
+  template <class FakeInstance, class TargetFakeInstance>
   static RawClass* NewCommon(intptr_t index);
 
   enum MemberKind {
@@ -1538,7 +1673,8 @@
                                           const Array& args_desc,
                                           RawFunction::Kind kind) const;
 
-  void CalculateFieldOffsets() const;
+  // Returns the bitmap of unboxed fields
+  UnboxedFieldBitmap CalculateFieldOffsets() const;
 
   // functions_hash_table is in use iff there are at least this many functions.
   static const intptr_t kFunctionLookupHashTreshold = 16;
@@ -1576,7 +1712,7 @@
                                       const String& name) const;
 
   // Allocate an instance class which has a VM implementation.
-  template <class FakeInstance>
+  template <class FakeInstance, class TargetFakeInstance>
   static RawClass* New(intptr_t id,
                        Isolate* isolate,
                        bool register_class = true,
@@ -3643,15 +3779,19 @@
 
   intptr_t KernelDataProgramOffset() const;
 
-  inline intptr_t Offset() const;
   // Called during class finalization.
-  inline void SetOffset(intptr_t offset_in_bytes) const;
+  inline void SetOffset(intptr_t host_offset_in_bytes,
+                        intptr_t target_offset_in_bytes) const;
+
+  inline intptr_t HostOffset() const;
+
+  inline intptr_t TargetOffset() const;
 
   inline RawInstance* StaticValue() const;
   void SetStaticValue(const Instance& value,
                       bool save_initial_value = false) const;
 
-  intptr_t field_id() const { return raw_ptr()->offset_or_field_id_; }
+  intptr_t field_id() const { return raw_ptr()->host_offset_or_field_id_; }
   inline void set_field_id(intptr_t field_id) const;
 
 #ifndef DART_PRECOMPILED_RUNTIME
@@ -3748,6 +3888,14 @@
     return OFFSET_OF(RawField, static_type_exactness_state_);
   }
 
+  static inline intptr_t TargetOffsetOf(const RawField* field) {
+#if !defined(DART_PRECOMPILED_RUNTIME)
+    return field->ptr()->target_offset_;
+#else
+    return field->ptr()->host_offset_or_field_id_;
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
+  }
+
   // Return class id that any non-null value read from this field is guaranteed
   // to have or kDynamicCid if such class id is not known.
   // Stores to this field must update this information hence the name.
@@ -6554,7 +6702,7 @@
     const Class& cls = Class::Handle(clazz());
     ASSERT(cls.is_finalized() || cls.is_prefinalized());
 #endif
-    return (clazz()->ptr()->instance_size_in_words_ * kWordSize);
+    return (clazz()->ptr()->host_instance_size_in_words_ * kWordSize);
   }
 
   // Returns Instance::null() if instance cannot be canonicalized.
@@ -6576,7 +6724,7 @@
   virtual bool CheckIsCanonical(Thread* thread) const;
 #endif  // DEBUG
 
-  RawObject* GetField(const Field& field) const { return *FieldAddr(field); }
+  RawObject* GetField(const Field& field) const;
 
   void SetField(const Field& field, const Object& value) const;
 
@@ -6713,7 +6861,7 @@
     return reinterpret_cast<RawObject**>(raw_value() - kHeapObjectTag + offset);
   }
   RawObject** FieldAddr(const Field& field) const {
-    return FieldAddrAtOffset(field.Offset());
+    return FieldAddrAtOffset(field.HostOffset());
   }
   RawObject** NativeFieldsAddr() const {
     return FieldAddrAtOffset(sizeof(RawObject));
@@ -6736,7 +6884,8 @@
   }
 
   static RawInstance* NewFromCidAndSize(SharedClassTable* shared_class_table,
-                                        classid_t cid);
+                                        classid_t cid,
+                                        Heap::Space heap = Heap::kNew);
 
   // TODO(iposva): Determine if this gets in the way of Smi.
   HEAP_OBJECT_IMPLEMENTATION(Instance, Object);
@@ -10313,26 +10462,45 @@
 }
 #endif  // !defined(DART_PRECOMPILED_RUNTIME)
 
-intptr_t Field::Offset() const {
+intptr_t Field::HostOffset() const {
   ASSERT(is_instance());  // Valid only for dart instance fields.
-  return (raw_ptr()->offset_or_field_id_ * kWordSize);
+  return (raw_ptr()->host_offset_or_field_id_ * kWordSize);
 }
 
-void Field::SetOffset(intptr_t offset_in_bytes) const {
+intptr_t Field::TargetOffset() const {
+  ASSERT(is_instance());  // Valid only for dart instance fields.
+#if !defined(DART_PRECOMPILED_RUNTIME)
+  return (raw_ptr()->target_offset_ * compiler::target::kWordSize);
+#else
+  return HostOffset();
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
+}
+
+void Field::SetOffset(intptr_t host_offset_in_bytes,
+                      intptr_t target_offset_in_bytes) const {
   ASSERT(is_instance());  // Valid only for dart instance fields.
   ASSERT(kWordSize != 0);
-  StoreNonPointer(&raw_ptr()->offset_or_field_id_, offset_in_bytes / kWordSize);
+  StoreNonPointer(&raw_ptr()->host_offset_or_field_id_,
+                  host_offset_in_bytes / kWordSize);
+#if !defined(DART_PRECOMPILED_RUNTIME)
+  ASSERT(compiler::target::kWordSize != 0);
+  StoreNonPointer(&raw_ptr()->target_offset_,
+                  target_offset_in_bytes / compiler::target::kWordSize);
+#else
+  ASSERT(host_offset_in_bytes == target_offset_in_bytes);
+#endif  //  !defined(DART_PRECOMPILED_RUNTIME)
 }
 
 RawInstance* Field::StaticValue() const {
   ASSERT(is_static());  // Valid only for static dart fields.
-  return Isolate::Current()->field_table()->At(raw_ptr()->offset_or_field_id_);
+  return Isolate::Current()->field_table()->At(
+      raw_ptr()->host_offset_or_field_id_);
 }
 
 void Field::set_field_id(intptr_t field_id) const {
   ASSERT(is_static());
   ASSERT(Thread::Current()->IsMutatorThread());
-  StoreNonPointer(&raw_ptr()->offset_or_field_id_, field_id);
+  StoreNonPointer(&raw_ptr()->host_offset_or_field_id_, field_id);
 }
 
 #ifndef DART_PRECOMPILED_RUNTIME
diff --git a/runtime/vm/object_graph.cc b/runtime/vm/object_graph.cc
index 4b38e2d..98b112f 100644
--- a/runtime/vm/object_graph.cc
+++ b/runtime/vm/object_graph.cc
@@ -1097,7 +1097,7 @@
                 if (field.is_instance()) {
                   intptr_t flags = 1;  // Strong.
                   WriteUnsigned(flags);
-                  intptr_t index = field.Offset() / kWordSize - 1;
+                  intptr_t index = field.HostOffset() / kWordSize - 1;
                   ASSERT(index >= 0);
                   WriteUnsigned(index);
                   str = field.name();
diff --git a/runtime/vm/object_reload.cc b/runtime/vm/object_reload.cc
index afed744..e17bd7f 100644
--- a/runtime/vm/object_reload.cc
+++ b/runtime/vm/object_reload.cc
@@ -606,6 +606,18 @@
   RawString* ToString() { return String::New(error_.ToErrorCString()); }
 };
 
+class ConstToNonConstClass : public ClassReasonForCancelling {
+ public:
+  ConstToNonConstClass(Zone* zone, const Class& from, const Class& to)
+      : ClassReasonForCancelling(zone, from, to) {}
+
+ private:
+  RawString* ToString() {
+    return String::NewFormatted("Const class cannot become non-const: %s",
+                                from_.ToCString());
+  }
+};
+
 class NativeFieldsConflict : public ClassReasonForCancelling {
  public:
   NativeFieldsConflict(Zone* zone, const Class& from, const Class& to)
@@ -663,8 +675,8 @@
     return String::NewFormatted("Instance size mismatch between '%s' (%" Pd
                                 ") and replacement "
                                 "'%s' ( %" Pd ")",
-                                from_.ToCString(), from_.instance_size(),
-                                to_.ToCString(), to_.instance_size());
+                                from_.ToCString(), from_.host_instance_size(),
+                                to_.ToCString(), to_.host_instance_size());
   }
 };
 
@@ -712,6 +724,14 @@
     TIR_Print("Finalized replacement class for %s\n", ToCString());
   }
 
+  if (is_finalized() && is_const() && !replacement.is_const()) {
+    if (constants() != Array::null() && Array::LengthOf(constants()) > 0) {
+      context->group_reload_context()->AddReasonForCancelling(
+          new (context->zone())
+              ConstToNonConstClass(context->zone(), *this, replacement));
+    }
+  }
+
   // Native field count cannot change.
   if (num_native_fields() != replacement.num_native_fields()) {
     context->group_reload_context()->AddReasonForCancelling(
@@ -748,7 +768,9 @@
   // Check that we have the same next field offset. This check is not
   // redundant with the one above because the instance OffsetToFieldMap
   // array length is based on the instance size (which may be aligned up).
-  if (next_field_offset() != replacement.next_field_offset()) return true;
+  if (host_next_field_offset() != replacement.host_next_field_offset()) {
+    return true;
+  }
 
   // Verify that field names / offsets match across the entire hierarchy.
   Field& field = Field::Handle();
@@ -805,7 +827,7 @@
     return false;
   }
   // Check the instance sizes are equal.
-  if (instance_size() != replacement.instance_size()) {
+  if (host_instance_size() != replacement.host_instance_size()) {
     context->group_reload_context()->AddReasonForCancelling(
         new (context->zone())
             InstanceSizeConflict(context->zone(), *this, replacement));
diff --git a/runtime/vm/object_test.cc b/runtime/vm/object_test.cc
index e16b264..a1359fe 100644
--- a/runtime/vm/object_test.cc
+++ b/runtime/vm/object_test.cc
@@ -217,7 +217,7 @@
   ClassFinalizer::FinalizeTypesInClass(empty_class);
   empty_class.Finalize();
 
-  EXPECT_EQ(kObjectAlignment, empty_class.instance_size());
+  EXPECT_EQ(kObjectAlignment, empty_class.host_instance_size());
   Instance& instance = Instance::Handle(Instance::New(empty_class));
   EXPECT_EQ(empty_class.raw(), instance.clazz());
 
@@ -242,8 +242,8 @@
   one_field_class.Finalize();
   intptr_t header_size = sizeof(RawObject);
   EXPECT_EQ(Utils::RoundUp((header_size + (1 * kWordSize)), kObjectAlignment),
-            one_field_class.instance_size());
-  EXPECT_EQ(header_size, field.Offset());
+            one_field_class.host_instance_size());
+  EXPECT_EQ(header_size, field.HostOffset());
   EXPECT(!one_field_class.is_implemented());
   one_field_class.set_is_implemented();
   EXPECT(one_field_class.is_implemented());
diff --git a/runtime/vm/os_fuchsia.cc b/runtime/vm/os_fuchsia.cc
index d65e9fb..05985ab 100644
--- a/runtime/vm/os_fuchsia.cc
+++ b/runtime/vm/os_fuchsia.cc
@@ -11,18 +11,14 @@
 #include <fcntl.h>
 #include <stdint.h>
 
-#include <fuchsia/intl/cpp/fidl.h>
+#include <fuchsia/deprecatedtimezone/cpp/fidl.h>
 #include <lib/sys/cpp/service_directory.h>
 #include <zircon/process.h>
 #include <zircon/syscalls.h>
 #include <zircon/syscalls/object.h>
 #include <zircon/types.h>
 
-#include "third_party/icu/source/common/unicode/errorcode.h"
-#include "third_party/icu/source/i18n/unicode/timezone.h"
-
 #include "platform/assert.h"
-#include "platform/syslog.h"
 #include "vm/zone.h"
 
 namespace dart {
@@ -65,72 +61,33 @@
   return static_cast<intptr_t>(getpid());
 }
 
-// This is the default timezone returned if it could not be obtained.  For
-// Fuchsia, the default device timezone is always UTC.
-static const char kDefaultTimezone[] = "UTC";
-
 // TODO(FL-98): Change this to talk to fuchsia.dart to get timezone service to
 // directly get timezone.
 //
 // Putting this hack right now due to CP-120 as I need to remove
 // component:ConnectToEnvironmentServices and this is the only thing that is
 // blocking it and FL-98 will take time.
-static fuchsia::intl::PropertyProviderSyncPtr property_provider;
-
-// 1000 milliseconds do one second make.
-static const int32_t kMSPerSec = 1000;
+static fuchsia::deprecatedtimezone::TimezoneSyncPtr tz;
 
 static zx_status_t GetLocalAndDstOffsetInSeconds(int64_t seconds_since_epoch,
                                                  int32_t* local_offset,
                                                  int32_t* dst_offset) {
-  const char* timezone_id = OS::GetTimeZoneName(seconds_since_epoch);
-  std::unique_ptr<icu::TimeZone> timezone(
-      icu::TimeZone::createTimeZone(timezone_id));
-  UErrorCode error = U_ZERO_ERROR;
-  const auto ms_since_epoch =
-      static_cast<UDate>(kMSPerSec * seconds_since_epoch);
-  // The units of time that local_offset and dst_offset are returned from this
-  // function is, usefully, not documented, but it seems that the units are
-  // milliseconds.  Add these variables here for clarity.
-  int32_t local_offset_ms = 0;
-  int32_t dst_offset_ms = 0;
-  timezone->getOffset(ms_since_epoch, /*local_time=*/false, local_offset_ms,
-                      dst_offset_ms, error);
-  if (error != U_ZERO_ERROR) {
-    icu::ErrorCode icu_error;
-    icu_error.set(error);
-    // Sadly there is no way to report the actual error.  Next best thing is to
-    // log.  On the upside, a direct call to timezone->getOffset should fail
-    // rarely, so this should not amount to log spam.
-    Syslog::PrintErr("could not get DST offset: %s\n", icu_error.errorName());
-    return ZX_ERR_INTERNAL;
+  zx_status_t status = tz->GetTimezoneOffsetMinutes(seconds_since_epoch * 1000,
+                                                    local_offset, dst_offset);
+  if (status != ZX_OK) {
+    return status;
   }
-  // We must return offset in seconds, so convert.
-  *local_offset = local_offset_ms / kMSPerSec;
-  *dst_offset = dst_offset_ms / kMSPerSec;
+  *local_offset *= 60;
+  *dst_offset *= 60;
   return ZX_OK;
 }
 
 const char* OS::GetTimeZoneName(int64_t seconds_since_epoch) {
   // TODO(abarth): Handle time zone changes.
-  static const std::string* tz_name = new std::string([]() -> std::string {
-    fuchsia::intl::Profile profile;
-    zx_status_t status = property_provider->GetProfile(&profile);
-    if (status != ZX_OK) {
-      // Shrug.  Let's continue with UTC.  Printing the error here as there is
-      // no way to report it from this API.
-      Syslog::PrintErr("no intl profile available\n");
-      return kDefaultTimezone;
-    }
-    const std::vector<fuchsia::intl::TimeZoneId>& timezones =
-        profile.time_zones();
-    if (timezones.empty()) {
-      // Empty timezone array is not up to fuchsia::intl spec.  The serving
-      // endpoint is broken and should be fixed.
-      Syslog::PrintErr("got empty timezone value\n");
-      return kDefaultTimezone;
-    }
-    return timezones[0].id;
+  static const auto* tz_name = new std::string([] {
+    std::string result;
+    tz->GetTimezoneId(&result);
+    return result;
   }());
   return tz_name->c_str();
 }
@@ -308,7 +265,7 @@
 void OS::Init() {
   InitializeTZData();
   auto services = sys::ServiceDirectory::CreateFromNamespace();
-  services->Connect(property_provider.NewRequest());
+  services->Connect(tz.NewRequest());
 }
 
 void OS::Cleanup() {}
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index a86665c..3aaf191 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -1144,6 +1144,17 @@
   OS::PrintErr(
       "version=%s\nthread=%" Pd ", isolate=%s(%p)\n", Version::String(),
       OSThread::ThreadIdToIntPtr(os_thread->trace_id()), name, isolate);
+  const IsolateGroupSource* source =
+      isolate == nullptr ? nullptr : isolate->source();
+  const IsolateGroupSource* vm_source =
+      Dart::vm_isolate() == nullptr ? nullptr : Dart::vm_isolate()->source();
+  OS::PrintErr("isolate_instructions=%" Px ", vm_instructions=%" Px "\n",
+               source == nullptr
+                   ? 0
+                   : reinterpret_cast<uword>(source->snapshot_instructions),
+               vm_source == nullptr
+                   ? 0
+                   : reinterpret_cast<uword>(vm_source->snapshot_instructions));
 
   if (!InitialRegisterCheck(pc, fp, sp)) {
     OS::PrintErr("Stack dump aborted because InitialRegisterCheck failed.\n");
diff --git a/runtime/vm/raw_object.cc b/runtime/vm/raw_object.cc
index 8ff35b9..f858f65 100644
--- a/runtime/vm/raw_object.cc
+++ b/runtime/vm/raw_object.cc
@@ -377,14 +377,32 @@
   uword next_field_offset = visitor->isolate()
                                 ->GetClassForHeapWalkAt(class_id)
                                 ->ptr()
-                                ->next_field_offset_in_words_
+                                ->host_next_field_offset_in_words_
                             << kWordSizeLog2;
   ASSERT(next_field_offset > 0);
   uword obj_addr = RawObject::ToAddr(this);
   uword from = obj_addr + sizeof(RawObject);
   uword to = obj_addr + next_field_offset - kWordSize;
-  visitor->VisitPointers(reinterpret_cast<RawObject**>(from),
-                         reinterpret_cast<RawObject**>(to));
+  const auto first = reinterpret_cast<RawObject**>(from);
+  const auto last = reinterpret_cast<RawObject**>(to);
+
+#if defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
+  const auto unboxed_fields_bitmap =
+      visitor->shared_class_table()->GetUnboxedFieldsMapAt(class_id);
+
+  if (!unboxed_fields_bitmap.IsEmpty()) {
+    intptr_t bit = sizeof(RawObject) / kWordSize;
+    for (RawObject** current = first; current <= last; current++) {
+      if (!unboxed_fields_bitmap.Get(bit++)) {
+        visitor->VisitPointer(current);
+      }
+    }
+  } else {
+    visitor->VisitPointers(first, last);
+  }
+#else
+  visitor->VisitPointers(first, last);
+#endif  // defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
 }
 
 bool RawObject::FindObject(FindObjectVisitor* visitor) {
diff --git a/runtime/vm/raw_object.h b/runtime/vm/raw_object.h
index acfaf53..da82750 100644
--- a/runtime/vm/raw_object.h
+++ b/runtime/vm/raw_object.h
@@ -474,10 +474,27 @@
     uword obj_addr = ToAddr(this);
     uword from = obj_addr + sizeof(RawObject);
     uword to = obj_addr + instance_size - kWordSize;
+    const auto first = reinterpret_cast<RawObject**>(from);
+    const auto last = reinterpret_cast<RawObject**>(to);
 
+#if defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
+    const auto unboxed_fields_bitmap =
+        visitor->shared_class_table()->GetUnboxedFieldsMapAt(class_id);
+
+    if (!unboxed_fields_bitmap.IsEmpty()) {
+      intptr_t bit = sizeof(RawObject) / kWordSize;
+      for (RawObject** current = first; current <= last; current++) {
+        if (!unboxed_fields_bitmap.Get(bit++)) {
+          visitor->VisitPointer(current);
+        }
+      }
+    } else {
+      visitor->VisitPointers(first, last);
+    }
+#else
     // Call visitor function virtually
-    visitor->VisitPointers(reinterpret_cast<RawObject**>(from),
-                           reinterpret_cast<RawObject**>(to));
+    visitor->VisitPointers(first, last);
+#endif  // defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
 
     return instance_size;
   }
@@ -495,10 +512,27 @@
     uword obj_addr = ToAddr(this);
     uword from = obj_addr + sizeof(RawObject);
     uword to = obj_addr + instance_size - kWordSize;
+    const auto first = reinterpret_cast<RawObject**>(from);
+    const auto last = reinterpret_cast<RawObject**>(to);
 
+#if defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
+    const auto unboxed_fields_bitmap =
+        visitor->shared_class_table()->GetUnboxedFieldsMapAt(class_id);
+
+    if (!unboxed_fields_bitmap.IsEmpty()) {
+      intptr_t bit = sizeof(RawObject) / kWordSize;
+      for (RawObject** current = first; current <= last; current++) {
+        if (!unboxed_fields_bitmap.Get(bit++)) {
+          visitor->V::VisitPointers(current, current);
+        }
+      }
+    } else {
+      visitor->V::VisitPointers(first, last);
+    }
+#else
     // Call visitor function non-virtually
-    visitor->V::VisitPointers(reinterpret_cast<RawObject**>(from),
-                              reinterpret_cast<RawObject**>(to));
+    visitor->V::VisitPointers(first, last);
+#endif  // defined(SUPPORT_UNBOXED_INSTANCE_FIELDS)
 
     return instance_size;
   }
@@ -814,14 +848,32 @@
 
   TokenPosition token_pos_;
   TokenPosition end_token_pos_;
-  int32_t instance_size_in_words_;  // Size if fixed len or 0 if variable len.
-  int32_t type_arguments_field_offset_in_words_;  // Offset of type args fld.
-  int32_t next_field_offset_in_words_;  // Offset of the next instance field.
+
   classid_t id_;                // Class Id, also index in the class table.
   int16_t num_type_arguments_;  // Number of type arguments in flattened vector.
   uint16_t num_native_fields_;
   uint32_t state_bits_;
 
+  // Size if fixed len or 0 if variable len.
+  int32_t host_instance_size_in_words_;
+
+  // Offset of type args fld.
+  int32_t host_type_arguments_field_offset_in_words_;
+
+  // Offset of the next instance field.
+  int32_t host_next_field_offset_in_words_;
+
+#if !defined(DART_PRECOMPILED_RUNTIME)
+  // Size if fixed len or 0 if variable len (target).
+  int32_t target_instance_size_in_words_;
+
+  // Offset of type args fld.
+  int32_t target_type_arguments_field_offset_in_words_;
+
+  // Offset of the next instance field (target).
+  int32_t target_next_field_offset_in_words_;
+#endif  // !defined(DART_PRECOMPILED_RUNTIME)
+
 #if !defined(DART_PRECOMPILED_RUNTIME)
   typedef BitField<uint32_t, bool, 0, 1> IsDeclaredInBytecode;
   typedef BitField<uint32_t, uint32_t, 1, 31> BinaryDeclarationOffset;
@@ -1177,11 +1229,16 @@
   // field.
   int8_t static_type_exactness_state_;
 
+  uint16_t kind_bits_;  // static, final, const, has initializer....
+
   // - for instance fields: offset in words to the value in the class instance.
   // - for static fields: index into field_table.
-  intptr_t offset_or_field_id_;
+  intptr_t host_offset_or_field_id_;
 
-  uint16_t kind_bits_;  // static, final, const, has initializer....
+#if !defined(DART_PRECOMPILED_RUNTIME)
+  // for instance fields, the offset in words in the target architecture
+  int32_t target_offset_;
+#endif  // !defined(DART_PRECOMPILED_RUNTIME)
 
   friend class CidRewriteVisitor;
 };
@@ -1429,7 +1486,7 @@
 #endif
 
   // Compilation timestamp.
-  NOT_IN_PRODUCT(int64_t compile_timestamp_);
+  NOT_IN_PRODUCT(alignas(8) int64_t compile_timestamp_);
 
   // state_bits_ is a bitfield with three fields:
   // The optimized bit, the alive bit, and a count of the number of pointer
@@ -2258,6 +2315,7 @@
 
   friend class Api;
   friend class SnapshotReader;
+  friend class Class;
 };
 COMPILE_ASSERT(sizeof(RawDouble) == 16);
 
@@ -2528,6 +2586,7 @@
   ALIGN8 float value_[4];
 
   friend class SnapshotReader;
+  friend class Class;
 
  public:
   float x() const { return value_[0]; }
@@ -2560,6 +2619,7 @@
   ALIGN8 double value_[2];
 
   friend class SnapshotReader;
+  friend class Class;
 
  public:
   double x() const { return value_[0]; }
diff --git a/runtime/vm/raw_object_snapshot.cc b/runtime/vm/raw_object_snapshot.cc
index a2a129e..31e4ed5 100644
--- a/runtime/vm/raw_object_snapshot.cc
+++ b/runtime/vm/raw_object_snapshot.cc
@@ -121,6 +121,13 @@
                       bool as_reference) {
   ASSERT(writer != NULL);
 
+  if (ptr()->signature_ != Function::null()) {
+    writer->SetWriteException(Exceptions::kArgument,
+                              "Illegal argument in isolate message"
+                              " : (function types are not supported yet)");
+    UNREACHABLE();
+  }
+
   // Only resolved and finalized types should be written to a snapshot.
   ASSERT((ptr()->type_state_ == RawType::kFinalizedInstantiated) ||
          (ptr()->type_state_ == RawType::kFinalizedUninstantiated));
diff --git a/runtime/vm/snapshot.cc b/runtime/vm/snapshot.cc
index 75e507c..cc04a43 100644
--- a/runtime/vm/snapshot.cc
+++ b/runtime/vm/snapshot.cc
@@ -593,47 +593,59 @@
     ASSERT(!cls_.IsNull());
     // Closure instances are handled by Closure::ReadFrom().
     ASSERT(!cls_.IsClosureClass());
-    instance_size = cls_.instance_size();
+    instance_size = cls_.host_instance_size();
     ASSERT(instance_size > 0);
     // Allocate the instance and read in all the fields for the object.
     *result ^= Object::Allocate(cls_.id(), instance_size, Heap::kNew);
   } else {
     cls_ ^= ReadObjectImpl(kAsInlinedObject);
     ASSERT(!cls_.IsNull());
-    instance_size = cls_.instance_size();
+    instance_size = cls_.host_instance_size();
   }
   if (cls_.id() == set_class_.id()) {
     EnqueueRehashingOfSet(*result);
   }
   if (!as_reference) {
     // Read all the individual fields for inlined objects.
-    intptr_t next_field_offset = cls_.next_field_offset();
+    intptr_t next_field_offset = cls_.host_next_field_offset();
 
-    intptr_t type_argument_field_offset = cls_.type_arguments_field_offset();
+    intptr_t type_argument_field_offset =
+        cls_.host_type_arguments_field_offset();
     ASSERT(next_field_offset > 0);
     // Instance::NextFieldOffset() returns the offset of the first field in
     // a Dart object.
     bool read_as_reference = RawObject::IsCanonical(tags) ? false : true;
     intptr_t offset = Instance::NextFieldOffset();
     intptr_t result_cid = result->GetClassId();
+
+    const auto unboxed_fields =
+        isolate()->shared_class_table()->GetUnboxedFieldsMapAt(result_cid);
+
     while (offset < next_field_offset) {
-      pobj_ = ReadObjectImpl(read_as_reference);
-      result->SetFieldAtOffset(offset, pobj_);
-      if ((offset != type_argument_field_offset) &&
-          (kind_ == Snapshot::kMessage) && isolate()->use_field_guards()) {
-        // TODO(fschneider): Consider hoisting these lookups out of the loop.
-        // This would involve creating a handle, since cls_ can't be reused
-        // across the call to ReadObjectImpl.
-        cls_ = isolate()->class_table()->At(result_cid);
-        array_ = cls_.OffsetToFieldMap();
-        field_ ^= array_.At(offset >> kWordSizeLog2);
-        ASSERT(!field_.IsNull());
-        ASSERT(field_.Offset() == offset);
-        obj_ = pobj_.raw();
-        field_.RecordStore(obj_);
+      if (unboxed_fields.Get(offset / kWordSize)) {
+        uword* p = reinterpret_cast<uword*>(result->raw_value() -
+                                            kHeapObjectTag + offset);
+        // Reads 32 bits of the unboxed value at a time
+        *p = ReadWordWith32BitReads();
+      } else {
+        pobj_ = ReadObjectImpl(read_as_reference);
+        result->SetFieldAtOffset(offset, pobj_);
+        if ((offset != type_argument_field_offset) &&
+            (kind_ == Snapshot::kMessage) && isolate()->use_field_guards()) {
+          // TODO(fschneider): Consider hoisting these lookups out of the loop.
+          // This would involve creating a handle, since cls_ can't be reused
+          // across the call to ReadObjectImpl.
+          cls_ = isolate()->class_table()->At(result_cid);
+          array_ = cls_.OffsetToFieldMap();
+          field_ ^= array_.At(offset >> kWordSizeLog2);
+          ASSERT(!field_.IsNull());
+          ASSERT(field_.HostOffset() == offset);
+          obj_ = pobj_.raw();
+          field_.RecordStore(obj_);
+        }
+        // TODO(fschneider): Verify the guarded cid and length for other kinds
+        // of snapshot (kFull, kScript) with asserts.
       }
-      // TODO(fschneider): Verify the guarded cid and length for other kinds of
-      // snapshot (kFull, kScript) with asserts.
       offset += kWordSize;
     }
     if (RawObject::IsCanonical(tags)) {
@@ -1439,7 +1451,7 @@
     // Write out the class information for this object.
     WriteObjectImpl(cls, kAsInlinedObject);
   } else {
-    intptr_t next_field_offset = cls->ptr()->next_field_offset_in_words_
+    intptr_t next_field_offset = Class::host_next_field_offset_in_words(cls)
                                  << kWordSizeLog2;
     ASSERT(next_field_offset > 0);
 
@@ -1455,15 +1467,26 @@
     // Write out the class information for this object.
     WriteObjectImpl(cls, kAsInlinedObject);
 
+    const auto unboxed_fields =
+        isolate()->shared_class_table()->GetUnboxedFieldsMapAt(cls->ptr()->id_);
+
     // Write out all the fields for the object.
     // Instance::NextFieldOffset() returns the offset of the first field in
     // a Dart object.
     bool write_as_reference = RawObject::IsCanonical(tags) ? false : true;
+
     intptr_t offset = Instance::NextFieldOffset();
     while (offset < next_field_offset) {
-      RawObject* raw_obj = *reinterpret_cast<RawObject**>(
-          reinterpret_cast<uword>(raw->ptr()) + offset);
-      WriteObjectImpl(raw_obj, write_as_reference);
+      if (unboxed_fields.Get(offset / kWordSize)) {
+        // Writes 32 bits of the unboxed value at a time
+        const uword value = *reinterpret_cast<uword*>(
+            reinterpret_cast<uword>(raw->ptr()) + offset);
+        WriteWordWith32BitWrites(value);
+      } else {
+        RawObject* raw_obj = *reinterpret_cast<RawObject**>(
+            reinterpret_cast<uword>(raw->ptr()) + offset);
+        WriteObjectImpl(raw_obj, write_as_reference);
+      }
       offset += kWordSize;
     }
   }
diff --git a/runtime/vm/snapshot.h b/runtime/vm/snapshot.h
index 1242943..3c528e8 100644
--- a/runtime/vm/snapshot.h
+++ b/runtime/vm/snapshot.h
@@ -272,6 +272,8 @@
     return SerializedHeaderData::decode(value);
   }
 
+  uword ReadWordWith32BitReads() { return stream_.ReadWordWith32BitReads(); }
+
  private:
   ReadStream stream_;  // input stream.
 };
@@ -529,6 +531,10 @@
     stream_.WriteBytes(reinterpret_cast<const uint8_t*>(&value), sizeof(value));
   }
 
+  void WriteWordWith32BitWrites(uword value) {
+    stream_.WriteWordWith32BitWrites(value);
+  }
+
  protected:
   BaseWriter(ReAlloc alloc, DeAlloc dealloc, intptr_t initial_size)
       : StackResource(Thread::Current()),
diff --git a/runtime/vm/stack_frame.h b/runtime/vm/stack_frame.h
index 72699ae..00ed7c91 100644
--- a/runtime/vm/stack_frame.h
+++ b/runtime/vm/stack_frame.h
@@ -132,6 +132,12 @@
 
   static void DumpCurrentTrace();
 
+  uword GetCallerSp() const {
+    return fp() +
+           ((is_interpreted() ? kKBCCallerSpSlotFromFp : kCallerSpSlotFromFp) *
+            kWordSize);
+  }
+
  protected:
   explicit StackFrame(Thread* thread)
       : fp_(0), sp_(0), pc_(0), thread_(thread), is_interpreted_(false) {}
@@ -151,11 +157,6 @@
   RawCode* GetCodeObject() const;
   RawBytecode* GetBytecodeObject() const;
 
-  uword GetCallerSp() const {
-    return fp() +
-           ((is_interpreted() ? kKBCCallerSpSlotFromFp : kCallerSpSlotFromFp) *
-            kWordSize);
-  }
 
   uword GetCallerFp() const {
     return *(reinterpret_cast<uword*>(
diff --git a/runtime/vm/stack_trace.cc b/runtime/vm/stack_trace.cc
index 7ea29a1..837817b 100644
--- a/runtime/vm/stack_trace.cc
+++ b/runtime/vm/stack_trace.cc
@@ -73,6 +73,9 @@
   if (yield_index == RawPcDescriptors::kInvalidYieldIndex) {
     return 0;
   }
+  if (!bytecode.HasSourcePositions()) {
+    return 0;
+  }
   intptr_t last_yield_point = 0;
   kernel::BytecodeSourcePositionsIterator iter(Thread::Current()->zone(),
                                                bytecode);
@@ -373,10 +376,9 @@
   CallerClosureFinder caller_closure_finder(zone);
   auto& pc_descs = PcDescriptors::Handle();
 
-  while (frame != nullptr) {
+  for (; frame != nullptr; frame = frames.NextFrame()) {
     if (skip_frames > 0) {
       skip_frames--;
-      frame = frames.NextFrame();
       continue;
     }
 
@@ -385,7 +387,6 @@
       ASSERT(!bytecode.IsNull());
       function = bytecode.function();
       if (function.IsNull()) {
-        frame = frames.NextFrame();
         continue;
       }
       RELEASE_ASSERT(function.raw() == frame->LookupDartFunction());
@@ -419,15 +420,14 @@
 
       // Next, look up caller's closure on the stack and walk backwards through
       // the yields.
-      frame = frames.NextFrame();
-      RawObject** last_caller_obj = reinterpret_cast<RawObject**>(frame->sp());
+      RawObject** last_caller_obj = reinterpret_cast<RawObject**>(
+          frame->GetCallerSp());
       closure = FindClosureInFrame(last_caller_obj, function,
                                    frame->is_interpreted());
 
       // If this async function hasn't yielded yet, we're still dealing with a
       // normal stack. Continue to next frame as usual.
       if (!caller_closure_finder.IsRunningAsync(closure)) {
-        // Don't advance frame since we already did so just above.
         continue;
       }
 
@@ -474,8 +474,6 @@
       // Ignore the rest of the stack; already unwound all async calls.
       return;
     }
-
-    frame = frames.NextFrame();
   }
 
   return;
diff --git a/runtime/vm/type_testing_stubs.cc b/runtime/vm/type_testing_stubs.cc
index c50bd59..6a69df1 100644
--- a/runtime/vm/type_testing_stubs.cc
+++ b/runtime/vm/type_testing_stubs.cc
@@ -111,7 +111,9 @@
   }
 
   if (type.IsType() || type.IsTypeParameter()) {
-    const bool should_specialize = !FLAG_precompiled_mode && lazy_specialize;
+    // TODO(dartbug.com/39755): Add support for specialized NNBD TTS.
+    const bool should_specialize =
+        !FLAG_precompiled_mode && lazy_specialize && type.IsNullable();
     return should_specialize ? StubCode::LazySpecializeTypeTest().raw()
                              : StubCode::DefaultTypeTest().raw();
   }
diff --git a/runtime/vm/unit_test.cc b/runtime/vm/unit_test.cc
index d5ec265..f23e5ee 100644
--- a/runtime/vm/unit_test.cc
+++ b/runtime/vm/unit_test.cc
@@ -199,13 +199,49 @@
 
 #ifndef PRODUCT
 static const char* kIsolateReloadTestLibSource =
-    "void reloadTest() native 'Reload_Test';\n";
+    "void reloadTest() native 'Test_Reload';\n"
+    "void collectNewSpace() native 'Test_CollectNewSpace';\n"
+    "void collectOldSpace() native 'Test_CollectOldSpace';\n";
 
 static const char* IsolateReloadTestLibUri() {
   return "test:isolate_reload_helper";
 }
 
-static void ReloadTest(Dart_NativeArguments native_args) {
+#define RELOAD_NATIVE_LIST(V)                                                  \
+  V(Test_Reload, 0)                                                            \
+  V(Test_CollectNewSpace, 0)                                                   \
+  V(Test_CollectOldSpace, 0)
+
+RELOAD_NATIVE_LIST(DECLARE_FUNCTION);
+
+static struct NativeEntries {
+  const char* name_;
+  Dart_NativeFunction function_;
+  int argument_count_;
+} ReloadEntries[] = {RELOAD_NATIVE_LIST(REGISTER_FUNCTION)};
+
+static Dart_NativeFunction IsolateReloadTestNativeResolver(
+    Dart_Handle name,
+    int argument_count,
+    bool* auto_setup_scope) {
+  const char* function_name = NULL;
+  Dart_Handle result = Dart_StringToCString(name, &function_name);
+  ASSERT(!Dart_IsError(result));
+  ASSERT(function_name != NULL);
+  ASSERT(auto_setup_scope != NULL);
+  *auto_setup_scope = true;
+  int num_entries = sizeof(ReloadEntries) / sizeof(struct NativeEntries);
+  for (int i = 0; i < num_entries; i++) {
+    struct NativeEntries* entry = &(ReloadEntries[i]);
+    if ((strcmp(function_name, entry->name_) == 0) &&
+        (entry->argument_count_ == argument_count)) {
+      return reinterpret_cast<Dart_NativeFunction>(entry->function_);
+    }
+  }
+  return NULL;
+}
+
+void FUNCTION_NAME(Test_Reload)(Dart_NativeArguments native_args) {
   Dart_Handle result = TestCase::TriggerReload(/* kernel_buffer= */ NULL,
                                                /* kernel_buffer_size= */ 0);
   if (Dart_IsError(result)) {
@@ -213,11 +249,14 @@
   }
 }
 
-static Dart_NativeFunction IsolateReloadTestNativeResolver(
-    Dart_Handle name,
-    int num_of_arguments,
-    bool* auto_setup_scope) {
-  return ReloadTest;
+void FUNCTION_NAME(Test_CollectNewSpace)(Dart_NativeArguments native_args) {
+  TransitionNativeToVM transition(Thread::Current());
+  GCTestHelper::CollectNewSpace();
+}
+
+void FUNCTION_NAME(Test_CollectOldSpace)(Dart_NativeArguments native_args) {
+  TransitionNativeToVM transition(Thread::Current());
+  GCTestHelper::CollectOldSpace();
 }
 
 static Dart_Handle LoadIsolateReloadTestLib() {
diff --git a/runtime/vm/visitor.cc b/runtime/vm/visitor.cc
new file mode 100644
index 0000000..0fd28d4
--- /dev/null
+++ b/runtime/vm/visitor.cc
@@ -0,0 +1,16 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "vm/visitor.h"
+
+#include "vm/isolate.h"
+
+namespace dart {
+
+ObjectPointerVisitor::ObjectPointerVisitor(Isolate* isolate)
+    : isolate_(isolate),
+      gc_root_type_("unknown"),
+      shared_class_table_(isolate->shared_class_table()) {}
+
+}  // namespace dart
diff --git a/runtime/vm/visitor.h b/runtime/vm/visitor.h
index cd0e967..9d5bf75 100644
--- a/runtime/vm/visitor.h
+++ b/runtime/vm/visitor.h
@@ -6,6 +6,7 @@
 #define RUNTIME_VM_VISITOR_H_
 
 #include "vm/allocation.h"
+#include "vm/class_table.h"
 #include "vm/globals.h"
 #include "vm/growable_array.h"
 
@@ -20,8 +21,7 @@
 // An object pointer visitor interface.
 class ObjectPointerVisitor {
  public:
-  explicit ObjectPointerVisitor(Isolate* isolate)
-      : isolate_(isolate), gc_root_type_("unknown") {}
+  explicit ObjectPointerVisitor(Isolate* isolate);
   virtual ~ObjectPointerVisitor() {}
 
   Isolate* isolate() const { return isolate_; }
@@ -54,9 +54,14 @@
 
   virtual bool visit_weak_persistent_handles() const { return false; }
 
+  const SharedClassTable* shared_class_table() const {
+    return shared_class_table_;
+  }
+
  private:
   Isolate* isolate_;
   const char* gc_root_type_;
+  SharedClassTable* shared_class_table_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(ObjectPointerVisitor);
 };
diff --git a/runtime/vm/vm_sources.gni b/runtime/vm/vm_sources.gni
index 9c5f727..b7d3f4e 100644
--- a/runtime/vm/vm_sources.gni
+++ b/runtime/vm/vm_sources.gni
@@ -357,6 +357,7 @@
   "virtual_memory_fuchsia.cc",
   "virtual_memory_posix.cc",
   "virtual_memory_win.cc",
+  "visitor.cc",
   "visitor.h",
   "zone.cc",
   "zone.h",
diff --git a/sdk/lib/_http/http_parser.dart b/sdk/lib/_http/http_parser.dart
index 8d64a50..e5772e0 100644
--- a/sdk/lib/_http/http_parser.dart
+++ b/sdk/lib/_http/http_parser.dart
@@ -246,7 +246,7 @@
   int _statusCode = 0;
   int _statusCodeLength = 0;
   final List<int> _method = [];
-  final List<int> _uri_or_reason_phrase = [];
+  final List<int> _uriOrReasonPhrase = [];
   final List<int> _headerField = [];
   final List<int> _headerValue = [];
 
@@ -319,8 +319,13 @@
     try {
       _doParse();
     } catch (e, s) {
-      _state = _State.FAILURE;
-      _reportError(e, s);
+      if (_state >= _State.CHUNK_SIZE_STARTING_CR && _state <= _State.BODY) {
+        _state = _State.FAILURE;
+        _reportBodyError(e, s);
+      } else {
+        _state = _State.FAILURE;
+        _reportHttpError(e, s);
+      }
     }
   }
 
@@ -350,14 +355,13 @@
     _createIncoming(_transferLength);
     if (_requestParser) {
       _incoming.method = new String.fromCharCodes(_method);
-      _incoming.uri =
-          Uri.parse(new String.fromCharCodes(_uri_or_reason_phrase));
+      _incoming.uri = Uri.parse(new String.fromCharCodes(_uriOrReasonPhrase));
     } else {
       _incoming.statusCode = _statusCode;
-      _incoming.reasonPhrase = new String.fromCharCodes(_uri_or_reason_phrase);
+      _incoming.reasonPhrase = new String.fromCharCodes(_uriOrReasonPhrase);
     }
     _method.clear();
-    _uri_or_reason_phrase.clear();
+    _uriOrReasonPhrase.clear();
     if (_connectionUpgrade) {
       _incoming.upgraded = true;
       _parserCalled = false;
@@ -510,7 +514,7 @@
 
         case _State.REQUEST_LINE_URI:
           if (byte == _CharCode.SP) {
-            if (_uri_or_reason_phrase.length == 0) {
+            if (_uriOrReasonPhrase.length == 0) {
               throw new HttpException("Invalid request URI");
             }
             _state = _State.REQUEST_LINE_HTTP_VERSION;
@@ -519,7 +523,7 @@
             if (byte == _CharCode.CR || byte == _CharCode.LF) {
               throw new HttpException("Invalid request URI");
             }
-            _uri_or_reason_phrase.add(byte);
+            _uriOrReasonPhrase.add(byte);
           }
           break;
 
@@ -567,7 +571,7 @@
             _state = _State.RESPONSE_LINE_ENDING;
           } else {
             _statusCodeLength++;
-            if ((byte < 0x30 && 0x39 < byte) || _statusCodeLength > 3) {
+            if (byte < 0x30 || byte > 0x39 || _statusCodeLength > 3) {
               throw new HttpException("Invalid response status code");
             } else {
               _statusCode = _statusCode * 10 + byte - 0x30;
@@ -582,7 +586,7 @@
             if (byte == _CharCode.CR || byte == _CharCode.LF) {
               throw new HttpException("Invalid response reason phrase");
             }
-            _uri_or_reason_phrase.add(byte);
+            _uriOrReasonPhrase.add(byte);
           }
           break;
 
@@ -821,8 +825,8 @@
       if (_state != _State.UPGRADED &&
           !(_state == _State.START && !_requestParser) &&
           !(_state == _State.BODY && !_chunked && _transferLength == -1)) {
-        _bodyController.addError(
-            new HttpException("Connection closed while receiving data"));
+        _reportBodyError(
+            HttpException("Connection closed while receiving data"));
       }
       _closeIncoming(true);
       _controller.close();
@@ -831,8 +835,8 @@
     // If the connection is idle the HTTP stream is closed.
     if (_state == _State.START) {
       if (!_requestParser) {
-        _reportError(new HttpException(
-            "Connection closed before full header was received"));
+        _reportHttpError(
+            HttpException("Connection closed before full header was received"));
       }
       _controller.close();
       return;
@@ -847,8 +851,8 @@
       _state = _State.FAILURE;
       // Report the error through the error callback if any. Otherwise
       // throw the error.
-      _reportError(new HttpException(
-          "Connection closed before full header was received"));
+      _reportHttpError(
+          HttpException("Connection closed before full header was received"));
       _controller.close();
       return;
     }
@@ -859,8 +863,8 @@
       _state = _State.FAILURE;
       // Report the error through the error callback if any. Otherwise
       // throw the error.
-      _reportError(
-          new HttpException("Connection closed before full body was received"));
+      _reportHttpError(
+          HttpException("Connection closed before full body was received"));
     }
     _controller.close();
   }
@@ -905,7 +909,7 @@
     _headerField.clear();
     _headerValue.clear();
     _method.clear();
-    _uri_or_reason_phrase.clear();
+    _uriOrReasonPhrase.clear();
 
     _statusCode = 0;
     _statusCodeLength = 0;
@@ -964,7 +968,7 @@
   }
 
   // expected should already be lowercase.
-  bool _caseInsensitiveCompare(List<int> expected, List<int> value) {
+  static bool _caseInsensitiveCompare(List<int> expected, List<int> value) {
     if (expected.length != value.length) return false;
     for (int i = 0; i < expected.length; i++) {
       if (expected[i] != _toLowerCaseByte(value[i])) return false;
@@ -974,7 +978,8 @@
 
   void _expect(int val1, int val2) {
     if (val1 != val2) {
-      throw new HttpException("Failed to parse HTTP");
+      throw new HttpException(
+          "Failed to parse HTTP, $val1 does not match $val2");
     }
   }
 
@@ -986,7 +991,8 @@
     } else if (0x61 <= byte && byte <= 0x66) {
       return byte - 0x61 + 10; // a - f
     } else {
-      throw new HttpException("Failed to parse HTTP");
+      throw new HttpException(
+          "Failed to parse HTTP, $byte should be a Hex digit");
     }
   }
 
@@ -1055,10 +1061,20 @@
     }
   }
 
-  void _reportError(error, [stackTrace]) {
+  void _reportHttpError(error, [stackTrace]) {
     if (_socketSubscription != null) _socketSubscription.cancel();
     _state = _State.FAILURE;
     _controller.addError(error, stackTrace);
     _controller.close();
   }
+
+  void _reportBodyError(error, [stackTrace]) {
+    if (_socketSubscription != null) _socketSubscription.cancel();
+    _state = _State.FAILURE;
+    _bodyController.addError(error, stackTrace);
+    // In case of drain(), error event will close the stream.
+    if (_bodyController != null) {
+      _bodyController.close();
+    }
+  }
 }
diff --git a/sdk/lib/_internal/js_runtime/lib/rti.dart b/sdk/lib/_internal/js_runtime/lib/rti.dart
index d1ab30f..30d4f45 100644
--- a/sdk/lib/_internal/js_runtime/lib/rti.dart
+++ b/sdk/lib/_internal/js_runtime/lib/rti.dart
@@ -812,8 +812,7 @@
 
   var isFn = RAW_DART_FUNCTION_REF(_generalIsTestImplementation);
 
-  // TODO(fishythefish): Update for NNBD.
-  if (isLegacyTopType(testRti)) {
+  if (isTopType(testRti)) {
     isFn = RAW_DART_FUNCTION_REF(_isTop);
     var asFn = RAW_DART_FUNCTION_REF(_asTop);
     Rti._setAsCheckFunction(testRti, asFn);
@@ -835,11 +834,7 @@
       String name = Rti._getInterfaceName(testRti);
       var arguments = Rti._getInterfaceTypeArguments(testRti);
       if (JS(
-          'bool',
-          '#.every(#)',
-          arguments,
-          // TODO(fishythefish): Update for NNBD.
-          RAW_DART_FUNCTION_REF(isLegacyTopType))) {
+          'bool', '#.every(#)', arguments, RAW_DART_FUNCTION_REF(isTopType))) {
         String propertyName =
             '${JS_GET_NAME(JsGetName.OPERATOR_IS_PREFIX)}${name}';
         Rti._setSpecializedTestResource(testRti, propertyName);
@@ -858,8 +853,7 @@
   // method. The Rti object is 'this'.
   Rti testRti = _castToRti(JS('', 'this'));
   Rti objectRti = instanceOrFunctionType(object, testRti);
-  // TODO(fishythefish): Update for NNBD.
-  return isLegacySubtype(_theUniverse(), objectRti, testRti);
+  return isSubtype(_theUniverse(), objectRti, testRti);
 }
 
 /// Called from generated code.
@@ -910,8 +904,7 @@
 
 /// Called from generated code.
 checkTypeBound(Rti type, Rti bound, variable, methodName) {
-  // TODO(fishythefish): Update for NNBD.
-  if (isLegacySubtype(_theUniverse(), type, bound)) return type;
+  if (isSubtype(_theUniverse(), type, bound)) return type;
   String message = "The type argument '${_rtiToString(type, null)}' is not"
       " a subtype of the type variable bound '${_rtiToString(bound, null)}'"
       " of type variable '${_Utils.asString(variable)}' in '$methodName'.";
@@ -1110,8 +1103,7 @@
       typeParametersText += typeSep;
       typeParametersText += genericContext[genericContext.length - 1 - i];
       Rti boundRti = _castToRti(_Utils.arrayAt(bounds, i));
-      // TODO(fishythefish): Update for NNBD.
-      if (!isLegacyTopType(boundRti)) {
+      if (!isTopType(boundRti)) {
         typeParametersText +=
             ' extends ' + _rtiToString(boundRti, genericContext);
       }
@@ -2340,12 +2332,8 @@
 // -------- Subtype tests ------------------------------------------------------
 
 // Future entry point from compiled code.
-bool isLegacySubtype(universe, Rti s, Rti t) {
-  return _isSubtype(universe, s, null, t, null, true);
-}
-
-bool isNnbdSubtype(universe, Rti s, Rti t) {
-  return _isSubtype(universe, s, null, t, null, false);
+bool isSubtype(universe, Rti s, Rti t) {
+  return _isSubtype(universe, s, null, t, null);
 }
 
 /// Based on
@@ -2371,18 +2359,20 @@
 /// the bottom of the type hierarchy, `Object` is treated as nullable, and
 /// `required` is ignored on named parameters. This should provide the same
 /// subtyping results as pre-NNBD Dart.
-bool _isSubtype(universe, Rti s, sEnv, Rti t, tEnv, bool isLegacy) {
+bool _isSubtype(universe, Rti s, sEnv, Rti t, tEnv) {
+  bool isLegacy = JS_GET_FLAG('LEGACY');
+
   // Reflexivity:
   if (_Utils.isIdentical(s, t)) return true;
 
   // Right Top:
-  if (isTopType(t, isLegacy)) return true;
+  if (isTopType(t)) return true;
 
   int sKind = Rti._getKind(s);
   if (sKind == Rti.kindAny) return true;
 
   // Left Top:
-  if (isTopType(s, isLegacy)) return false;
+  if (isTopType(s)) return false;
 
   // Left Bottom:
   if (isLegacy) {
@@ -2396,7 +2386,7 @@
   if (leftTypeVariable) {
     int index = Rti._getGenericFunctionParameterIndex(s);
     Rti bound = _castToRti(_Utils.arrayAt(sEnv, index));
-    if (_isSubtype(universe, bound, sEnv, t, tEnv, isLegacy)) return true;
+    if (_isSubtype(universe, bound, sEnv, t, tEnv)) return true;
   }
 
   int tKind = Rti._getKind(t);
@@ -2406,8 +2396,7 @@
   // reduce casework.
   if (!isLegacy && isNullType(s)) {
     if (tKind == Rti.kindFutureOr) {
-      return _isSubtype(
-          universe, s, sEnv, Rti._getFutureOrArgument(t), tEnv, isLegacy);
+      return _isSubtype(universe, s, sEnv, Rti._getFutureOrArgument(t), tEnv);
     }
     return isNullType(t) || tKind == Rti.kindQuestion || tKind == Rti.kindStar;
   }
@@ -2415,20 +2404,17 @@
   // Right Object:
   if (!isLegacy && isObjectType(t)) {
     if (sKind == Rti.kindFutureOr) {
-      return _isSubtype(
-          universe, Rti._getFutureOrArgument(s), sEnv, t, tEnv, isLegacy);
+      return _isSubtype(universe, Rti._getFutureOrArgument(s), sEnv, t, tEnv);
     }
     if (sKind == Rti.kindStar) {
-      return _isSubtype(
-          universe, Rti._getStarArgument(s), sEnv, t, tEnv, isLegacy);
+      return _isSubtype(universe, Rti._getStarArgument(s), sEnv, t, tEnv);
     }
     return sKind != Rti.kindQuestion;
   }
 
   // Left Legacy:
   if (sKind == Rti.kindStar) {
-    return _isSubtype(
-        universe, Rti._getStarArgument(s), sEnv, t, tEnv, isLegacy);
+    return _isSubtype(universe, Rti._getStarArgument(s), sEnv, t, tEnv);
   }
 
   // Right Legacy:
@@ -2440,26 +2426,23 @@
         isLegacy
             ? Rti._getStarArgument(t)
             : Rti._getQuestionFromStar(universe, t),
-        tEnv,
-        isLegacy);
+        tEnv);
   }
 
   // Left FutureOr:
   if (sKind == Rti.kindFutureOr) {
-    if (!_isSubtype(
-        universe, Rti._getFutureOrArgument(s), sEnv, t, tEnv, isLegacy)) {
+    if (!_isSubtype(universe, Rti._getFutureOrArgument(s), sEnv, t, tEnv)) {
       return false;
     }
-    return _isSubtype(universe, Rti._getFutureFromFutureOr(universe, s), sEnv,
-        t, tEnv, isLegacy);
+    return _isSubtype(
+        universe, Rti._getFutureFromFutureOr(universe, s), sEnv, t, tEnv);
   }
 
   // Left Nullable:
   if (sKind == Rti.kindQuestion) {
     return (isLegacy ||
-            _isSubtype(universe, TYPE_REF<Null>(), sEnv, t, tEnv, isLegacy)) &&
-        _isSubtype(
-            universe, Rti._getQuestionArgument(s), sEnv, t, tEnv, isLegacy);
+            _isSubtype(universe, TYPE_REF<Null>(), sEnv, t, tEnv)) &&
+        _isSubtype(universe, Rti._getQuestionArgument(s), sEnv, t, tEnv);
   }
 
   // Type Variable Reflexivity 1 is subsumed by Reflexivity and therefore
@@ -2469,20 +2452,18 @@
 
   // Right FutureOr:
   if (tKind == Rti.kindFutureOr) {
-    if (_isSubtype(
-        universe, s, sEnv, Rti._getFutureOrArgument(t), tEnv, isLegacy)) {
+    if (_isSubtype(universe, s, sEnv, Rti._getFutureOrArgument(t), tEnv)) {
       return true;
     }
-    return _isSubtype(universe, s, sEnv,
-        Rti._getFutureFromFutureOr(universe, t), tEnv, isLegacy);
+    return _isSubtype(
+        universe, s, sEnv, Rti._getFutureFromFutureOr(universe, t), tEnv);
   }
 
   // Right Nullable:
   if (tKind == Rti.kindQuestion) {
     return (!isLegacy &&
-            _isSubtype(universe, s, sEnv, TYPE_REF<Null>(), tEnv, isLegacy)) ||
-        _isSubtype(
-            universe, s, sEnv, Rti._getQuestionArgument(t), tEnv, isLegacy);
+            _isSubtype(universe, s, sEnv, TYPE_REF<Null>(), tEnv)) ||
+        _isSubtype(universe, s, sEnv, Rti._getQuestionArgument(t), tEnv);
   }
 
   // Left Promoted Variable does not apply at runtime.
@@ -2505,37 +2486,47 @@
 
     var sBounds = Rti._getGenericFunctionBounds(s);
     var tBounds = Rti._getGenericFunctionBounds(t);
-    if (!typesEqual(sBounds, tBounds, isLegacy)) return false;
+    int sLength = _Utils.arrayLength(sBounds);
+    int tLength = _Utils.arrayLength(tBounds);
+    if (sLength != tLength) return false;
+    for (int i = 0; i < sLength; i++) {
+      var sBound = _Utils.arrayAt(sBounds, i);
+      var tBound = _Utils.arrayAt(tBounds, i);
+      if (!_isSubtype(universe, sBound, sEnv, tBound, tEnv) ||
+          !_isSubtype(universe, tBound, tEnv, sBound, sEnv)) {
+        return false;
+      }
+    }
 
     sEnv = sEnv == null ? sBounds : _Utils.arrayConcat(sBounds, sEnv);
     tEnv = tEnv == null ? tBounds : _Utils.arrayConcat(tBounds, tEnv);
 
     return _isFunctionSubtype(universe, Rti._getGenericFunctionBase(s), sEnv,
-        Rti._getGenericFunctionBase(t), tEnv, isLegacy);
+        Rti._getGenericFunctionBase(t), tEnv);
   }
   if (tKind == Rti.kindFunction) {
     if (isJsFunctionType(s)) return true;
     if (sKind != Rti.kindFunction) return false;
-    return _isFunctionSubtype(universe, s, sEnv, t, tEnv, isLegacy);
+    return _isFunctionSubtype(universe, s, sEnv, t, tEnv);
   }
 
   // Interface Compositionality + Super-Interface:
   if (sKind == Rti.kindInterface) {
     if (tKind != Rti.kindInterface) return false;
-    return _isInterfaceSubtype(universe, s, sEnv, t, tEnv, isLegacy);
+    return _isInterfaceSubtype(universe, s, sEnv, t, tEnv);
   }
 
   return false;
 }
 
 // TODO(fishythefish): Support required named parameters.
-bool _isFunctionSubtype(universe, Rti s, sEnv, Rti t, tEnv, bool isLegacy) {
+bool _isFunctionSubtype(universe, Rti s, sEnv, Rti t, tEnv) {
   assert(Rti._getKind(s) == Rti.kindFunction);
   assert(Rti._getKind(t) == Rti.kindFunction);
 
   Rti sReturnType = Rti._getReturnType(s);
   Rti tReturnType = Rti._getReturnType(t);
-  if (!_isSubtype(universe, sReturnType, sEnv, tReturnType, tEnv, isLegacy)) {
+  if (!_isSubtype(universe, sReturnType, sEnv, tReturnType, tEnv)) {
     return false;
   }
 
@@ -2564,7 +2555,7 @@
   for (int i = 0; i < sRequiredPositionalLength; i++) {
     Rti sParameter = _castToRti(_Utils.arrayAt(sRequiredPositional, i));
     Rti tParameter = _castToRti(_Utils.arrayAt(tRequiredPositional, i));
-    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv, isLegacy)) {
+    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv)) {
       return false;
     }
   }
@@ -2573,7 +2564,7 @@
     Rti sParameter = _castToRti(_Utils.arrayAt(sOptionalPositional, i));
     Rti tParameter = _castToRti(
         _Utils.arrayAt(tRequiredPositional, sRequiredPositionalLength + i));
-    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv, isLegacy)) {
+    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv)) {
       return false;
     }
   }
@@ -2582,7 +2573,7 @@
     Rti sParameter = _castToRti(
         _Utils.arrayAt(sOptionalPositional, requiredPositionalDelta + i));
     Rti tParameter = _castToRti(_Utils.arrayAt(tOptionalPositional, i));
-    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv, isLegacy)) {
+    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv)) {
       return false;
     }
   }
@@ -2603,13 +2594,13 @@
     if (_Utils.stringLessThan(tName, sName)) return false;
     Rti sType = _castToRti(_Utils.arrayAt(sOptionalNamed, i - 1));
     Rti tType = _castToRti(_Utils.arrayAt(tOptionalNamed, j + 1));
-    if (!_isSubtype(universe, tType, tEnv, sType, sEnv, isLegacy)) return false;
+    if (!_isSubtype(universe, tType, tEnv, sType, sEnv)) return false;
   }
 
   return true;
 }
 
-bool _isInterfaceSubtype(universe, Rti s, sEnv, Rti t, tEnv, bool isLegacy) {
+bool _isInterfaceSubtype(universe, Rti s, sEnv, Rti t, tEnv) {
   String sName = Rti._getInterfaceName(s);
   String tName = Rti._getInterfaceName(t);
 
@@ -2638,18 +2629,18 @@
         switch (sVariance) {
           case Variance.legacyCovariant:
           case Variance.covariant:
-            if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv, isLegacy)) {
+            if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv)) {
               return false;
             }
             break;
           case Variance.contravariant:
-            if (!_isSubtype(universe, tArg, tEnv, sArg, sEnv, isLegacy)) {
+            if (!_isSubtype(universe, tArg, tEnv, sArg, sEnv)) {
               return false;
             }
             break;
           case Variance.invariant:
-            if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv, isLegacy) ||
-                !_isSubtype(universe, tArg, tEnv, sArg, sEnv, isLegacy)) {
+            if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv) ||
+                !_isSubtype(universe, tArg, tEnv, sArg, sEnv)) {
               return false;
             }
             break;
@@ -2658,7 +2649,7 @@
                 "Unknown variance given for subtype check: $sVariance");
         }
       } else {
-        if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv, isLegacy)) {
+        if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv)) {
           return false;
         }
       }
@@ -2687,102 +2678,15 @@
     String recipe = _Utils.asString(_Utils.arrayAt(supertypeArgs, i));
     Rti supertypeArg = _Universe.evalInEnvironment(universe, s, recipe);
     Rti tArg = _castToRti(_Utils.arrayAt(tArgs, i));
-    if (!_isSubtype(universe, supertypeArg, sEnv, tArg, tEnv, isLegacy)) {
+    if (!_isSubtype(universe, supertypeArg, sEnv, tArg, tEnv)) {
       return false;
     }
   }
   return true;
 }
 
-/// Types are equal if they are structurally equal up to renaming of bound type
-/// variables and equating all top types.
-///
-/// We ignore renaming of bound type variables because we operate on de Bruijn
-/// indices, not names.
-bool typeEqual(Rti s, Rti t, bool isLegacy) {
-  if (_Utils.isIdentical(s, t)) return true;
-
-  if (isTopType(s, isLegacy)) return isTopType(t, isLegacy);
-
-  int sKind = Rti._getKind(s);
-  int tKind = Rti._getKind(t);
-  if (sKind != tKind) return false;
-
-  switch (sKind) {
-    case Rti.kindStar:
-    case Rti.kindQuestion:
-    case Rti.kindFutureOr:
-      return typeEqual(_castToRti(Rti._getPrimary(s)),
-          _castToRti(Rti._getPrimary(t)), isLegacy);
-
-    case Rti.kindInterface:
-      if (Rti._getInterfaceName(s) != Rti._getInterfaceName(t)) return false;
-      return typesEqual(Rti._getInterfaceTypeArguments(s),
-          Rti._getInterfaceTypeArguments(t), isLegacy);
-
-    case Rti.kindBinding:
-      return typeEqual(
-              Rti._getBindingBase(s), Rti._getBindingBase(t), isLegacy) &&
-          typesEqual(Rti._getBindingArguments(s), Rti._getBindingArguments(t),
-              isLegacy);
-
-    case Rti.kindFunction:
-      return typeEqual(
-              Rti._getReturnType(s), Rti._getReturnType(t), isLegacy) &&
-          functionParametersEqual(Rti._getFunctionParameters(s),
-              Rti._getFunctionParameters(t), isLegacy);
-
-    case Rti.kindGenericFunction:
-      return typeEqual(Rti._getGenericFunctionBase(s),
-              Rti._getGenericFunctionBase(t), isLegacy) &&
-          typesEqual(Rti._getGenericFunctionBounds(s),
-              Rti._getGenericFunctionBounds(t), isLegacy);
-
-    default:
-      return false;
-  }
-}
-
-bool typesEqual(Object sArray, Object tArray, isLegacy) {
-  int sLength = _Utils.arrayLength(sArray);
-  int tLength = _Utils.arrayLength(tArray);
-  if (sLength != tLength) return false;
-  for (int i = 0; i < sLength; i++) {
-    if (!typeEqual(_castToRti(_Utils.arrayAt(sArray, i)),
-        _castToRti(_Utils.arrayAt(tArray, i)), isLegacy)) return false;
-  }
-  return true;
-}
-
-bool namedTypesEqual(Object sArray, Object tArray, isLegacy) {
-  int sLength = _Utils.arrayLength(sArray);
-  int tLength = _Utils.arrayLength(tArray);
-  assert(sLength.isEven);
-  assert(tLength.isEven);
-  if (sLength != tLength) return false;
-  for (int i = 0; i < sLength; i += 2) {
-    if (_Utils.asString(_Utils.arrayAt(sArray, i)) !=
-        _Utils.asString(_Utils.arrayAt(tArray, i))) return false;
-    if (!typeEqual(_castToRti(_Utils.arrayAt(sArray, i + 1)),
-        _castToRti(_Utils.arrayAt(tArray, i + 1)), isLegacy)) return false;
-  }
-  return true;
-}
-
-// TODO(fishythefish): Support required named parameters.
-bool functionParametersEqual(_FunctionParameters sParameters,
-        _FunctionParameters tParameters, isLegacy) =>
-    typesEqual(_FunctionParameters._getRequiredPositional(sParameters),
-        _FunctionParameters._getRequiredPositional(tParameters), isLegacy) &&
-    typesEqual(_FunctionParameters._getOptionalPositional(sParameters),
-        _FunctionParameters._getOptionalPositional(tParameters), isLegacy) &&
-    namedTypesEqual(_FunctionParameters._getOptionalNamed(sParameters),
-        _FunctionParameters._getOptionalNamed(tParameters), isLegacy);
-
-bool isLegacyTopType(Rti t) => isTopType(t, true);
-bool isNnbdTopType(Rti t) => isTopType(t, false);
-bool isTopType(Rti t, bool isLegacy) {
-  if (isLegacy) {
+bool isTopType(Rti t) {
+  if (JS_GET_FLAG('LEGACY')) {
     if (isObjectType(t)) return true;
   } else {
     if (isNullableObjectType(t)) return true;
@@ -2792,8 +2696,7 @@
       kind == Rti.kindVoid ||
       kind == Rti.kindAny ||
       kind == Rti.kindErased ||
-      kind == Rti.kindFutureOr &&
-          isTopType(Rti._getFutureOrArgument(t), isLegacy);
+      kind == Rti.kindFutureOr && isTopType(Rti._getFutureOrArgument(t));
 }
 
 bool isObjectType(Rti t) => _Utils.isIdentical(t, TYPE_REF<Object>());
@@ -2900,8 +2803,8 @@
   _Universe.addTypeParameterVariances(universe, variances);
 }
 
-bool testingIsLegacySubtype(universe, rti1, rti2) {
-  return isLegacySubtype(universe, _castToRti(rti1), _castToRti(rti2));
+bool testingIsSubtype(universe, rti1, rti2) {
+  return isSubtype(universe, _castToRti(rti1), _castToRti(rti2));
 }
 
 Object testingUniverseEval(universe, String recipe) {
diff --git a/sdk/lib/_internal/vm/bin/stdio_patch.dart b/sdk/lib/_internal/vm/bin/stdio_patch.dart
index 1303573..6ee2b8b 100644
--- a/sdk/lib/_internal/vm/bin/stdio_patch.dart
+++ b/sdk/lib/_internal/vm/bin/stdio_patch.dart
@@ -10,31 +10,30 @@
 class _StdIOUtils {
   @patch
   static Stdin _getStdioInputStream(int fd) {
-    switch (_getStdioHandleType(fd)) {
+    final type = _getStdioHandleType(fd);
+    if (type is OSError) {
+      throw FileSystemException(
+          "Failed to get type of stdio handle (fd $fd)", "", type);
+    }
+    switch (type) {
       case _stdioHandleTypeTerminal:
       case _stdioHandleTypePipe:
       case _stdioHandleTypeSocket:
+      case _stdioHandleTypeOther:
         return new Stdin._(new _Socket._readPipe(fd), fd);
       case _stdioHandleTypeFile:
         return new Stdin._(new _FileStream.forStdin(), fd);
-      default:
-        throw new FileSystemException(
-            "Couldn't determine file type of stdin (fd $fd)");
     }
   }
 
   @patch
   static _getStdioOutputStream(int fd) {
-    switch (_getStdioHandleType(fd)) {
-      case _stdioHandleTypeTerminal:
-      case _stdioHandleTypePipe:
-      case _stdioHandleTypeSocket:
-      case _stdioHandleTypeFile:
-        return new Stdout._(new IOSink(new _StdConsumer(fd)), fd);
-      default:
-        throw new FileSystemException(
-            "Couldn't determine file type of stdio handle (fd $fd)");
+    final type = _getStdioHandleType(fd);
+    if (type is OSError) {
+      throw FileSystemException(
+          "Failed to get type of stdio handle (fd $fd)", "", type);
     }
+    return new Stdout._(new IOSink(new _StdConsumer(fd)), fd);
   }
 
   @patch
diff --git a/sdk/lib/_internal/vm/bin/vmservice_io.dart b/sdk/lib/_internal/vm/bin/vmservice_io.dart
index 29fa6db..7e3146d 100644
--- a/sdk/lib/_internal/vm/bin/vmservice_io.dart
+++ b/sdk/lib/_internal/vm/bin/vmservice_io.dart
@@ -40,6 +40,8 @@
 @pragma("vm:entry-point")
 var _signalWatch;
 var _signalSubscription;
+@pragma("vm:entry-point")
+bool _enableServicePortFallback = false;
 
 // HTTP server.
 Server server;
@@ -53,7 +55,7 @@
   var service = new VMService();
   // Lazily create server.
   server = new Server(service, _ip, _port, _originCheckDisabled,
-      _authCodesDisabled, _serviceInfoFilename);
+      _authCodesDisabled, _serviceInfoFilename, _enableServicePortFallback);
 }
 
 Future cleanupCallback() async {
diff --git a/sdk/lib/_internal/vm/bin/vmservice_server.dart b/sdk/lib/_internal/vm/bin/vmservice_server.dart
index 46ac1e2..06f39b6 100644
--- a/sdk/lib/_internal/vm/bin/vmservice_server.dart
+++ b/sdk/lib/_internal/vm/bin/vmservice_server.dart
@@ -147,12 +147,13 @@
 
   final VMService _service;
   final String _ip;
-  final int _port;
   final bool _originCheckDisabled;
   final bool _authCodesDisabled;
+  final bool _enableServicePortFallback;
   final String _serviceInfoFilename;
   HttpServer _server;
   bool get running => _server != null;
+  int _port = -1;
 
   /// Returns the server address including the auth token.
   Uri get serverAddress {
@@ -167,8 +168,14 @@
 
   // On Fuchsia, authentication codes are disabled by default. To enable, the authentication token
   // would have to be written into the hub alongside the port number.
-  Server(this._service, this._ip, this._port, this._originCheckDisabled,
-      bool authCodesDisabled, this._serviceInfoFilename)
+  Server(
+      this._service,
+      this._ip,
+      this._port,
+      this._originCheckDisabled,
+      bool authCodesDisabled,
+      this._serviceInfoFilename,
+      this._enableServicePortFallback)
       : _authCodesDisabled = (authCodesDisabled || Platform.isFuchsia);
 
   bool _isAllowedOrigin(String origin) {
@@ -422,6 +429,10 @@
         onServerAddressChange(null);
         return this;
       }
+      if (_port != 0 && _enableServicePortFallback && attempts >= 3) {
+        _port = 0;
+        serverPrint('Falling back to automatic port selection');
+      }
       await new Future<Null>.delayed(const Duration(seconds: 1));
     }
     if (_service.isExiting) {
diff --git a/sdk/lib/_internal/vm/lib/async_patch.dart b/sdk/lib/_internal/vm/lib/async_patch.dart
index 3526df1..0192bfe 100644
--- a/sdk/lib/_internal/vm/lib/async_patch.dart
+++ b/sdk/lib/_internal/vm/lib/async_patch.dart
@@ -72,7 +72,7 @@
   // `Future` implementation could potentially invoke the callback with the
   // wrong number of arguments.
   if (Zone.current == Zone.root) return continuation;
-  return Zone.current.registerUnaryCallback((x) => continuation(x, null, null));
+  return Zone.current.registerUnaryCallback(continuation);
 }
 
 // We need to pass the exception and stack trace objects as second and third
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 58d810f..9e856ea 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -592,6 +592,7 @@
   }
 
   // Shadowing definition.
+
   num get delay => JS("num", "#.delay", this);
 
   set delay(num value) {
@@ -599,6 +600,7 @@
   }
 
   // Shadowing definition.
+
   String get direction => JS("String", "#.direction", this);
 
   set direction(String value) {
@@ -606,6 +608,7 @@
   }
 
   // Shadowing definition.
+
   Object get duration => JS("Object", "#.duration", this);
 
   set duration(Object value) {
@@ -613,6 +616,7 @@
   }
 
   // Shadowing definition.
+
   String get easing => JS("String", "#.easing", this);
 
   set easing(String value) {
@@ -620,6 +624,7 @@
   }
 
   // Shadowing definition.
+
   num get endDelay => JS("num", "#.endDelay", this);
 
   set endDelay(num value) {
@@ -627,6 +632,7 @@
   }
 
   // Shadowing definition.
+
   String get fill => JS("String", "#.fill", this);
 
   set fill(String value) {
@@ -634,6 +640,7 @@
   }
 
   // Shadowing definition.
+
   num get iterationStart => JS("num", "#.iterationStart", this);
 
   set iterationStart(num value) {
@@ -641,6 +648,7 @@
   }
 
   // Shadowing definition.
+
   num get iterations => JS("num", "#.iterations", this);
 
   set iterations(num value) {
@@ -1393,6 +1401,7 @@
   }
 
   // Shadowing definition.
+
   String get returnValue => JS("String", "#.returnValue", this);
 
   set returnValue(String value) {
@@ -10156,6 +10165,7 @@
   static DomMatrix _create_2() => JS('DomMatrix', 'new DOMMatrix()');
 
   // Shadowing definition.
+
   num get a => JS("num", "#.a", this);
 
   set a(num value) {
@@ -10163,6 +10173,7 @@
   }
 
   // Shadowing definition.
+
   num get b => JS("num", "#.b", this);
 
   set b(num value) {
@@ -10170,6 +10181,7 @@
   }
 
   // Shadowing definition.
+
   num get c => JS("num", "#.c", this);
 
   set c(num value) {
@@ -10177,6 +10189,7 @@
   }
 
   // Shadowing definition.
+
   num get d => JS("num", "#.d", this);
 
   set d(num value) {
@@ -10184,6 +10197,7 @@
   }
 
   // Shadowing definition.
+
   num get e => JS("num", "#.e", this);
 
   set e(num value) {
@@ -10191,6 +10205,7 @@
   }
 
   // Shadowing definition.
+
   num get f => JS("num", "#.f", this);
 
   set f(num value) {
@@ -10198,6 +10213,7 @@
   }
 
   // Shadowing definition.
+
   num get m11 => JS("num", "#.m11", this);
 
   set m11(num value) {
@@ -10205,6 +10221,7 @@
   }
 
   // Shadowing definition.
+
   num get m12 => JS("num", "#.m12", this);
 
   set m12(num value) {
@@ -10212,6 +10229,7 @@
   }
 
   // Shadowing definition.
+
   num get m13 => JS("num", "#.m13", this);
 
   set m13(num value) {
@@ -10219,6 +10237,7 @@
   }
 
   // Shadowing definition.
+
   num get m14 => JS("num", "#.m14", this);
 
   set m14(num value) {
@@ -10226,6 +10245,7 @@
   }
 
   // Shadowing definition.
+
   num get m21 => JS("num", "#.m21", this);
 
   set m21(num value) {
@@ -10233,6 +10253,7 @@
   }
 
   // Shadowing definition.
+
   num get m22 => JS("num", "#.m22", this);
 
   set m22(num value) {
@@ -10240,6 +10261,7 @@
   }
 
   // Shadowing definition.
+
   num get m23 => JS("num", "#.m23", this);
 
   set m23(num value) {
@@ -10247,6 +10269,7 @@
   }
 
   // Shadowing definition.
+
   num get m24 => JS("num", "#.m24", this);
 
   set m24(num value) {
@@ -10254,6 +10277,7 @@
   }
 
   // Shadowing definition.
+
   num get m31 => JS("num", "#.m31", this);
 
   set m31(num value) {
@@ -10261,6 +10285,7 @@
   }
 
   // Shadowing definition.
+
   num get m32 => JS("num", "#.m32", this);
 
   set m32(num value) {
@@ -10268,6 +10293,7 @@
   }
 
   // Shadowing definition.
+
   num get m33 => JS("num", "#.m33", this);
 
   set m33(num value) {
@@ -10275,6 +10301,7 @@
   }
 
   // Shadowing definition.
+
   num get m34 => JS("num", "#.m34", this);
 
   set m34(num value) {
@@ -10282,6 +10309,7 @@
   }
 
   // Shadowing definition.
+
   num get m41 => JS("num", "#.m41", this);
 
   set m41(num value) {
@@ -10289,6 +10317,7 @@
   }
 
   // Shadowing definition.
+
   num get m42 => JS("num", "#.m42", this);
 
   set m42(num value) {
@@ -10296,6 +10325,7 @@
   }
 
   // Shadowing definition.
+
   num get m43 => JS("num", "#.m43", this);
 
   set m43(num value) {
@@ -10303,6 +10333,7 @@
   }
 
   // Shadowing definition.
+
   num get m44 => JS("num", "#.m44", this);
 
   set m44(num value) {
@@ -10581,6 +10612,7 @@
       JS('bool', '!!(window.DOMPoint) || !!(window.WebKitPoint)');
 
   // Shadowing definition.
+
   num get w => JS("num", "#.w", this);
 
   set w(num value) {
@@ -10588,6 +10620,7 @@
   }
 
   // Shadowing definition.
+
   num get x => JS("num", "#.x", this);
 
   set x(num value) {
@@ -10595,6 +10628,7 @@
   }
 
   // Shadowing definition.
+
   num get y => JS("num", "#.y", this);
 
   set y(num value) {
@@ -10602,6 +10636,7 @@
   }
 
   // Shadowing definition.
+
   num get z => JS("num", "#.z", this);
 
   set z(num value) {
@@ -13872,6 +13907,7 @@
   String inputMode;
 
   // Using property as subclass shadows.
+
   bool get isContentEditable => JS("bool", "#.isContentEditable", this);
 
   String lang;
@@ -13935,6 +13971,7 @@
   final String _namespaceUri;
 
   // Using property as subclass shadows.
+
   String get outerHtml => JS("String", "#.outerHTML", this);
 
   @JSName('scrollHeight')
@@ -33048,6 +33085,7 @@
   static _DomRect _create_5() => JS('_DomRect', 'new DOMRect()');
 
   // Shadowing definition.
+
   num get height => JS("num", "#.height", this);
 
   set height(num value) {
@@ -33055,6 +33093,7 @@
   }
 
   // Shadowing definition.
+
   num get width => JS("num", "#.width", this);
 
   set width(num value) {
@@ -33062,6 +33101,7 @@
   }
 
   // Shadowing definition.
+
   num get x => JS("num", "#.x", this);
 
   set x(num value) {
@@ -33069,6 +33109,7 @@
   }
 
   // Shadowing definition.
+
   num get y => JS("num", "#.y", this);
 
   set y(num value) {
@@ -35676,7 +35717,9 @@
     }
     // Remove current event listener.
     _unlisten();
-    _onData = _wrapZone<Event>(handleData);
+    _onData = handleData == null
+        ? null
+        : _wrapZone<Event>((e) => (handleData as dynamic)(e));
     _tryResume();
   }
 
diff --git a/sdk/lib/io/common.dart b/sdk/lib/io/common.dart
index d047752..e6b5547 100644
--- a/sdk/lib/io/common.dart
+++ b/sdk/lib/io/common.dart
@@ -106,9 +106,7 @@
   var newBuffer = new Uint8List(length);
   int j = start;
   for (int i = 0; i < length; i++) {
-    int value = buffer[j];
-    if (value == null) throw ArgumentError("List element is null at index $j");
-    newBuffer[i] = value;
+    newBuffer[i] = buffer[j];
     j++;
   }
   return new _BufferAndStart(newBuffer, 0);
diff --git a/sdk/lib/io/stdio.dart b/sdk/lib/io/stdio.dart
index 8faf791..4dfc0af 100644
--- a/sdk/lib/io/stdio.dart
+++ b/sdk/lib/io/stdio.dart
@@ -6,11 +6,13 @@
 
 part of dart.io;
 
+// These match enum StdioHandleType in file.h
 const int _stdioHandleTypeTerminal = 0;
 const int _stdioHandleTypePipe = 1;
 const int _stdioHandleTypeFile = 2;
 const int _stdioHandleTypeSocket = 3;
 const int _stdioHandleTypeOther = 4;
+const int _stdioHandleTypeError = 5;
 
 class _StdStream extends Stream<List<int>> {
   final Stream<List<int>> _stream;
@@ -436,7 +438,12 @@
     object = object._stream;
   } else if (object == stdout || object == stderr) {
     int stdiofd = object == stdout ? _stdoutFD : _stderrFD;
-    switch (_StdIOUtils._getStdioHandleType(stdiofd)) {
+    final type = _StdIOUtils._getStdioHandleType(stdiofd);
+    if (type is OSError) {
+      throw FileSystemException(
+          "Failed to get type of stdio handle (fd $stdiofd)", "", type);
+    }
+    switch (type) {
       case _stdioHandleTypeTerminal:
         return StdioType.terminal;
       case _stdioHandleTypePipe:
diff --git a/sdk/lib/svg/dart2js/svg_dart2js.dart b/sdk/lib/svg/dart2js/svg_dart2js.dart
index ca8fbb2..2ad4ec6 100644
--- a/sdk/lib/svg/dart2js/svg_dart2js.dart
+++ b/sdk/lib/svg/dart2js/svg_dart2js.dart
@@ -3181,6 +3181,7 @@
   SvgElement.created() : super.created();
 
   // Shadowing definition.
+
   AnimatedString get _svgClassName => JS("AnimatedString", "#.className", this);
 
   @JSName('ownerSVGElement')
diff --git a/sdk_nnbd/lib/_http/http_parser.dart b/sdk_nnbd/lib/_http/http_parser.dart
index 4a4f196..ea51e57 100644
--- a/sdk_nnbd/lib/_http/http_parser.dart
+++ b/sdk_nnbd/lib/_http/http_parser.dart
@@ -243,7 +243,7 @@
   int _statusCode = 0;
   int _statusCodeLength = 0;
   final List<int> _method = [];
-  final List<int> _uri_or_reason_phrase = [];
+  final List<int> _uriOrReasonPhrase = [];
   final List<int> _headerField = [];
   final List<int> _headerValue = [];
 
@@ -314,8 +314,13 @@
     try {
       _doParse();
     } catch (e, s) {
-      _state = _State.FAILURE;
-      _reportError(e, s);
+      if (_state >= _State.CHUNK_SIZE_STARTING_CR && _state <= _State.BODY) {
+        _state = _State.FAILURE;
+        _reportBodyError(e, s);
+      } else {
+        _state = _State.FAILURE;
+        _reportHttpError(e, s);
+      }
     }
   }
 
@@ -346,13 +351,13 @@
     var incoming = _createIncoming(_transferLength);
     if (_requestParser) {
       incoming.method = new String.fromCharCodes(_method);
-      incoming.uri = Uri.parse(new String.fromCharCodes(_uri_or_reason_phrase));
+      incoming.uri = Uri.parse(new String.fromCharCodes(_uriOrReasonPhrase));
     } else {
       incoming.statusCode = _statusCode;
-      incoming.reasonPhrase = new String.fromCharCodes(_uri_or_reason_phrase);
+      incoming.reasonPhrase = new String.fromCharCodes(_uriOrReasonPhrase);
     }
     _method.clear();
-    _uri_or_reason_phrase.clear();
+    _uriOrReasonPhrase.clear();
     if (_connectionUpgrade) {
       incoming.upgraded = true;
       _parserCalled = false;
@@ -507,7 +512,7 @@
 
         case _State.REQUEST_LINE_URI:
           if (byte == _CharCode.SP) {
-            if (_uri_or_reason_phrase.length == 0) {
+            if (_uriOrReasonPhrase.length == 0) {
               throw new HttpException("Invalid request URI");
             }
             _state = _State.REQUEST_LINE_HTTP_VERSION;
@@ -516,7 +521,7 @@
             if (byte == _CharCode.CR || byte == _CharCode.LF) {
               throw new HttpException("Invalid request URI");
             }
-            _uri_or_reason_phrase.add(byte);
+            _uriOrReasonPhrase.add(byte);
           }
           break;
 
@@ -565,7 +570,7 @@
             _state = _State.RESPONSE_LINE_ENDING;
           } else {
             _statusCodeLength++;
-            if ((byte < 0x30 && 0x39 < byte) || _statusCodeLength > 3) {
+            if (byte < 0x30 || byte > 0x39 || _statusCodeLength > 3) {
               throw new HttpException("Invalid response status code");
             } else {
               _statusCode = _statusCode * 10 + byte - 0x30;
@@ -580,7 +585,7 @@
             if (byte == _CharCode.CR || byte == _CharCode.LF) {
               throw new HttpException("Invalid response reason phrase");
             }
-            _uri_or_reason_phrase.add(byte);
+            _uriOrReasonPhrase.add(byte);
           }
           break;
 
@@ -822,8 +827,8 @@
       if (_state != _State.UPGRADED &&
           !(_state == _State.START && !_requestParser) &&
           !(_state == _State.BODY && !_chunked && _transferLength == -1)) {
-        _bodyController!.addError(
-            new HttpException("Connection closed while receiving data"));
+        _reportBodyError(
+            HttpException("Connection closed while receiving data"));
       }
       _closeIncoming(true);
       _controller.close();
@@ -832,8 +837,8 @@
     // If the connection is idle the HTTP stream is closed.
     if (_state == _State.START) {
       if (!_requestParser) {
-        _reportError(new HttpException(
-            "Connection closed before full header was received"));
+        _reportHttpError(
+            HttpException("Connection closed before full header was received"));
       }
       _controller.close();
       return;
@@ -848,8 +853,8 @@
       _state = _State.FAILURE;
       // Report the error through the error callback if any. Otherwise
       // throw the error.
-      _reportError(new HttpException(
-          "Connection closed before full header was received"));
+      _reportHttpError(
+          HttpException("Connection closed before full header was received"));
       _controller.close();
       return;
     }
@@ -860,8 +865,8 @@
       _state = _State.FAILURE;
       // Report the error through the error callback if any. Otherwise
       // throw the error.
-      _reportError(
-          new HttpException("Connection closed before full body was received"));
+      _reportHttpError(
+          HttpException("Connection closed before full body was received"));
     }
     _controller.close();
   }
@@ -908,7 +913,7 @@
     _headerField.clear();
     _headerValue.clear();
     _method.clear();
-    _uri_or_reason_phrase.clear();
+    _uriOrReasonPhrase.clear();
 
     _statusCode = 0;
     _statusCodeLength = 0;
@@ -967,7 +972,7 @@
   }
 
   // expected should already be lowercase.
-  bool _caseInsensitiveCompare(List<int> expected, List<int> value) {
+  static bool _caseInsensitiveCompare(List<int> expected, List<int> value) {
     if (expected.length != value.length) return false;
     for (int i = 0; i < expected.length; i++) {
       if (expected[i] != _toLowerCaseByte(value[i])) return false;
@@ -977,7 +982,8 @@
 
   void _expect(int val1, int val2) {
     if (val1 != val2) {
-      throw new HttpException("Failed to parse HTTP");
+      throw new HttpException(
+          "Failed to parse HTTP, $val1 does not match $val2");
     }
   }
 
@@ -989,7 +995,8 @@
     } else if (0x61 <= byte && byte <= 0x66) {
       return byte - 0x61 + 10; // a - f
     } else {
-      throw new HttpException("Failed to parse HTTP");
+      throw new HttpException(
+          "Failed to parse HTTP, $byte should be a Hex digit");
     }
   }
 
@@ -1058,10 +1065,18 @@
     }
   }
 
-  void _reportError(Object error, [StackTrace? stackTrace]) {
+  void _reportHttpError(error, [stackTrace]) {
     _socketSubscription?.cancel();
     _state = _State.FAILURE;
     _controller.addError(error, stackTrace);
     _controller.close();
   }
+
+  void _reportBodyError(error, [stackTrace]) {
+    _socketSubscription?.cancel();
+    _state = _State.FAILURE;
+    _bodyController.addError(error, stackTrace);
+    // In case of drain(), error event will close the stream.
+    _bodyController?.close();
+  }
 }
diff --git a/sdk_nnbd/lib/_internal/js_dev_runtime/patch/io_patch.dart b/sdk_nnbd/lib/_internal/js_dev_runtime/patch/io_patch.dart
index 8c28b56..bbe913d 100644
--- a/sdk_nnbd/lib/_internal/js_dev_runtime/patch/io_patch.dart
+++ b/sdk_nnbd/lib/_internal/js_dev_runtime/patch/io_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 import 'dart:_js_helper' show patch;
 import 'dart:async';
 import 'dart:convert';
@@ -320,7 +318,7 @@
   }
 
   @patch
-  static int _pid(Process process) {
+  static int _pid(Process? process) {
     throw UnsupportedError("ProcessUtils._pid");
   }
 
@@ -347,8 +345,8 @@
 class Process {
   @patch
   static Future<Process> start(String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment = true,
       bool runInShell = false,
       ProcessStartMode mode = ProcessStartMode.normal}) {
@@ -357,8 +355,8 @@
 
   @patch
   static Future<ProcessResult> run(String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment = true,
       bool runInShell = false,
       Encoding stdoutEncoding = systemEncoding,
@@ -368,8 +366,8 @@
 
   @patch
   static ProcessResult runSync(String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment = true,
       bool runInShell = false,
       Encoding stdoutEncoding = systemEncoding,
@@ -459,14 +457,14 @@
 @patch
 class RawSocket {
   @patch
-  static Future<RawSocket> connect(host, int port,
-      {sourceAddress, Duration timeout}) {
+  static Future<RawSocket> connect(dynamic host, int port,
+      {dynamic sourceAddress, Duration? timeout}) {
     throw UnsupportedError("RawSocket constructor");
   }
 
   @patch
-  static Future<ConnectionTask<RawSocket>> startConnect(host, int port,
-      {sourceAddress}) {
+  static Future<ConnectionTask<RawSocket>> startConnect(dynamic host, int port,
+      {dynamic sourceAddress}) {
     throw UnsupportedError("RawSocket constructor");
   }
 }
@@ -474,14 +472,14 @@
 @patch
 class Socket {
   @patch
-  static Future<Socket> _connect(host, int port,
-      {sourceAddress, Duration timeout}) {
+  static Future<Socket> _connect(dynamic host, int port,
+      {dynamic sourceAddress, Duration? timeout}) {
     throw UnsupportedError("Socket constructor");
   }
 
   @patch
-  static Future<ConnectionTask<Socket>> _startConnect(host, int port,
-      {sourceAddress}) {
+  static Future<ConnectionTask<Socket>> _startConnect(dynamic host, int port,
+      {dynamic sourceAddress}) {
     throw UnsupportedError("Socket constructor");
   }
 }
@@ -497,7 +495,7 @@
 @patch
 class RawSynchronousSocket {
   @patch
-  static RawSynchronousSocket connectSync(host, int port) {
+  static RawSynchronousSocket connectSync(dynamic host, int port) {
     throw UnsupportedError("RawSynchronousSocket.connectSync");
   }
 }
@@ -539,7 +537,7 @@
 @patch
 class RawDatagramSocket {
   @patch
-  static Future<RawDatagramSocket> bind(host, int port,
+  static Future<RawDatagramSocket> bind(dynamic host, int port,
       {bool reuseAddress = true, bool reusePort = false, int ttl = 1}) {
     throw UnsupportedError("RawDatagramSocket.bind");
   }
@@ -601,14 +599,14 @@
       int windowBits,
       int memLevel,
       int strategy,
-      List<int> dictionary,
+      List<int>? dictionary,
       bool raw) {
     throw UnsupportedError("_newZLibDeflateFilter");
   }
 
   @patch
   static RawZLibFilter _makeZLibInflateFilter(
-      int windowBits, List<int> dictionary, bool raw) {
+      int windowBits, List<int>? dictionary, bool raw) {
     throw UnsupportedError("_newZLibInflateFilter");
   }
 }
diff --git a/sdk_nnbd/lib/_internal/js_dev_runtime/private/ddc_runtime/types.dart b/sdk_nnbd/lib/_internal/js_dev_runtime/private/ddc_runtime/types.dart
index b58a312..e2915e9 100644
--- a/sdk_nnbd/lib/_internal/js_dev_runtime/private/ddc_runtime/types.dart
+++ b/sdk_nnbd/lib/_internal/js_dev_runtime/private/ddc_runtime/types.dart
@@ -1343,15 +1343,22 @@
       // given a type parameter `T1 extends U1` from g1, and a type parameter
       // `T2 extends U2` from g2, we must ensure that:
       //
-      //      U2 == U1
+      //      U1 == U2
+      //
+      // given a legacy type can be equivalent to nullable or non-nullable
+      // versions of the same type. The language spec recomends testing for
+      // mutual subtypes to allow this behaivor.
       //
       // (Note there is no variance in the type bounds of type parameters of
       // generic functions).
       let t1Bounds = $t1.instantiateTypeBounds(fresh);
       let t2Bounds = $t2.instantiateTypeBounds(fresh);
       for (let i = 0; i < formalCount; i++) {
-        if (t2Bounds[i] != t1Bounds[i]) {
-          return false;
+        if (t1Bounds[i] != t2Bounds[i]) {
+          if (!($_isSubtype(t1Bounds[i], t2Bounds[i], $strictMode)
+              && $_isSubtype(t2Bounds[i], t1Bounds[i], $strictMode))) {
+            return false;
+          }
         }
       }
     }
@@ -1620,6 +1627,7 @@
   /// In the case where `false` is returned, some bogus constraints may have
   /// been added to [_protoConstraints].  It is the caller's responsibility to
   /// discard them if necessary.
+  // TODO(#40326) Update to support null safety subtyping algorithm.
   bool _isSubtypeMatch(Object subtype, Object supertype) {
     // A type variable `T` in `L` is a subtype match for any type schema `Q`:
     // - Under constraint `T <: Q`.
diff --git a/sdk_nnbd/lib/_internal/js_runtime/lib/io_patch.dart b/sdk_nnbd/lib/_internal/js_runtime/lib/io_patch.dart
index 48946c3..f657133 100644
--- a/sdk_nnbd/lib/_internal/js_runtime/lib/io_patch.dart
+++ b/sdk_nnbd/lib/_internal/js_runtime/lib/io_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 import 'dart:_js_helper' show patch;
 import 'dart:_internal' hide Symbol;
 import 'dart:async';
@@ -320,7 +318,7 @@
   }
 
   @patch
-  static int _pid(Process process) {
+  static int _pid(Process? process) {
     throw new UnsupportedError("ProcessUtils._pid");
   }
 
@@ -347,8 +345,8 @@
 class Process {
   @patch
   static Future<Process> start(String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment: true,
       bool runInShell: false,
       ProcessStartMode mode: ProcessStartMode.normal}) {
@@ -357,8 +355,8 @@
 
   @patch
   static Future<ProcessResult> run(String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment: true,
       bool runInShell: false,
       Encoding stdoutEncoding: systemEncoding,
@@ -368,8 +366,8 @@
 
   @patch
   static ProcessResult runSync(String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment: true,
       bool runInShell: false,
       Encoding stdoutEncoding: systemEncoding,
@@ -459,14 +457,14 @@
 @patch
 class RawSocket {
   @patch
-  static Future<RawSocket> connect(host, int port,
-      {sourceAddress, Duration timeout}) {
+  static Future<RawSocket> connect(dynamic host, int port,
+      {dynamic sourceAddress, Duration? timeout}) {
     throw new UnsupportedError("RawSocket constructor");
   }
 
   @patch
-  static Future<ConnectionTask<RawSocket>> startConnect(host, int port,
-      {sourceAddress}) {
+  static Future<ConnectionTask<RawSocket>> startConnect(dynamic host, int port,
+      {dynamic sourceAddress}) {
     throw new UnsupportedError("RawSocket constructor");
   }
 }
@@ -474,14 +472,14 @@
 @patch
 class Socket {
   @patch
-  static Future<Socket> _connect(host, int port,
-      {sourceAddress, Duration timeout}) {
+  static Future<Socket> _connect(dynamic host, int port,
+      {dynamic sourceAddress, Duration? timeout}) {
     throw new UnsupportedError("Socket constructor");
   }
 
   @patch
-  static Future<ConnectionTask<Socket>> _startConnect(host, int port,
-      {sourceAddress}) {
+  static Future<ConnectionTask<Socket>> _startConnect(dynamic host, int port,
+      {dynamic sourceAddress}) {
     throw new UnsupportedError("Socket constructor");
   }
 }
@@ -497,7 +495,7 @@
 @patch
 class RawSynchronousSocket {
   @patch
-  static RawSynchronousSocket connectSync(host, int port) {
+  static RawSynchronousSocket connectSync(dynamic host, int port) {
     throw new UnsupportedError("RawSynchronousSocket.connectSync");
   }
 }
@@ -539,7 +537,7 @@
 @patch
 class RawDatagramSocket {
   @patch
-  static Future<RawDatagramSocket> bind(host, int port,
+  static Future<RawDatagramSocket> bind(dynamic host, int port,
       {bool reuseAddress: true, bool reusePort: false, int ttl: 1}) {
     throw new UnsupportedError("RawDatagramSocket.bind");
   }
@@ -601,14 +599,14 @@
       int windowBits,
       int memLevel,
       int strategy,
-      List<int> dictionary,
+      List<int>? dictionary,
       bool raw) {
     throw new UnsupportedError("_newZLibDeflateFilter");
   }
 
   @patch
   static RawZLibFilter _makeZLibInflateFilter(
-      int windowBits, List<int> dictionary, bool raw) {
+      int windowBits, List<int>? dictionary, bool raw) {
     throw new UnsupportedError("_newZLibInflateFilter");
   }
 }
diff --git a/sdk_nnbd/lib/_internal/js_runtime/lib/rti.dart b/sdk_nnbd/lib/_internal/js_runtime/lib/rti.dart
index 8ee75ae..ef15c15 100644
--- a/sdk_nnbd/lib/_internal/js_runtime/lib/rti.dart
+++ b/sdk_nnbd/lib/_internal/js_runtime/lib/rti.dart
@@ -812,8 +812,7 @@
 
   var isFn = RAW_DART_FUNCTION_REF(_generalIsTestImplementation);
 
-  // TODO(fishythefish): Update for NNBD.
-  if (isLegacyTopType(testRti)) {
+  if (isTopType(testRti)) {
     isFn = RAW_DART_FUNCTION_REF(_isTop);
     var asFn = RAW_DART_FUNCTION_REF(_asTop);
     Rti._setAsCheckFunction(testRti, asFn);
@@ -835,11 +834,7 @@
       String name = Rti._getInterfaceName(testRti);
       var arguments = Rti._getInterfaceTypeArguments(testRti);
       if (JS(
-          'bool',
-          '#.every(#)',
-          arguments,
-          // TODO(fishythefish): Update for NNBD.
-          RAW_DART_FUNCTION_REF(isLegacyTopType))) {
+          'bool', '#.every(#)', arguments, RAW_DART_FUNCTION_REF(isTopType))) {
         String propertyName =
             '${JS_GET_NAME(JsGetName.OPERATOR_IS_PREFIX)}${name}';
         Rti._setSpecializedTestResource(testRti, propertyName);
@@ -858,8 +853,7 @@
   // method. The Rti object is 'this'.
   Rti testRti = _castToRti(JS('', 'this'));
   Rti objectRti = instanceOrFunctionType(object, testRti);
-  // TODO(fishythefish): Update for NNBD.
-  return isLegacySubtype(_theUniverse(), objectRti, testRti);
+  return isSubtype(_theUniverse(), objectRti, testRti);
 }
 
 /// Called from generated code.
@@ -910,8 +904,7 @@
 
 /// Called from generated code.
 checkTypeBound(Rti type, Rti bound, variable, methodName) {
-  // TODO(fishythefish): Update for NNBD.
-  if (isLegacySubtype(_theUniverse(), type, bound)) return type;
+  if (isSubtype(_theUniverse(), type, bound)) return type;
   String message = "The type argument '${_rtiToString(type, null)}' is not"
       " a subtype of the type variable bound '${_rtiToString(bound, null)}'"
       " of type variable '${_Utils.asString(variable)}' in '$methodName'.";
@@ -1110,8 +1103,7 @@
       typeParametersText += typeSep;
       typeParametersText += genericContext[genericContext.length - 1 - i];
       Rti boundRti = _castToRti(_Utils.arrayAt(bounds, i));
-      // TODO(fishythefish): Update for NNBD.
-      if (!isLegacyTopType(boundRti)) {
+      if (!isTopType(boundRti)) {
         typeParametersText +=
             ' extends ' + _rtiToString(boundRti, genericContext);
       }
@@ -2340,12 +2332,8 @@
 // -------- Subtype tests ------------------------------------------------------
 
 // Future entry point from compiled code.
-bool isLegacySubtype(universe, Rti s, Rti t) {
-  return _isSubtype(universe, s, null, t, null, true);
-}
-
-bool isNnbdSubtype(universe, Rti s, Rti t) {
-  return _isSubtype(universe, s, null, t, null, false);
+bool isSubtype(universe, Rti s, Rti t) {
+  return _isSubtype(universe, s, null, t, null);
 }
 
 /// Based on
@@ -2371,18 +2359,20 @@
 /// the bottom of the type hierarchy, `Object` is treated as nullable, and
 /// `required` is ignored on named parameters. This should provide the same
 /// subtyping results as pre-NNBD Dart.
-bool _isSubtype(universe, Rti s, sEnv, Rti t, tEnv, bool isLegacy) {
+bool _isSubtype(universe, Rti s, sEnv, Rti t, tEnv) {
+  bool isLegacy = JS_GET_FLAG('LEGACY');
+
   // Reflexivity:
   if (_Utils.isIdentical(s, t)) return true;
 
   // Right Top:
-  if (isTopType(t, isLegacy)) return true;
+  if (isTopType(t)) return true;
 
   int sKind = Rti._getKind(s);
   if (sKind == Rti.kindAny) return true;
 
   // Left Top:
-  if (isTopType(s, isLegacy)) return false;
+  if (isTopType(s)) return false;
 
   // Left Bottom:
   if (isLegacy) {
@@ -2396,7 +2386,7 @@
   if (leftTypeVariable) {
     int index = Rti._getGenericFunctionParameterIndex(s);
     Rti bound = _castToRti(_Utils.arrayAt(sEnv, index));
-    if (_isSubtype(universe, bound, sEnv, t, tEnv, isLegacy)) return true;
+    if (_isSubtype(universe, bound, sEnv, t, tEnv)) return true;
   }
 
   int tKind = Rti._getKind(t);
@@ -2406,8 +2396,7 @@
   // reduce casework.
   if (!isLegacy && isNullType(s)) {
     if (tKind == Rti.kindFutureOr) {
-      return _isSubtype(
-          universe, s, sEnv, Rti._getFutureOrArgument(t), tEnv, isLegacy);
+      return _isSubtype(universe, s, sEnv, Rti._getFutureOrArgument(t), tEnv);
     }
     return isNullType(t) || tKind == Rti.kindQuestion || tKind == Rti.kindStar;
   }
@@ -2415,20 +2404,17 @@
   // Right Object:
   if (!isLegacy && isObjectType(t)) {
     if (sKind == Rti.kindFutureOr) {
-      return _isSubtype(
-          universe, Rti._getFutureOrArgument(s), sEnv, t, tEnv, isLegacy);
+      return _isSubtype(universe, Rti._getFutureOrArgument(s), sEnv, t, tEnv);
     }
     if (sKind == Rti.kindStar) {
-      return _isSubtype(
-          universe, Rti._getStarArgument(s), sEnv, t, tEnv, isLegacy);
+      return _isSubtype(universe, Rti._getStarArgument(s), sEnv, t, tEnv);
     }
     return sKind != Rti.kindQuestion;
   }
 
   // Left Legacy:
   if (sKind == Rti.kindStar) {
-    return _isSubtype(
-        universe, Rti._getStarArgument(s), sEnv, t, tEnv, isLegacy);
+    return _isSubtype(universe, Rti._getStarArgument(s), sEnv, t, tEnv);
   }
 
   // Right Legacy:
@@ -2440,26 +2426,23 @@
         isLegacy
             ? Rti._getStarArgument(t)
             : Rti._getQuestionFromStar(universe, t),
-        tEnv,
-        isLegacy);
+        tEnv);
   }
 
   // Left FutureOr:
   if (sKind == Rti.kindFutureOr) {
-    if (!_isSubtype(
-        universe, Rti._getFutureOrArgument(s), sEnv, t, tEnv, isLegacy)) {
+    if (!_isSubtype(universe, Rti._getFutureOrArgument(s), sEnv, t, tEnv)) {
       return false;
     }
-    return _isSubtype(universe, Rti._getFutureFromFutureOr(universe, s), sEnv,
-        t, tEnv, isLegacy);
+    return _isSubtype(
+        universe, Rti._getFutureFromFutureOr(universe, s), sEnv, t, tEnv);
   }
 
   // Left Nullable:
   if (sKind == Rti.kindQuestion) {
     return (isLegacy ||
-            _isSubtype(universe, TYPE_REF<Null>(), sEnv, t, tEnv, isLegacy)) &&
-        _isSubtype(
-            universe, Rti._getQuestionArgument(s), sEnv, t, tEnv, isLegacy);
+            _isSubtype(universe, TYPE_REF<Null>(), sEnv, t, tEnv)) &&
+        _isSubtype(universe, Rti._getQuestionArgument(s), sEnv, t, tEnv);
   }
 
   // Type Variable Reflexivity 1 is subsumed by Reflexivity and therefore
@@ -2469,20 +2452,18 @@
 
   // Right FutureOr:
   if (tKind == Rti.kindFutureOr) {
-    if (_isSubtype(
-        universe, s, sEnv, Rti._getFutureOrArgument(t), tEnv, isLegacy)) {
+    if (_isSubtype(universe, s, sEnv, Rti._getFutureOrArgument(t), tEnv)) {
       return true;
     }
-    return _isSubtype(universe, s, sEnv,
-        Rti._getFutureFromFutureOr(universe, t), tEnv, isLegacy);
+    return _isSubtype(
+        universe, s, sEnv, Rti._getFutureFromFutureOr(universe, t), tEnv);
   }
 
   // Right Nullable:
   if (tKind == Rti.kindQuestion) {
     return (!isLegacy &&
-            _isSubtype(universe, s, sEnv, TYPE_REF<Null>(), tEnv, isLegacy)) ||
-        _isSubtype(
-            universe, s, sEnv, Rti._getQuestionArgument(t), tEnv, isLegacy);
+            _isSubtype(universe, s, sEnv, TYPE_REF<Null>(), tEnv)) ||
+        _isSubtype(universe, s, sEnv, Rti._getQuestionArgument(t), tEnv);
   }
 
   // Left Promoted Variable does not apply at runtime.
@@ -2505,37 +2486,47 @@
 
     var sBounds = Rti._getGenericFunctionBounds(s);
     var tBounds = Rti._getGenericFunctionBounds(t);
-    if (!typesEqual(sBounds, tBounds, isLegacy)) return false;
+    int sLength = _Utils.arrayLength(sBounds);
+    int tLength = _Utils.arrayLength(tBounds);
+    if (sLength != tLength) return false;
+    for (int i = 0; i < sLength; i++) {
+      var sBound = _Utils.arrayAt(sBounds, i);
+      var tBound = _Utils.arrayAt(tBounds, i);
+      if (!_isSubtype(universe, sBound, sEnv, tBound, tEnv) ||
+          !_isSubtype(universe, tBound, tEnv, sBound, sEnv)) {
+        return false;
+      }
+    }
 
     sEnv = sEnv == null ? sBounds : _Utils.arrayConcat(sBounds, sEnv);
     tEnv = tEnv == null ? tBounds : _Utils.arrayConcat(tBounds, tEnv);
 
     return _isFunctionSubtype(universe, Rti._getGenericFunctionBase(s), sEnv,
-        Rti._getGenericFunctionBase(t), tEnv, isLegacy);
+        Rti._getGenericFunctionBase(t), tEnv);
   }
   if (tKind == Rti.kindFunction) {
     if (isJsFunctionType(s)) return true;
     if (sKind != Rti.kindFunction) return false;
-    return _isFunctionSubtype(universe, s, sEnv, t, tEnv, isLegacy);
+    return _isFunctionSubtype(universe, s, sEnv, t, tEnv);
   }
 
   // Interface Compositionality + Super-Interface:
   if (sKind == Rti.kindInterface) {
     if (tKind != Rti.kindInterface) return false;
-    return _isInterfaceSubtype(universe, s, sEnv, t, tEnv, isLegacy);
+    return _isInterfaceSubtype(universe, s, sEnv, t, tEnv);
   }
 
   return false;
 }
 
 // TODO(fishythefish): Support required named parameters.
-bool _isFunctionSubtype(universe, Rti s, sEnv, Rti t, tEnv, bool isLegacy) {
+bool _isFunctionSubtype(universe, Rti s, sEnv, Rti t, tEnv) {
   assert(Rti._getKind(s) == Rti.kindFunction);
   assert(Rti._getKind(t) == Rti.kindFunction);
 
   Rti sReturnType = Rti._getReturnType(s);
   Rti tReturnType = Rti._getReturnType(t);
-  if (!_isSubtype(universe, sReturnType, sEnv, tReturnType, tEnv, isLegacy)) {
+  if (!_isSubtype(universe, sReturnType, sEnv, tReturnType, tEnv)) {
     return false;
   }
 
@@ -2564,7 +2555,7 @@
   for (int i = 0; i < sRequiredPositionalLength; i++) {
     Rti sParameter = _castToRti(_Utils.arrayAt(sRequiredPositional, i));
     Rti tParameter = _castToRti(_Utils.arrayAt(tRequiredPositional, i));
-    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv, isLegacy)) {
+    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv)) {
       return false;
     }
   }
@@ -2573,7 +2564,7 @@
     Rti sParameter = _castToRti(_Utils.arrayAt(sOptionalPositional, i));
     Rti tParameter = _castToRti(
         _Utils.arrayAt(tRequiredPositional, sRequiredPositionalLength + i));
-    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv, isLegacy)) {
+    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv)) {
       return false;
     }
   }
@@ -2582,7 +2573,7 @@
     Rti sParameter = _castToRti(
         _Utils.arrayAt(sOptionalPositional, requiredPositionalDelta + i));
     Rti tParameter = _castToRti(_Utils.arrayAt(tOptionalPositional, i));
-    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv, isLegacy)) {
+    if (!_isSubtype(universe, tParameter, tEnv, sParameter, sEnv)) {
       return false;
     }
   }
@@ -2603,13 +2594,13 @@
     if (_Utils.stringLessThan(tName, sName)) return false;
     Rti sType = _castToRti(_Utils.arrayAt(sOptionalNamed, i - 1));
     Rti tType = _castToRti(_Utils.arrayAt(tOptionalNamed, j + 1));
-    if (!_isSubtype(universe, tType, tEnv, sType, sEnv, isLegacy)) return false;
+    if (!_isSubtype(universe, tType, tEnv, sType, sEnv)) return false;
   }
 
   return true;
 }
 
-bool _isInterfaceSubtype(universe, Rti s, sEnv, Rti t, tEnv, bool isLegacy) {
+bool _isInterfaceSubtype(universe, Rti s, sEnv, Rti t, tEnv) {
   String sName = Rti._getInterfaceName(s);
   String tName = Rti._getInterfaceName(t);
 
@@ -2638,18 +2629,18 @@
         switch (sVariance) {
           case Variance.legacyCovariant:
           case Variance.covariant:
-            if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv, isLegacy)) {
+            if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv)) {
               return false;
             }
             break;
           case Variance.contravariant:
-            if (!_isSubtype(universe, tArg, tEnv, sArg, sEnv, isLegacy)) {
+            if (!_isSubtype(universe, tArg, tEnv, sArg, sEnv)) {
               return false;
             }
             break;
           case Variance.invariant:
-            if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv, isLegacy) ||
-                !_isSubtype(universe, tArg, tEnv, sArg, sEnv, isLegacy)) {
+            if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv) ||
+                !_isSubtype(universe, tArg, tEnv, sArg, sEnv)) {
               return false;
             }
             break;
@@ -2658,7 +2649,7 @@
                 "Unknown variance given for subtype check: $sVariance");
         }
       } else {
-        if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv, isLegacy)) {
+        if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv)) {
           return false;
         }
       }
@@ -2687,102 +2678,15 @@
     String recipe = _Utils.asString(_Utils.arrayAt(supertypeArgs, i));
     Rti supertypeArg = _Universe.evalInEnvironment(universe, s, recipe);
     Rti tArg = _castToRti(_Utils.arrayAt(tArgs, i));
-    if (!_isSubtype(universe, supertypeArg, sEnv, tArg, tEnv, isLegacy)) {
+    if (!_isSubtype(universe, supertypeArg, sEnv, tArg, tEnv)) {
       return false;
     }
   }
   return true;
 }
 
-/// Types are equal if they are structurally equal up to renaming of bound type
-/// variables and equating all top types.
-///
-/// We ignore renaming of bound type variables because we operate on de Bruijn
-/// indices, not names.
-bool typeEqual(Rti s, Rti t, bool isLegacy) {
-  if (_Utils.isIdentical(s, t)) return true;
-
-  if (isTopType(s, isLegacy)) return isTopType(t, isLegacy);
-
-  int sKind = Rti._getKind(s);
-  int tKind = Rti._getKind(t);
-  if (sKind != tKind) return false;
-
-  switch (sKind) {
-    case Rti.kindStar:
-    case Rti.kindQuestion:
-    case Rti.kindFutureOr:
-      return typeEqual(_castToRti(Rti._getPrimary(s)),
-          _castToRti(Rti._getPrimary(t)), isLegacy);
-
-    case Rti.kindInterface:
-      if (Rti._getInterfaceName(s) != Rti._getInterfaceName(t)) return false;
-      return typesEqual(Rti._getInterfaceTypeArguments(s),
-          Rti._getInterfaceTypeArguments(t), isLegacy);
-
-    case Rti.kindBinding:
-      return typeEqual(
-              Rti._getBindingBase(s), Rti._getBindingBase(t), isLegacy) &&
-          typesEqual(Rti._getBindingArguments(s), Rti._getBindingArguments(t),
-              isLegacy);
-
-    case Rti.kindFunction:
-      return typeEqual(
-              Rti._getReturnType(s), Rti._getReturnType(t), isLegacy) &&
-          functionParametersEqual(Rti._getFunctionParameters(s),
-              Rti._getFunctionParameters(t), isLegacy);
-
-    case Rti.kindGenericFunction:
-      return typeEqual(Rti._getGenericFunctionBase(s),
-              Rti._getGenericFunctionBase(t), isLegacy) &&
-          typesEqual(Rti._getGenericFunctionBounds(s),
-              Rti._getGenericFunctionBounds(t), isLegacy);
-
-    default:
-      return false;
-  }
-}
-
-bool typesEqual(Object sArray, Object tArray, isLegacy) {
-  int sLength = _Utils.arrayLength(sArray);
-  int tLength = _Utils.arrayLength(tArray);
-  if (sLength != tLength) return false;
-  for (int i = 0; i < sLength; i++) {
-    if (!typeEqual(_castToRti(_Utils.arrayAt(sArray, i)),
-        _castToRti(_Utils.arrayAt(tArray, i)), isLegacy)) return false;
-  }
-  return true;
-}
-
-bool namedTypesEqual(Object sArray, Object tArray, isLegacy) {
-  int sLength = _Utils.arrayLength(sArray);
-  int tLength = _Utils.arrayLength(tArray);
-  assert(sLength.isEven);
-  assert(tLength.isEven);
-  if (sLength != tLength) return false;
-  for (int i = 0; i < sLength; i += 2) {
-    if (_Utils.asString(_Utils.arrayAt(sArray, i)) !=
-        _Utils.asString(_Utils.arrayAt(tArray, i))) return false;
-    if (!typeEqual(_castToRti(_Utils.arrayAt(sArray, i + 1)),
-        _castToRti(_Utils.arrayAt(tArray, i + 1)), isLegacy)) return false;
-  }
-  return true;
-}
-
-// TODO(fishythefish): Support required named parameters.
-bool functionParametersEqual(_FunctionParameters sParameters,
-        _FunctionParameters tParameters, isLegacy) =>
-    typesEqual(_FunctionParameters._getRequiredPositional(sParameters),
-        _FunctionParameters._getRequiredPositional(tParameters), isLegacy) &&
-    typesEqual(_FunctionParameters._getOptionalPositional(sParameters),
-        _FunctionParameters._getOptionalPositional(tParameters), isLegacy) &&
-    namedTypesEqual(_FunctionParameters._getOptionalNamed(sParameters),
-        _FunctionParameters._getOptionalNamed(tParameters), isLegacy);
-
-bool isLegacyTopType(Rti t) => isTopType(t, true);
-bool isNnbdTopType(Rti t) => isTopType(t, false);
-bool isTopType(Rti t, bool isLegacy) {
-  if (isLegacy) {
+bool isTopType(Rti t) {
+  if (JS_GET_FLAG('LEGACY')) {
     if (isObjectType(t)) return true;
   } else {
     if (isNullableObjectType(t)) return true;
@@ -2792,8 +2696,7 @@
       kind == Rti.kindVoid ||
       kind == Rti.kindAny ||
       kind == Rti.kindErased ||
-      kind == Rti.kindFutureOr &&
-          isTopType(Rti._getFutureOrArgument(t), isLegacy);
+      kind == Rti.kindFutureOr && isTopType(Rti._getFutureOrArgument(t));
 }
 
 bool isObjectType(Rti t) => _Utils.isIdentical(t, TYPE_REF<Object>());
@@ -2900,8 +2803,8 @@
   _Universe.addTypeParameterVariances(universe, variances);
 }
 
-bool testingIsLegacySubtype(universe, rti1, rti2) {
-  return isLegacySubtype(universe, _castToRti(rti1), _castToRti(rti2));
+bool testingIsSubtype(universe, rti1, rti2) {
+  return isSubtype(universe, _castToRti(rti1), _castToRti(rti2));
 }
 
 Object testingUniverseEval(universe, String recipe) {
diff --git a/sdk_nnbd/lib/_internal/vm/bin/common_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/common_patch.dart
index f974bae..1bcd089 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/common_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/common_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 /// Note: the VM concatenates all patch files into a single patch file. This
 /// file is the first patch in "dart:io" which contains all the imports used by
 /// patches of that library. We plan to change this when we have a shared front
diff --git a/sdk_nnbd/lib/_internal/vm/bin/directory_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/directory_patch.dart
index 951bd09..7549f72 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/directory_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/directory_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 @patch
diff --git a/sdk_nnbd/lib/_internal/vm/bin/eventhandler_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/eventhandler_patch.dart
index abc5e21..11ada47 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/eventhandler_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/eventhandler_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 @patch
diff --git a/sdk_nnbd/lib/_internal/vm/bin/file_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/file_patch.dart
index fa5e9ab..5dde072 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/file_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/file_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 @patch
@@ -76,9 +74,9 @@
   int close() native "File_Close";
   readByte() native "File_ReadByte";
   read(int bytes) native "File_Read";
-  readInto(List<int> buffer, int start, int end) native "File_ReadInto";
+  readInto(List<int> buffer, int start, int? end) native "File_ReadInto";
   writeByte(int value) native "File_WriteByte";
-  writeFrom(List<int> buffer, int start, int end) native "File_WriteFrom";
+  writeFrom(List<int> buffer, int start, int? end) native "File_WriteFrom";
   position() native "File_Position";
   setPosition(int position) native "File_SetPosition";
   truncate(int length) native "File_Truncate";
@@ -96,19 +94,20 @@
 }
 
 @patch
-class _FileSystemWatcher {
+abstract class _FileSystemWatcher {
   void _pathWatchedEnd();
 
-  static int _id;
+  static int? _id;
   static final Map<int, _WatcherPath> _idMap = {};
 
   final String _path;
   final int _events;
   final bool _recursive;
 
-  _WatcherPath _watcherPath;
+  _WatcherPath? _watcherPath;
 
-  StreamController<FileSystemEvent> _broadcastController;
+  final StreamController<FileSystemEvent> _broadcastController =
+      new StreamController<FileSystemEvent>.broadcast();
 
   @patch
   static Stream<FileSystemEvent> _watch(
@@ -132,8 +131,9 @@
       throw new FileSystemException(
           "File system watching is not supported on this platform", _path);
     }
-    _broadcastController = new StreamController<FileSystemEvent>.broadcast(
-        onListen: _listen, onCancel: _cancel);
+    _broadcastController
+      ..onListen = _listen
+      ..onCancel = _cancel;
   }
 
   Stream<FileSystemEvent> get _stream => _broadcastController.stream;
@@ -153,7 +153,7 @@
     var pathId;
     try {
       pathId =
-          _watchPath(_id, _Namespace._namespace, _path, _events, _recursive);
+          _watchPath(_id!, _Namespace._namespace, _path, _events, _recursive);
     } catch (e) {
       _broadcastController
           .addError(new FileSystemException("Failed to watch path", _path, e));
@@ -164,23 +164,25 @@
       _idMap[pathId] = new _WatcherPath(pathId, _path, _events);
     }
     _watcherPath = _idMap[pathId];
-    _watcherPath.count++;
+    _watcherPath!.count++;
     _pathWatched().pipe(_broadcastController);
   }
 
   void _cancel() {
-    if (_watcherPath != null) {
-      assert(_watcherPath.count > 0);
-      _watcherPath.count--;
-      if (_watcherPath.count == 0) {
-        _unwatchPath(_id, _watcherPath.pathId);
+    final watcherPath = _watcherPath;
+    if (watcherPath != null) {
+      assert(watcherPath.count > 0);
+      watcherPath.count--;
+      if (watcherPath.count == 0) {
+        _unwatchPath(_id!, watcherPath.pathId);
         _pathWatchedEnd();
-        _idMap.remove(_watcherPath.pathId);
+        _idMap.remove(watcherPath.pathId);
       }
       _watcherPath = null;
     }
-    if (_idMap.isEmpty && _id != null) {
-      _closeWatcher(_id);
+    final id = _id;
+    if (_idMap.isEmpty && id != null) {
+      _closeWatcher(id);
       _doneWatcher();
       _id = null;
     }
@@ -196,7 +198,7 @@
   void _donePathWatched() {}
 
   static _WatcherPath _pathFromPathId(int pathId) {
-    return _idMap[pathId];
+    return _idMap[pathId]!;
   }
 
   static Stream _listenOnSocket(int socketId, int id, int pathId) {
@@ -305,7 +307,7 @@
           var path = _pathFromPathId(pathId).path;
           _idMap.remove(pathId);
           if (_idMap.isEmpty && _id != null) {
-            _closeWatcher(_id);
+            _closeWatcher(_id!);
             _id = null;
           }
           throw FileSystemException(
@@ -337,20 +339,20 @@
 
 class _InotifyFileSystemWatcher extends _FileSystemWatcher {
   static final Map<int, StreamController> _idMap = {};
-  static StreamSubscription _subscription;
+  static late StreamSubscription _subscription;
 
   _InotifyFileSystemWatcher(path, events, recursive)
       : super._(path, events, recursive);
 
   void _newWatcher() {
-    int id = _FileSystemWatcher._id;
+    int id = _FileSystemWatcher._id!;
     _subscription =
         _FileSystemWatcher._listenOnSocket(id, id, 0).listen((event) {
       if (_idMap.containsKey(event[0])) {
         if (event[1] != null) {
-          _idMap[event[0]].add(event[1]);
+          _idMap[event[0]]!.add(event[1]);
         } else {
-          _idMap[event[0]].close();
+          _idMap[event[0]]!.close();
         }
       }
     });
@@ -361,30 +363,30 @@
   }
 
   Stream _pathWatched() {
-    var pathId = _watcherPath.pathId;
+    var pathId = _watcherPath!.pathId;
     if (!_idMap.containsKey(pathId)) {
       _idMap[pathId] = new StreamController<FileSystemEvent>.broadcast();
     }
-    return _idMap[pathId].stream;
+    return _idMap[pathId]!.stream;
   }
 
   void _pathWatchedEnd() {
-    var pathId = _watcherPath.pathId;
+    var pathId = _watcherPath!.pathId;
     if (!_idMap.containsKey(pathId)) return;
-    _idMap[pathId].close();
+    _idMap[pathId]!.close();
     _idMap.remove(pathId);
   }
 }
 
 class _Win32FileSystemWatcher extends _FileSystemWatcher {
-  StreamSubscription _subscription;
-  StreamController _controller;
+  late StreamSubscription _subscription;
+  late StreamController _controller;
 
   _Win32FileSystemWatcher(path, events, recursive)
       : super._(path, events, recursive);
 
   Stream _pathWatched() {
-    var pathId = _watcherPath.pathId;
+    var pathId = _watcherPath!.pathId;
     _controller = new StreamController<FileSystemEvent>();
     _subscription =
         _FileSystemWatcher._listenOnSocket(pathId, 0, pathId).listen((event) {
@@ -405,14 +407,14 @@
 }
 
 class _FSEventStreamFileSystemWatcher extends _FileSystemWatcher {
-  StreamSubscription _subscription;
-  StreamController _controller;
+  late StreamSubscription _subscription;
+  late StreamController _controller;
 
   _FSEventStreamFileSystemWatcher(path, events, recursive)
       : super._(path, events, recursive);
 
   Stream _pathWatched() {
-    var pathId = _watcherPath.pathId;
+    var pathId = _watcherPath!.pathId;
     var socketId = _FileSystemWatcher._getSocketId(0, pathId);
     _controller = new StreamController<FileSystemEvent>();
     _subscription =
diff --git a/sdk_nnbd/lib/_internal/vm/bin/file_system_entity_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/file_system_entity_patch.dart
index 841219e..973e6b6 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/file_system_entity_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/file_system_entity_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 @patch
diff --git a/sdk_nnbd/lib/_internal/vm/bin/filter_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/filter_patch.dart
index a31f838..2bcf5a9 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/filter_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/filter_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 class _FilterImpl extends NativeFieldWrapperClass1 implements RawZLibFilter {
@@ -14,20 +12,20 @@
 }
 
 class _ZLibInflateFilter extends _FilterImpl {
-  _ZLibInflateFilter(int windowBits, List<int> dictionary, bool raw) {
+  _ZLibInflateFilter(int windowBits, List<int>? dictionary, bool raw) {
     _init(windowBits, dictionary, raw);
   }
-  void _init(int windowBits, List<int> dictionary, bool raw)
+  void _init(int windowBits, List<int>? dictionary, bool raw)
       native "Filter_CreateZLibInflate";
 }
 
 class _ZLibDeflateFilter extends _FilterImpl {
   _ZLibDeflateFilter(bool gzip, int level, int windowBits, int memLevel,
-      int strategy, List<int> dictionary, bool raw) {
+      int strategy, List<int>? dictionary, bool raw) {
     _init(gzip, level, windowBits, memLevel, strategy, dictionary, raw);
   }
   void _init(bool gzip, int level, int windowBits, int memLevel, int strategy,
-      List<int> dictionary, bool raw) native "Filter_CreateZLibDeflate";
+      List<int>? dictionary, bool raw) native "Filter_CreateZLibDeflate";
 }
 
 @patch
@@ -39,12 +37,12 @@
           int windowBits,
           int memLevel,
           int strategy,
-          List<int> dictionary,
+          List<int>? dictionary,
           bool raw) =>
       new _ZLibDeflateFilter(
           gzip, level, windowBits, memLevel, strategy, dictionary, raw);
   @patch
   static RawZLibFilter _makeZLibInflateFilter(
-          int windowBits, List<int> dictionary, bool raw) =>
+          int windowBits, List<int>? dictionary, bool raw) =>
       new _ZLibInflateFilter(windowBits, dictionary, raw);
 }
diff --git a/sdk_nnbd/lib/_internal/vm/bin/io_service_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/io_service_patch.dart
index 9b3dd9f..d54bbf2 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/io_service_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/io_service_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 class _IOServicePorts {
@@ -36,7 +34,7 @@
   }
 
   void _returnPort(int forRequestId) {
-    final SendPort port = _usedPorts.remove(forRequestId);
+    final SendPort port = _usedPorts.remove(forRequestId)!;
     if (!_usedPorts.values.contains(port)) {
       _freePorts.add(port);
     }
@@ -48,8 +46,8 @@
 @patch
 class _IOService {
   static _IOServicePorts _servicePorts = new _IOServicePorts();
-  static RawReceivePort _receivePort;
-  static SendPort _replyToPort;
+  static RawReceivePort? _receivePort;
+  static late SendPort _replyToPort;
   static HashMap<int, Completer> _messageMap = new HashMap<int, Completer>();
   static int _id = 0;
 
@@ -66,7 +64,7 @@
     try {
       servicePort.send(<dynamic>[id, _replyToPort, request, data]);
     } catch (error) {
-      _messageMap.remove(id).complete(error);
+      _messageMap.remove(id)!.complete(error);
       if (_messageMap.length == 0) {
         _finalize();
       }
@@ -77,10 +75,10 @@
   static void _ensureInitialize() {
     if (_receivePort == null) {
       _receivePort = new RawReceivePort();
-      _replyToPort = _receivePort.sendPort;
-      _receivePort.handler = (data) {
+      _replyToPort = _receivePort!.sendPort;
+      _receivePort!.handler = (data) {
         assert(data is List && data.length == 2);
-        _messageMap.remove(data[0]).complete(data[1]);
+        _messageMap.remove(data[0])!.complete(data[1]);
         _servicePorts._returnPort(data[0]);
         if (_messageMap.length == 0) {
           _finalize();
@@ -91,7 +89,7 @@
 
   static void _finalize() {
     _id = 0;
-    _receivePort.close();
+    _receivePort!.close();
     _receivePort = null;
   }
 
diff --git a/sdk_nnbd/lib/_internal/vm/bin/namespace_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/namespace_patch.dart
index bc8e2df..2cf329f 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/namespace_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/namespace_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 @pragma("vm:entry-point")
 class _NamespaceImpl extends NativeFieldWrapperClass1 implements _Namespace {
   _NamespaceImpl._();
@@ -16,7 +14,7 @@
 
   // If the platform supports "namespaces", this method is called by the
   // embedder with the platform-specific namespace information.
-  static _NamespaceImpl _cachedNamespace = null;
+  static _NamespaceImpl? _cachedNamespace = null;
   static void _setupNamespace(var namespace) {
     _cachedNamespace = _create(new _NamespaceImpl._(), namespace);
   }
@@ -27,7 +25,7 @@
       // instead use a safe-ish default value.
       _cachedNamespace = _create(new _NamespaceImpl._(), _getDefault());
     }
-    return _cachedNamespace;
+    return _cachedNamespace!;
   }
 
   static int get _namespacePointer => _getPointer(_namespace);
diff --git a/sdk_nnbd/lib/_internal/vm/bin/platform_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/platform_patch.dart
index 88c10bd..d187101 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/platform_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/platform_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 @patch
@@ -35,9 +33,9 @@
   static String _localeName() native "Platform_LocaleName";
 
   @patch
-  static String _packageRoot() => VMLibraryHooks.packageRootString;
+  static String? _packageRoot() => VMLibraryHooks.packageRootString;
   @patch
-  static String _packageConfig() => VMLibraryHooks.packageConfigString;
+  static String? _packageConfig() => VMLibraryHooks.packageConfigString;
 
   @patch
   static Uri _script() => VMLibraryHooks.platformScript;
diff --git a/sdk_nnbd/lib/_internal/vm/bin/process_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/process_patch.dart
index 8589244..49592e7 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/process_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/process_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 @patch
@@ -22,8 +20,8 @@
 class Process {
   @patch
   static Future<Process> start(String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment: true,
       bool runInShell: false,
       ProcessStartMode mode: ProcessStartMode.normal}) {
@@ -40,12 +38,12 @@
 
   @patch
   static Future<ProcessResult> run(String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment: true,
       bool runInShell: false,
-      Encoding stdoutEncoding: systemEncoding,
-      Encoding stderrEncoding: systemEncoding}) {
+      Encoding? stdoutEncoding: systemEncoding,
+      Encoding? stderrEncoding: systemEncoding}) {
     return _runNonInteractiveProcess(
         executable,
         arguments,
@@ -59,12 +57,12 @@
 
   @patch
   static ProcessResult runSync(String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment: true,
       bool runInShell: false,
-      Encoding stdoutEncoding: systemEncoding,
-      Encoding stderrEncoding: systemEncoding}) {
+      Encoding? stdoutEncoding: systemEncoding,
+      Encoding? stderrEncoding: systemEncoding}) {
     return _runNonInteractiveProcessSync(
         executable,
         arguments,
@@ -78,24 +76,24 @@
 
   @patch
   static bool killPid(int pid, [ProcessSignal signal = ProcessSignal.sigterm]) {
-    if (signal is! ProcessSignal) {
-      throw new ArgumentError("Argument 'signal' must be a ProcessSignal");
-    }
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(signal, "signal");
     return _ProcessUtils._killPid(pid, signal._signalNumber);
   }
 }
 
-List<_SignalController> _signalControllers = new List.filled(32, null);
+List<_SignalController?> _signalControllers = new List.filled(32, null);
 
 class _SignalController {
   final ProcessSignal signal;
 
-  StreamController<ProcessSignal> _controller;
+  final _controller = new StreamController<ProcessSignal>.broadcast();
   var _id;
 
   _SignalController(this.signal) {
-    _controller = new StreamController<ProcessSignal>.broadcast(
-        onListen: _listen, onCancel: _cancel);
+    _controller
+      ..onListen = _listen
+      ..onCancel = _cancel;
   }
 
   Stream<ProcessSignal> get stream => _controller.stream;
@@ -111,7 +109,7 @@
     var socket = new _RawSocket(new _NativeSocket.watchSignal(id));
     socket.listen((event) {
       if (event == RawSocketEvent.read) {
-        var bytes = socket.read();
+        var bytes = socket.read()!;
         for (int i = 0; i < bytes.length; i++) {
           _controller.add(signal);
         }
@@ -145,7 +143,7 @@
   @patch
   static void _sleep(int millis) native "Process_Sleep";
   @patch
-  static int _pid(Process process) native "Process_Pid";
+  static int _pid(Process? process) native "Process_Pid";
   static bool _killPid(int pid, int signal) native "Process_KillPid";
   @patch
   static Stream<ProcessSignal> _watchSignal(ProcessSignal signal) {
@@ -166,7 +164,7 @@
     if (_signalControllers[signal._signalNumber] == null) {
       _signalControllers[signal._signalNumber] = new _SignalController(signal);
     }
-    return _signalControllers[signal._signalNumber].stream;
+    return _signalControllers[signal._signalNumber]!.stream;
   }
 }
 
@@ -197,9 +195,9 @@
 @pragma("vm:entry-point")
 class _ProcessStartStatus {
   @pragma("vm:entry-point", "set")
-  int _errorCode; // Set to OS error code if process start failed.
+  int? _errorCode; // Set to OS error code if process start failed.
   @pragma("vm:entry-point", "set")
-  String _errorMessage; // Set to OS error message if process start failed.
+  String? _errorMessage; // Set to OS error message if process start failed.
 }
 
 // The NativeFieldWrapperClass1 can not be used with a mixin, due to missing
@@ -207,18 +205,25 @@
 class _ProcessImplNativeWrapper extends NativeFieldWrapperClass1 {}
 
 class _ProcessImpl extends _ProcessImplNativeWrapper implements Process {
-  _ProcessResourceInfo _resourceInfo;
   static bool connectedResourceHandler = false;
 
   _ProcessImpl(
       String path,
       List<String> arguments,
       this._workingDirectory,
-      Map<String, String> environment,
+      Map<String, String>? environment,
       bool includeParentEnvironment,
       bool runInShell,
-      ProcessStartMode mode)
+      this._mode)
       : super() {
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(path, "path");
+    ArgumentError.checkNotNull(arguments, "arguments");
+    for (int i = 0; i < arguments.length; i++) {
+      ArgumentError.checkNotNull(arguments[i], "arguments[]");
+    }
+    ArgumentError.checkNotNull(_mode, "mode");
+
     if (!connectedResourceHandler) {
       registerExtension(
           'ext.dart.io.getProcesses', _ProcessResourceInfo.getStartedProcesses);
@@ -232,10 +237,6 @@
       path = _getShellCommand();
     }
 
-    if (path is! String) {
-      throw new ArgumentError("Path is not a String: $path");
-    }
-
     if (Platform.isWindows && path.contains(' ') && !path.contains('"')) {
       // Escape paths that may contain spaces
       // Bug: https://github.com/dart-lang/sdk/issues/37751
@@ -244,57 +245,29 @@
       _path = path;
     }
 
-    if (arguments is! List) {
-      throw new ArgumentError("Arguments is not a List: $arguments");
-    }
-    int len = arguments.length;
-    _arguments = new List<String>.filled(len, "");
-    for (int i = 0; i < len; i++) {
-      var arg = arguments[i];
-      if (arg is! String) {
-        throw new ArgumentError("Non-string argument: $arg");
-      }
-      _arguments[i] = arguments[i];
-      if (Platform.isWindows) {
-        _arguments[i] = _windowsArgumentEscape(_arguments[i]);
-      }
-    }
-
-    if (_workingDirectory != null && _workingDirectory is! String) {
-      throw new ArgumentError(
-          "WorkingDirectory is not a String: $_workingDirectory");
-    }
+    _arguments = [
+      for (int i = 0; i < arguments.length; i++)
+        Platform.isWindows
+            ? _windowsArgumentEscape(_arguments[i])
+            : arguments[i],
+    ];
 
     _environment = [];
     // Ensure that we have a non-null environment.
-    environment = (environment == null) ? (const {}) : environment;
-    if (environment is! Map) {
-      throw new ArgumentError("Environment is not a map: $environment");
-    }
+    environment ??= const {};
     environment.forEach((key, value) {
-      if (key is! String || value is! String) {
-        throw new ArgumentError(
-            "Environment key or value is not a string: ($key, $value)");
-      }
       _environment.add('$key=$value');
     });
     if (includeParentEnvironment) {
       Platform.environment.forEach((key, value) {
-        assert(key is String);
-        assert(value is String);
         // Do not override keys already set as part of environment.
-        if (!environment.containsKey(key)) {
+        if (!environment!.containsKey(key)) {
           _environment.add('$key=$value');
         }
       });
     }
 
-    if (mode is! ProcessStartMode) {
-      throw new ArgumentError("Mode is not a ProcessStartMode: $mode");
-    }
-    _mode = mode;
-
-    if (_modeHasStdio(mode)) {
+    if (_modeHasStdio(_mode)) {
       // stdin going to process.
       _stdin = new _StdSink(new _Socket._writePipe().._owner = this);
       // stdout coming from process.
@@ -302,19 +275,17 @@
       // stderr coming from process.
       _stderr = new _StdStream(new _Socket._readPipe().._owner = this);
     }
-    if (_modeIsAttached(mode)) {
+    if (_modeIsAttached(_mode)) {
       _exitHandler = new _Socket._readPipe();
     }
-    _ended = false;
-    _started = false;
   }
 
   _NativeSocket get _stdinNativeSocket =>
-      (_stdin._sink as _Socket)._nativeSocket;
+      (_stdin!._sink as _Socket)._nativeSocket;
   _NativeSocket get _stdoutNativeSocket =>
-      (_stdout._stream as _Socket)._nativeSocket;
+      (_stdout!._stream as _Socket)._nativeSocket;
   _NativeSocket get _stderrNativeSocket =>
-      (_stderr._stream as _Socket)._nativeSocket;
+      (_stderr!._stream as _Socket)._nativeSocket;
 
   static bool _modeIsAttached(ProcessStartMode mode) {
     return (mode == ProcessStartMode.normal) ||
@@ -434,12 +405,12 @@
           status);
       if (!success) {
         completer.completeError(new ProcessException(
-            _path, _arguments, status._errorMessage, status._errorCode));
+            _path, _arguments, status._errorMessage!, status._errorCode!));
         return;
       }
 
       _started = true;
-      _resourceInfo = new _ProcessResourceInfo(this);
+      final resourceInfo = new _ProcessResourceInfo(this);
 
       // Setup an exit handler to handle internal cleanup and possible
       // callback when a process terminates.
@@ -457,12 +428,12 @@
 
           void handleExit() {
             _ended = true;
-            _exitCode.complete(exitCode(exitDataBuffer));
+            _exitCode!.complete(exitCode(exitDataBuffer));
             // Kill stdin, helping hand if the user forgot to do it.
             if (_modeHasStdio(_mode)) {
-              (_stdin._sink as _Socket).destroy();
+              (_stdin!._sink as _Socket).destroy();
             }
-            _resourceInfo.stopped();
+            resourceInfo.stopped();
           }
 
           exitDataBuffer.setRange(
@@ -479,7 +450,8 @@
     return completer.future;
   }
 
-  ProcessResult _runAndWait(Encoding stdoutEncoding, Encoding stderrEncoding) {
+  ProcessResult _runAndWait(
+      Encoding? stdoutEncoding, Encoding? stderrEncoding) {
     var status = new _ProcessStartStatus();
     _exitCode = new Completer<int>();
     bool success = _startNative(
@@ -496,10 +468,10 @@
         status);
     if (!success) {
       throw new ProcessException(
-          _path, _arguments, status._errorMessage, status._errorCode);
+          _path, _arguments, status._errorMessage!, status._errorCode!);
     }
 
-    _resourceInfo = new _ProcessResourceInfo(this);
+    final resourceInfo = new _ProcessResourceInfo(this);
 
     var result = _wait(_stdinNativeSocket, _stdoutNativeSocket,
         _stderrNativeSocket, _exitHandler._nativeSocket);
@@ -509,7 +481,7 @@
       return encoding.decode(output);
     }
 
-    _resourceInfo.stopped();
+    resourceInfo.stopped();
 
     return new ProcessResult(
         result[0],
@@ -522,36 +494,32 @@
       _Namespace namespace,
       String path,
       List<String> arguments,
-      String workingDirectory,
+      String? workingDirectory,
       List<String> environment,
       int mode,
-      _NativeSocket stdin,
-      _NativeSocket stdout,
-      _NativeSocket stderr,
-      _NativeSocket exitHandler,
+      _NativeSocket? stdin,
+      _NativeSocket? stdout,
+      _NativeSocket? stderr,
+      _NativeSocket? exitHandler,
       _ProcessStartStatus status) native "Process_Start";
 
-  _wait(_NativeSocket stdin, _NativeSocket stdout, _NativeSocket stderr,
+  _wait(_NativeSocket? stdin, _NativeSocket? stdout, _NativeSocket? stderr,
       _NativeSocket exitHandler) native "Process_Wait";
 
-  Stream<List<int>> get stdout {
-    return _stdout;
-  }
+  Stream<List<int>> get stdout =>
+      _stdout ?? (throw StateError("Process is detached"));
 
-  Stream<List<int>> get stderr {
-    return _stderr;
-  }
+  Stream<List<int>> get stderr =>
+      _stdout ?? (throw StateError("Process is detached"));
 
-  IOSink get stdin {
-    return _stdin;
-  }
+  IOSink get stdin => _stdin ?? (throw StateError("Process is detached"));
 
-  Future<int> get exitCode => _exitCode != null ? _exitCode.future : null;
+  Future<int> get exitCode =>
+      _exitCode?.future ?? (throw StateError("Process is detached"));
 
   bool kill([ProcessSignal signal = ProcessSignal.sigterm]) {
-    if (signal is! ProcessSignal) {
-      throw new ArgumentError("Argument 'signal' must be a ProcessSignal");
-    }
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(kill, "kill");
     assert(_started);
     if (_ended) return false;
     return _ProcessUtils._killPid(pid, signal._signalNumber);
@@ -559,19 +527,19 @@
 
   int get pid => _ProcessUtils._pid(this);
 
-  String _path;
-  List<String> _arguments;
-  String _workingDirectory;
-  List<String> _environment;
-  ProcessStartMode _mode;
+  late String _path;
+  late List<String> _arguments;
+  String? _workingDirectory;
+  late List<String> _environment;
+  final ProcessStartMode _mode;
   // Private methods of Socket are used by _in, _out, and _err.
-  _StdSink _stdin;
-  _StdStream _stdout;
-  _StdStream _stderr;
-  _Socket _exitHandler;
-  bool _ended;
-  bool _started;
-  Completer<int> _exitCode;
+  _StdSink? _stdin;
+  _StdStream? _stdout;
+  _StdStream? _stderr;
+  late _Socket _exitHandler;
+  bool _ended = false;
+  bool _started = false;
+  Completer<int>? _exitCode;
 }
 
 // _NonInteractiveProcess is a wrapper around an interactive process
@@ -581,12 +549,12 @@
 Future<ProcessResult> _runNonInteractiveProcess(
     String path,
     List<String> arguments,
-    String workingDirectory,
-    Map<String, String> environment,
+    String? workingDirectory,
+    Map<String, String>? environment,
     bool includeParentEnvironment,
     bool runInShell,
-    Encoding stdoutEncoding,
-    Encoding stderrEncoding) {
+    Encoding? stdoutEncoding,
+    Encoding? stderrEncoding) {
   // Start the underlying process.
   return Process.start(path, arguments,
           workingDirectory: workingDirectory,
@@ -600,7 +568,7 @@
     p.stdin.close();
 
     // Setup stdout and stderr handling.
-    Future foldStream(Stream<List<int>> stream, Encoding encoding) {
+    Future foldStream(Stream<List<int>> stream, Encoding? encoding) {
       if (encoding == null) {
         return stream
             .fold(new BytesBuilder(), (builder, data) => builder..add(data))
@@ -626,12 +594,12 @@
 ProcessResult _runNonInteractiveProcessSync(
     String executable,
     List<String> arguments,
-    String workingDirectory,
-    Map<String, String> environment,
+    String? workingDirectory,
+    Map<String, String>? environment,
     bool includeParentEnvironment,
     bool runInShell,
-    Encoding stdoutEncoding,
-    Encoding stderrEncoding) {
+    Encoding? stdoutEncoding,
+    Encoding? stderrEncoding) {
   var process = new _ProcessImpl(
       executable,
       arguments,
diff --git a/sdk_nnbd/lib/_internal/vm/bin/secure_socket_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/secure_socket_patch.dart
index af22246..69cc88a 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/secure_socket_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/secure_socket_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 @patch
@@ -28,7 +26,7 @@
 }
 
 class _SecureSocket extends _Socket implements SecureSocket {
-  _RawSecureSocket get _raw => super._raw as _RawSecureSocket;
+  _RawSecureSocket? get _raw => super._raw as _RawSecureSocket?;
 
   _SecureSocket(RawSecureSocket raw) : super(raw);
 
@@ -36,24 +34,24 @@
       {bool useSessionCache: true,
       bool requestClientCertificate: false,
       bool requireClientCertificate: false}) {
-    _raw.renegotiate(
+    _raw!.renegotiate(
         useSessionCache: useSessionCache,
         requestClientCertificate: requestClientCertificate,
         requireClientCertificate: requireClientCertificate);
   }
 
-  X509Certificate get peerCertificate {
+  X509Certificate? get peerCertificate {
     if (_raw == null) {
       throw new StateError("peerCertificate called on destroyed SecureSocket");
     }
-    return _raw.peerCertificate;
+    return _raw!.peerCertificate;
   }
 
-  String get selectedProtocol {
+  String? get selectedProtocol {
     if (_raw == null) {
       throw new StateError("selectedProtocol called on destroyed SecureSocket");
     }
-    return _raw.selectedProtocol;
+    return _raw!.selectedProtocol;
   }
 }
 
@@ -78,18 +76,17 @@
   static final int ENCRYPTED_SIZE = 10 * 1024;
 
   _SecureFilterImpl._() {
-    buffers =
-        new List<_ExternalBuffer>.filled(_RawSecureSocket.bufferCount, null);
-    for (int i = 0; i < _RawSecureSocket.bufferCount; ++i) {
-      buffers[i] = new _ExternalBuffer(
-          _RawSecureSocket._isBufferEncrypted(i) ? ENCRYPTED_SIZE : SIZE);
-    }
+    buffers = <_ExternalBuffer>[
+      for (int i = 0; i < _RawSecureSocket.bufferCount; ++i)
+        new _ExternalBuffer(
+            _RawSecureSocket._isBufferEncrypted(i) ? ENCRYPTED_SIZE : SIZE),
+    ];
   }
 
   void connect(
       String hostName,
       SecurityContext context,
-      bool is_server,
+      bool isServer,
       bool requestClientCertificate,
       bool requireClientCertificate,
       Uint8List protocols) native "SecureSocket_Connect";
@@ -114,7 +111,7 @@
 
   void init() native "SecureSocket_Init";
 
-  X509Certificate get peerCertificate native "SecureSocket_PeerCertificate";
+  X509Certificate? get peerCertificate native "SecureSocket_PeerCertificate";
 
   void registerBadCertificateCallback(Function callback)
       native "SecureSocket_RegisterBadCertificateCallback";
@@ -126,7 +123,7 @@
   int _pointer() native "SecureSocket_FilterPointer";
 
   @pragma("vm:entry-point", "get")
-  List<_ExternalBuffer> buffers;
+  List<_ExternalBuffer>? buffers;
 }
 
 @patch
@@ -158,36 +155,36 @@
 
   static final SecurityContext defaultContext = new _SecurityContext(true);
 
-  void usePrivateKey(String file, {String password}) {
+  void usePrivateKey(String file, {String? password}) {
     List<int> bytes = (new File(file)).readAsBytesSync();
     usePrivateKeyBytes(bytes, password: password);
   }
 
-  void usePrivateKeyBytes(List<int> keyBytes, {String password})
+  void usePrivateKeyBytes(List<int> keyBytes, {String? password})
       native "SecurityContext_UsePrivateKeyBytes";
 
-  void setTrustedCertificates(String file, {String password}) {
+  void setTrustedCertificates(String file, {String? password}) {
     List<int> bytes = (new File(file)).readAsBytesSync();
     setTrustedCertificatesBytes(bytes, password: password);
   }
 
-  void setTrustedCertificatesBytes(List<int> certBytes, {String password})
+  void setTrustedCertificatesBytes(List<int> certBytes, {String? password})
       native "SecurityContext_SetTrustedCertificatesBytes";
 
-  void useCertificateChain(String file, {String password}) {
+  void useCertificateChain(String file, {String? password}) {
     List<int> bytes = (new File(file)).readAsBytesSync();
     useCertificateChainBytes(bytes, password: password);
   }
 
-  void useCertificateChainBytes(List<int> chainBytes, {String password})
+  void useCertificateChainBytes(List<int> chainBytes, {String? password})
       native "SecurityContext_UseCertificateChainBytes";
 
-  void setClientAuthorities(String file, {String password}) {
+  void setClientAuthorities(String file, {String? password}) {
     List<int> bytes = (new File(file)).readAsBytesSync();
     setClientAuthoritiesBytes(bytes, password: password);
   }
 
-  void setClientAuthoritiesBytes(List<int> authCertBytes, {String password})
+  void setClientAuthoritiesBytes(List<int> authCertBytes, {String? password})
       native "SecurityContext_SetClientAuthoritiesBytes";
 
   void setAlpnProtocols(List<String> protocols, bool isServer) {
@@ -211,32 +208,14 @@
   // This is done by WrappedX509 in secure_socket.cc.
   _X509CertificateImpl._();
 
-  Uint8List _cachedDer;
   Uint8List get _der native "X509_Der";
-  Uint8List get der {
-    if (_cachedDer == null) {
-      _cachedDer = _der;
-    }
-    return _cachedDer;
-  }
+  late final Uint8List der = _der;
 
-  String _cachedPem;
   String get _pem native "X509_Pem";
-  String get pem {
-    if (_cachedPem == null) {
-      _cachedPem = _pem;
-    }
-    return _cachedPem;
-  }
+  late final String pem = _pem;
 
-  Uint8List _cachedSha1;
   Uint8List get _sha1 native "X509_Sha1";
-  Uint8List get sha1 {
-    if (_cachedSha1 == null) {
-      _cachedSha1 = _sha1;
-    }
-    return _cachedSha1;
-  }
+  late final Uint8List sha1 = _sha1;
 
   String get subject native "X509_Subject";
   String get issuer native "X509_Issuer";
diff --git a/sdk_nnbd/lib/_internal/vm/bin/socket_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/socket_patch.dart
index caf7055..a66984b 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/socket_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/socket_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 @patch
@@ -18,30 +16,29 @@
 @patch
 class RawSocket {
   @patch
-  static Future<RawSocket> connect(host, int port,
-      {sourceAddress, Duration timeout}) {
+  static Future<RawSocket> connect(dynamic host, int port,
+      {dynamic sourceAddress, Duration? timeout}) {
     return _RawSocket.connect(host, port, sourceAddress, timeout);
   }
 
   @patch
-  static Future<ConnectionTask<RawSocket>> startConnect(host, int port,
-      {sourceAddress}) {
+  static Future<ConnectionTask<RawSocket>> startConnect(dynamic host, int port,
+      {dynamic sourceAddress}) {
     return _RawSocket.startConnect(host, port, sourceAddress);
   }
 }
 
 @patch
 class RawSocketOption {
-  static final List<int> _optionsCache =
-      List<int>.filled(_RawSocketOptions.values.length, null);
+  static final List<int?> _optionsCache =
+      List<int?>.filled(_RawSocketOptions.values.length, null);
 
   @patch
   static int _getOptionValue(int key) {
     if (key > _RawSocketOptions.values.length) {
       throw ArgumentError.value(key, 'key');
     }
-    _optionsCache[key] ??= _getNativeOptionValue(key);
-    return _optionsCache[key];
+    return _optionsCache[key] ??= _getNativeOptionValue(key);
   }
 
   static int _getNativeOptionValue(int key)
@@ -110,13 +107,17 @@
 }
 
 void _throwOnBadPort(int port) {
-  if ((port == null) || (port < 0) || (port > 0xFFFF)) {
+  // TODO: Remove once non-nullability is sound.
+  ArgumentError.checkNotNull(port, "port");
+  if ((port < 0) || (port > 0xFFFF)) {
     throw new ArgumentError("Invalid port $port");
   }
 }
 
 void _throwOnBadTtl(int ttl) {
-  if (ttl == null || ttl < 1 || ttl > 255) {
+  // TODO: Remove once non-nullability is sound.
+  ArgumentError.checkNotNull(ttl, "ttl");
+  if (ttl < 1 || ttl > 255) {
     throw new ArgumentError('Invalid ttl $ttl');
   }
 }
@@ -137,7 +138,7 @@
   static _InternetAddress anyIPv6 = _InternetAddress.fixed(_addressAnyIPv6);
 
   final String address;
-  final String _host;
+  final String? _host;
   final Uint8List _in_addr;
   final int _scope_id;
 
@@ -145,7 +146,7 @@
       ? InternetAddressType.IPv4
       : InternetAddressType.IPv6;
 
-  String get host => _host != null ? _host : address;
+  String get host => _host ?? address;
 
   Uint8List get rawAddress => new Uint8List.fromList(_in_addr);
 
@@ -192,9 +193,8 @@
       [this._scope_id = 0]);
 
   factory _InternetAddress.parse(String address) {
-    if (address is! String) {
-      throw new ArgumentError("Invalid internet address $address");
-    }
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(address, "address");
     var in_addr = _parse(address);
     if (in_addr == null) {
       throw new ArgumentError("Invalid internet address $address");
@@ -253,7 +253,7 @@
     return "InternetAddress('$address', ${type.name})";
   }
 
-  static Uint8List _parse(String address) native "InternetAddress_Parse";
+  static Uint8List? _parse(String address) native "InternetAddress_Parse";
 }
 
 class _NetworkInterface implements NetworkInterface {
@@ -352,7 +352,7 @@
 
   // Handlers and receive port for socket events from the event handler.
   final List eventHandlers = new List.filled(eventCount + 1, null);
-  RawReceivePort eventPort;
+  RawReceivePort? eventPort;
   bool flagsSent = false;
 
   // The type flags for this socket.
@@ -362,7 +362,7 @@
   int localPort = 0;
 
   // Holds the address used to connect or bind the socket.
-  InternetAddress localAddress;
+  late InternetAddress localAddress;
 
   int available = 0;
 
@@ -376,11 +376,11 @@
   bool writeAvailable = false;
 
   static bool connectedResourceHandler = false;
-  _ReadWriteResourceInfo resourceInfo;
+  _SocketResourceInfo? resourceInfo;
 
   // The owner object is the object that the Socket is being used by, e.g.
   // a HttpServer, a WebSocket connection, a process pipe, etc.
-  Object owner;
+  Object? owner;
 
   static Future<List<InternetAddress>> lookup(String host,
       {InternetAddressType type: InternetAddressType.any}) {
@@ -464,7 +464,7 @@
   }
 
   static Future<ConnectionTask<_NativeSocket>> startConnect(
-      host, int port, sourceAddress) {
+      dynamic host, int port, dynamic sourceAddress) {
     if (host is String) {
       host = escapeLinkLocalAddress(host);
     }
@@ -496,7 +496,7 @@
           }
           return;
         }
-        final _InternetAddress address = it.current;
+        final _InternetAddress address = it.current as _InternetAddress;
         var socket = new _NativeSocket.normal();
         socket.localAddress = address;
         var result;
@@ -595,13 +595,12 @@
       }
 
       connectNext();
-      return new ConnectionTask<_NativeSocket>._(
-          socket: completer.future, onCancel: onCancel);
+      return new ConnectionTask<_NativeSocket>._(completer.future, onCancel);
     });
   }
 
   static Future<_NativeSocket> connect(
-      host, int port, sourceAddress, Duration timeout) {
+      dynamic host, int port, dynamic sourceAddress, Duration? timeout) {
     return startConnect(host, port, sourceAddress)
         .then((ConnectionTask<_NativeSocket> task) {
       Future<_NativeSocket> socketFuture = task.socket;
@@ -616,7 +615,7 @@
     });
   }
 
-  static Future<_InternetAddress> _resolveHost(host) async {
+  static Future<_InternetAddress> _resolveHost(dynamic host) async {
     if (host is _InternetAddress) {
       return host;
     } else {
@@ -706,7 +705,7 @@
   String get _serviceTypePath => throw new UnimplementedError();
   String get _serviceTypeName => throw new UnimplementedError();
 
-  Uint8List read(int len) {
+  Uint8List? read(int? len) {
     if (len != null && len <= 0) {
       throw new ArgumentError("Illegal length $len");
     }
@@ -718,34 +717,36 @@
       reportError(result, StackTrace.current, "Read failed");
       return null;
     }
-    if (result != null) {
-      available -= result.length;
+    final list = result as Uint8List?;
+    if (list != null) {
+      available -= list.length;
       // TODO(ricow): Remove when we track internal and pipe uses.
       assert(resourceInfo != null || isPipe || isInternal || isInternalSignal);
       if (resourceInfo != null) {
-        resourceInfo.totalRead += result.length;
+        resourceInfo!.totalRead += list.length;
       }
     }
     // TODO(ricow): Remove when we track internal and pipe uses.
     assert(resourceInfo != null || isPipe || isInternal || isInternalSignal);
     if (resourceInfo != null) {
-      resourceInfo.didRead();
+      resourceInfo!.didRead();
     }
     if (!const bool.fromEnvironment("dart.vm.product")) {
       _SocketProfile.collectStatistic(
-          nativeGetSocketId(), _SocketProfileType.readBytes, result?.length);
+          nativeGetSocketId(), _SocketProfileType.readBytes, list?.length);
     }
-    return result;
+    return list;
   }
 
-  Datagram receive() {
+  Datagram? receive() {
     if (isClosing || isClosed) return null;
     var result = nativeRecvFrom();
     if (result is OSError) {
       reportError(result, StackTrace.current, "Receive failed");
       return null;
     }
-    if (result != null) {
+    final datagram = result as Datagram?;
+    if (datagram != null) {
       // Read the next available. Available is only for the next datagram, not
       // the sum of all datagrams pending, so we need to call after each
       // receive. If available becomes > 0, the _NativeSocket will continue to
@@ -754,24 +755,26 @@
       // TODO(ricow): Remove when we track internal and pipe uses.
       assert(resourceInfo != null || isPipe || isInternal || isInternalSignal);
       if (resourceInfo != null) {
-        resourceInfo.totalRead += result.data.length;
+        resourceInfo!.totalRead += datagram.data.length;
       }
     }
     // TODO(ricow): Remove when we track internal and pipe uses.
     assert(resourceInfo != null || isPipe || isInternal || isInternalSignal);
     if (resourceInfo != null) {
-      resourceInfo.didRead();
+      resourceInfo!.didRead();
     }
     if (!const bool.fromEnvironment("dart.vm.product")) {
       _SocketProfile.collectStatistic(nativeGetSocketId(),
-          _SocketProfileType.readBytes, result?.data?.length);
+          _SocketProfileType.readBytes, datagram?.data.length);
     }
-    return result;
+    return datagram;
   }
 
-  int write(List<int> buffer, int offset, int bytes) {
-    if (buffer is! List) throw new ArgumentError();
-    if (offset == null) offset = 0;
+  static int _fixOffset(int? offset) => offset ?? 0;
+
+  int write(List<int> buffer, int offset, int? bytes) {
+    // TODO: Remove once non-nullability is sound.
+    offset = _fixOffset(offset);
     if (bytes == null) {
       if (offset > buffer.length) {
         throw new RangeError.value(offset);
@@ -783,9 +786,6 @@
     if ((offset + bytes) > buffer.length) {
       throw new RangeError.value(offset + bytes);
     }
-    if (offset is! int || bytes is! int) {
-      throw new ArgumentError("Invalid arguments to write on Socket");
-    }
     if (isClosing || isClosed) return 0;
     if (bytes == 0) return 0;
     _BufferAndStart bufferAndStart =
@@ -815,7 +815,7 @@
     // TODO(ricow): Remove when we track internal and pipe uses.
     assert(resourceInfo != null || isPipe || isInternal || isInternalSignal);
     if (resourceInfo != null) {
-      resourceInfo.addWrite(result);
+      resourceInfo!.addWrite(result);
     }
     return result;
   }
@@ -843,12 +843,12 @@
     // TODO(ricow): Remove when we track internal and pipe uses.
     assert(resourceInfo != null || isPipe || isInternal || isInternalSignal);
     if (resourceInfo != null) {
-      resourceInfo.addWrite(result);
+      resourceInfo!.addWrite(result);
     }
     return result;
   }
 
-  _NativeSocket accept() {
+  _NativeSocket? accept() {
     // Don't issue accept if we're closing.
     if (isClosing || isClosed) return null;
     assert(available > 0);
@@ -864,7 +864,7 @@
     assert(resourceInfo != null || isPipe || isInternal || isInternalSignal);
     if (resourceInfo != null) {
       // We track this as read one byte.
-      resourceInfo.addRead(1);
+      resourceInfo!.addRead(1);
     }
     return socket;
   }
@@ -949,7 +949,7 @@
   void multiplex(Object eventsObj) {
     // TODO(paulberry): when issue #31305 is fixed, we should be able to simply
     // declare `events` as a `covariant int` parameter.
-    int events = eventsObj;
+    int events = eventsObj as int;
     for (int i = firstEvent; i <= lastEvent; i++) {
       if (((events & (1 << i)) != 0)) {
         if ((i == closedEvent || i == readEvent) && isClosedRead) continue;
@@ -984,7 +984,7 @@
           assert(
               resourceInfo != null || isPipe || isInternal || isInternalSignal);
           if (resourceInfo != null) {
-            _SocketResourceInfo.SocketClosed(resourceInfo);
+            _SocketResourceInfo.SocketClosed(resourceInfo!);
           }
           isClosed = true;
           closeCompleter.complete();
@@ -1030,7 +1030,7 @@
     eventHandlers[destroyedEvent] = destroyed;
   }
 
-  void setListening({read: true, write: true}) {
+  void setListening({bool read: true, bool write: true}) {
     sendReadEvents = read;
     sendWriteEvents = write;
     if (read) issueReadEvent();
@@ -1096,7 +1096,7 @@
     int fullData = (typeFlags & typeTypeMask) | data;
     assert(!isClosing);
     connectToEventHandler();
-    _EventHandler._sendData(this, eventPort.sendPort, fullData);
+    _EventHandler._sendData(this, eventPort!.sendPort, fullData);
   }
 
   void connectToEventHandler() {
@@ -1115,8 +1115,7 @@
   }
 
   void disconnectFromEventHandler() {
-    assert(eventPort != null);
-    eventPort.close();
+    eventPort!.close();
     eventPort = null;
     // Now that we don't track this Socket anymore, we can clear the owner
     // field.
@@ -1131,7 +1130,7 @@
   // Create the appropriate error/exception from different returned
   // error objects.
   static createError(error, String message,
-      [InternetAddress address, int port]) {
+      [InternetAddress? address, int? port]) {
     if (error is OSError) {
       return new SocketException(message,
           osError: error, address: address, port: port);
@@ -1153,7 +1152,7 @@
     }
   }
 
-  void reportError(error, StackTrace st, String message) {
+  void reportError(error, StackTrace? st, String message) {
     var e = createError(error, message, address, localPort);
     // Invoke the error handler if any.
     if (eventHandlers[errorEvent] != null) {
@@ -1163,39 +1162,41 @@
     close();
   }
 
-  getOption(SocketOption option) {
-    if (option == null) throw new ArgumentError.notNull("option");
+  dynamic getOption(SocketOption option) {
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(option, "option");
     var result = nativeGetOption(option._value, address.type._value);
     if (result is OSError) throw result;
     return result;
   }
 
   bool setOption(SocketOption option, value) {
-    if (option == null) throw new ArgumentError.notNull("option");
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(option, "option");
     var result = nativeSetOption(option._value, address.type._value, value);
     if (result != null) throw result;
     return true;
   }
 
   Uint8List getRawOption(RawSocketOption option) {
-    if (option == null) throw new ArgumentError.notNull("option");
-    if (option.value == null) throw new ArgumentError.notNull("option.value");
-
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(option, "option");
+    ArgumentError.checkNotNull(option.value, "option.value");
     var result = nativeGetRawOption(option.level, option.option, option.value);
     if (result != null) throw result;
     return option.value;
   }
 
   void setRawOption(RawSocketOption option) {
-    if (option == null) throw new ArgumentError.notNull("option");
-    if (option.value == null) throw new ArgumentError.notNull("option.value");
-
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(option, "option");
+    ArgumentError.checkNotNull(option.value, "option.value");
     var result = nativeSetRawOption(option.level, option.option, option.value);
     if (result != null) throw result;
   }
 
-  InternetAddress multicastAddress(
-      InternetAddress addr, NetworkInterface interface) {
+  InternetAddress? multicastAddress(
+      InternetAddress addr, NetworkInterface? interface) {
     // On Mac OS using the interface index for joining IPv4 multicast groups
     // is not supported. Here the IP address of the interface is needed.
     if (Platform.isMacOS && addr.type == InternetAddressType.IPv4) {
@@ -1218,16 +1219,18 @@
     }
   }
 
-  void joinMulticast(InternetAddress addr, NetworkInterface interface) {
-    _InternetAddress interfaceAddr = multicastAddress(addr, interface);
+  void joinMulticast(InternetAddress addr, NetworkInterface? interface) {
+    final interfaceAddr =
+        multicastAddress(addr, interface) as _InternetAddress?;
     var interfaceIndex = interface == null ? 0 : interface.index;
     var result = nativeJoinMulticast((addr as _InternetAddress)._in_addr,
         interfaceAddr?._in_addr, interfaceIndex);
     if (result is OSError) throw result;
   }
 
-  void leaveMulticast(InternetAddress addr, NetworkInterface interface) {
-    _InternetAddress interfaceAddr = multicastAddress(addr, interface);
+  void leaveMulticast(InternetAddress addr, NetworkInterface? interface) {
+    final interfaceAddr =
+        multicastAddress(addr, interface) as _InternetAddress?;
     var interfaceIndex = interface == null ? 0 : interface.index;
     var result = nativeLeaveMulticast((addr as _InternetAddress)._in_addr,
         interfaceAddr?._in_addr, interfaceIndex);
@@ -1263,16 +1266,16 @@
       native "Socket_SetOption";
   OSError nativeSetRawOption(int level, int option, Uint8List data)
       native "Socket_SetRawOption";
-  OSError nativeJoinMulticast(Uint8List addr, Uint8List interfaceAddr,
+  OSError nativeJoinMulticast(Uint8List addr, Uint8List? interfaceAddr,
       int interfaceIndex) native "Socket_JoinMulticast";
-  bool nativeLeaveMulticast(Uint8List addr, Uint8List interfaceAddr,
+  bool nativeLeaveMulticast(Uint8List addr, Uint8List? interfaceAddr,
       int interfaceIndex) native "Socket_LeaveMulticast";
 }
 
 class _RawServerSocket extends Stream<RawSocket> implements RawServerSocket {
   final _NativeSocket _socket;
-  StreamController<RawSocket> _controller;
-  ReceivePort _referencePort;
+  StreamController<RawSocket>? _controller;
+  ReceivePort? _referencePort;
   bool _v6Only;
 
   static Future<_RawServerSocket> bind(
@@ -1285,13 +1288,13 @@
 
   _RawServerSocket(this._socket, this._v6Only);
 
-  StreamSubscription<RawSocket> listen(void onData(RawSocket event),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<RawSocket> listen(void onData(RawSocket event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     if (_controller != null) {
       throw new StateError("Stream was already listened to");
     }
     var zone = Zone.current;
-    _controller = new StreamController(
+    final controller = _controller = new StreamController(
         sync: true,
         onListen: _onSubscriptionStateChange,
         onCancel: _onSubscriptionStateChange,
@@ -1305,20 +1308,20 @@
           _SocketProfile.collectNewSocket(socket.nativeGetSocketId(),
               _tcpSocket, socket.address, socket.port);
         }
-        _controller.add(_RawSocket(socket));
-        if (_controller.isPaused) return;
+        controller.add(_RawSocket(socket));
+        if (controller.isPaused) return;
       }
     }), error: zone.bindBinaryCallbackGuarded((e, st) {
-      _controller.addError(e, st);
-      _controller.close();
+      controller.addError(e, st);
+      controller.close();
     }), destroyed: () {
-      _controller.close();
+      controller.close();
       if (_referencePort != null) {
-        _referencePort.close();
+        _referencePort!.close();
         _referencePort = null;
       }
     });
-    return _controller.stream.listen(onData,
+    return controller.stream.listen(onData,
         onError: onError, onDone: onDone, cancelOnError: cancelOnError);
   }
 
@@ -1329,7 +1332,7 @@
   Future<RawServerSocket> close() {
     return _socket.close().then<RawServerSocket>((_) {
       if (_referencePort != null) {
-        _referencePort.close();
+        _referencePort!.close();
         _referencePort = null;
       }
       return this;
@@ -1345,7 +1348,7 @@
   }
 
   void _onSubscriptionStateChange() {
-    if (_controller.hasListener) {
+    if (_controller!.hasListener) {
       _resume();
     } else {
       _socket.close();
@@ -1353,7 +1356,7 @@
   }
 
   void _onPauseStateChange() {
-    if (_controller.isPaused) {
+    if (_controller!.isPaused) {
       _pause();
     } else {
       _resume();
@@ -1367,7 +1370,7 @@
 
 class _RawSocket extends Stream<RawSocketEvent> implements RawSocket {
   final _NativeSocket _socket;
-  StreamController<RawSocketEvent> _controller;
+  final _controller = new StreamController<RawSocketEvent>(sync: true);
   bool _readEventsEnabled = true;
   bool _writeEventsEnabled = true;
 
@@ -1375,7 +1378,7 @@
   bool _isMacOSTerminalInput = false;
 
   static Future<RawSocket> connect(
-      host, int port, sourceAddress, Duration timeout) {
+      dynamic host, int port, dynamic sourceAddress, Duration? timeout) {
     return _NativeSocket.connect(host, port, sourceAddress, timeout)
         .then((socket) {
       if (!const bool.fromEnvironment("dart.vm.product")) {
@@ -1387,7 +1390,7 @@
   }
 
   static Future<ConnectionTask<_RawSocket>> startConnect(
-      host, int port, sourceAddress) {
+      dynamic host, int port, dynamic sourceAddress) {
     return _NativeSocket.startConnect(host, port, sourceAddress)
         .then((ConnectionTask<_NativeSocket> nativeTask) {
       final Future<_RawSocket> raw =
@@ -1398,19 +1401,17 @@
         }
         return _RawSocket(nativeSocket);
       });
-      return ConnectionTask<_RawSocket>._(
-          socket: raw, onCancel: nativeTask._onCancel);
+      return ConnectionTask<_RawSocket>._(raw, nativeTask._onCancel);
     });
   }
 
   _RawSocket(this._socket) {
     var zone = Zone.current;
-    _controller = new StreamController(
-        sync: true,
-        onListen: _onSubscriptionStateChange,
-        onCancel: _onSubscriptionStateChange,
-        onPause: _onPauseStateChange,
-        onResume: _onPauseStateChange);
+    _controller
+      ..onListen = _onSubscriptionStateChange
+      ..onCancel = _onSubscriptionStateChange
+      ..onPause = _onPauseStateChange
+      ..onResume = _onPauseStateChange;
     _socket.setHandlers(
         read: () => _controller.add(RawSocketEvent.read),
         write: () {
@@ -1437,7 +1438,7 @@
     return new _RawSocket(native);
   }
 
-  factory _RawSocket._readPipe(int fd) {
+  factory _RawSocket._readPipe(int? fd) {
     var native = new _NativeSocket.pipe();
     native.isClosedWrite = true;
     if (fd != null) _getStdioHandle(native, fd);
@@ -1450,15 +1451,15 @@
     return result;
   }
 
-  StreamSubscription<RawSocketEvent> listen(void onData(RawSocketEvent event),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<RawSocketEvent> listen(void onData(RawSocketEvent event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     return _controller.stream.listen(onData,
         onError: onError, onDone: onDone, cancelOnError: cancelOnError);
   }
 
   int available() => _socket.available;
 
-  Uint8List read([int len]) {
+  Uint8List? read([int? len]) {
     if (_isMacOSTerminalInput) {
       var available = this.available();
       if (available == 0) return null;
@@ -1474,7 +1475,7 @@
     }
   }
 
-  int write(List<int> buffer, [int offset, int count]) =>
+  int write(List<int> buffer, [int offset = 0, int? count]) =>
       _socket.write(buffer, offset, count);
 
   Future<RawSocket> close() => _socket.close().then<RawSocket>((_) {
@@ -1567,8 +1568,8 @@
 
   _ServerSocket(this._socket);
 
-  StreamSubscription<Socket> listen(void onData(Socket event),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<Socket> listen(void onData(Socket event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     return _socket.map<Socket>((rawSocket) => new _Socket(rawSocket)).listen(
         onData,
         onError: onError,
@@ -1591,39 +1592,38 @@
 @patch
 class Socket {
   @patch
-  static Future<Socket> _connect(host, int port,
-      {sourceAddress, Duration timeout}) {
+  static Future<Socket> _connect(dynamic host, int port,
+      {dynamic sourceAddress, Duration? timeout}) {
     return RawSocket.connect(host, port,
             sourceAddress: sourceAddress, timeout: timeout)
         .then((socket) => new _Socket(socket));
   }
 
   @patch
-  static Future<ConnectionTask<Socket>> _startConnect(host, int port,
-      {sourceAddress}) {
+  static Future<ConnectionTask<Socket>> _startConnect(dynamic host, int port,
+      {dynamic sourceAddress}) {
     return RawSocket.startConnect(host, port, sourceAddress: sourceAddress)
         .then((rawTask) {
       Future<Socket> socket =
           rawTask.socket.then((rawSocket) => new _Socket(rawSocket));
-      return new ConnectionTask<Socket>._(
-          socket: socket, onCancel: rawTask._onCancel);
+      return new ConnectionTask<Socket>._(socket, rawTask._onCancel);
     });
   }
 }
 
 class _SocketStreamConsumer extends StreamConsumer<List<int>> {
-  StreamSubscription subscription;
+  StreamSubscription? subscription;
   final _Socket socket;
-  int offset;
-  List<int> buffer;
+  int? offset;
+  List<int>? buffer;
   bool paused = false;
-  Completer streamCompleter;
+  Completer<Socket>? streamCompleter;
 
   _SocketStreamConsumer(this.socket);
 
   Future<Socket> addStream(Stream<List<int>> stream) {
     socket._ensureRawSocketSubscription();
-    streamCompleter = new Completer<Socket>();
+    final completer = streamCompleter = new Completer<Socket>();
     if (socket._raw != null) {
       subscription = stream.listen((data) {
         assert(!paused);
@@ -1644,7 +1644,7 @@
         done();
       }, cancelOnError: true);
     }
-    return streamCompleter.future;
+    return completer.future;
   }
 
   Future<Socket> close() {
@@ -1653,39 +1653,42 @@
   }
 
   void write() {
-    if (subscription == null) return;
-    assert(buffer != null);
+    final sub = subscription;
+    if (sub == null) return;
     // Write as much as possible.
-    offset += socket._write(buffer, offset, buffer.length - offset);
-    if (offset < buffer.length) {
+    offset =
+        offset! + socket._write(buffer!, offset!, buffer!.length - offset!);
+    if (offset! < buffer!.length) {
       if (!paused) {
         paused = true;
-        subscription.pause();
+        sub.pause();
       }
       socket._enableWriteEvent();
     } else {
       buffer = null;
       if (paused) {
         paused = false;
-        subscription.resume();
+        sub.resume();
       }
     }
   }
 
   void done([error, stackTrace]) {
-    if (streamCompleter != null) {
+    final completer = streamCompleter;
+    if (completer != null) {
       if (error != null) {
-        streamCompleter.completeError(error, stackTrace);
+        completer.completeError(error, stackTrace);
       } else {
-        streamCompleter.complete(socket);
+        completer.complete(socket);
       }
       streamCompleter = null;
     }
   }
 
   void stop() {
-    if (subscription == null) return;
-    subscription.cancel();
+    final sub = subscription;
+    if (sub == null) return;
+    sub.cancel();
     subscription = null;
     paused = false;
     socket._disableWriteEvent();
@@ -1693,37 +1696,36 @@
 }
 
 class _Socket extends Stream<Uint8List> implements Socket {
-  RawSocket _raw; // Set to null when the raw socket is closed.
+  RawSocket? _raw; // Set to null when the raw socket is closed.
   bool _closed = false; // Set to true when the raw socket is closed.
-  StreamController<Uint8List> _controller;
+  final _controller = new StreamController<Uint8List>(sync: true);
   bool _controllerClosed = false;
-  _SocketStreamConsumer _consumer;
-  IOSink _sink;
-  var _subscription;
+  late _SocketStreamConsumer _consumer;
+  late IOSink _sink;
+  StreamSubscription? _subscription;
   var _detachReady;
 
-  _Socket(this._raw) {
-    _controller = new StreamController<Uint8List>(
-        sync: true,
-        onListen: _onSubscriptionStateChange,
-        onCancel: _onSubscriptionStateChange,
-        onPause: _onPauseStateChange,
-        onResume: _onPauseStateChange);
+  _Socket(RawSocket raw) : _raw = raw {
+    _controller
+      ..onListen = _onSubscriptionStateChange
+      ..onCancel = _onSubscriptionStateChange
+      ..onPause = _onPauseStateChange
+      ..onResume = _onPauseStateChange;
     _consumer = new _SocketStreamConsumer(this);
     _sink = new IOSink(_consumer);
 
     // Disable read events until there is a subscription.
-    _raw.readEventsEnabled = false;
+    raw.readEventsEnabled = false;
 
     // Disable write events until the consumer needs it for pending writes.
-    _raw.writeEventsEnabled = false;
+    raw.writeEventsEnabled = false;
   }
 
   factory _Socket._writePipe() {
     return new _Socket(new _RawSocket._writePipe());
   }
 
-  factory _Socket._readPipe([int fd]) {
+  factory _Socket._readPipe([int? fd]) {
     return new _Socket(new _RawSocket._readPipe(fd));
   }
 
@@ -1733,8 +1735,8 @@
   // is Socket and not _NativeSocket.
   _NativeSocket get _nativeSocket => (_raw as _RawSocket)._socket;
 
-  StreamSubscription<Uint8List> listen(void onData(Uint8List event),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<Uint8List> listen(void onData(Uint8List event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     return _controller.stream.listen(onData,
         onError: onError, onDone: onDone, cancelOnError: cancelOnError);
   }
@@ -1745,17 +1747,18 @@
     _sink.encoding = value;
   }
 
-  void write(Object obj) => _sink.write(obj);
+  void write(Object? obj) => _sink.write(obj);
 
-  void writeln([Object obj = ""]) => _sink.writeln(obj);
+  void writeln([Object? obj = ""]) => _sink.writeln(obj);
 
   void writeCharCode(int charCode) => _sink.writeCharCode(charCode);
 
-  void writeAll(Iterable objects, [sep = ""]) => _sink.writeAll(objects, sep);
+  void writeAll(Iterable objects, [String sep = ""]) =>
+      _sink.writeAll(objects, sep);
 
   void add(List<int> bytes) => _sink.add(bytes);
 
-  void addError(Object error, [StackTrace stackTrace]) {
+  void addError(Object error, [StackTrace? stackTrace]) {
     throw new UnsupportedError("Cannot send errors on sockets");
   }
 
@@ -1779,41 +1782,45 @@
   }
 
   bool setOption(SocketOption option, bool enabled) {
-    if (_raw == null) return false;
-    return _raw.setOption(option, enabled);
+    final raw = _raw;
+    if (raw == null) throw const SocketException.closed();
+    return raw.setOption(option, enabled);
   }
 
   Uint8List getRawOption(RawSocketOption option) {
-    if (_raw == null) return null;
-    return _raw.getRawOption(option);
+    final raw = _raw;
+    if (raw == null) throw const SocketException.closed();
+    return raw.getRawOption(option);
   }
 
   void setRawOption(RawSocketOption option) {
-    _raw?.setRawOption(option);
+    final raw = _raw;
+    if (raw == null) throw const SocketException.closed();
+    raw.setRawOption(option);
   }
 
   int get port {
-    if (_raw == null) throw const SocketException.closed();
-    ;
-    return _raw.port;
+    final raw = _raw;
+    if (raw == null) throw const SocketException.closed();
+    return raw.port;
   }
 
   InternetAddress get address {
-    if (_raw == null) throw const SocketException.closed();
-    ;
-    return _raw.address;
+    final raw = _raw;
+    if (raw == null) throw const SocketException.closed();
+    return raw.address;
   }
 
   int get remotePort {
-    if (_raw == null) throw const SocketException.closed();
-    ;
-    return _raw.remotePort;
+    final raw = _raw;
+    if (raw == null) throw const SocketException.closed();
+    return raw.remotePort;
   }
 
   InternetAddress get remoteAddress {
-    if (_raw == null) throw const SocketException.closed();
-    ;
-    return _raw.remoteAddress;
+    final raw = _raw;
+    if (raw == null) throw const SocketException.closed();
+    return raw.remoteAddress;
   }
 
   Future _detachRaw() {
@@ -1831,45 +1838,45 @@
   // consumer needs a subscription as they share the error and done
   // events from the raw socket.
   void _ensureRawSocketSubscription() {
-    if (_subscription == null && _raw != null) {
-      _subscription = _raw.listen(_onData,
+    final raw = _raw;
+    if (_subscription == null && raw != null) {
+      _subscription = raw.listen(_onData,
           onError: _onError, onDone: _onDone, cancelOnError: true);
     }
   }
 
   _closeRawSocket() {
-    var tmp = _raw;
+    var raw = _raw!;
     _raw = null;
     _closed = true;
-    tmp.close();
+    raw.close();
   }
 
   void _onSubscriptionStateChange() {
+    final raw = _raw;
     if (_controller.hasListener) {
       _ensureRawSocketSubscription();
       // Enable read events for providing data to subscription.
-      if (_raw != null) {
-        _raw.readEventsEnabled = true;
+      if (raw != null) {
+        raw.readEventsEnabled = true;
       }
     } else {
       _controllerClosed = true;
-      if (_raw != null) {
-        _raw.shutdown(SocketDirection.receive);
+      if (raw != null) {
+        raw.shutdown(SocketDirection.receive);
       }
     }
   }
 
   void _onPauseStateChange() {
-    if (_raw != null) {
-      _raw.readEventsEnabled = !_controller.isPaused;
-    }
+    _raw?.readEventsEnabled = !_controller.isPaused;
   }
 
   void _onData(event) {
     switch (event) {
       case RawSocketEvent.read:
         if (_raw == null) break;
-        var buffer = _raw.read();
+        var buffer = _raw!.read();
         if (buffer != null) _controller.add(buffer);
         break;
       case RawSocketEvent.write:
@@ -1900,30 +1907,28 @@
   }
 
   int _write(List<int> data, int offset, int length) {
-    if (_raw != null) {
-      return _raw.write(data, offset, length);
+    final raw = _raw;
+    if (raw != null) {
+      return raw.write(data, offset, length);
     }
     return 0;
   }
 
   void _enableWriteEvent() {
-    if (_raw != null) {
-      _raw.writeEventsEnabled = true;
-    }
+    _raw?.writeEventsEnabled = true;
   }
 
   void _disableWriteEvent() {
-    if (_raw != null) {
-      _raw.writeEventsEnabled = false;
-    }
+    _raw?.writeEventsEnabled = false;
   }
 
   void _consumerDone() {
     if (_detachReady != null) {
       _detachReady.complete(null);
     } else {
-      if (_raw != null) {
-        _raw.shutdown(SocketDirection.send);
+      final raw = _raw;
+      if (raw != null) {
+        raw.shutdown(SocketDirection.send);
         _disableWriteEvent();
       }
     }
@@ -1948,7 +1953,7 @@
 class _RawDatagramSocket extends Stream<RawSocketEvent>
     implements RawDatagramSocket {
   _NativeSocket _socket;
-  StreamController<RawSocketEvent> _controller;
+  late StreamController<RawSocketEvent> _controller;
   bool _readEventsEnabled = true;
   bool _writeEventsEnabled = true;
 
@@ -1993,8 +1998,8 @@
     });
   }
 
-  StreamSubscription<RawSocketEvent> listen(void onData(RawSocketEvent event),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<RawSocketEvent> listen(void onData(RawSocketEvent event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     return _controller.stream.listen(onData,
         onError: onError, onDone: onDone, cancelOnError: cancelOnError);
   }
@@ -2010,15 +2015,15 @@
   int send(List<int> buffer, InternetAddress address, int port) =>
       _socket.send(buffer, 0, buffer.length, address, port);
 
-  Datagram receive() {
+  Datagram? receive() {
     return _socket.receive();
   }
 
-  void joinMulticast(InternetAddress group, [NetworkInterface interface]) {
+  void joinMulticast(InternetAddress group, [NetworkInterface? interface]) {
     _socket.joinMulticast(group, interface);
   }
 
-  void leaveMulticast(InternetAddress group, [NetworkInterface interface]) {
+  void leaveMulticast(InternetAddress group, [NetworkInterface? interface]) {
     _socket.leaveMulticast(group, interface);
   }
 
@@ -2048,7 +2053,7 @@
       _socket.setOption(SocketOption._ipMulticastHops, value);
 
   NetworkInterface get multicastInterface => throw "Not implemented";
-  void set multicastInterface(NetworkInterface value) =>
+  void set multicastInterface(NetworkInterface? value) =>
       throw "Not implemented";
 
   bool get broadcastEnabled => _socket.getOption(SocketOption._ipBroadcast);
diff --git a/sdk_nnbd/lib/_internal/vm/bin/stdio_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/stdio_patch.dart
index 58d1d0a..71e3669 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/stdio_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/stdio_patch.dart
@@ -2,43 +2,40 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 @patch
 class _StdIOUtils {
   @patch
   static Stdin _getStdioInputStream(int fd) {
-    switch (_getStdioHandleType(fd)) {
+    final type = _getStdioHandleType(fd);
+    if (type is OSError) {
+      throw FileSystemException(
+          "Failed to get type of stdio handle (fd $fd)", "", type);
+    }
+    switch (type) {
       case _stdioHandleTypeTerminal:
       case _stdioHandleTypePipe:
       case _stdioHandleTypeSocket:
+      case _stdioHandleTypeOther:
         return new Stdin._(new _Socket._readPipe(fd), fd);
       case _stdioHandleTypeFile:
         return new Stdin._(new _FileStream.forStdin(), fd);
-      default:
-        throw new FileSystemException(
-            "Couldn't determine file type of stdin (fd $fd)");
     }
   }
 
   @patch
   static _getStdioOutputStream(int fd) {
-    switch (_getStdioHandleType(fd)) {
-      case _stdioHandleTypeTerminal:
-      case _stdioHandleTypePipe:
-      case _stdioHandleTypeSocket:
-      case _stdioHandleTypeFile:
-        return new Stdout._(new IOSink(new _StdConsumer(fd)), fd);
-      default:
-        throw new FileSystemException(
-            "Couldn't determine file type of stdio handle (fd $fd)");
+    final type = _getStdioHandleType(fd);
+    if (type is OSError) {
+      throw FileSystemException(
+          "Failed to get type of stdio handle (fd $fd)", "", type);
     }
+    return new Stdout._(new IOSink(new _StdConsumer(fd)), fd);
   }
 
   @patch
-  static int _socketType(Socket socket) {
+  static int? _socketType(Socket socket) {
     if (socket is _Socket) return _nativeSocketType(socket._nativeSocket);
     return null;
   }
diff --git a/sdk_nnbd/lib/_internal/vm/bin/sync_socket_patch.dart b/sdk_nnbd/lib/_internal/vm/bin/sync_socket_patch.dart
index dcdafff..cf16b88 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/sync_socket_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/sync_socket_patch.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 // part of "common_patch.dart";
 
 @patch
@@ -34,14 +32,14 @@
 
   void closeSync() => _socket.closeSync();
 
-  int readIntoSync(List<int> buffer, [int start = 0, int end]) =>
+  int readIntoSync(List<int> buffer, [int start = 0, int? end]) =>
       _socket.readIntoSync(buffer, start, end);
 
-  List<int> readSync(int bytes) => _socket.readSync(bytes);
+  List<int>? readSync(int bytes) => _socket.readSync(bytes);
 
   void shutdown(SocketDirection direction) => _socket.shutdown(direction);
 
-  void writeFromSync(List<int> buffer, [int start = 0, int end]) =>
+  void writeFromSync(List<int> buffer, [int start = 0, int? end]) =>
       _socket.writeFromSync(buffer, start, end);
 }
 
@@ -57,18 +55,19 @@
   bool isClosedWrite = false;
 
   // Holds the address used to connect the socket.
-  InternetAddress localAddress;
+  late InternetAddress localAddress;
 
   // Holds the port of the socket, 0 if not known.
   int localPort = 0;
 
-  _ReadWriteResourceInfo resourceInfo;
+  // Always set by setupResourceInfo called by connectSync.
+  late _SocketResourceInfo resourceInfo;
 
   static _NativeSynchronousSocket connectSync(host, int port) {
     if (host == null) {
       throw new ArgumentError("Parameter host cannot be null");
     }
-    List<_InternetAddress> addresses = null;
+    late List<_InternetAddress> addresses;
     var error = null;
     if (host is _InternetAddress) {
       addresses = [host];
@@ -82,7 +81,6 @@
         throw createError(error, "Failed host lookup: '$host'");
       }
     }
-    assert(addresses is List);
     var it = addresses.iterator;
     _NativeSynchronousSocket connectNext() {
       if (!it.moveNext()) {
@@ -169,7 +167,7 @@
   // Create the appropriate error/exception from different returned
   // error objects.
   static createError(error, String message,
-      [InternetAddress address, int port]) {
+      [InternetAddress? address, int? port]) {
     if (error is OSError) {
       return new SocketException(message,
           osError: error, address: address, port: port);
@@ -184,34 +182,25 @@
     if (response is OSError) {
       throw response;
     }
-    List<_InternetAddress> addresses =
-        new List<_InternetAddress>.filled(response.length, null);
-    for (int i = 0; i < response.length; ++i) {
-      var result = response[i];
-      addresses[i] = new _InternetAddress(result[1], host, result[2]);
-    }
-    return addresses;
+    return <_InternetAddress>[
+      for (int i = 0; i < response.length; ++i)
+        new _InternetAddress(response[i][1], host, response[i][2]),
+    ];
   }
 
-  int readIntoSync(List<int> buffer, int start, int end) {
+  int readIntoSync(List<int> buffer, int start, int? end) {
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(buffer, "buffer");
+    ArgumentError.checkNotNull(start, "start");
     _checkAvailable();
     if (isClosedRead) {
       throw new SocketException("Socket is closed for reading");
     }
-
-    if ((buffer is! List) ||
-        ((start != null) && (start is! int)) ||
-        ((end != null) && (end is! int))) {
-      throw new ArgumentError("Invalid arguments to readIntoSync");
-    }
-    if (start == null) {
-      throw new ArgumentError("start cannot be null");
-    }
     end = RangeError.checkValidRange(start, end, buffer.length);
     if (end == start) {
       return 0;
     }
-    var result = _nativeReadInto(buffer, start, (end - start));
+    var result = _nativeReadInto(buffer, start, end! - start);
     if (result is OSError) {
       throw new SocketException("readIntoSync failed", osError: result);
     }
@@ -219,7 +208,7 @@
     return result;
   }
 
-  List<int> readSync(int len) {
+  List<int>? readSync(int len) {
     _checkAvailable();
     if (isClosedRead) {
       throw new SocketException("Socket is closed for reading");
@@ -235,15 +224,10 @@
     if (result is OSError) {
       throw result;
     }
-    assert(resourceInfo != null);
-    if (result != null) {
-      if (resourceInfo != null) {
-        resourceInfo.totalRead += result.length;
-      }
+    if (result is List<int>) {
+      resourceInfo.totalRead += result.length;
     }
-    if (resourceInfo != null) {
-      resourceInfo.didRead();
-    }
+    resourceInfo.didRead();
     return result;
   }
 
@@ -294,36 +278,26 @@
     isClosedWrite = true;
   }
 
-  void writeFromSync(List<int> buffer, int start, int end) {
+  void writeFromSync(List<int> buffer, int start, int? end) {
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(buffer, "buffer");
+    ArgumentError.checkNotNull(start, "start");
     _checkAvailable();
     if (isClosedWrite) {
       throw new SocketException("Socket is closed for writing");
     }
-    if ((buffer is! List) ||
-        ((start != null) && (start is! int)) ||
-        ((end != null) && (end is! int))) {
-      throw new ArgumentError("Invalid arguments to writeFromSync");
-    }
-    if (start == null) {
-      throw new ArgumentError("start cannot be equal to null");
-    }
-
     end = RangeError.checkValidRange(start, end, buffer.length);
     if (end == start) {
       return;
     }
-
     _BufferAndStart bufferAndStart =
-        _ensureFastAndSerializableByteData(buffer, start, end);
+        _ensureFastAndSerializableByteData(buffer, start, end!);
     var result = _nativeWrite(bufferAndStart.buffer, bufferAndStart.start,
         end - (start - bufferAndStart.start));
     if (result is OSError) {
       throw new SocketException("writeFromSync failed", osError: result);
     }
-    assert(resourceInfo != null);
-    if (resourceInfo != null) {
-      resourceInfo.addWrite(result);
-    }
+    resourceInfo.addWrite(result);
   }
 
   void _checkAvailable() {
diff --git a/sdk_nnbd/lib/_internal/vm/bin/vmservice_io.dart b/sdk_nnbd/lib/_internal/vm/bin/vmservice_io.dart
index 9644cd1..c6717ee 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/vmservice_io.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/vmservice_io.dart
@@ -35,6 +35,8 @@
 @pragma('vm:entry-point')
 var _signalWatch = null;
 var _signalSubscription;
+@pragma("vm:entry-point")
+bool _enableServicePortFallback = false;
 
 // HTTP server.
 Server? server;
@@ -49,7 +51,7 @@
   final service = VMService();
   // Lazily create server.
   localServer = Server(service, _ip, _port, _originCheckDisabled,
-      _authCodesDisabled, _serviceInfoFilename);
+      _authCodesDisabled, _serviceInfoFilename, _enableServicePortFallback);
   server = localServer;
   return localServer;
 }
diff --git a/sdk_nnbd/lib/_internal/vm/bin/vmservice_server.dart b/sdk_nnbd/lib/_internal/vm/bin/vmservice_server.dart
index 83409e7..1ae04a3 100644
--- a/sdk_nnbd/lib/_internal/vm/bin/vmservice_server.dart
+++ b/sdk_nnbd/lib/_internal/vm/bin/vmservice_server.dart
@@ -147,12 +147,13 @@
 
   final VMService _service;
   final String _ip;
-  final int _port;
   final bool _originCheckDisabled;
   final bool _authCodesDisabled;
+  final bool _enableServicePortFallback;
   final String? _serviceInfoFilename;
   HttpServer? _server;
   bool get running => _server != null;
+  int _port = -1;
 
   /// Returns the server address including the auth token.
   Uri? get serverAddress {
@@ -168,8 +169,14 @@
 
   // On Fuchsia, authentication codes are disabled by default. To enable, the authentication token
   // would have to be written into the hub alongside the port number.
-  Server(this._service, this._ip, this._port, this._originCheckDisabled,
-      bool authCodesDisabled, this._serviceInfoFilename)
+  Server(
+      this._service,
+      this._ip,
+      this._port,
+      this._originCheckDisabled,
+      bool authCodesDisabled,
+      this._serviceInfoFilename,
+      this._enableServicePortFallback)
       : _authCodesDisabled = (authCodesDisabled || Platform.isFuchsia);
 
   bool _isAllowedOrigin(String origin) {
@@ -424,6 +431,10 @@
         onServerAddressChange(null);
         return this;
       }
+      if (_port != 0 && _enableServicePortFallback && attempts >= 3) {
+        _port = 0;
+        serverPrint('Falling back to automatic port selection');
+      }
       await Future<void>.delayed(const Duration(seconds: 1));
     }
     if (_service.isExiting) {
diff --git a/sdk_nnbd/lib/_internal/vm/lib/async_patch.dart b/sdk_nnbd/lib/_internal/vm/lib/async_patch.dart
index 044c0de..b2b57d7 100644
--- a/sdk_nnbd/lib/_internal/vm/lib/async_patch.dart
+++ b/sdk_nnbd/lib/_internal/vm/lib/async_patch.dart
@@ -70,7 +70,7 @@
   // `Future` implementation could potentially invoke the callback with the
   // wrong number of arguments.
   if (Zone.current == Zone.root) return continuation;
-  return Zone.current.registerUnaryCallback((x) => continuation(x, null, null));
+  return Zone.current.registerUnaryCallback(continuation);
 }
 
 // We need to pass the exception and stack trace objects as second and third
diff --git a/sdk_nnbd/lib/_internal/vm/lib/timer_impl.dart b/sdk_nnbd/lib/_internal/vm/lib/timer_impl.dart
index b27f5e0..db626c2 100644
--- a/sdk_nnbd/lib/_internal/vm/lib/timer_impl.dart
+++ b/sdk_nnbd/lib/_internal/vm/lib/timer_impl.dart
@@ -467,6 +467,7 @@
     _sendPort = null;
     _scheduledWakeupTime = 0;
     _receivePort!.close();
+    _receivePort = null;
   }
 
   // The Timer factory registered with the dart:async library by the embedder.
diff --git a/sdk_nnbd/lib/async/stream.dart b/sdk_nnbd/lib/async/stream.dart
index b874e5e1..0928b6a 100644
--- a/sdk_nnbd/lib/async/stream.dart
+++ b/sdk_nnbd/lib/async/stream.dart
@@ -489,9 +489,12 @@
    * The returned stream is a broadcast stream if this stream is.
    */
   Stream<E> asyncMap<E>(FutureOr<E> convert(T event)) {
-    _StreamControllerBase<E> controller = isBroadcast
-        ? _SyncBroadcastStreamController<E>(null, null)
-        : _SyncStreamController<E>(null, null, null, null);
+    _StreamControllerBase<E> controller;
+    if (isBroadcast) {
+      controller = _SyncBroadcastStreamController<E>(null, null);
+    } else {
+      controller = _SyncStreamController<E>(null, null, null, null);
+    }
 
     controller.onListen = () {
       StreamSubscription<T> subscription = this.listen(null,
@@ -500,6 +503,7 @@
       FutureOr<Null> add(E value) {
         controller.add(value);
       }
+
       final addError = controller._addError;
       subscription.onData((T event) {
         FutureOr<E> newValue;
@@ -515,7 +519,9 @@
               .then(add, onError: addError)
               .whenComplete(subscription.resume);
         } else {
-          if (newValue is! E) throw "unreachable"; // TODO(lrn): Remove when type promotion works.
+          if (newValue is! E) {
+            throw "unreachable"; // TODO(lrn): Remove when type promotion works.
+          }
           controller.add(newValue);
         }
       });
@@ -548,9 +554,12 @@
    * The returned stream is a broadcast stream if this stream is.
    */
   Stream<E> asyncExpand<E>(Stream<E> convert(T event)) {
-    _StreamControllerBase<E> controller = isBroadcast
-        ? _SyncBroadcastStreamController<E>(null, null)
-        : _SyncStreamController<E>(null, null, null, null);
+    _StreamControllerBase<E> controller;
+    if (isBroadcast) {
+      controller = _SyncBroadcastStreamController<E>(null, null);
+    } else {
+      controller = _SyncStreamController<E>(null, null, null, null);
+    }
 
     controller.onListen = () {
       StreamSubscription<T> subscription = this.listen(null,
@@ -1498,9 +1507,12 @@
    * and the subscriptions' timers can be paused individually.
    */
   Stream<T> timeout(Duration timeLimit, {void onTimeout(EventSink<T> sink)?}) {
-    _StreamControllerBase<T> controller = isBroadcast
-        ? new _SyncBroadcastStreamController<T>(null, null)
-        : new _SyncStreamController<T>(null, null, null, null);
+    _StreamControllerBase<T> controller;
+    if (isBroadcast) {
+      controller = new _SyncBroadcastStreamController<T>(null, null);
+    } else {
+      controller = new _SyncStreamController<T>(null, null, null, null);
+    }
 
     Zone zone = Zone.current;
     // Register callback immediately.
diff --git a/sdk_nnbd/lib/convert/base64.dart b/sdk_nnbd/lib/convert/base64.dart
index ce94d1b..c36ba1a 100644
--- a/sdk_nnbd/lib/convert/base64.dart
+++ b/sdk_nnbd/lib/convert/base64.dart
@@ -615,9 +615,7 @@
     }
     if (start == end) return Uint8List(0);
     var buffer = _allocateBuffer(input, start, end, _state);
-    if (buffer.length > 0) {
-      _state = decodeChunk(input, start, end, buffer, 0, _state);
-    }
+    _state = decodeChunk(input, start, end, buffer, 0, _state);
     return buffer;
   }
 
diff --git a/sdk_nnbd/lib/html/dart2js/html_dart2js.dart b/sdk_nnbd/lib/html/dart2js/html_dart2js.dart
index 278548d..fb306dc 100644
--- a/sdk_nnbd/lib/html/dart2js/html_dart2js.dart
+++ b/sdk_nnbd/lib/html/dart2js/html_dart2js.dart
@@ -1,4 +1,3 @@
-// @dart = 2.5
 /**
  * HTML elements and other resources for web-based applications that need to
  * interact with the browser and the DOM (Document Object Model).
@@ -158,7 +157,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory AbsoluteOrientationSensor([Map sensorOptions]) {
+  factory AbsoluteOrientationSensor([Map? sensorOptions]) {
     if (sensorOptions != null) {
       var sensorOptions_1 = convertDartToNative_Dictionary(sensorOptions);
       return AbsoluteOrientationSensor._create_1(sensorOptions_1);
@@ -205,7 +204,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory Accelerometer([Map sensorOptions]) {
+  factory Accelerometer([Map? sensorOptions]) {
     if (sensorOptions != null) {
       var sensorOptions_1 = convertDartToNative_Dictionary(sensorOptions);
       return Accelerometer._create_1(sensorOptions_1);
@@ -258,99 +257,99 @@
   static AccessibleNode _create_1() =>
       JS('AccessibleNode', 'new AccessibleNode()');
 
-  AccessibleNode activeDescendant;
+  AccessibleNode? activeDescendant;
 
-  bool atomic;
+  bool? atomic;
 
-  String autocomplete;
+  String? autocomplete;
 
-  bool busy;
+  bool? busy;
 
-  String checked;
+  String? checked;
 
-  int colCount;
+  int? colCount;
 
-  int colIndex;
+  int? colIndex;
 
-  int colSpan;
+  int? colSpan;
 
-  AccessibleNodeList controls;
+  AccessibleNodeList? controls;
 
-  String current;
+  String? current;
 
-  AccessibleNodeList describedBy;
+  AccessibleNodeList? describedBy;
 
-  AccessibleNode details;
+  AccessibleNode? details;
 
-  bool disabled;
+  bool? disabled;
 
-  AccessibleNode errorMessage;
+  AccessibleNode? errorMessage;
 
-  bool expanded;
+  bool? expanded;
 
-  AccessibleNodeList flowTo;
+  AccessibleNodeList? flowTo;
 
-  String hasPopUp;
+  String? hasPopUp;
 
-  bool hidden;
+  bool? hidden;
 
-  String invalid;
+  String? invalid;
 
-  String keyShortcuts;
+  String? keyShortcuts;
 
-  String label;
+  String? label;
 
-  AccessibleNodeList labeledBy;
+  AccessibleNodeList? labeledBy;
 
-  int level;
+  int? level;
 
-  String live;
+  String? live;
 
-  bool modal;
+  bool? modal;
 
-  bool multiline;
+  bool? multiline;
 
-  bool multiselectable;
+  bool? multiselectable;
 
-  String orientation;
+  String? orientation;
 
-  AccessibleNodeList owns;
+  AccessibleNodeList? owns;
 
-  String placeholder;
+  String? placeholder;
 
-  int posInSet;
+  int? posInSet;
 
-  String pressed;
+  String? pressed;
 
-  bool readOnly;
+  bool? readOnly;
 
-  String relevant;
+  String? relevant;
 
-  bool required;
+  bool? required;
 
-  String role;
+  String? role;
 
-  String roleDescription;
+  String? roleDescription;
 
-  int rowCount;
+  int? rowCount;
 
-  int rowIndex;
+  int? rowIndex;
 
-  int rowSpan;
+  int? rowSpan;
 
-  bool selected;
+  bool? selected;
 
-  int setSize;
+  int? setSize;
 
-  String sort;
+  String? sort;
 
-  num valueMax;
+  num? valueMax;
 
-  num valueMin;
+  num? valueMin;
 
-  num valueNow;
+  num? valueNow;
 
-  String valueText;
+  String? valueText;
 
   void appendChild(AccessibleNode child) native;
 
@@ -381,7 +380,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory AccessibleNodeList([List<AccessibleNode> nodes]) {
+  factory AccessibleNodeList([List<AccessibleNode>? nodes]) {
     if (nodes != null) {
       return AccessibleNodeList._create_1(nodes);
     }
@@ -392,11 +391,15 @@
   static AccessibleNodeList _create_2() =>
       JS('AccessibleNodeList', 'new AccessibleNodeList()');
 
-  int length;
+  int get length => JS("int", "#.length", this);
+
+  set length(int value) {
+    JS("void", "#.length = #", this, value);
+  }
 
   void __setter__(int index, AccessibleNode node) native;
 
-  void add(AccessibleNode node, AccessibleNode before) native;
+  void add(AccessibleNode node, AccessibleNode? before) native;
 
   AccessibleNode item(int index) native;
 
@@ -413,7 +416,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory AmbientLightSensor([Map sensorOptions]) {
+  factory AmbientLightSensor([Map? sensorOptions]) {
     if (sensorOptions != null) {
       var sensorOptions_1 = convertDartToNative_Dictionary(sensorOptions);
       return AmbientLightSensor._create_1(sensorOptions_1);
@@ -438,9 +441,12 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory AnchorElement({String href}) {
-    AnchorElement e = JS('returns:AnchorElement;creates:AnchorElement;new:true',
-        '#.createElement(#)', document, "a");
+  factory AnchorElement({String? href}) {
+    AnchorElement e = JS<AnchorElement>(
+        'returns:AnchorElement;creates:AnchorElement;new:true',
+        '#.createElement(#)',
+        document,
+        "a");
     if (href != null) e.href = href;
     return e;
   }
@@ -451,41 +457,105 @@
    */
   AnchorElement.created() : super.created();
 
-  String download;
+  String get download => JS("String", "#.download", this);
 
-  String hreflang;
+  set download(String value) {
+    JS("void", "#.download = #", this, value);
+  }
 
-  String referrerPolicy;
+  String get hreflang => JS("String", "#.hreflang", this);
 
-  String rel;
+  set hreflang(String value) {
+    JS("void", "#.hreflang = #", this, value);
+  }
 
-  String target;
+  String get referrerPolicy => JS("String", "#.referrerPolicy", this);
 
-  String type;
+  set referrerPolicy(String value) {
+    JS("void", "#.referrerPolicy = #", this, value);
+  }
+
+  String get rel => JS("String", "#.rel", this);
+
+  set rel(String value) {
+    JS("void", "#.rel = #", this, value);
+  }
+
+  String get target => JS("String", "#.target", this);
+
+  set target(String value) {
+    JS("void", "#.target = #", this, value);
+  }
+
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 
   // From HTMLHyperlinkElementUtils
 
-  String hash;
+  String get hash => JS("String", "#.hash", this);
 
-  String host;
+  set hash(String value) {
+    JS("void", "#.hash = #", this, value);
+  }
 
-  String hostname;
+  String get host => JS("String", "#.host", this);
 
-  String href;
+  set host(String value) {
+    JS("void", "#.host = #", this, value);
+  }
 
-  final String origin;
+  String get hostname => JS("String", "#.hostname", this);
 
-  String password;
+  set hostname(String value) {
+    JS("void", "#.hostname = #", this, value);
+  }
 
-  String pathname;
+  String get href => JS("String", "#.href", this);
 
-  String port;
+  set href(String value) {
+    JS("void", "#.href = #", this, value);
+  }
 
-  String protocol;
+  String get origin => JS("String", "#.origin", this);
 
-  String search;
+  String get password => JS("String", "#.password", this);
 
-  String username;
+  set password(String value) {
+    JS("void", "#.password = #", this, value);
+  }
+
+  String get pathname => JS("String", "#.pathname", this);
+
+  set pathname(String value) {
+    JS("void", "#.pathname = #", this, value);
+  }
+
+  String get port => JS("String", "#.port", this);
+
+  set port(String value) {
+    JS("void", "#.port = #", this, value);
+  }
+
+  String get protocol => JS("String", "#.protocol", this);
+
+  set protocol(String value) {
+    JS("void", "#.protocol = #", this, value);
+  }
+
+  String get search => JS("String", "#.search", this);
+
+  set search(String value) {
+    JS("void", "#.search = #", this, value);
+  }
+
+  String get username => JS("String", "#.username", this);
+
+  set username(String value) {
+    JS("void", "#.username = #", this, value);
+  }
 
   String toString() => JS('String', 'String(#)', this);
 }
@@ -507,7 +577,7 @@
       const EventStreamProvider<Event>('finish');
 
   factory Animation(
-      [AnimationEffectReadOnly effect, AnimationTimeline timeline]) {
+      [AnimationEffectReadOnly? effect, AnimationTimeline? timeline]) {
     if (timeline != null) {
       return Animation._create_1(effect, timeline);
     }
@@ -525,25 +595,31 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => JS('bool', '!!(document.body.animate)');
 
-  num currentTime;
+  num? currentTime;
 
-  AnimationEffectReadOnly effect;
+  AnimationEffectReadOnly? effect;
 
-  Future<Animation> get finished =>
-      promiseToFuture<Animation>(JS("", "#.finished", this));
+  Future get finished => JS("Future", "#.finished", this);
 
-  String id;
+  String get id => JS("String", "#.id", this);
 
-  final String playState;
+  set id(String value) {
+    JS("void", "#.id = #", this, value);
+  }
 
-  num playbackRate;
+  String get playState => JS("String", "#.playState", this);
 
-  Future<Animation> get ready =>
-      promiseToFuture<Animation>(JS("", "#.ready", this));
+  num get playbackRate => JS("num", "#.playbackRate", this);
 
-  num startTime;
+  set playbackRate(num value) {
+    JS("void", "#.playbackRate = #", this, value);
+  }
 
-  final AnimationTimeline timeline;
+  Future get ready => JS("Future", "#.ready", this);
+
+  num? startTime;
+
+  final AnimationTimeline? timeline;
 
   void cancel() native;
 
@@ -570,7 +646,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final AnimationEffectTimingReadOnly timing;
+  AnimationEffectTimingReadOnly get timing =>
+      JS("AnimationEffectTimingReadOnly", "#.timing", this);
 
   Map getComputedTiming() {
     return convertNativeToDart_Dictionary(_getComputedTiming_1());
@@ -591,6 +668,7 @@
   }
 
   // Shadowing definition.
+
   num get delay => JS("num", "#.delay", this);
 
   set delay(num value) {
@@ -598,6 +676,7 @@
   }
 
   // Shadowing definition.
+
   String get direction => JS("String", "#.direction", this);
 
   set direction(String value) {
@@ -605,6 +684,7 @@
   }
 
   // Shadowing definition.
+
   Object get duration => JS("Object", "#.duration", this);
 
   set duration(Object value) {
@@ -612,6 +692,7 @@
   }
 
   // Shadowing definition.
+
   String get easing => JS("String", "#.easing", this);
 
   set easing(String value) {
@@ -619,6 +700,7 @@
   }
 
   // Shadowing definition.
+
   num get endDelay => JS("num", "#.endDelay", this);
 
   set endDelay(num value) {
@@ -626,6 +708,7 @@
   }
 
   // Shadowing definition.
+
   String get fill => JS("String", "#.fill", this);
 
   set fill(String value) {
@@ -633,6 +716,7 @@
   }
 
   // Shadowing definition.
+
   num get iterationStart => JS("num", "#.iterationStart", this);
 
   set iterationStart(num value) {
@@ -640,6 +724,7 @@
   }
 
   // Shadowing definition.
+
   num get iterations => JS("num", "#.iterations", this);
 
   set iterations(num value) {
@@ -657,21 +742,21 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num delay;
+  num get delay => JS("num", "#.delay", this);
 
-  final String direction;
+  String get direction => JS("String", "#.direction", this);
 
-  final Object duration;
+  Object get duration => JS("Object", "#.duration", this);
 
-  final String easing;
+  String get easing => JS("String", "#.easing", this);
 
-  final num endDelay;
+  num get endDelay => JS("num", "#.endDelay", this);
 
-  final String fill;
+  String get fill => JS("String", "#.fill", this);
 
-  final num iterationStart;
+  num get iterationStart => JS("num", "#.iterationStart", this);
 
-  final num iterations;
+  num get iterations => JS("num", "#.iterations", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -684,7 +769,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory AnimationEvent(String type, [Map eventInitDict]) {
+  factory AnimationEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return AnimationEvent._create_1(type, eventInitDict_1);
@@ -696,9 +781,9 @@
   static AnimationEvent _create_2(type) =>
       JS('AnimationEvent', 'new AnimationEvent(#)', type);
 
-  final String animationName;
+  String get animationName => JS("String", "#.animationName", this);
 
-  final num elapsedTime;
+  num get elapsedTime => JS("num", "#.elapsedTime", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -711,7 +796,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory AnimationPlaybackEvent(String type, [Map eventInitDict]) {
+  factory AnimationPlaybackEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return AnimationPlaybackEvent._create_1(type, eventInitDict_1);
@@ -863,7 +948,7 @@
 
   static const int UPDATEREADY = 4;
 
-  final int status;
+  int get status => JS("int", "#.status", this);
 
   void abort() native;
 
@@ -906,7 +991,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ApplicationCacheErrorEvent(String type, [Map eventInitDict]) {
+  factory ApplicationCacheErrorEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return ApplicationCacheErrorEvent._create_1(type, eventInitDict_1);
@@ -921,13 +1006,13 @@
   static ApplicationCacheErrorEvent _create_2(type) => JS(
       'ApplicationCacheErrorEvent', 'new ApplicationCacheErrorEvent(#)', type);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 
-  final String reason;
+  String get reason => JS("String", "#.reason", this);
 
-  final int status;
+  int get status => JS("int", "#.status", this);
 
-  final String url;
+  String get url => JS("String", "#.url", this);
 }
 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -950,7 +1035,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory AreaElement() => JS(
+  factory AreaElement() => JS<AreaElement>(
       'returns:AreaElement;creates:AreaElement;new:true',
       '#.createElement(#)',
       document,
@@ -962,43 +1047,111 @@
    */
   AreaElement.created() : super.created();
 
-  String alt;
+  String get alt => JS("String", "#.alt", this);
 
-  String coords;
+  set alt(String value) {
+    JS("void", "#.alt = #", this, value);
+  }
 
-  String download;
+  String get coords => JS("String", "#.coords", this);
 
-  String referrerPolicy;
+  set coords(String value) {
+    JS("void", "#.coords = #", this, value);
+  }
 
-  String rel;
+  String get download => JS("String", "#.download", this);
 
-  String shape;
+  set download(String value) {
+    JS("void", "#.download = #", this, value);
+  }
 
-  String target;
+  String get referrerPolicy => JS("String", "#.referrerPolicy", this);
+
+  set referrerPolicy(String value) {
+    JS("void", "#.referrerPolicy = #", this, value);
+  }
+
+  String get rel => JS("String", "#.rel", this);
+
+  set rel(String value) {
+    JS("void", "#.rel = #", this, value);
+  }
+
+  String get shape => JS("String", "#.shape", this);
+
+  set shape(String value) {
+    JS("void", "#.shape = #", this, value);
+  }
+
+  String get target => JS("String", "#.target", this);
+
+  set target(String value) {
+    JS("void", "#.target = #", this, value);
+  }
 
   // From HTMLHyperlinkElementUtils
 
-  String hash;
+  String get hash => JS("String", "#.hash", this);
 
-  String host;
+  set hash(String value) {
+    JS("void", "#.hash = #", this, value);
+  }
 
-  String hostname;
+  String get host => JS("String", "#.host", this);
 
-  String href;
+  set host(String value) {
+    JS("void", "#.host = #", this, value);
+  }
 
-  final String origin;
+  String get hostname => JS("String", "#.hostname", this);
 
-  String password;
+  set hostname(String value) {
+    JS("void", "#.hostname = #", this, value);
+  }
 
-  String pathname;
+  String get href => JS("String", "#.href", this);
 
-  String port;
+  set href(String value) {
+    JS("void", "#.href = #", this, value);
+  }
 
-  String protocol;
+  String get origin => JS("String", "#.origin", this);
 
-  String search;
+  String get password => JS("String", "#.password", this);
 
-  String username;
+  set password(String value) {
+    JS("void", "#.password = #", this, value);
+  }
+
+  String get pathname => JS("String", "#.pathname", this);
+
+  set pathname(String value) {
+    JS("void", "#.pathname = #", this, value);
+  }
+
+  String get port => JS("String", "#.port", this);
+
+  set port(String value) {
+    JS("void", "#.port = #", this, value);
+  }
+
+  String get protocol => JS("String", "#.protocol", this);
+
+  set protocol(String value) {
+    JS("void", "#.protocol = #", this, value);
+  }
+
+  String get search => JS("String", "#.search", this);
+
+  set search(String value) {
+    JS("void", "#.search = #", this, value);
+  }
+
+  String get username => JS("String", "#.username", this);
+
+  set username(String value) {
+    JS("void", "#.username = #", this, value);
+  }
 
   String toString() => JS('String', 'String(#)', this);
 }
@@ -1008,7 +1161,7 @@
 
 @Native("HTMLAudioElement")
 class AudioElement extends MediaElement {
-  factory AudioElement._([String src]) {
+  factory AudioElement._([String? src]) {
     if (src != null) {
       return AudioElement._create_1(src);
     }
@@ -1036,9 +1189,10 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final ByteBuffer authenticatorData;
+  ByteBuffer get authenticatorData =>
+      JS("ByteBuffer", "#.authenticatorData", this);
 
-  final ByteBuffer signature;
+  ByteBuffer get signature => JS("ByteBuffer", "#.signature", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1051,7 +1205,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final ByteBuffer attestationObject;
+  ByteBuffer get attestationObject =>
+      JS("ByteBuffer", "#.attestationObject", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1065,7 +1220,7 @@
   }
 
   @JSName('clientDataJSON')
-  final ByteBuffer clientDataJson;
+  ByteBuffer get clientDataJson => JS("ByteBuffer", "#.clientDataJSON", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1078,8 +1233,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory BRElement() => JS('returns:BRElement;creates:BRElement;new:true',
-      '#.createElement(#)', document, "br");
+  factory BRElement() => JS<BRElement>(
+      'returns:BRElement;creates:BRElement;new:true',
+      '#.createElement(#)',
+      document,
+      "br");
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1108,7 +1266,7 @@
       type,
       init);
 
-  final String state;
+  String get state => JS("String", "#.state", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1128,7 +1286,7 @@
   static BackgroundFetchEvent _create_1(type, init) =>
       JS('BackgroundFetchEvent', 'new BackgroundFetchEvent(#,#)', type, init);
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1151,7 +1309,8 @@
       type,
       init);
 
-  final List<BackgroundFetchSettledFetch> fetches;
+  List<BackgroundFetchSettledFetch> get fetches =>
+      JS("List<BackgroundFetchSettledFetch>", "#.fetches", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1164,7 +1323,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final _Request request;
+  _Request get request => JS("_Request", "#.request", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1178,7 +1337,7 @@
   }
 
   Future<BackgroundFetchRegistration> fetch(String id, Object requests,
-      [Map options]) {
+      [Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -1205,19 +1364,19 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int downloadTotal;
+  int get downloadTotal => JS("int", "#.downloadTotal", this);
 
-  final int downloaded;
+  int get downloaded => JS("int", "#.downloaded", this);
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
-  final String title;
+  String get title => JS("String", "#.title", this);
 
-  final int totalDownloadSize;
+  int get totalDownloadSize => JS("int", "#.totalDownloadSize", this);
 
-  final int uploadTotal;
+  int get uploadTotal => JS("int", "#.uploadTotal", this);
 
-  final int uploaded;
+  int get uploaded => JS("int", "#.uploaded", this);
 
   Future<bool> abort() => promiseToFuture<bool>(JS("", "#.abort()", this));
 }
@@ -1241,7 +1400,7 @@
       request,
       response);
 
-  final _Response response;
+  final _Response? response;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1261,7 +1420,8 @@
   static BackgroundFetchedEvent _create_1(type, init) => JS(
       'BackgroundFetchedEvent', 'new BackgroundFetchedEvent(#,#)', type, init);
 
-  final List<BackgroundFetchSettledFetch> fetches;
+  List<BackgroundFetchSettledFetch> get fetches =>
+      JS("List<BackgroundFetchSettledFetch>", "#.fetches", this);
 
   Future updateUI(String title) =>
       promiseToFuture(JS("", "#.updateUI(#)", this, title));
@@ -1279,7 +1439,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool visible;
+  bool get visible => JS("bool", "#.visible", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1312,7 +1472,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory BaseElement() => JS(
+  factory BaseElement() => JS<BaseElement>(
       'returns:BaseElement;creates:BaseElement;new:true',
       '#.createElement(#)',
       document,
@@ -1324,9 +1484,17 @@
    */
   BaseElement.created() : super.created();
 
-  String href;
+  String get href => JS("String", "#.href", this);
 
-  String target;
+  set href(String value) {
+    JS("void", "#.href = #", this, value);
+  }
+
+  String get target => JS("String", "#.target", this);
+
+  set target(String value) {
+    JS("void", "#.target = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1339,13 +1507,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool charging;
+  bool get charging => JS("bool", "#.charging", this);
 
-  final num chargingTime;
+  num get chargingTime => JS("num", "#.chargingTime", this);
 
-  final num dischargingTime;
+  num get dischargingTime => JS("num", "#.dischargingTime", this);
 
-  final num level;
+  num get level => JS("num", "#.level", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1358,7 +1526,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory BeforeInstallPromptEvent(String type, [Map eventInitDict]) {
+  factory BeforeInstallPromptEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return BeforeInstallPromptEvent._create_1(type, eventInitDict_1);
@@ -1373,10 +1541,9 @@
   static BeforeInstallPromptEvent _create_2(type) =>
       JS('BeforeInstallPromptEvent', 'new BeforeInstallPromptEvent(#)', type);
 
-  final List<String> platforms;
+  List<String> get platforms => JS("List<String>", "#.platforms", this);
 
-  Future<Map<String, dynamic>> get userChoice =>
-      promiseToFutureAsMap(JS("", "#.userChoice", this));
+  Future get userChoice => JS("Future", "#.userChoice", this);
 
   Future prompt() => promiseToFuture(JS("", "#.prompt()", this));
 }
@@ -1392,6 +1559,7 @@
   }
 
   // Shadowing definition.
+
   String get returnValue => JS("String", "#.returnValue", this);
 
   set returnValue(String value) {
@@ -1409,11 +1577,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int size;
+  int get size => JS("int", "#.size", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
-  Blob slice([int start, int end, String contentType]) native;
+  Blob slice([int? start, int? end, String? contentType]) native;
 
   factory Blob(List blobParts, [String type, String endings]) {
     // TODO: validate that blobParts is a JS Array and convert if not.
@@ -1442,7 +1610,7 @@
 
 // WARNING: Do not edit - generated code.
 
-typedef void BlobCallback(Blob blob);
+typedef void BlobCallback(Blob? blob);
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
@@ -1461,9 +1629,9 @@
   static BlobEvent _create_1(type, eventInitDict) =>
       JS('BlobEvent', 'new BlobEvent(#,#)', type, eventInitDict);
 
-  final Blob data;
+  Blob get data => JS("Blob", "#.data", this);
 
-  final num timecode;
+  num get timecode => JS("num", "#.timecode", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1476,11 +1644,12 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final _BluetoothRemoteGATTCharacteristic characteristic;
+  _BluetoothRemoteGATTCharacteristic get characteristic =>
+      JS("_BluetoothRemoteGATTCharacteristic", "#.characteristic", this);
 
-  final String uuid;
+  String get uuid => JS("String", "#.uuid", this);
 
-  final ByteData value;
+  final ByteData? value;
 
   Future readValue() => promiseToFuture(JS("", "#.readValue()", this));
 
@@ -1498,7 +1667,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool bodyUsed;
+  bool get bodyUsed => JS("bool", "#.bodyUsed", this);
 
   Future arrayBuffer() => promiseToFuture(JS("", "#.arrayBuffer()", this));
 
@@ -1633,7 +1802,7 @@
   static const EventStreamProvider<Event> unloadEvent =
       const EventStreamProvider<Event>('unload');
 
-  factory BodyElement() => JS(
+  factory BodyElement() => JS<BodyElement>(
       'returns:BodyElement;creates:BodyElement;new:true',
       '#.createElement(#)',
       document,
@@ -1703,7 +1872,7 @@
   static BroadcastChannel _create_1(name) =>
       JS('BroadcastChannel', 'new BroadcastChannel(#)', name);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
   void close() native;
 
@@ -1722,9 +1891,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num budgetAt;
+  num get budgetAt => JS("num", "#.budgetAt", this);
 
-  final int time;
+  int get time => JS("int", "#.time", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1737,7 +1906,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ButtonElement() => JS(
+  factory ButtonElement() => JS<ButtonElement>(
       'returns:ButtonElement;creates:ButtonElement;new:true',
       '#.createElement(#)',
       document,
@@ -1749,38 +1918,78 @@
    */
   ButtonElement.created() : super.created();
 
-  bool autofocus;
+  bool get autofocus => JS("bool", "#.autofocus", this);
 
-  bool disabled;
+  set autofocus(bool value) {
+    JS("void", "#.autofocus = #", this, value);
+  }
 
-  final FormElement form;
+  bool get disabled => JS("bool", "#.disabled", this);
 
-  String formAction;
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
 
-  String formEnctype;
+  final FormElement? form;
 
-  String formMethod;
+  String get formAction => JS("String", "#.formAction", this);
 
-  bool formNoValidate;
+  set formAction(String value) {
+    JS("void", "#.formAction = #", this, value);
+  }
 
-  String formTarget;
+  String get formEnctype => JS("String", "#.formEnctype", this);
+
+  set formEnctype(String value) {
+    JS("void", "#.formEnctype = #", this, value);
+  }
+
+  String get formMethod => JS("String", "#.formMethod", this);
+
+  set formMethod(String value) {
+    JS("void", "#.formMethod = #", this, value);
+  }
+
+  bool get formNoValidate => JS("bool", "#.formNoValidate", this);
+
+  set formNoValidate(bool value) {
+    JS("void", "#.formNoValidate = #", this, value);
+  }
+
+  String get formTarget => JS("String", "#.formTarget", this);
+
+  set formTarget(String value) {
+    JS("void", "#.formTarget = #", this, value);
+  }
 
   @Unstable()
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  final List<Node> labels;
+  List<Node> get labels => JS("NodeList", "#.labels", this);
 
-  String name;
+  String get name => JS("String", "#.name", this);
 
-  String type;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
-  final String validationMessage;
+  String get type => JS("String", "#.type", this);
 
-  final ValidityState validity;
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 
-  String value;
+  String get validationMessage => JS("String", "#.validationMessage", this);
 
-  final bool willValidate;
+  ValidityState get validity => JS("ValidityState", "#.validity", this);
+
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
+
+  bool get willValidate => JS("bool", "#.willValidate", this);
 
   bool checkValidity() native;
 
@@ -1820,7 +2029,7 @@
 
   Future keys() => promiseToFuture(JS("", "#.keys()", this));
 
-  Future match(/*RequestInfo*/ request, [Map options]) {
+  Future match(/*RequestInfo*/ request, [Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -1853,13 +2062,14 @@
       type,
       eventInitDict);
 
-  final List methodData;
+  List get methodData => JS("List", "#.methodData", this);
 
-  final List modifiers;
+  List get modifiers => JS("List", "#.modifiers", this);
 
-  final String paymentRequestOrigin;
+  String get paymentRequestOrigin =>
+      JS("String", "#.paymentRequestOrigin", this);
 
-  final String topLevelOrigin;
+  String get topLevelOrigin => JS("String", "#.topLevelOrigin", this);
 
   void respondWith(Future canMakePaymentResponse) native;
 }
@@ -1874,7 +2084,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final CanvasElement canvas;
+  CanvasElement get canvas => JS("CanvasElement", "#.canvas", this);
 
   void requestFrame() native;
 }
@@ -1907,9 +2117,12 @@
   static const EventStreamProvider<gl.ContextEvent> webGlContextRestoredEvent =
       const EventStreamProvider<gl.ContextEvent>('webglcontextrestored');
 
-  factory CanvasElement({int width, int height}) {
-    CanvasElement e = JS('returns:CanvasElement;creates:CanvasElement;new:true',
-        '#.createElement(#)', document, "canvas");
+  factory CanvasElement({int? width, int? height}) {
+    CanvasElement e = JS<CanvasElement>(
+        'returns:CanvasElement;creates:CanvasElement;new:true',
+        '#.createElement(#)',
+        document,
+        "canvas");
     if (width != null) e.width = width;
     if (height != null) e.height = height;
     return e;
@@ -1922,16 +2135,30 @@
   CanvasElement.created() : super.created();
 
   /// The height of this canvas element in CSS pixels.
-  int height;
+
+  int get height => JS("int", "#.height", this);
+
+  /// The height of this canvas element in CSS pixels.
+
+  set height(int value) {
+    JS("void", "#.height = #", this, value);
+  }
 
   /// The width of this canvas element in CSS pixels.
-  int width;
 
-  MediaStream captureStream([num frameRate]) native;
+  int get width => JS("int", "#.width", this);
+
+  /// The width of this canvas element in CSS pixels.
+
+  set width(int value) {
+    JS("void", "#.width = #", this, value);
+  }
+
+  MediaStream captureStream([num? frameRate]) native;
 
   @Creates('CanvasRenderingContext2D|RenderingContext|RenderingContext2')
   @Returns('CanvasRenderingContext2D|RenderingContext|RenderingContext2|Null')
-  Object getContext(String contextId, [Map attributes]) {
+  Object getContext(String contextId, [Map? attributes]) {
     if (attributes != null) {
       var attributes_1 = convertDartToNative_Dictionary(attributes);
       return _getContext_1(contextId, attributes_1);
@@ -2043,9 +2270,9 @@
       _toDataUrl(type, quality);
 
   @JSName('toBlob')
-  void _toBlob(BlobCallback callback, String type, [Object arguments]) native;
+  void _toBlob(BlobCallback callback, String type, [Object? arguments]) native;
 
-  Future<Blob> toBlob(String type, [Object arguments]) {
+  Future<Blob> toBlob(String type, [Object? arguments]) {
     var completer = new Completer<Blob>();
     _toBlob((value) {
       completer.complete(value);
@@ -2162,23 +2389,54 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final CanvasElement canvas;
+  CanvasElement get canvas => JS("CanvasElement", "#.canvas", this);
 
-  Matrix currentTransform;
+  Matrix get currentTransform => JS("Matrix", "#.currentTransform", this);
 
-  String direction;
+  set currentTransform(Matrix value) {
+    JS("void", "#.currentTransform = #", this, value);
+  }
+
+  String get direction => JS("String", "#.direction", this);
+
+  set direction(String value) {
+    JS("void", "#.direction = #", this, value);
+  }
 
   @Creates('String|CanvasGradient|CanvasPattern')
   @Returns('String|CanvasGradient|CanvasPattern')
-  Object fillStyle;
+  Object get fillStyle => JS("Object", "#.fillStyle", this);
 
-  String filter;
+  @Creates('String|CanvasGradient|CanvasPattern')
+  @Returns('String|CanvasGradient|CanvasPattern')
+  set fillStyle(Object value) {
+    JS("void", "#.fillStyle = #", this, value);
+  }
 
-  String font;
+  String get filter => JS("String", "#.filter", this);
 
-  num globalAlpha;
+  set filter(String value) {
+    JS("void", "#.filter = #", this, value);
+  }
 
-  String globalCompositeOperation;
+  String get font => JS("String", "#.font", this);
+
+  set font(String value) {
+    JS("void", "#.font = #", this, value);
+  }
+
+  num get globalAlpha => JS("num", "#.globalAlpha", this);
+
+  set globalAlpha(num value) {
+    JS("void", "#.globalAlpha = #", this, value);
+  }
+
+  String get globalCompositeOperation =>
+      JS("String", "#.globalCompositeOperation", this);
+
+  set globalCompositeOperation(String value) {
+    JS("void", "#.globalCompositeOperation = #", this, value);
+  }
 
   /**
    * Whether images and patterns on this canvas will be smoothed when this
@@ -2190,35 +2448,102 @@
    *   smoothing](https://html.spec.whatwg.org/multipage/scripting.html#image-smoothing)
    *   from WHATWG.
    */
-  bool imageSmoothingEnabled;
 
-  String imageSmoothingQuality;
+  bool get imageSmoothingEnabled => JS("bool", "#.imageSmoothingEnabled", this);
 
-  String lineCap;
+  /**
+   * Whether images and patterns on this canvas will be smoothed when this
+   * canvas is scaled.
+   *
+   * ## Other resources
+   *
+   * * [Image
+   *   smoothing](https://html.spec.whatwg.org/multipage/scripting.html#image-smoothing)
+   *   from WHATWG.
+   */
 
-  String lineJoin;
+  set imageSmoothingEnabled(bool value) {
+    JS("void", "#.imageSmoothingEnabled = #", this, value);
+  }
 
-  num lineWidth;
+  String get imageSmoothingQuality =>
+      JS("String", "#.imageSmoothingQuality", this);
 
-  num miterLimit;
+  set imageSmoothingQuality(String value) {
+    JS("void", "#.imageSmoothingQuality = #", this, value);
+  }
 
-  num shadowBlur;
+  String get lineCap => JS("String", "#.lineCap", this);
 
-  String shadowColor;
+  set lineCap(String value) {
+    JS("void", "#.lineCap = #", this, value);
+  }
 
-  num shadowOffsetX;
+  String get lineJoin => JS("String", "#.lineJoin", this);
 
-  num shadowOffsetY;
+  set lineJoin(String value) {
+    JS("void", "#.lineJoin = #", this, value);
+  }
+
+  num get lineWidth => JS("num", "#.lineWidth", this);
+
+  set lineWidth(num value) {
+    JS("void", "#.lineWidth = #", this, value);
+  }
+
+  num get miterLimit => JS("num", "#.miterLimit", this);
+
+  set miterLimit(num value) {
+    JS("void", "#.miterLimit = #", this, value);
+  }
+
+  num get shadowBlur => JS("num", "#.shadowBlur", this);
+
+  set shadowBlur(num value) {
+    JS("void", "#.shadowBlur = #", this, value);
+  }
+
+  String get shadowColor => JS("String", "#.shadowColor", this);
+
+  set shadowColor(String value) {
+    JS("void", "#.shadowColor = #", this, value);
+  }
+
+  num get shadowOffsetX => JS("num", "#.shadowOffsetX", this);
+
+  set shadowOffsetX(num value) {
+    JS("void", "#.shadowOffsetX = #", this, value);
+  }
+
+  num get shadowOffsetY => JS("num", "#.shadowOffsetY", this);
+
+  set shadowOffsetY(num value) {
+    JS("void", "#.shadowOffsetY = #", this, value);
+  }
 
   @Creates('String|CanvasGradient|CanvasPattern')
   @Returns('String|CanvasGradient|CanvasPattern')
-  Object strokeStyle;
+  Object get strokeStyle => JS("Object", "#.strokeStyle", this);
 
-  String textAlign;
+  @Creates('String|CanvasGradient|CanvasPattern')
+  @Returns('String|CanvasGradient|CanvasPattern')
+  set strokeStyle(Object value) {
+    JS("void", "#.strokeStyle = #", this, value);
+  }
 
-  String textBaseline;
+  String get textAlign => JS("String", "#.textAlign", this);
 
-  void addHitRegion([Map options]) {
+  set textAlign(String value) {
+    JS("void", "#.textAlign = #", this, value);
+  }
+
+  String get textBaseline => JS("String", "#.textBaseline", this);
+
+  set textBaseline(String value) {
+    JS("void", "#.textBaseline = #", this, value);
+  }
+
+  void addHitRegion([Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       _addHitRegion_1(options_1);
@@ -2239,13 +2564,13 @@
 
   void clearRect(num x, num y, num width, num height) native;
 
-  void clip([path_OR_winding, String winding]) native;
+  void clip([path_OR_winding, String? winding]) native;
 
   @Creates('ImageData|=Object')
   ImageData createImageData(data_OR_imagedata_OR_sw,
-      [int sh_OR_sw,
+      [int? sh_OR_sw,
       imageDataColorSettings_OR_sh,
-      Map imageDataColorSettings]) {
+      Map? imageDataColorSettings]) {
     if ((data_OR_imagedata_OR_sw is ImageData) &&
         sh_OR_sw == null &&
         imageDataColorSettings_OR_sh == null &&
@@ -2314,9 +2639,9 @@
   CanvasGradient createRadialGradient(
       num x0, num y0, num r0, num x1, num y1, num r1) native;
 
-  void drawFocusIfNeeded(element_OR_path, [Element element]) native;
+  void drawFocusIfNeeded(element_OR_path, [Element? element]) native;
 
-  void fill([path_OR_winding, String winding]) native;
+  void fill([path_OR_winding, String? winding]) native;
 
   void fillRect(num x, num y, num width, num height) native;
 
@@ -2341,15 +2666,15 @@
 
   bool isContextLost() native;
 
-  bool isPointInPath(path_OR_x, num x_OR_y, [winding_OR_y, String winding])
+  bool isPointInPath(path_OR_x, num x_OR_y, [winding_OR_y, String? winding])
       native;
 
-  bool isPointInStroke(path_OR_x, num x_OR_y, [num y]) native;
+  bool isPointInStroke(path_OR_x, num x_OR_y, [num? y]) native;
 
   TextMetrics measureText(String text) native;
 
   void putImageData(ImageData imagedata, int dx, int dy,
-      [int dirtyX, int dirtyY, int dirtyWidth, int dirtyHeight]) {
+      [int? dirtyX, int? dirtyY, int? dirtyWidth, int? dirtyHeight]) {
     if (dirtyX == null &&
         dirtyY == null &&
         dirtyWidth == null &&
@@ -2388,15 +2713,15 @@
 
   void scale(num x, num y) native;
 
-  void scrollPathIntoView([Path2D path]) native;
+  void scrollPathIntoView([Path2D? path]) native;
 
   void setTransform(num a, num b, num c, num d, num e, num f) native;
 
-  void stroke([Path2D path]) native;
+  void stroke([Path2D? path]) native;
 
   void strokeRect(num x, num y, num width, num height) native;
 
-  void strokeText(String text, num x, num y, [num maxWidth]) native;
+  void strokeText(String text, num x, num y, [num? maxWidth]) native;
 
   void transform(num a, num b, num c, num d, num e, num f) native;
 
@@ -2731,9 +3056,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String data;
+  String get data => JS("String", "#.data", this);
 
-  final int length;
+  set data(String value) {
+    JS("void", "#.data = #", this, value);
+  }
+
+  int get length => JS("int", "#.length", this);
 
   void appendData(String data) native;
 
@@ -2753,9 +3082,9 @@
 
   // From NonDocumentTypeChildNode
 
-  final Element nextElementSibling;
+  final Element? nextElementSibling;
 
-  final Element previousElementSibling;
+  final Element? previousElementSibling;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2784,15 +3113,15 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String frameType;
+  String get frameType => JS("String", "#.frameType", this);
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
-  final String url;
+  String get url => JS("String", "#.url", this);
 
-  void postMessage(Object message, [List<Object> transfer]) native;
+  void postMessage(Object message, [List<Object>? transfer]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2809,7 +3138,7 @@
 
   Future get(String id) => promiseToFuture(JS("", "#.get(#)", this, id));
 
-  Future<List<dynamic>> matchAll([Map options]) {
+  Future<List<dynamic>> matchAll([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -2832,7 +3161,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ClipboardEvent(String type, [Map eventInitDict]) {
+  factory ClipboardEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return ClipboardEvent._create_1(type, eventInitDict_1);
@@ -2844,7 +3173,7 @@
   static ClipboardEvent _create_2(type) =>
       JS('ClipboardEvent', 'new ClipboardEvent(#)', type);
 
-  final DataTransfer clipboardData;
+  final DataTransfer? clipboardData;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2857,7 +3186,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory CloseEvent(String type, [Map eventInitDict]) {
+  factory CloseEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return CloseEvent._create_1(type, eventInitDict_1);
@@ -2869,11 +3198,11 @@
   static CloseEvent _create_2(type) =>
       JS('CloseEvent', 'new CloseEvent(#)', type);
 
-  final int code;
+  int get code => JS("int", "#.code", this);
 
-  final String reason;
+  String get reason => JS("String", "#.reason", this);
 
-  final bool wasClean;
+  bool get wasClean => JS("bool", "#.wasClean", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2920,7 +3249,7 @@
     return e;
   }
 
-  factory CompositionEvent._(String type, [Map eventInitDict]) {
+  factory CompositionEvent._(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return CompositionEvent._create_1(type, eventInitDict_1);
@@ -2932,11 +3261,11 @@
   static CompositionEvent _create_2(type) =>
       JS('CompositionEvent', 'new CompositionEvent(#)', type);
 
-  final String data;
+  String get data => JS("String", "#.data", this);
 
   @JSName('initCompositionEvent')
   void _initCompositionEvent(String type, bool bubbles, bool cancelable,
-      Window view, String data) native;
+      Window? view, String data) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2950,7 +3279,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ContentElement() => document.createElement("content");
+  factory ContentElement() =>
+      document.createElement("content") as ContentElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2961,7 +3291,11 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('content');
 
-  String select;
+  String get select => JS("String", "#.select", this);
+
+  set select(String value) {
+    JS("void", "#.select = #", this, value);
+  }
 
   @Returns('NodeList|Null')
   @Creates('NodeList')
@@ -2978,7 +3312,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  Future getAll([Map options]) {
+  Future getAll([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -2986,7 +3320,7 @@
     return promiseToFuture(JS("", "#.getAll(#)", this, options_dict));
   }
 
-  Future set(String name, String value, [Map options]) {
+  Future set(String name, String value, [Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -3006,7 +3340,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num accuracy;
+  num get accuracy => JS("num", "#.accuracy", this);
 
   final num altitude;
 
@@ -3014,9 +3348,9 @@
 
   final num heading;
 
-  final num latitude;
+  num get latitude => JS("num", "#.latitude", this);
 
-  final num longitude;
+  num get longitude => JS("num", "#.longitude", this);
 
   final num speed;
 }
@@ -3031,9 +3365,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3047,9 +3381,9 @@
   }
 
   @JSName('iconURL')
-  final String iconUrl;
+  String get iconUrl => JS("String", "#.iconURL", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3062,7 +3396,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  Future create([Map options]) {
+  Future create([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -3070,7 +3404,7 @@
     return promiseToFuture(JS("", "#.create(#)", this, options_dict));
   }
 
-  Future get([Map options]) {
+  Future get([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -3108,7 +3442,7 @@
   static bool get supported =>
       JS('bool', '!!(window.crypto && window.crypto.getRandomValues)');
 
-  final _SubtleCrypto subtle;
+  _SubtleCrypto get subtle => JS("_SubtleCrypto", "#.subtle", this);
 
   @JSName('getRandomValues')
   @Creates('TypedData')
@@ -3127,13 +3461,13 @@
   }
 
   @Creates('Null')
-  final Object algorithm;
+  Object get algorithm => JS("Object", "#.algorithm", this);
 
-  final bool extractable;
+  bool get extractable => JS("bool", "#.extractable", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
-  final Object usages;
+  Object get usages => JS("Object", "#.usages", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3146,7 +3480,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  static final _Worklet paintWorklet;
+  _Worklet get paintWorklet => JS("_Worklet", "#.paintWorklet", this);
 
   static CssUnitValue Hz(num value) native;
 
@@ -3232,7 +3566,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String encoding;
+  String get encoding => JS("String", "#.encoding", this);
+
+  set encoding(String value) {
+    JS("void", "#.encoding = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3245,7 +3583,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String conditionText;
+  String get conditionText => JS("String", "#.conditionText", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3258,7 +3596,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final CssStyleDeclaration style;
+  CssStyleDeclaration get style => JS("CssStyleDeclaration", "#.style", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3273,7 +3611,7 @@
 
   @Returns('_CssRuleList|Null')
   @Creates('_CssRuleList')
-  final List<CssRule> cssRules;
+  List<CssRule> get cssRules => JS("_CssRuleList", "#.cssRules", this);
 
   void deleteRule(int index) native;
 
@@ -3307,11 +3645,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String href;
+  String get href => JS("String", "#.href", this);
 
-  final MediaList media;
+  MediaList get media => JS("MediaList", "#.media", this);
 
-  final CssStyleSheet styleSheet;
+  CssStyleSheet get styleSheet => JS("CssStyleSheet", "#.styleSheet", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3324,9 +3662,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String keyText;
+  String get keyText => JS("String", "#.keyText", this);
 
-  final CssStyleDeclaration style;
+  set keyText(String value) {
+    JS("void", "#.keyText = #", this, value);
+  }
+
+  CssStyleDeclaration get style => JS("CssStyleDeclaration", "#.style", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3341,9 +3683,13 @@
 
   @Returns('_CssRuleList|Null')
   @Creates('_CssRuleList')
-  final List<CssRule> cssRules;
+  List<CssRule> get cssRules => JS("_CssRuleList", "#.cssRules", this);
 
-  String name;
+  String get name => JS("String", "#.name", this);
+
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
   CssKeyframeRule __getter__(int index) native;
 
@@ -3370,7 +3716,11 @@
   static CssKeywordValue _create_1(keyword) =>
       JS('CssKeywordValue', 'new CSSKeywordValue(#)', keyword);
 
-  String value;
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3383,7 +3733,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory CssMatrixComponent(DomMatrixReadOnly matrix, [Map options]) {
+  factory CssMatrixComponent(DomMatrixReadOnly matrix, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return CssMatrixComponent._create_1(matrix, options_1);
@@ -3395,7 +3745,11 @@
   static CssMatrixComponent _create_2(matrix) =>
       JS('CssMatrixComponent', 'new CSSMatrixComponent(#)', matrix);
 
-  DomMatrix matrix;
+  DomMatrix get matrix => JS("DomMatrix", "#.matrix", this);
+
+  set matrix(DomMatrix value) {
+    JS("void", "#.matrix = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3408,7 +3762,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final MediaList media;
+  MediaList get media => JS("MediaList", "#.media", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3422,9 +3776,9 @@
   }
 
   @JSName('namespaceURI')
-  final String namespaceUri;
+  String get namespaceUri => JS("String", "#.namespaceURI", this);
 
-  final String prefix;
+  String get prefix => JS("String", "#.prefix", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3460,9 +3814,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String selectorText;
+  String get selectorText => JS("String", "#.selectorText", this);
 
-  final CssStyleDeclaration style;
+  set selectorText(String value) {
+    JS("void", "#.selectorText = #", this, value);
+  }
+
+  CssStyleDeclaration get style => JS("CssStyleDeclaration", "#.style", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3481,7 +3839,11 @@
   static CssPerspective _create_1(length) =>
       JS('CssPerspective', 'new CSSPerspective(#)', length);
 
-  CssNumericValue length;
+  CssNumericValue get length => JS("CssNumericValue", "#.length", this);
+
+  set length(CssNumericValue value) {
+    JS("void", "#.length = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3500,9 +3862,17 @@
   static CssPositionValue _create_1(x, y) =>
       JS('CssPositionValue', 'new CSSPositionValue(#,#)', x, y);
 
-  CssNumericValue x;
+  CssNumericValue get x => JS("CssNumericValue", "#.x", this);
 
-  CssNumericValue y;
+  set x(CssNumericValue value) {
+    JS("void", "#.x = #", this, value);
+  }
+
+  CssNumericValue get y => JS("CssNumericValue", "#.y", this);
+
+  set y(CssNumericValue value) {
+    JS("void", "#.y = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3515,7 +3885,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String state;
+  String get state => JS("String", "#.state", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3528,7 +3898,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory CssRotation(angleValue_OR_x, [num y, num z, CssNumericValue angle]) {
+  factory CssRotation(angleValue_OR_x,
+      [num? y, num? z, CssNumericValue? angle]) {
     if ((angleValue_OR_x is CssNumericValue) &&
         y == null &&
         z == null &&
@@ -3548,13 +3919,29 @@
   static CssRotation _create_2(angleValue_OR_x, y, z, angle) => JS(
       'CssRotation', 'new CSSRotation(#,#,#,#)', angleValue_OR_x, y, z, angle);
 
-  CssNumericValue angle;
+  CssNumericValue get angle => JS("CssNumericValue", "#.angle", this);
 
-  num x;
+  set angle(CssNumericValue value) {
+    JS("void", "#.angle = #", this, value);
+  }
 
-  num y;
+  num get x => JS("num", "#.x", this);
 
-  num z;
+  set x(num value) {
+    JS("void", "#.x = #", this, value);
+  }
+
+  num get y => JS("num", "#.y", this);
+
+  set y(num value) {
+    JS("void", "#.y = #", this, value);
+  }
+
+  num get z => JS("num", "#.z", this);
+
+  set z(num value) {
+    JS("void", "#.z = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3589,13 +3976,17 @@
 
   static const int VIEWPORT_RULE = 15;
 
-  String cssText;
+  String get cssText => JS("String", "#.cssText", this);
 
-  final CssRule parentRule;
+  set cssText(String value) {
+    JS("void", "#.cssText = #", this, value);
+  }
 
-  final CssStyleSheet parentStyleSheet;
+  final CssRule? parentRule;
 
-  final int type;
+  final CssStyleSheet? parentStyleSheet;
+
+  int get type => JS("int", "#.type", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3608,7 +3999,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory CssScale(num x, num y, [num z]) {
+  factory CssScale(num x, num y, [num? z]) {
     if ((y is num) && (x is num) && z == null) {
       return CssScale._create_1(x, y);
     }
@@ -3621,11 +4012,23 @@
   static CssScale _create_2(x, y, z) =>
       JS('CssScale', 'new CSSScale(#,#,#)', x, y, z);
 
-  num x;
+  num get x => JS("num", "#.x", this);
 
-  num y;
+  set x(num value) {
+    JS("void", "#.x = #", this, value);
+  }
 
-  num z;
+  num get y => JS("num", "#.y", this);
+
+  set y(num value) {
+    JS("void", "#.y = #", this, value);
+  }
+
+  num get z => JS("num", "#.z", this);
+
+  set z(num value) {
+    JS("void", "#.z = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3643,9 +4046,17 @@
   }
   static CssSkew _create_1(ax, ay) => JS('CssSkew', 'new CSSSkew(#,#)', ax, ay);
 
-  CssNumericValue ax;
+  CssNumericValue get ax => JS("CssNumericValue", "#.ax", this);
 
-  CssNumericValue ay;
+  set ax(CssNumericValue value) {
+    JS("void", "#.ax = #", this, value);
+  }
+
+  CssNumericValue get ay => JS("CssNumericValue", "#.ay", this);
+
+  set ay(CssNumericValue value) {
+    JS("void", "#.ay = #", this, value);
+  }
 }
 
 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
@@ -3705,7 +4116,7 @@
   }
 
   String _browserPropertyName(String propertyName) {
-    String name = _readCache(propertyName);
+    String? name = _readCache(propertyName);
     if (name is String) return name;
     name = _supportedBrowserPropertyName(propertyName);
     _writeCache(propertyName, name);
@@ -3725,7 +4136,7 @@
   }
 
   static final _propertyCache = JS('', '{}');
-  static String _readCache(String key) =>
+  static String? _readCache(String key) =>
       JS('String|Null', '#[#]', _propertyCache, key);
   static void _writeCache(String key, String value) {
     JS('void', '#[#] = #', _propertyCache, key, value);
@@ -3740,8 +4151,8 @@
         replacedMs);
   }
 
-  void _setPropertyHelper(String propertyName, String value,
-      [String priority]) {
+  void _setPropertyHelper(String propertyName, String? value,
+      [String? priority]) {
     if (value == null) value = '';
     if (priority == null) priority = '';
     JS('void', '#.setProperty(#, #, #)', this, propertyName, value, priority);
@@ -3759,13 +4170,21 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String cssFloat;
+  String get cssFloat => JS("String", "#.cssFloat", this);
 
-  String cssText;
+  set cssFloat(String value) {
+    JS("void", "#.cssFloat = #", this, value);
+  }
 
-  final int length;
+  String get cssText => JS("String", "#.cssText", this);
 
-  final CssRule parentRule;
+  set cssText(String value) {
+    JS("void", "#.cssText = #", this, value);
+  }
+
+  int get length => JS("int", "#.length", this);
+
+  final CssRule? parentRule;
 
   String getPropertyPriority(String property) native;
 
@@ -3780,7 +4199,7 @@
   String get background => this._background;
 
   /** Sets the value of "background" */
-  set background(String value) {
+  set background(String? value) {
     _background = value == null ? '' : value;
   }
 
@@ -3792,7 +4211,7 @@
   String get backgroundAttachment => this._backgroundAttachment;
 
   /** Sets the value of "background-attachment" */
-  set backgroundAttachment(String value) {
+  set backgroundAttachment(String? value) {
     _backgroundAttachment = value == null ? '' : value;
   }
 
@@ -3804,7 +4223,7 @@
   String get backgroundColor => this._backgroundColor;
 
   /** Sets the value of "background-color" */
-  set backgroundColor(String value) {
+  set backgroundColor(String? value) {
     _backgroundColor = value == null ? '' : value;
   }
 
@@ -3816,7 +4235,7 @@
   String get backgroundImage => this._backgroundImage;
 
   /** Sets the value of "background-image" */
-  set backgroundImage(String value) {
+  set backgroundImage(String? value) {
     _backgroundImage = value == null ? '' : value;
   }
 
@@ -3828,7 +4247,7 @@
   String get backgroundPosition => this._backgroundPosition;
 
   /** Sets the value of "background-position" */
-  set backgroundPosition(String value) {
+  set backgroundPosition(String? value) {
     _backgroundPosition = value == null ? '' : value;
   }
 
@@ -3840,7 +4259,7 @@
   String get backgroundRepeat => this._backgroundRepeat;
 
   /** Sets the value of "background-repeat" */
-  set backgroundRepeat(String value) {
+  set backgroundRepeat(String? value) {
     _backgroundRepeat = value == null ? '' : value;
   }
 
@@ -3852,7 +4271,7 @@
   String get border => this._border;
 
   /** Sets the value of "border" */
-  set border(String value) {
+  set border(String? value) {
     _border = value == null ? '' : value;
   }
 
@@ -3864,7 +4283,7 @@
   String get borderBottom => this._borderBottom;
 
   /** Sets the value of "border-bottom" */
-  set borderBottom(String value) {
+  set borderBottom(String? value) {
     _borderBottom = value == null ? '' : value;
   }
 
@@ -3876,7 +4295,7 @@
   String get borderBottomColor => this._borderBottomColor;
 
   /** Sets the value of "border-bottom-color" */
-  set borderBottomColor(String value) {
+  set borderBottomColor(String? value) {
     _borderBottomColor = value == null ? '' : value;
   }
 
@@ -3888,7 +4307,7 @@
   String get borderBottomStyle => this._borderBottomStyle;
 
   /** Sets the value of "border-bottom-style" */
-  set borderBottomStyle(String value) {
+  set borderBottomStyle(String? value) {
     _borderBottomStyle = value == null ? '' : value;
   }
 
@@ -3900,7 +4319,7 @@
   String get borderBottomWidth => this._borderBottomWidth;
 
   /** Sets the value of "border-bottom-width" */
-  set borderBottomWidth(String value) {
+  set borderBottomWidth(String? value) {
     _borderBottomWidth = value == null ? '' : value;
   }
 
@@ -3912,7 +4331,7 @@
   String get borderCollapse => this._borderCollapse;
 
   /** Sets the value of "border-collapse" */
-  set borderCollapse(String value) {
+  set borderCollapse(String? value) {
     _borderCollapse = value == null ? '' : value;
   }
 
@@ -3924,7 +4343,7 @@
   String get borderColor => this._borderColor;
 
   /** Sets the value of "border-color" */
-  set borderColor(String value) {
+  set borderColor(String? value) {
     _borderColor = value == null ? '' : value;
   }
 
@@ -3936,7 +4355,7 @@
   String get borderLeft => this._borderLeft;
 
   /** Sets the value of "border-left" */
-  set borderLeft(String value) {
+  set borderLeft(String? value) {
     _borderLeft = value == null ? '' : value;
   }
 
@@ -3948,7 +4367,7 @@
   String get borderLeftColor => this._borderLeftColor;
 
   /** Sets the value of "border-left-color" */
-  set borderLeftColor(String value) {
+  set borderLeftColor(String? value) {
     _borderLeftColor = value == null ? '' : value;
   }
 
@@ -3960,7 +4379,7 @@
   String get borderLeftStyle => this._borderLeftStyle;
 
   /** Sets the value of "border-left-style" */
-  set borderLeftStyle(String value) {
+  set borderLeftStyle(String? value) {
     _borderLeftStyle = value == null ? '' : value;
   }
 
@@ -3972,7 +4391,7 @@
   String get borderLeftWidth => this._borderLeftWidth;
 
   /** Sets the value of "border-left-width" */
-  set borderLeftWidth(String value) {
+  set borderLeftWidth(String? value) {
     _borderLeftWidth = value == null ? '' : value;
   }
 
@@ -3984,7 +4403,7 @@
   String get borderRight => this._borderRight;
 
   /** Sets the value of "border-right" */
-  set borderRight(String value) {
+  set borderRight(String? value) {
     _borderRight = value == null ? '' : value;
   }
 
@@ -3996,7 +4415,7 @@
   String get borderRightColor => this._borderRightColor;
 
   /** Sets the value of "border-right-color" */
-  set borderRightColor(String value) {
+  set borderRightColor(String? value) {
     _borderRightColor = value == null ? '' : value;
   }
 
@@ -4008,7 +4427,7 @@
   String get borderRightStyle => this._borderRightStyle;
 
   /** Sets the value of "border-right-style" */
-  set borderRightStyle(String value) {
+  set borderRightStyle(String? value) {
     _borderRightStyle = value == null ? '' : value;
   }
 
@@ -4020,7 +4439,7 @@
   String get borderRightWidth => this._borderRightWidth;
 
   /** Sets the value of "border-right-width" */
-  set borderRightWidth(String value) {
+  set borderRightWidth(String? value) {
     _borderRightWidth = value == null ? '' : value;
   }
 
@@ -4032,7 +4451,7 @@
   String get borderSpacing => this._borderSpacing;
 
   /** Sets the value of "border-spacing" */
-  set borderSpacing(String value) {
+  set borderSpacing(String? value) {
     _borderSpacing = value == null ? '' : value;
   }
 
@@ -4044,7 +4463,7 @@
   String get borderStyle => this._borderStyle;
 
   /** Sets the value of "border-style" */
-  set borderStyle(String value) {
+  set borderStyle(String? value) {
     _borderStyle = value == null ? '' : value;
   }
 
@@ -4056,7 +4475,7 @@
   String get borderTop => this._borderTop;
 
   /** Sets the value of "border-top" */
-  set borderTop(String value) {
+  set borderTop(String? value) {
     _borderTop = value == null ? '' : value;
   }
 
@@ -4068,7 +4487,7 @@
   String get borderTopColor => this._borderTopColor;
 
   /** Sets the value of "border-top-color" */
-  set borderTopColor(String value) {
+  set borderTopColor(String? value) {
     _borderTopColor = value == null ? '' : value;
   }
 
@@ -4080,7 +4499,7 @@
   String get borderTopStyle => this._borderTopStyle;
 
   /** Sets the value of "border-top-style" */
-  set borderTopStyle(String value) {
+  set borderTopStyle(String? value) {
     _borderTopStyle = value == null ? '' : value;
   }
 
@@ -4092,7 +4511,7 @@
   String get borderTopWidth => this._borderTopWidth;
 
   /** Sets the value of "border-top-width" */
-  set borderTopWidth(String value) {
+  set borderTopWidth(String? value) {
     _borderTopWidth = value == null ? '' : value;
   }
 
@@ -4104,7 +4523,7 @@
   String get borderWidth => this._borderWidth;
 
   /** Sets the value of "border-width" */
-  set borderWidth(String value) {
+  set borderWidth(String? value) {
     _borderWidth = value == null ? '' : value;
   }
 
@@ -4116,7 +4535,7 @@
   String get bottom => this._bottom;
 
   /** Sets the value of "bottom" */
-  set bottom(String value) {
+  set bottom(String? value) {
     _bottom = value == null ? '' : value;
   }
 
@@ -4128,7 +4547,7 @@
   String get captionSide => this._captionSide;
 
   /** Sets the value of "caption-side" */
-  set captionSide(String value) {
+  set captionSide(String? value) {
     _captionSide = value == null ? '' : value;
   }
 
@@ -4140,7 +4559,7 @@
   String get clear => this._clear;
 
   /** Sets the value of "clear" */
-  set clear(String value) {
+  set clear(String? value) {
     _clear = value == null ? '' : value;
   }
 
@@ -4152,7 +4571,7 @@
   String get clip => this._clip;
 
   /** Sets the value of "clip" */
-  set clip(String value) {
+  set clip(String? value) {
     _clip = value == null ? '' : value;
   }
 
@@ -4164,7 +4583,7 @@
   String get color => this._color;
 
   /** Sets the value of "color" */
-  set color(String value) {
+  set color(String? value) {
     _color = value == null ? '' : value;
   }
 
@@ -4176,7 +4595,7 @@
   String get content => this._content;
 
   /** Sets the value of "content" */
-  set content(String value) {
+  set content(String? value) {
     _content = value == null ? '' : value;
   }
 
@@ -4188,7 +4607,7 @@
   String get cursor => this._cursor;
 
   /** Sets the value of "cursor" */
-  set cursor(String value) {
+  set cursor(String? value) {
     _cursor = value == null ? '' : value;
   }
 
@@ -4200,7 +4619,7 @@
   String get direction => this._direction;
 
   /** Sets the value of "direction" */
-  set direction(String value) {
+  set direction(String? value) {
     _direction = value == null ? '' : value;
   }
 
@@ -4212,7 +4631,7 @@
   String get display => this._display;
 
   /** Sets the value of "display" */
-  set display(String value) {
+  set display(String? value) {
     _display = value == null ? '' : value;
   }
 
@@ -4224,7 +4643,7 @@
   String get emptyCells => this._emptyCells;
 
   /** Sets the value of "empty-cells" */
-  set emptyCells(String value) {
+  set emptyCells(String? value) {
     _emptyCells = value == null ? '' : value;
   }
 
@@ -4236,7 +4655,7 @@
   String get font => this._font;
 
   /** Sets the value of "font" */
-  set font(String value) {
+  set font(String? value) {
     _font = value == null ? '' : value;
   }
 
@@ -4248,7 +4667,7 @@
   String get fontFamily => this._fontFamily;
 
   /** Sets the value of "font-family" */
-  set fontFamily(String value) {
+  set fontFamily(String? value) {
     _fontFamily = value == null ? '' : value;
   }
 
@@ -4260,7 +4679,7 @@
   String get fontSize => this._fontSize;
 
   /** Sets the value of "font-size" */
-  set fontSize(String value) {
+  set fontSize(String? value) {
     _fontSize = value == null ? '' : value;
   }
 
@@ -4272,7 +4691,7 @@
   String get fontStyle => this._fontStyle;
 
   /** Sets the value of "font-style" */
-  set fontStyle(String value) {
+  set fontStyle(String? value) {
     _fontStyle = value == null ? '' : value;
   }
 
@@ -4284,7 +4703,7 @@
   String get fontVariant => this._fontVariant;
 
   /** Sets the value of "font-variant" */
-  set fontVariant(String value) {
+  set fontVariant(String? value) {
     _fontVariant = value == null ? '' : value;
   }
 
@@ -4296,7 +4715,7 @@
   String get fontWeight => this._fontWeight;
 
   /** Sets the value of "font-weight" */
-  set fontWeight(String value) {
+  set fontWeight(String? value) {
     _fontWeight = value == null ? '' : value;
   }
 
@@ -4308,7 +4727,7 @@
   String get height => this._height;
 
   /** Sets the value of "height" */
-  set height(String value) {
+  set height(String? value) {
     _height = value == null ? '' : value;
   }
 
@@ -4320,7 +4739,7 @@
   String get left => this._left;
 
   /** Sets the value of "left" */
-  set left(String value) {
+  set left(String? value) {
     _left = value == null ? '' : value;
   }
 
@@ -4332,7 +4751,7 @@
   String get letterSpacing => this._letterSpacing;
 
   /** Sets the value of "letter-spacing" */
-  set letterSpacing(String value) {
+  set letterSpacing(String? value) {
     _letterSpacing = value == null ? '' : value;
   }
 
@@ -4344,7 +4763,7 @@
   String get lineHeight => this._lineHeight;
 
   /** Sets the value of "line-height" */
-  set lineHeight(String value) {
+  set lineHeight(String? value) {
     _lineHeight = value == null ? '' : value;
   }
 
@@ -4356,7 +4775,7 @@
   String get listStyle => this._listStyle;
 
   /** Sets the value of "list-style" */
-  set listStyle(String value) {
+  set listStyle(String? value) {
     _listStyle = value == null ? '' : value;
   }
 
@@ -4368,7 +4787,7 @@
   String get listStyleImage => this._listStyleImage;
 
   /** Sets the value of "list-style-image" */
-  set listStyleImage(String value) {
+  set listStyleImage(String? value) {
     _listStyleImage = value == null ? '' : value;
   }
 
@@ -4380,7 +4799,7 @@
   String get listStylePosition => this._listStylePosition;
 
   /** Sets the value of "list-style-position" */
-  set listStylePosition(String value) {
+  set listStylePosition(String? value) {
     _listStylePosition = value == null ? '' : value;
   }
 
@@ -4392,7 +4811,7 @@
   String get listStyleType => this._listStyleType;
 
   /** Sets the value of "list-style-type" */
-  set listStyleType(String value) {
+  set listStyleType(String? value) {
     _listStyleType = value == null ? '' : value;
   }
 
@@ -4404,7 +4823,7 @@
   String get margin => this._margin;
 
   /** Sets the value of "margin" */
-  set margin(String value) {
+  set margin(String? value) {
     _margin = value == null ? '' : value;
   }
 
@@ -4416,7 +4835,7 @@
   String get marginBottom => this._marginBottom;
 
   /** Sets the value of "margin-bottom" */
-  set marginBottom(String value) {
+  set marginBottom(String? value) {
     _marginBottom = value == null ? '' : value;
   }
 
@@ -4428,7 +4847,7 @@
   String get marginLeft => this._marginLeft;
 
   /** Sets the value of "margin-left" */
-  set marginLeft(String value) {
+  set marginLeft(String? value) {
     _marginLeft = value == null ? '' : value;
   }
 
@@ -4440,7 +4859,7 @@
   String get marginRight => this._marginRight;
 
   /** Sets the value of "margin-right" */
-  set marginRight(String value) {
+  set marginRight(String? value) {
     _marginRight = value == null ? '' : value;
   }
 
@@ -4452,7 +4871,7 @@
   String get marginTop => this._marginTop;
 
   /** Sets the value of "margin-top" */
-  set marginTop(String value) {
+  set marginTop(String? value) {
     _marginTop = value == null ? '' : value;
   }
 
@@ -4464,7 +4883,7 @@
   String get maxHeight => this._maxHeight;
 
   /** Sets the value of "max-height" */
-  set maxHeight(String value) {
+  set maxHeight(String? value) {
     _maxHeight = value == null ? '' : value;
   }
 
@@ -4476,7 +4895,7 @@
   String get maxWidth => this._maxWidth;
 
   /** Sets the value of "max-width" */
-  set maxWidth(String value) {
+  set maxWidth(String? value) {
     _maxWidth = value == null ? '' : value;
   }
 
@@ -4488,7 +4907,7 @@
   String get minHeight => this._minHeight;
 
   /** Sets the value of "min-height" */
-  set minHeight(String value) {
+  set minHeight(String? value) {
     _minHeight = value == null ? '' : value;
   }
 
@@ -4500,7 +4919,7 @@
   String get minWidth => this._minWidth;
 
   /** Sets the value of "min-width" */
-  set minWidth(String value) {
+  set minWidth(String? value) {
     _minWidth = value == null ? '' : value;
   }
 
@@ -4512,7 +4931,7 @@
   String get outline => this._outline;
 
   /** Sets the value of "outline" */
-  set outline(String value) {
+  set outline(String? value) {
     _outline = value == null ? '' : value;
   }
 
@@ -4524,7 +4943,7 @@
   String get outlineColor => this._outlineColor;
 
   /** Sets the value of "outline-color" */
-  set outlineColor(String value) {
+  set outlineColor(String? value) {
     _outlineColor = value == null ? '' : value;
   }
 
@@ -4536,7 +4955,7 @@
   String get outlineStyle => this._outlineStyle;
 
   /** Sets the value of "outline-style" */
-  set outlineStyle(String value) {
+  set outlineStyle(String? value) {
     _outlineStyle = value == null ? '' : value;
   }
 
@@ -4548,7 +4967,7 @@
   String get outlineWidth => this._outlineWidth;
 
   /** Sets the value of "outline-width" */
-  set outlineWidth(String value) {
+  set outlineWidth(String? value) {
     _outlineWidth = value == null ? '' : value;
   }
 
@@ -4560,7 +4979,7 @@
   String get overflow => this._overflow;
 
   /** Sets the value of "overflow" */
-  set overflow(String value) {
+  set overflow(String? value) {
     _overflow = value == null ? '' : value;
   }
 
@@ -4572,7 +4991,7 @@
   String get padding => this._padding;
 
   /** Sets the value of "padding" */
-  set padding(String value) {
+  set padding(String? value) {
     _padding = value == null ? '' : value;
   }
 
@@ -4584,7 +5003,7 @@
   String get paddingBottom => this._paddingBottom;
 
   /** Sets the value of "padding-bottom" */
-  set paddingBottom(String value) {
+  set paddingBottom(String? value) {
     _paddingBottom = value == null ? '' : value;
   }
 
@@ -4596,7 +5015,7 @@
   String get paddingLeft => this._paddingLeft;
 
   /** Sets the value of "padding-left" */
-  set paddingLeft(String value) {
+  set paddingLeft(String? value) {
     _paddingLeft = value == null ? '' : value;
   }
 
@@ -4608,7 +5027,7 @@
   String get paddingRight => this._paddingRight;
 
   /** Sets the value of "padding-right" */
-  set paddingRight(String value) {
+  set paddingRight(String? value) {
     _paddingRight = value == null ? '' : value;
   }
 
@@ -4620,7 +5039,7 @@
   String get paddingTop => this._paddingTop;
 
   /** Sets the value of "padding-top" */
-  set paddingTop(String value) {
+  set paddingTop(String? value) {
     _paddingTop = value == null ? '' : value;
   }
 
@@ -4632,7 +5051,7 @@
   String get pageBreakAfter => this._pageBreakAfter;
 
   /** Sets the value of "page-break-after" */
-  set pageBreakAfter(String value) {
+  set pageBreakAfter(String? value) {
     _pageBreakAfter = value == null ? '' : value;
   }
 
@@ -4644,7 +5063,7 @@
   String get pageBreakBefore => this._pageBreakBefore;
 
   /** Sets the value of "page-break-before" */
-  set pageBreakBefore(String value) {
+  set pageBreakBefore(String? value) {
     _pageBreakBefore = value == null ? '' : value;
   }
 
@@ -4656,7 +5075,7 @@
   String get pageBreakInside => this._pageBreakInside;
 
   /** Sets the value of "page-break-inside" */
-  set pageBreakInside(String value) {
+  set pageBreakInside(String? value) {
     _pageBreakInside = value == null ? '' : value;
   }
 
@@ -4668,7 +5087,7 @@
   String get position => this._position;
 
   /** Sets the value of "position" */
-  set position(String value) {
+  set position(String? value) {
     _position = value == null ? '' : value;
   }
 
@@ -4680,7 +5099,7 @@
   String get quotes => this._quotes;
 
   /** Sets the value of "quotes" */
-  set quotes(String value) {
+  set quotes(String? value) {
     _quotes = value == null ? '' : value;
   }
 
@@ -4692,7 +5111,7 @@
   String get right => this._right;
 
   /** Sets the value of "right" */
-  set right(String value) {
+  set right(String? value) {
     _right = value == null ? '' : value;
   }
 
@@ -4704,7 +5123,7 @@
   String get tableLayout => this._tableLayout;
 
   /** Sets the value of "table-layout" */
-  set tableLayout(String value) {
+  set tableLayout(String? value) {
     _tableLayout = value == null ? '' : value;
   }
 
@@ -4716,7 +5135,7 @@
   String get textAlign => this._textAlign;
 
   /** Sets the value of "text-align" */
-  set textAlign(String value) {
+  set textAlign(String? value) {
     _textAlign = value == null ? '' : value;
   }
 
@@ -4728,7 +5147,7 @@
   String get textDecoration => this._textDecoration;
 
   /** Sets the value of "text-decoration" */
-  set textDecoration(String value) {
+  set textDecoration(String? value) {
     _textDecoration = value == null ? '' : value;
   }
 
@@ -4740,7 +5159,7 @@
   String get textIndent => this._textIndent;
 
   /** Sets the value of "text-indent" */
-  set textIndent(String value) {
+  set textIndent(String? value) {
     _textIndent = value == null ? '' : value;
   }
 
@@ -4752,7 +5171,7 @@
   String get textTransform => this._textTransform;
 
   /** Sets the value of "text-transform" */
-  set textTransform(String value) {
+  set textTransform(String? value) {
     _textTransform = value == null ? '' : value;
   }
 
@@ -4764,7 +5183,7 @@
   String get top => this._top;
 
   /** Sets the value of "top" */
-  set top(String value) {
+  set top(String? value) {
     _top = value == null ? '' : value;
   }
 
@@ -4776,7 +5195,7 @@
   String get unicodeBidi => this._unicodeBidi;
 
   /** Sets the value of "unicode-bidi" */
-  set unicodeBidi(String value) {
+  set unicodeBidi(String? value) {
     _unicodeBidi = value == null ? '' : value;
   }
 
@@ -4788,7 +5207,7 @@
   String get verticalAlign => this._verticalAlign;
 
   /** Sets the value of "vertical-align" */
-  set verticalAlign(String value) {
+  set verticalAlign(String? value) {
     _verticalAlign = value == null ? '' : value;
   }
 
@@ -4800,7 +5219,7 @@
   String get visibility => this._visibility;
 
   /** Sets the value of "visibility" */
-  set visibility(String value) {
+  set visibility(String? value) {
     _visibility = value == null ? '' : value;
   }
 
@@ -4812,7 +5231,7 @@
   String get whiteSpace => this._whiteSpace;
 
   /** Sets the value of "white-space" */
-  set whiteSpace(String value) {
+  set whiteSpace(String? value) {
     _whiteSpace = value == null ? '' : value;
   }
 
@@ -4824,7 +5243,7 @@
   String get width => this._width;
 
   /** Sets the value of "width" */
-  set width(String value) {
+  set width(String? value) {
     _width = value == null ? '' : value;
   }
 
@@ -4836,7 +5255,7 @@
   String get wordSpacing => this._wordSpacing;
 
   /** Sets the value of "word-spacing" */
-  set wordSpacing(String value) {
+  set wordSpacing(String? value) {
     _wordSpacing = value == null ? '' : value;
   }
 
@@ -4848,7 +5267,7 @@
   String get zIndex => this._zIndex;
 
   /** Sets the value of "z-index" */
-  set zIndex(String value) {
+  set zIndex(String? value) {
     _zIndex = value == null ? '' : value;
   }
 
@@ -4875,7 +5294,7 @@
         .forEach((e) => e.setProperty(propertyName, value, priority));
   }
 
-  void _setAll(String propertyName, String value) {
+  void _setAll(String propertyName, String? value) {
     value = value == null ? '' : value;
     for (Element element in _elementIterable) {
       JS('void', '#.style[#] = #', element, propertyName, value);
@@ -8111,9 +8530,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String selectorText;
+  String get selectorText => JS("String", "#.selectorText", this);
 
-  final CssStyleDeclaration style;
+  set selectorText(String value) {
+    JS("void", "#.selectorText = #", this, value);
+  }
+
+  CssStyleDeclaration get style => JS("CssStyleDeclaration", "#.style", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8128,19 +8551,19 @@
 
   @Returns('_CssRuleList|Null')
   @Creates('_CssRuleList')
-  final List<CssRule> cssRules;
+  List<CssRule> get cssRules => JS("_CssRuleList", "#.cssRules", this);
 
-  final CssRule ownerRule;
+  final CssRule? ownerRule;
 
   @Returns('_CssRuleList|Null')
   @Creates('_CssRuleList')
-  final List<CssRule> rules;
+  List<CssRule> get rules => JS("_CssRuleList", "#.rules", this);
 
-  int addRule(String selector, String style, [int index]) native;
+  int addRule(String selector, String style, [int? index]) native;
 
   void deleteRule(int index) native;
 
-  int insertRule(String rule, [int index]) native;
+  int insertRule(String rule, [int? index]) native;
 
   void removeRule(int index) native;
 }
@@ -8179,7 +8602,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  bool is2D;
+  bool get is2D => JS("bool", "#.is2D", this);
+
+  set is2D(bool value) {
+    JS("void", "#.is2D = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8192,7 +8619,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory CssTransformValue([List<CssTransformComponent> transformComponents]) {
+  factory CssTransformValue(
+      [List<CssTransformComponent>? transformComponents]) {
     if (transformComponents == null) {
       return CssTransformValue._create_1();
     }
@@ -8206,9 +8634,9 @@
   static CssTransformValue _create_2(transformComponents) =>
       JS('CssTransformValue', 'new CSSTransformValue(#)', transformComponents);
 
-  final bool is2D;
+  bool get is2D => JS("bool", "#.is2D", this);
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
   CssTransformComponent componentAtIndex(int index) native;
 
@@ -8226,7 +8654,7 @@
   }
 
   factory CssTranslation(CssNumericValue x, CssNumericValue y,
-      [CssNumericValue z]) {
+      [CssNumericValue? z]) {
     if ((y is CssNumericValue) && (x is CssNumericValue) && z == null) {
       return CssTranslation._create_1(x, y);
     }
@@ -8242,11 +8670,23 @@
   static CssTranslation _create_2(x, y, z) =>
       JS('CssTranslation', 'new CSSTranslation(#,#,#)', x, y, z);
 
-  CssNumericValue x;
+  CssNumericValue get x => JS("CssNumericValue", "#.x", this);
 
-  CssNumericValue y;
+  set x(CssNumericValue value) {
+    JS("void", "#.x = #", this, value);
+  }
 
-  CssNumericValue z;
+  CssNumericValue get y => JS("CssNumericValue", "#.y", this);
+
+  set y(CssNumericValue value) {
+    JS("void", "#.y = #", this, value);
+  }
+
+  CssNumericValue get z => JS("CssNumericValue", "#.z", this);
+
+  set z(CssNumericValue value) {
+    JS("void", "#.z = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8265,11 +8705,19 @@
   static CssUnitValue _create_1(value, unit) =>
       JS('CssUnitValue', 'new CSSUnitValue(#,#)', value, unit);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
-  String unit;
+  String get unit => JS("String", "#.unit", this);
 
-  num value;
+  set unit(String value) {
+    JS("void", "#.unit = #", this, value);
+  }
+
+  num get value => JS("num", "#.value", this);
+
+  set value(num value) {
+    JS("void", "#.value = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8282,7 +8730,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
   Object fragmentAtIndex(int index) native;
 }
@@ -8297,9 +8745,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final CssUnparsedValue fallback;
+  CssUnparsedValue get fallback => JS("CssUnparsedValue", "#.fallback", this);
 
-  final String variable;
+  String get variable => JS("String", "#.variable", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8312,7 +8760,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final CssStyleDeclaration style;
+  CssStyleDeclaration get style => JS("CssStyleDeclaration", "#.style", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8331,7 +8779,7 @@
   static CssurlImageValue _create_1(url) =>
       JS('CssurlImageValue', 'new CSSURLImageValue(#)', url);
 
-  final String url;
+  String get url => JS("String", "#.url", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8353,7 +8801,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  void define(String name, Object constructor, [Map options]) {
+  void define(String name, Object constructor, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       _define_1(name, constructor, options_1);
@@ -8413,7 +8861,7 @@
     return _detail;
   }
 
-  factory CustomEvent._(String type, [Map eventInitDict]) {
+  factory CustomEvent._(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return CustomEvent._create_1(type, eventInitDict_1);
@@ -8433,7 +8881,7 @@
 
   @JSName('initCustomEvent')
   void _initCustomEvent(String type,
-      [bool bubbles, bool cancelable, Object detail]) native;
+      [bool? bubbles, bool? cancelable, Object? detail]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8446,7 +8894,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DListElement() => JS(
+  factory DListElement() => JS<DListElement>(
       'returns:DListElement;creates:DListElement;new:true',
       '#.createElement(#)',
       document,
@@ -8475,7 +8923,11 @@
    */
   DataElement.created() : super.created();
 
-  String value;
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8492,7 +8944,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DataListElement() => document.createElement("datalist");
+  factory DataListElement() =>
+      document.createElement("datalist") as DataListElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -8505,7 +8958,7 @@
 
   @Returns('HtmlCollection|Null')
   @Creates('HtmlCollection')
-  final List<Node> options;
+  List<Node> get options => JS("HtmlCollection", "#.options", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8523,19 +8976,27 @@
   }
   static DataTransfer _create_1() => JS('DataTransfer', 'new DataTransfer()');
 
-  String dropEffect;
+  String get dropEffect => JS("String", "#.dropEffect", this);
 
-  String effectAllowed;
+  set dropEffect(String value) {
+    JS("void", "#.dropEffect = #", this, value);
+  }
+
+  String get effectAllowed => JS("String", "#.effectAllowed", this);
+
+  set effectAllowed(String value) {
+    JS("void", "#.effectAllowed = #", this, value);
+  }
 
   @Returns('FileList|Null')
   @Creates('FileList')
-  final List<File> files;
+  List<File> get files => JS("FileList", "#.files", this);
 
-  final DataTransferItemList items;
+  DataTransferItemList get items => JS("DataTransferItemList", "#.items", this);
 
-  final List<String> types;
+  List<String> get types => JS("List<String>", "#.types", this);
 
-  void clearData([String format]) native;
+  void clearData([String? format]) native;
 
   String getData(String format) native;
 
@@ -8567,9 +9028,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String kind;
+  String get kind => JS("String", "#.kind", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
   File getAsFile() native;
 
@@ -8589,9 +9050,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
-  DataTransferItem add(data_OR_file, [String type]) native;
+  DataTransferItem add(data_OR_file, [String? type]) native;
 
   @JSName('add')
   DataTransferItem addData(String data, String type) native;
@@ -8656,7 +9117,7 @@
 
   void close() native;
 
-  void postMessage(/*any*/ message, [List<Object> transfer]) {
+  void postMessage(/*any*/ message, [List<Object>? transfer]) {
     if (transfer != null) {
       var message_1 = convertDartToNative_SerializedScriptValue(message);
       _postMessage_1(message_1, transfer);
@@ -8676,8 +9137,8 @@
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
   void _webkitRequestFileSystem(int type, int size,
-      [_FileSystemCallback successCallback,
-      _ErrorCallback errorCallback]) native;
+      [_FileSystemCallback? successCallback,
+      _ErrorCallback? errorCallback]) native;
 
   @JSName('webkitRequestFileSystemSync')
   @SupportedBrowser(SupportedBrowser.CHROME)
@@ -8694,7 +9155,7 @@
   @SupportedBrowser(SupportedBrowser.SAFARI)
   void _webkitResolveLocalFileSystemUrl(
       String url, _EntryCallback successCallback,
-      [_ErrorCallback errorCallback]) native;
+      [_ErrorCallback? errorCallback]) native;
 
   /// Stream of `message` events handled by this [DedicatedWorkerGlobalScope].
   Stream<MessageEvent> get onMessage => messageEvent.forTarget(this);
@@ -8720,12 +9181,12 @@
   static const int TEMPORARY = 0;
 
   void queryUsageAndQuota(int storageType,
-      [StorageUsageCallback usageCallback,
-      StorageErrorCallback errorCallback]) native;
+      [StorageUsageCallback? usageCallback,
+      StorageErrorCallback? errorCallback]) native;
 
   void requestQuota(int storageType, int newQuotaInBytes,
-      [StorageQuotaCallback quotaCallback,
-      StorageErrorCallback errorCallback]) native;
+      [StorageQuotaCallback? quotaCallback,
+      StorageErrorCallback? errorCallback]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8739,11 +9200,11 @@
   }
 
   void queryUsageAndQuota(StorageUsageCallback usageCallback,
-      [StorageErrorCallback errorCallback]) native;
+      [StorageErrorCallback? errorCallback]) native;
 
   void requestQuota(int newQuotaInBytes,
-      [StorageQuotaCallback quotaCallback,
-      StorageErrorCallback errorCallback]) native;
+      [StorageQuotaCallback? quotaCallback,
+      StorageErrorCallback? errorCallback]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8756,11 +9217,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int lineNumber;
+  int get lineNumber => JS("int", "#.lineNumber", this);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 
-  final String sourceFile;
+  String get sourceFile => JS("String", "#.sourceFile", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8775,7 +9236,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DetailsElement() => document.createElement("details");
+  factory DetailsElement() =>
+      document.createElement("details") as DetailsElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -8786,7 +9248,11 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('details');
 
-  bool open;
+  bool get open => JS("bool", "#.open", this);
+
+  set open(bool value) {
+    JS("void", "#.open = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8805,11 +9271,11 @@
   static DetectedBarcode _create_1() =>
       JS('DetectedBarcode', 'new DetectedBarcode()');
 
-  final Rectangle boundingBox;
+  Rectangle get boundingBox => JS("Rectangle", "#.boundingBox", this);
 
-  final List cornerPoints;
+  List get cornerPoints => JS("List", "#.cornerPoints", this);
 
-  final String rawValue;
+  String get rawValue => JS("String", "#.rawValue", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8827,9 +9293,9 @@
   }
   static DetectedFace _create_1() => JS('DetectedFace', 'new DetectedFace()');
 
-  final Rectangle boundingBox;
+  Rectangle get boundingBox => JS("Rectangle", "#.boundingBox", this);
 
-  final List landmarks;
+  List get landmarks => JS("List", "#.landmarks", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8847,11 +9313,11 @@
   }
   static DetectedText _create_1() => JS('DetectedText', 'new DetectedText()');
 
-  final Rectangle boundingBox;
+  Rectangle get boundingBox => JS("Rectangle", "#.boundingBox", this);
 
-  final List cornerPoints;
+  List get cornerPoints => JS("List", "#.cornerPoints", this);
 
-  final String rawValue;
+  String get rawValue => JS("String", "#.rawValue", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8881,7 +9347,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DeviceMotionEvent(String type, [Map eventInitDict]) {
+  factory DeviceMotionEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return DeviceMotionEvent._create_1(type, eventInitDict_1);
@@ -8893,13 +9359,13 @@
   static DeviceMotionEvent _create_2(type) =>
       JS('DeviceMotionEvent', 'new DeviceMotionEvent(#)', type);
 
-  final DeviceAcceleration acceleration;
+  final DeviceAcceleration? acceleration;
 
-  final DeviceAcceleration accelerationIncludingGravity;
+  final DeviceAcceleration? accelerationIncludingGravity;
 
-  final num interval;
+  num get interval => JS("num", "#.interval", this);
 
-  final DeviceRotationRate rotationRate;
+  final DeviceRotationRate? rotationRate;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -8912,7 +9378,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DeviceOrientationEvent(String type, [Map eventInitDict]) {
+  factory DeviceOrientationEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return DeviceOrientationEvent._create_1(type, eventInitDict_1);
@@ -8927,7 +9393,7 @@
   static DeviceOrientationEvent _create_2(type) =>
       JS('DeviceOrientationEvent', 'new DeviceOrientationEvent(#)', type);
 
-  final bool absolute;
+  bool get absolute => JS("bool", "#.absolute", this);
 
   final num alpha;
 
@@ -8970,11 +9436,19 @@
    */
   DialogElement.created() : super.created();
 
-  bool open;
+  bool get open => JS("bool", "#.open", this);
 
-  String returnValue;
+  set open(bool value) {
+    JS("void", "#.open = #", this, value);
+  }
 
-  void close([String returnValue]) native;
+  String get returnValue => JS("String", "#.returnValue", this);
+
+  set returnValue(String value) {
+    JS("void", "#.returnValue = #", this, value);
+  }
+
+  void close([String? returnValue]) native;
 
   void show() native;
 
@@ -9037,10 +9511,10 @@
   @JSName('createReader')
   DirectoryReader _createReader() native;
 
-  void __getDirectory(String path,
-      [Map options,
-      _EntryCallback successCallback,
-      _ErrorCallback errorCallback]) {
+  void __getDirectory(String? path,
+      [Map? options,
+      _EntryCallback? successCallback,
+      _ErrorCallback? errorCallback]) {
     if (errorCallback != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       __getDirectory_1(path, options_1, successCallback, errorCallback);
@@ -9071,7 +9545,7 @@
   void __getDirectory_4(path) native;
 
   @JSName('getDirectory')
-  Future<Entry> _getDirectory(String path, {Map options}) {
+  Future<Entry> _getDirectory(String? path, {Map? options}) {
     var completer = new Completer<Entry>();
     __getDirectory(path, options, (value) {
       completer.complete(value);
@@ -9081,10 +9555,10 @@
     return completer.future;
   }
 
-  void __getFile(String path,
-      [Map options,
-      _EntryCallback successCallback,
-      _ErrorCallback errorCallback]) {
+  void __getFile(String? path,
+      [Map? options,
+      _EntryCallback? successCallback,
+      _ErrorCallback? errorCallback]) {
     if (errorCallback != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       __getFile_1(path, options_1, successCallback, errorCallback);
@@ -9115,7 +9589,7 @@
   void __getFile_4(path) native;
 
   @JSName('getFile')
-  Future<Entry> _getFile(String path, {Map options}) {
+  Future<Entry> _getFile(String? path, {Map? options}) {
     var completer = new Completer<Entry>();
     __getFile(path, options, (value) {
       applyExtension('FileEntry', value);
@@ -9128,7 +9602,7 @@
 
   @JSName('removeRecursively')
   void _removeRecursively(VoidCallback successCallback,
-      [_ErrorCallback errorCallback]) native;
+      [_ErrorCallback? errorCallback]) native;
 
   @JSName('removeRecursively')
   Future removeRecursively() {
@@ -9154,7 +9628,7 @@
 
   @JSName('readEntries')
   void _readEntries(_EntriesCallback successCallback,
-      [_ErrorCallback errorCallback]) native;
+      [_ErrorCallback? errorCallback]) native;
 
   Future<List<Entry>> readEntries() {
     var completer = new Completer<List<Entry>>();
@@ -9207,8 +9681,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DivElement() => JS('returns:DivElement;creates:DivElement;new:true',
-      '#.createElement(#)', document, "div");
+  factory DivElement() => JS<DivElement>(
+      'returns:DivElement;creates:DivElement;new:true',
+      '#.createElement(#)',
+      document,
+      "div");
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -9276,18 +9753,22 @@
   }
   static Document _create_1() => JS('Document', 'new Document()');
 
-  final String addressSpace;
+  String get addressSpace => JS("String", "#.addressSpace", this);
 
   @JSName('body')
-  HtmlElement _body;
+  HtmlElement? _body;
 
-  final String contentType;
+  String get contentType => JS("String", "#.contentType", this);
 
-  String cookie;
+  String get cookie => JS("String", "#.cookie", this);
 
-  final ScriptElement currentScript;
+  set cookie(String value) {
+    JS("void", "#.cookie = #", this, value);
+  }
 
-  WindowBase get window => _convertNativeToDart_Window(this._get_window);
+  final ScriptElement? currentScript;
+
+  WindowBase? get window => _convertNativeToDart_Window(this._get_window);
   @JSName('defaultView')
   @Creates('Window|=Object')
   @Returns('Window|=Object')
@@ -9295,70 +9776,79 @@
   @Returns('Window|=Object|Null')
   final dynamic _get_window;
 
-  final Element documentElement;
+  final Element? documentElement;
 
-  final String domain;
+  String get domain => JS("String", "#.domain", this);
 
-  final bool fullscreenEnabled;
+  bool get fullscreenEnabled => JS("bool", "#.fullscreenEnabled", this);
 
   @JSName('head')
-  final HeadElement _head;
+  final HeadElement? _head;
 
-  final bool hidden;
+  bool get hidden => JS("bool", "#.hidden", this);
 
-  final DomImplementation implementation;
+  DomImplementation get implementation =>
+      JS("DomImplementation", "#.implementation", this);
 
   @JSName('lastModified')
-  final String _lastModified;
+  String get _lastModified => JS("String", "#.lastModified", this);
 
-  final String origin;
+  String get origin => JS("String", "#.origin", this);
 
   @JSName('preferredStylesheetSet')
-  final String _preferredStylesheetSet;
+  final String? _preferredStylesheetSet;
 
-  final String readyState;
+  String get readyState => JS("String", "#.readyState", this);
 
   @JSName('referrer')
-  final String _referrer;
+  String get _referrer => JS("String", "#.referrer", this);
 
-  final SvgSvgElement rootElement;
+  SvgSvgElement get rootElement => JS("SvgSvgElement", "#.rootElement", this);
 
-  Element rootScroller;
+  Element? rootScroller;
 
-  final Element scrollingElement;
+  final Element? scrollingElement;
 
   @JSName('selectedStylesheetSet')
-  String _selectedStylesheetSet;
+  String? _selectedStylesheetSet;
 
-  final String suborigin;
+  String get suborigin => JS("String", "#.suborigin", this);
 
-  final DocumentTimeline timeline;
+  DocumentTimeline get timeline => JS("DocumentTimeline", "#.timeline", this);
 
   @JSName('title')
-  String _title;
+  String get _title => JS("String", "#.title", this);
+
+  @JSName('title')
+  set _title(String value) {
+    JS("void", "#.title = #", this, value);
+  }
 
   @JSName('visibilityState')
-  final String _visibilityState;
+  String get _visibilityState => JS("String", "#.visibilityState", this);
 
   @JSName('webkitFullscreenElement')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final Element _webkitFullscreenElement;
+  Element get _webkitFullscreenElement =>
+      JS("Element", "#.webkitFullscreenElement", this);
 
   @JSName('webkitFullscreenEnabled')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final bool _webkitFullscreenEnabled;
+  bool get _webkitFullscreenEnabled =>
+      JS("bool", "#.webkitFullscreenEnabled", this);
 
   @JSName('webkitHidden')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final bool _webkitHidden;
+  bool get _webkitHidden => JS("bool", "#.webkitHidden", this);
 
   @JSName('webkitVisibilityState')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final String _webkitVisibilityState;
+  String get _webkitVisibilityState =>
+      JS("String", "#.webkitVisibilityState", this);
 
   Node adoptNode(Node node) native;
 
@@ -9372,7 +9862,7 @@
       [options_OR_typeExtension]) native;
 
   @JSName('createElementNS')
-  Element _createElementNS(String namespaceURI, String qualifiedName,
+  Element _createElementNS(String? namespaceURI, String qualifiedName,
       [options_OR_typeExtension]) native;
 
   @JSName('createEvent')
@@ -9385,7 +9875,7 @@
 
   Touch _createTouch(Window view, EventTarget target, int identifier, num pageX,
       num pageY, num screenX, num screenY,
-      [num radiusX, num radiusY, num rotationAngle, num force]) {
+      [num? radiusX, num? radiusY, num? rotationAngle, num? force]) {
     if (force != null) {
       var target_1 = _convertDartToNative_EventTarget(target);
       return _createTouch_1(view, target_1, identifier, pageX, pageY, screenX,
@@ -9430,7 +9920,7 @@
   @JSName('createTouchList')
   TouchList _createTouchList(Touch touches) native;
 
-  bool execCommand(String commandId, [bool showUI, String value]) native;
+  bool execCommand(String commandId, [bool? showUI, String? value]) native;
 
   void exitFullscreen() native;
 
@@ -9450,7 +9940,7 @@
   @Returns('NodeList|HtmlCollection')
   List<Node> getElementsByTagName(String localName) native;
 
-  Node importNode(Node node, [bool deep]) native;
+  Node importNode(Node node, [bool? deep]) native;
 
   bool queryCommandEnabled(String commandId) native;
 
@@ -9462,7 +9952,7 @@
 
   String queryCommandValue(String commandId) native;
 
-  Function registerElement2(String type, [Map options]) {
+  Function registerElement2(String type, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return _registerElement2_1(type, options_1);
@@ -9486,16 +9976,17 @@
 
   // From DocumentOrShadowRoot
 
-  final Element activeElement;
+  final Element? activeElement;
 
-  final Element fullscreenElement;
+  final Element? fullscreenElement;
 
-  final Element pointerLockElement;
+  final Element? pointerLockElement;
 
   @JSName('styleSheets')
   @Returns('_StyleSheetList|Null')
   @Creates('_StyleSheetList')
-  final List<StyleSheet> _styleSheets;
+  List<StyleSheet> get _styleSheets =>
+      JS("_StyleSheetList", "#.styleSheets", this);
 
   @JSName('elementFromPoint')
   Element _elementFromPoint(int x, int y) native;
@@ -9504,23 +9995,23 @@
 
   // From FontFaceSource
 
-  final FontFaceSet fonts;
+  FontFaceSet get fonts => JS("FontFaceSet", "#.fonts", this);
 
   // From ParentNode
 
   @JSName('childElementCount')
-  final int _childElementCount;
+  int get _childElementCount => JS("int", "#.childElementCount", this);
 
   @JSName('children')
   @Returns('HtmlCollection|Null')
   @Creates('HtmlCollection')
-  final List<Node> _children;
+  List<Node> get _children => JS("HtmlCollection", "#.children", this);
 
   @JSName('firstElementChild')
-  final Element _firstElementChild;
+  final Element? _firstElementChild;
 
   @JSName('lastElementChild')
-  final Element _lastElementChild;
+  final Element? _lastElementChild;
 
   /**
    * Finds the first descendant element of this document that matches the
@@ -9937,13 +10428,13 @@
   // From ParentNode
 
   @JSName('childElementCount')
-  final int _childElementCount;
+  int get _childElementCount => JS("int", "#.childElementCount", this);
 
   @JSName('firstElementChild')
-  final Element _firstElementChild;
+  final Element? _firstElementChild;
 
   @JSName('lastElementChild')
-  final Element _lastElementChild;
+  final Element? _lastElementChild;
 
   /**
    * Finds the first descendant element of this document fragment that matches
@@ -9975,15 +10466,16 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Element activeElement;
+  final Element? activeElement;
 
-  final Element fullscreenElement;
+  final Element? fullscreenElement;
 
-  final Element pointerLockElement;
+  final Element? pointerLockElement;
 
   @Returns('_StyleSheetList|Null')
   @Creates('_StyleSheetList')
-  final List<StyleSheet> styleSheets;
+  List<StyleSheet> get styleSheets =>
+      JS("_StyleSheetList", "#.styleSheets", this);
 
   Element elementFromPoint(int x, int y) native;
 
@@ -10002,7 +10494,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DocumentTimeline([Map options]) {
+  factory DocumentTimeline([Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return DocumentTimeline._create_1(options_1);
@@ -10025,7 +10517,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DomError(String name, [String message]) {
+  factory DomError(String name, [String? message]) {
     if (message != null) {
       return DomError._create_1(name, message);
     }
@@ -10035,9 +10527,9 @@
       JS('DomError', 'new DOMError(#,#)', name, message);
   static DomError _create_2(name) => JS('DomError', 'new DOMError(#)', name);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -10095,7 +10587,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 
   String toString() => JS('String', 'String(#)', this);
 }
@@ -10110,14 +10602,14 @@
     throw new UnsupportedError("Not supported");
   }
 
-  XmlDocument createDocument(
-      String namespaceURI, String qualifiedName, _DocumentType doctype) native;
+  XmlDocument createDocument(String? namespaceURI, String qualifiedName,
+      _DocumentType? doctype) native;
 
   _DocumentType createDocumentType(
       String qualifiedName, String publicId, String systemId) native;
 
   @JSName('createHTMLDocument')
-  HtmlDocument createHtmlDocument([String title]) native;
+  HtmlDocument createHtmlDocument([String? title]) native;
 
   bool hasFeature() native;
 }
@@ -10132,7 +10624,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  Object next([Object value]) native;
+  Object next([Object? value]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -10145,7 +10637,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DomMatrix([Object init]) {
+  factory DomMatrix([Object? init]) {
     if (init != null) {
       return DomMatrix._create_1(init);
     }
@@ -10155,6 +10647,7 @@
   static DomMatrix _create_2() => JS('DomMatrix', 'new DOMMatrix()');
 
   // Shadowing definition.
+
   num get a => JS("num", "#.a", this);
 
   set a(num value) {
@@ -10162,6 +10655,7 @@
   }
 
   // Shadowing definition.
+
   num get b => JS("num", "#.b", this);
 
   set b(num value) {
@@ -10169,6 +10663,7 @@
   }
 
   // Shadowing definition.
+
   num get c => JS("num", "#.c", this);
 
   set c(num value) {
@@ -10176,6 +10671,7 @@
   }
 
   // Shadowing definition.
+
   num get d => JS("num", "#.d", this);
 
   set d(num value) {
@@ -10183,6 +10679,7 @@
   }
 
   // Shadowing definition.
+
   num get e => JS("num", "#.e", this);
 
   set e(num value) {
@@ -10190,6 +10687,7 @@
   }
 
   // Shadowing definition.
+
   num get f => JS("num", "#.f", this);
 
   set f(num value) {
@@ -10197,6 +10695,7 @@
   }
 
   // Shadowing definition.
+
   num get m11 => JS("num", "#.m11", this);
 
   set m11(num value) {
@@ -10204,6 +10703,7 @@
   }
 
   // Shadowing definition.
+
   num get m12 => JS("num", "#.m12", this);
 
   set m12(num value) {
@@ -10211,6 +10711,7 @@
   }
 
   // Shadowing definition.
+
   num get m13 => JS("num", "#.m13", this);
 
   set m13(num value) {
@@ -10218,6 +10719,7 @@
   }
 
   // Shadowing definition.
+
   num get m14 => JS("num", "#.m14", this);
 
   set m14(num value) {
@@ -10225,6 +10727,7 @@
   }
 
   // Shadowing definition.
+
   num get m21 => JS("num", "#.m21", this);
 
   set m21(num value) {
@@ -10232,6 +10735,7 @@
   }
 
   // Shadowing definition.
+
   num get m22 => JS("num", "#.m22", this);
 
   set m22(num value) {
@@ -10239,6 +10743,7 @@
   }
 
   // Shadowing definition.
+
   num get m23 => JS("num", "#.m23", this);
 
   set m23(num value) {
@@ -10246,6 +10751,7 @@
   }
 
   // Shadowing definition.
+
   num get m24 => JS("num", "#.m24", this);
 
   set m24(num value) {
@@ -10253,6 +10759,7 @@
   }
 
   // Shadowing definition.
+
   num get m31 => JS("num", "#.m31", this);
 
   set m31(num value) {
@@ -10260,6 +10767,7 @@
   }
 
   // Shadowing definition.
+
   num get m32 => JS("num", "#.m32", this);
 
   set m32(num value) {
@@ -10267,6 +10775,7 @@
   }
 
   // Shadowing definition.
+
   num get m33 => JS("num", "#.m33", this);
 
   set m33(num value) {
@@ -10274,6 +10783,7 @@
   }
 
   // Shadowing definition.
+
   num get m34 => JS("num", "#.m34", this);
 
   set m34(num value) {
@@ -10281,6 +10791,7 @@
   }
 
   // Shadowing definition.
+
   num get m41 => JS("num", "#.m41", this);
 
   set m41(num value) {
@@ -10288,6 +10799,7 @@
   }
 
   // Shadowing definition.
+
   num get m42 => JS("num", "#.m42", this);
 
   set m42(num value) {
@@ -10295,6 +10807,7 @@
   }
 
   // Shadowing definition.
+
   num get m43 => JS("num", "#.m43", this);
 
   set m43(num value) {
@@ -10302,6 +10815,7 @@
   }
 
   // Shadowing definition.
+
   num get m44 => JS("num", "#.m44", this);
 
   set m44(num value) {
@@ -10312,7 +10826,7 @@
 
   static DomMatrix fromFloat64Array(Float64List array64) native;
 
-  static DomMatrix fromMatrix([Map other]) {
+  static DomMatrix fromMatrix([Map? other]) {
     if (other != null) {
       var other_1 = convertDartToNative_Dictionary(other);
       return _fromMatrix_1(other_1);
@@ -10327,7 +10841,7 @@
 
   DomMatrix invertSelf() native;
 
-  DomMatrix multiplySelf([Map other]) {
+  DomMatrix multiplySelf([Map? other]) {
     if (other != null) {
       var other_1 = convertDartToNative_Dictionary(other);
       return _multiplySelf_1(other_1);
@@ -10340,7 +10854,7 @@
   @JSName('multiplySelf')
   DomMatrix _multiplySelf_2() native;
 
-  DomMatrix preMultiplySelf([Map other]) {
+  DomMatrix preMultiplySelf([Map? other]) {
     if (other != null) {
       var other_1 = convertDartToNative_Dictionary(other);
       return _preMultiplySelf_1(other_1);
@@ -10353,30 +10867,30 @@
   @JSName('preMultiplySelf')
   DomMatrix _preMultiplySelf_2() native;
 
-  DomMatrix rotateAxisAngleSelf([num x, num y, num z, num angle]) native;
+  DomMatrix rotateAxisAngleSelf([num? x, num? y, num? z, num? angle]) native;
 
-  DomMatrix rotateFromVectorSelf([num x, num y]) native;
+  DomMatrix rotateFromVectorSelf([num? x, num? y]) native;
 
-  DomMatrix rotateSelf([num rotX, num rotY, num rotZ]) native;
+  DomMatrix rotateSelf([num? rotX, num? rotY, num? rotZ]) native;
 
-  DomMatrix scale3dSelf([num scale, num originX, num originY, num originZ])
+  DomMatrix scale3dSelf([num? scale, num? originX, num? originY, num? originZ])
       native;
 
   DomMatrix scaleSelf(
-      [num scaleX,
-      num scaleY,
-      num scaleZ,
-      num originX,
-      num originY,
-      num originZ]) native;
+      [num? scaleX,
+      num? scaleY,
+      num? scaleZ,
+      num? originX,
+      num? originY,
+      num? originZ]) native;
 
   DomMatrix setMatrixValue(String transformList) native;
 
-  DomMatrix skewXSelf([num sx]) native;
+  DomMatrix skewXSelf([num? sx]) native;
 
-  DomMatrix skewYSelf([num sy]) native;
+  DomMatrix skewYSelf([num? sy]) native;
 
-  DomMatrix translateSelf([num tx, num ty, num tz]) native;
+  DomMatrix translateSelf([num? tx, num? ty, num? tz]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -10389,7 +10903,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DomMatrixReadOnly([Object init]) {
+  factory DomMatrixReadOnly([Object? init]) {
     if (init != null) {
       return DomMatrixReadOnly._create_1(init);
     }
@@ -10456,7 +10970,7 @@
 
   static DomMatrixReadOnly fromFloat64Array(Float64List array64) native;
 
-  static DomMatrixReadOnly fromMatrix([Map other]) {
+  static DomMatrixReadOnly fromMatrix([Map? other]) {
     if (other != null) {
       var other_1 = convertDartToNative_Dictionary(other);
       return _fromMatrix_1(other_1);
@@ -10471,7 +10985,7 @@
 
   DomMatrix inverse() native;
 
-  DomMatrix multiply([Map other]) {
+  DomMatrix multiply([Map? other]) {
     if (other != null) {
       var other_1 = convertDartToNative_Dictionary(other);
       return _multiply_1(other_1);
@@ -10484,31 +10998,32 @@
   @JSName('multiply')
   DomMatrix _multiply_2() native;
 
-  DomMatrix rotate([num rotX, num rotY, num rotZ]) native;
+  DomMatrix rotate([num? rotX, num? rotY, num? rotZ]) native;
 
-  DomMatrix rotateAxisAngle([num x, num y, num z, num angle]) native;
+  DomMatrix rotateAxisAngle([num? x, num? y, num? z, num? angle]) native;
 
-  DomMatrix rotateFromVector([num x, num y]) native;
+  DomMatrix rotateFromVector([num? x, num? y]) native;
 
   DomMatrix scale(
-      [num scaleX,
-      num scaleY,
-      num scaleZ,
-      num originX,
-      num originY,
-      num originZ]) native;
+      [num? scaleX,
+      num? scaleY,
+      num? scaleZ,
+      num? originX,
+      num? originY,
+      num? originZ]) native;
 
-  DomMatrix scale3d([num scale, num originX, num originY, num originZ]) native;
+  DomMatrix scale3d([num? scale, num? originX, num? originY, num? originZ])
+      native;
 
-  DomMatrix skewX([num sx]) native;
+  DomMatrix skewX([num? sx]) native;
 
-  DomMatrix skewY([num sy]) native;
+  DomMatrix skewY([num? sy]) native;
 
   Float32List toFloat32Array() native;
 
   Float64List toFloat64Array() native;
 
-  DomPoint transformPoint([Map point]) {
+  DomPoint transformPoint([Map? point]) {
     if (point != null) {
       var point_1 = convertDartToNative_Dictionary(point);
       return _transformPoint_1(point_1);
@@ -10521,7 +11036,7 @@
   @JSName('transformPoint')
   DomPoint _transformPoint_2() native;
 
-  DomMatrix translate([num tx, num ty, num tz]) native;
+  DomMatrix translate([num? tx, num? ty, num? tz]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -10552,7 +11067,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DomPoint([num x, num y, num z, num w]) {
+  factory DomPoint([num? x, num? y, num? z, num? w]) {
     if (w != null) {
       return DomPoint._create_1(x, y, z, w);
     }
@@ -10580,6 +11095,7 @@
       JS('bool', '!!(window.DOMPoint) || !!(window.WebKitPoint)');
 
   // Shadowing definition.
+
   num get w => JS("num", "#.w", this);
 
   set w(num value) {
@@ -10587,6 +11103,7 @@
   }
 
   // Shadowing definition.
+
   num get x => JS("num", "#.x", this);
 
   set x(num value) {
@@ -10594,6 +11111,7 @@
   }
 
   // Shadowing definition.
+
   num get y => JS("num", "#.y", this);
 
   set y(num value) {
@@ -10601,13 +11119,14 @@
   }
 
   // Shadowing definition.
+
   num get z => JS("num", "#.z", this);
 
   set z(num value) {
     JS("void", "#.z = #", this, value);
   }
 
-  static DomPoint fromPoint([Map other]) {
+  static DomPoint fromPoint([Map? other]) {
     if (other != null) {
       var other_1 = convertDartToNative_Dictionary(other);
       return _fromPoint_1(other_1);
@@ -10631,7 +11150,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DomPointReadOnly([num x, num y, num z, num w]) {
+  factory DomPointReadOnly([num? x, num? y, num? z, num? w]) {
     if (w != null) {
       return DomPointReadOnly._create_1(x, y, z, w);
     }
@@ -10665,7 +11184,7 @@
 
   num get z => JS("num", "#.z", this);
 
-  static DomPointReadOnly fromPoint([Map other]) {
+  static DomPointReadOnly fromPoint([Map? other]) {
     if (other != null) {
       var other_1 = convertDartToNative_Dictionary(other);
       return _fromPoint_1(other_1);
@@ -10678,7 +11197,7 @@
   @JSName('fromPoint')
   static DomPointReadOnly _fromPoint_2() native;
 
-  DomPoint matrixTransform([Map matrix]) {
+  DomPoint matrixTransform([Map? matrix]) {
     if (matrix != null) {
       var matrix_1 = convertDartToNative_Dictionary(matrix);
       return _matrixTransform_1(matrix_1);
@@ -10702,7 +11221,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DomQuad([Map p1, Map p2, Map p3, Map p4]) {
+  factory DomQuad([Map? p1, Map? p2, Map? p3, Map? p4]) {
     if (p4 != null) {
       var p1_1 = convertDartToNative_Dictionary(p1);
       var p2_2 = convertDartToNative_Dictionary(p2);
@@ -10735,15 +11254,15 @@
   static DomQuad _create_4(p1) => JS('DomQuad', 'new DOMQuad(#)', p1);
   static DomQuad _create_5() => JS('DomQuad', 'new DOMQuad()');
 
-  final DomPoint p1;
+  DomPoint get p1 => JS("DomPoint", "#.p1", this);
 
-  final DomPoint p2;
+  DomPoint get p2 => JS("DomPoint", "#.p2", this);
 
-  final DomPoint p3;
+  DomPoint get p3 => JS("DomPoint", "#.p3", this);
 
-  final DomPoint p4;
+  DomPoint get p4 => JS("DomPoint", "#.p4", this);
 
-  static DomQuad fromQuad([Map other]) {
+  static DomQuad fromQuad([Map? other]) {
     if (other != null) {
       var other_1 = convertDartToNative_Dictionary(other);
       return _fromQuad_1(other_1);
@@ -10756,7 +11275,7 @@
   @JSName('fromQuad')
   static DomQuad _fromQuad_2() native;
 
-  static DomQuad fromRect([Map other]) {
+  static DomQuad fromRect([Map? other]) {
     if (other != null) {
       var other_1 = convertDartToNative_Dictionary(other);
       return _fromRect_1(other_1);
@@ -10930,7 +11449,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DomRectReadOnly([num x, num y, num width, num height]) {
+  factory DomRectReadOnly([num? x, num? y, num? width, num? height]) {
     if (height != null) {
       return DomRectReadOnly._create_1(x, y, width, height);
     }
@@ -10972,7 +11491,7 @@
 
   num get y => JS("num", "#.y", this);
 
-  static DomRectReadOnly fromRect([Map other]) {
+  static DomRectReadOnly fromRect([Map? other]) {
     if (other != null) {
       var other_1 = convertDartToNative_Dictionary(other);
       return _fromRect_1(other_1);
@@ -11074,9 +11593,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
-  String value;
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
 
   void add(String tokens) native;
 
@@ -11090,7 +11613,7 @@
 
   bool supports(String token) native;
 
-  bool toggle(String token, [bool force]) native;
+  bool toggle(String token, [bool? force]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -11106,7 +11629,7 @@
       : _childElements = element._children,
         _element = element;
 
-  bool contains(Object element) => _childElements.contains(element);
+  bool contains(Object? element) => _childElements.contains(element);
 
   bool get isEmpty {
     return _element._firstElementChild == null;
@@ -11146,11 +11669,11 @@
     }
   }
 
-  void sort([int compare(Element a, Element b)]) {
+  void sort([int compare(Element a, Element b)?]) {
     throw new UnsupportedError('Cannot sort element lists');
   }
 
-  void shuffle([Random random]) {
+  void shuffle([Random? random]) {
     throw new UnsupportedError('Cannot shuffle element lists');
   }
 
@@ -11172,7 +11695,7 @@
     for (var e in removed) e.remove();
   }
 
-  void fillRange(int start, int end, [Element fillValue]) {
+  void fillRange(int start, int end, [Element? fillValue]) {
     throw new UnimplementedError();
   }
 
@@ -11189,7 +11712,7 @@
     throw new UnimplementedError();
   }
 
-  bool remove(Object object) {
+  bool remove(Object? object) {
     if (object is Element) {
       Element element = object;
       if (identical(element.parentNode, _element)) {
@@ -11658,11 +12181,11 @@
     throw new UnsupportedError('Cannot modify list');
   }
 
-  void sort([Comparator<E> compare]) {
+  void sort([Comparator<E>? compare]) {
     throw new UnsupportedError('Cannot sort list');
   }
 
-  void shuffle([Random random]) {
+  void shuffle([Random? random]) {
     throw new UnsupportedError('Cannot shuffle list');
   }
 
@@ -12497,7 +13020,7 @@
    * * [Pseudo-elements](https://developer.mozilla.org/en-US/docs/Web/CSS/Pseudo-elements)
    *   from MDN.
    */
-  CssStyleDeclaration getComputedStyle([String pseudoElement]) {
+  CssStyleDeclaration getComputedStyle([String? pseudoElement]) {
     if (pseudoElement == null) {
       pseudoElement = '';
     }
@@ -13057,7 +13580,7 @@
 
       // Workaround for Safari bug. Was also previously Chrome bug 229142
       // - URIs are not resolved in new doc.
-      BaseElement base = _parseDocument.createElement('base');
+      BaseElement base = _parseDocument.createElement('base') as BaseElement;
       base.href = document.baseUri;
       _parseDocument.head.append(base);
     }
@@ -13836,9 +14359,17 @@
   static const EventStreamProvider<WheelEvent> wheelEvent =
       const EventStreamProvider<WheelEvent>('wheel');
 
-  String contentEditable;
+  String get contentEditable => JS("String", "#.contentEditable", this);
 
-  String dir;
+  set contentEditable(String value) {
+    JS("void", "#.contentEditable = #", this, value);
+  }
+
+  String get dir => JS("String", "#.dir", this);
+
+  set dir(String value) {
+    JS("void", "#.dir = #", this, value);
+  }
 
   /**
    * Indicates whether the element can be dragged and dropped.
@@ -13853,7 +14384,26 @@
    *   specification](https://html.spec.whatwg.org/multipage/interaction.html#dnd)
    *   from WHATWG.
    */
-  bool draggable;
+
+  bool get draggable => JS("bool", "#.draggable", this);
+
+  /**
+   * Indicates whether the element can be dragged and dropped.
+   *
+   * ## Other resources
+   *
+   * * [Drag and drop
+   *   sample](https://github.com/dart-lang/dart-samples/tree/master/html5/web/dnd/basics)
+   *   based on [the tutorial](http://www.html5rocks.com/en/tutorials/dnd/basics/)
+   *   from HTML5Rocks.
+   * * [Drag and drop
+   *   specification](https://html.spec.whatwg.org/multipage/interaction.html#dnd)
+   *   from WHATWG.
+   */
+
+  set draggable(bool value) {
+    JS("void", "#.draggable = #", this, value);
+  }
 
   /**
    * Indicates whether the element is not relevant to the page's current state.
@@ -13864,24 +14414,64 @@
    *   specification](https://html.spec.whatwg.org/multipage/interaction.html#the-hidden-attribute)
    *   from WHATWG.
    */
-  bool hidden;
 
-  bool inert;
+  bool get hidden => JS("bool", "#.hidden", this);
 
-  String inputMode;
+  /**
+   * Indicates whether the element is not relevant to the page's current state.
+   *
+   * ## Other resources
+   *
+   * * [Hidden attribute
+   *   specification](https://html.spec.whatwg.org/multipage/interaction.html#the-hidden-attribute)
+   *   from WHATWG.
+   */
+
+  set hidden(bool value) {
+    JS("void", "#.hidden = #", this, value);
+  }
+
+  bool get inert => JS("bool", "#.inert", this);
+
+  set inert(bool value) {
+    JS("void", "#.inert = #", this, value);
+  }
+
+  String get inputMode => JS("String", "#.inputMode", this);
+
+  set inputMode(String value) {
+    JS("void", "#.inputMode = #", this, value);
+  }
 
   // Using property as subclass shadows.
+
   bool get isContentEditable => JS("bool", "#.isContentEditable", this);
 
-  String lang;
+  String get lang => JS("String", "#.lang", this);
 
-  bool spellcheck;
+  set lang(String value) {
+    JS("void", "#.lang = #", this, value);
+  }
 
-  final CssStyleDeclaration style;
+  bool get spellcheck => JS("bool", "#.spellcheck", this);
 
-  int tabIndex;
+  set spellcheck(bool value) {
+    JS("void", "#.spellcheck = #", this, value);
+  }
 
-  String title;
+  CssStyleDeclaration get style => JS("CssStyleDeclaration", "#.style", this);
+
+  int get tabIndex => JS("int", "#.tabIndex", this);
+
+  set tabIndex(int value) {
+    JS("void", "#.tabIndex = #", this, value);
+  }
+
+  String get title => JS("String", "#.title", this);
+
+  set title(String value) {
+    JS("void", "#.title = #", this, value);
+  }
 
   /**
    * Specifies whether this element's text content changes when the page is
@@ -13893,7 +14483,23 @@
    *   attribute](https://html.spec.whatwg.org/multipage/dom.html#the-translate-attribute)
    *   from WHATWG.
    */
-  bool translate;
+
+  bool get translate => JS("bool", "#.translate", this);
+
+  /**
+   * Specifies whether this element's text content changes when the page is
+   * localized.
+   *
+   * ## Other resources
+   *
+   * * [The translate
+   *   attribute](https://html.spec.whatwg.org/multipage/dom.html#the-translate-attribute)
+   *   from WHATWG.
+   */
+
+  set translate(bool value) {
+    JS("void", "#.translate = #", this, value);
+  }
 
   void blur() native;
 
@@ -13901,58 +14507,86 @@
 
   void focus() native;
 
-  final AccessibleNode accessibleNode;
+  final AccessibleNode? accessibleNode;
 
-  final SlotElement assignedSlot;
+  final SlotElement? assignedSlot;
 
   @JSName('attributes')
-  final _NamedNodeMap _attributes;
+  _NamedNodeMap get _attributes => JS("_NamedNodeMap", "#.attributes", this);
 
-  String className;
+  String get className => JS("String", "#.className", this);
 
-  final int clientHeight;
+  set className(String value) {
+    JS("void", "#.className = #", this, value);
+  }
 
-  final int clientLeft;
+  int get clientHeight => JS("int", "#.clientHeight", this);
 
-  final int clientTop;
+  int get clientLeft => JS("int", "#.clientLeft", this);
 
-  final int clientWidth;
+  int get clientTop => JS("int", "#.clientTop", this);
 
-  final String computedName;
+  int get clientWidth => JS("int", "#.clientWidth", this);
 
-  final String computedRole;
+  final String? computedName;
 
-  String id;
+  final String? computedRole;
+
+  String get id => JS("String", "#.id", this);
+
+  set id(String value) {
+    JS("void", "#.id = #", this, value);
+  }
 
   @JSName('innerHTML')
-  String _innerHtml;
+  String get _innerHtml => JS("String", "#.innerHTML", this);
+
+  @JSName('innerHTML')
+  set _innerHtml(String value) {
+    JS("void", "#.innerHTML = #", this, value);
+  }
 
   @JSName('localName')
-  final String _localName;
+  String get _localName => JS("String", "#.localName", this);
 
   @JSName('namespaceURI')
-  final String _namespaceUri;
+  final String? _namespaceUri;
 
   // Using property as subclass shadows.
+
   String get outerHtml => JS("String", "#.outerHTML", this);
 
   @JSName('scrollHeight')
-  final int _scrollHeight;
+  int get _scrollHeight => JS("int", "#.scrollHeight", this);
 
   @JSName('scrollLeft')
-  num _scrollLeft;
+  num get _scrollLeft => JS("num", "#.scrollLeft", this);
+
+  @JSName('scrollLeft')
+  set _scrollLeft(num value) {
+    JS("void", "#.scrollLeft = #", this, value);
+  }
 
   @JSName('scrollTop')
-  num _scrollTop;
+  num get _scrollTop => JS("num", "#.scrollTop", this);
+
+  @JSName('scrollTop')
+  set _scrollTop(num value) {
+    JS("void", "#.scrollTop = #", this, value);
+  }
 
   @JSName('scrollWidth')
-  final int _scrollWidth;
+  int get _scrollWidth => JS("int", "#.scrollWidth", this);
 
-  String slot;
+  String get slot => JS("String", "#.slot", this);
 
-  final StylePropertyMap styleMap;
+  set slot(String value) {
+    JS("void", "#.slot = #", this, value);
+  }
 
-  final String tagName;
+  StylePropertyMap get styleMap => JS("StylePropertyMap", "#.styleMap", this);
+
+  String get tagName => JS("String", "#.tagName", this);
 
   ShadowRoot attachShadow(Map shadowRootInitDict) {
     var shadowRootInitDict_1 =
@@ -13971,7 +14605,7 @@
   String _getAttribute(String name) native;
 
   @JSName('getAttributeNS')
-  String _getAttributeNS(String namespaceURI, String localName) native;
+  String _getAttributeNS(String? namespaceURI, String localName) native;
 
   List<String> getAttributeNames() native;
 
@@ -14044,7 +14678,7 @@
   bool _hasAttribute(String name) native;
 
   @JSName('hasAttributeNS')
-  bool _hasAttributeNS(String namespaceURI, String localName) native;
+  bool _hasAttributeNS(String? namespaceURI, String localName) native;
 
   bool hasPointerCapture(int pointerId) native;
 
@@ -14054,11 +14688,11 @@
   void _removeAttribute(String name) native;
 
   @JSName('removeAttributeNS')
-  void _removeAttributeNS(String namespaceURI, String localName) native;
+  void _removeAttributeNS(String? namespaceURI, String localName) native;
 
   void requestPointerLock() native;
 
-  void scroll([options_OR_x, num y]) {
+  void scroll([options_OR_x, num? y]) {
     if (options_OR_x == null && y == null) {
       _scroll_1();
       return;
@@ -14082,7 +14716,7 @@
   @JSName('scroll')
   void _scroll_3(num x, y) native;
 
-  void scrollBy([options_OR_x, num y]) {
+  void scrollBy([options_OR_x, num? y]) {
     if (options_OR_x == null && y == null) {
       _scrollBy_1();
       return;
@@ -14107,12 +14741,12 @@
   void _scrollBy_3(num x, y) native;
 
   @JSName('scrollIntoView')
-  void _scrollIntoView([Object arg]) native;
+  void _scrollIntoView([Object? arg]) native;
 
   @JSName('scrollIntoViewIfNeeded')
-  void _scrollIntoViewIfNeeded([bool centerIfNeeded]) native;
+  void _scrollIntoViewIfNeeded([bool? centerIfNeeded]) native;
 
-  void scrollTo([options_OR_x, num y]) {
+  void scrollTo([options_OR_x, num? y]) {
     if (options_OR_x == null && y == null) {
       _scrollTo_1();
       return;
@@ -14140,7 +14774,7 @@
   void _setAttribute(String name, String value) native;
 
   @JSName('setAttributeNS')
-  void _setAttributeNS(String namespaceURI, String name, String value) native;
+  void _setAttributeNS(String? namespaceURI, String name, String value) native;
 
   void setPointerCapture(int pointerId) native;
 
@@ -14167,25 +14801,25 @@
 
   // From NonDocumentTypeChildNode
 
-  final Element nextElementSibling;
+  final Element? nextElementSibling;
 
-  final Element previousElementSibling;
+  final Element? previousElementSibling;
 
   // From ParentNode
 
   @JSName('childElementCount')
-  final int _childElementCount;
+  int get _childElementCount => JS("int", "#.childElementCount", this);
 
   @JSName('children')
   @Returns('HtmlCollection|Null')
   @Creates('HtmlCollection')
-  final List<Node> _children;
+  List<Node> get _children => JS("HtmlCollection", "#.children", this);
 
   @JSName('firstElementChild')
-  final Element _firstElementChild;
+  final Element? _firstElementChild;
 
   @JSName('lastElementChild')
-  final Element _lastElementChild;
+  final Element? _lastElementChild;
 
   /**
    * Finds the first descendant element of this element that matches the
@@ -14563,7 +15197,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory EmbedElement() => document.createElement("embed");
+  factory EmbedElement() => document.createElement("embed") as EmbedElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -14574,15 +15208,35 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('embed');
 
-  String height;
+  String get height => JS("String", "#.height", this);
 
-  String name;
+  set height(String value) {
+    JS("void", "#.height = #", this, value);
+  }
 
-  String src;
+  String get name => JS("String", "#.name", this);
 
-  String type;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
-  String width;
+  String get src => JS("String", "#.src", this);
+
+  set src(String value) {
+    JS("void", "#.src = #", this, value);
+  }
+
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
+
+  String get width => JS("String", "#.width", this);
+
+  set width(String value) {
+    JS("void", "#.width = #", this, value);
+  }
 
   Node __getter__(String name) native;
 
@@ -14606,24 +15260,24 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final FileSystem filesystem;
+  FileSystem get filesystem => JS("FileSystem", "#.filesystem", this);
 
-  final String fullPath;
+  String get fullPath => JS("String", "#.fullPath", this);
 
-  final bool isDirectory;
+  bool get isDirectory => JS("bool", "#.isDirectory", this);
 
-  final bool isFile;
+  bool get isFile => JS("bool", "#.isFile", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
   @JSName('copyTo')
   void _copyTo(DirectoryEntry parent,
-      [String name,
-      _EntryCallback successCallback,
-      _ErrorCallback errorCallback]) native;
+      [String? name,
+      _EntryCallback? successCallback,
+      _ErrorCallback? errorCallback]) native;
 
   @JSName('copyTo')
-  Future<Entry> copyTo(DirectoryEntry parent, {String name}) {
+  Future<Entry> copyTo(DirectoryEntry parent, {String? name}) {
     var completer = new Completer<Entry>();
     _copyTo(parent, name, (value) {
       completer.complete(value);
@@ -14635,7 +15289,7 @@
 
   @JSName('getMetadata')
   void _getMetadata(MetadataCallback successCallback,
-      [_ErrorCallback errorCallback]) native;
+      [_ErrorCallback? errorCallback]) native;
 
   @JSName('getMetadata')
   Future<Metadata> getMetadata() {
@@ -14651,7 +15305,7 @@
 
   @JSName('getParent')
   void _getParent(
-      [_EntryCallback successCallback, _ErrorCallback errorCallback]) native;
+      [_EntryCallback? successCallback, _ErrorCallback? errorCallback]) native;
 
   @JSName('getParent')
   Future<Entry> getParent() {
@@ -14667,12 +15321,12 @@
 
   @JSName('moveTo')
   void _moveTo(DirectoryEntry parent,
-      [String name,
-      _EntryCallback successCallback,
-      _ErrorCallback errorCallback]) native;
+      [String? name,
+      _EntryCallback? successCallback,
+      _ErrorCallback? errorCallback]) native;
 
   @JSName('moveTo')
-  Future<Entry> moveTo(DirectoryEntry parent, {String name}) {
+  Future<Entry> moveTo(DirectoryEntry parent, {String? name}) {
     var completer = new Completer<Entry>();
     _moveTo(parent, name, (value) {
       completer.complete(value);
@@ -14683,7 +15337,7 @@
   }
 
   @JSName('remove')
-  void _remove(VoidCallback successCallback, [_ErrorCallback errorCallback])
+  void _remove(VoidCallback successCallback, [_ErrorCallback? errorCallback])
       native;
 
   @JSName('remove')
@@ -14726,7 +15380,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ErrorEvent(String type, [Map eventInitDict]) {
+  factory ErrorEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return ErrorEvent._create_1(type, eventInitDict_1);
@@ -14738,16 +15392,16 @@
   static ErrorEvent _create_2(type) =>
       JS('ErrorEvent', 'new ErrorEvent(#)', type);
 
-  final int colno;
+  int get colno => JS("int", "#.colno", this);
 
   @Creates('Null')
-  final Object error;
+  Object get error => JS("Object", "#.error", this);
 
-  final String filename;
+  String get filename => JS("String", "#.filename", this);
 
-  final int lineno;
+  int get lineno => JS("int", "#.lineno", this);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -14809,7 +15463,7 @@
   List<EventTarget> get path =>
       JS('bool', '!!#.composedPath', this) ? composedPath() : [];
 
-  factory Event._(String type, [Map eventInitDict]) {
+  factory Event._(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return Event._create_1(type, eventInitDict_1);
@@ -14851,39 +15505,39 @@
    */
   static const int CAPTURING_PHASE = 1;
 
-  final bool bubbles;
+  bool get bubbles => JS("bool", "#.bubbles", this);
 
-  final bool cancelable;
+  bool get cancelable => JS("bool", "#.cancelable", this);
 
-  final bool composed;
+  bool get composed => JS("bool", "#.composed", this);
 
-  EventTarget get currentTarget =>
+  EventTarget? get currentTarget =>
       _convertNativeToDart_EventTarget(this._get_currentTarget);
   @JSName('currentTarget')
   @Creates('Null')
   @Returns('EventTarget|=Object|Null')
   final dynamic _get_currentTarget;
 
-  final bool defaultPrevented;
+  bool get defaultPrevented => JS("bool", "#.defaultPrevented", this);
 
-  final int eventPhase;
+  int get eventPhase => JS("int", "#.eventPhase", this);
 
-  final bool isTrusted;
+  bool get isTrusted => JS("bool", "#.isTrusted", this);
 
-  EventTarget get target => _convertNativeToDart_EventTarget(this._get_target);
+  EventTarget? get target => _convertNativeToDart_EventTarget(this._get_target);
   @JSName('target')
   @Creates('Node')
   @Returns('EventTarget|=Object')
   final dynamic _get_target;
 
-  final num timeStamp;
+  num get timeStamp => JS("num", "#.timeStamp", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
   List<EventTarget> composedPath() native;
 
   @JSName('initEvent')
-  void _initEvent(String type, [bool bubbles, bool cancelable]) native;
+  void _initEvent(String type, [bool? bubbles, bool? cancelable]) native;
 
   void preventDefault() native;
 
@@ -14936,7 +15590,7 @@
       const EventStreamProvider<Event>('open');
 
   static EventSource _factoryEventSource(String url,
-      [Map eventSourceInitDict]) {
+      [Map? eventSourceInitDict]) {
     if (eventSourceInitDict != null) {
       var eventSourceInitDict_1 =
           convertDartToNative_Dictionary(eventSourceInitDict);
@@ -14956,11 +15610,11 @@
 
   static const int OPEN = 1;
 
-  final int readyState;
+  int get readyState => JS("int", "#.readyState", this);
 
-  final String url;
+  String get url => JS("String", "#.url", this);
 
-  final bool withCredentials;
+  bool get withCredentials => JS("bool", "#.withCredentials", this);
 
   void close() native;
 
@@ -15098,14 +15752,14 @@
   }
 
   @JSName('addEventListener')
-  void _addEventListener(String type, EventListener listener, [bool options])
+  void _addEventListener(String type, EventListener? listener, [bool? options])
       native;
 
   bool dispatchEvent(Event event) native;
 
   @JSName('removeEventListener')
-  void _removeEventListener(String type, EventListener listener, [bool options])
-      native;
+  void _removeEventListener(String type, EventListener? listener,
+      [bool? options]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -15118,7 +15772,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ExtendableEvent(String type, [Map eventInitDict]) {
+  factory ExtendableEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return ExtendableEvent._create_1(type, eventInitDict_1);
@@ -15145,17 +15799,17 @@
 
   @annotation_Creates_SerializedScriptValue
   @annotation_Returns_SerializedScriptValue
-  final Object data;
+  Object get data => JS("Object", "#.data", this);
 
-  final String lastEventId;
+  String get lastEventId => JS("String", "#.lastEventId", this);
 
-  final String origin;
+  String get origin => JS("String", "#.origin", this);
 
-  final List<MessagePort> ports;
+  List<MessagePort> get ports => JS("List<MessagePort>", "#.ports", this);
 
   @Creates('Client|ServiceWorker|MessagePort')
   @Returns('Client|ServiceWorker|MessagePort|Null')
-  final Object source;
+  final Object? source;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -15183,7 +15837,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory FaceDetector([Map faceDetectorOptions]) {
+  factory FaceDetector([Map? faceDetectorOptions]) {
     if (faceDetectorOptions != null) {
       var faceDetectorOptions_1 =
           convertDartToNative_Dictionary(faceDetectorOptions);
@@ -15216,16 +15870,16 @@
   static FederatedCredential _create_1(data) =>
       JS('FederatedCredential', 'new FederatedCredential(#)', data);
 
-  final String protocol;
+  final String? protocol;
 
-  final String provider;
+  String get provider => JS("String", "#.provider", this);
 
   // From CredentialUserData
 
   @JSName('iconURL')
-  final String iconUrl;
+  String get iconUrl => JS("String", "#.iconURL", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -15245,14 +15899,13 @@
   static FetchEvent _create_1(type, eventInitDict) =>
       JS('FetchEvent', 'new FetchEvent(#,#)', type, eventInitDict);
 
-  final String clientId;
+  final String? clientId;
 
-  final bool isReload;
+  bool get isReload => JS("bool", "#.isReload", this);
 
-  Future get preloadResponse =>
-      promiseToFuture(JS("", "#.preloadResponse", this));
+  Future get preloadResponse => JS("Future", "#.preloadResponse", this);
 
-  final _Request request;
+  _Request get request => JS("_Request", "#.request", this);
 
   void respondWith(Future r) native;
 }
@@ -15268,7 +15921,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory FieldSetElement() => JS(
+  factory FieldSetElement() => JS<FieldSetElement>(
       'returns:FieldSetElement;creates:FieldSetElement;new:true',
       '#.createElement(#)',
       document,
@@ -15280,23 +15933,31 @@
    */
   FieldSetElement.created() : super.created();
 
-  bool disabled;
+  bool get disabled => JS("bool", "#.disabled", this);
+
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
 
   @Returns('HtmlCollection|Null')
   @Creates('HtmlCollection')
-  final List<Node> elements;
+  List<Node> get elements => JS("HtmlCollection", "#.elements", this);
 
-  final FormElement form;
+  final FormElement? form;
 
-  String name;
+  String get name => JS("String", "#.name", this);
 
-  final String type;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
-  final String validationMessage;
+  String get type => JS("String", "#.type", this);
 
-  final ValidityState validity;
+  String get validationMessage => JS("String", "#.validationMessage", this);
 
-  final bool willValidate;
+  ValidityState get validity => JS("ValidityState", "#.validity", this);
+
+  bool get willValidate => JS("bool", "#.willValidate", this);
 
   bool checkValidity() native;
 
@@ -15315,7 +15976,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory File(List<Object> fileBits, String fileName, [Map options]) {
+  factory File(List<Object> fileBits, String fileName, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return File._create_1(fileBits, fileName, options_1);
@@ -15327,7 +15988,7 @@
   static File _create_2(fileBits, fileName) =>
       JS('File', 'new File(#,#)', fileBits, fileName);
 
-  final int lastModified;
+  int get lastModified => JS("int", "#.lastModified", this);
 
   DateTime get lastModifiedDate =>
       convertNativeToDart_DateTime(this._get_lastModifiedDate);
@@ -15335,12 +15996,12 @@
   @Creates('Null')
   final dynamic _get_lastModifiedDate;
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
   @JSName('webkitRelativePath')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final String relativePath;
+  String get relativePath => JS("String", "#.webkitRelativePath", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -15348,7 +16009,7 @@
 
 // WARNING: Do not edit - generated code.
 
-typedef void _FileCallback(File file);
+typedef void _FileCallback(File? file);
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
@@ -15362,7 +16023,7 @@
 
   @JSName('createWriter')
   void _createWriter(_FileWriterCallback successCallback,
-      [_ErrorCallback errorCallback]) native;
+      [_ErrorCallback? errorCallback]) native;
 
   @JSName('createWriter')
   Future<FileWriter> createWriter() {
@@ -15377,7 +16038,7 @@
   }
 
   @JSName('file')
-  void _file(_FileCallback successCallback, [_ErrorCallback errorCallback])
+  void _file(_FileCallback successCallback, [_ErrorCallback? errorCallback])
       native;
 
   @JSName('file')
@@ -15536,9 +16197,9 @@
 
   static const int LOADING = 1;
 
-  final DomException error;
+  final DomException? error;
 
-  final int readyState;
+  int get readyState => JS("int", "#.readyState", this);
 
   void abort() native;
 
@@ -15547,7 +16208,7 @@
   @JSName('readAsDataURL')
   void readAsDataUrl(Blob blob) native;
 
-  void readAsText(Blob blob, [String label]) native;
+  void readAsText(Blob blob, [String? label]) native;
 
   /// Stream of `abort` events handled by this [FileReader].
   Stream<ProgressEvent> get onAbort => abortEvent.forTarget(this);
@@ -15582,9 +16243,9 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => JS('bool', '!!(window.webkitRequestFileSystem)');
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
-  final DirectoryEntry root;
+  DirectoryEntry get root => JS("DirectoryEntry", "#.root", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -15664,13 +16325,13 @@
 
   static const int WRITING = 1;
 
-  final DomException error;
+  final DomException? error;
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
-  final int position;
+  int get position => JS("int", "#.position", this);
 
-  final int readyState;
+  int get readyState => JS("int", "#.readyState", this);
 
   void abort() native;
 
@@ -15716,7 +16377,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory FocusEvent(String type, [Map eventInitDict]) {
+  factory FocusEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return FocusEvent._create_1(type, eventInitDict_1);
@@ -15728,7 +16389,7 @@
   static FocusEvent _create_2(type) =>
       JS('FocusEvent', 'new FocusEvent(#)', type);
 
-  EventTarget get relatedTarget =>
+  EventTarget? get relatedTarget =>
       _convertNativeToDart_EventTarget(this._get_relatedTarget);
   @JSName('relatedTarget')
   @Creates('Null')
@@ -15745,7 +16406,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory FontFace(String family, Object source, [Map descriptors]) {
+  factory FontFace(String family, Object source, [Map? descriptors]) {
     if (descriptors != null) {
       var descriptors_1 = convertDartToNative_Dictionary(descriptors);
       return FontFace._create_1(family, source, descriptors_1);
@@ -15757,26 +16418,57 @@
   static FontFace _create_2(family, source) =>
       JS('FontFace', 'new FontFace(#,#)', family, source);
 
-  String display;
+  String get display => JS("String", "#.display", this);
 
-  String family;
+  set display(String value) {
+    JS("void", "#.display = #", this, value);
+  }
 
-  String featureSettings;
+  String get family => JS("String", "#.family", this);
 
-  Future<FontFace> get loaded =>
-      promiseToFuture<FontFace>(JS("", "#.loaded", this));
+  set family(String value) {
+    JS("void", "#.family = #", this, value);
+  }
 
-  final String status;
+  String get featureSettings => JS("String", "#.featureSettings", this);
 
-  String stretch;
+  set featureSettings(String value) {
+    JS("void", "#.featureSettings = #", this, value);
+  }
 
-  String style;
+  Future get loaded => JS("Future", "#.loaded", this);
 
-  String unicodeRange;
+  String get status => JS("String", "#.status", this);
 
-  String variant;
+  String get stretch => JS("String", "#.stretch", this);
 
-  String weight;
+  set stretch(String value) {
+    JS("void", "#.stretch = #", this, value);
+  }
+
+  String get style => JS("String", "#.style", this);
+
+  set style(String value) {
+    JS("void", "#.style = #", this, value);
+  }
+
+  String get unicodeRange => JS("String", "#.unicodeRange", this);
+
+  set unicodeRange(String value) {
+    JS("void", "#.unicodeRange = #", this, value);
+  }
+
+  String get variant => JS("String", "#.variant", this);
+
+  set variant(String value) {
+    JS("void", "#.variant = #", this, value);
+  }
+
+  String get weight => JS("String", "#.weight", this);
+
+  set weight(String value) {
+    JS("void", "#.weight = #", this, value);
+  }
 
   Future<FontFace> load() =>
       promiseToFuture<FontFace>(JS("", "#.load()", this));
@@ -15801,17 +16493,17 @@
   static const EventStreamProvider<FontFaceSetLoadEvent> loadingErrorEvent =
       const EventStreamProvider<FontFaceSetLoadEvent>('loadingerror');
 
-  final String status;
+  String get status => JS("String", "#.status", this);
 
   FontFaceSet add(FontFace arg) native;
 
-  bool check(String font, [String text]) native;
+  bool check(String font, [String? text]) native;
 
   void clear() native;
 
   bool delete(FontFace arg) native;
 
-  void forEach(FontFaceSetForEachCallback callback, [Object thisArg]) native;
+  void forEach(FontFaceSetForEachCallback callback, [Object? thisArg]) native;
 
   bool has(FontFace arg) native;
 
@@ -15834,7 +16526,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory FontFaceSetLoadEvent(String type, [Map eventInitDict]) {
+  factory FontFaceSetLoadEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return FontFaceSetLoadEvent._create_1(type, eventInitDict_1);
@@ -15849,7 +16541,7 @@
   static FontFaceSetLoadEvent _create_2(type) =>
       JS('FontFaceSetLoadEvent', 'new FontFaceSetLoadEvent(#)', type);
 
-  final List<FontFace> fontfaces;
+  List<FontFace> get fontfaces => JS("List<FontFace>", "#.fontfaces", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -15862,7 +16554,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final FontFaceSet fonts;
+  FontFaceSet get fonts => JS("FontFaceSet", "#.fonts", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -15882,9 +16574,9 @@
   static ForeignFetchEvent _create_1(type, eventInitDict) => JS(
       'ForeignFetchEvent', 'new ForeignFetchEvent(#,#)', type, eventInitDict);
 
-  final String origin;
+  String get origin => JS("String", "#.origin", this);
 
-  final _Request request;
+  _Request get request => JS("_Request", "#.request", this);
 
   void respondWith(Future r) native;
 }
@@ -15903,7 +16595,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory FormData([FormElement form]) {
+  factory FormData([FormElement? form]) {
     if (form != null) {
       return FormData._create_1(form);
     }
@@ -15918,7 +16610,7 @@
   void append(String name, String value) native;
 
   @JSName('append')
-  void appendBlob(String name, Blob value, [String filename]) native;
+  void appendBlob(String name, Blob value, [String? filename]) native;
 
   void delete(String name) native;
 
@@ -15928,7 +16620,7 @@
 
   bool has(String name) native;
 
-  void set(String name, value, [String filename]) native;
+  void set(String name, value, [String? filename]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -15941,7 +16633,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory FormElement() => JS(
+  factory FormElement() => JS<FormElement>(
       'returns:FormElement;creates:FormElement;new:true',
       '#.createElement(#)',
       document,
@@ -15953,25 +16645,61 @@
    */
   FormElement.created() : super.created();
 
-  String acceptCharset;
+  String get acceptCharset => JS("String", "#.acceptCharset", this);
 
-  String action;
+  set acceptCharset(String value) {
+    JS("void", "#.acceptCharset = #", this, value);
+  }
 
-  String autocomplete;
+  String get action => JS("String", "#.action", this);
 
-  String encoding;
+  set action(String value) {
+    JS("void", "#.action = #", this, value);
+  }
 
-  String enctype;
+  String get autocomplete => JS("String", "#.autocomplete", this);
 
-  final int length;
+  set autocomplete(String value) {
+    JS("void", "#.autocomplete = #", this, value);
+  }
 
-  String method;
+  String get encoding => JS("String", "#.encoding", this);
 
-  String name;
+  set encoding(String value) {
+    JS("void", "#.encoding = #", this, value);
+  }
 
-  bool noValidate;
+  String get enctype => JS("String", "#.enctype", this);
 
-  String target;
+  set enctype(String value) {
+    JS("void", "#.enctype = #", this, value);
+  }
+
+  int get length => JS("int", "#.length", this);
+
+  String get method => JS("String", "#.method", this);
+
+  set method(String value) {
+    JS("void", "#.method = #", this, value);
+  }
+
+  String get name => JS("String", "#.name", this);
+
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
+
+  bool get noValidate => JS("bool", "#.noValidate", this);
+
+  set noValidate(bool value) {
+    JS("void", "#.noValidate = #", this, value);
+  }
+
+  String get target => JS("String", "#.target", this);
+
+  set target(String value) {
+    JS("void", "#.target = #", this, value);
+  }
 
   Object __getter__(String name) native;
 
@@ -16019,27 +16747,28 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final List<num> axes;
+  List<num> get axes => JS("List<num>", "#.axes", this);
 
   @Creates('JSExtendableArray|GamepadButton')
   @Returns('JSExtendableArray')
-  final List<GamepadButton> buttons;
+  List<GamepadButton> get buttons =>
+      JS("List<GamepadButton>", "#.buttons", this);
 
-  final bool connected;
+  bool get connected => JS("bool", "#.connected", this);
 
-  final int displayId;
+  int get displayId => JS("int", "#.displayId", this);
 
-  final String hand;
+  String get hand => JS("String", "#.hand", this);
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
-  final int index;
+  int get index => JS("int", "#.index", this);
 
-  final String mapping;
+  String get mapping => JS("String", "#.mapping", this);
 
-  final GamepadPose pose;
+  final GamepadPose? pose;
 
-  final int timestamp;
+  int get timestamp => JS("int", "#.timestamp", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -16052,11 +16781,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool pressed;
+  bool get pressed => JS("bool", "#.pressed", this);
 
-  final bool touched;
+  bool get touched => JS("bool", "#.touched", this);
 
-  final num value;
+  num get value => JS("num", "#.value", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -16069,7 +16798,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory GamepadEvent(String type, [Map eventInitDict]) {
+  factory GamepadEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return GamepadEvent._create_1(type, eventInitDict_1);
@@ -16081,7 +16810,7 @@
   static GamepadEvent _create_2(type) =>
       JS('GamepadEvent', 'new GamepadEvent(#)', type);
 
-  final Gamepad gamepad;
+  Gamepad get gamepad => JS("Gamepad", "#.gamepad", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -16094,21 +16823,21 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Float32List angularAcceleration;
+  final Float32List? angularAcceleration;
 
-  final Float32List angularVelocity;
+  final Float32List? angularVelocity;
 
-  final bool hasOrientation;
+  bool get hasOrientation => JS("bool", "#.hasOrientation", this);
 
-  final bool hasPosition;
+  bool get hasPosition => JS("bool", "#.hasPosition", this);
 
-  final Float32List linearAcceleration;
+  final Float32List? linearAcceleration;
 
-  final Float32List linearVelocity;
+  final Float32List? linearVelocity;
 
-  final Float32List orientation;
+  final Float32List? orientation;
 
-  final Float32List position;
+  final Float32List? position;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -16118,7 +16847,7 @@
 @Native("Geolocation")
 class Geolocation extends Interceptor {
   Future<Geoposition> getCurrentPosition(
-      {bool enableHighAccuracy, Duration timeout, Duration maximumAge}) {
+      {bool? enableHighAccuracy, Duration? timeout, Duration? maximumAge}) {
     var options = {};
     if (enableHighAccuracy != null) {
       options['enableHighAccuracy'] = enableHighAccuracy;
@@ -16143,7 +16872,7 @@
   }
 
   Stream<Geoposition> watchPosition(
-      {bool enableHighAccuracy, Duration timeout, Duration maximumAge}) {
+      {bool? enableHighAccuracy, Duration? timeout, Duration? maximumAge}) {
     var options = {};
     if (enableHighAccuracy != null) {
       options['enableHighAccuracy'] = enableHighAccuracy;
@@ -16197,7 +16926,7 @@
   void _clearWatch(int watchID) native;
 
   void _getCurrentPosition(_PositionCallback successCallback,
-      [_PositionErrorCallback errorCallback, Map options]) {
+      [_PositionErrorCallback? errorCallback, Map? options]) {
     if (options != null) {
       var successCallback_1 = convertDartClosureToJS(successCallback, 1);
       var options_2 = convertDartToNative_Dictionary(options);
@@ -16224,7 +16953,7 @@
   void _getCurrentPosition_3(successCallback) native;
 
   int _watchPosition(_PositionCallback successCallback,
-      [_PositionErrorCallback errorCallback, Map options]) {
+      [_PositionErrorCallback? errorCallback, Map? options]) {
     if (options != null) {
       var successCallback_1 = convertDartClosureToJS(successCallback, 1);
       var options_2 = convertDartToNative_Dictionary(options);
@@ -16271,9 +17000,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Coordinates coords;
+  Coordinates get coords => JS("Coordinates", "#.coords", this);
 
-  final int timestamp;
+  int get timestamp => JS("int", "#.timestamp", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -16593,7 +17322,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory Gyroscope([Map sensorOptions]) {
+  factory Gyroscope([Map? sensorOptions]) {
     if (sensorOptions != null) {
       var sensorOptions_1 = convertDartToNative_Dictionary(sensorOptions);
       return Gyroscope._create_1(sensorOptions_1);
@@ -16624,8 +17353,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory HRElement() => JS('returns:HRElement;creates:HRElement;new:true',
-      '#.createElement(#)', document, "hr");
+  factory HRElement() => JS<HRElement>(
+      'returns:HRElement;creates:HRElement;new:true',
+      '#.createElement(#)',
+      document,
+      "hr");
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -16633,7 +17365,11 @@
    */
   HRElement.created() : super.created();
 
-  String color;
+  String get color => JS("String", "#.color", this);
+
+  set color(String value) {
+    JS("void", "#.color = #", this, value);
+  }
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -16662,7 +17398,7 @@
         convertDartToNative_Dictionary(options));
   }
 
-  factory HashChangeEvent._(String type, [Map eventInitDict]) {
+  factory HashChangeEvent._(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return HashChangeEvent._create_1(type, eventInitDict_1);
@@ -16678,10 +17414,10 @@
   static bool get supported => Device.isEventTypeSupported('HashChangeEvent');
 
   @JSName('newURL')
-  final String newUrl;
+  String get newUrl => JS("String", "#.newURL", this);
 
   @JSName('oldURL')
-  final String oldUrl;
+  String get oldUrl => JS("String", "#.oldURL", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -16694,7 +17430,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory HeadElement() => JS(
+  factory HeadElement() => JS<HeadElement>(
       'returns:HeadElement;creates:HeadElement;new:true',
       '#.createElement(#)',
       document,
@@ -16717,7 +17453,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory Headers([Object init]) {
+  factory Headers([Object? init]) {
     if (init != null) {
       return Headers._create_1(init);
     }
@@ -16737,37 +17473,37 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory HeadingElement.h1() => JS(
+  factory HeadingElement.h1() => JS<HeadingElement>(
       'returns:HeadingElement;creates:HeadingElement;new:true',
       '#.createElement(#)',
       document,
       "h1");
 
-  factory HeadingElement.h2() => JS(
+  factory HeadingElement.h2() => JS<HeadingElement>(
       'returns:HeadingElement;creates:HeadingElement;new:true',
       '#.createElement(#)',
       document,
       "h2");
 
-  factory HeadingElement.h3() => JS(
+  factory HeadingElement.h3() => JS<HeadingElement>(
       'returns:HeadingElement;creates:HeadingElement;new:true',
       '#.createElement(#)',
       document,
       "h3");
 
-  factory HeadingElement.h4() => JS(
+  factory HeadingElement.h4() => JS<HeadingElement>(
       'returns:HeadingElement;creates:HeadingElement;new:true',
       '#.createElement(#)',
       document,
       "h4");
 
-  factory HeadingElement.h5() => JS(
+  factory HeadingElement.h5() => JS<HeadingElement>(
       'returns:HeadingElement;creates:HeadingElement;new:true',
       '#.createElement(#)',
       document,
       "h5");
 
-  factory HeadingElement.h6() => JS(
+  factory HeadingElement.h6() => JS<HeadingElement>(
       'returns:HeadingElement;creates:HeadingElement;new:true',
       '#.createElement(#)',
       document,
@@ -16800,9 +17536,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
-  String scrollRestoration;
+  String get scrollRestoration => JS("String", "#.scrollRestoration", this);
+
+  set scrollRestoration(String value) {
+    JS("void", "#.scrollRestoration = #", this, value);
+  }
 
   dynamic get state =>
       convertNativeToDart_SerializedScriptValue(this._get_state);
@@ -16815,13 +17555,13 @@
 
   void forward() native;
 
-  void go([int delta]) native;
+  void go([int? delta]) native;
 
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.FIREFOX)
   @SupportedBrowser(SupportedBrowser.IE, '10')
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  void pushState(/*SerializedScriptValue*/ data, String title, String url) {
+  void pushState(/*SerializedScriptValue*/ data, String title, String? url) {
     var data_1 = convertDartToNative_SerializedScriptValue(data);
     _pushState_1(data_1, title, url);
     return;
@@ -16838,7 +17578,7 @@
   @SupportedBrowser(SupportedBrowser.FIREFOX)
   @SupportedBrowser(SupportedBrowser.IE, '10')
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  void replaceState(/*SerializedScriptValue*/ data, String title, String url) {
+  void replaceState(/*SerializedScriptValue*/ data, String title, String? url) {
     var data_1 = convertDartToNative_SerializedScriptValue(data);
     _replaceState_1(data_1, title, url);
     return;
@@ -17098,7 +17838,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory HtmlHtmlElement() => JS(
+  factory HtmlHtmlElement() => JS<HtmlHtmlElement>(
       'returns:HtmlHtmlElement;creates:HtmlHtmlElement;new:true',
       '#.createElement(#)',
       document,
@@ -17121,27 +17861,67 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String hash;
+  String get hash => JS("String", "#.hash", this);
 
-  String host;
+  set hash(String value) {
+    JS("void", "#.hash = #", this, value);
+  }
 
-  String hostname;
+  String get host => JS("String", "#.host", this);
 
-  String href;
+  set host(String value) {
+    JS("void", "#.host = #", this, value);
+  }
 
-  final String origin;
+  String get hostname => JS("String", "#.hostname", this);
 
-  String password;
+  set hostname(String value) {
+    JS("void", "#.hostname = #", this, value);
+  }
 
-  String pathname;
+  String get href => JS("String", "#.href", this);
 
-  String port;
+  set href(String value) {
+    JS("void", "#.href = #", this, value);
+  }
 
-  String protocol;
+  String get origin => JS("String", "#.origin", this);
 
-  String search;
+  String get password => JS("String", "#.password", this);
 
-  String username;
+  set password(String value) {
+    JS("void", "#.password = #", this, value);
+  }
+
+  String get pathname => JS("String", "#.pathname", this);
+
+  set pathname(String value) {
+    JS("void", "#.pathname = #", this, value);
+  }
+
+  String get port => JS("String", "#.port", this);
+
+  set port(String value) {
+    JS("void", "#.port = #", this, value);
+  }
+
+  String get protocol => JS("String", "#.protocol", this);
+
+  set protocol(String value) {
+    JS("void", "#.protocol = #", this, value);
+  }
+
+  String get search => JS("String", "#.search", this);
+
+  set search(String value) {
+    JS("void", "#.search = #", this, value);
+  }
+
+  String get username => JS("String", "#.username", this);
+
+  set username(String value) {
+    JS("void", "#.username = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -17230,7 +18010,7 @@
    * * [request]
    */
   static Future<String> getString(String url,
-      {bool withCredentials, void onProgress(ProgressEvent e)}) {
+      {bool? withCredentials, void onProgress(ProgressEvent e)?}) {
     return request(url,
             withCredentials: withCredentials, onProgress: onProgress)
         .then((HttpRequest xhr) => xhr.responseText);
@@ -17628,7 +18408,8 @@
    *   </tr>
    * </table>
    */
-  final int readyState;
+
+  int get readyState => JS("int", "#.readyState", this);
 
   /**
    * The data received as a reponse from the request.
@@ -17661,7 +18442,8 @@
   /**
    * The response in String form or empty String on failure.
    */
-  final String responseText;
+
+  String get responseText => JS("String", "#.responseText", this);
 
   /**
    * [String] telling the server the desired response format.
@@ -17674,10 +18456,27 @@
    * See also: [MDN
    * responseType](https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest#xmlhttprequest-responsetype)
    */
-  String responseType;
+
+  String get responseType => JS("String", "#.responseType", this);
+
+  /**
+   * [String] telling the server the desired response format.
+   *
+   * Default is `String`.
+   * Other options are one of 'arraybuffer', 'blob', 'document', 'json',
+   * 'text'. Some newer browsers will throw NS_ERROR_DOM_INVALID_ACCESS_ERR if
+   * `responseType` is set while performing a synchronous request.
+   *
+   * See also: [MDN
+   * responseType](https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest#xmlhttprequest-responsetype)
+   */
+
+  set responseType(String value) {
+    JS("void", "#.responseType = #", this, value);
+  }
 
   @JSName('responseURL')
-  final String responseUrl;
+  String get responseUrl => JS("String", "#.responseURL", this);
 
   @JSName('responseXML')
   /**
@@ -17687,19 +18486,21 @@
    * `text/xml` stream, unless responseType = 'document' and the request is
    * synchronous.
    */
-  final Document responseXml;
+  final Document? responseXml;
 
   /**
    * The HTTP result code from the request (200, 404, etc).
    * See also: [HTTP Status Codes](http://en.wikipedia.org/wiki/List_of_HTTP_status_codes)
    */
-  final int status;
+
+  int get status => JS("int", "#.status", this);
 
   /**
    * The request response string (such as \"OK\").
    * See also: [HTTP Status Codes](http://en.wikipedia.org/wiki/List_of_HTTP_status_codes)
    */
-  final String statusText;
+
+  String get statusText => JS("String", "#.statusText", this);
 
   /**
    * Length of time in milliseconds before a request is automatically
@@ -17716,14 +18517,35 @@
    * * [The timeout attribute](http://www.w3.org/TR/XMLHttpRequest/#the-timeout-attribute)
    *   from W3C.
    */
-  int timeout;
+
+  int get timeout => JS("int", "#.timeout", this);
+
+  /**
+   * Length of time in milliseconds before a request is automatically
+   * terminated.
+   *
+   * When the time has passed, a [TimeoutEvent] is dispatched.
+   *
+   * If [timeout] is set to 0, then the request will not time out.
+   *
+   * ## Other resources
+   *
+   * * [XMLHttpRequest.timeout](https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest#xmlhttprequest-timeout)
+   *   from MDN.
+   * * [The timeout attribute](http://www.w3.org/TR/XMLHttpRequest/#the-timeout-attribute)
+   *   from W3C.
+   */
+
+  set timeout(int value) {
+    JS("void", "#.timeout = #", this, value);
+  }
 
   /**
    * [EventTarget] that can hold listeners to track the progress of the request.
    * The events fired will be members of [HttpRequestUploadEvents].
    */
   @Unstable()
-  final HttpRequestUpload upload;
+  HttpRequestUpload get upload => JS("HttpRequestUpload", "#.upload", this);
 
   /**
    * True if cross-site requests should use credentials such as cookies
@@ -17731,7 +18553,19 @@
    *
    * This value is ignored for same-site requests.
    */
-  bool withCredentials;
+
+  bool get withCredentials => JS("bool", "#.withCredentials", this);
+
+  /**
+   * True if cross-site requests should use credentials such as cookies
+   * or authorization headers; false otherwise.
+   *
+   * This value is ignored for same-site requests.
+   */
+
+  set withCredentials(bool value) {
+    JS("void", "#.withCredentials = #", this, value);
+  }
 
   /**
    * Stop the current request.
@@ -17944,7 +18778,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory IFrameElement() => JS(
+  factory IFrameElement() => JS<IFrameElement>(
       'returns:IFrameElement;creates:IFrameElement;new:true',
       '#.createElement(#)',
       document,
@@ -17956,34 +18790,74 @@
    */
   IFrameElement.created() : super.created();
 
-  String allow;
+  String get allow => JS("String", "#.allow", this);
 
-  bool allowFullscreen;
+  set allow(String value) {
+    JS("void", "#.allow = #", this, value);
+  }
 
-  bool allowPaymentRequest;
+  bool get allowFullscreen => JS("bool", "#.allowFullscreen", this);
 
-  WindowBase get contentWindow =>
+  set allowFullscreen(bool value) {
+    JS("void", "#.allowFullscreen = #", this, value);
+  }
+
+  bool get allowPaymentRequest => JS("bool", "#.allowPaymentRequest", this);
+
+  set allowPaymentRequest(bool value) {
+    JS("void", "#.allowPaymentRequest = #", this, value);
+  }
+
+  WindowBase? get contentWindow =>
       _convertNativeToDart_Window(this._get_contentWindow);
   @JSName('contentWindow')
   @Creates('Window|=Object')
   @Returns('Window|=Object')
   final dynamic _get_contentWindow;
 
-  String csp;
+  String get csp => JS("String", "#.csp", this);
 
-  String height;
+  set csp(String value) {
+    JS("void", "#.csp = #", this, value);
+  }
 
-  String name;
+  String get height => JS("String", "#.height", this);
 
-  String referrerPolicy;
+  set height(String value) {
+    JS("void", "#.height = #", this, value);
+  }
 
-  final DomTokenList sandbox;
+  String get name => JS("String", "#.name", this);
 
-  String src;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
-  String srcdoc;
+  String get referrerPolicy => JS("String", "#.referrerPolicy", this);
 
-  String width;
+  set referrerPolicy(String value) {
+    JS("void", "#.referrerPolicy = #", this, value);
+  }
+
+  DomTokenList get sandbox => JS("DomTokenList", "#.sandbox", this);
+
+  String get src => JS("String", "#.src", this);
+
+  set src(String value) {
+    JS("void", "#.src = #", this, value);
+  }
+
+  String get srcdoc => JS("String", "#.srcdoc", this);
+
+  set srcdoc(String value) {
+    JS("void", "#.srcdoc = #", this, value);
+  }
+
+  String get width => JS("String", "#.width", this);
+
+  set width(String value) {
+    JS("void", "#.width = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -17996,7 +18870,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool didTimeout;
+  bool get didTimeout => JS("bool", "#.didTimeout", this);
 
   double timeRemaining() native;
 }
@@ -18018,9 +18892,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int height;
+  int get height => JS("int", "#.height", this);
 
-  final int width;
+  int get width => JS("int", "#.width", this);
 
   void close() native;
 }
@@ -18035,9 +18909,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final CanvasElement canvas;
+  CanvasElement get canvas => JS("CanvasElement", "#.canvas", this);
 
-  void transferFromImageBitmap(ImageBitmap bitmap) native;
+  void transferFromImageBitmap(ImageBitmap? bitmap) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -18056,7 +18930,7 @@
   static ImageCapture _create_1(track) =>
       JS('ImageCapture', 'new ImageCapture(#)', track);
 
-  final MediaStreamTrack track;
+  MediaStreamTrack get track => JS("MediaStreamTrack", "#.track", this);
 
   Future<PhotoCapabilities> getPhotoCapabilities() =>
       promiseToFuture<PhotoCapabilities>(
@@ -18073,7 +18947,7 @@
     return promiseToFuture(JS("", "#.setOptions(#)", this, photoSettings_dict));
   }
 
-  Future<Blob> takePhoto([Map photoSettings]) {
+  Future<Blob> takePhoto([Map? photoSettings]) {
     var photoSettings_dict = null;
     if (photoSettings != null) {
       photoSettings_dict = convertDartToNative_Dictionary(photoSettings);
@@ -18093,7 +18967,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ImageData(data_OR_sw, int sh_OR_sw, [int sh]) {
+  factory ImageData(data_OR_sw, int sh_OR_sw, [int? sh]) {
     if ((sh_OR_sw is int) && (data_OR_sw is int) && sh == null) {
       return ImageData._create_1(data_OR_sw, sh_OR_sw);
     }
@@ -18114,11 +18988,11 @@
 
   @Creates('NativeUint8ClampedList')
   @Returns('NativeUint8ClampedList')
-  final Uint8ClampedList data;
+  Uint8ClampedList get data => JS("Uint8ClampedList", "#.data", this);
 
-  final int height;
+  int get height => JS("int", "#.height", this);
 
-  final int width;
+  int get width => JS("int", "#.width", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -18131,9 +19005,12 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ImageElement({String src, int width, int height}) {
-    ImageElement e = JS('returns:ImageElement;creates:ImageElement;new:true',
-        '#.createElement(#)', document, "img");
+  factory ImageElement({String? src, int? width, int? height}) {
+    ImageElement e = JS<ImageElement>(
+        'returns:ImageElement;creates:ImageElement;new:true',
+        '#.createElement(#)',
+        document,
+        "img");
     if (src != null) e.src = src;
     if (width != null) e.width = width;
     if (height != null) e.height = height;
@@ -18146,35 +19023,75 @@
    */
   ImageElement.created() : super.created();
 
-  String alt;
+  String get alt => JS("String", "#.alt", this);
 
-  String async;
+  set alt(String value) {
+    JS("void", "#.alt = #", this, value);
+  }
 
-  final bool complete;
+  String get async => JS("String", "#.async", this);
 
-  String crossOrigin;
+  set async(String value) {
+    JS("void", "#.async = #", this, value);
+  }
 
-  final String currentSrc;
+  bool get complete => JS("bool", "#.complete", this);
 
-  int height;
+  String? crossOrigin;
 
-  bool isMap;
+  String get currentSrc => JS("String", "#.currentSrc", this);
 
-  final int naturalHeight;
+  int get height => JS("int", "#.height", this);
 
-  final int naturalWidth;
+  set height(int value) {
+    JS("void", "#.height = #", this, value);
+  }
 
-  String referrerPolicy;
+  bool get isMap => JS("bool", "#.isMap", this);
 
-  String sizes;
+  set isMap(bool value) {
+    JS("void", "#.isMap = #", this, value);
+  }
 
-  String src;
+  int get naturalHeight => JS("int", "#.naturalHeight", this);
 
-  String srcset;
+  int get naturalWidth => JS("int", "#.naturalWidth", this);
 
-  String useMap;
+  String get referrerPolicy => JS("String", "#.referrerPolicy", this);
 
-  int width;
+  set referrerPolicy(String value) {
+    JS("void", "#.referrerPolicy = #", this, value);
+  }
+
+  String get sizes => JS("String", "#.sizes", this);
+
+  set sizes(String value) {
+    JS("void", "#.sizes = #", this, value);
+  }
+
+  String get src => JS("String", "#.src", this);
+
+  set src(String value) {
+    JS("void", "#.src = #", this, value);
+  }
+
+  String get srcset => JS("String", "#.srcset", this);
+
+  set srcset(String value) {
+    JS("void", "#.srcset = #", this, value);
+  }
+
+  String get useMap => JS("String", "#.useMap", this);
+
+  set useMap(String value) {
+    JS("void", "#.useMap = #", this, value);
+  }
+
+  int get width => JS("int", "#.width", this);
+
+  set width(int value) {
+    JS("void", "#.width = #", this, value);
+  }
 
   Future decode() => promiseToFuture(JS("", "#.decode()", this));
 }
@@ -18189,7 +19106,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory InputDeviceCapabilities([Map deviceInitDict]) {
+  factory InputDeviceCapabilities([Map? deviceInitDict]) {
     if (deviceInitDict != null) {
       var deviceInitDict_1 = convertDartToNative_Dictionary(deviceInitDict);
       return InputDeviceCapabilities._create_1(deviceInitDict_1);
@@ -18203,7 +19120,7 @@
   static InputDeviceCapabilities _create_2() =>
       JS('InputDeviceCapabilities', 'new InputDeviceCapabilities()');
 
-  final bool firesTouchEvents;
+  bool get firesTouchEvents => JS("bool", "#.firesTouchEvents", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -18233,7 +19150,7 @@
         ImageButtonInputElement,
         ResetButtonInputElement,
         ButtonInputElement {
-  factory InputElement({String type}) {
+  factory InputElement({String? type}) {
     InputElement e = document.createElement("input");
     if (type != null) {
       try {
@@ -18255,95 +19172,231 @@
    */
   InputElement.created() : super.created();
 
-  String accept;
+  String get accept => JS("String", "#.accept", this);
 
-  String alt;
+  set accept(String value) {
+    JS("void", "#.accept = #", this, value);
+  }
 
-  String autocapitalize;
+  String get alt => JS("String", "#.alt", this);
 
-  String autocomplete;
+  set alt(String value) {
+    JS("void", "#.alt = #", this, value);
+  }
 
-  bool autofocus;
+  String get autocapitalize => JS("String", "#.autocapitalize", this);
 
-  String capture;
+  set autocapitalize(String value) {
+    JS("void", "#.autocapitalize = #", this, value);
+  }
 
-  bool checked;
+  String get autocomplete => JS("String", "#.autocomplete", this);
 
-  bool defaultChecked;
+  set autocomplete(String value) {
+    JS("void", "#.autocomplete = #", this, value);
+  }
 
-  String defaultValue;
+  bool get autofocus => JS("bool", "#.autofocus", this);
 
-  String dirName;
+  set autofocus(bool value) {
+    JS("void", "#.autofocus = #", this, value);
+  }
 
-  bool disabled;
+  String get capture => JS("String", "#.capture", this);
+
+  set capture(String value) {
+    JS("void", "#.capture = #", this, value);
+  }
+
+  bool get checked => JS("bool", "#.checked", this);
+
+  set checked(bool value) {
+    JS("void", "#.checked = #", this, value);
+  }
+
+  bool get defaultChecked => JS("bool", "#.defaultChecked", this);
+
+  set defaultChecked(bool value) {
+    JS("void", "#.defaultChecked = #", this, value);
+  }
+
+  String get defaultValue => JS("String", "#.defaultValue", this);
+
+  set defaultValue(String value) {
+    JS("void", "#.defaultValue = #", this, value);
+  }
+
+  String get dirName => JS("String", "#.dirName", this);
+
+  set dirName(String value) {
+    JS("void", "#.dirName = #", this, value);
+  }
+
+  bool get disabled => JS("bool", "#.disabled", this);
+
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
 
   @Returns('FileList|Null')
   @Creates('FileList')
-  List<File> files;
+  List<File>? files;
 
-  final FormElement form;
+  final FormElement? form;
 
-  String formAction;
+  String get formAction => JS("String", "#.formAction", this);
 
-  String formEnctype;
+  set formAction(String value) {
+    JS("void", "#.formAction = #", this, value);
+  }
 
-  String formMethod;
+  String get formEnctype => JS("String", "#.formEnctype", this);
 
-  bool formNoValidate;
+  set formEnctype(String value) {
+    JS("void", "#.formEnctype = #", this, value);
+  }
 
-  String formTarget;
+  String get formMethod => JS("String", "#.formMethod", this);
 
-  int height;
+  set formMethod(String value) {
+    JS("void", "#.formMethod = #", this, value);
+  }
 
-  bool incremental;
+  bool get formNoValidate => JS("bool", "#.formNoValidate", this);
 
-  bool indeterminate;
+  set formNoValidate(bool value) {
+    JS("void", "#.formNoValidate = #", this, value);
+  }
+
+  String get formTarget => JS("String", "#.formTarget", this);
+
+  set formTarget(String value) {
+    JS("void", "#.formTarget = #", this, value);
+  }
+
+  int get height => JS("int", "#.height", this);
+
+  set height(int value) {
+    JS("void", "#.height = #", this, value);
+  }
+
+  bool get incremental => JS("bool", "#.incremental", this);
+
+  set incremental(bool value) {
+    JS("void", "#.incremental = #", this, value);
+  }
+
+  bool get indeterminate => JS("bool", "#.indeterminate", this);
+
+  set indeterminate(bool value) {
+    JS("void", "#.indeterminate = #", this, value);
+  }
 
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  final List<Node> labels;
+  List<Node> get labels => JS("NodeList", "#.labels", this);
 
-  final HtmlElement list;
+  final HtmlElement? list;
 
-  String max;
+  String get max => JS("String", "#.max", this);
 
-  int maxLength;
+  set max(String value) {
+    JS("void", "#.max = #", this, value);
+  }
 
-  String min;
+  int get maxLength => JS("int", "#.maxLength", this);
 
-  int minLength;
+  set maxLength(int value) {
+    JS("void", "#.maxLength = #", this, value);
+  }
 
-  bool multiple;
+  String get min => JS("String", "#.min", this);
 
-  String name;
+  set min(String value) {
+    JS("void", "#.min = #", this, value);
+  }
 
-  String pattern;
+  int get minLength => JS("int", "#.minLength", this);
 
-  String placeholder;
+  set minLength(int value) {
+    JS("void", "#.minLength = #", this, value);
+  }
 
-  bool readOnly;
+  bool get multiple => JS("bool", "#.multiple", this);
 
-  bool required;
+  set multiple(bool value) {
+    JS("void", "#.multiple = #", this, value);
+  }
 
-  String selectionDirection;
+  String get name => JS("String", "#.name", this);
 
-  int selectionEnd;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
-  int selectionStart;
+  String get pattern => JS("String", "#.pattern", this);
 
-  int size;
+  set pattern(String value) {
+    JS("void", "#.pattern = #", this, value);
+  }
 
-  String src;
+  String get placeholder => JS("String", "#.placeholder", this);
 
-  String step;
+  set placeholder(String value) {
+    JS("void", "#.placeholder = #", this, value);
+  }
 
-  String type;
+  bool get readOnly => JS("bool", "#.readOnly", this);
 
-  final String validationMessage;
+  set readOnly(bool value) {
+    JS("void", "#.readOnly = #", this, value);
+  }
 
-  final ValidityState validity;
+  bool get required => JS("bool", "#.required", this);
 
-  String value;
+  set required(bool value) {
+    JS("void", "#.required = #", this, value);
+  }
+
+  String? selectionDirection;
+
+  int? selectionEnd;
+
+  int? selectionStart;
+
+  int get size => JS("int", "#.size", this);
+
+  set size(int value) {
+    JS("void", "#.size = #", this, value);
+  }
+
+  String get src => JS("String", "#.src", this);
+
+  set src(String value) {
+    JS("void", "#.src = #", this, value);
+  }
+
+  String get step => JS("String", "#.step", this);
+
+  set step(String value) {
+    JS("void", "#.step = #", this, value);
+  }
+
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
+
+  String get validationMessage => JS("String", "#.validationMessage", this);
+
+  ValidityState get validity => JS("ValidityState", "#.validity", this);
+
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
 
   DateTime get valueAsDate =>
       convertNativeToDart_DateTime(this._get_valueAsDate);
@@ -18355,25 +19408,40 @@
     this._set_valueAsDate = convertDartToNative_DateTime(value);
   }
 
-  set _set_valueAsDate(/*dynamic*/ value) {
+  set _set_valueAsDate(/*dynamic?*/ value) {
     JS("void", "#.valueAsDate = #", this, value);
   }
 
-  num valueAsNumber;
+  num get valueAsNumber => JS("num", "#.valueAsNumber", this);
+
+  set valueAsNumber(num value) {
+    JS("void", "#.valueAsNumber = #", this, value);
+  }
 
   @JSName('webkitEntries')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final List<Entry> entries;
+  List<Entry> get entries => JS("List<Entry>", "#.webkitEntries", this);
 
   @JSName('webkitdirectory')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  bool directory;
+  bool get directory => JS("bool", "#.webkitdirectory", this);
 
-  int width;
+  @JSName('webkitdirectory')
+  @SupportedBrowser(SupportedBrowser.CHROME)
+  @SupportedBrowser(SupportedBrowser.SAFARI)
+  set directory(bool value) {
+    JS("void", "#.webkitdirectory = #", this, value);
+  }
 
-  final bool willValidate;
+  int get width => JS("int", "#.width", this);
+
+  set width(int value) {
+    JS("void", "#.width = #", this, value);
+  }
+
+  bool get willValidate => JS("bool", "#.willValidate", this);
 
   bool checkValidity() native;
 
@@ -18384,13 +19452,13 @@
   void setCustomValidity(String error) native;
 
   void setRangeText(String replacement,
-      {int start, int end, String selectionMode}) native;
+      {int? start, int? end, String? selectionMode}) native;
 
-  void setSelectionRange(int start, int end, [String direction]) native;
+  void setSelectionRange(int start, int end, [String? direction]) native;
 
-  void stepDown([int n]) native;
+  void stepDown([int? n]) native;
 
-  void stepUp([int n]) native;
+  void stepUp([int? n]) native;
 }
 
 // Interfaces representing the InputElement APIs which are supported
@@ -18477,7 +19545,7 @@
 
   String dirName;
 
-  Element get list;
+  Element? get list;
 
   /// Returns true if this input type is supported on the current platform.
   static bool get supported {
@@ -18493,7 +19561,7 @@
 
   String dirName;
 
-  Element get list;
+  Element? get list;
 }
 
 /**
@@ -18508,7 +19576,7 @@
 abstract class UrlInputElement implements TextInputElementBase {
   factory UrlInputElement() => new InputElement(type: 'url');
 
-  Element get list;
+  Element? get list;
 
   /// Returns true if this input type is supported on the current platform.
   static bool get supported {
@@ -18531,7 +19599,7 @@
 abstract class TelephoneInputElement implements TextInputElementBase {
   factory TelephoneInputElement() => new InputElement(type: 'tel');
 
-  Element get list;
+  Element? get list;
 
   /// Returns true if this input type is supported on the current platform.
   static bool get supported {
@@ -18555,7 +19623,7 @@
 
   bool autofocus;
 
-  Element get list;
+  Element? get list;
 
   int maxLength;
 
@@ -18588,7 +19656,7 @@
  * Base interface for all input element types which involve ranges.
  */
 abstract class RangeInputElementBase implements InputElementBase {
-  Element get list;
+  Element? get list;
 
   String max;
 
@@ -18861,7 +19929,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory InstallEvent(String type, [Map eventInitDict]) {
+  factory InstallEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return InstallEvent._create_1(type, eventInitDict_1);
@@ -18894,7 +19962,7 @@
   }
 
   factory IntersectionObserver(IntersectionObserverCallback callback,
-      [Map options]) {
+      [Map? options]) {
     if (options != null) {
       var callback_1 = convertDartClosureToJS(callback, 2);
       var options_2 = convertDartToNative_Dictionary(options);
@@ -18911,11 +19979,11 @@
   static IntersectionObserver _create_2(callback) =>
       JS('IntersectionObserver', 'new IntersectionObserver(#)', callback);
 
-  final Element root;
+  final Element? root;
 
-  final String rootMargin;
+  String get rootMargin => JS("String", "#.rootMargin", this);
 
-  final List<num> thresholds;
+  List<num> get thresholds => JS("List<num>", "#.thresholds", this);
 
   void disconnect() native;
 
@@ -18944,19 +20012,21 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final DomRectReadOnly boundingClientRect;
+  DomRectReadOnly get boundingClientRect =>
+      JS("DomRectReadOnly", "#.boundingClientRect", this);
 
-  final num intersectionRatio;
+  num get intersectionRatio => JS("num", "#.intersectionRatio", this);
 
-  final DomRectReadOnly intersectionRect;
+  DomRectReadOnly get intersectionRect =>
+      JS("DomRectReadOnly", "#.intersectionRect", this);
 
-  final bool isIntersecting;
+  bool get isIntersecting => JS("bool", "#.isIntersecting", this);
 
-  final DomRectReadOnly rootBounds;
+  final DomRectReadOnly? rootBounds;
 
-  final Element target;
+  Element get target => JS("Element", "#.target", this);
 
-  final num time;
+  num get time => JS("num", "#.time", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -18969,11 +20039,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int lineNumber;
+  int get lineNumber => JS("int", "#.lineNumber", this);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 
-  final String sourceFile;
+  String get sourceFile => JS("String", "#.sourceFile", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19063,7 +20133,7 @@
 
   int get which => _which;
 
-  factory KeyboardEvent._(String type, [Map eventInitDict]) {
+  factory KeyboardEvent._(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return KeyboardEvent._create_1(type, eventInitDict_1);
@@ -19083,29 +20153,29 @@
 
   static const int DOM_KEY_LOCATION_STANDARD = 0x00;
 
-  final bool altKey;
+  bool get altKey => JS("bool", "#.altKey", this);
 
   @JSName('charCode')
-  final int _charCode;
+  int get _charCode => JS("int", "#.charCode", this);
 
-  final String code;
+  String get code => JS("String", "#.code", this);
 
-  final bool ctrlKey;
+  bool get ctrlKey => JS("bool", "#.ctrlKey", this);
 
-  final bool isComposing;
+  bool get isComposing => JS("bool", "#.isComposing", this);
 
-  final String key;
+  String get key => JS("String", "#.key", this);
 
   @JSName('keyCode')
-  final int _keyCode;
+  int get _keyCode => JS("int", "#.keyCode", this);
 
-  final int location;
+  int get location => JS("int", "#.location", this);
 
-  final bool metaKey;
+  bool get metaKey => JS("bool", "#.metaKey", this);
 
-  final bool repeat;
+  bool get repeat => JS("bool", "#.repeat", this);
 
-  final bool shiftKey;
+  bool get shiftKey => JS("bool", "#.shiftKey", this);
 
   bool getModifierState(String keyArg) native;
 }
@@ -19120,7 +20190,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory KeyframeEffect(Element target, Object effect, [Object options]) {
+  factory KeyframeEffect(Element? target, Object? effect, [Object? options]) {
     if (options != null) {
       return KeyframeEffect._create_1(target, effect, options);
     }
@@ -19142,8 +20212,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory KeyframeEffectReadOnly(Element target, Object effect,
-      [Object options]) {
+  factory KeyframeEffectReadOnly(Element? target, Object? effect,
+      [Object? options]) {
     if (options != null) {
       return KeyframeEffectReadOnly._create_1(target, effect, options);
     }
@@ -19172,8 +20242,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory LIElement() => JS('returns:LIElement;creates:LIElement;new:true',
-      '#.createElement(#)', document, "li");
+  factory LIElement() => JS<LIElement>(
+      'returns:LIElement;creates:LIElement;new:true',
+      '#.createElement(#)',
+      document,
+      "li");
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -19181,7 +20254,11 @@
    */
   LIElement.created() : super.created();
 
-  int value;
+  int get value => JS("int", "#.value", this);
+
+  set value(int value) {
+    JS("void", "#.value = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19194,7 +20271,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory LabelElement() => JS(
+  factory LabelElement() => JS<LabelElement>(
       'returns:LabelElement;creates:LabelElement;new:true',
       '#.createElement(#)',
       document,
@@ -19206,11 +20283,15 @@
    */
   LabelElement.created() : super.created();
 
-  final HtmlElement control;
+  final HtmlElement? control;
 
-  final FormElement form;
+  final FormElement? form;
 
-  String htmlFor;
+  String get htmlFor => JS("String", "#.htmlFor", this);
+
+  set htmlFor(String value) {
+    JS("void", "#.htmlFor = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19223,7 +20304,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory LegendElement() => JS(
+  factory LegendElement() => JS<LegendElement>(
       'returns:LegendElement;creates:LegendElement;new:true',
       '#.createElement(#)',
       document,
@@ -19235,7 +20316,7 @@
    */
   LegendElement.created() : super.created();
 
-  final FormElement form;
+  final FormElement? form;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19248,7 +20329,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory LinearAccelerationSensor([Map sensorOptions]) {
+  factory LinearAccelerationSensor([Map? sensorOptions]) {
     if (sensorOptions != null) {
       var sensorOptions_1 = convertDartToNative_Dictionary(sensorOptions);
       return LinearAccelerationSensor._create_1(sensorOptions_1);
@@ -19273,7 +20354,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory LinkElement() => JS(
+  factory LinkElement() => JS<LinkElement>(
       'returns:LinkElement;creates:LinkElement;new:true',
       '#.createElement(#)',
       document,
@@ -19285,35 +20366,75 @@
    */
   LinkElement.created() : super.created();
 
-  String as;
+  String get as => JS("String", "#.as", this);
 
-  String crossOrigin;
+  set as(String value) {
+    JS("void", "#.as = #", this, value);
+  }
 
-  bool disabled;
+  String? crossOrigin;
 
-  String href;
+  bool get disabled => JS("bool", "#.disabled", this);
 
-  String hreflang;
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
 
-  final Document import;
+  String get href => JS("String", "#.href", this);
 
-  String integrity;
+  set href(String value) {
+    JS("void", "#.href = #", this, value);
+  }
 
-  String media;
+  String get hreflang => JS("String", "#.hreflang", this);
 
-  String referrerPolicy;
+  set hreflang(String value) {
+    JS("void", "#.hreflang = #", this, value);
+  }
 
-  String rel;
+  final Document? import;
 
-  final DomTokenList relList;
+  String get integrity => JS("String", "#.integrity", this);
 
-  String scope;
+  set integrity(String value) {
+    JS("void", "#.integrity = #", this, value);
+  }
 
-  final StyleSheet sheet;
+  String get media => JS("String", "#.media", this);
 
-  final DomTokenList sizes;
+  set media(String value) {
+    JS("void", "#.media = #", this, value);
+  }
 
-  String type;
+  String get referrerPolicy => JS("String", "#.referrerPolicy", this);
+
+  set referrerPolicy(String value) {
+    JS("void", "#.referrerPolicy = #", this, value);
+  }
+
+  String get rel => JS("String", "#.rel", this);
+
+  set rel(String value) {
+    JS("void", "#.rel = #", this, value);
+  }
+
+  DomTokenList get relList => JS("DomTokenList", "#.relList", this);
+
+  String get scope => JS("String", "#.scope", this);
+
+  set scope(String value) {
+    JS("void", "#.scope = #", this, value);
+  }
+
+  final StyleSheet? sheet;
+
+  DomTokenList get sizes => JS("DomTokenList", "#.sizes", this);
+
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 
   /// Checks if HTML imports are supported on the current platform.
   bool get supportsImport {
@@ -19333,27 +20454,64 @@
 
   @Returns('DomStringList|Null')
   @Creates('DomStringList')
-  final List<String> ancestorOrigins;
+  List<String> get ancestorOrigins =>
+      JS("DomStringList", "#.ancestorOrigins", this);
 
-  String hash;
+  String get hash => JS("String", "#.hash", this);
 
-  String host;
+  set hash(String value) {
+    JS("void", "#.hash = #", this, value);
+  }
 
-  String hostname;
+  String get host => JS("String", "#.host", this);
 
-  String href;
+  set host(String value) {
+    JS("void", "#.host = #", this, value);
+  }
 
-  String pathname;
+  String get hostname => JS("String", "#.hostname", this);
 
-  String port;
+  set hostname(String value) {
+    JS("void", "#.hostname = #", this, value);
+  }
 
-  String protocol;
+  String get href => JS("String", "#.href", this);
 
-  String search;
+  set href(String value) {
+    JS("void", "#.href = #", this, value);
+  }
 
-  TrustedUrl trustedHref;
+  String get pathname => JS("String", "#.pathname", this);
 
-  void assign([String url]) native;
+  set pathname(String value) {
+    JS("void", "#.pathname = #", this, value);
+  }
+
+  String get port => JS("String", "#.port", this);
+
+  set port(String value) {
+    JS("void", "#.port = #", this, value);
+  }
+
+  String get protocol => JS("String", "#.protocol", this);
+
+  set protocol(String value) {
+    JS("void", "#.protocol = #", this, value);
+  }
+
+  String get search => JS("String", "#.search", this);
+
+  set search(String value) {
+    JS("void", "#.search = #", this, value);
+  }
+
+  TrustedUrl get trustedHref => JS("TrustedUrl", "#.trustedHref", this);
+
+  set trustedHref(TrustedUrl value) {
+    JS("void", "#.trustedHref = #", this, value);
+  }
+
+  void assign([String? url]) native;
 
   void reload() native;
 
@@ -19379,7 +20537,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory Magnetometer([Map sensorOptions]) {
+  factory Magnetometer([Map? sensorOptions]) {
     if (sensorOptions != null) {
       var sensorOptions_1 = convertDartToNative_Dictionary(sensorOptions);
       return Magnetometer._create_1(sensorOptions_1);
@@ -19407,8 +20565,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory MapElement() => JS('returns:MapElement;creates:MapElement;new:true',
-      '#.createElement(#)', document, "map");
+  factory MapElement() => JS<MapElement>(
+      'returns:MapElement;creates:MapElement;new:true',
+      '#.createElement(#)',
+      document,
+      "map");
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -19418,9 +20579,13 @@
 
   @Returns('HtmlCollection|Null')
   @Creates('HtmlCollection')
-  final List<Node> areas;
+  List<Node> get areas => JS("HtmlCollection", "#.areas", this);
 
-  String name;
+  String get name => JS("String", "#.name", this);
+
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19456,11 +20621,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool powerEfficient;
+  bool get powerEfficient => JS("bool", "#.powerEfficient", this);
 
-  final bool smooth;
+  bool get smooth => JS("bool", "#.smooth", this);
 
-  final bool supported;
+  bool get supported => JS("bool", "#.supported", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19473,13 +20638,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String deviceId;
+  String get deviceId => JS("String", "#.deviceId", this);
 
-  final String groupId;
+  String get groupId => JS("String", "#.groupId", this);
 
-  final String kind;
+  String get kind => JS("String", "#.kind", this);
 
-  final String label;
+  String get label => JS("String", "#.label", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19538,84 +20703,138 @@
 
   static const int NETWORK_NO_SOURCE = 3;
 
-  final AudioTrackList audioTracks;
+  AudioTrackList get audioTracks => JS("AudioTrackList", "#.audioTracks", this);
 
-  bool autoplay;
+  bool get autoplay => JS("bool", "#.autoplay", this);
 
-  final TimeRanges buffered;
+  set autoplay(bool value) {
+    JS("void", "#.autoplay = #", this, value);
+  }
 
-  bool controls;
+  TimeRanges get buffered => JS("TimeRanges", "#.buffered", this);
 
-  final DomTokenList controlsList;
+  bool get controls => JS("bool", "#.controls", this);
 
-  String crossOrigin;
+  set controls(bool value) {
+    JS("void", "#.controls = #", this, value);
+  }
 
-  final String currentSrc;
+  DomTokenList get controlsList => JS("DomTokenList", "#.controlsList", this);
 
-  num currentTime;
+  String? crossOrigin;
 
-  bool defaultMuted;
+  String get currentSrc => JS("String", "#.currentSrc", this);
 
-  num defaultPlaybackRate;
+  num get currentTime => JS("num", "#.currentTime", this);
 
-  bool disableRemotePlayback;
+  set currentTime(num value) {
+    JS("void", "#.currentTime = #", this, value);
+  }
 
-  final num duration;
+  bool get defaultMuted => JS("bool", "#.defaultMuted", this);
 
-  final bool ended;
+  set defaultMuted(bool value) {
+    JS("void", "#.defaultMuted = #", this, value);
+  }
 
-  final MediaError error;
+  num get defaultPlaybackRate => JS("num", "#.defaultPlaybackRate", this);
 
-  bool loop;
+  set defaultPlaybackRate(num value) {
+    JS("void", "#.defaultPlaybackRate = #", this, value);
+  }
 
-  final MediaKeys mediaKeys;
+  bool get disableRemotePlayback => JS("bool", "#.disableRemotePlayback", this);
 
-  bool muted;
+  set disableRemotePlayback(bool value) {
+    JS("void", "#.disableRemotePlayback = #", this, value);
+  }
 
-  final int networkState;
+  num get duration => JS("num", "#.duration", this);
 
-  final bool paused;
+  bool get ended => JS("bool", "#.ended", this);
 
-  num playbackRate;
+  final MediaError? error;
 
-  final TimeRanges played;
+  bool get loop => JS("bool", "#.loop", this);
 
-  String preload;
+  set loop(bool value) {
+    JS("void", "#.loop = #", this, value);
+  }
 
-  final int readyState;
+  MediaKeys get mediaKeys => JS("MediaKeys", "#.mediaKeys", this);
 
-  final RemotePlayback remote;
+  bool get muted => JS("bool", "#.muted", this);
 
-  final TimeRanges seekable;
+  set muted(bool value) {
+    JS("void", "#.muted = #", this, value);
+  }
 
-  final bool seeking;
+  int get networkState => JS("int", "#.networkState", this);
 
-  final String sinkId;
+  bool get paused => JS("bool", "#.paused", this);
 
-  String src;
+  num get playbackRate => JS("num", "#.playbackRate", this);
 
-  MediaStream srcObject;
+  set playbackRate(num value) {
+    JS("void", "#.playbackRate = #", this, value);
+  }
 
-  final TextTrackList textTracks;
+  TimeRanges get played => JS("TimeRanges", "#.played", this);
 
-  final VideoTrackList videoTracks;
+  String get preload => JS("String", "#.preload", this);
 
-  num volume;
+  set preload(String value) {
+    JS("void", "#.preload = #", this, value);
+  }
+
+  int get readyState => JS("int", "#.readyState", this);
+
+  RemotePlayback get remote => JS("RemotePlayback", "#.remote", this);
+
+  TimeRanges get seekable => JS("TimeRanges", "#.seekable", this);
+
+  bool get seeking => JS("bool", "#.seeking", this);
+
+  String get sinkId => JS("String", "#.sinkId", this);
+
+  String get src => JS("String", "#.src", this);
+
+  set src(String value) {
+    JS("void", "#.src = #", this, value);
+  }
+
+  MediaStream get srcObject => JS("MediaStream", "#.srcObject", this);
+
+  set srcObject(MediaStream value) {
+    JS("void", "#.srcObject = #", this, value);
+  }
+
+  TextTrackList get textTracks => JS("TextTrackList", "#.textTracks", this);
+
+  VideoTrackList get videoTracks => JS("VideoTrackList", "#.videoTracks", this);
+
+  num get volume => JS("num", "#.volume", this);
+
+  set volume(num value) {
+    JS("void", "#.volume = #", this, value);
+  }
 
   @JSName('webkitAudioDecodedByteCount')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final int audioDecodedByteCount;
+  int get audioDecodedByteCount =>
+      JS("int", "#.webkitAudioDecodedByteCount", this);
 
   @JSName('webkitVideoDecodedByteCount')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final int videoDecodedByteCount;
+  int get videoDecodedByteCount =>
+      JS("int", "#.webkitVideoDecodedByteCount", this);
 
-  TextTrack addTextTrack(String kind, [String label, String language]) native;
+  TextTrack addTextTrack(String kind, [String? label, String? language]) native;
 
   @Unstable()
-  String canPlayType(String type, [String keySystem]) native;
+  String canPlayType(String type, [String? keySystem]) native;
 
   MediaStream captureStream() native;
 
@@ -19625,7 +20844,7 @@
 
   Future play() => promiseToFuture(JS("", "#.play()", this));
 
-  Future setMediaKeys(MediaKeys mediaKeys) =>
+  Future setMediaKeys(MediaKeys? mediaKeys) =>
       promiseToFuture(JS("", "#.setMediaKeys(#)", this, mediaKeys));
 
   Future setSinkId(String sinkId) =>
@@ -19642,7 +20861,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory MediaEncryptedEvent(String type, [Map eventInitDict]) {
+  factory MediaEncryptedEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return MediaEncryptedEvent._create_1(type, eventInitDict_1);
@@ -19657,9 +20876,9 @@
   static MediaEncryptedEvent _create_2(type) =>
       JS('MediaEncryptedEvent', 'new MediaEncryptedEvent(#)', type);
 
-  final ByteBuffer initData;
+  final ByteBuffer? initData;
 
-  final String initDataType;
+  String get initDataType => JS("String", "#.initDataType", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19681,9 +20900,9 @@
 
   static const int MEDIA_ERR_SRC_NOT_SUPPORTED = 4;
 
-  final int code;
+  int get code => JS("int", "#.code", this);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19706,9 +20925,9 @@
       type,
       eventInitDict);
 
-  final ByteBuffer message;
+  ByteBuffer get message => JS("ByteBuffer", "#.message", this);
 
-  final String messageType;
+  String get messageType => JS("String", "#.messageType", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19724,13 +20943,14 @@
   static const EventStreamProvider<MessageEvent> messageEvent =
       const EventStreamProvider<MessageEvent>('message');
 
-  Future<void> get closed => promiseToFuture<void>(JS("", "#.closed", this));
+  Future get closed => JS("Future", "#.closed", this);
 
-  final num expiration;
+  num get expiration => JS("num", "#.expiration", this);
 
-  final MediaKeyStatusMap keyStatuses;
+  MediaKeyStatusMap get keyStatuses =>
+      JS("MediaKeyStatusMap", "#.keyStatuses", this);
 
-  final String sessionId;
+  String get sessionId => JS("String", "#.sessionId", this);
 
   Future close() => promiseToFuture(JS("", "#.close()", this));
 
@@ -19759,7 +20979,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int size;
+  int get size => JS("int", "#.size", this);
 
   Object get(/*BufferSource*/ keyId) native;
 
@@ -19776,7 +20996,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String keySystem;
+  String get keySystem => JS("String", "#.keySystem", this);
 
   Future createMediaKeys() =>
       promiseToFuture(JS("", "#.createMediaKeys()", this));
@@ -19800,7 +21020,7 @@
   }
 
   @JSName('createSession')
-  MediaKeySession _createSession([String sessionType]) native;
+  MediaKeySession _createSession([String? sessionType]) native;
 
   Future getStatusForPolicy(MediaKeysPolicy policy) =>
       promiseToFuture(JS("", "#.getStatusForPolicy(#)", this, policy));
@@ -19827,7 +21047,7 @@
   static MediaKeysPolicy _create_1(init) =>
       JS('MediaKeysPolicy', 'new MediaKeysPolicy(#)', init);
 
-  final String minHdcpVersion;
+  String get minHdcpVersion => JS("String", "#.minHdcpVersion", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19841,9 +21061,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
-  String mediaText;
+  String? mediaText;
 
   void appendMedium(String medium) native;
 
@@ -19862,7 +21082,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory MediaMetadata([Map metadata]) {
+  factory MediaMetadata([Map? metadata]) {
     if (metadata != null) {
       var metadata_1 = convertDartToNative_Dictionary(metadata);
       return MediaMetadata._create_1(metadata_1);
@@ -19874,13 +21094,29 @@
   static MediaMetadata _create_2() =>
       JS('MediaMetadata', 'new MediaMetadata()');
 
-  String album;
+  String get album => JS("String", "#.album", this);
 
-  String artist;
+  set album(String value) {
+    JS("void", "#.album = #", this, value);
+  }
 
-  List artwork;
+  String get artist => JS("String", "#.artist", this);
 
-  String title;
+  set artist(String value) {
+    JS("void", "#.artist = #", this, value);
+  }
+
+  List get artwork => JS("List", "#.artwork", this);
+
+  set artwork(List value) {
+    JS("void", "#.artwork = #", this, value);
+  }
+
+  String get title => JS("String", "#.title", this);
+
+  set title(String value) {
+    JS("void", "#.title = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19897,13 +21133,13 @@
   static const EventStreamProvider<Event> changeEvent =
       const EventStreamProvider<Event>('change');
 
-  final bool matches;
+  bool get matches => JS("bool", "#.matches", this);
 
-  final String media;
+  String get media => JS("String", "#.media", this);
 
-  void addListener(EventListener listener) native;
+  void addListener(EventListener? listener) native;
 
-  void removeListener(EventListener listener) native;
+  void removeListener(EventListener? listener) native;
 
   Stream<Event> get onChange => changeEvent.forTarget(this);
 }
@@ -19918,7 +21154,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory MediaQueryListEvent(String type, [Map eventInitDict]) {
+  factory MediaQueryListEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return MediaQueryListEvent._create_1(type, eventInitDict_1);
@@ -19933,9 +21169,9 @@
   static MediaQueryListEvent _create_2(type) =>
       JS('MediaQueryListEvent', 'new MediaQueryListEvent(#)', type);
 
-  final bool matches;
+  bool get matches => JS("bool", "#.matches", this);
 
-  final String media;
+  String get media => JS("String", "#.media", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -19954,7 +21190,7 @@
   static const EventStreamProvider<Event> pauseEvent =
       const EventStreamProvider<Event>('pause');
 
-  factory MediaRecorder(MediaStream stream, [Map options]) {
+  factory MediaRecorder(MediaStream stream, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return MediaRecorder._create_1(stream, options_1);
@@ -19966,15 +21202,15 @@
   static MediaRecorder _create_2(stream) =>
       JS('MediaRecorder', 'new MediaRecorder(#)', stream);
 
-  final int audioBitsPerSecond;
+  int get audioBitsPerSecond => JS("int", "#.audioBitsPerSecond", this);
 
-  final String mimeType;
+  String get mimeType => JS("String", "#.mimeType", this);
 
-  final String state;
+  String get state => JS("String", "#.state", this);
 
-  final MediaStream stream;
+  MediaStream get stream => JS("MediaStream", "#.stream", this);
 
-  final int videoBitsPerSecond;
+  int get videoBitsPerSecond => JS("int", "#.videoBitsPerSecond", this);
 
   static bool isTypeSupported(String type) native;
 
@@ -19984,7 +21220,7 @@
 
   void resume() native;
 
-  void start([int timeslice]) native;
+  void start([int? timeslice]) native;
 
   void stop() native;
 
@@ -20003,11 +21239,15 @@
     throw new UnsupportedError("Not supported");
   }
 
-  MediaMetadata metadata;
+  MediaMetadata? metadata;
 
-  String playbackState;
+  String get playbackState => JS("String", "#.playbackState", this);
 
-  void setActionHandler(String action, MediaSessionActionHandler handler)
+  set playbackState(String value) {
+    JS("void", "#.playbackState = #", this, value);
+  }
+
+  void setActionHandler(String action, MediaSessionActionHandler? handler)
       native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
@@ -20028,11 +21268,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num max;
+  num get max => JS("num", "#.max", this);
 
-  final num min;
+  num get min => JS("num", "#.min", this);
 
-  final num step;
+  num get step => JS("num", "#.step", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20055,19 +21295,25 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => JS('bool', '!!(window.MediaSource)');
 
-  final SourceBufferList activeSourceBuffers;
+  SourceBufferList get activeSourceBuffers =>
+      JS("SourceBufferList", "#.activeSourceBuffers", this);
 
-  num duration;
+  num get duration => JS("num", "#.duration", this);
 
-  final String readyState;
+  set duration(num value) {
+    JS("void", "#.duration = #", this, value);
+  }
 
-  final SourceBufferList sourceBuffers;
+  String get readyState => JS("String", "#.readyState", this);
+
+  SourceBufferList get sourceBuffers =>
+      JS("SourceBufferList", "#.sourceBuffers", this);
 
   SourceBuffer addSourceBuffer(String type) native;
 
   void clearLiveSeekableRange() native;
 
-  void endOfStream([String error]) native;
+  void endOfStream([String? error]) native;
 
   static bool isTypeSupported(String type) native;
 
@@ -20123,9 +21369,9 @@
   static MediaStream _create_3(stream_OR_tracks) =>
       JS('MediaStream', 'new MediaStream(#)', stream_OR_tracks);
 
-  final bool active;
+  bool get active => JS("bool", "#.active", this);
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
   void addTrack(MediaStreamTrack track) native;
 
@@ -20179,7 +21425,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory MediaStreamEvent(String type, [Map eventInitDict]) {
+  factory MediaStreamEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return MediaStreamEvent._create_1(type, eventInitDict_1);
@@ -20194,7 +21440,7 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => Device.isEventTypeSupported('MediaStreamEvent');
 
-  final MediaStream stream;
+  final MediaStream? stream;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20235,21 +21481,29 @@
   static const EventStreamProvider<Event> unmuteEvent =
       const EventStreamProvider<Event>('unmute');
 
-  String contentHint;
+  String get contentHint => JS("String", "#.contentHint", this);
 
-  bool enabled;
+  set contentHint(String value) {
+    JS("void", "#.contentHint = #", this, value);
+  }
 
-  final String id;
+  bool get enabled => JS("bool", "#.enabled", this);
 
-  final String kind;
+  set enabled(bool value) {
+    JS("void", "#.enabled = #", this, value);
+  }
 
-  final String label;
+  String get id => JS("String", "#.id", this);
 
-  final bool muted;
+  String get kind => JS("String", "#.kind", this);
 
-  final String readyState;
+  String get label => JS("String", "#.label", this);
 
-  Future applyConstraints([Map constraints]) {
+  bool get muted => JS("bool", "#.muted", this);
+
+  String get readyState => JS("String", "#.readyState", this);
+
+  Future applyConstraints([Map? constraints]) {
     var constraints_dict = null;
     if (constraints != null) {
       constraints_dict = convertDartToNative_Dictionary(constraints);
@@ -20318,7 +21572,7 @@
   static bool get supported =>
       Device.isEventTypeSupported('MediaStreamTrackEvent');
 
-  final MediaStreamTrack track;
+  MediaStreamTrack get track => JS("MediaStreamTrack", "#.track", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20331,11 +21585,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int jsHeapSizeLimit;
+  int get jsHeapSizeLimit => JS("int", "#.jsHeapSizeLimit", this);
 
-  final int totalJSHeapSize;
+  int get totalJSHeapSize => JS("int", "#.totalJSHeapSize", this);
 
-  final int usedJSHeapSize;
+  int get usedJSHeapSize => JS("int", "#.usedJSHeapSize", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20358,7 +21612,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory MenuElement() => JS(
+  factory MenuElement() => JS<MenuElement>(
       'returns:MenuElement;creates:MenuElement;new:true',
       '#.createElement(#)',
       document,
@@ -20395,9 +21649,9 @@
   static MessageChannel _create_1() =>
       JS('MessageChannel', 'new MessageChannel()');
 
-  final MessagePort port1;
+  MessagePort get port1 => JS("MessagePort", "#.port1", this);
 
-  final MessagePort port2;
+  MessagePort get port2 => JS("MessagePort", "#.port2", this);
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20449,7 +21703,7 @@
   @annotation_Returns_SerializedScriptValue
   final dynamic _get_data;
 
-  factory MessageEvent._(String type, [Map eventInitDict]) {
+  factory MessageEvent._(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return MessageEvent._create_1(type, eventInitDict_1);
@@ -20462,21 +21716,21 @@
       JS('MessageEvent', 'new MessageEvent(#)', type);
 
   @Unstable()
-  final String lastEventId;
+  String get lastEventId => JS("String", "#.lastEventId", this);
 
-  final String origin;
+  String get origin => JS("String", "#.origin", this);
 
   @Unstable()
   @Creates('JSExtendableArray')
-  final List<MessagePort> ports;
+  List<MessagePort> get ports => JS("List<MessagePort>", "#.ports", this);
 
-  EventTarget get source => _convertNativeToDart_EventTarget(this._get_source);
+  EventTarget? get source => _convertNativeToDart_EventTarget(this._get_source);
   @JSName('source')
   @Creates('Null')
   @Returns('EventTarget|=Object')
   final dynamic _get_source;
 
-  final String suborigin;
+  String get suborigin => JS("String", "#.suborigin", this);
 
   void _initMessageEvent(
       String typeArg,
@@ -20533,7 +21787,7 @@
 
   void close() native;
 
-  void postMessage(/*any*/ message, [List<Object> transfer]) {
+  void postMessage(/*any*/ message, [List<Object>? transfer]) {
     if (transfer != null) {
       var message_1 = convertDartToNative_SerializedScriptValue(message);
       _postMessage_1(message_1, transfer);
@@ -20567,7 +21821,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory MetaElement() => JS(
+  factory MetaElement() => JS<MetaElement>(
       'returns:MetaElement;creates:MetaElement;new:true',
       '#.createElement(#)',
       document,
@@ -20579,11 +21833,23 @@
    */
   MetaElement.created() : super.created();
 
-  String content;
+  String get content => JS("String", "#.content", this);
 
-  String httpEquiv;
+  set content(String value) {
+    JS("void", "#.content = #", this, value);
+  }
 
-  String name;
+  String get httpEquiv => JS("String", "#.httpEquiv", this);
+
+  set httpEquiv(String value) {
+    JS("void", "#.httpEquiv = #", this, value);
+  }
+
+  String get name => JS("String", "#.name", this);
+
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20602,7 +21868,7 @@
   @Creates('Null')
   final dynamic _get_modificationTime;
 
-  final int size;
+  int get size => JS("int", "#.size", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20626,7 +21892,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory MeterElement() => document.createElement("meter");
+  factory MeterElement() => document.createElement("meter") as MeterElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -20637,22 +21903,46 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('meter');
 
-  num high;
+  num get high => JS("num", "#.high", this);
+
+  set high(num value) {
+    JS("void", "#.high = #", this, value);
+  }
 
   @Unstable()
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  final List<Node> labels;
+  List<Node> get labels => JS("NodeList", "#.labels", this);
 
-  num low;
+  num get low => JS("num", "#.low", this);
 
-  num max;
+  set low(num value) {
+    JS("void", "#.low = #", this, value);
+  }
 
-  num min;
+  num get max => JS("num", "#.max", this);
 
-  num optimum;
+  set max(num value) {
+    JS("void", "#.max = #", this, value);
+  }
 
-  num value;
+  num get min => JS("num", "#.min", this);
+
+  set min(num value) {
+    JS("void", "#.min = #", this, value);
+  }
+
+  num get optimum => JS("num", "#.optimum", this);
+
+  set optimum(num value) {
+    JS("void", "#.optimum = #", this, value);
+  }
+
+  num get value => JS("num", "#.value", this);
+
+  set value(num value) {
+    JS("void", "#.value = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20665,11 +21955,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final MidiInputMap inputs;
+  MidiInputMap get inputs => JS("MidiInputMap", "#.inputs", this);
 
-  final MidiOutputMap outputs;
+  MidiOutputMap get outputs => JS("MidiOutputMap", "#.outputs", this);
 
-  final bool sysexEnabled;
+  bool get sysexEnabled => JS("bool", "#.sysexEnabled", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20682,7 +21972,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory MidiConnectionEvent(String type, [Map eventInitDict]) {
+  factory MidiConnectionEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return MidiConnectionEvent._create_1(type, eventInitDict_1);
@@ -20697,7 +21987,7 @@
   static MidiConnectionEvent _create_2(type) =>
       JS('MidiConnectionEvent', 'new MIDIConnectionEvent(#)', type);
 
-  final MidiPort port;
+  MidiPort get port => JS("MidiPort", "#.port", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20802,7 +22092,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory MidiMessageEvent(String type, [Map eventInitDict]) {
+  factory MidiMessageEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return MidiMessageEvent._create_1(type, eventInitDict_1);
@@ -20814,7 +22104,7 @@
   static MidiMessageEvent _create_2(type) =>
       JS('MidiMessageEvent', 'new MIDIMessageEvent(#)', type);
 
-  final Uint8List data;
+  Uint8List get data => JS("Uint8List", "#.data", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20827,7 +22117,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  void send(Uint8List data, [num timestamp]) native;
+  void send(Uint8List data, [num? timestamp]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -20908,19 +22198,19 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String connection;
+  String get connection => JS("String", "#.connection", this);
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
-  final String manufacturer;
+  String get manufacturer => JS("String", "#.manufacturer", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
-  final String state;
+  String get state => JS("String", "#.state", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
-  final String version;
+  String get version => JS("String", "#.version", this);
 
   Future close() => promiseToFuture(JS("", "#.close()", this));
 
@@ -20937,13 +22227,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String description;
+  String get description => JS("String", "#.description", this);
 
-  final Plugin enabledPlugin;
+  Plugin get enabledPlugin => JS("Plugin", "#.enabledPlugin", this);
 
-  final String suffixes;
+  String get suffixes => JS("String", "#.suffixes", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -21025,9 +22315,17 @@
    */
   ModElement.created() : super.created();
 
-  String cite;
+  String get cite => JS("String", "#.cite", this);
 
-  String dateTime;
+  set cite(String value) {
+    JS("void", "#.cite = #", this, value);
+  }
+
+  String get dateTime => JS("String", "#.dateTime", this);
+
+  set dateTime(String value) {
+    JS("void", "#.dateTime = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -21080,7 +22378,7 @@
     return event;
   }
 
-  factory MouseEvent._(String type, [Map eventInitDict]) {
+  factory MouseEvent._(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return MouseEvent._create_1(type, eventInitDict_1);
@@ -21092,19 +22390,19 @@
   static MouseEvent _create_2(type) =>
       JS('MouseEvent', 'new MouseEvent(#)', type);
 
-  final bool altKey;
+  bool get altKey => JS("bool", "#.altKey", this);
 
-  final int button;
+  int get button => JS("int", "#.button", this);
 
-  final int buttons;
+  int get buttons => JS("int", "#.buttons", this);
 
   @JSName('clientX')
-  final num _clientX;
+  num get _clientX => JS("num", "#.clientX", this);
 
   @JSName('clientY')
-  final num _clientY;
+  num get _clientY => JS("num", "#.clientY", this);
 
-  final bool ctrlKey;
+  bool get ctrlKey => JS("bool", "#.ctrlKey", this);
 
   /**
    * The nonstandard way to access the element that the mouse comes
@@ -21114,31 +22412,31 @@
    * relatedTarget to get the same information in the standard way.
    */
   @deprecated
-  final Node fromElement;
+  Node get fromElement => JS("Node", "#.fromElement", this);
 
   @JSName('layerX')
-  final int _layerX;
+  int get _layerX => JS("int", "#.layerX", this);
 
   @JSName('layerY')
-  final int _layerY;
+  int get _layerY => JS("int", "#.layerY", this);
 
-  final bool metaKey;
+  bool get metaKey => JS("bool", "#.metaKey", this);
 
   @JSName('movementX')
-  final int _movementX;
+  int get _movementX => JS("int", "#.movementX", this);
 
   @JSName('movementY')
-  final int _movementY;
+  int get _movementY => JS("int", "#.movementY", this);
 
   @JSName('pageX')
-  final num _pageX;
+  num get _pageX => JS("num", "#.pageX", this);
 
   @JSName('pageY')
-  final num _pageY;
+  num get _pageY => JS("num", "#.pageY", this);
 
-  final String region;
+  final String? region;
 
-  EventTarget get relatedTarget =>
+  EventTarget? get relatedTarget =>
       _convertNativeToDart_EventTarget(this._get_relatedTarget);
   @JSName('relatedTarget')
   @Creates('Node')
@@ -21146,12 +22444,12 @@
   final dynamic _get_relatedTarget;
 
   @JSName('screenX')
-  final num _screenX;
+  num get _screenX => JS("num", "#.screenX", this);
 
   @JSName('screenY')
-  final num _screenY;
+  num get _screenY => JS("num", "#.screenY", this);
 
-  final bool shiftKey;
+  bool get shiftKey => JS("bool", "#.shiftKey", this);
 
   /**
    * The nonstandard way to access the element that the mouse goes
@@ -21161,7 +22459,7 @@
    * relatedTarget to get the same information in the standard way.
    */
   @deprecated
-  final Node toElement;
+  Node get toElement => JS("Node", "#.toElement", this);
 
   bool getModifierState(String keyArg) native;
 
@@ -21169,7 +22467,7 @@
       String type,
       bool bubbles,
       bool cancelable,
-      Window view,
+      Window? view,
       int detail,
       int screenX,
       int screenY,
@@ -21180,7 +22478,7 @@
       bool shiftKey,
       bool metaKey,
       int button,
-      EventTarget relatedTarget) {
+      EventTarget? relatedTarget) {
     var relatedTarget_1 = _convertDartToNative_EventTarget(relatedTarget);
     _initMouseEvent_1(
         type,
@@ -21206,7 +22504,7 @@
       type,
       bubbles,
       cancelable,
-      Window view,
+      Window? view,
       detail,
       screenX,
       screenY,
@@ -21283,21 +22581,21 @@
 
   static const int REMOVAL = 3;
 
-  final int attrChange;
+  int get attrChange => JS("int", "#.attrChange", this);
 
-  final String attrName;
+  String get attrName => JS("String", "#.attrName", this);
 
-  final String newValue;
+  String get newValue => JS("String", "#.newValue", this);
 
-  final String prevValue;
+  String get prevValue => JS("String", "#.prevValue", this);
 
-  final Node relatedNode;
+  final Node? relatedNode;
 
   void initMutationEvent(
       String type,
       bool bubbles,
       bool cancelable,
-      Node relatedNode,
+      Node? relatedNode,
       String prevValue,
       String newValue,
       String attrName,
@@ -21314,7 +22612,7 @@
 class MutationObserver extends Interceptor {
   void disconnect() native;
 
-  void _observe(Node target, [Map options]) {
+  void _observe(Node target, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       _observe_1(target, options_1);
@@ -21357,7 +22655,7 @@
       bool subtree,
       bool attributeOldValue,
       bool characterDataOldValue,
-      List<String> attributeFilter}) {
+      List<String>? attributeFilter}) {
     // Parse options into map of known type.
     var parsedOptions = _createDict();
 
@@ -21424,25 +22722,25 @@
 
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  final List<Node> addedNodes;
+  List<Node> get addedNodes => JS("NodeList", "#.addedNodes", this);
 
-  final String attributeName;
+  final String? attributeName;
 
-  final String attributeNamespace;
+  final String? attributeNamespace;
 
-  final Node nextSibling;
+  final Node? nextSibling;
 
-  final String oldValue;
+  final String? oldValue;
 
-  final Node previousSibling;
+  final Node? previousSibling;
 
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  final List<Node> removedNodes;
+  List<Node> get removedNodes => JS("NodeList", "#.removedNodes", this);
 
-  final Node target;
+  Node get target => JS("Node", "#.target", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -21563,61 +22861,67 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final _BudgetService budget;
+  _BudgetService get budget => JS("_BudgetService", "#.budget", this);
 
-  final _Clipboard clipboard;
+  _Clipboard get clipboard => JS("_Clipboard", "#.clipboard", this);
 
-  final NetworkInformation connection;
+  NetworkInformation get connection =>
+      JS("NetworkInformation", "#.connection", this);
 
-  final CredentialsContainer credentials;
+  CredentialsContainer get credentials =>
+      JS("CredentialsContainer", "#.credentials", this);
 
-  final num deviceMemory;
+  num get deviceMemory => JS("num", "#.deviceMemory", this);
 
-  final String doNotTrack;
+  final String? doNotTrack;
 
   @Unstable()
-  final Geolocation geolocation;
+  Geolocation get geolocation => JS("Geolocation", "#.geolocation", this);
 
-  final int maxTouchPoints;
+  int get maxTouchPoints => JS("int", "#.maxTouchPoints", this);
 
-  final MediaCapabilities mediaCapabilities;
+  MediaCapabilities get mediaCapabilities =>
+      JS("MediaCapabilities", "#.mediaCapabilities", this);
 
-  final MediaDevices mediaDevices;
+  MediaDevices get mediaDevices => JS("MediaDevices", "#.mediaDevices", this);
 
-  final MediaSession mediaSession;
+  MediaSession get mediaSession => JS("MediaSession", "#.mediaSession", this);
 
-  final MimeTypeArray mimeTypes;
+  MimeTypeArray get mimeTypes => JS("MimeTypeArray", "#.mimeTypes", this);
 
-  final _NFC nfc;
+  _NFC get nfc => JS("_NFC", "#.nfc", this);
 
-  final Permissions permissions;
+  Permissions get permissions => JS("Permissions", "#.permissions", this);
 
-  final Presentation presentation;
+  Presentation get presentation => JS("Presentation", "#.presentation", this);
 
   @Unstable()
-  final String productSub;
+  String get productSub => JS("String", "#.productSub", this);
 
-  final ServiceWorkerContainer serviceWorker;
+  ServiceWorkerContainer get serviceWorker =>
+      JS("ServiceWorkerContainer", "#.serviceWorker", this);
 
-  final StorageManager storage;
+  StorageManager get storage => JS("StorageManager", "#.storage", this);
 
   @Unstable()
-  final String vendor;
+  String get vendor => JS("String", "#.vendor", this);
 
   @Unstable()
-  final String vendorSub;
+  String get vendorSub => JS("String", "#.vendorSub", this);
 
-  final VR vr;
+  VR get vr => JS("VR", "#.vr", this);
 
   @JSName('webkitPersistentStorage')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final DeprecatedStorageQuota persistentStorage;
+  DeprecatedStorageQuota get persistentStorage =>
+      JS("DeprecatedStorageQuota", "#.webkitPersistentStorage", this);
 
   @JSName('webkitTemporaryStorage')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final DeprecatedStorageQuota temporaryStorage;
+  DeprecatedStorageQuota get temporaryStorage =>
+      JS("DeprecatedStorageQuota", "#.webkitTemporaryStorage", this);
 
   void cancelKeyboardLock() native;
 
@@ -21637,7 +22941,7 @@
   @Unstable()
   void registerProtocolHandler(String scheme, String url, String title) native;
 
-  Future requestKeyboardLock([List<String> keyCodes]) {
+  Future requestKeyboardLock([List<String>? keyCodes]) {
     if (keyCodes != null) {
       List keyCodes_1 = convertDartToNative_StringArray(keyCodes);
       return _requestKeyboardLock_1(keyCodes_1);
@@ -21653,7 +22957,7 @@
       promiseToFuture(JS("", "#.requestKeyboardLock()", this));
 
   @JSName('requestMIDIAccess')
-  Future requestMidiAccess([Map options]) {
+  Future requestMidiAccess([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -21667,9 +22971,9 @@
       promiseToFuture(JS("", "#.requestMediaKeySystemAccess(#, #)", this,
           keySystem, supportedConfigurations));
 
-  bool sendBeacon(String url, Object data) native;
+  bool sendBeacon(String url, Object? data) native;
 
-  Future share([Map data]) {
+  Future share([Map? data]) {
     var data_dict = null;
     if (data != null) {
       data_dict = convertDartToNative_Dictionary(data);
@@ -21679,38 +22983,38 @@
 
   // From NavigatorAutomationInformation
 
-  final bool webdriver;
+  bool get webdriver => JS("bool", "#.webdriver", this);
 
   // From NavigatorCookies
 
   @Unstable()
-  final bool cookieEnabled;
+  bool get cookieEnabled => JS("bool", "#.cookieEnabled", this);
 
   // From NavigatorID
 
-  final String appCodeName;
+  String get appCodeName => JS("String", "#.appCodeName", this);
 
-  final String appName;
+  String get appName => JS("String", "#.appName", this);
 
-  final String appVersion;
+  String get appVersion => JS("String", "#.appVersion", this);
 
-  final bool dartEnabled;
+  bool get dartEnabled => JS("bool", "#.dartEnabled", this);
 
-  final String platform;
+  String get platform => JS("String", "#.platform", this);
 
   @Unstable()
-  final String product;
+  String get product => JS("String", "#.product", this);
 
-  final String userAgent;
+  String get userAgent => JS("String", "#.userAgent", this);
 
   // From NavigatorLanguage
 
-  final List<String> languages;
+  List<String> get languages => JS("List<String>", "#.languages", this);
 
   // From NavigatorOnLine
 
   @Unstable()
-  final bool onLine;
+  bool get onLine => JS("bool", "#.onLine", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -21723,7 +23027,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool webdriver;
+  bool get webdriver => JS("bool", "#.webdriver", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -21736,7 +23040,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int hardwareConcurrency;
+  int get hardwareConcurrency => JS("int", "#.hardwareConcurrency", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -21749,7 +23053,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool cookieEnabled;
+  bool get cookieEnabled => JS("bool", "#.cookieEnabled", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -21812,11 +23116,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String constraintName;
+  String get constraintName => JS("String", "#.constraintName", this);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -21846,15 +23150,15 @@
   static const EventStreamProvider<Event> changeEvent =
       const EventStreamProvider<Event>('change');
 
-  final num downlink;
+  num get downlink => JS("num", "#.downlink", this);
 
-  final num downlinkMax;
+  num get downlinkMax => JS("num", "#.downlinkMax", this);
 
-  final String effectiveType;
+  String get effectiveType => JS("String", "#.effectiveType", this);
 
-  final int rtt;
+  int get rtt => JS("int", "#.rtt", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
   Stream<Event> get onChange => changeEvent.forTarget(this);
 }
@@ -21951,7 +23255,7 @@
     return result;
   }
 
-  bool remove(Object object) {
+  bool remove(Object? object) {
     if (object is! Node) return false;
     Node node = object;
     if (!identical(_this, node.parentNode)) return false;
@@ -21995,11 +23299,11 @@
 
   // TODO(jacobr): this could be implemented for child node lists.
   // The exception we throw here is misleading.
-  void sort([Comparator<Node> compare]) {
+  void sort([Comparator<Node>? compare]) {
     throw new UnsupportedError("Cannot sort Node list");
   }
 
-  void shuffle([Random random]) {
+  void shuffle([Random? random]) {
     throw new UnsupportedError("Cannot shuffle Node list");
   }
 
@@ -22009,7 +23313,7 @@
     throw new UnsupportedError("Cannot setRange on Node list");
   }
 
-  void fillRange(int start, int end, [Node fill]) {
+  void fillRange(int start, int end, [Node? fill]) {
     throw new UnsupportedError("Cannot fillRange on Node list");
   }
 
@@ -22158,7 +23462,7 @@
   static const int TEXT_NODE = 3;
 
   @JSName('baseURI')
-  final String baseUri;
+  String get baseUri => JS("String", "#.baseURI", this);
 
   /**
    * The first child of this node.
@@ -22168,9 +23472,9 @@
    * * [Node.firstChild](https://developer.mozilla.org/en-US/docs/Web/API/Node.firstChild)
    *   from MDN.
    */
-  final Node firstChild;
+  final Node? firstChild;
 
-  final bool isConnected;
+  bool get isConnected => JS("bool", "#.isConnected", this);
 
   /**
    * The last child of this node.
@@ -22180,7 +23484,7 @@
    * * [Node.lastChild](https://developer.mozilla.org/en-US/docs/Web/API/Node.lastChild)
    *   from MDN.
    */
-  final Node lastChild;
+  final Node? lastChild;
 
   @JSName('nextSibling')
   /**
@@ -22191,7 +23495,7 @@
    * * [Node.nextSibling](https://developer.mozilla.org/en-US/docs/Web/API/Node.nextSibling)
    *   from MDN.
    */
-  final Node nextNode;
+  final Node? nextNode;
 
   /**
    * The name of this node.
@@ -22204,7 +23508,8 @@
    *   from MDN. This page contains a table of [nodeName] values for each
    *   [nodeType].
    */
-  final String nodeName;
+
+  String get nodeName => JS("String", "#.nodeName", this);
 
   /**
    * The type of node.
@@ -22229,7 +23534,8 @@
    * * [Node.nodeType](https://developer.mozilla.org/en-US/docs/Web/API/Node.nodeType)
    *   from MDN.
    */
-  final int nodeType;
+
+  int get nodeType => JS("int", "#.nodeType", this);
 
   /**
    * The value of this node.
@@ -22242,7 +23548,7 @@
    *   from MDN. This page contains a table of [nodeValue] values for each
    *   [nodeType].
    */
-  final String nodeValue;
+  final String? nodeValue;
 
   /**
    * The document this node belongs to.
@@ -22254,7 +23560,7 @@
    * * [Node.ownerDocument](https://developer.mozilla.org/en-US/docs/Web/API/Node.ownerDocument)
    *   from MDN.
    */
-  final Document ownerDocument;
+  final Document? ownerDocument;
 
   @JSName('parentElement')
   /**
@@ -22268,7 +23574,7 @@
    * * [Node.parentElement](https://developer.mozilla.org/en-US/docs/Web/API/Node.parentElement)
    *   from W3C.
    */
-  final Element parent;
+  final Element? parent;
 
   /**
    * The parent node of this node.
@@ -22278,7 +23584,7 @@
    * * [Node.parentNode](https://developer.mozilla.org/en-US/docs/Web/API/Node.parentNode)
    *   from MDN.
    */
-  final Node parentNode;
+  final Node? parentNode;
 
   @JSName('previousSibling')
   /**
@@ -22289,7 +23595,7 @@
    * * [Node.previousSibling](https://developer.mozilla.org/en-US/docs/Web/API/Node.previousSibling)
    *   from MDN.
    */
-  final Node previousNode;
+  final Node? previousNode;
 
   @JSName('textContent')
   /**
@@ -22300,7 +23606,7 @@
    * * [Node.textContent](https://developer.mozilla.org/en-US/docs/Web/API/Node.textContent)
    *   from MDN.
    */
-  String text;
+  String? text;
 
   @JSName('appendChild')
   /**
@@ -22336,9 +23642,9 @@
    * * [Node.contains](https://developer.mozilla.org/en-US/docs/Web/API/Node.contains)
    *   from MDN.
    */
-  bool contains(Node other) native;
+  bool contains(Node? other) native;
 
-  Node getRootNode([Map options]) {
+  Node getRootNode([Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return _getRootNode_1(options_1);
@@ -22369,7 +23675,7 @@
    * * [Node.insertBefore](https://developer.mozilla.org/en-US/docs/Web/API/Node.insertBefore)
    *   from MDN.
    */
-  Node insertBefore(Node node, Node child) native;
+  Node insertBefore(Node node, Node? child) native;
 
   @JSName('removeChild')
   Node _removeChild(Node child) native;
@@ -22426,13 +23732,14 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool pointerBeforeReferenceNode;
+  bool get pointerBeforeReferenceNode =>
+      JS("bool", "#.pointerBeforeReferenceNode", this);
 
-  final Node referenceNode;
+  Node get referenceNode => JS("Node", "#.referenceNode", this);
 
-  final Node root;
+  Node get root => JS("Node", "#.root", this);
 
-  final int whatToShow;
+  int get whatToShow => JS("int", "#.whatToShow", this);
 
   void detach() native;
 
@@ -22512,9 +23819,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Element nextElementSibling;
+  final Element? nextElementSibling;
 
-  final Element previousElementSibling;
+  final Element? previousElementSibling;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -22540,7 +23847,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String nonce;
+  String get nonce => JS("String", "#.nonce", this);
+
+  set nonce(String value) {
+    JS("void", "#.nonce = #", this, value);
+  }
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -22603,7 +23914,7 @@
   static const EventStreamProvider<Event> showEvent =
       const EventStreamProvider<Event>('show');
 
-  static Notification _factoryNotification(String title, [Map options]) {
+  static Notification _factoryNotification(String title, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return Notification._create_1(title, options_1);
@@ -22619,47 +23930,47 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => JS('bool', '!!(window.Notification)');
 
-  final List actions;
+  List get actions => JS("List", "#.actions", this);
 
-  final String badge;
+  String get badge => JS("String", "#.badge", this);
 
-  final String body;
+  String get body => JS("String", "#.body", this);
 
   @annotation_Creates_SerializedScriptValue
   @annotation_Returns_SerializedScriptValue
-  final Object data;
+  Object get data => JS("Object", "#.data", this);
 
-  final String dir;
+  String get dir => JS("String", "#.dir", this);
 
-  final String icon;
+  String get icon => JS("String", "#.icon", this);
 
-  final String image;
+  String get image => JS("String", "#.image", this);
 
-  final String lang;
+  String get lang => JS("String", "#.lang", this);
 
-  static final int maxActions;
+  int get maxActions => JS("int", "#.maxActions", this);
 
-  static final String permission;
+  String get permission => JS("String", "#.permission", this);
 
-  final bool renotify;
+  bool get renotify => JS("bool", "#.renotify", this);
 
-  final bool requireInteraction;
+  bool get requireInteraction => JS("bool", "#.requireInteraction", this);
 
-  final bool silent;
+  bool get silent => JS("bool", "#.silent", this);
 
-  final String tag;
+  String get tag => JS("String", "#.tag", this);
 
-  final int timestamp;
+  int get timestamp => JS("int", "#.timestamp", this);
 
-  final String title;
+  String get title => JS("String", "#.title", this);
 
-  final List<int> vibrate;
+  List<int> get vibrate => JS("List<int>", "#.vibrate", this);
 
   void close() native;
 
   @JSName('requestPermission')
   static Future _requestPermission(
-      [_NotificationPermissionCallback deprecatedCallback]) native;
+      [_NotificationPermissionCallback? deprecatedCallback]) native;
 
   @JSName('requestPermission')
   static Future<String> requestPermission() {
@@ -22700,11 +24011,11 @@
   static NotificationEvent _create_1(type, eventInitDict) => JS(
       'NotificationEvent', 'new NotificationEvent(#,#)', type, eventInitDict);
 
-  final String action;
+  String get action => JS("String", "#.action", this);
 
-  final Notification notification;
+  Notification get notification => JS("Notification", "#.notification", this);
 
-  final String reply;
+  final String? reply;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -22724,7 +24035,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory OListElement() => JS(
+  factory OListElement() => JS<OListElement>(
       'returns:OListElement;creates:OListElement;new:true',
       '#.createElement(#)',
       document,
@@ -22736,11 +24047,23 @@
    */
   OListElement.created() : super.created();
 
-  bool reversed;
+  bool get reversed => JS("bool", "#.reversed", this);
 
-  int start;
+  set reversed(bool value) {
+    JS("void", "#.reversed = #", this, value);
+  }
 
-  String type;
+  int get start => JS("int", "#.start", this);
+
+  set start(int value) {
+    JS("void", "#.start = #", this, value);
+  }
+
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -22757,7 +24080,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ObjectElement() => document.createElement("object");
+  factory ObjectElement() => document.createElement("object") as ObjectElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -22768,32 +24091,56 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('object');
 
-  WindowBase get contentWindow =>
+  WindowBase? get contentWindow =>
       _convertNativeToDart_Window(this._get_contentWindow);
   @JSName('contentWindow')
   @Creates('Window|=Object')
   @Returns('Window|=Object')
   final dynamic _get_contentWindow;
 
-  String data;
+  String get data => JS("String", "#.data", this);
 
-  final FormElement form;
+  set data(String value) {
+    JS("void", "#.data = #", this, value);
+  }
 
-  String height;
+  final FormElement? form;
 
-  String name;
+  String get height => JS("String", "#.height", this);
 
-  String type;
+  set height(String value) {
+    JS("void", "#.height = #", this, value);
+  }
 
-  String useMap;
+  String get name => JS("String", "#.name", this);
 
-  final String validationMessage;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
-  final ValidityState validity;
+  String get type => JS("String", "#.type", this);
 
-  String width;
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 
-  final bool willValidate;
+  String get useMap => JS("String", "#.useMap", this);
+
+  set useMap(String value) {
+    JS("void", "#.useMap = #", this, value);
+  }
+
+  String get validationMessage => JS("String", "#.validationMessage", this);
+
+  ValidityState get validity => JS("ValidityState", "#.validity", this);
+
+  String get width => JS("String", "#.width", this);
+
+  set width(String value) {
+    JS("void", "#.width = #", this, value);
+  }
+
+  bool get willValidate => JS("bool", "#.willValidate", this);
 
   Node __getter__(String name) native;
 
@@ -22822,11 +24169,19 @@
   static OffscreenCanvas _create_1(width, height) =>
       JS('OffscreenCanvas', 'new OffscreenCanvas(#,#)', width, height);
 
-  int height;
+  int get height => JS("int", "#.height", this);
 
-  int width;
+  set height(int value) {
+    JS("void", "#.height = #", this, value);
+  }
 
-  Future<Blob> convertToBlob([Map options]) {
+  int get width => JS("int", "#.width", this);
+
+  set width(int value) {
+    JS("void", "#.width = #", this, value);
+  }
+
+  Future<Blob> convertToBlob([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -22835,7 +24190,7 @@
         JS("", "#.convertToBlob(#)", this, options_dict));
   }
 
-  Object getContext(String contextType, [Map attributes]) {
+  Object getContext(String contextType, [Map? attributes]) {
     if (attributes != null) {
       var attributes_1 = convertDartToNative_Dictionary(attributes);
       return _getContext_1(contextType, attributes_1);
@@ -22862,60 +24217,142 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final OffscreenCanvas canvas;
+  OffscreenCanvas get canvas => JS("OffscreenCanvas", "#.canvas", this);
 
-  String direction;
+  String get direction => JS("String", "#.direction", this);
 
-  Object fillStyle;
+  set direction(String value) {
+    JS("void", "#.direction = #", this, value);
+  }
 
-  String filter;
+  Object get fillStyle => JS("Object", "#.fillStyle", this);
 
-  String font;
+  set fillStyle(Object value) {
+    JS("void", "#.fillStyle = #", this, value);
+  }
 
-  num globalAlpha;
+  String get filter => JS("String", "#.filter", this);
 
-  String globalCompositeOperation;
+  set filter(String value) {
+    JS("void", "#.filter = #", this, value);
+  }
 
-  bool imageSmoothingEnabled;
+  String get font => JS("String", "#.font", this);
 
-  String imageSmoothingQuality;
+  set font(String value) {
+    JS("void", "#.font = #", this, value);
+  }
 
-  String lineCap;
+  num get globalAlpha => JS("num", "#.globalAlpha", this);
 
-  num lineDashOffset;
+  set globalAlpha(num value) {
+    JS("void", "#.globalAlpha = #", this, value);
+  }
 
-  String lineJoin;
+  String get globalCompositeOperation =>
+      JS("String", "#.globalCompositeOperation", this);
 
-  num lineWidth;
+  set globalCompositeOperation(String value) {
+    JS("void", "#.globalCompositeOperation = #", this, value);
+  }
 
-  num miterLimit;
+  bool get imageSmoothingEnabled => JS("bool", "#.imageSmoothingEnabled", this);
 
-  num shadowBlur;
+  set imageSmoothingEnabled(bool value) {
+    JS("void", "#.imageSmoothingEnabled = #", this, value);
+  }
 
-  String shadowColor;
+  String get imageSmoothingQuality =>
+      JS("String", "#.imageSmoothingQuality", this);
 
-  num shadowOffsetX;
+  set imageSmoothingQuality(String value) {
+    JS("void", "#.imageSmoothingQuality = #", this, value);
+  }
 
-  num shadowOffsetY;
+  String get lineCap => JS("String", "#.lineCap", this);
 
-  Object strokeStyle;
+  set lineCap(String value) {
+    JS("void", "#.lineCap = #", this, value);
+  }
 
-  String textAlign;
+  num get lineDashOffset => JS("num", "#.lineDashOffset", this);
 
-  String textBaseline;
+  set lineDashOffset(num value) {
+    JS("void", "#.lineDashOffset = #", this, value);
+  }
+
+  String get lineJoin => JS("String", "#.lineJoin", this);
+
+  set lineJoin(String value) {
+    JS("void", "#.lineJoin = #", this, value);
+  }
+
+  num get lineWidth => JS("num", "#.lineWidth", this);
+
+  set lineWidth(num value) {
+    JS("void", "#.lineWidth = #", this, value);
+  }
+
+  num get miterLimit => JS("num", "#.miterLimit", this);
+
+  set miterLimit(num value) {
+    JS("void", "#.miterLimit = #", this, value);
+  }
+
+  num get shadowBlur => JS("num", "#.shadowBlur", this);
+
+  set shadowBlur(num value) {
+    JS("void", "#.shadowBlur = #", this, value);
+  }
+
+  String get shadowColor => JS("String", "#.shadowColor", this);
+
+  set shadowColor(String value) {
+    JS("void", "#.shadowColor = #", this, value);
+  }
+
+  num get shadowOffsetX => JS("num", "#.shadowOffsetX", this);
+
+  set shadowOffsetX(num value) {
+    JS("void", "#.shadowOffsetX = #", this, value);
+  }
+
+  num get shadowOffsetY => JS("num", "#.shadowOffsetY", this);
+
+  set shadowOffsetY(num value) {
+    JS("void", "#.shadowOffsetY = #", this, value);
+  }
+
+  Object get strokeStyle => JS("Object", "#.strokeStyle", this);
+
+  set strokeStyle(Object value) {
+    JS("void", "#.strokeStyle = #", this, value);
+  }
+
+  String get textAlign => JS("String", "#.textAlign", this);
+
+  set textAlign(String value) {
+    JS("void", "#.textAlign = #", this, value);
+  }
+
+  String get textBaseline => JS("String", "#.textBaseline", this);
+
+  set textBaseline(String value) {
+    JS("void", "#.textBaseline = #", this, value);
+  }
 
   void beginPath() native;
 
   void clearRect(num x, num y, num width, num height) native;
 
-  void clip([Path2D path]) native;
+  void clip([Path2D? path]) native;
 
   Future commit() => promiseToFuture(JS("", "#.commit()", this));
 
   ImageData createImageData(data_OR_imagedata_OR_sw,
-      [int sh_OR_sw,
+      [int? sh_OR_sw,
       imageDataColorSettings_OR_sh,
-      Map imageDataColorSettings]) {
+      Map? imageDataColorSettings]) {
     if ((data_OR_imagedata_OR_sw is ImageData) &&
         sh_OR_sw == null &&
         imageDataColorSettings_OR_sh == null &&
@@ -22972,18 +24409,18 @@
       num x0, num y0, num r0, num x1, num y1, num r1) native;
 
   void drawImage(/*CanvasImageSource*/ image, num sx_OR_x, num sy_OR_y,
-      [num sw_OR_width,
-      num height_OR_sh,
-      num dx,
-      num dy,
-      num dw,
-      num dh]) native;
+      [num? sw_OR_width,
+      num? height_OR_sh,
+      num? dx,
+      num? dy,
+      num? dw,
+      num? dh]) native;
 
-  void fill([path_OR_winding, String winding]) native;
+  void fill([path_OR_winding, String? winding]) native;
 
   void fillRect(num x, num y, num width, num height) native;
 
-  void fillText(String text, num x, num y, [num maxWidth]) native;
+  void fillText(String text, num x, num y, [num? maxWidth]) native;
 
   ImageData getImageData(int sx, int sy, int sw, int sh) {
     return convertNativeToDart_ImageData(_getImageData_1(sx, sy, sw, sh));
@@ -22994,15 +24431,15 @@
 
   List<num> getLineDash() native;
 
-  bool isPointInPath(path_OR_x, num x_OR_y, [winding_OR_y, String winding])
+  bool isPointInPath(path_OR_x, num x_OR_y, [winding_OR_y, String? winding])
       native;
 
-  bool isPointInStroke(path_OR_x, num x_OR_y, [num y]) native;
+  bool isPointInStroke(path_OR_x, num x_OR_y, [num? y]) native;
 
   TextMetrics measureText(String text) native;
 
   void putImageData(ImageData imagedata, int dx, int dy,
-      [int dirtyX, int dirtyY, int dirtyWidth, int dirtyHeight]) {
+      [int? dirtyX, int? dirtyY, int? dirtyWidth, int? dirtyHeight]) {
     if (dirtyX == null &&
         dirtyY == null &&
         dirtyWidth == null &&
@@ -23043,11 +24480,11 @@
 
   void setTransform(num a, num b, num c, num d, num e, num f) native;
 
-  void stroke([Path2D path]) native;
+  void stroke([Path2D? path]) native;
 
   void strokeRect(num x, num y, num width, num height) native;
 
-  void strokeText(String text, num x, num y, [num maxWidth]) native;
+  void strokeText(String text, num x, num y, [num? maxWidth]) native;
 
   void transform(num a, num b, num c, num d, num e, num f) native;
 
@@ -23087,7 +24524,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory OptGroupElement() => JS(
+  factory OptGroupElement() => JS<OptGroupElement>(
       'returns:OptGroupElement;creates:OptGroupElement;new:true',
       '#.createElement(#)',
       document,
@@ -23099,9 +24536,17 @@
    */
   OptGroupElement.created() : super.created();
 
-  bool disabled;
+  bool get disabled => JS("bool", "#.disabled", this);
 
-  String label;
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
+
+  String get label => JS("String", "#.label", this);
+
+  set label(String value) {
+    JS("void", "#.label = #", this, value);
+  }
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23115,7 +24560,7 @@
   }
 
   factory OptionElement._(
-      [String data, String value, bool defaultSelected, bool selected]) {
+      [String? data, String? value, bool? defaultSelected, bool? selected]) {
     if (selected != null) {
       return OptionElement._create_1(data, value, defaultSelected, selected);
     }
@@ -23151,19 +24596,39 @@
    */
   OptionElement.created() : super.created();
 
-  bool defaultSelected;
+  bool get defaultSelected => JS("bool", "#.defaultSelected", this);
 
-  bool disabled;
+  set defaultSelected(bool value) {
+    JS("void", "#.defaultSelected = #", this, value);
+  }
 
-  final FormElement form;
+  bool get disabled => JS("bool", "#.disabled", this);
 
-  final int index;
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
 
-  String label;
+  final FormElement? form;
 
-  bool selected;
+  int get index => JS("int", "#.index", this);
 
-  String value;
+  String get label => JS("String", "#.label", this);
+
+  set label(String value) {
+    JS("void", "#.label = #", this, value);
+  }
+
+  bool get selected => JS("bool", "#.selected", this);
+
+  set selected(bool value) {
+    JS("void", "#.selected = #", this, value);
+  }
+
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23176,7 +24641,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final List<num> quaternion;
+  final List<num>? quaternion;
 
   void populateMatrix(Object targetBuffer) native;
 }
@@ -23194,7 +24659,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory OutputElement() => document.createElement("output");
+  factory OutputElement() => document.createElement("output") as OutputElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -23205,28 +24670,40 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('output');
 
-  String defaultValue;
+  String get defaultValue => JS("String", "#.defaultValue", this);
 
-  final FormElement form;
+  set defaultValue(String value) {
+    JS("void", "#.defaultValue = #", this, value);
+  }
 
-  final DomTokenList htmlFor;
+  final FormElement? form;
+
+  DomTokenList get htmlFor => JS("DomTokenList", "#.htmlFor", this);
 
   @Unstable()
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  final List<Node> labels;
+  List<Node> get labels => JS("NodeList", "#.labels", this);
 
-  String name;
+  String get name => JS("String", "#.name", this);
 
-  final String type;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
-  final String validationMessage;
+  String get type => JS("String", "#.type", this);
 
-  final ValidityState validity;
+  String get validationMessage => JS("String", "#.validationMessage", this);
 
-  String value;
+  ValidityState get validity => JS("ValidityState", "#.validity", this);
 
-  final bool willValidate;
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
+
+  bool get willValidate => JS("bool", "#.willValidate", this);
 
   bool checkValidity() native;
 
@@ -23254,11 +24731,11 @@
       constraint,
       message);
 
-  final String constraint;
+  final String? constraint;
 
-  final String message;
+  final String? message;
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23271,7 +24748,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory PageTransitionEvent(String type, [Map eventInitDict]) {
+  factory PageTransitionEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return PageTransitionEvent._create_1(type, eventInitDict_1);
@@ -23286,7 +24763,7 @@
   static PageTransitionEvent _create_2(type) =>
       JS('PageTransitionEvent', 'new PageTransitionEvent(#)', type);
 
-  final bool persisted;
+  bool get persisted => JS("bool", "#.persisted", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23299,45 +24776,115 @@
     throw new UnsupportedError("Not supported");
   }
 
-  Matrix currentTransform;
+  Matrix get currentTransform => JS("Matrix", "#.currentTransform", this);
 
-  Object fillStyle;
+  set currentTransform(Matrix value) {
+    JS("void", "#.currentTransform = #", this, value);
+  }
 
-  String filter;
+  Object get fillStyle => JS("Object", "#.fillStyle", this);
 
-  num globalAlpha;
+  set fillStyle(Object value) {
+    JS("void", "#.fillStyle = #", this, value);
+  }
 
-  String globalCompositeOperation;
+  String get filter => JS("String", "#.filter", this);
 
-  bool imageSmoothingEnabled;
+  set filter(String value) {
+    JS("void", "#.filter = #", this, value);
+  }
 
-  String imageSmoothingQuality;
+  num get globalAlpha => JS("num", "#.globalAlpha", this);
 
-  String lineCap;
+  set globalAlpha(num value) {
+    JS("void", "#.globalAlpha = #", this, value);
+  }
 
-  num lineDashOffset;
+  String get globalCompositeOperation =>
+      JS("String", "#.globalCompositeOperation", this);
 
-  String lineJoin;
+  set globalCompositeOperation(String value) {
+    JS("void", "#.globalCompositeOperation = #", this, value);
+  }
 
-  num lineWidth;
+  bool get imageSmoothingEnabled => JS("bool", "#.imageSmoothingEnabled", this);
 
-  num miterLimit;
+  set imageSmoothingEnabled(bool value) {
+    JS("void", "#.imageSmoothingEnabled = #", this, value);
+  }
 
-  num shadowBlur;
+  String get imageSmoothingQuality =>
+      JS("String", "#.imageSmoothingQuality", this);
 
-  String shadowColor;
+  set imageSmoothingQuality(String value) {
+    JS("void", "#.imageSmoothingQuality = #", this, value);
+  }
 
-  num shadowOffsetX;
+  String get lineCap => JS("String", "#.lineCap", this);
 
-  num shadowOffsetY;
+  set lineCap(String value) {
+    JS("void", "#.lineCap = #", this, value);
+  }
 
-  Object strokeStyle;
+  num get lineDashOffset => JS("num", "#.lineDashOffset", this);
+
+  set lineDashOffset(num value) {
+    JS("void", "#.lineDashOffset = #", this, value);
+  }
+
+  String get lineJoin => JS("String", "#.lineJoin", this);
+
+  set lineJoin(String value) {
+    JS("void", "#.lineJoin = #", this, value);
+  }
+
+  num get lineWidth => JS("num", "#.lineWidth", this);
+
+  set lineWidth(num value) {
+    JS("void", "#.lineWidth = #", this, value);
+  }
+
+  num get miterLimit => JS("num", "#.miterLimit", this);
+
+  set miterLimit(num value) {
+    JS("void", "#.miterLimit = #", this, value);
+  }
+
+  num get shadowBlur => JS("num", "#.shadowBlur", this);
+
+  set shadowBlur(num value) {
+    JS("void", "#.shadowBlur = #", this, value);
+  }
+
+  String get shadowColor => JS("String", "#.shadowColor", this);
+
+  set shadowColor(String value) {
+    JS("void", "#.shadowColor = #", this, value);
+  }
+
+  num get shadowOffsetX => JS("num", "#.shadowOffsetX", this);
+
+  set shadowOffsetX(num value) {
+    JS("void", "#.shadowOffsetX = #", this, value);
+  }
+
+  num get shadowOffsetY => JS("num", "#.shadowOffsetY", this);
+
+  set shadowOffsetY(num value) {
+    JS("void", "#.shadowOffsetY = #", this, value);
+  }
+
+  Object get strokeStyle => JS("Object", "#.strokeStyle", this);
+
+  set strokeStyle(Object value) {
+    JS("void", "#.strokeStyle = #", this, value);
+  }
 
   void beginPath() native;
 
   void clearRect(num x, num y, num width, num height) native;
 
-  void clip([path_OR_winding, String winding]) native;
+  void clip([path_OR_winding, String? winding]) native;
 
   CanvasGradient createLinearGradient(num x0, num y0, num x1, num y1) native;
 
@@ -23348,23 +24895,23 @@
       num x0, num y0, num r0, num x1, num y1, num r1) native;
 
   void drawImage(/*CanvasImageSource*/ image, num sx_OR_x, num sy_OR_y,
-      [num sw_OR_width,
-      num height_OR_sh,
-      num dx,
-      num dy,
-      num dw,
-      num dh]) native;
+      [num? sw_OR_width,
+      num? height_OR_sh,
+      num? dx,
+      num? dy,
+      num? dw,
+      num? dh]) native;
 
-  void fill([path_OR_winding, String winding]) native;
+  void fill([path_OR_winding, String? winding]) native;
 
   void fillRect(num x, num y, num width, num height) native;
 
   List<num> getLineDash() native;
 
-  bool isPointInPath(path_OR_x, num x_OR_y, [winding_OR_y, String winding])
+  bool isPointInPath(path_OR_x, num x_OR_y, [winding_OR_y, String? winding])
       native;
 
-  bool isPointInStroke(path_OR_x, num x_OR_y, [num y]) native;
+  bool isPointInStroke(path_OR_x, num x_OR_y, [num? y]) native;
 
   void resetTransform() native;
 
@@ -23380,7 +24927,7 @@
 
   void setTransform(num a, num b, num c, num d, num e, num f) native;
 
-  void stroke([Path2D path]) native;
+  void stroke([Path2D? path]) native;
 
   void strokeRect(num x, num y, num width, num height) native;
 
@@ -23422,9 +24969,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num height;
+  num get height => JS("num", "#.height", this);
 
-  final num width;
+  num get width => JS("num", "#.width", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23437,7 +24984,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num devicePixelRatio;
+  num get devicePixelRatio => JS("num", "#.devicePixelRatio", this);
 
   void registerPaint(String name, Object paintCtor) native;
 }
@@ -23452,7 +24999,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ParagraphElement() => JS(
+  factory ParagraphElement() => JS<ParagraphElement>(
       'returns:ParagraphElement;creates:ParagraphElement;new:true',
       '#.createElement(#)',
       document,
@@ -23476,7 +25023,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ParamElement() => JS(
+  factory ParamElement() => JS<ParamElement>(
       'returns:ParamElement;creates:ParamElement;new:true',
       '#.createElement(#)',
       document,
@@ -23488,9 +25035,17 @@
    */
   ParamElement.created() : super.created();
 
-  String name;
+  String get name => JS("String", "#.name", this);
 
-  String value;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
+
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23540,20 +25095,28 @@
   static PasswordCredential _create_2(data_OR_form) =>
       JS('PasswordCredential', 'new PasswordCredential(#)', data_OR_form);
 
-  Object additionalData;
+  Object? additionalData;
 
-  String idName;
+  String get idName => JS("String", "#.idName", this);
 
-  final String password;
+  set idName(String value) {
+    JS("void", "#.idName = #", this, value);
+  }
 
-  String passwordName;
+  String get password => JS("String", "#.password", this);
+
+  String get passwordName => JS("String", "#.passwordName", this);
+
+  set passwordName(String value) {
+    JS("void", "#.passwordName = #", this, value);
+  }
 
   // From CredentialUserData
 
   @JSName('iconURL')
-  final String iconUrl;
+  String get iconUrl => JS("String", "#.iconURL", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23584,7 +25147,7 @@
   static Path2D _create_3(path_OR_text) =>
       JS('Path2D', 'new Path2D(#)', path_OR_text);
 
-  void addPath(Path2D path, [Matrix transform]) native;
+  void addPath(Path2D path, [Matrix? transform]) native;
 
   // From CanvasPath
 
@@ -23620,27 +25183,27 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final List<String> addressLine;
+  List<String> get addressLine => JS("List<String>", "#.addressLine", this);
 
-  final String city;
+  String get city => JS("String", "#.city", this);
 
-  final String country;
+  String get country => JS("String", "#.country", this);
 
-  final String dependentLocality;
+  String get dependentLocality => JS("String", "#.dependentLocality", this);
 
-  final String languageCode;
+  String get languageCode => JS("String", "#.languageCode", this);
 
-  final String organization;
+  String get organization => JS("String", "#.organization", this);
 
-  final String phone;
+  String get phone => JS("String", "#.phone", this);
 
-  final String postalCode;
+  String get postalCode => JS("String", "#.postalCode", this);
 
-  final String recipient;
+  String get recipient => JS("String", "#.recipient", this);
 
-  final String region;
+  String get region => JS("String", "#.region", this);
 
-  final String sortingCode;
+  String get sortingCode => JS("String", "#.sortingCode", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23684,9 +25247,14 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final PaymentInstruments instruments;
+  PaymentInstruments get instruments =>
+      JS("PaymentInstruments", "#.instruments", this);
 
-  String userHint;
+  String get userHint => JS("String", "#.userHint", this);
+
+  set userHint(String value) {
+    JS("void", "#.userHint = #", this, value);
+  }
 }
 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23722,13 +25290,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
-  final PaymentAddress shippingAddress;
+  final PaymentAddress? shippingAddress;
 
-  final String shippingOption;
+  final String? shippingOption;
 
-  final String shippingType;
+  final String? shippingType;
 
   Future abort() => promiseToFuture(JS("", "#.abort()", this));
 
@@ -23760,19 +25328,20 @@
       type,
       eventInitDict);
 
-  final String instrumentKey;
+  String get instrumentKey => JS("String", "#.instrumentKey", this);
 
-  final List methodData;
+  List get methodData => JS("List", "#.methodData", this);
 
-  final List modifiers;
+  List get modifiers => JS("List", "#.modifiers", this);
 
-  final String paymentRequestId;
+  String get paymentRequestId => JS("String", "#.paymentRequestId", this);
 
-  final String paymentRequestOrigin;
+  String get paymentRequestOrigin =>
+      JS("String", "#.paymentRequestOrigin", this);
 
-  final String topLevelOrigin;
+  String get topLevelOrigin => JS("String", "#.topLevelOrigin", this);
 
-  final Object total;
+  Object get total => JS("Object", "#.total", this);
 
   Future<WindowClient> openWindow(String url) =>
       promiseToFuture<WindowClient>(JS("", "#.openWindow(#)", this, url));
@@ -23790,7 +25359,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory PaymentRequestUpdateEvent(String type, [Map eventInitDict]) {
+  factory PaymentRequestUpdateEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return PaymentRequestUpdateEvent._create_1(type, eventInitDict_1);
@@ -23818,23 +25387,23 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Object details;
+  Object get details => JS("Object", "#.details", this);
 
-  final String methodName;
+  String get methodName => JS("String", "#.methodName", this);
 
-  final String payerEmail;
+  final String? payerEmail;
 
-  final String payerName;
+  final String? payerName;
 
-  final String payerPhone;
+  final String? payerPhone;
 
-  final String requestId;
+  String get requestId => JS("String", "#.requestId", this);
 
-  final PaymentAddress shippingAddress;
+  final PaymentAddress? shippingAddress;
 
-  final String shippingOption;
+  final String? shippingOption;
 
-  Future complete([String paymentResult]) =>
+  Future complete([String? paymentResult]) =>
       promiseToFuture(JS("", "#.complete(#)", this, paymentResult));
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
@@ -23854,13 +25423,14 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => JS('bool', '!!(window.performance)');
 
-  final MemoryInfo memory;
+  MemoryInfo get memory => JS("MemoryInfo", "#.memory", this);
 
-  final PerformanceNavigation navigation;
+  PerformanceNavigation get navigation =>
+      JS("PerformanceNavigation", "#.navigation", this);
 
-  final num timeOrigin;
+  num get timeOrigin => JS("num", "#.timeOrigin", this);
 
-  final PerformanceTiming timing;
+  PerformanceTiming get timing => JS("PerformanceTiming", "#.timing", this);
 
   void clearMarks(String markName) native;
 
@@ -23893,13 +25463,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num duration;
+  num get duration => JS("num", "#.duration", this);
 
-  final String entryType;
+  String get entryType => JS("String", "#.entryType", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
-  final num startTime;
+  num get startTime => JS("num", "#.startTime", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23912,7 +25482,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final List<TaskAttributionTiming> attribution;
+  List<TaskAttributionTiming> get attribution =>
+      JS("List<TaskAttributionTiming>", "#.attribution", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23956,9 +25527,9 @@
 
   static const int TYPE_RESERVED = 255;
 
-  final int redirectCount;
+  int get redirectCount => JS("int", "#.redirectCount", this);
 
-  final int type;
+  int get type => JS("int", "#.type", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -23971,25 +25542,27 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num domComplete;
+  num get domComplete => JS("num", "#.domComplete", this);
 
-  final num domContentLoadedEventEnd;
+  num get domContentLoadedEventEnd =>
+      JS("num", "#.domContentLoadedEventEnd", this);
 
-  final num domContentLoadedEventStart;
+  num get domContentLoadedEventStart =>
+      JS("num", "#.domContentLoadedEventStart", this);
 
-  final num domInteractive;
+  num get domInteractive => JS("num", "#.domInteractive", this);
 
-  final num loadEventEnd;
+  num get loadEventEnd => JS("num", "#.loadEventEnd", this);
 
-  final num loadEventStart;
+  num get loadEventStart => JS("num", "#.loadEventStart", this);
 
-  final int redirectCount;
+  int get redirectCount => JS("int", "#.redirectCount", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
-  final num unloadEventEnd;
+  num get unloadEventEnd => JS("num", "#.unloadEventEnd", this);
 
-  final num unloadEventStart;
+  num get unloadEventStart => JS("num", "#.unloadEventStart", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24067,41 +25640,42 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num connectEnd;
+  num get connectEnd => JS("num", "#.connectEnd", this);
 
-  final num connectStart;
+  num get connectStart => JS("num", "#.connectStart", this);
 
-  final int decodedBodySize;
+  int get decodedBodySize => JS("int", "#.decodedBodySize", this);
 
-  final num domainLookupEnd;
+  num get domainLookupEnd => JS("num", "#.domainLookupEnd", this);
 
-  final num domainLookupStart;
+  num get domainLookupStart => JS("num", "#.domainLookupStart", this);
 
-  final int encodedBodySize;
+  int get encodedBodySize => JS("int", "#.encodedBodySize", this);
 
-  final num fetchStart;
+  num get fetchStart => JS("num", "#.fetchStart", this);
 
-  final String initiatorType;
+  String get initiatorType => JS("String", "#.initiatorType", this);
 
-  final String nextHopProtocol;
+  String get nextHopProtocol => JS("String", "#.nextHopProtocol", this);
 
-  final num redirectEnd;
+  num get redirectEnd => JS("num", "#.redirectEnd", this);
 
-  final num redirectStart;
+  num get redirectStart => JS("num", "#.redirectStart", this);
 
-  final num requestStart;
+  num get requestStart => JS("num", "#.requestStart", this);
 
-  final num responseEnd;
+  num get responseEnd => JS("num", "#.responseEnd", this);
 
-  final num responseStart;
+  num get responseStart => JS("num", "#.responseStart", this);
 
-  final num secureConnectionStart;
+  num get secureConnectionStart => JS("num", "#.secureConnectionStart", this);
 
-  final List<PerformanceServerTiming> serverTiming;
+  List<PerformanceServerTiming> get serverTiming =>
+      JS("List<PerformanceServerTiming>", "#.serverTiming", this);
 
-  final int transferSize;
+  int get transferSize => JS("int", "#.transferSize", this);
 
-  final num workerStart;
+  num get workerStart => JS("num", "#.workerStart", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24114,11 +25688,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String description;
+  String get description => JS("String", "#.description", this);
 
-  final num duration;
+  num get duration => JS("num", "#.duration", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24132,47 +25706,49 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int connectEnd;
+  int get connectEnd => JS("int", "#.connectEnd", this);
 
-  final int connectStart;
+  int get connectStart => JS("int", "#.connectStart", this);
 
-  final int domComplete;
+  int get domComplete => JS("int", "#.domComplete", this);
 
-  final int domContentLoadedEventEnd;
+  int get domContentLoadedEventEnd =>
+      JS("int", "#.domContentLoadedEventEnd", this);
 
-  final int domContentLoadedEventStart;
+  int get domContentLoadedEventStart =>
+      JS("int", "#.domContentLoadedEventStart", this);
 
-  final int domInteractive;
+  int get domInteractive => JS("int", "#.domInteractive", this);
 
-  final int domLoading;
+  int get domLoading => JS("int", "#.domLoading", this);
 
-  final int domainLookupEnd;
+  int get domainLookupEnd => JS("int", "#.domainLookupEnd", this);
 
-  final int domainLookupStart;
+  int get domainLookupStart => JS("int", "#.domainLookupStart", this);
 
-  final int fetchStart;
+  int get fetchStart => JS("int", "#.fetchStart", this);
 
-  final int loadEventEnd;
+  int get loadEventEnd => JS("int", "#.loadEventEnd", this);
 
-  final int loadEventStart;
+  int get loadEventStart => JS("int", "#.loadEventStart", this);
 
-  final int navigationStart;
+  int get navigationStart => JS("int", "#.navigationStart", this);
 
-  final int redirectEnd;
+  int get redirectEnd => JS("int", "#.redirectEnd", this);
 
-  final int redirectStart;
+  int get redirectStart => JS("int", "#.redirectStart", this);
 
-  final int requestStart;
+  int get requestStart => JS("int", "#.requestStart", this);
 
-  final int responseEnd;
+  int get responseEnd => JS("int", "#.responseEnd", this);
 
-  final int responseStart;
+  int get responseStart => JS("int", "#.responseStart", this);
 
-  final int secureConnectionStart;
+  int get secureConnectionStart => JS("int", "#.secureConnectionStart", this);
 
-  final int unloadEventEnd;
+  int get unloadEventEnd => JS("int", "#.unloadEventEnd", this);
 
-  final int unloadEventStart;
+  int get unloadEventStart => JS("int", "#.unloadEventStart", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24188,7 +25764,7 @@
   static const EventStreamProvider<Event> changeEvent =
       const EventStreamProvider<Event>('change');
 
-  final String state;
+  String get state => JS("String", "#.state", this);
 
   Stream<Event> get onChange => changeEvent.forTarget(this);
 }
@@ -24236,13 +25812,15 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final List fillLightMode;
+  List get fillLightMode => JS("List", "#.fillLightMode", this);
 
-  final MediaSettingsRange imageHeight;
+  MediaSettingsRange get imageHeight =>
+      JS("MediaSettingsRange", "#.imageHeight", this);
 
-  final MediaSettingsRange imageWidth;
+  MediaSettingsRange get imageWidth =>
+      JS("MediaSettingsRange", "#.imageWidth", this);
 
-  final String redEyeReduction;
+  String get redEyeReduction => JS("String", "#.redEyeReduction", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24272,13 +25850,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String description;
+  String get description => JS("String", "#.description", this);
 
-  final String filename;
+  String get filename => JS("String", "#.filename", this);
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
   MimeType item(int index) native;
 
@@ -24361,7 +25939,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory PointerEvent(String type, [Map eventInitDict]) {
+  factory PointerEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return PointerEvent._create_1(type, eventInitDict_1);
@@ -24373,25 +25951,25 @@
   static PointerEvent _create_2(type) =>
       JS('PointerEvent', 'new PointerEvent(#)', type);
 
-  final num height;
+  num get height => JS("num", "#.height", this);
 
-  final bool isPrimary;
+  bool get isPrimary => JS("bool", "#.isPrimary", this);
 
-  final int pointerId;
+  int get pointerId => JS("int", "#.pointerId", this);
 
-  final String pointerType;
+  String get pointerType => JS("String", "#.pointerType", this);
 
-  final num pressure;
+  num get pressure => JS("num", "#.pressure", this);
 
-  final num tangentialPressure;
+  num get tangentialPressure => JS("num", "#.tangentialPressure", this);
 
-  final int tiltX;
+  int get tiltX => JS("int", "#.tiltX", this);
 
-  final int tiltY;
+  int get tiltY => JS("int", "#.tiltY", this);
 
-  final int twist;
+  int get twist => JS("int", "#.twist", this);
 
-  final num width;
+  num get width => JS("num", "#.width", this);
 
   List<PointerEvent> getCoalescedEvents() native;
 
@@ -24421,7 +25999,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory PopStateEvent(String type, [Map eventInitDict]) {
+  factory PopStateEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return PopStateEvent._create_1(type, eventInitDict_1);
@@ -24466,9 +26044,9 @@
 
   static const int TIMEOUT = 3;
 
-  final int code;
+  int get code => JS("int", "#.code", this);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24489,8 +26067,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory PreElement() => JS('returns:PreElement;creates:PreElement;new:true',
-      '#.createElement(#)', document, "pre");
+  factory PreElement() => JS<PreElement>(
+      'returns:PreElement;creates:PreElement;new:true',
+      '#.createElement(#)',
+      document,
+      "pre");
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -24509,9 +26090,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  PresentationRequest defaultRequest;
+  PresentationRequest? defaultRequest;
 
-  final PresentationReceiver receiver;
+  final PresentationReceiver? receiver;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24527,7 +26108,7 @@
   static const EventStreamProvider<Event> changeEvent =
       const EventStreamProvider<Event>('change');
 
-  final bool value;
+  bool get value => JS("bool", "#.value", this);
 
   Stream<Event> get onChange => changeEvent.forTarget(this);
 }
@@ -24545,13 +26126,17 @@
   static const EventStreamProvider<MessageEvent> messageEvent =
       const EventStreamProvider<MessageEvent>('message');
 
-  String binaryType;
+  String get binaryType => JS("String", "#.binaryType", this);
 
-  final String id;
+  set binaryType(String value) {
+    JS("void", "#.binaryType = #", this, value);
+  }
 
-  final String state;
+  String get id => JS("String", "#.id", this);
 
-  final String url;
+  String get state => JS("String", "#.state", this);
+
+  String get url => JS("String", "#.url", this);
 
   void close() native;
 
@@ -24581,7 +26166,8 @@
       JS('PresentationConnectionAvailableEvent',
           'new PresentationConnectionAvailableEvent(#,#)', type, eventInitDict);
 
-  final PresentationConnection connection;
+  PresentationConnection get connection =>
+      JS("PresentationConnection", "#.connection", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24604,9 +26190,9 @@
       type,
       eventInitDict);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 
-  final String reason;
+  String get reason => JS("String", "#.reason", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24619,7 +26205,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final List<PresentationConnection> connections;
+  List<PresentationConnection> get connections =>
+      JS("List<PresentationConnection>", "#.connections", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24632,9 +26219,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  Future<PresentationConnectionList> get connectionList =>
-      promiseToFuture<PresentationConnectionList>(
-          JS("", "#.connectionList", this));
+  Future get connectionList => JS("Future", "#.connectionList", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24685,9 +26270,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final StyleSheet sheet;
+  final StyleSheet? sheet;
 
-  final String target;
+  String get target => JS("String", "#.target", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24704,7 +26289,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ProgressElement() => document.createElement("progress");
+  factory ProgressElement() =>
+      document.createElement("progress") as ProgressElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -24718,13 +26304,21 @@
   @Unstable()
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  final List<Node> labels;
+  List<Node> get labels => JS("NodeList", "#.labels", this);
 
-  num max;
+  num get max => JS("num", "#.max", this);
 
-  final num position;
+  set max(num value) {
+    JS("void", "#.max = #", this, value);
+  }
 
-  num value;
+  num get position => JS("num", "#.position", this);
+
+  num get value => JS("num", "#.value", this);
+
+  set value(num value) {
+    JS("void", "#.value = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24737,7 +26331,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ProgressEvent(String type, [Map eventInitDict]) {
+  factory ProgressEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return ProgressEvent._create_1(type, eventInitDict_1);
@@ -24749,11 +26343,11 @@
   static ProgressEvent _create_2(type) =>
       JS('ProgressEvent', 'new ProgressEvent(#)', type);
 
-  final bool lengthComputable;
+  bool get lengthComputable => JS("bool", "#.lengthComputable", this);
 
-  final int loaded;
+  int get loaded => JS("int", "#.loaded", this);
 
-  final int total;
+  int get total => JS("int", "#.total", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24776,9 +26370,9 @@
       type,
       eventInitDict);
 
-  Future get promise => promiseToFuture(JS("", "#.promise", this));
+  Future get promise => JS("Future", "#.promise", this);
 
-  final Object reason;
+  Object get reason => JS("Object", "#.reason", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24791,9 +26385,10 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final ByteBuffer rawId;
+  ByteBuffer get rawId => JS("ByteBuffer", "#.rawId", this);
 
-  final AuthenticatorResponse response;
+  AuthenticatorResponse get response =>
+      JS("AuthenticatorResponse", "#.response", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24806,7 +26401,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory PushEvent(String type, [Map eventInitDict]) {
+  factory PushEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return PushEvent._create_1(type, eventInitDict_1);
@@ -24817,7 +26412,7 @@
       JS('PushEvent', 'new PushEvent(#,#)', type, eventInitDict);
   static PushEvent _create_2(type) => JS('PushEvent', 'new PushEvent(#)', type);
 
-  final PushMessageData data;
+  final PushMessageData? data;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24830,12 +26425,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  static final List<String> supportedContentEncodings;
+  List<String> get supportedContentEncodings =>
+      JS("List<String>", "#.supportedContentEncodings", this);
 
   Future<PushSubscription> getSubscription() =>
       promiseToFuture<PushSubscription>(JS("", "#.getSubscription()", this));
 
-  Future permissionState([Map options]) {
+  Future permissionState([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -24843,7 +26439,7 @@
     return promiseToFuture(JS("", "#.permissionState(#)", this, options_dict));
   }
 
-  Future<PushSubscription> subscribe([Map options]) {
+  Future<PushSubscription> subscribe([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -24882,11 +26478,12 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String endpoint;
+  String get endpoint => JS("String", "#.endpoint", this);
 
-  final int expirationTime;
+  int get expirationTime => JS("int", "#.expirationTime", this);
 
-  final PushSubscriptionOptions options;
+  PushSubscriptionOptions get options =>
+      JS("PushSubscriptionOptions", "#.options", this);
 
   ByteBuffer getKey(String name) native;
 
@@ -24904,9 +26501,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final ByteBuffer applicationServerKey;
+  final ByteBuffer? applicationServerKey;
 
-  final bool userVisibleOnly;
+  bool get userVisibleOnly => JS("bool", "#.userVisibleOnly", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24919,7 +26516,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory QuoteElement() => JS(
+  factory QuoteElement() => JS<QuoteElement>(
       'returns:QuoteElement;creates:QuoteElement;new:true',
       '#.createElement(#)',
       document,
@@ -24931,7 +26528,11 @@
    */
   QuoteElement.created() : super.created();
 
-  String cite;
+  String get cite => JS("String", "#.cite", this);
+
+  set cite(String value) {
+    JS("void", "#.cite = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -24980,23 +26581,24 @@
 
   static const int START_TO_START = 0;
 
-  final bool collapsed;
+  bool get collapsed => JS("bool", "#.collapsed", this);
 
-  final Node commonAncestorContainer;
+  Node get commonAncestorContainer =>
+      JS("Node", "#.commonAncestorContainer", this);
 
-  final Node endContainer;
+  Node get endContainer => JS("Node", "#.endContainer", this);
 
-  final int endOffset;
+  int get endOffset => JS("int", "#.endOffset", this);
 
-  final Node startContainer;
+  Node get startContainer => JS("Node", "#.startContainer", this);
 
-  final int startOffset;
+  int get startOffset => JS("int", "#.startOffset", this);
 
   DocumentFragment cloneContents() native;
 
   Range cloneRange() native;
 
-  void collapse([bool toStart]) native;
+  void collapse([bool? toStart]) native;
 
   int compareBoundaryPoints(int how, Range sourceRange) native;
 
@@ -25076,11 +26678,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
-  final String platform;
+  String get platform => JS("String", "#.platform", this);
 
-  final String url;
+  String get url => JS("String", "#.url", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25093,7 +26695,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory RelativeOrientationSensor([Map sensorOptions]) {
+  factory RelativeOrientationSensor([Map? sensorOptions]) {
     if (sensorOptions != null) {
       var sensorOptions_1 = convertDartToNative_Dictionary(sensorOptions);
       return RelativeOrientationSensor._create_1(sensorOptions_1);
@@ -25118,9 +26720,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String state;
+  String get state => JS("String", "#.state", this);
 
-  Future cancelWatchAvailability([int id]) =>
+  Future cancelWatchAvailability([int? id]) =>
       promiseToFuture(JS("", "#.cancelWatchAvailability(#)", this, id));
 
   Future prompt() => promiseToFuture(JS("", "#.prompt()", this));
@@ -25225,9 +26827,10 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final DomRectReadOnly contentRect;
+  DomRectReadOnly get contentRect =>
+      JS("DomRectReadOnly", "#.contentRect", this);
 
-  final Element target;
+  Element get target => JS("Element", "#.target", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25240,7 +26843,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int expires;
+  int get expires => JS("int", "#.expires", this);
 
   List<Map> getFingerprints() native;
 }
@@ -25291,29 +26894,38 @@
   static const EventStreamProvider<Event> openEvent =
       const EventStreamProvider<Event>('open');
 
-  String binaryType;
+  String get binaryType => JS("String", "#.binaryType", this);
 
-  final int bufferedAmount;
+  set binaryType(String value) {
+    JS("void", "#.binaryType = #", this, value);
+  }
 
-  int bufferedAmountLowThreshold;
+  int get bufferedAmount => JS("int", "#.bufferedAmount", this);
 
-  final int id;
+  int get bufferedAmountLowThreshold =>
+      JS("int", "#.bufferedAmountLowThreshold", this);
 
-  final String label;
+  set bufferedAmountLowThreshold(int value) {
+    JS("void", "#.bufferedAmountLowThreshold = #", this, value);
+  }
 
-  final int maxRetransmitTime;
+  int get id => JS("int", "#.id", this);
 
-  final int maxRetransmits;
+  String get label => JS("String", "#.label", this);
 
-  final bool negotiated;
+  int get maxRetransmitTime => JS("int", "#.maxRetransmitTime", this);
 
-  final bool ordered;
+  int get maxRetransmits => JS("int", "#.maxRetransmits", this);
 
-  final String protocol;
+  bool get negotiated => JS("bool", "#.negotiated", this);
 
-  final String readyState;
+  bool get ordered => JS("bool", "#.ordered", this);
 
-  final bool reliable;
+  String get protocol => JS("String", "#.protocol", this);
+
+  String get readyState => JS("String", "#.readyState", this);
+
+  bool get reliable => JS("bool", "#.reliable", this);
 
   void close() native;
 
@@ -25364,7 +26976,7 @@
       type,
       eventInitDict);
 
-  final RtcDataChannel channel;
+  RtcDataChannel get channel => JS("RtcDataChannel", "#.channel", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25387,18 +26999,18 @@
       const EventStreamProvider<RtcDtmfToneChangeEvent>('tonechange');
 
   @JSName('canInsertDTMF')
-  final bool canInsertDtmf;
+  bool get canInsertDtmf => JS("bool", "#.canInsertDTMF", this);
 
-  final int duration;
+  int get duration => JS("int", "#.duration", this);
 
-  final int interToneGap;
+  int get interToneGap => JS("int", "#.interToneGap", this);
 
-  final String toneBuffer;
+  String get toneBuffer => JS("String", "#.toneBuffer", this);
 
-  final MediaStreamTrack track;
+  MediaStreamTrack get track => JS("MediaStreamTrack", "#.track", this);
 
   @JSName('insertDTMF')
-  void insertDtmf(String tones, [int duration, int interToneGap]) native;
+  void insertDtmf(String tones, [int? duration, int? interToneGap]) native;
 
   /// Stream of `tonechange` events handled by this [RtcDtmfSender].
   Stream<RtcDtmfToneChangeEvent> get onToneChange =>
@@ -25425,7 +27037,7 @@
       type,
       eventInitDict);
 
-  final String tone;
+  String get tone => JS("String", "#.tone", this);
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25444,11 +27056,23 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String candidate;
+  String get candidate => JS("String", "#.candidate", this);
 
-  int sdpMLineIndex;
+  set candidate(String value) {
+    JS("void", "#.candidate = #", this, value);
+  }
 
-  String sdpMid;
+  int get sdpMLineIndex => JS("int", "#.sdpMLineIndex", this);
+
+  set sdpMLineIndex(int value) {
+    JS("void", "#.sdpMLineIndex = #", this, value);
+  }
+
+  String get sdpMid => JS("String", "#.sdpMid", this);
+
+  set sdpMid(String value) {
+    JS("void", "#.sdpMid = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25461,13 +27085,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
   DateTime get timestamp => convertNativeToDart_DateTime(this._get_timestamp);
   @JSName('timestamp')
   final dynamic _get_timestamp;
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
   List<String> names() native;
 
@@ -25606,23 +27230,23 @@
   static const EventStreamProvider<Event> signalingStateChangeEvent =
       const EventStreamProvider<Event>('signalingstatechange');
 
-  final String iceConnectionState;
+  String get iceConnectionState => JS("String", "#.iceConnectionState", this);
 
-  final String iceGatheringState;
+  String get iceGatheringState => JS("String", "#.iceGatheringState", this);
 
-  final RtcSessionDescription localDescription;
+  final RtcSessionDescription? localDescription;
 
-  final RtcSessionDescription remoteDescription;
+  final RtcSessionDescription? remoteDescription;
 
-  final String signalingState;
+  String get signalingState => JS("String", "#.signalingState", this);
 
   Future addIceCandidate(Object candidate,
-          [VoidCallback successCallback,
-          RtcPeerConnectionErrorCallback failureCallback]) =>
+          [VoidCallback? successCallback,
+          RtcPeerConnectionErrorCallback? failureCallback]) =>
       promiseToFuture(JS("", "#.addIceCandidate(#, #, #)", this, candidate,
           successCallback, failureCallback));
 
-  void addStream(MediaStream stream, [Map mediaConstraints]) {
+  void addStream(MediaStream? stream, [Map? mediaConstraints]) {
     if (mediaConstraints != null) {
       var mediaConstraints_1 = convertDartToNative_Dictionary(mediaConstraints);
       _addStream_1(stream, mediaConstraints_1);
@@ -25633,15 +27257,15 @@
   }
 
   @JSName('addStream')
-  void _addStream_1(MediaStream stream, mediaConstraints) native;
+  void _addStream_1(MediaStream? stream, mediaConstraints) native;
   @JSName('addStream')
-  void _addStream_2(MediaStream stream) native;
+  void _addStream_2(MediaStream? stream) native;
 
   RtcRtpSender addTrack(MediaStreamTrack track, MediaStream streams) native;
 
   void close() native;
 
-  Future<RtcSessionDescription> createAnswer([Map options]) {
+  Future<RtcSessionDescription> createAnswer([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -25653,7 +27277,7 @@
   @JSName('createDTMFSender')
   RtcDtmfSender createDtmfSender(MediaStreamTrack track) native;
 
-  RtcDataChannel createDataChannel(String label, [Map dataChannelDict]) {
+  RtcDataChannel createDataChannel(String label, [Map? dataChannelDict]) {
     if (dataChannelDict != null) {
       var dataChannelDict_1 = convertDartToNative_Dictionary(dataChannelDict);
       return _createDataChannel_1(label, dataChannelDict_1);
@@ -25666,7 +27290,7 @@
   @JSName('createDataChannel')
   RtcDataChannel _createDataChannel_2(label) native;
 
-  Future<RtcSessionDescription> createOffer([Map options]) {
+  Future<RtcSessionDescription> createOffer([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -25686,7 +27310,7 @@
   Future<RtcStatsReport> getStats() =>
       promiseToFuture<RtcStatsReport>(JS("", "#.getStats()", this));
 
-  void removeStream(MediaStream stream) native;
+  void removeStream(MediaStream? stream) native;
 
   void removeTrack(RtcRtpSender sender) native;
 
@@ -25749,7 +27373,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory RtcPeerConnectionIceEvent(String type, [Map eventInitDict]) {
+  factory RtcPeerConnectionIceEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return RtcPeerConnectionIceEvent._create_1(type, eventInitDict_1);
@@ -25764,7 +27388,7 @@
   static RtcPeerConnectionIceEvent _create_2(type) =>
       JS('RtcPeerConnectionIceEvent', 'new RTCPeerConnectionIceEvent(#)', type);
 
-  final RtcIceCandidate candidate;
+  final RtcIceCandidate? candidate;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25777,9 +27401,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int source;
+  int get source => JS("int", "#.source", this);
 
-  final num timestamp;
+  num get timestamp => JS("num", "#.timestamp", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25792,7 +27416,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final MediaStreamTrack track;
+  MediaStreamTrack get track => JS("MediaStreamTrack", "#.track", this);
 
   List<RtcRtpContributingSource> getContributingSources() native;
 }
@@ -25807,7 +27431,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final MediaStreamTrack track;
+  final MediaStreamTrack? track;
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25826,9 +27450,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String sdp;
+  String? sdp;
 
-  String type;
+  String? type;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25931,11 +27555,11 @@
   static RtcTrackEvent _create_1(type, eventInitDict) =>
       JS('RtcTrackEvent', 'new RTCTrackEvent(#,#)', type, eventInitDict);
 
-  final RtcRtpReceiver receiver;
+  RtcRtpReceiver get receiver => JS("RtcRtpReceiver", "#.receiver", this);
 
-  final List<MediaStream> streams;
+  List<MediaStream> get streams => JS("List<MediaStream>", "#.streams", this);
 
-  final MediaStreamTrack track;
+  MediaStreamTrack get track => JS("MediaStreamTrack", "#.track", this);
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25951,28 +27575,33 @@
   }
 
   @JSName('availHeight')
-  final int _availHeight;
+  int get _availHeight => JS("int", "#.availHeight", this);
 
   @JSName('availLeft')
-  final int _availLeft;
+  int get _availLeft => JS("int", "#.availLeft", this);
 
   @JSName('availTop')
-  final int _availTop;
+  int get _availTop => JS("int", "#.availTop", this);
 
   @JSName('availWidth')
-  final int _availWidth;
+  int get _availWidth => JS("int", "#.availWidth", this);
 
-  final int colorDepth;
+  int get colorDepth => JS("int", "#.colorDepth", this);
 
-  final int height;
+  int get height => JS("int", "#.height", this);
 
-  bool keepAwake;
+  bool get keepAwake => JS("bool", "#.keepAwake", this);
 
-  final ScreenOrientation orientation;
+  set keepAwake(bool value) {
+    JS("void", "#.keepAwake = #", this, value);
+  }
 
-  final int pixelDepth;
+  ScreenOrientation get orientation =>
+      JS("ScreenOrientation", "#.orientation", this);
 
-  final int width;
+  int get pixelDepth => JS("int", "#.pixelDepth", this);
+
+  int get width => JS("int", "#.width", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -25988,9 +27617,9 @@
   static const EventStreamProvider<Event> changeEvent =
       const EventStreamProvider<Event>('change');
 
-  final int angle;
+  int get angle => JS("int", "#.angle", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
   Future lock(String orientation) =>
       promiseToFuture(JS("", "#.lock(#)", this, orientation));
@@ -26010,7 +27639,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ScriptElement() => JS(
+  factory ScriptElement() => JS<ScriptElement>(
       'returns:ScriptElement;creates:ScriptElement;new:true',
       '#.createElement(#)',
       document,
@@ -26022,21 +27651,49 @@
    */
   ScriptElement.created() : super.created();
 
-  bool async;
+  bool get async => JS("bool", "#.async", this);
 
-  String charset;
+  set async(bool value) {
+    JS("void", "#.async = #", this, value);
+  }
 
-  String crossOrigin;
+  String get charset => JS("String", "#.charset", this);
 
-  bool defer;
+  set charset(String value) {
+    JS("void", "#.charset = #", this, value);
+  }
 
-  String integrity;
+  String? crossOrigin;
 
-  bool noModule;
+  bool get defer => JS("bool", "#.defer", this);
 
-  String src;
+  set defer(bool value) {
+    JS("void", "#.defer = #", this, value);
+  }
 
-  String type;
+  String get integrity => JS("String", "#.integrity", this);
+
+  set integrity(String value) {
+    JS("void", "#.integrity = #", this, value);
+  }
+
+  bool get noModule => JS("bool", "#.noModule", this);
+
+  set noModule(bool value) {
+    JS("void", "#.noModule = #", this, value);
+  }
+
+  String get src => JS("String", "#.src", this);
+
+  set src(String value) {
+    JS("void", "#.src = #", this, value);
+  }
+
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -26049,7 +27706,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ScrollState([Map scrollStateInit]) {
+  factory ScrollState([Map? scrollStateInit]) {
     if (scrollStateInit != null) {
       var scrollStateInit_1 = convertDartToNative_Dictionary(scrollStateInit);
       return ScrollState._create_1(scrollStateInit_1);
@@ -26060,29 +27717,29 @@
       JS('ScrollState', 'new ScrollState(#)', scrollStateInit);
   static ScrollState _create_2() => JS('ScrollState', 'new ScrollState()');
 
-  final num deltaGranularity;
+  num get deltaGranularity => JS("num", "#.deltaGranularity", this);
 
-  final num deltaX;
+  num get deltaX => JS("num", "#.deltaX", this);
 
-  final num deltaY;
+  num get deltaY => JS("num", "#.deltaY", this);
 
-  final bool fromUserInput;
+  bool get fromUserInput => JS("bool", "#.fromUserInput", this);
 
-  final bool inInertialPhase;
+  bool get inInertialPhase => JS("bool", "#.inInertialPhase", this);
 
-  final bool isBeginning;
+  bool get isBeginning => JS("bool", "#.isBeginning", this);
 
-  final bool isDirectManipulation;
+  bool get isDirectManipulation => JS("bool", "#.isDirectManipulation", this);
 
-  final bool isEnding;
+  bool get isEnding => JS("bool", "#.isEnding", this);
 
-  final int positionX;
+  int get positionX => JS("int", "#.positionX", this);
 
-  final int positionY;
+  int get positionY => JS("int", "#.positionY", this);
 
-  final num velocityX;
+  num get velocityX => JS("num", "#.velocityX", this);
 
-  final num velocityY;
+  num get velocityY => JS("num", "#.velocityY", this);
 
   void consumeDelta(num x, num y) native;
 
@@ -26106,7 +27763,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ScrollTimeline([Map options]) {
+  factory ScrollTimeline([Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return ScrollTimeline._create_1(options_1);
@@ -26118,11 +27775,11 @@
   static ScrollTimeline _create_2() =>
       JS('ScrollTimeline', 'new ScrollTimeline()');
 
-  final String orientation;
+  String get orientation => JS("String", "#.orientation", this);
 
-  final Element scrollSource;
+  final Element? scrollSource;
 
-  final Object timeRange;
+  Object get timeRange => JS("Object", "#.timeRange", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -26135,7 +27792,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory SecurityPolicyViolationEvent(String type, [Map eventInitDict]) {
+  factory SecurityPolicyViolationEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return SecurityPolicyViolationEvent._create_1(type, eventInitDict_1);
@@ -26153,30 +27810,30 @@
       type);
 
   @JSName('blockedURI')
-  final String blockedUri;
+  String get blockedUri => JS("String", "#.blockedURI", this);
 
-  final int columnNumber;
+  int get columnNumber => JS("int", "#.columnNumber", this);
 
-  final String disposition;
+  String get disposition => JS("String", "#.disposition", this);
 
   @JSName('documentURI')
-  final String documentUri;
+  String get documentUri => JS("String", "#.documentURI", this);
 
-  final String effectiveDirective;
+  String get effectiveDirective => JS("String", "#.effectiveDirective", this);
 
-  final int lineNumber;
+  int get lineNumber => JS("int", "#.lineNumber", this);
 
-  final String originalPolicy;
+  String get originalPolicy => JS("String", "#.originalPolicy", this);
 
-  final String referrer;
+  String get referrer => JS("String", "#.referrer", this);
 
-  final String sample;
+  String get sample => JS("String", "#.sample", this);
 
-  final String sourceFile;
+  String get sourceFile => JS("String", "#.sourceFile", this);
 
-  final int statusCode;
+  int get statusCode => JS("int", "#.statusCode", this);
 
-  final String violatedDirective;
+  String get violatedDirective => JS("String", "#.violatedDirective", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -26189,7 +27846,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory SelectElement() => JS(
+  factory SelectElement() => JS<SelectElement>(
       'returns:SelectElement;creates:SelectElement;new:true',
       '#.createElement(#)',
       document,
@@ -26201,42 +27858,78 @@
    */
   SelectElement.created() : super.created();
 
-  bool autofocus;
+  bool get autofocus => JS("bool", "#.autofocus", this);
 
-  bool disabled;
+  set autofocus(bool value) {
+    JS("void", "#.autofocus = #", this, value);
+  }
 
-  final FormElement form;
+  bool get disabled => JS("bool", "#.disabled", this);
+
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
+
+  final FormElement? form;
 
   @Unstable()
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  final List<Node> labels;
+  List<Node> get labels => JS("NodeList", "#.labels", this);
 
-  int length;
+  int get length => JS("int", "#.length", this);
 
-  bool multiple;
+  set length(int value) {
+    JS("void", "#.length = #", this, value);
+  }
 
-  String name;
+  bool get multiple => JS("bool", "#.multiple", this);
 
-  bool required;
+  set multiple(bool value) {
+    JS("void", "#.multiple = #", this, value);
+  }
 
-  int selectedIndex;
+  String get name => JS("String", "#.name", this);
 
-  int size;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
-  final String type;
+  bool get required => JS("bool", "#.required", this);
 
-  final String validationMessage;
+  set required(bool value) {
+    JS("void", "#.required = #", this, value);
+  }
 
-  final ValidityState validity;
+  int get selectedIndex => JS("int", "#.selectedIndex", this);
 
-  String value;
+  set selectedIndex(int value) {
+    JS("void", "#.selectedIndex = #", this, value);
+  }
 
-  final bool willValidate;
+  int get size => JS("int", "#.size", this);
 
-  void __setter__(int index, OptionElement option) native;
+  set size(int value) {
+    JS("void", "#.size = #", this, value);
+  }
 
-  void add(Object element, Object before) native;
+  String get type => JS("String", "#.type", this);
+
+  String get validationMessage => JS("String", "#.validationMessage", this);
+
+  ValidityState get validity => JS("ValidityState", "#.validity", this);
+
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
+
+  bool get willValidate => JS("bool", "#.willValidate", this);
+
+  void __setter__(int index, OptionElement? option) native;
+
+  void add(Object element, Object? before) native;
 
   bool checkValidity() native;
 
@@ -26276,43 +27969,43 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Node anchorNode;
+  final Node? anchorNode;
 
-  final int anchorOffset;
+  int get anchorOffset => JS("int", "#.anchorOffset", this);
 
-  final Node baseNode;
+  final Node? baseNode;
 
-  final int baseOffset;
+  int get baseOffset => JS("int", "#.baseOffset", this);
 
-  final Node extentNode;
+  final Node? extentNode;
 
-  final int extentOffset;
+  int get extentOffset => JS("int", "#.extentOffset", this);
 
-  final Node focusNode;
+  final Node? focusNode;
 
-  final int focusOffset;
+  int get focusOffset => JS("int", "#.focusOffset", this);
 
-  final bool isCollapsed;
+  bool get isCollapsed => JS("bool", "#.isCollapsed", this);
 
-  final int rangeCount;
+  int get rangeCount => JS("int", "#.rangeCount", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
   void addRange(Range range) native;
 
-  void collapse(Node node, [int offset]) native;
+  void collapse(Node? node, [int? offset]) native;
 
   void collapseToEnd() native;
 
   void collapseToStart() native;
 
-  bool containsNode(Node node, [bool allowPartialContainment]) native;
+  bool containsNode(Node node, [bool? allowPartialContainment]) native;
 
   void deleteFromDocument() native;
 
   void empty() native;
 
-  void extend(Node node, [int offset]) native;
+  void extend(Node node, [int? offset]) native;
 
   Range getRangeAt(int index) native;
 
@@ -26324,10 +28017,10 @@
 
   void selectAllChildren(Node node) native;
 
-  void setBaseAndExtent(
-      Node baseNode, int baseOffset, Node extentNode, int extentOffset) native;
+  void setBaseAndExtent(Node? baseNode, int baseOffset, Node? extentNode,
+      int extentOffset) native;
 
-  void setPosition(Node node, [int offset]) native;
+  void setPosition(Node? node, [int? offset]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -26343,11 +28036,11 @@
   static const EventStreamProvider<Event> errorEvent =
       const EventStreamProvider<Event>('error');
 
-  final bool activated;
+  bool get activated => JS("bool", "#.activated", this);
 
-  final bool hasReading;
+  bool get hasReading => JS("bool", "#.hasReading", this);
 
-  final num timestamp;
+  num get timestamp => JS("num", "#.timestamp", this);
 
   void start() native;
 
@@ -26373,7 +28066,7 @@
   static SensorErrorEvent _create_1(type, eventInitDict) =>
       JS('SensorErrorEvent', 'new SensorErrorEvent(#,#)', type, eventInitDict);
 
-  final DomException error;
+  DomException get error => JS("DomException", "#.error", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -26390,11 +28083,11 @@
       const EventStreamProvider<Event>('error');
 
   @JSName('scriptURL')
-  final String scriptUrl;
+  String get scriptUrl => JS("String", "#.scriptURL", this);
 
-  final String state;
+  String get state => JS("String", "#.state", this);
 
-  void postMessage(/*any*/ message, [List<Object> transfer]) {
+  void postMessage(/*any*/ message, [List<Object>? transfer]) {
     if (transfer != null) {
       var message_1 = convertDartToNative_SerializedScriptValue(message);
       _postMessage_1(message_1, transfer);
@@ -26426,19 +28119,18 @@
   static const EventStreamProvider<MessageEvent> messageEvent =
       const EventStreamProvider<MessageEvent>('message');
 
-  final ServiceWorker controller;
+  final ServiceWorker? controller;
 
-  Future<ServiceWorkerRegistration> get ready =>
-      promiseToFuture<ServiceWorkerRegistration>(JS("", "#.ready", this));
+  Future get ready => JS("Future", "#.ready", this);
 
-  Future<ServiceWorkerRegistration> getRegistration([String documentURL]) =>
+  Future<ServiceWorkerRegistration> getRegistration([String? documentURL]) =>
       promiseToFuture<ServiceWorkerRegistration>(
           JS("", "#.getRegistration(#)", this, documentURL));
 
   Future<List<dynamic>> getRegistrations() =>
       promiseToFuture<List<dynamic>>(JS("", "#.getRegistrations()", this));
 
-  Future<ServiceWorkerRegistration> register(String url, [Map options]) {
+  Future<ServiceWorkerRegistration> register(String url, [Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -26475,9 +28167,10 @@
   static const EventStreamProvider<MessageEvent> messageEvent =
       const EventStreamProvider<MessageEvent>('message');
 
-  final Clients clients;
+  Clients get clients => JS("Clients", "#.clients", this);
 
-  final ServiceWorkerRegistration registration;
+  ServiceWorkerRegistration get registration =>
+      JS("ServiceWorkerRegistration", "#.registration", this);
 
   Future skipWaiting() => promiseToFuture(JS("", "#.skipWaiting()", this));
 
@@ -26508,25 +28201,28 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final ServiceWorker active;
+  final ServiceWorker? active;
 
-  final BackgroundFetchManager backgroundFetch;
+  BackgroundFetchManager get backgroundFetch =>
+      JS("BackgroundFetchManager", "#.backgroundFetch", this);
 
-  final ServiceWorker installing;
+  final ServiceWorker? installing;
 
-  final NavigationPreloadManager navigationPreload;
+  NavigationPreloadManager get navigationPreload =>
+      JS("NavigationPreloadManager", "#.navigationPreload", this);
 
-  final PaymentManager paymentManager;
+  PaymentManager get paymentManager =>
+      JS("PaymentManager", "#.paymentManager", this);
 
-  final PushManager pushManager;
+  PushManager get pushManager => JS("PushManager", "#.pushManager", this);
 
-  final String scope;
+  String get scope => JS("String", "#.scope", this);
 
-  final SyncManager sync;
+  SyncManager get sync => JS("SyncManager", "#.sync", this);
 
-  final ServiceWorker waiting;
+  final ServiceWorker? waiting;
 
-  Future<List<dynamic>> getNotifications([Map filter]) {
+  Future<List<dynamic>> getNotifications([Map? filter]) {
     var filter_dict = null;
     if (filter != null) {
       filter_dict = convertDartToNative_Dictionary(filter);
@@ -26535,7 +28231,7 @@
         JS("", "#.getNotifications(#)", this, filter_dict));
   }
 
-  Future showNotification(String title, [Map options]) {
+  Future showNotification(String title, [Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -26561,7 +28257,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ShadowElement() => document.createElement("shadow");
+  factory ShadowElement() => document.createElement("shadow") as ShadowElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -26590,28 +28286,34 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool delegatesFocus;
+  bool get delegatesFocus => JS("bool", "#.delegatesFocus", this);
 
-  final Element host;
+  Element get host => JS("Element", "#.host", this);
 
   @JSName('innerHTML')
-  String innerHtml;
+  String get innerHtml => JS("String", "#.innerHTML", this);
 
-  final String mode;
+  @JSName('innerHTML')
+  set innerHtml(String value) {
+    JS("void", "#.innerHTML = #", this, value);
+  }
 
-  final ShadowRoot olderShadowRoot;
+  String get mode => JS("String", "#.mode", this);
+
+  final ShadowRoot? olderShadowRoot;
 
   // From DocumentOrShadowRoot
 
-  final Element activeElement;
+  final Element? activeElement;
 
-  final Element fullscreenElement;
+  final Element? fullscreenElement;
 
-  final Element pointerLockElement;
+  final Element? pointerLockElement;
 
   @Returns('_StyleSheetList|Null')
   @Creates('_StyleSheetList')
-  final List<StyleSheet> styleSheets;
+  List<StyleSheet> get styleSheets =>
+      JS("_StyleSheetList", "#.styleSheets", this);
 
   Element elementFromPoint(int x, int y) native;
 
@@ -26670,7 +28372,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int byteLength;
+  int get byteLength => JS("int", "#.byteLength", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -26686,7 +28388,7 @@
   static const EventStreamProvider<Event> errorEvent =
       const EventStreamProvider<Event>('error');
 
-  factory SharedWorker(String scriptURL, [String name]) {
+  factory SharedWorker(String scriptURL, [String? name]) {
     if (name != null) {
       return SharedWorker._create_1(scriptURL, name);
     }
@@ -26697,7 +28399,7 @@
   static SharedWorker _create_2(scriptURL) =>
       JS('SharedWorker', 'new SharedWorker(#)', scriptURL);
 
-  final MessagePort port;
+  MessagePort get port => JS("MessagePort", "#.port", this);
 
   Stream<Event> get onError => errorEvent.forTarget(this);
 }
@@ -26725,7 +28427,7 @@
 
   static const int TEMPORARY = 0;
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
   void close() native;
 
@@ -26733,8 +28435,8 @@
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
   void _webkitRequestFileSystem(int type, int size,
-      [_FileSystemCallback successCallback,
-      _ErrorCallback errorCallback]) native;
+      [_FileSystemCallback? successCallback,
+      _ErrorCallback? errorCallback]) native;
 
   @JSName('webkitRequestFileSystemSync')
   @SupportedBrowser(SupportedBrowser.CHROME)
@@ -26751,7 +28453,7 @@
   @SupportedBrowser(SupportedBrowser.SAFARI)
   void _webkitResolveLocalFileSystemUrl(
       String url, _EntryCallback successCallback,
-      [_ErrorCallback errorCallback]) native;
+      [_ErrorCallback? errorCallback]) native;
 
   /// Stream of `connect` events handled by this [SharedWorkerGlobalScope].
   Stream<Event> get onConnect => connectEvent.forTarget(this);
@@ -26778,9 +28480,13 @@
    */
   SlotElement.created() : super.created();
 
-  String name;
+  String get name => JS("String", "#.name", this);
 
-  List<Node> assignedNodes([Map options]) {
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
+
+  List<Node> assignedNodes([Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return _assignedNodes_1(options_1);
@@ -26810,23 +28516,44 @@
   static const EventStreamProvider<Event> errorEvent =
       const EventStreamProvider<Event>('error');
 
-  num appendWindowEnd;
+  num get appendWindowEnd => JS("num", "#.appendWindowEnd", this);
 
-  num appendWindowStart;
+  set appendWindowEnd(num value) {
+    JS("void", "#.appendWindowEnd = #", this, value);
+  }
 
-  final AudioTrackList audioTracks;
+  num get appendWindowStart => JS("num", "#.appendWindowStart", this);
 
-  final TimeRanges buffered;
+  set appendWindowStart(num value) {
+    JS("void", "#.appendWindowStart = #", this, value);
+  }
 
-  String mode;
+  AudioTrackList get audioTracks => JS("AudioTrackList", "#.audioTracks", this);
 
-  num timestampOffset;
+  TimeRanges get buffered => JS("TimeRanges", "#.buffered", this);
 
-  TrackDefaultList trackDefaults;
+  String get mode => JS("String", "#.mode", this);
 
-  final bool updating;
+  set mode(String value) {
+    JS("void", "#.mode = #", this, value);
+  }
 
-  final VideoTrackList videoTracks;
+  num get timestampOffset => JS("num", "#.timestampOffset", this);
+
+  set timestampOffset(num value) {
+    JS("void", "#.timestampOffset = #", this, value);
+  }
+
+  TrackDefaultList get trackDefaults =>
+      JS("TrackDefaultList", "#.trackDefaults", this);
+
+  set trackDefaults(TrackDefaultList value) {
+    JS("void", "#.trackDefaults = #", this, value);
+  }
+
+  bool get updating => JS("bool", "#.updating", this);
+
+  VideoTrackList get videoTracks => JS("VideoTrackList", "#.videoTracks", this);
 
   void abort() native;
 
@@ -26912,7 +28639,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory SourceElement() => JS(
+  factory SourceElement() => JS<SourceElement>(
       'returns:SourceElement;creates:SourceElement;new:true',
       '#.createElement(#)',
       document,
@@ -26924,15 +28651,35 @@
    */
   SourceElement.created() : super.created();
 
-  String media;
+  String get media => JS("String", "#.media", this);
 
-  String sizes;
+  set media(String value) {
+    JS("void", "#.media = #", this, value);
+  }
 
-  String src;
+  String get sizes => JS("String", "#.sizes", this);
 
-  String srcset;
+  set sizes(String value) {
+    JS("void", "#.sizes = #", this, value);
+  }
 
-  String type;
+  String get src => JS("String", "#.src", this);
+
+  set src(String value) {
+    JS("void", "#.src = #", this, value);
+  }
+
+  String get srcset => JS("String", "#.srcset", this);
+
+  set srcset(String value) {
+    JS("void", "#.srcset = #", this, value);
+  }
+
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -26945,7 +28692,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory SpanElement() => JS(
+  factory SpanElement() => JS<SpanElement>(
       'returns:SpanElement;creates:SpanElement;new:true',
       '#.createElement(#)',
       document,
@@ -26974,9 +28721,17 @@
   static SpeechGrammar _create_1() =>
       JS('SpeechGrammar', 'new SpeechGrammar()');
 
-  String src;
+  String get src => JS("String", "#.src", this);
 
-  num weight;
+  set src(String value) {
+    JS("void", "#.src = #", this, value);
+  }
+
+  num get weight => JS("num", "#.weight", this);
+
+  set weight(num value) {
+    JS("void", "#.weight = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27042,9 +28797,9 @@
   SpeechGrammar elementAt(int index) => this[index];
   // -- end List<SpeechGrammar> mixins.
 
-  void addFromString(String string, [num weight]) native;
+  void addFromString(String string, [num? weight]) native;
 
-  void addFromUri(String src, [num weight]) native;
+  void addFromUri(String src, [num? weight]) native;
 
   SpeechGrammar item(int index) native;
 }
@@ -27163,17 +28918,37 @@
   static bool get supported => JS(
       'bool', '!!(window.SpeechRecognition || window.webkitSpeechRecognition)');
 
-  MediaStreamTrack audioTrack;
+  MediaStreamTrack? audioTrack;
 
-  bool continuous;
+  bool get continuous => JS("bool", "#.continuous", this);
 
-  SpeechGrammarList grammars;
+  set continuous(bool value) {
+    JS("void", "#.continuous = #", this, value);
+  }
 
-  bool interimResults;
+  SpeechGrammarList get grammars => JS("SpeechGrammarList", "#.grammars", this);
 
-  String lang;
+  set grammars(SpeechGrammarList value) {
+    JS("void", "#.grammars = #", this, value);
+  }
 
-  int maxAlternatives;
+  bool get interimResults => JS("bool", "#.interimResults", this);
+
+  set interimResults(bool value) {
+    JS("void", "#.interimResults = #", this, value);
+  }
+
+  String get lang => JS("String", "#.lang", this);
+
+  set lang(String value) {
+    JS("void", "#.lang = #", this, value);
+  }
+
+  int get maxAlternatives => JS("int", "#.maxAlternatives", this);
+
+  set maxAlternatives(int value) {
+    JS("void", "#.maxAlternatives = #", this, value);
+  }
 
   void abort() native;
 
@@ -27231,9 +29006,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num confidence;
+  num get confidence => JS("num", "#.confidence", this);
 
-  final String transcript;
+  String get transcript => JS("String", "#.transcript", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27247,7 +29022,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory SpeechRecognitionError(String type, [Map initDict]) {
+  factory SpeechRecognitionError(String type, [Map? initDict]) {
     if (initDict != null) {
       var initDict_1 = convertDartToNative_Dictionary(initDict);
       return SpeechRecognitionError._create_1(type, initDict_1);
@@ -27262,9 +29037,9 @@
   static SpeechRecognitionError _create_2(type) =>
       JS('SpeechRecognitionError', 'new SpeechRecognitionError(#)', type);
 
-  final String error;
+  String get error => JS("String", "#.error", this);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27278,7 +29053,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory SpeechRecognitionEvent(String type, [Map initDict]) {
+  factory SpeechRecognitionEvent(String type, [Map? initDict]) {
     if (initDict != null) {
       var initDict_1 = convertDartToNative_Dictionary(initDict);
       return SpeechRecognitionEvent._create_1(type, initDict_1);
@@ -27293,15 +29068,15 @@
   static SpeechRecognitionEvent _create_2(type) =>
       JS('SpeechRecognitionEvent', 'new SpeechRecognitionEvent(#)', type);
 
-  final Document emma;
+  final Document? emma;
 
-  final Document interpretation;
+  final Document? interpretation;
 
-  final int resultIndex;
+  int get resultIndex => JS("int", "#.resultIndex", this);
 
   @Returns('_SpeechRecognitionResultList|Null')
   @Creates('_SpeechRecognitionResultList')
-  final List<SpeechRecognitionResult> results;
+  final List<SpeechRecognitionResult>? results;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27315,9 +29090,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool isFinal;
+  bool get isFinal => JS("bool", "#.isFinal", this);
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
   SpeechRecognitionAlternative item(int index) native;
 }
@@ -27338,11 +29113,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool paused;
+  bool get paused => JS("bool", "#.paused", this);
 
-  final bool pending;
+  bool get pending => JS("bool", "#.pending", this);
 
-  final bool speaking;
+  bool get speaking => JS("bool", "#.speaking", this);
 
   void cancel() native;
 
@@ -27366,13 +29141,14 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int charIndex;
+  int get charIndex => JS("int", "#.charIndex", this);
 
-  final num elapsedTime;
+  num get elapsedTime => JS("num", "#.elapsedTime", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
-  final SpeechSynthesisUtterance utterance;
+  SpeechSynthesisUtterance get utterance =>
+      JS("SpeechSynthesisUtterance", "#.utterance", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27448,7 +29224,7 @@
   static const EventStreamProvider<SpeechSynthesisEvent> startEvent =
       const EventStreamProvider<SpeechSynthesisEvent>('start');
 
-  factory SpeechSynthesisUtterance([String text]) {
+  factory SpeechSynthesisUtterance([String? text]) {
     if (text != null) {
       return SpeechSynthesisUtterance._create_1(text);
     }
@@ -27459,17 +29235,37 @@
   static SpeechSynthesisUtterance _create_2() =>
       JS('SpeechSynthesisUtterance', 'new SpeechSynthesisUtterance()');
 
-  String lang;
+  String get lang => JS("String", "#.lang", this);
 
-  num pitch;
+  set lang(String value) {
+    JS("void", "#.lang = #", this, value);
+  }
 
-  num rate;
+  num get pitch => JS("num", "#.pitch", this);
 
-  String text;
+  set pitch(num value) {
+    JS("void", "#.pitch = #", this, value);
+  }
 
-  SpeechSynthesisVoice voice;
+  num get rate => JS("num", "#.rate", this);
 
-  num volume;
+  set rate(num value) {
+    JS("void", "#.rate = #", this, value);
+  }
+
+  String get text => JS("String", "#.text", this);
+
+  set text(String value) {
+    JS("void", "#.text = #", this, value);
+  }
+
+  SpeechSynthesisVoice? voice;
+
+  num get volume => JS("num", "#.volume", this);
+
+  set volume(num value) {
+    JS("void", "#.volume = #", this, value);
+  }
 
   /// Stream of `boundary` events handled by this [SpeechSynthesisUtterance].
   Stream<SpeechSynthesisEvent> get onBoundary => boundaryEvent.forTarget(this);
@@ -27504,16 +29300,16 @@
   }
 
   @JSName('default')
-  final bool defaultValue;
+  bool get defaultValue => JS("bool", "#.default", this);
 
-  final String lang;
+  String get lang => JS("String", "#.lang", this);
 
-  final bool localService;
+  bool get localService => JS("bool", "#.localService", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
   @JSName('voiceURI')
-  final String voiceUri;
+  String get voiceUri => JS("String", "#.voiceURI", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27526,15 +29322,15 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool collapsed;
+  bool get collapsed => JS("bool", "#.collapsed", this);
 
-  final Node endContainer;
+  Node get endContainer => JS("Node", "#.endContainer", this);
 
-  final int endOffset;
+  int get endOffset => JS("int", "#.endOffset", this);
 
-  final Node startContainer;
+  Node get startContainer => JS("Node", "#.startContainer", this);
 
-  final int startOffset;
+  int get startOffset => JS("int", "#.startOffset", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27575,11 +29371,11 @@
   }
 
   // TODO(nweiz): update this when maps support lazy iteration
-  bool containsValue(Object value) => values.any((e) => e == value);
+  bool containsValue(Object? value) => values.any((e) => e == value);
 
-  bool containsKey(Object key) => _getItem(key) != null;
+  bool containsKey(Object? key) => _getItem(key) != null;
 
-  String operator [](Object key) => _getItem(key);
+  String? operator [](Object? key) => _getItem(key as String);
 
   void operator []=(String key, String value) {
     _setItem(key, value);
@@ -27590,7 +29386,7 @@
     return this[key];
   }
 
-  String remove(Object key) {
+  String? remove(Object? key) {
     final value = this[key];
     _removeItem(key);
     return value;
@@ -27630,7 +29426,7 @@
   }
 
   @JSName('length')
-  final int _length;
+  int get _length => JS("int", "#.length", this);
 
   @JSName('clear')
   void _clear() native;
@@ -27677,7 +29473,7 @@
     return e;
   }
 
-  factory StorageEvent._(String type, [Map eventInitDict]) {
+  factory StorageEvent._(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return StorageEvent._create_1(type, eventInitDict_1);
@@ -27689,15 +29485,15 @@
   static StorageEvent _create_2(type) =>
       JS('StorageEvent', 'new StorageEvent(#)', type);
 
-  final String key;
+  final String? key;
 
-  final String newValue;
+  final String? newValue;
 
-  final String oldValue;
+  final String? oldValue;
 
-  final Storage storageArea;
+  final Storage? storageArea;
 
-  final String url;
+  String get url => JS("String", "#.url", this);
 
   @JSName('initStorageEvent')
   void _initStorageEvent(
@@ -27705,8 +29501,8 @@
       bool canBubbleArg,
       bool cancelableArg,
       String keyArg,
-      String oldValueArg,
-      String newValueArg,
+      String? oldValueArg,
+      String? newValueArg,
       String urlArg,
       Storage storageAreaArg) native;
 }
@@ -27755,7 +29551,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory StyleElement() => JS(
+  factory StyleElement() => JS<StyleElement>(
       'returns:StyleElement;creates:StyleElement;new:true',
       '#.createElement(#)',
       document,
@@ -27767,13 +29563,25 @@
    */
   StyleElement.created() : super.created();
 
-  bool disabled;
+  bool get disabled => JS("bool", "#.disabled", this);
 
-  String media;
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
 
-  final StyleSheet sheet;
+  String get media => JS("String", "#.media", this);
 
-  String type;
+  set media(String value) {
+    JS("void", "#.media = #", this, value);
+  }
+
+  final StyleSheet? sheet;
+
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27786,7 +29594,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
   bool matchMedium(String mediaquery) native;
 }
@@ -27837,19 +29645,23 @@
     throw new UnsupportedError("Not supported");
   }
 
-  bool disabled;
+  bool get disabled => JS("bool", "#.disabled", this);
 
-  final String href;
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
 
-  final MediaList media;
+  final String? href;
 
-  final Node ownerNode;
+  MediaList get media => JS("MediaList", "#.media", this);
 
-  final StyleSheet parentStyleSheet;
+  final Node? ownerNode;
 
-  final String title;
+  final StyleSheet? parentStyleSheet;
 
-  final String type;
+  final String? title;
+
+  String get type => JS("String", "#.type", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27869,9 +29681,9 @@
   static SyncEvent _create_1(type, init) =>
       JS('SyncEvent', 'new SyncEvent(#,#)', type, init);
 
-  final bool lastChance;
+  bool get lastChance => JS("bool", "#.lastChance", this);
 
-  final String tag;
+  String get tag => JS("String", "#.tag", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27901,7 +29713,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TableCaptionElement() => JS(
+  factory TableCaptionElement() => JS<TableCaptionElement>(
       'returns:TableCaptionElement;creates:TableCaptionElement;new:true',
       '#.createElement(#)',
       document,
@@ -27925,7 +29737,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TableCellElement() => JS(
+  factory TableCellElement() => JS<TableCellElement>(
       'returns:TableCellElement;creates:TableCellElement;new:true',
       '#.createElement(#)',
       document,
@@ -27937,13 +29749,25 @@
    */
   TableCellElement.created() : super.created();
 
-  final int cellIndex;
+  int get cellIndex => JS("int", "#.cellIndex", this);
 
-  int colSpan;
+  int get colSpan => JS("int", "#.colSpan", this);
 
-  String headers;
+  set colSpan(int value) {
+    JS("void", "#.colSpan = #", this, value);
+  }
 
-  int rowSpan;
+  String get headers => JS("String", "#.headers", this);
+
+  set headers(String value) {
+    JS("void", "#.headers = #", this, value);
+  }
+
+  int get rowSpan => JS("int", "#.rowSpan", this);
+
+  set rowSpan(int value) {
+    JS("void", "#.rowSpan = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -27956,7 +29780,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TableColElement() => JS(
+  factory TableColElement() => JS<TableColElement>(
       'returns:TableColElement;creates:TableColElement;new:true',
       '#.createElement(#)',
       document,
@@ -27968,7 +29792,11 @@
    */
   TableColElement.created() : super.created();
 
-  int span;
+  int get span => JS("int", "#.span", this);
+
+  set span(int value) {
+    JS("void", "#.span = #", this, value);
+  }
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -28024,7 +29852,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TableElement() => JS(
+  factory TableElement() => JS<TableElement>(
       'returns:TableElement;creates:TableElement;new:true',
       '#.createElement(#)',
       document,
@@ -28036,21 +29864,21 @@
    */
   TableElement.created() : super.created();
 
-  TableCaptionElement caption;
+  TableCaptionElement? caption;
 
   @JSName('rows')
   @Returns('HtmlCollection|Null')
   @Creates('HtmlCollection')
-  final List<Node> _rows;
+  List<Node> get _rows => JS("HtmlCollection", "#.rows", this);
 
   @JSName('tBodies')
   @Returns('HtmlCollection|Null')
   @Creates('HtmlCollection')
-  final List<Node> _tBodies;
+  List<Node> get _tBodies => JS("HtmlCollection", "#.tBodies", this);
 
-  TableSectionElement tFoot;
+  TableSectionElement? tFoot;
 
-  TableSectionElement tHead;
+  TableSectionElement? tHead;
 
   @JSName('createCaption')
   TableCaptionElement _createCaption() native;
@@ -28070,7 +29898,7 @@
   void deleteTHead() native;
 
   @JSName('insertRow')
-  TableRowElement _insertRow([int index]) native;
+  TableRowElement _insertRow([int? index]) native;
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -28110,7 +29938,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TableRowElement() => JS(
+  factory TableRowElement() => JS<TableRowElement>(
       'returns:TableRowElement;creates:TableRowElement;new:true',
       '#.createElement(#)',
       document,
@@ -28125,16 +29953,16 @@
   @JSName('cells')
   @Returns('HtmlCollection|Null')
   @Creates('HtmlCollection')
-  final List<Node> _cells;
+  List<Node> get _cells => JS("HtmlCollection", "#.cells", this);
 
-  final int rowIndex;
+  int get rowIndex => JS("int", "#.rowIndex", this);
 
-  final int sectionRowIndex;
+  int get sectionRowIndex => JS("int", "#.sectionRowIndex", this);
 
   void deleteCell(int index) native;
 
   @JSName('insertCell')
-  HtmlElement _insertCell([int index]) native;
+  HtmlElement _insertCell([int? index]) native;
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -28181,12 +30009,12 @@
   @JSName('rows')
   @Returns('HtmlCollection|Null')
   @Creates('HtmlCollection')
-  final List<Node> _rows;
+  List<Node> get _rows => JS("HtmlCollection", "#.rows", this);
 
   void deleteRow(int index) native;
 
   @JSName('insertRow')
-  HtmlElement _insertRow([int index]) native;
+  HtmlElement _insertRow([int? index]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -28199,16 +30027,16 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String containerId;
+  String get containerId => JS("String", "#.containerId", this);
 
-  final String containerName;
+  String get containerName => JS("String", "#.containerName", this);
 
-  final String containerSrc;
+  String get containerSrc => JS("String", "#.containerSrc", this);
 
-  final String containerType;
+  String get containerType => JS("String", "#.containerType", this);
 
   @JSName('scriptURL')
-  final String scriptUrl;
+  String get scriptUrl => JS("String", "#.scriptURL", this);
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -28224,7 +30052,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TemplateElement() => document.createElement("template");
+  factory TemplateElement() =>
+      document.createElement("template") as TemplateElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -28235,7 +30064,7 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('template');
 
-  final DocumentFragment content;
+  DocumentFragment get content => JS("DocumentFragment", "#.content", this);
 
   /**
    * An override to place the contents into content rather than as child nodes.
@@ -28272,9 +30101,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final SlotElement assignedSlot;
+  final SlotElement? assignedSlot;
 
-  final String wholeText;
+  String get wholeText => JS("String", "#.wholeText", this);
 
   @Returns('NodeList|Null')
   @Creates('NodeList')
@@ -28293,7 +30122,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TextAreaElement() => JS(
+  factory TextAreaElement() => JS<TextAreaElement>(
       'returns:TextAreaElement;creates:TextAreaElement;new:true',
       '#.createElement(#)',
       document,
@@ -28305,58 +30134,130 @@
    */
   TextAreaElement.created() : super.created();
 
-  String autocapitalize;
+  String get autocapitalize => JS("String", "#.autocapitalize", this);
 
-  bool autofocus;
+  set autocapitalize(String value) {
+    JS("void", "#.autocapitalize = #", this, value);
+  }
 
-  int cols;
+  bool get autofocus => JS("bool", "#.autofocus", this);
 
-  String defaultValue;
+  set autofocus(bool value) {
+    JS("void", "#.autofocus = #", this, value);
+  }
 
-  String dirName;
+  int get cols => JS("int", "#.cols", this);
 
-  bool disabled;
+  set cols(int value) {
+    JS("void", "#.cols = #", this, value);
+  }
 
-  final FormElement form;
+  String get defaultValue => JS("String", "#.defaultValue", this);
+
+  set defaultValue(String value) {
+    JS("void", "#.defaultValue = #", this, value);
+  }
+
+  String get dirName => JS("String", "#.dirName", this);
+
+  set dirName(String value) {
+    JS("void", "#.dirName = #", this, value);
+  }
+
+  bool get disabled => JS("bool", "#.disabled", this);
+
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
+
+  final FormElement? form;
 
   @Unstable()
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  final List<Node> labels;
+  List<Node> get labels => JS("NodeList", "#.labels", this);
 
-  int maxLength;
+  int get maxLength => JS("int", "#.maxLength", this);
 
-  int minLength;
+  set maxLength(int value) {
+    JS("void", "#.maxLength = #", this, value);
+  }
 
-  String name;
+  int get minLength => JS("int", "#.minLength", this);
 
-  String placeholder;
+  set minLength(int value) {
+    JS("void", "#.minLength = #", this, value);
+  }
 
-  bool readOnly;
+  String get name => JS("String", "#.name", this);
 
-  bool required;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
-  int rows;
+  String get placeholder => JS("String", "#.placeholder", this);
 
-  String selectionDirection;
+  set placeholder(String value) {
+    JS("void", "#.placeholder = #", this, value);
+  }
 
-  int selectionEnd;
+  bool get readOnly => JS("bool", "#.readOnly", this);
 
-  int selectionStart;
+  set readOnly(bool value) {
+    JS("void", "#.readOnly = #", this, value);
+  }
 
-  final int textLength;
+  bool get required => JS("bool", "#.required", this);
 
-  final String type;
+  set required(bool value) {
+    JS("void", "#.required = #", this, value);
+  }
 
-  final String validationMessage;
+  int get rows => JS("int", "#.rows", this);
 
-  final ValidityState validity;
+  set rows(int value) {
+    JS("void", "#.rows = #", this, value);
+  }
 
-  String value;
+  String get selectionDirection => JS("String", "#.selectionDirection", this);
 
-  final bool willValidate;
+  set selectionDirection(String value) {
+    JS("void", "#.selectionDirection = #", this, value);
+  }
 
-  String wrap;
+  int get selectionEnd => JS("int", "#.selectionEnd", this);
+
+  set selectionEnd(int value) {
+    JS("void", "#.selectionEnd = #", this, value);
+  }
+
+  int get selectionStart => JS("int", "#.selectionStart", this);
+
+  set selectionStart(int value) {
+    JS("void", "#.selectionStart = #", this, value);
+  }
+
+  int get textLength => JS("int", "#.textLength", this);
+
+  String get type => JS("String", "#.type", this);
+
+  String get validationMessage => JS("String", "#.validationMessage", this);
+
+  ValidityState get validity => JS("ValidityState", "#.validity", this);
+
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
+
+  bool get willValidate => JS("bool", "#.willValidate", this);
+
+  String get wrap => JS("String", "#.wrap", this);
+
+  set wrap(String value) {
+    JS("void", "#.wrap = #", this, value);
+  }
 
   bool checkValidity() native;
 
@@ -28367,9 +30268,9 @@
   void setCustomValidity(String error) native;
 
   void setRangeText(String replacement,
-      {int start, int end, String selectionMode}) native;
+      {int? start, int? end, String? selectionMode}) native;
 
-  void setSelectionRange(int start, int end, [String direction]) native;
+  void setSelectionRange(int start, int end, [String? direction]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -28416,10 +30317,10 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String data;
+  String get data => JS("String", "#.data", this);
 
   @JSName('initTextEvent')
-  void _initTextEvent(String type, bool bubbles, bool cancelable, Window view,
+  void _initTextEvent(String type, bool bubbles, bool cancelable, Window? view,
       String data) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
@@ -28433,29 +30334,31 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num actualBoundingBoxAscent;
+  num get actualBoundingBoxAscent =>
+      JS("num", "#.actualBoundingBoxAscent", this);
 
-  final num actualBoundingBoxDescent;
+  num get actualBoundingBoxDescent =>
+      JS("num", "#.actualBoundingBoxDescent", this);
 
-  final num actualBoundingBoxLeft;
+  num get actualBoundingBoxLeft => JS("num", "#.actualBoundingBoxLeft", this);
 
-  final num actualBoundingBoxRight;
+  num get actualBoundingBoxRight => JS("num", "#.actualBoundingBoxRight", this);
 
-  final num alphabeticBaseline;
+  num get alphabeticBaseline => JS("num", "#.alphabeticBaseline", this);
 
-  final num emHeightAscent;
+  num get emHeightAscent => JS("num", "#.emHeightAscent", this);
 
-  final num emHeightDescent;
+  num get emHeightDescent => JS("num", "#.emHeightDescent", this);
 
-  final num fontBoundingBoxAscent;
+  num get fontBoundingBoxAscent => JS("num", "#.fontBoundingBoxAscent", this);
 
-  final num fontBoundingBoxDescent;
+  num get fontBoundingBoxDescent => JS("num", "#.fontBoundingBoxDescent", this);
 
-  final num hangingBaseline;
+  num get hangingBaseline => JS("num", "#.hangingBaseline", this);
 
-  final num ideographicBaseline;
+  num get ideographicBaseline => JS("num", "#.ideographicBaseline", this);
 
-  final num width;
+  num get width => JS("num", "#.width", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -28477,19 +30380,23 @@
   static const EventStreamProvider<Event> cueChangeEvent =
       const EventStreamProvider<Event>('cuechange');
 
-  final TextTrackCueList activeCues;
+  final TextTrackCueList? activeCues;
 
-  final TextTrackCueList cues;
+  final TextTrackCueList? cues;
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
-  final String kind;
+  String get kind => JS("String", "#.kind", this);
 
-  final String label;
+  String get label => JS("String", "#.label", this);
 
-  final String language;
+  String get language => JS("String", "#.language", this);
 
-  String mode;
+  String get mode => JS("String", "#.mode", this);
+
+  set mode(String value) {
+    JS("void", "#.mode = #", this, value);
+  }
 
   void addCue(TextTrackCue cue) native;
 
@@ -28527,15 +30434,31 @@
   static const EventStreamProvider<Event> exitEvent =
       const EventStreamProvider<Event>('exit');
 
-  num endTime;
+  num get endTime => JS("num", "#.endTime", this);
 
-  String id;
+  set endTime(num value) {
+    JS("void", "#.endTime = #", this, value);
+  }
 
-  bool pauseOnExit;
+  String get id => JS("String", "#.id", this);
 
-  num startTime;
+  set id(String value) {
+    JS("void", "#.id = #", this, value);
+  }
 
-  final TextTrack track;
+  bool get pauseOnExit => JS("bool", "#.pauseOnExit", this);
+
+  set pauseOnExit(bool value) {
+    JS("void", "#.pauseOnExit = #", this, value);
+  }
+
+  num get startTime => JS("num", "#.startTime", this);
+
+  set startTime(num value) {
+    JS("void", "#.startTime = #", this, value);
+  }
+
+  final TextTrack? track;
 
   /// Stream of `enter` events handled by this [TextTrackCue].
   Stream<Event> get onEnter => enterEvent.forTarget(this);
@@ -28701,7 +30624,11 @@
    */
   TimeElement.created() : super.created();
 
-  String dateTime;
+  String get dateTime => JS("String", "#.dateTime", this);
+
+  set dateTime(String value) {
+    JS("void", "#.dateTime = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -28715,7 +30642,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
   double end(int index) native;
 
@@ -28739,7 +30666,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TitleElement() => JS(
+  factory TitleElement() => JS<TitleElement>(
       'returns:TitleElement;creates:TitleElement;new:true',
       '#.createElement(#)',
       document,
@@ -28769,38 +30696,38 @@
   static Touch _create_1(initDict) => JS('Touch', 'new Touch(#)', initDict);
 
   @JSName('clientX')
-  final num _clientX;
+  num get _clientX => JS("num", "#.clientX", this);
 
   @JSName('clientY')
-  final num _clientY;
+  num get _clientY => JS("num", "#.clientY", this);
 
-  final num force;
+  num get force => JS("num", "#.force", this);
 
-  final int identifier;
+  int get identifier => JS("int", "#.identifier", this);
 
   @JSName('pageX')
-  final num _pageX;
+  num get _pageX => JS("num", "#.pageX", this);
 
   @JSName('pageY')
-  final num _pageY;
+  num get _pageY => JS("num", "#.pageY", this);
 
   @JSName('radiusX')
-  final num _radiusX;
+  num get _radiusX => JS("num", "#.radiusX", this);
 
   @JSName('radiusY')
-  final num _radiusY;
+  num get _radiusY => JS("num", "#.radiusY", this);
 
-  final String region;
+  final String? region;
 
-  final num rotationAngle;
+  num get rotationAngle => JS("num", "#.rotationAngle", this);
 
   @JSName('screenX')
-  final num _screenX;
+  num get _screenX => JS("num", "#.screenX", this);
 
   @JSName('screenY')
-  final num _screenY;
+  num get _screenY => JS("num", "#.screenY", this);
 
-  EventTarget get target => _convertNativeToDart_EventTarget(this._get_target);
+  EventTarget? get target => _convertNativeToDart_EventTarget(this._get_target);
   @JSName('target')
   @Creates('Element|Document')
   @Returns('Element|Document')
@@ -28844,7 +30771,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TouchEvent(String type, [Map eventInitDict]) {
+  factory TouchEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return TouchEvent._create_1(type, eventInitDict_1);
@@ -28856,19 +30783,19 @@
   static TouchEvent _create_2(type) =>
       JS('TouchEvent', 'new TouchEvent(#)', type);
 
-  final bool altKey;
+  bool get altKey => JS("bool", "#.altKey", this);
 
-  final TouchList changedTouches;
+  TouchList get changedTouches => JS("TouchList", "#.changedTouches", this);
 
-  final bool ctrlKey;
+  bool get ctrlKey => JS("bool", "#.ctrlKey", this);
 
-  final bool metaKey;
+  bool get metaKey => JS("bool", "#.metaKey", this);
 
-  final bool shiftKey;
+  bool get shiftKey => JS("bool", "#.shiftKey", this);
 
-  final TouchList targetTouches;
+  TouchList get targetTouches => JS("TouchList", "#.targetTouches", this);
 
-  final TouchList touches;
+  TouchList get touches => JS("TouchList", "#.touches", this);
 
   /**
    * Checks if touch events supported on the current platform.
@@ -28964,7 +30891,7 @@
 
   factory TrackDefault(
       String type, String language, String label, List<String> kinds,
-      [String byteStreamTrackID]) {
+      [String? byteStreamTrackID]) {
     if (byteStreamTrackID != null) {
       List kinds_1 = convertDartToNative_StringArray(kinds);
       return TrackDefault._create_1(
@@ -28985,15 +30912,15 @@
       label,
       kinds);
 
-  final String byteStreamTrackID;
+  String get byteStreamTrackID => JS("String", "#.byteStreamTrackID", this);
 
-  final Object kinds;
+  Object get kinds => JS("Object", "#.kinds", this);
 
-  final String label;
+  String get label => JS("String", "#.label", this);
 
-  final String language;
+  String get language => JS("String", "#.language", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29006,7 +30933,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TrackDefaultList([List<TrackDefault> trackDefaults]) {
+  factory TrackDefaultList([List<TrackDefault>? trackDefaults]) {
     if (trackDefaults != null) {
       return TrackDefaultList._create_1(trackDefaults);
     }
@@ -29017,7 +30944,7 @@
   static TrackDefaultList _create_2() =>
       JS('TrackDefaultList', 'new TrackDefaultList()');
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
   TrackDefault item(int index) native;
 }
@@ -29035,7 +30962,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TrackElement() => document.createElement("track");
+  factory TrackElement() => document.createElement("track") as TrackElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -29055,19 +30982,40 @@
   static const int NONE = 0;
 
   @JSName('default')
-  bool defaultValue;
+  bool get defaultValue => JS("bool", "#.default", this);
 
-  String kind;
+  @JSName('default')
+  set defaultValue(bool value) {
+    JS("void", "#.default = #", this, value);
+  }
 
-  String label;
+  String get kind => JS("String", "#.kind", this);
 
-  final int readyState;
+  set kind(String value) {
+    JS("void", "#.kind = #", this, value);
+  }
 
-  String src;
+  String get label => JS("String", "#.label", this);
 
-  String srclang;
+  set label(String value) {
+    JS("void", "#.label = #", this, value);
+  }
 
-  final TextTrack track;
+  int get readyState => JS("int", "#.readyState", this);
+
+  String get src => JS("String", "#.src", this);
+
+  set src(String value) {
+    JS("void", "#.src = #", this, value);
+  }
+
+  String get srclang => JS("String", "#.srclang", this);
+
+  set srclang(String value) {
+    JS("void", "#.srclang = #", this, value);
+  }
+
+  TextTrack get track => JS("TextTrack", "#.track", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29081,7 +31029,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TrackEvent(String type, [Map eventInitDict]) {
+  factory TrackEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return TrackEvent._create_1(type, eventInitDict_1);
@@ -29094,7 +31042,7 @@
       JS('TrackEvent', 'new TrackEvent(#)', type);
 
   @Creates('Null')
-  final Object track;
+  final Object? track;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29107,7 +31055,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory TransitionEvent(String type, [Map eventInitDict]) {
+  factory TransitionEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return TransitionEvent._create_1(type, eventInitDict_1);
@@ -29119,11 +31067,11 @@
   static TransitionEvent _create_2(type) =>
       JS('TransitionEvent', 'new TransitionEvent(#)', type);
 
-  final num elapsedTime;
+  num get elapsedTime => JS("num", "#.elapsedTime", this);
 
-  final String propertyName;
+  String get propertyName => JS("String", "#.propertyName", this);
 
-  final String pseudoElement;
+  String get pseudoElement => JS("String", "#.pseudoElement", this);
 }
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29140,13 +31088,17 @@
     throw new UnsupportedError("Not supported");
   }
 
-  Node currentNode;
+  Node get currentNode => JS("Node", "#.currentNode", this);
 
-  final NodeFilter filter;
+  set currentNode(Node value) {
+    JS("void", "#.currentNode = #", this, value);
+  }
 
-  final Node root;
+  final NodeFilter? filter;
 
-  final int whatToShow;
+  Node get root => JS("Node", "#.root", this);
+
+  int get whatToShow => JS("int", "#.whatToShow", this);
 
   Node firstChild() native;
 
@@ -29232,7 +31184,7 @@
     return e;
   }
 
-  factory UIEvent._(String type, [Map eventInitDict]) {
+  factory UIEvent._(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return UIEvent._create_1(type, eventInitDict_1);
@@ -29243,11 +31195,11 @@
       JS('UIEvent', 'new UIEvent(#,#)', type, eventInitDict);
   static UIEvent _create_2(type) => JS('UIEvent', 'new UIEvent(#)', type);
 
-  final int detail;
+  int get detail => JS("int", "#.detail", this);
 
-  final InputDeviceCapabilities sourceCapabilities;
+  final InputDeviceCapabilities? sourceCapabilities;
 
-  WindowBase get view => _convertNativeToDart_Window(this._get_view);
+  WindowBase? get view => _convertNativeToDart_Window(this._get_view);
   @JSName('view')
   @Creates('Window|=Object')
   @Returns('Window|=Object')
@@ -29255,10 +31207,10 @@
 
   @JSName('which')
   @Unstable()
-  final int _which;
+  int get _which => JS("int", "#.which", this);
 
   @JSName('initUIEvent')
-  void _initUIEvent(String type, bool bubbles, bool cancelable, Window view,
+  void _initUIEvent(String type, bool bubbles, bool cancelable, Window? view,
       int detail) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
@@ -29272,7 +31224,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory UListElement() => JS(
+  factory UListElement() => JS<UListElement>(
       'returns:UListElement;creates:UListElement;new:true',
       '#.createElement(#)',
       document,
@@ -29354,29 +31306,70 @@
     throw new UnsupportedError("Not supported");
   }
 
-  String hash;
+  String get hash => JS("String", "#.hash", this);
 
-  String host;
+  set hash(String value) {
+    JS("void", "#.hash = #", this, value);
+  }
 
-  String hostname;
+  String get host => JS("String", "#.host", this);
 
-  String href;
+  set host(String value) {
+    JS("void", "#.host = #", this, value);
+  }
 
-  final String origin;
+  String get hostname => JS("String", "#.hostname", this);
 
-  String password;
+  set hostname(String value) {
+    JS("void", "#.hostname = #", this, value);
+  }
 
-  String pathname;
+  String get href => JS("String", "#.href", this);
 
-  String port;
+  set href(String value) {
+    JS("void", "#.href = #", this, value);
+  }
 
-  String protocol;
+  String get origin => JS("String", "#.origin", this);
 
-  String search;
+  String get password => JS("String", "#.password", this);
 
-  final UrlSearchParams searchParams;
+  set password(String value) {
+    JS("void", "#.password = #", this, value);
+  }
 
-  String username;
+  String get pathname => JS("String", "#.pathname", this);
+
+  set pathname(String value) {
+    JS("void", "#.pathname = #", this, value);
+  }
+
+  String get port => JS("String", "#.port", this);
+
+  set port(String value) {
+    JS("void", "#.port = #", this, value);
+  }
+
+  String get protocol => JS("String", "#.protocol", this);
+
+  set protocol(String value) {
+    JS("void", "#.protocol = #", this, value);
+  }
+
+  String get search => JS("String", "#.search", this);
+
+  set search(String value) {
+    JS("void", "#.search = #", this, value);
+  }
+
+  UrlSearchParams get searchParams =>
+      JS("UrlSearchParams", "#.searchParams", this);
+
+  String get username => JS("String", "#.username", this);
+
+  set username(String value) {
+    JS("void", "#.username = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29389,7 +31382,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory UrlSearchParams([Object init]) {
+  factory UrlSearchParams([Object? init]) {
     if (init != null) {
       return UrlSearchParams._create_1(init);
     }
@@ -29479,11 +31472,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String deviceName;
+  String get deviceName => JS("String", "#.deviceName", this);
 
-  final bool isExternal;
+  bool get isExternal => JS("bool", "#.isExternal", this);
 
-  Future requestSession([Map options]) {
+  Future requestSession([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -29491,7 +31484,7 @@
     return promiseToFuture(JS("", "#.requestSession(#)", this, options_dict));
   }
 
-  Future supportsSession([Map options]) {
+  Future supportsSession([Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -29517,7 +31510,7 @@
   static VRDeviceEvent _create_1(type, eventInitDict) =>
       JS('VRDeviceEvent', 'new VRDeviceEvent(#,#)', type, eventInitDict);
 
-  final VRDevice device;
+  VRDevice get device => JS("VRDevice", "#.device", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29530,19 +31523,29 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final VRDisplayCapabilities capabilities;
+  VRDisplayCapabilities get capabilities =>
+      JS("VRDisplayCapabilities", "#.capabilities", this);
 
-  num depthFar;
+  num get depthFar => JS("num", "#.depthFar", this);
 
-  num depthNear;
+  set depthFar(num value) {
+    JS("void", "#.depthFar = #", this, value);
+  }
 
-  final int displayId;
+  num get depthNear => JS("num", "#.depthNear", this);
 
-  final String displayName;
+  set depthNear(num value) {
+    JS("void", "#.depthNear = #", this, value);
+  }
 
-  final bool isPresenting;
+  int get displayId => JS("int", "#.displayId", this);
 
-  final VRStageParameters stageParameters;
+  String get displayName => JS("String", "#.displayName", this);
+
+  bool get isPresenting => JS("bool", "#.isPresenting", this);
+
+  VRStageParameters get stageParameters =>
+      JS("VRStageParameters", "#.stageParameters", this);
 
   void cancelAnimationFrame(int handle) native;
 
@@ -29572,13 +31575,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool canPresent;
+  bool get canPresent => JS("bool", "#.canPresent", this);
 
-  final bool hasExternalDisplay;
+  bool get hasExternalDisplay => JS("bool", "#.hasExternalDisplay", this);
 
-  final bool hasPosition;
+  bool get hasPosition => JS("bool", "#.hasPosition", this);
 
-  final int maxLayers;
+  int get maxLayers => JS("int", "#.maxLayers", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29591,7 +31594,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory VRDisplayEvent(String type, [Map eventInitDict]) {
+  factory VRDisplayEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return VRDisplayEvent._create_1(type, eventInitDict_1);
@@ -29603,9 +31606,9 @@
   static VRDisplayEvent _create_2(type) =>
       JS('VRDisplayEvent', 'new VRDisplayEvent(#)', type);
 
-  final VRDisplay display;
+  VRDisplay get display => JS("VRDisplay", "#.display", this);
 
-  final String reason;
+  String get reason => JS("String", "#.reason", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29618,11 +31621,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Float32List offset;
+  Float32List get offset => JS("Float32List", "#.offset", this);
 
-  final int renderHeight;
+  int get renderHeight => JS("int", "#.renderHeight", this);
 
-  final int renderWidth;
+  int get renderWidth => JS("int", "#.renderWidth", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29640,15 +31643,18 @@
   }
   static VRFrameData _create_1() => JS('VRFrameData', 'new VRFrameData()');
 
-  final Float32List leftProjectionMatrix;
+  Float32List get leftProjectionMatrix =>
+      JS("Float32List", "#.leftProjectionMatrix", this);
 
-  final Float32List leftViewMatrix;
+  Float32List get leftViewMatrix => JS("Float32List", "#.leftViewMatrix", this);
 
-  final VRPose pose;
+  VRPose get pose => JS("VRPose", "#.pose", this);
 
-  final Float32List rightProjectionMatrix;
+  Float32List get rightProjectionMatrix =>
+      JS("Float32List", "#.rightProjectionMatrix", this);
 
-  final Float32List rightViewMatrix;
+  Float32List get rightViewMatrix =>
+      JS("Float32List", "#.rightViewMatrix", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29661,9 +31667,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final VRStageBounds bounds;
+  final VRStageBounds? bounds;
 
-  final num emulatedHeight;
+  num get emulatedHeight => JS("num", "#.emulatedHeight", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29676,17 +31682,17 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Float32List angularAcceleration;
+  final Float32List? angularAcceleration;
 
-  final Float32List angularVelocity;
+  final Float32List? angularVelocity;
 
-  final Float32List linearAcceleration;
+  final Float32List? linearAcceleration;
 
-  final Float32List linearVelocity;
+  final Float32List? linearVelocity;
 
-  final Float32List orientation;
+  final Float32List? orientation;
 
-  final Float32List position;
+  final Float32List? position;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29705,17 +31711,25 @@
   static const EventStreamProvider<Event> focusEvent =
       const EventStreamProvider<Event>('focus');
 
-  num depthFar;
+  num get depthFar => JS("num", "#.depthFar", this);
 
-  num depthNear;
+  set depthFar(num value) {
+    JS("void", "#.depthFar = #", this, value);
+  }
 
-  final VRDevice device;
+  num get depthNear => JS("num", "#.depthNear", this);
 
-  final bool exclusive;
+  set depthNear(num value) {
+    JS("void", "#.depthNear = #", this, value);
+  }
+
+  VRDevice get device => JS("VRDevice", "#.device", this);
+
+  bool get exclusive => JS("bool", "#.exclusive", this);
 
   Future end() => promiseToFuture(JS("", "#.end()", this));
 
-  Future requestFrameOfReference(String type, [Map options]) {
+  Future requestFrameOfReference(String type, [Map? options]) {
     var options_dict = null;
     if (options != null) {
       options_dict = convertDartToNative_Dictionary(options);
@@ -29746,7 +31760,7 @@
   static VRSessionEvent _create_1(type, eventInitDict) =>
       JS('VRSessionEvent', 'new VRSessionEvent(#,#)', type, eventInitDict);
 
-  final VRSession session;
+  VRSession get session => JS("VRSession", "#.session", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29759,7 +31773,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final List<VRStageBoundsPoint> geometry;
+  List<VRStageBoundsPoint> get geometry =>
+      JS("List<VRStageBoundsPoint>", "#.geometry", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29772,9 +31787,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num x;
+  num get x => JS("num", "#.x", this);
 
-  final num z;
+  num get z => JS("num", "#.z", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29787,11 +31802,12 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Float32List sittingToStandingTransform;
+  Float32List get sittingToStandingTransform =>
+      JS("Float32List", "#.sittingToStandingTransform", this);
 
-  final num sizeX;
+  num get sizeX => JS("num", "#.sizeX", this);
 
-  final num sizeZ;
+  num get sizeZ => JS("num", "#.sizeZ", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29804,27 +31820,27 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool badInput;
+  bool get badInput => JS("bool", "#.badInput", this);
 
-  final bool customError;
+  bool get customError => JS("bool", "#.customError", this);
 
-  final bool patternMismatch;
+  bool get patternMismatch => JS("bool", "#.patternMismatch", this);
 
-  final bool rangeOverflow;
+  bool get rangeOverflow => JS("bool", "#.rangeOverflow", this);
 
-  final bool rangeUnderflow;
+  bool get rangeUnderflow => JS("bool", "#.rangeUnderflow", this);
 
-  final bool stepMismatch;
+  bool get stepMismatch => JS("bool", "#.stepMismatch", this);
 
-  final bool tooLong;
+  bool get tooLong => JS("bool", "#.tooLong", this);
 
-  final bool tooShort;
+  bool get tooShort => JS("bool", "#.tooShort", this);
 
-  final bool typeMismatch;
+  bool get typeMismatch => JS("bool", "#.typeMismatch", this);
 
-  final bool valid;
+  bool get valid => JS("bool", "#.valid", this);
 
-  final bool valueMissing;
+  bool get valueMissing => JS("bool", "#.valueMissing", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29837,7 +31853,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory VideoElement() => JS(
+  factory VideoElement() => JS<VideoElement>(
       'returns:VideoElement;creates:VideoElement;new:true',
       '#.createElement(#)',
       document,
@@ -29849,25 +31865,37 @@
    */
   VideoElement.created() : super.created();
 
-  int height;
+  int get height => JS("int", "#.height", this);
 
-  String poster;
+  set height(int value) {
+    JS("void", "#.height = #", this, value);
+  }
 
-  final int videoHeight;
+  String get poster => JS("String", "#.poster", this);
 
-  final int videoWidth;
+  set poster(String value) {
+    JS("void", "#.poster = #", this, value);
+  }
+
+  int get videoHeight => JS("int", "#.videoHeight", this);
+
+  int get videoWidth => JS("int", "#.videoWidth", this);
 
   @JSName('webkitDecodedFrameCount')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final int decodedFrameCount;
+  int get decodedFrameCount => JS("int", "#.webkitDecodedFrameCount", this);
 
   @JSName('webkitDroppedFrameCount')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.SAFARI)
-  final int droppedFrameCount;
+  int get droppedFrameCount => JS("int", "#.webkitDroppedFrameCount", this);
 
-  int width;
+  int get width => JS("int", "#.width", this);
+
+  set width(int value) {
+    JS("void", "#.width = #", this, value);
+  }
 
   VideoPlaybackQuality getVideoPlaybackQuality() native;
 
@@ -29892,13 +31920,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int corruptedVideoFrames;
+  int get corruptedVideoFrames => JS("int", "#.corruptedVideoFrames", this);
 
-  final num creationTime;
+  num get creationTime => JS("num", "#.creationTime", this);
 
-  final int droppedVideoFrames;
+  int get droppedVideoFrames => JS("int", "#.droppedVideoFrames", this);
 
-  final int totalVideoFrames;
+  int get totalVideoFrames => JS("int", "#.totalVideoFrames", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29911,17 +31939,21 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String id;
+  String get id => JS("String", "#.id", this);
 
-  final String kind;
+  String get kind => JS("String", "#.kind", this);
 
-  final String label;
+  String get label => JS("String", "#.label", this);
 
-  final String language;
+  String get language => JS("String", "#.language", this);
 
-  bool selected;
+  bool get selected => JS("bool", "#.selected", this);
 
-  final SourceBuffer sourceBuffer;
+  set selected(bool value) {
+    JS("void", "#.selected = #", this, value);
+  }
+
+  final SourceBuffer? sourceBuffer;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -29937,9 +31969,9 @@
   static const EventStreamProvider<Event> changeEvent =
       const EventStreamProvider<Event>('change');
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
-  final int selectedIndex;
+  int get selectedIndex => JS("int", "#.selectedIndex", this);
 
   VideoTrack __getter__(int index) native;
 
@@ -29964,19 +31996,19 @@
   static const EventStreamProvider<Event> scrollEvent =
       const EventStreamProvider<Event>('scroll');
 
-  final num height;
+  num get height => JS("num", "#.height", this);
 
-  final num offsetLeft;
+  num get offsetLeft => JS("num", "#.offsetLeft", this);
 
-  final num offsetTop;
+  num get offsetTop => JS("num", "#.offsetTop", this);
 
-  final num pageLeft;
+  num get pageLeft => JS("num", "#.pageLeft", this);
 
-  final num pageTop;
+  num get pageTop => JS("num", "#.pageTop", this);
 
-  final num scale;
+  num get scale => JS("num", "#.scale", this);
 
-  final num width;
+  num get width => JS("num", "#.width", this);
 
   Stream<Event> get onResize => resizeEvent.forTarget(this);
 
@@ -30006,25 +32038,57 @@
   static VttCue _create_1(startTime, endTime, text) =>
       JS('VttCue', 'new VTTCue(#,#,#)', startTime, endTime, text);
 
-  String align;
+  String get align => JS("String", "#.align", this);
+
+  set align(String value) {
+    JS("void", "#.align = #", this, value);
+  }
 
   @Creates('Null')
   @Returns('num|String')
-  Object line;
+  Object get line => JS("Object", "#.line", this);
 
   @Creates('Null')
   @Returns('num|String')
-  Object position;
+  set line(Object value) {
+    JS("void", "#.line = #", this, value);
+  }
 
-  VttRegion region;
+  @Creates('Null')
+  @Returns('num|String')
+  Object get position => JS("Object", "#.position", this);
 
-  num size;
+  @Creates('Null')
+  @Returns('num|String')
+  set position(Object value) {
+    JS("void", "#.position = #", this, value);
+  }
 
-  bool snapToLines;
+  VttRegion? region;
 
-  String text;
+  num get size => JS("num", "#.size", this);
 
-  String vertical;
+  set size(num value) {
+    JS("void", "#.size = #", this, value);
+  }
+
+  bool get snapToLines => JS("bool", "#.snapToLines", this);
+
+  set snapToLines(bool value) {
+    JS("void", "#.snapToLines = #", this, value);
+  }
+
+  String get text => JS("String", "#.text", this);
+
+  set text(String value) {
+    JS("void", "#.text = #", this, value);
+  }
+
+  String get vertical => JS("String", "#.vertical", this);
+
+  set vertical(String value) {
+    JS("void", "#.vertical = #", this, value);
+  }
 
   @JSName('getCueAsHTML')
   DocumentFragment getCueAsHtml() native;
@@ -30045,21 +32109,53 @@
   }
   static VttRegion _create_1() => JS('VttRegion', 'new VTTRegion()');
 
-  String id;
+  String get id => JS("String", "#.id", this);
 
-  int lines;
+  set id(String value) {
+    JS("void", "#.id = #", this, value);
+  }
 
-  num regionAnchorX;
+  int get lines => JS("int", "#.lines", this);
 
-  num regionAnchorY;
+  set lines(int value) {
+    JS("void", "#.lines = #", this, value);
+  }
 
-  String scroll;
+  num get regionAnchorX => JS("num", "#.regionAnchorX", this);
 
-  num viewportAnchorX;
+  set regionAnchorX(num value) {
+    JS("void", "#.regionAnchorX = #", this, value);
+  }
 
-  num viewportAnchorY;
+  num get regionAnchorY => JS("num", "#.regionAnchorY", this);
 
-  num width;
+  set regionAnchorY(num value) {
+    JS("void", "#.regionAnchorY = #", this, value);
+  }
+
+  String get scroll => JS("String", "#.scroll", this);
+
+  set scroll(String value) {
+    JS("void", "#.scroll = #", this, value);
+  }
+
+  num get viewportAnchorX => JS("num", "#.viewportAnchorX", this);
+
+  set viewportAnchorX(num value) {
+    JS("void", "#.viewportAnchorX = #", this, value);
+  }
+
+  num get viewportAnchorY => JS("num", "#.viewportAnchorY", this);
+
+  set viewportAnchorY(num value) {
+    JS("void", "#.viewportAnchorY = #", this, value);
+  }
+
+  num get width => JS("num", "#.width", this);
+
+  set width(num value) {
+    JS("void", "#.width = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -30147,7 +32243,7 @@
   static const EventStreamProvider<Event> openEvent =
       const EventStreamProvider<Event>('open');
 
-  factory WebSocket(String url, [Object protocols]) {
+  factory WebSocket(String url, [Object? protocols]) {
     if (protocols != null) {
       return WebSocket._create_1(url, protocols);
     }
@@ -30169,19 +32265,23 @@
 
   static const int OPEN = 1;
 
-  String binaryType;
+  String get binaryType => JS("String", "#.binaryType", this);
 
-  final int bufferedAmount;
+  set binaryType(String value) {
+    JS("void", "#.binaryType = #", this, value);
+  }
 
-  final String extensions;
+  int get bufferedAmount => JS("int", "#.bufferedAmount", this);
 
-  final String protocol;
+  String get extensions => JS("String", "#.extensions", this);
 
-  final int readyState;
+  String get protocol => JS("String", "#.protocol", this);
 
-  final String url;
+  int get readyState => JS("int", "#.readyState", this);
 
-  void close([int code, String reason]) native;
+  String get url => JS("String", "#.url", this);
+
+  void close([int? code, String? reason]) native;
 
   /**
    * Transmit data to the server over this connection.
@@ -30298,7 +32398,7 @@
         convertDartToNative_Dictionary(options));
   }
 
-  factory WheelEvent._(String type, [Map eventInitDict]) {
+  factory WheelEvent._(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return WheelEvent._create_1(type, eventInitDict_1);
@@ -30317,12 +32417,12 @@
   static const int DOM_DELTA_PIXEL = 0x00;
 
   @JSName('deltaX')
-  final num _deltaX;
+  num get _deltaX => JS("num", "#.deltaX", this);
 
   @JSName('deltaY')
-  final num _deltaY;
+  num get _deltaY => JS("num", "#.deltaY", this);
 
-  final num deltaZ;
+  num get deltaZ => JS("num", "#.deltaZ", this);
 
   /**
    * The amount that is expected to scroll vertically, in units determined by
@@ -30821,7 +32921,7 @@
    */
   static const int TEMPORARY = 0;
 
-  final _Worklet animationWorklet;
+  _Worklet get animationWorklet => JS("_Worklet", "#.animationWorklet", this);
 
   /**
    * The application cache for this window.
@@ -30835,15 +32935,17 @@
    *   API](https://html.spec.whatwg.org/multipage/browsers.html#application-cache-api)
    *   from WHATWG.
    */
-  final ApplicationCache applicationCache;
 
-  final _Worklet audioWorklet;
+  ApplicationCache get applicationCache =>
+      JS("ApplicationCache", "#.applicationCache", this);
 
-  final CacheStorage caches;
+  _Worklet get audioWorklet => JS("_Worklet", "#.audioWorklet", this);
 
-  final bool closed;
+  CacheStorage get caches => JS("CacheStorage", "#.caches", this);
 
-  final CookieStore cookieStore;
+  bool get closed => JS("bool", "#.closed", this);
+
+  CookieStore get cookieStore => JS("CookieStore", "#.cookieStore", this);
 
   /**
    * Entrypoint for the browser's cryptographic functions.
@@ -30852,15 +32954,31 @@
    *
    * * [Web cryptography API](http://www.w3.org/TR/WebCryptoAPI/) from W3C.
    */
-  final Crypto crypto;
 
-  final CustomElementRegistry customElements;
+  Crypto get crypto => JS("Crypto", "#.crypto", this);
+
+  CustomElementRegistry get customElements =>
+      JS("CustomElementRegistry", "#.customElements", this);
 
   /// *Deprecated*.
-  String defaultStatus;
+
+  String get defaultStatus => JS("String", "#.defaultStatus", this);
 
   /// *Deprecated*.
-  String defaultstatus;
+
+  set defaultStatus(String value) {
+    JS("void", "#.defaultStatus = #", this, value);
+  }
+
+  /// *Deprecated*.
+
+  String get defaultstatus => JS("String", "#.defaultstatus", this);
+
+  /// *Deprecated*.
+
+  set defaultstatus(String value) {
+    JS("void", "#.defaultstatus = #", this, value);
+  }
 
   /**
    * The ratio between physical pixels and logical CSS pixels.
@@ -30872,9 +32990,10 @@
    * * [More about devicePixelRatio](http://www.quirksmode.org/blog/archives/2012/07/more_about_devi.html)
    *   from quirksmode.
    */
-  final num devicePixelRatio;
 
-  final External external;
+  num get devicePixelRatio => JS("num", "#.devicePixelRatio", this);
+
+  External get external => JS("External", "#.external", this);
 
   /**
    * The current session history for this window's newest document.
@@ -30884,7 +33003,8 @@
    * * [Loading web pages](https://html.spec.whatwg.org/multipage/browsers.html)
    *   from WHATWG.
    */
-  final History history;
+
+  History get history => JS("History", "#.history", this);
 
   /**
    * The height of the viewport including scrollbars.
@@ -30894,7 +33014,8 @@
    * * [Window.innerHeight](https://developer.mozilla.org/en-US/docs/Web/API/Window/innerHeight)
    *   from MDN.
    */
-  final int innerHeight;
+
+  int get innerHeight => JS("int", "#.innerHeight", this);
 
   /**
    * The width of the viewport including scrollbars.
@@ -30904,9 +33025,10 @@
    * * [Window.innerWidth](https://developer.mozilla.org/en-US/docs/Web/API/Window/innerWidth)
    *   from MDN.
    */
-  final int innerWidth;
 
-  final bool isSecureContext;
+  int get innerWidth => JS("int", "#.innerWidth", this);
+
+  bool get isSecureContext => JS("bool", "#.isSecureContext", this);
 
   /**
    * Storage for this window that persists across sessions.
@@ -30920,7 +33042,8 @@
    * * [Local storage specification](http://www.w3.org/TR/webstorage/#the-localstorage-attribute)
    *   from W3C.
    */
-  final Storage localStorage;
+
+  Storage get localStorage => JS("Storage", "#.localStorage", this);
 
   /**
    * This window's location bar, which displays the URL.
@@ -30931,7 +33054,8 @@
    *   elements](https://html.spec.whatwg.org/multipage/browsers.html#browser-interface-elements)
    *   from WHATWG.
    */
-  final BarProp locationbar;
+
+  BarProp get locationbar => JS("BarProp", "#.locationbar", this);
 
   /**
    * This window's menu bar, which displays menu commands.
@@ -30942,7 +33066,8 @@
    *   elements](https://html.spec.whatwg.org/multipage/browsers.html#browser-interface-elements)
    *   from WHATWG.
    */
-  final BarProp menubar;
+
+  BarProp get menubar => JS("BarProp", "#.menubar", this);
 
   /**
    * The name of this window.
@@ -30952,7 +33077,21 @@
    * * [Window.name](https://developer.mozilla.org/en-US/docs/Web/API/Window/name)
    *   from MDN.
    */
-  String name;
+
+  String get name => JS("String", "#.name", this);
+
+  /**
+   * The name of this window.
+   *
+   * ## Other resources
+   *
+   * * [Window.name](https://developer.mozilla.org/en-US/docs/Web/API/Window/name)
+   *   from MDN.
+   */
+
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
   /**
    * The user agent accessing this window.
@@ -30963,7 +33102,8 @@
    *   object](https://html.spec.whatwg.org/multipage/webappapis.html#the-navigator-object)
    *   from WHATWG.
    */
-  final Navigator navigator;
+
+  Navigator get navigator => JS("Navigator", "#.navigator", this);
 
   /**
    * Whether objects are drawn offscreen before being displayed.
@@ -30973,9 +33113,10 @@
    * * [offscreenBuffering](https://webplatform.github.io/docs/dom/HTMLElement/offscreenBuffering/)
    *   from WebPlatform.org.
    */
-  final bool offscreenBuffering;
 
-  WindowBase get opener => _convertNativeToDart_Window(this._get_opener);
+  bool get offscreenBuffering => JS("bool", "#.offscreenBuffering", this);
+
+  WindowBase? get opener => _convertNativeToDart_Window(this._get_opener);
   @JSName('opener')
   @Creates('Window|=Object')
   @Returns('Window|=Object')
@@ -30985,9 +33126,9 @@
     JS("void", "#.opener = #", this, value);
   }
 
-  final int orientation;
+  int get orientation => JS("int", "#.orientation", this);
 
-  final String origin;
+  String get origin => JS("String", "#.origin", this);
 
   /**
    * The height of this window including all user interface elements.
@@ -30997,7 +33138,8 @@
    * * [Window.outerHeight](https://developer.mozilla.org/en-US/docs/Web/API/Window/outerHeight)
    *   from MDN.
    */
-  final int outerHeight;
+
+  int get outerHeight => JS("int", "#.outerHeight", this);
 
   /**
    * The width of the window including all user interface elements.
@@ -31007,9 +33149,11 @@
    * * [Window.outerWidth](https://developer.mozilla.org/en-US/docs/Web/API/Window/outerWidth)
    *   from MDN.
    */
-  final int outerWidth;
+
+  int get outerWidth => JS("int", "#.outerWidth", this);
 
   @JSName('pageXOffset')
+
   /**
    * The distance this window has been scrolled horizontally.
    *
@@ -31023,9 +33167,11 @@
    *   pageXOffset](https://developer.mozilla.org/en-US/docs/Web/API/Window.scrollX)
    *   from MDN.
    */
-  final num _pageXOffset;
+
+  num get _pageXOffset => JS("num", "#.pageXOffset", this);
 
   @JSName('pageYOffset')
+
   /**
    * The distance this window has been scrolled vertically.
    *
@@ -31039,9 +33185,10 @@
    *   pageYOffset](https://developer.mozilla.org/en-US/docs/Web/API/Window.scrollY)
    *   from MDN.
    */
-  final num _pageYOffset;
 
-  WindowBase get parent => _convertNativeToDart_Window(this._get_parent);
+  num get _pageYOffset => JS("num", "#.pageYOffset", this);
+
+  WindowBase? get parent => _convertNativeToDart_Window(this._get_parent);
   @JSName('parent')
   @Creates('Window|=Object')
   @Returns('Window|=Object')
@@ -31061,7 +33208,7 @@
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.FIREFOX)
   @SupportedBrowser(SupportedBrowser.IE)
-  final Performance performance;
+  Performance get performance => JS("Performance", "#.performance", this);
 
   /**
    * Information about the screen displaying this window.
@@ -31071,7 +33218,8 @@
    * * [The Screen interface specification](http://www.w3.org/TR/cssom-view/#screen)
    *   from W3C.
    */
-  final Screen screen;
+
+  Screen get screen => JS("Screen", "#.screen", this);
 
   /**
    * The distance from the left side of the screen to the left side of this
@@ -31082,7 +33230,8 @@
    * * [The Screen interface specification](http://www.w3.org/TR/cssom-view/#screen)
    *   from W3C.
    */
-  final int screenLeft;
+
+  int get screenLeft => JS("int", "#.screenLeft", this);
 
   /**
    * The distance from the top of the screen to the top of this window.
@@ -31092,7 +33241,8 @@
    * * [The Screen interface specification](http://www.w3.org/TR/cssom-view/#screen)
    *   from W3C.
    */
-  final int screenTop;
+
+  int get screenTop => JS("int", "#.screenTop", this);
 
   /**
    * The distance from the left side of the screen to the mouse pointer.
@@ -31102,7 +33252,8 @@
    * * [The Screen interface specification](http://www.w3.org/TR/cssom-view/#screen)
    *   from W3C.
    */
-  final int screenX;
+
+  int get screenX => JS("int", "#.screenX", this);
 
   /**
    * The distance from the top of the screen to the mouse pointer.
@@ -31112,7 +33263,8 @@
    * * [The Screen interface specification](http://www.w3.org/TR/cssom-view/#screen)
    *   from W3C.
    */
-  final int screenY;
+
+  int get screenY => JS("int", "#.screenY", this);
 
   /**
    * This window's scroll bars.
@@ -31123,7 +33275,8 @@
    *   elements](https://html.spec.whatwg.org/multipage/browsers.html#browser-interface-elements)
    *   from WHATWG.
    */
-  final BarProp scrollbars;
+
+  BarProp get scrollbars => JS("BarProp", "#.scrollbars", this);
 
   /**
    * The current window.
@@ -31133,7 +33286,7 @@
    * * [Window.self](https://developer.mozilla.org/en-US/docs/Web/API/Window.self)
    *   from MDN.
    */
-  WindowBase get self => _convertNativeToDart_Window(this._get_self);
+  WindowBase? get self => _convertNativeToDart_Window(this._get_self);
   @JSName('self')
   /**
    * The current window.
@@ -31160,7 +33313,8 @@
    * * [Local storage
    *   specification](http://www.w3.org/TR/webstorage/#dom-sessionstorage) from W3C.
    */
-  final Storage sessionStorage;
+
+  Storage get sessionStorage => JS("Storage", "#.sessionStorage", this);
 
   /**
    * Access to speech synthesis in the browser.
@@ -31171,10 +33325,19 @@
    *   specification](https://dvcs.w3.org/hg/speech-api/raw-file/tip/speechapi.html#tts-section)
    *   from W3C.
    */
-  final SpeechSynthesis speechSynthesis;
+
+  SpeechSynthesis get speechSynthesis =>
+      JS("SpeechSynthesis", "#.speechSynthesis", this);
 
   /// *Deprecated*.
-  String status;
+
+  String get status => JS("String", "#.status", this);
+
+  /// *Deprecated*.
+
+  set status(String value) {
+    JS("void", "#.status = #", this, value);
+  }
 
   /**
    * This window's status bar.
@@ -31185,7 +33348,8 @@
    *   elements](https://html.spec.whatwg.org/multipage/browsers.html#browser-interface-elements)
    *   from WHATWG.
    */
-  final BarProp statusbar;
+
+  BarProp get statusbar => JS("BarProp", "#.statusbar", this);
 
   /**
    * Access to CSS media queries.
@@ -31196,7 +33360,8 @@
    *   reference](https://developer.apple.com/library/safari/documentation/SafariDOMAdditions/Reference/StyleMedia/)
    *   from Safari Developer Library.
    */
-  final StyleMedia styleMedia;
+
+  StyleMedia get styleMedia => JS("StyleMedia", "#.styleMedia", this);
 
   /**
    * This window's tool bar.
@@ -31207,15 +33372,17 @@
    *   elements](https://html.spec.whatwg.org/multipage/browsers.html#browser-interface-elements)
    *   from WHATWG.
    */
-  final BarProp toolbar;
 
-  WindowBase get top => _convertNativeToDart_Window(this._get_top);
+  BarProp get toolbar => JS("BarProp", "#.toolbar", this);
+
+  WindowBase? get top => _convertNativeToDart_Window(this._get_top);
   @JSName('top')
   @Creates('Window|=Object')
   @Returns('Window|=Object')
   final dynamic _get_top;
 
-  final VisualViewport visualViewport;
+  VisualViewport get visualViewport =>
+      JS("VisualViewport", "#.visualViewport", this);
 
   /**
    * The current window.
@@ -31225,7 +33392,7 @@
    * * [Window.window](https://developer.mozilla.org/en-US/docs/Web/API/Window.window)
    *   from MDN.
    */
-  WindowBase get window => _convertNativeToDart_Window(this._get_window);
+  WindowBase? get window => _convertNativeToDart_Window(this._get_window);
   @JSName('window')
   /**
    * The current window.
@@ -31241,7 +33408,7 @@
 
   @Creates('Window|=Object')
   @Returns('Window|=Object')
-  WindowBase __getter__(index_OR_name) {
+  WindowBase? __getter__(index_OR_name) {
     if ((index_OR_name is int)) {
       return _convertNativeToDart_Window(__getter___1(index_OR_name));
     }
@@ -31268,7 +33435,7 @@
    * * [User prompts](https://html.spec.whatwg.org/multipage/webappapis.html#user-prompts)
    *   from WHATWG.
    */
-  void alert([String message]) native;
+  void alert([String? message]) native;
 
   void cancelIdleCallback(int handle) native;
 
@@ -31282,9 +33449,9 @@
    * * [User prompts](https://html.spec.whatwg.org/multipage/webappapis.html#user-prompts)
    *   from WHATWG.
    */
-  bool confirm([String message]) native;
+  bool confirm([String? message]) native;
 
-  Future fetch(/*RequestInfo*/ input, [Map init]) {
+  Future fetch(/*RequestInfo*/ input, [Map? init]) {
     var init_dict = null;
     if (init != null) {
       init_dict = convertDartToNative_Dictionary(init);
@@ -31304,10 +33471,11 @@
       bool wholeWord, bool searchInFrames, bool showDialog) native;
 
   @JSName('getComputedStyle')
-  CssStyleDeclaration _getComputedStyle(Element elt, [String pseudoElt]) native;
+  CssStyleDeclaration _getComputedStyle(Element elt, [String? pseudoElt])
+      native;
 
   StylePropertyMapReadonly getComputedStyleMap(
-      Element element, String pseudoElement) native;
+      Element element, String? pseudoElement) native;
 
   @JSName('getMatchedCSSRules')
   /**
@@ -31315,7 +33483,7 @@
    */
   @Returns('_CssRuleList|Null')
   @Creates('_CssRuleList')
-  List<CssRule> getMatchedCssRules(Element element, String pseudoElement)
+  List<CssRule> getMatchedCssRules(Element element, String? pseudoElement)
       native;
 
   /**
@@ -31365,10 +33533,10 @@
   @Creates('SqlDatabase')
   SqlDatabase _openDatabase(
       String name, String version, String displayName, int estimatedSize,
-      [DatabaseCallback creationCallback]) native;
+      [DatabaseCallback? creationCallback]) native;
 
   void postMessage(/*any*/ message, String targetOrigin,
-      [List<Object> transfer]) {
+      [List<Object>? transfer]) {
     if (transfer != null) {
       var message_1 = convertDartToNative_SerializedScriptValue(message);
       _postMessage_1(message_1, targetOrigin, transfer);
@@ -31394,7 +33562,7 @@
    */
   void print() native;
 
-  int requestIdleCallback(IdleRequestCallback callback, [Map options]) {
+  int requestIdleCallback(IdleRequestCallback callback, [Map? options]) {
     if (options != null) {
       var callback_1 = convertDartClosureToJS(callback, 1);
       var options_2 = convertDartToNative_Dictionary(options);
@@ -31439,7 +33607,7 @@
    * * [Window.scroll](https://developer.mozilla.org/en-US/docs/Web/API/Window/scroll)
    *   from MDN.
    */
-  void scroll([options_OR_x, y, Map scrollOptions]) {
+  void scroll([options_OR_x, y, Map? scrollOptions]) {
     if (options_OR_x == null && y == null && scrollOptions == null) {
       _scroll_1();
       return;
@@ -31534,7 +33702,7 @@
    * * [Window.scrollBy](https://developer.mozilla.org/en-US/docs/Web/API/Window/scrollBy)
    *   from MDN.
    */
-  void scrollBy([options_OR_x, y, Map scrollOptions]) {
+  void scrollBy([options_OR_x, y, Map? scrollOptions]) {
     if (options_OR_x == null && y == null && scrollOptions == null) {
       _scrollBy_1();
       return;
@@ -31621,7 +33789,7 @@
    * * [Window.scrollTo](https://developer.mozilla.org/en-US/docs/Web/API/Window/scrollTo)
    *   from MDN.
    */
-  void scrollTo([options_OR_x, y, Map scrollOptions]) {
+  void scrollTo([options_OR_x, y, Map? scrollOptions]) {
     if (options_OR_x == null && y == null && scrollOptions == null) {
       _scrollTo_1();
       return;
@@ -31723,7 +33891,7 @@
   @SupportedBrowser(SupportedBrowser.CHROME)
   void __requestFileSystem(
       int type, int size, _FileSystemCallback successCallback,
-      [_ErrorCallback errorCallback]) native;
+      [_ErrorCallback? errorCallback]) native;
 
   @JSName('webkitRequestFileSystem')
   @SupportedBrowser(SupportedBrowser.CHROME)
@@ -31751,7 +33919,7 @@
    */
   @SupportedBrowser(SupportedBrowser.CHROME)
   void _resolveLocalFileSystemUrl(String url, _EntryCallback successCallback,
-      [_ErrorCallback errorCallback]) native;
+      [_ErrorCallback? errorCallback]) native;
 
   @JSName('webkitResolveLocalFileSystemURL')
   /**
@@ -31783,24 +33951,24 @@
   // From WindowTimers
 
   @JSName('setInterval')
-  int _setInterval_String(String handler, [int timeout, Object arguments])
+  int _setInterval_String(String handler, [int? timeout, Object? arguments])
       native;
 
   @JSName('setTimeout')
-  int _setTimeout_String(String handler, [int timeout, Object arguments])
+  int _setTimeout_String(String handler, [int? timeout, Object? arguments])
       native;
 
   @JSName('clearInterval')
-  void _clearInterval([int handle]) native;
+  void _clearInterval([int? handle]) native;
 
   @JSName('clearTimeout')
-  void _clearTimeout([int handle]) native;
+  void _clearTimeout([int? handle]) native;
 
   @JSName('setInterval')
-  int _setInterval(Object handler, [int timeout]) native;
+  int _setInterval(Object handler, [int? timeout]) native;
 
   @JSName('setTimeout')
-  int _setTimeout(Object handler, [int timeout]) native;
+  int _setTimeout(Object handler, [int? timeout]) native;
 
   /// Stream of `contentloaded` events handled by this [Window].
   Stream<Event> get onContentLoaded => contentLoadedEvent.forTarget(this);
@@ -32185,9 +34353,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool focused;
+  bool get focused => JS("bool", "#.focused", this);
 
-  final String visibilityState;
+  String get visibilityState => JS("String", "#.visibilityState", this);
 
   Future<WindowClient> focus() =>
       promiseToFuture<WindowClient>(JS("", "#.focus()", this));
@@ -32283,7 +34451,7 @@
   static bool get supported =>
       JS('bool', '(typeof window.Worker != "undefined")');
 
-  void postMessage(/*any*/ message, [List<Object> transfer]) {
+  void postMessage(/*any*/ message, [List<Object>? transfer]) {
     if (transfer != null) {
       var message_1 = convertDartToNative_SerializedScriptValue(message);
       _postMessage_1(message_1, transfer);
@@ -32328,27 +34496,28 @@
   static const EventStreamProvider<Event> errorEvent =
       const EventStreamProvider<Event>('error');
 
-  final String addressSpace;
+  String get addressSpace => JS("String", "#.addressSpace", this);
 
-  final CacheStorage caches;
+  CacheStorage get caches => JS("CacheStorage", "#.caches", this);
 
-  final Crypto crypto;
+  Crypto get crypto => JS("Crypto", "#.crypto", this);
 
-  final IdbFactory indexedDB;
+  IdbFactory get indexedDB => JS("IdbFactory", "#.indexedDB", this);
 
-  final bool isSecureContext;
+  bool get isSecureContext => JS("bool", "#.isSecureContext", this);
 
-  final _WorkerLocation location;
+  _WorkerLocation get location => JS("_WorkerLocation", "#.location", this);
 
-  final _WorkerNavigator navigator;
+  _WorkerNavigator get navigator => JS("_WorkerNavigator", "#.navigator", this);
 
-  final String origin;
+  String get origin => JS("String", "#.origin", this);
 
-  final WorkerPerformance performance;
+  WorkerPerformance get performance =>
+      JS("WorkerPerformance", "#.performance", this);
 
-  final WorkerGlobalScope self;
+  WorkerGlobalScope get self => JS("WorkerGlobalScope", "#.self", this);
 
-  Future fetch(/*RequestInfo*/ input, [Map init]) {
+  Future fetch(/*RequestInfo*/ input, [Map? init]) {
     var init_dict = null;
     if (init != null) {
       init_dict = convertDartToNative_Dictionary(init);
@@ -32367,24 +34536,24 @@
   // From WindowTimers
 
   @JSName('setInterval')
-  int _setInterval_String(String handler, [int timeout, Object arguments])
+  int _setInterval_String(String handler, [int? timeout, Object? arguments])
       native;
 
   @JSName('setTimeout')
-  int _setTimeout_String(String handler, [int timeout, Object arguments])
+  int _setTimeout_String(String handler, [int? timeout, Object? arguments])
       native;
 
   @JSName('clearInterval')
-  void _clearInterval([int handle]) native;
+  void _clearInterval([int? handle]) native;
 
   @JSName('clearTimeout')
-  void _clearTimeout([int handle]) native;
+  void _clearTimeout([int? handle]) native;
 
   @JSName('setInterval')
-  int _setInterval(Object handler, [int timeout]) native;
+  int _setInterval(Object handler, [int? timeout]) native;
 
   @JSName('setTimeout')
-  int _setTimeout(Object handler, [int timeout]) native;
+  int _setTimeout(Object handler, [int? timeout]) native;
 
   /// Stream of `error` events handled by this [WorkerGlobalScope].
   Stream<Event> get onError => errorEvent.forTarget(this);
@@ -32403,9 +34572,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final MemoryInfo memory;
+  MemoryInfo get memory => JS("MemoryInfo", "#.memory", this);
 
-  final num timeOrigin;
+  num get timeOrigin => JS("num", "#.timeOrigin", this);
 
   void clearMarks(String markName) native;
 
@@ -32452,7 +34621,7 @@
       JS('WorkletAnimation', 'new WorkletAnimation(#,#,#,#)', animatorName,
           effects, timelines, options);
 
-  final String playState;
+  String get playState => JS("String", "#.playState", this);
 
   void cancel() native;
 
@@ -32488,14 +34657,14 @@
   static XPathEvaluator _create_1() =>
       JS('XPathEvaluator', 'new XPathEvaluator()');
 
-  XPathExpression createExpression(String expression, XPathNSResolver resolver)
+  XPathExpression createExpression(String expression, XPathNSResolver? resolver)
       native;
 
   XPathNSResolver createNSResolver(Node nodeResolver) native;
 
   XPathResult evaluate(
-      String expression, Node contextNode, XPathNSResolver resolver,
-      [int type, Object inResult]) native;
+      String expression, Node contextNode, XPathNSResolver? resolver,
+      [int? type, Object? inResult]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -32510,7 +34679,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  XPathResult evaluate(Node contextNode, [int type, Object inResult]) native;
+  XPathResult evaluate(Node contextNode, [int? type, Object? inResult]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -32561,19 +34730,19 @@
 
   static const int UNORDERED_NODE_SNAPSHOT_TYPE = 6;
 
-  final bool booleanValue;
+  bool get booleanValue => JS("bool", "#.booleanValue", this);
 
-  final bool invalidIteratorState;
+  bool get invalidIteratorState => JS("bool", "#.invalidIteratorState", this);
 
-  final num numberValue;
+  num get numberValue => JS("num", "#.numberValue", this);
 
-  final int resultType;
+  int get resultType => JS("int", "#.resultType", this);
 
-  final Node singleNodeValue;
+  Node get singleNodeValue => JS("Node", "#.singleNodeValue", this);
 
-  final int snapshotLength;
+  int get snapshotLength => JS("int", "#.snapshotLength", this);
 
-  final String stringValue;
+  String get stringValue => JS("String", "#.stringValue", this);
 
   Node iterateNext() native;
 
@@ -32637,15 +34806,16 @@
 
   void clearParameters() native;
 
-  String getParameter(String namespaceURI, String localName) native;
+  String getParameter(String? namespaceURI, String localName) native;
 
   void importStylesheet(Node style) native;
 
-  void removeParameter(String namespaceURI, String localName) native;
+  void removeParameter(String? namespaceURI, String localName) native;
 
   void reset() native;
 
-  void setParameter(String namespaceURI, String localName, String value) native;
+  void setParameter(String? namespaceURI, String localName, String value)
+      native;
 
   Document transformToDocument(Node source) native;
 
@@ -32663,14 +34833,18 @@
   }
 
   @JSName('localName')
-  final String _localName;
+  String get _localName => JS("String", "#.localName", this);
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
   @JSName('namespaceURI')
-  final String _namespaceUri;
+  final String? _namespaceUri;
 
-  String value;
+  String get value => JS("String", "#.value", this);
+
+  set value(String value) {
+    JS("void", "#.value = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -33023,7 +35197,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory _DomRect([num x, num y, num width, num height]) {
+  factory _DomRect([num? x, num? y, num? width, num? height]) {
     if (height != null) {
       return _DomRect._create_1(x, y, width, height);
     }
@@ -33047,6 +35221,7 @@
   static _DomRect _create_5() => JS('_DomRect', 'new DOMRect()');
 
   // Shadowing definition.
+
   num get height => JS("num", "#.height", this);
 
   set height(num value) {
@@ -33054,6 +35229,7 @@
   }
 
   // Shadowing definition.
+
   num get width => JS("num", "#.width", this);
 
   set width(num value) {
@@ -33061,6 +35237,7 @@
   }
 
   // Shadowing definition.
+
   num get x => JS("num", "#.x", this);
 
   set x(num value) {
@@ -33068,6 +35245,7 @@
   }
 
   // Shadowing definition.
+
   num get y => JS("num", "#.y", this);
 
   set y(num value) {
@@ -33367,7 +35545,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory _MojoInterfaceInterceptor(String interfaceName, [String scope]) {
+  factory _MojoInterfaceInterceptor(String interfaceName, [String? scope]) {
     if (scope != null) {
       return _MojoInterfaceInterceptor._create_1(interfaceName, scope);
     }
@@ -33394,7 +35572,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory _MojoInterfaceRequestEvent(String type, [Map eventInitDict]) {
+  factory _MojoInterfaceRequestEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return _MojoInterfaceRequestEvent._create_1(type, eventInitDict_1);
@@ -33493,13 +35671,13 @@
 
   _Attr getNamedItem(String name) native;
 
-  _Attr getNamedItemNS(String namespaceURI, String localName) native;
+  _Attr getNamedItemNS(String? namespaceURI, String localName) native;
 
   _Attr item(int index) native;
 
   _Attr removeNamedItem(String name) native;
 
-  _Attr removeNamedItemNS(String namespaceURI, String localName) native;
+  _Attr removeNamedItemNS(String? namespaceURI, String localName) native;
 
   _Attr setNamedItem(_Attr attr) native;
 
@@ -33536,11 +35714,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final ReportBody body;
+  final ReportBody? body;
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
-  final String url;
+  String get url => JS("String", "#.url", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -33553,7 +35731,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory _Request(Object input, [Map requestInitDict]) {
+  factory _Request(Object input, [Map? requestInitDict]) {
     if (requestInitDict != null) {
       var requestInitDict_1 = convertDartToNative_Dictionary(requestInitDict);
       return _Request._create_1(input, requestInitDict_1);
@@ -33564,23 +35742,23 @@
       JS('_Request', 'new Request(#,#)', input, requestInitDict);
   static _Request _create_2(input) => JS('_Request', 'new Request(#)', input);
 
-  final String cache;
+  String get cache => JS("String", "#.cache", this);
 
-  final String credentials;
+  String get credentials => JS("String", "#.credentials", this);
 
-  final Headers headers;
+  Headers get headers => JS("Headers", "#.headers", this);
 
-  final String integrity;
+  String get integrity => JS("String", "#.integrity", this);
 
-  final String mode;
+  String get mode => JS("String", "#.mode", this);
 
-  final String redirect;
+  String get redirect => JS("String", "#.redirect", this);
 
-  final String referrer;
+  String get referrer => JS("String", "#.referrer", this);
 
-  final String referrerPolicy;
+  String get referrerPolicy => JS("String", "#.referrerPolicy", this);
 
-  final String url;
+  String get url => JS("String", "#.url", this);
 
   _Request clone() native;
 }
@@ -33608,7 +35786,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory _Response([Object body, Map init]) {
+  factory _Response([Object? body, Map? init]) {
     if (init != null) {
       var init_1 = convertDartToNative_Dictionary(init);
       return _Response._create_1(body, init_1);
@@ -33875,7 +36053,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory _USBInTransferResult(String status, [ByteData data]) {
+  factory _USBInTransferResult(String status, [ByteData? data]) {
     if (data != null) {
       return _USBInTransferResult._create_1(status, data);
     }
@@ -33914,7 +36092,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory _USBIsochronousInTransferPacket(String status, [ByteData data]) {
+  factory _USBIsochronousInTransferPacket(String status, [ByteData? data]) {
     if (data != null) {
       return _USBIsochronousInTransferPacket._create_1(status, data);
     }
@@ -33943,7 +36121,7 @@
 
   factory _USBIsochronousInTransferResult(
       List<_USBIsochronousInTransferPacket> packets,
-      [ByteData data]) {
+      [ByteData? data]) {
     if (data != null) {
       return _USBIsochronousInTransferResult._create_1(packets, data);
     }
@@ -33970,7 +36148,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory _USBIsochronousOutTransferPacket(String status, [int bytesWritten]) {
+  factory _USBIsochronousOutTransferPacket(String status, [int? bytesWritten]) {
     if (bytesWritten != null) {
       return _USBIsochronousOutTransferPacket._create_1(status, bytesWritten);
     }
@@ -34017,7 +36195,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory _USBOutTransferResult(String status, [int bytesWritten]) {
+  factory _USBOutTransferResult(String status, [int? bytesWritten]) {
     if (bytesWritten != null) {
       return _USBOutTransferResult._create_1(status, bytesWritten);
     }
@@ -34041,17 +36219,17 @@
     throw new UnsupportedError("Not supported");
   }
 
-  int _setInterval_String(String handler, [int timeout, Object arguments]);
+  int _setInterval_String(String handler, [int? timeout, Object? arguments]);
 
-  int _setTimeout_String(String handler, [int timeout, Object arguments]);
+  int _setTimeout_String(String handler, [int? timeout, Object? arguments]);
 
-  void _clearInterval([int handle]);
+  void _clearInterval([int? handle]);
 
-  void _clearTimeout([int handle]);
+  void _clearTimeout([int? handle]);
 
-  int _setInterval(Object handler, [int timeout]);
+  int _setInterval(Object handler, [int? timeout]);
 
-  int _setTimeout(Object handler, [int timeout]);
+  int _setTimeout(Object handler, [int? timeout]);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -34113,7 +36291,7 @@
   }
 
   Map<K, V> cast<K, V>() => Map.castFrom<String, String, K, V>(this);
-  bool containsValue(Object value) {
+  bool containsValue(Object? value) {
     for (var v in this.values) {
       if (value == v) {
         return true;
@@ -34192,11 +36370,11 @@
 class _ElementAttributeMap extends _AttributeMap {
   _ElementAttributeMap(Element element) : super(element);
 
-  bool containsKey(Object key) {
+  bool containsKey(Object? key) {
     return _element._hasAttribute(key);
   }
 
-  String operator [](Object key) {
+  String? operator [](Object? key) {
     return _element.getAttribute(key);
   }
 
@@ -34205,7 +36383,7 @@
   }
 
   @pragma('dart2js:tryInline')
-  String remove(Object key) => key is String ? _remove(_element, key) : null;
+  String? remove(Object? key) => key is String ? _remove(_element, key) : null;
 
   /**
    * The number of {key, value} pairs in the map.
@@ -34240,11 +36418,11 @@
 
   _NamespacedAttributeMap(Element element, this._namespace) : super(element);
 
-  bool containsKey(Object key) {
+  bool containsKey(Object? key) {
     return _element._hasAttributeNS(_namespace, key);
   }
 
-  String operator [](Object key) {
+  String? operator [](Object? key) {
     return _element.getAttributeNS(_namespace, key);
   }
 
@@ -34253,7 +36431,7 @@
   }
 
   @pragma('dart2js:tryInline')
-  String remove(Object key) =>
+  String? remove(Object? key) =>
       key is String ? _remove(_namespace, _element, key) : null;
 
   /**
@@ -34302,11 +36480,11 @@
 
   Map<K, V> cast<K, V>() => Map.castFrom<String, String, K, V>(this);
   // TODO: Use lazy iterator when it is available on Map.
-  bool containsValue(Object value) => values.any((v) => v == value);
+  bool containsValue(Object? value) => values.any((v) => v == value);
 
-  bool containsKey(Object key) => _attributes.containsKey(_attr(key));
+  bool containsKey(Object? key) => _attributes.containsKey(_attr(key));
 
-  String operator [](Object key) => _attributes[_attr(key)];
+  String? operator [](Object? key) => _attributes[_attr(key)];
 
   void operator []=(String key, String value) {
     _attributes[_attr(key)] = value;
@@ -34315,7 +36493,7 @@
   String putIfAbsent(String key, String ifAbsent()) =>
       _attributes.putIfAbsent(_attr(key), ifAbsent);
 
-  String remove(Object key) => _attributes.remove(_attr(key));
+  String? remove(Object? key) => _attributes.remove(_attr(key));
 
   void clear() {
     // Needs to operate on a snapshot since we are mutating the collection.
@@ -34627,7 +36805,7 @@
    * [value] must be a valid 'token' representing a single class, i.e. a
    * non-empty string containing no whitespace.
    */
-  bool contains(Object value);
+  bool contains(Object? value);
 
   /**
    * Add the class [value] to element.
@@ -34657,7 +36835,7 @@
    * non-empty string containing no whitespace.  To remove multiple classes, use
    * [removeAll].
    */
-  bool remove(Object value);
+  bool remove(Object? value);
 
   /**
    * Add all classes specified in [iterable] to element.
@@ -34679,7 +36857,7 @@
    * Each element of [iterable] must be a valid 'token' representing a single
    * class, i.e. a non-empty string containing no whitespace.
    */
-  void removeAll(Iterable<Object> iterable);
+  void removeAll(Iterable<Object?> iterable);
 
   /**
    * Toggles all classes specified in [iterable] on element.
@@ -35120,7 +37298,7 @@
    * TODO(sra): It seems wrong to collect a 'changed' flag like this when the
    * underlying toggle returns an 'is set' flag.
    */
-  bool toggle(String value, [bool shouldAdd]) => _sets.fold(
+  bool toggle(String value, [bool? shouldAdd]) => _sets.fold(
       false,
       (bool changed, CssClassSetImpl e) =>
           e.toggle(value, shouldAdd) || changed);
@@ -35132,7 +37310,7 @@
    * This is the Dart equivalent of jQuery's
    * [removeClass](http://api.jquery.com/removeClass/).
    */
-  bool remove(Object value) => _sets.fold(
+  bool remove(Object? value) => _sets.fold(
       false, (bool changed, CssClassSetImpl e) => e.remove(value) || changed);
 }
 
@@ -35166,7 +37344,7 @@
     _element.className = '';
   }
 
-  bool contains(Object value) {
+  bool contains(Object? value) {
     return _contains(_element, value);
   }
 
@@ -35174,11 +37352,11 @@
     return _add(_element, value);
   }
 
-  bool remove(Object value) {
+  bool remove(Object? value) {
     return value is String && _remove(_element, value);
   }
 
-  bool toggle(String value, [bool shouldAdd]) {
+  bool toggle(String value, [bool? shouldAdd]) {
     return _toggle(_element, value, shouldAdd);
   }
 
@@ -35186,11 +37364,11 @@
     _addAll(_element, iterable);
   }
 
-  void removeAll(Iterable<Object> iterable) {
+  void removeAll(Iterable<Object?> iterable) {
     _removeAll(_element, iterable);
   }
 
-  void retainAll(Iterable<Object> iterable) {
+  void retainAll(Iterable<Object?> iterable) {
     _removeWhere(_element, iterable.toSet().contains, false);
   }
 
@@ -35223,7 +37401,7 @@
     return removed;
   }
 
-  static bool _toggle(Element _element, String value, bool shouldAdd) {
+  static bool _toggle(Element _element, String value, bool? shouldAdd) {
     // There is no value that can be passed as the second argument of
     // DomTokenList.toggle that behaves the same as passing one argument.
     // `null` is seen as false, meaning 'remove'.
@@ -35237,13 +37415,13 @@
     return _classListToggle1(list, value);
   }
 
-  static bool _toggleOnOff(Element _element, String value, bool shouldAdd) {
+  static bool _toggleOnOff(Element _element, String value, bool? shouldAdd) {
     DomTokenList list = _classListOf(_element);
     // IE's toggle does not take a second parameter. We would prefer:
     //
     //    return _classListToggle2(list, value, shouldAdd);
     //
-    if (shouldAdd) {
+    if (shouldAdd ?? false) {
       _classListAdd(list, value);
       return true;
     } else {
@@ -35320,7 +37498,7 @@
   }
 
   static bool _classListToggle2(
-      DomTokenList list, String value, bool shouldAdd) {
+      DomTokenList list, String value, bool? shouldAdd) {
     return JS('bool', '#.toggle(#, #)', list, value, shouldAdd);
   }
 }
@@ -35544,16 +37722,16 @@
 
   // DOM events are inherently multi-subscribers.
   Stream<T> asBroadcastStream(
-          {void onListen(StreamSubscription<T> subscription),
-          void onCancel(StreamSubscription<T> subscription)}) =>
+          {void onListen(StreamSubscription<T> subscription)?,
+          void onCancel(StreamSubscription<T> subscription)?}) =>
       this;
   bool get isBroadcast => true;
 
   // TODO(9757): Inlining should be smart and inline only when inlining would
   // enable scalar replacement of an immediately allocated receiver.
   @pragma('dart2js:tryInline')
-  StreamSubscription<T> listen(void onData(T event),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<T> listen(void onData(T event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     return new _EventStreamSubscription<T>(
         this._target, this._eventType, onData, this._useCapture);
   }
@@ -35604,8 +37782,8 @@
       });
 
   // Delegate all regular Stream behavior to a wrapped Stream.
-  StreamSubscription<T> listen(void onData(T event),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<T> listen(void onData(T event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     var pool = new _StreamPool<T>.broadcast();
     for (var target in _targetList) {
       pool.add(new _EventStream<T>(target, _eventType, _useCapture));
@@ -35623,8 +37801,8 @@
   }
 
   Stream<T> asBroadcastStream(
-          {void onListen(StreamSubscription<T> subscription),
-          void onCancel(StreamSubscription<T> subscription)}) =>
+          {void onListen(StreamSubscription<T> subscription)?,
+          void onCancel(StreamSubscription<T> subscription)?}) =>
       this;
   bool get isBroadcast => true;
 }
@@ -35669,23 +37847,25 @@
 
   bool get _canceled => _target == null;
 
-  void onData(void handleData(T event)) {
+  void onData(void handleData(T event)?) {
     if (_canceled) {
       throw new StateError("Subscription has been canceled.");
     }
     // Remove current event listener.
     _unlisten();
-    _onData = _wrapZone<Event>(handleData);
+    _onData = handleData == null
+        ? null
+        : _wrapZone<Event>((e) => (handleData as dynamic)(e));
     _tryResume();
   }
 
   /// Has no effect.
-  void onError(Function handleError) {}
+  void onError(Function? handleError) {}
 
   /// Has no effect.
-  void onDone(void handleDone()) {}
+  void onDone(void handleDone()?) {}
 
-  void pause([Future resumeSignal]) {
+  void pause([Future? resumeSignal]) {
     if (_canceled) return;
     ++_pauseCount;
     _unlisten();
@@ -35715,7 +37895,7 @@
     }
   }
 
-  Future<E> asFuture<E>([E futureValue]) {
+  Future<E> asFuture<E>([E? futureValue]) {
     // We just need a future that will never succeed or fail.
     var completer = new Completer<E>();
     return completer.future;
@@ -35746,15 +37926,15 @@
   }
 
   // Delegate all regular Stream behavior to our wrapped Stream.
-  StreamSubscription<T> listen(void onData(T event),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<T> listen(void onData(T event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     return _streamController.stream.listen(onData,
         onError: onError, onDone: onDone, cancelOnError: cancelOnError);
   }
 
   Stream<T> asBroadcastStream(
-          {void onListen(StreamSubscription<T> subscription),
-          void onCancel(StreamSubscription<T> subscription)}) =>
+          {void onListen(StreamSubscription<T> subscription)?,
+          void onCancel(StreamSubscription<T> subscription)?}) =>
       _streamController.stream;
 
   bool get isBroadcast => true;
@@ -36271,8 +38451,8 @@
    * All known URI attributes will be validated against the UriPolicy, if
    * [uriPolicy] is null then a default UriPolicy will be used.
    */
-  _Html5NodeValidator({UriPolicy uriPolicy})
-      : uriPolicy = uriPolicy != null ? uriPolicy : new UriPolicy() {
+  _Html5NodeValidator({UriPolicy? uriPolicy})
+      : uriPolicy = uriPolicy ?? UriPolicy() {
     if (_attributeValidators.isEmpty) {
       for (var attr in _standardAttributes) {
         _attributeValidators[attr] = _standardAttributeValidator;
@@ -36332,11 +38512,11 @@
     throw new UnsupportedError("Cannot add to immutable List.");
   }
 
-  void sort([int compare(E a, E b)]) {
+  void sort([int compare(E a, E b)?]) {
     throw new UnsupportedError("Cannot sort immutable List.");
   }
 
-  void shuffle([Random random]) {
+  void shuffle([Random? random]) {
     throw new UnsupportedError("Cannot shuffle immutable List.");
   }
 
@@ -36360,7 +38540,7 @@
     throw new UnsupportedError("Cannot remove from immutable List.");
   }
 
-  bool remove(Object object) {
+  bool remove(Object? object) {
     throw new UnsupportedError("Cannot remove from immutable List.");
   }
 
@@ -36384,7 +38564,7 @@
     throw new UnsupportedError("Cannot modify an immutable List.");
   }
 
-  void fillRange(int start, int end, [E fillValue]) {
+  void fillRange(int start, int end, [E? fillValue]) {
     throw new UnsupportedError("Cannot modify an immutable List.");
   }
 }
@@ -37795,7 +39975,7 @@
    */
   void allowCustomElement(String tagName,
       {UriPolicy uriPolicy,
-      Iterable<String> attributes,
+      Iterable<String>? attributes,
       Iterable<String> uriAttributes}) {
     var tagNameUpper = tagName.toUpperCase();
     var attrs = attributes
@@ -38147,7 +40327,7 @@
     _list.add(element);
   }
 
-  bool remove(Object element) => _list.remove(element);
+  bool remove(Object? element) => _list.remove(element);
 
   void clear() {
     _list.clear();
@@ -38165,14 +40345,14 @@
     _list.length = newLength;
   }
 
-  void sort([int compare(E a, E b)]) {
+  void sort([int compare(E a, E b)?]) {
     // Implicit downcast on argument from Node to E-extends-Node.
     _list.sort((Node a, Node b) => compare(a, b));
   }
 
   int indexOf(Object element, [int start = 0]) => _list.indexOf(element, start);
 
-  int lastIndexOf(Object element, [int start]) =>
+  int lastIndexOf(Object element, [int? start]) =>
       _list.lastIndexOf(element, start);
 
   void insert(int index, E element) => _list.insert(index, element);
@@ -38191,7 +40371,7 @@
     _list.replaceRange(start, end, iterable);
   }
 
-  void fillRange(int start, int end, [E fillValue]) {
+  void fillRange(int start, int end, [E? fillValue]) {
     _list.fillRange(start, end, fillValue);
   }
 
@@ -38210,7 +40390,7 @@
     return _iterator.moveNext();
   }
 
-  E get current => _iterator.current;
+  E get current => _iterator.current as E;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -38693,8 +40873,8 @@
   Events get on => throw new UnsupportedError(
       'You can only attach EventListeners to your own window.');
   // TODO(efortuna): Remove this method. dartbug.com/16814
-  void _addEventListener(String type, EventListener listener,
-          [bool useCapture]) =>
+  void _addEventListener(String? type, EventListener? listener,
+          [bool? useCapture]) =>
       throw new UnsupportedError(
           'You can only attach EventListeners to your own window.');
   // TODO(efortuna): Remove this method. dartbug.com/16814
@@ -38706,8 +40886,8 @@
   bool dispatchEvent(Event event) => throw new UnsupportedError(
       'You can only attach EventListeners to your own window.');
   // TODO(efortuna): Remove this method. dartbug.com/16814
-  void _removeEventListener(String type, EventListener listener,
-          [bool useCapture]) =>
+  void _removeEventListener(String? type, EventListener? listener,
+          [bool? useCapture]) =>
       throw new UnsupportedError(
           'You can only attach EventListeners to your own window.');
   // TODO(efortuna): Remove this method. dartbug.com/16814
@@ -38968,7 +41148,7 @@
   bool get shiftKey => _parent.shiftKey;
   Window get view => _parent.view;
   void _initUIEvent(
-      String type, bool canBubble, bool cancelable, Window view, int detail) {
+      String type, bool canBubble, bool cancelable, Window? view, int detail) {
     throw new UnsupportedError("Cannot initialize a UI Event from a KeyEvent.");
   }
 
@@ -39057,7 +41237,7 @@
 
   String get type => wrapped.type;
 
-  void _initEvent(String type, [bool bubbles, bool cancelable]) {
+  void _initEvent(String type, [bool? bubbles, bool? cancelable]) {
     throw new UnsupportedError('Cannot initialize this Event.');
   }
 
diff --git a/sdk_nnbd/lib/indexed_db/dart2js/indexed_db_dart2js.dart b/sdk_nnbd/lib/indexed_db/dart2js/indexed_db_dart2js.dart
index f1acb15..26b7a28 100644
--- a/sdk_nnbd/lib/indexed_db/dart2js/indexed_db_dart2js.dart
+++ b/sdk_nnbd/lib/indexed_db/dart2js/indexed_db_dart2js.dart
@@ -1,4 +1,3 @@
-// @dart = 2.5
 /**
  * A client-side key-value store with support for indexes.
  *
@@ -245,19 +244,19 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String direction;
+  String get direction => JS("String", "#.direction", this);
 
   @_annotation_Creates_IDBKey
   @_annotation_Returns_IDBKey
-  final Object key;
+  Object get key => JS("Object", "#.key", this);
 
   @_annotation_Creates_IDBKey
   @_annotation_Returns_IDBKey
-  final Object primaryKey;
+  Object get primaryKey => JS("Object", "#.primaryKey", this);
 
   @Creates('Null')
   @Returns('ObjectStore|Index|Null')
-  final Object source;
+  Object get source => JS("Object", "#.source", this);
 
   void advance(int count) native;
 
@@ -401,19 +400,20 @@
   static const EventStreamProvider<VersionChangeEvent> versionChangeEvent =
       const EventStreamProvider<VersionChangeEvent>('versionchange');
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
   @Returns('DomStringList|Null')
   @Creates('DomStringList')
-  final List<String> objectStoreNames;
+  List<String> get objectStoreNames =>
+      JS("DomStringList", "#.objectStoreNames", this);
 
   @Creates('int|String|Null')
   @Returns('int|String|Null')
-  final int version;
+  int get version => JS("int", "#.version", this);
 
   void close() native;
 
-  ObjectStore _createObjectStore(String name, [Map options]) {
+  ObjectStore _createObjectStore(String name, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return _createObjectStore_1(name, options_1);
@@ -539,7 +539,7 @@
   @Returns('Request')
   @Creates('Request')
   @Creates('Database')
-  OpenDBRequest _open(String name, [int version]) native;
+  OpenDBRequest _open(String name, [int? version]) native;
 }
 
 /**
@@ -655,15 +655,19 @@
   }
 
   @annotation_Creates_SerializedScriptValue
-  final Object keyPath;
+  Object get keyPath => JS("Object", "#.keyPath", this);
 
-  final bool multiEntry;
+  bool get multiEntry => JS("bool", "#.multiEntry", this);
 
-  String name;
+  String get name => JS("String", "#.name", this);
 
-  final ObjectStore objectStore;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
 
-  final bool unique;
+  ObjectStore get objectStore => JS("ObjectStore", "#.objectStore", this);
+
+  bool get unique => JS("bool", "#.unique", this);
 
   @JSName('count')
   Request _count(Object key) native;
@@ -674,9 +678,9 @@
   @annotation_Creates_SerializedScriptValue
   Request _get(Object key) native;
 
-  Request getAll(Object query, [int count]) native;
+  Request getAll(Object query, [int? count]) native;
 
-  Request getAllKeys(Object query, [int count]) native;
+  Request getAllKeys(Object query, [int? count]) native;
 
   @JSName('getKey')
   @Returns('Request')
@@ -689,13 +693,13 @@
   @Returns('Request')
   @Creates('Request')
   @Creates('Cursor')
-  Request _openCursor(Object range, [String direction]) native;
+  Request _openCursor(Object range, [String? direction]) native;
 
   @JSName('openKeyCursor')
   @Returns('Request')
   @Creates('Request')
   @Creates('Cursor')
-  Request _openKeyCursor(Object range, [String direction]) native;
+  Request _openKeyCursor(Object range, [String? direction]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -724,29 +728,29 @@
   }
 
   @annotation_Creates_SerializedScriptValue
-  final Object lower;
+  Object get lower => JS("Object", "#.lower", this);
 
-  final bool lowerOpen;
+  bool get lowerOpen => JS("bool", "#.lowerOpen", this);
 
   @annotation_Creates_SerializedScriptValue
-  final Object upper;
+  Object get upper => JS("Object", "#.upper", this);
 
-  final bool upperOpen;
+  bool get upperOpen => JS("bool", "#.upperOpen", this);
 
   @JSName('bound')
   static KeyRange bound_(Object lower, Object upper,
-      [bool lowerOpen, bool upperOpen]) native;
+      [bool? lowerOpen, bool? upperOpen]) native;
 
   bool includes(Object key) native;
 
   @JSName('lowerBound')
-  static KeyRange lowerBound_(Object bound, [bool open]) native;
+  static KeyRange lowerBound_(Object bound, [bool? open]) native;
 
   @JSName('only')
   static KeyRange only_(Object value) native;
 
   @JSName('upperBound')
-  static KeyRange upperBound_(Object bound, [bool open]) native;
+  static KeyRange upperBound_(Object bound, [bool? open]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -878,18 +882,22 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool autoIncrement;
+  bool get autoIncrement => JS("bool", "#.autoIncrement", this);
 
   @Returns('DomStringList|Null')
   @Creates('DomStringList')
-  final List<String> indexNames;
+  List<String> get indexNames => JS("DomStringList", "#.indexNames", this);
 
   @annotation_Creates_SerializedScriptValue
-  final Object keyPath;
+  Object get keyPath => JS("Object", "#.keyPath", this);
 
-  String name;
+  String get name => JS("String", "#.name", this);
 
-  final Transaction transaction;
+  set name(String value) {
+    JS("void", "#.name = #", this, value);
+  }
+
+  Transaction get transaction => JS("Transaction", "#.transaction", this);
 
   @Returns('Request')
   @Creates('Request')
@@ -921,7 +929,7 @@
   @JSName('count')
   Request _count(Object key) native;
 
-  Index _createIndex(String name, Object keyPath, [Map options]) {
+  Index _createIndex(String name, Object keyPath, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return _createIndex_1(name, keyPath, options_1);
@@ -945,9 +953,9 @@
   @annotation_Creates_SerializedScriptValue
   Request _get(Object key) native;
 
-  Request getAll(Object query, [int count]) native;
+  Request getAll(Object query, [int? count]) native;
 
-  Request getAllKeys(Object query, [int count]) native;
+  Request getAllKeys(Object query, [int? count]) native;
 
   Request getKey(Object key) native;
 
@@ -957,9 +965,9 @@
   @Returns('Request')
   @Creates('Request')
   @Creates('Cursor')
-  Request _openCursor(Object range, [String direction]) native;
+  Request _openCursor(Object range, [String? direction]) native;
 
-  Request openKeyCursor(Object range, [String direction]) native;
+  Request openKeyCursor(Object range, [String? direction]) native;
 
   @Returns('Request')
   @Creates('Request')
@@ -1023,11 +1031,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Object key;
+  Object get key => JS("Object", "#.key", this);
 
-  final String type;
+  String get type => JS("String", "#.type", this);
 
-  final Object value;
+  Object get value => JS("Object", "#.value", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1069,11 +1077,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Database database;
+  Database get database => JS("Database", "#.database", this);
 
-  final Object records;
+  Object get records => JS("Object", "#.records", this);
 
-  final Transaction transaction;
+  Transaction get transaction => JS("Transaction", "#.transaction", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1142,9 +1150,9 @@
   static const EventStreamProvider<Event> successEvent =
       const EventStreamProvider<Event>('success');
 
-  final DomException error;
+  DomException get error => JS("DomException", "#.error", this);
 
-  final String readyState;
+  String get readyState => JS("String", "#.readyState", this);
 
   dynamic get result => _convertNativeToDart_IDBAny(this._get_result);
   @JSName('result')
@@ -1152,9 +1160,9 @@
   final dynamic _get_result;
 
   @Creates('Null')
-  final Object source;
+  Object get source => JS("Object", "#.source", this);
 
-  final Transaction transaction;
+  Transaction get transaction => JS("Transaction", "#.transaction", this);
 
   /// Stream of `error` events handled by this [Request].
   Stream<Event> get onError => errorEvent.forTarget(this);
@@ -1229,15 +1237,16 @@
   static const EventStreamProvider<Event> errorEvent =
       const EventStreamProvider<Event>('error');
 
-  final Database db;
+  Database get db => JS("Database", "#.db", this);
 
-  final DomException error;
+  DomException get error => JS("DomException", "#.error", this);
 
-  final String mode;
+  String get mode => JS("String", "#.mode", this);
 
   @Returns('DomStringList|Null')
   @Creates('DomStringList')
-  final List<String> objectStoreNames;
+  List<String> get objectStoreNames =>
+      JS("DomStringList", "#.objectStoreNames", this);
 
   void abort() native;
 
@@ -1264,7 +1273,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory VersionChangeEvent(String type, [Map eventInitDict]) {
+  factory VersionChangeEvent(String type, [Map? eventInitDict]) {
     if (eventInitDict != null) {
       var eventInitDict_1 = convertDartToNative_Dictionary(eventInitDict);
       return VersionChangeEvent._create_1(type, eventInitDict_1);
@@ -1279,17 +1288,17 @@
   static VersionChangeEvent _create_2(type) =>
       JS('VersionChangeEvent', 'new IDBVersionChangeEvent(#)', type);
 
-  final String dataLoss;
+  String get dataLoss => JS("String", "#.dataLoss", this);
 
-  final String dataLossMessage;
+  String get dataLossMessage => JS("String", "#.dataLossMessage", this);
 
   @Creates('int|String|Null')
   @Returns('int|String|Null')
-  final int newVersion;
+  final int? newVersion;
 
   @Creates('int|String|Null')
   @Returns('int|String|Null')
-  final int oldVersion;
+  int get oldVersion => JS("int", "#.oldVersion", this);
 
   @JSName('target')
   final OpenDBRequest target;
diff --git a/sdk_nnbd/lib/io/bytes_builder.dart b/sdk_nnbd/lib/io/bytes_builder.dart
index 0951945..6f13693 100644
--- a/sdk_nnbd/lib/io/bytes_builder.dart
+++ b/sdk_nnbd/lib/io/bytes_builder.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
diff --git a/sdk_nnbd/lib/io/common.dart b/sdk_nnbd/lib/io/common.dart
index 1635f56..f8fda15 100644
--- a/sdk_nnbd/lib/io/common.dart
+++ b/sdk_nnbd/lib/io/common.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 // Constants used when working with native ports.
@@ -56,8 +54,8 @@
   /** Constant used to indicate that no OS error code is available. */
   static const int noErrorCode = -1;
 
-  /// Error message supplied by the operating system. This may be `null` or
-  /// empty if no message is associated with the error.
+  /// Error message supplied by the operating system. This will be empty if no
+  /// message is associated with the error.
   final String message;
 
   /// Error code supplied by the operating system.
@@ -107,7 +105,8 @@
   int j = start;
   for (int i = 0; i < length; i++) {
     int value = buffer[j];
-    if (value == null) throw ArgumentError("List element is null at index $j");
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(value, "buffer[]");
     newBuffer[i] = value;
     j++;
   }
diff --git a/sdk_nnbd/lib/io/data_transformer.dart b/sdk_nnbd/lib/io/data_transformer.dart
index 4e23969..81fe195 100644
--- a/sdk_nnbd/lib/io/data_transformer.dart
+++ b/sdk_nnbd/lib/io/data_transformer.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -155,7 +153,7 @@
    * be predicted with good accuracy; the data can then be compressed better
    * than with the default empty dictionary.
    */
-  final List<int> dictionary;
+  final List<int>? dictionary;
 
   ZLibCodec(
       {this.level: ZLibOption.defaultLevel,
@@ -266,7 +264,7 @@
    * be predicted with good accuracy; the data can then be compressed better
    * than with the default empty dictionary.
    */
-  final List<int> dictionary;
+  final List<int>? dictionary;
 
   /**
    * When true, deflate generates raw data with no zlib header or trailer, and
@@ -373,7 +371,7 @@
    * be predicted with good accuracy; the data can then be compressed better
    * than with the default empty dictionary.
    */
-  final List<int> dictionary;
+  final List<int>? dictionary;
 
   /**
    * When true, deflate generates raw data with no zlib header or trailer, and
@@ -442,7 +440,7 @@
    * be predicted with good accuracy; the data can then be compressed better
    * than with the default empty dictionary.
    */
-  final List<int> dictionary;
+  final List<int>? dictionary;
 
   /**
    * When true, deflate generates raw data with no zlib header or trailer, and
@@ -496,7 +494,7 @@
     int windowBits: ZLibOption.defaultWindowBits,
     int memLevel: ZLibOption.defaultMemLevel,
     int strategy: ZLibOption.strategyDefault,
-    List<int> dictionary,
+    List<int>? dictionary,
     bool raw: false,
   }) {
     return _makeZLibDeflateFilter(
@@ -509,7 +507,7 @@
    */
   factory RawZLibFilter.inflateFilter({
     int windowBits: ZLibOption.defaultWindowBits,
-    List<int> dictionary,
+    List<int>? dictionary,
     bool raw: false,
   }) {
     return _makeZLibInflateFilter(windowBits, dictionary, raw);
@@ -529,7 +527,7 @@
    * The last call to [processed] should have [end] set to [:true:]. This will
    * make sure an 'end' packet is written on the stream.
    */
-  List<int> processed({bool flush: true, bool end: false});
+  List<int>? processed({bool flush: true, bool end: false});
 
   external static RawZLibFilter _makeZLibDeflateFilter(
       bool gzip,
@@ -537,11 +535,11 @@
       int windowBits,
       int memLevel,
       int strategy,
-      List<int> dictionary,
+      List<int>? dictionary,
       bool raw);
 
   external static RawZLibFilter _makeZLibInflateFilter(
-      int windowBits, List<int> dictionary, bool raw);
+      int windowBits, List<int>? dictionary, bool raw);
 }
 
 class _BufferSink extends ByteConversionSink {
@@ -572,7 +570,7 @@
       int windowBits,
       int memLevel,
       int strategy,
-      List<int> dictionary,
+      List<int>? dictionary,
       bool raw)
       : super(
             sink,
@@ -582,7 +580,7 @@
 
 class _ZLibDecoderSink extends _FilterSink {
   _ZLibDecoderSink._(
-      ByteConversionSink sink, int windowBits, List<int> dictionary, bool raw)
+      ByteConversionSink sink, int windowBits, List<int>? dictionary, bool raw)
       : super(sink,
             RawZLibFilter._makeZLibInflateFilter(windowBits, dictionary, raw));
 }
@@ -600,8 +598,9 @@
   }
 
   void addSlice(List<int> data, int start, int end, bool isLast) {
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(end, "end");
     if (_closed) return;
-    if (end == null) throw new ArgumentError.notNull("end");
     RangeError.checkValidRange(start, end, data.length);
     try {
       _empty = false;
@@ -609,8 +608,10 @@
           _ensureFastAndSerializableByteData(data, start, end);
       _filter.process(bufferAndStart.buffer, bufferAndStart.start,
           end - (start - bufferAndStart.start));
-      List<int> out;
-      while ((out = _filter.processed(flush: false)) != null) {
+      List<int>? out;
+      while (true) {
+        final out = _filter.processed(flush: false);
+        if (out == null) break;
         _sink.add(out);
       }
     } catch (e) {
@@ -627,8 +628,9 @@
     // message would not have a GZip frame (if compressed with GZip).
     if (_empty) _filter.process(const [], 0, 0);
     try {
-      List<int> out;
-      while ((out = _filter.processed(end: true)) != null) {
+      while (true) {
+        final out = _filter.processed(end: true);
+        if (out == null) break;
         _sink.add(out);
       }
     } catch (e) {
diff --git a/sdk_nnbd/lib/io/directory.dart b/sdk_nnbd/lib/io/directory.dart
index b655779..90e2159 100644
--- a/sdk_nnbd/lib/io/directory.dart
+++ b/sdk_nnbd/lib/io/directory.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -131,7 +129,7 @@
    */
   @pragma("vm:entry-point")
   factory Directory(String path) {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return new _Directory(path);
     }
@@ -156,7 +154,7 @@
    * directory.
    */
   static Directory get current {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return _Directory.current;
     }
@@ -191,7 +189,7 @@
    * are working with the file system, can lead to unexpected results.
    */
   static void set current(path) {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       _Directory.current = path;
       return;
@@ -232,7 +230,7 @@
    * and may be set by an environment variable.
    */
   static Directory get systemTemp {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return _Directory.systemTemp;
     }
@@ -248,7 +246,7 @@
    * Returns a [:Future<Directory>:] that completes with the newly
    * created temporary directory.
    */
-  Future<Directory> createTemp([String prefix]);
+  Future<Directory> createTemp([String? prefix]);
 
   /**
    * Synchronously creates a temporary directory in this directory.
@@ -258,7 +256,7 @@
    *
    * Returns the newly created temporary directory.
    */
-  Directory createTempSync([String prefix]);
+  Directory createTempSync([String? prefix]);
 
   Future<String> resolveSymbolicLinks();
 
diff --git a/sdk_nnbd/lib/io/directory_impl.dart b/sdk_nnbd/lib/io/directory_impl.dart
index 9f6b907..29342c5 100644
--- a/sdk_nnbd/lib/io/directory_impl.dart
+++ b/sdk_nnbd/lib/io/directory_impl.dart
@@ -2,27 +2,19 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 class _Directory extends FileSystemEntity implements Directory {
-  String _path;
-  Uint8List _rawPath;
+  final String _path;
+  final Uint8List _rawPath;
 
-  _Directory(String path) {
-    ArgumentError.checkNotNull(path, 'path');
-    _path = path;
-    _rawPath = FileSystemEntity._toUtf8Array(_path);
-  }
+  _Directory(String path)
+      : _path = path,
+        _rawPath = FileSystemEntity._toUtf8Array(path);
 
-  _Directory.fromRawPath(Uint8List rawPath) {
-    if (rawPath == null) {
-      throw new ArgumentError('rawPath cannot be null');
-    }
-    _rawPath = FileSystemEntity._toNullTerminatedUtf8Array(rawPath);
-    _path = FileSystemEntity._toStringFromUtf8Array(rawPath);
-  }
+  _Directory.fromRawPath(Uint8List rawPath)
+      : _rawPath = FileSystemEntity._toNullTerminatedUtf8Array(rawPath),
+        _path = FileSystemEntity._toStringFromUtf8Array(rawPath);
 
   String get path => _path;
 
@@ -53,7 +45,7 @@
   }
 
   static void set current(path) {
-    Uint8List _rawPath;
+    late Uint8List _rawPath;
     if (path is _Directory) {
       // For our internal Directory implementation, go ahead and use the raw
       // path.
@@ -144,7 +136,7 @@
   static Directory get systemTemp =>
       new Directory(_systemTemp(_Namespace._namespace));
 
-  Future<Directory> createTemp([String prefix]) {
+  Future<Directory> createTemp([String? prefix]) {
     prefix ??= '';
     if (path == '') {
       throw new ArgumentError("Directory.createTemp called with an empty path. "
@@ -168,7 +160,7 @@
     });
   }
 
-  Directory createTempSync([String prefix]) {
+  Directory createTempSync([String? prefix]) {
     prefix ??= '';
     if (path == '') {
       throw new ArgumentError("Directory.createTemp called with an empty path. "
@@ -220,9 +212,8 @@
   }
 
   Directory renameSync(String newPath) {
-    if (newPath is! String) {
-      throw new ArgumentError();
-    }
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(newPath, "newPath");
     var result = _rename(_Namespace._namespace, _rawPath, newPath);
     if (result is OSError) {
       throw new FileSystemException("Rename failed", path, result);
@@ -244,9 +235,9 @@
 
   List<FileSystemEntity> listSync(
       {bool recursive: false, bool followLinks: true}) {
-    if (recursive is! bool || followLinks is! bool) {
-      throw new ArgumentError();
-    }
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(recursive, "recursive");
+    ArgumentError.checkNotNull(followLinks, "followLinks");
     var result = <FileSystemEntity>[];
     _fillWithDirectoryListing(
         _Namespace._namespace,
@@ -283,7 +274,7 @@
 abstract class _AsyncDirectoryListerOps {
   external factory _AsyncDirectoryListerOps(int pointer);
 
-  int getPointer();
+  int? getPointer();
 }
 
 class _AsyncDirectoryLister {
@@ -302,16 +293,18 @@
   final bool recursive;
   final bool followLinks;
 
-  StreamController<FileSystemEntity> controller;
+  final controller = new StreamController<FileSystemEntity>(sync: true);
   bool canceled = false;
   bool nextRunning = false;
   bool closed = false;
-  _AsyncDirectoryListerOps _ops;
+  _AsyncDirectoryListerOps? _ops;
   Completer closeCompleter = new Completer();
 
   _AsyncDirectoryLister(this.rawPath, this.recursive, this.followLinks) {
-    controller = new StreamController<FileSystemEntity>(
-        onListen: onListen, onResume: onResume, onCancel: onCancel, sync: true);
+    controller
+      ..onListen = onListen
+      ..onResume = onResume
+      ..onCancel = onCancel;
   }
 
   // WARNING:
@@ -319,8 +312,8 @@
   // object that implements the async directory lister operations. It should
   // only be called to pass the pointer to the IO Service, which will decrement
   // the reference count when it is finished with it.
-  int _pointer() {
-    return (_ops == null) ? null : _ops.getPointer();
+  int? _pointer() {
+    return _ops?.getPointer();
   }
 
   Stream<FileSystemEntity> get stream => controller.stream;
diff --git a/sdk_nnbd/lib/io/embedder_config.dart b/sdk_nnbd/lib/io/embedder_config.dart
index 2248d1b..cbc94f7 100644
--- a/sdk_nnbd/lib/io/embedder_config.dart
+++ b/sdk_nnbd/lib/io/embedder_config.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /// Embedder-specific, fine-grained dart:io configuration.
diff --git a/sdk_nnbd/lib/io/eventhandler.dart b/sdk_nnbd/lib/io/eventhandler.dart
index 90f22a6..36f54e6 100644
--- a/sdk_nnbd/lib/io/eventhandler.dart
+++ b/sdk_nnbd/lib/io/eventhandler.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 class _EventHandler {
diff --git a/sdk_nnbd/lib/io/file.dart b/sdk_nnbd/lib/io/file.dart
index a291c71..a4d5ef8 100644
--- a/sdk_nnbd/lib/io/file.dart
+++ b/sdk_nnbd/lib/io/file.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -252,7 +250,7 @@
    */
   @pragma("vm:entry-point")
   factory File(String path) {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return new _File(path);
     }
@@ -485,7 +483,7 @@
    * must be read to completion or the subscription on the stream must
    * be cancelled.
    */
-  Stream<List<int>> openRead([int start, int end]);
+  Stream<List<int>> openRead([int? start, int? end]);
 
   /**
    * Creates a new independent [IOSink] for the file. The
@@ -703,7 +701,7 @@
    *
    * Returns a `Future<int>` that completes with the number of bytes read.
    */
-  Future<int> readInto(List<int> buffer, [int start = 0, int end]);
+  Future<int> readInto(List<int> buffer, [int start = 0, int? end]);
 
   /**
    * Synchronously reads into an existing [List<int>] from the file and returns
@@ -716,7 +714,7 @@
    *
    * Throws a [FileSystemException] if the operation fails.
    */
-  int readIntoSync(List<int> buffer, [int start = 0, int end]);
+  int readIntoSync(List<int> buffer, [int start = 0, int? end]);
 
   /**
    * Writes a single byte to the file. Returns a
@@ -742,7 +740,7 @@
    * [RandomAccessFile] when the write completes.
    */
   Future<RandomAccessFile> writeFrom(List<int> buffer,
-      [int start = 0, int end]);
+      [int start = 0, int? end]);
 
   /**
    * Synchronously writes from a [List<int>] to the file. It will read the
@@ -752,7 +750,7 @@
    *
    * Throws a [FileSystemException] if the operation fails.
    */
-  void writeFromSync(List<int> buffer, [int start = 0, int end]);
+  void writeFromSync(List<int> buffer, [int start = 0, int? end]);
 
   /**
    * Writes a string to the file using the given [Encoding]. Returns a
@@ -974,13 +972,13 @@
    * The file system path on which the error occurred. Can be `null`
    * if the exception does not relate directly to a file system path.
    */
-  final String path;
+  final String? path;
 
   /**
    * The underlying OS error. Can be `null` if the exception is not
    * raised due to an OS error.
    */
-  final OSError osError;
+  final OSError? osError;
 
   /**
    * Creates a new FileSystemException with an optional error message
diff --git a/sdk_nnbd/lib/io/file_impl.dart b/sdk_nnbd/lib/io/file_impl.dart
index ea8fb3f..47593d3 100644
--- a/sdk_nnbd/lib/io/file_impl.dart
+++ b/sdk_nnbd/lib/io/file_impl.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 // Read the file in blocks of size 64k.
@@ -11,13 +9,13 @@
 
 class _FileStream extends Stream<List<int>> {
   // Stream controller.
-  StreamController<Uint8List> _controller;
+  late StreamController<Uint8List> _controller;
 
   // Information about the underlying file.
-  String _path;
-  RandomAccessFile _openedFile;
+  String? _path;
+  late RandomAccessFile _openedFile;
   int _position;
-  int _end;
+  int? _end;
   final Completer _closeCompleter = new Completer();
 
   // Has the stream been paused or unsubscribed?
@@ -29,20 +27,12 @@
 
   bool _atEnd = false;
 
-  _FileStream(this._path, this._position, this._end) {
-    _position ??= 0;
-  }
+  _FileStream(this._path, int? position, this._end) : _position = position ?? 0;
 
   _FileStream.forStdin() : _position = 0;
 
-  StreamSubscription<Uint8List> listen(void onData(Uint8List event),
-      {Function onError, void onDone(), bool cancelOnError}) {
-    _setupController();
-    return _controller.stream.listen(onData,
-        onError: onError, onDone: onDone, cancelOnError: cancelOnError);
-  }
-
-  void _setupController() {
+  StreamSubscription<Uint8List> listen(void onData(Uint8List event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     _controller = new StreamController<Uint8List>(
         sync: true,
         onListen: _start,
@@ -51,6 +41,8 @@
           _unsubscribed = true;
           return _closeFile();
         });
+    return _controller.stream.listen(onData,
+        onError: onError, onDone: onDone, cancelOnError: cancelOnError);
   }
 
   Future _closeFile() {
@@ -77,12 +69,13 @@
     }
     _readInProgress = true;
     int readBytes = _blockSize;
-    if (_end != null) {
-      readBytes = min(readBytes, _end - _position);
+    final end = _end;
+    if (end != null) {
+      readBytes = min(readBytes, end - _position);
       if (readBytes < 0) {
         _readInProgress = false;
         if (!_unsubscribed) {
-          _controller.addError(new RangeError("Bad end position: $_end"));
+          _controller.addError(new RangeError("Bad end position: $end"));
           _closeFile();
           _unsubscribed = true;
         }
@@ -147,8 +140,9 @@
       _closeCompleter.complete();
     }
 
-    if (_path != null) {
-      new File(_path)
+    final path = _path;
+    if (path != null) {
+      new File(path)
           .open(mode: FileMode.read)
           .then(onOpenFile, onError: openFailed);
     } else {
@@ -162,22 +156,21 @@
 }
 
 class _FileStreamConsumer extends StreamConsumer<List<int>> {
-  File _file;
+  File? _file;
   Future<RandomAccessFile> _openFuture;
 
-  _FileStreamConsumer(this._file, FileMode mode) {
-    _openFuture = _file.open(mode: mode);
-  }
+  _FileStreamConsumer(File file, FileMode mode)
+      : _file = file,
+        _openFuture = file.open(mode: mode);
 
-  _FileStreamConsumer.fromStdio(int fd) {
-    _openFuture = new Future.value(_File._openStdioSync(fd));
-  }
+  _FileStreamConsumer.fromStdio(int fd)
+      : _openFuture = new Future.value(_File._openStdioSync(fd));
 
   Future<File> addStream(Stream<List<int>> stream) {
     Completer<File> completer = new Completer<File>.sync();
     _openFuture.then((openedFile) {
-      var _subscription;
-      void error(e, [StackTrace stackTrace]) {
+      late StreamSubscription<List<int>> _subscription;
+      void error(e, StackTrace stackTrace) {
         _subscription.cancel();
         openedFile.close();
         completer.completeError(e, stackTrace);
@@ -199,26 +192,22 @@
     return completer.future;
   }
 
-  Future<File> close() =>
+  Future<File?> close() =>
       _openFuture.then((openedFile) => openedFile.close()).then((_) => _file);
 }
 
 // Class for encapsulating the native implementation of files.
 class _File extends FileSystemEntity implements File {
-  String _path;
-  Uint8List _rawPath;
+  final String _path;
+  final Uint8List _rawPath;
 
-  _File(String path) {
-    ArgumentError.checkNotNull(path, 'path');
-    _path = path;
-    _rawPath = FileSystemEntity._toUtf8Array(path);
-  }
+  _File(String path)
+      : _path = path,
+        _rawPath = FileSystemEntity._toUtf8Array(path);
 
-  _File.fromRawPath(Uint8List rawPath) {
-    ArgumentError.checkNotNull(rawPath, 'rawPath');
-    _rawPath = FileSystemEntity._toNullTerminatedUtf8Array(rawPath);
-    _path = FileSystemEntity._toStringFromUtf8Array(rawPath);
-  }
+  _File.fromRawPath(Uint8List rawPath)
+      : _rawPath = FileSystemEntity._toNullTerminatedUtf8Array(rawPath),
+        _path = FileSystemEntity._toStringFromUtf8Array(rawPath);
 
   String get path => _path;
 
@@ -500,7 +489,7 @@
     return new _RandomAccessFile(id, "");
   }
 
-  Stream<List<int>> openRead([int start, int end]) {
+  Stream<List<int>> openRead([int? start, int? end]) {
     return new _FileStream(path, start, end);
   }
 
@@ -654,9 +643,9 @@
   int close();
   readByte();
   read(int bytes);
-  readInto(List<int> buffer, int start, int end);
+  readInto(List<int> buffer, int start, int? end);
   writeByte(int value);
-  writeFrom(List<int> buffer, int start, int end);
+  writeFrom(List<int> buffer, int start, int? end);
   position();
   setPosition(int position);
   truncate(int length);
@@ -671,13 +660,12 @@
   final String path;
 
   bool _asyncDispatched = false;
-  SendPort _fileService;
 
-  _FileResourceInfo _resourceInfo;
+  late _FileResourceInfo _resourceInfo;
   _RandomAccessFileOps _ops;
 
-  _RandomAccessFile(int pointer, this.path) {
-    _ops = new _RandomAccessFileOps(pointer);
+  _RandomAccessFile(int pointer, this.path)
+      : _ops = new _RandomAccessFileOps(pointer) {
     _resourceInfo = new _FileResourceInfo(this);
     _maybeConnectHandler();
   }
@@ -744,7 +732,8 @@
   }
 
   Future<Uint8List> read(int bytes) {
-    ArgumentError.checkNotNull(bytes, 'bytes');
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(bytes, "bytes");
     return _dispatch(_IOService.fileRead, [null, bytes]).then((response) {
       if (_isErrorResponse(response)) {
         throw _exceptionFromResponse(response, "read failed", path);
@@ -756,8 +745,9 @@
   }
 
   Uint8List readSync(int bytes) {
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(bytes, "bytes");
     _checkAvailable();
-    ArgumentError.checkNotNull(bytes, 'bytes');
     var result = _ops.read(bytes);
     if (result is OSError) {
       throw new FileSystemException("readSync failed", path, result);
@@ -766,17 +756,14 @@
     return result;
   }
 
-  Future<int> readInto(List<int> buffer, [int start = 0, int end]) {
-    if ((buffer is! List) ||
-        ((start != null) && (start is! int)) ||
-        ((end != null) && (end is! int))) {
-      throw new ArgumentError();
-    }
+  Future<int> readInto(List<int> buffer, [int start = 0, int? end]) {
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(buffer, "buffer");
     end = RangeError.checkValidRange(start, end, buffer.length);
     if (end == start) {
       return new Future.value(0);
     }
-    int length = end - start;
+    int length = end! - start;
     return _dispatch(_IOService.fileReadInto, [null, length]).then((response) {
       if (_isErrorResponse(response)) {
         throw _exceptionFromResponse(response, "readInto failed", path);
@@ -789,18 +776,15 @@
     });
   }
 
-  int readIntoSync(List<int> buffer, [int start = 0, int end]) {
+  int readIntoSync(List<int> buffer, [int start = 0, int? end]) {
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(buffer, "buffer");
     _checkAvailable();
-    if ((buffer is! List) ||
-        ((start != null) && (start is! int)) ||
-        ((end != null) && (end is! int))) {
-      throw new ArgumentError();
-    }
     end = RangeError.checkValidRange(start, end, buffer.length);
     if (end == start) {
       return 0;
     }
-    var result = _ops.readInto(buffer, start, end);
+    var result = _ops.readInto(buffer, start, end!);
     if (result is OSError) {
       throw new FileSystemException("readInto failed", path, result);
     }
@@ -809,7 +793,8 @@
   }
 
   Future<RandomAccessFile> writeByte(int value) {
-    ArgumentError.checkNotNull(value, 'value');
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(value, "value");
     return _dispatch(_IOService.fileWriteByte, [null, value]).then((response) {
       if (_isErrorResponse(response)) {
         throw _exceptionFromResponse(response, "writeByte failed", path);
@@ -821,7 +806,8 @@
 
   int writeByteSync(int value) {
     _checkAvailable();
-    ArgumentError.checkNotNull(value, 'value');
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(value, "value");
     var result = _ops.writeByte(value);
     if (result is OSError) {
       throw new FileSystemException("writeByte failed", path, result);
@@ -831,19 +817,17 @@
   }
 
   Future<RandomAccessFile> writeFrom(List<int> buffer,
-      [int start = 0, int end]) {
-    if ((buffer is! List) ||
-        ((start != null) && (start is! int)) ||
-        ((end != null) && (end is! int))) {
-      throw new ArgumentError("Invalid arguments to writeFrom");
-    }
+      [int start = 0, int? end]) {
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(buffer, "buffer");
+    ArgumentError.checkNotNull(start, "start");
     end = RangeError.checkValidRange(start, end, buffer.length);
     if (end == start) {
       return new Future.value(this);
     }
     _BufferAndStart result;
     try {
-      result = _ensureFastAndSerializableByteData(buffer, start, end);
+      result = _ensureFastAndSerializableByteData(buffer, start, end!);
     } catch (e) {
       return new Future.error(e);
     }
@@ -857,24 +841,19 @@
       if (_isErrorResponse(response)) {
         throw _exceptionFromResponse(response, "writeFrom failed", path);
       }
-      _resourceInfo.addWrite(end - (start - result.start));
+      _resourceInfo.addWrite(end! - (start - result.start));
       return this;
     });
   }
 
-  void writeFromSync(List<int> buffer, [int start = 0, int end]) {
+  void writeFromSync(List<int> buffer, [int start = 0, int? end]) {
     _checkAvailable();
-    if ((buffer is! List) ||
-        ((start != null) && (start is! int)) ||
-        ((end != null) && (end is! int))) {
-      throw new ArgumentError("Invalid arguments to writeFromSync");
-    }
     end = RangeError.checkValidRange(start, end, buffer.length);
     if (end == start) {
       return;
     }
     _BufferAndStart bufferAndStart =
-        _ensureFastAndSerializableByteData(buffer, start, end);
+        _ensureFastAndSerializableByteData(buffer, start, end!);
     var result = _ops.writeFrom(bufferAndStart.buffer, bufferAndStart.start,
         end - (start - bufferAndStart.start));
     if (result is OSError) {
@@ -885,13 +864,11 @@
 
   Future<RandomAccessFile> writeString(String string,
       {Encoding encoding: utf8}) {
-    ArgumentError.checkNotNull(encoding, 'encoding');
     var data = encoding.encode(string);
     return writeFrom(data, 0, data.length);
   }
 
   void writeStringSync(String string, {Encoding encoding: utf8}) {
-    ArgumentError.checkNotNull(encoding, 'encoding');
     var data = encoding.encode(string);
     writeFromSync(data, 0, data.length);
   }
@@ -994,9 +971,10 @@
 
   Future<RandomAccessFile> lock(
       [FileLock mode = FileLock.exclusive, int start = 0, int end = -1]) {
-    if ((mode is! FileLock) || (start is! int) || (end is! int)) {
-      throw new ArgumentError();
-    }
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(mode, "mode");
+    ArgumentError.checkNotNull(start, "start");
+    ArgumentError.checkNotNull(end, "end");
     if ((start < 0) || (end < -1) || ((end != -1) && (start >= end))) {
       throw new ArgumentError();
     }
@@ -1011,9 +989,9 @@
   }
 
   Future<RandomAccessFile> unlock([int start = 0, int end = -1]) {
-    if ((start is! int) || (end is! int)) {
-      throw new ArgumentError();
-    }
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(start, "start");
+    ArgumentError.checkNotNull(end, "end");
     if (start == end) {
       throw new ArgumentError();
     }
@@ -1029,9 +1007,10 @@
   void lockSync(
       [FileLock mode = FileLock.exclusive, int start = 0, int end = -1]) {
     _checkAvailable();
-    if ((mode is! FileLock) || (start is! int) || (end is! int)) {
-      throw new ArgumentError();
-    }
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(mode, "mode");
+    ArgumentError.checkNotNull(start, "start");
+    ArgumentError.checkNotNull(end, "end");
     if ((start < 0) || (end < -1) || ((end != -1) && (start >= end))) {
       throw new ArgumentError();
     }
@@ -1044,9 +1023,9 @@
 
   void unlockSync([int start = 0, int end = -1]) {
     _checkAvailable();
-    if ((start is! int) || (end is! int)) {
-      throw new ArgumentError();
-    }
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(start, "start");
+    ArgumentError.checkNotNull(end, "end");
     if (start == end) {
       throw new ArgumentError();
     }
diff --git a/sdk_nnbd/lib/io/file_system_entity.dart b/sdk_nnbd/lib/io/file_system_entity.dart
index dc56f7f..737d673 100644
--- a/sdk_nnbd/lib/io/file_system_entity.dart
+++ b/sdk_nnbd/lib/io/file_system_entity.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -59,7 +57,9 @@
   static const _mode = 4;
   static const _size = 5;
 
-  static const _notFound = const FileStat._internalNotFound();
+  static final _epoch = DateTime.fromMillisecondsSinceEpoch(0, isUtc: true);
+  static final _notFound = new FileStat._internal(
+      _epoch, _epoch, _epoch, FileSystemEntityType.notFound, 0, -1);
 
   /**
    * The time of the last change to the data or metadata of the file system
@@ -105,14 +105,6 @@
   FileStat._internal(this.changed, this.modified, this.accessed, this.type,
       this.mode, this.size);
 
-  const FileStat._internalNotFound()
-      : changed = null,
-        modified = null,
-        accessed = null,
-        type = FileSystemEntityType.notFound,
-        mode = 0,
-        size = -1;
-
   external static _statSync(_Namespace namespace, String path);
 
   /**
@@ -123,7 +115,7 @@
    * [FileSystemEntityType.notFound] and the other fields invalid.
    */
   static FileStat statSync(String path) {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return _statSyncInternal(path);
     }
@@ -153,7 +145,7 @@
    * Returns a [Future] which completes with the same results as [statSync].
    */
   static Future<FileStat> stat(String path) {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return _stat(path);
     }
@@ -255,8 +247,8 @@
  *   files and directories.
  */
 abstract class FileSystemEntity {
-  String _path;
-  Uint8List _rawPath;
+  String get _path;
+  Uint8List get _rawPath;
 
   String get path;
 
@@ -502,7 +494,7 @@
       {int events: FileSystemEvent.all, bool recursive: false}) {
     // FIXME(bkonyi): find a way to do this using the raw path.
     final String trimmedPath = _trimTrailingPathSeparators(path);
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return _FileSystemWatcher._watch(trimmedPath, events, recursive);
     }
@@ -538,7 +530,7 @@
    * to an object that does not exist.
    */
   static Future<bool> identical(String path1, String path2) {
-    IOOverrides overrides = IOOverrides.current;
+    IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return _identical(path1, path2);
     }
@@ -620,7 +612,7 @@
    * exist.
    */
   static bool identicalSync(String path1, String path2) {
-    IOOverrides overrides = IOOverrides.current;
+    IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return _identicalSync(path1, path2);
     }
@@ -633,7 +625,7 @@
    * OS X 10.6 and below is not supported.
    */
   static bool get isWatchSupported {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return _FileSystemWatcher.isSupported;
     }
@@ -643,12 +635,9 @@
   // The native methods which determine type of the FileSystemEntity require
   // that the buffer provided is null terminated.
   static Uint8List _toUtf8Array(String s) =>
-      _toNullTerminatedUtf8Array(utf8.encode(s));
+      _toNullTerminatedUtf8Array(utf8.encoder.convert(s));
 
   static Uint8List _toNullTerminatedUtf8Array(Uint8List l) {
-    if (l == null) {
-      return null;
-    }
     if (l.isNotEmpty && l.last != 0) {
       final tmp = new Uint8List(l.length + 1);
       tmp.setRange(0, l.length, l);
@@ -659,9 +648,6 @@
   }
 
   static String _toStringFromUtf8Array(Uint8List l) {
-    if (l == null) {
-      return '';
-    }
     Uint8List nonNullTerminated = l;
     if (l.last == 0) {
       nonNullTerminated =
@@ -799,7 +785,7 @@
 
   static FileSystemEntityType _getTypeSync(
       Uint8List rawPath, bool followLinks) {
-    IOOverrides overrides = IOOverrides.current;
+    IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return _getTypeSyncHelper(rawPath, followLinks);
     }
@@ -821,7 +807,7 @@
 
   static Future<FileSystemEntityType> _getType(
       Uint8List rawPath, bool followLinks) {
-    IOOverrides overrides = IOOverrides.current;
+    IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return _getTypeRequest(rawPath, followLinks);
     }
@@ -829,7 +815,7 @@
         utf8.decode(rawPath, allowMalformed: true), followLinks);
   }
 
-  static _throwIfError(Object result, String msg, [String path]) {
+  static _throwIfError(Object result, String msg, [String? path]) {
     if (result is OSError) {
       throw new FileSystemException(msg, path, result);
     } else if (result is ArgumentError) {
@@ -839,8 +825,8 @@
 
   // TODO(bkonyi): find a way to do this with raw paths.
   static String _trimTrailingPathSeparators(String path) {
-    // Don't handle argument errors here.
-    if (path == null) return path;
+    // TODO: Remove once non-nullability is sound.
+    ArgumentError.checkNotNull(path, "path");
     if (Platform.isWindows) {
       while (path.length > 1 &&
           (path.endsWith(Platform.pathSeparator) || path.endsWith('/'))) {
@@ -856,8 +842,6 @@
 
   // TODO(bkonyi): find a way to do this with raw paths.
   static String _ensureTrailingPathSeparators(String path) {
-    // Don't handle argument errors here.
-    if (path == null) return path;
     if (path.isEmpty) path = '.';
     if (Platform.isWindows) {
       while (!path.endsWith(Platform.pathSeparator) && !path.endsWith('/')) {
@@ -986,7 +970,7 @@
    * If the underlying implementation is able to identify the destination of
    * the moved file, [destination] will be set. Otherwise, it will be `null`.
    */
-  final String destination;
+  final String? destination;
 
   FileSystemMoveEvent._(path, isDirectory, this.destination)
       : super._(FileSystemEvent.move, path, isDirectory);
@@ -1000,7 +984,7 @@
   }
 }
 
-class _FileSystemWatcher {
+abstract class _FileSystemWatcher {
   external static Stream<FileSystemEvent> _watch(
       String path, int events, bool recursive);
   external static bool get isSupported;
diff --git a/sdk_nnbd/lib/io/io.dart b/sdk_nnbd/lib/io/io.dart
index 2c692fcf..27cd6a3 100644
--- a/sdk_nnbd/lib/io/io.dart
+++ b/sdk_nnbd/lib/io/io.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 /**
  * File, socket, HTTP, and other I/O support for non-web applications.
  *
diff --git a/sdk_nnbd/lib/io/io_resource_info.dart b/sdk_nnbd/lib/io/io_resource_info.dart
index 8426483..b916dd8 100644
--- a/sdk_nnbd/lib/io/io_resource_info.dart
+++ b/sdk_nnbd/lib/io/io_resource_info.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 abstract class _IOResourceInfo {
@@ -125,10 +123,9 @@
   }
 
   static Future<ServiceExtensionResponse> getFileInfoMapByID(function, params) {
-    assert(params.containsKey('id'));
-    var id = int.parse(params['id']);
+    var id = int.parse(params['id']!);
     var result =
-        openFiles.containsKey(id) ? openFiles[id].getFileInfoMap() : {};
+        openFiles.containsKey(id) ? openFiles[id]!.getFileInfoMap() : {};
     var jsonValue = json.encode(result);
     return new Future.value(new ServiceExtensionResponse.result(jsonValue));
   }
@@ -192,9 +189,9 @@
 
   static Future<ServiceExtensionResponse> getProcessInfoMapById(
       String function, Map<String, String> params) {
-    var id = int.parse(params['id']);
+    var id = int.parse(params['id']!);
     var result = startedProcesses.containsKey(id)
-        ? startedProcesses[id].fullValueMap
+        ? startedProcesses[id]!.fullValueMap
         : {};
     var jsonValue = json.encode(result);
     return new Future.value(new ServiceExtensionResponse.result(jsonValue));
@@ -257,10 +254,9 @@
 
   static Future<ServiceExtensionResponse> getSocketInfoMapByID(
       String function, Map<String, String> params) {
-    assert(params.containsKey('id'));
-    var id = int.parse(params['id']);
+    var id = int.parse(params['id']!);
     var result =
-        openSockets.containsKey(id) ? openSockets[id].getSocketInfoMap() : {};
+        openSockets.containsKey(id) ? openSockets[id]!.getSocketInfoMap() : {};
     var jsonValue = json.encode(result);
     return new Future.value(new ServiceExtensionResponse.result(jsonValue));
   }
diff --git a/sdk_nnbd/lib/io/io_service.dart b/sdk_nnbd/lib/io/io_service.dart
index b572def..7af382c 100644
--- a/sdk_nnbd/lib/io/io_service.dart
+++ b/sdk_nnbd/lib/io/io_service.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 class _IOService {
diff --git a/sdk_nnbd/lib/io/io_sink.dart b/sdk_nnbd/lib/io/io_sink.dart
index 8331dd0..38296b8 100644
--- a/sdk_nnbd/lib/io/io_sink.dart
+++ b/sdk_nnbd/lib/io/io_sink.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -58,13 +56,13 @@
    * This operation is non-blocking. See [flush] or [done] for how to get any
    * errors generated by this call.
    */
-  void write(Object obj);
+  void write(Object? obj);
 
   /**
    * Iterates over the given [objects] and [write]s them in sequence.
    *
    * If [separator] is provided, a `write` with the `separator` is performed
-   * between any two elements of objects`.
+   * between any two elements of objects.
    *
    * This operation is non-blocking. See [flush] or [done] for how to get any
    * errors generated by this call.
@@ -78,7 +76,7 @@
    * This operation is non-blocking. See [flush] or [done] for how to get any
    * errors generated by this call.
    */
-  void writeln([Object obj = ""]);
+  void writeln([Object? obj = ""]);
 
   /**
    * Writes the character of [charCode].
@@ -99,7 +97,7 @@
    * This operation is non-blocking. See [flush] or [done] for how to get any
    * errors generated by this call.
    */
-  void addError(error, [StackTrace stackTrace]);
+  void addError(error, [StackTrace? stackTrace]);
 
   /**
    * Adds all elements of the given [stream] to `this`.
@@ -143,8 +141,8 @@
 class _StreamSinkImpl<T> implements StreamSink<T> {
   final StreamConsumer<T> _target;
   final Completer _doneCompleter = new Completer();
-  StreamController<T> _controllerInstance;
-  Completer _controllerCompleter;
+  StreamController<T>? _controllerInstance;
+  Completer? _controllerCompleter;
   bool _isClosed = false;
   bool _isBound = false;
   bool _hasError = false;
@@ -158,7 +156,7 @@
     _controller.add(data);
   }
 
-  void addError(error, [StackTrace stackTrace]) {
+  void addError(error, [StackTrace? stackTrace]) {
     if (_isClosed) {
       throw StateError("StreamSink is closed");
     }
@@ -174,7 +172,7 @@
     _isBound = true;
     var future = _controllerCompleter == null
         ? _target.addStream(stream)
-        : _controllerCompleter.future.then((_) => _target.addStream(stream));
+        : _controllerCompleter!.future.then((_) => _target.addStream(stream));
     _controllerInstance?.close();
 
     // Wait for any pending events in [_controller] to be dispatched before
@@ -192,8 +190,8 @@
     // Adding an empty stream-controller will return a future that will complete
     // when all data is done.
     _isBound = true;
-    var future = _controllerCompleter.future;
-    _controllerInstance.close();
+    var future = _controllerCompleter!.future;
+    _controllerInstance!.close();
     return future.whenComplete(() {
       _isBound = false;
     });
@@ -206,7 +204,7 @@
     if (!_isClosed) {
       _isClosed = true;
       if (_controllerInstance != null) {
-        _controllerInstance.close();
+        _controllerInstance!.close();
       } else {
         _closeTarget();
       }
@@ -226,7 +224,7 @@
     }
   }
 
-  void _completeDoneError(error, StackTrace stackTrace) {
+  void _completeDoneError(error, StackTrace? stackTrace) {
     if (!_doneCompleter.isCompleted) {
       _hasError = true;
       _doneCompleter.completeError(error, stackTrace);
@@ -246,7 +244,7 @@
       _target.addStream(_controller.stream).then((_) {
         if (_isBound) {
           // A new stream takes over - forward values to that stream.
-          _controllerCompleter.complete(this);
+          _controllerCompleter!.complete(this);
           _controllerCompleter = null;
           _controllerInstance = null;
         } else {
@@ -256,7 +254,7 @@
       }, onError: (error, stackTrace) {
         if (_isBound) {
           // A new stream takes over - forward errors to that stream.
-          _controllerCompleter.completeError(error, stackTrace);
+          _controllerCompleter!.completeError(error, stackTrace);
           _controllerCompleter = null;
           _controllerInstance = null;
         } else {
@@ -266,7 +264,7 @@
         }
       });
     }
-    return _controllerInstance;
+    return _controllerInstance!;
   }
 }
 
@@ -285,7 +283,7 @@
     _encoding = value;
   }
 
-  void write(Object obj) {
+  void write(Object? obj) {
     String string = '$obj';
     if (string.isEmpty) return;
     add(_encoding.encode(string));
@@ -307,7 +305,7 @@
     }
   }
 
-  void writeln([Object object = ""]) {
+  void writeln([Object? object = ""]) {
     write(object);
     write("\n");
   }
diff --git a/sdk_nnbd/lib/io/link.dart b/sdk_nnbd/lib/io/link.dart
index 0ff9e9d..97addfb 100644
--- a/sdk_nnbd/lib/io/link.dart
+++ b/sdk_nnbd/lib/io/link.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -17,7 +15,7 @@
    */
   @pragma("vm:entry-point")
   factory Link(String path) {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return new _Link(path);
     }
@@ -155,19 +153,16 @@
 }
 
 class _Link extends FileSystemEntity implements Link {
-  String _path;
-  Uint8List _rawPath;
+  final String _path;
+  final Uint8List _rawPath;
 
-  _Link(String path) {
-    ArgumentError.checkNotNull(path, 'path');
-    _path = path;
-    _rawPath = FileSystemEntity._toUtf8Array(path);
-  }
+  _Link(String path)
+      : _path = path,
+        _rawPath = FileSystemEntity._toUtf8Array(path);
 
-  _Link.fromRawPath(Uint8List rawPath) {
-    _rawPath = FileSystemEntity._toNullTerminatedUtf8Array(rawPath);
-    _path = FileSystemEntity._toStringFromUtf8Array(rawPath);
-  }
+  _Link.fromRawPath(Uint8List rawPath)
+      : _rawPath = FileSystemEntity._toNullTerminatedUtf8Array(rawPath),
+        _path = FileSystemEntity._toStringFromUtf8Array(rawPath);
 
   String get path => _path;
 
diff --git a/sdk_nnbd/lib/io/namespace_impl.dart b/sdk_nnbd/lib/io/namespace_impl.dart
index 1bac5a2..88987b6 100644
--- a/sdk_nnbd/lib/io/namespace_impl.dart
+++ b/sdk_nnbd/lib/io/namespace_impl.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 // Each Isolate may run in a different "namespace", which provides the scope in
diff --git a/sdk_nnbd/lib/io/network_profiling.dart b/sdk_nnbd/lib/io/network_profiling.dart
index 3ab99b2..87d6527 100644
--- a/sdk_nnbd/lib/io/network_profiling.dart
+++ b/sdk_nnbd/lib/io/network_profiling.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 const int _versionMajor = 1;
@@ -105,7 +103,7 @@
   if (!parameters.containsKey(kEnable)) {
     throw _missingArgument(kEnable);
   }
-  final enable = parameters[kEnable].toLowerCase();
+  final enable = parameters[kEnable]!.toLowerCase();
   if (enable != 'true' && enable != 'false') {
     throw _invalidArgument(kEnable, enable);
   }
@@ -139,8 +137,7 @@
     // Skip socket that started before _enableSocketProfiling turned on.
     if (!_idToSocketStatistic.containsKey(id) &&
         type != _SocketProfileType.startTime) return;
-    _idToSocketStatistic[id] ??= _SocketStatistic(id);
-    _SocketStatistic stats = _idToSocketStatistic[id];
+    _SocketStatistic stats = _idToSocketStatistic[id] ??= _SocketStatistic(id);
     switch (type) {
       case _SocketProfileType.startTime:
         stats.startTime = Timeline.now;
@@ -162,16 +159,12 @@
         break;
       case _SocketProfileType.readBytes:
         if (object == null) return;
-        assert(object is int);
-        stats.readBytes ??= 0;
-        stats.readBytes += object;
+        stats.readBytes += object as int;
         stats.lastReadTime = Timeline.now;
         break;
       case _SocketProfileType.writeBytes:
         if (object == null) return;
-        assert(object is int);
-        stats.writeBytes ??= 0;
-        stats.writeBytes += object;
+        stats.writeBytes += object as int;
         stats.lastWriteTime = Timeline.now;
         break;
       default:
@@ -192,7 +185,7 @@
 
   // clear the storage if _idToSocketStatistic has been initialized.
   static String clear() {
-    _idToSocketStatistic?.clear();
+    _idToSocketStatistic.clear();
     return _success();
   }
 }
@@ -212,15 +205,15 @@
 /// Socket statistic
 class _SocketStatistic {
   final int id;
-  int startTime;
-  int endTime;
-  String address;
-  int port;
-  String socketType;
+  int? startTime;
+  int? endTime;
+  String? address;
+  int? port;
+  String? socketType;
   int readBytes = 0;
   int writeBytes = 0;
-  int lastWriteTime;
-  int lastReadTime;
+  int? lastWriteTime;
+  int? lastReadTime;
 
   _SocketStatistic(this.id);
 
@@ -240,7 +233,7 @@
     return map;
   }
 
-  void _setIfNotNull(Map<String, Object> json, String key, Object value) {
+  void _setIfNotNull(Map<String, dynamic> json, String key, Object? value) {
     if (value == null) return;
     json[key] = value;
   }
diff --git a/sdk_nnbd/lib/io/overrides.dart b/sdk_nnbd/lib/io/overrides.dart
index b46af8a..1fd0f06 100644
--- a/sdk_nnbd/lib/io/overrides.dart
+++ b/sdk_nnbd/lib/io/overrides.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 final _ioOverridesToken = new Object();
@@ -34,9 +32,9 @@
 /// }
 /// ```
 abstract class IOOverrides {
-  static IOOverrides _global;
+  static IOOverrides? _global;
 
-  static IOOverrides get current {
+  static IOOverrides? get current {
     return Zone.current[_ioOverridesToken] ?? _global;
   }
 
@@ -45,7 +43,7 @@
   /// These are the [IOOverrides] that will be used in the root Zone, and in
   /// Zone's that do not set [IOOverrides] and whose ancestors up to the root
   /// Zone do not set [IOOverrides].
-  static set global(IOOverrides overrides) {
+  static set global(IOOverrides? overrides) {
     _global = overrides;
   }
 
@@ -56,47 +54,47 @@
   static R runZoned<R>(R body(),
       {
       // Directory
-      Directory Function(String) createDirectory,
-      Directory Function() getCurrentDirectory,
-      void Function(String) setCurrentDirectory,
-      Directory Function() getSystemTempDirectory,
+      Directory Function(String)? createDirectory,
+      Directory Function()? getCurrentDirectory,
+      void Function(String)? setCurrentDirectory,
+      Directory Function()? getSystemTempDirectory,
 
       // File
-      File Function(String) createFile,
+      File Function(String)? createFile,
 
       // FileStat
-      Future<FileStat> Function(String) stat,
-      FileStat Function(String) statSync,
+      Future<FileStat> Function(String)? stat,
+      FileStat Function(String)? statSync,
 
       // FileSystemEntity
-      Future<bool> Function(String, String) fseIdentical,
-      bool Function(String, String) fseIdenticalSync,
-      Future<FileSystemEntityType> Function(String, bool) fseGetType,
-      FileSystemEntityType Function(String, bool) fseGetTypeSync,
+      Future<bool> Function(String, String)? fseIdentical,
+      bool Function(String, String)? fseIdenticalSync,
+      Future<FileSystemEntityType> Function(String, bool)? fseGetType,
+      FileSystemEntityType Function(String, bool)? fseGetTypeSync,
 
       // _FileSystemWatcher
-      Stream<FileSystemEvent> Function(String, int, bool) fsWatch,
-      bool Function() fsWatchIsSupported,
+      Stream<FileSystemEvent> Function(String, int, bool)? fsWatch,
+      bool Function()? fsWatchIsSupported,
 
       // Link
-      Link Function(String) createLink,
+      Link Function(String)? createLink,
 
       // Socket
       Future<Socket> Function(dynamic, int,
-              {dynamic sourceAddress, Duration timeout})
+              {dynamic sourceAddress, Duration? timeout})?
           socketConnect,
       Future<ConnectionTask<Socket>> Function(dynamic, int,
-              {dynamic sourceAddress})
+              {dynamic sourceAddress})?
           socketStartConnect,
 
       // ServerSocket
       Future<ServerSocket> Function(dynamic, int,
-              {int backlog, bool v6Only, bool shared})
+              {int backlog, bool v6Only, bool shared})?
           serverSocketBind,
 
       // Optional Zone parameters
-      ZoneSpecification zoneSpecification,
-      Function onError}) {
+      ZoneSpecification? zoneSpecification,
+      Function? onError}) {
     IOOverrides overrides = new _IOOverridesScope(
       // Directory
       createDirectory,
@@ -142,7 +140,7 @@
   /// Note that [overrides] should be an instance of a class that extends
   /// [IOOverrides].
   static R runWithIOOverrides<R>(R body(), IOOverrides overrides,
-      {ZoneSpecification zoneSpecification, Function onError}) {
+      {ZoneSpecification? zoneSpecification, Function? onError}) {
     return _asyncRunZoned<R>(body,
         zoneValues: {_ioOverridesToken: overrides},
         zoneSpecification: zoneSpecification,
@@ -228,7 +226,8 @@
   /// When this override is installed, this function overrides the behavior of
   /// `FileSystemEntity.type`.
   Future<FileSystemEntityType> fseGetType(String path, bool followLinks) {
-    return FileSystemEntity._getTypeRequest(utf8.encode(path), followLinks);
+    return FileSystemEntity._getTypeRequest(
+        utf8.encoder.convert(path), followLinks);
   }
 
   /// Returns the [FileSystemEntityType] for [path].
@@ -236,7 +235,8 @@
   /// When this override is installed, this function overrides the behavior of
   /// `FileSystemEntity.typeSync`.
   FileSystemEntityType fseGetTypeSync(String path, bool followLinks) {
-    return FileSystemEntity._getTypeSyncHelper(utf8.encode(path), followLinks);
+    return FileSystemEntity._getTypeSyncHelper(
+        utf8.encoder.convert(path), followLinks);
   }
 
   // _FileSystemWatcher
@@ -270,7 +270,7 @@
   /// When this override is installed, this functions overrides the behavior of
   /// `Socket.connect(...)`.
   Future<Socket> socketConnect(host, int port,
-      {sourceAddress, Duration timeout}) {
+      {sourceAddress, Duration? timeout}) {
     return Socket._connect(host, port,
         sourceAddress: sourceAddress, timeout: timeout);
   }
@@ -300,43 +300,43 @@
 }
 
 class _IOOverridesScope extends IOOverrides {
-  final IOOverrides _previous = IOOverrides.current;
+  final IOOverrides? _previous = IOOverrides.current;
 
   // Directory
-  Directory Function(String) _createDirectory;
-  Directory Function() _getCurrentDirectory;
-  void Function(String) _setCurrentDirectory;
-  Directory Function() _getSystemTempDirectory;
+  Directory Function(String)? _createDirectory;
+  Directory Function()? _getCurrentDirectory;
+  void Function(String)? _setCurrentDirectory;
+  Directory Function()? _getSystemTempDirectory;
 
   // File
-  File Function(String) _createFile;
+  File Function(String)? _createFile;
 
   // FileStat
-  Future<FileStat> Function(String) _stat;
-  FileStat Function(String) _statSync;
+  Future<FileStat> Function(String)? _stat;
+  FileStat Function(String)? _statSync;
 
   // FileSystemEntity
-  Future<bool> Function(String, String) _fseIdentical;
-  bool Function(String, String) _fseIdenticalSync;
-  Future<FileSystemEntityType> Function(String, bool) _fseGetType;
-  FileSystemEntityType Function(String, bool) _fseGetTypeSync;
+  Future<bool> Function(String, String)? _fseIdentical;
+  bool Function(String, String)? _fseIdenticalSync;
+  Future<FileSystemEntityType> Function(String, bool)? _fseGetType;
+  FileSystemEntityType Function(String, bool)? _fseGetTypeSync;
 
   // _FileSystemWatcher
-  Stream<FileSystemEvent> Function(String, int, bool) _fsWatch;
-  bool Function() _fsWatchIsSupported;
+  Stream<FileSystemEvent> Function(String, int, bool)? _fsWatch;
+  bool Function()? _fsWatchIsSupported;
 
   // Link
-  Link Function(String) _createLink;
+  Link Function(String)? _createLink;
 
   // Socket
   Future<Socket> Function(dynamic, int,
-      {dynamic sourceAddress, Duration timeout}) _socketConnect;
-  Future<ConnectionTask<Socket>> Function(dynamic, int, {dynamic sourceAddress})
-      _socketStartConnect;
+      {dynamic sourceAddress, Duration? timeout})? _socketConnect;
+  Future<ConnectionTask<Socket>> Function(dynamic, int,
+      {dynamic sourceAddress})? _socketStartConnect;
 
   // ServerSocket
   Future<ServerSocket> Function(dynamic, int,
-      {int backlog, bool v6Only, bool shared}) _serverSocketBind;
+      {int backlog, bool v6Only, bool shared})? _serverSocketBind;
 
   _IOOverridesScope(
     // Directory
@@ -376,120 +376,120 @@
   // Directory
   @override
   Directory createDirectory(String path) {
-    if (_createDirectory != null) return _createDirectory(path);
-    if (_previous != null) return _previous.createDirectory(path);
+    if (_createDirectory != null) return _createDirectory!(path);
+    if (_previous != null) return _previous!.createDirectory(path);
     return super.createDirectory(path);
   }
 
   @override
   Directory getCurrentDirectory() {
-    if (_getCurrentDirectory != null) return _getCurrentDirectory();
-    if (_previous != null) return _previous.getCurrentDirectory();
+    if (_getCurrentDirectory != null) return _getCurrentDirectory!();
+    if (_previous != null) return _previous!.getCurrentDirectory();
     return super.getCurrentDirectory();
   }
 
   @override
   void setCurrentDirectory(String path) {
     if (_setCurrentDirectory != null)
-      _setCurrentDirectory(path);
+      _setCurrentDirectory!(path);
     else if (_previous != null)
-      _previous.setCurrentDirectory(path);
+      _previous!.setCurrentDirectory(path);
     else
       super.setCurrentDirectory(path);
   }
 
   @override
   Directory getSystemTempDirectory() {
-    if (_getSystemTempDirectory != null) return _getSystemTempDirectory();
-    if (_previous != null) return _previous.getSystemTempDirectory();
+    if (_getSystemTempDirectory != null) return _getSystemTempDirectory!();
+    if (_previous != null) return _previous!.getSystemTempDirectory();
     return super.getSystemTempDirectory();
   }
 
   // File
   @override
   File createFile(String path) {
-    if (_createFile != null) return _createFile(path);
-    if (_previous != null) return _previous.createFile(path);
+    if (_createFile != null) return _createFile!(path);
+    if (_previous != null) return _previous!.createFile(path);
     return super.createFile(path);
   }
 
   // FileStat
   @override
   Future<FileStat> stat(String path) {
-    if (_stat != null) return _stat(path);
-    if (_previous != null) return _previous.stat(path);
+    if (_stat != null) return _stat!(path);
+    if (_previous != null) return _previous!.stat(path);
     return super.stat(path);
   }
 
   @override
   FileStat statSync(String path) {
-    if (_stat != null) return _statSync(path);
-    if (_previous != null) return _previous.statSync(path);
+    if (_stat != null) return _statSync!(path);
+    if (_previous != null) return _previous!.statSync(path);
     return super.statSync(path);
   }
 
   // FileSystemEntity
   @override
   Future<bool> fseIdentical(String path1, String path2) {
-    if (_fseIdentical != null) return _fseIdentical(path1, path2);
-    if (_previous != null) return _previous.fseIdentical(path1, path2);
+    if (_fseIdentical != null) return _fseIdentical!(path1, path2);
+    if (_previous != null) return _previous!.fseIdentical(path1, path2);
     return super.fseIdentical(path1, path2);
   }
 
   @override
   bool fseIdenticalSync(String path1, String path2) {
-    if (_fseIdenticalSync != null) return _fseIdenticalSync(path1, path2);
-    if (_previous != null) return _previous.fseIdenticalSync(path1, path2);
+    if (_fseIdenticalSync != null) return _fseIdenticalSync!(path1, path2);
+    if (_previous != null) return _previous!.fseIdenticalSync(path1, path2);
     return super.fseIdenticalSync(path1, path2);
   }
 
   @override
   Future<FileSystemEntityType> fseGetType(String path, bool followLinks) {
-    if (_fseGetType != null) return _fseGetType(path, followLinks);
-    if (_previous != null) return _previous.fseGetType(path, followLinks);
+    if (_fseGetType != null) return _fseGetType!(path, followLinks);
+    if (_previous != null) return _previous!.fseGetType(path, followLinks);
     return super.fseGetType(path, followLinks);
   }
 
   @override
   FileSystemEntityType fseGetTypeSync(String path, bool followLinks) {
-    if (_fseGetTypeSync != null) return _fseGetTypeSync(path, followLinks);
-    if (_previous != null) return _previous.fseGetTypeSync(path, followLinks);
+    if (_fseGetTypeSync != null) return _fseGetTypeSync!(path, followLinks);
+    if (_previous != null) return _previous!.fseGetTypeSync(path, followLinks);
     return super.fseGetTypeSync(path, followLinks);
   }
 
   // _FileSystemWatcher
   @override
   Stream<FileSystemEvent> fsWatch(String path, int events, bool recursive) {
-    if (_fsWatch != null) return _fsWatch(path, events, recursive);
-    if (_previous != null) return _previous.fsWatch(path, events, recursive);
+    if (_fsWatch != null) return _fsWatch!(path, events, recursive);
+    if (_previous != null) return _previous!.fsWatch(path, events, recursive);
     return super.fsWatch(path, events, recursive);
   }
 
   @override
   bool fsWatchIsSupported() {
-    if (_fsWatchIsSupported != null) return _fsWatchIsSupported();
-    if (_previous != null) return _previous.fsWatchIsSupported();
+    if (_fsWatchIsSupported != null) return _fsWatchIsSupported!();
+    if (_previous != null) return _previous!.fsWatchIsSupported();
     return super.fsWatchIsSupported();
   }
 
   // Link
   @override
   Link createLink(String path) {
-    if (_createLink != null) return _createLink(path);
-    if (_previous != null) return _previous.createLink(path);
+    if (_createLink != null) return _createLink!(path);
+    if (_previous != null) return _previous!.createLink(path);
     return super.createLink(path);
   }
 
   // Socket
   @override
   Future<Socket> socketConnect(host, int port,
-      {sourceAddress, Duration timeout}) {
+      {sourceAddress, Duration? timeout}) {
     if (_socketConnect != null) {
-      return _socketConnect(host, port,
+      return _socketConnect!(host, port,
           sourceAddress: sourceAddress, timeout: timeout);
     }
     if (_previous != null) {
-      return _previous.socketConnect(host, port,
+      return _previous!.socketConnect(host, port,
           sourceAddress: sourceAddress, timeout: timeout);
     }
     return super.socketConnect(host, port,
@@ -500,11 +500,11 @@
   Future<ConnectionTask<Socket>> socketStartConnect(host, int port,
       {sourceAddress}) {
     if (_socketStartConnect != null) {
-      return _socketStartConnect(host, port, sourceAddress: sourceAddress);
+      return _socketStartConnect!(host, port, sourceAddress: sourceAddress);
     }
     if (_previous != null) {
-      return _previous.socketStartConnect(host, port,
-          sourceAddress: sourceAddress);
+      return _previous!
+          .socketStartConnect(host, port, sourceAddress: sourceAddress);
     }
     return super.socketStartConnect(host, port, sourceAddress: sourceAddress);
   }
@@ -514,11 +514,11 @@
   Future<ServerSocket> serverSocketBind(address, int port,
       {int backlog: 0, bool v6Only: false, bool shared: false}) {
     if (_serverSocketBind != null) {
-      return _serverSocketBind(address, port,
+      return _serverSocketBind!(address, port,
           backlog: backlog, v6Only: v6Only, shared: shared);
     }
     if (_previous != null) {
-      return _previous.serverSocketBind(address, port,
+      return _previous!.serverSocketBind(address, port,
           backlog: backlog, v6Only: v6Only, shared: shared);
     }
     return super.serverSocketBind(address, port,
diff --git a/sdk_nnbd/lib/io/platform.dart b/sdk_nnbd/lib/io/platform.dart
index c08b937..412e258 100644
--- a/sdk_nnbd/lib/io/platform.dart
+++ b/sdk_nnbd/lib/io/platform.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -210,7 +208,7 @@
    *
    */
   @Deprecated('packages/ directory resolution is not supported in Dart 2')
-  static String get packageRoot => null; // TODO(mfairhurst): remove this
+  static String? get packageRoot => null; // TODO(mfairhurst): remove this
 
   /**
    * The `--packages` flag passed to the executable used to run the script
@@ -220,7 +218,7 @@
    *
    * Is `null` if there is no `--packages` flag.
    */
-  static String get packageConfig => _Platform.packageConfig;
+  static String? get packageConfig => _Platform.packageConfig;
 
   /**
    * The version of the current Dart runtime.
diff --git a/sdk_nnbd/lib/io/platform_impl.dart b/sdk_nnbd/lib/io/platform_impl.dart
index c7b23a9..0251445 100644
--- a/sdk_nnbd/lib/io/platform_impl.dart
+++ b/sdk_nnbd/lib/io/platform_impl.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 class _Platform {
@@ -32,21 +30,19 @@
    */
   external static _environment();
   external static List<String> _executableArguments();
-  external static String _packageRoot(); // TODO(mfairhurst): remove this
-  external static String _packageConfig();
+  external static String? _packageConfig();
   external static String _version();
   external static String _localeName();
   external static Uri _script();
 
   static String executable = _executable();
   static String resolvedExecutable = _resolvedExecutable();
-  static String packageRoot; // TODO(mfairhurst): remove this
-  static String packageConfig = _packageConfig();
+  static String? packageConfig = _packageConfig();
 
   @pragma("vm:entry-point")
-  static String Function() _localeClosure;
+  static String Function()? _localeClosure;
   static String localeName() {
-    final result = (_localeClosure == null) ? _localeName() : _localeClosure();
+    final result = (_localeClosure == null) ? _localeName() : _localeClosure!();
     if (result is OSError) {
       throw result;
     }
@@ -55,14 +51,14 @@
 
   // Cache the OS environment. This can be an OSError instance if
   // retrieving the environment failed.
-  static var /*OSError|Map<String,String>*/ _environmentCache;
+  static var /*OSError?|Map<String,String>?*/ _environmentCache;
 
   static int get numberOfProcessors => _numberOfProcessors();
   static String get pathSeparator => _pathSeparator();
   static String get operatingSystem => _operatingSystem();
   static Uri get script => _script();
 
-  static String _cachedOSVersion;
+  static String? _cachedOSVersion;
   static String get operatingSystemVersion {
     if (_cachedOSVersion == null) {
       var result = _operatingSystemVersion();
@@ -71,7 +67,7 @@
       }
       _cachedOSVersion = result;
     }
-    return _cachedOSVersion;
+    return _cachedOSVersion!;
   }
 
   static String get localHostname {
@@ -116,7 +112,7 @@
     if (_environmentCache is OSError) {
       throw _environmentCache;
     } else {
-      return _environmentCache;
+      return _environmentCache!;
     }
   }
 
@@ -128,10 +124,10 @@
 class _CaseInsensitiveStringMap<V> extends MapBase<String, V> {
   final Map<String, V> _map = new Map<String, V>();
 
-  bool containsKey(Object key) =>
+  bool containsKey(Object? key) =>
       key is String && _map.containsKey(key.toUpperCase());
-  bool containsValue(Object value) => _map.containsValue(value);
-  V operator [](Object key) => key is String ? _map[key.toUpperCase()] : null;
+  bool containsValue(Object? value) => _map.containsValue(value);
+  V? operator [](Object? key) => key is String ? _map[key.toUpperCase()] : null;
   void operator []=(String key, V value) {
     _map[key.toUpperCase()] = value;
   }
@@ -144,7 +140,8 @@
     other.forEach((key, value) => this[key.toUpperCase()] = value);
   }
 
-  V remove(Object key) => key is String ? _map.remove(key.toUpperCase()) : null;
+  V? remove(Object? key) =>
+      key is String ? _map.remove(key.toUpperCase()) : null;
 
   void clear() {
     _map.clear();
@@ -165,7 +162,7 @@
   Map<K2, V2> map<K2, V2>(MapEntry<K2, V2> transform(String key, V value)) =>
       _map.map(transform);
 
-  V update(String key, V update(V value), {V ifAbsent()}) =>
+  V update(String key, V update(V value), {V ifAbsent()?}) =>
       _map.update(key.toUpperCase(), update, ifAbsent: ifAbsent);
 
   void updateAll(V update(String key, V value)) {
diff --git a/sdk_nnbd/lib/io/process.dart b/sdk_nnbd/lib/io/process.dart
index b503e9e..9b2884f 100644
--- a/sdk_nnbd/lib/io/process.dart
+++ b/sdk_nnbd/lib/io/process.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 // TODO(ager): The only reason for this class is that we
@@ -13,7 +11,7 @@
   external static void _setExitCode(int status);
   external static int _getExitCode();
   external static void _sleep(int millis);
-  external static int _pid(Process process);
+  external static int _pid(Process? process);
   external static Stream<ProcessSignal> _watchSignal(ProcessSignal signal);
 }
 
@@ -363,8 +361,8 @@
    */
   external static Future<Process> start(
       String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment: true,
       bool runInShell: false,
       ProcessStartMode mode: ProcessStartMode.normal});
@@ -412,12 +410,12 @@
    */
   external static Future<ProcessResult> run(
       String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment: true,
       bool runInShell: false,
-      Encoding stdoutEncoding: systemEncoding,
-      Encoding stderrEncoding: systemEncoding});
+      Encoding? stdoutEncoding: systemEncoding,
+      Encoding? stderrEncoding: systemEncoding});
 
   /**
    * Starts a process and runs it to completion. This is a synchronous
@@ -430,12 +428,12 @@
    */
   external static ProcessResult runSync(
       String executable, List<String> arguments,
-      {String workingDirectory,
-      Map<String, String> environment,
+      {String? workingDirectory,
+      Map<String, String>? environment,
       bool includeParentEnvironment: true,
       bool runInShell: false,
-      Encoding stdoutEncoding: systemEncoding,
-      Encoding stderrEncoding: systemEncoding});
+      Encoding? stdoutEncoding: systemEncoding,
+      Encoding? stderrEncoding: systemEncoding});
 
   /**
    * Kills the process with id [pid].
@@ -695,8 +693,7 @@
   const ProcessException(this.executable, this.arguments,
       [this.message = "", this.errorCode = 0]);
   String toString() {
-    var msg = (message == null) ? 'OS error code: $errorCode' : message;
     var args = arguments.join(' ');
-    return "ProcessException: $msg\n  Command: $executable $args";
+    return "ProcessException: $message\n  Command: $executable $args";
   }
 }
diff --git a/sdk_nnbd/lib/io/secure_server_socket.dart b/sdk_nnbd/lib/io/secure_server_socket.dart
index 4b84859..c7b58f5 100644
--- a/sdk_nnbd/lib/io/secure_server_socket.dart
+++ b/sdk_nnbd/lib/io/secure_server_socket.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -74,10 +72,9 @@
       bool v6Only: false,
       bool requestClientCertificate: false,
       bool requireClientCertificate: false,
-      List<String> supportedProtocols,
+      List<String>? supportedProtocols,
       bool shared: false}) {
-    return RawSecureServerSocket
-        .bind(address, port, context,
+    return RawSecureServerSocket.bind(address, port, context,
             backlog: backlog,
             v6Only: v6Only,
             requestClientCertificate: requestClientCertificate,
@@ -87,8 +84,8 @@
         .then((serverSocket) => new SecureServerSocket._(serverSocket));
   }
 
-  StreamSubscription<SecureSocket> listen(void onData(SecureSocket socket),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<SecureSocket> listen(void onData(SecureSocket socket)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     return _socket.map((rawSocket) => new SecureSocket._(rawSocket)).listen(
         onData,
         onError: onError,
@@ -125,12 +122,12 @@
  */
 class RawSecureServerSocket extends Stream<RawSecureSocket> {
   final RawServerSocket _socket;
-  StreamController<RawSecureSocket> _controller;
-  StreamSubscription<RawSocket> _subscription;
+  late StreamController<RawSecureSocket> _controller;
+  StreamSubscription<RawSocket>? _subscription;
   final SecurityContext _context;
   final bool requestClientCertificate;
   final bool requireClientCertificate;
-  final List<String> supportedProtocols;
+  final List<String>? supportedProtocols;
   bool _closed = false;
 
   RawSecureServerSocket._(
@@ -203,10 +200,10 @@
       bool v6Only: false,
       bool requestClientCertificate: false,
       bool requireClientCertificate: false,
-      List<String> supportedProtocols,
+      List<String>? supportedProtocols,
       bool shared: false}) {
-    return RawServerSocket
-        .bind(address, port, backlog: backlog, v6Only: v6Only, shared: shared)
+    return RawServerSocket.bind(address, port,
+            backlog: backlog, v6Only: v6Only, shared: shared)
         .then((serverSocket) => new RawSecureServerSocket._(
             serverSocket,
             context,
@@ -215,8 +212,8 @@
             supportedProtocols));
   }
 
-  StreamSubscription<RawSecureSocket> listen(void onData(RawSecureSocket s),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<RawSecureSocket> listen(void onData(RawSecureSocket s)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     return _controller.stream.listen(onData,
         onError: onError, onDone: onDone, cancelOnError: cancelOnError);
   }
@@ -249,11 +246,8 @@
       // Do nothing - connection is closed.
       return;
     }
-    _RawSecureSocket
-        .connect(connection.address, remotePort,
+    _RawSecureSocket.connect(connection.address, remotePort, true, connection,
             context: _context,
-            is_server: true,
-            socket: connection,
             requestClientCertificate: requestClientCertificate,
             requireClientCertificate: requireClientCertificate,
             supportedProtocols: supportedProtocols)
@@ -272,9 +266,9 @@
 
   void _onPauseStateChange() {
     if (_controller.isPaused) {
-      _subscription.pause();
+      _subscription!.pause();
     } else {
-      _subscription.resume();
+      _subscription!.resume();
     }
   }
 
diff --git a/sdk_nnbd/lib/io/secure_socket.dart b/sdk_nnbd/lib/io/secure_socket.dart
index 6d23b13..2f6fc00 100644
--- a/sdk_nnbd/lib/io/secure_socket.dart
+++ b/sdk_nnbd/lib/io/secure_socket.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -44,10 +42,10 @@
 
    */
   static Future<SecureSocket> connect(host, int port,
-      {SecurityContext context,
-      bool onBadCertificate(X509Certificate certificate),
-      List<String> supportedProtocols,
-      Duration timeout}) {
+      {SecurityContext? context,
+      bool onBadCertificate(X509Certificate certificate)?,
+      List<String>? supportedProtocols,
+      Duration? timeout}) {
     return RawSecureSocket.connect(host, port,
             context: context,
             onBadCertificate: onBadCertificate,
@@ -60,9 +58,9 @@
   /// [ConnectionTask] that can be cancelled if the [SecureSocket] is no
   /// longer needed.
   static Future<ConnectionTask<SecureSocket>> startConnect(host, int port,
-      {SecurityContext context,
-      bool onBadCertificate(X509Certificate certificate),
-      List<String> supportedProtocols}) {
+      {SecurityContext? context,
+      bool onBadCertificate(X509Certificate certificate)?,
+      List<String>? supportedProtocols}) {
     return RawSecureSocket.startConnect(host, port,
             context: context,
             onBadCertificate: onBadCertificate,
@@ -70,8 +68,7 @@
         .then((rawState) {
       Future<SecureSocket> socket =
           rawState.socket.then((rawSocket) => new SecureSocket._(rawSocket));
-      return new ConnectionTask<SecureSocket>._(
-          socket: socket, onCancel: rawState._onCancel);
+      return new ConnectionTask<SecureSocket>._(socket, rawState._onCancel);
     });
   }
 
@@ -110,9 +107,9 @@
    */
   static Future<SecureSocket> secure(Socket socket,
       {host,
-      SecurityContext context,
-      bool onBadCertificate(X509Certificate certificate),
-      @Since("2.6") List<String> supportedProtocols}) {
+      SecurityContext? context,
+      bool onBadCertificate(X509Certificate certificate)?,
+      @Since("2.6") List<String>? supportedProtocols}) {
     return ((socket as dynamic /*_Socket*/)._detachRaw() as Future)
         .then<RawSecureSocket>((detachedRaw) {
       return RawSecureSocket.secure(detachedRaw[0] as RawSocket,
@@ -146,11 +143,11 @@
    *
    */
   static Future<SecureSocket> secureServer(
-      Socket socket, SecurityContext context,
-      {List<int> bufferedData,
+      Socket socket, SecurityContext? context,
+      {List<int>? bufferedData,
       bool requestClientCertificate: false,
       bool requireClientCertificate: false,
-      List<String> supportedProtocols}) {
+      List<String>? supportedProtocols}) {
     return ((socket as dynamic /*_Socket*/)._detachRaw() as Future)
         .then<RawSecureSocket>((detachedRaw) {
       return RawSecureSocket.secureServer(detachedRaw[0] as RawSocket, context,
@@ -169,7 +166,7 @@
    * client certificate was received.  If it is the client end,
    * [peerCertificate] will return the server's certificate.
    */
-  X509Certificate get peerCertificate;
+  X509Certificate? get peerCertificate;
 
   /**
    * The protocol which was selected during ALPN protocol negotiation.
@@ -178,7 +175,7 @@
    * specify a list of supported ALPN protocols or there was no common
    * protocol between client and server.
    */
-  String get selectedProtocol;
+  String? get selectedProtocol;
 
   /**
    * Renegotiate an existing secure connection, renewing the session keys
@@ -228,12 +225,11 @@
    * can be obtained via [RawSecureSocket.selectedProtocol].
    */
   static Future<RawSecureSocket> connect(host, int port,
-      {SecurityContext context,
-      bool onBadCertificate(X509Certificate certificate),
-      List<String> supportedProtocols,
-      Duration timeout}) {
-    _RawSecureSocket._verifyFields(
-        host, port, false, false, false, onBadCertificate);
+      {SecurityContext? context,
+      bool onBadCertificate(X509Certificate certificate)?,
+      List<String>? supportedProtocols,
+      Duration? timeout}) {
+    _RawSecureSocket._verifyFields(host, port, false, false);
     return RawSocket.connect(host, port, timeout: timeout).then((socket) {
       return secure(socket,
           context: context,
@@ -246,9 +242,9 @@
   /// [ConnectionTask] that can be cancelled if the [RawSecureSocket] is no
   /// longer needed.
   static Future<ConnectionTask<RawSecureSocket>> startConnect(host, int port,
-      {SecurityContext context,
-      bool onBadCertificate(X509Certificate certificate),
-      List<String> supportedProtocols}) {
+      {SecurityContext? context,
+      bool onBadCertificate(X509Certificate certificate)?,
+      List<String>? supportedProtocols}) {
     return RawSocket.startConnect(host, port)
         .then((ConnectionTask<RawSocket> rawState) {
       Future<RawSecureSocket> socket = rawState.socket.then((rawSocket) {
@@ -257,8 +253,7 @@
             onBadCertificate: onBadCertificate,
             supportedProtocols: supportedProtocols);
       });
-      return new ConnectionTask<RawSecureSocket>._(
-          socket: socket, onCancel: rawState._onCancel);
+      return new ConnectionTask<RawSecureSocket>._(socket, rawState._onCancel);
     });
   }
 
@@ -296,17 +291,15 @@
    *
    */
   static Future<RawSecureSocket> secure(RawSocket socket,
-      {StreamSubscription<RawSocketEvent> subscription,
+      {StreamSubscription<RawSocketEvent>? subscription,
       host,
-      SecurityContext context,
-      bool onBadCertificate(X509Certificate certificate),
-      List<String> supportedProtocols}) {
+      SecurityContext? context,
+      bool onBadCertificate(X509Certificate certificate)?,
+      List<String>? supportedProtocols}) {
     socket.readEventsEnabled = false;
     socket.writeEventsEnabled = false;
     return _RawSecureSocket.connect(
-        host != null ? host : socket.address.host, socket.port,
-        is_server: false,
-        socket: socket,
+        host != null ? host : socket.address.host, socket.port, false, socket,
         subscription: subscription,
         context: context,
         onBadCertificate: onBadCertificate,
@@ -337,18 +330,17 @@
    *
    */
   static Future<RawSecureSocket> secureServer(
-      RawSocket socket, SecurityContext context,
-      {StreamSubscription<RawSocketEvent> subscription,
-      List<int> bufferedData,
+      RawSocket socket, SecurityContext? context,
+      {StreamSubscription<RawSocketEvent>? subscription,
+      List<int>? bufferedData,
       bool requestClientCertificate: false,
       bool requireClientCertificate: false,
-      List<String> supportedProtocols}) {
+      List<String>? supportedProtocols}) {
     socket.readEventsEnabled = false;
     socket.writeEventsEnabled = false;
-    return _RawSecureSocket.connect(socket.address, socket.remotePort,
+    return _RawSecureSocket.connect(
+        socket.address, socket.remotePort, true, socket,
         context: context,
-        is_server: true,
-        socket: socket,
         subscription: subscription,
         bufferedData: bufferedData,
         requestClientCertificate: requestClientCertificate,
@@ -375,7 +367,7 @@
    * client certificate was received.  If it is the client end,
    * [peerCertificate] will return the server's certificate.
    */
-  X509Certificate get peerCertificate;
+  X509Certificate? get peerCertificate;
 
   /**
    * The protocol which was selected during protocol negotiation.
@@ -384,7 +376,7 @@
    * specify a list of supported ALPN protocols or there was no common
    * protocol between client and server.
    */
-  String get selectedProtocol;
+  String? get selectedProtocol;
 }
 
 /**
@@ -443,20 +435,19 @@
   static bool _isBufferEncrypted(int identifier) =>
       identifier >= readEncryptedId;
 
-  RawSocket _socket;
+  final RawSocket _socket;
   final Completer<_RawSecureSocket> _handshakeComplete =
       new Completer<_RawSecureSocket>();
-  StreamController<RawSocketEvent> _controller;
-  Stream<RawSocketEvent> _stream;
-  StreamSubscription<RawSocketEvent> _socketSubscription;
-  List<int> _bufferedData;
+  final _controller = new StreamController<RawSocketEvent>(sync: true);
+  late final StreamSubscription<RawSocketEvent> _socketSubscription;
+  List<int>? _bufferedData;
   int _bufferedDataIndex = 0;
   final InternetAddress address;
-  final bool is_server;
-  SecurityContext context;
+  final bool isServer;
+  final SecurityContext context;
   final bool requestClientCertificate;
   final bool requireClientCertificate;
-  final Function onBadCertificate;
+  final bool Function(X509Certificate certificate)? onBadCertificate;
 
   var _status = handshakeStatus;
   bool _writeEventsEnabled = true;
@@ -474,22 +465,23 @@
   bool _filterPending = false;
   bool _filterActive = false;
 
-  _SecureFilter _secureFilter = new _SecureFilter._();
-  String _selectedProtocol;
+  _SecureFilter? _secureFilter = new _SecureFilter._();
+  String? _selectedProtocol;
 
   static Future<_RawSecureSocket> connect(
-      dynamic /*String|InternetAddress*/ host, int requestedPort,
-      {bool is_server,
-      SecurityContext context,
+      dynamic /*String|InternetAddress*/ host,
+      int requestedPort,
+      bool isServer,
       RawSocket socket,
-      StreamSubscription<RawSocketEvent> subscription,
-      List<int> bufferedData,
+      {SecurityContext? context,
+      StreamSubscription<RawSocketEvent>? subscription,
+      List<int>? bufferedData,
       bool requestClientCertificate: false,
       bool requireClientCertificate: false,
-      bool onBadCertificate(X509Certificate certificate),
-      List<String> supportedProtocols}) {
-    _verifyFields(host, requestedPort, is_server, requestClientCertificate,
-        requireClientCertificate, onBadCertificate);
+      bool onBadCertificate(X509Certificate certificate)?,
+      List<String>? supportedProtocols}) {
+    _verifyFields(host, requestedPort, requestClientCertificate,
+        requireClientCertificate);
     if (host is InternetAddress) host = host.host;
     InternetAddress address = socket.address;
     if (host != null) {
@@ -498,8 +490,8 @@
     return new _RawSecureSocket(
             address,
             requestedPort,
-            is_server,
-            context,
+            isServer,
+            context ?? SecurityContext.defaultContext,
             socket,
             subscription,
             bufferedData,
@@ -514,39 +506,38 @@
   _RawSecureSocket(
       this.address,
       int requestedPort,
-      this.is_server,
+      this.isServer,
       this.context,
       this._socket,
-      this._socketSubscription,
+      StreamSubscription<RawSocketEvent>? subscription,
       this._bufferedData,
       this.requestClientCertificate,
       this.requireClientCertificate,
       this.onBadCertificate,
-      List<String> supportedProtocols) {
-    context ??= SecurityContext.defaultContext;
-    _controller = new StreamController<RawSocketEvent>(
-        sync: true,
-        onListen: _onSubscriptionStateChange,
-        onPause: _onPauseStateChange,
-        onResume: _onPauseStateChange,
-        onCancel: _onSubscriptionStateChange);
-    _stream = _controller.stream;
+      List<String>? supportedProtocols) {
+    _controller
+      ..onListen = _onSubscriptionStateChange
+      ..onPause = _onPauseStateChange
+      ..onResume = _onPauseStateChange
+      ..onCancel = _onSubscriptionStateChange;
     // Throw an ArgumentError if any field is invalid.  After this, all
     // errors will be reported through the future or the stream.
-    _secureFilter.init();
-    _secureFilter
+    final secureFilter = _secureFilter!;
+    secureFilter.init();
+    secureFilter
         .registerHandshakeCompleteCallback(_secureHandshakeCompleteHandler);
     if (onBadCertificate != null) {
-      _secureFilter.registerBadCertificateCallback(_onBadCertificateWrapper);
+      secureFilter.registerBadCertificateCallback(_onBadCertificateWrapper);
     }
     _socket.readEventsEnabled = true;
     _socket.writeEventsEnabled = false;
-    if (_socketSubscription == null) {
+    if (subscription == null) {
       // If a current subscription is provided use this otherwise
       // create a new one.
       _socketSubscription = _socket.listen(_eventDispatcher,
           onError: _reportError, onDone: _doneHandler);
     } else {
+      _socketSubscription = subscription;
       if (_socketSubscription.isPaused) {
         _socket.close();
         throw new ArgumentError("Subscription passed to TLS upgrade is paused");
@@ -565,10 +556,10 @@
     try {
       var encodedProtocols =
           SecurityContext._protocolsToLengthEncoding(supportedProtocols);
-      _secureFilter.connect(
+      secureFilter.connect(
           address.host,
           context,
-          is_server,
+          isServer,
           requestClientCertificate || requireClientCertificate,
           requireClientCertificate,
           encodedProtocols);
@@ -578,27 +569,24 @@
     }
   }
 
-  StreamSubscription<RawSocketEvent> listen(void onData(RawSocketEvent data),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<RawSocketEvent> listen(void onData(RawSocketEvent data)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     _sendWriteEvent();
-    return _stream.listen(onData,
+    return _controller.stream.listen(onData,
         onError: onError, onDone: onDone, cancelOnError: cancelOnError);
   }
 
-  static void _verifyFields(
-      host,
-      int requestedPort,
-      bool is_server,
-      bool requestClientCertificate,
-      bool requireClientCertificate,
-      Function onBadCertificate) {
+  static void _verifyFields(host, int requestedPort,
+      bool requestClientCertificate, bool requireClientCertificate) {
     if (host is! String && host is! InternetAddress) {
       throw new ArgumentError("host is not a String or an InternetAddress");
     }
+    // TODO: Remove once non-nullability is sound.
     ArgumentError.checkNotNull(requestedPort, "requestedPort");
     if (requestedPort < 0 || requestedPort > 65535) {
       throw ArgumentError("requestedPort is not in the range 0..65535");
     }
+    // TODO: Remove once non-nullability is sound.
     ArgumentError.checkNotNull(
         requestClientCertificate, "requestClientCertificate");
     ArgumentError.checkNotNull(
@@ -618,7 +606,7 @@
   int available() {
     return _status != connectedStatus
         ? 0
-        : _secureFilter.buffers[readPlaintextId].length;
+        : _secureFilter!.buffers![readPlaintextId].length;
   }
 
   Future<RawSecureSocket> close() {
@@ -626,22 +614,18 @@
     return _closeCompleter.future;
   }
 
-  void _completeCloseCompleter([RawSocket dummy]) {
+  void _completeCloseCompleter([RawSocket? dummy]) {
     if (!_closeCompleter.isCompleted) _closeCompleter.complete(this);
   }
 
   void _close() {
     _closedWrite = true;
     _closedRead = true;
-    if (_socket != null) {
-      _socket.close().then(_completeCloseCompleter);
-    } else {
-      _completeCloseCompleter();
-    }
+    _socket.close().then(_completeCloseCompleter);
     _socketClosedWrite = true;
     _socketClosedRead = true;
     if (!_filterActive && _secureFilter != null) {
-      _secureFilter.destroy();
+      _secureFilter!.destroy();
       _secureFilter = null;
     }
     if (_socketSubscription != null) {
@@ -690,8 +674,8 @@
     _scheduleReadEvent();
   }
 
-  Uint8List read([int length]) {
-    if (length != null && (length is! int || length < 0)) {
+  Uint8List? read([int? length]) {
+    if (length != null && length < 0) {
       throw new ArgumentError(
           "Invalid length parameter in SecureSocket.read (length: $length)");
     }
@@ -701,18 +685,22 @@
     if (_status != connectedStatus) {
       return null;
     }
-    var result = _secureFilter.buffers[readPlaintextId].read(length);
+    var result = _secureFilter!.buffers![readPlaintextId].read(length);
     _scheduleFilter();
     return result;
   }
 
+  static int _fixOffset(int? offset) => offset ?? 0;
+
   // Write the data to the socket, and schedule the filter to encrypt it.
-  int write(List<int> data, [int offset, int bytes]) {
-    if (bytes != null && (bytes is! int || bytes < 0)) {
+  int write(List<int> data, [int offset = 0, int? bytes]) {
+    if (bytes != null && bytes < 0) {
       throw new ArgumentError(
           "Invalid bytes parameter in SecureSocket.read (bytes: $bytes)");
     }
-    if (offset != null && (offset is! int || offset < 0)) {
+    // TODO: Remove once non-nullability is sound.
+    offset = _fixOffset(offset);
+    if (offset < 0) {
       throw new ArgumentError(
           "Invalid offset parameter in SecureSocket.read (offset: $offset)");
     }
@@ -725,7 +713,7 @@
     bytes ??= data.length - offset;
 
     int written =
-        _secureFilter.buffers[writePlaintextId].write(data, offset, bytes);
+        _secureFilter!.buffers![writePlaintextId].write(data, offset, bytes);
     if (written > 0) {
       _filterStatus.writeEmpty = false;
     }
@@ -733,29 +721,25 @@
     return written;
   }
 
-  X509Certificate get peerCertificate => _secureFilter.peerCertificate;
+  X509Certificate? get peerCertificate => _secureFilter!.peerCertificate;
 
-  String get selectedProtocol => _selectedProtocol;
+  String? get selectedProtocol => _selectedProtocol;
 
   bool _onBadCertificateWrapper(X509Certificate certificate) {
     if (onBadCertificate == null) return false;
-    var result = onBadCertificate(certificate);
-    if (result is bool) return result;
-    throw new HandshakeException(
-        "onBadCertificate callback returned non-boolean $result");
+    return onBadCertificate!(certificate);
   }
 
   bool setOption(SocketOption option, bool enabled) {
-    if (_socket == null) return false;
     return _socket.setOption(option, enabled);
   }
 
   Uint8List getRawOption(RawSocketOption option) {
-    return _socket?.getRawOption(option);
+    return _socket.getRawOption(option);
   }
 
   void setRawOption(RawSocketOption option) {
-    _socket?.setRawOption(option);
+    _socket.setRawOption(option);
   }
 
   void _eventDispatcher(RawSocketEvent event) {
@@ -788,7 +772,7 @@
     }
   }
 
-  void _reportError(e, [StackTrace stackTrace]) {
+  void _reportError(e, [StackTrace? stackTrace]) {
     if (_status == closedStatus) {
       return;
     } else if (_connectPending) {
@@ -829,7 +813,7 @@
 
   void _secureHandshake() {
     try {
-      _secureFilter.handshake();
+      _secureFilter!.handshake();
       _filterStatus.writeEmpty = false;
       _readSocket();
       _writeSocket();
@@ -847,7 +831,7 @@
       throw new HandshakeException(
           "Called renegotiate on a non-connected socket");
     }
-    _secureFilter.renegotiate(
+    _secureFilter!.renegotiate(
         useSessionCache, requestClientCertificate, requireClientCertificate);
     _status = handshakeStatus;
     _filterStatus.writeEmpty = false;
@@ -859,7 +843,7 @@
     if (_connectPending) {
       _connectPending = false;
       try {
-        _selectedProtocol = _secureFilter.selectedProtocol();
+        _selectedProtocol = _secureFilter!.selectedProtocol();
         // We don't want user code to run synchronously in this callback.
         Timer.run(() => _handshakeComplete.complete(this));
       } catch (error, stack) {
@@ -910,7 +894,7 @@
         _filterStatus = status;
         _filterActive = false;
         if (_status == closedStatus) {
-          _secureFilter.destroy();
+          _secureFilter!.destroy();
           _secureFilter = null;
           return;
         }
@@ -924,7 +908,7 @@
         }
         if (_filterStatus.readEmpty && _socketClosedRead && !_closedRead) {
           if (_status == handshakeStatus) {
-            _secureFilter.handshake();
+            _secureFilter!.handshake();
             if (_status == handshakeStatus) {
               throw new HandshakeException(
                   'Connection terminated during handshake');
@@ -958,15 +942,16 @@
     }
   }
 
-  List<int> _readSocketOrBufferedData(int bytes) {
-    if (_bufferedData != null) {
-      if (bytes > _bufferedData.length - _bufferedDataIndex) {
-        bytes = _bufferedData.length - _bufferedDataIndex;
+  List<int>? _readSocketOrBufferedData(int bytes) {
+    final bufferedData = _bufferedData;
+    if (bufferedData != null) {
+      if (bytes > bufferedData.length - _bufferedDataIndex) {
+        bytes = bufferedData.length - _bufferedDataIndex;
       }
       var result =
-          _bufferedData.sublist(_bufferedDataIndex, _bufferedDataIndex + bytes);
+          bufferedData.sublist(_bufferedDataIndex, _bufferedDataIndex + bytes);
       _bufferedDataIndex += bytes;
-      if (_bufferedData.length == _bufferedDataIndex) {
+      if (bufferedData.length == _bufferedDataIndex) {
         _bufferedData = null;
       }
       return result;
@@ -979,7 +964,7 @@
 
   void _readSocket() {
     if (_status == closedStatus) return;
-    var buffer = _secureFilter.buffers[readEncryptedId];
+    var buffer = _secureFilter!.buffers![readEncryptedId];
     if (buffer.writeFromSource(_readSocketOrBufferedData) > 0) {
       _filterStatus.readEmpty = false;
     } else {
@@ -989,7 +974,7 @@
 
   void _writeSocket() {
     if (_socketClosedWrite) return;
-    var buffer = _secureFilter.buffers[writeEncryptedId];
+    var buffer = _secureFilter!.buffers![writeEncryptedId];
     if (buffer.readToSocket(_socket)) {
       // Returns true if blocked
       _socket.writeEventsEnabled = true;
@@ -1002,7 +987,7 @@
         _readEventsEnabled &&
         _pauseCount == 0 &&
         _secureFilter != null &&
-        !_secureFilter.buffers[readPlaintextId].isEmpty) {
+        !_secureFilter!.buffers![readPlaintextId].isEmpty) {
       _pendingReadEvent = true;
       Timer.run(_sendReadEvent);
     }
@@ -1014,7 +999,7 @@
         _readEventsEnabled &&
         _pauseCount == 0 &&
         _secureFilter != null &&
-        !_secureFilter.buffers[readPlaintextId].isEmpty) {
+        !_secureFilter!.buffers![readPlaintextId].isEmpty) {
       _controller.add(RawSocketEvent.read);
       _scheduleReadEvent();
     }
@@ -1026,7 +1011,7 @@
         _writeEventsEnabled &&
         _pauseCount == 0 &&
         _secureFilter != null &&
-        _secureFilter.buffers[writePlaintextId].free > 0) {
+        _secureFilter!.buffers![writePlaintextId].free > 0) {
       _writeEventsEnabled = false;
       _controller.add(RawSocketEvent.write);
     }
@@ -1035,9 +1020,9 @@
   Future<_FilterStatus> _pushAllFilterStages() {
     bool wasInHandshake = _status != connectedStatus;
     List args = new List.filled(2 + bufferCount * 2, null);
-    args[0] = _secureFilter._pointer();
+    args[0] = _secureFilter!._pointer();
     args[1] = wasInHandshake;
-    var bufs = _secureFilter.buffers;
+    var bufs = _secureFilter!.buffers!;
     for (var i = 0; i < bufferCount; ++i) {
       args[2 * i + 2] = bufs[i].start;
       args[2 * i + 3] = bufs[i].end;
@@ -1123,7 +1108,7 @@
 class _ExternalBuffer {
   // This will be an ExternalByteArray, backed by C allocated data.
   @pragma("vm:entry-point", "set")
-  List<int> data;
+  List<int>? data;
 
   @pragma("vm:entry-point")
   int start;
@@ -1131,11 +1116,12 @@
   @pragma("vm:entry-point")
   int end;
 
-  final size;
+  final int size;
 
-  _ExternalBuffer(this.size) {
-    start = end = size ~/ 2;
-  }
+  _ExternalBuffer(int size)
+      : size = size,
+        start = size ~/ 2,
+        end = size ~/ 2;
 
   void advanceStart(int bytes) {
     assert(start > end || start + bytes <= end);
@@ -1171,7 +1157,7 @@
     return size - end;
   }
 
-  Uint8List read(int bytes) {
+  Uint8List? read(int? bytes) {
     if (bytes == null) {
       bytes = length;
     } else {
@@ -1183,7 +1169,7 @@
     // Loop over zero, one, or two linear data ranges.
     while (bytesRead < bytes) {
       int toRead = min(bytes - bytesRead, linearLength);
-      result.setRange(bytesRead, bytesRead + toRead, data, start);
+      result.setRange(bytesRead, bytesRead + toRead, data!, start);
       advanceStart(toRead);
       bytesRead += toRead;
     }
@@ -1198,7 +1184,7 @@
     int toWrite = min(bytes, linearFree);
     // Loop over zero, one, or two linear data ranges.
     while (toWrite > 0) {
-      data.setRange(end, end + toWrite, inputData, offset);
+      data!.setRange(end, end + toWrite, inputData, offset);
       advanceEnd(toWrite);
       offset += toWrite;
       written += toWrite;
@@ -1207,7 +1193,7 @@
     return written;
   }
 
-  int writeFromSource(List<int> getData(int requested)) {
+  int writeFromSource(List<int>? getData(int requested)) {
     int written = 0;
     int toWrite = linearFree;
     // Loop over zero, one, or two linear data ranges.
@@ -1216,7 +1202,7 @@
       var inputData = getData(toWrite);
       if (inputData == null || inputData.length == 0) break;
       var len = inputData.length;
-      data.setRange(end, end + len, inputData);
+      data!.setRange(end, end + len, inputData);
       advanceEnd(len);
       written += len;
       toWrite = linearFree;
@@ -1229,7 +1215,7 @@
     while (true) {
       var toWrite = linearLength;
       if (toWrite == 0) return false;
-      int bytes = socket.write(data, start, toWrite);
+      int bytes = socket.write(data!, start, toWrite);
       advanceStart(bytes);
       if (bytes < toWrite) {
         // The socket has blocked while we have data to write.
@@ -1245,7 +1231,7 @@
   void connect(
       String hostName,
       SecurityContext context,
-      bool is_server,
+      bool isServer,
       bool requestClientCertificate,
       bool requireClientCertificate,
       Uint8List protocols);
@@ -1256,7 +1242,7 @@
   void renegotiate(bool useSessionCache, bool requestClientCertificate,
       bool requireClientCertificate);
   void init();
-  X509Certificate get peerCertificate;
+  X509Certificate? get peerCertificate;
   int processBuffer(int bufferIndex);
   void registerBadCertificateCallback(Function callback);
   void registerHandshakeCompleteCallback(Function handshakeCompleteHandler);
@@ -1266,7 +1252,7 @@
   // value is passed to the IO service through a call to dispatch().
   int _pointer();
 
-  List<_ExternalBuffer> get buffers;
+  List<_ExternalBuffer>? get buffers;
 }
 
 /** A secure networking exception caused by a failure in the
@@ -1275,10 +1261,10 @@
 class TlsException implements IOException {
   final String type;
   final String message;
-  final OSError osError;
+  final OSError? osError;
 
   @pragma("vm:entry-point")
-  const TlsException([String message = "", OSError osError])
+  const TlsException([String message = "", OSError? osError])
       : this._("TlsException", message, osError);
 
   const TlsException._(this.type, this.message, this.osError);
@@ -1305,7 +1291,7 @@
 @pragma("vm:entry-point")
 class HandshakeException extends TlsException {
   @pragma("vm:entry-point")
-  const HandshakeException([String message = "", OSError osError])
+  const HandshakeException([String message = "", OSError? osError])
       : super._("HandshakeException", message, osError);
 }
 
@@ -1316,6 +1302,6 @@
  */
 class CertificateException extends TlsException {
   @pragma("vm:entry-point")
-  const CertificateException([String message = "", OSError osError])
+  const CertificateException([String message = "", OSError? osError])
       : super._("CertificateException", message, osError);
 }
diff --git a/sdk_nnbd/lib/io/security_context.dart b/sdk_nnbd/lib/io/security_context.dart
index 78a4569..e4fd5c6 100644
--- a/sdk_nnbd/lib/io/security_context.dart
+++ b/sdk_nnbd/lib/io/security_context.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -69,7 +67,7 @@
    * data is used instead of two calls to [useCertificateChain] and
    * [usePrivateKey].
    */
-  void usePrivateKey(String file, {String password});
+  void usePrivateKey(String file, {String? password});
 
   /**
    * Sets the private key for a server certificate or client certificate.
@@ -77,7 +75,7 @@
    * Like [usePrivateKey], but takes the contents of the file as a list
    * of bytes.
    */
-  void usePrivateKeyBytes(List<int> keyBytes, {String password});
+  void usePrivateKeyBytes(List<int> keyBytes, {String? password});
 
   /**
    * Sets the set of trusted X509 certificates used by [SecureSocket]
@@ -99,7 +97,7 @@
    *
    *   $ openssl x509 -outform der -in cert.pem -out cert.der
    */
-  void setTrustedCertificates(String file, {String password});
+  void setTrustedCertificates(String file, {String? password});
 
   /**
    * Sets the set of trusted X509 certificates used by [SecureSocket]
@@ -107,7 +105,7 @@
    *
    * Like [setTrustedCertificates] but takes the contents of the file.
    */
-  void setTrustedCertificatesBytes(List<int> certBytes, {String password});
+  void setTrustedCertificatesBytes(List<int> certBytes, {String? password});
 
   /**
    * Sets the chain of X509 certificates served by [SecureServerSocket]
@@ -127,7 +125,7 @@
    * iOS note: As noted above, [usePrivateKey] does the job of both
    * that call and this one. On iOS, this call is a no-op.
    */
-  void useCertificateChain(String file, {String password});
+  void useCertificateChain(String file, {String? password});
 
   /**
    * Sets the chain of X509 certificates served by [SecureServerSocket]
@@ -135,7 +133,7 @@
    *
    * Like [useCertificateChain] but takes the contents of the file.
    */
-  void useCertificateChainBytes(List<int> chainBytes, {String password});
+  void useCertificateChainBytes(List<int> chainBytes, {String? password});
 
   /**
    * Sets the list of authority names that a [SecureServerSocket] will advertise
@@ -153,7 +151,7 @@
    *
    * iOS note: This call is not supported.
    */
-  void setClientAuthorities(String file, {String password});
+  void setClientAuthorities(String file, {String? password});
 
   /**
    * Sets the list of authority names that a [SecureServerSocket] will advertise
@@ -162,7 +160,7 @@
    *
    * Like [setClientAuthorities] but takes the contents of the file.
    */
-  void setClientAuthoritiesBytes(List<int> authCertBytes, {String password});
+  void setClientAuthoritiesBytes(List<int> authCertBytes, {String? password});
 
   /**
    * Whether the platform supports ALPN. This always returns true and will be
@@ -205,7 +203,7 @@
   /// `ProtocolNameList` length of 65535, this limit cannot be reached. Testing
   /// showed that more than ~ 2^14  bytes will fail to negotiate a protocol.
   /// We will be conservative and support only messages up to (1<<13)-1 bytes.
-  static Uint8List _protocolsToLengthEncoding(List<String> protocols) {
+  static Uint8List _protocolsToLengthEncoding(List<String>? protocols) {
     if (protocols == null || protocols.length == 0) {
       return new Uint8List(0);
     }
diff --git a/sdk_nnbd/lib/io/service_object.dart b/sdk_nnbd/lib/io/service_object.dart
index 54db0ea..e6b1851 100644
--- a/sdk_nnbd/lib/io/service_object.dart
+++ b/sdk_nnbd/lib/io/service_object.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 int _nextServiceId = 1;
diff --git a/sdk_nnbd/lib/io/socket.dart b/sdk_nnbd/lib/io/socket.dart
index 1ee61a8..dc92d8b 100644
--- a/sdk_nnbd/lib/io/socket.dart
+++ b/sdk_nnbd/lib/io/socket.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -331,7 +329,7 @@
    */
   static Future<ServerSocket> bind(address, int port,
       {int backlog: 0, bool v6Only: false, bool shared: false}) {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return ServerSocket._bind(address, port,
           backlog: backlog, v6Only: v6Only, shared: shared);
@@ -429,8 +427,6 @@
 class RawSocketOption {
   /// Creates a RawSocketOption for getRawOption andSetRawOption.
   ///
-  /// All arguments are required and must not be null.
-  ///
   /// The level and option arguments correspond to level and optname arguments
   /// on the get/setsockopt native calls.
   ///
@@ -446,9 +442,6 @@
 
   /// Convenience constructor for creating an int based RawSocketOption.
   factory RawSocketOption.fromInt(int level, int option, int value) {
-    if (value == null) {
-      value = 0;
-    }
     final Uint8List list = Uint8List(4);
     final buffer = ByteData.view(list.buffer, list.offsetInBytes);
     buffer.setInt32(0, value, Endian.host);
@@ -457,7 +450,7 @@
 
   /// Convenience constructor for creating a bool based RawSocketOption.
   factory RawSocketOption.fromBool(int level, int option, bool value) =>
-      RawSocketOption.fromInt(level, option, value == true ? 1 : 0);
+      RawSocketOption.fromInt(level, option, value ? 1 : 0);
 
   /// The level for the option to set or get.
   ///
@@ -553,11 +546,8 @@
   final Future<S> socket;
   final void Function() _onCancel;
 
-  ConnectionTask._({Future<S> socket, void Function() onCancel})
-      : assert(socket != null),
-        assert(onCancel != null),
-        this.socket = socket,
-        this._onCancel = onCancel;
+  ConnectionTask._(Future<S> this.socket, void Function() onCancel)
+      : _onCancel = onCancel;
 
   /// Cancels the connection attempt.
   ///
@@ -582,7 +572,8 @@
    * Set or get, if the [RawSocket] should listen for [RawSocketEvent.read]
    * events. Default is [:true:].
    */
-  bool readEventsEnabled;
+  bool get readEventsEnabled;
+  void set readEventsEnabled(bool value);
 
   /**
    * Set or get, if the [RawSocket] should listen for [RawSocketEvent.write]
@@ -590,7 +581,8 @@
    * This is a one-shot listener, and writeEventsEnabled must be set
    * to true again to receive another write event.
    */
-  bool writeEventsEnabled;
+  bool get writeEventsEnabled;
+  void set writeEventsEnabled(bool value);
 
   /**
    * Creates a new socket connection to the host and port and returns a [Future]
@@ -615,7 +607,7 @@
    * connection attempts to [host] are cancelled.
    */
   external static Future<RawSocket> connect(host, int port,
-      {sourceAddress, Duration timeout});
+      {sourceAddress, Duration? timeout});
 
   /// Like [connect], but returns a [Future] that completes with a
   /// [ConnectionTask] that can be cancelled if the [RawSocket] is no
@@ -636,7 +628,7 @@
    * available for immediate reading. If no data is available [:null:]
    * is returned.
    */
-  Uint8List read([int len]);
+  Uint8List? read([int? len]);
 
   /**
    * Writes up to [count] bytes of the buffer from [offset] buffer offset to
@@ -647,25 +639,33 @@
    * The default value for [offset] is 0, and the default value for [count] is
    * [:buffer.length - offset:].
    */
-  int write(List<int> buffer, [int offset, int count]);
+  int write(List<int> buffer, [int offset = 0, int? count]);
 
   /**
    * Returns the port used by this socket.
+   *
+   * Throws a [SocketException] if the socket is closed.
    */
   int get port;
 
   /**
    * Returns the remote port connected to by this socket.
+   *
+   * Throws a [SocketException] if the socket is closed.
    */
   int get remotePort;
 
   /**
    * Returns the [InternetAddress] used to connect this socket.
+   *
+   * Throws a [SocketException] if the socket is closed.
    */
   InternetAddress get address;
 
   /**
    * Returns the remote [InternetAddress] connected to by this socket.
+   *
+   * Throws a [SocketException] if the socket is closed.
    */
   InternetAddress get remoteAddress;
 
@@ -746,8 +746,8 @@
    * connection attempts to [host] are cancelled.
    */
   static Future<Socket> connect(host, int port,
-      {sourceAddress, Duration timeout}) {
-    final IOOverrides overrides = IOOverrides.current;
+      {sourceAddress, Duration? timeout}) {
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return Socket._connect(host, port,
           sourceAddress: sourceAddress, timeout: timeout);
@@ -761,7 +761,7 @@
   /// longer needed.
   static Future<ConnectionTask<Socket>> startConnect(host, int port,
       {sourceAddress}) {
-    final IOOverrides overrides = IOOverrides.current;
+    final IOOverrides? overrides = IOOverrides.current;
     if (overrides == null) {
       return Socket._startConnect(host, port, sourceAddress: sourceAddress);
     }
@@ -770,7 +770,7 @@
   }
 
   external static Future<Socket> _connect(host, int port,
-      {sourceAddress, Duration timeout});
+      {sourceAddress, Duration? timeout});
 
   external static Future<ConnectionTask<Socket>> _startConnect(host, int port,
       {sourceAddress});
@@ -790,6 +790,9 @@
    * available options.
    *
    * Returns [:true:] if the option was set successfully, false otherwise.
+   *
+   * Throws a [SocketException] if the socket has been destroyed or upgraded to
+   * a secure socket.
    */
   bool setOption(SocketOption option, bool enabled);
 
@@ -799,7 +802,8 @@
    *
    * Returns the [RawSocketOption.value] on success.
    *
-   * Throws an [OSError] on failure.
+   * Throws an [OSError] on failure and a [SocketException] if the socket has
+   * been destroyed or upgraded to a secure socket.
    */
   Uint8List getRawOption(RawSocketOption option);
 
@@ -807,27 +811,36 @@
    * Use [setRawOption] to customize the [RawSocket]. See [RawSocketOption] for
    * available options.
    *
-   * Throws an [OSError] on failure.
+   * Throws an [OSError] on failure and a [SocketException] if the socket has
+   * been destroyed or upgraded to a secure socket.
    */
   void setRawOption(RawSocketOption option);
 
   /**
    * Returns the port used by this socket.
+   *
+   * Throws a [SocketException] if the socket is closed.
    */
   int get port;
 
   /**
    * Returns the remote port connected to by this socket.
+   *
+   * Throws a [SocketException] if the socket is closed.
    */
   int get remotePort;
 
   /**
    * Returns the [InternetAddress] used to connect this socket.
+   *
+   * Throws a [SocketException] if the socket is closed.
    */
   InternetAddress get address;
 
   /**
    * Returns the remote [InternetAddress] connected to by this socket.
+   *
+   * Throws a [SocketException] if the socket is closed.
    */
   InternetAddress get remoteAddress;
 
@@ -866,7 +879,8 @@
    * Set or get, if the [RawDatagramSocket] should listen for
    * [RawSocketEvent.read] events. Default is [:true:].
    */
-  bool readEventsEnabled;
+  bool get readEventsEnabled;
+  void set readEventsEnabled(bool value);
 
   /**
    * Set or get, if the [RawDatagramSocket] should listen for
@@ -874,14 +888,16 @@
    * one-shot listener, and writeEventsEnabled must be set to true
    * again to receive another write event.
    */
-  bool writeEventsEnabled;
+  bool get writeEventsEnabled;
+  void set writeEventsEnabled(bool value);
 
   /**
    * Set or get, whether multicast traffic is looped back to the host.
    *
    * By default multicast loopback is enabled.
    */
-  bool multicastLoopback;
+  bool get multicastLoopback;
+  void set multicastLoopback(bool value);
 
   /**
    * Set or get, the maximum network hops for multicast packages
@@ -892,7 +908,8 @@
    * By default this value is 1 causing multicast traffic to stay on
    * the local network.
    */
-  int multicastHops;
+  int get multicastHops;
+  void set multicastHops(int value);
 
   /**
    * Set or get, the network interface used for outgoing multicast packages.
@@ -904,7 +921,7 @@
    */
   @Deprecated("This property is not implemented. Use getRawOption and "
       "setRawOption instead.")
-  NetworkInterface multicastInterface;
+  NetworkInterface? multicastInterface;
 
   /**
    * Set or get, whether IPv4 broadcast is enabled.
@@ -915,7 +932,8 @@
    * For IPv6 there is no general broadcast mechanism. Use multicast
    * instead.
    */
-  bool broadcastEnabled;
+  bool get broadcastEnabled;
+  void set broadcastEnabled(bool value);
 
   /**
    * Creates a new raw datagram socket binding it to an address and
@@ -953,7 +971,7 @@
    *
    * The maximum length of the datagram that can be received is 65503 bytes.
    */
-  Datagram receive();
+  Datagram? receive();
 
   /**
    * Join a multicast group.
@@ -961,7 +979,7 @@
    * If an error occur when trying to join the multicast group an
    * exception is thrown.
    */
-  void joinMulticast(InternetAddress group, [NetworkInterface interface]);
+  void joinMulticast(InternetAddress group, [NetworkInterface? interface]);
 
   /**
    * Leave a multicast group.
@@ -969,7 +987,7 @@
    * If an error occur when trying to join the multicase group an
    * exception is thrown.
    */
-  void leaveMulticast(InternetAddress group, [NetworkInterface interface]);
+  void leaveMulticast(InternetAddress group, [NetworkInterface? interface]);
 
   /**
    * Use [getRawOption] to get low level information about the [RawSocket]. See
@@ -992,9 +1010,9 @@
 
 class SocketException implements IOException {
   final String message;
-  final OSError osError;
-  final InternetAddress address;
-  final int port;
+  final OSError? osError;
+  final InternetAddress? address;
+  final int? port;
 
   const SocketException(this.message, {this.osError, this.address, this.port});
   const SocketException.closed()
@@ -1015,7 +1033,7 @@
       sb.write(": $osError");
     }
     if (address != null) {
-      sb.write(", address = ${address.host}");
+      sb.write(", address = ${address!.host}");
     }
     if (port != null) {
       sb.write(", port = $port");
diff --git a/sdk_nnbd/lib/io/stdio.dart b/sdk_nnbd/lib/io/stdio.dart
index c1aacba..a0034c6 100644
--- a/sdk_nnbd/lib/io/stdio.dart
+++ b/sdk_nnbd/lib/io/stdio.dart
@@ -2,23 +2,23 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
+// These match enum StdioHandleType in file.h
 const int _stdioHandleTypeTerminal = 0;
 const int _stdioHandleTypePipe = 1;
 const int _stdioHandleTypeFile = 2;
 const int _stdioHandleTypeSocket = 3;
 const int _stdioHandleTypeOther = 4;
+const int _stdioHandleTypeError = 5;
 
 class _StdStream extends Stream<List<int>> {
   final Stream<List<int>> _stream;
 
   _StdStream(this._stream);
 
-  StreamSubscription<List<int>> listen(void onData(List<int> event),
-      {Function onError, void onDone(), bool cancelOnError}) {
+  StreamSubscription<List<int>> listen(void onData(List<int> event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
     return _stream.listen(onData,
         onError: onError, onDone: onDone, cancelOnError: cancelOnError);
   }
@@ -55,7 +55,7 @@
    * that data is returned without a line terminator.
    * Returns `null` if no bytes preceded the end of input.
    */
-  String readLineSync(
+  String? readLineSync(
       {Encoding encoding: systemEncoding, bool retainNewlines: false}) {
     const CR = 13;
     const LF = 10;
@@ -212,7 +212,7 @@
  */
 class Stdout extends _StdSink implements IOSink {
   final int _fd;
-  IOSink _nonBlocking;
+  IOSink? _nonBlocking;
 
   Stdout._(IOSink sink, this._fd) : super(sink);
 
@@ -270,14 +270,13 @@
    * Get a non-blocking `IOSink`.
    */
   IOSink get nonBlocking {
-    _nonBlocking ??= new IOSink(new _FileStreamConsumer.fromStdio(_fd));
-    return _nonBlocking;
+    return _nonBlocking ??= new IOSink(new _FileStreamConsumer.fromStdio(_fd));
   }
 }
 
 class StdoutException implements IOException {
   final String message;
-  final OSError osError;
+  final OSError? osError;
 
   const StdoutException(this.message, [this.osError]);
 
@@ -288,7 +287,7 @@
 
 class StdinException implements IOException {
   final String message;
-  final OSError osError;
+  final OSError? osError;
 
   const StdinException(this.message, [this.osError]);
 
@@ -335,15 +334,15 @@
     _sink.encoding = encoding;
   }
 
-  void write(object) {
+  void write(Object? object) {
     _sink.write(object);
   }
 
-  void writeln([object = ""]) {
+  void writeln([Object? object = ""]) {
     _sink.writeln(object);
   }
 
-  void writeAll(objects, [sep = ""]) {
+  void writeAll(Iterable objects, [String sep = ""]) {
     _sink.writeAll(objects, sep);
   }
 
@@ -351,7 +350,7 @@
     _sink.add(data);
   }
 
-  void addError(error, [StackTrace stackTrace]) {
+  void addError(error, [StackTrace? stackTrace]) {
     _sink.addError(error, stackTrace);
   }
 
@@ -386,9 +385,9 @@
   String toString() => "StdioType: $name";
 }
 
-Stdin _stdin;
-Stdout _stdout;
-Stdout _stderr;
+Stdin? _stdin;
+Stdout? _stdout;
+Stdout? _stderr;
 
 // These may be set to different values by the embedder by calling
 // _setStdioFDs when initializing dart:io.
@@ -405,8 +404,7 @@
 
 /// The standard input stream of data read by this program.
 Stdin get stdin {
-  _stdin ??= _StdIOUtils._getStdioInputStream(_stdinFD);
-  return _stdin;
+  return _stdin ??= _StdIOUtils._getStdioInputStream(_stdinFD);
 }
 
 /// The standard output stream of data written by this program.
@@ -415,8 +413,7 @@
 /// result in an unhandled asynchronous error unless there is an error handler
 /// on `done`.
 Stdout get stdout {
-  _stdout ??= _StdIOUtils._getStdioOutputStream(_stdoutFD);
-  return _stdout;
+  return _stdout ??= _StdIOUtils._getStdioOutputStream(_stdoutFD);
 }
 
 /// The standard output stream of errors written by this program.
@@ -425,8 +422,7 @@
 /// result in an unhandled asynchronous error unless there is an error handler
 /// on `done`.
 Stdout get stderr {
-  _stderr ??= _StdIOUtils._getStdioOutputStream(_stderrFD);
-  return _stderr;
+  return _stderr ??= _StdIOUtils._getStdioOutputStream(_stderrFD);
 }
 
 /// For a stream, returns whether it is attached to a file, pipe, terminal, or
@@ -436,7 +432,12 @@
     object = object._stream;
   } else if (object == stdout || object == stderr) {
     int stdiofd = object == stdout ? _stdoutFD : _stderrFD;
-    switch (_StdIOUtils._getStdioHandleType(stdiofd)) {
+    final type = _StdIOUtils._getStdioHandleType(stdiofd);
+    if (type is OSError) {
+      throw FileSystemException(
+          "Failed to get type of stdio handle (fd $stdiofd)", "", type);
+    }
+    switch (type) {
       case _stdioHandleTypeTerminal:
         return StdioType.terminal;
       case _stdioHandleTypePipe:
@@ -449,7 +450,7 @@
     return StdioType.file;
   }
   if (object is Socket) {
-    int socketType = _StdIOUtils._socketType(object);
+    int? socketType = _StdIOUtils._socketType(object);
     if (socketType == null) return StdioType.other;
     switch (socketType) {
       case _stdioHandleTypeTerminal:
@@ -477,6 +478,6 @@
   external static Stdin _getStdioInputStream(int fd);
 
   /// Returns the socket type or `null` if [socket] is not a builtin socket.
-  external static int _socketType(Socket socket);
+  external static int? _socketType(Socket socket);
   external static _getStdioHandleType(int fd);
 }
diff --git a/sdk_nnbd/lib/io/string_transformer.dart b/sdk_nnbd/lib/io/string_transformer.dart
index e8548d1..f31c41e 100644
--- a/sdk_nnbd/lib/io/string_transformer.dart
+++ b/sdk_nnbd/lib/io/string_transformer.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /// The current system encoding.
diff --git a/sdk_nnbd/lib/io/sync_socket.dart b/sdk_nnbd/lib/io/sync_socket.dart
index 0b7d5b1..771edfd 100644
--- a/sdk_nnbd/lib/io/sync_socket.dart
+++ b/sdk_nnbd/lib/io/sync_socket.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.5
-
 part of dart.io;
 
 /**
@@ -54,7 +52,7 @@
    * otherwise up to [buffer.length]. If [end] == [start], no bytes are read.
    * Returns the number of bytes read.
    */
-  int readIntoSync(List<int> buffer, [int start = 0, int end]);
+  int readIntoSync(List<int> buffer, [int start = 0, int? end]);
 
   /**
    * Reads up to [bytes] bytes from the socket.
@@ -64,7 +62,7 @@
    * be read. Returns the list of bytes read, which could be less than the
    * value specified by [bytes].
    */
-  List<int> readSync(int bytes);
+  List<int>? readSync(int bytes);
 
   /**
    * Shutdown a socket in the provided direction.
@@ -87,7 +85,7 @@
    * be written to the socket starting from index [start]. If [end] == [start],
    * nothing happens.
    */
-  void writeFromSync(List<int> buffer, [int start = 0, int end]);
+  void writeFromSync(List<int> buffer, [int start = 0, int? end]);
 
   /**
    * The port used by this socket.
diff --git a/sdk_nnbd/lib/svg/dart2js/svg_dart2js.dart b/sdk_nnbd/lib/svg/dart2js/svg_dart2js.dart
index f81c43a..4393f4b 100644
--- a/sdk_nnbd/lib/svg/dart2js/svg_dart2js.dart
+++ b/sdk_nnbd/lib/svg/dart2js/svg_dart2js.dart
@@ -1,4 +1,3 @@
-// @dart = 2.5
 /**
  * Scalable Vector Graphics:
  * Two-dimensional vector graphics with support for events and animation.
@@ -46,7 +45,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory AElement() => _SvgElementFactoryProvider.createSvgElement_tag("a");
+  factory AElement() =>
+      _SvgElementFactoryProvider.createSvgElement_tag("a") as AElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -54,11 +54,11 @@
    */
   AElement.created() : super.created();
 
-  final AnimatedString target;
+  AnimatedString get target => JS("AnimatedString", "#.target", this);
 
   // From SVGURIReference
 
-  final AnimatedString href;
+  AnimatedString get href => JS("AnimatedString", "#.href", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -82,13 +82,25 @@
 
   static const int SVG_ANGLETYPE_UNSPECIFIED = 1;
 
-  final int unitType;
+  int get unitType => JS("int", "#.unitType", this);
 
-  num value;
+  num get value => JS("num", "#.value", this);
 
-  String valueAsString;
+  set value(num value) {
+    JS("void", "#.value = #", this, value);
+  }
 
-  num valueInSpecifiedUnits;
+  String get valueAsString => JS("String", "#.valueAsString", this);
+
+  set valueAsString(String value) {
+    JS("void", "#.valueAsString = #", this, value);
+  }
+
+  num get valueInSpecifiedUnits => JS("num", "#.valueInSpecifiedUnits", this);
+
+  set valueInSpecifiedUnits(num value) {
+    JS("void", "#.valueInSpecifiedUnits = #", this, value);
+  }
 
   void convertToSpecifiedUnits(int unitType) native;
 
@@ -110,7 +122,8 @@
   }
 
   factory AnimateElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("animate");
+      _SvgElementFactoryProvider.createSvgElement_tag("animate")
+          as AnimateElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -139,7 +152,8 @@
   }
 
   factory AnimateMotionElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("animateMotion");
+      _SvgElementFactoryProvider.createSvgElement_tag("animateMotion")
+          as AnimateMotionElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -168,7 +182,8 @@
   }
 
   factory AnimateTransformElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("animateTransform");
+      _SvgElementFactoryProvider.createSvgElement_tag("animateTransform")
+          as AnimateTransformElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -193,9 +208,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Angle animVal;
+  Angle get animVal => JS("Angle", "#.animVal", this);
 
-  final Angle baseVal;
+  Angle get baseVal => JS("Angle", "#.baseVal", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -209,9 +224,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool animVal;
+  bool get animVal => JS("bool", "#.animVal", this);
 
-  bool baseVal;
+  bool get baseVal => JS("bool", "#.baseVal", this);
+
+  set baseVal(bool value) {
+    JS("void", "#.baseVal = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -225,9 +244,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int animVal;
+  int get animVal => JS("int", "#.animVal", this);
 
-  int baseVal;
+  int get baseVal => JS("int", "#.baseVal", this);
+
+  set baseVal(int value) {
+    JS("void", "#.baseVal = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -241,9 +264,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int animVal;
+  int get animVal => JS("int", "#.animVal", this);
 
-  int baseVal;
+  int get baseVal => JS("int", "#.baseVal", this);
+
+  set baseVal(int value) {
+    JS("void", "#.baseVal = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -257,9 +284,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Length animVal;
+  Length get animVal => JS("Length", "#.animVal", this);
 
-  final Length baseVal;
+  Length get baseVal => JS("Length", "#.baseVal", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -273,9 +300,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final LengthList animVal;
+  LengthList get animVal => JS("LengthList", "#.animVal", this);
 
-  final LengthList baseVal;
+  LengthList get baseVal => JS("LengthList", "#.baseVal", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -289,9 +316,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num animVal;
+  num get animVal => JS("num", "#.animVal", this);
 
-  num baseVal;
+  num get baseVal => JS("num", "#.baseVal", this);
+
+  set baseVal(num value) {
+    JS("void", "#.baseVal = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -305,9 +336,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final NumberList animVal;
+  NumberList get animVal => JS("NumberList", "#.animVal", this);
 
-  final NumberList baseVal;
+  NumberList get baseVal => JS("NumberList", "#.baseVal", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -321,9 +352,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final PreserveAspectRatio animVal;
+  PreserveAspectRatio get animVal =>
+      JS("PreserveAspectRatio", "#.animVal", this);
 
-  final PreserveAspectRatio baseVal;
+  PreserveAspectRatio get baseVal =>
+      JS("PreserveAspectRatio", "#.baseVal", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -337,9 +370,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Rect animVal;
+  Rect get animVal => JS("Rect", "#.animVal", this);
 
-  final Rect baseVal;
+  Rect get baseVal => JS("Rect", "#.baseVal", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -353,9 +386,13 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String animVal;
+  String get animVal => JS("String", "#.animVal", this);
 
-  String baseVal;
+  String get baseVal => JS("String", "#.baseVal", this);
+
+  set baseVal(String value) {
+    JS("void", "#.baseVal = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -369,9 +406,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final TransformList animVal;
+  TransformList get animVal => JS("TransformList", "#.animVal", this);
 
-  final TransformList baseVal;
+  TransformList get baseVal => JS("TransformList", "#.baseVal", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -386,7 +423,8 @@
   }
 
   factory AnimationElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("animation");
+      _SvgElementFactoryProvider.createSvgElement_tag("animation")
+          as AnimationElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -394,7 +432,7 @@
    */
   AnimationElement.created() : super.created();
 
-  final SvgElement targetElement;
+  SvgElement get targetElement => JS("SvgElement", "#.targetElement", this);
 
   void beginElement() native;
 
@@ -412,9 +450,10 @@
 
   // From SVGTests
 
-  final StringList requiredExtensions;
+  StringList get requiredExtensions =>
+      JS("StringList", "#.requiredExtensions", this);
 
-  final StringList systemLanguage;
+  StringList get systemLanguage => JS("StringList", "#.systemLanguage", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -429,7 +468,8 @@
   }
 
   factory CircleElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("circle");
+      _SvgElementFactoryProvider.createSvgElement_tag("circle")
+          as CircleElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -437,11 +477,11 @@
    */
   CircleElement.created() : super.created();
 
-  final AnimatedLength cx;
+  AnimatedLength get cx => JS("AnimatedLength", "#.cx", this);
 
-  final AnimatedLength cy;
+  AnimatedLength get cy => JS("AnimatedLength", "#.cy", this);
 
-  final AnimatedLength r;
+  AnimatedLength get r => JS("AnimatedLength", "#.r", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -456,7 +496,8 @@
   }
 
   factory ClipPathElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("clipPath");
+      _SvgElementFactoryProvider.createSvgElement_tag("clipPath")
+          as ClipPathElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -464,7 +505,8 @@
    */
   ClipPathElement.created() : super.created();
 
-  final AnimatedEnumeration clipPathUnits;
+  AnimatedEnumeration get clipPathUnits =>
+      JS("AnimatedEnumeration", "#.clipPathUnits", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -479,7 +521,7 @@
   }
 
   factory DefsElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("defs");
+      _SvgElementFactoryProvider.createSvgElement_tag("defs") as DefsElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -500,7 +542,7 @@
   }
 
   factory DescElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("desc");
+      _SvgElementFactoryProvider.createSvgElement_tag("desc") as DescElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -538,7 +580,8 @@
   }
 
   factory EllipseElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("ellipse");
+      _SvgElementFactoryProvider.createSvgElement_tag("ellipse")
+          as EllipseElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -546,13 +589,13 @@
    */
   EllipseElement.created() : super.created();
 
-  final AnimatedLength cx;
+  AnimatedLength get cx => JS("AnimatedLength", "#.cx", this);
 
-  final AnimatedLength cy;
+  AnimatedLength get cy => JS("AnimatedLength", "#.cy", this);
 
-  final AnimatedLength rx;
+  AnimatedLength get rx => JS("AnimatedLength", "#.rx", this);
 
-  final AnimatedLength ry;
+  AnimatedLength get ry => JS("AnimatedLength", "#.ry", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -572,7 +615,8 @@
   }
 
   factory FEBlendElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feBlend");
+      _SvgElementFactoryProvider.createSvgElement_tag("feBlend")
+          as FEBlendElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -597,23 +641,23 @@
 
   static const int SVG_FEBLEND_MODE_UNKNOWN = 0;
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
-  final AnimatedString in2;
+  AnimatedString get in2 => JS("AnimatedString", "#.in2", this);
 
-  final AnimatedEnumeration mode;
+  AnimatedEnumeration get mode => JS("AnimatedEnumeration", "#.mode", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -633,7 +677,8 @@
   }
 
   factory FEColorMatrixElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feColorMatrix");
+      _SvgElementFactoryProvider.createSvgElement_tag("feColorMatrix")
+          as FEColorMatrixElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -656,23 +701,23 @@
 
   static const int SVG_FECOLORMATRIX_TYPE_UNKNOWN = 0;
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
-  final AnimatedEnumeration type;
+  AnimatedEnumeration get type => JS("AnimatedEnumeration", "#.type", this);
 
-  final AnimatedNumberList values;
+  AnimatedNumberList get values => JS("AnimatedNumberList", "#.values", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -692,7 +737,8 @@
   }
 
   factory FEComponentTransferElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feComponentTransfer");
+      _SvgElementFactoryProvider.createSvgElement_tag("feComponentTransfer")
+          as FEComponentTransferElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -705,19 +751,19 @@
       SvgElement.isTagSupported('feComponentTransfer') &&
       (new SvgElement.tag('feComponentTransfer') is FEComponentTransferElement);
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -752,31 +798,32 @@
 
   static const int SVG_FECOMPOSITE_OPERATOR_XOR = 5;
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
-  final AnimatedString in2;
+  AnimatedString get in2 => JS("AnimatedString", "#.in2", this);
 
-  final AnimatedNumber k1;
+  AnimatedNumber get k1 => JS("AnimatedNumber", "#.k1", this);
 
-  final AnimatedNumber k2;
+  AnimatedNumber get k2 => JS("AnimatedNumber", "#.k2", this);
 
-  final AnimatedNumber k3;
+  AnimatedNumber get k3 => JS("AnimatedNumber", "#.k3", this);
 
-  final AnimatedNumber k4;
+  AnimatedNumber get k4 => JS("AnimatedNumber", "#.k4", this);
 
-  final AnimatedEnumeration operator;
+  AnimatedEnumeration get operator =>
+      JS("AnimatedEnumeration", "#.operator", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -796,7 +843,8 @@
   }
 
   factory FEConvolveMatrixElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feConvolveMatrix");
+      _SvgElementFactoryProvider.createSvgElement_tag("feConvolveMatrix")
+          as FEConvolveMatrixElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -817,41 +865,46 @@
 
   static const int SVG_EDGEMODE_WRAP = 2;
 
-  final AnimatedNumber bias;
+  AnimatedNumber get bias => JS("AnimatedNumber", "#.bias", this);
 
-  final AnimatedNumber divisor;
+  AnimatedNumber get divisor => JS("AnimatedNumber", "#.divisor", this);
 
-  final AnimatedEnumeration edgeMode;
+  AnimatedEnumeration get edgeMode =>
+      JS("AnimatedEnumeration", "#.edgeMode", this);
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
-  final AnimatedNumberList kernelMatrix;
+  AnimatedNumberList get kernelMatrix =>
+      JS("AnimatedNumberList", "#.kernelMatrix", this);
 
-  final AnimatedNumber kernelUnitLengthX;
+  AnimatedNumber get kernelUnitLengthX =>
+      JS("AnimatedNumber", "#.kernelUnitLengthX", this);
 
-  final AnimatedNumber kernelUnitLengthY;
+  AnimatedNumber get kernelUnitLengthY =>
+      JS("AnimatedNumber", "#.kernelUnitLengthY", this);
 
-  final AnimatedInteger orderX;
+  AnimatedInteger get orderX => JS("AnimatedInteger", "#.orderX", this);
 
-  final AnimatedInteger orderY;
+  AnimatedInteger get orderY => JS("AnimatedInteger", "#.orderY", this);
 
-  final AnimatedBoolean preserveAlpha;
+  AnimatedBoolean get preserveAlpha =>
+      JS("AnimatedBoolean", "#.preserveAlpha", this);
 
-  final AnimatedInteger targetX;
+  AnimatedInteger get targetX => JS("AnimatedInteger", "#.targetX", this);
 
-  final AnimatedInteger targetY;
+  AnimatedInteger get targetY => JS("AnimatedInteger", "#.targetY", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -871,7 +924,8 @@
   }
 
   factory FEDiffuseLightingElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feDiffuseLighting");
+      _SvgElementFactoryProvider.createSvgElement_tag("feDiffuseLighting")
+          as FEDiffuseLightingElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -884,27 +938,31 @@
       SvgElement.isTagSupported('feDiffuseLighting') &&
       (new SvgElement.tag('feDiffuseLighting') is FEDiffuseLightingElement);
 
-  final AnimatedNumber diffuseConstant;
+  AnimatedNumber get diffuseConstant =>
+      JS("AnimatedNumber", "#.diffuseConstant", this);
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
-  final AnimatedNumber kernelUnitLengthX;
+  AnimatedNumber get kernelUnitLengthX =>
+      JS("AnimatedNumber", "#.kernelUnitLengthX", this);
 
-  final AnimatedNumber kernelUnitLengthY;
+  AnimatedNumber get kernelUnitLengthY =>
+      JS("AnimatedNumber", "#.kernelUnitLengthY", this);
 
-  final AnimatedNumber surfaceScale;
+  AnimatedNumber get surfaceScale =>
+      JS("AnimatedNumber", "#.surfaceScale", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -924,7 +982,8 @@
   }
 
   factory FEDisplacementMapElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feDisplacementMap");
+      _SvgElementFactoryProvider.createSvgElement_tag("feDisplacementMap")
+          as FEDisplacementMapElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -947,27 +1006,29 @@
 
   static const int SVG_CHANNEL_UNKNOWN = 0;
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
-  final AnimatedString in2;
+  AnimatedString get in2 => JS("AnimatedString", "#.in2", this);
 
-  final AnimatedNumber scale;
+  AnimatedNumber get scale => JS("AnimatedNumber", "#.scale", this);
 
-  final AnimatedEnumeration xChannelSelector;
+  AnimatedEnumeration get xChannelSelector =>
+      JS("AnimatedEnumeration", "#.xChannelSelector", this);
 
-  final AnimatedEnumeration yChannelSelector;
+  AnimatedEnumeration get yChannelSelector =>
+      JS("AnimatedEnumeration", "#.yChannelSelector", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -986,7 +1047,8 @@
   }
 
   factory FEDistantLightElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feDistantLight");
+      _SvgElementFactoryProvider.createSvgElement_tag("feDistantLight")
+          as FEDistantLightElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -999,9 +1061,9 @@
       SvgElement.isTagSupported('feDistantLight') &&
       (new SvgElement.tag('feDistantLight') is FEDistantLightElement);
 
-  final AnimatedNumber azimuth;
+  AnimatedNumber get azimuth => JS("AnimatedNumber", "#.azimuth", this);
 
-  final AnimatedNumber elevation;
+  AnimatedNumber get elevation => JS("AnimatedNumber", "#.elevation", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1021,7 +1083,8 @@
   }
 
   factory FEFloodElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feFlood");
+      _SvgElementFactoryProvider.createSvgElement_tag("feFlood")
+          as FEFloodElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1036,15 +1099,15 @@
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1063,7 +1126,8 @@
   }
 
   factory FEFuncAElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feFuncA");
+      _SvgElementFactoryProvider.createSvgElement_tag("feFuncA")
+          as FEFuncAElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1093,7 +1157,8 @@
   }
 
   factory FEFuncBElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feFuncB");
+      _SvgElementFactoryProvider.createSvgElement_tag("feFuncB")
+          as FEFuncBElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1123,7 +1188,8 @@
   }
 
   factory FEFuncGElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feFuncG");
+      _SvgElementFactoryProvider.createSvgElement_tag("feFuncG")
+          as FEFuncGElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1153,7 +1219,8 @@
   }
 
   factory FEFuncRElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feFuncR");
+      _SvgElementFactoryProvider.createSvgElement_tag("feFuncR")
+          as FEFuncRElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1184,7 +1251,8 @@
   }
 
   factory FEGaussianBlurElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feGaussianBlur");
+      _SvgElementFactoryProvider.createSvgElement_tag("feGaussianBlur")
+          as FEGaussianBlurElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1197,25 +1265,27 @@
       SvgElement.isTagSupported('feGaussianBlur') &&
       (new SvgElement.tag('feGaussianBlur') is FEGaussianBlurElement);
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
-  final AnimatedNumber stdDeviationX;
+  AnimatedNumber get stdDeviationX =>
+      JS("AnimatedNumber", "#.stdDeviationX", this);
 
-  final AnimatedNumber stdDeviationY;
+  AnimatedNumber get stdDeviationY =>
+      JS("AnimatedNumber", "#.stdDeviationY", this);
 
   void setStdDeviation(num stdDeviationX, num stdDeviationY) native;
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1235,7 +1305,8 @@
   }
 
   factory FEImageElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feImage");
+      _SvgElementFactoryProvider.createSvgElement_tag("feImage")
+          as FEImageElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1248,23 +1319,24 @@
       SvgElement.isTagSupported('feImage') &&
       (new SvgElement.tag('feImage') is FEImageElement);
 
-  final AnimatedPreserveAspectRatio preserveAspectRatio;
+  AnimatedPreserveAspectRatio get preserveAspectRatio =>
+      JS("AnimatedPreserveAspectRatio", "#.preserveAspectRatio", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 
   // From SVGURIReference
 
-  final AnimatedString href;
+  AnimatedString get href => JS("AnimatedString", "#.href", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1284,7 +1356,8 @@
   }
 
   factory FEMergeElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feMerge");
+      _SvgElementFactoryProvider.createSvgElement_tag("feMerge")
+          as FEMergeElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1299,15 +1372,15 @@
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1326,7 +1399,8 @@
   }
 
   factory FEMergeNodeElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feMergeNode");
+      _SvgElementFactoryProvider.createSvgElement_tag("feMergeNode")
+          as FEMergeNodeElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1339,7 +1413,7 @@
       SvgElement.isTagSupported('feMergeNode') &&
       (new SvgElement.tag('feMergeNode') is FEMergeNodeElement);
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1370,25 +1444,26 @@
 
   static const int SVG_MORPHOLOGY_OPERATOR_UNKNOWN = 0;
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
-  final AnimatedEnumeration operator;
+  AnimatedEnumeration get operator =>
+      JS("AnimatedEnumeration", "#.operator", this);
 
-  final AnimatedNumber radiusX;
+  AnimatedNumber get radiusX => JS("AnimatedNumber", "#.radiusX", this);
 
-  final AnimatedNumber radiusY;
+  AnimatedNumber get radiusY => JS("AnimatedNumber", "#.radiusY", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1408,7 +1483,8 @@
   }
 
   factory FEOffsetElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feOffset");
+      _SvgElementFactoryProvider.createSvgElement_tag("feOffset")
+          as FEOffsetElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1421,23 +1497,23 @@
       SvgElement.isTagSupported('feOffset') &&
       (new SvgElement.tag('feOffset') is FEOffsetElement);
 
-  final AnimatedNumber dx;
+  AnimatedNumber get dx => JS("AnimatedNumber", "#.dx", this);
 
-  final AnimatedNumber dy;
+  AnimatedNumber get dy => JS("AnimatedNumber", "#.dy", this);
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1456,7 +1532,8 @@
   }
 
   factory FEPointLightElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("fePointLight");
+      _SvgElementFactoryProvider.createSvgElement_tag("fePointLight")
+          as FEPointLightElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1469,11 +1546,11 @@
       SvgElement.isTagSupported('fePointLight') &&
       (new SvgElement.tag('fePointLight') is FEPointLightElement);
 
-  final AnimatedNumber x;
+  AnimatedNumber get x => JS("AnimatedNumber", "#.x", this);
 
-  final AnimatedNumber y;
+  AnimatedNumber get y => JS("AnimatedNumber", "#.y", this);
 
-  final AnimatedNumber z;
+  AnimatedNumber get z => JS("AnimatedNumber", "#.z", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1493,7 +1570,8 @@
   }
 
   factory FESpecularLightingElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feSpecularLighting");
+      _SvgElementFactoryProvider.createSvgElement_tag("feSpecularLighting")
+          as FESpecularLightingElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1506,29 +1584,34 @@
       SvgElement.isTagSupported('feSpecularLighting') &&
       (new SvgElement.tag('feSpecularLighting') is FESpecularLightingElement);
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
-  final AnimatedNumber kernelUnitLengthX;
+  AnimatedNumber get kernelUnitLengthX =>
+      JS("AnimatedNumber", "#.kernelUnitLengthX", this);
 
-  final AnimatedNumber kernelUnitLengthY;
+  AnimatedNumber get kernelUnitLengthY =>
+      JS("AnimatedNumber", "#.kernelUnitLengthY", this);
 
-  final AnimatedNumber specularConstant;
+  AnimatedNumber get specularConstant =>
+      JS("AnimatedNumber", "#.specularConstant", this);
 
-  final AnimatedNumber specularExponent;
+  AnimatedNumber get specularExponent =>
+      JS("AnimatedNumber", "#.specularExponent", this);
 
-  final AnimatedNumber surfaceScale;
+  AnimatedNumber get surfaceScale =>
+      JS("AnimatedNumber", "#.surfaceScale", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1547,7 +1630,8 @@
   }
 
   factory FESpotLightElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feSpotLight");
+      _SvgElementFactoryProvider.createSvgElement_tag("feSpotLight")
+          as FESpotLightElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1560,21 +1644,23 @@
       SvgElement.isTagSupported('feSpotLight') &&
       (new SvgElement.tag('feSpotLight') is FESpotLightElement);
 
-  final AnimatedNumber limitingConeAngle;
+  AnimatedNumber get limitingConeAngle =>
+      JS("AnimatedNumber", "#.limitingConeAngle", this);
 
-  final AnimatedNumber pointsAtX;
+  AnimatedNumber get pointsAtX => JS("AnimatedNumber", "#.pointsAtX", this);
 
-  final AnimatedNumber pointsAtY;
+  AnimatedNumber get pointsAtY => JS("AnimatedNumber", "#.pointsAtY", this);
 
-  final AnimatedNumber pointsAtZ;
+  AnimatedNumber get pointsAtZ => JS("AnimatedNumber", "#.pointsAtZ", this);
 
-  final AnimatedNumber specularExponent;
+  AnimatedNumber get specularExponent =>
+      JS("AnimatedNumber", "#.specularExponent", this);
 
-  final AnimatedNumber x;
+  AnimatedNumber get x => JS("AnimatedNumber", "#.x", this);
 
-  final AnimatedNumber y;
+  AnimatedNumber get y => JS("AnimatedNumber", "#.y", this);
 
-  final AnimatedNumber z;
+  AnimatedNumber get z => JS("AnimatedNumber", "#.z", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1594,7 +1680,8 @@
   }
 
   factory FETileElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feTile");
+      _SvgElementFactoryProvider.createSvgElement_tag("feTile")
+          as FETileElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1607,19 +1694,19 @@
       SvgElement.isTagSupported('feTile') &&
       (new SvgElement.tag('feTile') is FETileElement);
 
-  final AnimatedString in1;
+  AnimatedString get in1 => JS("AnimatedString", "#.in1", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1639,7 +1726,8 @@
   }
 
   factory FETurbulenceElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("feTurbulence");
+      _SvgElementFactoryProvider.createSvgElement_tag("feTurbulence")
+          as FETurbulenceElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1664,29 +1752,32 @@
 
   static const int SVG_TURBULENCE_TYPE_UNKNOWN = 0;
 
-  final AnimatedNumber baseFrequencyX;
+  AnimatedNumber get baseFrequencyX =>
+      JS("AnimatedNumber", "#.baseFrequencyX", this);
 
-  final AnimatedNumber baseFrequencyY;
+  AnimatedNumber get baseFrequencyY =>
+      JS("AnimatedNumber", "#.baseFrequencyY", this);
 
-  final AnimatedInteger numOctaves;
+  AnimatedInteger get numOctaves => JS("AnimatedInteger", "#.numOctaves", this);
 
-  final AnimatedNumber seed;
+  AnimatedNumber get seed => JS("AnimatedNumber", "#.seed", this);
 
-  final AnimatedEnumeration stitchTiles;
+  AnimatedEnumeration get stitchTiles =>
+      JS("AnimatedEnumeration", "#.stitchTiles", this);
 
-  final AnimatedEnumeration type;
+  AnimatedEnumeration get type => JS("AnimatedEnumeration", "#.type", this);
 
   // From SVGFilterPrimitiveStandardAttributes
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedString result;
+  AnimatedString get result => JS("AnimatedString", "#.result", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1705,7 +1796,8 @@
   }
 
   factory FilterElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("filter");
+      _SvgElementFactoryProvider.createSvgElement_tag("filter")
+          as FilterElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1718,21 +1810,23 @@
       SvgElement.isTagSupported('filter') &&
       (new SvgElement.tag('filter') is FilterElement);
 
-  final AnimatedEnumeration filterUnits;
+  AnimatedEnumeration get filterUnits =>
+      JS("AnimatedEnumeration", "#.filterUnits", this);
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedEnumeration primitiveUnits;
+  AnimatedEnumeration get primitiveUnits =>
+      JS("AnimatedEnumeration", "#.primitiveUnits", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 
   // From SVGURIReference
 
-  final AnimatedString href;
+  AnimatedString get href => JS("AnimatedString", "#.href", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1786,7 +1880,8 @@
   }
 
   factory ForeignObjectElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("foreignObject");
+      _SvgElementFactoryProvider.createSvgElement_tag("foreignObject")
+          as ForeignObjectElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1799,13 +1894,13 @@
       SvgElement.isTagSupported('foreignObject') &&
       (new SvgElement.tag('foreignObject') is ForeignObjectElement);
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1819,7 +1914,8 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory GElement() => _SvgElementFactoryProvider.createSvgElement_tag("g");
+  factory GElement() =>
+      _SvgElementFactoryProvider.createSvgElement_tag("g") as GElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1844,7 +1940,7 @@
    */
   GeometryElement.created() : super.created();
 
-  final AnimatedNumber pathLength;
+  AnimatedNumber get pathLength => JS("AnimatedNumber", "#.pathLength", this);
 
   Point getPointAtLength(num distance) native;
 
@@ -1871,11 +1967,14 @@
    */
   GraphicsElement.created() : super.created();
 
-  final SvgElement farthestViewportElement;
+  SvgElement get farthestViewportElement =>
+      JS("SvgElement", "#.farthestViewportElement", this);
 
-  final SvgElement nearestViewportElement;
+  SvgElement get nearestViewportElement =>
+      JS("SvgElement", "#.nearestViewportElement", this);
 
-  final AnimatedTransformList transform;
+  AnimatedTransformList get transform =>
+      JS("AnimatedTransformList", "#.transform", this);
 
   Rect getBBox() native;
 
@@ -1887,9 +1986,10 @@
 
   // From SVGTests
 
-  final StringList requiredExtensions;
+  StringList get requiredExtensions =>
+      JS("StringList", "#.requiredExtensions", this);
 
-  final StringList systemLanguage;
+  StringList get systemLanguage => JS("StringList", "#.systemLanguage", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1904,7 +2004,7 @@
   }
 
   factory ImageElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("image");
+      _SvgElementFactoryProvider.createSvgElement_tag("image") as ImageElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -1912,23 +2012,28 @@
    */
   ImageElement.created() : super.created();
 
-  String async;
+  String get async => JS("String", "#.async", this);
 
-  final AnimatedLength height;
+  set async(String value) {
+    JS("void", "#.async = #", this, value);
+  }
 
-  final AnimatedPreserveAspectRatio preserveAspectRatio;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedLength width;
+  AnimatedPreserveAspectRatio get preserveAspectRatio =>
+      JS("AnimatedPreserveAspectRatio", "#.preserveAspectRatio", this);
 
-  final AnimatedLength x;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength y;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
+
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 
   Future decode() => promiseToFuture(JS("", "#.decode()", this));
 
   // From SVGURIReference
 
-  final AnimatedString href;
+  AnimatedString get href => JS("AnimatedString", "#.href", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1964,13 +2069,25 @@
 
   static const int SVG_LENGTHTYPE_UNKNOWN = 0;
 
-  final int unitType;
+  int get unitType => JS("int", "#.unitType", this);
 
-  num value;
+  num get value => JS("num", "#.value", this);
 
-  String valueAsString;
+  set value(num value) {
+    JS("void", "#.value = #", this, value);
+  }
 
-  num valueInSpecifiedUnits;
+  String get valueAsString => JS("String", "#.valueAsString", this);
+
+  set valueAsString(String value) {
+    JS("void", "#.valueAsString = #", this, value);
+  }
+
+  num get valueInSpecifiedUnits => JS("num", "#.valueInSpecifiedUnits", this);
+
+  set valueInSpecifiedUnits(num value) {
+    JS("void", "#.valueInSpecifiedUnits = #", this, value);
+  }
 
   void convertToSpecifiedUnits(int unitType) native;
 
@@ -1992,7 +2109,7 @@
 
   int get length => JS("int", "#.length", this);
 
-  final int numberOfItems;
+  int get numberOfItems => JS("int", "#.numberOfItems", this);
 
   Length operator [](int index) {
     if (JS("bool", "# >>> 0 !== # || # >= #", index, index, index, length))
@@ -2066,7 +2183,7 @@
   }
 
   factory LineElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("line");
+      _SvgElementFactoryProvider.createSvgElement_tag("line") as LineElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2074,13 +2191,13 @@
    */
   LineElement.created() : super.created();
 
-  final AnimatedLength x1;
+  AnimatedLength get x1 => JS("AnimatedLength", "#.x1", this);
 
-  final AnimatedLength x2;
+  AnimatedLength get x2 => JS("AnimatedLength", "#.x2", this);
 
-  final AnimatedLength y1;
+  AnimatedLength get y1 => JS("AnimatedLength", "#.y1", this);
 
-  final AnimatedLength y2;
+  AnimatedLength get y2 => JS("AnimatedLength", "#.y2", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2095,7 +2212,8 @@
   }
 
   factory LinearGradientElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("linearGradient");
+      _SvgElementFactoryProvider.createSvgElement_tag("linearGradient")
+          as LinearGradientElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2103,13 +2221,13 @@
    */
   LinearGradientElement.created() : super.created();
 
-  final AnimatedLength x1;
+  AnimatedLength get x1 => JS("AnimatedLength", "#.x1", this);
 
-  final AnimatedLength x2;
+  AnimatedLength get x2 => JS("AnimatedLength", "#.x2", this);
 
-  final AnimatedLength y1;
+  AnimatedLength get y1 => JS("AnimatedLength", "#.y1", this);
 
-  final AnimatedLength y2;
+  AnimatedLength get y2 => JS("AnimatedLength", "#.y2", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2124,7 +2242,8 @@
   }
 
   factory MarkerElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("marker");
+      _SvgElementFactoryProvider.createSvgElement_tag("marker")
+          as MarkerElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2144,19 +2263,22 @@
 
   static const int SVG_MARKER_ORIENT_UNKNOWN = 0;
 
-  final AnimatedLength markerHeight;
+  AnimatedLength get markerHeight =>
+      JS("AnimatedLength", "#.markerHeight", this);
 
-  final AnimatedEnumeration markerUnits;
+  AnimatedEnumeration get markerUnits =>
+      JS("AnimatedEnumeration", "#.markerUnits", this);
 
-  final AnimatedLength markerWidth;
+  AnimatedLength get markerWidth => JS("AnimatedLength", "#.markerWidth", this);
 
-  final AnimatedAngle orientAngle;
+  AnimatedAngle get orientAngle => JS("AnimatedAngle", "#.orientAngle", this);
 
-  final AnimatedEnumeration orientType;
+  AnimatedEnumeration get orientType =>
+      JS("AnimatedEnumeration", "#.orientType", this);
 
-  final AnimatedLength refX;
+  AnimatedLength get refX => JS("AnimatedLength", "#.refX", this);
 
-  final AnimatedLength refY;
+  AnimatedLength get refY => JS("AnimatedLength", "#.refY", this);
 
   void setOrientToAngle(Angle angle) native;
 
@@ -2164,9 +2286,10 @@
 
   // From SVGFitToViewBox
 
-  final AnimatedPreserveAspectRatio preserveAspectRatio;
+  AnimatedPreserveAspectRatio get preserveAspectRatio =>
+      JS("AnimatedPreserveAspectRatio", "#.preserveAspectRatio", this);
 
-  final AnimatedRect viewBox;
+  AnimatedRect get viewBox => JS("AnimatedRect", "#.viewBox", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2181,7 +2304,7 @@
   }
 
   factory MaskElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("mask");
+      _SvgElementFactoryProvider.createSvgElement_tag("mask") as MaskElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2189,23 +2312,26 @@
    */
   MaskElement.created() : super.created();
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedEnumeration maskContentUnits;
+  AnimatedEnumeration get maskContentUnits =>
+      JS("AnimatedEnumeration", "#.maskContentUnits", this);
 
-  final AnimatedEnumeration maskUnits;
+  AnimatedEnumeration get maskUnits =>
+      JS("AnimatedEnumeration", "#.maskUnits", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 
   // From SVGTests
 
-  final StringList requiredExtensions;
+  StringList get requiredExtensions =>
+      JS("StringList", "#.requiredExtensions", this);
 
-  final StringList systemLanguage;
+  StringList get systemLanguage => JS("StringList", "#.systemLanguage", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2219,17 +2345,41 @@
     throw new UnsupportedError("Not supported");
   }
 
-  num a;
+  num get a => JS("num", "#.a", this);
 
-  num b;
+  set a(num value) {
+    JS("void", "#.a = #", this, value);
+  }
 
-  num c;
+  num get b => JS("num", "#.b", this);
 
-  num d;
+  set b(num value) {
+    JS("void", "#.b = #", this, value);
+  }
 
-  num e;
+  num get c => JS("num", "#.c", this);
 
-  num f;
+  set c(num value) {
+    JS("void", "#.c = #", this, value);
+  }
+
+  num get d => JS("num", "#.d", this);
+
+  set d(num value) {
+    JS("void", "#.d = #", this, value);
+  }
+
+  num get e => JS("num", "#.e", this);
+
+  set e(num value) {
+    JS("void", "#.e = #", this, value);
+  }
+
+  num get f => JS("num", "#.f", this);
+
+  set f(num value) {
+    JS("void", "#.f = #", this, value);
+  }
 
   Matrix flipX() native;
 
@@ -2283,7 +2433,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  num value;
+  num get value => JS("num", "#.value", this);
+
+  set value(num value) {
+    JS("void", "#.value = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2301,7 +2455,7 @@
 
   int get length => JS("int", "#.length", this);
 
-  final int numberOfItems;
+  int get numberOfItems => JS("int", "#.numberOfItems", this);
 
   Number operator [](int index) {
     if (JS("bool", "# >>> 0 !== # || # >= #", index, index, index, length))
@@ -2375,7 +2529,7 @@
   }
 
   factory PathElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("path");
+      _SvgElementFactoryProvider.createSvgElement_tag("path") as PathElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2397,7 +2551,8 @@
   }
 
   factory PatternElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("pattern");
+      _SvgElementFactoryProvider.createSvgElement_tag("pattern")
+          as PatternElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2405,35 +2560,40 @@
    */
   PatternElement.created() : super.created();
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedEnumeration patternContentUnits;
+  AnimatedEnumeration get patternContentUnits =>
+      JS("AnimatedEnumeration", "#.patternContentUnits", this);
 
-  final AnimatedTransformList patternTransform;
+  AnimatedTransformList get patternTransform =>
+      JS("AnimatedTransformList", "#.patternTransform", this);
 
-  final AnimatedEnumeration patternUnits;
+  AnimatedEnumeration get patternUnits =>
+      JS("AnimatedEnumeration", "#.patternUnits", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 
   // From SVGFitToViewBox
 
-  final AnimatedPreserveAspectRatio preserveAspectRatio;
+  AnimatedPreserveAspectRatio get preserveAspectRatio =>
+      JS("AnimatedPreserveAspectRatio", "#.preserveAspectRatio", this);
 
-  final AnimatedRect viewBox;
+  AnimatedRect get viewBox => JS("AnimatedRect", "#.viewBox", this);
 
   // From SVGTests
 
-  final StringList requiredExtensions;
+  StringList get requiredExtensions =>
+      JS("StringList", "#.requiredExtensions", this);
 
-  final StringList systemLanguage;
+  StringList get systemLanguage => JS("StringList", "#.systemLanguage", this);
 
   // From SVGURIReference
 
-  final AnimatedString href;
+  AnimatedString get href => JS("AnimatedString", "#.href", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2447,9 +2607,17 @@
     throw new UnsupportedError("Not supported");
   }
 
-  num x;
+  num get x => JS("num", "#.x", this);
 
-  num y;
+  set x(num value) {
+    JS("void", "#.x = #", this, value);
+  }
+
+  num get y => JS("num", "#.y", this);
+
+  set y(num value) {
+    JS("void", "#.y = #", this, value);
+  }
 
   Point matrixTransform(Matrix matrix) native;
 }
@@ -2465,9 +2633,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
-  final int numberOfItems;
+  int get numberOfItems => JS("int", "#.numberOfItems", this);
 
   void __setter__(int index, Point newItem) native;
 
@@ -2498,7 +2666,8 @@
   }
 
   factory PolygonElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("polygon");
+      _SvgElementFactoryProvider.createSvgElement_tag("polygon")
+          as PolygonElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2506,9 +2675,9 @@
    */
   PolygonElement.created() : super.created();
 
-  final PointList animatedPoints;
+  PointList get animatedPoints => JS("PointList", "#.animatedPoints", this);
 
-  final PointList points;
+  PointList get points => JS("PointList", "#.points", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2523,7 +2692,8 @@
   }
 
   factory PolylineElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("polyline");
+      _SvgElementFactoryProvider.createSvgElement_tag("polyline")
+          as PolylineElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2531,9 +2701,9 @@
    */
   PolylineElement.created() : super.created();
 
-  final PointList animatedPoints;
+  PointList get animatedPoints => JS("PointList", "#.animatedPoints", this);
 
-  final PointList points;
+  PointList get points => JS("PointList", "#.points", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2575,9 +2745,17 @@
 
   static const int SVG_PRESERVEASPECTRATIO_XMINYMIN = 2;
 
-  int align;
+  int get align => JS("int", "#.align", this);
 
-  int meetOrSlice;
+  set align(int value) {
+    JS("void", "#.align = #", this, value);
+  }
+
+  int get meetOrSlice => JS("int", "#.meetOrSlice", this);
+
+  set meetOrSlice(int value) {
+    JS("void", "#.meetOrSlice = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2592,7 +2770,8 @@
   }
 
   factory RadialGradientElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("radialGradient");
+      _SvgElementFactoryProvider.createSvgElement_tag("radialGradient")
+          as RadialGradientElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2600,17 +2779,17 @@
    */
   RadialGradientElement.created() : super.created();
 
-  final AnimatedLength cx;
+  AnimatedLength get cx => JS("AnimatedLength", "#.cx", this);
 
-  final AnimatedLength cy;
+  AnimatedLength get cy => JS("AnimatedLength", "#.cy", this);
 
-  final AnimatedLength fr;
+  AnimatedLength get fr => JS("AnimatedLength", "#.fr", this);
 
-  final AnimatedLength fx;
+  AnimatedLength get fx => JS("AnimatedLength", "#.fx", this);
 
-  final AnimatedLength fy;
+  AnimatedLength get fy => JS("AnimatedLength", "#.fy", this);
 
-  final AnimatedLength r;
+  AnimatedLength get r => JS("AnimatedLength", "#.r", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2624,13 +2803,29 @@
     throw new UnsupportedError("Not supported");
   }
 
-  num height;
+  num get height => JS("num", "#.height", this);
 
-  num width;
+  set height(num value) {
+    JS("void", "#.height = #", this, value);
+  }
 
-  num x;
+  num get width => JS("num", "#.width", this);
 
-  num y;
+  set width(num value) {
+    JS("void", "#.width = #", this, value);
+  }
+
+  num get x => JS("num", "#.x", this);
+
+  set x(num value) {
+    JS("void", "#.x = #", this, value);
+  }
+
+  num get y => JS("num", "#.y", this);
+
+  set y(num value) {
+    JS("void", "#.y = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2645,7 +2840,7 @@
   }
 
   factory RectElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("rect");
+      _SvgElementFactoryProvider.createSvgElement_tag("rect") as RectElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2653,17 +2848,17 @@
    */
   RectElement.created() : super.created();
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedLength rx;
+  AnimatedLength get rx => JS("AnimatedLength", "#.rx", this);
 
-  final AnimatedLength ry;
+  AnimatedLength get ry => JS("AnimatedLength", "#.ry", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2678,7 +2873,8 @@
   }
 
   factory ScriptElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("script");
+      _SvgElementFactoryProvider.createSvgElement_tag("script")
+          as ScriptElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2686,11 +2882,15 @@
    */
   ScriptElement.created() : super.created();
 
-  String type;
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 
   // From SVGURIReference
 
-  final AnimatedString href;
+  AnimatedString get href => JS("AnimatedString", "#.href", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2708,7 +2908,7 @@
   }
 
   factory SetElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("set");
+      _SvgElementFactoryProvider.createSvgElement_tag("set") as SetElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2734,7 +2934,7 @@
   }
 
   factory StopElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("stop");
+      _SvgElementFactoryProvider.createSvgElement_tag("stop") as StopElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2743,7 +2943,7 @@
   StopElement.created() : super.created();
 
   @JSName('offset')
-  final AnimatedNumber gradientOffset;
+  AnimatedNumber get gradientOffset => JS("AnimatedNumber", "#.offset", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2761,7 +2961,7 @@
 
   int get length => JS("int", "#.length", this);
 
-  final int numberOfItems;
+  int get numberOfItems => JS("int", "#.numberOfItems", this);
 
   String operator [](int index) {
     if (JS("bool", "# >>> 0 !== # || # >= #", index, index, index, length))
@@ -2834,7 +3034,7 @@
   }
 
   factory StyleElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("style");
+      _SvgElementFactoryProvider.createSvgElement_tag("style") as StyleElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -2842,16 +3042,28 @@
    */
   StyleElement.created() : super.created();
 
-  bool disabled;
+  bool get disabled => JS("bool", "#.disabled", this);
 
-  String media;
+  set disabled(bool value) {
+    JS("void", "#.disabled = #", this, value);
+  }
 
-  final StyleSheet sheet;
+  String get media => JS("String", "#.media", this);
+
+  set media(String value) {
+    JS("void", "#.media = #", this, value);
+  }
+
+  final StyleSheet? sheet;
 
   // Use implementation from Element.
   // final String title;
 
-  String type;
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 }
 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3180,10 +3392,11 @@
   SvgElement.created() : super.created();
 
   // Shadowing definition.
+
   AnimatedString get _svgClassName => JS("AnimatedString", "#.className", this);
 
   @JSName('ownerSVGElement')
-  final SvgSvgElement ownerSvgElement;
+  final SvgSvgElement? ownerSvgElement;
 
   // Use implementation from Element.
   // final CssStyleDeclaration style;
@@ -3191,7 +3404,7 @@
   // Use implementation from Element.
   // final int tabIndex;
 
-  final SvgElement viewportElement;
+  final SvgElement? viewportElement;
 
   void blur() native;
 
@@ -3199,7 +3412,11 @@
 
   // From NoncedElement
 
-  String nonce;
+  String get nonce => JS("String", "#.nonce", this);
+
+  set nonce(String value) {
+    JS("void", "#.nonce = #", this, value);
+  }
 
   ElementStream<Event> get onAbort => abortEvent.forElement(this);
 
@@ -3351,17 +3568,21 @@
    */
   SvgSvgElement.created() : super.created();
 
-  num currentScale;
+  num get currentScale => JS("num", "#.currentScale", this);
 
-  final Point currentTranslate;
+  set currentScale(num value) {
+    JS("void", "#.currentScale = #", this, value);
+  }
 
-  final AnimatedLength height;
+  Point get currentTranslate => JS("Point", "#.currentTranslate", this);
 
-  final AnimatedLength width;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedLength x;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength y;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
+
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 
   bool animationsPaused() native;
 
@@ -3403,11 +3624,12 @@
 
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  List<Node> getEnclosureList(Rect rect, SvgElement referenceElement) native;
+  List<Node> getEnclosureList(Rect rect, SvgElement? referenceElement) native;
 
   @Returns('NodeList|Null')
   @Creates('NodeList')
-  List<Node> getIntersectionList(Rect rect, SvgElement referenceElement) native;
+  List<Node> getIntersectionList(Rect rect, SvgElement? referenceElement)
+      native;
 
   void pauseAnimations() native;
 
@@ -3423,13 +3645,18 @@
 
   // From SVGFitToViewBox
 
-  final AnimatedPreserveAspectRatio preserveAspectRatio;
+  AnimatedPreserveAspectRatio get preserveAspectRatio =>
+      JS("AnimatedPreserveAspectRatio", "#.preserveAspectRatio", this);
 
-  final AnimatedRect viewBox;
+  AnimatedRect get viewBox => JS("AnimatedRect", "#.viewBox", this);
 
   // From SVGZoomAndPan
 
-  int zoomAndPan;
+  int get zoomAndPan => JS("int", "#.zoomAndPan", this);
+
+  set zoomAndPan(int value) {
+    JS("void", "#.zoomAndPan = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3444,7 +3671,8 @@
   }
 
   factory SwitchElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("switch");
+      _SvgElementFactoryProvider.createSvgElement_tag("switch")
+          as SwitchElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -3465,7 +3693,8 @@
   }
 
   factory SymbolElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("symbol");
+      _SvgElementFactoryProvider.createSvgElement_tag("symbol")
+          as SymbolElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -3475,9 +3704,10 @@
 
   // From SVGFitToViewBox
 
-  final AnimatedPreserveAspectRatio preserveAspectRatio;
+  AnimatedPreserveAspectRatio get preserveAspectRatio =>
+      JS("AnimatedPreserveAspectRatio", "#.preserveAspectRatio", this);
 
-  final AnimatedRect viewBox;
+  AnimatedRect get viewBox => JS("AnimatedRect", "#.viewBox", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3492,7 +3722,7 @@
   }
 
   factory TSpanElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("tspan");
+      _SvgElementFactoryProvider.createSvgElement_tag("tspan") as TSpanElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -3539,9 +3769,10 @@
 
   static const int LENGTHADJUST_UNKNOWN = 0;
 
-  final AnimatedEnumeration lengthAdjust;
+  AnimatedEnumeration get lengthAdjust =>
+      JS("AnimatedEnumeration", "#.lengthAdjust", this);
 
-  final AnimatedLength textLength;
+  AnimatedLength get textLength => JS("AnimatedLength", "#.textLength", this);
 
   int getCharNumAtPosition(Point point) native;
 
@@ -3574,7 +3805,7 @@
   }
 
   factory TextElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("text");
+      _SvgElementFactoryProvider.createSvgElement_tag("text") as TextElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -3612,15 +3843,16 @@
 
   static const int TEXTPATH_SPACINGTYPE_UNKNOWN = 0;
 
-  final AnimatedEnumeration method;
+  AnimatedEnumeration get method => JS("AnimatedEnumeration", "#.method", this);
 
-  final AnimatedEnumeration spacing;
+  AnimatedEnumeration get spacing =>
+      JS("AnimatedEnumeration", "#.spacing", this);
 
-  final AnimatedLength startOffset;
+  AnimatedLength get startOffset => JS("AnimatedLength", "#.startOffset", this);
 
   // From SVGURIReference
 
-  final AnimatedString href;
+  AnimatedString get href => JS("AnimatedString", "#.href", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3640,15 +3872,15 @@
    */
   TextPositioningElement.created() : super.created();
 
-  final AnimatedLengthList dx;
+  AnimatedLengthList get dx => JS("AnimatedLengthList", "#.dx", this);
 
-  final AnimatedLengthList dy;
+  AnimatedLengthList get dy => JS("AnimatedLengthList", "#.dy", this);
 
-  final AnimatedNumberList rotate;
+  AnimatedNumberList get rotate => JS("AnimatedNumberList", "#.rotate", this);
 
-  final AnimatedLengthList x;
+  AnimatedLengthList get x => JS("AnimatedLengthList", "#.x", this);
 
-  final AnimatedLengthList y;
+  AnimatedLengthList get y => JS("AnimatedLengthList", "#.y", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3663,7 +3895,7 @@
   }
 
   factory TitleElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("title");
+      _SvgElementFactoryProvider.createSvgElement_tag("title") as TitleElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -3697,11 +3929,11 @@
 
   static const int SVG_TRANSFORM_UNKNOWN = 0;
 
-  final num angle;
+  num get angle => JS("num", "#.angle", this);
 
-  final Matrix matrix;
+  Matrix get matrix => JS("Matrix", "#.matrix", this);
 
-  final int type;
+  int get type => JS("int", "#.type", this);
 
   void setMatrix(Matrix matrix) native;
 
@@ -3731,7 +3963,7 @@
 
   int get length => JS("int", "#.length", this);
 
-  final int numberOfItems;
+  int get numberOfItems => JS("int", "#.numberOfItems", this);
 
   Transform operator [](int index) {
     if (JS("bool", "# >>> 0 !== # || # >= #", index, index, index, length))
@@ -3841,7 +4073,7 @@
   }
 
   factory UseElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("use");
+      _SvgElementFactoryProvider.createSvgElement_tag("use") as UseElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -3849,17 +4081,17 @@
    */
   UseElement.created() : super.created();
 
-  final AnimatedLength height;
+  AnimatedLength get height => JS("AnimatedLength", "#.height", this);
 
-  final AnimatedLength width;
+  AnimatedLength get width => JS("AnimatedLength", "#.width", this);
 
-  final AnimatedLength x;
+  AnimatedLength get x => JS("AnimatedLength", "#.x", this);
 
-  final AnimatedLength y;
+  AnimatedLength get y => JS("AnimatedLength", "#.y", this);
 
   // From SVGURIReference
 
-  final AnimatedString href;
+  AnimatedString get href => JS("AnimatedString", "#.href", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3874,7 +4106,7 @@
   }
 
   factory ViewElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("view");
+      _SvgElementFactoryProvider.createSvgElement_tag("view") as ViewElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
@@ -3884,13 +4116,18 @@
 
   // From SVGFitToViewBox
 
-  final AnimatedPreserveAspectRatio preserveAspectRatio;
+  AnimatedPreserveAspectRatio get preserveAspectRatio =>
+      JS("AnimatedPreserveAspectRatio", "#.preserveAspectRatio", this);
 
-  final AnimatedRect viewBox;
+  AnimatedRect get viewBox => JS("AnimatedRect", "#.viewBox", this);
 
   // From SVGZoomAndPan
 
-  int zoomAndPan;
+  int get zoomAndPan => JS("int", "#.zoomAndPan", this);
+
+  set zoomAndPan(int value) {
+    JS("void", "#.zoomAndPan = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3937,15 +4174,18 @@
 
   static const int SVG_SPREADMETHOD_UNKNOWN = 0;
 
-  final AnimatedTransformList gradientTransform;
+  AnimatedTransformList get gradientTransform =>
+      JS("AnimatedTransformList", "#.gradientTransform", this);
 
-  final AnimatedEnumeration gradientUnits;
+  AnimatedEnumeration get gradientUnits =>
+      JS("AnimatedEnumeration", "#.gradientUnits", this);
 
-  final AnimatedEnumeration spreadMethod;
+  AnimatedEnumeration get spreadMethod =>
+      JS("AnimatedEnumeration", "#.spreadMethod", this);
 
   // From SVGURIReference
 
-  final AnimatedString href;
+  AnimatedString get href => JS("AnimatedString", "#.href", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -3999,7 +4239,8 @@
   }
 
   factory _SVGMPathElement() =>
-      _SvgElementFactoryProvider.createSvgElement_tag("mpath");
+      _SvgElementFactoryProvider.createSvgElement_tag("mpath")
+          as _SVGMPathElement;
   /**
    * Constructor instantiated by the DOM when a custom element has been created.
    *
diff --git a/sdk_nnbd/lib/web_audio/dart2js/web_audio_dart2js.dart b/sdk_nnbd/lib/web_audio/dart2js/web_audio_dart2js.dart
index 57f93f6..370361b 100644
--- a/sdk_nnbd/lib/web_audio/dart2js/web_audio_dart2js.dart
+++ b/sdk_nnbd/lib/web_audio/dart2js/web_audio_dart2js.dart
@@ -1,4 +1,3 @@
-// @dart = 2.5
 /**
  * High-fidelity audio programming in the browser.
  *
@@ -39,7 +38,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory AnalyserNode(BaseAudioContext context, [Map options]) {
+  factory AnalyserNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return AnalyserNode._create_1(context, options_1);
@@ -51,15 +50,31 @@
   static AnalyserNode _create_2(context) =>
       JS('AnalyserNode', 'new AnalyserNode(#)', context);
 
-  int fftSize;
+  int get fftSize => JS("int", "#.fftSize", this);
 
-  final int frequencyBinCount;
+  set fftSize(int value) {
+    JS("void", "#.fftSize = #", this, value);
+  }
 
-  num maxDecibels;
+  int get frequencyBinCount => JS("int", "#.frequencyBinCount", this);
 
-  num minDecibels;
+  num get maxDecibels => JS("num", "#.maxDecibels", this);
 
-  num smoothingTimeConstant;
+  set maxDecibels(num value) {
+    JS("void", "#.maxDecibels = #", this, value);
+  }
+
+  num get minDecibels => JS("num", "#.minDecibels", this);
+
+  set minDecibels(num value) {
+    JS("void", "#.minDecibels = #", this, value);
+  }
+
+  num get smoothingTimeConstant => JS("num", "#.smoothingTimeConstant", this);
+
+  set smoothingTimeConstant(num value) {
+    JS("void", "#.smoothingTimeConstant = #", this, value);
+  }
 
   void getByteFrequencyData(Uint8List array) native;
 
@@ -87,19 +102,19 @@
   static AudioBuffer _create_1(options) =>
       JS('AudioBuffer', 'new AudioBuffer(#)', options);
 
-  final num duration;
+  num get duration => JS("num", "#.duration", this);
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
-  final int numberOfChannels;
+  int get numberOfChannels => JS("int", "#.numberOfChannels", this);
 
-  final num sampleRate;
+  num get sampleRate => JS("num", "#.sampleRate", this);
 
   void copyFromChannel(Float32List destination, int channelNumber,
-      [int startInChannel]) native;
+      [int? startInChannel]) native;
 
   void copyToChannel(Float32List source, int channelNumber,
-      [int startInChannel]) native;
+      [int? startInChannel]) native;
 
   Float32List getChannelData(int channelIndex) native;
 }
@@ -116,7 +131,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory AudioBufferSourceNode(BaseAudioContext context, [Map options]) {
+  factory AudioBufferSourceNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return AudioBufferSourceNode._create_1(context, options_1);
@@ -131,19 +146,31 @@
   static AudioBufferSourceNode _create_2(context) =>
       JS('AudioBufferSourceNode', 'new AudioBufferSourceNode(#)', context);
 
-  AudioBuffer buffer;
+  AudioBuffer? buffer;
 
-  final AudioParam detune;
+  AudioParam get detune => JS("AudioParam", "#.detune", this);
 
-  bool loop;
+  bool get loop => JS("bool", "#.loop", this);
 
-  num loopEnd;
+  set loop(bool value) {
+    JS("void", "#.loop = #", this, value);
+  }
 
-  num loopStart;
+  num get loopEnd => JS("num", "#.loopEnd", this);
 
-  final AudioParam playbackRate;
+  set loopEnd(num value) {
+    JS("void", "#.loopEnd = #", this, value);
+  }
 
-  void start([num when, num grainOffset, num grainDuration]) native;
+  num get loopStart => JS("num", "#.loopStart", this);
+
+  set loopStart(num value) {
+    JS("void", "#.loopStart = #", this, value);
+  }
+
+  AudioParam get playbackRate => JS("AudioParam", "#.playbackRate", this);
+
+  void start([num? when, num? grainOffset, num? grainDuration]) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -162,7 +189,7 @@
   static bool get supported =>
       JS('bool', '!!(window.AudioContext || window.webkitAudioContext)');
 
-  final num baseLatency;
+  num get baseLatency => JS("num", "#.baseLatency", this);
 
   Future close() => promiseToFuture(JS("", "#.close()", this));
 
@@ -187,7 +214,9 @@
   }
 
   ScriptProcessorNode createScriptProcessor(
-      [int bufferSize, int numberOfInputChannels, int numberOfOutputChannels]) {
+      [int? bufferSize,
+      int? numberOfInputChannels,
+      int? numberOfOutputChannels]) {
     var function = JS(
         '=Object',
         '#.createScriptProcessor || '
@@ -214,8 +243,8 @@
       DecodeErrorCallback errorCallback]) native;
 
   Future<AudioBuffer> decodeAudioData(ByteBuffer audioData,
-      [DecodeSuccessCallback successCallback,
-      DecodeErrorCallback errorCallback]) {
+      [DecodeSuccessCallback? successCallback,
+      DecodeErrorCallback? errorCallback]) {
     if (successCallback != null && errorCallback != null) {
       return _decodeAudioData(audioData, successCallback, errorCallback);
     }
@@ -244,7 +273,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int maxChannelCount;
+  int get maxChannelCount => JS("int", "#.maxChannelCount", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -257,23 +286,23 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final AudioParam forwardX;
+  AudioParam get forwardX => JS("AudioParam", "#.forwardX", this);
 
-  final AudioParam forwardY;
+  AudioParam get forwardY => JS("AudioParam", "#.forwardY", this);
 
-  final AudioParam forwardZ;
+  AudioParam get forwardZ => JS("AudioParam", "#.forwardZ", this);
 
-  final AudioParam positionX;
+  AudioParam get positionX => JS("AudioParam", "#.positionX", this);
 
-  final AudioParam positionY;
+  AudioParam get positionY => JS("AudioParam", "#.positionY", this);
 
-  final AudioParam positionZ;
+  AudioParam get positionZ => JS("AudioParam", "#.positionZ", this);
 
-  final AudioParam upX;
+  AudioParam get upX => JS("AudioParam", "#.upX", this);
 
-  final AudioParam upY;
+  AudioParam get upY => JS("AudioParam", "#.upY", this);
 
-  final AudioParam upZ;
+  AudioParam get upZ => JS("AudioParam", "#.upZ", this);
 
   void setOrientation(num x, num y, num z, num xUp, num yUp, num zUp) native;
 
@@ -290,22 +319,35 @@
     throw new UnsupportedError("Not supported");
   }
 
-  int channelCount;
+  int get channelCount => JS("int", "#.channelCount", this);
 
-  String channelCountMode;
+  set channelCount(int value) {
+    JS("void", "#.channelCount = #", this, value);
+  }
 
-  String channelInterpretation;
+  String get channelCountMode => JS("String", "#.channelCountMode", this);
 
-  final BaseAudioContext context;
+  set channelCountMode(String value) {
+    JS("void", "#.channelCountMode = #", this, value);
+  }
 
-  final int numberOfInputs;
+  String get channelInterpretation =>
+      JS("String", "#.channelInterpretation", this);
 
-  final int numberOfOutputs;
+  set channelInterpretation(String value) {
+    JS("void", "#.channelInterpretation = #", this, value);
+  }
+
+  BaseAudioContext get context => JS("BaseAudioContext", "#.context", this);
+
+  int get numberOfInputs => JS("int", "#.numberOfInputs", this);
+
+  int get numberOfOutputs => JS("int", "#.numberOfOutputs", this);
 
   @JSName('connect')
-  AudioNode _connect(destination, [int output, int input]) native;
+  AudioNode _connect(destination, [int? output, int? input]) native;
 
-  void disconnect([destination_OR_output, int output, int input]) native;
+  void disconnect([destination_OR_output, int? output, int? input]) native;
 
   void connectNode(AudioNode destination, [int output = 0, int input = 0]) {
     _connect(destination, output, input);
@@ -326,13 +368,17 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num defaultValue;
+  num get defaultValue => JS("num", "#.defaultValue", this);
 
-  final num maxValue;
+  num get maxValue => JS("num", "#.maxValue", this);
 
-  final num minValue;
+  num get minValue => JS("num", "#.minValue", this);
 
-  num value;
+  num get value => JS("num", "#.value", this);
+
+  set value(num value) {
+    JS("void", "#.value = #", this, value);
+  }
 
   AudioParam cancelAndHoldAtTime(num startTime) native;
 
@@ -438,11 +484,11 @@
       type,
       eventInitDict);
 
-  final AudioBuffer inputBuffer;
+  AudioBuffer get inputBuffer => JS("AudioBuffer", "#.inputBuffer", this);
 
-  final AudioBuffer outputBuffer;
+  AudioBuffer get outputBuffer => JS("AudioBuffer", "#.outputBuffer", this);
 
-  final num playbackTime;
+  num get playbackTime => JS("num", "#.playbackTime", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -459,9 +505,9 @@
       const EventStreamProvider<Event>('ended');
 
   @JSName('start')
-  void start2([num when]) native;
+  void start2([num? when]) native;
 
-  void stop([num when]) native;
+  void stop([num? when]) native;
 
   Stream<Event> get onEnded => endedEvent.forTarget(this);
 }
@@ -476,17 +522,21 @@
     throw new UnsupportedError("Not supported");
   }
 
-  bool enabled;
+  bool get enabled => JS("bool", "#.enabled", this);
 
-  final String id;
+  set enabled(bool value) {
+    JS("void", "#.enabled = #", this, value);
+  }
 
-  final String kind;
+  String get id => JS("String", "#.id", this);
 
-  final String label;
+  String get kind => JS("String", "#.kind", this);
 
-  final String language;
+  String get label => JS("String", "#.label", this);
 
-  final SourceBuffer sourceBuffer;
+  String get language => JS("String", "#.language", this);
+
+  final SourceBuffer? sourceBuffer;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -502,7 +552,7 @@
   static const EventStreamProvider<Event> changeEvent =
       const EventStreamProvider<Event>('change');
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
   AudioTrack __getter__(int index) native;
 
@@ -521,9 +571,9 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num currentTime;
+  num get currentTime => JS("num", "#.currentTime", this);
 
-  final num sampleRate;
+  num get sampleRate => JS("num", "#.sampleRate", this);
 
   void registerProcessor(String name, Object processorConstructor) native;
 }
@@ -539,7 +589,7 @@
   }
 
   factory AudioWorkletNode(BaseAudioContext context, String name,
-      [Map options]) {
+      [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return AudioWorkletNode._create_1(context, name, options_1);
@@ -555,7 +605,7 @@
   static AudioWorkletNode _create_2(context, name) =>
       JS('AudioWorkletNode', 'new AudioWorkletNode(#,#)', context, name);
 
-  final AudioParamMap parameters;
+  AudioParamMap get parameters => JS("AudioParamMap", "#.parameters", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -579,15 +629,16 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final num currentTime;
+  num get currentTime => JS("num", "#.currentTime", this);
 
-  final AudioDestinationNode destination;
+  AudioDestinationNode get destination =>
+      JS("AudioDestinationNode", "#.destination", this);
 
-  final AudioListener listener;
+  AudioListener get listener => JS("AudioListener", "#.listener", this);
 
-  final num sampleRate;
+  num get sampleRate => JS("num", "#.sampleRate", this);
 
-  final String state;
+  String get state => JS("String", "#.state", this);
 
   AnalyserNode createAnalyser() native;
 
@@ -598,15 +649,15 @@
 
   AudioBufferSourceNode createBufferSource() native;
 
-  ChannelMergerNode createChannelMerger([int numberOfInputs]) native;
+  ChannelMergerNode createChannelMerger([int? numberOfInputs]) native;
 
-  ChannelSplitterNode createChannelSplitter([int numberOfOutputs]) native;
+  ChannelSplitterNode createChannelSplitter([int? numberOfOutputs]) native;
 
   ConstantSourceNode createConstantSource() native;
 
   ConvolverNode createConvolver() native;
 
-  DelayNode createDelay([num maxDelayTime]) native;
+  DelayNode createDelay([num? maxDelayTime]) native;
 
   DynamicsCompressorNode createDynamicsCompressor() native;
 
@@ -629,7 +680,7 @@
   PannerNode createPanner() native;
 
   PeriodicWave createPeriodicWave(List<num> real, List<num> imag,
-      [Map options]) {
+      [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return _createPeriodicWave_1(real, imag, options_1);
@@ -644,17 +695,17 @@
   PeriodicWave _createPeriodicWave_2(List<num> real, List<num> imag) native;
 
   ScriptProcessorNode createScriptProcessor(
-      [int bufferSize,
-      int numberOfInputChannels,
-      int numberOfOutputChannels]) native;
+      [int? bufferSize,
+      int? numberOfInputChannels,
+      int? numberOfOutputChannels]) native;
 
   StereoPannerNode createStereoPanner() native;
 
   WaveShaperNode createWaveShaper() native;
 
   Future<AudioBuffer> decodeAudioData(ByteBuffer audioData,
-          [DecodeSuccessCallback successCallback,
-          DecodeErrorCallback errorCallback]) =>
+          [DecodeSuccessCallback? successCallback,
+          DecodeErrorCallback? errorCallback]) =>
       promiseToFuture<AudioBuffer>(JS("", "#.decodeAudioData(#, #, #)", this,
           audioData, successCallback, errorCallback));
 
@@ -671,7 +722,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory BiquadFilterNode(BaseAudioContext context, [Map options]) {
+  factory BiquadFilterNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return BiquadFilterNode._create_1(context, options_1);
@@ -683,15 +734,19 @@
   static BiquadFilterNode _create_2(context) =>
       JS('BiquadFilterNode', 'new BiquadFilterNode(#)', context);
 
-  final AudioParam Q;
+  AudioParam get Q => JS("AudioParam", "#.Q", this);
 
-  final AudioParam detune;
+  AudioParam get detune => JS("AudioParam", "#.detune", this);
 
-  final AudioParam frequency;
+  AudioParam get frequency => JS("AudioParam", "#.frequency", this);
 
-  final AudioParam gain;
+  AudioParam get gain => JS("AudioParam", "#.gain", this);
 
-  String type;
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 
   void getFrequencyResponse(Float32List frequencyHz, Float32List magResponse,
       Float32List phaseResponse) native;
@@ -707,7 +762,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ChannelMergerNode(BaseAudioContext context, [Map options]) {
+  factory ChannelMergerNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return ChannelMergerNode._create_1(context, options_1);
@@ -730,7 +785,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ChannelSplitterNode(BaseAudioContext context, [Map options]) {
+  factory ChannelSplitterNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return ChannelSplitterNode._create_1(context, options_1);
@@ -753,7 +808,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ConstantSourceNode(BaseAudioContext context, [Map options]) {
+  factory ConstantSourceNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return ConstantSourceNode._create_1(context, options_1);
@@ -765,7 +820,7 @@
   static ConstantSourceNode _create_2(context) =>
       JS('ConstantSourceNode', 'new ConstantSourceNode(#)', context);
 
-  final AudioParam offset;
+  AudioParam get offset => JS("AudioParam", "#.offset", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -778,7 +833,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ConvolverNode(BaseAudioContext context, [Map options]) {
+  factory ConvolverNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return ConvolverNode._create_1(context, options_1);
@@ -790,9 +845,13 @@
   static ConvolverNode _create_2(context) =>
       JS('ConvolverNode', 'new ConvolverNode(#)', context);
 
-  AudioBuffer buffer;
+  AudioBuffer? buffer;
 
-  bool normalize;
+  bool get normalize => JS("bool", "#.normalize", this);
+
+  set normalize(bool value) {
+    JS("void", "#.normalize = #", this, value);
+  }
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -805,7 +864,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DelayNode(BaseAudioContext context, [Map options]) {
+  factory DelayNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return DelayNode._create_1(context, options_1);
@@ -817,7 +876,7 @@
   static DelayNode _create_2(context) =>
       JS('DelayNode', 'new DelayNode(#)', context);
 
-  final AudioParam delayTime;
+  AudioParam get delayTime => JS("AudioParam", "#.delayTime", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -830,7 +889,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory DynamicsCompressorNode(BaseAudioContext context, [Map options]) {
+  factory DynamicsCompressorNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return DynamicsCompressorNode._create_1(context, options_1);
@@ -845,17 +904,17 @@
   static DynamicsCompressorNode _create_2(context) =>
       JS('DynamicsCompressorNode', 'new DynamicsCompressorNode(#)', context);
 
-  final AudioParam attack;
+  AudioParam get attack => JS("AudioParam", "#.attack", this);
 
-  final AudioParam knee;
+  AudioParam get knee => JS("AudioParam", "#.knee", this);
 
-  final AudioParam ratio;
+  AudioParam get ratio => JS("AudioParam", "#.ratio", this);
 
-  final num reduction;
+  num get reduction => JS("num", "#.reduction", this);
 
-  final AudioParam release;
+  AudioParam get release => JS("AudioParam", "#.release", this);
 
-  final AudioParam threshold;
+  AudioParam get threshold => JS("AudioParam", "#.threshold", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -868,7 +927,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory GainNode(BaseAudioContext context, [Map options]) {
+  factory GainNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return GainNode._create_1(context, options_1);
@@ -880,7 +939,7 @@
   static GainNode _create_2(context) =>
       JS('GainNode', 'new GainNode(#)', context);
 
-  final AudioParam gain;
+  AudioParam get gain => JS("AudioParam", "#.gain", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -924,7 +983,7 @@
       context,
       options);
 
-  final MediaElement mediaElement;
+  MediaElement get mediaElement => JS("MediaElement", "#.mediaElement", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -938,7 +997,7 @@
   }
 
   factory MediaStreamAudioDestinationNode(BaseAudioContext context,
-      [Map options]) {
+      [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return MediaStreamAudioDestinationNode._create_1(context, options_1);
@@ -955,7 +1014,7 @@
       'new MediaStreamAudioDestinationNode(#)',
       context);
 
-  final MediaStream stream;
+  MediaStream get stream => JS("MediaStream", "#.stream", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -978,7 +1037,7 @@
       context,
       options);
 
-  final MediaStream mediaStream;
+  MediaStream get mediaStream => JS("MediaStream", "#.mediaStream", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1001,7 +1060,7 @@
       type,
       eventInitDict);
 
-  final AudioBuffer renderedBuffer;
+  AudioBuffer get renderedBuffer => JS("AudioBuffer", "#.renderedBuffer", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1015,7 +1074,7 @@
   }
 
   factory OfflineAudioContext(numberOfChannels_OR_options,
-      [int numberOfFrames, num sampleRate]) {
+      [int? numberOfFrames, num? sampleRate]) {
     if ((sampleRate is num) &&
         (numberOfFrames is int) &&
         (numberOfChannels_OR_options is int)) {
@@ -1040,7 +1099,7 @@
       'new OfflineAudioContext(#)',
       numberOfChannels_OR_options);
 
-  final int length;
+  int get length => JS("int", "#.length", this);
 
   Future<AudioBuffer> startRendering() =>
       promiseToFuture<AudioBuffer>(JS("", "#.startRendering()", this));
@@ -1060,7 +1119,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory OscillatorNode(BaseAudioContext context, [Map options]) {
+  factory OscillatorNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return OscillatorNode._create_1(context, options_1);
@@ -1072,11 +1131,15 @@
   static OscillatorNode _create_2(context) =>
       JS('OscillatorNode', 'new OscillatorNode(#)', context);
 
-  final AudioParam detune;
+  AudioParam get detune => JS("AudioParam", "#.detune", this);
 
-  final AudioParam frequency;
+  AudioParam get frequency => JS("AudioParam", "#.frequency", this);
 
-  String type;
+  String get type => JS("String", "#.type", this);
+
+  set type(String value) {
+    JS("void", "#.type = #", this, value);
+  }
 
   void setPeriodicWave(PeriodicWave periodicWave) native;
 }
@@ -1091,7 +1154,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory PannerNode(BaseAudioContext context, [Map options]) {
+  factory PannerNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return PannerNode._create_1(context, options_1);
@@ -1103,33 +1166,65 @@
   static PannerNode _create_2(context) =>
       JS('PannerNode', 'new PannerNode(#)', context);
 
-  num coneInnerAngle;
+  num get coneInnerAngle => JS("num", "#.coneInnerAngle", this);
 
-  num coneOuterAngle;
+  set coneInnerAngle(num value) {
+    JS("void", "#.coneInnerAngle = #", this, value);
+  }
 
-  num coneOuterGain;
+  num get coneOuterAngle => JS("num", "#.coneOuterAngle", this);
 
-  String distanceModel;
+  set coneOuterAngle(num value) {
+    JS("void", "#.coneOuterAngle = #", this, value);
+  }
 
-  num maxDistance;
+  num get coneOuterGain => JS("num", "#.coneOuterGain", this);
 
-  final AudioParam orientationX;
+  set coneOuterGain(num value) {
+    JS("void", "#.coneOuterGain = #", this, value);
+  }
 
-  final AudioParam orientationY;
+  String get distanceModel => JS("String", "#.distanceModel", this);
 
-  final AudioParam orientationZ;
+  set distanceModel(String value) {
+    JS("void", "#.distanceModel = #", this, value);
+  }
 
-  String panningModel;
+  num get maxDistance => JS("num", "#.maxDistance", this);
 
-  final AudioParam positionX;
+  set maxDistance(num value) {
+    JS("void", "#.maxDistance = #", this, value);
+  }
 
-  final AudioParam positionY;
+  AudioParam get orientationX => JS("AudioParam", "#.orientationX", this);
 
-  final AudioParam positionZ;
+  AudioParam get orientationY => JS("AudioParam", "#.orientationY", this);
 
-  num refDistance;
+  AudioParam get orientationZ => JS("AudioParam", "#.orientationZ", this);
 
-  num rolloffFactor;
+  String get panningModel => JS("String", "#.panningModel", this);
+
+  set panningModel(String value) {
+    JS("void", "#.panningModel = #", this, value);
+  }
+
+  AudioParam get positionX => JS("AudioParam", "#.positionX", this);
+
+  AudioParam get positionY => JS("AudioParam", "#.positionY", this);
+
+  AudioParam get positionZ => JS("AudioParam", "#.positionZ", this);
+
+  num get refDistance => JS("num", "#.refDistance", this);
+
+  set refDistance(num value) {
+    JS("void", "#.refDistance = #", this, value);
+  }
+
+  num get rolloffFactor => JS("num", "#.rolloffFactor", this);
+
+  set rolloffFactor(num value) {
+    JS("void", "#.rolloffFactor = #", this, value);
+  }
 
   void setOrientation(num x, num y, num z) native;
 
@@ -1146,7 +1241,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory PeriodicWave(BaseAudioContext context, [Map options]) {
+  factory PeriodicWave(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return PeriodicWave._create_1(context, options_1);
@@ -1178,7 +1273,7 @@
   static const EventStreamProvider<AudioProcessingEvent> audioProcessEvent =
       const EventStreamProvider<AudioProcessingEvent>('audioprocess');
 
-  final int bufferSize;
+  int get bufferSize => JS("int", "#.bufferSize", this);
 
   void setEventListener(EventListener eventListener) native;
 
@@ -1204,7 +1299,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory StereoPannerNode(BaseAudioContext context, [Map options]) {
+  factory StereoPannerNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return StereoPannerNode._create_1(context, options_1);
@@ -1216,7 +1311,7 @@
   static StereoPannerNode _create_2(context) =>
       JS('StereoPannerNode', 'new StereoPannerNode(#)', context);
 
-  final AudioParam pan;
+  AudioParam get pan => JS("AudioParam", "#.pan", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -1229,7 +1324,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory WaveShaperNode(BaseAudioContext context, [Map options]) {
+  factory WaveShaperNode(BaseAudioContext context, [Map? options]) {
     if (options != null) {
       var options_1 = convertDartToNative_Dictionary(options);
       return WaveShaperNode._create_1(context, options_1);
@@ -1241,7 +1336,11 @@
   static WaveShaperNode _create_2(context) =>
       JS('WaveShaperNode', 'new WaveShaperNode(#)', context);
 
-  Float32List curve;
+  Float32List? curve;
 
-  String oversample;
+  String get oversample => JS("String", "#.oversample", this);
+
+  set oversample(String value) {
+    JS("void", "#.oversample = #", this, value);
+  }
 }
diff --git a/sdk_nnbd/lib/web_gl/dart2js/web_gl_dart2js.dart b/sdk_nnbd/lib/web_gl/dart2js/web_gl_dart2js.dart
index 77e0a9f..f47047a 100644
--- a/sdk_nnbd/lib/web_gl/dart2js/web_gl_dart2js.dart
+++ b/sdk_nnbd/lib/web_gl/dart2js/web_gl_dart2js.dart
@@ -1,4 +1,3 @@
-// @dart = 2.5
 /**
  * 3D programming in the browser.
  *
@@ -33,11 +32,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final String name;
+  String get name => JS("String", "#.name", this);
 
-  final int size;
+  int get size => JS("int", "#.size", this);
 
-  final int type;
+  int get type => JS("int", "#.type", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -301,7 +300,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  factory ContextEvent(String type, [Map eventInit]) {
+  factory ContextEvent(String type, [Map? eventInit]) {
     if (eventInit != null) {
       var eventInit_1 = convertDartToNative_Dictionary(eventInit);
       return ContextEvent._create_1(type, eventInit_1);
@@ -313,7 +312,7 @@
   static ContextEvent _create_2(type) =>
       JS('ContextEvent', 'new WebGLContextEvent(#)', type);
 
-  final String statusMessage;
+  String get statusMessage => JS("String", "#.statusMessage", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -458,7 +457,7 @@
   TimerQueryExt createQueryExt() native;
 
   @JSName('deleteQueryEXT')
-  void deleteQueryExt(TimerQueryExt query) native;
+  void deleteQueryExt(TimerQueryExt? query) native;
 
   @JSName('endQueryEXT')
   void endQueryExt(int target) native;
@@ -470,7 +469,7 @@
   Object getQueryObjectExt(TimerQueryExt query, int pname) native;
 
   @JSName('isQueryEXT')
-  bool isQueryExt(TimerQueryExt query) native;
+  bool isQueryExt(TimerQueryExt? query) native;
 
   @JSName('queryCounterEXT')
   void queryCounterExt(TimerQueryExt query, int target) native;
@@ -558,7 +557,7 @@
   }
 
   Future getBufferSubDataAsync(int target, int srcByteOffset, TypedData dstData,
-          [int dstOffset, int length]) =>
+          [int? dstOffset, int? length]) =>
       promiseToFuture(JS("", "#.getBufferSubDataAsync(#, #, #, #, #)", this,
           target, srcByteOffset, dstData, dstOffset, length));
 }
@@ -661,16 +660,16 @@
   static const int VERTEX_ARRAY_BINDING_OES = 0x85B5;
 
   @JSName('bindVertexArrayOES')
-  void bindVertexArray(VertexArrayObjectOes arrayObject) native;
+  void bindVertexArray(VertexArrayObjectOes? arrayObject) native;
 
   @JSName('createVertexArrayOES')
   VertexArrayObjectOes createVertexArray() native;
 
   @JSName('deleteVertexArrayOES')
-  void deleteVertexArray(VertexArrayObjectOes arrayObject) native;
+  void deleteVertexArray(VertexArrayObjectOes? arrayObject) native;
 
   @JSName('isVertexArrayOES')
-  bool isVertexArray(VertexArrayObjectOes arrayObject) native;
+  bool isVertexArray(VertexArrayObjectOes? arrayObject) native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -724,13 +723,13 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => JS('bool', '!!(window.WebGLRenderingContext)');
 
-  final CanvasElement canvas;
+  CanvasElement get canvas => JS("CanvasElement", "#.canvas", this);
 
   // From WebGLRenderingContextBase
 
-  final int drawingBufferHeight;
+  int get drawingBufferHeight => JS("int", "#.drawingBufferHeight", this);
 
-  final int drawingBufferWidth;
+  int get drawingBufferWidth => JS("int", "#.drawingBufferWidth", this);
 
   void activeTexture(int texture) native;
 
@@ -738,13 +737,13 @@
 
   void bindAttribLocation(Program program, int index, String name) native;
 
-  void bindBuffer(int target, Buffer buffer) native;
+  void bindBuffer(int target, Buffer? buffer) native;
 
-  void bindFramebuffer(int target, Framebuffer framebuffer) native;
+  void bindFramebuffer(int target, Framebuffer? framebuffer) native;
 
-  void bindRenderbuffer(int target, Renderbuffer renderbuffer) native;
+  void bindRenderbuffer(int target, Renderbuffer? renderbuffer) native;
 
-  void bindTexture(int target, Texture texture) native;
+  void bindTexture(int target, Texture? texture) native;
 
   void blendColor(num red, num green, num blue, num alpha) native;
 
@@ -803,17 +802,17 @@
 
   void cullFace(int mode) native;
 
-  void deleteBuffer(Buffer buffer) native;
+  void deleteBuffer(Buffer? buffer) native;
 
-  void deleteFramebuffer(Framebuffer framebuffer) native;
+  void deleteFramebuffer(Framebuffer? framebuffer) native;
 
-  void deleteProgram(Program program) native;
+  void deleteProgram(Program? program) native;
 
-  void deleteRenderbuffer(Renderbuffer renderbuffer) native;
+  void deleteRenderbuffer(Renderbuffer? renderbuffer) native;
 
-  void deleteShader(Shader shader) native;
+  void deleteShader(Shader? shader) native;
 
-  void deleteTexture(Texture texture) native;
+  void deleteTexture(Texture? texture) native;
 
   void depthFunc(int func) native;
 
@@ -840,10 +839,10 @@
   void flush() native;
 
   void framebufferRenderbuffer(int target, int attachment,
-      int renderbuffertarget, Renderbuffer renderbuffer) native;
+      int renderbuffertarget, Renderbuffer? renderbuffer) native;
 
   void framebufferTexture2D(int target, int attachment, int textarget,
-      Texture texture, int level) native;
+      Texture? texture, int level) native;
 
   void frontFace(int mode) native;
 
@@ -928,21 +927,21 @@
 
   void hint(int target, int mode) native;
 
-  bool isBuffer(Buffer buffer) native;
+  bool isBuffer(Buffer? buffer) native;
 
   bool isContextLost() native;
 
   bool isEnabled(int cap) native;
 
-  bool isFramebuffer(Framebuffer framebuffer) native;
+  bool isFramebuffer(Framebuffer? framebuffer) native;
 
-  bool isProgram(Program program) native;
+  bool isProgram(Program? program) native;
 
-  bool isRenderbuffer(Renderbuffer renderbuffer) native;
+  bool isRenderbuffer(Renderbuffer? renderbuffer) native;
 
-  bool isShader(Shader shader) native;
+  bool isShader(Shader? shader) native;
 
-  bool isTexture(Texture texture) native;
+  bool isTexture(Texture? texture) native;
 
   void lineWidth(num width) native;
 
@@ -954,7 +953,7 @@
 
   @JSName('readPixels')
   void _readPixels(int x, int y, int width, int height, int format, int type,
-      TypedData pixels) native;
+      TypedData? pixels) native;
 
   void renderbufferStorage(
       int target, int internalformat, int width, int height) native;
@@ -984,9 +983,9 @@
       int format_OR_width,
       int height_OR_type,
       bitmap_OR_border_OR_canvas_OR_image_OR_pixels_OR_video,
-      [int format,
-      int type,
-      TypedData pixels]) {
+      [int? format,
+      int? type,
+      TypedData? pixels]) {
     if (type != null &&
         format != null &&
         (bitmap_OR_border_OR_canvas_OR_image_OR_pixels_OR_video is int)) {
@@ -1073,7 +1072,7 @@
 
   @JSName('texImage2D')
   void _texImage2D_1(target, level, internalformat, width, height, int border,
-      format, type, TypedData pixels) native;
+      format, type, TypedData? pixels) native;
   @JSName('texImage2D')
   void _texImage2D_2(target, level, internalformat, format, type, pixels)
       native;
@@ -1102,8 +1101,8 @@
       int format_OR_width,
       int height_OR_type,
       bitmap_OR_canvas_OR_format_OR_image_OR_pixels_OR_video,
-      [int type,
-      TypedData pixels]) {
+      [int? type,
+      TypedData? pixels]) {
     if (type != null &&
         (bitmap_OR_canvas_OR_format_OR_image_OR_pixels_OR_video is int)) {
       _texSubImage2D_1(
@@ -1188,7 +1187,7 @@
 
   @JSName('texSubImage2D')
   void _texSubImage2D_1(target, level, xoffset, yoffset, width, height,
-      int format, type, TypedData pixels) native;
+      int format, type, TypedData? pixels) native;
   @JSName('texSubImage2D')
   void _texSubImage2D_2(target, level, xoffset, yoffset, format, type, pixels)
       native;
@@ -1205,45 +1204,48 @@
   void _texSubImage2D_6(
       target, level, xoffset, yoffset, format, type, ImageBitmap bitmap) native;
 
-  void uniform1f(UniformLocation location, num x) native;
+  void uniform1f(UniformLocation? location, num x) native;
 
-  void uniform1fv(UniformLocation location, v) native;
+  void uniform1fv(UniformLocation? location, v) native;
 
-  void uniform1i(UniformLocation location, int x) native;
+  void uniform1i(UniformLocation? location, int x) native;
 
-  void uniform1iv(UniformLocation location, v) native;
+  void uniform1iv(UniformLocation? location, v) native;
 
-  void uniform2f(UniformLocation location, num x, num y) native;
+  void uniform2f(UniformLocation? location, num x, num y) native;
 
-  void uniform2fv(UniformLocation location, v) native;
+  void uniform2fv(UniformLocation? location, v) native;
 
-  void uniform2i(UniformLocation location, int x, int y) native;
+  void uniform2i(UniformLocation? location, int x, int y) native;
 
-  void uniform2iv(UniformLocation location, v) native;
+  void uniform2iv(UniformLocation? location, v) native;
 
-  void uniform3f(UniformLocation location, num x, num y, num z) native;
+  void uniform3f(UniformLocation? location, num x, num y, num z) native;
 
-  void uniform3fv(UniformLocation location, v) native;
+  void uniform3fv(UniformLocation? location, v) native;
 
-  void uniform3i(UniformLocation location, int x, int y, int z) native;
+  void uniform3i(UniformLocation? location, int x, int y, int z) native;
 
-  void uniform3iv(UniformLocation location, v) native;
+  void uniform3iv(UniformLocation? location, v) native;
 
-  void uniform4f(UniformLocation location, num x, num y, num z, num w) native;
+  void uniform4f(UniformLocation? location, num x, num y, num z, num w) native;
 
-  void uniform4fv(UniformLocation location, v) native;
+  void uniform4fv(UniformLocation? location, v) native;
 
-  void uniform4i(UniformLocation location, int x, int y, int z, int w) native;
+  void uniform4i(UniformLocation? location, int x, int y, int z, int w) native;
 
-  void uniform4iv(UniformLocation location, v) native;
+  void uniform4iv(UniformLocation? location, v) native;
 
-  void uniformMatrix2fv(UniformLocation location, bool transpose, array) native;
+  void uniformMatrix2fv(UniformLocation? location, bool transpose, array)
+      native;
 
-  void uniformMatrix3fv(UniformLocation location, bool transpose, array) native;
+  void uniformMatrix3fv(UniformLocation? location, bool transpose, array)
+      native;
 
-  void uniformMatrix4fv(UniformLocation location, bool transpose, array) native;
+  void uniformMatrix4fv(UniformLocation? location, bool transpose, array)
+      native;
 
-  void useProgram(Program program) native;
+  void useProgram(Program? program) native;
 
   void validateProgram(Program program) native;
 
@@ -1361,7 +1363,7 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final Canvas canvas;
+  Canvas get canvas => JS("Canvas", "#.canvas", this);
 
   // From WebGL2RenderingContextBase
 
@@ -1369,36 +1371,38 @@
 
   void beginTransformFeedback(int primitiveMode) native;
 
-  void bindBufferBase(int target, int index, Buffer buffer) native;
+  void bindBufferBase(int target, int index, Buffer? buffer) native;
 
   void bindBufferRange(
-      int target, int index, Buffer buffer, int offset, int size) native;
+      int target, int index, Buffer? buffer, int offset, int size) native;
 
-  void bindSampler(int unit, Sampler sampler) native;
+  void bindSampler(int unit, Sampler? sampler) native;
 
-  void bindTransformFeedback(int target, TransformFeedback feedback) native;
+  void bindTransformFeedback(int target, TransformFeedback? feedback) native;
 
-  void bindVertexArray(VertexArrayObject vertexArray) native;
+  void bindVertexArray(VertexArrayObject? vertexArray) native;
 
   void blitFramebuffer(int srcX0, int srcY0, int srcX1, int srcY1, int dstX0,
       int dstY0, int dstX1, int dstY1, int mask, int filter) native;
 
   @JSName('bufferData')
   void bufferData2(int target, TypedData srcData, int usage, int srcOffset,
-      [int length]) native;
+      [int? length]) native;
 
   @JSName('bufferSubData')
   void bufferSubData2(
       int target, int dstByteOffset, TypedData srcData, int srcOffset,
-      [int length]) native;
+      [int? length]) native;
 
   void clearBufferfi(int buffer, int drawbuffer, num depth, int stencil) native;
 
-  void clearBufferfv(int buffer, int drawbuffer, value, [int srcOffset]) native;
+  void clearBufferfv(int buffer, int drawbuffer, value, [int? srcOffset])
+      native;
 
-  void clearBufferiv(int buffer, int drawbuffer, value, [int srcOffset]) native;
+  void clearBufferiv(int buffer, int drawbuffer, value, [int? srcOffset])
+      native;
 
-  void clearBufferuiv(int buffer, int drawbuffer, value, [int srcOffset])
+  void clearBufferuiv(int buffer, int drawbuffer, value, [int? srcOffset])
       native;
 
   int clientWaitSync(Sync sync, int flags, int timeout) native;
@@ -1406,7 +1410,7 @@
   @JSName('compressedTexImage2D')
   void compressedTexImage2D2(int target, int level, int internalformat,
       int width, int height, int border, TypedData data, int srcOffset,
-      [int srcLengthOverride]) native;
+      [int? srcLengthOverride]) native;
 
   @JSName('compressedTexImage2D')
   void compressedTexImage2D3(int target, int level, int internalformat,
@@ -1414,7 +1418,7 @@
 
   void compressedTexImage3D(int target, int level, int internalformat,
       int width, int height, int depth, int border, TypedData data,
-      [int srcOffset, int srcLengthOverride]) native;
+      [int? srcOffset, int? srcLengthOverride]) native;
 
   @JSName('compressedTexImage3D')
   void compressedTexImage3D2(
@@ -1431,7 +1435,7 @@
   @JSName('compressedTexSubImage2D')
   void compressedTexSubImage2D2(int target, int level, int xoffset, int yoffset,
       int width, int height, int format, TypedData data, int srcOffset,
-      [int srcLengthOverride]) native;
+      [int? srcLengthOverride]) native;
 
   @JSName('compressedTexSubImage2D')
   void compressedTexSubImage2D3(int target, int level, int xoffset, int yoffset,
@@ -1439,7 +1443,7 @@
 
   void compressedTexSubImage3D(int target, int level, int xoffset, int yoffset,
       int zoffset, int width, int height, int depth, int format, TypedData data,
-      [int srcOffset, int srcLengthOverride]) native;
+      [int? srcOffset, int? srcLengthOverride]) native;
 
   @JSName('compressedTexSubImage3D')
   void compressedTexSubImage3D2(
@@ -1469,15 +1473,15 @@
 
   VertexArrayObject createVertexArray() native;
 
-  void deleteQuery(Query query) native;
+  void deleteQuery(Query? query) native;
 
-  void deleteSampler(Sampler sampler) native;
+  void deleteSampler(Sampler? sampler) native;
 
-  void deleteSync(Sync sync) native;
+  void deleteSync(Sync? sync) native;
 
-  void deleteTransformFeedback(TransformFeedback feedback) native;
+  void deleteTransformFeedback(TransformFeedback? feedback) native;
 
-  void deleteVertexArray(VertexArrayObject vertexArray) native;
+  void deleteVertexArray(VertexArrayObject? vertexArray) native;
 
   void drawArraysInstanced(int mode, int first, int count, int instanceCount)
       native;
@@ -1496,8 +1500,8 @@
 
   Sync fenceSync(int condition, int flags) native;
 
-  void framebufferTextureLayer(
-      int target, int attachment, Texture texture, int level, int layer) native;
+  void framebufferTextureLayer(int target, int attachment, Texture? texture,
+      int level, int layer) native;
 
   String getActiveUniformBlockName(Program program, int uniformBlockIndex)
       native;
@@ -1509,7 +1513,7 @@
       native;
 
   void getBufferSubData(int target, int srcByteOffset, TypedData dstData,
-      [int dstOffset, int length]) native;
+      [int? dstOffset, int? length]) native;
 
   int getFragDataLocation(Program program, String name) native;
 
@@ -1543,15 +1547,15 @@
   void invalidateSubFramebuffer(int target, List<int> attachments, int x, int y,
       int width, int height) native;
 
-  bool isQuery(Query query) native;
+  bool isQuery(Query? query) native;
 
-  bool isSampler(Sampler sampler) native;
+  bool isSampler(Sampler? sampler) native;
 
-  bool isSync(Sync sync) native;
+  bool isSync(Sync? sync) native;
 
-  bool isTransformFeedback(TransformFeedback feedback) native;
+  bool isTransformFeedback(TransformFeedback? feedback) native;
 
-  bool isVertexArray(VertexArrayObject vertexArray) native;
+  bool isVertexArray(VertexArrayObject? vertexArray) native;
 
   void pauseTransformFeedback() native;
 
@@ -1560,7 +1564,7 @@
   @JSName('readPixels')
   void readPixels2(int x, int y, int width, int height, int format, int type,
       dstData_OR_offset,
-      [int offset]) native;
+      [int? offset]) native;
 
   void renderbufferStorageMultisample(int target, int samples,
       int internalformat, int width, int height) native;
@@ -1581,7 +1585,7 @@
       int format,
       int type,
       bitmap_OR_canvas_OR_data_OR_image_OR_offset_OR_srcData_OR_video,
-      [int srcOffset]) {
+      [int? srcOffset]) {
     if ((bitmap_OR_canvas_OR_data_OR_image_OR_offset_OR_srcData_OR_video
             is int) &&
         srcOffset == null) {
@@ -1718,7 +1722,7 @@
       int format,
       int type,
       bitmap_OR_canvas_OR_data_OR_image_OR_offset_OR_pixels_OR_video,
-      [int srcOffset]) {
+      [int? srcOffset]) {
     if ((bitmap_OR_canvas_OR_data_OR_image_OR_offset_OR_pixels_OR_video
             is int) &&
         srcOffset == null) {
@@ -1866,7 +1870,7 @@
       border, format, type, ImageBitmap bitmap) native;
   @JSName('texImage3D')
   void _texImage3D_7(target, level, internalformat, width, height, depth,
-      border, format, type, TypedData pixels) native;
+      border, format, type, TypedData? pixels) native;
   @JSName('texImage3D')
   void _texImage3D_8(target, level, internalformat, width, height, depth,
       border, format, type, TypedData pixels, srcOffset) native;
@@ -1887,7 +1891,7 @@
       int format,
       int type,
       bitmap_OR_canvas_OR_data_OR_image_OR_offset_OR_srcData_OR_video,
-      [int srcOffset]) {
+      [int? srcOffset]) {
     if ((bitmap_OR_canvas_OR_data_OR_image_OR_offset_OR_srcData_OR_video
             is int) &&
         srcOffset == null) {
@@ -2025,7 +2029,7 @@
       int format,
       int type,
       bitmap_OR_canvas_OR_data_OR_image_OR_offset_OR_pixels_OR_video,
-      [int srcOffset]) {
+      [int? srcOffset]) {
     if ((bitmap_OR_canvas_OR_data_OR_image_OR_offset_OR_pixels_OR_video
             is int) &&
         srcOffset == null) {
@@ -2195,93 +2199,93 @@
       native;
 
   @JSName('uniform1fv')
-  void uniform1fv2(UniformLocation location, v, int srcOffset, [int srcLength])
-      native;
+  void uniform1fv2(UniformLocation? location, v, int srcOffset,
+      [int? srcLength]) native;
 
   @JSName('uniform1iv')
-  void uniform1iv2(UniformLocation location, v, int srcOffset, [int srcLength])
-      native;
+  void uniform1iv2(UniformLocation? location, v, int srcOffset,
+      [int? srcLength]) native;
 
-  void uniform1ui(UniformLocation location, int v0) native;
+  void uniform1ui(UniformLocation? location, int v0) native;
 
-  void uniform1uiv(UniformLocation location, v, [int srcOffset, int srcLength])
-      native;
+  void uniform1uiv(UniformLocation? location, v,
+      [int? srcOffset, int? srcLength]) native;
 
   @JSName('uniform2fv')
-  void uniform2fv2(UniformLocation location, v, int srcOffset, [int srcLength])
-      native;
+  void uniform2fv2(UniformLocation? location, v, int srcOffset,
+      [int? srcLength]) native;
 
   @JSName('uniform2iv')
-  void uniform2iv2(UniformLocation location, v, int srcOffset, [int srcLength])
-      native;
+  void uniform2iv2(UniformLocation? location, v, int srcOffset,
+      [int? srcLength]) native;
 
-  void uniform2ui(UniformLocation location, int v0, int v1) native;
+  void uniform2ui(UniformLocation? location, int v0, int v1) native;
 
-  void uniform2uiv(UniformLocation location, v, [int srcOffset, int srcLength])
-      native;
+  void uniform2uiv(UniformLocation? location, v,
+      [int? srcOffset, int? srcLength]) native;
 
   @JSName('uniform3fv')
-  void uniform3fv2(UniformLocation location, v, int srcOffset, [int srcLength])
-      native;
+  void uniform3fv2(UniformLocation? location, v, int srcOffset,
+      [int? srcLength]) native;
 
   @JSName('uniform3iv')
-  void uniform3iv2(UniformLocation location, v, int srcOffset, [int srcLength])
-      native;
+  void uniform3iv2(UniformLocation? location, v, int srcOffset,
+      [int? srcLength]) native;
 
-  void uniform3ui(UniformLocation location, int v0, int v1, int v2) native;
+  void uniform3ui(UniformLocation? location, int v0, int v1, int v2) native;
 
-  void uniform3uiv(UniformLocation location, v, [int srcOffset, int srcLength])
-      native;
+  void uniform3uiv(UniformLocation? location, v,
+      [int? srcOffset, int? srcLength]) native;
 
   @JSName('uniform4fv')
-  void uniform4fv2(UniformLocation location, v, int srcOffset, [int srcLength])
-      native;
+  void uniform4fv2(UniformLocation? location, v, int srcOffset,
+      [int? srcLength]) native;
 
   @JSName('uniform4iv')
-  void uniform4iv2(UniformLocation location, v, int srcOffset, [int srcLength])
+  void uniform4iv2(UniformLocation? location, v, int srcOffset,
+      [int? srcLength]) native;
+
+  void uniform4ui(UniformLocation? location, int v0, int v1, int v2, int v3)
       native;
 
-  void uniform4ui(UniformLocation location, int v0, int v1, int v2, int v3)
-      native;
-
-  void uniform4uiv(UniformLocation location, v, [int srcOffset, int srcLength])
-      native;
+  void uniform4uiv(UniformLocation? location, v,
+      [int? srcOffset, int? srcLength]) native;
 
   void uniformBlockBinding(
       Program program, int uniformBlockIndex, int uniformBlockBinding) native;
 
   @JSName('uniformMatrix2fv')
   void uniformMatrix2fv2(
-      UniformLocation location, bool transpose, array, int srcOffset,
-      [int srcLength]) native;
+      UniformLocation? location, bool transpose, array, int srcOffset,
+      [int? srcLength]) native;
 
-  void uniformMatrix2x3fv(UniformLocation location, bool transpose, value,
-      [int srcOffset, int srcLength]) native;
+  void uniformMatrix2x3fv(UniformLocation? location, bool transpose, value,
+      [int? srcOffset, int? srcLength]) native;
 
-  void uniformMatrix2x4fv(UniformLocation location, bool transpose, value,
-      [int srcOffset, int srcLength]) native;
+  void uniformMatrix2x4fv(UniformLocation? location, bool transpose, value,
+      [int? srcOffset, int? srcLength]) native;
 
   @JSName('uniformMatrix3fv')
   void uniformMatrix3fv2(
-      UniformLocation location, bool transpose, array, int srcOffset,
-      [int srcLength]) native;
+      UniformLocation? location, bool transpose, array, int srcOffset,
+      [int? srcLength]) native;
 
-  void uniformMatrix3x2fv(UniformLocation location, bool transpose, value,
-      [int srcOffset, int srcLength]) native;
+  void uniformMatrix3x2fv(UniformLocation? location, bool transpose, value,
+      [int? srcOffset, int? srcLength]) native;
 
-  void uniformMatrix3x4fv(UniformLocation location, bool transpose, value,
-      [int srcOffset, int srcLength]) native;
+  void uniformMatrix3x4fv(UniformLocation? location, bool transpose, value,
+      [int? srcOffset, int? srcLength]) native;
 
   @JSName('uniformMatrix4fv')
   void uniformMatrix4fv2(
-      UniformLocation location, bool transpose, array, int srcOffset,
-      [int srcLength]) native;
+      UniformLocation? location, bool transpose, array, int srcOffset,
+      [int? srcLength]) native;
 
-  void uniformMatrix4x2fv(UniformLocation location, bool transpose, value,
-      [int srcOffset, int srcLength]) native;
+  void uniformMatrix4x2fv(UniformLocation? location, bool transpose, value,
+      [int? srcOffset, int? srcLength]) native;
 
-  void uniformMatrix4x3fv(UniformLocation location, bool transpose, value,
-      [int srcOffset, int srcLength]) native;
+  void uniformMatrix4x3fv(UniformLocation? location, bool transpose, value,
+      [int? srcOffset, int? srcLength]) native;
 
   void vertexAttribDivisor(int index, int divisor) native;
 
@@ -2300,9 +2304,9 @@
 
   // From WebGLRenderingContextBase
 
-  final int drawingBufferHeight;
+  int get drawingBufferHeight => JS("int", "#.drawingBufferHeight", this);
 
-  final int drawingBufferWidth;
+  int get drawingBufferWidth => JS("int", "#.drawingBufferWidth", this);
 
   void activeTexture(int texture) native;
 
@@ -2310,13 +2314,13 @@
 
   void bindAttribLocation(Program program, int index, String name) native;
 
-  void bindBuffer(int target, Buffer buffer) native;
+  void bindBuffer(int target, Buffer? buffer) native;
 
-  void bindFramebuffer(int target, Framebuffer framebuffer) native;
+  void bindFramebuffer(int target, Framebuffer? framebuffer) native;
 
-  void bindRenderbuffer(int target, Renderbuffer renderbuffer) native;
+  void bindRenderbuffer(int target, Renderbuffer? renderbuffer) native;
 
-  void bindTexture(int target, Texture texture) native;
+  void bindTexture(int target, Texture? texture) native;
 
   void blendColor(num red, num green, num blue, num alpha) native;
 
@@ -2375,17 +2379,17 @@
 
   void cullFace(int mode) native;
 
-  void deleteBuffer(Buffer buffer) native;
+  void deleteBuffer(Buffer? buffer) native;
 
-  void deleteFramebuffer(Framebuffer framebuffer) native;
+  void deleteFramebuffer(Framebuffer? framebuffer) native;
 
-  void deleteProgram(Program program) native;
+  void deleteProgram(Program? program) native;
 
-  void deleteRenderbuffer(Renderbuffer renderbuffer) native;
+  void deleteRenderbuffer(Renderbuffer? renderbuffer) native;
 
-  void deleteShader(Shader shader) native;
+  void deleteShader(Shader? shader) native;
 
-  void deleteTexture(Texture texture) native;
+  void deleteTexture(Texture? texture) native;
 
   void depthFunc(int func) native;
 
@@ -2412,10 +2416,10 @@
   void flush() native;
 
   void framebufferRenderbuffer(int target, int attachment,
-      int renderbuffertarget, Renderbuffer renderbuffer) native;
+      int renderbuffertarget, Renderbuffer? renderbuffer) native;
 
   void framebufferTexture2D(int target, int attachment, int textarget,
-      Texture texture, int level) native;
+      Texture? texture, int level) native;
 
   void frontFace(int mode) native;
 
@@ -2476,21 +2480,21 @@
 
   void hint(int target, int mode) native;
 
-  bool isBuffer(Buffer buffer) native;
+  bool isBuffer(Buffer? buffer) native;
 
   bool isContextLost() native;
 
   bool isEnabled(int cap) native;
 
-  bool isFramebuffer(Framebuffer framebuffer) native;
+  bool isFramebuffer(Framebuffer? framebuffer) native;
 
-  bool isProgram(Program program) native;
+  bool isProgram(Program? program) native;
 
-  bool isRenderbuffer(Renderbuffer renderbuffer) native;
+  bool isRenderbuffer(Renderbuffer? renderbuffer) native;
 
-  bool isShader(Shader shader) native;
+  bool isShader(Shader? shader) native;
 
-  bool isTexture(Texture texture) native;
+  bool isTexture(Texture? texture) native;
 
   void lineWidth(num width) native;
 
@@ -2502,7 +2506,7 @@
 
   @JSName('readPixels')
   void _readPixels(int x, int y, int width, int height, int format, int type,
-      TypedData pixels) native;
+      TypedData? pixels) native;
 
   void renderbufferStorage(
       int target, int internalformat, int width, int height) native;
@@ -2532,9 +2536,9 @@
       int format_OR_width,
       int height_OR_type,
       bitmap_OR_border_OR_canvas_OR_image_OR_pixels_OR_video,
-      [int format,
-      int type,
-      TypedData pixels]) {
+      [int? format,
+      int? type,
+      TypedData? pixels]) {
     if (type != null &&
         format != null &&
         (bitmap_OR_border_OR_canvas_OR_image_OR_pixels_OR_video is int)) {
@@ -2621,7 +2625,7 @@
 
   @JSName('texImage2D')
   void _texImage2D_1(target, level, internalformat, width, height, int border,
-      format, type, TypedData pixels) native;
+      format, type, TypedData? pixels) native;
   @JSName('texImage2D')
   void _texImage2D_2(target, level, internalformat, format, type, pixels)
       native;
@@ -2650,8 +2654,8 @@
       int format_OR_width,
       int height_OR_type,
       bitmap_OR_canvas_OR_format_OR_image_OR_pixels_OR_video,
-      [int type,
-      TypedData pixels]) {
+      [int? type,
+      TypedData? pixels]) {
     if (type != null &&
         (bitmap_OR_canvas_OR_format_OR_image_OR_pixels_OR_video is int)) {
       _texSubImage2D_1(
@@ -2736,7 +2740,7 @@
 
   @JSName('texSubImage2D')
   void _texSubImage2D_1(target, level, xoffset, yoffset, width, height,
-      int format, type, TypedData pixels) native;
+      int format, type, TypedData? pixels) native;
   @JSName('texSubImage2D')
   void _texSubImage2D_2(target, level, xoffset, yoffset, format, type, pixels)
       native;
@@ -2753,45 +2757,48 @@
   void _texSubImage2D_6(
       target, level, xoffset, yoffset, format, type, ImageBitmap bitmap) native;
 
-  void uniform1f(UniformLocation location, num x) native;
+  void uniform1f(UniformLocation? location, num x) native;
 
-  void uniform1fv(UniformLocation location, v) native;
+  void uniform1fv(UniformLocation? location, v) native;
 
-  void uniform1i(UniformLocation location, int x) native;
+  void uniform1i(UniformLocation? location, int x) native;
 
-  void uniform1iv(UniformLocation location, v) native;
+  void uniform1iv(UniformLocation? location, v) native;
 
-  void uniform2f(UniformLocation location, num x, num y) native;
+  void uniform2f(UniformLocation? location, num x, num y) native;
 
-  void uniform2fv(UniformLocation location, v) native;
+  void uniform2fv(UniformLocation? location, v) native;
 
-  void uniform2i(UniformLocation location, int x, int y) native;
+  void uniform2i(UniformLocation? location, int x, int y) native;
 
-  void uniform2iv(UniformLocation location, v) native;
+  void uniform2iv(UniformLocation? location, v) native;
 
-  void uniform3f(UniformLocation location, num x, num y, num z) native;
+  void uniform3f(UniformLocation? location, num x, num y, num z) native;
 
-  void uniform3fv(UniformLocation location, v) native;
+  void uniform3fv(UniformLocation? location, v) native;
 
-  void uniform3i(UniformLocation location, int x, int y, int z) native;
+  void uniform3i(UniformLocation? location, int x, int y, int z) native;
 
-  void uniform3iv(UniformLocation location, v) native;
+  void uniform3iv(UniformLocation? location, v) native;
 
-  void uniform4f(UniformLocation location, num x, num y, num z, num w) native;
+  void uniform4f(UniformLocation? location, num x, num y, num z, num w) native;
 
-  void uniform4fv(UniformLocation location, v) native;
+  void uniform4fv(UniformLocation? location, v) native;
 
-  void uniform4i(UniformLocation location, int x, int y, int z, int w) native;
+  void uniform4i(UniformLocation? location, int x, int y, int z, int w) native;
 
-  void uniform4iv(UniformLocation location, v) native;
+  void uniform4iv(UniformLocation? location, v) native;
 
-  void uniformMatrix2fv(UniformLocation location, bool transpose, array) native;
+  void uniformMatrix2fv(UniformLocation? location, bool transpose, array)
+      native;
 
-  void uniformMatrix3fv(UniformLocation location, bool transpose, array) native;
+  void uniformMatrix3fv(UniformLocation? location, bool transpose, array)
+      native;
 
-  void uniformMatrix4fv(UniformLocation location, bool transpose, array) native;
+  void uniformMatrix4fv(UniformLocation? location, bool transpose, array)
+      native;
 
-  void useProgram(Program program) native;
+  void useProgram(Program? program) native;
 
   void validateProgram(Program program) native;
 
@@ -2855,11 +2862,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int precision;
+  int get precision => JS("int", "#.precision", this);
 
-  final int rangeMax;
+  int get rangeMax => JS("int", "#.rangeMax", this);
 
-  final int rangeMin;
+  int get rangeMin => JS("int", "#.rangeMin", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -2883,13 +2890,16 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final bool lastUploadedVideoFrameWasSkipped;
+  bool get lastUploadedVideoFrameWasSkipped =>
+      JS("bool", "#.lastUploadedVideoFrameWasSkipped", this);
 
-  final int lastUploadedVideoHeight;
+  int get lastUploadedVideoHeight =>
+      JS("int", "#.lastUploadedVideoHeight", this);
 
-  final num lastUploadedVideoTimestamp;
+  num get lastUploadedVideoTimestamp =>
+      JS("num", "#.lastUploadedVideoTimestamp", this);
 
-  final int lastUploadedVideoWidth;
+  int get lastUploadedVideoWidth => JS("int", "#.lastUploadedVideoWidth", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
diff --git a/sdk_nnbd/lib/web_sql/dart2js/web_sql_dart2js.dart b/sdk_nnbd/lib/web_sql/dart2js/web_sql_dart2js.dart
index 106ae4d..53f192b 100644
--- a/sdk_nnbd/lib/web_sql/dart2js/web_sql_dart2js.dart
+++ b/sdk_nnbd/lib/web_sql/dart2js/web_sql_dart2js.dart
@@ -1,4 +1,3 @@
-// @dart = 2.5
 /**
  * An API for storing data in the browser that can be queried with SQL.
  *
@@ -79,7 +78,7 @@
   /// Checks if this type is supported on the current platform.
   static bool get supported => JS('bool', '!!(window.openDatabase)');
 
-  final String version;
+  String get version => JS("String", "#.version", this);
 
   @JSName('changeVersion')
   /**
@@ -97,9 +96,9 @@
    * * [Database.changeVersion](http://www.w3.org/TR/webdatabase/#dom-database-changeversion) from W3C.
    */
   void _changeVersion(String oldVersion, String newVersion,
-      [SqlTransactionCallback callback,
-      SqlTransactionErrorCallback errorCallback,
-      VoidCallback successCallback]) native;
+      [SqlTransactionCallback? callback,
+      SqlTransactionErrorCallback? errorCallback,
+      VoidCallback? successCallback]) native;
 
   @JSName('changeVersion')
   /**
@@ -128,8 +127,8 @@
 
   @JSName('readTransaction')
   void _readTransaction(SqlTransactionCallback callback,
-      [SqlTransactionErrorCallback errorCallback,
-      VoidCallback successCallback]) native;
+      [SqlTransactionErrorCallback? errorCallback,
+      VoidCallback? successCallback]) native;
 
   @JSName('readTransaction')
   Future<SqlTransaction> readTransaction() {
@@ -143,8 +142,8 @@
   }
 
   void transaction(SqlTransactionCallback callback,
-      [SqlTransactionErrorCallback errorCallback,
-      VoidCallback successCallback]) native;
+      [SqlTransactionErrorCallback? errorCallback,
+      VoidCallback? successCallback]) native;
 
   @JSName('transaction')
   Future<SqlTransaction> transaction_future() {
@@ -185,9 +184,9 @@
 
   static const int VERSION_ERR = 2;
 
-  final int code;
+  int get code => JS("int", "#.code", this);
 
-  final String message;
+  String get message => JS("String", "#.message", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -200,11 +199,11 @@
     throw new UnsupportedError("Not supported");
   }
 
-  final int insertId;
+  int get insertId => JS("int", "#.insertId", this);
 
-  final SqlResultSetRowList rows;
+  SqlResultSetRowList get rows => JS("SqlResultSetRowList", "#.rows", this);
 
-  final int rowsAffected;
+  int get rowsAffected => JS("int", "#.rowsAffected", this);
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -288,12 +287,12 @@
 
   @JSName('executeSql')
   void _executeSql(String sqlStatement,
-      [List arguments,
-      SqlStatementCallback callback,
-      SqlStatementErrorCallback errorCallback]) native;
+      [List? arguments,
+      SqlStatementCallback? callback,
+      SqlStatementErrorCallback? errorCallback]) native;
 
   @JSName('executeSql')
-  Future<SqlResultSet> executeSql(String sqlStatement, [List arguments]) {
+  Future<SqlResultSet> executeSql(String sqlStatement, [List? arguments]) {
     var completer = new Completer<SqlResultSet>();
     _executeSql(sqlStatement, arguments, (transaction, resultSet) {
       applyExtension('SQLResultSet', resultSet);
diff --git a/tests/co19_2/co19_2-dart2js.status b/tests/co19_2/co19_2-dart2js.status
index 4434d09..df64c4a 100644
--- a/tests/co19_2/co19_2-dart2js.status
+++ b/tests/co19_2/co19_2-dart2js.status
@@ -8,14 +8,14 @@
 WebPlatformTest/*: SkipByDesign # d8 is not a browser
 
 [ $compiler == dart2js && $runtime == d8 && $host_checked ]
-LibTest/collection/ListBase/ListBase_class_A01_t04: Slow
-LibTest/collection/ListBase/ListBase_class_A01_t05: Slow
-LibTest/collection/ListBase/ListBase_class_A01_t06: Slow
-LibTest/collection/ListMixin/ListMixin_class_A01_t04: Slow
-LibTest/collection/ListMixin/ListMixin_class_A01_t05: Slow
-LibTest/collection/ListMixin/ListMixin_class_A01_t06: Slow
-LibTest/core/List/List_class_A01_t05: Slow
-LibTest/core/List/List_class_A01_t06: Slow
+LibTest/collection/ListBase/ListBase_class_A01_t04: Slow, Pass
+LibTest/collection/ListBase/ListBase_class_A01_t05: Slow, Pass
+LibTest/collection/ListBase/ListBase_class_A01_t06: Slow, Pass
+LibTest/collection/ListMixin/ListMixin_class_A01_t04: Slow, Pass
+LibTest/collection/ListMixin/ListMixin_class_A01_t05: Slow, Pass
+LibTest/collection/ListMixin/ListMixin_class_A01_t06: Slow, Pass
+LibTest/core/List/List_class_A01_t05: Slow, Pass
+LibTest/core/List/List_class_A01_t06: Slow, Pass
 
 [ $compiler == dart2js && $runtime == ie11 ]
 LibTest/collection/ListBase/ListBase_class_A01_t04: SkipSlow # slow babeljs transformation
diff --git a/tests/co19_2/co19_2-kernel.status b/tests/co19_2/co19_2-kernel.status
index 2511212..8aa80ab 100644
--- a/tests/co19_2/co19_2-kernel.status
+++ b/tests/co19_2/co19_2-kernel.status
@@ -3,9 +3,9 @@
 # BSD-style license that can be found in the LICENSE file.
 
 [ $builder_tag == bytecode_interpreter ]
-LibTest/collection/ListBase/ListBase_class_A01_t04: Slow
-LibTest/collection/ListBase/ListBase_class_A01_t05: Slow
-LibTest/collection/ListBase/ListBase_class_A01_t06: Slow
+LibTest/collection/ListBase/ListBase_class_A01_t04: Slow, Pass
+LibTest/collection/ListBase/ListBase_class_A01_t05: Slow, Pass
+LibTest/collection/ListBase/ListBase_class_A01_t06: Slow, Pass
 
 [ $compiler == dartkb ]
 LibTest/isolate/Isolate/kill_A01_t01: Skip # Issue 37699
@@ -18,9 +18,9 @@
 LanguageFeatures/Constant-update-2018/NewOperators_A01_t06/none: Crash
 
 [ $runtime == vm ]
-LibTest/collection/ListBase/ListBase_class_A01_t02: Slow # Does many calls
-LibTest/collection/ListMixin/ListMixin_class_A01_t02: Slow # Does many calls
-LibTest/core/List/List_class_A01_t02: Slow # Does many calls
+LibTest/collection/ListBase/ListBase_class_A01_t02: Slow, Pass # Does many calls
+LibTest/collection/ListMixin/ListMixin_class_A01_t02: Slow, Pass # Does many calls
+LibTest/core/List/List_class_A01_t02: Slow, Pass # Does many calls
 LibTest/io/RawDatagramSocket/*: Skip # RawDatagramSocket are flacky. Skip them all until rewritten
 
 [ $fasta ]
@@ -182,12 +182,12 @@
 LibTest/isolate/Isolate/spawn_A06_t03: Crash
 
 [ $runtime == vm && $system == macos && ($compiler == dartk || $compiler == dartkb) ]
-LibTest/collection/ListBase/ListBase_class_A01_t02: Slow
-LibTest/collection/ListBase/ListBase_class_A01_t03: Slow
-LibTest/collection/ListMixin/ListMixin_class_A01_t02: Slow
-LibTest/collection/ListMixin/ListMixin_class_A01_t03: Slow
-LibTest/core/List/List_class_A01_t02: Slow
-LibTest/core/List/List_class_A01_t03: Slow
+LibTest/collection/ListBase/ListBase_class_A01_t02: Slow, Pass
+LibTest/collection/ListBase/ListBase_class_A01_t03: Slow, Pass
+LibTest/collection/ListMixin/ListMixin_class_A01_t02: Slow, Pass
+LibTest/collection/ListMixin/ListMixin_class_A01_t03: Slow, Pass
+LibTest/core/List/List_class_A01_t02: Slow, Pass
+LibTest/core/List/List_class_A01_t03: Slow, Pass
 
 [ $runtime != vm && ($compiler == dartk || $compiler == dartkb) ]
 Language/Classes/Constructors/Constant_Constructors/potentially_constant_expression_t01: Crash
diff --git a/tests/compiler/dart2js/analyses/api_allowed.json b/tests/compiler/dart2js/analyses/api_allowed.json
index 062db80..4a05aa5 100644
--- a/tests/compiler/dart2js/analyses/api_allowed.json
+++ b/tests/compiler/dart2js/analyses/api_allowed.json
@@ -87,7 +87,7 @@
     "Dynamic access of 'firstChild'.": 2,
     "Dynamic invocation of 'append'.": 1,
     "Dynamic access of 'tagName'.": 2,
-    "Dynamic invocation of 'call'.": 1,
+    "Dynamic invocation of 'call'.": 2,
     "Dynamic invocation of 'dart.dom.html::_initKeyboardEvent'.": 1,
     "Dynamic access of 'attributes'.": 1,
     "Dynamic invocation of '[]'.": 1,
@@ -225,4 +225,4 @@
     "Dynamic access of 'port'.": 1,
     "Dynamic invocation of 'dart._http::_toJSON'.": 1
   }
-}
\ No newline at end of file
+}
diff --git a/tests/compiler/dart2js/analyses/dart2js_allowed.json b/tests/compiler/dart2js/analyses/dart2js_allowed.json
index 8881b99..7f57a19 100644
--- a/tests/compiler/dart2js/analyses/dart2js_allowed.json
+++ b/tests/compiler/dart2js/analyses/dart2js_allowed.json
@@ -187,14 +187,11 @@
     "Dynamic access of 'universe.side_effects::_flags'.": 1
   },
   "pkg/compiler/lib/src/ssa/builder_kernel.dart": {
-    "Dynamic update to 'instantiatedTypes'.": 1,
-    "Dynamic update to 'sideEffects'.": 1,
     "Dynamic access of 'name'.": 1,
     "Dynamic access of 'id'.": 1,
     "Dynamic invocation of 'addSuccessor'.": 1
   },
   "pkg/compiler/lib/src/ssa/types.dart": {
-    "Dynamic access of 'isTop'.": 1,
     "Dynamic access of 'element'.": 1
   },
   "pkg/compiler/lib/src/js_emitter/program_builder/program_builder.dart": {
diff --git a/tests/compiler/dart2js/dart2js.status b/tests/compiler/dart2js/dart2js.status
index 28c1f67..c5b7400 100644
--- a/tests/compiler/dart2js/dart2js.status
+++ b/tests/compiler/dart2js/dart2js.status
@@ -2,59 +2,59 @@
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
-analyses/analyze_test: Slow
-analyses/api_dynamic_test: Slow
-analyses/dart2js_dynamic_test: Slow
-closure/closure_test: Slow
-codegen/load_elimination_test: Slow
-codegen/model_test: Slow
-deferred_loading/deferred_loading_test: Slow
-end_to_end/dump_info_test: Slow
-equivalence/id_equivalence1_test: Slow
-equivalence/id_equivalence2_test: Slow
-impact/impact_test: Slow
-inference/inference0_test: Slow
-inference/inference1_test: Slow
-inference/inference2_test: Slow
-inference/inference3_test: Slow
-inference/swarm_test: Slow #
-inlining/inlining_test: Slow
-model/native_test: Slow
-model/no_such_method_enabled_test: Slow
-model/subtype_test: Slow
-modular/*: Slow
+analyses/analyze_test: Slow, Pass
+analyses/api_dynamic_test: Slow, Pass
+analyses/dart2js_dynamic_test: Slow, Pass
+closure/closure_test: Slow, Pass
+codegen/load_elimination_test: Slow, Pass
+codegen/model_test: Slow, Pass
+deferred_loading/deferred_loading_test: Slow, Pass
+end_to_end/dump_info_test: Slow, Pass
+equivalence/id_equivalence1_test: Slow, Pass
+equivalence/id_equivalence2_test: Slow, Pass
+impact/impact_test: Slow, Pass
+inference/inference0_test: Slow, Pass
+inference/inference1_test: Slow, Pass
+inference/inference2_test: Slow, Pass
+inference/inference3_test: Slow, Pass
+inference/swarm_test: Slow, Pass #
+inlining/inlining_test: Slow, Pass
+model/native_test: Slow, Pass
+model/no_such_method_enabled_test: Slow, Pass
+model/subtype_test: Slow, Pass
+modular/*: Slow, Pass
 packages/*: Skip # Skip packages folder
-rti/rti_emission_test: Slow
-rti/rti_need0_test: Slow
-rti/rti_need1_test: Slow
-serialization/serialization_test: Slow
-sourcemaps/source_mapping_invokes_test: Slow
-sourcemaps/source_mapping_operators_test: Slow
-sourcemaps/source_mapping_test: Slow
-sourcemaps/stacktrace_test: Slow
+rti/rti_emission_test: Slow, Pass
+rti/rti_need0_test: Slow, Pass
+rti/rti_need1_test: Slow, Pass
+serialization/serialization_test: Slow, Pass
+sourcemaps/source_mapping_invokes_test: Slow, Pass
+sourcemaps/source_mapping_operators_test: Slow, Pass
+sourcemaps/source_mapping_test: Slow, Pass
+sourcemaps/stacktrace_test: Slow, Pass
 
 [ $mode == debug ]
-deferred/load_graph_segmentation_test: Slow
-deferred/load_mapping_test: Slow
-end_to_end/dart2js_batch_test: Slow
-end_to_end/exit_code_test: Slow
-end_to_end/in_user_code_test: Slow
-end_to_end/show_package_warnings_test: Slow
+deferred/load_graph_segmentation_test: Slow, Pass
+deferred/load_mapping_test: Slow, Pass
+end_to_end/dart2js_batch_test: Slow, Pass
+end_to_end/exit_code_test: Slow, Pass
+end_to_end/in_user_code_test: Slow, Pass
+end_to_end/show_package_warnings_test: Slow, Pass
 
 [ $checked ]
-codegen/value_range_kernel_test: Slow
-codegen/value_range_test: Slow
-end_to_end/exit_code_test: Slow
-end_to_end/output_type_test: Slow
-end_to_end/uri_retention_test: Slow
-jsinterop/declaration_test: Slow
-jsinterop/interop_anonymous_unreachable_test: Slow
-jsinterop/world_test: Slow
-sourcemaps/stacktrace_test: Slow
+codegen/value_range_kernel_test: Slow, Pass
+codegen/value_range_test: Slow, Pass
+end_to_end/exit_code_test: Slow, Pass
+end_to_end/output_type_test: Slow, Pass
+end_to_end/uri_retention_test: Slow, Pass
+jsinterop/declaration_test: Slow, Pass
+jsinterop/interop_anonymous_unreachable_test: Slow, Pass
+jsinterop/world_test: Slow, Pass
+sourcemaps/stacktrace_test: Slow, Pass
 
 [ !$checked ]
 end_to_end/exit_code_test: Skip # This tests requires checked mode.
-jsinterop/declaration_test: Slow
+jsinterop/declaration_test: Slow, Pass
 
 [ $runtime == chrome || $runtime == ff || $runtime == firefox || $runtime == safari || $jscl ]
 *: Skip # dart2js uses #import('dart:io'); and it is not self-hosted (yet).
diff --git a/tests/compiler/dart2js/deferred/constant_emission_test_helper.dart b/tests/compiler/dart2js/deferred/constant_emission_test_helper.dart
index 1d4fd35..7f8b97e 100644
--- a/tests/compiler/dart2js/deferred/constant_emission_test_helper.dart
+++ b/tests/compiler/dart2js/deferred/constant_emission_test_helper.dart
@@ -10,6 +10,7 @@
 import 'package:compiler/src/constants/values.dart';
 import 'package:compiler/src/deferred_load.dart';
 import 'package:compiler/src/elements/entities.dart';
+import 'package:compiler/src/elements/types.dart';
 import 'package:compiler/src/js_emitter/model.dart';
 import 'package:compiler/src/util/util.dart';
 import 'package:expect/expect.dart';
@@ -31,6 +32,7 @@
   CompilationResult result = await runCompiler(
       memorySourceFiles: sourceFiles, outputProvider: collector);
   Compiler compiler = result.compiler;
+  DartTypes dartTypes = compiler.frontendStrategy.commonElements.dartTypes;
   ProgramLookup lookup = new ProgramLookup(compiler.backendStrategy);
   var closedWorld = compiler.backendClosedWorldForTesting;
   var elementEnvironment = closedWorld.elementEnvironment;
@@ -59,7 +61,7 @@
 
   void processFragment(String fragmentName, Fragment fragment) {
     for (Constant constant in fragment.constants) {
-      String text = constant.value.toStructuredText();
+      String text = constant.value.toStructuredText(dartTypes);
       Set<String> expectedConstantUnit = expectedOutputUnits[text];
       if (expectedConstantUnit == null) {
         if (constant.value is DeferredGlobalConstantValue) {
diff --git a/tests/compiler/dart2js/deferred/follow_constant_dependencies_test.dart b/tests/compiler/dart2js/deferred/follow_constant_dependencies_test.dart
index 971c524..e4b5593 100644
--- a/tests/compiler/dart2js/deferred/follow_constant_dependencies_test.dart
+++ b/tests/compiler/dart2js/deferred/follow_constant_dependencies_test.dart
@@ -7,6 +7,7 @@
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/constants/values.dart';
+import 'package:compiler/src/elements/types.dart';
 import 'package:expect/expect.dart';
 import '../helpers/memory_compiler.dart';
 
@@ -16,6 +17,7 @@
         await runCompiler(memorySourceFiles: MEMORY_SOURCE_FILES);
 
     Compiler compiler = result.compiler;
+    DartTypes dartTypes = compiler.frontendStrategy.commonElements.dartTypes;
     var closedWorld = compiler.backendClosedWorldForTesting;
     var outputUnitForConstant =
         closedWorld.outputUnitData.outputUnitForConstant;
@@ -35,12 +37,15 @@
           allConstants.firstWhere((dynamic constant) {
         return constant.isString && constant.stringValue == stringValue;
       });
-      Expect.notEquals(null, outputUnitForConstant(constant),
-          "Constant value ${constant.toStructuredText()} has no output unit.");
+      Expect.notEquals(
+          null,
+          outputUnitForConstant(constant),
+          "Constant value ${constant.toStructuredText(dartTypes)} has no "
+          "output unit.");
       Expect.notEquals(
           mainOutputUnit,
           outputUnitForConstant(constant),
-          "Constant value ${constant.toStructuredText()} "
+          "Constant value ${constant.toStructuredText(dartTypes)} "
           "is in the main output unit.");
     }
   }
diff --git a/tests/compiler/dart2js/deferred_loading/deferred_loading_test.dart b/tests/compiler/dart2js/deferred_loading/deferred_loading_test.dart
index 78462c7..fc041f3 100644
--- a/tests/compiler/dart2js/deferred_loading/deferred_loading_test.dart
+++ b/tests/compiler/dart2js/deferred_loading/deferred_loading_test.dart
@@ -175,7 +175,7 @@
   visitConstantExpression(ir.ConstantExpression node) {
     ConstantValue constant = _elementMap.getConstantValue(null, node);
     if (!constant.isPrimitive) {
-      _constants.add('${constant.toStructuredText()}='
+      _constants.add('${constant.toStructuredText(_elementMap.types)}='
           '${outputUnitString(_data.outputUnitForConstant(constant))}');
     }
     return super.visitConstantExpression(node);
diff --git a/tests/compiler/dart2js/field_analysis/jfield_analysis_test.dart b/tests/compiler/dart2js/field_analysis/jfield_analysis_test.dart
index 159134e..55f3014 100644
--- a/tests/compiler/dart2js/field_analysis/jfield_analysis_test.dart
+++ b/tests/compiler/dart2js/field_analysis/jfield_analysis_test.dart
@@ -7,6 +7,7 @@
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/elements/entities.dart';
+import 'package:compiler/src/elements/types.dart';
 import 'package:compiler/src/js_backend/field_analysis.dart';
 import 'package:compiler/src/js_model/js_world.dart';
 import 'package:kernel/ast.dart' as ir;
@@ -40,6 +41,7 @@
       Map<Id, ActualData<Features>> actualMap,
       {bool verbose: false}) {
     if (member.isField) {
+      DartTypes dartTypes = compiler.frontendStrategy.commonElements.dartTypes;
       JsClosedWorld closedWorld = compiler.backendClosedWorldForTesting;
       JFieldAnalysis fieldAnalysis = closedWorld.fieldAnalysis;
       ir.Member node = closedWorld.elementMap.getMemberDefinition(member).node;
@@ -53,9 +55,10 @@
       }
       if (fieldData.isEffectivelyConstant) {
         features[Tags.constantValue] =
-            fieldData.constantValue.toStructuredText();
+            fieldData.constantValue.toStructuredText(dartTypes);
       } else if (fieldData.initialValue != null) {
-        features[Tags.initialValue] = fieldData.initialValue.toStructuredText();
+        features[Tags.initialValue] =
+            fieldData.initialValue.toStructuredText(dartTypes);
       } else if (fieldData.isEager) {
         if (fieldData.eagerCreationIndex != null) {
           features[Tags.eagerCreationIndex] =
diff --git a/tests/compiler/dart2js/field_analysis/kfield_analysis_test.dart b/tests/compiler/dart2js/field_analysis/kfield_analysis_test.dart
index 4d53430..7e3d8de 100644
--- a/tests/compiler/dart2js/field_analysis/kfield_analysis_test.dart
+++ b/tests/compiler/dart2js/field_analysis/kfield_analysis_test.dart
@@ -7,6 +7,7 @@
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/elements/entities.dart';
+import 'package:compiler/src/elements/types.dart';
 import 'package:compiler/src/js_backend/field_analysis.dart';
 import 'package:compiler/src/kernel/kernel_strategy.dart';
 import 'package:kernel/ast.dart' as ir;
@@ -35,6 +36,7 @@
       {bool verbose: false}) {
     if (member.isField) {
       KernelFrontendStrategy frontendStrategy = compiler.frontendStrategy;
+      DartTypes dartTypes = frontendStrategy.commonElements.dartTypes;
       KFieldAnalysis allocatorAnalysis =
           frontendStrategy.fieldAnalysisForTesting;
       ir.Member node = frontendStrategy.elementMap.getMemberNode(member);
@@ -44,11 +46,12 @@
             allocatorAnalysis.getAllocatorDataForTesting(member);
         if (data != null) {
           if (data.initialValue != null) {
-            features[Tags.initialValue] = data.initialValue.toStructuredText();
+            features[Tags.initialValue] =
+                data.initialValue.toStructuredText(dartTypes);
           }
           data.initializers.forEach((constructor, value) {
             features['${constructor.enclosingClass.name}.${constructor.name}'] =
-                value?.shortText;
+                value?.shortText(dartTypes);
           });
         }
       } else {
@@ -56,7 +59,7 @@
             allocatorAnalysis.getStaticFieldDataForTesting(member);
         if (staticFieldData.initialValue != null) {
           features[Tags.initialValue] =
-              staticFieldData.initialValue.toStructuredText();
+              staticFieldData.initialValue.toStructuredText(dartTypes);
         }
         features[Tags.complexity] = staticFieldData.complexity.shortText;
       }
diff --git a/tests/compiler/dart2js/helpers/shared_helper.dart b/tests/compiler/dart2js/helpers/shared_helper.dart
index ec3cc15..34b897b 100644
--- a/tests/compiler/dart2js/helpers/shared_helper.dart
+++ b/tests/compiler/dart2js/helpers/shared_helper.dart
@@ -6,9 +6,9 @@
 import 'package:compiler/src/elements/entities.dart';
 import 'package:compiler/src/elements/types.dart';
 
-String constantToText(ConstantValue constant) {
+String constantToText(DartTypes dartTypes, ConstantValue constant) {
   StringBuffer sb = new StringBuffer();
-  new ConstantToTextVisitor().visit(constant, sb);
+  new ConstantToTextVisitor(dartTypes).visit(constant, sb);
   return sb.toString();
 }
 
@@ -118,8 +118,11 @@
 
 class ConstantToTextVisitor
     implements ConstantValueVisitor<void, StringBuffer> {
+  final DartTypes _dartTypes;
   final DartTypeToTextVisitor typeToText = new DartTypeToTextVisitor();
 
+  ConstantToTextVisitor(this._dartTypes);
+
   void visit(ConstantValue constant, StringBuffer sb) =>
       constant.accept(this, sb);
 
@@ -224,33 +227,33 @@
   @override
   void visitInterceptor(InterceptorConstantValue constant, StringBuffer sb) {
     throw new UnsupportedError(
-        'Unsupported constant value: ${constant.toStructuredText()}');
+        'Unsupported constant value: ${constant.toStructuredText(_dartTypes)}');
   }
 
   @override
   void visitDummyInterceptor(
       DummyInterceptorConstantValue constant, StringBuffer sb) {
     throw new UnsupportedError(
-        'Unsupported constant value: ${constant.toStructuredText()}');
+        'Unsupported constant value: ${constant.toStructuredText(_dartTypes)}');
   }
 
   @override
   void visitUnreachable(UnreachableConstantValue constant, StringBuffer sb) {
     throw new UnsupportedError(
-        'Unsupported constant value: ${constant.toStructuredText()}');
+        'Unsupported constant value: ${constant.toStructuredText(_dartTypes)}');
   }
 
   @override
   void visitJsName(JsNameConstantValue constant, StringBuffer sb) {
     throw new UnsupportedError(
-        'Unsupported constant value: ${constant.toStructuredText()}');
+        'Unsupported constant value: ${constant.toStructuredText(_dartTypes)}');
   }
 
   @override
   void visitDeferredGlobal(
       DeferredGlobalConstantValue constant, StringBuffer sb) {
     throw new UnsupportedError(
-        'Unsupported constant value: ${constant.toStructuredText()}');
+        'Unsupported constant value: ${constant.toStructuredText(_dartTypes)}');
   }
 
   @override
diff --git a/tests/compiler/dart2js/model/cfe_constant_evaluation_test.dart b/tests/compiler/dart2js/model/cfe_constant_evaluation_test.dart
index 5a5e639..eddb490 100644
--- a/tests/compiler/dart2js/model/cfe_constant_evaluation_test.dart
+++ b/tests/compiler/dart2js/model/cfe_constant_evaluation_test.dart
@@ -13,6 +13,7 @@
 import 'package:compiler/src/constants/values.dart';
 import 'package:compiler/src/elements/entities.dart';
 import 'package:compiler/src/elements/indexed.dart';
+import 'package:compiler/src/elements/types.dart';
 import 'package:compiler/src/ir/constants.dart';
 import 'package:compiler/src/ir/visitors.dart';
 import 'package:compiler/src/kernel/kernel_strategy.dart';
@@ -576,6 +577,7 @@
     Compiler compiler = result.compiler;
     KernelFrontendStrategy frontEndStrategy = compiler.frontendStrategy;
     KernelToElementMapImpl elementMap = frontEndStrategy.elementMap;
+    DartTypes dartTypes = elementMap.types;
     ir.TypeEnvironment typeEnvironment = elementMap.typeEnvironment;
     KElementEnvironment elementEnvironment =
         compiler.frontendStrategy.elementEnvironment;
@@ -619,7 +621,7 @@
               "Expected non-null value from evaluation of "
               "`${data.code}`.");
 
-          String valueText = value.toStructuredText();
+          String valueText = value.toStructuredText(dartTypes);
           Expect.equals(
               expectedText,
               valueText,
diff --git a/tests/compiler/dart2js/model/cfe_constant_test.dart b/tests/compiler/dart2js/model/cfe_constant_test.dart
index d00a766..3f522df 100644
--- a/tests/compiler/dart2js/model/cfe_constant_test.dart
+++ b/tests/compiler/dart2js/model/cfe_constant_test.dart
@@ -85,8 +85,10 @@
   @override
   String computeNodeValue(Id id, ir.TreeNode node) {
     if (node is ir.ConstantExpression) {
-      return constantToText(elementMap.getConstantValue(
-          elementMap.getStaticTypeContext(member), node));
+      return constantToText(
+          elementMap.types,
+          elementMap.getConstantValue(
+              elementMap.getStaticTypeContext(member), node));
     }
     return null;
   }
diff --git a/tests/compiler/dart2js/rti/type_representation_test.dart b/tests/compiler/dart2js/rti/type_representation_test.dart
index e1c2e07..7cae429 100644
--- a/tests/compiler/dart2js/rti/type_representation_test.dart
+++ b/tests/compiler/dart2js/rti/type_representation_test.dart
@@ -70,7 +70,9 @@
   RuntimeTypeTags rtiTags = const RuntimeTypeTags();
   TypeRepresentationGenerator typeRepresentation =
       new TypeRepresentationGenerator(
-          rtiTags, compiler.backendClosedWorldForTesting.nativeData);
+          compiler.frontendStrategy.commonElements.dartTypes,
+          rtiTags,
+          compiler.backendClosedWorldForTesting.nativeData);
 
   Expression onVariable(TypeVariableType _variable) {
     TypeVariableType variable = _variable;
diff --git a/tests/compiler/dart2js_extra/dart2js_extra.status b/tests/compiler/dart2js_extra/dart2js_extra.status
index 29be72f..9faa92a 100644
--- a/tests/compiler/dart2js_extra/dart2js_extra.status
+++ b/tests/compiler/dart2js_extra/dart2js_extra.status
@@ -13,26 +13,26 @@
 string_interpolation_test: Skip
 
 [ $compiler == dart2js && $runtime == chrome && $system == windows ]
-class_test: Slow # Issue 25940
-closure_capture3_test: Slow # Issue 25940
-closure_capture5_test: Slow # Issue 25940
-conditional_test: Slow # Issue 25940
-consistent_codeUnitAt_error_test: Slow # Issue 25940
-constant_javascript_semantics2_test: Slow # Issue 25940
-deferred_split_test: Slow # Issue 25940
+class_test: Slow, Pass # Issue 25940
+closure_capture3_test: Slow, Pass # Issue 25940
+closure_capture5_test: Slow, Pass # Issue 25940
+conditional_test: Slow, Pass # Issue 25940
+consistent_codeUnitAt_error_test: Slow, Pass # Issue 25940
+constant_javascript_semantics2_test: Slow, Pass # Issue 25940
+deferred_split_test: Slow, Pass # Issue 25940
 
 [ $compiler == dart2js && $runtime == chrome && $csp ]
 deferred/load_in_correct_order_test: SkipByDesign # Purposely uses `eval`
 
 [ $compiler == dart2js && $runtime == ff && $system == windows ]
-consistent_index_error_string_test: Slow # Issue 25940
+consistent_index_error_string_test: Slow, Pass # Issue 25940
 
 [ $compiler == dart2js && $csp ]
 deferred_custom_loader_test: SkipByDesign # Issue 25683
 deferred_fail_and_retry_test: SkipByDesign # Uses eval to simulate failed loading.
 
 [ $compiler == dart2js && !$host_checked ]
-dummy_compiler_test: Slow # Issue 32439. self-hosting doesn't work with CFE yet.
+dummy_compiler_test: Slow, Pass # Issue 32439. self-hosting doesn't work with CFE yet.
 
 [ $compiler == dart2js && $minified ]
 code_motion_exception_test: Skip # Requires unminified operator names.
diff --git a/tests/compiler/dart2js_extra/regress_40349_test.dart b/tests/compiler/dart2js_extra/regress_40349_test.dart
new file mode 100644
index 0000000..796688d
--- /dev/null
+++ b/tests/compiler/dart2js_extra/regress_40349_test.dart
@@ -0,0 +1,43 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Regression test for Issue #40349:
+///
+/// Before the fix, this code was accidentally generating a type check twice.
+/// In between the two checks, code to update `_foo` was overriding a temporary
+/// variable used by the check subexpression, which made the code for the
+/// second check invalid.
+///
+/// The second check should not have been generated, but it was emitted due to
+/// a broken invariant of the SSA generate-at-use logic.
+
+void main() {
+  // `x` which is used multiple times after inilining, so a temporary is used.
+  x.method(40);
+}
+
+dynamic x = Wrapper<int>();
+
+class A<E> {
+  int _foo = 0;
+  List<E> list = [null];
+
+  @pragma('dart2js:tryInline')
+  void internalMethod(E value) {
+    // The update and use of `_foo` requires a separate temporary which reuses
+    // the same variable given to `x` (technically `x` is no longer live).
+    _foo = (_foo + 1) & 0;
+
+    // This use of `value` accidentally contains the second check, which
+    // still refers to the temporary assuming it was `x` and not `_foo`.
+    list[_foo] = value;
+  }
+}
+
+class Wrapper<T> {
+  A<T> a = A<T>();
+
+  @pragma('dart2js:tryInline')
+  method(T t) => a.internalMethod(t);
+}
diff --git a/tests/compiler/dart2js_extra/rti/subtype_utils.dart b/tests/compiler/dart2js_extra/rti/subtype_utils.dart
index f147dc7..dc4f608 100644
--- a/tests/compiler/dart2js_extra/rti/subtype_utils.dart
+++ b/tests/compiler/dart2js_extra/rti/subtype_utils.dart
@@ -12,23 +12,20 @@
 void strictSubtype(String s, String t) {
   var sRti = rti.testingUniverseEval(universe, s);
   var tRti = rti.testingUniverseEval(universe, t);
-  Expect.isTrue(rti.testingIsLegacySubtype(universe, sRti, tRti), reason(s, t));
-  Expect.isFalse(
-      rti.testingIsLegacySubtype(universe, tRti, sRti), reason(t, s));
+  Expect.isTrue(rti.testingIsSubtype(universe, sRti, tRti), reason(s, t));
+  Expect.isFalse(rti.testingIsSubtype(universe, tRti, sRti), reason(t, s));
 }
 
 void unrelated(String s, String t) {
   var sRti = rti.testingUniverseEval(universe, s);
   var tRti = rti.testingUniverseEval(universe, t);
-  Expect.isFalse(
-      rti.testingIsLegacySubtype(universe, sRti, tRti), reason(s, t));
-  Expect.isFalse(
-      rti.testingIsLegacySubtype(universe, tRti, sRti), reason(t, s));
+  Expect.isFalse(rti.testingIsSubtype(universe, sRti, tRti), reason(s, t));
+  Expect.isFalse(rti.testingIsSubtype(universe, tRti, sRti), reason(t, s));
 }
 
 void equivalent(String s, String t) {
   var sRti = rti.testingUniverseEval(universe, s);
   var tRti = rti.testingUniverseEval(universe, t);
-  Expect.isTrue(rti.testingIsLegacySubtype(universe, sRti, tRti), reason(s, t));
-  Expect.isTrue(rti.testingIsLegacySubtype(universe, tRti, sRti), reason(t, s));
+  Expect.isTrue(rti.testingIsSubtype(universe, sRti, tRti), reason(s, t));
+  Expect.isTrue(rti.testingIsSubtype(universe, tRti, sRti), reason(t, s));
 }
diff --git a/tests/compiler/dartdevc_native/js_interop_test.dart b/tests/compiler/dartdevc_native/js_interop_test.dart
index f80896d..4303dfc 100644
--- a/tests/compiler/dartdevc_native/js_interop_test.dart
+++ b/tests/compiler/dartdevc_native/js_interop_test.dart
@@ -5,10 +5,12 @@
 @JS()
 library js_interop_test;
 
-import 'package:expect/expect.dart';
-import 'package:js/js.dart';
 import 'dart:_foreign_helper' as helper show JS;
 import 'dart:_runtime' as dart;
+import 'dart:js' show context;
+
+import 'package:expect/expect.dart';
+import 'package:js/js.dart';
 
 @JS()
 class Console {
@@ -38,6 +40,7 @@
 
 @JS()
 class SomeClass {
+  external factory SomeClass(String Function() f);
   external set jsFunctionFieldSetter(String Function() f);
   external void Function(String Function() f) get jsFunctionFieldGetter;
   external String jsInstanceMethod(String Function() f);
@@ -46,7 +49,9 @@
 }
 
 @JS()
+@anonymous
 class NestedJs {
+  external factory NestedJs({String Function() constructorArg});
   external String get stringField;
 }
 
@@ -72,8 +77,6 @@
 
   final Function localNonNullLegacy = () => 'hello';
   final String Function() localNonNull = () => 'hello';
-  //final Function? localNullableLegacy = () => 'hello';
-  //final String Function()? localNullable = () => 'hello';
 
   // Assigment to JS static field.
   Expect.throws(() {
@@ -88,12 +91,6 @@
   Expect.throws(() {
     _jsStaticVariable = localNonNull;
   });
-  //Expect.throws(() {
-  //  _jsStaticVariable = localNullableLegacy;
-  //});
-  //Expect.throws(() {
-  //  _jsStaticVariable = localNullable;
-  //});
   _jsStaticVariable = allowInterop(dartStaticMethod);
   _jsStaticVariable = wrappedDartStaticMethod;
 
@@ -112,12 +109,6 @@
   Expect.throws(() {
     jsStaticFunction(localNonNull);
   });
-  //Expect.throws(() {
-  //  jsStaticFunction(localNullableLegacy);
-  //});
-  //Expect.throws(() {
-  //  jsStaticFunction(localNullable);
-  //});
   jsStaticFunction(allowInterop(() => 'hello'));
   jsStaticFunction(wrappedDartStaticMethod);
 
@@ -135,12 +126,6 @@
   Expect.throws(() {
     method(localNonNull);
   });
-  //Expect.throws(() {
-  //  method(localNullableLegacy);
-  //});
-  //Expect.throws(() {
-  //  method(localNullable);
-  //});
   method(allowInterop(() => 'hello'));
   method(wrappedDartStaticMethod);
 
@@ -162,12 +147,6 @@
   Expect.throws((() {
     someClass.jsFunctionFieldSetter = localNonNull;
   }));
-  //Expect.throws((() {
-  //  someClass.jsFunctionFieldSetter = localNullableLegacy;
-  //}));
-  //Expect.throws((() {
-  //  someClass.jsFunctionFieldSetter = localNullable;
-  //}));
   someClass.jsFunctionFieldSetter = allowInterop(() => 'hello');
   someClass.jsFunctionFieldSetter = wrappedDartStaticMethod;
 
@@ -184,15 +163,42 @@
   Expect.throws(() {
     someClass.jsInstanceMethod(localNonNull);
   });
-  //Expect.throws(() {
-  //  someClass.jsInstanceMethod(localNullableLegacy);
-  //});
-  //Expect.throws(() {
-  //  someClass.jsInstanceMethod(localNullable);
-  //});
   someClass.jsInstanceMethod(allowInterop(() => 'hello'));
   someClass.jsInstanceMethod(wrappedDartStaticMethod);
 
+  // Argument to  constructor.
+  context.callMethod('eval', ['function SomeClass(a) { a(); }']);
+  Expect.throws(() {
+    SomeClass(() => 'hello');
+  });
+  Expect.throws(() {
+    SomeClass(dartStaticMethod);
+  });
+  Expect.throws(() {
+    SomeClass(localNonNullLegacy);
+  });
+  Expect.throws(() {
+    SomeClass(localNonNull);
+  });
+  SomeClass(allowInterop(() => 'hello'));
+  SomeClass(wrappedDartStaticMethod);
+
+  // Argument to anonymous constructor.
+  Expect.throws(() {
+    NestedJs(constructorArg: () => 'hello');
+  });
+  Expect.throws(() {
+    NestedJs(constructorArg: dartStaticMethod);
+  });
+  Expect.throws(() {
+    NestedJs(constructorArg: localNonNullLegacy);
+  });
+  Expect.throws(() {
+    NestedJs(constructorArg: localNonNull);
+  });
+  NestedJs(constructorArg: allowInterop(() => 'hello'));
+  NestedJs(constructorArg: wrappedDartStaticMethod);
+
   // Argument to torn off instance method.
   method = someClass.jsInstanceMethod;
   Expect.throws(() {
@@ -207,12 +213,6 @@
   Expect.throws(() {
     method(localNonNull);
   });
-  //Expect.throws(() {
-  //  method(localNullableLegacy);
-  //});
-  //Expect.throws(() {
-  //  method(localNullable);
-  //});
   method(allowInterop(() => 'hello'));
   method(wrappedDartStaticMethod);
 
@@ -229,12 +229,6 @@
   Expect.throws(() {
     someClass.jsFunctionFieldGetter(localNonNull);
   });
-  //Expect.throws(() {
-  //  someClass.jsFunctionFieldGetter(localNullableLegacy);
-  //});
-  //Expect.throws(() {
-  //  someClass.jsFunctionFieldGetter(localNullable);
-  //});
   someClass.jsFunctionFieldGetter(allowInterop(() => 'hello'));
   someClass.jsFunctionFieldGetter(wrappedDartStaticMethod);
 
@@ -256,12 +250,6 @@
   //Expect.throws(() {
   //  method(localNonNull);
   //});
-  //Expect.throws(() {
-  //  method(localNullableLegacy);
-  //});
-  //Expect.throws(() {
-  //  method(localNullable);
-  //});
   method(allowInterop(() => 'hello'));
   method(wrappedDartStaticMethod);
 
diff --git a/tests/compiler/dartdevc_native/nnbd_js_interop_test.dart b/tests/compiler/dartdevc_native/nnbd_js_interop_test.dart
new file mode 100644
index 0000000..56ce33f
--- /dev/null
+++ b/tests/compiler/dartdevc_native/nnbd_js_interop_test.dart
@@ -0,0 +1,323 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+@JS()
+library js_interop_test;
+
+import 'dart:_foreign_helper' as helper show JS;
+import 'dart:_runtime' as dart;
+import 'dart:js' show context;
+
+import 'package:expect/expect.dart';
+import 'package:js/js.dart';
+
+// Requirements=nnbd
+
+@JS()
+class Console {
+  @JS()
+  external void log(arg);
+}
+
+@JS('console')
+external Console get console;
+
+@JS('console.log')
+external void log(String s);
+
+String dartStaticMethod() => 'hello';
+
+@JS('jsStaticVariable')
+external set _jsStaticVariable(Function f);
+
+@JS('jsStaticVariable')
+external void jsStaticVariable(String s);
+
+@JS('jsStaticFunction')
+external set _jsStaticFunction(Function f);
+
+@JS('jsStaticFunction')
+external void jsStaticFunction(String Function() f);
+
+@JS()
+class SomeClass {
+  external factory SomeClass(String Function() f);
+  external set jsFunctionFieldSetter(String Function() f);
+  external void Function(String Function() f) get jsFunctionFieldGetter;
+  external String jsInstanceMethod(String Function() f);
+
+  external NestedJs get jsNonFunctionField;
+}
+
+@JS()
+@anonymous
+class NestedJs {
+  external factory NestedJs({String Function() constructorArg});
+  external String get stringField;
+}
+
+@JS('someClass')
+external set _someClass(dynamic s);
+@JS('someClass')
+external SomeClass get someClass;
+
+void main() {
+  Function(String) jsFunc = helper.JS('', '(x) => {}');
+  Expect.equals(dart.assertInterop(jsFunc), jsFunc);
+
+  Expect.equals(dart.assertInterop(log), log);
+  Expect.equals(dart.assertInterop(console.log), console.log);
+  Expect.throws(() => dart.assertInterop(dartStaticMethod));
+
+  Expect.isNull(jsStaticVariable);
+  _jsStaticVariable = jsFunc;
+  Expect.isNotNull(jsStaticVariable);
+  Expect.equals(dart.assertInterop(jsStaticVariable), jsStaticVariable);
+
+  final dynamic wrappedDartStaticMethod = allowInterop(dartStaticMethod);
+
+  final Function localNonNullLegacy = () => 'hello';
+  final String Function() localNonNull = () => 'hello';
+  final Function? localNullableLegacy = () => 'hello';
+  final String Function()? localNullable = () => 'hello';
+
+  // Assigment to JS static field.
+  Expect.throws(() {
+    _jsStaticVariable = () => 'hello';
+  });
+  Expect.throws(() {
+    _jsStaticVariable = dartStaticMethod;
+  });
+  Expect.throws(() {
+    _jsStaticVariable = localNonNullLegacy;
+  });
+  Expect.throws(() {
+    _jsStaticVariable = localNonNull;
+  });
+  Expect.throws(() {
+    _jsStaticVariable = localNullableLegacy;
+  });
+  Expect.throws(() {
+    _jsStaticVariable = localNullable;
+  });
+  _jsStaticVariable = allowInterop(dartStaticMethod);
+  _jsStaticVariable = wrappedDartStaticMethod;
+
+  // Argument to static JS function.
+  Function(Function(String), String) jsFunc2 = helper.JS('', '(f) => f()');
+  _jsStaticFunction = jsFunc2;
+  Expect.throws(() {
+    jsStaticFunction(() => 'hello');
+  });
+  Expect.throws(() {
+    jsStaticFunction(dartStaticMethod);
+  });
+  Expect.throws(() {
+    jsStaticFunction(localNonNullLegacy);
+  });
+  Expect.throws(() {
+    jsStaticFunction(localNonNull);
+  });
+  Expect.throws(() {
+    jsStaticFunction(localNullableLegacy);
+  });
+  Expect.throws(() {
+    jsStaticFunction(localNullable);
+  });
+  jsStaticFunction(allowInterop(() => 'hello'));
+  jsStaticFunction(wrappedDartStaticMethod);
+
+  // Argument to torn off static JS function
+  dynamic method = jsStaticFunction;
+  Expect.throws(() {
+    method(() => 'hello');
+  });
+  Expect.throws(() {
+    method(dartStaticMethod);
+  });
+  Expect.throws(() {
+    method(localNonNullLegacy);
+  });
+  Expect.throws(() {
+    method(localNonNull);
+  });
+  Expect.throws(() {
+    method(localNullableLegacy);
+  });
+  Expect.throws(() {
+    method(localNullable);
+  });
+  method(allowInterop(() => 'hello'));
+  method(wrappedDartStaticMethod);
+
+  // Assignment to instance field.
+  _someClass = helper.JS(
+      '',
+      '{"jsInstanceMethod": function(f) {return f();}, '
+          '"jsNonFunctionField": {"stringField":"hello js"}, '
+          '"jsFunctionFieldGetter": function(f) {return f();}}');
+  Expect.throws((() {
+    someClass.jsFunctionFieldSetter = () => 'hello';
+  }));
+  Expect.throws((() {
+    someClass.jsFunctionFieldSetter = dartStaticMethod;
+  }));
+  Expect.throws((() {
+    someClass.jsFunctionFieldSetter = localNonNullLegacy;
+  }));
+  Expect.throws((() {
+    someClass.jsFunctionFieldSetter = localNonNull;
+  }));
+  Expect.throws((() {
+    someClass.jsFunctionFieldSetter = localNullableLegacy;
+  }));
+  Expect.throws((() {
+    someClass.jsFunctionFieldSetter = localNullable;
+  }));
+  someClass.jsFunctionFieldSetter = allowInterop(() => 'hello');
+  someClass.jsFunctionFieldSetter = wrappedDartStaticMethod;
+
+  // Argument to instance method.
+  Expect.throws(() {
+    someClass.jsInstanceMethod(() => 'hello');
+  });
+  Expect.throws(() {
+    someClass.jsInstanceMethod(dartStaticMethod);
+  });
+  Expect.throws(() {
+    someClass.jsInstanceMethod(localNonNullLegacy);
+  });
+  Expect.throws(() {
+    someClass.jsInstanceMethod(localNonNull);
+  });
+  Expect.throws(() {
+    someClass.jsInstanceMethod(localNullableLegacy);
+  });
+  Expect.throws(() {
+    someClass.jsInstanceMethod(localNullable);
+  });
+  someClass.jsInstanceMethod(allowInterop(() => 'hello'));
+  someClass.jsInstanceMethod(wrappedDartStaticMethod);
+
+  // Argument to  constructor.
+  context.callMethod('eval', ['function SomeClass(a) { a(); }']);
+  Expect.throws(() {
+    SomeClass(() => 'hello');
+  });
+  Expect.throws(() {
+    SomeClass(dartStaticMethod);
+  });
+  Expect.throws(() {
+    SomeClass(localNonNullLegacy);
+  });
+  Expect.throws(() {
+    SomeClass(localNonNull);
+  });
+  Expect.throws(() {
+    SomeClass(localNullableLegacy);
+  });
+  Expect.throws(() {
+    SomeClass(localNullable);
+  });
+  SomeClass(allowInterop(() => 'hello'));
+  SomeClass(wrappedDartStaticMethod);
+
+  // Argument to anonymous constructor.
+  Expect.throws(() {
+    NestedJs(constructorArg: () => 'hello');
+  });
+  Expect.throws(() {
+    NestedJs(constructorArg: dartStaticMethod);
+  });
+  Expect.throws(() {
+    NestedJs(constructorArg: localNonNullLegacy);
+  });
+  Expect.throws(() {
+    NestedJs(constructorArg: localNonNull);
+  });
+  Expect.throws(() {
+    NestedJs(constructorArg: localNullableLegacy);
+  });
+  Expect.throws(() {
+    NestedJs(constructorArg: localNullable);
+  });
+  NestedJs(constructorArg: allowInterop(() => 'hello'));
+  NestedJs(constructorArg: wrappedDartStaticMethod);
+
+  // Argument to torn off instance method.
+  method = someClass.jsInstanceMethod;
+  Expect.throws(() {
+    method(() => 'hello');
+  });
+  Expect.throws(() {
+    method(dartStaticMethod);
+  });
+  Expect.throws(() {
+    method(localNonNullLegacy);
+  });
+  Expect.throws(() {
+    method(localNonNull);
+  });
+  Expect.throws(() {
+    method(localNullableLegacy);
+  });
+  Expect.throws(() {
+    method(localNullable);
+  });
+  method(allowInterop(() => 'hello'));
+  method(wrappedDartStaticMethod);
+
+  // Function typed getter
+  Expect.throws(() {
+    someClass.jsFunctionFieldGetter(() => 'hello');
+  });
+  Expect.throws(() {
+    someClass.jsFunctionFieldGetter(dartStaticMethod);
+  });
+  Expect.throws(() {
+    someClass.jsFunctionFieldGetter(localNonNullLegacy);
+  });
+  Expect.throws(() {
+    someClass.jsFunctionFieldGetter(localNonNull);
+  });
+  Expect.throws(() {
+    someClass.jsFunctionFieldGetter(localNullableLegacy);
+  });
+  Expect.throws(() {
+    someClass.jsFunctionFieldGetter(localNullable);
+  });
+  someClass.jsFunctionFieldGetter(allowInterop(() => 'hello'));
+  someClass.jsFunctionFieldGetter(wrappedDartStaticMethod);
+
+  // Stored Function typed getter
+  method = someClass.jsFunctionFieldGetter;
+  // We lose safety after calling a getter that returns a function, which takes
+  // a function as an argument. Since this can be modeled with a method, isntead
+  // of a getter returning a function, we don't expect this is a pattern likely
+  // to show up in real code.
+  //Expect.throws(() {
+  //  method(() => 'hello');
+  //});
+  //Expect.throws(() {
+  //  method(dartStaticMethod);
+  //});
+  //Expect.throws(() {
+  //  method(localNonNullLegacy);
+  //});
+  //Expect.throws(() {
+  //  method(localNonNull);
+  //});
+  //Expect.throws(() {
+  //  method(localNullableLegacy);
+  //});
+  //Expect.throws(() {
+  //  method(localNullable);
+  //});
+  method(allowInterop(() => 'hello'));
+  method(wrappedDartStaticMethod);
+
+  // Non-function fields
+  Expect.equals('hello js', someClass.jsNonFunctionField.stringField,
+      'Does not wrap access to a field');
+}
diff --git a/tests/corelib/corelib.status b/tests/corelib/corelib.status
index 834728b..e13f379 100644
--- a/tests/corelib/corelib.status
+++ b/tests/corelib/corelib.status
@@ -6,7 +6,7 @@
 regexp/lookbehind_test/01: Skip # Flaky in uncatchable way.  Issue 36280
 
 [ $mode == debug ]
-regexp/pcre_test: Slow # Issue 22008
+regexp/pcre_test: Slow, Pass # Issue 22008
 
 [ $arch == x64 && $system == windows ]
 stopwatch_test: Skip # Flaky test due to expected performance behaviour.
@@ -22,7 +22,7 @@
 bigint_js_test: SkipByDesign # JavaScript-specific test
 
 [ $compiler == dart2js && $runtime != none ]
-regexp/pcre_test: Slow # Issue 21593
+regexp/pcre_test: Slow, Pass # Issue 21593
 
 # We no longer expect Dart2 tests to run with the standalone VM without the new
 # common front end, but for now we get better coverage by still running them in
@@ -43,19 +43,19 @@
 bigint_test/15: SkipSlow # modPow is very slow
 int_parse_with_limited_ints_test: Skip # Requires fixed-size int64 support.
 typed_data_with_limited_ints_test: Skip # Requires fixed-size int64 support.
-uri_parse_test: Slow
-uri_test: Slow
+uri_parse_test: Slow, Pass
+uri_test: Slow, Pass
 
 [ $compiler == dartkb || $compiler == dartkp ]
-bigint_parse_radix_test: Slow # --no_intrinsify
+bigint_parse_radix_test: Slow, Pass # --no_intrinsify
 bigint_test/03: SkipSlow # --no_intrinsify
 bigint_test/15: SkipSlow # --no_intrinsify
 
 [ $runtime == dart_precompiled || $runtime == vm ]
 regexp/global_test: Skip # Issue 21709
-regexp/pcre_test: Slow
+regexp/pcre_test: Slow, Pass
 
 [ $hot_reload || $hot_reload_rollback ]
 bigint_parse_radix_test: Skip # Issue 31659. Issue 34361.
 bigint_test: Skip # Issue 31659
-integer_parsed_mul_div_vm_test: Slow # Slow
+integer_parsed_mul_div_vm_test: Slow, Pass # Slow
diff --git a/tests/corelib_2/corelib_2.status b/tests/corelib_2/corelib_2.status
index 834728b..e13f379 100644
--- a/tests/corelib_2/corelib_2.status
+++ b/tests/corelib_2/corelib_2.status
@@ -6,7 +6,7 @@
 regexp/lookbehind_test/01: Skip # Flaky in uncatchable way.  Issue 36280
 
 [ $mode == debug ]
-regexp/pcre_test: Slow # Issue 22008
+regexp/pcre_test: Slow, Pass # Issue 22008
 
 [ $arch == x64 && $system == windows ]
 stopwatch_test: Skip # Flaky test due to expected performance behaviour.
@@ -22,7 +22,7 @@
 bigint_js_test: SkipByDesign # JavaScript-specific test
 
 [ $compiler == dart2js && $runtime != none ]
-regexp/pcre_test: Slow # Issue 21593
+regexp/pcre_test: Slow, Pass # Issue 21593
 
 # We no longer expect Dart2 tests to run with the standalone VM without the new
 # common front end, but for now we get better coverage by still running them in
@@ -43,19 +43,19 @@
 bigint_test/15: SkipSlow # modPow is very slow
 int_parse_with_limited_ints_test: Skip # Requires fixed-size int64 support.
 typed_data_with_limited_ints_test: Skip # Requires fixed-size int64 support.
-uri_parse_test: Slow
-uri_test: Slow
+uri_parse_test: Slow, Pass
+uri_test: Slow, Pass
 
 [ $compiler == dartkb || $compiler == dartkp ]
-bigint_parse_radix_test: Slow # --no_intrinsify
+bigint_parse_radix_test: Slow, Pass # --no_intrinsify
 bigint_test/03: SkipSlow # --no_intrinsify
 bigint_test/15: SkipSlow # --no_intrinsify
 
 [ $runtime == dart_precompiled || $runtime == vm ]
 regexp/global_test: Skip # Issue 21709
-regexp/pcre_test: Slow
+regexp/pcre_test: Slow, Pass
 
 [ $hot_reload || $hot_reload_rollback ]
 bigint_parse_radix_test: Skip # Issue 31659. Issue 34361.
 bigint_test: Skip # Issue 31659
-integer_parsed_mul_div_vm_test: Slow # Slow
+integer_parsed_mul_div_vm_test: Slow, Pass # Slow
diff --git a/tests/ffi/data_test.dart b/tests/ffi/data_test.dart
index a533ced..b2d304d 100644
--- a/tests/ffi/data_test.dart
+++ b/tests/ffi/data_test.dart
@@ -103,7 +103,7 @@
   //
   // Null pointer throws a Dart exception.
   bool returnedNullPointer = false;
-  Pointer<Int8> p;
+  Pointer<Int8> p = nullptr;
   try {
     p = allocate<Int8>(count: 0);
   } on Exception {
diff --git a/tests/ffi/dylib_utils.dart b/tests/ffi/dylib_utils.dart
index fb8153a..2b7ac27 100644
--- a/tests/ffi/dylib_utils.dart
+++ b/tests/ffi/dylib_utils.dart
@@ -5,7 +5,7 @@
 import 'dart:ffi' as ffi;
 import 'dart:io' show Platform;
 
-String _platformPath(String name, {String path}) {
+String _platformPath(String name, {String? path}) {
   if (path == null) path = "";
   if (Platform.isLinux || Platform.isAndroid)
     return path + "lib" + name + ".so";
@@ -14,7 +14,7 @@
   throw Exception("Platform not implemented");
 }
 
-ffi.DynamicLibrary dlopenPlatformSpecific(String name, {String path}) {
+ffi.DynamicLibrary dlopenPlatformSpecific(String name, {String? path}) {
   String fullPath = _platformPath(name, path: path);
   return ffi.DynamicLibrary.open(fullPath);
 }
diff --git a/tests/ffi/external_typed_data_test.dart b/tests/ffi/external_typed_data_test.dart
index 8d19f79..2b584b4 100644
--- a/tests/ffi/external_typed_data_test.dart
+++ b/tests/ffi/external_typed_data_test.dart
@@ -199,8 +199,8 @@
   free(ptr);
 }
 
-double maxFloat = (2 - pow(2, -23)) * pow(2, 127);
-double maxDouble = (2 - pow(2, -52)) * pow(2, pow(2, 10) - 1);
+double maxFloat = (2 - pow(2, -23)) * pow(2, 127) as double;
+double maxDouble = (2 - pow(2, -52)) * pow(2, pow(2, 10) - 1) as double;
 
 void testFloatLoad() {
   // Load
diff --git a/tests/ffi/regress_37254_test.dart b/tests/ffi/regress_37254_test.dart
index dcd42b9..b4fce7c 100644
--- a/tests/ffi/regress_37254_test.dart
+++ b/tests/ffi/regress_37254_test.dart
@@ -84,7 +84,7 @@
 
   // Successful implicit downcast of argument at runtime.
   // Should succeed now, should statically be rejected when NNBD lands.
-  a.value = b;
+  a.value = b as Pointer<Int8>;
 
   free(a);
   free(b);
@@ -97,7 +97,7 @@
   // Failing implicit downcast of argument at runtime.
   // Should fail now at runtime, should statically be rejected when NNBD lands.
   Expect.throws(() {
-    a.value = b;
+    a.value = b as Pointer<Int8>;
   });
 
   free(a);
@@ -199,7 +199,7 @@
   // Reified as Pointer<Pointer<Int8>> at runtime.
   final Pointer<Pointer<NativeType>> a = allocate<Pointer<Int8>>();
 
-  Pointer<Int8> b = a.value;
+  Pointer<Int8> b = a.value as Pointer<Int8>;
   Expect.type<Pointer<Int8>>(b);
 
   free(a);
@@ -222,7 +222,7 @@
   // Failing implicit downcast of return value at runtime.
   // Should fail now at runtime, should statically be rejected when NNBD lands.
   Expect.throws(() {
-    Pointer<Int8> b = a.value;
+    Pointer<Int8> b = a.value as Pointer<Int8>;
   });
 
   free(a);
diff --git a/tests/ffi/variance_function_test.dart b/tests/ffi/variance_function_test.dart
index d6e6378..539c245 100644
--- a/tests/ffi/variance_function_test.dart
+++ b/tests/ffi/variance_function_test.dart
@@ -165,7 +165,7 @@
 }
 
 // Pointer to return to C when C calls back into Dart and asks for a Pointer.
-Pointer<Int64> data;
+Pointer<Int64> data = nullptr;
 
 Pointer<Int64> int64PointerReturnOp() {
   return data;
@@ -194,7 +194,7 @@
       CallbackNaTyPointerParamOpDart>(callbackParamOpName);
   final fp = Pointer.fromFunction<Int64PointerParamOp>(int64PointerParamOp);
   Expect.throws(() {
-    callback(fp);
+    callback(fp as Pointer<NativeFunction<NaTyPointerParamOp>>);
   });
 }
 
diff --git a/tests/ffi/vmspecific_enable_ffi_test.dart b/tests/ffi/vmspecific_enable_ffi_test.dart
index 3cbd635..f44753d 100644
--- a/tests/ffi/vmspecific_enable_ffi_test.dart
+++ b/tests/ffi/vmspecific_enable_ffi_test.dart
@@ -4,18 +4,14 @@
 //
 // Dart test program for testing the --enable-ffi=false flag.
 //
-// Note: In AoT and Android the flag is passed to Dart when executing the
-// precompiled executable, so the error shows up as a runtime error rather than
-// a compile time error.
-//
 // VMOptions=--enable-ffi=false
 
-import 'dart:ffi'; //# 01: compile-time error, runtime error
-import 'package:ffi/ffi.dart'; //# 01: compile-time error, runtime error
+import 'dart:ffi'; //# 01: compile-time error
+import 'package:ffi/ffi.dart'; //# 01: compile-time error
 
 void main() {
-  Pointer<Int8> p = //# 01: compile-time error, runtime error
-      allocate(); //# 01: compile-time error, runtime error
-  print(p.address); //# 01: compile-time error, runtime error
-  free(p); //# 01: compile-time error, runtime error
+  Pointer<Int8> p = //# 01: compile-time error
+      allocate(); //# 01: compile-time error
+  print(p.address); //# 01: compile-time error
+  free(p); //# 01: compile-time error
 }
diff --git a/tests/ffi/vmspecific_static_checks_test.dart b/tests/ffi/vmspecific_static_checks_test.dart
index 410f33f..a0af90f 100644
--- a/tests/ffi/vmspecific_static_checks_test.dart
+++ b/tests/ffi/vmspecific_static_checks_test.dart
@@ -51,7 +51,7 @@
 
 void testGetGeneric() {
   int generic(Pointer p) {
-    int result;
+    int result = -1;
     result = p.value; //# 20: compile-time error
     return result;
   }
@@ -64,10 +64,10 @@
 }
 
 void testGetGeneric2() {
-  T generic<T extends Object>() {
+  T? generic<T extends Object>() {
     Pointer<Int8> p = allocate();
     p.value = 123;
-    T result;
+    T? result;
     result = p.value; //# 21: compile-time error
     free(p);
     return result;
@@ -161,19 +161,19 @@
 }
 
 void testAsFunctionGeneric() {
-  T generic<T extends Function>() {
+  T generic<T extends Function>(T defaultFunction) {
     Pointer<NativeFunction<Int8UnOp>> p = Pointer.fromAddress(1337);
-    Function f;
+    T f = defaultFunction;
     f = p.asFunction<T>(); //# 11: compile-time error
     return f;
   }
 
-  generic<IntUnOp>();
+  generic<IntUnOp>((int a) => a + 1);
 }
 
 void testAsFunctionGeneric2() {
   generic(Pointer<NativeFunction> p) {
-    Function f;
+    Function f = () => "dummy";
     f = p.asFunction<IntUnOp>(); //# 12: compile-time error
     return f;
   }
@@ -203,7 +203,7 @@
 
 void testFromFunctionGeneric() {
   Pointer<NativeFunction> generic<T extends Function>(T f) {
-    Pointer<NativeFunction<NativeDoubleUnOp>> result;
+    Pointer<NativeFunction<NativeDoubleUnOp>> result = nullptr;
     result = Pointer.fromFunction(f); //# 70: compile-time error
     return result;
   }
@@ -213,7 +213,7 @@
 
 void testFromFunctionGeneric2() {
   Pointer<NativeFunction<T>> generic<T extends Function>() {
-    Pointer<NativeFunction<T>> result;
+    Pointer<NativeFunction<T>> result = nullptr;
     result = Pointer.fromFunction(myTimesThree); //# 71: compile-time error
     return result;
   }
@@ -254,7 +254,7 @@
 void testLookupFunctionGeneric() {
   Function generic<T extends Function>() {
     DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
-    Function result;
+    Function result = () => "dummy";
     result = l.lookupFunction<T, DoubleUnOp>("cos"); //# 15: compile-time error
     return result;
   }
@@ -265,7 +265,7 @@
 void testLookupFunctionGeneric2() {
   Function generic<T extends Function>() {
     DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
-    Function result;
+    Function result = () => "dummy";
     result = //# 16: compile-time error
         l.lookupFunction<NativeDoubleUnOp, T>("cos"); //# 16: compile-time error
     return result;
diff --git a/tests/ffi_2/aliasing_test.dart b/tests/ffi_2/aliasing_test.dart
new file mode 100644
index 0000000..6c2f698
--- /dev/null
+++ b/tests/ffi_2/aliasing_test.dart
@@ -0,0 +1,212 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test programing for testing that optimizations do wrongly assume loads
+// from and stores to C memory are not aliased.
+//
+// SharedObjects=ffi_test_functions
+// VMOptions=--deterministic --optimization-counter-threshold=50
+
+import 'dart:ffi';
+
+import "package:ffi/ffi.dart";
+import "package:expect/expect.dart";
+
+import 'ffi_test_helpers.dart';
+
+void main() {
+  for (int i = 0; i < 100; ++i) {
+    testNonAlias();
+    testAliasCast();
+    testAliasCast2();
+    testAliasOffsetBy();
+    testAliasOffsetBy2();
+    testAliasElementAt();
+    testAliasElementAt2();
+    testAliasFromAddress();
+    testAliasFromAddress2();
+    testAliasFromAddressViaMemory();
+    testAliasFromAddressViaMemory2();
+    testAliasFromAddressViaNativeFunction();
+    testAliasFromAddressViaNativeFunction2();
+    testPartialOverlap();
+  }
+}
+
+void testNonAlias() {
+  final source = allocate<Int64>();
+  source.value = 42;
+  final int a = source.value;
+  source.value = 1984;
+  // alias.value should be re-executed, as we wrote to alias.
+  Expect.notEquals(a, source.value);
+  free(source);
+}
+
+void testAliasCast() {
+  final source = allocate<Int64>();
+  final alias = source.cast<Int8>().cast<Int64>();
+  source.value = 42;
+  final int a = source.value;
+  alias.value = 1984;
+  // source.value should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.value);
+  free(source);
+}
+
+void testAliasCast2() {
+  final source = allocate<Int64>();
+  final alias = source.cast<Int16>().cast<Int64>();
+  final alias2 = source.cast<Int8>().cast<Int64>();
+  alias.value = 42;
+  final int a = alias.value;
+  alias2.value = 1984;
+  // alias.value should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.value);
+  free(source);
+}
+
+void testAliasOffsetBy() {
+  final source = allocate<Int64>(count: 2);
+  final alias = source.offsetBy(8).offsetBy(-8);
+  source.value = 42;
+  final int a = source.value;
+  alias.value = 1984;
+  // source.value should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.value);
+  free(source);
+}
+
+void testAliasOffsetBy2() {
+  final source = allocate<Int64>(count: 3);
+  final alias = source.offsetBy(16).offsetBy(-16);
+  final alias2 = source.offsetBy(8).offsetBy(-8);
+  alias.value = 42;
+  final int a = alias.value;
+  alias2.value = 1984;
+  // alias.value should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.value);
+  free(source);
+}
+
+void testAliasElementAt() {
+  final source = allocate<Int64>(count: 2);
+  final alias = source.elementAt(1).elementAt(-1);
+  source.value = 42;
+  final int a = source.value;
+  alias.value = 1984;
+  // source.value should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.value);
+  free(source);
+}
+
+void testAliasElementAt2() {
+  final source = allocate<Int64>(count: 3);
+  final alias = source.elementAt(2).elementAt(-2);
+  final alias2 = source.elementAt(1).elementAt(-1);
+  alias.value = 42;
+  final int a = alias.value;
+  alias2.value = 1984;
+  // alias.value should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.value);
+  free(source);
+}
+
+void testAliasFromAddress() {
+  final source = allocate<Int64>();
+  final alias = Pointer<Int64>.fromAddress(source.address);
+  source.value = 42;
+  final int a = source.value;
+  alias.value = 1984;
+  // source.value should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.value);
+  free(source);
+}
+
+void testAliasFromAddress2() {
+  final source = allocate<Int64>();
+  final alias = Pointer<Int64>.fromAddress(source.address);
+  final alias2 = Pointer<Int64>.fromAddress(source.address);
+  alias.value = 42;
+  final int a = alias.value;
+  alias2.value = 1984;
+  // alias.value should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.value);
+  free(source);
+}
+
+void testAliasFromAddressViaMemory() {
+  final helper = allocate<IntPtr>();
+  final source = allocate<Int64>();
+  helper.value = source.address;
+  final alias = Pointer<Int64>.fromAddress(helper.value);
+  source.value = 42;
+  final int a = source.value;
+  alias.value = 1984;
+  // source.value should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.value);
+  free(helper);
+  free(source);
+}
+
+void testAliasFromAddressViaMemory2() {
+  final helper = allocate<IntPtr>();
+  final source = allocate<Int64>();
+  helper.value = source.address;
+  final alias = Pointer<Int64>.fromAddress(helper.value);
+  final alias2 = Pointer<Int64>.fromAddress(helper.value);
+  alias.value = 42;
+  final int a = alias.value;
+  alias2.value = 1984;
+  // alias.value should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.value);
+  free(helper);
+  free(source);
+}
+
+typedef NativeQuadOpSigned = Int64 Function(Int8, Int16, Int32, Int64);
+typedef QuadOp = int Function(int, int, int, int);
+
+QuadOp intComputation = ffiTestFunctions
+    .lookupFunction<NativeQuadOpSigned, QuadOp>("IntComputation");
+
+void testAliasFromAddressViaNativeFunction() {
+  final source = allocate<Int64>();
+  final alias =
+      Pointer<Int64>.fromAddress(intComputation(0, 0, 0, source.address));
+  source.value = 42;
+  final int a = source.value;
+  alias.value = 1984;
+  // source.value should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.value);
+  free(source);
+}
+
+void testAliasFromAddressViaNativeFunction2() {
+  final source = allocate<Int64>();
+  final alias =
+      Pointer<Int64>.fromAddress(intComputation(0, 0, 0, source.address));
+  final alias2 =
+      Pointer<Int64>.fromAddress(intComputation(0, 0, 0, source.address));
+  alias.value = 42;
+  final int a = alias.value;
+  alias2.value = 1984;
+  // alias.value should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.value);
+  free(source);
+}
+
+@pragma('vm:never-inline')
+Pointer<Int8> makeDerived(Pointer<Int64> source) =>
+    source.offsetBy(7).cast<Int8>();
+
+testPartialOverlap() {
+  final source = allocate<Int64>(count: 2);
+  final derived = makeDerived(source);
+  source.value = 0x1122334455667788;
+  final int value = source.value;
+  derived.value = 0xaa;
+  Expect.notEquals(value, source.value);
+  free(source);
+}
diff --git a/tests/ffi_2/analysis_options.yaml b/tests/ffi_2/analysis_options.yaml
new file mode 100644
index 0000000..f8701d7
--- /dev/null
+++ b/tests/ffi_2/analysis_options.yaml
@@ -0,0 +1,3 @@
+analyzer:
+  exclude:
+    # Do analyze this subfolder in the tests/ even if tests/ is fully excluded.
diff --git a/tests/ffi_2/callback_tests_utils.dart b/tests/ffi_2/callback_tests_utils.dart
new file mode 100644
index 0000000..ac5fdcb
--- /dev/null
+++ b/tests/ffi_2/callback_tests_utils.dart
@@ -0,0 +1,34 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:ffi';
+
+import 'dylib_utils.dart';
+
+import "package:expect/expect.dart";
+
+final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+typedef NativeCallbackTest = Int32 Function(Pointer);
+typedef NativeCallbackTestFn = int Function(Pointer);
+
+class CallbackTest {
+  final String name;
+  final Pointer callback;
+  final bool skip;
+
+  CallbackTest(this.name, this.callback, {bool skipIf: false})
+      : skip = skipIf {}
+
+  void run() {
+    if (skip) return;
+
+    final NativeCallbackTestFn tester = ffiTestFunctions
+        .lookupFunction<NativeCallbackTest, NativeCallbackTestFn>("Test$name");
+    final int testCode = tester(callback);
+    if (testCode != 0) {
+      Expect.fail("Test $name failed.");
+    }
+  }
+}
diff --git a/tests/ffi_2/coordinate.dart b/tests/ffi_2/coordinate.dart
new file mode 100644
index 0000000..92dd9d4
--- /dev/null
+++ b/tests/ffi_2/coordinate.dart
@@ -0,0 +1,26 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library FfiTest;
+
+import 'dart:ffi';
+import "package:ffi/ffi.dart";
+
+/// Sample struct for dart:ffi library.
+class Coordinate extends Struct {
+  @Double()
+  double x;
+
+  @Double()
+  double y;
+
+  Pointer<Coordinate> next;
+
+  factory Coordinate.allocate(double x, double y, Pointer<Coordinate> next) {
+    return allocate<Coordinate>().ref
+      ..x = x
+      ..y = y
+      ..next = next;
+  }
+}
diff --git a/tests/ffi_2/coordinate_bare.dart b/tests/ffi_2/coordinate_bare.dart
new file mode 100644
index 0000000..daaea24
--- /dev/null
+++ b/tests/ffi_2/coordinate_bare.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library FfiTestCoordinateBare;
+
+import 'dart:ffi';
+
+/// Stripped down sample struct for dart:ffi library.
+class Coordinate extends Struct {
+  @Double()
+  double x;
+
+  @Double()
+  double y;
+
+  Pointer<Coordinate> next;
+}
diff --git a/tests/ffi_2/data_not_asan_test.dart b/tests/ffi_2/data_not_asan_test.dart
new file mode 100644
index 0000000..e95658f
--- /dev/null
+++ b/tests/ffi_2/data_not_asan_test.dart
@@ -0,0 +1,35 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi primitive data pointers.
+//
+// These mallocs trigger an asan alarm, so these tests are in a separate file
+// which is excluded in asan mode.
+
+import 'dart:ffi';
+
+import "package:ffi/ffi.dart";
+import "package:expect/expect.dart";
+
+void main() {
+  testPointerAllocateTooLarge();
+  testPointerAllocateNegative();
+}
+
+void testPointerAllocateTooLarge() {
+  // Try to allocate something that doesn't fit in 64 bit address space.
+  int maxInt = 9223372036854775807; // 2^63 - 1
+  Expect.throws(() => allocate<Int64>(count: maxInt));
+
+  // Try to allocate almost the full 64 bit address space.
+  int maxInt1_8 = 1152921504606846975; // 2^60 -1
+  Expect.throws(() => allocate<Int64>(count: maxInt1_8));
+}
+
+void testPointerAllocateNegative() {
+  // Passing in -1 will be converted into an unsigned integer. So, it will try
+  // to allocate SIZE_MAX - 1 + 1 bytes. This will fail as it is the max amount
+  // of addressable memory on the system.
+  Expect.throws(() => allocate<Int8>(count: -1));
+}
diff --git a/tests/ffi_2/data_test.dart b/tests/ffi_2/data_test.dart
new file mode 100644
index 0000000..a533ced
--- /dev/null
+++ b/tests/ffi_2/data_test.dart
@@ -0,0 +1,518 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi primitive data pointers.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+import "package:ffi/ffi.dart";
+
+import 'ffi_test_helpers.dart';
+
+void main() {
+  testPointerBasic();
+  testPointerFromPointer();
+  testPointerPointerArithmetic();
+  testPointerPointerArithmeticSizes();
+  testPointerAllocateZero();
+  testPointerCast();
+  testCastGeneric();
+  testCastGeneric2();
+  testCastNativeType();
+  testCondensedNumbersInt8();
+  testCondensedNumbersFloat();
+  testRangeInt8();
+  testRangeUint8();
+  testRangeInt16();
+  testRangeUint16();
+  testRangeInt32();
+  testRangeUint32();
+  testRangeInt64();
+  testRangeUint64();
+  testRangeIntPtr();
+  testFloat();
+  testDouble();
+  testVoid();
+  testPointerPointer();
+  testPointerPointerNull();
+  testSizeOf();
+  testPointerChain(100);
+  testTypeTest();
+  testToString();
+  testEquality();
+  testAllocateGeneric();
+  testAllocateVoid();
+  testAllocateNativeFunction();
+  testAllocateNativeType();
+  testSizeOfGeneric();
+  testSizeOfVoid();
+  testSizeOfNativeFunction();
+  testSizeOfNativeType();
+  testDynamicInvocation();
+  testMemoryAddressTruncation();
+  testNullptrCast();
+}
+
+void testPointerBasic() {
+  Pointer<Int64> p = allocate();
+  p.value = 42;
+  Expect.equals(42, p.value);
+  free(p);
+}
+
+void testPointerFromPointer() {
+  Pointer<Int64> p = allocate();
+  p.value = 1337;
+  int ptr = p.address;
+  Pointer<Int64> p2 = Pointer.fromAddress(ptr);
+  Expect.equals(1337, p2.value);
+  free(p);
+}
+
+void testPointerPointerArithmetic() {
+  Pointer<Int64> p = allocate(count: 2);
+  Pointer<Int64> p2 = p.elementAt(1);
+  p2.value = 100;
+  Pointer<Int64> p3 = p.offsetBy(8);
+  Expect.equals(100, p3.value);
+  free(p);
+}
+
+void testPointerPointerArithmeticSizes() {
+  Pointer<Int64> p = allocate(count: 2);
+  Pointer<Int64> p2 = p.elementAt(1);
+  int addr = p.address;
+  Expect.equals(addr + 8, p2.address);
+  free(p);
+
+  Pointer<Int32> p3 = allocate(count: 2);
+  Pointer<Int32> p4 = p3.elementAt(1);
+  addr = p3.address;
+  Expect.equals(addr + 4, p4.address);
+  free(p3);
+}
+
+void testPointerAllocateZero() {
+  // > If size is 0, either a null pointer or a unique pointer that can be
+  // > successfully passed to free() shall be returned.
+  // http://pubs.opengroup.org/onlinepubs/009695399/functions/malloc.html
+  //
+  // Null pointer throws a Dart exception.
+  bool returnedNullPointer = false;
+  Pointer<Int8> p;
+  try {
+    p = allocate<Int8>(count: 0);
+  } on Exception {
+    returnedNullPointer = true;
+  }
+  if (!returnedNullPointer) {
+    free(p);
+  }
+}
+
+void testPointerCast() {
+  Pointer<Int64> p = allocate();
+  p.cast<Int32>(); // gets the correct type args back
+  free(p);
+}
+
+void testCastGeneric() {
+  Pointer<T> generic<T extends NativeType>(Pointer<Int16> p) {
+    return p.cast();
+  }
+
+  Pointer<Int16> p = allocate();
+  Pointer<Int64> p2 = generic(p);
+  free(p);
+}
+
+void testCastGeneric2() {
+  Pointer<Int64> generic<T extends NativeType>(Pointer<T> p) {
+    return p.cast();
+  }
+
+  Pointer<Int16> p = allocate();
+  Pointer<Int64> p2 = generic(p);
+  free(p);
+}
+
+void testCastNativeType() {
+  Pointer<Int64> p = allocate();
+  p.cast<Pointer>();
+  free(p);
+}
+
+void testCondensedNumbersInt8() {
+  Pointer<Int8> p = allocate(count: 8);
+  for (var i in [0, 1, 2, 3, 4, 5, 6, 7]) {
+    p[i] = i * 3;
+  }
+  for (var i in [0, 1, 2, 3, 4, 5, 6, 7]) {
+    Expect.equals(i * 3, p[i]);
+  }
+  free(p);
+}
+
+void testCondensedNumbersFloat() {
+  Pointer<Float> p = allocate(count: 8);
+  for (var i in [0, 1, 2, 3, 4, 5, 6, 7]) {
+    p[i] = 1.511366173271439e-13;
+  }
+  for (var i in [0, 1, 2, 3, 4, 5, 6, 7]) {
+    Expect.equals(1.511366173271439e-13, p[i]);
+  }
+  free(p);
+}
+
+void testRangeInt8() {
+  Pointer<Int8> p = allocate();
+  p.value = 127;
+  Expect.equals(127, p.value);
+  p.value = -128;
+  Expect.equals(-128, p.value);
+
+  Expect.equals(0x0000000000000080, 128);
+  Expect.equals(0xFFFFFFFFFFFFFF80, -128);
+  p.value = 128;
+  Expect.equals(-128, p.value); // truncated and sign extended
+
+  Expect.equals(0xFFFFFFFFFFFFFF7F, -129);
+  Expect.equals(0x000000000000007F, 127);
+  p.value = -129;
+  Expect.equals(127, p.value); // truncated
+  free(p);
+}
+
+void testRangeUint8() {
+  Pointer<Uint8> p = allocate();
+  p.value = 255;
+  Expect.equals(255, p.value);
+  p.value = 0;
+  Expect.equals(0, p.value);
+
+  Expect.equals(0x0000000000000000, 0);
+  Expect.equals(0x0000000000000100, 256);
+  p.value = 256;
+  Expect.equals(0, p.value); // truncated
+
+  Expect.equals(0xFFFFFFFFFFFFFFFF, -1);
+  Expect.equals(0x00000000000000FF, 255);
+  p.value = -1;
+  Expect.equals(255, p.value); // truncated
+  free(p);
+}
+
+void testRangeInt16() {
+  Pointer<Int16> p = allocate();
+  p.value = 0x7FFF;
+  Expect.equals(0x7FFF, p.value);
+  p.value = -0x8000;
+  Expect.equals(-0x8000, p.value);
+  p.value = 0x8000;
+  Expect.equals(0xFFFFFFFFFFFF8000, p.value); // truncated and sign extended
+  p.value = -0x8001;
+  Expect.equals(0x7FFF, p.value); // truncated
+  free(p);
+}
+
+void testRangeUint16() {
+  Pointer<Uint16> p = allocate();
+  p.value = 0xFFFF;
+  Expect.equals(0xFFFF, p.value);
+  p.value = 0;
+  Expect.equals(0, p.value);
+  p.value = 0x10000;
+  Expect.equals(0, p.value); // truncated
+  p.value = -1;
+  Expect.equals(0xFFFF, p.value); // truncated
+  free(p);
+}
+
+void testRangeInt32() {
+  Pointer<Int32> p = allocate();
+  p.value = 0x7FFFFFFF;
+  Expect.equals(0x7FFFFFFF, p.value);
+  p.value = -0x80000000;
+  Expect.equals(-0x80000000, p.value);
+  p.value = 0x80000000;
+  Expect.equals(0xFFFFFFFF80000000, p.value); // truncated and sign extended
+  p.value = -0x80000001;
+  Expect.equals(0x7FFFFFFF, p.value); // truncated
+  free(p);
+}
+
+void testRangeUint32() {
+  Pointer<Uint32> p = allocate();
+  p.value = 0xFFFFFFFF;
+  Expect.equals(0xFFFFFFFF, p.value);
+  p.value = 0;
+  Expect.equals(0, p.value);
+  p.value = 0x100000000;
+  Expect.equals(0, p.value); // truncated
+  p.value = -1;
+  Expect.equals(0xFFFFFFFF, p.value); // truncated
+  free(p);
+}
+
+void testRangeInt64() {
+  Pointer<Int64> p = allocate();
+  p.value = 0x7FFFFFFFFFFFFFFF; // 2 ^ 63 - 1
+  Expect.equals(0x7FFFFFFFFFFFFFFF, p.value);
+  p.value = -0x8000000000000000; // -2 ^ 63
+  Expect.equals(-0x8000000000000000, p.value);
+  free(p);
+}
+
+void testRangeUint64() {
+  Pointer<Uint64> p = allocate();
+  p.value = 0x7FFFFFFFFFFFFFFF; // 2 ^ 63 - 1
+  Expect.equals(0x7FFFFFFFFFFFFFFF, p.value);
+  p.value = -0x8000000000000000; // -2 ^ 63 interpreted as 2 ^ 63
+  Expect.equals(-0x8000000000000000, p.value);
+
+  // Dart allows interpreting bits both signed and unsigned
+  Expect.equals(0xFFFFFFFFFFFFFFFF, -1);
+  p.value = -1; // -1 interpreted as 2 ^ 64 - 1
+  Expect.equals(-1, p.value);
+  Expect.equals(0xFFFFFFFFFFFFFFFF, p.value);
+  free(p);
+}
+
+void testRangeIntPtr() {
+  Pointer<IntPtr> p = allocate();
+  int pAddr = p.address;
+  p.value = pAddr; // its own address should fit
+  p.value = 0x7FFFFFFF; // and 32 bit addresses should fit
+  Expect.equals(0x7FFFFFFF, p.value);
+  p.value = -0x80000000;
+  Expect.equals(-0x80000000, p.value);
+  free(p);
+}
+
+void testFloat() {
+  Pointer<Float> p = allocate();
+  p.value = 1.511366173271439e-13;
+  Expect.equals(1.511366173271439e-13, p.value);
+  p.value = 1.4260258159703532e-105; // float does not have enough precision
+  Expect.notEquals(1.4260258159703532e-105, p.value);
+  free(p);
+}
+
+void testDouble() {
+  Pointer<Double> p = allocate();
+  p.value = 1.4260258159703532e-105;
+  Expect.equals(1.4260258159703532e-105, p.value);
+  free(p);
+}
+
+void testVoid() {
+  Pointer<IntPtr> p1 = allocate();
+  Pointer<Void> p2 = p1.cast(); // make this dart pointer opaque
+  p2.address; // we can print the address
+  free(p2);
+}
+
+void testPointerPointer() {
+  Pointer<Int16> p = allocate();
+  p.value = 17;
+  Pointer<Pointer<Int16>> p2 = allocate();
+  p2.value = p;
+  Expect.equals(17, p2.value.value);
+  free(p2);
+  free(p);
+}
+
+void testPointerPointerNull() {
+  Pointer<Pointer<Int8>> pointerToPointer = allocate();
+  Pointer<Int8> value = nullptr;
+  pointerToPointer.value = value;
+  value = pointerToPointer.value;
+  Expect.equals(value, nullptr);
+  value = allocate();
+  pointerToPointer.value = value;
+  value = pointerToPointer.value;
+  Expect.isNotNull(value);
+  free(value);
+  value = nullptr;
+  pointerToPointer.value = value;
+  value = pointerToPointer.value;
+  Expect.equals(value, nullptr);
+  free(pointerToPointer);
+}
+
+void testSizeOf() {
+  Expect.equals(1, sizeOf<Int8>());
+  Expect.equals(2, sizeOf<Int16>());
+  Expect.equals(4, sizeOf<Int32>());
+  Expect.equals(8, sizeOf<Int64>());
+  Expect.equals(1, sizeOf<Uint8>());
+  Expect.equals(2, sizeOf<Uint16>());
+  Expect.equals(4, sizeOf<Uint32>());
+  Expect.equals(8, sizeOf<Uint64>());
+  Expect.equals(true, 4 == sizeOf<IntPtr>() || 8 == sizeOf<IntPtr>());
+  Expect.equals(4, sizeOf<Float>());
+  Expect.equals(8, sizeOf<Double>());
+}
+
+// note: stack overflows at around 15k calls
+void testPointerChain(int length) {
+  void createChain(Pointer<IntPtr> head, int length, int value) {
+    if (length == 0) {
+      head.value = value;
+      return;
+    }
+    Pointer<IntPtr> next = allocate();
+    head.value = next.address;
+    createChain(next, length - 1, value);
+  }
+
+  int getChainValue(Pointer<IntPtr> head, int length) {
+    if (length == 0) {
+      return head.value;
+    }
+    Pointer<IntPtr> next = Pointer.fromAddress(head.value);
+    return getChainValue(next, length - 1);
+  }
+
+  void freeChain(Pointer<IntPtr> head, int length) {
+    Pointer<IntPtr> next = Pointer.fromAddress(head.value);
+    free(head);
+    if (length == 0) {
+      return;
+    }
+    freeChain(next, length - 1);
+  }
+
+  Pointer<IntPtr> head = allocate();
+  createChain(head, length, 512);
+  int tailValue = getChainValue(head, length);
+  Expect.equals(512, tailValue);
+  freeChain(head, length);
+}
+
+void testTypeTest() {
+  Pointer<Int8> p = allocate();
+  Expect.isTrue(p is Pointer);
+  free(p);
+}
+
+void testToString() {
+  Pointer<Int16> p = allocate();
+  Expect.stringEquals(
+      "Pointer<Int16>: address=0x", p.toString().substring(0, 26));
+  free(p);
+  Pointer<Int64> p2 = Pointer.fromAddress(0x123abc);
+  Expect.stringEquals("Pointer<Int64>: address=0x123abc", p2.toString());
+}
+
+void testEquality() {
+  Pointer<Int8> p = Pointer.fromAddress(12345678);
+  Pointer<Int8> p2 = Pointer.fromAddress(12345678);
+  Expect.equals(p, p2);
+  Expect.equals(p.hashCode, p2.hashCode);
+  Pointer<Int16> p3 = p.cast();
+  Expect.equals(p, p3);
+  Expect.equals(p.hashCode, p3.hashCode);
+  Pointer<Int8> p4 = p.offsetBy(1337);
+  Expect.notEquals(p, p4);
+}
+
+typedef Int8UnOp = Int8 Function(Int8);
+
+void testAllocateGeneric() {
+  Pointer<T> generic<T extends NativeType>() {
+    Pointer<T> pointer;
+    pointer = allocate();
+    return pointer;
+  }
+
+  Pointer p = generic<Int64>();
+  free(p);
+}
+
+void testAllocateVoid() {
+  Expect.throws(() {
+    Pointer<Void> p = allocate();
+  });
+}
+
+void testAllocateNativeFunction() {
+  Expect.throws(() {
+    Pointer<NativeFunction<Int8UnOp>> p = allocate();
+  });
+}
+
+void testAllocateNativeType() {
+  Expect.throws(() {
+    allocate();
+  });
+}
+
+void testSizeOfGeneric() {
+  int generic<T extends Pointer>() {
+    int size;
+    size = sizeOf<T>();
+    return size;
+  }
+
+  int size = generic<Pointer<Int64>>();
+  Expect.isTrue(size == 8 || size == 4);
+}
+
+void testSizeOfVoid() {
+  Expect.throws(() {
+    sizeOf<Void>();
+  });
+}
+
+void testSizeOfNativeFunction() {
+  Expect.throws(() {
+    sizeOf<NativeFunction<Int8UnOp>>();
+  });
+}
+
+void testSizeOfNativeType() {
+  Expect.throws(() {
+    sizeOf();
+  });
+}
+
+void testDynamicInvocation() {
+  dynamic p = allocate<Int8>();
+  Expect.throws(() {
+    final int i = p.value;
+  });
+  Expect.throws(() => p.value = 1);
+  p.elementAt(5); // Works, but is slow.
+  final int addr = p.address;
+  final Pointer<Int16> p2 = p.cast<Int16>();
+  free(p);
+}
+
+final nullableInt64ElementAt1 = ffiTestFunctions.lookupFunction<
+    Pointer<Int64> Function(Pointer<Int64>),
+    Pointer<Int64> Function(Pointer<Int64>)>("NullableInt64ElemAt1");
+
+void testNullptrCast() {
+  Pointer<Int64> ptr = nullptr;
+  ptr = nullableInt64ElementAt1(ptr);
+  Expect.equals(ptr, nullptr);
+}
+
+void testMemoryAddressTruncation() {
+  const int kIgnoreBytesPositive = 0x1122334400000000;
+  const int kIgnoreBytesNegative = 0xffddccbb00000000;
+  if (sizeOf<IntPtr>() == 4) {
+    final p1 = Pointer<Int8>.fromAddress(123);
+    final p2 = Pointer<Int8>.fromAddress(123 + kIgnoreBytesPositive);
+    final p3 = Pointer<Int8>.fromAddress(123 + kIgnoreBytesNegative);
+    Expect.equals(p1.address, p2.address);
+    Expect.equals(p1, p2);
+    Expect.equals(p1.address, p3.address);
+    Expect.equals(p1, p3);
+  }
+}
diff --git a/tests/ffi_2/dylib_utils.dart b/tests/ffi_2/dylib_utils.dart
new file mode 100644
index 0000000..fb8153a
--- /dev/null
+++ b/tests/ffi_2/dylib_utils.dart
@@ -0,0 +1,20 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:ffi' as ffi;
+import 'dart:io' show Platform;
+
+String _platformPath(String name, {String path}) {
+  if (path == null) path = "";
+  if (Platform.isLinux || Platform.isAndroid)
+    return path + "lib" + name + ".so";
+  if (Platform.isMacOS) return path + "lib" + name + ".dylib";
+  if (Platform.isWindows) return path + name + ".dll";
+  throw Exception("Platform not implemented");
+}
+
+ffi.DynamicLibrary dlopenPlatformSpecific(String name, {String path}) {
+  String fullPath = _platformPath(name, path: path);
+  return ffi.DynamicLibrary.open(fullPath);
+}
diff --git a/tests/ffi_2/extension_methods_test.dart b/tests/ffi_2/extension_methods_test.dart
new file mode 100644
index 0000000..19bc44b
--- /dev/null
+++ b/tests/ffi_2/extension_methods_test.dart
@@ -0,0 +1,65 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+import "package:ffi/ffi.dart";
+
+main(List<String> arguments) {
+  for (int i = 0; i < 100; i++) {
+    testStoreLoad();
+    testReifiedGeneric();
+  }
+}
+
+testStoreLoad() {
+  final p = allocate<Int8>(count: 2);
+  p.value = 10;
+  Expect.equals(10, p.value);
+  p[1] = 20;
+  Expect.equals(20, p[1]);
+  if (sizeOf<IntPtr>() == 4) {
+    // Test round tripping.
+    Expect.equals(20, p.elementAt(0x100000001).value);
+    Expect.equals(20, p[0x100000001]);
+  }
+
+  // Test negative index.
+  final pUseNegative = p.elementAt(1);
+  Expect.equals(10, pUseNegative[-1]);
+
+  final p1 = allocate<Double>(count: 2);
+  p1.value = 10.0;
+  Expect.approxEquals(10.0, p1.value);
+  p1[1] = 20.0;
+  Expect.approxEquals(20.0, p1[1]);
+  free(p1);
+
+  final p2 = allocate<Pointer<Int8>>(count: 2);
+  p2.value = p;
+  Expect.equals(p, p2.value);
+  p2[1] = p;
+  Expect.equals(p, p2[1]);
+  free(p2);
+  free(p);
+
+  final p3 = allocate<Foo>();
+  Foo foo = p3.ref;
+  foo.a = 1;
+  Expect.equals(1, foo.a);
+  free(p3);
+}
+
+testReifiedGeneric() {
+  final p = allocate<Pointer<Int8>>();
+  Pointer<Pointer<NativeType>> p2 = p;
+  Expect.isTrue(p2.value is Pointer<Int8>);
+  free(p);
+}
+
+class Foo extends Struct {
+  @Int8()
+  int a;
+}
diff --git a/tests/ffi_2/external_typed_data_test.dart b/tests/ffi_2/external_typed_data_test.dart
new file mode 100644
index 0000000..8d19f79
--- /dev/null
+++ b/tests/ffi_2/external_typed_data_test.dart
@@ -0,0 +1,295 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:ffi';
+import 'dart:math';
+import 'dart:typed_data';
+
+import 'package:expect/expect.dart';
+import "package:ffi/ffi.dart";
+
+main() {
+  testInt8Load();
+  testInt8Store();
+  testUint8Load();
+  testUint8Store();
+  testInt16Load();
+  testInt16Store();
+  testUint16Load();
+  testUint16Store();
+  testInt32Load();
+  testInt32Store();
+  testUint32Load();
+  testUint32Store();
+  testInt64Load();
+  testInt64Store();
+  testUint64Load();
+  testUint64Store();
+  testFloatLoad();
+  testFloatStore();
+  testDoubleLoad();
+  testDoubleStore();
+  testArrayLoad();
+  testArrayStore();
+  testNegativeArray();
+  testAlignment();
+}
+
+// For signed int tests, we store 0xf* and load -1 to check sign-extension.
+// For unsigned int tests, we store 0xf* and load the same to check truncation.
+
+void testInt8Load() {
+  // Load
+  Pointer<Int8> ptr = allocate();
+  ptr.value = 0xff;
+  Int8List list = ptr.asTypedList(1);
+  Expect.equals(list[0], -1);
+  Expect.equals(list.length, 1);
+  free(ptr);
+}
+
+void testInt8Store() {
+  // Store
+  Pointer<Int8> ptr = allocate();
+  Int8List list = ptr.asTypedList(1);
+  list[0] = 0xff;
+  Expect.equals(list.length, 1);
+  Expect.equals(ptr.value, -1);
+  free(ptr);
+}
+
+void testUint8Load() {
+  // Load
+  Pointer<Uint8> ptr = allocate();
+  ptr.value = 0xff;
+  Uint8List list = ptr.asTypedList(1);
+  Expect.equals(list[0], 0xff);
+  Expect.equals(list.length, 1);
+  free(ptr);
+}
+
+void testUint8Store() {
+  // Store
+  Pointer<Uint8> ptr = allocate();
+  Uint8List list = ptr.asTypedList(1);
+  list[0] = 0xff;
+  Expect.equals(list.length, 1);
+  Expect.equals(ptr.value, 0xff);
+  free(ptr);
+}
+
+void testInt16Load() {
+  // Load
+  Pointer<Int16> ptr = allocate();
+  ptr.value = 0xffff;
+  Int16List list = ptr.asTypedList(1);
+  Expect.equals(list[0], -1);
+  Expect.equals(list.length, 1);
+  free(ptr);
+}
+
+void testInt16Store() {
+  // Store
+  Pointer<Int16> ptr = allocate();
+  Int16List list = ptr.asTypedList(1);
+  list[0] = 0xffff;
+  Expect.equals(list.length, 1);
+  Expect.equals(ptr.value, -1);
+  free(ptr);
+}
+
+void testUint16Load() {
+  // Load
+  Pointer<Uint16> ptr = allocate();
+  ptr.value = 0xffff;
+  Uint16List list = ptr.asTypedList(1);
+  Expect.equals(list[0], 0xffff);
+  Expect.equals(list.length, 1);
+  free(ptr);
+}
+
+void testUint16Store() {
+  // Store
+  Pointer<Uint16> ptr = allocate();
+  Uint16List list = ptr.asTypedList(1);
+  list[0] = 0xffff;
+  Expect.equals(list.length, 1);
+  Expect.equals(ptr.value, 0xffff);
+  free(ptr);
+}
+
+void testInt32Load() {
+  // Load
+  Pointer<Int32> ptr = allocate();
+  ptr.value = 0xffffffff;
+  Int32List list = ptr.asTypedList(1);
+  Expect.equals(list[0], -1);
+  Expect.equals(list.length, 1);
+  free(ptr);
+}
+
+void testInt32Store() {
+  // Store
+  Pointer<Int32> ptr = allocate();
+  Int32List list = ptr.asTypedList(1);
+  list[0] = 0xffffffff;
+  Expect.equals(list.length, 1);
+  Expect.equals(ptr.value, -1);
+  free(ptr);
+}
+
+void testUint32Load() {
+  // Load
+  Pointer<Uint32> ptr = allocate();
+  ptr.value = 0xffffffff;
+  Uint32List list = ptr.asTypedList(1);
+  Expect.equals(list[0], 0xffffffff);
+  Expect.equals(list.length, 1);
+  free(ptr);
+}
+
+void testUint32Store() {
+  // Store
+  Pointer<Uint32> ptr = allocate();
+  Uint32List list = ptr.asTypedList(1);
+  list[0] = 0xffffffff;
+  Expect.equals(list.length, 1);
+  Expect.equals(ptr.value, 0xffffffff);
+  free(ptr);
+}
+
+void testInt64Load() {
+  // Load
+  Pointer<Int64> ptr = allocate();
+  ptr.value = 0xffffffffffffffff;
+  Int64List list = ptr.asTypedList(1);
+  Expect.equals(list[0], -1);
+  Expect.equals(list.length, 1);
+  free(ptr);
+}
+
+void testInt64Store() {
+  // Store
+  Pointer<Int64> ptr = allocate();
+  Int64List list = ptr.asTypedList(1);
+  list[0] = 0xffffffffffffffff;
+  Expect.equals(list.length, 1);
+  Expect.equals(ptr.value, -1);
+  free(ptr);
+}
+
+void testUint64Load() {
+  // Load
+  Pointer<Uint64> ptr = allocate();
+  ptr.value = 0xffffffffffffffff;
+  Uint64List list = ptr.asTypedList(1);
+  Expect.equals(list[0], 0xffffffffffffffff);
+  Expect.equals(list.length, 1);
+  free(ptr);
+}
+
+void testUint64Store() {
+  // Store
+  Pointer<Uint64> ptr = allocate();
+  Uint64List list = ptr.asTypedList(1);
+  list[0] = 0xffffffffffffffff;
+  Expect.equals(list.length, 1);
+  Expect.equals(ptr.value, 0xffffffffffffffff);
+  free(ptr);
+}
+
+double maxFloat = (2 - pow(2, -23)) * pow(2, 127);
+double maxDouble = (2 - pow(2, -52)) * pow(2, pow(2, 10) - 1);
+
+void testFloatLoad() {
+  // Load
+  Pointer<Float> ptr = allocate();
+  ptr.value = maxFloat;
+  Float32List list = ptr.asTypedList(1);
+  Expect.equals(list[0], maxFloat);
+  Expect.equals(list.length, 1);
+  free(ptr);
+}
+
+void testFloatStore() {
+  // Store
+  Pointer<Float> ptr = allocate();
+  Float32List list = ptr.asTypedList(1);
+  list[0] = maxFloat;
+  Expect.equals(list.length, 1);
+  Expect.equals(ptr.value, maxFloat);
+  free(ptr);
+}
+
+void testDoubleLoad() {
+  // Load
+  Pointer<Double> ptr = allocate();
+  ptr.value = maxDouble;
+  Float64List list = ptr.asTypedList(1);
+  Expect.equals(list[0], maxDouble);
+  Expect.equals(list.length, 1);
+  free(ptr);
+}
+
+void testDoubleStore() {
+  // Store
+  Pointer<Double> ptr = allocate();
+  Float64List list = ptr.asTypedList(1);
+  list[0] = maxDouble;
+  Expect.equals(list.length, 1);
+  Expect.equals(ptr.value, maxDouble);
+  free(ptr);
+}
+
+void testArrayLoad() {
+  const int count = 0x100;
+  Pointer<Int32> ptr = allocate(count: count);
+  for (int i = 0; i < count; ++i) {
+    ptr[i] = i;
+  }
+  Int32List array = ptr.asTypedList(count);
+  for (int i = 0; i < count; ++i) {
+    Expect.equals(array[i], i);
+  }
+  free(ptr);
+}
+
+void testArrayStore() {
+  const int count = 0x100;
+  Pointer<Int32> ptr = allocate(count: count);
+  Int32List array = ptr.asTypedList(count);
+  for (int i = 0; i < count; ++i) {
+    array[i] = i;
+  }
+  for (int i = 0; i < count; ++i) {
+    Expect.equals(ptr[i], i);
+  }
+  free(ptr);
+}
+
+void testNegativeArray() {
+  Pointer<Int32> ptr = nullptr;
+  Expect.throws<ArgumentError>(() => ptr.asTypedList(-1));
+}
+
+// Tests that the address we're creating an ExternalTypedData from is aligned to
+// the element size.
+void testAlignment() {
+  Expect.throws<ArgumentError>(
+      () => Pointer<Int16>.fromAddress(1).asTypedList(1));
+  Expect.throws<ArgumentError>(
+      () => Pointer<Int32>.fromAddress(2).asTypedList(1));
+  Expect.throws<ArgumentError>(
+      () => Pointer<Int64>.fromAddress(4).asTypedList(1));
+  Expect.throws<ArgumentError>(
+      () => Pointer<Uint16>.fromAddress(1).asTypedList(1));
+  Expect.throws<ArgumentError>(
+      () => Pointer<Uint32>.fromAddress(2).asTypedList(1));
+  Expect.throws<ArgumentError>(
+      () => Pointer<Uint64>.fromAddress(4).asTypedList(1));
+  Expect.throws<ArgumentError>(
+      () => Pointer<Float>.fromAddress(2).asTypedList(1));
+  Expect.throws<ArgumentError>(
+      () => Pointer<Double>.fromAddress(4).asTypedList(1));
+}
diff --git a/tests/ffi_2/ffi_2.status b/tests/ffi_2/ffi_2.status
new file mode 100644
index 0000000..6400609
--- /dev/null
+++ b/tests/ffi_2/ffi_2.status
@@ -0,0 +1,34 @@
+# Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+
+[ $builder_tag == asan ]
+data_not_asan_test: SkipByDesign # This test tries to allocate too much memory on purpose.
+
+[ $system == android ]
+*: Pass, Slow # https://github.com/dart-lang/sdk/issues/38489
+
+[ $arch == arm && $system != android ]
+*: Skip # "hardfp" calling convention is not yet supported (iOS is also supported but not tested): dartbug.com/36309
+
+[ $compiler != dart2analyzer && $compiler != fasta && $runtime != dart_precompiled && $runtime != vm ]
+*: SkipByDesign # FFI is a VM-only feature. (This test suite is part of the default set.)
+
+[ $system != android && $system != linux && $system != macos && $system != windows ]
+*: Skip # FFI not yet supported on other OSes.
+
+[ $arch == simarm || $arch == simarm64 ]
+*: Skip # FFI not yet supported on the arm simulator.
+
+# These tests trigger and catch an abort (intentionally) and terminate the VM.
+# They're incompatible with ASAN because not all memory is freed when aborting and
+# with AppJit because the abort the VM before it can generate a snapshot.
+[ $builder_tag == asan || $compiler == app_jitk ]
+vmspecific_function_callbacks_exit_test: SkipByDesign
+
+[ $compiler == dart2analyzer || $compiler == fasta ]
+vmspecific_enable_ffi_test: SkipByDesign # This is a check for VM only.
+
+[ $hot_reload || $hot_reload_rollback ]
+snapshot_test: Skip # https://dartbug.com/36097: Ongoing concurrency work.
+vmspecific_function_callbacks_test: Skip # https://dartbug.com/36097: Ongoing concurrency work.
diff --git a/tests/ffi_2/ffi_test_helpers.dart b/tests/ffi_2/ffi_test_helpers.dart
new file mode 100644
index 0000000..0c598ec
--- /dev/null
+++ b/tests/ffi_2/ffi_test_helpers.dart
@@ -0,0 +1,28 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Helpers for tests which trigger GC in delicate places.
+
+import 'dart:ffi';
+
+import 'dylib_utils.dart';
+
+typedef NativeNullaryOp = Void Function();
+typedef NullaryOpVoid = void Function();
+
+typedef NativeUnaryOp = Void Function(IntPtr);
+typedef UnaryOpVoid = void Function(int);
+
+final DynamicLibrary ffiTestFunctions =
+    dlopenPlatformSpecific("ffi_test_functions");
+
+final triggerGc = ffiTestFunctions
+    .lookupFunction<NativeNullaryOp, NullaryOpVoid>("TriggerGC");
+
+final collectOnNthAllocation = ffiTestFunctions
+    .lookupFunction<NativeUnaryOp, UnaryOpVoid>("CollectOnNthAllocation");
+
+extension PointerOffsetBy<T extends NativeType> on Pointer<T> {
+  Pointer<T> offsetBy(int bytes) => Pointer.fromAddress(address + bytes);
+}
diff --git a/tests/ffi_2/function_callbacks_many_test.dart b/tests/ffi_2/function_callbacks_many_test.dart
new file mode 100644
index 0000000..c8fb519
--- /dev/null
+++ b/tests/ffi_2/function_callbacks_many_test.dart
@@ -0,0 +1,1043 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi function pointers with callbacks.
+//
+// VMOptions=--enable-testing-pragmas
+// VMOptions=--enable-testing-pragmas --stacktrace-every=100
+// VMOptions=--enable-testing-pragmas --write-protect-code --no-dual-map-code
+// VMOptions=--enable-testing-pragmas --write-protect-code --no-dual-map-code --stacktrace-every=100
+// VMOptions=--use-slow-path --enable-testing-pragmas
+// VMOptions=--use-slow-path --enable-testing-pragmas --stacktrace-every=100
+// VMOptions=--use-slow-path --enable-testing-pragmas --write-protect-code --no-dual-map-code
+// VMOptions=--use-slow-path --enable-testing-pragmas --write-protect-code --no-dual-map-code --stacktrace-every=100
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'callback_tests_utils.dart';
+
+typedef SimpleAdditionType = Int32 Function(Int32, Int32);
+int simpleAddition(int x, int y) => x + y;
+
+void main() {
+  testManyCallbacks();
+}
+
+void testManyCallbacks() {
+  // Create enough callbacks (1000) to overflow one page of the JIT callback
+  // trampolines. The use of distinct exceptional return values forces separate
+  // trampolines.
+  final List<Pointer> pointers = [];
+
+  // All the parameters of 'fromFunction' are forced to be constant so that we
+  // only need to generate one trampoline per 'fromFunction' call-site.
+  //
+  // As a consequence, to force the creation of 1000 trampolines (and prevent
+  // any possible caching), we need literally 1000 call-sites.
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 0));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 1));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 2));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 3));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 4));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 5));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 6));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 7));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 8));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 9));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 10));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 11));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 12));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 13));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 14));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 15));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 16));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 17));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 18));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 19));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 20));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 21));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 22));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 23));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 24));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 25));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 26));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 27));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 28));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 29));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 30));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 31));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 32));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 33));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 34));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 35));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 36));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 37));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 38));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 39));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 40));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 41));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 42));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 43));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 44));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 45));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 46));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 47));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 48));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 49));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 50));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 51));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 52));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 53));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 54));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 55));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 56));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 57));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 58));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 59));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 60));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 61));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 62));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 63));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 64));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 65));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 66));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 67));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 68));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 69));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 70));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 71));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 72));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 73));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 74));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 75));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 76));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 77));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 78));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 79));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 80));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 81));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 82));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 83));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 84));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 85));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 86));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 87));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 88));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 89));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 90));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 91));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 92));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 93));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 94));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 95));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 96));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 97));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 98));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 99));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 100));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 101));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 102));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 103));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 104));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 105));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 106));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 107));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 108));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 109));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 110));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 111));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 112));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 113));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 114));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 115));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 116));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 117));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 118));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 119));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 120));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 121));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 122));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 123));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 124));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 125));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 126));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 127));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 128));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 129));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 130));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 131));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 132));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 133));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 134));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 135));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 136));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 137));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 138));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 139));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 140));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 141));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 142));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 143));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 144));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 145));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 146));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 147));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 148));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 149));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 150));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 151));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 152));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 153));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 154));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 155));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 156));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 157));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 158));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 159));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 160));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 161));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 162));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 163));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 164));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 165));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 166));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 167));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 168));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 169));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 170));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 171));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 172));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 173));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 174));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 175));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 176));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 177));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 178));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 179));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 180));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 181));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 182));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 183));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 184));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 185));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 186));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 187));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 188));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 189));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 190));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 191));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 192));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 193));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 194));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 195));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 196));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 197));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 198));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 199));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 200));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 201));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 202));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 203));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 204));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 205));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 206));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 207));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 208));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 209));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 210));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 211));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 212));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 213));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 214));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 215));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 216));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 217));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 218));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 219));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 220));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 221));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 222));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 223));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 224));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 225));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 226));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 227));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 228));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 229));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 230));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 231));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 232));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 233));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 234));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 235));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 236));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 237));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 238));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 239));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 240));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 241));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 242));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 243));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 244));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 245));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 246));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 247));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 248));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 249));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 250));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 251));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 252));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 253));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 254));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 255));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 256));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 257));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 258));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 259));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 260));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 261));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 262));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 263));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 264));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 265));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 266));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 267));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 268));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 269));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 270));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 271));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 272));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 273));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 274));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 275));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 276));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 277));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 278));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 279));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 280));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 281));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 282));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 283));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 284));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 285));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 286));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 287));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 288));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 289));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 290));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 291));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 292));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 293));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 294));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 295));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 296));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 297));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 298));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 299));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 300));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 301));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 302));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 303));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 304));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 305));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 306));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 307));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 308));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 309));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 310));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 311));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 312));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 313));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 314));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 315));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 316));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 317));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 318));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 319));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 320));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 321));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 322));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 323));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 324));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 325));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 326));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 327));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 328));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 329));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 330));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 331));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 332));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 333));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 334));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 335));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 336));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 337));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 338));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 339));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 340));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 341));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 342));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 343));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 344));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 345));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 346));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 347));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 348));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 349));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 350));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 351));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 352));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 353));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 354));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 355));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 356));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 357));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 358));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 359));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 360));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 361));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 362));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 363));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 364));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 365));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 366));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 367));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 368));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 369));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 370));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 371));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 372));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 373));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 374));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 375));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 376));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 377));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 378));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 379));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 380));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 381));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 382));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 383));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 384));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 385));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 386));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 387));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 388));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 389));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 390));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 391));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 392));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 393));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 394));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 395));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 396));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 397));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 398));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 399));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 400));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 401));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 402));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 403));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 404));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 405));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 406));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 407));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 408));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 409));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 410));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 411));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 412));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 413));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 414));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 415));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 416));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 417));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 418));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 419));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 420));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 421));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 422));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 423));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 424));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 425));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 426));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 427));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 428));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 429));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 430));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 431));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 432));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 433));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 434));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 435));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 436));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 437));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 438));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 439));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 440));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 441));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 442));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 443));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 444));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 445));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 446));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 447));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 448));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 449));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 450));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 451));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 452));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 453));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 454));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 455));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 456));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 457));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 458));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 459));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 460));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 461));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 462));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 463));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 464));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 465));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 466));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 467));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 468));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 469));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 470));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 471));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 472));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 473));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 474));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 475));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 476));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 477));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 478));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 479));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 480));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 481));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 482));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 483));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 484));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 485));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 486));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 487));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 488));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 489));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 490));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 491));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 492));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 493));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 494));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 495));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 496));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 497));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 498));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 499));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 500));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 501));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 502));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 503));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 504));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 505));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 506));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 507));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 508));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 509));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 510));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 511));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 512));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 513));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 514));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 515));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 516));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 517));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 518));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 519));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 520));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 521));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 522));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 523));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 524));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 525));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 526));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 527));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 528));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 529));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 530));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 531));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 532));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 533));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 534));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 535));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 536));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 537));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 538));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 539));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 540));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 541));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 542));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 543));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 544));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 545));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 546));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 547));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 548));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 549));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 550));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 551));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 552));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 553));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 554));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 555));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 556));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 557));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 558));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 559));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 560));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 561));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 562));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 563));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 564));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 565));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 566));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 567));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 568));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 569));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 570));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 571));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 572));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 573));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 574));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 575));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 576));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 577));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 578));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 579));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 580));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 581));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 582));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 583));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 584));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 585));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 586));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 587));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 588));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 589));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 590));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 591));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 592));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 593));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 594));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 595));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 596));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 597));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 598));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 599));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 600));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 601));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 602));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 603));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 604));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 605));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 606));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 607));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 608));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 609));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 610));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 611));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 612));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 613));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 614));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 615));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 616));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 617));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 618));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 619));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 620));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 621));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 622));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 623));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 624));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 625));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 626));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 627));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 628));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 629));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 630));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 631));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 632));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 633));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 634));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 635));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 636));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 637));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 638));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 639));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 640));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 641));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 642));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 643));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 644));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 645));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 646));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 647));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 648));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 649));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 650));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 651));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 652));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 653));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 654));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 655));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 656));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 657));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 658));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 659));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 660));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 661));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 662));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 663));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 664));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 665));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 666));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 667));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 668));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 669));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 670));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 671));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 672));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 673));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 674));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 675));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 676));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 677));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 678));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 679));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 680));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 681));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 682));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 683));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 684));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 685));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 686));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 687));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 688));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 689));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 690));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 691));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 692));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 693));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 694));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 695));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 696));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 697));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 698));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 699));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 700));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 701));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 702));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 703));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 704));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 705));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 706));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 707));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 708));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 709));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 710));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 711));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 712));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 713));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 714));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 715));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 716));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 717));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 718));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 719));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 720));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 721));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 722));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 723));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 724));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 725));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 726));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 727));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 728));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 729));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 730));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 731));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 732));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 733));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 734));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 735));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 736));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 737));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 738));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 739));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 740));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 741));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 742));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 743));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 744));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 745));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 746));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 747));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 748));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 749));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 750));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 751));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 752));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 753));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 754));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 755));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 756));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 757));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 758));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 759));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 760));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 761));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 762));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 763));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 764));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 765));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 766));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 767));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 768));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 769));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 770));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 771));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 772));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 773));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 774));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 775));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 776));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 777));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 778));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 779));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 780));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 781));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 782));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 783));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 784));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 785));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 786));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 787));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 788));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 789));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 790));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 791));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 792));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 793));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 794));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 795));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 796));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 797));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 798));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 799));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 800));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 801));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 802));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 803));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 804));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 805));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 806));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 807));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 808));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 809));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 810));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 811));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 812));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 813));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 814));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 815));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 816));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 817));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 818));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 819));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 820));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 821));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 822));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 823));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 824));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 825));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 826));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 827));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 828));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 829));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 830));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 831));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 832));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 833));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 834));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 835));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 836));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 837));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 838));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 839));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 840));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 841));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 842));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 843));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 844));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 845));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 846));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 847));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 848));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 849));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 850));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 851));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 852));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 853));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 854));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 855));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 856));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 857));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 858));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 859));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 860));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 861));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 862));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 863));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 864));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 865));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 866));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 867));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 868));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 869));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 870));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 871));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 872));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 873));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 874));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 875));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 876));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 877));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 878));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 879));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 880));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 881));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 882));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 883));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 884));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 885));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 886));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 887));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 888));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 889));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 890));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 891));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 892));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 893));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 894));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 895));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 896));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 897));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 898));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 899));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 900));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 901));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 902));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 903));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 904));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 905));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 906));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 907));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 908));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 909));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 910));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 911));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 912));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 913));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 914));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 915));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 916));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 917));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 918));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 919));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 920));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 921));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 922));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 923));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 924));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 925));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 926));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 927));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 928));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 929));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 930));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 931));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 932));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 933));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 934));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 935));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 936));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 937));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 938));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 939));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 940));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 941));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 942));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 943));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 944));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 945));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 946));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 947));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 948));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 949));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 950));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 951));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 952));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 953));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 954));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 955));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 956));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 957));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 958));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 959));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 960));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 961));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 962));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 963));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 964));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 965));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 966));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 967));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 968));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 969));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 970));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 971));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 972));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 973));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 974));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 975));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 976));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 977));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 978));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 979));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 980));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 981));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 982));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 983));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 984));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 985));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 986));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 987));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 988));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 989));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 990));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 991));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 992));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 993));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 994));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 995));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 996));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 997));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 998));
+  pointers.add(Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 999));
+
+  for (final pointer in pointers) {
+    CallbackTest("SimpleAddition", pointer).run();
+  }
+}
diff --git a/tests/ffi_2/function_callbacks_test.dart b/tests/ffi_2/function_callbacks_test.dart
new file mode 100644
index 0000000..24ca064
--- /dev/null
+++ b/tests/ffi_2/function_callbacks_test.dart
@@ -0,0 +1,224 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Dart test program for testing dart:ffi function pointers with callbacks.
+//
+// VMOptions=--enable-testing-pragmas
+// VMOptions=--enable-testing-pragmas --stacktrace-every=100
+// VMOptions=--enable-testing-pragmas --write-protect-code --no-dual-map-code
+// VMOptions=--enable-testing-pragmas --write-protect-code --no-dual-map-code --stacktrace-every=100
+// VMOptions=--use-slow-path --enable-testing-pragmas
+// VMOptions=--use-slow-path --enable-testing-pragmas --stacktrace-every=100
+// VMOptions=--use-slow-path --enable-testing-pragmas --write-protect-code --no-dual-map-code
+// VMOptions=--use-slow-path --enable-testing-pragmas --write-protect-code --no-dual-map-code --stacktrace-every=100
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'callback_tests_utils.dart';
+
+typedef SimpleAdditionType = Int32 Function(Int32, Int32);
+int simpleAddition(int x, int y) {
+  print("simpleAddition($x, $y)");
+  return x + y;
+}
+
+typedef IntComputationType = Int64 Function(Int8, Int16, Int32, Int64);
+int intComputation(int a, int b, int c, int d) {
+  print("intComputation($a, $b, $c, $d)");
+  return d - c + b - a;
+}
+
+typedef UintComputationType = Uint64 Function(Uint8, Uint16, Uint32, Uint64);
+int uintComputation(int a, int b, int c, int d) {
+  print("uintComputation($a, $b, $c, $d)");
+  return d - c + b - a;
+}
+
+typedef SimpleMultiplyType = Double Function(Double);
+double simpleMultiply(double x) {
+  print("simpleMultiply($x)");
+  return x * 1.337;
+}
+
+typedef SimpleMultiplyFloatType = Float Function(Float);
+double simpleMultiplyFloat(double x) {
+  print("simpleMultiplyFloat($x)");
+  return x * 1.337;
+}
+
+typedef ManyIntsType = IntPtr Function(IntPtr, IntPtr, IntPtr, IntPtr, IntPtr,
+    IntPtr, IntPtr, IntPtr, IntPtr, IntPtr);
+int manyInts(
+    int a, int b, int c, int d, int e, int f, int g, int h, int i, int j) {
+  print("manyInts($a, $b, $c, $d, $e, $f, $g, $h, $i, $j");
+  return a + b + c + d + e + f + g + h + i + j;
+}
+
+typedef ManyDoublesType = Double Function(Double, Double, Double, Double,
+    Double, Double, Double, Double, Double, Double);
+double manyDoubles(double a, double b, double c, double d, double e, double f,
+    double g, double h, double i, double j) {
+  print("manyDoubles($a, $b, $c, $d, $e, $f, $g, $h, $i, $j");
+  return a + b + c + d + e + f + g + h + i + j;
+}
+
+typedef ManyArgsType = Double Function(
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double);
+double manyArgs(
+    int _1,
+    double _2,
+    int _3,
+    double _4,
+    int _5,
+    double _6,
+    int _7,
+    double _8,
+    int _9,
+    double _10,
+    int _11,
+    double _12,
+    int _13,
+    double _14,
+    int _15,
+    double _16,
+    int _17,
+    double _18,
+    int _19,
+    double _20) {
+  print("manyArgs( $_1, $_2, $_3, $_4, $_5, $_6, $_7, $_8, $_9, $_10," +
+      "$_11, $_12, $_13, $_14, $_15, $_16, $_17, $_18, $_19, $_20)");
+  return _1 +
+      _2 +
+      _3 +
+      _4 +
+      _5 +
+      _6 +
+      _7 +
+      _8 +
+      _9 +
+      _10 +
+      _11 +
+      _12 +
+      _13 +
+      _14 +
+      _15 +
+      _16 +
+      _17 +
+      _18 +
+      _19 +
+      _20;
+}
+
+typedef StoreType = Pointer<Int64> Function(Pointer<Int64>);
+Pointer<Int64> store(Pointer<Int64> ptr) => ptr.elementAt(1)..value = 1337;
+
+typedef NullPointersType = Pointer<Int64> Function(Pointer<Int64>);
+Pointer<Int64> nullPointers(Pointer<Int64> ptr) => ptr.elementAt(1);
+
+typedef ReturnVoid = Void Function();
+void returnVoid() {}
+
+void throwException() {
+  throw "Exception.";
+}
+
+typedef ThrowExceptionInt = IntPtr Function();
+int throwExceptionInt() {
+  throw "Exception.";
+}
+
+typedef ThrowExceptionDouble = Double Function();
+double throwExceptionDouble() {
+  throw "Exception.";
+}
+
+typedef ThrowExceptionPointer = Pointer<Void> Function();
+Pointer<Void> throwExceptionPointer() {
+  throw "Exception.";
+}
+
+typedef TakeMaxUint8x10Type = IntPtr Function(
+    Uint8, Uint8, Uint8, Uint8, Uint8, Uint8, Uint8, Uint8, Uint8, Uint8);
+int takeMaxUint8x10(
+    int a, int b, int c, int d, int e, int f, int g, int h, int i, int j) {
+  print("takeMaxUint8x10($a, $b, $c, $d, $e, $f, $g, $h, $i, $j)");
+  return a == 0xff &&
+          b == 0xff &&
+          c == 0xff &&
+          d == 0xff &&
+          e == 0xff &&
+          f == 0xff &&
+          g == 0xff &&
+          h == 0xff &&
+          i == 0xff &&
+          j == 0xff
+      ? 1
+      : 0;
+}
+
+typedef ReturnMaxUint8Type = Uint8 Function();
+int returnMaxUint8() {
+  return 0xff;
+}
+
+int returnMaxUint8v2() {
+  return 0xabcff;
+}
+
+final testcases = [
+  CallbackTest("SimpleAddition",
+      Pointer.fromFunction<SimpleAdditionType>(simpleAddition, 0)),
+  CallbackTest("IntComputation",
+      Pointer.fromFunction<IntComputationType>(intComputation, 0)),
+  CallbackTest("UintComputation",
+      Pointer.fromFunction<UintComputationType>(uintComputation, 0)),
+  CallbackTest("SimpleMultiply",
+      Pointer.fromFunction<SimpleMultiplyType>(simpleMultiply, 0.0)),
+  CallbackTest("SimpleMultiplyFloat",
+      Pointer.fromFunction<SimpleMultiplyFloatType>(simpleMultiplyFloat, 0.0)),
+  CallbackTest("ManyInts", Pointer.fromFunction<ManyIntsType>(manyInts, 0)),
+  CallbackTest(
+      "ManyDoubles", Pointer.fromFunction<ManyDoublesType>(manyDoubles, 0.0)),
+  CallbackTest("ManyArgs", Pointer.fromFunction<ManyArgsType>(manyArgs, 0.0)),
+  CallbackTest("Store", Pointer.fromFunction<StoreType>(store)),
+  CallbackTest(
+      "NullPointers", Pointer.fromFunction<NullPointersType>(nullPointers)),
+  CallbackTest("ReturnVoid", Pointer.fromFunction<ReturnVoid>(returnVoid)),
+  CallbackTest("ThrowExceptionDouble",
+      Pointer.fromFunction<ThrowExceptionDouble>(throwExceptionDouble, 42.0)),
+  CallbackTest("ThrowExceptionPointer",
+      Pointer.fromFunction<ThrowExceptionPointer>(throwExceptionPointer)),
+  CallbackTest("ThrowException",
+      Pointer.fromFunction<ThrowExceptionInt>(throwExceptionInt, 42)),
+  CallbackTest("TakeMaxUint8x10",
+      Pointer.fromFunction<TakeMaxUint8x10Type>(takeMaxUint8x10, 0)),
+  CallbackTest("ReturnMaxUint8",
+      Pointer.fromFunction<ReturnMaxUint8Type>(returnMaxUint8, 0)),
+  CallbackTest("ReturnMaxUint8",
+      Pointer.fromFunction<ReturnMaxUint8Type>(returnMaxUint8v2, 0)),
+];
+
+void main() {
+  testcases.forEach((t) => t.run());
+}
diff --git a/tests/ffi_2/function_callbacks_very_many_test copy.dart b/tests/ffi_2/function_callbacks_very_many_test copy.dart
new file mode 100644
index 0000000..383b482
--- /dev/null
+++ b/tests/ffi_2/function_callbacks_very_many_test copy.dart
@@ -0,0 +1,295 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Dart test program for testing dart:ffi function pointers with callbacks.
+//
+// VMOptions=--deterministic --optimization-counter-threshold=10
+// VMOptions=--enable-testing-pragmas
+// VMOptions=--enable-testing-pragmas --stacktrace-every=100
+// VMOptions=--enable-testing-pragmas --write-protect-code --no-dual-map-code
+// VMOptions=--enable-testing-pragmas --write-protect-code --no-dual-map-code --stacktrace-every=100
+// VMOptions=--use-slow-path --enable-testing-pragmas
+// VMOptions=--use-slow-path --enable-testing-pragmas --stacktrace-every=100
+// VMOptions=--use-slow-path --enable-testing-pragmas --write-protect-code --no-dual-map-code
+// VMOptions=--use-slow-path --enable-testing-pragmas --write-protect-code --no-dual-map-code --stacktrace-every=100
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'callback_tests_utils.dart';
+
+final testcases = [
+  CallbackTest("SumVeryManySmallInts",
+      Pointer.fromFunction<NativeVeryManyIntsOp>(sumVeryManySmallInts, 0)),
+  CallbackTest(
+      "SumVeryManyFloatsDoubles",
+      Pointer.fromFunction<NativeVeryManyFloatsDoublesOp>(
+          sumVeryManyDoubles, 0.0)),
+];
+
+void main() {
+  for (int i = 0; i < 100; ++i) {
+    testcases.forEach((t) => t.run());
+  }
+}
+
+int sumVeryManySmallInts(
+    int _1,
+    int _2,
+    int _3,
+    int _4,
+    int _5,
+    int _6,
+    int _7,
+    int _8,
+    int _9,
+    int _10,
+    int _11,
+    int _12,
+    int _13,
+    int _14,
+    int _15,
+    int _16,
+    int _17,
+    int _18,
+    int _19,
+    int _20,
+    int _21,
+    int _22,
+    int _23,
+    int _24,
+    int _25,
+    int _26,
+    int _27,
+    int _28,
+    int _29,
+    int _30,
+    int _31,
+    int _32,
+    int _33,
+    int _34,
+    int _35,
+    int _36,
+    int _37,
+    int _38,
+    int _39,
+    int _40) {
+  print("sumVeryManySmallInts(" +
+      "$_1, $_2, $_3, $_4, $_5, $_6, $_7, $_8, $_9, $_10, " +
+      "$_11, $_12, $_13, $_14, $_15, $_16, $_17, $_18, $_19, $_20, " +
+      "$_21, $_22, $_23, $_24, $_25, $_26, $_27, $_28, $_29, $_30, " +
+      "$_31, $_32, $_33, $_34, $_35, $_36, $_37, $_38, $_39, $_40)");
+  return _1 +
+      _2 +
+      _3 +
+      _4 +
+      _5 +
+      _6 +
+      _7 +
+      _8 +
+      _9 +
+      _10 +
+      _11 +
+      _12 +
+      _13 +
+      _14 +
+      _15 +
+      _16 +
+      _17 +
+      _18 +
+      _19 +
+      _20 +
+      _21 +
+      _22 +
+      _23 +
+      _24 +
+      _25 +
+      _26 +
+      _27 +
+      _28 +
+      _29 +
+      _30 +
+      _31 +
+      _32 +
+      _33 +
+      _34 +
+      _35 +
+      _36 +
+      _37 +
+      _38 +
+      _39 +
+      _40;
+}
+
+double sumVeryManyDoubles(
+    double _1,
+    double _2,
+    double _3,
+    double _4,
+    double _5,
+    double _6,
+    double _7,
+    double _8,
+    double _9,
+    double _10,
+    double _11,
+    double _12,
+    double _13,
+    double _14,
+    double _15,
+    double _16,
+    double _17,
+    double _18,
+    double _19,
+    double _20,
+    double _21,
+    double _22,
+    double _23,
+    double _24,
+    double _25,
+    double _26,
+    double _27,
+    double _28,
+    double _29,
+    double _30,
+    double _31,
+    double _32,
+    double _33,
+    double _34,
+    double _35,
+    double _36,
+    double _37,
+    double _38,
+    double _39,
+    double _40) {
+  print("sumVeryManyDoubles(" +
+      "$_1, $_2, $_3, $_4, $_5, $_6, $_7, $_8, $_9, $_10, " +
+      "$_11, $_12, $_13, $_14, $_15, $_16, $_17, $_18, $_19, $_20, " +
+      "$_21, $_22, $_23, $_24, $_25, $_26, $_27, $_28, $_29, $_30, " +
+      "$_31, $_32, $_33, $_34, $_35, $_36, $_37, $_38, $_39, $_40)");
+  return _1 +
+      _2 +
+      _3 +
+      _4 +
+      _5 +
+      _6 +
+      _7 +
+      _8 +
+      _9 +
+      _10 +
+      _11 +
+      _12 +
+      _13 +
+      _14 +
+      _15 +
+      _16 +
+      _17 +
+      _18 +
+      _19 +
+      _20 +
+      _21 +
+      _22 +
+      _23 +
+      _24 +
+      _25 +
+      _26 +
+      _27 +
+      _28 +
+      _29 +
+      _30 +
+      _31 +
+      _32 +
+      _33 +
+      _34 +
+      _35 +
+      _36 +
+      _37 +
+      _38 +
+      _39 +
+      _40;
+}
+
+typedef NativeVeryManyIntsOp = Int16 Function(
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16);
+
+typedef NativeVeryManyFloatsDoublesOp = Double Function(
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double);
diff --git a/tests/ffi_2/function_callbacks_very_many_test.dart b/tests/ffi_2/function_callbacks_very_many_test.dart
new file mode 100644
index 0000000..383b482
--- /dev/null
+++ b/tests/ffi_2/function_callbacks_very_many_test.dart
@@ -0,0 +1,295 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Dart test program for testing dart:ffi function pointers with callbacks.
+//
+// VMOptions=--deterministic --optimization-counter-threshold=10
+// VMOptions=--enable-testing-pragmas
+// VMOptions=--enable-testing-pragmas --stacktrace-every=100
+// VMOptions=--enable-testing-pragmas --write-protect-code --no-dual-map-code
+// VMOptions=--enable-testing-pragmas --write-protect-code --no-dual-map-code --stacktrace-every=100
+// VMOptions=--use-slow-path --enable-testing-pragmas
+// VMOptions=--use-slow-path --enable-testing-pragmas --stacktrace-every=100
+// VMOptions=--use-slow-path --enable-testing-pragmas --write-protect-code --no-dual-map-code
+// VMOptions=--use-slow-path --enable-testing-pragmas --write-protect-code --no-dual-map-code --stacktrace-every=100
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'callback_tests_utils.dart';
+
+final testcases = [
+  CallbackTest("SumVeryManySmallInts",
+      Pointer.fromFunction<NativeVeryManyIntsOp>(sumVeryManySmallInts, 0)),
+  CallbackTest(
+      "SumVeryManyFloatsDoubles",
+      Pointer.fromFunction<NativeVeryManyFloatsDoublesOp>(
+          sumVeryManyDoubles, 0.0)),
+];
+
+void main() {
+  for (int i = 0; i < 100; ++i) {
+    testcases.forEach((t) => t.run());
+  }
+}
+
+int sumVeryManySmallInts(
+    int _1,
+    int _2,
+    int _3,
+    int _4,
+    int _5,
+    int _6,
+    int _7,
+    int _8,
+    int _9,
+    int _10,
+    int _11,
+    int _12,
+    int _13,
+    int _14,
+    int _15,
+    int _16,
+    int _17,
+    int _18,
+    int _19,
+    int _20,
+    int _21,
+    int _22,
+    int _23,
+    int _24,
+    int _25,
+    int _26,
+    int _27,
+    int _28,
+    int _29,
+    int _30,
+    int _31,
+    int _32,
+    int _33,
+    int _34,
+    int _35,
+    int _36,
+    int _37,
+    int _38,
+    int _39,
+    int _40) {
+  print("sumVeryManySmallInts(" +
+      "$_1, $_2, $_3, $_4, $_5, $_6, $_7, $_8, $_9, $_10, " +
+      "$_11, $_12, $_13, $_14, $_15, $_16, $_17, $_18, $_19, $_20, " +
+      "$_21, $_22, $_23, $_24, $_25, $_26, $_27, $_28, $_29, $_30, " +
+      "$_31, $_32, $_33, $_34, $_35, $_36, $_37, $_38, $_39, $_40)");
+  return _1 +
+      _2 +
+      _3 +
+      _4 +
+      _5 +
+      _6 +
+      _7 +
+      _8 +
+      _9 +
+      _10 +
+      _11 +
+      _12 +
+      _13 +
+      _14 +
+      _15 +
+      _16 +
+      _17 +
+      _18 +
+      _19 +
+      _20 +
+      _21 +
+      _22 +
+      _23 +
+      _24 +
+      _25 +
+      _26 +
+      _27 +
+      _28 +
+      _29 +
+      _30 +
+      _31 +
+      _32 +
+      _33 +
+      _34 +
+      _35 +
+      _36 +
+      _37 +
+      _38 +
+      _39 +
+      _40;
+}
+
+double sumVeryManyDoubles(
+    double _1,
+    double _2,
+    double _3,
+    double _4,
+    double _5,
+    double _6,
+    double _7,
+    double _8,
+    double _9,
+    double _10,
+    double _11,
+    double _12,
+    double _13,
+    double _14,
+    double _15,
+    double _16,
+    double _17,
+    double _18,
+    double _19,
+    double _20,
+    double _21,
+    double _22,
+    double _23,
+    double _24,
+    double _25,
+    double _26,
+    double _27,
+    double _28,
+    double _29,
+    double _30,
+    double _31,
+    double _32,
+    double _33,
+    double _34,
+    double _35,
+    double _36,
+    double _37,
+    double _38,
+    double _39,
+    double _40) {
+  print("sumVeryManyDoubles(" +
+      "$_1, $_2, $_3, $_4, $_5, $_6, $_7, $_8, $_9, $_10, " +
+      "$_11, $_12, $_13, $_14, $_15, $_16, $_17, $_18, $_19, $_20, " +
+      "$_21, $_22, $_23, $_24, $_25, $_26, $_27, $_28, $_29, $_30, " +
+      "$_31, $_32, $_33, $_34, $_35, $_36, $_37, $_38, $_39, $_40)");
+  return _1 +
+      _2 +
+      _3 +
+      _4 +
+      _5 +
+      _6 +
+      _7 +
+      _8 +
+      _9 +
+      _10 +
+      _11 +
+      _12 +
+      _13 +
+      _14 +
+      _15 +
+      _16 +
+      _17 +
+      _18 +
+      _19 +
+      _20 +
+      _21 +
+      _22 +
+      _23 +
+      _24 +
+      _25 +
+      _26 +
+      _27 +
+      _28 +
+      _29 +
+      _30 +
+      _31 +
+      _32 +
+      _33 +
+      _34 +
+      _35 +
+      _36 +
+      _37 +
+      _38 +
+      _39 +
+      _40;
+}
+
+typedef NativeVeryManyIntsOp = Int16 Function(
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16,
+    Int8,
+    Int16);
+
+typedef NativeVeryManyFloatsDoublesOp = Double Function(
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double,
+    Float,
+    Double);
diff --git a/tests/ffi_2/function_structs_test.dart b/tests/ffi_2/function_structs_test.dart
new file mode 100644
index 0000000..3738876
--- /dev/null
+++ b/tests/ffi_2/function_structs_test.dart
@@ -0,0 +1,118 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi function pointers with struct
+// arguments.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'dylib_utils.dart';
+
+import "package:expect/expect.dart";
+import "package:ffi/ffi.dart";
+
+import 'coordinate.dart';
+import 'very_large_struct.dart';
+
+typedef NativeCoordinateOp = Pointer<Coordinate> Function(Pointer<Coordinate>);
+
+void main() {
+  testFunctionWithStruct();
+  // testFunctionWithStructArray();
+  // testFunctionWithVeryLargeStruct();
+}
+
+DynamicLibrary ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+/// pass a struct to a c function and get a struct as return value
+void testFunctionWithStruct() {
+  Pointer<NativeFunction<NativeCoordinateOp>> p1 =
+      ffiTestFunctions.lookup("TransposeCoordinate");
+  NativeCoordinateOp f1 = p1.asFunction();
+
+  Pointer<Coordinate> c1 = Coordinate.allocate(10.0, 20.0, nullptr).addressOf;
+  Pointer<Coordinate> c2 = Coordinate.allocate(42.0, 84.0, c1).addressOf;
+  c1.ref.next = c2;
+
+  Coordinate result = f1(c1).ref;
+
+  Expect.approxEquals(20.0, c1.ref.x);
+  Expect.approxEquals(30.0, c1.ref.y);
+
+  Expect.approxEquals(42.0, result.x);
+  Expect.approxEquals(84.0, result.y);
+
+  free(c1);
+  free(c2);
+}
+
+/// pass an array of structs to a c funtion
+void testFunctionWithStructArray() {
+  Pointer<NativeFunction<NativeCoordinateOp>> p1 =
+      ffiTestFunctions.lookup("CoordinateElemAt1");
+  NativeCoordinateOp f1 = p1.asFunction();
+
+  Coordinate c1 = allocate<Coordinate>(count: 3).ref;
+  Coordinate c2 = c1.addressOf[1];
+  Coordinate c3 = c1.addressOf[2];
+  c1.x = 10.0;
+  c1.y = 10.0;
+  c1.next = c3.addressOf;
+  c2.x = 20.0;
+  c2.y = 20.0;
+  c2.next = c1.addressOf;
+  c3.x = 30.0;
+  c3.y = 30.0;
+  c3.next = c2.addressOf;
+
+  Coordinate result = f1(c1.addressOf).ref;
+  Expect.approxEquals(20.0, result.x);
+  Expect.approxEquals(20.0, result.y);
+
+  free(c1.addressOf);
+}
+
+typedef VeryLargeStructSum = int Function(Pointer<VeryLargeStruct>);
+typedef NativeVeryLargeStructSum = Int64 Function(Pointer<VeryLargeStruct>);
+
+void testFunctionWithVeryLargeStruct() {
+  Pointer<NativeFunction<NativeVeryLargeStructSum>> p1 =
+      ffiTestFunctions.lookup("SumVeryLargeStruct");
+  VeryLargeStructSum f = p1.asFunction();
+
+  VeryLargeStruct vls1 = allocate<VeryLargeStruct>(count: 2).ref;
+  VeryLargeStruct vls2 = vls1.addressOf[1];
+  List<VeryLargeStruct> structs = [vls1, vls2];
+  for (VeryLargeStruct struct in structs) {
+    struct.a = 1;
+    struct.b = 2;
+    struct.c = 4;
+    struct.d = 8;
+    struct.e = 16;
+    struct.f = 32;
+    struct.g = 64;
+    struct.h = 128;
+    struct.i = 256;
+    struct.j = 512;
+    struct.k = 1024;
+    struct.smallLastField = 1;
+  }
+  vls1.parent = vls2.addressOf;
+  vls1.numChildren = 2;
+  vls1.children = vls1.addressOf;
+  vls2.parent = vls2.addressOf;
+  vls2.parent = nullptr;
+  vls2.numChildren = 0;
+  vls2.children = nullptr;
+
+  int result = f(vls1.addressOf);
+  Expect.equals(2051, result);
+
+  result = f(vls2.addressOf);
+  Expect.equals(2048, result);
+
+  free(vls1.addressOf);
+}
diff --git a/tests/ffi_2/function_test.dart b/tests/ffi_2/function_test.dart
new file mode 100644
index 0000000..376711b
--- /dev/null
+++ b/tests/ffi_2/function_test.dart
@@ -0,0 +1,450 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi function pointers.
+//
+// VMOptions=
+// VMOptions=--deterministic --optimization-counter-threshold=10
+// VMOptions=--use-slow-path
+// VMOptions=--use-slow-path --stacktrace-every=100
+// VMOptions=--write-protect-code --no-dual-map-code
+// VMOptions=--write-protect-code --no-dual-map-code --use-slow-path
+// VMOptions=--write-protect-code --no-dual-map-code --stacktrace-every=100
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'dylib_utils.dart';
+
+import "package:ffi/ffi.dart";
+import "package:expect/expect.dart";
+
+void main() {
+  for (int i = 0; i < 100; ++i) {
+    testNativeFunctionFromCast();
+    testNativeFunctionFromLookup();
+    test64bitInterpretations();
+    testExtension();
+    testTruncation();
+    testNativeFunctionDoubles();
+    testNativeFunctionFloats();
+    testNativeFunctionManyArguments1();
+    testNativeFunctionManyArguments2();
+    testNativeFunctionManyArguments3();
+    testNativeFunctionManyArguments4();
+    testNativeFunctionManyArguments5();
+    testNativeFunctionPointer();
+    testNullPointers();
+    testFloatRounding();
+    testVoidReturn();
+    testNoArgs();
+  }
+}
+
+final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+typedef NativeBinaryOp = Int32 Function(Int32, Int32);
+typedef UnaryOp = int Function(int);
+typedef BinaryOp = int Function(int, int);
+typedef GenericBinaryOp<T> = int Function(int, T);
+
+void testNativeFunctionFromCast() {
+  Pointer<IntPtr> p1 = allocate();
+  Pointer<NativeFunction<NativeBinaryOp>> p2 = p1.cast();
+  p2.asFunction<BinaryOp>();
+  p2.asFunction<GenericBinaryOp<int>>();
+  free(p1);
+}
+
+typedef NativeQuadOpSigned = Int64 Function(Int8, Int16, Int32, Int64);
+typedef QuadOp = int Function(int, int, int, int);
+typedef NativeQuadOpUnsigned = Uint64 Function(Uint8, Uint16, Uint32, Uint64);
+
+BinaryOp sumPlus42 =
+    ffiTestFunctions.lookupFunction<NativeBinaryOp, BinaryOp>("SumPlus42");
+
+QuadOp intComputation = ffiTestFunctions
+    .lookupFunction<NativeQuadOpSigned, QuadOp>("IntComputation");
+
+void testNativeFunctionFromLookup() {
+  Expect.equals(49, sumPlus42(3, 4));
+
+  Expect.equals(625, intComputation(125, 250, 500, 1000));
+
+  Expect.equals(
+      0x7FFFFFFFFFFFFFFF, intComputation(0, 0, 0, 0x7FFFFFFFFFFFFFFF));
+  Expect.equals(
+      -0x8000000000000000, intComputation(0, 0, 0, -0x8000000000000000));
+}
+
+typedef NativeReturnMaxUint8 = Uint8 Function();
+int Function() returnMaxUint8 = ffiTestFunctions
+    .lookup("ReturnMaxUint8")
+    .cast<NativeFunction<NativeReturnMaxUint8>>()
+    .asFunction();
+int Function() returnMaxUint8v2 = ffiTestFunctions
+    .lookup("ReturnMaxUint8v2")
+    .cast<NativeFunction<NativeReturnMaxUint8>>()
+    .asFunction();
+
+typedef NativeReturnMaxUint16 = Uint16 Function();
+int Function() returnMaxUint16 = ffiTestFunctions
+    .lookup("ReturnMaxUint16")
+    .cast<NativeFunction<NativeReturnMaxUint16>>()
+    .asFunction();
+int Function() returnMaxUint16v2 = ffiTestFunctions
+    .lookup("ReturnMaxUint16v2")
+    .cast<NativeFunction<NativeReturnMaxUint16>>()
+    .asFunction();
+
+typedef NativeReturnMaxUint32 = Uint32 Function();
+int Function() returnMaxUint32 = ffiTestFunctions
+    .lookup("ReturnMaxUint32")
+    .cast<NativeFunction<NativeReturnMaxUint32>>()
+    .asFunction();
+int Function() returnMaxUint32v2 = ffiTestFunctions
+    .lookup("ReturnMaxUint32v2")
+    .cast<NativeFunction<NativeReturnMaxUint32>>()
+    .asFunction();
+
+typedef NativeReturnMinInt8 = Int8 Function();
+int Function() returnMinInt8 = ffiTestFunctions
+    .lookup("ReturnMinInt8")
+    .cast<NativeFunction<NativeReturnMinInt8>>()
+    .asFunction();
+int Function() returnMinInt8v2 = ffiTestFunctions
+    .lookup("ReturnMinInt8v2")
+    .cast<NativeFunction<NativeReturnMinInt8>>()
+    .asFunction();
+
+typedef NativeReturnMinInt16 = Int16 Function();
+int Function() returnMinInt16 = ffiTestFunctions
+    .lookup("ReturnMinInt16")
+    .cast<NativeFunction<NativeReturnMinInt16>>()
+    .asFunction();
+int Function() returnMinInt16v2 = ffiTestFunctions
+    .lookup("ReturnMinInt16v2")
+    .cast<NativeFunction<NativeReturnMinInt16>>()
+    .asFunction();
+
+typedef NativeReturnMinInt32 = Int32 Function();
+int Function() returnMinInt32 = ffiTestFunctions
+    .lookup("ReturnMinInt32")
+    .cast<NativeFunction<NativeReturnMinInt32>>()
+    .asFunction();
+int Function() returnMinInt32v2 = ffiTestFunctions
+    .lookup("ReturnMinInt32v2")
+    .cast<NativeFunction<NativeReturnMinInt32>>()
+    .asFunction();
+
+typedef NativeTakeMaxUint8 = IntPtr Function(Uint8);
+int Function(int) takeMaxUint8 = ffiTestFunctions
+    .lookup("TakeMaxUint8")
+    .cast<NativeFunction<NativeTakeMaxUint8>>()
+    .asFunction();
+
+typedef NativeTakeMaxUint16 = IntPtr Function(Uint16);
+int Function(int) takeMaxUint16 = ffiTestFunctions
+    .lookup("TakeMaxUint16")
+    .cast<NativeFunction<NativeTakeMaxUint16>>()
+    .asFunction();
+
+typedef NativeTakeMaxUint32 = IntPtr Function(Uint32);
+int Function(int) takeMaxUint32 = ffiTestFunctions
+    .lookup("TakeMaxUint32")
+    .cast<NativeFunction<NativeTakeMaxUint32>>()
+    .asFunction();
+
+typedef NativeTakeMinInt8 = IntPtr Function(Int8);
+int Function(int) takeMinInt8 = ffiTestFunctions
+    .lookup("TakeMinInt8")
+    .cast<NativeFunction<NativeTakeMinInt8>>()
+    .asFunction();
+
+typedef NativeTakeMinInt16 = IntPtr Function(Int16);
+int Function(int) takeMinInt16 = ffiTestFunctions
+    .lookup("TakeMinInt16")
+    .cast<NativeFunction<NativeTakeMinInt16>>()
+    .asFunction();
+
+typedef NativeTakeMinInt32 = IntPtr Function(Int32);
+int Function(int) takeMinInt32 = ffiTestFunctions
+    .lookup("TakeMinInt32")
+    .cast<NativeFunction<NativeTakeMinInt32>>()
+    .asFunction();
+
+typedef NativeTakeMaxUint8x10 = IntPtr Function(
+    Uint8, Uint8, Uint8, Uint8, Uint8, Uint8, Uint8, Uint8, Uint8, Uint8);
+int Function(int, int, int, int, int, int, int, int, int, int) takeMaxUint8x10 =
+    ffiTestFunctions
+        .lookup("TakeMaxUint8x10")
+        .cast<NativeFunction<NativeTakeMaxUint8x10>>()
+        .asFunction();
+
+void testExtension() {
+  // Sign extension on the way back to Dart.
+  Expect.equals(0xff, returnMaxUint8());
+  Expect.equals(0xffff, returnMaxUint16());
+  Expect.equals(0xffffffff, returnMaxUint32());
+  Expect.equals(-0x80, returnMinInt8());
+  Expect.equals(-0x8000, returnMinInt16());
+  Expect.equals(-0x80000000, returnMinInt32());
+  // Truncation in C, and sign extension back to Dart.
+  Expect.equals(0xff, returnMaxUint8v2());
+  Expect.equals(0xffff, returnMaxUint16v2());
+  Expect.equals(0xffffffff, returnMaxUint32v2());
+  Expect.equals(-0x80, returnMinInt8v2());
+  Expect.equals(-0x8000, returnMinInt16v2());
+  Expect.equals(-0x80000000, returnMinInt32v2());
+
+  // Upper bits propper, should work without truncation.
+  Expect.equals(1, takeMaxUint8(0xff));
+  Expect.equals(1, takeMaxUint16(0xffff));
+  Expect.equals(1, takeMaxUint32(0xffffffff));
+  Expect.equals(1, takeMinInt8(-0x80));
+  Expect.equals(1, takeMinInt16(-0x8000));
+  Expect.equals(1, takeMinInt32(-0x80000000));
+  Expect.equals(
+      1,
+      takeMaxUint8x10(
+          0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff));
+  // Upper bits garbage, needs to truncate.
+  Expect.equals(1, takeMaxUint8(0xabcff));
+  Expect.equals(1, takeMaxUint16(0xabcffff));
+  Expect.equals(1, takeMaxUint32(0xabcffffffff));
+  Expect.equals(1, takeMinInt8(0x8abc80));
+  Expect.equals(1, takeMinInt16(0x8abc8000));
+  Expect.equals(1, takeMinInt32(0x8abc80000000));
+  Expect.equals(
+      1,
+      takeMaxUint8x10(0xabcff, 0xabcff, 0xabcff, 0xabcff, 0xabcff, 0xabcff,
+          0xabcff, 0xabcff, 0xabcff, 0xabcff));
+}
+
+QuadOp uintComputation = ffiTestFunctions
+    .lookupFunction<NativeQuadOpUnsigned, QuadOp>("UintComputation");
+
+void test64bitInterpretations() {
+  // 2 ^ 63 - 1
+  Expect.equals(
+      0x7FFFFFFFFFFFFFFF, uintComputation(0, 0, 0, 0x7FFFFFFFFFFFFFFF));
+  // -2 ^ 63 interpreted as 2 ^ 63
+  Expect.equals(
+      -0x8000000000000000, uintComputation(0, 0, 0, -0x8000000000000000));
+  // -1 interpreted as 2 ^ 64 - 1
+  Expect.equals(-1, uintComputation(0, 0, 0, -1));
+}
+
+typedef NativeSenaryOp = Int64 Function(
+    Int8, Int16, Int32, Uint8, Uint16, Uint32);
+typedef SenaryOp = int Function(int, int, int, int, int, int);
+
+SenaryOp sumSmallNumbers = ffiTestFunctions
+    .lookupFunction<NativeSenaryOp, SenaryOp>("SumSmallNumbers");
+
+void testTruncation() {
+  sumSmallNumbers(128, 0, 0, 0, 0, 0);
+  sumSmallNumbers(-129, 0, 0, 0, 0, 0);
+  sumSmallNumbers(0, 0, 0, 256, 0, 0);
+  sumSmallNumbers(0, 0, 0, -1, 0, 0);
+
+  sumSmallNumbers(0, 0x8000, 0, 0, 0, 0);
+  sumSmallNumbers(0, 0xFFFFFFFFFFFF7FFF, 0, 0, 0, 0);
+  sumSmallNumbers(0, 0, 0, 0, 0x10000, 0);
+  sumSmallNumbers(0, 0, 0, 0, -1, 0);
+
+  Expect.equals(0xFFFFFFFF80000000, sumSmallNumbers(0, 0, 0x80000000, 0, 0, 0));
+  Expect.equals(
+      0x000000007FFFFFFF, sumSmallNumbers(0, 0, 0xFFFFFFFF7FFFFFFF, 0, 0, 0));
+  Expect.equals(0, sumSmallNumbers(0, 0, 0, 0, 0, 0x100000000));
+  Expect.equals(0xFFFFFFFF, sumSmallNumbers(0, 0, 0, 0, 0, -1));
+}
+
+typedef NativeDoubleUnaryOp = Double Function(Double);
+typedef DoubleUnaryOp = double Function(double);
+
+DoubleUnaryOp times1_337Double = ffiTestFunctions
+    .lookupFunction<NativeDoubleUnaryOp, DoubleUnaryOp>("Times1_337Double");
+
+void testNativeFunctionDoubles() {
+  Expect.approxEquals(2.0 * 1.337, times1_337Double(2.0));
+}
+
+typedef NativeFloatUnaryOp = Float Function(Float);
+
+DoubleUnaryOp times1_337Float = ffiTestFunctions
+    .lookupFunction<NativeFloatUnaryOp, DoubleUnaryOp>("Times1_337Float");
+
+void testNativeFunctionFloats() {
+  Expect.approxEquals(1337.0, times1_337Float(1000.0));
+}
+
+typedef NativeDecenaryOp = IntPtr Function(IntPtr, IntPtr, IntPtr, IntPtr,
+    IntPtr, IntPtr, IntPtr, IntPtr, IntPtr, IntPtr);
+typedef NativeDecenaryOp2 = Int16 Function(
+    Int8, Int16, Int8, Int16, Int8, Int16, Int8, Int16, Int8, Int16);
+typedef DecenaryOp = int Function(
+    int, int, int, int, int, int, int, int, int, int);
+
+DecenaryOp sumManyInts = ffiTestFunctions
+    .lookupFunction<NativeDecenaryOp, DecenaryOp>("SumManyInts");
+
+void testNativeFunctionManyArguments1() {
+  Expect.equals(55, sumManyInts(1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
+}
+
+DecenaryOp sumManySmallInts = ffiTestFunctions
+    .lookupFunction<NativeDecenaryOp2, DecenaryOp>("SumManySmallInts");
+
+void testNativeFunctionManyArguments5() {
+  Expect.equals(55, sumManySmallInts(1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
+}
+
+typedef NativeUndenaryOp = IntPtr Function(IntPtr, IntPtr, IntPtr, IntPtr,
+    IntPtr, IntPtr, IntPtr, IntPtr, IntPtr, IntPtr, IntPtr);
+typedef UndenaryOp = int Function(
+    int, int, int, int, int, int, int, int, int, int, int);
+
+UndenaryOp sumManyIntsOdd = ffiTestFunctions
+    .lookupFunction<NativeUndenaryOp, UndenaryOp>("SumManyIntsOdd");
+
+void testNativeFunctionManyArguments4() {
+  Expect.equals(66, sumManyIntsOdd(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11));
+}
+
+typedef NativeDoubleDecenaryOp = Double Function(Double, Double, Double, Double,
+    Double, Double, Double, Double, Double, Double);
+typedef DoubleDecenaryOp = double Function(double, double, double, double,
+    double, double, double, double, double, double);
+
+DoubleDecenaryOp sumManyDoubles = ffiTestFunctions
+    .lookupFunction<NativeDoubleDecenaryOp, DoubleDecenaryOp>("SumManyDoubles");
+
+void testNativeFunctionManyArguments2() {
+  Expect.approxEquals(
+      55.0, sumManyDoubles(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0));
+}
+
+typedef NativeVigesimalOp = Double Function(
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double);
+typedef VigesimalOp = double Function(
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double);
+
+VigesimalOp sumManyNumbers = ffiTestFunctions
+    .lookupFunction<NativeVigesimalOp, VigesimalOp>("SumManyNumbers");
+
+void testNativeFunctionManyArguments3() {
+  Expect.approxEquals(
+      210.0,
+      sumManyNumbers(1, 2.0, 3, 4.0, 5, 6.0, 7, 8.0, 9, 10.0, 11, 12.0, 13,
+          14.0, 15, 16.0, 17, 18.0, 19, 20.0));
+}
+
+typedef Int64PointerUnOp = Pointer<Int64> Function(Pointer<Int64>);
+
+Int64PointerUnOp assign1337Index1 = ffiTestFunctions
+    .lookupFunction<Int64PointerUnOp, Int64PointerUnOp>("Assign1337Index1");
+
+void testNativeFunctionPointer() {
+  Pointer<Int64> p2 = allocate(count: 2);
+  p2.value = 42;
+  p2[1] = 1000;
+  Pointer<Int64> result = assign1337Index1(p2);
+  Expect.equals(1337, result.value);
+  Expect.equals(1337, p2[1]);
+  Expect.equals(p2.elementAt(1).address, result.address);
+  free(p2);
+}
+
+Int64PointerUnOp nullableInt64ElemAt1 = ffiTestFunctions
+    .lookupFunction<Int64PointerUnOp, Int64PointerUnOp>("NullableInt64ElemAt1");
+
+void testNullPointers() {
+  Pointer<Int64> result = nullableInt64ElemAt1(nullptr);
+  Expect.equals(result, nullptr);
+
+  Pointer<Int64> p2 = allocate(count: 2);
+  result = nullableInt64ElemAt1(p2);
+  Expect.notEquals(result, nullptr);
+  free(p2);
+}
+
+typedef NativeFloatPointerToBool = Uint8 Function(Pointer<Float>);
+typedef FloatPointerToBool = int Function(Pointer<Float>);
+
+FloatPointerToBool isRoughly1337 = ffiTestFunctions.lookupFunction<
+    NativeFloatPointerToBool, FloatPointerToBool>("IsRoughly1337");
+
+void testFloatRounding() {
+  Pointer<Float> p2 = allocate();
+  p2.value = 1337.0;
+
+  int result = isRoughly1337(p2);
+  Expect.equals(1, result);
+
+  free(p2);
+}
+
+typedef NativeFloatToVoid = Void Function(Float);
+typedef DoubleToVoid = void Function(double);
+
+DoubleToVoid devNullFloat = ffiTestFunctions
+    .lookupFunction<NativeFloatToVoid, DoubleToVoid>("DevNullFloat");
+
+void testVoidReturn() {
+  devNullFloat(1337.0);
+
+  dynamic loseSignature = devNullFloat;
+  dynamic result = loseSignature(1337.0);
+  Expect.isNull(result);
+}
+
+typedef NativeVoidToFloat = Float Function();
+typedef VoidToDouble = double Function();
+
+VoidToDouble inventFloatValue = ffiTestFunctions
+    .lookupFunction<NativeVoidToFloat, VoidToDouble>("InventFloatValue");
+
+void testNoArgs() {
+  double result = inventFloatValue();
+  Expect.approxEquals(1337.0, result);
+}
diff --git a/tests/ffi_2/hardfp_test.dart b/tests/ffi_2/hardfp_test.dart
new file mode 100644
index 0000000..600e26b
--- /dev/null
+++ b/tests/ffi_2/hardfp_test.dart
@@ -0,0 +1,51 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi function pointers.
+//
+// VMOptions=
+// VMOptions=--deterministic --optimization-counter-threshold=10
+// VMOptions=--use-slow-path
+// VMOptions=--use-slow-path --stacktrace-every=100
+// VMOptions=--write-protect-code --no-dual-map-code
+// VMOptions=--write-protect-code --no-dual-map-code --use-slow-path
+// VMOptions=--write-protect-code --no-dual-map-code --stacktrace-every=100
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+
+import 'callback_tests_utils.dart';
+import 'dylib_utils.dart';
+
+void main() {
+  for (int i = 0; i < 100; ++i) {
+    testSumFloatsAndDoubles();
+    testSumFloatsAndDoublesCallback();
+  }
+}
+
+DynamicLibrary ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+final sumFloatsAndDoubles = ffiTestFunctions.lookupFunction<
+    Double Function(Float, Double, Float),
+    double Function(double, double, double)>("SumFloatsAndDoubles");
+
+void testSumFloatsAndDoubles() {
+  Expect.approxEquals(6.0, sumFloatsAndDoubles(1.0, 2.0, 3.0));
+}
+
+void testSumFloatsAndDoublesCallback() {
+  CallbackTest(
+          "SumFloatsAndDoubles",
+          Pointer.fromFunction<Double Function(Float, Double, Float)>(
+              sumFloatsAndDoublesDart, 0.0))
+      .run();
+}
+
+double sumFloatsAndDoublesDart(double a, double b, double c) {
+  print("sumFloatsAndDoublesDart($a, $b, $c)");
+  return a + b + c;
+}
diff --git a/tests/ffi_2/negative_function_test.dart b/tests/ffi_2/negative_function_test.dart
new file mode 100644
index 0000000..d96c17c
--- /dev/null
+++ b/tests/ffi_2/negative_function_test.dart
@@ -0,0 +1,83 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing error handling with dart:ffi functions.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi' as ffi;
+import 'dylib_utils.dart';
+import "package:expect/expect.dart";
+
+main() {
+  testWrongArity();
+  testWrongTypes();
+  testDynamicAsFunction();
+  testDynamicLookupFunction();
+}
+
+ffi.DynamicLibrary ffiTestFunctions =
+    dlopenPlatformSpecific("ffi_test_functions");
+
+typedef NativeBinaryOp = ffi.Int32 Function(ffi.Int32, ffi.Int32);
+typedef BinaryOp = int Function(int, int);
+
+typedef NativeUnaryOp = ffi.Int64 Function(ffi.Pointer<ffi.Int64>);
+typedef UnaryOp = int Function(ffi.Pointer<ffi.Int64>);
+
+void testWrongArity() {
+  {
+    dynamic sumPlus42 =
+        ffiTestFunctions.lookupFunction<NativeBinaryOp, BinaryOp>("SumPlus42");
+    Expect.throwsNoSuchMethodError(() => sumPlus42(10));
+    Expect.throwsNoSuchMethodError(() => sumPlus42(10, 11, 12));
+    Expect.throwsNoSuchMethodError(() => sumPlus42(10, 11, 12, y: 13));
+  }
+
+  {
+    Function sumPlus42 =
+        ffiTestFunctions.lookupFunction<NativeBinaryOp, BinaryOp>("SumPlus42");
+    Expect.throwsNoSuchMethodError(() => sumPlus42(10));
+    Expect.throwsNoSuchMethodError(() => sumPlus42(10, 11, 12));
+    Expect.throwsNoSuchMethodError(() => sumPlus42(10, 11, 12, y: 13));
+  }
+}
+
+void testWrongTypes() {
+  {
+    dynamic sumPlus42 =
+        ffiTestFunctions.lookupFunction<NativeBinaryOp, BinaryOp>("SumPlus42");
+    Expect.throwsTypeError(() => sumPlus42("abc", "def"));
+  }
+
+  {
+    Function sumPlus42 =
+        ffiTestFunctions.lookupFunction<NativeBinaryOp, BinaryOp>("SumPlus42");
+    Expect.throwsTypeError(() => sumPlus42("abc", "def"));
+  }
+
+  {
+    dynamic pointerOp = ffiTestFunctions
+        .lookupFunction<NativeUnaryOp, UnaryOp>("Assign1337Index1");
+    Expect.throwsTypeError(() => pointerOp(0));
+  }
+}
+
+// Test that invoking 'Pointer.asFunction' with a dynamic receiver type throws
+// an exception.
+void testDynamicAsFunction() {
+  dynamic x = ffi.nullptr.cast<ffi.NativeFunction<ffi.Void Function()>>();
+  Expect.throwsUnsupportedError(() {
+    x.asFunction<void Function()>();
+  });
+}
+
+// Test that invoking 'DynamicLibrary.lookupFunction' with a dynamic receiver
+// type throws an exception.
+void testDynamicLookupFunction() {
+  dynamic lib = ffiTestFunctions;
+  Expect.throwsUnsupportedError(() {
+    lib.lookupFunction<ffi.Void Function(), void Function()>("_");
+  });
+}
diff --git a/tests/ffi/null_regress_39068_test.dart b/tests/ffi_2/null_regress_39068_test.dart
similarity index 100%
rename from tests/ffi/null_regress_39068_test.dart
rename to tests/ffi_2/null_regress_39068_test.dart
diff --git a/tests/ffi/null_test.dart b/tests/ffi_2/null_test.dart
similarity index 100%
rename from tests/ffi/null_test.dart
rename to tests/ffi_2/null_test.dart
diff --git a/tests/ffi_2/prepare_flutter_bundle.dart b/tests/ffi_2/prepare_flutter_bundle.dart
new file mode 100644
index 0000000..83a4a42
--- /dev/null
+++ b/tests/ffi_2/prepare_flutter_bundle.dart
@@ -0,0 +1,204 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:io';
+
+import 'package:path/path.dart' as path;
+import 'package:args/args.dart';
+
+main(List<String> args) async {
+  if (args.length != 1) {
+    print('Usage ${Platform.executable} ${Platform.script} <output-dir>');
+    exit(1);
+  }
+
+  final sdkRoot =
+      path.canonicalize(path.join(Platform.script.path, '../../..'));
+  final flutterTestsDir = args.single;
+
+  print('Using SDK root: $sdkRoot');
+  final testFiles = <String>[];
+  final failedOrTimedOut = <String>[];
+  final filteredTests = <String>[];
+  await for (final testFile in listTestFiles(sdkRoot, filteredTests)) {
+    final duration = await run(sdkRoot, testFile);
+    if (duration != null && duration.inSeconds < 5) {
+      testFiles.add(testFile);
+    } else {
+      failedOrTimedOut.add(testFile);
+    }
+  }
+  testFiles.sort();
+  failedOrTimedOut.sort();
+  filteredTests.sort();
+
+  dumpTestList(testFiles, 'The following tests will be included:');
+  dumpTestList(failedOrTimedOut,
+      'The following tests will be excluded due to timeout or test failure:');
+  dumpTestList(
+      filteredTests,
+      'The following tests were filtered due to using '
+      'dart_api.h/async/DynamicLibrary.{process,executable}/...');
+
+  final allFiles = <String>{};
+  allFiles.add(path.join(sdkRoot, 'pkg/expect/lib/expect.dart'));
+  for (final testFile in testFiles) {
+    allFiles.add(testFile);
+    await addImportedFilesTo(allFiles, testFile);
+  }
+
+  await generateCleanDir(flutterTestsDir);
+
+  final dartTestsDir = path.join(flutterTestsDir, 'lib/src/generated');
+  await generateDartTests(dartTestsDir, allFiles, testFiles);
+
+  final ccDir = path.join(flutterTestsDir, 'ios/Classes');
+  await generateCLibs(sdkRoot, ccDir, allFiles, testFiles);
+
+  print('');
+  print('Please copy generated files into FFI flutter test application');
+  print('  * $dartTestsDir');
+  print('  * $ccDir');
+}
+
+void dumpTestList(List<String> testFiles, String message) {
+  if (testFiles.isEmpty) return;
+
+  print(message);
+  for (final testFile in testFiles) {
+    print('  ${path.basename(testFile)}');
+  }
+}
+
+final importRegExp = RegExp(r'''^import.*['"](.+)['"].*;''');
+
+Future addImportedFilesTo(Set<String> allFiles, String testFile) async {
+  final content = await File(testFile).readAsString();
+  for (final line in content.split('\n')) {
+    final match = importRegExp.matchAsPrefix(line);
+    if (match != null) {
+      final filename = match.group(1);
+      if (!filename.contains('dart:') &&
+          !filename.contains('package:expect') &&
+          !filename.contains('package:ffi')) {
+        final importedFile = Uri.file(testFile).resolve(filename).toFilePath();
+        if (allFiles.add(importedFile)) {
+          addImportedFilesTo(allFiles, importedFile);
+        }
+      }
+    }
+  }
+}
+
+Future generateCLibs(String sdkRoot, String destDir, Set<String> allFiles,
+    List<String> testFiles) async {
+  final dir = await generateCleanDir(destDir);
+
+  String destinationFile;
+
+  final lib1 =
+      path.join(sdkRoot, 'runtime/bin/ffi_test/ffi_test_dynamic_library.cc');
+  destinationFile =
+      path.join(dir.path, path.basename(lib1)).replaceAll('.cc', '.cpp');
+  File(destinationFile).writeAsStringSync(File(lib1).readAsStringSync());
+
+  final lib2 = path.join(sdkRoot, 'runtime/bin/ffi_test/ffi_test_functions.cc');
+  destinationFile =
+      path.join(dir.path, path.basename(lib2)).replaceAll('.cc', '.cpp');
+  File(destinationFile).writeAsStringSync(File(lib2).readAsStringSync());
+}
+
+String cleanDart(String content) {
+  return content.replaceAll('package:expect/expect.dart', 'expect.dart');
+}
+
+Future generateDartTests(
+    String destDir, Set<String> allFiles, List<String> testFiles) async {
+  final dir = await generateCleanDir(destDir);
+
+  final sink = File(path.join(dir.path, 'all.dart')).openWrite();
+  sink.writeln('import "dart:async";');
+  sink.writeln('');
+  for (int i = 0; i < testFiles.length; ++i) {
+    sink.writeln('import "${path.basename(testFiles[i])}" as main$i;');
+  }
+  sink.writeln('');
+  sink.writeln('Future invoke(dynamic fun) async {');
+  sink.writeln('  if (fun is void Function() || fun is Future Function()) {');
+  sink.writeln('    return await fun();');
+  sink.writeln('  } else {');
+  sink.writeln('    return await fun(<String>[]);');
+  sink.writeln('  }');
+  sink.writeln('}');
+  sink.writeln('');
+  sink.writeln('dynamic main() async {');
+  for (int i = 0; i < testFiles.length; ++i) {
+    sink.writeln('  await invoke(main$i.main);');
+  }
+  sink.writeln('}');
+  await sink.close();
+
+  for (final file in allFiles) {
+    File(path.join(dir.path, path.basename(file)))
+        .writeAsStringSync(cleanDart(File(file).readAsStringSync()));
+  }
+
+  File(path.join(dir.path, 'dylib_utils.dart')).writeAsStringSync('''
+import 'dart:ffi' as ffi;
+import 'dart:io' show Platform;
+
+ffi.DynamicLibrary dlopenPlatformSpecific(String name, {String path}) {
+  return Platform.isAndroid
+      ? ffi.DynamicLibrary.open('libffi_tests.so')
+      : ffi.DynamicLibrary.process();
+}
+''');
+}
+
+Stream<String> listTestFiles(
+    String sdkRoot, List<String> filteredTests) async* {
+  await for (final file in Directory(path.join(sdkRoot, 'tests/ffi')).list()) {
+    if (file is File && file.path.endsWith('_test.dart')) {
+      // These tests are VM specific and cannot necessarily be run on Flutter.
+      if (path.basename(file.path).startsWith('vmspecific_')) {
+        filteredTests.add(file.path);
+        continue;
+      }
+      // These tests use special features which are hard to test on Flutter.
+      final contents = file.readAsStringSync();
+      if (contents.contains(RegExp('//# .* compile-time error')) ||
+          contents.contains('DynamicLibrary.process') ||
+          contents.contains('DynamicLibrary.executable')) {
+        filteredTests.add(file.path);
+        continue;
+      }
+      yield file.path;
+    }
+  }
+}
+
+Future<Duration> run(String sdkRoot, String testFile) async {
+  final env = Map<String, String>.from(Platform.environment);
+  env['LD_LIBRARY_PATH'] = path.join(sdkRoot, 'out/ReleaseX64');
+  final sw = Stopwatch()..start();
+  final Process process = await Process.start(
+      Platform.executable, <String>[testFile],
+      environment: env);
+  final timer = Timer(const Duration(seconds: 3), () => process.kill());
+  process.stdout.listen((_) {});
+  process.stderr.listen((_) {});
+  if (await process.exitCode != 0) return null;
+  timer.cancel();
+  return sw.elapsed;
+}
+
+Future<Directory> generateCleanDir(String dirname) async {
+  final directory = Directory(dirname);
+  if (await directory.exists()) {
+    await directory.delete(recursive: true);
+  }
+  await directory.create(recursive: true);
+  return directory;
+}
diff --git a/tests/ffi_2/regress_37254_test.dart b/tests/ffi_2/regress_37254_test.dart
new file mode 100644
index 0000000..dcd42b9
--- /dev/null
+++ b/tests/ffi_2/regress_37254_test.dart
@@ -0,0 +1,259 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// This program tests interaction with generic Pointers.
+//
+// Notation used in following tables:
+// * static_type//dynamic_type
+// * P = Pointer
+// * I = Int8
+// * NT = NativeType
+//
+// Note #1: When NNBD is landed, implicit downcasts will be static errors.
+//
+// Note #2: When we switch to extension methods we will _only_ use the static
+//          type of the container.
+//
+// ===== a.value = b ======
+// Does a.value = b, where a and b have specific static and dynamic types: run
+// fine, fail at compile time, or fail at runtime?
+// =======================
+//                  b     P<I>//P<I>   P<NT>//P<I>           P<NT>//P<NT>
+// a
+// P<P<I>>//P<P<I>>     1 ok         2 implicit downcast   3 implicit downcast
+//                                     of argument:          of argument:
+//                                     static error          static error
+//
+// P<P<NT>>//P<P<I>>    4 ok         5 ok                  6 fail at runtime
+//
+// P<P<NT>>//P<P<NT>>   7 ok         8 ok                  9 ok
+//
+// ====== final c = a.value ======
+// What is the (inferred) static type and runtime type of `a.value`. Note that
+// we assume extension method here: on Pointer<PointerT>> { Pointer<T> load(); }
+// ================================
+// a                    a.value
+//                      inferred static type*//runtime type
+// P<P<I>>//P<P<I>>     P<I>//P<I>
+//
+// P<P<NT>>//P<P<I>>    P<NT>//P<I>
+//
+// P<P<NT>>//P<P<NT>>   P<NT>//P<NT>
+//
+// * The inferred static type when we get extension methods.
+//
+// ====== b = a.value ======
+// What happens when we try to assign the result of a.value to variable b with
+// a specific static type: runs fine, fails at compile time, or fails at runtime.
+// ==========================
+//                  b     P<I>                        P<NT>
+// a
+// P<P<I>>//P<P<I>>     1 ok                        2 ok
+//
+// P<P<NT>>//P<P<I>>    3 implicit downcast         4 ok
+//                        of returnvalue: ok
+//
+// P<P<NT>>//P<P<NT>>   5 implicit downcast         6 ok
+//                        of returnvalue: fail
+//                        at runtime
+//
+// These are the normal Dart assignment rules.
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+import "package:ffi/ffi.dart";
+
+// ===== a.value = b ======
+// The tests follow table cells left to right, top to bottom.
+void store1() {
+  final Pointer<Pointer<Int8>> a = allocate<Pointer<Int8>>();
+  final Pointer<Int8> b = allocate<Int8>();
+
+  a.value = b;
+
+  free(a);
+  free(b);
+}
+
+void store2() {
+  final Pointer<Pointer<Int8>> a = allocate<Pointer<Int8>>();
+  final Pointer<NativeType> b =
+      allocate<Int8>(); // Reified Pointer<Int8> at runtime.
+
+  // Successful implicit downcast of argument at runtime.
+  // Should succeed now, should statically be rejected when NNBD lands.
+  a.value = b;
+
+  free(a);
+  free(b);
+}
+
+void store3() {
+  final Pointer<Pointer<Int8>> a = allocate<Pointer<Int8>>();
+  final Pointer<NativeType> b = allocate<Int8>().cast<Pointer<NativeType>>();
+
+  // Failing implicit downcast of argument at runtime.
+  // Should fail now at runtime, should statically be rejected when NNBD lands.
+  Expect.throws(() {
+    a.value = b;
+  });
+
+  free(a);
+  free(b);
+}
+
+void store4() {
+  // Reified as Pointer<Pointer<Int8>> at runtime.
+  final Pointer<Pointer<NativeType>> a = allocate<Pointer<Int8>>();
+
+  final Pointer<Int8> b = allocate<Int8>();
+
+  a.value = b;
+
+  free(a);
+  free(b);
+}
+
+void store5() {
+  // Reified as Pointer<Pointer<Int8>> at runtime.
+  final Pointer<Pointer<NativeType>> a = allocate<Pointer<Int8>>();
+
+  final Pointer<NativeType> b =
+      allocate<Int8>(); // Reified as Pointer<Int8> at runtime.
+
+  a.value = b;
+
+  free(a);
+  free(b);
+}
+
+void store6() {
+  // Reified as Pointer<Pointer<Int8>> at runtime.
+  final Pointer<Pointer<NativeType>> a = allocate<Pointer<Int8>>();
+  final Pointer<NativeType> b = allocate<Int8>().cast<Pointer<NativeType>>();
+
+  // Fails on type check of argument.
+  Expect.throws(() {
+    a.value = b;
+  });
+
+  free(a);
+  free(b);
+}
+
+void store7() {
+  final Pointer<Pointer<NativeType>> a = allocate<Pointer<NativeType>>();
+  final Pointer<Int8> b = allocate<Int8>();
+
+  a.value = b;
+
+  free(a);
+  free(b);
+}
+
+void store8() {
+  final Pointer<Pointer<NativeType>> a = allocate<Pointer<NativeType>>();
+
+  // Reified as Pointer<Int8> at runtime.
+  final Pointer<NativeType> b = allocate<Int8>();
+
+  a.value = b;
+
+  free(a);
+  free(b);
+}
+
+void store9() {
+  final Pointer<Pointer<NativeType>> a = allocate<Pointer<NativeType>>();
+  final Pointer<NativeType> b = allocate<Int8>().cast<Pointer<NativeType>>();
+
+  a.value = b;
+
+  free(a);
+  free(b);
+}
+
+// ====== b = a.value ======
+// The tests follow table cells left to right, top to bottom.
+void load1() {
+  final Pointer<Pointer<Int8>> a = allocate<Pointer<Int8>>();
+
+  Pointer<Int8> b = a.value;
+  Expect.type<Pointer<Int8>>(b);
+
+  free(a);
+}
+
+void load2() {
+  final Pointer<Pointer<Int8>> a = allocate<Pointer<Int8>>();
+
+  Pointer<NativeType> b = a.value;
+  Expect.type<Pointer<Int8>>(b);
+
+  free(a);
+}
+
+void load3() {
+  // Reified as Pointer<Pointer<Int8>> at runtime.
+  final Pointer<Pointer<NativeType>> a = allocate<Pointer<Int8>>();
+
+  Pointer<Int8> b = a.value;
+  Expect.type<Pointer<Int8>>(b);
+
+  free(a);
+}
+
+void load4() {
+  // Reified as Pointer<Pointer<Int8>> at runtime.
+  final Pointer<Pointer<NativeType>> a = allocate<Pointer<Int8>>();
+
+  // Return value runtime type is Pointer<Int8>.
+  Pointer<NativeType> b = a.value;
+  Expect.type<Pointer<Int8>>(b);
+
+  free(a);
+}
+
+void load5() {
+  final Pointer<Pointer<NativeType>> a = allocate<Pointer<NativeType>>();
+
+  // Failing implicit downcast of return value at runtime.
+  // Should fail now at runtime, should statically be rejected when NNBD lands.
+  Expect.throws(() {
+    Pointer<Int8> b = a.value;
+  });
+
+  free(a);
+}
+
+void load6() {
+  final Pointer<Pointer<NativeType>> a = allocate<Pointer<NativeType>>();
+
+  Pointer<NativeType> b = a.value;
+  Expect.type<Pointer<NativeType>>(b);
+
+  free(a);
+}
+
+void main() {
+  // Trigger both the runtime entry and the IL in bytecode.
+  for (int i = 0; i < 100; i++) {
+    store1();
+    store2();
+    store3();
+    store4();
+    store5();
+    store6();
+    store7();
+    store8();
+    store9();
+    load1();
+    load2();
+    load3();
+    load4();
+    load5();
+    load6();
+  }
+}
diff --git a/tests/ffi_2/regress_39044_test.dart b/tests/ffi_2/regress_39044_test.dart
new file mode 100644
index 0000000..785500d
--- /dev/null
+++ b/tests/ffi_2/regress_39044_test.dart
@@ -0,0 +1,28 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Check that the optimizer does not fuse constants with different
+// representations.
+//
+// SharedObjects=ffi_test_functions
+
+import "dart:ffi";
+
+import "package:expect/expect.dart";
+
+import "dylib_utils.dart";
+
+main() {
+  final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+  final intComputation = ffiTestFunctions.lookupFunction<
+      Int64 Function(Int64, Int8), int Function(int, int)>("Regress39044");
+
+  // The arguments are the same Smi constant, however they are different sizes.
+  final result = intComputation(
+      /* dart::kUnboxedInt64 --> int64_t             */ 1,
+      /* dart::kUnboxedInt32 --> truncated to int8_t */ 1);
+
+  Expect.equals(0, result);
+}
diff --git a/tests/ffi_2/regress_39063_test.dart b/tests/ffi_2/regress_39063_test.dart
new file mode 100644
index 0000000..52dca18
--- /dev/null
+++ b/tests/ffi_2/regress_39063_test.dart
@@ -0,0 +1,69 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Check that the optimizer does not fuse constants with different
+// representations.
+//
+// SharedObjects=ffi_test_functions
+
+import "dart:ffi";
+
+import "package:expect/expect.dart";
+
+import "dylib_utils.dart";
+
+typedef VigesimalOp = double Function(
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double,
+    int,
+    double);
+
+typedef NativeVigesimalOp = Double Function(
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double,
+    IntPtr,
+    Float,
+    IntPtr,
+    Double);
+
+main() {
+  final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+  final sumManyNumbers = ffiTestFunctions
+      .lookupFunction<NativeVigesimalOp, VigesimalOp>("SumManyNumbers");
+
+  // Should not crash.
+  sumManyNumbers(1, 2.0, 3, 4.0, 5, 6.0, 7, 8.0, 9, 10.0, 11, 12.0, 13, 14.0,
+      15, 16.0, 17, 18.0, 19, 20.0);
+}
diff --git a/tests/ffi_2/regress_39885_test.dart b/tests/ffi_2/regress_39885_test.dart
new file mode 100644
index 0000000..7d960f2
--- /dev/null
+++ b/tests/ffi_2/regress_39885_test.dart
@@ -0,0 +1,14 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:ffi';
+import "package:ffi/ffi.dart" show allocate, free;
+
+main() {
+  final data = allocate<Uint8>(count: 3);
+  for (int i = 0; i < 3; ++i) {
+    data.elementAt(i).value = 1;
+  }
+  free(data);
+}
diff --git a/tests/ffi_2/sizeof_test.dart b/tests/ffi_2/sizeof_test.dart
new file mode 100644
index 0000000..fd02efc
--- /dev/null
+++ b/tests/ffi_2/sizeof_test.dart
@@ -0,0 +1,13 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+
+void main() async {
+  Expect.equals(true, 4 == sizeOf<Pointer>() || 8 == sizeOf<Pointer>());
+}
diff --git a/tests/ffi_2/snapshot_test.dart b/tests/ffi_2/snapshot_test.dart
new file mode 100644
index 0000000..b27b88b
--- /dev/null
+++ b/tests/ffi_2/snapshot_test.dart
@@ -0,0 +1,25 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// VMOptions=--enable-isolate-groups
+// VMOptions=--no-enable-isolate-groups
+//
+// Checks that the VM throws an appropriate exception when FFI objects are
+// passed between isolates.
+
+import 'dart:ffi';
+import 'dart:isolate';
+
+import 'package:expect/expect.dart';
+
+main(args) async {
+  try {
+    await Isolate.spawn(print, Pointer<Void>.fromAddress(1));
+  } catch (e) {
+    Expect.type<ArgumentError>(e);
+    return;
+  }
+
+  throw "Test didn't throw an exception!";
+}
diff --git a/tests/ffi_2/stacktrace_regress_37910_test.dart b/tests/ffi_2/stacktrace_regress_37910_test.dart
new file mode 100644
index 0000000..0a76648
--- /dev/null
+++ b/tests/ffi_2/stacktrace_regress_37910_test.dart
@@ -0,0 +1,24 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// VMOptions=--stacktrace_every=100
+
+import 'dart:ffi' as ffi;
+
+typedef fooFfi1Type = ffi.Int32 Function();
+int fooFfi1() {
+  int a = 0;
+  for (int i = 0; i < 1000; ++i) {
+    a += i;
+  }
+  return a;
+}
+
+int Function() foo1 = ffi.Pointer.fromFunction<fooFfi1Type>(fooFfi1, 0)
+    .cast<ffi.NativeFunction<fooFfi1Type>>()
+    .asFunction();
+
+main() {
+  foo1();
+}
diff --git a/tests/ffi_2/structs_test.dart b/tests/ffi_2/structs_test.dart
new file mode 100644
index 0000000..263d562
--- /dev/null
+++ b/tests/ffi_2/structs_test.dart
@@ -0,0 +1,133 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi struct pointers.
+//
+// VMOptions=--deterministic --optimization-counter-threshold=50 --enable-inlining-annotations
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+import "package:ffi/ffi.dart";
+
+import 'ffi_test_helpers.dart';
+import 'coordinate_bare.dart' as bare;
+import 'coordinate.dart';
+
+void main() {
+  for (int i = 0; i < 100; i++) {
+    testStructAllocate();
+    testStructFromAddress();
+    testStructWithNulls();
+    testBareStruct();
+    testTypeTest();
+    testUtf8();
+  }
+}
+
+/// allocates each coordinate separately in c memory
+void testStructAllocate() {
+  Pointer<Coordinate> c1 = Coordinate.allocate(10.0, 10.0, nullptr).addressOf;
+  Pointer<Coordinate> c2 = Coordinate.allocate(20.0, 20.0, c1).addressOf;
+  Pointer<Coordinate> c3 = Coordinate.allocate(30.0, 30.0, c2).addressOf;
+  c1.ref.next = c3;
+
+  Coordinate currentCoordinate = c1.ref;
+  Expect.equals(10.0, currentCoordinate.x);
+  currentCoordinate = currentCoordinate.next.ref;
+  Expect.equals(30.0, currentCoordinate.x);
+  currentCoordinate = currentCoordinate.next.ref;
+  Expect.equals(20.0, currentCoordinate.x);
+  currentCoordinate = currentCoordinate.next.ref;
+  Expect.equals(10.0, currentCoordinate.x);
+
+  free(c1);
+  free(c2);
+  free(c3);
+}
+
+/// allocates coordinates consecutively in c memory
+void testStructFromAddress() {
+  Pointer<Coordinate> c1 = allocate(count: 3);
+  Pointer<Coordinate> c2 = c1.elementAt(1);
+  Pointer<Coordinate> c3 = c1.elementAt(2);
+  c1.ref
+    ..x = 10.0
+    ..y = 10.0
+    ..next = c3;
+  c2.ref
+    ..x = 20.0
+    ..y = 20.0
+    ..next = c1;
+  c3.ref
+    ..x = 30.0
+    ..y = 30.0
+    ..next = c2;
+
+  Coordinate currentCoordinate = c1.ref;
+  Expect.equals(10.0, currentCoordinate.x);
+  currentCoordinate = currentCoordinate.next.ref;
+  Expect.equals(30.0, currentCoordinate.x);
+  currentCoordinate = currentCoordinate.next.ref;
+  Expect.equals(20.0, currentCoordinate.x);
+  currentCoordinate = currentCoordinate.next.ref;
+  Expect.equals(10.0, currentCoordinate.x);
+
+  free(c1);
+}
+
+void testStructWithNulls() {
+  Pointer<Coordinate> coordinate =
+      Coordinate.allocate(10.0, 10.0, nullptr).addressOf;
+  Expect.equals(coordinate.ref.next, nullptr);
+  coordinate.ref.next = coordinate;
+  Expect.notEquals(coordinate.ref.next, nullptr);
+  coordinate.ref.next = nullptr;
+  Expect.equals(coordinate.ref.next, nullptr);
+  free(coordinate);
+}
+
+void testBareStruct() {
+  int structSize = sizeOf<Double>() * 2 + sizeOf<IntPtr>();
+  bare.Coordinate c1 =
+      allocate<Uint8>(count: structSize * 3).cast<bare.Coordinate>().ref;
+  bare.Coordinate c2 =
+      c1.addressOf.offsetBy(structSize).cast<bare.Coordinate>().ref;
+  bare.Coordinate c3 =
+      c1.addressOf.offsetBy(structSize * 2).cast<bare.Coordinate>().ref;
+  c1.x = 10.0;
+  c1.y = 10.0;
+  c1.next = c3.addressOf;
+  c2.x = 20.0;
+  c2.y = 20.0;
+  c2.next = c1.addressOf;
+  c3.x = 30.0;
+  c3.y = 30.0;
+  c3.next = c2.addressOf;
+
+  bare.Coordinate currentCoordinate = c1;
+  Expect.equals(10.0, currentCoordinate.x);
+  currentCoordinate = currentCoordinate.next.ref;
+  Expect.equals(30.0, currentCoordinate.x);
+  currentCoordinate = currentCoordinate.next.ref;
+  Expect.equals(20.0, currentCoordinate.x);
+  currentCoordinate = currentCoordinate.next.ref;
+  Expect.equals(10.0, currentCoordinate.x);
+
+  free(c1.addressOf);
+}
+
+void testTypeTest() {
+  Coordinate c = Coordinate.allocate(10, 10, nullptr);
+  Expect.isTrue(c is Struct);
+  Expect.isTrue(c.addressOf is Pointer<Coordinate>);
+  free(c.addressOf);
+}
+
+void testUtf8() {
+  final String test = 'Hasta Mañana';
+  final Pointer<Utf8> medium = Utf8.toUtf8(test);
+  Expect.equals(test, Utf8.fromUtf8(medium));
+  free(medium);
+}
diff --git a/tests/ffi_2/variance_function_test.dart b/tests/ffi_2/variance_function_test.dart
new file mode 100644
index 0000000..d6e6378
--- /dev/null
+++ b/tests/ffi_2/variance_function_test.dart
@@ -0,0 +1,238 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// VMOptions=
+// VMOptions=--deterministic --optimization-counter-threshold=10
+// VMOptions=--use-slow-path
+// SharedObjects=ffi_test_functions
+//
+// This file tests subtyping relationships (at compile time and at runtime) of
+// parameters and return types of ffi trampolines and ffi callback trampolines.
+
+import 'dart:ffi';
+
+import 'dylib_utils.dart';
+
+import "package:expect/expect.dart";
+import "package:ffi/ffi.dart";
+
+typedef Int64PointerParamOpDart = void Function(Pointer<Int64>);
+typedef Int64PointerParamOp = Void Function(Pointer<Int64>);
+typedef NaTyPointerParamOpDart = void Function(Pointer<NativeType>);
+typedef NaTyPointerParamOp = Void Function(Pointer<NativeType>);
+typedef Int64PointerReturnOp = Pointer<Int64> Function();
+typedef NaTyPointerReturnOp = Pointer<NativeType> Function();
+
+final paramOpName = "NativeTypePointerParam";
+final returnOpName = "NativeTypePointerReturn";
+
+final DynamicLibrary ffiTestFunctions =
+    dlopenPlatformSpecific("ffi_test_functions");
+
+// =============================================
+// Tests calls from Dart to native (asFunction).
+// =============================================
+
+void paramInvariant1() {
+  final fp =
+      ffiTestFunctions.lookup<NativeFunction<Int64PointerParamOp>>(paramOpName);
+  final f = fp.asFunction<Int64PointerParamOpDart>();
+  final arg = allocate<Int64>();
+  f(arg);
+  free(arg);
+}
+
+void paramInvariant2() {
+  final fp =
+      ffiTestFunctions.lookup<NativeFunction<NaTyPointerParamOp>>(paramOpName);
+  final f = fp.asFunction<NaTyPointerParamOpDart>();
+  final arg = allocate<Int64>().cast<NativeType>();
+  Expect.type<Pointer<NativeType>>(arg);
+  f(arg);
+  free(arg);
+}
+
+// Pass a statically and dynamically subtyped argument.
+void paramSubtype1() {
+  final fp =
+      ffiTestFunctions.lookup<NativeFunction<NaTyPointerParamOp>>(paramOpName);
+  final f = fp.asFunction<NaTyPointerParamOpDart>();
+  final arg = allocate<Int64>();
+  Expect.type<Pointer<Int64>>(arg);
+  f(arg);
+  free(arg);
+}
+
+// Pass a statically subtyped but dynamically invariant argument.
+void paramSubtype2() {
+  final fp =
+      ffiTestFunctions.lookup<NativeFunction<NaTyPointerParamOp>>(paramOpName);
+  final f = fp.asFunction<NaTyPointerParamOpDart>();
+  final Pointer<NativeType> arg = allocate<Int64>();
+  Expect.type<Pointer<Int64>>(arg);
+  f(arg);
+  free(arg);
+}
+
+void returnInvariant1() {
+  final fp = ffiTestFunctions
+      .lookup<NativeFunction<Int64PointerReturnOp>>(returnOpName);
+  final f = fp.asFunction<Int64PointerReturnOp>();
+  final result = f();
+  Expect.type<Pointer<Int64>>(result);
+}
+
+void returnInvariant2() {
+  final fp = ffiTestFunctions
+      .lookup<NativeFunction<NaTyPointerReturnOp>>(returnOpName);
+  final f = fp.asFunction<NaTyPointerReturnOp>();
+  final result = f();
+  Expect.type<Pointer<NativeType>>(result);
+}
+
+void returnSubtype() {
+  final fp = ffiTestFunctions
+      .lookup<NativeFunction<Int64PointerReturnOp>>(returnOpName);
+  final f = fp.asFunction<Int64PointerReturnOp>();
+  final NaTyPointerReturnOp f2 = f;
+  Expect.type<Int64PointerReturnOp>(f2);
+  final result = f2();
+  Expect.type<Pointer<NativeType>>(result);
+}
+
+void functionArgumentVariance() {
+  final p = Pointer<
+      NativeFunction<
+          Pointer<NativeFunction<Pointer<Int8> Function(Pointer<NativeType>)>> Function(
+              Pointer<
+                  NativeFunction<
+                      Pointer<NativeType> Function(
+                          Pointer<Int8>)>>)>>.fromAddress(0x1234);
+  final f = p.asFunction<
+      Pointer<NativeFunction<Pointer<NativeType> Function(Pointer<Int8>)>> Function(
+          Pointer<
+              NativeFunction<Pointer<Int8> Function(Pointer<NativeType>)>>)>();
+}
+
+void asFunctionTests() {
+  for (int i = 0; i < 100; ++i) {
+    paramInvariant1(); // Parameter invariant: Pointer<Int64>.
+    paramInvariant2(); // Parameter invariant: Pointer<NativeType>.
+    paramSubtype1(); // Parameter statically and dynamically subtyped.
+    paramSubtype2(); // Parameter statically invariant, dynamically subtyped.
+    returnInvariant1(); // Return value invariant: Pointer<Int64>.
+    returnInvariant2(); // Return value invariant: Pointer<NativeType>.
+    returnSubtype(); // Return value static subtyped, dynamically invariant.
+    functionArgumentVariance(); // Check nested function signatures.
+  }
+}
+
+// =======================================================
+// Test with callbacks from native to Dart (fromFunction).
+// =======================================================
+
+typedef CallbackInt64PointerParamOpDart = void Function(
+    Pointer<NativeFunction<Int64PointerParamOp>>);
+typedef CallbackInt64PointerParamOp = Void Function(
+    Pointer<NativeFunction<Int64PointerParamOp>>);
+
+typedef CallbackNaTyPointerParamOpDart = void Function(
+    Pointer<NativeFunction<NaTyPointerParamOp>>);
+typedef CallbackNaTyPointerParamOp = Void Function(
+    Pointer<NativeFunction<NaTyPointerParamOp>>);
+
+typedef CallbackInt64PointerReturnOpDart = void Function(
+    Pointer<NativeFunction<Int64PointerReturnOp>>);
+typedef CallbackInt64PointerReturnOp = Void Function(
+    Pointer<NativeFunction<Int64PointerReturnOp>>);
+
+typedef CallbackNaTyPointerReturnOpDart = void Function(
+    Pointer<NativeFunction<NaTyPointerReturnOp>>);
+typedef CallbackNaTyPointerReturnOp = Void Function(
+    Pointer<NativeFunction<NaTyPointerReturnOp>>);
+
+final callbackParamOpName = "CallbackNativeTypePointerParam";
+final callbackReturnOpName = "CallbackNativeTypePointerReturn";
+
+void int64PointerParamOp(Pointer<Int64> p) {
+  p.value = 42;
+}
+
+void naTyPointerParamOp(Pointer<NativeType> p) {
+  final Pointer<Int8> asInt8 = p.cast();
+  asInt8.value = 42;
+}
+
+// Pointer to return to C when C calls back into Dart and asks for a Pointer.
+Pointer<Int64> data;
+
+Pointer<Int64> int64PointerReturnOp() {
+  return data;
+}
+
+Pointer<NativeType> naTyPointerReturnOp() {
+  return data;
+}
+
+void callbackParamInvariant1() {
+  final callback = ffiTestFunctions.lookupFunction<CallbackInt64PointerParamOp,
+      CallbackInt64PointerParamOpDart>(callbackParamOpName);
+  final fp = Pointer.fromFunction<Int64PointerParamOp>(int64PointerParamOp);
+  callback(fp);
+}
+
+void callbackParamInvariant2() {
+  final callback = ffiTestFunctions.lookupFunction<CallbackNaTyPointerParamOp,
+      CallbackNaTyPointerParamOpDart>(callbackParamOpName);
+  final fp = Pointer.fromFunction<NaTyPointerParamOp>(naTyPointerParamOp);
+  callback(fp);
+}
+
+void callbackParamImplictDowncast1() {
+  final callback = ffiTestFunctions.lookupFunction<CallbackNaTyPointerParamOp,
+      CallbackNaTyPointerParamOpDart>(callbackParamOpName);
+  final fp = Pointer.fromFunction<Int64PointerParamOp>(int64PointerParamOp);
+  Expect.throws(() {
+    callback(fp);
+  });
+}
+
+void callbackParamSubtype1() {
+  final callback = ffiTestFunctions.lookupFunction<CallbackNaTyPointerParamOp,
+      CallbackNaTyPointerParamOpDart>(callbackParamOpName);
+  final fp = Pointer.fromFunction<NaTyPointerParamOp>(int64PointerParamOp);
+  callback(fp);
+}
+
+void callbackReturnInvariant1() {
+  final callback = ffiTestFunctions.lookupFunction<CallbackInt64PointerReturnOp,
+      CallbackInt64PointerReturnOpDart>(callbackReturnOpName);
+  final fp = Pointer.fromFunction<Int64PointerReturnOp>(int64PointerReturnOp);
+  callback(fp);
+}
+
+void callbackReturnInvariant2() {
+  final callback = ffiTestFunctions.lookupFunction<CallbackNaTyPointerReturnOp,
+      CallbackNaTyPointerReturnOpDart>(callbackReturnOpName);
+  final fp = Pointer.fromFunction<NaTyPointerReturnOp>(naTyPointerReturnOp);
+  callback(fp);
+}
+
+void fromFunctionTests() {
+  data = allocate();
+  for (int i = 0; i < 100; ++i) {
+    callbackParamInvariant1(); // Pointer<Int64> invariant
+    callbackParamInvariant2(); // Pointer<NativeType> invariant
+    callbackParamImplictDowncast1(); // static and dynamically supertyped
+    callbackParamSubtype1(); // static and dynamically subtyped
+    callbackReturnInvariant1(); // Pointer<Int64> invariant
+    callbackReturnInvariant2(); // Pointer<NativeType> invariant
+  }
+  free(data);
+}
+
+void main() {
+  asFunctionTests();
+  fromFunctionTests();
+}
diff --git a/tests/ffi_2/very_large_struct.dart b/tests/ffi_2/very_large_struct.dart
new file mode 100644
index 0000000..ca29143
--- /dev/null
+++ b/tests/ffi_2/very_large_struct.dart
@@ -0,0 +1,51 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:ffi';
+
+/// Large sample struct for dart:ffi library.
+class VeryLargeStruct extends Struct {
+  @Int8()
+  int a;
+
+  @Int16()
+  int b;
+
+  @Int32()
+  int c;
+
+  @Int64()
+  int d;
+
+  @Uint8()
+  int e;
+
+  @Uint16()
+  int f;
+
+  @Uint32()
+  int g;
+
+  @Uint64()
+  int h;
+
+  @IntPtr()
+  int i;
+
+  @Double()
+  double j;
+
+  @Float()
+  double k;
+
+  Pointer<VeryLargeStruct> parent;
+
+  @IntPtr()
+  int numChildren;
+
+  Pointer<VeryLargeStruct> children;
+
+  @Int8()
+  int smallLastField;
+}
diff --git a/tests/ffi_2/vmspecific_dynamic_library_test.dart b/tests/ffi_2/vmspecific_dynamic_library_test.dart
new file mode 100644
index 0000000..c15f850
--- /dev/null
+++ b/tests/ffi_2/vmspecific_dynamic_library_test.dart
@@ -0,0 +1,89 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi dynamic library loading.
+//
+// SharedObjects=ffi_test_dynamic_library ffi_test_functions
+
+import 'dart:io';
+import 'dart:ffi';
+
+import 'package:expect/expect.dart';
+
+import 'dylib_utils.dart';
+
+void main() {
+  testOpen();
+  testOpenError();
+  testLookup();
+  testLookupError();
+  testToString();
+  testEquality();
+  testHandle();
+}
+
+void testOpen() {
+  DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
+}
+
+void testOpenError() {
+  Expect.throws(
+      () => dlopenPlatformSpecific("doesnotexistforsurelibrary123409876"));
+}
+
+typedef NativeDoubleUnOp = Double Function(Double);
+
+typedef DoubleUnOp = double Function(double);
+
+void testLookup() {
+  DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
+  var timesFour = l.lookupFunction<NativeDoubleUnOp, DoubleUnOp>("timesFour");
+  Expect.approxEquals(12.0, timesFour(3));
+
+  if (Platform.isMacOS ||
+      Platform.isIOS ||
+      Platform.isAndroid ||
+      Platform.isLinux) {
+    // Lookup a symbol from 'libc' since it's loaded with global visibility.
+    DynamicLibrary p = DynamicLibrary.process();
+    Expect.isTrue(p.lookup<Void>("strcmp") != nullptr);
+  } else {
+    Expect.throws<UnsupportedError>(() => DynamicLibrary.process());
+  }
+
+  DynamicLibrary e = DynamicLibrary.executable();
+  Expect.isTrue(e.lookup("Dart_Invoke") != nullptr);
+}
+
+void testLookupError() {
+  DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
+  Expect.throws(() => l.lookupFunction<NativeDoubleUnOp, DoubleUnOp>(
+      "functionnamethatdoesnotexistforsure749237593845"));
+}
+
+void testToString() {
+  DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
+  Expect.stringEquals(
+      "DynamicLibrary: handle=0x", l.toString().substring(0, 25));
+}
+
+void testEquality() {
+  DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
+  DynamicLibrary l2 = dlopenPlatformSpecific("ffi_test_dynamic_library");
+  Expect.equals(l, l2);
+  Expect.equals(l.hashCode, l2.hashCode);
+  DynamicLibrary l3 = dlopenPlatformSpecific("ffi_test_functions");
+  Expect.notEquals(l, l3);
+}
+
+void testHandle() {
+  DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
+  DynamicLibrary l2 = dlopenPlatformSpecific("ffi_test_dynamic_library");
+  Pointer<Void> h = l.handle;
+  Pointer<Void> h2 = l2.handle;
+  Expect.equals(h, h2);
+  DynamicLibrary l3 = dlopenPlatformSpecific("ffi_test_functions");
+  Pointer<Void> h3 = l3.handle;
+  Expect.notEquals(h, h3);
+}
diff --git a/tests/ffi_2/vmspecific_enable_ffi_test.dart b/tests/ffi_2/vmspecific_enable_ffi_test.dart
new file mode 100644
index 0000000..f44753d
--- /dev/null
+++ b/tests/ffi_2/vmspecific_enable_ffi_test.dart
@@ -0,0 +1,17 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing the --enable-ffi=false flag.
+//
+// VMOptions=--enable-ffi=false
+
+import 'dart:ffi'; //# 01: compile-time error
+import 'package:ffi/ffi.dart'; //# 01: compile-time error
+
+void main() {
+  Pointer<Int8> p = //# 01: compile-time error
+      allocate(); //# 01: compile-time error
+  print(p.address); //# 01: compile-time error
+  free(p); //# 01: compile-time error
+}
diff --git a/tests/ffi_2/vmspecific_function_callbacks_exit_test.dart b/tests/ffi_2/vmspecific_function_callbacks_exit_test.dart
new file mode 100644
index 0000000..e7f33a2
--- /dev/null
+++ b/tests/ffi_2/vmspecific_function_callbacks_exit_test.dart
@@ -0,0 +1,64 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi function pointers with callbacks.
+//
+// VMOptions=
+// VMOptions=--use-slow-path
+// SharedObjects=ffi_test_functions
+import 'dart:io';
+import 'dart:ffi';
+import 'dart:isolate';
+
+import "package:expect/expect.dart";
+
+import 'callback_tests_utils.dart';
+import 'dylib_utils.dart';
+
+final testLibrary = dlopenPlatformSpecific("ffi_test_functions");
+
+typedef ReturnVoid = Void Function();
+void returnVoid() {}
+testCallbackWrongThread() {
+  print("Test CallbackWrongThread.");
+  CallbackTest(
+          "CallbackWrongThread", Pointer.fromFunction<ReturnVoid>(returnVoid))
+      .run();
+}
+
+testCallbackOutsideIsolate() {
+  print("Test CallbackOutsideIsolate.");
+  CallbackTest("CallbackOutsideIsolate",
+          Pointer.fromFunction<ReturnVoid>(returnVoid))
+      .run();
+}
+
+isolateHelper(int callbackPointer) {
+  final Pointer<Void> ptr = Pointer.fromAddress(callbackPointer);
+  final NativeCallbackTestFn tester =
+      testLibrary.lookupFunction<NativeCallbackTest, NativeCallbackTestFn>(
+          "TestCallbackWrongIsolate");
+  Expect.equals(0, tester(ptr));
+}
+
+testCallbackWrongIsolate() async {
+  final int callbackPointer =
+      Pointer.fromFunction<ReturnVoid>(returnVoid).address;
+  final ReceivePort exitPort = ReceivePort();
+  await Isolate.spawn(isolateHelper, callbackPointer,
+      errorsAreFatal: true, onExit: exitPort.sendPort);
+  await exitPort.first;
+}
+
+void main() async {
+  // These tests terminate the process after successful completion, so we have
+  // to run them separately.
+  //
+  // Since they use signal handlers they only run on Linux.
+  if (Platform.isLinux && !const bool.fromEnvironment("dart.vm.product")) {
+    testCallbackWrongThread(); //# 01: ok
+    testCallbackOutsideIsolate(); //# 02: ok
+    await testCallbackWrongIsolate(); //# 03: ok
+  }
+}
diff --git a/tests/ffi_2/vmspecific_function_callbacks_negative_test.dart b/tests/ffi_2/vmspecific_function_callbacks_negative_test.dart
new file mode 100644
index 0000000..067cec4
--- /dev/null
+++ b/tests/ffi_2/vmspecific_function_callbacks_negative_test.dart
@@ -0,0 +1,26 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi function pointers with callbacks.
+
+import 'dart:ffi';
+
+import 'dylib_utils.dart';
+
+final DynamicLibrary testLibrary = dlopenPlatformSpecific("ffi_test_functions");
+
+// Correct type of exceptionalReturn argument to Pointer.fromFunction.
+double testExceptionalReturn() {
+  Pointer.fromFunction<Double Function()>(returnVoid, null); //# 59: compile-time error
+  Pointer.fromFunction<Void Function()>(returnVoid, 0); //# 60: compile-time error
+  Pointer.fromFunction<Double Function()>(testExceptionalReturn, "abc"); //# 61: compile-time error
+  Pointer.fromFunction<Double Function()>(testExceptionalReturn, 0); //# 62: compile-time error
+  Pointer.fromFunction<Double Function()>(testExceptionalReturn); //# 63: compile-time error
+
+  return 0.0; // not used
+}
+
+void main() {
+  testExceptionalReturn();
+}
diff --git a/tests/ffi_2/vmspecific_function_callbacks_test.dart b/tests/ffi_2/vmspecific_function_callbacks_test.dart
new file mode 100644
index 0000000..99a036b
--- /dev/null
+++ b/tests/ffi_2/vmspecific_function_callbacks_test.dart
@@ -0,0 +1,63 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// VMOptions=--enable-testing-pragmas --enable-isolate-groups
+// VMOptions=--enable-testing-pragmas --no-enable-isolate-groups
+//
+// Dart test program for testing dart:ffi function pointers with callbacks.
+//
+// VMOptions=--enable-testing-pragmas
+// VMOptions=--enable-testing-pragmas --stacktrace-every=100
+// VMOptions=--enable-testing-pragmas --write-protect-code --no-dual-map-code
+// VMOptions=--enable-testing-pragmas --write-protect-code --no-dual-map-code --stacktrace-every=100
+// VMOptions=--use-slow-path --enable-testing-pragmas
+// VMOptions=--use-slow-path --enable-testing-pragmas --stacktrace-every=100
+// VMOptions=--use-slow-path --enable-testing-pragmas --write-protect-code --no-dual-map-code
+// VMOptions=--use-slow-path --enable-testing-pragmas --write-protect-code --no-dual-map-code --stacktrace-every=100
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'ffi_test_helpers.dart';
+import 'callback_tests_utils.dart';
+import 'dylib_utils.dart';
+
+typedef ReturnVoid = Void Function();
+
+final testLibrary = dlopenPlatformSpecific("ffi_test_functions");
+
+void testGC() {
+  triggerGc();
+}
+
+typedef WaitForHelperNative = Void Function(Pointer<Void>);
+typedef WaitForHelper = void Function(Pointer<Void>);
+
+void waitForHelper(Pointer<Void> helper) {
+  print("helper: $helper");
+  testLibrary.lookupFunction<WaitForHelperNative, WaitForHelper>(
+      "WaitForHelper")(helper);
+}
+
+final testcases = [
+  CallbackTest("GC", Pointer.fromFunction<ReturnVoid>(testGC)),
+  CallbackTest("UnprotectCode",
+      Pointer.fromFunction<WaitForHelperNative>(waitForHelper)),
+];
+
+const double zeroPointZero = 0.0;
+
+// Correct type of exceptionalReturn argument to Pointer.fromFunction.
+double testExceptionalReturn() {
+  Pointer.fromFunction<Double Function()>(testExceptionalReturn, 0.0);
+  Pointer.fromFunction<Double Function()>(testExceptionalReturn, zeroPointZero);
+
+  return 0.0;
+}
+
+void main() {
+  testExceptionalReturn();
+
+  testcases.forEach((t) => t.run());
+}
diff --git a/tests/ffi_2/vmspecific_function_gc_test.dart b/tests/ffi_2/vmspecific_function_gc_test.dart
new file mode 100644
index 0000000..e104bcc
--- /dev/null
+++ b/tests/ffi_2/vmspecific_function_gc_test.dart
@@ -0,0 +1,121 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// VMOptions=--deterministic --optimization-counter-threshold=500 --enable-testing-pragmas
+// VMOptions=--deterministic --optimization-counter-threshold=-1 --enable-testing-pragmas
+// VMOptions=--deterministic --optimization-counter-threshold=500 --enable-testing-pragmas --no-dual-map-code --write-protect-code
+// VMOptions=--deterministic --optimization-counter-threshold=-1 --enable-testing-pragmas --no-dual-map-code --write-protect-code
+// VMOptions=--enable-testing-pragmas --no-dual-map-code --write-protect-code
+// VMOptions=--enable-testing-pragmas --no-dual-map-code --write-protect-code --stacktrace-every=100
+//
+// Dart test program for stress-testing boxing and GC in return paths from FFI
+// trampolines.
+//
+// NOTE: This test does not produce useful stderr when it fails because the
+// stderr is redirected to a file for reflection.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi' as ffi;
+import "package:expect/expect.dart";
+import 'ffi_test_helpers.dart';
+
+main() async {
+  testBoxInt64();
+  testBoxInt32();
+  testBoxDouble();
+  testBoxPointer();
+  testAllocateInNative();
+  testRegress37069();
+  testWriteProtection();
+}
+
+typedef NativeNullaryOp64 = ffi.Int64 Function();
+typedef NativeNullaryOp32 = ffi.Int32 Function();
+typedef NativeNullaryOpDouble = ffi.Double Function();
+typedef NativeNullaryOpPtr = ffi.Pointer<ffi.Void> Function();
+typedef NativeUnaryOp = ffi.Void Function(ffi.Uint64);
+typedef NativeUndenaryOp = ffi.Uint64 Function(
+    ffi.Uint64,
+    ffi.Uint64,
+    ffi.Uint64,
+    ffi.Uint64,
+    ffi.Uint64,
+    ffi.Uint64,
+    ffi.Uint64,
+    ffi.Uint64,
+    ffi.Uint64,
+    ffi.Uint64,
+    ffi.Uint64);
+typedef NullaryOp = int Function();
+typedef NullaryOpDbl = double Function();
+typedef NullaryOpPtr = ffi.Pointer<ffi.Void> Function();
+typedef UnaryOp = void Function(int);
+typedef UndenaryOp = int Function(
+    int, int, int, int, int, int, int, int, int, int, int);
+
+//// These functions return values that require boxing into different types.
+
+final minInt64 =
+    ffiTestFunctions.lookupFunction<NativeNullaryOp64, NullaryOp>("MinInt64");
+
+// Forces boxing into Mint on all platforms.
+void testBoxInt64() {
+  Expect.equals(0x8000000000000000, minInt64());
+}
+
+NullaryOp minInt32 =
+    ffiTestFunctions.lookupFunction<NativeNullaryOp32, NullaryOp>("MinInt32");
+
+// Forces boxing into Mint on 32-bit platforms only.
+void testBoxInt32() {
+  Expect.equals(-0x80000000, minInt32());
+}
+
+final smallDouble = ffiTestFunctions
+    .lookupFunction<NativeNullaryOpDouble, NullaryOpDbl>("SmallDouble");
+
+// Forces boxing into Double.
+void testBoxDouble() {
+  Expect.equals(0x80000000 * -1.0, smallDouble());
+}
+
+final largePointer = ffiTestFunctions
+    .lookupFunction<NativeNullaryOpPtr, NullaryOpPtr>("LargePointer");
+
+// Forces boxing into ffi.Pointer and ffi.Mint.
+void testBoxPointer() {
+  ffi.Pointer pointer = largePointer();
+  if (ffi.sizeOf<ffi.Pointer>() == 4) {
+    Expect.equals(0x82000000, pointer.address);
+  } else {
+    Expect.equals(0x8100000082000000, pointer.address);
+  }
+}
+
+// Test GC in the FFI call path by calling a C function which triggers GC
+// directly.
+void testAllocateInNative() => triggerGc();
+
+// This also works as a regression test for 37176.
+
+final regress37069 = ffiTestFunctions
+    .lookupFunction<NativeUndenaryOp, UndenaryOp>("Regress37069");
+
+// Test GC in the FFI call path by calling a C function which triggers GC
+// directly.
+void testRegress37069() {
+  regress37069(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11);
+}
+
+final unprotectCode = ffiTestFunctions.lookupFunction<
+    ffi.Pointer<ffi.Void> Function(ffi.Pointer<ffi.Void>),
+    ffi.Pointer<ffi.Void> Function(ffi.Pointer<ffi.Void>)>("TestUnprotectCode");
+final waitForHelper = ffiTestFunctions.lookupFunction<
+    ffi.Void Function(ffi.Pointer<ffi.Void>),
+    void Function(ffi.Pointer<ffi.Void>)>("WaitForHelper");
+
+void testWriteProtection() {
+  waitForHelper(unprotectCode(ffi.nullptr));
+}
diff --git a/tests/ffi_2/vmspecific_function_test.dart b/tests/ffi_2/vmspecific_function_test.dart
new file mode 100644
index 0000000..00ea922
--- /dev/null
+++ b/tests/ffi_2/vmspecific_function_test.dart
@@ -0,0 +1,40 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi function pointers.
+//
+// VMOptions=
+// VMOptions=--deterministic --optimization-counter-threshold=10
+// VMOptions=--use-slow-path
+// VMOptions=--use-slow-path --stacktrace-every=100
+// VMOptions=--write-protect-code --no-dual-map-code
+// VMOptions=--write-protect-code --no-dual-map-code --use-slow-path
+// VMOptions=--write-protect-code --no-dual-map-code --stacktrace-every=100
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'dylib_utils.dart';
+
+import "package:ffi/ffi.dart";
+import "package:expect/expect.dart";
+
+void main() {
+  for (int i = 0; i < 100; ++i) {
+    testLookupFunctionPointerNativeType();
+  }
+}
+
+final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+typedef NativeTypeNFT = Pointer<NativeType> Function(
+    Pointer<Pointer<NativeType>>, Int8);
+typedef NativeTypeFT = Pointer<NativeType> Function(
+    Pointer<Pointer<NativeType>>, int);
+
+void testLookupFunctionPointerNativeType() {
+  // The function signature does not match up, but that does not matter since
+  // this test does not use the trampoline.
+  ffiTestFunctions.lookupFunction<NativeTypeNFT, NativeTypeFT>("LargePointer");
+}
diff --git a/tests/ffi_2/vmspecific_highmem_32bit_test.dart b/tests/ffi_2/vmspecific_highmem_32bit_test.dart
new file mode 100644
index 0000000..eeee5fa
--- /dev/null
+++ b/tests/ffi_2/vmspecific_highmem_32bit_test.dart
@@ -0,0 +1,133 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file
+
+import 'dart:ffi';
+import 'dart:io';
+import 'dart:typed_data';
+
+import 'package:expect/expect.dart';
+
+import 'ffi_test_helpers.dart';
+
+// void* mmap(void* addr, size_t length,
+//            int prot, int flags,
+//            int fd, off_t offset)
+typedef MMapNative = Pointer<Uint8> Function(Pointer<Uint8> address, IntPtr len,
+    IntPtr prot, IntPtr flags, IntPtr fd, IntPtr offset);
+typedef MMap = Pointer<Uint8> Function(
+    Pointer<Uint8> address, int len, int prot, int flags, int fd, int offset);
+final mmap = processSymbols.lookupFunction<MMapNative, MMap>('mmap');
+
+// int munmap(void *addr, size_t length)
+typedef MUnMapNative = IntPtr Function(Pointer<Uint8> address, IntPtr len);
+typedef MUnMap = int Function(Pointer<Uint8> address, int len);
+final munmap = processSymbols.lookupFunction<MUnMapNative, MUnMap>('munmap');
+
+final processSymbols = DynamicLibrary.process();
+
+const int kProtRead = 1;
+const int kProtWrite = 2;
+
+const int kMapPrivate = 2;
+const int kMapFixed = 16;
+final int kMapAnonymous = Platform.isMacOS ? 0x1000 : 0x20;
+
+const int kMapFailed = -1;
+
+// On 32-bit platforms the upper 4 bytes should be ignored.
+const int kIgnoreBytesPositive = 0x1122334400000000;
+const int kIgnoreBytesNegative = 0xffddccbb00000000;
+
+void swapBytes(
+    Pointer<Uint8> memoryView, int indexOffset, int indexA, int indexB) {
+  final int oldA = memoryView[indexOffset + indexA];
+  memoryView[indexOffset + indexA] = memoryView[indexOffset + indexB];
+  memoryView[indexOffset + indexB] = oldA;
+}
+
+void testLoadsAndStores(int indexOffset, Pointer<Uint8> memory) {
+  for (int i = 0; i < 10; ++i) {
+    memory[indexOffset + i] = 10 + i;
+  }
+  Expect.listEquals(<int>[10, 11, 12, 13, 14, 15, 16, 17, 18, 19],
+      memory.offsetBy(indexOffset).asTypedList(10));
+
+  for (int i = 0; i < 9; ++i) {
+    swapBytes(memory, indexOffset + 0, i, i + 1);
+  }
+  Expect.listEquals(<int>[11, 12, 13, 14, 15, 16, 17, 18, 19, 10],
+      memory.offsetBy(indexOffset).asTypedList(10));
+  for (int i = 0; i < 9; ++i) {
+    swapBytes(memory, indexOffset + kIgnoreBytesPositive, i, i + 1);
+  }
+  Expect.listEquals(<int>[12, 13, 14, 15, 16, 17, 18, 19, 10, 11],
+      memory.offsetBy(indexOffset).asTypedList(10));
+  for (int i = 0; i < 9; ++i) {
+    swapBytes(memory, indexOffset + kIgnoreBytesNegative, i, i + 1);
+  }
+  Expect.listEquals(<int>[13, 14, 15, 16, 17, 18, 19, 10, 11, 12],
+      memory.offsetBy(indexOffset).asTypedList(10));
+}
+
+void testOnHighOrLowMemory(Pointer<Uint8> memory, int indexOffset) {
+  testLoadsAndStores(indexOffset, memory);
+  testLoadsAndStores(indexOffset, memory.offsetBy(5));
+  testLoadsAndStores(indexOffset, memory.offsetBy(-5));
+  testLoadsAndStores(indexOffset, memory.offsetBy(kIgnoreBytesPositive + 5));
+  testLoadsAndStores(indexOffset, memory.offsetBy(kIgnoreBytesNegative + 5));
+  testLoadsAndStores(indexOffset, memory.offsetBy(kIgnoreBytesPositive - 5));
+  testLoadsAndStores(indexOffset, memory.offsetBy(kIgnoreBytesNegative - 5));
+  final m2 = Pointer<Uint8>.fromAddress(kIgnoreBytesPositive + memory.address);
+  Expect.equals(memory, m2); //# 01: ok
+  Expect.equals(memory.address, m2.address); //# 01: ok
+  testLoadsAndStores(indexOffset, m2);
+  final m3 = Pointer<Uint8>.fromAddress(kIgnoreBytesNegative + memory.address);
+  Expect.equals(memory, m3); //# 01: ok
+  Expect.equals(memory.address, m3.address); //# 01: ok
+  testLoadsAndStores(indexOffset, m3);
+}
+
+const int kPageSize = 4096;
+
+withMMapedAddress(
+    Pointer<Uint8> fixedAddress, void fun(Pointer<Uint8> address)) {
+  final result = mmap(fixedAddress, kPageSize, kProtRead | kProtWrite,
+      kMapAnonymous | kMapFixed | kMapPrivate, 0, 0);
+  if (result.address == kMapFailed) {
+    throw 'Could not mmap @0x${fixedAddress.address.toRadixString(16)}!';
+  }
+  Expect.equals(fixedAddress, result); //# 01: ok
+  Expect.equals(fixedAddress.address, result.address); //# 01: ok
+  try {
+    fun(result);
+  } finally {
+    if (munmap(result, kPageSize) != 0) {
+      throw 'Failed to unmap memory!';
+    }
+  }
+}
+
+main() {
+  final bool is32BitProcess = sizeOf<Pointer<Uint8>>() == 4;
+
+  // User space processes usually have
+  //   * the lower 3 GB available on Linux/Android on 32bit OS
+  //   * full 4 GB available on Linux/Android on 64bit OS
+  //   * full 4 GB available on MacOS
+  // So we choose high and low addresses that fall into lower 3 GB.
+  if (is32BitProcess && !Platform.isWindows) {
+    final highMemoryAddress = Pointer<Uint8>.fromAddress(0xaaaa0000);
+    final lowMemoryAddress = Pointer<Uint8>.fromAddress(0x11110000);
+    withMMapedAddress(lowMemoryAddress, (Pointer<Uint8> lowMemory) {
+      withMMapedAddress(highMemoryAddress, (Pointer<Uint8> highMemory) {
+        testOnHighOrLowMemory(lowMemory, 2048);
+        testOnHighOrLowMemory(highMemory, 2048);
+        testOnHighOrLowMemory(
+            lowMemory, 2048 + highMemory.address - lowMemory.address);
+        testOnHighOrLowMemory(
+            highMemory, 2048 + lowMemory.address - highMemory.address);
+      });
+    });
+  }
+}
diff --git a/tests/ffi/vmspecific_null_test.dart b/tests/ffi_2/vmspecific_null_test.dart
similarity index 100%
rename from tests/ffi/vmspecific_null_test.dart
rename to tests/ffi_2/vmspecific_null_test.dart
diff --git a/tests/ffi_2/vmspecific_object_gc_test.dart b/tests/ffi_2/vmspecific_object_gc_test.dart
new file mode 100644
index 0000000..c1d9f9c
--- /dev/null
+++ b/tests/ffi_2/vmspecific_object_gc_test.dart
@@ -0,0 +1,34 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Tests GC of Pointer objects.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+
+import 'dylib_utils.dart';
+
+DynamicLibrary ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+final triggerGc = ffiTestFunctions
+    .lookupFunction<Void Function(), void Function()>("TriggerGC");
+
+void main() async {
+  testGC();
+}
+
+dynamic bar;
+
+Future<void> testGC() async {
+  bar = Pointer<Int8>.fromAddress(11);
+
+  // Verify that the objects manufactured by 'fromAddress' can be scanned by the
+  // GC.
+  triggerGc();
+
+  Expect.equals(11, bar.address);
+}
diff --git a/tests/ffi_2/vmspecific_regress_37100_test.dart b/tests/ffi_2/vmspecific_regress_37100_test.dart
new file mode 100644
index 0000000..a819503
--- /dev/null
+++ b/tests/ffi_2/vmspecific_regress_37100_test.dart
@@ -0,0 +1,25 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+
+import 'dylib_utils.dart';
+
+class EVP_MD extends Struct {}
+
+DynamicLibrary ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+final EVP_sha1 = ffiTestFunctions.lookupFunction<Pointer<EVP_MD> Function(),
+    Pointer<EVP_MD> Function()>('LargePointer');
+
+main() {
+  int result = EVP_sha1().address;
+  // On 32 bit only the lowest 32 bits are returned, so only test those.
+  result &= 0x00000000FFFFFFFF;
+  Expect.equals(0x0000000082000000, result);
+}
diff --git a/tests/ffi_2/vmspecific_regress_37511_callbacks_test.dart b/tests/ffi_2/vmspecific_regress_37511_callbacks_test.dart
new file mode 100644
index 0000000..0153560
--- /dev/null
+++ b/tests/ffi_2/vmspecific_regress_37511_callbacks_test.dart
@@ -0,0 +1,52 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi struct pointers.
+//
+// VMOptions=--deterministic --enable-testing-pragmas
+//
+// SharedObjects=ffi_test_functions
+//
+// TODO(37295): Merge this file with regress_37511_test.dart when callback
+// support lands.
+
+import 'dart:ffi';
+
+import 'ffi_test_helpers.dart';
+
+/// Estimate of how many allocations functions in `functionsToTest` do at most.
+const gcAfterNAllocationsMax = 10;
+
+void main() {
+  for (Function() f in functionsToTest) {
+    f(); // Ensure code is compiled.
+
+    for (int n = 1; n <= gcAfterNAllocationsMax; n++) {
+      collectOnNthAllocation(n);
+      f();
+    }
+  }
+}
+
+final List<Function()> functionsToTest = [
+  // Callback trampolines.
+  doFromFunction,
+  () => callbackSmallDouble(dartFunctionPointer),
+];
+
+// Callback trampoline helpers.
+typedef NativeCallbackTest = Int32 Function(Pointer);
+typedef NativeCallbackTestFn = int Function(Pointer);
+
+final callbackSmallDouble =
+    ffiTestFunctions.lookupFunction<NativeCallbackTest, NativeCallbackTestFn>(
+        "TestSimpleMultiply");
+
+typedef SimpleMultiplyType = Double Function(Double);
+double simpleMultiply(double x) => x * 1.337;
+
+final doFromFunction =
+    () => Pointer.fromFunction<SimpleMultiplyType>(simpleMultiply, 0.0);
+
+final dartFunctionPointer = doFromFunction();
diff --git a/tests/ffi_2/vmspecific_regress_37511_test.dart b/tests/ffi_2/vmspecific_regress_37511_test.dart
new file mode 100644
index 0000000..6d857e5
--- /dev/null
+++ b/tests/ffi_2/vmspecific_regress_37511_test.dart
@@ -0,0 +1,106 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi struct pointers.
+//
+// VMOptions=--deterministic --enable-testing-pragmas
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'dylib_utils.dart';
+import 'ffi_test_helpers.dart';
+
+/// Estimate of how many allocations functions in `functionsToTest` do at most.
+const gcAfterNAllocationsMax = 10;
+
+void main() {
+  for (Function() f in functionsToTest) {
+    f(); // Ensure code is compiled.
+
+    for (int n = 1; n <= gcAfterNAllocationsMax; n++) {
+      collectOnNthAllocation(n);
+      f();
+    }
+  }
+}
+
+final List<Function()> functionsToTest = [
+  // Pointer operations.
+  () => highAddressPointer.cast<Double>(),
+  () => Pointer.fromAddress(highAddressPointer.address),
+  () => highAddressPointer.address,
+  () => highAddressPointer.elementAt(1),
+  () => highAddressPointer.offsetBy(1),
+  () => highAddressPointer.asTypedList(1),
+
+  // DynamicLibrary operations.
+  doDlopen,
+  doDlsym, // Includes `asFunction`.
+  () => ffiTestFunctions.handle,
+
+  // Trampolines.
+  () => sumManyIntsOdd(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, mint64bit),
+  () => sumManyDoubles(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0),
+  minInt64,
+  minInt32,
+  smallDouble,
+  largePointer,
+
+  // Callback trampolines.
+  //
+  // In regress_37511_callbacks_test.dart because callbacks are not supported
+  // in AOT yet.
+];
+
+// Pointer operation helpers.
+const mint32bit = 0xFFFFFFF0;
+const mint64bit = 0x7FFFFFFFFFFFFFF0;
+
+final int highAddress = sizeOf<IntPtr>() == 4 ? mint32bit : mint64bit;
+
+final Pointer<Int64> highAddressPointer = Pointer.fromAddress(highAddress);
+
+// Dynamic library operation helpers.
+final doDlopen = () => dlopenPlatformSpecific("ffi_test_functions");
+
+final doDlsym = () => ffiTestFunctions
+    .lookupFunction<NativeNullaryOp, NullaryOpVoid>("TriggerGC");
+
+// Trampoline helpers.
+typedef NativeUndenaryOp = IntPtr Function(IntPtr, IntPtr, IntPtr, IntPtr,
+    IntPtr, IntPtr, IntPtr, IntPtr, IntPtr, IntPtr, IntPtr);
+typedef UndenaryOp = int Function(
+    int, int, int, int, int, int, int, int, int, int, int);
+
+final UndenaryOp sumManyIntsOdd = ffiTestFunctions
+    .lookupFunction<NativeUndenaryOp, UndenaryOp>("SumManyIntsOdd");
+
+typedef NativeDoubleDecenaryOp = Double Function(Double, Double, Double, Double,
+    Double, Double, Double, Double, Double, Double);
+typedef DoubleDecenaryOp = double Function(double, double, double, double,
+    double, double, double, double, double, double);
+
+final DoubleDecenaryOp sumManyDoubles = ffiTestFunctions
+    .lookupFunction<NativeDoubleDecenaryOp, DoubleDecenaryOp>("SumManyDoubles");
+
+typedef NativeNullaryOp64 = Int64 Function();
+typedef NativeNullaryOp32 = Int32 Function();
+typedef NativeNullaryOpDouble = Double Function();
+typedef NullaryOpPtr = Pointer<Void> Function();
+typedef NullaryOp = int Function();
+typedef NullaryOpDbl = double Function();
+
+final minInt64 =
+    ffiTestFunctions.lookupFunction<NativeNullaryOp64, NullaryOp>("MinInt64");
+
+final minInt32 =
+    ffiTestFunctions.lookupFunction<NativeNullaryOp32, NullaryOp>("MinInt32");
+
+final smallDouble = ffiTestFunctions
+    .lookupFunction<NativeNullaryOpDouble, NullaryOpDbl>("SmallDouble");
+
+final largePointer =
+    ffiTestFunctions.lookupFunction<NullaryOpPtr, NullaryOpPtr>("LargePointer");
diff --git a/tests/ffi_2/vmspecific_regress_37780_test.dart b/tests/ffi_2/vmspecific_regress_37780_test.dart
new file mode 100644
index 0000000..a6b9f7e
--- /dev/null
+++ b/tests/ffi_2/vmspecific_regress_37780_test.dart
@@ -0,0 +1,20 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'dylib_utils.dart';
+
+DynamicLibrary ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+final triggerGc = ffiTestFunctions
+    .lookupFunction<Void Function(), void Function()>("TriggerGC");
+
+main(List<String> args) {
+  final foo = [Float(), Double(), Uint8()];
+  triggerGc();
+  print(foo);
+}
diff --git a/tests/ffi_2/vmspecific_regress_38993_test.dart b/tests/ffi_2/vmspecific_regress_38993_test.dart
new file mode 100644
index 0000000..8c9972f
--- /dev/null
+++ b/tests/ffi_2/vmspecific_regress_38993_test.dart
@@ -0,0 +1,13 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Tests a compile time error that should not crash the analyzer or CFE.
+
+import "dart:ffi";
+
+class C extends Struct {
+  dynamic x; //# 1: compile-time error
+}
+
+main() {}
diff --git a/tests/ffi_2/vmspecific_send_port_id_test.dart b/tests/ffi_2/vmspecific_send_port_id_test.dart
new file mode 100644
index 0000000..abe7ccc
--- /dev/null
+++ b/tests/ffi_2/vmspecific_send_port_id_test.dart
@@ -0,0 +1,37 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:ffi';
+import 'dart:isolate';
+
+import 'package:expect/expect.dart';
+
+typedef Dart_PostIntegerNFT = IntPtr Function(Int64 port, Int64 message);
+typedef Dart_PostIntegerFT = int Function(int port, int message);
+
+main() async {
+  const int message = 112344556677888;
+
+  final completer = Completer();
+
+  final receivePort = ReceivePort()
+    ..listen((receivedMessage) => completer.complete(receivedMessage));
+
+  final executableSymbols = DynamicLibrary.executable();
+
+  final postInteger =
+      executableSymbols.lookupFunction<Dart_PostIntegerNFT, Dart_PostIntegerFT>(
+          "Dart_PostInteger");
+
+  // Issue(dartbug.com/38545): The dart:ffi doesn't have a bool type yet.
+  final bool success =
+      postInteger(receivePort.sendPort.nativePort, message) != 0;
+  Expect.isTrue(success);
+
+  final postedMessage = await completer.future;
+  Expect.equals(message, postedMessage);
+
+  receivePort.close();
+}
diff --git a/tests/ffi_2/vmspecific_static_checks_test.dart b/tests/ffi_2/vmspecific_static_checks_test.dart
new file mode 100644
index 0000000..410f33f
--- /dev/null
+++ b/tests/ffi_2/vmspecific_static_checks_test.dart
@@ -0,0 +1,449 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// Dart test program for testing dart:ffi extra checks
+//
+// SharedObjects=ffi_test_dynamic_library
+
+import 'dart:ffi';
+
+import "package:ffi/ffi.dart";
+
+import 'dylib_utils.dart';
+
+void main() {
+  testGetGeneric();
+  testGetGeneric2();
+  testGetVoid();
+  testGetNativeFunction();
+  testGetNativeType();
+  testGetTypeMismatch();
+  testSetGeneric();
+  testSetGeneric2();
+  testSetVoid();
+  testSetNativeFunction();
+  testSetNativeType();
+  testSetTypeMismatch();
+  testAsFunctionGeneric();
+  testAsFunctionGeneric2();
+  testAsFunctionWrongNativeFunctionSignature();
+  testAsFunctionTypeMismatch();
+  testFromFunctionGeneric();
+  testFromFunctionGeneric2();
+  testFromFunctionWrongNativeFunctionSignature();
+  testFromFunctionTypeMismatch();
+  testFromFunctionClosure();
+  testFromFunctionTearOff();
+  testFromFunctionAbstract();
+  testLookupFunctionGeneric();
+  testLookupFunctionGeneric2();
+  testLookupFunctionWrongNativeFunctionSignature();
+  testLookupFunctionTypeMismatch();
+  testNativeFunctionSignatureInvalidReturn();
+  testNativeFunctionSignatureInvalidParam();
+  testNativeFunctionSignatureInvalidOptionalNamed();
+  testNativeFunctionSignatureInvalidOptionalPositional();
+}
+
+typedef Int8UnOp = Int8 Function(Int8);
+typedef IntUnOp = int Function(int);
+
+void testGetGeneric() {
+  int generic(Pointer p) {
+    int result;
+    result = p.value; //# 20: compile-time error
+    return result;
+  }
+
+  Pointer<Int8> p = allocate();
+  p.value = 123;
+  Pointer loseType = p;
+  generic(loseType);
+  free(p);
+}
+
+void testGetGeneric2() {
+  T generic<T extends Object>() {
+    Pointer<Int8> p = allocate();
+    p.value = 123;
+    T result;
+    result = p.value; //# 21: compile-time error
+    free(p);
+    return result;
+  }
+
+  generic<int>();
+}
+
+void testGetVoid() {
+  Pointer<IntPtr> p1 = allocate();
+  Pointer<Void> p2 = p1.cast();
+
+  p2.value; //# 22: compile-time error
+
+  free(p1);
+}
+
+void testGetNativeFunction() {
+  Pointer<NativeFunction<Int8UnOp>> p = Pointer.fromAddress(1337);
+  IntUnOp f = p.value; //# 23: compile-time error
+}
+
+void testGetNativeType() {
+  // Is it possible to obtain a Pointer<NativeType> at all?
+}
+
+void testGetTypeMismatch() {
+  Pointer<Pointer<Int16>> p = allocate();
+  Pointer<Int16> typedNull = nullptr;
+  p.value = typedNull;
+
+  // this fails to compile due to type mismatch
+  Pointer<Int8> p2 = p.value; //# 25: compile-time error
+
+  free(p);
+}
+
+void testSetGeneric() {
+  void generic(Pointer p) {
+    p.value = 123; //# 26: compile-time error
+  }
+
+  Pointer<Int8> p = allocate();
+  p.value = 123;
+  Pointer loseType = p;
+  generic(loseType);
+  free(p);
+}
+
+void testSetGeneric2() {
+  void generic<T extends Object>(T arg) {
+    Pointer<Int8> p = allocate();
+    p.value = arg; //# 27: compile-time error
+    free(p);
+  }
+
+  generic<int>(123);
+}
+
+void testSetVoid() {
+  Pointer<IntPtr> p1 = allocate();
+  Pointer<Void> p2 = p1.cast();
+
+  p2.value = 1234; //# 28: compile-time error
+
+  free(p1);
+}
+
+void testSetNativeFunction() {
+  Pointer<NativeFunction<Int8UnOp>> p = Pointer.fromAddress(1337);
+  IntUnOp f = (a) => a + 1;
+  p.value = f; //# 29: compile-time error
+}
+
+void testSetNativeType() {
+  // Is it possible to obtain a Pointer<NativeType> at all?
+}
+
+void testSetTypeMismatch() {
+  // the pointer to pointer types must match up
+  Pointer<Int8> pHelper = allocate();
+  pHelper.value = 123;
+
+  Pointer<Pointer<Int16>> p = allocate();
+
+  // this fails to compile due to type mismatch
+  p.value = pHelper; //# 40: compile-time error
+
+  free(pHelper);
+  free(p);
+}
+
+void testAsFunctionGeneric() {
+  T generic<T extends Function>() {
+    Pointer<NativeFunction<Int8UnOp>> p = Pointer.fromAddress(1337);
+    Function f;
+    f = p.asFunction<T>(); //# 11: compile-time error
+    return f;
+  }
+
+  generic<IntUnOp>();
+}
+
+void testAsFunctionGeneric2() {
+  generic(Pointer<NativeFunction> p) {
+    Function f;
+    f = p.asFunction<IntUnOp>(); //# 12: compile-time error
+    return f;
+  }
+
+  Pointer<NativeFunction<Int8UnOp>> p = Pointer.fromAddress(1337);
+  generic(p);
+}
+
+void testAsFunctionWrongNativeFunctionSignature() {
+  Pointer<NativeFunction<IntUnOp>> p;
+  Function f = p.asFunction<IntUnOp>(); //# 13: compile-time error
+}
+
+typedef IntBinOp = int Function(int, int);
+
+void testAsFunctionTypeMismatch() {
+  Pointer<NativeFunction<Int8UnOp>> p = Pointer.fromAddress(1337);
+  IntBinOp f = p.asFunction(); //# 14: compile-time error
+}
+
+typedef NativeDoubleUnOp = Double Function(Double);
+typedef DoubleUnOp = double Function(double);
+
+double myTimesThree(double d) => d * 3;
+
+int myTimesFour(int i) => i * 4;
+
+void testFromFunctionGeneric() {
+  Pointer<NativeFunction> generic<T extends Function>(T f) {
+    Pointer<NativeFunction<NativeDoubleUnOp>> result;
+    result = Pointer.fromFunction(f); //# 70: compile-time error
+    return result;
+  }
+
+  generic(myTimesThree);
+}
+
+void testFromFunctionGeneric2() {
+  Pointer<NativeFunction<T>> generic<T extends Function>() {
+    Pointer<NativeFunction<T>> result;
+    result = Pointer.fromFunction(myTimesThree); //# 71: compile-time error
+    return result;
+  }
+
+  generic<NativeDoubleUnOp>();
+}
+
+void testFromFunctionWrongNativeFunctionSignature() {
+  Pointer.fromFunction<IntUnOp>(myTimesFour); //# 72: compile-time error
+}
+
+void testFromFunctionTypeMismatch() {
+  Pointer<NativeFunction<NativeDoubleUnOp>> p;
+  p = Pointer.fromFunction(myTimesFour); //# 73: compile-time error
+}
+
+void testFromFunctionClosure() {
+  DoubleUnOp someClosure = (double z) => z / 27.0;
+  Pointer<NativeFunction<NativeDoubleUnOp>> p;
+  p = Pointer.fromFunction(someClosure); //# 74: compile-time error
+}
+
+class X {
+  double tearoff(double d) => d / 27.0;
+}
+
+void testFromFunctionTearOff() {
+  DoubleUnOp fld = X().tearoff;
+  Pointer<NativeFunction<NativeDoubleUnOp>> p;
+  p = Pointer.fromFunction(fld); //# 75: compile-time error
+}
+
+void testFromFunctionAbstract() {
+  Pointer.fromFunction<Function>(//# 76: compile-time error
+      testFromFunctionAbstract); //# 76: compile-time error
+}
+
+void testLookupFunctionGeneric() {
+  Function generic<T extends Function>() {
+    DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
+    Function result;
+    result = l.lookupFunction<T, DoubleUnOp>("cos"); //# 15: compile-time error
+    return result;
+  }
+
+  generic<NativeDoubleUnOp>();
+}
+
+void testLookupFunctionGeneric2() {
+  Function generic<T extends Function>() {
+    DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
+    Function result;
+    result = //# 16: compile-time error
+        l.lookupFunction<NativeDoubleUnOp, T>("cos"); //# 16: compile-time error
+    return result;
+  }
+
+  generic<DoubleUnOp>();
+}
+
+void testLookupFunctionWrongNativeFunctionSignature() {
+  DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
+  l.lookupFunction<IntUnOp, IntUnOp>("cos"); //# 17: compile-time error
+}
+
+void testLookupFunctionTypeMismatch() {
+  DynamicLibrary l = dlopenPlatformSpecific("ffi_test_dynamic_library");
+  l.lookupFunction<NativeDoubleUnOp, IntUnOp>("cos"); //# 18: compile-time error
+}
+
+// TODO(dacoharkes): make the next 4 test compile errors
+typedef Invalid1 = int Function(Int8);
+typedef Invalid2 = Int8 Function(int);
+typedef Invalid3 = Int8 Function({Int8 named});
+typedef Invalid4 = Int8 Function([Int8 positional]);
+
+void testNativeFunctionSignatureInvalidReturn() {
+  // Pointer<NativeFunction<Invalid1>> p = fromAddress(999);
+}
+
+void testNativeFunctionSignatureInvalidParam() {
+  // Pointer<NativeFunction<Invalid2>> p = fromAddress(999);
+}
+
+void testNativeFunctionSignatureInvalidOptionalNamed() {
+  // Pointer<NativeFunction<Invalid3>> p = fromAddress(999);
+}
+
+void testNativeFunctionSignatureInvalidOptionalPositional() {
+  // Pointer<NativeFunction<Invalid4>> p = fromAddress(999);
+}
+
+// error on missing field annotation
+class TestStruct extends Struct {
+  @Double()
+  double x;
+
+  double y; //# 50: compile-time error
+}
+
+// Cannot extend structs.
+class TestStruct3 extends TestStruct {} //# 52: compile-time error
+
+// error on double annotation
+class TestStruct4 extends Struct {
+  @Double()
+  @Double() //# 53: compile-time error
+  double z;
+}
+
+// error on annotation not matching up
+class TestStruct5 extends Struct {
+  @Int64() //# 54: compile-time error
+  double z; //# 54: compile-time error
+}
+
+// error on annotation not matching up
+class TestStruct6 extends Struct {
+  @Void() //# 55: compile-time error
+  double z; //# 55: compile-time error
+}
+
+// error on annotation not matching up
+class TestStruct7 extends Struct {
+  @NativeType() //# 56: compile-time error
+  double z; //# 56: compile-time error
+}
+
+// error on field initializer on field
+class TestStruct8 extends Struct {
+  @Double() //# 57: compile-time error
+  double z = 10.0; //# 57: compile-time error
+}
+
+// error on field initializer in constructor
+class TestStruct9 extends Struct {
+  @Double()
+  double z;
+
+  TestStruct9() : z = 0.0 {} //# 58: compile-time error
+}
+
+// Struct classes may not be generic.
+class TestStruct11<T> extends //# 60: compile-time error
+    Struct<TestStruct11<dynamic>> {} //# 60: compile-time error
+
+// Structs may not appear inside structs (currently, there is no suitable
+// annotation).
+class TestStruct12 extends Struct {
+  @Pointer //# 61: compile-time error
+  TestStruct9 struct; //# 61: compile-time error
+}
+
+class DummyAnnotation {
+  const DummyAnnotation();
+}
+
+// Structs fields may have other annotations.
+class TestStruct13 extends Struct {
+  @DummyAnnotation()
+  @Double()
+  double z;
+}
+
+// Cannot extend native types.
+
+class ENativeType extends NativeType {} //# 90: compile-time error
+
+class EInt8 extends Int8 {} //# 91: compile-time error
+
+class EInt16 extends Int16 {} //# 92: compile-time error
+
+class EInt32 extends Int32 {} //# 93: compile-time error
+
+class EInt64 extends Int64 {} //# 94: compile-time error
+
+class EUint8 extends Uint8 {} //# 95: compile-time error
+
+class EUint16 extends Uint16 {} //# 96: compile-time error
+
+class EUint32 extends Uint32 {} //# 97: compile-time error
+
+class EUint64 extends Uint64 {} //# 98: compile-time error
+
+class EIntPtr extends IntPtr {} //# 99: compile-time error
+
+class EFloat extends Float {} //# 910: compile-time error
+
+class EDouble extends Double {} //# 911: compile-time error
+
+class EVoid extends Void {} //# 912: compile-time error
+
+class ENativeFunction extends NativeFunction {} //# 913: compile-time error
+
+class EPointer extends Pointer {} //# 914: compile-time error
+
+// Cannot implement native natives or Struct.
+
+// Cannot extend native types.
+
+class INativeType implements NativeType {} //# 80: compile-time error
+
+class IInt8 implements Int8 {} //# 81: compile-time error
+
+class IInt16 implements Int16 {} //# 82: compile-time error
+
+class IInt32 implements Int32 {} //# 83: compile-time error
+
+class IInt64 implements Int64 {} //# 84: compile-time error
+
+class IUint8 implements Uint8 {} //# 85: compile-time error
+
+class IUint16 implements Uint16 {} //# 86: compile-time error
+
+class IUint32 implements Uint32 {} //# 87: compile-time error
+
+class IUint64 implements Uint64 {} //# 88: compile-time error
+
+class IIntPtr implements IntPtr {} //# 88: compile-time error
+
+class IFloat implements Float {} //# 810: compile-time error
+
+class IDouble implements Double {} //# 811: compile-time error
+
+class IVoid implements Void {} //# 812: compile-time error
+
+class INativeFunction //# 813: compile-time error
+    implements //# 813: compile-time error
+        NativeFunction {} //# 813: compile-time error
+
+class IPointer implements Pointer {} //# 814: compile-time error
+
+class IStruct implements Struct {} //# 815: compile-time error
diff --git a/tests/ffi_2/vmspecific_variance_function_checks_test.dart b/tests/ffi_2/vmspecific_variance_function_checks_test.dart
new file mode 100644
index 0000000..c17488c
--- /dev/null
+++ b/tests/ffi_2/vmspecific_variance_function_checks_test.dart
@@ -0,0 +1,67 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'dylib_utils.dart';
+
+// ============================================
+// Tests checks on Dart to native (asFunction).
+// ============================================
+
+typedef Int64PointerParamOpDart = void Function(Pointer<Int64>);
+typedef Int64PointerParamOp = Void Function(Pointer<Int64>);
+typedef Int64PointerReturnOp = Pointer<Int64> Function();
+typedef NaTyPointerReturnOp = Pointer<NativeType> Function();
+
+final paramOpName = "NativeTypePointerParam";
+final returnOpName = "NativeTypePointerReturn";
+
+final DynamicLibrary ffiTestFunctions =
+    dlopenPlatformSpecific("ffi_test_functions");
+
+final p1 =
+    ffiTestFunctions.lookup<NativeFunction<Int64PointerParamOp>>(paramOpName);
+final nonInvariantBinding1 = //# 1:  compile-time error
+    p1.asFunction<NaTyPointerParamOpDart>(); //# 1:  continued
+
+final p2 =
+    ffiTestFunctions.lookup<NativeFunction<NaTyPointerReturnOp>>(returnOpName);
+final nonInvariantBinding2 = //# 2:  compile-time error
+    p2.asFunction<Int64PointerReturnOp>(); //# 2:  continued
+
+final p3 = Pointer<
+    NativeFunction<
+        Pointer<NativeFunction<Pointer<NativeType> Function()>>
+            Function()>>.fromAddress(0x1234);
+final f3 = p3 //# 10:  compile-time error
+    .asFunction< //# 10:  continued
+        Pointer< //# 10:  continued
+                NativeFunction< //# 10:  continued
+                    Pointer<Int8> Function()>> //# 10:  continued
+            Function()>(); //# 10:  continued
+
+// ===========================================================
+// Test check on callbacks from native to Dart (fromFunction).
+// ===========================================================
+
+void naTyPointerParamOp(Pointer<NativeType> p) {
+  final Pointer<Int8> asInt8 = p.cast();
+  asInt8.value = 42;
+}
+
+Pointer<Int64> int64PointerReturnOp() {
+  return Pointer.fromAddress(0x13370000);
+}
+
+final implictDowncast1 = //# 3:  compile-time error
+    Pointer.fromFunction<Int64PointerParamOp>(//# 3:  continued
+        naTyPointerParamOp); //# 3:  continued
+final implictDowncast2 = //# 4:  compile-time error
+    Pointer.fromFunction<NaTyPointerReturnOp>(//# 4:  continued
+        int64PointerReturnOp); //# 4:  continued
+
+void main() {}
diff --git a/tests/language/await_type_error_test.dart b/tests/language/await_type_error_test.dart
new file mode 100644
index 0000000..b838fcc
--- /dev/null
+++ b/tests/language/await_type_error_test.dart
@@ -0,0 +1,54 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:async";
+import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
+
+main() async {
+  int i = 1;
+  Future<int> fi = Future<int>.value(i);
+  Future<Future<int>> ffi = Future<Future<int>>.value(fi);
+  Future<Future<Future<int>>> fffi = Future<Future<Future<int>>>.value(ffi);
+
+  String v1 = await i;
+  //                ^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  String v2 = await fi;
+  //                ^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  int v3 = await ffi;
+  //             ^^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  Future<int> v4 = await fffi;
+  //                     ^^^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  Future<int> v5 = await i;
+  //                     ^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  Future<int> v6 = await fi;
+  //                     ^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  Future<FutureOr<int>> v7 = await fi;
+  //                               ^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  Future<Future<int>> v8 = await ffi;
+  //                             ^^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+}
diff --git a/tests/language/await_type_test.dart b/tests/language/await_type_test.dart
new file mode 100644
index 0000000..dd3a765
--- /dev/null
+++ b/tests/language/await_type_test.dart
@@ -0,0 +1,87 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:async";
+import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
+
+void main() async {
+  asyncStart();
+
+  var fi = Future<int>.value(1);
+  var ffi = Future<Future<int>>.value(fi);
+
+  // Sanity check.
+  Expect.equals(type<int>(), typeOf(1));
+
+  {
+    int v = 1; //                          // Variable with type T.
+    var f = await v; //                    // Variable with type FLATTEN(T).
+    Expect.equals(type<int>(), typeOf(f)); // Dynamic check of static type of f.
+    int s = f; //                          // Static check upper bound of f.
+    f = 1; //                              // Static check lower bound of f.
+    s.toString(); //                       // Avoid "unused variable" warning.
+  }
+
+  {
+    Future<int> v = fi;
+    var f = await v;
+    Expect.equals(type<int>(), typeOf(f));
+    int s = f;
+    f = 1;
+    s.toString();
+  }
+
+  {
+    Future<Future<int>> v = ffi;
+    var f = await v;
+    Expect.equals(type<Future<int>>(), typeOf(f));
+    Future<int> s = f;
+    f = fi;
+    s.toString();
+  }
+
+  {
+    FutureOr<int> v = 1;
+    var f = await v;
+    Expect.equals(type<int>(), typeOf(f));
+    int s = f;
+    f = 1;
+    s.toString();
+  }
+
+  {
+    FutureOr<Future<int>> v = fi;
+    var f = await v;
+    Expect.equals(type<Future<int>>(), typeOf(f));
+    Future<int> s = f;
+    f = fi;
+    s.toString();
+  }
+
+  {
+    Future<FutureOr<int>> v = fi;
+    var f = await v;
+    Expect.equals(type<FutureOr<int>>(), typeOf(f));
+    FutureOr<int> s = f;
+    f = 1;
+    f = fi;
+    s.toString();
+  }
+
+  {
+    FutureOr<FutureOr<int>> v = 1;
+    var f = await v;
+    Expect.equals(type<FutureOr<int>>(), typeOf(f));
+    FutureOr<int> s = f;
+    f = 1;
+    f = fi;
+    s.toString();
+  }
+
+  asyncEnd();
+}
+
+Type type<T>() => T;
+Type typeOf<T>(T of) => T;
diff --git a/tests/language/language.status b/tests/language/language.status
index 7944430..266988d 100644
--- a/tests/language/language.status
+++ b/tests/language/language.status
@@ -19,7 +19,7 @@
 void/*: Skip # https://github.com/dart-lang/sdk/issues/34015
 
 [ $mode == debug ]
-class/large_class_declaration_test: Slow
+class/large_class_declaration_test: Slow, Pass
 
 [ $mode == product ]
 assert/assert_test: SkipByDesign # Requires checked mode.
@@ -43,4 +43,4 @@
 
 [ $hot_reload || $hot_reload_rollback ]
 regress/regress22780_test/01: Crash # Issue 29094
-vm/optimized_stacktrace_test: Slow
+vm/optimized_stacktrace_test: Slow, Pass
diff --git a/tests/language/language_analyzer.status b/tests/language/language_analyzer.status
index 23eabf4..90a98d3 100644
--- a/tests/language/language_analyzer.status
+++ b/tests/language/language_analyzer.status
@@ -5,7 +5,7 @@
 # Sections in this file should contain "$compiler == dart2analyzer".
 
 [ $compiler == dart2analyzer ]
-class/large_class_declaration_test: Slow
+class/large_class_declaration_test: Slow, Pass
 vm/debug_break_enabled_vm_test: Skip
 vm/debug_break_vm_test/*: Skip
 vm/regress_27201_test: SkipByDesign # Loads bad library, so will always crash.
diff --git a/tests/language/language_dart2js.status b/tests/language/language_dart2js.status
index 5bdb444..e0b4991 100644
--- a/tests/language/language_dart2js.status
+++ b/tests/language/language_dart2js.status
@@ -15,7 +15,7 @@
 control_flow_collections/for_non_bool_condition_test: Crash # Issue 36442
 
 [ $compiler == dart2js && $runtime == chromeOnAndroid ]
-override_field_test/02: Slow # TODO(kasperl): Please triage.
+override_field_test/02: Slow, Pass # TODO(kasperl): Please triage.
 
 [ $compiler == dart2js && $runtime == d8 ]
 import/conditional_string_test: SkipByDesign # No XHR in d8
diff --git a/tests/language/language_dartdevc.status b/tests/language/language_dartdevc.status
index f94dbaa..d92526e 100644
--- a/tests/language/language_dartdevc.status
+++ b/tests/language/language_dartdevc.status
@@ -4,7 +4,7 @@
 
 # Sections in this file should contain "$compiler == dartdevc" or dartdevk.
 [ $compiler == dartdevc ]
-class/large_class_declaration_test: Slow
+class/large_class_declaration_test: Slow, Pass
 const/double_in_int_op_test/dd6: Skip # Triple shift
 const/double_in_int_op_test/di6: Skip # Triple shift
 const/double_in_int_op_test/id6: Skip # Triple shift
diff --git a/tests/language/language_kernel.status b/tests/language/language_kernel.status
index a627eb8..8ca708b 100644
--- a/tests/language/language_kernel.status
+++ b/tests/language/language_kernel.status
@@ -237,7 +237,7 @@
 unsorted/inference_enum_list_test: Skip # Issue 35885
 
 [ $compiler == dartkp && $mode == debug && $runtime == dart_precompiled ]
-vm/precompiled_static_initializer_test: Slow
+vm/precompiled_static_initializer_test: Slow, Pass
 
 # ==== dartkp + dart_precompiled status lines ====
 [ $compiler == dartkp && $runtime == dart_precompiled ]
@@ -293,7 +293,7 @@
 assert/initializer_const_error2_test/cc11: Crash
 
 [ $compiler == dartkp && $system == windows ]
-unsorted/disassemble_test: Slow
+unsorted/disassemble_test: Slow, Pass
 
 [ $mode == debug && $runtime == vm && ($compiler == app_jitk || $compiler == dartk || $compiler == dartkb) ]
 optimize/deopt_inlined_function_lazy_test: Skip
@@ -324,7 +324,7 @@
 web_int_literals_test/*: SkipByDesign # Test applies only to JavaScript targets
 
 [ $hot_reload_rollback && ($compiler == dartk || $compiler == dartkb) ]
-symbol/conflict_test: Slow
+symbol/conflict_test: Slow, Pass
 
 [ ($compiler == dartk || $compiler == dartkb) && ($hot_reload || $hot_reload_rollback) ]
 async_star/async_star2_test/01: Skip # Timeout
diff --git a/tests/language/operator/invalid_operators_test.dart b/tests/language/operator/invalid_operators_test.dart
new file mode 100644
index 0000000..d0ec7e4
--- /dev/null
+++ b/tests/language/operator/invalid_operators_test.dart
@@ -0,0 +1,667 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class Operators1 {
+  operator ==() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.INVALID_OVERRIDE
+  // [cfe] Operator '==' should have exactly one parameter.
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  operator <() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<' should have exactly one parameter.
+  operator >() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>' should have exactly one parameter.
+  operator <=() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<=' should have exactly one parameter.
+  operator >=() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>=' should have exactly one parameter.
+  operator +() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '+' should have exactly one parameter.
+  operator /() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '/' should have exactly one parameter.
+  operator ~/() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~/' should have exactly one parameter.
+  operator *() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '*' should have exactly one parameter.
+  operator %() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '%' should have exactly one parameter.
+  operator |() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '|' should have exactly one parameter.
+  operator ^() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '^' should have exactly one parameter.
+  operator &() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '&' should have exactly one parameter.
+  operator <<() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<<' should have exactly one parameter.
+  operator >>() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>>' should have exactly one parameter.
+  operator []=(a, b, c) => true;
+  //       ^^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]=' should have exactly two parameters.
+  operator []() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]' should have exactly one parameter.
+  operator ~(a) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+}
+
+class Operators2 {
+  operator ==(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.INVALID_OVERRIDE
+  // [cfe] Operator '==' should have exactly one parameter.
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  operator <(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<' should have exactly one parameter.
+  operator >(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>' should have exactly one parameter.
+  operator <=(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<=' should have exactly one parameter.
+  operator >=(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>=' should have exactly one parameter.
+  operator -(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR_MINUS
+  // [cfe] Operator '-' should have zero or one parameter.
+  operator +(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '+' should have exactly one parameter.
+  operator /(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '/' should have exactly one parameter.
+  operator ~/(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~/' should have exactly one parameter.
+  operator *(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '*' should have exactly one parameter.
+  operator %(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '%' should have exactly one parameter.
+  operator |(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '|' should have exactly one parameter.
+  operator ^(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '^' should have exactly one parameter.
+  operator &(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '&' should have exactly one parameter.
+  operator <<(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<<' should have exactly one parameter.
+  operator >>(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>>' should have exactly one parameter.
+  operator []=(a, b, c) => true;
+  //       ^^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]=' should have exactly two parameters.
+  operator [](a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]' should have exactly one parameter.
+  operator ~(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+}
+
+class Operators3 {
+  operator ==([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <=([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >=([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator -([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator +([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator /([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ~/([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator *([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator %([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator |([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ^([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator &([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <<([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >>([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator []=([a, b]) => true;
+  //            ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  //               ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator []([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ~([a]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+}
+
+class Operators4 {
+  operator ==({a}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.INVALID_OVERRIDE
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <=({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >=({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator -({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator +({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator /({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ~/({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator *({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator %({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator |({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ^({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator &({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <<({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >>({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator []=({a, b}) => true;
+  //            ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  //               ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator []({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ~({a}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+}
+
+class Operators5 {
+  operator ==(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '==' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <=(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<=' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >=(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>=' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator -(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR_MINUS
+  // [cfe] Operator '-' should have zero or one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator +(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '+' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator /(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '/' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ~/(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~/' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator *(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '*' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator %(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '%' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator |(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '|' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ^(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '^' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator &(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '&' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <<(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<<' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >>(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>>' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator []=(a, b, [c]) => true;
+  //       ^^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]=' should have exactly two parameters.
+  //                  ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator [](a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ~(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+}
+
+class Operators6 {
+  operator ==(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '==' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <=(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<=' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >=(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>=' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator -(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR_MINUS
+  // [cfe] Operator '-' should have zero or one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator +(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '+' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator /(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '/' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ~/(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~/' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator *(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '*' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator %(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '%' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator |(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '|' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ^(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '^' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator &(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '&' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <<(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<<' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >>(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>>' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator []=(a, b, {c}) => true;
+  //       ^^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]=' should have exactly two parameters.
+  //                  ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator [](a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ~(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+}
+
+class Operators7 {
+  operator ==<T>(a) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.INVALID_OVERRIDE
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator ><T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator <=<T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator >=<T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator -<T>() => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator -<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator +<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator /<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator ~/<T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator *<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator %<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator |<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator ^<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator &<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator <<<T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator >><T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator []=<T>(a, b) => true;
+  //          ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //           ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator []<T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator ~<T, S>() => true;
+  //        ^^^^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+}
+
+main() {}
diff --git a/tests/language_2/await_type_error_test.dart b/tests/language_2/await_type_error_test.dart
new file mode 100644
index 0000000..b838fcc
--- /dev/null
+++ b/tests/language_2/await_type_error_test.dart
@@ -0,0 +1,54 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:async";
+import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
+
+main() async {
+  int i = 1;
+  Future<int> fi = Future<int>.value(i);
+  Future<Future<int>> ffi = Future<Future<int>>.value(fi);
+  Future<Future<Future<int>>> fffi = Future<Future<Future<int>>>.value(ffi);
+
+  String v1 = await i;
+  //                ^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  String v2 = await fi;
+  //                ^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  int v3 = await ffi;
+  //             ^^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  Future<int> v4 = await fffi;
+  //                     ^^^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  Future<int> v5 = await i;
+  //                     ^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  Future<int> v6 = await fi;
+  //                     ^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  Future<FutureOr<int>> v7 = await fi;
+  //                               ^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  Future<Future<int>> v8 = await ffi;
+  //                             ^^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+}
diff --git a/tests/language_2/await_type_test.dart b/tests/language_2/await_type_test.dart
new file mode 100644
index 0000000..349beac
--- /dev/null
+++ b/tests/language_2/await_type_test.dart
@@ -0,0 +1,83 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:async";
+import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
+
+void main() async {
+  asyncStart();
+
+  // Sanity check.
+  Expect.equals(type<int>(), type(1));
+
+  {
+    int v = null; //                     // Variable with type T.
+    var f = await v; //                  // Variable with type FLATTEN(T).
+    Expect.equals(type<int>(), type(f)); // Dynamic check of static type of f.
+    int s = f; //                        // Static check upper bound of f.
+    f = 1; //                            // Static check lower bound of f.
+    s.toString(); //                     // Avoid "unused variable" warning.
+  }
+
+  {
+    Future<int> v = null;
+    var f = await v;
+    Expect.equals(type<int>(), type(f));
+    int s = f;
+    f = 1;
+    s.toString();
+  }
+
+  {
+    Future<Future<int>> v = null;
+    var f = await v;
+    Expect.equals(type<Future<int>>(), type(f));
+    Future<int> s = f;
+    f = Future<int>.value(1);
+    s.toString();
+  }
+
+  {
+    FutureOr<int> v = null;
+    var f = await v;
+    Expect.equals(type<int>(), type(f));
+    int s = f;
+    f = 1;
+    s.toString();
+  }
+
+  {
+    FutureOr<Future<int>> v = null;
+    var f = await v;
+    Expect.equals(type<Future<int>>(), type(f));
+    Future<int> s = f;
+    f = Future<int>.value(1);
+    s.toString();
+  }
+
+  {
+    Future<FutureOr<int>> v = null;
+    var f = await v;
+    Expect.equals(type<FutureOr<int>>(), type(f));
+    FutureOr<int> s = f;
+    f = 1;
+    f = Future<int>.value(1);
+    s.toString();
+  }
+
+  {
+    FutureOr<FutureOr<int>> v = null;
+    var f = await v;
+    Expect.equals(type<FutureOr<int>>(), type(f));
+    FutureOr<int> s = f;
+    f = 1;
+    f = Future<int>.value(1);
+    s.toString();
+  }
+
+  asyncEnd();
+}
+
+Type type<T>([T of]) => T;
diff --git a/tests/language_2/enum/private_test.dart b/tests/language_2/enum/private_test.dart
index cf2376d..bd99d84 100644
--- a/tests/language_2/enum/private_test.dart
+++ b/tests/language_2/enum/private_test.dart
@@ -20,6 +20,6 @@
   Expect.equals('Enum2._A,Enum2._B', Enum2.values.join(','));
   Expect.throwsNoSuchMethodError(() => Enum2._A);
   //                                         ^^
-  // [analyzer] STATIC_TYPE_WARNING.UNDEFINED_GETTER
+  // [analyzer] STATIC_TYPE_WARNING.UNDEFINED_ENUM_CONSTANT
   // [cfe] Getter not found: '_A'.
 }
diff --git a/tests/language_2/extension_methods/static_extension_setter_getter_assignability_error_test.dart b/tests/language_2/extension_methods/static_extension_setter_getter_assignability_error_test.dart
index 1cff35a..1b0a81b 100644
--- a/tests/language_2/extension_methods/static_extension_setter_getter_assignability_error_test.dart
+++ b/tests/language_2/extension_methods/static_extension_setter_getter_assignability_error_test.dart
@@ -12,7 +12,7 @@
   //     ^^
   // [cfe] unspecified
   //             ^^^^^^^^
-  // [analyzer] STATIC_WARNING.MISMATCHED_GETTER_AND_SETTER_TYPES
+  // [analyzer] STATIC_WARNING.GETTER_NOT_ASSIGNABLE_SETTER_TYPES
   static void set property(String value) {}
   //                       ^^
   // [cfe] unspecified
@@ -20,7 +20,7 @@
   //  ^^
   // [cfe] unspecified
   //      ^^^^^^^^^
-  // [analyzer] STATIC_WARNING.MISMATCHED_GETTER_AND_SETTER_TYPES
+  // [analyzer] STATIC_WARNING.GETTER_NOT_ASSIGNABLE_SETTER_TYPES
   void set property2(String x) {}
   //                 ^^
   // [cfe] unspecified
diff --git a/tests/language_2/getter/setter2_test.dart b/tests/language_2/getter/setter2_test.dart
index cdc268b..de9bc28 100644
--- a/tests/language_2/getter/setter2_test.dart
+++ b/tests/language_2/getter/setter2_test.dart
@@ -37,7 +37,7 @@
   C setterField;
   A get field {
   //    ^^^^^
-  // [analyzer] STATIC_WARNING.MISMATCHED_GETTER_AND_SETTER_TYPES
+  // [analyzer] STATIC_WARNING.GETTER_NOT_ASSIGNABLE_SETTER_TYPES
     return getterField;
   }
 
diff --git a/tests/language_2/getter/setter_type_test.dart b/tests/language_2/getter/setter_type_test.dart
index 63db11a..e108848 100644
--- a/tests/language_2/getter/setter_type_test.dart
+++ b/tests/language_2/getter/setter_type_test.dart
@@ -9,8 +9,8 @@
 int bar = 499;
 
 int get foo => bar;
-// [error line 11, column 1, length 19]
-// [analyzer] STATIC_WARNING.MISMATCHED_GETTER_AND_SETTER_TYPES
+//      ^^^
+// [analyzer] STATIC_WARNING.GETTER_NOT_ASSIGNABLE_SETTER_TYPES
 
 void set foo(String str) {
   bar = str.length;
diff --git a/tests/language_2/language_2.status b/tests/language_2/language_2.status
index a13e7f6..72e60ac 100644
--- a/tests/language_2/language_2.status
+++ b/tests/language_2/language_2.status
@@ -19,7 +19,7 @@
 void/*: Skip # https://github.com/dart-lang/sdk/issues/34015
 
 [ $mode == debug ]
-class/large_class_declaration_test: Slow
+class/large_class_declaration_test: Slow, Pass
 
 [ $mode == product ]
 assert/assert_test: SkipByDesign # Requires checked mode.
@@ -45,4 +45,4 @@
 regress/regress22780_test/01: Crash # Issue 29094
 regress/regress23244_test: Skip # https://dartbug.com/36097: Ongoing concurrency work.
 vm/optimized_guarded_field_isolates_test: Skip # https://dartbug.com/36097: Ongoing concurrency work.
-vm/optimized_stacktrace_test: Slow
+vm/optimized_stacktrace_test: Slow, Pass
diff --git a/tests/language_2/language_2_analyzer.status b/tests/language_2/language_2_analyzer.status
index 23eabf4..90a98d3 100644
--- a/tests/language_2/language_2_analyzer.status
+++ b/tests/language_2/language_2_analyzer.status
@@ -5,7 +5,7 @@
 # Sections in this file should contain "$compiler == dart2analyzer".
 
 [ $compiler == dart2analyzer ]
-class/large_class_declaration_test: Slow
+class/large_class_declaration_test: Slow, Pass
 vm/debug_break_enabled_vm_test: Skip
 vm/debug_break_vm_test/*: Skip
 vm/regress_27201_test: SkipByDesign # Loads bad library, so will always crash.
diff --git a/tests/language_2/language_2_dart2js.status b/tests/language_2/language_2_dart2js.status
index 5bdb444..e0b4991 100644
--- a/tests/language_2/language_2_dart2js.status
+++ b/tests/language_2/language_2_dart2js.status
@@ -15,7 +15,7 @@
 control_flow_collections/for_non_bool_condition_test: Crash # Issue 36442
 
 [ $compiler == dart2js && $runtime == chromeOnAndroid ]
-override_field_test/02: Slow # TODO(kasperl): Please triage.
+override_field_test/02: Slow, Pass # TODO(kasperl): Please triage.
 
 [ $compiler == dart2js && $runtime == d8 ]
 import/conditional_string_test: SkipByDesign # No XHR in d8
diff --git a/tests/language_2/language_2_dartdevc.status b/tests/language_2/language_2_dartdevc.status
index f94dbaa..d92526e 100644
--- a/tests/language_2/language_2_dartdevc.status
+++ b/tests/language_2/language_2_dartdevc.status
@@ -4,7 +4,7 @@
 
 # Sections in this file should contain "$compiler == dartdevc" or dartdevk.
 [ $compiler == dartdevc ]
-class/large_class_declaration_test: Slow
+class/large_class_declaration_test: Slow, Pass
 const/double_in_int_op_test/dd6: Skip # Triple shift
 const/double_in_int_op_test/di6: Skip # Triple shift
 const/double_in_int_op_test/id6: Skip # Triple shift
diff --git a/tests/language_2/language_2_kernel.status b/tests/language_2/language_2_kernel.status
index dce25e7..1d10def 100644
--- a/tests/language_2/language_2_kernel.status
+++ b/tests/language_2/language_2_kernel.status
@@ -52,7 +52,7 @@
 unsorted/inference_enum_list_test: Skip # Issue 35885
 
 [ $compiler == dartkp && $mode == debug && $runtime == dart_precompiled ]
-vm/precompiled_static_initializer_test: Slow
+vm/precompiled_static_initializer_test: Slow, Pass
 
 # ==== dartkp + dart_precompiled status lines ====
 [ $compiler == dartkp && $runtime == dart_precompiled ]
@@ -108,7 +108,7 @@
 assert/initializer_const_error2_test/cc11: Crash
 
 [ $compiler == dartkp && $system == windows ]
-unsorted/disassemble_test: Slow
+unsorted/disassemble_test: Slow, Pass
 
 [ $mode == debug && $runtime == vm && ($compiler == app_jitk || $compiler == dartk || $compiler == dartkb) ]
 optimize/deopt_inlined_function_lazy_test: Skip
@@ -135,7 +135,7 @@
 web_int_literals_test/*: SkipByDesign # Test applies only to JavaScript targets
 
 [ $hot_reload_rollback && ($compiler == dartk || $compiler == dartkb) ]
-symbol/conflict_test: Slow
+symbol/conflict_test: Slow, Pass
 
 [ ($compiler == dartk || $compiler == dartkb) && ($hot_reload || $hot_reload_rollback) ]
 type_constants_test/none: Skip # Deferred libraries and hot reload.
diff --git a/tests/language_2/operator/invalid_operators_test.dart b/tests/language_2/operator/invalid_operators_test.dart
new file mode 100644
index 0000000..d0ec7e4
--- /dev/null
+++ b/tests/language_2/operator/invalid_operators_test.dart
@@ -0,0 +1,667 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class Operators1 {
+  operator ==() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.INVALID_OVERRIDE
+  // [cfe] Operator '==' should have exactly one parameter.
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  operator <() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<' should have exactly one parameter.
+  operator >() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>' should have exactly one parameter.
+  operator <=() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<=' should have exactly one parameter.
+  operator >=() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>=' should have exactly one parameter.
+  operator +() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '+' should have exactly one parameter.
+  operator /() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '/' should have exactly one parameter.
+  operator ~/() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~/' should have exactly one parameter.
+  operator *() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '*' should have exactly one parameter.
+  operator %() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '%' should have exactly one parameter.
+  operator |() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '|' should have exactly one parameter.
+  operator ^() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '^' should have exactly one parameter.
+  operator &() => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '&' should have exactly one parameter.
+  operator <<() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<<' should have exactly one parameter.
+  operator >>() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>>' should have exactly one parameter.
+  operator []=(a, b, c) => true;
+  //       ^^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]=' should have exactly two parameters.
+  operator []() => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]' should have exactly one parameter.
+  operator ~(a) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+}
+
+class Operators2 {
+  operator ==(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.INVALID_OVERRIDE
+  // [cfe] Operator '==' should have exactly one parameter.
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  operator <(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<' should have exactly one parameter.
+  operator >(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>' should have exactly one parameter.
+  operator <=(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<=' should have exactly one parameter.
+  operator >=(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>=' should have exactly one parameter.
+  operator -(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR_MINUS
+  // [cfe] Operator '-' should have zero or one parameter.
+  operator +(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '+' should have exactly one parameter.
+  operator /(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '/' should have exactly one parameter.
+  operator ~/(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~/' should have exactly one parameter.
+  operator *(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '*' should have exactly one parameter.
+  operator %(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '%' should have exactly one parameter.
+  operator |(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '|' should have exactly one parameter.
+  operator ^(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '^' should have exactly one parameter.
+  operator &(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '&' should have exactly one parameter.
+  operator <<(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<<' should have exactly one parameter.
+  operator >>(a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>>' should have exactly one parameter.
+  operator []=(a, b, c) => true;
+  //       ^^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]=' should have exactly two parameters.
+  operator [](a, b) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]' should have exactly one parameter.
+  operator ~(a, b) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+}
+
+class Operators3 {
+  operator ==([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <=([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >=([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator -([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator +([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator /([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ~/([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator *([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator %([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator |([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ^([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator &([a]) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <<([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >>([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator []=([a, b]) => true;
+  //            ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  //               ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator []([a]) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ~([a]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+}
+
+class Operators4 {
+  operator ==({a}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.INVALID_OVERRIDE
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <=({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >=({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator -({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator +({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator /({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ~/({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator *({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator %({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator |({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ^({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator &({a}) => true;
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator <<({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator >>({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator []=({a, b}) => true;
+  //            ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  //               ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator []({a}) => true;
+  //           ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  // [cfe] An operator can't have optional parameters.
+  operator ~({a}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+  //          ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+}
+
+class Operators5 {
+  operator ==(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '==' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <=(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<=' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >=(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>=' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator -(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR_MINUS
+  // [cfe] Operator '-' should have zero or one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator +(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '+' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator /(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '/' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ~/(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~/' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator *(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '*' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator %(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '%' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator |(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '|' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ^(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '^' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator &(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '&' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <<(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<<' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >>(a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>>' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator []=(a, b, [c]) => true;
+  //       ^^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]=' should have exactly two parameters.
+  //                  ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator [](a, [b]) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ~(a, [b]) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+}
+
+class Operators6 {
+  operator ==(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '==' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <=(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<=' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >=(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>=' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator -(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR_MINUS
+  // [cfe] Operator '-' should have zero or one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator +(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '+' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator /(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '/' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ~/(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~/' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator *(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '*' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator %(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '%' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator |(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '|' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ^(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '^' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator &(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '&' should have exactly one parameter.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator <<(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '<<' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator >>(a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '>>' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator []=(a, b, {c}) => true;
+  //       ^^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]=' should have exactly two parameters.
+  //                  ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator [](a, {b}) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '[]' should have exactly one parameter.
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+  operator ~(a, {b}) => true;
+  //       ^
+  // [analyzer] COMPILE_TIME_ERROR.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR
+  // [cfe] Operator '~' shouldn't have any parameters.
+  //             ^
+  // [analyzer] COMPILE_TIME_ERROR.OPTIONAL_PARAMETER_IN_OPERATOR
+}
+
+class Operators7 {
+  operator ==<T>(a) => true;
+  //       ^^
+  // [analyzer] COMPILE_TIME_ERROR.INVALID_OVERRIDE
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator ><T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator <=<T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator >=<T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator -<T>() => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator -<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator +<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator /<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator ~/<T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator *<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator %<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator |<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator ^<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator &<T>(a) => true;
+  //        ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator <<<T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator >><T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator []=<T>(a, b) => true;
+  //          ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //           ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator []<T>(a) => true;
+  //         ^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //          ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+  operator ~<T, S>() => true;
+  //        ^^^^^^
+  // [analyzer] SYNTACTIC_ERROR.TYPE_PARAMETERS_ON_OPERATOR
+  //         ^
+  // [cfe] Types parameters aren't allowed when defining an operator.
+}
+
+main() {}
diff --git a/tests/language_2/vm/causal_async_exception_stack_test.dart b/tests/language_2/vm/causal_async_exception_stack_test.dart
index caba5d9..f4421c2 100644
--- a/tests/language_2/vm/causal_async_exception_stack_test.dart
+++ b/tests/language_2/vm/causal_async_exception_stack_test.dart
@@ -34,11 +34,11 @@
     } catch (e, st) {
       expect(
           h.stringContainsInOrder(st.toString(), [
-            'thrower', '.dart:10', //
-            'generator', '.dart:19', //
-            '<asynchronous suspension>', //
-            'foo', '.dart:23', //
-            'main', //
+            'thrower', '.dart:10', // no auto-format.
+            'generator', '.dart:19', // no auto-format.
+            '<asynchronous suspension>', // no auto-format.
+            'foo', '.dart', // no auto-format.
+            'main',
           ]),
           isTrue);
     }
@@ -72,8 +72,8 @@
     } catch (e, st) {
       expect(
           h.stringContainsInOrder(st.toString(), [
-            'thrower', '.dart:10', //
-            'main.<anonymous closure>', '.dart:71', //
+            'thrower', '.dart:10', // no auto-format.
+            'main.<anonymous closure>', '.dart:71', // no auto-format.
           ]),
           isTrue);
     }
diff --git a/tests/lib/lib.status b/tests/lib/lib.status
index a592e6a..4dd40c9 100644
--- a/tests/lib/lib.status
+++ b/tests/lib/lib.status
@@ -12,8 +12,8 @@
 isolate/issue_24243_parent_isolate_test: Skip # Requires checked mode
 
 [ $runtime == ff ]
-convert/streamed_conversion_utf8_decode_test: Slow # Issue 12029
-mirrors/mirrors_reader_test: Slow # Issue 16589
+convert/streamed_conversion_utf8_decode_test: Slow, Pass # Issue 12029
+mirrors/mirrors_reader_test: Slow, Pass # Issue 16589
 
 [ $runtime == ie11 ]
 html/request_animation_frame_test: Skip # Times out. Issue 22167
@@ -31,7 +31,7 @@
 isolate/deferred_in_isolate2_test: Skip # Issue 16898. Deferred loading does not work from an isolate in CSP-mode
 
 [ $runtime == chrome && $system == linux ]
-mirrors/native_class_test: Slow
+mirrors/native_class_test: Slow, Pass
 
 [ $runtime == chrome && $system == macos ]
 convert/streamed_conversion_utf8_encode_test: SkipSlow # Times out. Issue 22050
diff --git a/tests/lib/lib_dart2js.status b/tests/lib/lib_dart2js.status
index 3119691..360147c 100644
--- a/tests/lib/lib_dart2js.status
+++ b/tests/lib/lib_dart2js.status
@@ -3,24 +3,24 @@
 # BSD-style license that can be found in the LICENSE file.
 
 [ $compiler == dart2js ]
-convert/chunked_conversion_utf88_test: Slow
-convert/utf85_test: Slow
+convert/chunked_conversion_utf88_test: Slow, Pass
+convert/utf85_test: Slow, Pass
 developer/metrics_num_test: Skip # Because of an int / double type test.
 developer/timeline_test: Skip # Not supported
 html/async_test: SkipByDesign
-html/custom/document_register_basic_test: Slow
-html/custom/document_register_type_extensions_test/construction: Slow
-html/custom/document_register_type_extensions_test/registration: Slow
-html/custom/entered_left_view_test/shadow_dom: Slow
+html/custom/document_register_basic_test: Slow, Pass
+html/custom/document_register_type_extensions_test/construction: Slow, Pass
+html/custom/document_register_type_extensions_test/registration: Slow, Pass
+html/custom/entered_left_view_test/shadow_dom: Slow, Pass
 html/custom/js_custom_test: Skip # mirrors not supported, delete this test.
 html/custom/mirrors_2_test: Skip # mirrors not supported, delete this test.
 html/custom/mirrors_test: Skip # mirrors not supported, delete this test.
-html/custom_elements_test: Slow # Issue 26789
+html/custom_elements_test: Slow, Pass # Issue 26789
 html/isolates_test: SkipByDesign
 html/mirrors_js_typed_interop_test: Skip # mirrors not supported, delete this test.
 html/worker_api_test: SkipByDesign
 html/wrapping_collections_test: SkipByDesign # Testing an issue that is only relevant to Dartium
-html/xhr_test: Slow
+html/xhr_test: Slow, Pass
 isolate/*: SkipByDesign # No support for dart:isolate in dart4web (http://dartbug.com/30538)
 mirrors/*: SkipByDesign # Mirrors not supported on web in Dart 2.0.
 typed_data/int64_list_load_store_test: SkipByDesign # dart2js does not support Int64List
@@ -38,8 +38,8 @@
 convert/streamed_conversion_utf8_decode_test: SkipSlow # Times out. Issue 22050
 
 [ $compiler == dart2js && $runtime == chromeOnAndroid ]
-html/crypto_test/functional: Slow # TODO(dart2js-team): Please triage this failure.
-html/input_element_datetime_test: Slow # TODO(dart2js-team): Please triage this failure.
+html/crypto_test/functional: Slow, Pass # TODO(dart2js-team): Please triage this failure.
+html/input_element_datetime_test: Slow, Pass # TODO(dart2js-team): Please triage this failure.
 
 [ $compiler == dart2js && $runtime == d8 ]
 html/event_callback_test: Skip # Browser test
@@ -49,7 +49,7 @@
 convert/streamed_conversion_json_utf8_decode_test: SkipSlow # Times out. Issue 22050
 convert/streamed_conversion_json_utf8_encode_test: SkipSlow # Times out. Issue 22050
 convert/streamed_conversion_utf8_decode_test: SkipSlow # Times out. Issue 22050
-convert/utf85_test: Slow
+convert/utf85_test: Slow, Pass
 html/callback_list_test: SkipByDesign # FileSystem not supported in FireFox.
 html/custom/attribute_changed_callback_test: Skip # Times out
 html/custom/created_callback_test: Skip # Times out
@@ -71,7 +71,7 @@
 html/interactive_geolocation_test: Skip # Requires allowing geo location.
 
 [ $compiler == dart2js && $checked ]
-convert/utf85_test: Slow # Issue 12029.
+convert/utf85_test: Slow, Pass # Issue 12029.
 html/js_function_getter_trust_types_test: Skip # --trust-type-annotations incompatible with --checked
 
 [ $compiler == dart2js && $csp && ($runtime == chrome || $runtime == chromeOnAndroid || $runtime == ff || $runtime == safari) ]
diff --git a/tests/lib/lib_dartdevc.status b/tests/lib/lib_dartdevc.status
index 2b4741b..4264211 100644
--- a/tests/lib/lib_dartdevc.status
+++ b/tests/lib/lib_dartdevc.status
@@ -3,7 +3,7 @@
 # BSD-style license that can be found in the LICENSE file.
 
 [ $compiler == dartdevc ]
-html/xhr_test: Slow
+html/xhr_test: Slow, Pass
 
 [ $runtime == chrome && ($compiler == dartdevc || $compiler == dartdevk) ]
 html/js_dispatch_property_test: Skip # Timeout Issue 31030
@@ -18,10 +18,10 @@
 html/xhr_test: Skip # Times out. Issue 21527
 
 [ $compiler == dartdevc || $compiler == dartdevk ]
-convert/chunked_conversion_utf88_test: Slow
-convert/json_utf8_chunk_test: Slow
-convert/streamed_conversion_utf8_decode_test: Slow # Issue 29922
-convert/utf85_test: Slow
+convert/chunked_conversion_utf88_test: Slow, Pass
+convert/json_utf8_chunk_test: Slow, Pass
+convert/streamed_conversion_utf8_decode_test: Slow, Pass # Issue 29922
+convert/utf85_test: Slow, Pass
 developer/metrics_num_test: Skip # Because of an int / double type test.
 html/callback_list_test: Skip # Test requires user interaction to accept permissions.
 html/custom/attribute_changed_callback_test: Skip # Issue 31577
diff --git a/tests/lib_2/developer/timeline_recorders_test.dart b/tests/lib_2/developer/timeline_recorders_test.dart
new file mode 100644
index 0000000..349cbba
--- /dev/null
+++ b/tests/lib_2/developer/timeline_recorders_test.dart
@@ -0,0 +1,23 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// VMOptions=--timeline_streams=VM,Isolate,GC,Dart --timeline_recorder=endless
+/// VMOptions=--timeline_streams=VM,Isolate,GC,Dart --timeline_recorder=ring
+/// VMOptions=--timeline_streams=VM,Isolate,GC,Dart --timeline_recorder=startup
+/// VMOptions=--timeline_streams=VM,Isolate,GC,Dart --timeline_recorder=systrace
+
+import 'dart:developer';
+
+void main() {
+  Timeline.startSync('A');
+
+  Timeline.instantSync('B');
+
+  var task = new TimelineTask();
+  task.start('C');
+  task.instant('D');
+  task.finish();
+
+  Timeline.finishSync();
+}
diff --git a/tests/lib_2/isolate/unboxed_double_snapshot_writer_test.dart b/tests/lib_2/isolate/unboxed_double_snapshot_writer_test.dart
new file mode 100644
index 0000000..132ad6b
--- /dev/null
+++ b/tests/lib_2/isolate/unboxed_double_snapshot_writer_test.dart
@@ -0,0 +1,34 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:isolate';
+import 'dart:typed_data';
+
+import 'package:expect/expect.dart';
+
+double getDoubleWithHeapObjectTag() {
+  final bd = ByteData(8);
+  bd.setUint64(0, 0x8000000000000001, Endian.host);
+  final double v = bd.getFloat64(0, Endian.host);
+  return v;
+}
+
+class Foo {
+  final double x = getDoubleWithHeapObjectTag();
+  final String name = "Foo Class";
+  Foo();
+}
+
+main(args) async {
+  final receivePort = new ReceivePort();
+
+  receivePort.sendPort.send(Foo());
+  final it = StreamIterator(receivePort);
+  Expect.isTrue(await it.moveNext());
+  final Foo receivedFoo = it.current as Foo;
+  Expect.equals(receivedFoo.x, getDoubleWithHeapObjectTag());
+  Expect.equals(receivedFoo.name, "Foo Class");
+  await it.cancel();
+}
diff --git a/tests/lib_2/lib_2.status b/tests/lib_2/lib_2.status
index a592e6a..4dd40c9 100644
--- a/tests/lib_2/lib_2.status
+++ b/tests/lib_2/lib_2.status
@@ -12,8 +12,8 @@
 isolate/issue_24243_parent_isolate_test: Skip # Requires checked mode
 
 [ $runtime == ff ]
-convert/streamed_conversion_utf8_decode_test: Slow # Issue 12029
-mirrors/mirrors_reader_test: Slow # Issue 16589
+convert/streamed_conversion_utf8_decode_test: Slow, Pass # Issue 12029
+mirrors/mirrors_reader_test: Slow, Pass # Issue 16589
 
 [ $runtime == ie11 ]
 html/request_animation_frame_test: Skip # Times out. Issue 22167
@@ -31,7 +31,7 @@
 isolate/deferred_in_isolate2_test: Skip # Issue 16898. Deferred loading does not work from an isolate in CSP-mode
 
 [ $runtime == chrome && $system == linux ]
-mirrors/native_class_test: Slow
+mirrors/native_class_test: Slow, Pass
 
 [ $runtime == chrome && $system == macos ]
 convert/streamed_conversion_utf8_encode_test: SkipSlow # Times out. Issue 22050
diff --git a/tests/lib_2/lib_2_dart2js.status b/tests/lib_2/lib_2_dart2js.status
index 784ae82..db9b90d 100644
--- a/tests/lib_2/lib_2_dart2js.status
+++ b/tests/lib_2/lib_2_dart2js.status
@@ -3,24 +3,24 @@
 # BSD-style license that can be found in the LICENSE file.
 
 [ $compiler == dart2js ]
-convert/chunked_conversion_utf88_test: Slow
-convert/utf85_test: Slow
+convert/chunked_conversion_utf88_test: Slow, Pass
+convert/utf85_test: Slow, Pass
 developer/metrics_num_test: Skip # Because of an int / double type test.
 developer/timeline_test: Skip # Not supported
 html/async_test: SkipByDesign
-html/custom/document_register_basic_test: Slow
-html/custom/document_register_type_extensions_test/construction: Slow
-html/custom/document_register_type_extensions_test/registration: Slow
-html/custom/entered_left_view_test/shadow_dom: Slow
+html/custom/document_register_basic_test: Slow, Pass
+html/custom/document_register_type_extensions_test/construction: Slow, Pass
+html/custom/document_register_type_extensions_test/registration: Slow, Pass
+html/custom/entered_left_view_test/shadow_dom: Slow, Pass
 html/custom/js_custom_test: Skip # mirrors not supported, delete this test.
 html/custom/mirrors_2_test: Skip # mirrors not supported, delete this test.
 html/custom/mirrors_test: Skip # mirrors not supported, delete this test.
-html/custom_elements_test: Slow # Issue 26789
+html/custom_elements_test: Slow, Pass # Issue 26789
 html/isolates_test: SkipByDesign
 html/mirrors_js_typed_interop_test: Skip # mirrors not supported, delete this test.
 html/worker_api_test: SkipByDesign
 html/wrapping_collections_test: SkipByDesign # Testing an issue that is only relevant to Dartium
-html/xhr_test: Slow
+html/xhr_test: Slow, Pass
 isolate/*: SkipByDesign # No support for dart:isolate in dart4web (http://dartbug.com/30538)
 mirrors/*: SkipByDesign # Mirrors not supported on web in Dart 2.0.
 wasm/*: SkipByDesign # dart:wasm not currently supported on web.
@@ -35,8 +35,8 @@
 convert/streamed_conversion_utf8_decode_test: SkipSlow # Times out. Issue 22050
 
 [ $compiler == dart2js && $runtime == chromeOnAndroid ]
-html/crypto_test/functional: Slow # TODO(dart2js-team): Please triage this failure.
-html/input_element_datetime_test: Slow # TODO(dart2js-team): Please triage this failure.
+html/crypto_test/functional: Slow, Pass # TODO(dart2js-team): Please triage this failure.
+html/input_element_datetime_test: Slow, Pass # TODO(dart2js-team): Please triage this failure.
 
 [ $compiler == dart2js && $runtime == d8 ]
 html/*: SkipByDesign # Browser test
@@ -46,7 +46,7 @@
 convert/streamed_conversion_json_utf8_decode_test: SkipSlow # Times out. Issue 22050
 convert/streamed_conversion_json_utf8_encode_test: SkipSlow # Times out. Issue 22050
 convert/streamed_conversion_utf8_decode_test: SkipSlow # Times out. Issue 22050
-convert/utf85_test: Slow
+convert/utf85_test: Slow, Pass
 html/callback_list_test: SkipByDesign # FileSystem not supported in FireFox.
 html/custom/attribute_changed_callback_test: Skip # Times out
 html/custom/created_callback_test: Skip # Times out
@@ -68,7 +68,7 @@
 html/interactive_geolocation_test: Skip # Requires allowing geo location.
 
 [ $compiler == dart2js && $checked ]
-convert/utf85_test: Slow # Issue 12029.
+convert/utf85_test: Slow, Pass # Issue 12029.
 html/js_function_getter_trust_types_test: Skip # --trust-type-annotations incompatible with --checked
 
 [ $compiler == dart2js && $csp && ($runtime == chrome || $runtime == chromeOnAndroid || $runtime == ff || $runtime == safari) ]
diff --git a/tests/lib_2/lib_2_dartdevc.status b/tests/lib_2/lib_2_dartdevc.status
index 7a07129..ae2ca1a 100644
--- a/tests/lib_2/lib_2_dartdevc.status
+++ b/tests/lib_2/lib_2_dartdevc.status
@@ -3,7 +3,7 @@
 # BSD-style license that can be found in the LICENSE file.
 
 [ $compiler == dartdevc ]
-html/xhr_test: Slow
+html/xhr_test: Slow, Pass
 
 [ $runtime == chrome && ($compiler == dartdevc || $compiler == dartdevk) ]
 html/js_dispatch_property_test: Skip # Timeout Issue 31030
@@ -18,10 +18,10 @@
 html/xhr_test: Skip # Times out. Issue 21527
 
 [ $compiler == dartdevc || $compiler == dartdevk ]
-convert/chunked_conversion_utf88_test: Slow
-convert/json_utf8_chunk_test: Slow
-convert/streamed_conversion_utf8_decode_test: Slow # Issue 29922
-convert/utf85_test: Slow
+convert/chunked_conversion_utf88_test: Slow, Pass
+convert/json_utf8_chunk_test: Slow, Pass
+convert/streamed_conversion_utf8_decode_test: Slow, Pass # Issue 29922
+convert/utf85_test: Slow, Pass
 developer/metrics_num_test: Skip # Because of an int / double type test.
 html/callback_list_test: Skip # Test requires user interaction to accept permissions.
 html/custom/attribute_changed_callback_test: Skip # Issue 31577
diff --git a/tests/standalone/io/issue_32052_test.dart b/tests/standalone/io/issue_32052_test.dart
new file mode 100644
index 0000000..b39f816
--- /dev/null
+++ b/tests/standalone/io/issue_32052_test.dart
@@ -0,0 +1,20 @@
+// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:cli';
+
+import 'package:async_helper/async_helper.dart';
+import 'package:expect/expect.dart';
+
+main() {
+  asyncStart();
+  Completer<Null> c = new Completer<Null>();
+  Timer.run(() {
+    c.complete(null);
+    asyncEnd();
+  });
+  Null result = waitFor<Null>(c.future);
+  Expect.isNull(result);
+}
diff --git a/tests/standalone/io/wait_for_error_test.dart b/tests/standalone/io/wait_for_error_test.dart
new file mode 100644
index 0000000..a3b71c5
--- /dev/null
+++ b/tests/standalone/io/wait_for_error_test.dart
@@ -0,0 +1,19 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:cli';
+
+import 'package:async_helper/async_helper.dart';
+import 'package:expect/expect.dart';
+
+main() {
+  asyncStart();
+  Completer<bool> c = new Completer<bool>();
+  Timer.run(() {
+    c.completeError("Error", StackTrace.current);
+    asyncEnd();
+  });
+  Expect.throws(() => waitFor<bool>(c.future), (e) => e is AsyncError);
+}
diff --git a/tests/standalone/io/wait_for_exception_test.dart b/tests/standalone/io/wait_for_exception_test.dart
new file mode 100644
index 0000000..f5c207d
--- /dev/null
+++ b/tests/standalone/io/wait_for_exception_test.dart
@@ -0,0 +1,24 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:cli';
+
+import 'package:async_helper/async_helper.dart';
+import 'package:expect/expect.dart';
+
+main() {
+  asyncStart();
+  Completer<bool> c = new Completer<bool>();
+  runZoned(() {
+    Timer.run(() {
+      asyncEnd();
+      throw "Error";
+    });
+  }, onError: (e) {
+    Expect.isTrue(e is String);
+    c.complete(true);
+  });
+  Expect.isTrue(waitFor<bool>(c.future));
+}
diff --git a/tests/standalone/io/wait_for_test.dart b/tests/standalone/io/wait_for_test.dart
new file mode 100644
index 0000000..a8ac543
--- /dev/null
+++ b/tests/standalone/io/wait_for_test.dart
@@ -0,0 +1,21 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:mirrors';
+import 'dart:cli';
+
+import 'package:async_helper/async_helper.dart';
+import 'package:expect/expect.dart';
+
+main() {
+  asyncStart();
+  Completer<bool> c = new Completer<bool>();
+  Timer.run(() {
+    c.complete(true);
+    asyncEnd();
+  });
+  bool result = waitFor<bool>(c.future);
+  Expect.isTrue(result);
+}
diff --git a/tests/standalone/io/wait_for_timeout_test.dart b/tests/standalone/io/wait_for_timeout_test.dart
new file mode 100644
index 0000000..2b239fa
--- /dev/null
+++ b/tests/standalone/io/wait_for_timeout_test.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:cli';
+
+import 'package:async_helper/async_helper.dart';
+import 'package:expect/expect.dart';
+
+main() {
+  asyncStart();
+  Completer<bool> c = new Completer<bool>();
+  Expect.throws(() {
+    waitFor<bool>(c.future, timeout: const Duration(seconds: 1));
+  }, (e) => e is TimeoutException);
+  asyncEnd();
+}
diff --git a/tests/standalone/standalone.status b/tests/standalone/standalone.status
index 2518819..59dca0b 100644
--- a/tests/standalone/standalone.status
+++ b/tests/standalone/standalone.status
@@ -13,7 +13,7 @@
 packages_file_test/none: Skip # contains no tests.
 
 [ $builder_tag == asan ]
-io/process_detached_test: Slow
+io/process_detached_test: Slow, Pass
 
 [ $builder_tag == no_ipv6 ]
 io/http_ipv6_test: SkipByDesign
@@ -70,8 +70,8 @@
 dwarf_stack_trace_test: SkipByDesign # Due to instruction canonicalization we can end up having the wrong names in stack traces.
 
 [ $runtime == vm && $system == linux ]
-io/http_basic_test: Slow # Issue 28046, These tests might be slow on an opt counter threshold bot. They also time out on the bot occasionally => flaky test issue 28046
-io/http_launch_test: Slow # Issue 28046, These tests might be slow on an opt counter threshold bot. They also time out on the bot occasionally => flaky test issue 28046
+io/http_basic_test: Slow, Pass # Issue 28046, These tests might be slow on an opt counter threshold bot. They also time out on the bot occasionally => flaky test issue 28046
+io/http_launch_test: Slow, Pass # Issue 28046, These tests might be slow on an opt counter threshold bot. They also time out on the bot occasionally => flaky test issue 28046
 
 [ $system == macos && ($runtime == dart_precompiled || $runtime == vm) ]
 io/raw_secure_server_socket_test: Crash
diff --git a/tests/standalone/standalone_kernel.status b/tests/standalone/standalone_kernel.status
index b967e9f..cfbe667 100644
--- a/tests/standalone/standalone_kernel.status
+++ b/tests/standalone/standalone_kernel.status
@@ -18,7 +18,7 @@
 io/file_lock_test: SkipSlow # Timeout
 
 [ $arch == simarm64 && ($compiler == dartk || $compiler == dartkb) ]
-io/http_bind_test: Slow
+io/http_bind_test: Slow, Pass
 
 [ $builder_tag == optimization_counter_threshold && ($compiler == dartk || $compiler == dartkb) ]
 map_insert_remove_oom_test: Skip # Heap limit too low.
@@ -58,7 +58,7 @@
 no_support_debugger_test: Skip # kernel-service snapshot not compatible with flag disabled
 
 [ $mode == debug && $runtime == vm && ($compiler == dartk || $compiler == dartkb) ]
-io/file_lock_test: Slow
+io/file_lock_test: Slow, Pass
 io/raw_socket_test: Crash
 io/socket_exception_test: Crash
 io/socket_finalizer_test: Crash
@@ -73,7 +73,7 @@
 no_support_debugger_test: Skip # kernel-service snapshot not compatible with flag disabled
 
 [ $system == windows && ($compiler == dartk || $compiler == dartkb) ]
-io/dart_std_io_pipe_test: Slow
+io/dart_std_io_pipe_test: Slow, Pass
 io/secure_builtin_roots_test: Skip # Issues 32137 and 32138.
 io/wait_for_event_isolate_test: Skip # Issues 32137 and 32138.
 map_insert_remove_oom_test: Skip # Heap limit too low.
@@ -84,14 +84,14 @@
 
 [ $hot_reload_rollback && ($compiler == dartk || $compiler == dartkb) ]
 io/directory_chdir_test: Skip # Timeout
-io/echo_server_stream_test: Slow
+io/echo_server_stream_test: Slow, Pass
 
 # Enabling of dartk for sim{arm,arm64} revealed these test failures, which
 # are to be triaged.  Isolate tests are skipped on purpose due to the usage of
 # batch mode.
 [ ($arch == simarm || $arch == simarm64) && ($compiler == dartk || $compiler == dartkb) ]
 io/file_blocking_lock_test: Crash # Please triage.
-io/file_lock_test: Slow
+io/file_lock_test: Slow, Pass
 map_insert_remove_oom_test: Skip # Heap limit too low.
 
 [ ($compiler == dartk || $compiler == dartkb) && ($hot_reload || $hot_reload_rollback) ]
diff --git a/tests/standalone_2/io/http_parser_test.dart b/tests/standalone_2/io/http_parser_test.dart
index 06ed070..6951916 100644
--- a/tests/standalone_2/io/http_parser_test.dart
+++ b/tests/standalone_2/io/http_parser_test.dart
@@ -251,8 +251,6 @@
         }
       }
 
-      ;
-
       var subscription = httpParser.listen((incoming) {
         port.close();
         statusCode = incoming.statusCode;
@@ -313,7 +311,6 @@
       _HttpParser httpParser = new _HttpParser.responseParser();
       StreamController<Uint8List> controller = new StreamController(sync: true);
       bool errorCalled = false;
-      ;
 
       if (chunkSize == -1) chunkSize = requestData.length;
 
@@ -785,6 +782,9 @@
     response = "HTTP/1.1 OK\r\nContent-Length: 0\r\n\r\n";
     _testParseInvalidResponse(response);
 
+    response = "HTTP/1.1 20A OK\r\nContent-Length: 0\r\n\r\n";
+    _testParseInvalidResponse(response);
+
     response = "200 OK\r\nContent-Length: 0\r\n\r\n";
     _testParseInvalidResponse(response);
 
diff --git a/tests/standalone_2/standalone_2.status b/tests/standalone_2/standalone_2.status
index 66306a1e..1fa495c 100644
--- a/tests/standalone_2/standalone_2.status
+++ b/tests/standalone_2/standalone_2.status
@@ -13,7 +13,7 @@
 packages_file_test/none: Skip # contains no tests.
 
 [ $builder_tag == asan ]
-io/process_detached_test: Slow
+io/process_detached_test: Slow, Pass
 
 [ $builder_tag == no_ipv6 ]
 io/http_ipv6_test: SkipByDesign
@@ -67,8 +67,8 @@
 env_test: Skip # This is testing a vm command line parsing scenario.
 
 [ $runtime == vm && $system == linux ]
-io/http_basic_test: Slow # Issue 28046, These tests might be slow on an opt counter threshold bot. They also time out on the bot occasionally => flaky test issue 28046
-io/http_launch_test: Slow # Issue 28046, These tests might be slow on an opt counter threshold bot. They also time out on the bot occasionally => flaky test issue 28046
+io/http_basic_test: Slow, Pass # Issue 28046, These tests might be slow on an opt counter threshold bot. They also time out on the bot occasionally => flaky test issue 28046
+io/http_launch_test: Slow, Pass # Issue 28046, These tests might be slow on an opt counter threshold bot. They also time out on the bot occasionally => flaky test issue 28046
 
 [ $system == macos && ($runtime == dart_precompiled || $runtime == vm) ]
 io/raw_secure_server_socket_test: Crash
diff --git a/tests/standalone_2/standalone_2_kernel.status b/tests/standalone_2/standalone_2_kernel.status
index b967e9f..cfbe667 100644
--- a/tests/standalone_2/standalone_2_kernel.status
+++ b/tests/standalone_2/standalone_2_kernel.status
@@ -18,7 +18,7 @@
 io/file_lock_test: SkipSlow # Timeout
 
 [ $arch == simarm64 && ($compiler == dartk || $compiler == dartkb) ]
-io/http_bind_test: Slow
+io/http_bind_test: Slow, Pass
 
 [ $builder_tag == optimization_counter_threshold && ($compiler == dartk || $compiler == dartkb) ]
 map_insert_remove_oom_test: Skip # Heap limit too low.
@@ -58,7 +58,7 @@
 no_support_debugger_test: Skip # kernel-service snapshot not compatible with flag disabled
 
 [ $mode == debug && $runtime == vm && ($compiler == dartk || $compiler == dartkb) ]
-io/file_lock_test: Slow
+io/file_lock_test: Slow, Pass
 io/raw_socket_test: Crash
 io/socket_exception_test: Crash
 io/socket_finalizer_test: Crash
@@ -73,7 +73,7 @@
 no_support_debugger_test: Skip # kernel-service snapshot not compatible with flag disabled
 
 [ $system == windows && ($compiler == dartk || $compiler == dartkb) ]
-io/dart_std_io_pipe_test: Slow
+io/dart_std_io_pipe_test: Slow, Pass
 io/secure_builtin_roots_test: Skip # Issues 32137 and 32138.
 io/wait_for_event_isolate_test: Skip # Issues 32137 and 32138.
 map_insert_remove_oom_test: Skip # Heap limit too low.
@@ -84,14 +84,14 @@
 
 [ $hot_reload_rollback && ($compiler == dartk || $compiler == dartkb) ]
 io/directory_chdir_test: Skip # Timeout
-io/echo_server_stream_test: Slow
+io/echo_server_stream_test: Slow, Pass
 
 # Enabling of dartk for sim{arm,arm64} revealed these test failures, which
 # are to be triaged.  Isolate tests are skipped on purpose due to the usage of
 # batch mode.
 [ ($arch == simarm || $arch == simarm64) && ($compiler == dartk || $compiler == dartkb) ]
 io/file_blocking_lock_test: Crash # Please triage.
-io/file_lock_test: Slow
+io/file_lock_test: Slow, Pass
 map_insert_remove_oom_test: Skip # Heap limit too low.
 
 [ ($compiler == dartk || $compiler == dartkb) && ($hot_reload || $hot_reload_rollback) ]
diff --git a/tools/VERSION b/tools/VERSION
index 3140836..fe48ed7 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -33,7 +33,7 @@
 MAJOR 2
 MINOR 8
 PATCH 0
-PRERELEASE 6
+PRERELEASE 7
 PRERELEASE_PATCH 0
 ABI_VERSION 28
 OLDEST_SUPPORTED_ABI_VERSION 28
diff --git a/tools/bots/get_builder_status.dart b/tools/bots/get_builder_status.dart
index 9ad188b..9ec200e 100755
--- a/tools/bots/get_builder_status.dart
+++ b/tools/bots/get_builder_status.dart
@@ -155,9 +155,7 @@
     final groups = <String>{
       for (Map document in documents)
         if (document.containsKey('document'))
-          document['document']['fields']['builder']['stringValue']
-              .split('-')
-              .first
+          document['document']['name'].split('/').last.split('-').first
     };
     String fragment = [
       'showLatestFailures=true',
diff --git a/tools/bots/post_results_to_pubsub.dart b/tools/bots/post_results_to_pubsub.dart
index d864765..92e91d1 100644
--- a/tools/bots/post_results_to_pubsub.dart
+++ b/tools/bots/post_results_to_pubsub.dart
@@ -32,7 +32,7 @@
   exit(1);
 }
 
-const resultsPerMessage = 100;
+const resultsPerMessage = 50;
 const postUrl =
     'https://pubsub.googleapis.com/v1/projects/dart-ci/topics/results:publish';
 
diff --git a/tools/bots/test_matrix.json b/tools/bots/test_matrix.json
index a3128d6..17a1c39 100644
--- a/tools/bots/test_matrix.json
+++ b/tools/bots/test_matrix.json
@@ -46,6 +46,7 @@
       "tests/search/",
       "tests/standalone_2/",
       "tests/ffi/",
+      "tests/ffi_2/",
       "third_party/babel/babel.min.js",
       "third_party/d8/",
       "third_party/observatory_pub_packages/packages/web_components/",
@@ -87,6 +88,7 @@
       "tests/search/",
       "tests/standalone_2/",
       "tests/ffi/",
+      "tests/ffi_2/",
       "third_party/babel/babel.min.js",
       "third_party/d8/",
       "third_party/observatory_pub_packages/packages/web_components/",
@@ -128,6 +130,7 @@
       "tests/search/",
       "tests/standalone_2/",
       "tests/ffi/",
+      "tests/ffi_2/",
       "third_party/d8/",
       "third_party/pkg/",
       "third_party/pkg_tested/",
@@ -208,6 +211,7 @@
       "tests/search/",
       "tests/standalone_2/",
       "tests/ffi/",
+      "tests/ffi_2/",
       "third_party/d8/",
       "third_party/pkg/",
       "third_party/pkg_tested/",
@@ -305,6 +309,7 @@
       "tests/search/",
       "tests/standalone_2/",
       "tests/ffi/",
+      "tests/ffi_2/",
       "pkg/_fe_analyzer_shared/",
       "pkg/async_helper/",
       "pkg/build_integration/",
@@ -336,7 +341,8 @@
         "runtime": "vm",
         "timeout": 240,
         "use-sdk": true
-    }},
+      }
+    },
     "unittest-asserts-(debug|product|release)-(linux|mac|win)": {
       "options": {
         "compiler": "dartk",
@@ -344,7 +350,8 @@
         "runtime": "vm",
         "timeout": 240,
         "use-sdk": true
-    }},
+      }
+    },
     "analyzer-unittest-asserts-(debug|product|release)-(linux|mac|win)": {
       "options": {
         "compiler": "dartk",
@@ -353,7 +360,8 @@
         "timeout": 240,
         "use-sdk": true,
         "builder-tag": "analyzer"
-    }},
+      }
+    },
     "cfe-unittest-asserts-(debug|product|release)-(linux|mac|win)": {
       "options": {
         "compiler": "dartk",
@@ -362,7 +370,8 @@
         "timeout": 240,
         "use-sdk": true,
         "builder-tag": "cfe"
-    }},
+      }
+    },
     "unittest-asserts-no-sdk-(linux|mac|win)": {
       "options": {
         "compiler": "dartk",
@@ -370,208 +379,299 @@
         "mode": "release",
         "runtime": "vm",
         "timeout": 240
-    }},
+      }
+    },
     "unittest-analyzer_use_fasta-(linux|mac|win)": {
       "options": {
         "compiler": "none",
         "runtime": "vm",
         "mode": "release",
         "use-sdk": true,
-        "vm-options": ["-DuseFastaParser=true"],
+        "vm-options": [
+          "-DuseFastaParser=true"
+        ],
         "builder-tag": "analyzer_use_fasta"
-    }},
+      }
+    },
     "dartk-asan-(linux|mac|win)-(debug|product|release)-(ia32|x64)": {
       "options": {
         "builder-tag": "asan",
         "timeout": 240
-    }},
+      }
+    },
     "dartk-lsan-(linux|mac|win)-(debug|product|release)-(ia32|x64)": {
       "options": {
         "builder-tag": "lsan",
         "timeout": 240
-    }},
+      }
+    },
     "dartk-msan-(linux|mac|win)-(debug|product|release)-(ia32|x64)": {
       "options": {
         "builder-tag": "msan",
         "timeout": 240
-    }},
+      }
+    },
     "dartk-tsan-(linux|mac|win)-(debug|product|release)-x64": {
       "options": {
         "builder-tag": "tsan",
         "timeout": 240
-    }},
+      }
+    },
     "dartk-ubsan-(linux|mac|win)-(debug|product|release)-(ia32|x64)": {
       "options": {
         "builder-tag": "ubsan",
         "timeout": 240
-    }},
+      }
+    },
     "dart2js-(linux|mac|win)-chrome": {
       "options": {
         "use-sdk": true
-    }},
+      }
+    },
     "dart2js-weak-(linux|mac|win)-x64-d8": {
       "options": {
         "builder-tag": "dart2js-weak",
-        "enable-experiment": ["non-nullable"],
-        "dart2js-options": ["--no-runtime-null-safety"],
+        "enable-experiment": [
+          "non-nullable"
+        ],
+        "dart2js-options": [
+          "--no-runtime-null-safety"
+        ],
         "use-sdk": true
-    }},
+      }
+    },
     "dart2js-(linux|win)-firefox": {
       "options": {
         "use-sdk": true
-    }},
+      }
+    },
     "dart2js-win-ie11": {
       "options": {
         "use-sdk": true,
         "babel": "{\"presets\":[\"es2015\"]}"
-    }},
+      }
+    },
     "dart2js-win-edge": {
       "options": {
         "use-sdk": true
-    }},
+      }
+    },
     "dart2js-mac-safari": {
       "options": {
         "use-sdk": true
-    }},
+      }
+    },
     "dart2js-minified-csp-(linux|mac|win)-chrome": {
       "options": {
         "minified": true,
         "csp": true,
         "use-sdk": true
-    }},
+      }
+    },
     "dart2js-minified-(linux|mac|win)-d8": {
       "options": {
         "minified": true,
         "use-sdk": true
-    }},
+      }
+    },
     "dart2js-production-(linux|mac|win)-d8": {
       "options": {
         "builder-tag": "dart2js_production",
         "use-sdk": true,
-        "dart2js-options": ["-O3"]
-    }},
+        "dart2js-options": [
+          "-O3"
+        ]
+      }
+    },
     "dart2js-hostasserts-(linux|mac|win)-(ia32|x64)-d8": {
       "options": {
         "host-checked": true
-    }},
+      }
+    },
     "dart2js-hostasserts-weak-(linux|mac|win)-x64-d8": {
       "options": {
         "builder-tag": "dart2js-weak",
-        "enable-experiment": ["non-nullable"],
-        "dart2js-options": ["--no-runtime-null-safety"],
+        "enable-experiment": [
+          "non-nullable"
+        ],
+        "dart2js-options": [
+          "--no-runtime-null-safety"
+        ],
         "host-checked": true
-    }},
+      }
+    },
     "dart2js-old-rti-(linux|mac|win)-x64-d8": {
       "options": {
         "builder-tag": "old_rti",
-        "dart2js-options": ["--use-old-rti"],
+        "dart2js-options": [
+          "--use-old-rti"
+        ],
         "host-checked": true
-    }},
+      }
+    },
     "dart2js-old-rti-minified-csp-(linux|mac|win)-x64-d8": {
       "options": {
         "builder-tag": "old_rti",
         "csp": true,
-        "dart2js-options": ["--use-old-rti"],
+        "dart2js-options": [
+          "--use-old-rti"
+        ],
         "minified": true,
         "use-sdk": true
-    }},
+      }
+    },
     "dartkp-android-(debug|product|release)-arm_x64": {
       "options": {
         "builder-tag": "crossword",
         "use-elf": true
-    }},
+      }
+    },
     "dartkp-android-(debug|product|release)-(arm|arm64)": {
       "options": {
         "use-elf": true
-    }},
+      }
+    },
     "dartk-android-(debug|product|release)-(arm|arm64)": {},
     "dartkp-(linux|win|mac)-(debug|product|release)-(simarm|simarm64)": {
       "options": {
         "use-blobs": true
-    }},
+      }
+    },
     "dartkp-linux-(debug|product|release)-simarm-crossword": {
       "options": {
         "builder-tag": "crossword"
-    }},
+      }
+    },
     "dartkp-(win|mac)-(debug|product|release)-simarm-crossword": {
       "options": {
         "builder-tag": "crossword",
         "use-blobs": true
-    }},
+      }
+    },
     "dartkp-win-(product|release)-x64": {
       "options": {
         "use-elf": true
-    }},
+      }
+    },
     "dartkp-win-debug-x64": {
       "options": {
         "use-elf": true,
-        "vm-options": ["--no-enable-malloc-hooks"]
-    }},
-    "dartkp-(linux|mac)-(product|release)-x64": { },
+        "vm-options": [
+          "--no-enable-malloc-hooks"
+        ]
+      }
+    },
+    "dartkp-(linux|mac)-(product|release)-x64": {},
     "dartkp-obfuscate-(linux|mac|win)-(debug|product|release)-x64": {
       "options": {
         "builder-tag": "obfuscated",
-        "vm-options": ["--obfuscate"]
-    }},
+        "vm-options": [
+          "--obfuscate"
+        ]
+      }
+    },
     "dartkp-(linux|mac)-debug-x64": {
       "options": {
-        "vm-options": ["--no-enable-malloc-hooks"]
-    }},
+        "vm-options": [
+          "--no-enable-malloc-hooks"
+        ]
+      }
+    },
     "dartkp-no-bare-(linux|mac|win)-(debug|product|release)-x64": {
       "options": {
-        "vm-options": ["--no-enable-malloc-hooks", "--no-use-bare-instructions"]
-    }},
+        "vm-options": [
+          "--no-enable-malloc-hooks",
+          "--no-use-bare-instructions"
+        ]
+      }
+    },
     "dartkp-no-bare-(linux|mac|win)-(debug|product|release)-(simarm|simarm64)": {
       "options": {
-        "vm-options": ["--no-enable-malloc-hooks", "--no-use-bare-instructions"],
+        "vm-options": [
+          "--no-enable-malloc-hooks",
+          "--no-use-bare-instructions"
+        ],
         "use-elf": true
-    }},
-    "dartk-(linux|mac|win)-(debug|product|release)-(ia32|x64)": { },
+      }
+    },
+    "dartk-(linux|mac|win)-(debug|product|release)-(ia32|x64)": {},
     "dartk-weak-asserts-(linux|mac|win)-(debug|product|release)-x64": {
       "options": {
-        "enable-experiment": ["non-nullable"],
+        "enable-experiment": [
+          "non-nullable"
+        ],
         "enable-asserts": true
-    }},
+      }
+    },
     "dartk-(linux|mac|win)-(debug|product|release)-(ia32|simarm|simarm64|x64)-ast": {
       "options": {
         "builder-tag": "ast",
-        "gen-kernel-options": ["--no-gen-bytecode"]
-    }},
+        "gen-kernel-options": [
+          "--no-gen-bytecode"
+        ]
+      }
+    },
     "dartkp-(linux|mac)-(debug|product|release)-x64-ast": {
       "options": {
         "builder-tag": "ast",
-        "gen-kernel-options": ["--no-gen-bytecode"]
-    }},
+        "gen-kernel-options": [
+          "--no-gen-bytecode"
+        ]
+      }
+    },
     "dartkp-(linux|mac)-(debug|product|release)-simarm64-ast": {
-       "options": {
+      "options": {
         "builder-tag": "ast",
         "use-blobs": true,
-        "gen-kernel-options": ["--no-gen-bytecode"]
-    }},
+        "gen-kernel-options": [
+          "--no-gen-bytecode"
+        ]
+      }
+    },
     "dartkp-linux-(debug|product|release)-simarm-crossword-ast": {
       "options": {
         "builder-tag": "crossword_ast",
-        "gen-kernel-options": ["--no-gen-bytecode"]
-    }},
+        "gen-kernel-options": [
+          "--no-gen-bytecode"
+        ]
+      }
+    },
     "dartk-checked-(linux|mac|win)-(debug|product|release)-(ia32|x64)": {
       "options": {
         "enable-asserts": true
-    }},
-    "dartk-(linux|mac|win)-(debug|product|release)-(arm64|simarm|simarm64)": { },
+      }
+    },
+    "dartk-(linux|mac|win)-(debug|product|release)-(arm64|simarm|simarm64)": {},
     "dartk-optcounter-(linux|mac|win)-(debug|product|release)-(ia32|x64)": {
       "options": {
         "builder-tag": "optimization_counter_threshold",
-        "vm-options": ["--optimization-counter-threshold=5", "--random-seed=__RANDOM__"]
-    }},
+        "vm-options": [
+          "--optimization-counter-threshold=5",
+          "--random-seed=__RANDOM__"
+        ]
+      }
+    },
     "dartk-reload-(linux|mac|win)-(debug|product|release)-(ia32|x64)": {
       "options": {
         "hot-reload": true
-    }},
+      }
+    },
     "dartk-reload-rollback-(linux|mac|win)-(debug|product|release)-(ia32|x64)": {
       "options": {
         "hot-reload-rollback": true
-    }},
-    "app_jitk-(linux|mac|win)-(debug|product|release)-(ia32|x64)": { },
+      }
+    },
+    "dartk-linux-(debug|product|release)-arm-qemu": {
+      "options": {
+        "use-qemu": true
+      }
+    },
+    "dartkp-linux-(debug|product|release)-arm-qemu": {
+      "options": {
+        "use-qemu": true
+      }
+    },
+    "app_jitk-(linux|mac|win)-(debug|product|release)-(ia32|x64)": {},
     "dartkb-interpret-(linux|mac|win)-product-(ia32|x64|arm|arm64|simarm|simarm64)": {
       "options": {
         "builder-tag": "bytecode_interpreter",
@@ -580,8 +680,12 @@
           "--drop-ast",
           "--bytecode-options=source-positions,annotations"
         ],
-        "vm-options": ["--enable_interpreter", "--compilation-counter-threshold=-1"]
-    }},
+        "vm-options": [
+          "--enable_interpreter",
+          "--compilation-counter-threshold=-1"
+        ]
+      }
+    },
     "dartkb-interpret-(linux|mac|win)-(debug|release)-(ia32|x64|arm|arm64|simarm|simarm64)": {
       "options": {
         "builder-tag": "bytecode_interpreter",
@@ -590,8 +694,12 @@
           "--drop-ast",
           "--bytecode-options=source-positions,annotations,local-var-info,debugger-stops"
         ],
-        "vm-options": ["--enable_interpreter", "--compilation-counter-threshold=-1"]
-    }},
+        "vm-options": [
+          "--enable_interpreter",
+          "--compilation-counter-threshold=-1"
+        ]
+      }
+    },
     "dartkb-mixed-(linux|mac|win)-(debug|release)-(ia32|x64|arm|arm64|simarm|simarm64)": {
       "options": {
         "builder-tag": "bytecode_mixed",
@@ -600,8 +708,11 @@
           "--drop-ast",
           "--bytecode-options=source-positions,annotations,local-var-info,debugger-stops"
         ],
-        "vm-options": ["--enable_interpreter"]
-    }},
+        "vm-options": [
+          "--enable_interpreter"
+        ]
+      }
+    },
     "dartkb-mixed-(linux|mac|win)-product-(ia32|x64|arm|arm64|simarm|simarm64)": {
       "options": {
         "builder-tag": "bytecode_mixed",
@@ -610,63 +721,83 @@
           "--drop-ast",
           "--bytecode-options=source-positions,annotations"
         ],
-        "vm-options": ["--enable_interpreter"]
-    }},
+        "vm-options": [
+          "--enable_interpreter"
+        ]
+      }
+    },
     "dartdevk-checked-(linux|mac|win)-(debug|product|release)-(chrome|firefox)": {
       "options": {
         "checked": true,
         "use-sdk": true
-    }},
+      }
+    },
     "dartdevk-strong-linux-release-chrome": {
       "options": {
         "checked": true,
         "use-sdk": true,
-        "enable-experiment": ["non-nullable"],
+        "enable-experiment": [
+          "non-nullable"
+        ],
         "enable-asserts": true
-
-    }},
+      }
+    },
     "dartdevk-weak-linux-release-chrome": {
       "options": {
         "checked": true,
         "use-sdk": true,
-        "enable-experiment": ["non-nullable"],
+        "enable-experiment": [
+          "non-nullable"
+        ],
         "enable-asserts": true
-    }},
+      }
+    },
     "cfe-(linux|mac|win)": {
       "options": {
         "compiler": "fasta"
-    }},
+      }
+    },
     "cfe-weak-(linux|mac|win)": {
       "options": {
         "compiler": "fasta",
-        "enable-experiment": ["non-nullable"]
+        "enable-experiment": [
+          "non-nullable"
+        ]
       }
     },
     "analyzer-(linux|mac|win)": {
       "options": {
         "compiler": "dart2analyzer",
         "use-sdk": true
-    }},
+      }
+    },
     "analyzer-asserts-(linux|mac|win)": {
       "options": {
         "compiler": "dart2analyzer",
         "enable-asserts": true,
         "use-sdk": true
-    }},
+      }
+    },
     "analyzer-asserts-strong-(linux|mac|win)": {
       "options": {
         "compiler": "dart2analyzer",
         "enable-asserts": true,
         "use-sdk": true,
-        "enable-experiment": ["non-nullable"]
-    }},
+        "enable-experiment": [
+          "non-nullable"
+        ]
+      }
+    },
     "analyzer-asserts-weak-(linux|mac|win)": {
       "options": {
         "compiler": "dart2analyzer",
         "enable-asserts": true,
         "use-sdk": true,
-        "enable-experiment": ["non-nullable"]
-    }}
+        "enable-experiment": [
+          "non-nullable"
+        ]
+      }
+    }
   },
   "builder_configurations": [
     {
@@ -700,7 +831,9 @@
         },
         {
           "name": "sdk tests",
-          "arguments": ["-ncfe-${system}"],
+          "arguments": [
+            "-ncfe-${system}"
+          ],
           "fileset": "front-end",
           "shards": 5
         },
@@ -708,7 +841,7 @@
           "name": "unit tests",
           "arguments": [
             "-ncfe-unittest-asserts-${mode}-${system}",
-             "pkg/(kernel|front_end|fasta)"
+            "pkg/(kernel|front_end|fasta)"
           ]
         },
         {
@@ -746,8 +879,9 @@
           "name": "weak sdk tests",
           "arguments": [
             "-ncfe-weak-${system}",
-            "language",
             "corelib",
+            "ffi",
+            "language",
             "lib"
           ],
           "fileset": "front-end",
@@ -764,7 +898,9 @@
         },
         {
           "name": "legacy sdk tests",
-          "arguments": ["-ncfe-weak-${system}"],
+          "arguments": [
+            "-ncfe-weak-${system}"
+          ],
           "fileset": "front-end",
           "shards": 5
         },
@@ -851,19 +987,24 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["--arch=ia32,x64", "runtime"]
+          "arguments": [
+            "--arch=ia32,x64",
+            "runtime"
+          ]
         },
         {
           "name": "vm ia32 tests",
           "arguments": [
             "-ndartk-linux-debug-ia32",
-            "vm"]
+            "vm"
+          ]
         },
         {
           "name": "vm x64 tests",
           "arguments": [
             "-ndartk-linux-debug-x64",
-            "vm"]
+            "vm"
+          ]
         }
       ]
     },
@@ -922,7 +1063,7 @@
           "name": "ffi tests",
           "arguments": [
             "-ndartk-android-${mode}-${arch}",
-            "ffi"
+            "ffi_2"
           ],
           "fileset": "vm-kernel",
           "shards": 1
@@ -1072,7 +1213,9 @@
         },
         {
           "name": "vm tests",
-          "arguments": ["-ndartk-asan-linux-release-${arch}"],
+          "arguments": [
+            "-ndartk-asan-linux-release-${arch}"
+          ],
           "environment": {
             "ASAN_OPTIONS": "handle_segv=0:detect_leaks=1:detect_stack_use_after_return=0:disable_coredump=0:abort_on_error=1",
             "ASAN_SYMBOLIZER_PATH": "buildtools/linux-x64/clang/bin/llvm-symbolizer"
@@ -1112,7 +1255,9 @@
         },
         {
           "name": "vm tests",
-          "arguments": ["-ndartk-lsan-linux-release-${arch}"],
+          "arguments": [
+            "-ndartk-lsan-linux-release-${arch}"
+          ],
           "environment": {
             "ASAN_OPTIONS": "handle_segv=0:detect_leaks=1:detect_stack_use_after_return=0:disable_coredump=0:abort_on_error=1",
             "ASAN_SYMBOLIZER_PATH": "buildtools/linux-x64/clang/bin/llvm-symbolizer"
@@ -1153,7 +1298,8 @@
         {
           "name": "vm tests",
           "arguments": [
-            "-ndartk-msan-linux-release-${arch}"],
+            "-ndartk-msan-linux-release-${arch}"
+          ],
           "environment": {
             "MSAN_OPTIONS": "handle_segv=0:detect_leaks=1:detect_stack_use_after_return=0:disable_coredump=0:abort_on_error=1",
             "MSAN_SYMBOLIZER_PATH": "buildtools/linux-x64/clang/bin/llvm-symbolizer"
@@ -1192,7 +1338,9 @@
         },
         {
           "name": "vm tests",
-          "arguments": ["-ndartk-tsan-linux-release-${arch}"],
+          "arguments": [
+            "-ndartk-tsan-linux-release-${arch}"
+          ],
           "environment": {
             "TSAN_OPTIONS": "handle_segv=0:disable_coredump=0:abort_on_error=1",
             "TSAN_SYMBOLIZER_PATH": "buildtools/linux-x64/clang/bin/llvm-symbolizer"
@@ -1231,7 +1379,9 @@
         },
         {
           "name": "vm tests",
-          "arguments": ["-ndartk-ubsan-linux-release-${arch}"],
+          "arguments": [
+            "-ndartk-ubsan-linux-release-${arch}"
+          ],
           "environment": {
             "UBSAN_OPTIONS": "handle_segv=0:disable_coredump=0:abort_on_error=1"
           }
@@ -1256,12 +1406,15 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["runtime_kernel"]
+          "arguments": [
+            "runtime_kernel"
+          ]
         },
         {
           "name": "vm tests",
           "arguments": [
-            "-ndartk-${system}-${mode}-${arch}"],
+            "-ndartk-${system}-${mode}-${arch}"
+          ],
           "fileset": "vm-kernel",
           "shards": 10
         }
@@ -1281,15 +1434,18 @@
           "script": "tools/build.py",
           "arguments": [
             "--nnbd",
-            "create_sdk"
+            "create_sdk",
+            "runtime_kernel"
           ]
         },
         {
           "name": "vm weak tests with asserts",
           "arguments": [
             "-ndartk-weak-asserts-${system}-${mode}-${arch}",
+            "ffi",
             "language",
-            "lib/mirrors"
+            "lib/mirrors",
+            "standalone/io"
           ]
         }
       ]
@@ -1311,12 +1467,15 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["runtime_kernel"]
+          "arguments": [
+            "runtime_kernel"
+          ]
         },
         {
           "name": "vm tests",
           "arguments": [
-            "-ndartk-${system}-${mode}-${arch}"],
+            "-ndartk-${system}-${mode}-${arch}"
+          ],
           "fileset": "vm-kernel",
           "shards": 10
         },
@@ -1342,12 +1501,15 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["runtime_kernel"]
+          "arguments": [
+            "runtime_kernel"
+          ]
         },
         {
           "name": "vm tests",
           "arguments": [
-            "-ndartk-checked-linux-release-x64"],
+            "-ndartk-checked-linux-release-x64"
+          ],
           "fileset": "vm-kernel",
           "shards": 10
         }
@@ -1364,11 +1526,15 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["runtime_kernel"]
+          "arguments": [
+            "runtime_kernel"
+          ]
         },
         {
           "name": "vm tests",
-          "arguments": ["-ndartk-${system}-${mode}-${arch}"],
+          "arguments": [
+            "-ndartk-${system}-${mode}-${arch}"
+          ],
           "fileset": "vm-kernel",
           "shards": 1
         }
@@ -1394,7 +1560,8 @@
         {
           "name": "vm tests",
           "arguments": [
-            "-napp_jitk-linux-${mode}-x64"],
+            "-napp_jitk-linux-${mode}-x64"
+          ],
           "shards": 6,
           "fileset": "vm-kernel"
         }
@@ -1412,7 +1579,10 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["dart2js_bot", "dartdevc_test"]
+          "arguments": [
+            "dart2js_bot",
+            "dartdevc_test"
+          ]
         },
         {
           "name": "ddk co19_2 tests",
@@ -1493,7 +1663,10 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["dart2js_bot", "dartdevc_test"]
+          "arguments": [
+            "dart2js_bot",
+            "dartdevc_test"
+          ]
         },
         {
           "name": "ddk co19_2 tests",
@@ -1527,7 +1700,10 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["--nnbd", "dartdevc_test"]
+          "arguments": [
+            "--nnbd",
+            "dartdevc_test"
+          ]
         },
         {
           "name": "check dart nnbd sdk for static errors",
@@ -1561,6 +1737,15 @@
           "fileset": "dart2js_nnbd"
         },
         {
+          "name": "ddc legacy weak co19 tests",
+          "arguments": [
+            "-ndartdevk-weak-linux-release-chrome",
+            "co19_2"
+          ],
+          "shards": 6,
+          "fileset": "dart2js_nnbd"
+        },
+        {
           "name": "ddc nnbd strong tests",
           "arguments": [
             "-ndartdevk-strong-linux-release-chrome",
@@ -1590,7 +1775,10 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["dart2js_bot", "dartdevc_test"]
+          "arguments": [
+            "dart2js_bot",
+            "dartdevc_test"
+          ]
         },
         {
           "name": "ddc kernel tests",
@@ -1670,7 +1858,8 @@
         {
           "name": "vm tests",
           "arguments": [
-            "-ndartk-optcounter-linux-release-${arch}"],
+            "-ndartk-optcounter-linux-release-${arch}"
+          ],
           "fileset": "vm-kernel",
           "shards": 10
         }
@@ -1688,15 +1877,18 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["runtime_kernel"]
+          "arguments": [
+            "runtime_kernel"
+          ]
         },
         {
           "name": "vm tests",
           "arguments": [
-            "-ndartk-reload-${system}-${mode}-${arch}"],
-            "fileset": "vm-kernel",
-            "shards": 10
-          }
+            "-ndartk-reload-${system}-${mode}-${arch}"
+          ],
+          "fileset": "vm-kernel",
+          "shards": 10
+        }
       ]
     },
     {
@@ -1711,15 +1903,18 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["runtime_kernel"]
+          "arguments": [
+            "runtime_kernel"
+          ]
         },
         {
           "name": "vm tests",
           "arguments": [
-            "-ndartk-reload-rollback-linux-${mode}-x64"],
-            "fileset": "vm-kernel",
-            "shards": 10
-          }
+            "-ndartk-reload-rollback-linux-${mode}-x64"
+          ],
+          "fileset": "vm-kernel",
+          "shards": 10
+        }
       ]
     },
     {
@@ -1733,7 +1928,9 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["create_sdk"]
+          "arguments": [
+            "create_sdk"
+          ]
         },
         {
           "name": "dart2js modular tests",
@@ -1767,7 +1964,9 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["dart2js_bot"]
+          "arguments": [
+            "dart2js_bot"
+          ]
         },
         {
           "name": "dart2js tests",
@@ -1827,7 +2026,9 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["dart2js_bot"]
+          "arguments": [
+            "dart2js_bot"
+          ]
         },
         {
           "name": "dart2js old-rti tests",
@@ -1875,7 +2076,9 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["create_sdk"]
+          "arguments": [
+            "create_sdk"
+          ]
         },
         {
           "name": "dart2js tests",
@@ -1930,7 +2133,9 @@
       ]
     },
     {
-      "builders": ["dart2js-minified-strong-linux-x64-d8"],
+      "builders": [
+        "dart2js-minified-strong-linux-x64-d8"
+      ],
       "meta": {
         "description": "dart2js tests for Dart 2.0."
       },
@@ -1938,7 +2143,9 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["create_sdk"]
+          "arguments": [
+            "create_sdk"
+          ]
         },
         {
           "name": "dart2js tests",
@@ -1997,7 +2204,9 @@
       ]
     },
     {
-      "builders": ["dart2js-csp-minified-linux-x64-chrome"],
+      "builders": [
+        "dart2js-csp-minified-linux-x64-chrome"
+      ],
       "meta": {
         "description": "dart2js tests in csp and minified mode."
       },
@@ -2005,7 +2214,9 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["create_sdk"]
+          "arguments": [
+            "create_sdk"
+          ]
         },
         {
           "name": "dart2js tests",
@@ -2048,7 +2259,9 @@
       ]
     },
     {
-      "builders": ["dart2js-nnbd-linux-x64-chrome"],
+      "builders": [
+        "dart2js-nnbd-linux-x64-chrome"
+      ],
       "meta": {
         "description": "dart2js tests for NNBD."
       },
@@ -2069,7 +2282,7 @@
             "--enable-experiment=non-nullable",
             "pkg/dev_compiler/tool/check_nnbd_sdk.dart",
             "--target",
-            "dart2js_server"
+            "dart2js"
           ]
         },
         {
@@ -2098,20 +2311,31 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["--arch=ia32,x64,arm,arm64",
-                        "--mode=release", "create_sdk"]
+          "arguments": [
+            "--arch=ia32,x64,arm,arm64",
+            "--mode=release",
+            "create_sdk"
+          ]
         },
         {
           "name": "build gen_kernel.dart.snapshot",
           "script": "tools/build.py",
-          "arguments": ["--arch=x64,arm,arm64", "--mode=release",
-                        "copy_gen_kernel_snapshot"]
+          "arguments": [
+            "--arch=x64,arm,arm64",
+            "--mode=release",
+            "copy_gen_kernel_snapshot"
+          ]
         },
         {
           "name": "build gen_snapshot and dartaotruntime",
           "script": "tools/build.py",
-          "arguments": ["--arch=x64,arm,arm64", "--mode=product",
-                        "copy_gen_snapshot", "copy_dartaotruntime", "copy_vm_dill_files"]
+          "arguments": [
+            "--arch=x64,arm,arm64",
+            "--mode=product",
+            "copy_gen_snapshot",
+            "copy_dartaotruntime",
+            "copy_vm_dill_files"
+          ]
         },
         {
           "name": "upload sdk",
@@ -2127,7 +2351,9 @@
         {
           "name": "build api docs",
           "script": "tools/bots/dart_sdk.py",
-          "arguments": [ "api_docs" ]
+          "arguments": [
+            "api_docs"
+          ]
         },
         {
           "name": "upload abi dills",
@@ -2140,7 +2366,9 @@
       ]
     },
     {
-      "builders": ["dart-sdk-mac"],
+      "builders": [
+        "dart-sdk-mac"
+      ],
       "meta": {
         "description": "This configuration is used by the sdk-builders for MacOS."
       },
@@ -2148,20 +2376,31 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["--arch=x64",
-                        "--mode=release", "create_sdk"]
+          "arguments": [
+            "--arch=x64",
+            "--mode=release",
+            "create_sdk"
+          ]
         },
         {
           "name": "build gen_kernel.dart.snapshot",
           "script": "tools/build.py",
-          "arguments": ["--arch=x64", "--mode=release",
-                        "copy_gen_kernel_snapshot"]
+          "arguments": [
+            "--arch=x64",
+            "--mode=release",
+            "copy_gen_kernel_snapshot"
+          ]
         },
         {
           "name": "build gen_snapshot and dartaotruntime",
           "script": "tools/build.py",
-          "arguments": ["--arch=x64", "--mode=product",
-                        "copy_gen_snapshot", "copy_dartaotruntime", "copy_vm_dill_files"]
+          "arguments": [
+            "--arch=x64",
+            "--mode=product",
+            "copy_gen_snapshot",
+            "copy_dartaotruntime",
+            "copy_vm_dill_files"
+          ]
         },
         {
           "name": "upload sdk",
@@ -2177,7 +2416,9 @@
       ]
     },
     {
-      "builders": ["dart-sdk-win"],
+      "builders": [
+        "dart-sdk-win"
+      ],
       "meta": {
         "description": "This configuration is used by the sdk-builders for Windows. It also adds CQ coverage for building on Windows."
       },
@@ -2185,20 +2426,32 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["--arch=ia32,x64",
-                        "--mode=release", "create_sdk", "runtime_kernel"]
+          "arguments": [
+            "--arch=ia32,x64",
+            "--mode=release",
+            "create_sdk",
+            "runtime_kernel"
+          ]
         },
         {
           "name": "build gen_kernel.dart.snapshot",
           "script": "tools/build.py",
-          "arguments": ["--arch=x64", "--mode=release",
-                        "copy_gen_kernel_snapshot"]
+          "arguments": [
+            "--arch=x64",
+            "--mode=release",
+            "copy_gen_kernel_snapshot"
+          ]
         },
         {
           "name": "build gen_snapshot and dartaotruntime",
           "script": "tools/build.py",
-          "arguments": ["--arch=x64", "--mode=product",
-                        "copy_gen_snapshot", "copy_dartaotruntime", "copy_vm_dill_files"]
+          "arguments": [
+            "--arch=x64",
+            "--mode=product",
+            "copy_gen_snapshot",
+            "copy_dartaotruntime",
+            "copy_vm_dill_files"
+          ]
         },
         {
           "name": "upload sdk",
@@ -2214,7 +2467,9 @@
       ]
     },
     {
-      "builders": ["debianpackage-linux"],
+      "builders": [
+        "debianpackage-linux"
+      ],
       "meta": {
         "description": "This configuration is used by the debianpackage-builder."
       },
@@ -2232,7 +2487,9 @@
       ]
     },
     {
-      "builders": ["versionchecker-linux"],
+      "builders": [
+        "versionchecker-linux"
+      ],
       "meta": {
         "description": "This configuration is used by the versionchecker-builder."
       },
@@ -2260,7 +2517,9 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["create_sdk"]
+          "arguments": [
+            "create_sdk"
+          ]
         },
         {
           "name": "analyzer unit tests",
@@ -2283,7 +2542,8 @@
         {
           "name": "analyze tests enable-asserts",
           "arguments": [
-            "-nanalyzer-asserts-${system}"]
+            "-nanalyzer-asserts-${system}"
+          ]
         },
         {
           "name": "analyze pkg tests enable-asserts",
@@ -2316,7 +2576,9 @@
         {
           "name": "check nnbd sdk (ddc patch) for static errors",
           "script": "out/ReleaseX64/dart-sdk/bin/dart",
-          "arguments": ["pkg/dev_compiler/tool/check_nnbd_sdk.dart"]
+          "arguments": [
+            "pkg/dev_compiler/tool/check_nnbd_sdk.dart"
+          ]
         }
       ]
     },
@@ -2331,22 +2593,29 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["--nnbd", "create_sdk"]
+          "arguments": [
+            "--nnbd",
+            "create_sdk"
+          ]
         },
         {
           "name": "analyze nnbd strong tests enable-asserts",
           "arguments": [
             "-nanalyzer-asserts-strong-${system}",
+            "ffi",
             "language",
-            "lib/mirrors"
+            "lib/mirrors",
+            "standalone/io"
           ]
         },
         {
           "name": "analyze nnbd weak tests enable-asserts",
           "arguments": [
             "-nanalyzer-asserts-weak-${system}",
+            "ffi",
             "language",
-            "lib/mirrors"
+            "lib/mirrors",
+            "standalone/io"
           ]
         },
         {
@@ -2370,149 +2639,235 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["create_sdk"]
+          "arguments": [
+            "create_sdk"
+          ]
         },
         {
           "name": "analyze runtime/tools/dartfuzz",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "runtime/tools/dartfuzz"]
+          "arguments": [
+            "--fatal-warnings",
+            "runtime/tools/dartfuzz"
+          ]
         },
         {
           "name": "analyze pkg/analysis_server",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/analysis_server"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/analysis_server"
+          ]
         },
         {
           "name": "analyze pkg/analysis_server_client",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/analysis_server_client"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/analysis_server_client"
+          ]
         },
         {
           "name": "analyze pkg/analyzer",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/analyzer"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/analyzer"
+          ]
         },
         {
           "name": "analyze pkg/analyzer_cli",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/analyzer_cli"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/analyzer_cli"
+          ]
         },
         {
           "name": "analyze pkg/analyzer_plugin",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/analyzer_plugin"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/analyzer_plugin"
+          ]
         },
         {
           "name": "analyze pkg/async_helper",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/async_helper"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/async_helper"
+          ]
         },
         {
           "name": "analyze pkg/build_integration",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/build_integration"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/build_integration"
+          ]
         },
         {
           "name": "analyze pkg/compiler",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/compiler"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/compiler"
+          ]
         },
         {
           "name": "analyze pkg/dartdev",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/dartdev"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/dartdev"
+          ]
         },
         {
           "name": "analyze pkg/dart2js_tools",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/dart2js_tools"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/dart2js_tools"
+          ]
         },
         {
           "name": "analyze pkg/dart_internal",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/dart_internal"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/dart_internal"
+          ]
         },
         {
           "name": "analyze pkg/dev_compiler",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "--fatal-lints", "pkg/dev_compiler"]
+          "arguments": [
+            "--fatal-warnings",
+            "--fatal-lints",
+            "pkg/dev_compiler"
+          ]
         },
         {
           "name": "analyze pkg/expect",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/expect"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/expect"
+          ]
         },
         {
           "name": "analyze pkg/front_end",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/front_end"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/front_end"
+          ]
         },
         {
           "name": "analyze pkg/js",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/js"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/js"
+          ]
         },
         {
           "name": "analyze pkg/js_ast",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/js_ast"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/js_ast"
+          ]
         },
         {
           "name": "analyze pkg/kernel",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/kernel"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/kernel"
+          ]
         },
         {
           "name": "analyze pkg/meta",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/meta"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/meta"
+          ]
         },
         {
           "name": "analyze pkg/native_stack_traces",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/native_stack_traces"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/native_stack_traces"
+          ]
         },
         {
           "name": "analyze pkg/smith",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/smith"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/smith"
+          ]
         },
         {
           "name": "analyze pkg/sourcemap_testing",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/sourcemap_testing"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/sourcemap_testing"
+          ]
         },
         {
           "name": "analyze pkg/status_file",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/status_file"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/status_file"
+          ]
         },
         {
           "name": "analyze pkg/telemetry",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/telemetry"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/telemetry"
+          ]
         },
         {
           "name": "analyze pkg/test_runner",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/test_runner"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/test_runner"
+          ]
         },
         {
           "name": "analyze pkg/testing",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/testing"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/testing"
+          ]
         },
         {
           "name": "analyze pkg/vm",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/vm"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/vm"
+          ]
         },
         {
           "name": "analyze pkg/vm_service",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "pkg/vm_service"]
+          "arguments": [
+            "--fatal-warnings",
+            "pkg/vm_service"
+          ]
         },
-
         {
           "name": "analyze runtime/observatory",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
@@ -2525,12 +2880,16 @@
         {
           "name": "analyze tools/gardening",
           "script": "out/ReleaseX64/dart-sdk/bin/dartanalyzer",
-          "arguments": ["--fatal-warnings", "tools/gardening"]
+          "arguments": [
+            "--fatal-warnings",
+            "tools/gardening"
+          ]
         },
         {
           "name": "dartanalyzer --batch tests",
           "arguments": [
-            "-nanalyzer-${system}"]
+            "-nanalyzer-${system}"
+          ]
         },
         {
           "name": "dartanalyzer --batch pkg tests",
@@ -2542,9 +2901,11 @@
       ]
     },
     {
-      "builders": ["pkg-linux-release",
-                   "pkg-win-release",
-                   "pkg-mac-release"],
+      "builders": [
+        "pkg-linux-release",
+        "pkg-win-release",
+        "pkg-mac-release"
+      ],
       "meta": {
         "description": "This configuration is used by the release pkg builders."
       },
@@ -2552,7 +2913,9 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["create_sdk"]
+          "arguments": [
+            "create_sdk"
+          ]
         },
         {
           "name": "package unit tests",
@@ -2578,7 +2941,9 @@
       ]
     },
     {
-      "builders": ["pkg-linux-debug"],
+      "builders": [
+        "pkg-linux-debug"
+      ],
       "meta": {
         "description": "This configuration is used by the debug pkg builders."
       },
@@ -2586,7 +2951,9 @@
         {
           "name": "build dart",
           "script": "tools/build.py",
-          "arguments": ["create_sdk"]
+          "arguments": [
+            "create_sdk"
+          ]
         },
         {
           "name": "package unit tests",
@@ -2612,7 +2979,9 @@
       ]
     },
     {
-      "builders": ["benchmark-linux"],
+      "builders": [
+        "benchmark-linux"
+      ],
       "meta": {
         "description": "Verify benchmarks build and run correctly.",
         "owner": "sortie@google.com"
@@ -2621,12 +2990,16 @@
         {
           "name": "see this step for details on what this bot does",
           "script": "tools/bots/try_benchmarks.sh",
-          "arguments": ["noop"]
+          "arguments": [
+            "noop"
+          ]
         },
         {
           "name": "remove out directory to do a clean linux-ia32 build",
           "script": "tools/bots/try_benchmarks.sh",
-          "arguments": ["clean"]
+          "arguments": [
+            "clean"
+          ]
         },
         {
           "name": "build linux-ia32 for benchmarking",
@@ -2635,22 +3008,29 @@
             "--mode=release",
             "--arch=ia32",
             "create_sdk",
-            "runtime"]
+            "runtime"
+          ]
         },
         {
           "name": "archive linux-ia32 for benchmarking",
           "script": "tools/bots/try_benchmarks.sh",
-          "arguments": ["linux-ia32-archive"]
+          "arguments": [
+            "linux-ia32-archive"
+          ]
         },
         {
           "name": "try linux-ia32 benchmarking",
           "script": "tools/bots/try_benchmarks.sh",
-          "arguments": ["linux-ia32-benchmark"]
+          "arguments": [
+            "linux-ia32-benchmark"
+          ]
         },
         {
           "name": "remove out directory to do a clean linux-x64 build",
           "script": "tools/bots/try_benchmarks.sh",
-          "arguments": ["clean"]
+          "arguments": [
+            "clean"
+          ]
         },
         {
           "name": "build linux-x64 for benchmarking",
@@ -2661,22 +3041,29 @@
             "create_sdk",
             "runtime",
             "gen_snapshot",
-            "dart_precompiled_runtime"]
+            "dart_precompiled_runtime"
+          ]
         },
         {
           "name": "archive linux-x64 for benchmarking",
           "script": "tools/bots/try_benchmarks.sh",
-          "arguments": ["linux-x64-archive"]
+          "arguments": [
+            "linux-x64-archive"
+          ]
         },
         {
           "name": "try linux-x64 benchmarking",
           "script": "tools/bots/try_benchmarks.sh",
-          "arguments": ["linux-x64-benchmark"]
+          "arguments": [
+            "linux-x64-benchmark"
+          ]
         },
         {
           "name": "remove out directory to do a clean linux-x64-bytecode build",
           "script": "tools/bots/try_benchmarks.sh",
-          "arguments": ["clean"]
+          "arguments": [
+            "clean"
+          ]
         },
         {
           "name": "generate ninja for linux-x64-bytecode",
@@ -2684,7 +3071,8 @@
           "arguments": [
             "--mode=release",
             "--arch=x64",
-            "--bytecode"]
+            "--bytecode"
+          ]
         },
         {
           "name": "build linux-x64-bytecode for benchmarking",
@@ -2695,17 +3083,22 @@
             "create_sdk",
             "runtime",
             "gen_snapshot",
-            "dart_precompiled_runtime"]
+            "dart_precompiled_runtime"
+          ]
         },
         {
           "name": "archive linux-x64-bytecode for benchmarking",
           "script": "tools/bots/try_benchmarks.sh",
-          "arguments": ["linux-x64-bytecode-archive"]
+          "arguments": [
+            "linux-x64-bytecode-archive"
+          ]
         },
         {
           "name": "try linux-x64-bytecode benchmarking",
           "script": "tools/bots/try_benchmarks.sh",
-          "arguments": ["linux-x64-bytecode-benchmark"]
+          "arguments": [
+            "linux-x64-bytecode-benchmark"
+          ]
         }
       ]
     },
@@ -2751,14 +3144,15 @@
           ]
         },
         {
-
           "name": "compile flutter tests",
           "script": "tools/bots/flutter/compile_flutter.sh"
         }
       ]
     },
     {
-      "builders": ["fuzz-linux"],
+      "builders": [
+        "fuzz-linux"
+      ],
       "meta": {
         "description": "This configuration is used for fuzz testing."
       },
@@ -2880,8 +3274,7 @@
         {
           "name": "vm tests",
           "arguments": [
-            "-ndartkp-${system}-${mode}-simarm-crossword",
-            "--gen-snapshot=${build_root}/gen_snapshot"
+            "-ndartkp-${system}-${mode}-simarm-crossword"
           ],
           "fileset": "vm-kernel",
           "shards": 10
diff --git a/tools/dom/nnbd_src/AttributeMap.dart b/tools/dom/nnbd_src/AttributeMap.dart
new file mode 100644
index 0000000..e8c79aa
--- /dev/null
+++ b/tools/dom/nnbd_src/AttributeMap.dart
@@ -0,0 +1,298 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+abstract class _AttributeMap extends MapBase<String, String> {
+  final Element _element;
+
+  _AttributeMap(this._element);
+
+  void addAll(Map<String, String> other) {
+    other.forEach((k, v) {
+      this[k] = v;
+    });
+  }
+
+  Map<K, V> cast<K, V>() => Map.castFrom<String, String, K, V>(this);
+  bool containsValue(Object? value) {
+    for (var v in this.values) {
+      if (value == v) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  String putIfAbsent(String key, String ifAbsent()) {
+    if (!containsKey(key)) {
+      this[key] = ifAbsent();
+    }
+    return this[key];
+  }
+
+  void clear() {
+    for (var key in keys) {
+      remove(key);
+    }
+  }
+
+  void forEach(void f(String key, String value)) {
+    for (var key in keys) {
+      var value = this[key];
+      f(key, value);
+    }
+  }
+
+  Iterable<String> get keys {
+    // TODO: generate a lazy collection instead.
+    var attributes = _element._attributes;
+    var keys = <String>[];
+    for (int i = 0, len = attributes.length; i < len; i++) {
+      _Attr attr = attributes[i];
+      if (_matches(attr)) {
+        keys.add(attr.name);
+      }
+    }
+    return keys;
+  }
+
+  Iterable<String> get values {
+    // TODO: generate a lazy collection instead.
+    var attributes = _element._attributes;
+    var values = <String>[];
+    for (int i = 0, len = attributes.length; i < len; i++) {
+      _Attr attr = attributes[i];
+      if (_matches(attr)) {
+        values.add(attr.value);
+      }
+    }
+    return values;
+  }
+
+  /**
+   * Returns true if there is no {key, value} pair in the map.
+   */
+  bool get isEmpty {
+    return length == 0;
+  }
+
+  /**
+   * Returns true if there is at least one {key, value} pair in the map.
+   */
+  bool get isNotEmpty => !isEmpty;
+
+  /**
+   * Checks to see if the node should be included in this map.
+   */
+  bool _matches(_Attr node);
+}
+
+/**
+ * Wrapper to expose [Element.attributes] as a typed map.
+ */
+class _ElementAttributeMap extends _AttributeMap {
+  _ElementAttributeMap(Element element) : super(element);
+
+  bool containsKey(Object? key) {
+    return _element._hasAttribute(key);
+  }
+
+  String? operator [](Object? key) {
+    return _element.getAttribute(key);
+  }
+
+  void operator []=(String key, String value) {
+    _element.setAttribute(key, value);
+  }
+
+  @pragma('dart2js:tryInline')
+  String? remove(Object? key) => key is String ? _remove(_element, key) : null;
+
+  /**
+   * The number of {key, value} pairs in the map.
+   */
+  int get length {
+    return keys.length;
+  }
+
+  bool _matches(_Attr node) => node._namespaceUri == null;
+
+  // Inline this because almost all call sites of [remove] do not use [value],
+  // and the annotations on the `getAttribute` call allow it to be removed.
+  @pragma('dart2js:tryInline')
+  static String _remove(Element element, String key) {
+    String value = JS(
+        // throws:null(1) is not accurate since [key] could be malformed, but
+        // [key] is checked again by `removeAttributeNS`.
+        'returns:String|Null;depends:all;effects:none;throws:null(1)',
+        '#.getAttribute(#)',
+        element,
+        key);
+    JS('', '#.removeAttribute(#)', element, key);
+    return value;
+  }
+}
+
+/**
+ * Wrapper to expose namespaced attributes as a typed map.
+ */
+class _NamespacedAttributeMap extends _AttributeMap {
+  final String _namespace;
+
+  _NamespacedAttributeMap(Element element, this._namespace) : super(element);
+
+  bool containsKey(Object? key) {
+    return _element._hasAttributeNS(_namespace, key);
+  }
+
+  String? operator [](Object? key) {
+    return _element.getAttributeNS(_namespace, key);
+  }
+
+  void operator []=(String key, String value) {
+    _element.setAttributeNS(_namespace, key, value);
+  }
+
+  @pragma('dart2js:tryInline')
+  String? remove(Object? key) =>
+      key is String ? _remove(_namespace, _element, key) : null;
+
+  /**
+   * The number of {key, value} pairs in the map.
+   */
+  int get length {
+    return keys.length;
+  }
+
+  bool _matches(_Attr node) => node._namespaceUri == _namespace;
+
+  // Inline this because almost all call sites of [remove] do not use the
+  // returned [value], and the annotations on the `getAttributeNS` call allow it
+  // to be removed.
+  @pragma('dart2js:tryInline')
+  static String _remove(String namespace, Element element, String key) {
+    String value = JS(
+        // throws:null(1) is not accurate since [key] could be malformed, but
+        // [key] is checked again by `removeAttributeNS`.
+        'returns:String|Null;depends:all;effects:none;throws:null(1)',
+        '#.getAttributeNS(#, #)',
+        element,
+        namespace,
+        key);
+    JS('', '#.removeAttributeNS(#, #)', element, namespace, key);
+    return value;
+  }
+}
+
+/**
+ * Provides a Map abstraction on top of data-* attributes, similar to the
+ * dataSet in the old DOM.
+ */
+class _DataAttributeMap extends MapBase<String, String> {
+  final Map<String, String> _attributes;
+
+  _DataAttributeMap(this._attributes);
+
+  // interface Map
+
+  void addAll(Map<String, String> other) {
+    other.forEach((k, v) {
+      this[k] = v;
+    });
+  }
+
+  Map<K, V> cast<K, V>() => Map.castFrom<String, String, K, V>(this);
+  // TODO: Use lazy iterator when it is available on Map.
+  bool containsValue(Object? value) => values.any((v) => v == value);
+
+  bool containsKey(Object? key) => _attributes.containsKey(_attr(key));
+
+  String? operator [](Object? key) => _attributes[_attr(key)];
+
+  void operator []=(String key, String value) {
+    _attributes[_attr(key)] = value;
+  }
+
+  String putIfAbsent(String key, String ifAbsent()) =>
+      _attributes.putIfAbsent(_attr(key), ifAbsent);
+
+  String? remove(Object? key) => _attributes.remove(_attr(key));
+
+  void clear() {
+    // Needs to operate on a snapshot since we are mutating the collection.
+    for (String key in keys) {
+      remove(key);
+    }
+  }
+
+  void forEach(void f(String key, String value)) {
+    _attributes.forEach((String key, String value) {
+      if (_matches(key)) {
+        f(_strip(key), value);
+      }
+    });
+  }
+
+  Iterable<String> get keys {
+    final keys = <String>[];
+    _attributes.forEach((String key, String value) {
+      if (_matches(key)) {
+        keys.add(_strip(key));
+      }
+    });
+    return keys;
+  }
+
+  Iterable<String> get values {
+    final values = <String>[];
+    _attributes.forEach((String key, String value) {
+      if (_matches(key)) {
+        values.add(value);
+      }
+    });
+    return values;
+  }
+
+  int get length => keys.length;
+
+  // TODO: Use lazy iterator when it is available on Map.
+  bool get isEmpty => length == 0;
+
+  bool get isNotEmpty => !isEmpty;
+
+  // Helpers.
+  String _attr(String key) => 'data-${_toHyphenedName(key)}';
+  bool _matches(String key) => key.startsWith('data-');
+  String _strip(String key) => _toCamelCase(key.substring(5));
+
+  /**
+   * Converts a string name with hyphens into an identifier, by removing hyphens
+   * and capitalizing the following letter. Optionally [startUppercase] to
+   * capitalize the first letter.
+   */
+  String _toCamelCase(String hyphenedName, {bool startUppercase: false}) {
+    var segments = hyphenedName.split('-');
+    int start = startUppercase ? 0 : 1;
+    for (int i = start; i < segments.length; i++) {
+      var segment = segments[i];
+      if (segment.length > 0) {
+        // Character between 'a'..'z' mapped to 'A'..'Z'
+        segments[i] = '${segment[0].toUpperCase()}${segment.substring(1)}';
+      }
+    }
+    return segments.join('');
+  }
+
+  /** Reverse of [toCamelCase]. */
+  String _toHyphenedName(String word) {
+    var sb = new StringBuffer();
+    for (int i = 0; i < word.length; i++) {
+      var lower = word[i].toLowerCase();
+      if (word[i] != lower && i > 0) sb.write('-');
+      sb.write(lower);
+    }
+    return sb.toString();
+  }
+}
diff --git a/tools/dom/nnbd_src/CanvasImageSource.dart b/tools/dom/nnbd_src/CanvasImageSource.dart
new file mode 100644
index 0000000..ffcd34a
--- /dev/null
+++ b/tools/dom/nnbd_src/CanvasImageSource.dart
@@ -0,0 +1,42 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * An object that can be drawn to a 2D canvas rendering context.
+ *
+ * The image drawn to the canvas depends on the type of this object:
+ *
+ * * If this object is an [ImageElement], then this element's image is
+ * drawn to the canvas. If this element is an animated image, then this
+ * element's poster frame is drawn. If this element has no poster frame, then
+ * the first frame of animation is drawn.
+ *
+ * * If this object is a [VideoElement], then the frame at this element's current
+ * playback position is drawn to the canvas.
+ *
+ * * If this object is a [CanvasElement], then this element's bitmap is drawn to
+ * the canvas.
+ *
+ * **Note:** Currently all versions of Internet Explorer do not support
+ * drawing a video element to a canvas. You may also encounter problems drawing
+ * a video to a canvas in Firefox if the source of the video is a data URL.
+ *
+ * ## See also
+ *
+ * * [CanvasRenderingContext2D.drawImage]
+ * * [CanvasRenderingContext2D.drawImageToRect]
+ * * [CanvasRenderingContext2D.drawImageScaled]
+ * * [CanvasRenderingContext2D.drawImageScaledFromSource]
+ *
+ * ## Other resources
+ *
+ * * [Image sources for 2D rendering
+ *   contexts](https://html.spec.whatwg.org/multipage/scripting.html#image-sources-for-2d-rendering-contexts)
+ *   from WHATWG.
+ * * [Drawing images](https://html.spec.whatwg.org/multipage/scripting.html#dom-context-2d-drawimage)
+ *   from WHATWG.
+ */
+abstract class CanvasImageSource {}
diff --git a/tools/dom/nnbd_src/CrossFrameTypes.dart b/tools/dom/nnbd_src/CrossFrameTypes.dart
new file mode 100644
index 0000000..a2aa545
--- /dev/null
+++ b/tools/dom/nnbd_src/CrossFrameTypes.dart
@@ -0,0 +1,156 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * Top-level container for a browser tab or window.
+ *
+ * In a web browser, a [WindowBase] object represents any browser window. This
+ * object contains the window's state and its relation to other
+ * windows, such as which window opened this window.
+ *
+ * **Note:** This class represents any window, while [Window] is
+ * used to access the properties and content of the current window or tab.
+ *
+ * ## See also
+ *
+ * * [Window]
+ *
+ * ## Other resources
+ *
+ * * [DOM Window](https://developer.mozilla.org/en-US/docs/DOM/window) from MDN.
+ * * [Window](http://www.w3.org/TR/Window/) from the W3C.
+ */
+abstract class WindowBase implements EventTarget {
+  // Fields.
+
+  /**
+   * The current location of this window.
+   *
+   *     Location currentLocation = window.location;
+   *     print(currentLocation.href); // 'http://www.example.com:80/'
+   */
+  LocationBase get location;
+
+  /**
+   * The current session history for this window.
+   *
+   * ## Other resources
+   *
+   * * [Session history and navigation
+   *   specification](https://html.spec.whatwg.org/multipage/browsers.html#history)
+   *   from WHATWG.
+   */
+  HistoryBase get history;
+
+  /**
+   * Indicates whether this window has been closed.
+   *
+   *     print(window.closed); // 'false'
+   *     window.close();
+   *     print(window.closed); // 'true'
+   */
+  bool get closed;
+
+  /**
+   * A reference to the window that opened this one.
+   *
+   *     Window thisWindow = window;
+   *     WindowBase otherWindow = thisWindow.open('http://www.example.com/', 'foo');
+   *     print(otherWindow.opener == thisWindow); // 'true'
+   */
+  WindowBase get opener;
+
+  /**
+   * A reference to the parent of this window.
+   *
+   * If this [WindowBase] has no parent, [parent] will return a reference to
+   * the [WindowBase] itself.
+   *
+   *     IFrameElement myIFrame = new IFrameElement();
+   *     window.document.body.elements.add(myIFrame);
+   *     print(myIframe.contentWindow.parent == window) // 'true'
+   *
+   *     print(window.parent == window) // 'true'
+   */
+  WindowBase get parent;
+
+  /**
+   * A reference to the topmost window in the window hierarchy.
+   *
+   * If this [WindowBase] is the topmost [WindowBase], [top] will return a
+   * reference to the [WindowBase] itself.
+   *
+   *     // Add an IFrame to the current window.
+   *     IFrameElement myIFrame = new IFrameElement();
+   *     window.document.body.elements.add(myIFrame);
+   *
+   *     // Add an IFrame inside of the other IFrame.
+   *     IFrameElement innerIFrame = new IFrameElement();
+   *     myIFrame.elements.add(innerIFrame);
+   *
+   *     print(myIframe.contentWindow.top == window) // 'true'
+   *     print(innerIFrame.contentWindow.top == window) // 'true'
+   *
+   *     print(window.top == window) // 'true'
+   */
+  WindowBase get top;
+
+  // Methods.
+  /**
+   * Closes the window.
+   *
+   * This method should only succeed if the [WindowBase] object is
+   * **script-closeable** and the window calling [close] is allowed to navigate
+   * the window.
+   *
+   * A window is script-closeable if it is either a window
+   * that was opened by another window, or if it is a window with only one
+   * document in its history.
+   *
+   * A window might not be allowed to navigate, and therefore close, another
+   * window due to browser security features.
+   *
+   *     var other = window.open('http://www.example.com', 'foo');
+   *     // Closes other window, as it is script-closeable.
+   *     other.close();
+   *     print(other.closed); // 'true'
+   *
+   *     var newLocation = window.location
+   *         ..href = 'http://www.mysite.com';
+   *     window.location = newLocation;
+   *     // Does not close this window, as the history has changed.
+   *     window.close();
+   *     print(window.closed); // 'false'
+   *
+   * See also:
+   *
+   * * [Window close discussion](http://www.w3.org/TR/html5/browsers.html#dom-window-close) from the W3C
+   */
+  void close();
+
+  /**
+   * Sends a cross-origin message.
+   *
+   * ## Other resources
+   *
+   * * [window.postMessage](https://developer.mozilla.org/en-US/docs/Web/API/Window.postMessage)
+   *   from MDN.
+   * * [Cross-document messaging](https://html.spec.whatwg.org/multipage/comms.html#web-messaging)
+   *   from WHATWG.
+   */
+  void postMessage(var message, String targetOrigin,
+      [List<MessagePort> messagePorts]);
+}
+
+abstract class LocationBase {
+  void set href(String val);
+}
+
+abstract class HistoryBase {
+  void back();
+  void forward();
+  void go(int distance);
+}
diff --git a/tools/dom/nnbd_src/CssClassSet.dart b/tools/dom/nnbd_src/CssClassSet.dart
new file mode 100644
index 0000000..d2a28e1
--- /dev/null
+++ b/tools/dom/nnbd_src/CssClassSet.dart
@@ -0,0 +1,111 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/** A Set that stores the CSS class names for an element. */
+abstract class CssClassSet implements Set<String> {
+  /**
+   * Adds the class [value] to the element if it is not on it, removes it if it
+   * is.
+   *
+   * If [shouldAdd] is true, then we always add that [value] to the element. If
+   * [shouldAdd] is false then we always remove [value] from the element.
+   *
+   * If this corresponds to one element, returns `true` if [value] is present
+   * after the operation, and returns `false` if [value] is absent after the
+   * operation.
+   *
+   * If this corresponds to many elements, `null` is always returned.
+   *
+   * [value] must be a valid 'token' representing a single class, i.e. a
+   * non-empty string containing no whitespace.  To toggle multiple classes, use
+   * [toggleAll].
+   */
+  bool toggle(String value, [bool shouldAdd]);
+
+  /**
+   * Returns [:true:] if classes cannot be added or removed from this
+   * [:CssClassSet:].
+   */
+  bool get frozen;
+
+  /**
+   * Determine if this element contains the class [value].
+   *
+   * This is the Dart equivalent of jQuery's
+   * [hasClass](http://api.jquery.com/hasClass/).
+   *
+   * [value] must be a valid 'token' representing a single class, i.e. a
+   * non-empty string containing no whitespace.
+   */
+  bool contains(Object? value);
+
+  /**
+   * Add the class [value] to element.
+   *
+   * [add] and [addAll] are the Dart equivalent of jQuery's
+   * [addClass](http://api.jquery.com/addClass/).
+   *
+   * If this CssClassSet corresponds to one element. Returns true if [value] was
+   * added to the set, otherwise false.
+   *
+   * If this corresponds to many elements, `null` is always returned.
+   *
+   * [value] must be a valid 'token' representing a single class, i.e. a
+   * non-empty string containing no whitespace.  To add multiple classes use
+   * [addAll].
+   */
+  bool add(String value);
+
+  /**
+   * Remove the class [value] from element, and return true on successful
+   * removal.
+   *
+   * [remove] and [removeAll] are the Dart equivalent of jQuery's
+   * [removeClass](http://api.jquery.com/removeClass/).
+   *
+   * [value] must be a valid 'token' representing a single class, i.e. a
+   * non-empty string containing no whitespace.  To remove multiple classes, use
+   * [removeAll].
+   */
+  bool remove(Object? value);
+
+  /**
+   * Add all classes specified in [iterable] to element.
+   *
+   * [add] and [addAll] are the Dart equivalent of jQuery's
+   * [addClass](http://api.jquery.com/addClass/).
+   *
+   * Each element of [iterable] must be a valid 'token' representing a single
+   * class, i.e. a non-empty string containing no whitespace.
+   */
+  void addAll(Iterable<String> iterable);
+
+  /**
+   * Remove all classes specified in [iterable] from element.
+   *
+   * [remove] and [removeAll] are the Dart equivalent of jQuery's
+   * [removeClass](http://api.jquery.com/removeClass/).
+   *
+   * Each element of [iterable] must be a valid 'token' representing a single
+   * class, i.e. a non-empty string containing no whitespace.
+   */
+  void removeAll(Iterable<Object?> iterable);
+
+  /**
+   * Toggles all classes specified in [iterable] on element.
+   *
+   * Iterate through [iterable]'s items, and add it if it is not on it, or
+   * remove it if it is. This is the Dart equivalent of jQuery's
+   * [toggleClass](http://api.jquery.com/toggleClass/).
+   * If [shouldAdd] is true, then we always add all the classes in [iterable]
+   * element. If [shouldAdd] is false then we always remove all the classes in
+   * [iterable] from the element.
+   *
+   * Each element of [iterable] must be a valid 'token' representing a single
+   * class, i.e. a non-empty string containing no whitespace.
+   */
+  void toggleAll(Iterable<String> iterable, [bool shouldAdd]);
+}
diff --git a/tools/dom/nnbd_src/CssRectangle.dart b/tools/dom/nnbd_src/CssRectangle.dart
new file mode 100644
index 0000000..9cdef06
--- /dev/null
+++ b/tools/dom/nnbd_src/CssRectangle.dart
@@ -0,0 +1,372 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * A rectangle representing all the content of the element in the
+ * [box model](http://www.w3.org/TR/CSS2/box.html).
+ */
+class _ContentCssRect extends CssRect {
+  _ContentCssRect(Element element) : super(element);
+
+  num get height =>
+      _element.offsetHeight + _addOrSubtractToBoxModel(_HEIGHT, _CONTENT);
+
+  num get width =>
+      _element.offsetWidth + _addOrSubtractToBoxModel(_WIDTH, _CONTENT);
+
+  /**
+   * Set the height to `newHeight`.
+   *
+   * newHeight can be either a [num] representing the height in pixels or a
+   * [Dimension] object. Values of newHeight that are less than zero are
+   * converted to effectively setting the height to 0. This is equivalent to the
+   * `height` function in jQuery and the calculated `height` CSS value,
+   * converted to a num in pixels.
+   */
+  set height(dynamic newHeight) {
+    if (newHeight is Dimension) {
+      Dimension newHeightAsDimension = newHeight;
+      if (newHeightAsDimension.value < 0) newHeight = new Dimension.px(0);
+      _element.style.height = newHeight.toString();
+    } else if (newHeight is num) {
+      if (newHeight < 0) newHeight = 0;
+      _element.style.height = '${newHeight}px';
+    } else {
+      throw new ArgumentError("newHeight is not a Dimension or num");
+    }
+  }
+
+  /**
+   * Set the current computed width in pixels of this element.
+   *
+   * newWidth can be either a [num] representing the width in pixels or a
+   * [Dimension] object. This is equivalent to the `width` function in jQuery
+   * and the calculated
+   * `width` CSS value, converted to a dimensionless num in pixels.
+   */
+  set width(dynamic newWidth) {
+    if (newWidth is Dimension) {
+      Dimension newWidthAsDimension = newWidth;
+      if (newWidthAsDimension.value < 0) newWidth = new Dimension.px(0);
+      _element.style.width = newWidth.toString();
+    } else if (newWidth is num) {
+      if (newWidth < 0) newWidth = 0;
+      _element.style.width = '${newWidth}px';
+    } else {
+      throw new ArgumentError("newWidth is not a Dimension or num");
+    }
+  }
+
+  num get left =>
+      _element.getBoundingClientRect().left -
+      _addOrSubtractToBoxModel(['left'], _CONTENT);
+  num get top =>
+      _element.getBoundingClientRect().top -
+      _addOrSubtractToBoxModel(['top'], _CONTENT);
+}
+
+/**
+ * A list of element content rectangles in the
+ * [box model](http://www.w3.org/TR/CSS2/box.html).
+ */
+class _ContentCssListRect extends _ContentCssRect {
+  List<Element> _elementList;
+
+  _ContentCssListRect(List<Element> elementList) : super(elementList.first) {
+    _elementList = elementList;
+  }
+
+  /**
+   * Set the height to `newHeight`.
+   *
+   * Values of newHeight that are less than zero are converted to effectively
+   * setting the height to 0. This is equivalent to the `height`
+   * function in jQuery and the calculated `height` CSS value, converted to a
+   * num in pixels.
+   */
+  set height(newHeight) {
+    _elementList.forEach((e) => e.contentEdge.height = newHeight);
+  }
+
+  /**
+   * Set the current computed width in pixels of this element.
+   *
+   * This is equivalent to the `width` function in jQuery and the calculated
+   * `width` CSS value, converted to a dimensionless num in pixels.
+   */
+  set width(newWidth) {
+    _elementList.forEach((e) => e.contentEdge.width = newWidth);
+  }
+}
+
+/**
+ * A rectangle representing the dimensions of the space occupied by the
+ * element's content + padding in the
+ * [box model](http://www.w3.org/TR/CSS2/box.html).
+ */
+class _PaddingCssRect extends CssRect {
+  _PaddingCssRect(element) : super(element);
+  num get height =>
+      _element.offsetHeight + _addOrSubtractToBoxModel(_HEIGHT, _PADDING);
+  num get width =>
+      _element.offsetWidth + _addOrSubtractToBoxModel(_WIDTH, _PADDING);
+
+  num get left =>
+      _element.getBoundingClientRect().left -
+      _addOrSubtractToBoxModel(['left'], _PADDING);
+  num get top =>
+      _element.getBoundingClientRect().top -
+      _addOrSubtractToBoxModel(['top'], _PADDING);
+}
+
+/**
+ * A rectangle representing the dimensions of the space occupied by the
+ * element's content + padding + border in the
+ * [box model](http://www.w3.org/TR/CSS2/box.html).
+ */
+class _BorderCssRect extends CssRect {
+  _BorderCssRect(element) : super(element);
+  num get height => _element.offsetHeight;
+  num get width => _element.offsetWidth;
+
+  num get left => _element.getBoundingClientRect().left;
+  num get top => _element.getBoundingClientRect().top;
+}
+
+/**
+ * A rectangle representing the dimensions of the space occupied by the
+ * element's content + padding + border + margin in the
+ * [box model](http://www.w3.org/TR/CSS2/box.html).
+ */
+class _MarginCssRect extends CssRect {
+  _MarginCssRect(element) : super(element);
+  num get height =>
+      _element.offsetHeight + _addOrSubtractToBoxModel(_HEIGHT, _MARGIN);
+  num get width =>
+      _element.offsetWidth + _addOrSubtractToBoxModel(_WIDTH, _MARGIN);
+
+  num get left =>
+      _element.getBoundingClientRect().left -
+      _addOrSubtractToBoxModel(['left'], _MARGIN);
+  num get top =>
+      _element.getBoundingClientRect().top -
+      _addOrSubtractToBoxModel(['top'], _MARGIN);
+}
+
+/**
+ * A class for representing CSS dimensions.
+ *
+ * In contrast to the more general purpose [Rectangle] class, this class's
+ * values are mutable, so one can change the height of an element
+ * programmatically.
+ *
+ * _Important_ _note_: use of these methods will perform CSS calculations that
+ * can trigger a browser reflow. Therefore, use of these properties _during_ an
+ * animation frame is discouraged. See also:
+ * [Browser Reflow](https://developers.google.com/speed/articles/reflow)
+ */
+abstract class CssRect implements Rectangle<num> {
+  Element _element;
+
+  CssRect(this._element);
+
+  num get left;
+
+  num get top;
+
+  /**
+   * The height of this rectangle.
+   *
+   * This is equivalent to the `height` function in jQuery and the calculated
+   * `height` CSS value, converted to a dimensionless num in pixels. Unlike
+   * [getBoundingClientRect], `height` will return the same numerical width if
+   * the element is hidden or not.
+   */
+  num get height;
+
+  /**
+   * The width of this rectangle.
+   *
+   * This is equivalent to the `width` function in jQuery and the calculated
+   * `width` CSS value, converted to a dimensionless num in pixels. Unlike
+   * [getBoundingClientRect], `width` will return the same numerical width if
+   * the element is hidden or not.
+   */
+  num get width;
+
+  /**
+   * Set the height to `newHeight`.
+   *
+   * newHeight can be either a [num] representing the height in pixels or a
+   * [Dimension] object. Values of newHeight that are less than zero are
+   * converted to effectively setting the height to 0. This is equivalent to the
+   * `height` function in jQuery and the calculated `height` CSS value,
+   * converted to a num in pixels.
+   *
+   * Note that only the content height can actually be set via this method.
+   */
+  set height(dynamic newHeight) {
+    throw new UnsupportedError("Can only set height for content rect.");
+  }
+
+  /**
+   * Set the current computed width in pixels of this element.
+   *
+   * newWidth can be either a [num] representing the width in pixels or a
+   * [Dimension] object. This is equivalent to the `width` function in jQuery
+   * and the calculated
+   * `width` CSS value, converted to a dimensionless num in pixels.
+   *
+   * Note that only the content width can be set via this method.
+   */
+  set width(dynamic newWidth) {
+    throw new UnsupportedError("Can only set width for content rect.");
+  }
+
+  /**
+   * Return a value that is used to modify the initial height or width
+   * measurement of an element. Depending on the value (ideally an enum) passed
+   * to augmentingMeasurement, we may need to add or subtract margin, padding,
+   * or border values, depending on the measurement we're trying to obtain.
+   */
+  num _addOrSubtractToBoxModel(
+      List<String> dimensions, String augmentingMeasurement) {
+    // getComputedStyle always returns pixel values (hence, computed), so we're
+    // always dealing with pixels in this method.
+    var styles = _element.getComputedStyle();
+
+    num val = 0;
+
+    for (String measurement in dimensions) {
+      // The border-box and default box model both exclude margin in the regular
+      // height/width calculation, so add it if we want it for this measurement.
+      if (augmentingMeasurement == _MARGIN) {
+        val += new Dimension.css(
+                styles.getPropertyValue('$augmentingMeasurement-$measurement'))
+            .value;
+      }
+
+      // The border-box includes padding and border, so remove it if we want
+      // just the content itself.
+      if (augmentingMeasurement == _CONTENT) {
+        val -= new Dimension.css(
+                styles.getPropertyValue('${_PADDING}-$measurement'))
+            .value;
+      }
+
+      // At this point, we don't wan't to augment with border or margin,
+      // so remove border.
+      if (augmentingMeasurement != _MARGIN) {
+        val -= new Dimension.css(
+                styles.getPropertyValue('border-${measurement}-width'))
+            .value;
+      }
+    }
+    return val;
+  }
+
+  // TODO(jacobr): these methods are duplicated from _RectangleBase in dart:math
+  // Ideally we would provide a RectangleMixin class that provides this
+  // implementation. In an ideal world we would exp
+  /** The x-coordinate of the right edge. */
+  num get right => left + width;
+  /** The y-coordinate of the bottom edge. */
+  num get bottom => top + height;
+
+  String toString() {
+    return 'Rectangle ($left, $top) $width x $height';
+  }
+
+  bool operator ==(other) =>
+      other is Rectangle &&
+      left == other.left &&
+      top == other.top &&
+      right == other.right &&
+      bottom == other.bottom;
+
+  int get hashCode => _JenkinsSmiHash.hash4(
+      left.hashCode, top.hashCode, right.hashCode, bottom.hashCode);
+
+  /**
+   * Computes the intersection of `this` and [other].
+   *
+   * The intersection of two axis-aligned rectangles, if any, is always another
+   * axis-aligned rectangle.
+   *
+   * Returns the intersection of this and `other`, or `null` if they don't
+   * intersect.
+   */
+  Rectangle<num> intersection(Rectangle<num> other) {
+    var x0 = max(left, other.left);
+    var x1 = min(left + width, other.left + other.width);
+
+    if (x0 <= x1) {
+      var y0 = max(top, other.top);
+      var y1 = min(top + height, other.top + other.height);
+
+      if (y0 <= y1) {
+        return new Rectangle<num>(x0, y0, x1 - x0, y1 - y0);
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Returns true if `this` intersects [other].
+   */
+  bool intersects(Rectangle<num> other) {
+    return (left <= other.left + other.width &&
+        other.left <= left + width &&
+        top <= other.top + other.height &&
+        other.top <= top + height);
+  }
+
+  /**
+   * Returns a new rectangle which completely contains `this` and [other].
+   */
+  Rectangle<num> boundingBox(Rectangle<num> other) {
+    var right = max(this.left + this.width, other.left + other.width);
+    var bottom = max(this.top + this.height, other.top + other.height);
+
+    var left = min(this.left, other.left);
+    var top = min(this.top, other.top);
+
+    return new Rectangle<num>(left, top, right - left, bottom - top);
+  }
+
+  /**
+   * Tests whether `this` entirely contains [another].
+   */
+  bool containsRectangle(Rectangle<num> another) {
+    return left <= another.left &&
+        left + width >= another.left + another.width &&
+        top <= another.top &&
+        top + height >= another.top + another.height;
+  }
+
+  /**
+   * Tests whether [another] is inside or along the edges of `this`.
+   */
+  bool containsPoint(Point<num> another) {
+    return another.x >= left &&
+        another.x <= left + width &&
+        another.y >= top &&
+        another.y <= top + height;
+  }
+
+  Point<num> get topLeft => new Point<num>(this.left, this.top);
+  Point<num> get topRight => new Point<num>(this.left + this.width, this.top);
+  Point<num> get bottomRight =>
+      new Point<num>(this.left + this.width, this.top + this.height);
+  Point<num> get bottomLeft =>
+      new Point<num>(this.left, this.top + this.height);
+}
+
+final _HEIGHT = ['top', 'bottom'];
+final _WIDTH = ['right', 'left'];
+final _CONTENT = 'content';
+final _PADDING = 'padding';
+final _MARGIN = 'margin';
diff --git a/tools/dom/nnbd_src/Dimension.dart b/tools/dom/nnbd_src/Dimension.dart
new file mode 100644
index 0000000..502b68d
--- /dev/null
+++ b/tools/dom/nnbd_src/Dimension.dart
@@ -0,0 +1,82 @@
+part of html;
+
+/**
+ * Class representing a
+ * [length measurement](https://developer.mozilla.org/en-US/docs/Web/CSS/length)
+ * in CSS.
+ */
+class Dimension {
+  num _value;
+  String _unit;
+
+  /** Set this CSS Dimension to a percentage `value`. */
+  Dimension.percent(this._value) : _unit = '%';
+
+  /** Set this CSS Dimension to a pixel `value`. */
+  Dimension.px(this._value) : _unit = 'px';
+
+  /** Set this CSS Dimension to a pica `value`. */
+  Dimension.pc(this._value) : _unit = 'pc';
+
+  /** Set this CSS Dimension to a point `value`. */
+  Dimension.pt(this._value) : _unit = 'pt';
+
+  /** Set this CSS Dimension to an inch `value`. */
+  Dimension.inch(this._value) : _unit = 'in';
+
+  /** Set this CSS Dimension to a centimeter `value`. */
+  Dimension.cm(this._value) : _unit = 'cm';
+
+  /** Set this CSS Dimension to a millimeter `value`. */
+  Dimension.mm(this._value) : _unit = 'mm';
+
+  /**
+   * Set this CSS Dimension to the specified number of ems.
+   *
+   * 1em is equal to the current font size. (So 2ems is equal to double the font
+   * size). This is useful for producing website layouts that scale nicely with
+   * the user's desired font size.
+   */
+  Dimension.em(this._value) : _unit = 'em';
+
+  /**
+   * Set this CSS Dimension to the specified number of x-heights.
+   *
+   * One ex is equal to the x-height of a font's baseline to its mean line,
+   * generally the height of the letter "x" in the font, which is usually about
+   * half the font-size.
+   */
+  Dimension.ex(this._value) : _unit = 'ex';
+
+  /**
+   * Construct a Dimension object from the valid, simple CSS string `cssValue`
+   * that represents a distance measurement.
+   *
+   * This constructor is intended as a convenience method for working with
+   * simplistic CSS length measurements. Non-numeric values such as `auto` or
+   * `inherit` or invalid CSS will cause this constructor to throw a
+   * FormatError.
+   */
+  Dimension.css(String cssValue) {
+    if (cssValue == '') cssValue = '0px';
+    if (cssValue.endsWith('%')) {
+      _unit = '%';
+    } else {
+      _unit = cssValue.substring(cssValue.length - 2);
+    }
+    if (cssValue.contains('.')) {
+      _value =
+          double.parse(cssValue.substring(0, cssValue.length - _unit.length));
+    } else {
+      _value = int.parse(cssValue.substring(0, cssValue.length - _unit.length));
+    }
+  }
+
+  /** Print out the CSS String representation of this value. */
+  String toString() {
+    return '${_value}${_unit}';
+  }
+
+  /** Return a unitless, numerical value of this CSS value. */
+  num get value => this._value;
+}
diff --git a/tools/dom/nnbd_src/EventListener.dart b/tools/dom/nnbd_src/EventListener.dart
new file mode 100644
index 0000000..60b29f1
--- /dev/null
+++ b/tools/dom/nnbd_src/EventListener.dart
@@ -0,0 +1,7 @@
+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+typedef EventListener(Event event);
diff --git a/tools/dom/nnbd_src/EventStreamProvider.dart b/tools/dom/nnbd_src/EventStreamProvider.dart
new file mode 100644
index 0000000..cb7e69b
--- /dev/null
+++ b/tools/dom/nnbd_src/EventStreamProvider.dart
@@ -0,0 +1,457 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * A factory to expose DOM events as Streams.
+ */
+class EventStreamProvider<T extends Event> {
+  final String _eventType;
+
+  const EventStreamProvider(this._eventType);
+
+  /**
+   * Gets a [Stream] for this event type, on the specified target.
+   *
+   * This will always return a broadcast stream so multiple listeners can be
+   * used simultaneously.
+   *
+   * This may be used to capture DOM events:
+   *
+   *     Element.keyDownEvent.forTarget(element, useCapture: true).listen(...);
+   *
+   *     // Alternate method:
+   *     Element.keyDownEvent.forTarget(element).capture(...);
+   *
+   * Or for listening to an event which will bubble through the DOM tree:
+   *
+   *     MediaElement.pauseEvent.forTarget(document.body).listen(...);
+   *
+   * See also:
+   *
+   * * [EventTarget.addEventListener](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener)
+   *   from MDN.
+   */
+  Stream<T> forTarget(EventTarget e, {bool useCapture: false}) =>
+      new _EventStream<T>(e, _eventType, useCapture);
+
+  /**
+   * Gets an [ElementEventStream] for this event type, on the specified element.
+   *
+   * This will always return a broadcast stream so multiple listeners can be
+   * used simultaneously.
+   *
+   * This may be used to capture DOM events:
+   *
+   *     Element.keyDownEvent.forElement(element, useCapture: true).listen(...);
+   *
+   *     // Alternate method:
+   *     Element.keyDownEvent.forElement(element).capture(...);
+   *
+   * Or for listening to an event which will bubble through the DOM tree:
+   *
+   *     MediaElement.pauseEvent.forElement(document.body).listen(...);
+   *
+   * See also:
+   *
+   * * [EventTarget.addEventListener](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener)
+   *   from MDN.
+   */
+  ElementStream<T> forElement(Element e, {bool useCapture: false}) {
+    return new _ElementEventStreamImpl<T>(e, _eventType, useCapture);
+  }
+
+  /**
+   * Gets an [ElementEventStream] for this event type, on the list of elements.
+   *
+   * This will always return a broadcast stream so multiple listeners can be
+   * used simultaneously.
+   *
+   * This may be used to capture DOM events:
+   *
+   *     Element.keyDownEvent._forElementList(element, useCapture: true).listen(...);
+   *
+   * See also:
+   *
+   * * [EventTarget.addEventListener](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener)
+   *   from MDN.
+   */
+  ElementStream<T> _forElementList(ElementList<Element> e,
+      {bool useCapture: false}) {
+    return new _ElementListEventStreamImpl<T>(e, _eventType, useCapture);
+  }
+
+  /**
+   * Gets the type of the event which this would listen for on the specified
+   * event target.
+   *
+   * The target is necessary because some browsers may use different event names
+   * for the same purpose and the target allows differentiating browser support.
+   */
+  String getEventType(EventTarget target) {
+    return _eventType;
+  }
+}
+
+/** A specialized Stream available to [Element]s to enable event delegation. */
+abstract class ElementStream<T extends Event> implements Stream<T> {
+  /**
+   * Return a stream that only fires when the particular event fires for
+   * elements matching the specified CSS selector.
+   *
+   * This is the Dart equivalent to jQuery's
+   * [delegate](http://api.jquery.com/delegate/).
+   */
+  Stream<T> matches(String selector);
+
+  /**
+   * Adds a capturing subscription to this stream.
+   *
+   * If the target of the event is a descendant of the element from which this
+   * stream derives then [onData] is called before the event propagates down to
+   * the target. This is the opposite of bubbling behavior, where the event
+   * is first processed for the event target and then bubbles upward.
+   *
+   * ## Other resources
+   *
+   * * [Event Capture](http://www.w3.org/TR/DOM-Level-2-Events/events.html#Events-flow-capture)
+   *   from the W3C DOM Events specification.
+   */
+  StreamSubscription<T> capture(void onData(T event));
+}
+
+/**
+ * Adapter for exposing DOM events as Dart streams.
+ */
+class _EventStream<T extends Event> extends Stream<T> {
+  final EventTarget _target;
+  final String _eventType;
+  final bool _useCapture;
+
+  _EventStream(this._target, this._eventType, this._useCapture);
+
+  // DOM events are inherently multi-subscribers.
+  Stream<T> asBroadcastStream(
+          {void onListen(StreamSubscription<T> subscription)?,
+          void onCancel(StreamSubscription<T> subscription)?}) =>
+      this;
+  bool get isBroadcast => true;
+
+  // TODO(9757): Inlining should be smart and inline only when inlining would
+  // enable scalar replacement of an immediately allocated receiver.
+  @pragma('dart2js:tryInline')
+  StreamSubscription<T> listen(void onData(T event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
+    return new _EventStreamSubscription<T>(
+        this._target, this._eventType, onData, this._useCapture);
+  }
+}
+
+bool _matchesWithAncestors(Event event, String selector) {
+  var target = event.target;
+  return target is Element ? target.matchesWithAncestors(selector) : false;
+}
+
+/**
+ * Adapter for exposing DOM Element events as streams, while also allowing
+ * event delegation.
+ */
+class _ElementEventStreamImpl<T extends Event> extends _EventStream<T>
+    implements ElementStream<T> {
+  _ElementEventStreamImpl(target, eventType, useCapture)
+      : super(target, eventType, useCapture);
+
+  Stream<T> matches(String selector) =>
+      this.where((event) => _matchesWithAncestors(event, selector)).map((e) {
+        e._selector = selector;
+        return e;
+      });
+
+  StreamSubscription<T> capture(void onData(T event)) =>
+      new _EventStreamSubscription<T>(
+          this._target, this._eventType, onData, true);
+}
+
+/**
+ * Adapter for exposing events on a collection of DOM Elements as streams,
+ * while also allowing event delegation.
+ */
+class _ElementListEventStreamImpl<T extends Event> extends Stream<T>
+    implements ElementStream<T> {
+  final Iterable<Element> _targetList;
+  final bool _useCapture;
+  final String _eventType;
+
+  _ElementListEventStreamImpl(
+      this._targetList, this._eventType, this._useCapture);
+
+  Stream<T> matches(String selector) =>
+      this.where((event) => _matchesWithAncestors(event, selector)).map((e) {
+        e._selector = selector;
+        return e;
+      });
+
+  // Delegate all regular Stream behavior to a wrapped Stream.
+  StreamSubscription<T> listen(void onData(T event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
+    var pool = new _StreamPool<T>.broadcast();
+    for (var target in _targetList) {
+      pool.add(new _EventStream<T>(target, _eventType, _useCapture));
+    }
+    return pool.stream.listen(onData,
+        onError: onError, onDone: onDone, cancelOnError: cancelOnError);
+  }
+
+  StreamSubscription<T> capture(void onData(T event)) {
+    var pool = new _StreamPool<T>.broadcast();
+    for (var target in _targetList) {
+      pool.add(new _EventStream<T>(target, _eventType, true));
+    }
+    return pool.stream.listen(onData);
+  }
+
+  Stream<T> asBroadcastStream(
+          {void onListen(StreamSubscription<T> subscription)?,
+          void onCancel(StreamSubscription<T> subscription)?}) =>
+      this;
+  bool get isBroadcast => true;
+}
+
+// We would like this to just be EventListener<T> but that typdef cannot
+// use generics until dartbug/26276 is fixed.
+typedef _EventListener<T extends Event>(T event);
+
+class _EventStreamSubscription<T extends Event> extends StreamSubscription<T> {
+  int _pauseCount = 0;
+  EventTarget _target;
+  final String _eventType;
+  EventListener _onData;
+  final bool _useCapture;
+
+  // TODO(leafp): It would be better to write this as
+  // _onData = onData == null ? null :
+  //   onData is void Function(Event)
+  //     ? _wrapZone<Event>(onData)
+  //     : _wrapZone<Event>((e) => onData(e as T))
+  // In order to support existing tests which pass the wrong type of events but
+  // use a more general listener, without causing as much slowdown for things
+  // which are typed correctly.  But this currently runs afoul of restrictions
+  // on is checks for compatibility with the VM.
+  _EventStreamSubscription(
+      this._target, this._eventType, void onData(T event), this._useCapture)
+      : _onData = onData == null
+            ? null
+            : _wrapZone<Event>((e) => (onData as dynamic)(e)) {
+    _tryResume();
+  }
+
+  Future cancel() {
+    if (_canceled) return null;
+
+    _unlisten();
+    // Clear out the target to indicate this is complete.
+    _target = null;
+    _onData = null;
+    return null;
+  }
+
+  bool get _canceled => _target == null;
+
+  void onData(void handleData(T event)?) {
+    if (_canceled) {
+      throw new StateError("Subscription has been canceled.");
+    }
+    // Remove current event listener.
+    _unlisten();
+    _onData = handleData == null
+        ? null
+        : _wrapZone<Event>((e) => (handleData as dynamic)(e));
+    _tryResume();
+  }
+
+  /// Has no effect.
+  void onError(Function? handleError) {}
+
+  /// Has no effect.
+  void onDone(void handleDone()?) {}
+
+  void pause([Future? resumeSignal]) {
+    if (_canceled) return;
+    ++_pauseCount;
+    _unlisten();
+
+    if (resumeSignal != null) {
+      resumeSignal.whenComplete(resume);
+    }
+  }
+
+  bool get isPaused => _pauseCount > 0;
+
+  void resume() {
+    if (_canceled || !isPaused) return;
+    --_pauseCount;
+    _tryResume();
+  }
+
+  void _tryResume() {
+    if (_onData != null && !isPaused) {
+      _target.addEventListener(_eventType, _onData, _useCapture);
+    }
+  }
+
+  void _unlisten() {
+    if (_onData != null) {
+      _target.removeEventListener(_eventType, _onData, _useCapture);
+    }
+  }
+
+  Future<E> asFuture<E>([E? futureValue]) {
+    // We just need a future that will never succeed or fail.
+    var completer = new Completer<E>();
+    return completer.future;
+  }
+}
+
+/**
+ * A stream of custom events, which enables the user to "fire" (add) their own
+ * custom events to a stream.
+ */
+abstract class CustomStream<T extends Event> implements Stream<T> {
+  /**
+   * Add the following custom event to the stream for dispatching to interested
+   * listeners.
+   */
+  void add(T event);
+}
+
+class _CustomEventStreamImpl<T extends Event> extends Stream<T>
+    implements CustomStream<T> {
+  StreamController<T> _streamController;
+  /** The type of event this stream is providing (e.g. "keydown"). */
+  String _type;
+
+  _CustomEventStreamImpl(String type) {
+    _type = type;
+    _streamController = new StreamController.broadcast(sync: true);
+  }
+
+  // Delegate all regular Stream behavior to our wrapped Stream.
+  StreamSubscription<T> listen(void onData(T event)?,
+      {Function? onError, void onDone()?, bool? cancelOnError}) {
+    return _streamController.stream.listen(onData,
+        onError: onError, onDone: onDone, cancelOnError: cancelOnError);
+  }
+
+  Stream<T> asBroadcastStream(
+          {void onListen(StreamSubscription<T> subscription)?,
+          void onCancel(StreamSubscription<T> subscription)?}) =>
+      _streamController.stream;
+
+  bool get isBroadcast => true;
+
+  void add(T event) {
+    if (event.type == _type) _streamController.add(event);
+  }
+}
+
+class _CustomKeyEventStreamImpl extends _CustomEventStreamImpl<KeyEvent>
+    implements CustomStream<KeyEvent> {
+  _CustomKeyEventStreamImpl(String type) : super(type);
+
+  void add(KeyEvent event) {
+    if (event.type == _type) {
+      event.currentTarget.dispatchEvent(event._parent);
+      _streamController.add(event);
+    }
+  }
+}
+
+/**
+ * A pool of streams whose events are unified and emitted through a central
+ * stream.
+ */
+// TODO (efortuna): Remove this when Issue 12218 is addressed.
+class _StreamPool<T> {
+  StreamController<T> _controller;
+
+  /// Subscriptions to the streams that make up the pool.
+  var _subscriptions = new Map<Stream<T>, StreamSubscription<T>>();
+
+  /**
+   * Creates a new stream pool where [stream] can be listened to more than
+   * once.
+   *
+   * Any events from buffered streams in the pool will be emitted immediately,
+   * regardless of whether [stream] has any subscribers.
+   */
+  _StreamPool.broadcast() {
+    _controller =
+        new StreamController<T>.broadcast(sync: true, onCancel: close);
+  }
+
+  /**
+   * The stream through which all events from streams in the pool are emitted.
+   */
+  Stream<T> get stream => _controller.stream;
+
+  /**
+   * Adds [stream] as a member of this pool.
+   *
+   * Any events from [stream] will be emitted through [this.stream]. If
+   * [stream] is sync, they'll be emitted synchronously; if [stream] is async,
+   * they'll be emitted asynchronously.
+   */
+  void add(Stream<T> stream) {
+    if (_subscriptions.containsKey(stream)) return;
+    _subscriptions[stream] = stream.listen(_controller.add,
+        onError: _controller.addError, onDone: () => remove(stream));
+  }
+
+  /** Removes [stream] as a member of this pool. */
+  void remove(Stream<T> stream) {
+    var subscription = _subscriptions.remove(stream);
+    if (subscription != null) subscription.cancel();
+  }
+
+  /** Removes all streams from this pool and closes [stream]. */
+  void close() {
+    for (var subscription in _subscriptions.values) {
+      subscription.cancel();
+    }
+    _subscriptions.clear();
+    _controller.close();
+  }
+}
+
+/**
+ * A factory to expose DOM events as streams, where the DOM event name has to
+ * be determined on the fly (for example, mouse wheel events).
+ */
+class _CustomEventStreamProvider<T extends Event>
+    implements EventStreamProvider<T> {
+  final _eventTypeGetter;
+  const _CustomEventStreamProvider(this._eventTypeGetter);
+
+  Stream<T> forTarget(EventTarget e, {bool useCapture: false}) {
+    return new _EventStream<T>(e, _eventTypeGetter(e), useCapture);
+  }
+
+  ElementStream<T> forElement(Element e, {bool useCapture: false}) {
+    return new _ElementEventStreamImpl<T>(e, _eventTypeGetter(e), useCapture);
+  }
+
+  ElementStream<T> _forElementList(ElementList<Element> e,
+      {bool useCapture: false}) {
+    return new _ElementListEventStreamImpl<T>(
+        e, _eventTypeGetter(e), useCapture);
+  }
+
+  String getEventType(EventTarget target) {
+    return _eventTypeGetter(target);
+  }
+
+  String get _eventType =>
+      throw new UnsupportedError('Access type through getEventType method.');
+}
diff --git a/tools/dom/nnbd_src/Html5NodeValidator.dart b/tools/dom/nnbd_src/Html5NodeValidator.dart
new file mode 100644
index 0000000..e6bdede
--- /dev/null
+++ b/tools/dom/nnbd_src/Html5NodeValidator.dart
@@ -0,0 +1,449 @@
+// DO NOT EDIT- this file is generated from running tool/generator.sh.
+
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.dom.html;
+
+/**
+ * A Dart DOM validator generated from Caja whitelists.
+ *
+ * This contains a whitelist of known HTML tagNames and attributes and will only
+ * accept known good values.
+ *
+ * See also:
+ *
+ * * <https://code.google.com/p/google-caja/wiki/CajaWhitelists>
+ */
+class _Html5NodeValidator implements NodeValidator {
+  static final Set<String> _allowedElements = new Set.from([
+    'A',
+    'ABBR',
+    'ACRONYM',
+    'ADDRESS',
+    'AREA',
+    'ARTICLE',
+    'ASIDE',
+    'AUDIO',
+    'B',
+    'BDI',
+    'BDO',
+    'BIG',
+    'BLOCKQUOTE',
+    'BR',
+    'BUTTON',
+    'CANVAS',
+    'CAPTION',
+    'CENTER',
+    'CITE',
+    'CODE',
+    'COL',
+    'COLGROUP',
+    'COMMAND',
+    'DATA',
+    'DATALIST',
+    'DD',
+    'DEL',
+    'DETAILS',
+    'DFN',
+    'DIR',
+    'DIV',
+    'DL',
+    'DT',
+    'EM',
+    'FIELDSET',
+    'FIGCAPTION',
+    'FIGURE',
+    'FONT',
+    'FOOTER',
+    'FORM',
+    'H1',
+    'H2',
+    'H3',
+    'H4',
+    'H5',
+    'H6',
+    'HEADER',
+    'HGROUP',
+    'HR',
+    'I',
+    'IFRAME',
+    'IMG',
+    'INPUT',
+    'INS',
+    'KBD',
+    'LABEL',
+    'LEGEND',
+    'LI',
+    'MAP',
+    'MARK',
+    'MENU',
+    'METER',
+    'NAV',
+    'NOBR',
+    'OL',
+    'OPTGROUP',
+    'OPTION',
+    'OUTPUT',
+    'P',
+    'PRE',
+    'PROGRESS',
+    'Q',
+    'S',
+    'SAMP',
+    'SECTION',
+    'SELECT',
+    'SMALL',
+    'SOURCE',
+    'SPAN',
+    'STRIKE',
+    'STRONG',
+    'SUB',
+    'SUMMARY',
+    'SUP',
+    'TABLE',
+    'TBODY',
+    'TD',
+    'TEXTAREA',
+    'TFOOT',
+    'TH',
+    'THEAD',
+    'TIME',
+    'TR',
+    'TRACK',
+    'TT',
+    'U',
+    'UL',
+    'VAR',
+    'VIDEO',
+    'WBR',
+  ]);
+
+  static const _standardAttributes = const <String>[
+    '*::class',
+    '*::dir',
+    '*::draggable',
+    '*::hidden',
+    '*::id',
+    '*::inert',
+    '*::itemprop',
+    '*::itemref',
+    '*::itemscope',
+    '*::lang',
+    '*::spellcheck',
+    '*::title',
+    '*::translate',
+    'A::accesskey',
+    'A::coords',
+    'A::hreflang',
+    'A::name',
+    'A::shape',
+    'A::tabindex',
+    'A::target',
+    'A::type',
+    'AREA::accesskey',
+    'AREA::alt',
+    'AREA::coords',
+    'AREA::nohref',
+    'AREA::shape',
+    'AREA::tabindex',
+    'AREA::target',
+    'AUDIO::controls',
+    'AUDIO::loop',
+    'AUDIO::mediagroup',
+    'AUDIO::muted',
+    'AUDIO::preload',
+    'BDO::dir',
+    'BODY::alink',
+    'BODY::bgcolor',
+    'BODY::link',
+    'BODY::text',
+    'BODY::vlink',
+    'BR::clear',
+    'BUTTON::accesskey',
+    'BUTTON::disabled',
+    'BUTTON::name',
+    'BUTTON::tabindex',
+    'BUTTON::type',
+    'BUTTON::value',
+    'CANVAS::height',
+    'CANVAS::width',
+    'CAPTION::align',
+    'COL::align',
+    'COL::char',
+    'COL::charoff',
+    'COL::span',
+    'COL::valign',
+    'COL::width',
+    'COLGROUP::align',
+    'COLGROUP::char',
+    'COLGROUP::charoff',
+    'COLGROUP::span',
+    'COLGROUP::valign',
+    'COLGROUP::width',
+    'COMMAND::checked',
+    'COMMAND::command',
+    'COMMAND::disabled',
+    'COMMAND::label',
+    'COMMAND::radiogroup',
+    'COMMAND::type',
+    'DATA::value',
+    'DEL::datetime',
+    'DETAILS::open',
+    'DIR::compact',
+    'DIV::align',
+    'DL::compact',
+    'FIELDSET::disabled',
+    'FONT::color',
+    'FONT::face',
+    'FONT::size',
+    'FORM::accept',
+    'FORM::autocomplete',
+    'FORM::enctype',
+    'FORM::method',
+    'FORM::name',
+    'FORM::novalidate',
+    'FORM::target',
+    'FRAME::name',
+    'H1::align',
+    'H2::align',
+    'H3::align',
+    'H4::align',
+    'H5::align',
+    'H6::align',
+    'HR::align',
+    'HR::noshade',
+    'HR::size',
+    'HR::width',
+    'HTML::version',
+    'IFRAME::align',
+    'IFRAME::frameborder',
+    'IFRAME::height',
+    'IFRAME::marginheight',
+    'IFRAME::marginwidth',
+    'IFRAME::width',
+    'IMG::align',
+    'IMG::alt',
+    'IMG::border',
+    'IMG::height',
+    'IMG::hspace',
+    'IMG::ismap',
+    'IMG::name',
+    'IMG::usemap',
+    'IMG::vspace',
+    'IMG::width',
+    'INPUT::accept',
+    'INPUT::accesskey',
+    'INPUT::align',
+    'INPUT::alt',
+    'INPUT::autocomplete',
+    'INPUT::autofocus',
+    'INPUT::checked',
+    'INPUT::disabled',
+    'INPUT::inputmode',
+    'INPUT::ismap',
+    'INPUT::list',
+    'INPUT::max',
+    'INPUT::maxlength',
+    'INPUT::min',
+    'INPUT::multiple',
+    'INPUT::name',
+    'INPUT::placeholder',
+    'INPUT::readonly',
+    'INPUT::required',
+    'INPUT::size',
+    'INPUT::step',
+    'INPUT::tabindex',
+    'INPUT::type',
+    'INPUT::usemap',
+    'INPUT::value',
+    'INS::datetime',
+    'KEYGEN::disabled',
+    'KEYGEN::keytype',
+    'KEYGEN::name',
+    'LABEL::accesskey',
+    'LABEL::for',
+    'LEGEND::accesskey',
+    'LEGEND::align',
+    'LI::type',
+    'LI::value',
+    'LINK::sizes',
+    'MAP::name',
+    'MENU::compact',
+    'MENU::label',
+    'MENU::type',
+    'METER::high',
+    'METER::low',
+    'METER::max',
+    'METER::min',
+    'METER::value',
+    'OBJECT::typemustmatch',
+    'OL::compact',
+    'OL::reversed',
+    'OL::start',
+    'OL::type',
+    'OPTGROUP::disabled',
+    'OPTGROUP::label',
+    'OPTION::disabled',
+    'OPTION::label',
+    'OPTION::selected',
+    'OPTION::value',
+    'OUTPUT::for',
+    'OUTPUT::name',
+    'P::align',
+    'PRE::width',
+    'PROGRESS::max',
+    'PROGRESS::min',
+    'PROGRESS::value',
+    'SELECT::autocomplete',
+    'SELECT::disabled',
+    'SELECT::multiple',
+    'SELECT::name',
+    'SELECT::required',
+    'SELECT::size',
+    'SELECT::tabindex',
+    'SOURCE::type',
+    'TABLE::align',
+    'TABLE::bgcolor',
+    'TABLE::border',
+    'TABLE::cellpadding',
+    'TABLE::cellspacing',
+    'TABLE::frame',
+    'TABLE::rules',
+    'TABLE::summary',
+    'TABLE::width',
+    'TBODY::align',
+    'TBODY::char',
+    'TBODY::charoff',
+    'TBODY::valign',
+    'TD::abbr',
+    'TD::align',
+    'TD::axis',
+    'TD::bgcolor',
+    'TD::char',
+    'TD::charoff',
+    'TD::colspan',
+    'TD::headers',
+    'TD::height',
+    'TD::nowrap',
+    'TD::rowspan',
+    'TD::scope',
+    'TD::valign',
+    'TD::width',
+    'TEXTAREA::accesskey',
+    'TEXTAREA::autocomplete',
+    'TEXTAREA::cols',
+    'TEXTAREA::disabled',
+    'TEXTAREA::inputmode',
+    'TEXTAREA::name',
+    'TEXTAREA::placeholder',
+    'TEXTAREA::readonly',
+    'TEXTAREA::required',
+    'TEXTAREA::rows',
+    'TEXTAREA::tabindex',
+    'TEXTAREA::wrap',
+    'TFOOT::align',
+    'TFOOT::char',
+    'TFOOT::charoff',
+    'TFOOT::valign',
+    'TH::abbr',
+    'TH::align',
+    'TH::axis',
+    'TH::bgcolor',
+    'TH::char',
+    'TH::charoff',
+    'TH::colspan',
+    'TH::headers',
+    'TH::height',
+    'TH::nowrap',
+    'TH::rowspan',
+    'TH::scope',
+    'TH::valign',
+    'TH::width',
+    'THEAD::align',
+    'THEAD::char',
+    'THEAD::charoff',
+    'THEAD::valign',
+    'TR::align',
+    'TR::bgcolor',
+    'TR::char',
+    'TR::charoff',
+    'TR::valign',
+    'TRACK::default',
+    'TRACK::kind',
+    'TRACK::label',
+    'TRACK::srclang',
+    'UL::compact',
+    'UL::type',
+    'VIDEO::controls',
+    'VIDEO::height',
+    'VIDEO::loop',
+    'VIDEO::mediagroup',
+    'VIDEO::muted',
+    'VIDEO::preload',
+    'VIDEO::width',
+  ];
+
+  static const _uriAttributes = const <String>[
+    'A::href',
+    'AREA::href',
+    'BLOCKQUOTE::cite',
+    'BODY::background',
+    'COMMAND::icon',
+    'DEL::cite',
+    'FORM::action',
+    'IMG::src',
+    'INPUT::src',
+    'INS::cite',
+    'Q::cite',
+    'VIDEO::poster',
+  ];
+
+  final UriPolicy uriPolicy;
+
+  static final Map<String, Function> _attributeValidators = {};
+
+  /**
+   * All known URI attributes will be validated against the UriPolicy, if
+   * [uriPolicy] is null then a default UriPolicy will be used.
+   */
+  _Html5NodeValidator({UriPolicy? uriPolicy})
+      : uriPolicy = uriPolicy ?? UriPolicy() {
+    if (_attributeValidators.isEmpty) {
+      for (var attr in _standardAttributes) {
+        _attributeValidators[attr] = _standardAttributeValidator;
+      }
+
+      for (var attr in _uriAttributes) {
+        _attributeValidators[attr] = _uriAttributeValidator;
+      }
+    }
+  }
+
+  bool allowsElement(Element element) {
+    return _allowedElements.contains(Element._safeTagName(element));
+  }
+
+  bool allowsAttribute(Element element, String attributeName, String value) {
+    var tagName = Element._safeTagName(element);
+    var validator = _attributeValidators['$tagName::$attributeName'];
+    if (validator == null) {
+      validator = _attributeValidators['*::$attributeName'];
+    }
+    if (validator == null) {
+      return false;
+    }
+    return validator(element, attributeName, value, this);
+  }
+
+  static bool _standardAttributeValidator(Element element, String attributeName,
+      String value, _Html5NodeValidator context) {
+    return true;
+  }
+
+  static bool _uriAttributeValidator(Element element, String attributeName,
+      String value, _Html5NodeValidator context) {
+    return context.uriPolicy.allowsUri(value);
+  }
+}
diff --git a/tools/dom/nnbd_src/ImmutableListMixin.dart b/tools/dom/nnbd_src/ImmutableListMixin.dart
new file mode 100644
index 0000000..9910ebe
--- /dev/null
+++ b/tools/dom/nnbd_src/ImmutableListMixin.dart
@@ -0,0 +1,80 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.dom.html;
+
+abstract class ImmutableListMixin<E> implements List<E> {
+  // From Iterable<$E>:
+  Iterator<E> get iterator {
+    // Note: NodeLists are not fixed size. And most probably length shouldn't
+    // be cached in both iterator _and_ forEach method. For now caching it
+    // for consistency.
+    return new FixedSizeListIterator<E>(this);
+  }
+
+  // From List<E>:
+  void add(E value) {
+    throw new UnsupportedError("Cannot add to immutable List.");
+  }
+
+  void addAll(Iterable<E> iterable) {
+    throw new UnsupportedError("Cannot add to immutable List.");
+  }
+
+  void sort([int compare(E a, E b)?]) {
+    throw new UnsupportedError("Cannot sort immutable List.");
+  }
+
+  void shuffle([Random? random]) {
+    throw new UnsupportedError("Cannot shuffle immutable List.");
+  }
+
+  void insert(int index, E element) {
+    throw new UnsupportedError("Cannot add to immutable List.");
+  }
+
+  void insertAll(int index, Iterable<E> iterable) {
+    throw new UnsupportedError("Cannot add to immutable List.");
+  }
+
+  void setAll(int index, Iterable<E> iterable) {
+    throw new UnsupportedError("Cannot modify an immutable List.");
+  }
+
+  E removeAt(int pos) {
+    throw new UnsupportedError("Cannot remove from immutable List.");
+  }
+
+  E removeLast() {
+    throw new UnsupportedError("Cannot remove from immutable List.");
+  }
+
+  bool remove(Object? object) {
+    throw new UnsupportedError("Cannot remove from immutable List.");
+  }
+
+  void removeWhere(bool test(E element)) {
+    throw new UnsupportedError("Cannot remove from immutable List.");
+  }
+
+  void retainWhere(bool test(E element)) {
+    throw new UnsupportedError("Cannot remove from immutable List.");
+  }
+
+  void setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]) {
+    throw new UnsupportedError("Cannot setRange on immutable List.");
+  }
+
+  void removeRange(int start, int end) {
+    throw new UnsupportedError("Cannot removeRange on immutable List.");
+  }
+
+  void replaceRange(int start, int end, Iterable<E> iterable) {
+    throw new UnsupportedError("Cannot modify an immutable List.");
+  }
+
+  void fillRange(int start, int end, [E? fillValue]) {
+    throw new UnsupportedError("Cannot modify an immutable List.");
+  }
+}
diff --git a/tools/dom/nnbd_src/KeyCode.dart b/tools/dom/nnbd_src/KeyCode.dart
new file mode 100644
index 0000000..a51d062
--- /dev/null
+++ b/tools/dom/nnbd_src/KeyCode.dart
@@ -0,0 +1,331 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * Defines the keycode values for keys that are returned by
+ * KeyboardEvent.keyCode.
+ *
+ * Important note: There is substantial divergence in how different browsers
+ * handle keycodes and their variants in different locales/keyboard layouts. We
+ * provide these constants to help make code processing keys more readable.
+ */
+abstract class KeyCode {
+  // These constant names were borrowed from Closure's Keycode enumeration
+  // class.
+  // https://github.com/google/closure-library/blob/master/closure/goog/events/keycodes.js
+  static const int WIN_KEY_FF_LINUX = 0;
+  static const int MAC_ENTER = 3;
+  static const int BACKSPACE = 8;
+  static const int TAB = 9;
+  /** NUM_CENTER is also NUMLOCK for FF and Safari on Mac. */
+  static const int NUM_CENTER = 12;
+  static const int ENTER = 13;
+  static const int SHIFT = 16;
+  static const int CTRL = 17;
+  static const int ALT = 18;
+  static const int PAUSE = 19;
+  static const int CAPS_LOCK = 20;
+  static const int ESC = 27;
+  static const int SPACE = 32;
+  static const int PAGE_UP = 33;
+  static const int PAGE_DOWN = 34;
+  static const int END = 35;
+  static const int HOME = 36;
+  static const int LEFT = 37;
+  static const int UP = 38;
+  static const int RIGHT = 39;
+  static const int DOWN = 40;
+  static const int NUM_NORTH_EAST = 33;
+  static const int NUM_SOUTH_EAST = 34;
+  static const int NUM_SOUTH_WEST = 35;
+  static const int NUM_NORTH_WEST = 36;
+  static const int NUM_WEST = 37;
+  static const int NUM_NORTH = 38;
+  static const int NUM_EAST = 39;
+  static const int NUM_SOUTH = 40;
+  static const int PRINT_SCREEN = 44;
+  static const int INSERT = 45;
+  static const int NUM_INSERT = 45;
+  static const int DELETE = 46;
+  static const int NUM_DELETE = 46;
+  static const int ZERO = 48;
+  static const int ONE = 49;
+  static const int TWO = 50;
+  static const int THREE = 51;
+  static const int FOUR = 52;
+  static const int FIVE = 53;
+  static const int SIX = 54;
+  static const int SEVEN = 55;
+  static const int EIGHT = 56;
+  static const int NINE = 57;
+  static const int FF_SEMICOLON = 59;
+  static const int FF_EQUALS = 61;
+  /**
+   * CAUTION: The question mark is for US-keyboard layouts. It varies
+   * for other locales and keyboard layouts.
+   */
+  static const int QUESTION_MARK = 63;
+  static const int A = 65;
+  static const int B = 66;
+  static const int C = 67;
+  static const int D = 68;
+  static const int E = 69;
+  static const int F = 70;
+  static const int G = 71;
+  static const int H = 72;
+  static const int I = 73;
+  static const int J = 74;
+  static const int K = 75;
+  static const int L = 76;
+  static const int M = 77;
+  static const int N = 78;
+  static const int O = 79;
+  static const int P = 80;
+  static const int Q = 81;
+  static const int R = 82;
+  static const int S = 83;
+  static const int T = 84;
+  static const int U = 85;
+  static const int V = 86;
+  static const int W = 87;
+  static const int X = 88;
+  static const int Y = 89;
+  static const int Z = 90;
+  static const int META = 91;
+  static const int WIN_KEY_LEFT = 91;
+  static const int WIN_KEY_RIGHT = 92;
+  static const int CONTEXT_MENU = 93;
+  static const int NUM_ZERO = 96;
+  static const int NUM_ONE = 97;
+  static const int NUM_TWO = 98;
+  static const int NUM_THREE = 99;
+  static const int NUM_FOUR = 100;
+  static const int NUM_FIVE = 101;
+  static const int NUM_SIX = 102;
+  static const int NUM_SEVEN = 103;
+  static const int NUM_EIGHT = 104;
+  static const int NUM_NINE = 105;
+  static const int NUM_MULTIPLY = 106;
+  static const int NUM_PLUS = 107;
+  static const int NUM_MINUS = 109;
+  static const int NUM_PERIOD = 110;
+  static const int NUM_DIVISION = 111;
+  static const int F1 = 112;
+  static const int F2 = 113;
+  static const int F3 = 114;
+  static const int F4 = 115;
+  static const int F5 = 116;
+  static const int F6 = 117;
+  static const int F7 = 118;
+  static const int F8 = 119;
+  static const int F9 = 120;
+  static const int F10 = 121;
+  static const int F11 = 122;
+  static const int F12 = 123;
+  static const int NUMLOCK = 144;
+  static const int SCROLL_LOCK = 145;
+
+  // OS-specific media keys like volume controls and browser controls.
+  static const int FIRST_MEDIA_KEY = 166;
+  static const int LAST_MEDIA_KEY = 183;
+
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int SEMICOLON = 186;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int DASH = 189;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int EQUALS = 187;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int COMMA = 188;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int PERIOD = 190;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int SLASH = 191;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int APOSTROPHE = 192;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int TILDE = 192;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int SINGLE_QUOTE = 222;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int OPEN_SQUARE_BRACKET = 219;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int BACKSLASH = 220;
+  /**
+   * CAUTION: This constant requires localization for other locales and keyboard
+   * layouts.
+   */
+  static const int CLOSE_SQUARE_BRACKET = 221;
+  static const int WIN_KEY = 224;
+  static const int MAC_FF_META = 224;
+  static const int WIN_IME = 229;
+
+  /** A sentinel value if the keycode could not be determined. */
+  static const int UNKNOWN = -1;
+
+  /**
+   * Returns true if the keyCode produces a (US keyboard) character.
+   * Note: This does not (yet) cover characters on non-US keyboards (Russian,
+   * Hebrew, etc.).
+   */
+  static bool isCharacterKey(int keyCode) {
+    if ((keyCode >= ZERO && keyCode <= NINE) ||
+        (keyCode >= NUM_ZERO && keyCode <= NUM_MULTIPLY) ||
+        (keyCode >= A && keyCode <= Z)) {
+      return true;
+    }
+
+    // Safari sends zero key code for non-latin characters.
+    if (Device.isWebKit && keyCode == 0) {
+      return true;
+    }
+
+    return (keyCode == SPACE ||
+        keyCode == QUESTION_MARK ||
+        keyCode == NUM_PLUS ||
+        keyCode == NUM_MINUS ||
+        keyCode == NUM_PERIOD ||
+        keyCode == NUM_DIVISION ||
+        keyCode == SEMICOLON ||
+        keyCode == FF_SEMICOLON ||
+        keyCode == DASH ||
+        keyCode == EQUALS ||
+        keyCode == FF_EQUALS ||
+        keyCode == COMMA ||
+        keyCode == PERIOD ||
+        keyCode == SLASH ||
+        keyCode == APOSTROPHE ||
+        keyCode == SINGLE_QUOTE ||
+        keyCode == OPEN_SQUARE_BRACKET ||
+        keyCode == BACKSLASH ||
+        keyCode == CLOSE_SQUARE_BRACKET);
+  }
+
+  /**
+   * Experimental helper function for converting keyCodes to keyNames for the
+   * keyIdentifier attribute still used in browsers not updated with current
+   * spec. This is an imperfect conversion! It will need to be refined, but
+   * hopefully it can just completely go away once all the browsers update to
+   * follow the DOM3 spec.
+   */
+  static String _convertKeyCodeToKeyName(int keyCode) {
+    switch (keyCode) {
+      case KeyCode.ALT:
+        return _KeyName.ALT;
+      case KeyCode.BACKSPACE:
+        return _KeyName.BACKSPACE;
+      case KeyCode.CAPS_LOCK:
+        return _KeyName.CAPS_LOCK;
+      case KeyCode.CTRL:
+        return _KeyName.CONTROL;
+      case KeyCode.DELETE:
+        return _KeyName.DEL;
+      case KeyCode.DOWN:
+        return _KeyName.DOWN;
+      case KeyCode.END:
+        return _KeyName.END;
+      case KeyCode.ENTER:
+        return _KeyName.ENTER;
+      case KeyCode.ESC:
+        return _KeyName.ESC;
+      case KeyCode.F1:
+        return _KeyName.F1;
+      case KeyCode.F2:
+        return _KeyName.F2;
+      case KeyCode.F3:
+        return _KeyName.F3;
+      case KeyCode.F4:
+        return _KeyName.F4;
+      case KeyCode.F5:
+        return _KeyName.F5;
+      case KeyCode.F6:
+        return _KeyName.F6;
+      case KeyCode.F7:
+        return _KeyName.F7;
+      case KeyCode.F8:
+        return _KeyName.F8;
+      case KeyCode.F9:
+        return _KeyName.F9;
+      case KeyCode.F10:
+        return _KeyName.F10;
+      case KeyCode.F11:
+        return _KeyName.F11;
+      case KeyCode.F12:
+        return _KeyName.F12;
+      case KeyCode.HOME:
+        return _KeyName.HOME;
+      case KeyCode.INSERT:
+        return _KeyName.INSERT;
+      case KeyCode.LEFT:
+        return _KeyName.LEFT;
+      case KeyCode.META:
+        return _KeyName.META;
+      case KeyCode.NUMLOCK:
+        return _KeyName.NUM_LOCK;
+      case KeyCode.PAGE_DOWN:
+        return _KeyName.PAGE_DOWN;
+      case KeyCode.PAGE_UP:
+        return _KeyName.PAGE_UP;
+      case KeyCode.PAUSE:
+        return _KeyName.PAUSE;
+      case KeyCode.PRINT_SCREEN:
+        return _KeyName.PRINT_SCREEN;
+      case KeyCode.RIGHT:
+        return _KeyName.RIGHT;
+      case KeyCode.SCROLL_LOCK:
+        return _KeyName.SCROLL;
+      case KeyCode.SHIFT:
+        return _KeyName.SHIFT;
+      case KeyCode.SPACE:
+        return _KeyName.SPACEBAR;
+      case KeyCode.TAB:
+        return _KeyName.TAB;
+      case KeyCode.UP:
+        return _KeyName.UP;
+      case KeyCode.WIN_IME:
+      case KeyCode.WIN_KEY:
+      case KeyCode.WIN_KEY_LEFT:
+      case KeyCode.WIN_KEY_RIGHT:
+        return _KeyName.WIN;
+      default:
+        return _KeyName.UNIDENTIFIED;
+    }
+    return _KeyName.UNIDENTIFIED;
+  }
+}
diff --git a/tools/dom/nnbd_src/KeyLocation.dart b/tools/dom/nnbd_src/KeyLocation.dart
new file mode 100644
index 0000000..db4c423
--- /dev/null
+++ b/tools/dom/nnbd_src/KeyLocation.dart
@@ -0,0 +1,46 @@
+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * Defines the standard key locations returned by
+ * KeyboardEvent.getKeyLocation.
+ */
+abstract class KeyLocation {
+  /**
+   * The event key is not distinguished as the left or right version
+   * of the key, and did not originate from the numeric keypad (or did not
+   * originate with a virtual key corresponding to the numeric keypad).
+   */
+  static const int STANDARD = 0;
+
+  /**
+   * The event key is in the left key location.
+   */
+  static const int LEFT = 1;
+
+  /**
+   * The event key is in the right key location.
+   */
+  static const int RIGHT = 2;
+
+  /**
+   * The event key originated on the numeric keypad or with a virtual key
+   * corresponding to the numeric keypad.
+   */
+  static const int NUMPAD = 3;
+
+  /**
+   * The event key originated on a mobile device, either on a physical
+   * keypad or a virtual keyboard.
+   */
+  static const int MOBILE = 4;
+
+  /**
+   * The event key originated on a game controller or a joystick on a mobile
+   * device.
+   */
+  static const int JOYSTICK = 5;
+}
diff --git a/tools/dom/nnbd_src/KeyName.dart b/tools/dom/nnbd_src/KeyName.dart
new file mode 100644
index 0000000..094d57e
--- /dev/null
+++ b/tools/dom/nnbd_src/KeyName.dart
@@ -0,0 +1,494 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * Defines the standard keyboard identifier names for keys that are returned
+ * by KeyboardEvent.getKeyboardIdentifier when the key does not have a direct
+ * unicode mapping.
+ */
+abstract class _KeyName {
+  /** The Accept (Commit, OK) key */
+  static const String ACCEPT = "Accept";
+
+  /** The Add key */
+  static const String ADD = "Add";
+
+  /** The Again key */
+  static const String AGAIN = "Again";
+
+  /** The All Candidates key */
+  static const String ALL_CANDIDATES = "AllCandidates";
+
+  /** The Alphanumeric key */
+  static const String ALPHANUMERIC = "Alphanumeric";
+
+  /** The Alt (Menu) key */
+  static const String ALT = "Alt";
+
+  /** The Alt-Graph key */
+  static const String ALT_GRAPH = "AltGraph";
+
+  /** The Application key */
+  static const String APPS = "Apps";
+
+  /** The ATTN key */
+  static const String ATTN = "Attn";
+
+  /** The Browser Back key */
+  static const String BROWSER_BACK = "BrowserBack";
+
+  /** The Browser Favorites key */
+  static const String BROWSER_FAVORTIES = "BrowserFavorites";
+
+  /** The Browser Forward key */
+  static const String BROWSER_FORWARD = "BrowserForward";
+
+  /** The Browser Home key */
+  static const String BROWSER_NAME = "BrowserHome";
+
+  /** The Browser Refresh key */
+  static const String BROWSER_REFRESH = "BrowserRefresh";
+
+  /** The Browser Search key */
+  static const String BROWSER_SEARCH = "BrowserSearch";
+
+  /** The Browser Stop key */
+  static const String BROWSER_STOP = "BrowserStop";
+
+  /** The Camera key */
+  static const String CAMERA = "Camera";
+
+  /** The Caps Lock (Capital) key */
+  static const String CAPS_LOCK = "CapsLock";
+
+  /** The Clear key */
+  static const String CLEAR = "Clear";
+
+  /** The Code Input key */
+  static const String CODE_INPUT = "CodeInput";
+
+  /** The Compose key */
+  static const String COMPOSE = "Compose";
+
+  /** The Control (Ctrl) key */
+  static const String CONTROL = "Control";
+
+  /** The Crsel key */
+  static const String CRSEL = "Crsel";
+
+  /** The Convert key */
+  static const String CONVERT = "Convert";
+
+  /** The Copy key */
+  static const String COPY = "Copy";
+
+  /** The Cut key */
+  static const String CUT = "Cut";
+
+  /** The Decimal key */
+  static const String DECIMAL = "Decimal";
+
+  /** The Divide key */
+  static const String DIVIDE = "Divide";
+
+  /** The Down Arrow key */
+  static const String DOWN = "Down";
+
+  /** The diagonal Down-Left Arrow key */
+  static const String DOWN_LEFT = "DownLeft";
+
+  /** The diagonal Down-Right Arrow key */
+  static const String DOWN_RIGHT = "DownRight";
+
+  /** The Eject key */
+  static const String EJECT = "Eject";
+
+  /** The End key */
+  static const String END = "End";
+
+  /**
+   * The Enter key. Note: This key value must also be used for the Return
+   *  (Macintosh numpad) key
+   */
+  static const String ENTER = "Enter";
+
+  /** The Erase EOF key */
+  static const String ERASE_EOF = "EraseEof";
+
+  /** The Execute key */
+  static const String EXECUTE = "Execute";
+
+  /** The Exsel key */
+  static const String EXSEL = "Exsel";
+
+  /** The Function switch key */
+  static const String FN = "Fn";
+
+  /** The F1 key */
+  static const String F1 = "F1";
+
+  /** The F2 key */
+  static const String F2 = "F2";
+
+  /** The F3 key */
+  static const String F3 = "F3";
+
+  /** The F4 key */
+  static const String F4 = "F4";
+
+  /** The F5 key */
+  static const String F5 = "F5";
+
+  /** The F6 key */
+  static const String F6 = "F6";
+
+  /** The F7 key */
+  static const String F7 = "F7";
+
+  /** The F8 key */
+  static const String F8 = "F8";
+
+  /** The F9 key */
+  static const String F9 = "F9";
+
+  /** The F10 key */
+  static const String F10 = "F10";
+
+  /** The F11 key */
+  static const String F11 = "F11";
+
+  /** The F12 key */
+  static const String F12 = "F12";
+
+  /** The F13 key */
+  static const String F13 = "F13";
+
+  /** The F14 key */
+  static const String F14 = "F14";
+
+  /** The F15 key */
+  static const String F15 = "F15";
+
+  /** The F16 key */
+  static const String F16 = "F16";
+
+  /** The F17 key */
+  static const String F17 = "F17";
+
+  /** The F18 key */
+  static const String F18 = "F18";
+
+  /** The F19 key */
+  static const String F19 = "F19";
+
+  /** The F20 key */
+  static const String F20 = "F20";
+
+  /** The F21 key */
+  static const String F21 = "F21";
+
+  /** The F22 key */
+  static const String F22 = "F22";
+
+  /** The F23 key */
+  static const String F23 = "F23";
+
+  /** The F24 key */
+  static const String F24 = "F24";
+
+  /** The Final Mode (Final) key used on some asian keyboards */
+  static const String FINAL_MODE = "FinalMode";
+
+  /** The Find key */
+  static const String FIND = "Find";
+
+  /** The Full-Width Characters key */
+  static const String FULL_WIDTH = "FullWidth";
+
+  /** The Half-Width Characters key */
+  static const String HALF_WIDTH = "HalfWidth";
+
+  /** The Hangul (Korean characters) Mode key */
+  static const String HANGUL_MODE = "HangulMode";
+
+  /** The Hanja (Korean characters) Mode key */
+  static const String HANJA_MODE = "HanjaMode";
+
+  /** The Help key */
+  static const String HELP = "Help";
+
+  /** The Hiragana (Japanese Kana characters) key */
+  static const String HIRAGANA = "Hiragana";
+
+  /** The Home key */
+  static const String HOME = "Home";
+
+  /** The Insert (Ins) key */
+  static const String INSERT = "Insert";
+
+  /** The Japanese-Hiragana key */
+  static const String JAPANESE_HIRAGANA = "JapaneseHiragana";
+
+  /** The Japanese-Katakana key */
+  static const String JAPANESE_KATAKANA = "JapaneseKatakana";
+
+  /** The Japanese-Romaji key */
+  static const String JAPANESE_ROMAJI = "JapaneseRomaji";
+
+  /** The Junja Mode key */
+  static const String JUNJA_MODE = "JunjaMode";
+
+  /** The Kana Mode (Kana Lock) key */
+  static const String KANA_MODE = "KanaMode";
+
+  /**
+   * The Kanji (Japanese name for ideographic characters of Chinese origin)
+   * Mode key
+   */
+  static const String KANJI_MODE = "KanjiMode";
+
+  /** The Katakana (Japanese Kana characters) key */
+  static const String KATAKANA = "Katakana";
+
+  /** The Start Application One key */
+  static const String LAUNCH_APPLICATION_1 = "LaunchApplication1";
+
+  /** The Start Application Two key */
+  static const String LAUNCH_APPLICATION_2 = "LaunchApplication2";
+
+  /** The Start Mail key */
+  static const String LAUNCH_MAIL = "LaunchMail";
+
+  /** The Left Arrow key */
+  static const String LEFT = "Left";
+
+  /** The Menu key */
+  static const String MENU = "Menu";
+
+  /**
+   * The Meta key. Note: This key value shall be also used for the Apple
+   * Command key
+   */
+  static const String META = "Meta";
+
+  /** The Media Next Track key */
+  static const String MEDIA_NEXT_TRACK = "MediaNextTrack";
+
+  /** The Media Play Pause key */
+  static const String MEDIA_PAUSE_PLAY = "MediaPlayPause";
+
+  /** The Media Previous Track key */
+  static const String MEDIA_PREVIOUS_TRACK = "MediaPreviousTrack";
+
+  /** The Media Stop key */
+  static const String MEDIA_STOP = "MediaStop";
+
+  /** The Mode Change key */
+  static const String MODE_CHANGE = "ModeChange";
+
+  /** The Next Candidate function key */
+  static const String NEXT_CANDIDATE = "NextCandidate";
+
+  /** The Nonconvert (Don't Convert) key */
+  static const String NON_CONVERT = "Nonconvert";
+
+  /** The Number Lock key */
+  static const String NUM_LOCK = "NumLock";
+
+  /** The Page Down (Next) key */
+  static const String PAGE_DOWN = "PageDown";
+
+  /** The Page Up key */
+  static const String PAGE_UP = "PageUp";
+
+  /** The Paste key */
+  static const String PASTE = "Paste";
+
+  /** The Pause key */
+  static const String PAUSE = "Pause";
+
+  /** The Play key */
+  static const String PLAY = "Play";
+
+  /**
+   * The Power key. Note: Some devices may not expose this key to the
+   * operating environment
+   */
+  static const String POWER = "Power";
+
+  /** The Previous Candidate function key */
+  static const String PREVIOUS_CANDIDATE = "PreviousCandidate";
+
+  /** The Print Screen (PrintScrn, SnapShot) key */
+  static const String PRINT_SCREEN = "PrintScreen";
+
+  /** The Process key */
+  static const String PROCESS = "Process";
+
+  /** The Props key */
+  static const String PROPS = "Props";
+
+  /** The Right Arrow key */
+  static const String RIGHT = "Right";
+
+  /** The Roman Characters function key */
+  static const String ROMAN_CHARACTERS = "RomanCharacters";
+
+  /** The Scroll Lock key */
+  static const String SCROLL = "Scroll";
+
+  /** The Select key */
+  static const String SELECT = "Select";
+
+  /** The Select Media key */
+  static const String SELECT_MEDIA = "SelectMedia";
+
+  /** The Separator key */
+  static const String SEPARATOR = "Separator";
+
+  /** The Shift key */
+  static const String SHIFT = "Shift";
+
+  /** The Soft1 key */
+  static const String SOFT_1 = "Soft1";
+
+  /** The Soft2 key */
+  static const String SOFT_2 = "Soft2";
+
+  /** The Soft3 key */
+  static const String SOFT_3 = "Soft3";
+
+  /** The Soft4 key */
+  static const String SOFT_4 = "Soft4";
+
+  /** The Stop key */
+  static const String STOP = "Stop";
+
+  /** The Subtract key */
+  static const String SUBTRACT = "Subtract";
+
+  /** The Symbol Lock key */
+  static const String SYMBOL_LOCK = "SymbolLock";
+
+  /** The Up Arrow key */
+  static const String UP = "Up";
+
+  /** The diagonal Up-Left Arrow key */
+  static const String UP_LEFT = "UpLeft";
+
+  /** The diagonal Up-Right Arrow key */
+  static const String UP_RIGHT = "UpRight";
+
+  /** The Undo key */
+  static const String UNDO = "Undo";
+
+  /** The Volume Down key */
+  static const String VOLUME_DOWN = "VolumeDown";
+
+  /** The Volume Mute key */
+  static const String VOLUMN_MUTE = "VolumeMute";
+
+  /** The Volume Up key */
+  static const String VOLUMN_UP = "VolumeUp";
+
+  /** The Windows Logo key */
+  static const String WIN = "Win";
+
+  /** The Zoom key */
+  static const String ZOOM = "Zoom";
+
+  /**
+   * The Backspace (Back) key. Note: This key value shall be also used for the
+   * key labeled 'delete' MacOS keyboards when not modified by the 'Fn' key
+   */
+  static const String BACKSPACE = "Backspace";
+
+  /** The Horizontal Tabulation (Tab) key */
+  static const String TAB = "Tab";
+
+  /** The Cancel key */
+  static const String CANCEL = "Cancel";
+
+  /** The Escape (Esc) key */
+  static const String ESC = "Esc";
+
+  /** The Space (Spacebar) key:   */
+  static const String SPACEBAR = "Spacebar";
+
+  /**
+   * The Delete (Del) Key. Note: This key value shall be also used for the key
+   * labeled 'delete' MacOS keyboards when modified by the 'Fn' key
+   */
+  static const String DEL = "Del";
+
+  /** The Combining Grave Accent (Greek Varia, Dead Grave) key */
+  static const String DEAD_GRAVE = "DeadGrave";
+
+  /**
+   * The Combining Acute Accent (Stress Mark, Greek Oxia, Tonos, Dead Eacute)
+   * key
+   */
+  static const String DEAD_EACUTE = "DeadEacute";
+
+  /** The Combining Circumflex Accent (Hat, Dead Circumflex) key */
+  static const String DEAD_CIRCUMFLEX = "DeadCircumflex";
+
+  /** The Combining Tilde (Dead Tilde) key */
+  static const String DEAD_TILDE = "DeadTilde";
+
+  /** The Combining Macron (Long, Dead Macron) key */
+  static const String DEAD_MACRON = "DeadMacron";
+
+  /** The Combining Breve (Short, Dead Breve) key */
+  static const String DEAD_BREVE = "DeadBreve";
+
+  /** The Combining Dot Above (Derivative, Dead Above Dot) key */
+  static const String DEAD_ABOVE_DOT = "DeadAboveDot";
+
+  /**
+   * The Combining Diaeresis (Double Dot Abode, Umlaut, Greek Dialytika,
+   * Double Derivative, Dead Diaeresis) key
+   */
+  static const String DEAD_UMLAUT = "DeadUmlaut";
+
+  /** The Combining Ring Above (Dead Above Ring) key */
+  static const String DEAD_ABOVE_RING = "DeadAboveRing";
+
+  /** The Combining Double Acute Accent (Dead Doubleacute) key */
+  static const String DEAD_DOUBLEACUTE = "DeadDoubleacute";
+
+  /** The Combining Caron (Hacek, V Above, Dead Caron) key */
+  static const String DEAD_CARON = "DeadCaron";
+
+  /** The Combining Cedilla (Dead Cedilla) key */
+  static const String DEAD_CEDILLA = "DeadCedilla";
+
+  /** The Combining Ogonek (Nasal Hook, Dead Ogonek) key */
+  static const String DEAD_OGONEK = "DeadOgonek";
+
+  /**
+   * The Combining Greek Ypogegrammeni (Greek Non-Spacing Iota Below, Iota
+   * Subscript, Dead Iota) key
+   */
+  static const String DEAD_IOTA = "DeadIota";
+
+  /**
+   * The Combining Katakana-Hiragana Voiced Sound Mark (Dead Voiced Sound) key
+   */
+  static const String DEAD_VOICED_SOUND = "DeadVoicedSound";
+
+  /**
+   * The Combining Katakana-Hiragana Semi-Voiced Sound Mark (Dead Semivoiced
+   * Sound) key
+   */
+  static const String DEC_SEMIVOICED_SOUND = "DeadSemivoicedSound";
+
+  /**
+   * Key value used when an implementation is unable to identify another key
+   * value, due to either hardware, platform, or software constraints
+   */
+  static const String UNIDENTIFIED = "Unidentified";
+}
diff --git a/tools/dom/nnbd_src/KeyboardEventStream.dart b/tools/dom/nnbd_src/KeyboardEventStream.dart
new file mode 100644
index 0000000..48f7a68
--- /dev/null
+++ b/tools/dom/nnbd_src/KeyboardEventStream.dart
@@ -0,0 +1,394 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * Internal class that does the actual calculations to determine keyCode and
+ * charCode for keydown, keypress, and keyup events for all browsers.
+ */
+class _KeyboardEventHandler extends EventStreamProvider<KeyEvent> {
+  // This code inspired by Closure's KeyHandling library.
+  // https://github.com/google/closure-library/blob/master/closure/goog/events/keyhandler.js
+
+  /**
+   * The set of keys that have been pressed down without seeing their
+   * corresponding keyup event.
+   */
+  final List<KeyEvent> _keyDownList = <KeyEvent>[];
+
+  /** The type of KeyEvent we are tracking (keyup, keydown, keypress). */
+  final String _type;
+
+  /** The element we are watching for events to happen on. */
+  final EventTarget _target;
+
+  // The distance to shift from upper case alphabet Roman letters to lower case.
+  static final int _ROMAN_ALPHABET_OFFSET = "a".codeUnits[0] - "A".codeUnits[0];
+
+  /** Custom Stream (Controller) to produce KeyEvents for the stream. */
+  _CustomKeyEventStreamImpl _stream;
+
+  static const _EVENT_TYPE = 'KeyEvent';
+
+  /**
+   * An enumeration of key identifiers currently part of the W3C draft for DOM3
+   * and their mappings to keyCodes.
+   * https://www.w3.org/TR/2003/NOTE-DOM-Level-3-Events-20031107/keyset.html#KeySet-Set
+   */
+  static const Map<String, int> _keyIdentifier = const {
+    'Up': KeyCode.UP,
+    'Down': KeyCode.DOWN,
+    'Left': KeyCode.LEFT,
+    'Right': KeyCode.RIGHT,
+    'Enter': KeyCode.ENTER,
+    'F1': KeyCode.F1,
+    'F2': KeyCode.F2,
+    'F3': KeyCode.F3,
+    'F4': KeyCode.F4,
+    'F5': KeyCode.F5,
+    'F6': KeyCode.F6,
+    'F7': KeyCode.F7,
+    'F8': KeyCode.F8,
+    'F9': KeyCode.F9,
+    'F10': KeyCode.F10,
+    'F11': KeyCode.F11,
+    'F12': KeyCode.F12,
+    'U+007F': KeyCode.DELETE,
+    'Home': KeyCode.HOME,
+    'End': KeyCode.END,
+    'PageUp': KeyCode.PAGE_UP,
+    'PageDown': KeyCode.PAGE_DOWN,
+    'Insert': KeyCode.INSERT
+  };
+
+  /** Return a stream for KeyEvents for the specified target. */
+  // Note: this actually functions like a factory constructor.
+  CustomStream<KeyEvent> forTarget(EventTarget e, {bool useCapture: false}) {
+    var handler =
+        new _KeyboardEventHandler.initializeAllEventListeners(_type, e);
+    return handler._stream;
+  }
+
+  /**
+   * General constructor, performs basic initialization for our improved
+   * KeyboardEvent controller.
+   */
+  _KeyboardEventHandler(this._type)
+      : _stream = new _CustomKeyEventStreamImpl('event'),
+        _target = null,
+        super(_EVENT_TYPE);
+
+  /**
+   * Hook up all event listeners under the covers so we can estimate keycodes
+   * and charcodes when they are not provided.
+   */
+  _KeyboardEventHandler.initializeAllEventListeners(this._type, this._target)
+      : super(_EVENT_TYPE) {
+    Element.keyDownEvent
+        .forTarget(_target, useCapture: true)
+        .listen(processKeyDown);
+    Element.keyPressEvent
+        .forTarget(_target, useCapture: true)
+        .listen(processKeyPress);
+    Element.keyUpEvent
+        .forTarget(_target, useCapture: true)
+        .listen(processKeyUp);
+    _stream = new _CustomKeyEventStreamImpl(_type);
+  }
+
+  /** Determine if caps lock is one of the currently depressed keys. */
+  bool get _capsLockOn =>
+      _keyDownList.any((var element) => element.keyCode == KeyCode.CAPS_LOCK);
+
+  /**
+   * Given the previously recorded keydown key codes, see if we can determine
+   * the keycode of this keypress [event]. (Generally browsers only provide
+   * charCode information for keypress events, but with a little
+   * reverse-engineering, we can also determine the keyCode.) Returns
+   * KeyCode.UNKNOWN if the keycode could not be determined.
+   */
+  int _determineKeyCodeForKeypress(KeyboardEvent event) {
+    // Note: This function is a work in progress. We'll expand this function
+    // once we get more information about other keyboards.
+    for (var prevEvent in _keyDownList) {
+      if (prevEvent._shadowCharCode == event.charCode) {
+        return prevEvent.keyCode;
+      }
+      if ((event.shiftKey || _capsLockOn) &&
+          event.charCode >= "A".codeUnits[0] &&
+          event.charCode <= "Z".codeUnits[0] &&
+          event.charCode + _ROMAN_ALPHABET_OFFSET ==
+              prevEvent._shadowCharCode) {
+        return prevEvent.keyCode;
+      }
+    }
+    return KeyCode.UNKNOWN;
+  }
+
+  /**
+   * Given the character code returned from a keyDown [event], try to ascertain
+   * and return the corresponding charCode for the character that was pressed.
+   * This information is not shown to the user, but used to help polyfill
+   * keypress events.
+   */
+  int _findCharCodeKeyDown(KeyboardEvent event) {
+    if (event.location == 3) {
+      // Numpad keys.
+      switch (event.keyCode) {
+        case KeyCode.NUM_ZERO:
+          // Even though this function returns _charCodes_, for some cases the
+          // KeyCode == the charCode we want, in which case we use the keycode
+          // constant for readability.
+          return KeyCode.ZERO;
+        case KeyCode.NUM_ONE:
+          return KeyCode.ONE;
+        case KeyCode.NUM_TWO:
+          return KeyCode.TWO;
+        case KeyCode.NUM_THREE:
+          return KeyCode.THREE;
+        case KeyCode.NUM_FOUR:
+          return KeyCode.FOUR;
+        case KeyCode.NUM_FIVE:
+          return KeyCode.FIVE;
+        case KeyCode.NUM_SIX:
+          return KeyCode.SIX;
+        case KeyCode.NUM_SEVEN:
+          return KeyCode.SEVEN;
+        case KeyCode.NUM_EIGHT:
+          return KeyCode.EIGHT;
+        case KeyCode.NUM_NINE:
+          return KeyCode.NINE;
+        case KeyCode.NUM_MULTIPLY:
+          return 42; // Char code for *
+        case KeyCode.NUM_PLUS:
+          return 43; // +
+        case KeyCode.NUM_MINUS:
+          return 45; // -
+        case KeyCode.NUM_PERIOD:
+          return 46; // .
+        case KeyCode.NUM_DIVISION:
+          return 47; // /
+      }
+    } else if (event.keyCode >= 65 && event.keyCode <= 90) {
+      // Set the "char code" for key down as the lower case letter. Again, this
+      // will not show up for the user, but will be helpful in estimating
+      // keyCode locations and other information during the keyPress event.
+      return event.keyCode + _ROMAN_ALPHABET_OFFSET;
+    }
+    switch (event.keyCode) {
+      case KeyCode.SEMICOLON:
+        return KeyCode.FF_SEMICOLON;
+      case KeyCode.EQUALS:
+        return KeyCode.FF_EQUALS;
+      case KeyCode.COMMA:
+        return 44; // Ascii value for ,
+      case KeyCode.DASH:
+        return 45; // -
+      case KeyCode.PERIOD:
+        return 46; // .
+      case KeyCode.SLASH:
+        return 47; // /
+      case KeyCode.APOSTROPHE:
+        return 96; // `
+      case KeyCode.OPEN_SQUARE_BRACKET:
+        return 91; // [
+      case KeyCode.BACKSLASH:
+        return 92; // \
+      case KeyCode.CLOSE_SQUARE_BRACKET:
+        return 93; // ]
+      case KeyCode.SINGLE_QUOTE:
+        return 39; // '
+    }
+    return event.keyCode;
+  }
+
+  /**
+   * Returns true if the key fires a keypress event in the current browser.
+   */
+  bool _firesKeyPressEvent(KeyEvent event) {
+    if (!Device.isIE && !Device.isWebKit) {
+      return true;
+    }
+
+    if (Device.userAgent.contains('Mac') && event.altKey) {
+      return KeyCode.isCharacterKey(event.keyCode);
+    }
+
+    // Alt but not AltGr which is represented as Alt+Ctrl.
+    if (event.altKey && !event.ctrlKey) {
+      return false;
+    }
+
+    // Saves Ctrl or Alt + key for IE and WebKit, which won't fire keypress.
+    if (!event.shiftKey &&
+        (_keyDownList.last.keyCode == KeyCode.CTRL ||
+            _keyDownList.last.keyCode == KeyCode.ALT ||
+            Device.userAgent.contains('Mac') &&
+                _keyDownList.last.keyCode == KeyCode.META)) {
+      return false;
+    }
+
+    // Some keys with Ctrl/Shift do not issue keypress in WebKit.
+    if (Device.isWebKit &&
+        event.ctrlKey &&
+        event.shiftKey &&
+        (event.keyCode == KeyCode.BACKSLASH ||
+            event.keyCode == KeyCode.OPEN_SQUARE_BRACKET ||
+            event.keyCode == KeyCode.CLOSE_SQUARE_BRACKET ||
+            event.keyCode == KeyCode.TILDE ||
+            event.keyCode == KeyCode.SEMICOLON ||
+            event.keyCode == KeyCode.DASH ||
+            event.keyCode == KeyCode.EQUALS ||
+            event.keyCode == KeyCode.COMMA ||
+            event.keyCode == KeyCode.PERIOD ||
+            event.keyCode == KeyCode.SLASH ||
+            event.keyCode == KeyCode.APOSTROPHE ||
+            event.keyCode == KeyCode.SINGLE_QUOTE)) {
+      return false;
+    }
+
+    switch (event.keyCode) {
+      case KeyCode.ENTER:
+        // IE9 does not fire keypress on ENTER.
+        return !Device.isIE;
+      case KeyCode.ESC:
+        return !Device.isWebKit;
+    }
+
+    return KeyCode.isCharacterKey(event.keyCode);
+  }
+
+  /**
+   * Normalize the keycodes to the IE KeyCodes (this is what Chrome, IE, and
+   * Opera all use).
+   */
+  int _normalizeKeyCodes(KeyboardEvent event) {
+    // Note: This may change once we get input about non-US keyboards.
+    if (Device.isFirefox) {
+      switch (event.keyCode) {
+        case KeyCode.FF_EQUALS:
+          return KeyCode.EQUALS;
+        case KeyCode.FF_SEMICOLON:
+          return KeyCode.SEMICOLON;
+        case KeyCode.MAC_FF_META:
+          return KeyCode.META;
+        case KeyCode.WIN_KEY_FF_LINUX:
+          return KeyCode.WIN_KEY;
+      }
+    }
+    return event.keyCode;
+  }
+
+  /** Handle keydown events. */
+  void processKeyDown(KeyboardEvent e) {
+    // Ctrl-Tab and Alt-Tab can cause the focus to be moved to another window
+    // before we've caught a key-up event.  If the last-key was one of these
+    // we reset the state.
+    if (_keyDownList.length > 0 &&
+        (_keyDownList.last.keyCode == KeyCode.CTRL && !e.ctrlKey ||
+            _keyDownList.last.keyCode == KeyCode.ALT && !e.altKey ||
+            Device.userAgent.contains('Mac') &&
+                _keyDownList.last.keyCode == KeyCode.META &&
+                !e.metaKey)) {
+      _keyDownList.clear();
+    }
+
+    var event = new KeyEvent.wrap(e);
+    event._shadowKeyCode = _normalizeKeyCodes(event);
+    // Technically a "keydown" event doesn't have a charCode. This is
+    // calculated nonetheless to provide us with more information in giving
+    // as much information as possible on keypress about keycode and also
+    // charCode.
+    event._shadowCharCode = _findCharCodeKeyDown(event);
+    if (_keyDownList.length > 0 &&
+        event.keyCode != _keyDownList.last.keyCode &&
+        !_firesKeyPressEvent(event)) {
+      // Some browsers have quirks not firing keypress events where all other
+      // browsers do. This makes them more consistent.
+      processKeyPress(e);
+    }
+    _keyDownList.add(event);
+    _stream.add(event);
+  }
+
+  /** Handle keypress events. */
+  void processKeyPress(KeyboardEvent event) {
+    var e = new KeyEvent.wrap(event);
+    // IE reports the character code in the keyCode field for keypress events.
+    // There are two exceptions however, Enter and Escape.
+    if (Device.isIE) {
+      if (e.keyCode == KeyCode.ENTER || e.keyCode == KeyCode.ESC) {
+        e._shadowCharCode = 0;
+      } else {
+        e._shadowCharCode = e.keyCode;
+      }
+    } else if (Device.isOpera) {
+      // Opera reports the character code in the keyCode field.
+      e._shadowCharCode = KeyCode.isCharacterKey(e.keyCode) ? e.keyCode : 0;
+    }
+    // Now we guesstimate about what the keycode is that was actually
+    // pressed, given previous keydown information.
+    e._shadowKeyCode = _determineKeyCodeForKeypress(e);
+
+    // Correct the key value for certain browser-specific quirks.
+    if (e._shadowKeyIdentifier != null &&
+        _keyIdentifier.containsKey(e._shadowKeyIdentifier)) {
+      // This is needed for Safari Windows because it currently doesn't give a
+      // keyCode/which for non printable keys.
+      e._shadowKeyCode = _keyIdentifier[e._shadowKeyIdentifier];
+    }
+    e._shadowAltKey = _keyDownList.any((var element) => element.altKey);
+    _stream.add(e);
+  }
+
+  /** Handle keyup events. */
+  void processKeyUp(KeyboardEvent event) {
+    var e = new KeyEvent.wrap(event);
+    KeyboardEvent toRemove = null;
+    for (var key in _keyDownList) {
+      if (key.keyCode == e.keyCode) {
+        toRemove = key;
+      }
+    }
+    if (toRemove != null) {
+      _keyDownList.removeWhere((element) => element == toRemove);
+    } else if (_keyDownList.length > 0) {
+      // This happens when we've reached some international keyboard case we
+      // haven't accounted for or we haven't correctly eliminated all browser
+      // inconsistencies. Filing bugs on when this is reached is welcome!
+      _keyDownList.removeLast();
+    }
+    _stream.add(e);
+  }
+}
+
+/**
+ * Records KeyboardEvents that occur on a particular element, and provides a
+ * stream of outgoing KeyEvents with cross-browser consistent keyCode and
+ * charCode values despite the fact that a multitude of browsers that have
+ * varying keyboard default behavior.
+ *
+ * Example usage:
+ *
+ *     KeyboardEventStream.onKeyDown(document.body).listen(
+ *         keydownHandlerTest);
+ *
+ * This class is very much a work in progress, and we'd love to get information
+ * on how we can make this class work with as many international keyboards as
+ * possible. Bugs welcome!
+ */
+class KeyboardEventStream {
+  /** Named constructor to produce a stream for onKeyPress events. */
+  static CustomStream<KeyEvent> onKeyPress(EventTarget target) =>
+      new _KeyboardEventHandler('keypress').forTarget(target);
+
+  /** Named constructor to produce a stream for onKeyUp events. */
+  static CustomStream<KeyEvent> onKeyUp(EventTarget target) =>
+      new _KeyboardEventHandler('keyup').forTarget(target);
+
+  /** Named constructor to produce a stream for onKeyDown events. */
+  static CustomStream<KeyEvent> onKeyDown(EventTarget target) =>
+      new _KeyboardEventHandler('keydown').forTarget(target);
+}
diff --git a/tools/dom/nnbd_src/NodeValidatorBuilder.dart b/tools/dom/nnbd_src/NodeValidatorBuilder.dart
new file mode 100644
index 0000000..0c8216f
--- /dev/null
+++ b/tools/dom/nnbd_src/NodeValidatorBuilder.dart
@@ -0,0 +1,454 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.dom.html;
+
+/**
+ * Class which helps construct standard node validation policies.
+ *
+ * By default this will not accept anything, but the 'allow*' functions can be
+ * used to expand what types of elements or attributes are allowed.
+ *
+ * All allow functions are additive- elements will be accepted if they are
+ * accepted by any specific rule.
+ *
+ * It is important to remember that sanitization is not just intended to prevent
+ * cross-site scripting attacks, but also to prevent information from being
+ * displayed in unexpected ways. For example something displaying basic
+ * formatted text may not expect `<video>` tags to appear. In this case an
+ * empty NodeValidatorBuilder with just [allowTextElements] might be
+ * appropriate.
+ */
+class NodeValidatorBuilder implements NodeValidator {
+  final List<NodeValidator> _validators = <NodeValidator>[];
+
+  NodeValidatorBuilder() {}
+
+  /**
+   * Creates a new NodeValidatorBuilder which accepts common constructs.
+   *
+   * By default this will accept HTML5 elements and attributes with the default
+   * [UriPolicy] and templating elements.
+   *
+   * Notable syntax which is filtered:
+   *
+   * * Only known-good HTML5 elements and attributes are allowed.
+   * * All URLs must be same-origin, use [allowNavigation] and [allowImages] to
+   * specify additional URI policies.
+   * * Inline-styles are not allowed.
+   * * Custom element tags are disallowed, use [allowCustomElement].
+   * * Custom tags extensions are disallowed, use [allowTagExtension].
+   * * SVG Elements are not allowed, use [allowSvg].
+   *
+   * For scenarios where the HTML should only contain formatted text
+   * [allowTextElements] is more appropriate.
+   *
+   * Use [allowSvg] to allow SVG elements.
+   */
+  NodeValidatorBuilder.common() {
+    allowHtml5();
+    allowTemplating();
+  }
+
+  /**
+   * Allows navigation elements- Form and Anchor tags, along with common
+   * attributes.
+   *
+   * The UriPolicy can be used to restrict the locations the navigation elements
+   * are allowed to direct to. By default this will use the default [UriPolicy].
+   */
+  void allowNavigation([UriPolicy uriPolicy]) {
+    if (uriPolicy == null) {
+      uriPolicy = new UriPolicy();
+    }
+    add(new _SimpleNodeValidator.allowNavigation(uriPolicy));
+  }
+
+  /**
+   * Allows image elements.
+   *
+   * The UriPolicy can be used to restrict the locations the images may be
+   * loaded from. By default this will use the default [UriPolicy].
+   */
+  void allowImages([UriPolicy uriPolicy]) {
+    if (uriPolicy == null) {
+      uriPolicy = new UriPolicy();
+    }
+    add(new _SimpleNodeValidator.allowImages(uriPolicy));
+  }
+
+  /**
+   * Allow basic text elements.
+   *
+   * This allows a subset of HTML5 elements, specifically just these tags and
+   * no attributes.
+   *
+   * * B
+   * * BLOCKQUOTE
+   * * BR
+   * * EM
+   * * H1
+   * * H2
+   * * H3
+   * * H4
+   * * H5
+   * * H6
+   * * HR
+   * * I
+   * * LI
+   * * OL
+   * * P
+   * * SPAN
+   * * UL
+   */
+  void allowTextElements() {
+    add(new _SimpleNodeValidator.allowTextElements());
+  }
+
+  /**
+   * Allow inline styles on elements.
+   *
+   * If [tagName] is not specified then this allows inline styles on all
+   * elements. Otherwise tagName limits the styles to the specified elements.
+   */
+  void allowInlineStyles({String tagName}) {
+    if (tagName == null) {
+      tagName = '*';
+    } else {
+      tagName = tagName.toUpperCase();
+    }
+    add(new _SimpleNodeValidator(null, allowedAttributes: ['$tagName::style']));
+  }
+
+  /**
+   * Allow common safe HTML5 elements and attributes.
+   *
+   * This list is based off of the Caja whitelists at:
+   * https://code.google.com/p/google-caja/wiki/CajaWhitelists.
+   *
+   * Common things which are not allowed are script elements, style attributes
+   * and any script handlers.
+   */
+  void allowHtml5({UriPolicy uriPolicy}) {
+    add(new _Html5NodeValidator(uriPolicy: uriPolicy));
+  }
+
+  /**
+   * Allow SVG elements and attributes except for known bad ones.
+   */
+  void allowSvg() {
+    add(new _SvgNodeValidator());
+  }
+
+  /**
+   * Allow custom elements with the specified tag name and specified attributes.
+   *
+   * This will allow the elements as custom tags (such as <x-foo></x-foo>),
+   * but will not allow tag extensions. Use [allowTagExtension] to allow
+   * tag extensions.
+   */
+  void allowCustomElement(String tagName,
+      {UriPolicy uriPolicy,
+      Iterable<String>? attributes,
+      Iterable<String> uriAttributes}) {
+    var tagNameUpper = tagName.toUpperCase();
+    var attrs = attributes
+        ?.map<String>((name) => '$tagNameUpper::${name.toLowerCase()}');
+    var uriAttrs = uriAttributes
+        ?.map<String>((name) => '$tagNameUpper::${name.toLowerCase()}');
+    if (uriPolicy == null) {
+      uriPolicy = new UriPolicy();
+    }
+
+    add(new _CustomElementNodeValidator(
+        uriPolicy, [tagNameUpper], attrs, uriAttrs, false, true));
+  }
+
+  /**
+   * Allow custom tag extensions with the specified type name and specified
+   * attributes.
+   *
+   * This will allow tag extensions (such as <div is="x-foo"></div>),
+   * but will not allow custom tags. Use [allowCustomElement] to allow
+   * custom tags.
+   */
+  void allowTagExtension(String tagName, String baseName,
+      {UriPolicy uriPolicy,
+      Iterable<String> attributes,
+      Iterable<String> uriAttributes}) {
+    var baseNameUpper = baseName.toUpperCase();
+    var tagNameUpper = tagName.toUpperCase();
+    var attrs = attributes
+        ?.map<String>((name) => '$baseNameUpper::${name.toLowerCase()}');
+    var uriAttrs = uriAttributes
+        ?.map<String>((name) => '$baseNameUpper::${name.toLowerCase()}');
+    if (uriPolicy == null) {
+      uriPolicy = new UriPolicy();
+    }
+
+    add(new _CustomElementNodeValidator(uriPolicy,
+        [tagNameUpper, baseNameUpper], attrs, uriAttrs, true, false));
+  }
+
+  void allowElement(String tagName,
+      {UriPolicy uriPolicy,
+      Iterable<String> attributes,
+      Iterable<String> uriAttributes}) {
+    allowCustomElement(tagName,
+        uriPolicy: uriPolicy,
+        attributes: attributes,
+        uriAttributes: uriAttributes);
+  }
+
+  /**
+   * Allow templating elements (such as <template> and template-related
+   * attributes.
+   *
+   * This still requires other validators to allow regular attributes to be
+   * bound (such as [allowHtml5]).
+   */
+  void allowTemplating() {
+    add(new _TemplatingNodeValidator());
+  }
+
+  /**
+   * Add an additional validator to the current list of validators.
+   *
+   * Elements and attributes will be accepted if they are accepted by any
+   * validators.
+   */
+  void add(NodeValidator validator) {
+    _validators.add(validator);
+  }
+
+  bool allowsElement(Element element) {
+    return _validators.any((v) => v.allowsElement(element));
+  }
+
+  bool allowsAttribute(Element element, String attributeName, String value) {
+    return _validators
+        .any((v) => v.allowsAttribute(element, attributeName, value));
+  }
+}
+
+class _SimpleNodeValidator implements NodeValidator {
+  final Set<String> allowedElements = new Set<String>();
+  final Set<String> allowedAttributes = new Set<String>();
+  final Set<String> allowedUriAttributes = new Set<String>();
+  final UriPolicy uriPolicy;
+
+  factory _SimpleNodeValidator.allowNavigation(UriPolicy uriPolicy) {
+    return new _SimpleNodeValidator(uriPolicy, allowedElements: const [
+      'A',
+      'FORM'
+    ], allowedAttributes: const [
+      'A::accesskey',
+      'A::coords',
+      'A::hreflang',
+      'A::name',
+      'A::shape',
+      'A::tabindex',
+      'A::target',
+      'A::type',
+      'FORM::accept',
+      'FORM::autocomplete',
+      'FORM::enctype',
+      'FORM::method',
+      'FORM::name',
+      'FORM::novalidate',
+      'FORM::target',
+    ], allowedUriAttributes: const [
+      'A::href',
+      'FORM::action',
+    ]);
+  }
+
+  factory _SimpleNodeValidator.allowImages(UriPolicy uriPolicy) {
+    return new _SimpleNodeValidator(uriPolicy, allowedElements: const [
+      'IMG'
+    ], allowedAttributes: const [
+      'IMG::align',
+      'IMG::alt',
+      'IMG::border',
+      'IMG::height',
+      'IMG::hspace',
+      'IMG::ismap',
+      'IMG::name',
+      'IMG::usemap',
+      'IMG::vspace',
+      'IMG::width',
+    ], allowedUriAttributes: const [
+      'IMG::src',
+    ]);
+  }
+
+  factory _SimpleNodeValidator.allowTextElements() {
+    return new _SimpleNodeValidator(null, allowedElements: const [
+      'B',
+      'BLOCKQUOTE',
+      'BR',
+      'EM',
+      'H1',
+      'H2',
+      'H3',
+      'H4',
+      'H5',
+      'H6',
+      'HR',
+      'I',
+      'LI',
+      'OL',
+      'P',
+      'SPAN',
+      'UL',
+    ]);
+  }
+
+  /**
+   * Elements must be uppercased tag names. For example `'IMG'`.
+   * Attributes must be uppercased tag name followed by :: followed by
+   * lowercase attribute name. For example `'IMG:src'`.
+   */
+  _SimpleNodeValidator(this.uriPolicy,
+      {Iterable<String> allowedElements,
+      Iterable<String> allowedAttributes,
+      Iterable<String> allowedUriAttributes}) {
+    this.allowedElements.addAll(allowedElements ?? const []);
+    allowedAttributes = allowedAttributes ?? const [];
+    allowedUriAttributes = allowedUriAttributes ?? const [];
+    var legalAttributes = allowedAttributes
+        .where((x) => !_Html5NodeValidator._uriAttributes.contains(x));
+    var extraUriAttributes = allowedAttributes
+        .where((x) => _Html5NodeValidator._uriAttributes.contains(x));
+    this.allowedAttributes.addAll(legalAttributes);
+    this.allowedUriAttributes.addAll(allowedUriAttributes);
+    this.allowedUriAttributes.addAll(extraUriAttributes);
+  }
+
+  bool allowsElement(Element element) {
+    return allowedElements.contains(Element._safeTagName(element));
+  }
+
+  bool allowsAttribute(Element element, String attributeName, String value) {
+    var tagName = Element._safeTagName(element);
+    if (allowedUriAttributes.contains('$tagName::$attributeName')) {
+      return uriPolicy.allowsUri(value);
+    } else if (allowedUriAttributes.contains('*::$attributeName')) {
+      return uriPolicy.allowsUri(value);
+    } else if (allowedAttributes.contains('$tagName::$attributeName')) {
+      return true;
+    } else if (allowedAttributes.contains('*::$attributeName')) {
+      return true;
+    } else if (allowedAttributes.contains('$tagName::*')) {
+      return true;
+    } else if (allowedAttributes.contains('*::*')) {
+      return true;
+    }
+    return false;
+  }
+}
+
+class _CustomElementNodeValidator extends _SimpleNodeValidator {
+  final bool allowTypeExtension;
+  final bool allowCustomTag;
+
+  _CustomElementNodeValidator(
+      UriPolicy uriPolicy,
+      Iterable<String> allowedElements,
+      Iterable<String> allowedAttributes,
+      Iterable<String> allowedUriAttributes,
+      bool allowTypeExtension,
+      bool allowCustomTag)
+      : this.allowTypeExtension = allowTypeExtension == true,
+        this.allowCustomTag = allowCustomTag == true,
+        super(uriPolicy,
+            allowedElements: allowedElements,
+            allowedAttributes: allowedAttributes,
+            allowedUriAttributes: allowedUriAttributes);
+
+  bool allowsElement(Element element) {
+    if (allowTypeExtension) {
+      var isAttr = element.attributes['is'];
+      if (isAttr != null) {
+        return allowedElements.contains(isAttr.toUpperCase()) &&
+            allowedElements.contains(Element._safeTagName(element));
+      }
+    }
+    return allowCustomTag &&
+        allowedElements.contains(Element._safeTagName(element));
+  }
+
+  bool allowsAttribute(Element element, String attributeName, String value) {
+    if (allowsElement(element)) {
+      if (allowTypeExtension &&
+          attributeName == 'is' &&
+          allowedElements.contains(value.toUpperCase())) {
+        return true;
+      }
+      return super.allowsAttribute(element, attributeName, value);
+    }
+    return false;
+  }
+}
+
+class _TemplatingNodeValidator extends _SimpleNodeValidator {
+  static const _TEMPLATE_ATTRS = const <String>[
+    'bind',
+    'if',
+    'ref',
+    'repeat',
+    'syntax'
+  ];
+
+  final Set<String> _templateAttrs;
+
+  _TemplatingNodeValidator()
+      : _templateAttrs = new Set<String>.from(_TEMPLATE_ATTRS),
+        super(null,
+            allowedElements: ['TEMPLATE'],
+            allowedAttributes:
+                _TEMPLATE_ATTRS.map((attr) => 'TEMPLATE::$attr')) {}
+
+  bool allowsAttribute(Element element, String attributeName, String value) {
+    if (super.allowsAttribute(element, attributeName, value)) {
+      return true;
+    }
+
+    if (attributeName == 'template' && value == "") {
+      return true;
+    }
+
+    if (element.attributes['template'] == "") {
+      return _templateAttrs.contains(attributeName);
+    }
+    return false;
+  }
+}
+
+class _SvgNodeValidator implements NodeValidator {
+  bool allowsElement(Element element) {
+    if (element is svg.ScriptElement) {
+      return false;
+    }
+    // Firefox 37 has issues with creating foreign elements inside a
+    // foreignobject tag as SvgElement. We don't want foreignobject contents
+    // anyway, so just remove the whole tree outright. And we can't rely
+    // on IE recognizing the SvgForeignObject type, so go by tagName. Bug 23144
+    if (element is svg.SvgElement &&
+        Element._safeTagName(element) == 'foreignObject') {
+      return false;
+    }
+    if (element is svg.SvgElement) {
+      return true;
+    }
+    return false;
+  }
+
+  bool allowsAttribute(Element element, String attributeName, String value) {
+    if (attributeName == 'is' || attributeName.startsWith('on')) {
+      return false;
+    }
+    return allowsElement(element);
+  }
+}
diff --git a/tools/dom/nnbd_src/ReadyState.dart b/tools/dom/nnbd_src/ReadyState.dart
new file mode 100644
index 0000000..37c3fdb
--- /dev/null
+++ b/tools/dom/nnbd_src/ReadyState.dart
@@ -0,0 +1,26 @@
+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * Contains the set of standard values returned by HTMLDocument.getReadyState.
+ */
+abstract class ReadyState {
+  /**
+   * Indicates the document is still loading and parsing.
+   */
+  static const String LOADING = "loading";
+
+  /**
+   * Indicates the document is finished parsing but is still loading
+   * subresources.
+   */
+  static const String INTERACTIVE = "interactive";
+
+  /**
+   * Indicates the document and all subresources have been loaded.
+   */
+  static const String COMPLETE = "complete";
+}
diff --git a/tools/dom/nnbd_src/Validators.dart b/tools/dom/nnbd_src/Validators.dart
new file mode 100644
index 0000000..ac0663d
--- /dev/null
+++ b/tools/dom/nnbd_src/Validators.dart
@@ -0,0 +1,307 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.dom.html;
+
+/**
+ * Interface used to validate that only accepted elements and attributes are
+ * allowed while parsing HTML strings into DOM nodes.
+ *
+ * In general, customization of validation behavior should be done via the
+ * [NodeValidatorBuilder] class to mitigate the chances of incorrectly
+ * implementing validation rules.
+ */
+abstract class NodeValidator {
+  /**
+   * Construct a default NodeValidator which only accepts whitelisted HTML5
+   * elements and attributes.
+   *
+   * If a uriPolicy is not specified then the default uriPolicy will be used.
+   */
+  factory NodeValidator({UriPolicy uriPolicy}) =>
+      new _Html5NodeValidator(uriPolicy: uriPolicy);
+
+  factory NodeValidator.throws(NodeValidator base) =>
+      new _ThrowsNodeValidator(base);
+
+  /**
+   * Returns true if the tagName is an accepted type.
+   */
+  bool allowsElement(Element element);
+
+  /**
+   * Returns true if the attribute is allowed.
+   *
+   * The attributeName parameter will always be in lowercase.
+   *
+   * See [allowsElement] for format of tagName.
+   */
+  bool allowsAttribute(Element element, String attributeName, String value);
+}
+
+/**
+ * Performs sanitization of a node tree after construction to ensure that it
+ * does not contain any disallowed elements or attributes.
+ *
+ * In general custom implementations of this class should not be necessary and
+ * all validation customization should be done in custom NodeValidators, but
+ * custom implementations of this class can be created to perform more complex
+ * tree sanitization.
+ */
+abstract class NodeTreeSanitizer {
+  /**
+   * Constructs a default tree sanitizer which will remove all elements and
+   * attributes which are not allowed by the provided validator.
+   */
+  factory NodeTreeSanitizer(NodeValidator validator) =>
+      new _ValidatingTreeSanitizer(validator);
+
+  /**
+   * Called with the root of the tree which is to be sanitized.
+   *
+   * This method needs to walk the entire tree and either remove elements and
+   * attributes which are not recognized as safe or throw an exception which
+   * will mark the entire tree as unsafe.
+   */
+  void sanitizeTree(Node node);
+
+  /**
+   * A sanitizer for trees that we trust. It does no validation and allows
+   * any elements. It is also more efficient, since it can pass the text
+   * directly through to the underlying APIs without creating a document
+   * fragment to be sanitized.
+   */
+  static const trusted = const _TrustedHtmlTreeSanitizer();
+}
+
+/**
+ * A sanitizer for trees that we trust. It does no validation and allows
+ * any elements.
+ */
+class _TrustedHtmlTreeSanitizer implements NodeTreeSanitizer {
+  const _TrustedHtmlTreeSanitizer();
+
+  sanitizeTree(Node node) {}
+}
+
+/**
+ * Defines the policy for what types of uris are allowed for particular
+ * attribute values.
+ *
+ * This can be used to provide custom rules such as allowing all http:// URIs
+ * for image attributes but only same-origin URIs for anchor tags.
+ */
+abstract class UriPolicy {
+  /**
+   * Constructs the default UriPolicy which is to only allow Uris to the same
+   * origin as the application was launched from.
+   *
+   * This will block all ftp: mailto: URIs. It will also block accessing
+   * https://example.com if the app is running from http://example.com.
+   */
+  factory UriPolicy() => new _SameOriginUriPolicy();
+
+  /**
+   * Checks if the uri is allowed on the specified attribute.
+   *
+   * The uri provided may or may not be a relative path.
+   */
+  bool allowsUri(String uri);
+}
+
+/**
+ * Allows URIs to the same origin as the current application was loaded from
+ * (such as https://example.com:80).
+ */
+class _SameOriginUriPolicy implements UriPolicy {
+  final AnchorElement _hiddenAnchor = new AnchorElement();
+  final Location _loc = window.location;
+
+  bool allowsUri(String uri) {
+    _hiddenAnchor.href = uri;
+    // IE leaves an empty hostname for same-origin URIs.
+    return (_hiddenAnchor.hostname == _loc.hostname &&
+            _hiddenAnchor.port == _loc.port &&
+            _hiddenAnchor.protocol == _loc.protocol) ||
+        (_hiddenAnchor.hostname == '' &&
+            _hiddenAnchor.port == '' &&
+            (_hiddenAnchor.protocol == ':' || _hiddenAnchor.protocol == ''));
+  }
+}
+
+class _ThrowsNodeValidator implements NodeValidator {
+  final NodeValidator validator;
+
+  _ThrowsNodeValidator(this.validator) {}
+
+  bool allowsElement(Element element) {
+    if (!validator.allowsElement(element)) {
+      throw new ArgumentError(Element._safeTagName(element));
+    }
+    return true;
+  }
+
+  bool allowsAttribute(Element element, String attributeName, String value) {
+    if (!validator.allowsAttribute(element, attributeName, value)) {
+      throw new ArgumentError(
+          '${Element._safeTagName(element)}[$attributeName="$value"]');
+    }
+  }
+}
+
+/**
+ * Standard tree sanitizer which validates a node tree against the provided
+ * validator and removes any nodes or attributes which are not allowed.
+ */
+class _ValidatingTreeSanitizer implements NodeTreeSanitizer {
+  NodeValidator validator;
+  _ValidatingTreeSanitizer(this.validator) {}
+
+  void sanitizeTree(Node node) {
+    void walk(Node node, Node parent) {
+      sanitizeNode(node, parent);
+
+      var child = node.lastChild;
+      while (null != child) {
+        var nextChild;
+        try {
+          // Child may be removed during the walk, and we may not
+          // even be able to get its previousNode.
+          nextChild = child.previousNode;
+        } catch (e) {
+          // Child appears bad, remove it. We want to check the rest of the
+          // children of node and, but we have no way of getting to the next
+          // child, so start again from the last child.
+          _removeNode(child, node);
+          child = null;
+          nextChild = node.lastChild;
+        }
+        if (child != null) walk(child, node);
+        child = nextChild;
+      }
+    }
+
+    walk(node, null);
+  }
+
+  /// Aggressively try to remove node.
+  void _removeNode(Node node, Node parent) {
+    // If we have the parent, it's presumably already passed more sanitization
+    // or is the fragment, so ask it to remove the child. And if that fails
+    // try to set the outer html.
+    if (parent == null) {
+      node.remove();
+    } else {
+      parent._removeChild(node);
+    }
+  }
+
+  /// Sanitize the element, assuming we can't trust anything about it.
+  void _sanitizeUntrustedElement(/* Element */ element, Node parent) {
+    // If the _hasCorruptedAttributes does not successfully return false,
+    // then we consider it corrupted and remove.
+    // TODO(alanknight): This is a workaround because on Firefox
+    // embed/object
+    // tags typeof is "function", not "object". We don't recognize them, and
+    // can't call methods. This does mean that you can't explicitly allow an
+    // embed tag. The only thing that will let it through is a null
+    // sanitizer that doesn't traverse the tree at all. But sanitizing while
+    // allowing embeds seems quite unlikely. This is also the reason that we
+    // can't declare the type of element, as an embed won't pass any type
+    // check in dart2js.
+    var corrupted = true;
+    var attrs;
+    var isAttr;
+    try {
+      // If getting/indexing attributes throws, count that as corrupt.
+      attrs = element.attributes;
+      isAttr = attrs['is'];
+      var corruptedTest1 = Element._hasCorruptedAttributes(element);
+
+      // On IE, erratically, the hasCorruptedAttributes test can return false,
+      // even though it clearly is corrupted. A separate copy of the test
+      // inlining just the basic check seems to help.
+      corrupted = corruptedTest1
+          ? true
+          : Element._hasCorruptedAttributesAdditionalCheck(element);
+    } catch (e) {}
+    var elementText = 'element unprintable';
+    try {
+      elementText = element.toString();
+    } catch (e) {}
+    try {
+      var elementTagName = Element._safeTagName(element);
+      _sanitizeElement(element, parent, corrupted, elementText, elementTagName,
+          attrs, isAttr);
+    } on ArgumentError {
+      // Thrown by _ThrowsNodeValidator
+      rethrow;
+    } catch (e) {
+      // Unexpected exception sanitizing -> remove
+      _removeNode(element, parent);
+      window.console.warn('Removing corrupted element $elementText');
+    }
+  }
+
+  /// Having done basic sanity checking on the element, and computed the
+  /// important attributes we want to check, remove it if it's not valid
+  /// or not allowed, either as a whole or particular attributes.
+  void _sanitizeElement(Element element, Node parent, bool corrupted,
+      String text, String tag, Map attrs, String isAttr) {
+    if (false != corrupted) {
+      _removeNode(element, parent);
+      window.console
+          .warn('Removing element due to corrupted attributes on <$text>');
+      return;
+    }
+    if (!validator.allowsElement(element)) {
+      _removeNode(element, parent);
+      window.console.warn('Removing disallowed element <$tag> from $parent');
+      return;
+    }
+
+    if (isAttr != null) {
+      if (!validator.allowsAttribute(element, 'is', isAttr)) {
+        _removeNode(element, parent);
+        window.console.warn('Removing disallowed type extension '
+            '<$tag is="$isAttr">');
+        return;
+      }
+    }
+
+    // TODO(blois): Need to be able to get all attributes, irrespective of
+    // XMLNS.
+    var keys = attrs.keys.toList();
+    for (var i = attrs.length - 1; i >= 0; --i) {
+      var name = keys[i];
+      if (!validator.allowsAttribute(
+          element, name.toLowerCase(), attrs[name])) {
+        window.console.warn('Removing disallowed attribute '
+            '<$tag $name="${attrs[name]}">');
+        attrs.remove(name);
+      }
+    }
+
+    if (element is TemplateElement) {
+      TemplateElement template = element;
+      sanitizeTree(template.content);
+    }
+  }
+
+  /// Sanitize the node and its children recursively.
+  void sanitizeNode(Node node, Node parent) {
+    switch (node.nodeType) {
+      case Node.ELEMENT_NODE:
+        _sanitizeUntrustedElement(node, parent);
+        break;
+      case Node.COMMENT_NODE:
+      case Node.DOCUMENT_FRAGMENT_NODE:
+      case Node.TEXT_NODE:
+      case Node.CDATA_SECTION_NODE:
+        break;
+      default:
+        _removeNode(node, parent);
+    }
+  }
+}
diff --git a/tools/dom/nnbd_src/WrappedList.dart b/tools/dom/nnbd_src/WrappedList.dart
new file mode 100644
index 0000000..6a8d43c
--- /dev/null
+++ b/tools/dom/nnbd_src/WrappedList.dart
@@ -0,0 +1,93 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.dom.html;
+
+/**
+ * A list which just wraps another list, for either intercepting list calls or
+ * retyping the list (for example, from List<A> to List<B> where B extends A).
+ */
+class _WrappedList<E extends Node> extends ListBase<E>
+    implements NodeListWrapper {
+  final List<Node> _list;
+
+  _WrappedList(this._list);
+
+  // Iterable APIs
+
+  Iterator<E> get iterator => new _WrappedIterator<E>(_list.iterator);
+
+  int get length => _list.length;
+
+  // Collection APIs
+
+  void add(E element) {
+    _list.add(element);
+  }
+
+  bool remove(Object? element) => _list.remove(element);
+
+  void clear() {
+    _list.clear();
+  }
+
+  // List APIs
+
+  E operator [](int index) => _list[index];
+
+  void operator []=(int index, E value) {
+    _list[index] = value;
+  }
+
+  set length(int newLength) {
+    _list.length = newLength;
+  }
+
+  void sort([int compare(E a, E b)?]) {
+    // Implicit downcast on argument from Node to E-extends-Node.
+    _list.sort((Node a, Node b) => compare(a, b));
+  }
+
+  int indexOf(Object element, [int start = 0]) => _list.indexOf(element, start);
+
+  int lastIndexOf(Object element, [int? start]) =>
+      _list.lastIndexOf(element, start);
+
+  void insert(int index, E element) => _list.insert(index, element);
+
+  E removeAt(int index) => _list.removeAt(index);
+
+  void setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]) {
+    _list.setRange(start, end, iterable, skipCount);
+  }
+
+  void removeRange(int start, int end) {
+    _list.removeRange(start, end);
+  }
+
+  void replaceRange(int start, int end, Iterable<E> iterable) {
+    _list.replaceRange(start, end, iterable);
+  }
+
+  void fillRange(int start, int end, [E? fillValue]) {
+    _list.fillRange(start, end, fillValue);
+  }
+
+  List<Node> get rawList => _list;
+}
+
+/**
+ * Iterator wrapper for _WrappedList.
+ */
+class _WrappedIterator<E extends Node> implements Iterator<E> {
+  Iterator<Node> _iterator;
+
+  _WrappedIterator(this._iterator);
+
+  bool moveNext() {
+    return _iterator.moveNext();
+  }
+
+  E get current => _iterator.current as E;
+}
diff --git a/tools/dom/nnbd_src/_HttpRequestUtils.dart b/tools/dom/nnbd_src/_HttpRequestUtils.dart
new file mode 100644
index 0000000..d6e73d7
--- /dev/null
+++ b/tools/dom/nnbd_src/_HttpRequestUtils.dart
@@ -0,0 +1,26 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+class _HttpRequestUtils {
+  // Helper for factory HttpRequest.get
+  static HttpRequest get(
+      String url, onComplete(HttpRequest request), bool withCredentials) {
+    final request = new HttpRequest();
+    request.open('GET', url, async: true);
+
+    request.withCredentials = withCredentials;
+
+    request.onReadyStateChange.listen((e) {
+      if (request.readyState == HttpRequest.DONE) {
+        onComplete(request);
+      }
+    });
+
+    request.send();
+
+    return request;
+  }
+}
diff --git a/tools/dom/nnbd_src/_ListIterators.dart b/tools/dom/nnbd_src/_ListIterators.dart
new file mode 100644
index 0000000..0a9080e
--- /dev/null
+++ b/tools/dom/nnbd_src/_ListIterators.dart
@@ -0,0 +1,57 @@
+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+// Iterator for arrays with fixed size.
+class FixedSizeListIterator<T> implements Iterator<T> {
+  final List<T> _array;
+  final int _length; // Cache array length for faster access.
+  int _position;
+  T _current;
+
+  FixedSizeListIterator(List<T> array)
+      : _array = array,
+        _position = -1,
+        _length = array.length;
+
+  bool moveNext() {
+    int nextPosition = _position + 1;
+    if (nextPosition < _length) {
+      _current = _array[nextPosition];
+      _position = nextPosition;
+      return true;
+    }
+    _current = null;
+    _position = _length;
+    return false;
+  }
+
+  T get current => _current;
+}
+
+// Iterator for arrays with variable size.
+class _VariableSizeListIterator<T> implements Iterator<T> {
+  final List<T> _array;
+  int _position;
+  T _current;
+
+  _VariableSizeListIterator(List<T> array)
+      : _array = array,
+        _position = -1;
+
+  bool moveNext() {
+    int nextPosition = _position + 1;
+    if (nextPosition < _array.length) {
+      _current = _array[nextPosition];
+      _position = nextPosition;
+      return true;
+    }
+    _current = null;
+    _position = _array.length;
+    return false;
+  }
+
+  T get current => _current;
+}
diff --git a/tools/dom/nnbd_src/dart2js_Console.dart b/tools/dom/nnbd_src/dart2js_Console.dart
new file mode 100644
index 0000000..5ed9206
--- /dev/null
+++ b/tools/dom/nnbd_src/dart2js_Console.dart
@@ -0,0 +1,82 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+class Console {
+  const Console._safe();
+  static const Console _safeConsole = const Console._safe();
+
+  bool get _isConsoleDefined => JS('bool', 'typeof console != "undefined"');
+
+  MemoryInfo get memory =>
+      _isConsoleDefined ? JS('MemoryInfo', 'window.console.memory') : null;
+
+  void assertCondition(bool condition, Object arg) => _isConsoleDefined
+      ? JS('void', 'window.console.assertCondition(#, #)', condition, arg)
+      : null;
+
+  void clear(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.clear(#)', arg) : null;
+
+  void count(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.count(#)', arg) : null;
+
+  void debug(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.debug(#)', arg) : null;
+
+  void dir(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.dir(#)', arg) : null;
+
+  void dirxml(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.dirxml(#)', arg) : null;
+
+  void error(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.error(#)', arg) : null;
+
+  void group(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.group(#)', arg) : null;
+
+  void groupCollapsed(Object arg) => _isConsoleDefined
+      ? JS('void', 'window.console.groupCollapsed(#)', arg)
+      : null;
+
+  void groupEnd() =>
+      _isConsoleDefined ? JS('void', 'window.console.groupEnd()') : null;
+
+  void info(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.info(#)', arg) : null;
+
+  void log(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.log(#)', arg) : null;
+
+  void markTimeline(Object arg) => _isConsoleDefined
+      ? JS('void', 'window.console.markTimeline(#)', arg)
+      : null;
+
+  void profile(String title) =>
+      _isConsoleDefined ? JS('void', 'window.console.profile(#)', title) : null;
+
+  void profileEnd(String title) => _isConsoleDefined
+      ? JS('void', 'window.console.profileEnd(#)', title)
+      : null;
+
+  void table(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.table(#)', arg) : null;
+
+  void time(String title) =>
+      _isConsoleDefined ? JS('void', 'window.console.time(#)', title) : null;
+
+  void timeEnd(String title) =>
+      _isConsoleDefined ? JS('void', 'window.console.timeEnd(#)', title) : null;
+
+  void timeStamp(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.timeStamp(#)', arg) : null;
+
+  void trace(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.trace(#)', arg) : null;
+
+  void warn(Object arg) =>
+      _isConsoleDefined ? JS('void', 'window.console.warn(#)', arg) : null;
+}
diff --git a/tools/dom/nnbd_src/dart2js_Conversions.dart b/tools/dom/nnbd_src/dart2js_Conversions.dart
new file mode 100644
index 0000000..aa78ec1
--- /dev/null
+++ b/tools/dom/nnbd_src/dart2js_Conversions.dart
@@ -0,0 +1,49 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Conversions for Window.  These check if the window is the local
+// window, and if it's not, wraps or unwraps it with a secure wrapper.
+// We need to test for EventTarget here as well as it's a base type.
+// We omit an unwrapper for Window as no methods take a non-local
+// window as a parameter.
+
+part of html;
+
+WindowBase _convertNativeToDart_Window(win) {
+  if (win == null) return null;
+  return _DOMWindowCrossFrame._createSafe(win);
+}
+
+EventTarget _convertNativeToDart_EventTarget(e) {
+  if (e == null) {
+    return null;
+  }
+  // Assume it's a Window if it contains the postMessage property.  It may be
+  // from a different frame - without a patched prototype - so we cannot
+  // rely on Dart type checking.
+  if (JS('bool', r'"postMessage" in #', e)) {
+    var window = _DOMWindowCrossFrame._createSafe(e);
+    // If it's a native window.
+    if (window is EventTarget) {
+      return window;
+    }
+    return null;
+  } else
+    return e;
+}
+
+EventTarget _convertDartToNative_EventTarget(e) {
+  if (e is _DOMWindowCrossFrame) {
+    return e._window;
+  } else {
+    return e;
+  }
+}
+
+_convertNativeToDart_XHR_Response(o) {
+  if (o is Document) {
+    return o;
+  }
+  return convertNativeToDart_SerializedScriptValue(o);
+}
diff --git a/tools/dom/nnbd_src/dart2js_CssClassSet.dart b/tools/dom/nnbd_src/dart2js_CssClassSet.dart
new file mode 100644
index 0000000..0afe6fcf
--- /dev/null
+++ b/tools/dom/nnbd_src/dart2js_CssClassSet.dart
@@ -0,0 +1,260 @@
+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * A set (union) of the CSS classes that are present in a set of elements.
+ * Implemented separately from _ElementCssClassSet for performance.
+ */
+class _MultiElementCssClassSet extends CssClassSetImpl {
+  final Iterable<Element> _elementIterable;
+
+  // TODO(sra): Perhaps we should store the DomTokenList instead.
+  final List<CssClassSetImpl> _sets;
+
+  factory _MultiElementCssClassSet(Iterable<Element> elements) {
+    return new _MultiElementCssClassSet._(elements,
+        new List<CssClassSetImpl>.from(elements.map((Element e) => e.classes)));
+  }
+
+  _MultiElementCssClassSet._(this._elementIterable, this._sets);
+
+  Set<String> readClasses() {
+    var s = new LinkedHashSet<String>();
+    _sets.forEach((CssClassSetImpl e) => s.addAll(e.readClasses()));
+    return s;
+  }
+
+  void writeClasses(Set<String> s) {
+    var classes = s.join(' ');
+    for (Element e in _elementIterable) {
+      e.className = classes;
+    }
+  }
+
+  /**
+   * Helper method used to modify the set of css classes on this element.
+   *
+   *   f - callback with:
+   *   s - a Set of all the css class name currently on this element.
+   *
+   *   After f returns, the modified set is written to the
+   *       className property of this element.
+   */
+  modify(f(Set<String> s)) {
+    _sets.forEach((CssClassSetImpl e) => e.modify(f));
+  }
+
+  /**
+   * Adds the class [value] to the element if it is not on it, removes it if it
+   * is.
+   *
+   * TODO(sra): It seems wrong to collect a 'changed' flag like this when the
+   * underlying toggle returns an 'is set' flag.
+   */
+  bool toggle(String value, [bool? shouldAdd]) => _sets.fold(
+      false,
+      (bool changed, CssClassSetImpl e) =>
+          e.toggle(value, shouldAdd) || changed);
+
+  /**
+   * Remove the class [value] from element, and return true on successful
+   * removal.
+   *
+   * This is the Dart equivalent of jQuery's
+   * [removeClass](http://api.jquery.com/removeClass/).
+   */
+  bool remove(Object? value) => _sets.fold(
+      false, (bool changed, CssClassSetImpl e) => e.remove(value) || changed);
+}
+
+class _ElementCssClassSet extends CssClassSetImpl {
+  final Element _element;
+
+  _ElementCssClassSet(this._element);
+
+  Set<String> readClasses() {
+    var s = new LinkedHashSet<String>();
+    var classname = _element.className;
+
+    for (String name in classname.split(' ')) {
+      String trimmed = name.trim();
+      if (!trimmed.isEmpty) {
+        s.add(trimmed);
+      }
+    }
+    return s;
+  }
+
+  void writeClasses(Set<String> s) {
+    _element.className = s.join(' ');
+  }
+
+  int get length => _classListLength(_classListOf(_element));
+  bool get isEmpty => length == 0;
+  bool get isNotEmpty => length != 0;
+
+  void clear() {
+    _element.className = '';
+  }
+
+  bool contains(Object? value) {
+    return _contains(_element, value);
+  }
+
+  bool add(String value) {
+    return _add(_element, value);
+  }
+
+  bool remove(Object? value) {
+    return value is String && _remove(_element, value);
+  }
+
+  bool toggle(String value, [bool? shouldAdd]) {
+    return _toggle(_element, value, shouldAdd);
+  }
+
+  void addAll(Iterable<String> iterable) {
+    _addAll(_element, iterable);
+  }
+
+  void removeAll(Iterable<Object?> iterable) {
+    _removeAll(_element, iterable);
+  }
+
+  void retainAll(Iterable<Object?> iterable) {
+    _removeWhere(_element, iterable.toSet().contains, false);
+  }
+
+  void removeWhere(bool test(String name)) {
+    _removeWhere(_element, test, true);
+  }
+
+  void retainWhere(bool test(String name)) {
+    _removeWhere(_element, test, false);
+  }
+
+  static bool _contains(Element _element, Object value) {
+    return value is String && _classListContains(_classListOf(_element), value);
+  }
+
+  @pragma('dart2js:tryInline')
+  static bool _add(Element _element, String value) {
+    DomTokenList list = _classListOf(_element);
+    // Compute returned result independently of action upon the set.
+    bool added = !_classListContainsBeforeAddOrRemove(list, value);
+    _classListAdd(list, value);
+    return added;
+  }
+
+  @pragma('dart2js:tryInline')
+  static bool _remove(Element _element, String value) {
+    DomTokenList list = _classListOf(_element);
+    bool removed = _classListContainsBeforeAddOrRemove(list, value);
+    _classListRemove(list, value);
+    return removed;
+  }
+
+  static bool _toggle(Element _element, String value, bool? shouldAdd) {
+    // There is no value that can be passed as the second argument of
+    // DomTokenList.toggle that behaves the same as passing one argument.
+    // `null` is seen as false, meaning 'remove'.
+    return shouldAdd == null
+        ? _toggleDefault(_element, value)
+        : _toggleOnOff(_element, value, shouldAdd);
+  }
+
+  static bool _toggleDefault(Element _element, String value) {
+    DomTokenList list = _classListOf(_element);
+    return _classListToggle1(list, value);
+  }
+
+  static bool _toggleOnOff(Element _element, String value, bool? shouldAdd) {
+    DomTokenList list = _classListOf(_element);
+    // IE's toggle does not take a second parameter. We would prefer:
+    //
+    //    return _classListToggle2(list, value, shouldAdd);
+    //
+    if (shouldAdd ?? false) {
+      _classListAdd(list, value);
+      return true;
+    } else {
+      _classListRemove(list, value);
+      return false;
+    }
+  }
+
+  static void _addAll(Element _element, Iterable<String> iterable) {
+    DomTokenList list = _classListOf(_element);
+    for (String value in iterable) {
+      _classListAdd(list, value);
+    }
+  }
+
+  static void _removeAll(Element _element, Iterable<Object> iterable) {
+    DomTokenList list = _classListOf(_element);
+    for (String value in iterable) {
+      _classListRemove(list, value);
+    }
+  }
+
+  static void _removeWhere(
+      Element _element, bool test(String name), bool doRemove) {
+    DomTokenList list = _classListOf(_element);
+    int i = 0;
+    while (i < _classListLength(list)) {
+      String item = list.item(i);
+      if (doRemove == test(item)) {
+        _classListRemove(list, item);
+      } else {
+        ++i;
+      }
+    }
+  }
+
+  // A collection of static methods for DomTokenList. These methods are a
+  // work-around for the lack of annotations to express the full behaviour of
+  // the DomTokenList methods.
+
+  static DomTokenList _classListOf(Element e) => JS(
+      'returns:DomTokenList;creates:DomTokenList;effects:none;depends:all;',
+      '#.classList',
+      e);
+
+  static int _classListLength(DomTokenList list) =>
+      JS('returns:JSUInt31;effects:none;depends:all;', '#.length', list);
+
+  static bool _classListContains(DomTokenList list, String value) =>
+      JS('returns:bool;effects:none;depends:all', '#.contains(#)', list, value);
+
+  static bool _classListContainsBeforeAddOrRemove(
+          DomTokenList list, String value) =>
+      // 'throws:never' is a lie, since 'contains' will throw on an illegal
+      // token.  However, we always call this function immediately prior to
+      // add/remove/toggle with the same token.  Often the result of 'contains'
+      // is unused and the lie makes it possible for the 'contains' instruction
+      // to be removed.
+      JS('returns:bool;effects:none;depends:all;throws:null(1)',
+          '#.contains(#)', list, value);
+
+  static void _classListAdd(DomTokenList list, String value) {
+    // list.add(value);
+    JS('', '#.add(#)', list, value);
+  }
+
+  static void _classListRemove(DomTokenList list, String value) {
+    // list.remove(value);
+    JS('', '#.remove(#)', list, value);
+  }
+
+  static bool _classListToggle1(DomTokenList list, String value) {
+    return JS('bool', '#.toggle(#)', list, value);
+  }
+
+  static bool _classListToggle2(
+      DomTokenList list, String value, bool? shouldAdd) {
+    return JS('bool', '#.toggle(#, #)', list, value, shouldAdd);
+  }
+}
diff --git a/tools/dom/nnbd_src/dart2js_CustomElementSupport.dart b/tools/dom/nnbd_src/dart2js_CustomElementSupport.dart
new file mode 100644
index 0000000..98c3c24
--- /dev/null
+++ b/tools/dom/nnbd_src/dart2js_CustomElementSupport.dart
@@ -0,0 +1,214 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.dom.html;
+
+_callConstructor(constructor, interceptor) {
+  return (receiver) {
+    setNativeSubclassDispatchRecord(receiver, interceptor);
+
+    // Mirrors uses the constructor property to cache lookups, so we need it to
+    // be set correctly, including on IE where it is not automatically picked
+    // up from the __proto__.
+    JS('', '#.constructor = #.__proto__.constructor', receiver, receiver);
+    return JS('', '#(#)', constructor, receiver);
+  };
+}
+
+_callAttached(receiver) {
+  return receiver.attached();
+}
+
+_callDetached(receiver) {
+  return receiver.detached();
+}
+
+_callAttributeChanged(receiver, name, oldValue, newValue) {
+  return receiver.attributeChanged(name, oldValue, newValue);
+}
+
+_makeCallbackMethod(callback) {
+  return JS(
+      '',
+      '''((function(invokeCallback) {
+             return function() {
+               return invokeCallback(this);
+             };
+          })(#))''',
+      convertDartClosureToJS(callback, 1));
+}
+
+_makeCallbackMethod3(callback) {
+  return JS(
+      '',
+      '''((function(invokeCallback) {
+             return function(arg1, arg2, arg3) {
+               return invokeCallback(this, arg1, arg2, arg3);
+             };
+          })(#))''',
+      convertDartClosureToJS(callback, 4));
+}
+
+/// Checks whether the given [element] correctly extends from the native class
+/// with the given [baseClassName]. This method will throw if the base class
+/// doesn't match, except when the element extends from `template` and it's base
+/// class is `HTMLUnknownElement`. This exclusion is needed to support extension
+/// of template elements (used heavily in Polymer 1.0) on IE11 when using the
+/// webcomponents-lite.js polyfill.
+void _checkExtendsNativeClassOrTemplate(
+    Element element, String extendsTag, String baseClassName) {
+  if (!JS('bool', '(# instanceof window[#])', element, baseClassName) &&
+      !((extendsTag == 'template' &&
+          JS('bool', '(# instanceof window["HTMLUnknownElement"])',
+              element)))) {
+    throw new UnsupportedError('extendsTag does not match base native class');
+  }
+}
+
+Function _registerCustomElement(context, document, String tag, [Map options]) {
+  // Function follows the same pattern as the following JavaScript code for
+  // registering a custom element.
+  //
+  //    var proto = Object.create(HTMLElement.prototype, {
+  //        createdCallback: {
+  //          value: function() {
+  //            window.console.log('here');
+  //          }
+  //        }
+  //    });
+  //    document.registerElement('x-foo', { prototype: proto });
+  //    ...
+  //    var e = document.createElement('x-foo');
+
+  var extendsTagName = '';
+  Type type;
+  if (options != null) {
+    extendsTagName = options['extends'];
+    type = options['prototype'];
+  }
+
+  var interceptorClass = findInterceptorConstructorForType(type);
+  if (interceptorClass == null) {
+    throw new ArgumentError(type);
+  }
+
+  var interceptor = JS('=Object', '#.prototype', interceptorClass);
+
+  var constructor = findConstructorForNativeSubclassType(type, 'created');
+  if (constructor == null) {
+    throw new ArgumentError("$type has no constructor called 'created'");
+  }
+
+  // Workaround for 13190- use an article element to ensure that HTMLElement's
+  // interceptor is resolved correctly.
+  getNativeInterceptor(new Element.tag('article'));
+
+  String baseClassName = findDispatchTagForInterceptorClass(interceptorClass);
+  if (baseClassName == null) {
+    throw new ArgumentError(type);
+  }
+
+  if (extendsTagName == null) {
+    if (baseClassName != 'HTMLElement') {
+      throw new UnsupportedError('Class must provide extendsTag if base '
+          'native class is not HtmlElement');
+    }
+  } else {
+    var element = document.createElement(extendsTagName);
+    _checkExtendsNativeClassOrTemplate(element, extendsTagName, baseClassName);
+  }
+
+  var baseConstructor = JS('=Object', '#[#]', context, baseClassName);
+
+  var properties = JS('=Object', '{}');
+
+  JS(
+      'void',
+      '#.createdCallback = #',
+      properties,
+      JS('=Object', '{value: #}',
+          _makeCallbackMethod(_callConstructor(constructor, interceptor))));
+  JS('void', '#.attachedCallback = #', properties,
+      JS('=Object', '{value: #}', _makeCallbackMethod(_callAttached)));
+  JS('void', '#.detachedCallback = #', properties,
+      JS('=Object', '{value: #}', _makeCallbackMethod(_callDetached)));
+  JS('void', '#.attributeChangedCallback = #', properties,
+      JS('=Object', '{value: #}', _makeCallbackMethod3(_callAttributeChanged)));
+
+  var baseProto = JS('=Object', '#.prototype', baseConstructor);
+  var proto = JS('=Object', 'Object.create(#, #)', baseProto, properties);
+
+  setNativeSubclassDispatchRecord(proto, interceptor);
+
+  var opts = JS('=Object', '{prototype: #}', proto);
+
+  if (extendsTagName != null) {
+    JS('=Object', '#.extends = #', opts, extendsTagName);
+  }
+
+  return JS(
+      'JavaScriptFunction', '#.registerElement(#, #)', document, tag, opts);
+}
+
+//// Called by Element.created to do validation & initialization.
+void _initializeCustomElement(Element e) {
+  // TODO(blois): Add validation that this is only in response to an upgrade.
+}
+
+/// Dart2JS implementation of ElementUpgrader
+class _JSElementUpgrader implements ElementUpgrader {
+  var _interceptor;
+  var _constructor;
+  var _nativeType;
+
+  _JSElementUpgrader(Document document, Type type, String extendsTag) {
+    var interceptorClass = findInterceptorConstructorForType(type);
+    if (interceptorClass == null) {
+      throw new ArgumentError(type);
+    }
+
+    _constructor = findConstructorForNativeSubclassType(type, 'created');
+    if (_constructor == null) {
+      throw new ArgumentError("$type has no constructor called 'created'");
+    }
+
+    // Workaround for 13190- use an article element to ensure that HTMLElement's
+    // interceptor is resolved correctly.
+    getNativeInterceptor(new Element.tag('article'));
+
+    var baseClassName = findDispatchTagForInterceptorClass(interceptorClass);
+    if (baseClassName == null) {
+      throw new ArgumentError(type);
+    }
+
+    if (extendsTag == null) {
+      if (baseClassName != 'HTMLElement') {
+        throw new UnsupportedError('Class must provide extendsTag if base '
+            'native class is not HtmlElement');
+      }
+      _nativeType = HtmlElement;
+    } else {
+      var element = document.createElement(extendsTag);
+      _checkExtendsNativeClassOrTemplate(element, extendsTag, baseClassName);
+      _nativeType = element.runtimeType;
+    }
+
+    _interceptor = JS('=Object', '#.prototype', interceptorClass);
+  }
+
+  Element upgrade(Element element) {
+    // Only exact type matches are supported- cannot be a subclass.
+    if (element.runtimeType != _nativeType) {
+      // Some browsers may represent non-upgraded elements <x-foo> as
+      // UnknownElement and not a plain HtmlElement.
+      if (_nativeType != HtmlElement || element.runtimeType != UnknownElement) {
+        throw new ArgumentError('element is not subclass of $_nativeType');
+      }
+    }
+
+    setNativeSubclassDispatchRecord(element, _interceptor);
+    JS('', '#(#)', _constructor, element);
+    return element;
+  }
+}
diff --git a/tools/dom/nnbd_src/dart2js_DOMImplementation.dart b/tools/dom/nnbd_src/dart2js_DOMImplementation.dart
new file mode 100644
index 0000000..e45e37c
--- /dev/null
+++ b/tools/dom/nnbd_src/dart2js_DOMImplementation.dart
@@ -0,0 +1,137 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+// TODO(vsm): Unify with Dartium version.
+class _DOMWindowCrossFrame implements WindowBase {
+  // Private window.  Note, this is a window in another frame, so it
+  // cannot be typed as "Window" as its prototype is not patched
+  // properly.  Its fields and methods can only be accessed via JavaScript.
+  final _window;
+
+  // Fields.
+  HistoryBase get history =>
+      _HistoryCrossFrame._createSafe(JS('HistoryBase', '#.history', _window));
+  LocationBase get location => _LocationCrossFrame._createSafe(
+      JS('LocationBase', '#.location', _window));
+
+  // TODO(vsm): Add frames to navigate subframes.  See 2312.
+
+  bool get closed => JS('bool', '#.closed', _window);
+
+  WindowBase get opener => _createSafe(JS('WindowBase', '#.opener', _window));
+
+  WindowBase get parent => _createSafe(JS('WindowBase', '#.parent', _window));
+
+  WindowBase get top => _createSafe(JS('WindowBase', '#.top', _window));
+
+  // Methods.
+  void close() => JS('void', '#.close()', _window);
+
+  void postMessage(var message, String targetOrigin,
+      [List messagePorts = null]) {
+    if (messagePorts == null) {
+      JS('void', '#.postMessage(#,#)', _window,
+          convertDartToNative_SerializedScriptValue(message), targetOrigin);
+    } else {
+      JS(
+          'void',
+          '#.postMessage(#,#,#)',
+          _window,
+          convertDartToNative_SerializedScriptValue(message),
+          targetOrigin,
+          messagePorts);
+    }
+  }
+
+  // Implementation support.
+  _DOMWindowCrossFrame(this._window);
+
+  static WindowBase _createSafe(w) {
+    if (identical(w, window)) {
+      return w;
+    } else {
+      // TODO(vsm): Cache or implement equality.
+      registerGlobalObject(w);
+      return new _DOMWindowCrossFrame(w);
+    }
+  }
+
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  Events get on => throw new UnsupportedError(
+      'You can only attach EventListeners to your own window.');
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  void _addEventListener(String? type, EventListener? listener,
+          [bool? useCapture]) =>
+      throw new UnsupportedError(
+          'You can only attach EventListeners to your own window.');
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  void addEventListener(String type, EventListener listener,
+          [bool useCapture]) =>
+      throw new UnsupportedError(
+          'You can only attach EventListeners to your own window.');
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  bool dispatchEvent(Event event) => throw new UnsupportedError(
+      'You can only attach EventListeners to your own window.');
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  void _removeEventListener(String? type, EventListener? listener,
+          [bool? useCapture]) =>
+      throw new UnsupportedError(
+          'You can only attach EventListeners to your own window.');
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  void removeEventListener(String type, EventListener listener,
+          [bool useCapture]) =>
+      throw new UnsupportedError(
+          'You can only attach EventListeners to your own window.');
+}
+
+class _LocationCrossFrame implements LocationBase {
+  // Private location.  Note, this is a location object in another frame, so it
+  // cannot be typed as "Location" as its prototype is not patched
+  // properly.  Its fields and methods can only be accessed via JavaScript.
+  var _location;
+
+  set href(String val) => _setHref(_location, val);
+  static void _setHref(location, val) {
+    JS('void', '#.href = #', location, val);
+  }
+
+  // Implementation support.
+  _LocationCrossFrame(this._location);
+
+  static LocationBase _createSafe(location) {
+    if (identical(location, window.location)) {
+      return location;
+    } else {
+      // TODO(vsm): Cache or implement equality.
+      return new _LocationCrossFrame(location);
+    }
+  }
+}
+
+class _HistoryCrossFrame implements HistoryBase {
+  // Private history.  Note, this is a history object in another frame, so it
+  // cannot be typed as "History" as its prototype is not patched
+  // properly.  Its fields and methods can only be accessed via JavaScript.
+  var _history;
+
+  void back() => JS('void', '#.back()', _history);
+
+  void forward() => JS('void', '#.forward()', _history);
+
+  void go(int distance) => JS('void', '#.go(#)', _history, distance);
+
+  // Implementation support.
+  _HistoryCrossFrame(this._history);
+
+  static HistoryBase _createSafe(h) {
+    if (identical(h, window.history)) {
+      return h;
+    } else {
+      // TODO(vsm): Cache or implement equality.
+      return new _HistoryCrossFrame(h);
+    }
+  }
+}
diff --git a/tools/dom/nnbd_src/dart2js_KeyEvent.dart b/tools/dom/nnbd_src/dart2js_KeyEvent.dart
new file mode 100644
index 0000000..aca9fd2
--- /dev/null
+++ b/tools/dom/nnbd_src/dart2js_KeyEvent.dart
@@ -0,0 +1,237 @@
+/**
+ * A custom KeyboardEvent that attempts to eliminate cross-browser
+ * inconsistencies, and also provide both keyCode and charCode information
+ * for all key events (when such information can be determined).
+ *
+ * KeyEvent tries to provide a higher level, more polished keyboard event
+ * information on top of the "raw" [KeyboardEvent].
+ *
+ * The mechanics of using KeyEvents is a little different from the underlying
+ * [KeyboardEvent]. To use KeyEvents, you need to create a stream and then add
+ * KeyEvents to the stream, rather than using the [EventTarget.dispatchEvent].
+ * Here's an example usage:
+ *
+ *     // Initialize a stream for the KeyEvents:
+ *     var stream = KeyEvent.keyPressEvent.forTarget(document.body);
+ *     // Start listening to the stream of KeyEvents.
+ *     stream.listen((keyEvent) =>
+ *         window.console.log('KeyPress event detected ${keyEvent.charCode}'));
+ *     ...
+ *     // Add a new KeyEvent of someone pressing the 'A' key to the stream so
+ *     // listeners can know a KeyEvent happened.
+ *     stream.add(new KeyEvent('keypress', keyCode: 65, charCode: 97));
+ *
+ * This class is very much a work in progress, and we'd love to get information
+ * on how we can make this class work with as many international keyboards as
+ * possible. Bugs welcome!
+ */
+class KeyEvent extends _WrappedEvent implements KeyboardEvent {
+  /** The parent KeyboardEvent that this KeyEvent is wrapping and "fixing". */
+  KeyboardEvent _parent;
+
+  /** The "fixed" value of whether the alt key is being pressed. */
+  bool _shadowAltKey;
+
+  /** Calculated value of what the estimated charCode is for this event. */
+  int _shadowCharCode;
+
+  /** Calculated value of what the estimated keyCode is for this event. */
+  int _shadowKeyCode;
+
+  /** Calculated value of what the estimated keyCode is for this event. */
+  int get keyCode => _shadowKeyCode;
+
+  /** Calculated value of what the estimated charCode is for this event. */
+  int get charCode => this.type == 'keypress' ? _shadowCharCode : 0;
+
+  /** Calculated value of whether the alt key is pressed is for this event. */
+  bool get altKey => _shadowAltKey;
+
+  /** Calculated value of what the estimated keyCode is for this event. */
+  int get which => keyCode;
+
+  /** Accessor to the underlying keyCode value is the parent event. */
+  int get _realKeyCode => JS('int', '#.keyCode', _parent);
+
+  /** Accessor to the underlying charCode value is the parent event. */
+  int get _realCharCode => JS('int', '#.charCode', _parent);
+
+  /** Accessor to the underlying altKey value is the parent event. */
+  bool get _realAltKey => JS('bool', '#.altKey', _parent);
+
+  /** Shadows on top of the parent's currentTarget. */
+  EventTarget _currentTarget;
+
+  final InputDeviceCapabilities sourceCapabilities;
+
+  /**
+   * The value we want to use for this object's dispatch. Created here so it is
+   * only invoked once.
+   */
+  static final _keyboardEventDispatchRecord = _makeRecord();
+
+  /** Helper to statically create the dispatch record. */
+  static _makeRecord() {
+    var interceptor = JS_INTERCEPTOR_CONSTANT(KeyboardEvent);
+    return makeLeafDispatchRecord(interceptor);
+  }
+
+  /** Construct a KeyEvent with [parent] as the event we're emulating. */
+  KeyEvent.wrap(KeyboardEvent parent) : super(parent) {
+    _parent = parent;
+    _shadowAltKey = _realAltKey;
+    _shadowCharCode = _realCharCode;
+    _shadowKeyCode = _realKeyCode;
+    _currentTarget = _parent.currentTarget;
+  }
+
+  /** Programmatically create a new KeyEvent (and KeyboardEvent). */
+  factory KeyEvent(String type,
+      {Window view,
+      bool canBubble: true,
+      bool cancelable: true,
+      int keyCode: 0,
+      int charCode: 0,
+      int location: 1,
+      bool ctrlKey: false,
+      bool altKey: false,
+      bool shiftKey: false,
+      bool metaKey: false,
+      EventTarget currentTarget}) {
+    if (view == null) {
+      view = window;
+    }
+
+    var eventObj;
+
+    // Currently this works on everything but Safari. Safari throws an
+    // "Attempting to change access mechanism for an unconfigurable property"
+    // TypeError when trying to do the Object.defineProperty hack, so we avoid
+    // this branch if possible.
+    // Also, if we want this branch to work in FF, we also need to modify
+    // _initKeyboardEvent to also take charCode and keyCode values to
+    // initialize initKeyEvent.
+
+    eventObj = new Event.eventType('KeyboardEvent', type,
+        canBubble: canBubble, cancelable: cancelable);
+
+    // Chromium Hack
+    JS(
+        'void',
+        "Object.defineProperty(#, 'keyCode', {"
+            "  get : function() { return this.keyCodeVal; } })",
+        eventObj);
+    JS(
+        'void',
+        "Object.defineProperty(#, 'which', {"
+            "  get : function() { return this.keyCodeVal; } })",
+        eventObj);
+    JS(
+        'void',
+        "Object.defineProperty(#, 'charCode', {"
+            "  get : function() { return this.charCodeVal; } })",
+        eventObj);
+
+    var keyIdentifier = _convertToHexString(charCode, keyCode);
+    eventObj._initKeyboardEvent(type, canBubble, cancelable, view,
+        keyIdentifier, location, ctrlKey, altKey, shiftKey, metaKey);
+    JS('void', '#.keyCodeVal = #', eventObj, keyCode);
+    JS('void', '#.charCodeVal = #', eventObj, charCode);
+
+    // Tell dart2js that it smells like a KeyboardEvent!
+    setDispatchProperty(eventObj, _keyboardEventDispatchRecord);
+
+    var keyEvent = new KeyEvent.wrap(eventObj);
+    if (keyEvent._currentTarget == null) {
+      keyEvent._currentTarget = currentTarget == null ? window : currentTarget;
+    }
+    return keyEvent;
+  }
+
+  // Currently known to work on all browsers but IE.
+  static bool get canUseDispatchEvent => JS(
+      'bool',
+      '(typeof document.body.dispatchEvent == "function")'
+          '&& document.body.dispatchEvent.length > 0');
+
+  /** The currently registered target for this event. */
+  EventTarget get currentTarget => _currentTarget;
+
+  // This is an experimental method to be sure.
+  static String _convertToHexString(int charCode, int keyCode) {
+    if (charCode != -1) {
+      var hex = charCode.toRadixString(16); // Convert to hexadecimal.
+      StringBuffer sb = new StringBuffer('U+');
+      for (int i = 0; i < 4 - hex.length; i++) sb.write('0');
+      sb.write(hex);
+      return sb.toString();
+    } else {
+      return KeyCode._convertKeyCodeToKeyName(keyCode);
+    }
+  }
+
+  // TODO(efortuna): If KeyEvent is sufficiently successful that we want to make
+  // it the default keyboard event handling, move these methods over to Element.
+  /** Accessor to provide a stream of KeyEvents on the desired target. */
+  static EventStreamProvider<KeyEvent> keyDownEvent =
+      new _KeyboardEventHandler('keydown');
+  /** Accessor to provide a stream of KeyEvents on the desired target. */
+  static EventStreamProvider<KeyEvent> keyUpEvent =
+      new _KeyboardEventHandler('keyup');
+  /** Accessor to provide a stream of KeyEvents on the desired target. */
+  static EventStreamProvider<KeyEvent> keyPressEvent =
+      new _KeyboardEventHandler('keypress');
+
+  String get code => _parent.code;
+  /** True if the ctrl key is pressed during this event. */
+  bool get ctrlKey => _parent.ctrlKey;
+  int get detail => _parent.detail;
+  bool get isComposing => _parent.isComposing;
+  String get key => _parent.key;
+  /**
+   * Accessor to the part of the keyboard that the key was pressed from (one of
+   * KeyLocation.STANDARD, KeyLocation.RIGHT, KeyLocation.LEFT,
+   * KeyLocation.NUMPAD, KeyLocation.MOBILE, KeyLocation.JOYSTICK).
+   */
+  int get location => _parent.location;
+  /** True if the Meta (or Mac command) key is pressed during this event. */
+  bool get metaKey => _parent.metaKey;
+  /** True if the shift key was pressed during this event. */
+  bool get shiftKey => _parent.shiftKey;
+  Window get view => _parent.view;
+  void _initUIEvent(
+      String type, bool canBubble, bool cancelable, Window? view, int detail) {
+    throw new UnsupportedError("Cannot initialize a UI Event from a KeyEvent.");
+  }
+
+  String get _shadowKeyIdentifier => JS('String', '#.keyIdentifier', _parent);
+
+  int get _charCode => charCode;
+  int get _keyCode => keyCode;
+  int get _which => which;
+
+  String get _keyIdentifier {
+    throw new UnsupportedError("keyIdentifier is unsupported.");
+  }
+
+  void _initKeyboardEvent(
+      String type,
+      bool canBubble,
+      bool cancelable,
+      Window view,
+      String keyIdentifier,
+      int location,
+      bool ctrlKey,
+      bool altKey,
+      bool shiftKey,
+      bool metaKey) {
+    throw new UnsupportedError(
+        "Cannot initialize a KeyboardEvent from a KeyEvent.");
+  }
+
+  bool getModifierState(String keyArgument) => throw new UnimplementedError();
+
+  bool get repeat => throw new UnimplementedError();
+  bool get isComposed => throw new UnimplementedError();
+  dynamic get _get_view => throw new UnimplementedError();
+}
diff --git a/tools/dom/nnbd_src/dart2js_Platform.dart b/tools/dom/nnbd_src/dart2js_Platform.dart
new file mode 100644
index 0000000..5988011
--- /dev/null
+++ b/tools/dom/nnbd_src/dart2js_Platform.dart
@@ -0,0 +1,21 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+class Platform {
+  /**
+   * Returns true if dart:typed_data types are supported on this
+   * browser.  If false, using these types will generate a runtime
+   * error.
+   */
+  static final supportsTypedData = JS('bool', '!!(window.ArrayBuffer)');
+
+  /**
+   * Returns true if SIMD types in dart:typed_data types are supported
+   * on this browser.  If false, using these types will generate a runtime
+   * error.
+   */
+  static final supportsSimd = false;
+}
diff --git a/tools/dom/nnbd_src/dart2js_TypedArrayFactoryProvider.dart b/tools/dom/nnbd_src/dart2js_TypedArrayFactoryProvider.dart
new file mode 100644
index 0000000..58112a7
--- /dev/null
+++ b/tools/dom/nnbd_src/dart2js_TypedArrayFactoryProvider.dart
@@ -0,0 +1,154 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+class _TypedArrayFactoryProvider {
+  static ByteData createByteData(int length) => _B8(length);
+  static ByteData createByteData_fromBuffer(ByteBuffer buffer,
+      [int byteOffset = 0, int length]) {
+    if (length == null) return _B8_2(buffer, byteOffset);
+    return _B8_3(buffer, byteOffset, length);
+  }
+
+  static Float32List createFloat32List(int length) => _F32(length);
+  static Float32List createFloat32List_fromList(List<num> list) =>
+      _F32(ensureNative(list));
+  static Float32List createFloat32List_fromBuffer(ByteBuffer buffer,
+      [int byteOffset = 0, int length]) {
+    if (length == null) return _F32_2(buffer, byteOffset);
+    return _F32_3(buffer, byteOffset, length);
+  }
+
+  static Float64List createFloat64List(int length) => _F64(length);
+  static Float64List createFloat64List_fromList(List<num> list) =>
+      _F64(ensureNative(list));
+  static Float64List createFloat64List_fromBuffer(ByteBuffer buffer,
+      [int byteOffset = 0, int length]) {
+    if (length == null) return _F64_2(buffer, byteOffset);
+    return _F64_3(buffer, byteOffset, length);
+  }
+
+  static Int8List createInt8List(int length) => _I8(length);
+  static Int8List createInt8List_fromList(List<num> list) =>
+      _I8(ensureNative(list));
+  static Int8List createInt8List_fromBuffer(ByteBuffer buffer,
+      [int byteOffset = 0, int length]) {
+    if (length == null) return _I8_2(buffer, byteOffset);
+    return _I8_3(buffer, byteOffset, length);
+  }
+
+  static Int16List createInt16List(int length) => _I16(length);
+  static Int16List createInt16List_fromList(List<num> list) =>
+      _I16(ensureNative(list));
+  static Int16List createInt16List_fromBuffer(ByteBuffer buffer,
+      [int byteOffset = 0, int length]) {
+    if (length == null) return _I16_2(buffer, byteOffset);
+    return _I16_3(buffer, byteOffset, length);
+  }
+
+  static Int32List createInt32List(int length) => _I32(length);
+  static Int32List createInt32List_fromList(List<num> list) =>
+      _I32(ensureNative(list));
+  static Int32List createInt32List_fromBuffer(ByteBuffer buffer,
+      [int byteOffset = 0, int length]) {
+    if (length == null) return _I32_2(buffer, byteOffset);
+    return _I32_3(buffer, byteOffset, length);
+  }
+
+  static Uint8List createUint8List(int length) => _U8(length);
+  static Uint8List createUint8List_fromList(List<num> list) =>
+      _U8(ensureNative(list));
+  static Uint8List createUint8List_fromBuffer(ByteBuffer buffer,
+      [int byteOffset = 0, int length]) {
+    if (length == null) return _U8_2(buffer, byteOffset);
+    return _U8_3(buffer, byteOffset, length);
+  }
+
+  static Uint16List createUint16List(int length) => _U16(length);
+  static Uint16List createUint16List_fromList(List<num> list) =>
+      _U16(ensureNative(list));
+  static Uint16List createUint16List_fromBuffer(ByteBuffer buffer,
+      [int byteOffset = 0, int length]) {
+    if (length == null) return _U16_2(buffer, byteOffset);
+    return _U16_3(buffer, byteOffset, length);
+  }
+
+  static Uint32List createUint32List(int length) => _U32(length);
+  static Uint32List createUint32List_fromList(List<num> list) =>
+      _U32(ensureNative(list));
+  static Uint32List createUint32List_fromBuffer(ByteBuffer buffer,
+      [int byteOffset = 0, int length]) {
+    if (length == null) return _U32_2(buffer, byteOffset);
+    return _U32_3(buffer, byteOffset, length);
+  }
+
+  static Uint8ClampedList createUint8ClampedList(int length) => _U8C(length);
+  static Uint8ClampedList createUint8ClampedList_fromList(List<num> list) =>
+      _U8C(ensureNative(list));
+  static Uint8ClampedList createUint8ClampedList_fromBuffer(ByteBuffer buffer,
+      [int byteOffset = 0, int length]) {
+    if (length == null) return _U8C_2(buffer, byteOffset);
+    return _U8C_3(buffer, byteOffset, length);
+  }
+
+  static ByteData _B8(arg) =>
+      JS('ByteData', 'new DataView(new ArrayBuffer(#))', arg);
+  static Float32List _F32(arg) => JS('Float32List', 'new Float32Array(#)', arg);
+  static Float64List _F64(arg) => JS('Float64List', 'new Float64Array(#)', arg);
+  static Int8List _I8(arg) => JS('Int8List', 'new Int8Array(#)', arg);
+  static Int16List _I16(arg) => JS('Int16List', 'new Int16Array(#)', arg);
+  static Int32List _I32(arg) => JS('Int32List', 'new Int32Array(#)', arg);
+  static Uint8List _U8(arg) => JS('Uint8List', 'new Uint8Array(#)', arg);
+  static Uint16List _U16(arg) => JS('Uint16List', 'new Uint16Array(#)', arg);
+  static Uint32List _U32(arg) => JS('Uint32List', 'new Uint32Array(#)', arg);
+  static Uint8ClampedList _U8C(arg) =>
+      JS('Uint8ClampedList', 'new Uint8ClampedArray(#)', arg);
+
+  static ByteData _B8_2(arg1, arg2) =>
+      JS('ByteData', 'new DataView(#, #)', arg1, arg2);
+  static Float32List _F32_2(arg1, arg2) =>
+      JS('Float32List', 'new Float32Array(#, #)', arg1, arg2);
+  static Float64List _F64_2(arg1, arg2) =>
+      JS('Float64List', 'new Float64Array(#, #)', arg1, arg2);
+  static Int8List _I8_2(arg1, arg2) =>
+      JS('Int8List', 'new Int8Array(#, #)', arg1, arg2);
+  static Int16List _I16_2(arg1, arg2) =>
+      JS('Int16List', 'new Int16Array(#, #)', arg1, arg2);
+  static Int32List _I32_2(arg1, arg2) =>
+      JS('Int32List', 'new Int32Array(#, #)', arg1, arg2);
+  static Uint8List _U8_2(arg1, arg2) =>
+      JS('Uint8List', 'new Uint8Array(#, #)', arg1, arg2);
+  static Uint16List _U16_2(arg1, arg2) =>
+      JS('Uint16List', 'new Uint16Array(#, #)', arg1, arg2);
+  static Uint32List _U32_2(arg1, arg2) =>
+      JS('Uint32List', 'new Uint32Array(#, #)', arg1, arg2);
+  static Uint8ClampedList _U8C_2(arg1, arg2) =>
+      JS('Uint8ClampedList', 'new Uint8ClampedArray(#, #)', arg1, arg2);
+
+  static ByteData _B8_3(arg1, arg2, arg3) =>
+      JS('ByteData', 'new DataView(#, #, #)', arg1, arg2, arg3);
+  static Float32List _F32_3(arg1, arg2, arg3) =>
+      JS('Float32List', 'new Float32Array(#, #, #)', arg1, arg2, arg3);
+  static Float64List _F64_3(arg1, arg2, arg3) =>
+      JS('Float64List', 'new Float64Array(#, #, #)', arg1, arg2, arg3);
+  static Int8List _I8_3(arg1, arg2, arg3) =>
+      JS('Int8List', 'new Int8Array(#, #, #)', arg1, arg2, arg3);
+  static Int16List _I16_3(arg1, arg2, arg3) =>
+      JS('Int16List', 'new Int16Array(#, #, #)', arg1, arg2, arg3);
+  static Int32List _I32_3(arg1, arg2, arg3) =>
+      JS('Int32List', 'new Int32Array(#, #, #)', arg1, arg2, arg3);
+  static Uint8List _U8_3(arg1, arg2, arg3) =>
+      JS('Uint8List', 'new Uint8Array(#, #, #)', arg1, arg2, arg3);
+  static Uint16List _U16_3(arg1, arg2, arg3) =>
+      JS('Uint16List', 'new Uint16Array(#, #, #)', arg1, arg2, arg3);
+  static Uint32List _U32_3(arg1, arg2, arg3) =>
+      JS('Uint32List', 'new Uint32Array(#, #, #)', arg1, arg2, arg3);
+  static Uint8ClampedList _U8C_3(arg1, arg2, arg3) => JS(
+      'Uint8ClampedList', 'new Uint8ClampedArray(#, #, #)', arg1, arg2, arg3);
+
+  // Ensures that [list] is a JavaScript Array or a typed array.  If necessary,
+  // copies the list.
+  static ensureNative(List list) => list; // TODO: make sure.
+}
diff --git a/tools/dom/nnbd_src/dart2js_WrappedEvent.dart b/tools/dom/nnbd_src/dart2js_WrappedEvent.dart
new file mode 100644
index 0000000..089b223
--- /dev/null
+++ b/tools/dom/nnbd_src/dart2js_WrappedEvent.dart
@@ -0,0 +1,91 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.html;
+
+/**
+ * Helper class to implement custom events which wrap DOM events.
+ */
+class _WrappedEvent implements Event {
+  final Event wrapped;
+
+  /** The CSS selector involved with event delegation. */
+  String _selector;
+
+  _WrappedEvent(this.wrapped);
+
+  bool get bubbles => wrapped.bubbles;
+
+  bool get cancelable => wrapped.cancelable;
+
+  bool get composed => wrapped.composed;
+
+  EventTarget get currentTarget => wrapped.currentTarget;
+
+  bool get defaultPrevented => wrapped.defaultPrevented;
+
+  int get eventPhase => wrapped.eventPhase;
+
+  bool get isTrusted => wrapped.isTrusted;
+
+  EventTarget get target => wrapped.target;
+
+  double get timeStamp => wrapped.timeStamp;
+
+  String get type => wrapped.type;
+
+  void _initEvent(String type, [bool? bubbles, bool? cancelable]) {
+    throw new UnsupportedError('Cannot initialize this Event.');
+  }
+
+  void preventDefault() {
+    wrapped.preventDefault();
+  }
+
+  void stopImmediatePropagation() {
+    wrapped.stopImmediatePropagation();
+  }
+
+  void stopPropagation() {
+    wrapped.stopPropagation();
+  }
+
+  List<EventTarget> composedPath() => wrapped.composedPath();
+
+  /**
+   * A pointer to the element whose CSS selector matched within which an event
+   * was fired. If this Event was not associated with any Event delegation,
+   * accessing this value will throw an [UnsupportedError].
+   */
+  Element get matchingTarget {
+    if (_selector == null) {
+      throw new UnsupportedError('Cannot call matchingTarget if this Event did'
+          ' not arise as a result of event delegation.');
+    }
+    Element currentTarget = this.currentTarget;
+    Element target = this.target;
+    var matchedTarget;
+    do {
+      if (target.matches(_selector)) return target;
+      target = target.parent;
+    } while (target != null && target != currentTarget.parent);
+    throw new StateError('No selector matched for populating matchedTarget.');
+  }
+
+  /**
+   * This event's path, taking into account shadow DOM.
+   *
+   * ## Other resources
+   *
+   * * [Shadow DOM extensions to
+   *   Event](http://w3c.github.io/webcomponents/spec/shadow/#extensions-to-event)
+   *   from W3C.
+   */
+  // https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#extensions-to-event
+  List<Node> get path => wrapped.path;
+
+  dynamic get _get_currentTarget => wrapped._get_currentTarget;
+
+  dynamic get _get_target => wrapped._get_target;
+}
diff --git a/tools/dom/nnbd_src/native_DOMImplementation.dart b/tools/dom/nnbd_src/native_DOMImplementation.dart
new file mode 100644
index 0000000..6f197d0
--- /dev/null
+++ b/tools/dom/nnbd_src/native_DOMImplementation.dart
@@ -0,0 +1,1399 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+class _Property {
+  _Property(this.name)
+      : _hasValue = false,
+        writable = false,
+        isMethod = false,
+        isOwn = true,
+        wasThrown = false;
+
+  bool get hasValue => _hasValue;
+  get value => _value;
+  set value(v) {
+    _value = v;
+    _hasValue = true;
+  }
+
+  final String name;
+  Function setter;
+  Function getter;
+  var _value;
+  bool _hasValue;
+  bool writable;
+  bool isMethod;
+  bool isOwn;
+  bool wasThrown;
+}
+
+/**
+ * Manager for navigating between libraries from the devtools console.
+ */
+class _LibraryManager {
+  /**
+   * Current active library
+   */
+  static var _currentLibrary;
+  static var _validCache = false;
+
+  static List<Uri> _libraryUris;
+
+  // List of all maps to check to determine if there is an exact match.
+  static Map<String, List<Uri>> _fastPaths;
+
+  static void _addFastPath(String key, Uri uri) {
+    _fastPaths.putIfAbsent(key, () => <Uri>[]).add(uri);
+  }
+
+  static cache() {
+    if (_validCache) return;
+    _validCache = true;
+    _libraryUris = <Uri>[];
+    _fastPaths = new Map<String, List<Uri>>();
+    var system = currentMirrorSystem();
+    system.libraries.forEach((uri, library) {
+      _libraryUris.add(uri);
+      _addFastPath(uri.toString(), uri);
+      _addFastPath(MirrorSystem.getName(library.simpleName), uri);
+    });
+  }
+
+  static String get currentLibrary {
+    if (_currentLibrary == null) {
+      _currentLibrary =
+          currentMirrorSystem().isolate.rootLibrary.uri.toString();
+    }
+    return _currentLibrary;
+  }
+
+  /**
+   * Find libraries matching a given name.
+   *
+   * Uses heuristics to only return a single match when the user intent is
+   * generally unambiguous.
+   */
+  static List<Uri> findMatches(String name) {
+    cache();
+    var nameAsFile = name.endsWith('.dart') ? name : '${name}.dart';
+    // Perfect match first.
+    var fastPatchMatches = _fastPaths[name];
+    if (fastPatchMatches != null) {
+      return fastPatchMatches.toList();
+    }
+
+    // Exact match for file path.
+    var matches = new LinkedHashSet<Uri>();
+    for (var uri in _libraryUris) {
+      if (uri.path == name || uri.path == nameAsFile) matches.add(uri);
+    }
+    if (matches.isNotEmpty) return matches.toList();
+
+    // Exact match for file name.
+    if (name != nameAsFile) {
+      for (var uri in _libraryUris) {
+        if (uri.pathSegments.isNotEmpty &&
+            (uri.pathSegments.last == nameAsFile)) {
+          matches.add(uri);
+        }
+      }
+      if (matches.isNotEmpty) return matches.toList();
+    }
+
+    for (var uri in _libraryUris) {
+      if (uri.pathSegments.isNotEmpty && (uri.pathSegments.last == name)) {
+        matches.add(uri);
+      }
+    }
+    if (matches.isNotEmpty) return matches.toList();
+
+    // Partial match on path.
+    for (var uri in _libraryUris) {
+      if (uri.path.contains(name)) {
+        matches.add(uri);
+      }
+    }
+    if (matches.isNotEmpty) return matches.toList();
+
+    // Partial match on entire uri.
+    for (var uri in _libraryUris) {
+      if (uri.toString().contains(name)) {
+        matches.add(uri);
+      }
+    }
+
+    if (matches.isNotEmpty) return matches.toList();
+
+    // Partial match on entire uri ignoring case.
+    name = name.toLowerCase();
+    for (var uri in _libraryUris) {
+      if (uri.toString().toLowerCase().contains(name)) {
+        matches.add(uri);
+      }
+    }
+    return matches.toList();
+  }
+
+  static setLibrary([String name]) {
+    // Bust cache in case library list has changed. Ideally we would listen for
+    // when libraries are loaded and invalidate based on that.
+    _validCache = false;
+    cache();
+    if (name == null) {
+      window.console
+        ..group("Current library: $_currentLibrary")
+        ..groupCollapsed("All libraries:");
+      _listLibraries();
+      window.console..groupEnd()..groupEnd();
+      return;
+    }
+    var matches = findMatches(name);
+    if (matches.length != 1) {
+      if (matches.length > 1) {
+        window.console.warn("Ambiguous library name: $name");
+      }
+      showMatches(name, matches);
+      return;
+    }
+    _currentLibrary = matches.first.toString();
+    window.console.log("Set library to $_currentLibrary");
+  }
+
+  static getLibrary() {
+    return currentLibrary;
+  }
+
+  static List<Uri> _sortUris(Iterable<Uri> uris) {
+    return (uris.toList())
+      ..sort((Uri a, Uri b) {
+        if (a.scheme != b.scheme) {
+          if (a.scheme == 'dart') return -1;
+          if (b.scheme == 'dart') return 1;
+          return a.scheme.compareTo(b.scheme);
+        }
+        return a.toString().compareTo(b.toString());
+      });
+  }
+
+  static void listLibraries() {
+    _validCache = false;
+    cache();
+    _listLibraries();
+  }
+
+  static void _listLibraries() {
+    window.console.log(_sortUris(_libraryUris).join("\n"));
+  }
+
+  // Workaround to allow calling console.log with an arbitrary number of
+  // arguments.
+  static void _log(List<String> args) {
+    js.JsNative.callMethod(window.console, 'log', args);
+  }
+
+  static showMatches(String key, Iterable<Uri> uris) {
+    var boldPairs = [];
+    var sb = new StringBuffer();
+    if (uris.isEmpty) {
+      window.console.group("All libraries:");
+      _listLibraries();
+      window.console
+        ..groupEnd()
+        ..error("No library names or URIs match '$key'");
+      return;
+    }
+    sb.write("${uris.length} matches\n");
+    var lowerCaseKey = key.toLowerCase();
+    for (var uri in uris) {
+      var txt = uri.toString();
+      int index = txt.toLowerCase().indexOf(lowerCaseKey);
+      if (index != -1) {
+        // %c enables styling console log messages with css
+        // specified at the end of the console.
+        sb..write(txt.substring(0, index))..write('%c');
+        var matchEnd = index + key.length;
+        sb
+          ..write(txt.substring(index, matchEnd))
+          ..write('%c')
+          ..write(txt.substring(matchEnd))
+          ..write('\n');
+        boldPairs..add('font-weight: bold')..add('font-weight: normal');
+      }
+    }
+    _log([sb.toString()]..addAll(boldPairs));
+  }
+}
+
+class _ConsoleVariables {
+  Map<String, Object> _data = new Map<String, Object>();
+
+  /**
+   * Forward member accesses to the backing JavaScript object.
+   */
+  noSuchMethod(Invocation invocation) {
+    String member = MirrorSystem.getName(invocation.memberName);
+    if (invocation.isGetter) {
+      return _data[member];
+    } else if (invocation.isSetter) {
+      assert(member.endsWith('='));
+      member = member.substring(0, member.length - 1);
+      _data[member] = invocation.positionalArguments[0];
+    } else {
+      return Function.apply(_data[member], invocation.positionalArguments,
+          invocation.namedArguments);
+    }
+  }
+
+  void clear() => _data.clear();
+
+  /**
+   * List all variables currently defined.
+   */
+  List variables() => _data.keys.toList();
+
+  void setVariable(String name, value) {
+    _data[name] = value;
+  }
+}
+
+/**
+ * Base class for invocation trampolines used to closurize methods, getters
+ * and setters.
+ */
+abstract class _Trampoline implements Function {
+  final ObjectMirror _receiver;
+  final MethodMirror _methodMirror;
+  final Symbol _selector;
+
+  _Trampoline(this._receiver, this._methodMirror, this._selector);
+}
+
+class _MethodTrampoline extends _Trampoline {
+  _MethodTrampoline(
+      ObjectMirror receiver, MethodMirror methodMirror, Symbol selector)
+      : super(receiver, methodMirror, selector);
+
+  noSuchMethod(Invocation msg) {
+    if (msg.memberName != #call) return super.noSuchMethod(msg);
+    return _receiver
+        .invoke(_selector, msg.positionalArguments, msg.namedArguments)
+        .reflectee;
+  }
+}
+
+/**
+ * Invocation trampoline class used to closurize getters.
+ */
+class _GetterTrampoline extends _Trampoline {
+  _GetterTrampoline(
+      ObjectMirror receiver, MethodMirror methodMirror, Symbol selector)
+      : super(receiver, methodMirror, selector);
+
+  call() => _receiver.getField(_selector).reflectee;
+}
+
+/**
+ * Invocation trampoline class used to closurize setters.
+ */
+class _SetterTrampoline extends _Trampoline {
+  _SetterTrampoline(
+      ObjectMirror receiver, MethodMirror methodMirror, Symbol selector)
+      : super(receiver, methodMirror, selector);
+
+  call(value) {
+    _receiver.setField(_selector, value);
+  }
+}
+
+class _Utils {
+  static double dateTimeToDouble(DateTime dateTime) =>
+      dateTime.millisecondsSinceEpoch.toDouble();
+  static DateTime doubleToDateTime(double dateTime) {
+    try {
+      return new DateTime.fromMillisecondsSinceEpoch(dateTime.toInt());
+    } catch (_) {
+      // TODO(antonnm): treat exceptions properly in bindings and
+      // find out how to treat NaNs.
+      return null;
+    }
+  }
+
+  static List convertToList(List list) {
+    // FIXME: [possible optimization]: do not copy the array if Dart_IsArray is fine w/ it.
+    final length = list.length;
+    List result = new List(length);
+    result.setRange(0, length, list);
+    return result;
+  }
+
+  static List convertMapToList(Map map) {
+    List result = [];
+    map.forEach((k, v) => result.addAll([k, v]));
+    return result;
+  }
+
+  static int convertCanvasElementGetContextMap(Map map) {
+    int result = 0;
+    if (map['alpha'] == true) result |= 0x01;
+    if (map['depth'] == true) result |= 0x02;
+    if (map['stencil'] == true) result |= 0x4;
+    if (map['antialias'] == true) result |= 0x08;
+    if (map['premultipliedAlpha'] == true) result |= 0x10;
+    if (map['preserveDrawingBuffer'] == true) result |= 0x20;
+
+    return result;
+  }
+
+  static void populateMap(Map result, List list) {
+    for (int i = 0; i < list.length; i += 2) {
+      result[list[i]] = list[i + 1];
+    }
+  }
+
+  static bool isMap(obj) => obj is Map;
+
+  static List toListIfIterable(obj) => obj is Iterable ? obj.toList() : null;
+
+  static Map createMap() => {};
+
+  static parseJson(String jsonSource) =>
+      const JsonDecoder().convert(jsonSource);
+
+  static String getLibraryUrl() => _LibraryManager.currentLibrary;
+
+  static makeUnimplementedError(String fileName, int lineNo) {
+    return new UnsupportedError('[info: $fileName:$lineNo]');
+  }
+
+  static bool isTypeSubclassOf(Type type, Type other) {
+    if (type == other) {
+      return true;
+    }
+    var superclass = reflectClass(type).superclass;
+    if (superclass != null) {
+      return isTypeSubclassOf(superclass.reflectedType, other);
+    }
+    return false;
+  }
+
+  static Element getAndValidateNativeType(Type type, String tagName) {
+    var element = new Element.tag(tagName);
+    if (!isTypeSubclassOf(type, element.runtimeType)) {
+      return null;
+    }
+    return element;
+  }
+
+  static forwardingPrint(String message) =>
+      _blink.Blink_Utils.forwardingPrint(message);
+  static void spawnDomHelper(Function f, int replyTo) =>
+      _blink.Blink_Utils.spawnDomHelper(f, replyTo);
+
+  // TODO(vsm): Make this API compatible with spawnUri.  It should also
+  // return a Future<Isolate>.
+  // TODO(jacobr): IS THIS RIGHT? I worry we have broken conversion from Promise to Future.
+  static spawnDomUri(String uri) => _blink.Blink_Utils.spawnDomUri(uri);
+
+  // The following methods were added for debugger integration to make working
+  // with the Dart C mirrors API simpler.
+  // TODO(jacobr): consider moving them to a separate library.
+  // If Dart supported dynamic code injection, we would only inject this code
+  // when the debugger is invoked.
+
+  /**
+   * Strips the private secret prefix from member names of the form
+   * someName@hash.
+   */
+  static String stripMemberName(String name) {
+    int endIndex = name.indexOf('@');
+    return endIndex > 0 ? name.substring(0, endIndex) : name;
+  }
+
+  /**
+   * Takes a list containing variable names and corresponding values and
+   * returns a map from normalized names to values. Variable names are assumed
+   * to have list offsets 2*n values at offset 2*n+1. This method is required
+   * because Dart_GetLocalVariables returns a list instead of an object that
+   * can be queried to lookup names and values.
+   */
+  static Map<String, dynamic> createLocalVariablesMap(List localVariables) {
+    var map = {};
+    for (int i = 0; i < localVariables.length; i += 2) {
+      map[stripMemberName(localVariables[i])] = localVariables[i + 1];
+    }
+    return map;
+  }
+
+  static _ConsoleVariables _consoleTempVariables = new _ConsoleVariables();
+
+  /**
+   * Takes an [expression] and a list of [local] variable and returns an
+   * expression for a closure with a body matching the original expression
+   * where locals are passed in as arguments. Returns a list containing the
+   * String expression for the closure and the list of arguments that should
+   * be passed to it. The expression should then be evaluated using
+   * Dart_EvaluateExpr which will generate a closure that should be invoked
+   * with the list of arguments passed to this method.
+   *
+   * For example:
+   * <code>
+   * _consoleTempVariables = {'a' : someValue, 'b': someOtherValue}
+   * wrapExpressionAsClosure("foo + bar + a", ["bar", 40, "foo", 2], true)
+   * </code>
+   * will return:
+   * <code>
+   * ["""(final $consoleVariables, final bar, final foo, final a, final b) =>
+   * (foo + bar + a
+   * )""",
+   * [_consoleTempVariables, 40, 2, someValue, someOtherValue]]
+   * </code>
+   */
+  static List wrapExpressionAsClosure(
+      String expression, List locals, bool includeCommandLineAPI) {
+    var args = {};
+    var sb = new StringBuffer("(");
+    addArg(arg, value) {
+      arg = stripMemberName(arg);
+      if (args.containsKey(arg)) return;
+      // We ignore arguments with the name 'this' rather than throwing an
+      // exception because Dart_GetLocalVariables includes 'this' and it
+      // is more convenient to filter it out here than from C++ code.
+      // 'this' needs to be handled by calling Dart_EvaluateExpr with
+      // 'this' as the target rather than by passing it as an argument.
+      if (arg == 'this') return;
+      // Avoid being broken by bogus ':async_op' local passed in when within
+      // an async method.
+      if (arg.startsWith(':')) return;
+      if (args.isNotEmpty) {
+        sb.write(", ");
+      }
+      sb.write("final $arg");
+      args[arg] = value;
+    }
+
+    if (includeCommandLineAPI) {
+      addArg("\$consoleVariables", _consoleTempVariables);
+
+      // FIXME: use a real Dart tokenizer. The following regular expressions
+      // only allow setting variables at the immediate start of the expression
+      // to limit the number of edge cases we have to handle.
+
+      // Match expressions that start with "var x"
+      final _VARIABLE_DECLARATION = new RegExp("^(\\s*)var\\s+(\\w+)");
+      // Match expressions that start with "someExistingConsoleVar ="
+      final _SET_VARIABLE = new RegExp("^(\\s*)(\\w+)(\\s*=)");
+      // Match trailing semicolons.
+      final _ENDING_SEMICOLONS = new RegExp("(;\\s*)*\$");
+      expression = expression.replaceAllMapped(_VARIABLE_DECLARATION, (match) {
+        var variableName = match[2];
+        // Set the console variable if it isn't already set.
+        if (!_consoleTempVariables._data.containsKey(variableName)) {
+          _consoleTempVariables._data[variableName] = null;
+        }
+        return "${match[1]}\$consoleVariables.${variableName}";
+      });
+
+      expression = expression.replaceAllMapped(_SET_VARIABLE, (match) {
+        var variableName = match[2];
+        // Only rewrite if the name matches an existing console variable.
+        if (_consoleTempVariables._data.containsKey(variableName)) {
+          return "${match[1]}\$consoleVariables.${variableName}${match[3]}";
+        } else {
+          return match[0];
+        }
+      });
+
+      // We only allow dart expressions not Dart statements. Silently remove
+      // trailing semicolons the user might have added by accident to reduce the
+      // number of spurious compile errors.
+      expression = expression.replaceFirst(_ENDING_SEMICOLONS, "");
+    }
+
+    if (locals != null) {
+      for (int i = 0; i < locals.length; i += 2) {
+        addArg(locals[i], locals[i + 1]);
+      }
+    }
+    // Inject all the already defined console variables.
+    _consoleTempVariables._data.forEach(addArg);
+
+    // TODO(jacobr): remove the parentheses around the expression once
+    // dartbug.com/13723 is fixed. Currently we wrap expression in parentheses
+    // to ensure only valid Dart expressions are allowed. Otherwise the DartVM
+    // quietly ignores trailing Dart statements resulting in user confusion
+    // when part of an invalid expression they entered is ignored.
+    sb..write(') => (\n$expression\n)');
+    return [sb.toString(), args.values.toList(growable: false)];
+  }
+
+  static String _getShortSymbolName(
+      Symbol symbol, DeclarationMirror declaration) {
+    var name = MirrorSystem.getName(symbol);
+    if (declaration is MethodMirror) {
+      if (declaration.isSetter && name[name.length - 1] == "=") {
+        return name.substring(0, name.length - 1);
+      }
+      if (declaration.isConstructor) {
+        return name.substring(name.indexOf('.') + 1);
+      }
+    }
+    return name;
+  }
+
+  /**
+   * Handle special console commands such as $lib and $libs that should not be
+   * evaluated as Dart expressions and instead should be interpreted directly.
+   * Commands supported:
+   * library <-- shows the current library and lists all libraries.
+   * library "library_uri" <-- select a specific library
+   * library "library_uri_fragment"
+   */
+  static bool maybeHandleSpecialConsoleCommand(String expression) {
+    expression = expression.trim();
+    var setLibraryCommand = r'library ';
+    if (expression == r'library') {
+      _LibraryManager.setLibrary();
+      return true;
+    }
+    if (expression.startsWith(setLibraryCommand)) {
+      expression = expression.substring(setLibraryCommand.length);
+      if (expression.length >= 2) {
+        String start = expression[0];
+        String end = expression[expression.length - 1];
+        // TODO(jacobr): maybe we should require quotes.
+        if ((start == "'" && end == "'") || (start == '"' && end == '"')) {
+          expression = expression.substring(1, expression.length - 1);
+        }
+      }
+
+      _LibraryManager.setLibrary(expression);
+      return true;
+    }
+    return false;
+  }
+
+  /**
+   * Returns a list of completions to use if the receiver is o.
+   */
+  static List<String> getCompletions(o) {
+    MirrorSystem system = currentMirrorSystem();
+    var completions = new Set<String>();
+    addAll(Map<Symbol, dynamic> map, bool isStatic) {
+      map.forEach((symbol, mirror) {
+        if (mirror.isStatic == isStatic && !mirror.isPrivate) {
+          var name = MirrorSystem.getName(symbol);
+          if (mirror is MethodMirror && mirror.isSetter)
+            name = name.substring(0, name.length - 1);
+          completions.add(name);
+        }
+      });
+    }
+
+    addForClass(ClassMirror mirror, bool isStatic) {
+      if (mirror == null) return;
+      addAll(mirror.declarations, isStatic);
+      if (mirror.superclass != null) addForClass(mirror.superclass, isStatic);
+      for (var interface in mirror.superinterfaces) {
+        addForClass(interface, isStatic);
+      }
+    }
+
+    if (o is Type) {
+      addForClass(reflectClass(o), true);
+    } else {
+      addForClass(reflect(o).type, false);
+    }
+    return completions.toList(growable: false);
+  }
+
+  /**
+   * Adds all candidate String completions from [declarations] to [output]
+   * filtering based on [staticContext] and [includePrivate].
+   */
+  static void _getCompletionsHelper(ClassMirror classMirror, bool staticContext,
+      LibraryMirror libraryMirror, Set<String> output) {
+    bool includePrivate = libraryMirror == classMirror.owner;
+    classMirror.declarations.forEach((symbol, declaration) {
+      if (!includePrivate && declaration.isPrivate) return;
+      if (declaration is VariableMirror) {
+        if (staticContext != declaration.isStatic) return;
+      } else if (declaration is MethodMirror) {
+        if (declaration.isOperator) return;
+        if (declaration.isConstructor) {
+          if (!staticContext) return;
+          var name = MirrorSystem.getName(declaration.constructorName);
+          if (name.isNotEmpty) output.add(name);
+          return;
+        }
+        if (staticContext != declaration.isStatic) return;
+      } else if (declaration is TypeMirror) {
+        return;
+      }
+      output.add(_getShortSymbolName(symbol, declaration));
+    });
+
+    if (!staticContext) {
+      for (var interface in classMirror.superinterfaces) {
+        _getCompletionsHelper(interface, staticContext, libraryMirror, output);
+      }
+      if (classMirror.superclass != null) {
+        _getCompletionsHelper(
+            classMirror.superclass, staticContext, libraryMirror, output);
+      }
+    }
+  }
+
+  static void _getLibraryCompletionsHelper(
+      LibraryMirror library, bool includePrivate, Set<String> output) {
+    library.declarations.forEach((symbol, declaration) {
+      if (!includePrivate && declaration.isPrivate) return;
+      output.add(_getShortSymbolName(symbol, declaration));
+    });
+  }
+
+  static LibraryMirror getLibraryMirror(String url) =>
+      currentMirrorSystem().libraries[Uri.parse(url)];
+
+  /**
+   * Get code completions for [o] only showing privates from [libraryUrl].
+   */
+  static List<String> getObjectCompletions(o, String libraryUrl) {
+    var classMirror;
+    bool staticContext;
+    if (o is Type) {
+      classMirror = reflectClass(o);
+      staticContext = true;
+    } else {
+      classMirror = reflect(o).type;
+      staticContext = false;
+    }
+    var names = new Set<String>();
+    getClassCompletions(classMirror, names, staticContext, libraryUrl);
+    return names.toList()..sort();
+  }
+
+  static void getClassCompletions(ClassMirror classMirror, Set<String> names,
+      bool staticContext, String libraryUrl) {
+    LibraryMirror libraryMirror = getLibraryMirror(libraryUrl);
+    _getCompletionsHelper(classMirror, staticContext, libraryMirror, names);
+  }
+
+  static List<String> getLibraryCompletions(String url) {
+    var names = new Set<String>();
+    _getLibraryCompletionsHelper(getLibraryMirror(url), true, names);
+    return names.toList();
+  }
+
+  /**
+   * Get valid code completions from within a library and all libraries
+   * imported by that library.
+   */
+  static List<String> getLibraryCompletionsIncludingImports(String url) {
+    var names = new Set<String>();
+    var libraryMirror = getLibraryMirror(url);
+    _getLibraryCompletionsHelper(libraryMirror, true, names);
+    for (var dependency in libraryMirror.libraryDependencies) {
+      if (dependency.isImport) {
+        if (dependency.prefix == null) {
+          _getLibraryCompletionsHelper(dependency.targetLibrary, false, names);
+        } else {
+          names.add(MirrorSystem.getName(dependency.prefix));
+        }
+      }
+    }
+    return names.toList();
+  }
+
+  static final SIDE_EFFECT_FREE_LIBRARIES = new Set<String>()
+    ..add('dart:html')
+    ..add('dart:indexed_db')
+    ..add('dart:svg')
+    ..add('dart:typed_data')
+    ..add('dart:web_audio')
+    ..add('dart:web_gl')
+    ..add('dart:web_sql');
+
+  static LibraryMirror _getLibrary(MethodMirror methodMirror) {
+    var owner = methodMirror.owner;
+    if (owner is ClassMirror) {
+      return owner;
+    } else if (owner is LibraryMirror) {
+      return owner;
+    }
+    return null;
+  }
+
+  /**
+   * For parity with the JavaScript debugger, we treat some getters as if
+   * they are fields so that users can see their values immediately.
+   * This matches JavaScript's behavior for getters on DOM objects.
+   * In the future we should consider adding an annotation to tag getters
+   * in user libraries as side effect free.
+   */
+  static bool _isSideEffectFreeGetter(
+      MethodMirror methodMirror, LibraryMirror libraryMirror) {
+    // This matches JavaScript behavior. We should consider displaying
+    // getters for all dart platform libraries rather than just the DOM
+    // libraries.
+    return libraryMirror.uri.scheme == 'dart' &&
+        SIDE_EFFECT_FREE_LIBRARIES.contains(libraryMirror.uri.toString());
+  }
+
+  /**
+   * Whether we should treat a property as a field for the purposes of the
+   * debugger.
+   */
+  static bool treatPropertyAsField(
+      MethodMirror methodMirror, LibraryMirror libraryMirror) {
+    return (methodMirror.isGetter || methodMirror.isSetter) &&
+        (methodMirror.isSynthetic ||
+            _isSideEffectFreeGetter(methodMirror, libraryMirror));
+  }
+
+  // TODO(jacobr): generate more concise function descriptions instead of
+  // dumping the entire function source.
+  static String describeFunction(function) {
+    if (function is _Trampoline) return function._methodMirror.source;
+    try {
+      var mirror = reflect(function);
+      return mirror.function.source;
+    } catch (e) {
+      return function.toString();
+    }
+  }
+
+  static List getInvocationTrampolineDetails(_Trampoline method) {
+    var loc = method._methodMirror.location;
+    return [
+      loc.line,
+      loc.column,
+      loc.sourceUri.toString(),
+      MirrorSystem.getName(method._selector)
+    ];
+  }
+
+  static List getLibraryProperties(
+      String libraryUrl, bool ownProperties, bool accessorPropertiesOnly) {
+    var properties = new Map<String, _Property>();
+    var libraryMirror = getLibraryMirror(libraryUrl);
+    _addInstanceMirrors(
+        libraryMirror,
+        libraryMirror,
+        libraryMirror.declarations,
+        ownProperties,
+        accessorPropertiesOnly,
+        false,
+        false,
+        properties);
+    if (!accessorPropertiesOnly) {
+      // We need to add class properties for all classes in the library.
+      libraryMirror.declarations.forEach((symbol, declarationMirror) {
+        if (declarationMirror is ClassMirror) {
+          var name = MirrorSystem.getName(symbol);
+          if (declarationMirror.hasReflectedType &&
+              !properties.containsKey(name)) {
+            properties[name] = new _Property(name)
+              ..value = declarationMirror.reflectedType;
+          }
+        }
+      });
+    }
+    return packageProperties(properties);
+  }
+
+  static List getObjectProperties(
+      o, bool ownProperties, bool accessorPropertiesOnly) {
+    var properties = new Map<String, _Property>();
+    var names = new Set<String>();
+    var objectMirror = reflect(o);
+    var classMirror = objectMirror.type;
+    _addInstanceMirrors(
+        objectMirror,
+        classMirror.owner,
+        classMirror.instanceMembers,
+        ownProperties,
+        accessorPropertiesOnly,
+        false,
+        true,
+        properties);
+    return packageProperties(properties);
+  }
+
+  static List getObjectClassProperties(
+      o, bool ownProperties, bool accessorPropertiesOnly) {
+    var properties = new Map<String, _Property>();
+    var objectMirror = reflect(o);
+    var classMirror = objectMirror.type;
+    _addInstanceMirrors(
+        objectMirror,
+        classMirror.owner,
+        classMirror.instanceMembers,
+        ownProperties,
+        accessorPropertiesOnly,
+        true,
+        false,
+        properties);
+    _addStatics(classMirror, properties, accessorPropertiesOnly);
+    return packageProperties(properties);
+  }
+
+  static List getClassProperties(
+      Type t, bool ownProperties, bool accessorPropertiesOnly) {
+    var properties = new Map<String, _Property>();
+    var classMirror = reflectClass(t);
+    _addStatics(classMirror, properties, accessorPropertiesOnly);
+    return packageProperties(properties);
+  }
+
+  static void _addStatics(ClassMirror classMirror,
+      Map<String, _Property> properties, bool accessorPropertiesOnly) {
+    var libraryMirror = classMirror.owner;
+    classMirror.declarations.forEach((symbol, declaration) {
+      var name = _getShortSymbolName(symbol, declaration);
+      if (name.isEmpty) return;
+      if (declaration is VariableMirror) {
+        if (accessorPropertiesOnly) return;
+        if (!declaration.isStatic) return;
+        properties.putIfAbsent(name, () => new _Property(name))
+          ..value = classMirror.getField(symbol).reflectee
+          ..writable = !declaration.isFinal && !declaration.isConst;
+      } else if (declaration is MethodMirror) {
+        MethodMirror methodMirror = declaration;
+        // FIXMEDART: should we display constructors?
+        if (methodMirror.isConstructor) return;
+        if (!methodMirror.isStatic) return;
+        if (accessorPropertiesOnly) {
+          if (methodMirror.isRegularMethod ||
+              treatPropertyAsField(methodMirror, libraryMirror)) {
+            return;
+          }
+        } else if (!methodMirror.isRegularMethod &&
+            !treatPropertyAsField(methodMirror, libraryMirror)) {
+          return;
+        }
+        var property = properties.putIfAbsent(name, () => new _Property(name));
+        _fillMethodMirrorProperty(libraryMirror, classMirror, methodMirror,
+            symbol, accessorPropertiesOnly, property);
+      }
+    });
+  }
+
+  static void _fillMethodMirrorProperty(
+      LibraryMirror libraryMirror,
+      methodOwner,
+      MethodMirror methodMirror,
+      Symbol symbol,
+      bool accessorPropertiesOnly,
+      _Property property) {
+    if (methodMirror.isRegularMethod) {
+      property
+        ..value = new _MethodTrampoline(methodOwner, methodMirror, symbol)
+        ..isMethod = true;
+    } else if (methodMirror.isGetter) {
+      if (treatPropertyAsField(methodMirror, libraryMirror)) {
+        try {
+          property.value = methodOwner.getField(symbol).reflectee;
+        } catch (e) {
+          property
+            ..wasThrown = true
+            ..value = e;
+        }
+      } else if (accessorPropertiesOnly) {
+        property.getter =
+            new _GetterTrampoline(methodOwner, methodMirror, symbol);
+      }
+    } else if (methodMirror.isSetter) {
+      if (accessorPropertiesOnly &&
+          !treatPropertyAsField(methodMirror, libraryMirror)) {
+        property.setter = new _SetterTrampoline(methodOwner, methodMirror,
+            MirrorSystem.getSymbol(property.name, libraryMirror));
+      }
+      property.writable = true;
+    }
+  }
+
+  /**
+   * Helper method that handles collecting up properties from classes
+   * or libraries using the filters [ownProperties], [accessorPropertiesOnly],
+   * [hideFields], and [hideMethods] to determine which properties are
+   * collected. [accessorPropertiesOnly] specifies whether all properties
+   * should be returned or just accessors. [hideFields] specifies whether
+   * fields should be hidden. hideMethods specifies whether methods should be
+   * shown or hidden. [ownProperties] is not currently used but is part of the
+   * Blink devtools API for enumerating properties.
+   */
+  static void _addInstanceMirrors(
+      ObjectMirror objectMirror,
+      LibraryMirror libraryMirror,
+      Map<Symbol, Mirror> declarations,
+      bool ownProperties,
+      bool accessorPropertiesOnly,
+      bool hideFields,
+      bool hideMethods,
+      Map<String, _Property> properties) {
+    declarations.forEach((symbol, declaration) {
+      if (declaration is TypedefMirror || declaration is ClassMirror) return;
+      var name = _getShortSymbolName(symbol, declaration);
+      if (name.isEmpty) return;
+      bool isField = declaration is VariableMirror ||
+          (declaration is MethodMirror &&
+              treatPropertyAsField(declaration, libraryMirror));
+      if ((isField && hideFields) || (hideMethods && !isField)) return;
+      if (accessorPropertiesOnly) {
+        if (declaration is VariableMirror ||
+            declaration.isRegularMethod ||
+            isField) {
+          return;
+        }
+      } else if (declaration is MethodMirror &&
+          (declaration.isGetter || declaration.isSetter) &&
+          !treatPropertyAsField(declaration, libraryMirror)) {
+        return;
+      }
+      var property = properties.putIfAbsent(name, () => new _Property(name));
+      if (declaration is VariableMirror) {
+        property
+          ..value = objectMirror.getField(symbol).reflectee
+          ..writable = !declaration.isFinal && !declaration.isConst;
+        return;
+      }
+      _fillMethodMirrorProperty(libraryMirror, objectMirror, declaration,
+          symbol, accessorPropertiesOnly, property);
+    });
+  }
+
+  /**
+   * Flatten down the properties data structure into a List that is easy to
+   * access from native code.
+   */
+  static List packageProperties(Map<String, _Property> properties) {
+    var ret = [];
+    for (var property in properties.values) {
+      ret.addAll([
+        property.name,
+        property.setter,
+        property.getter,
+        property.value,
+        property.hasValue,
+        property.writable,
+        property.isMethod,
+        property.isOwn,
+        property.wasThrown
+      ]);
+    }
+    return ret;
+  }
+
+  /**
+   * Get a property, returning null if the property does not exist.
+   * For private property names, we attempt to resolve the property in the
+   * context of each library that the property name could be associated with.
+   */
+  static getObjectPropertySafe(o, String propertyName) {
+    var objectMirror = reflect(o);
+    var classMirror = objectMirror.type;
+    if (propertyName.startsWith("_")) {
+      var attemptedLibraries = new Set<LibraryMirror>();
+      while (classMirror != null) {
+        LibraryMirror library = classMirror.owner;
+        if (!attemptedLibraries.contains(library)) {
+          try {
+            return objectMirror
+                .getField(MirrorSystem.getSymbol(propertyName, library))
+                .reflectee;
+          } catch (e) {}
+          attemptedLibraries.add(library);
+        }
+        classMirror = classMirror.superclass;
+      }
+      return null;
+    }
+    try {
+      return objectMirror
+          .getField(MirrorSystem.getSymbol(propertyName))
+          .reflectee;
+    } catch (e) {
+      return null;
+    }
+  }
+
+  /**
+   * Helper to wrap the inspect method on InjectedScriptHost to provide the
+   * inspect method required for the
+   */
+  static List consoleApi(host) {
+    return [
+      "inspect",
+      (o) {
+        js.JsNative.callMethod(host, "_inspect", [o]);
+        return o;
+      },
+      "dir",
+      window.console.dir,
+      "dirxml",
+      window.console.dirxml
+      // FIXME: add copy method.
+    ];
+  }
+
+  static List getMapKeyList(Map map) => map.keys.toList();
+
+  static bool isNoSuchMethodError(obj) => obj is NoSuchMethodError;
+
+  static void register(
+      Document document, String tag, Type type, String extendsTagName) {
+    var nativeClass = _validateCustomType(type);
+
+    if (extendsTagName == null) {
+      if (nativeClass.reflectedType != HtmlElement) {
+        throw new UnsupportedError('Class must provide extendsTag if base '
+            'native class is not HTMLElement');
+      }
+    }
+
+    _register(document, tag, type, extendsTagName);
+  }
+
+  static void _register(Document document, String tag, Type customType,
+          String extendsTagName) =>
+      _blink.Blink_Utils.register(document, tag, customType, extendsTagName);
+
+  static Element createElement(Document document, String tagName) =>
+      _blink.Blink_Utils.createElement(document, tagName);
+}
+
+class _DOMWindowCrossFrame extends DartHtmlDomObject implements WindowBase {
+  _DOMWindowCrossFrame.internal();
+
+  static _createSafe(win) {
+    if (identical(win, window)) {
+      // The current Window object is the only window object that should not
+      // use _DOMWindowCrossFrame.
+      return window;
+    }
+    return win is _DOMWindowCrossFrame
+        ? win
+        : _blink.Blink_Utils.setInstanceInterceptor(win, _DOMWindowCrossFrame);
+  }
+
+  // Fields.
+  HistoryBase get history {
+    var history = _blink.BlinkWindow.instance.history_Getter_(this);
+    return history is _HistoryCrossFrame
+        ? history
+        : _blink.Blink_Utils.setInstanceInterceptor(
+            history, _HistoryCrossFrame);
+  }
+
+  LocationBase get location {
+    var location = _blink.BlinkWindow.instance.location_Getter_(this);
+    return location is _LocationCrossFrame
+        ? location
+        : _blink.Blink_Utils.setInstanceInterceptor(
+            location, _LocationCrossFrame);
+  }
+
+  bool get closed => _blink.BlinkWindow.instance.closed_Getter_(this);
+  WindowBase get opener => _convertNativeToDart_Window(
+      _blink.BlinkWindow.instance.opener_Getter_(this));
+  WindowBase get parent => _convertNativeToDart_Window(
+      _blink.BlinkWindow.instance.parent_Getter_(this));
+  WindowBase get top => _convertNativeToDart_Window(
+      _blink.BlinkWindow.instance.top_Getter_(this));
+
+  // Methods.
+  void close() => _blink.BlinkWindow.instance.close_Callback_0_(this);
+  void postMessage(Object message, String targetOrigin,
+          [List<MessagePort> transfer]) =>
+      _blink.BlinkWindow.instance.postMessage_Callback_3_(
+          this,
+          convertDartToNative_SerializedScriptValue(message),
+          targetOrigin,
+          transfer);
+
+  // Implementation support.
+  String get typeName => "Window";
+
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  Events get on => throw new UnsupportedError(
+      'You can only attach EventListeners to your own window.');
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  void _addEventListener(
+          [String type, EventListener listener, bool useCapture]) =>
+      throw new UnsupportedError(
+          'You can only attach EventListeners to your own window.');
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  void addEventListener(String type, EventListener listener,
+          [bool useCapture]) =>
+      throw new UnsupportedError(
+          'You can only attach EventListeners to your own window.');
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  bool dispatchEvent(Event event) => throw new UnsupportedError(
+      'You can only attach EventListeners to your own window.');
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  void _removeEventListener(
+          [String type, EventListener listener, bool useCapture]) =>
+      throw new UnsupportedError(
+          'You can only attach EventListeners to your own window.');
+  // TODO(efortuna): Remove this method. dartbug.com/16814
+  void removeEventListener(String type, EventListener listener,
+          [bool useCapture]) =>
+      throw new UnsupportedError(
+          'You can only attach EventListeners to your own window.');
+}
+
+class _HistoryCrossFrame extends DartHtmlDomObject implements HistoryBase {
+  _HistoryCrossFrame.internal();
+
+  // Methods.
+  void back() => _blink.BlinkHistory.instance.back_Callback_0_(this);
+  void forward() => _blink.BlinkHistory.instance.forward_Callback_0_(this);
+  void go([int delta]) {
+    if (delta != null) {
+      _blink.BlinkHistory.instance.go_Callback_1_(this, delta);
+      return;
+    }
+    _blink.BlinkHistory.instance.go_Callback_0_(this);
+    return;
+  }
+
+  // Implementation support.
+  String get typeName => "History";
+}
+
+class _LocationCrossFrame extends DartHtmlDomObject implements LocationBase {
+  _LocationCrossFrame.internal();
+
+  // Fields.
+  set href(String value) =>
+      _blink.BlinkLocation.instance.href_Setter_(this, value);
+
+  // Implementation support.
+  String get typeName => "Location";
+}
+
+// TODO(vsm): Remove DOM isolate code once we have Dartium isolates
+// as workers.  This is only used to support
+// printing and timers in background isolates. As workers they should
+// be able to just do those things natively.
+
+_makeSendPortFuture(spawnRequest) {
+  final completer = new Completer<SendPort>.sync();
+  final port = new ReceivePort();
+  port.listen((result) {
+    completer.complete(result);
+    port.close();
+  });
+  // TODO: SendPort.hashCode is ugly way to access port id.
+  spawnRequest(port.sendPort.hashCode);
+  return completer.future;
+}
+
+Future<SendPort> _spawnDomHelper(Function f) => _makeSendPortFuture((portId) {
+      _Utils.spawnDomHelper(f, portId);
+    });
+
+final Future<SendPort> __HELPER_ISOLATE_PORT =
+    _spawnDomHelper(_helperIsolateMain);
+
+// Tricky part.
+// Once __HELPER_ISOLATE_PORT gets resolved, it will still delay in .then
+// and to delay Timer.run is used. However, Timer.run will try to register
+// another Timer and here we got stuck: event cannot be posted as then
+// callback is not executed because it's delayed with timer.
+// Therefore once future is resolved, it's unsafe to call .then on it
+// in Timer code.
+SendPort __SEND_PORT;
+
+_sendToHelperIsolate(msg, SendPort replyTo) {
+  if (__SEND_PORT != null) {
+    __SEND_PORT.send([msg, replyTo]);
+  } else {
+    __HELPER_ISOLATE_PORT.then((port) {
+      __SEND_PORT = port;
+      __SEND_PORT.send([msg, replyTo]);
+    });
+  }
+}
+
+final _TIMER_REGISTRY = new Map<SendPort, Timer>();
+
+const _NEW_TIMER = 'NEW_TIMER';
+const _CANCEL_TIMER = 'CANCEL_TIMER';
+const _TIMER_PING = 'TIMER_PING';
+const _PRINT = 'PRINT';
+
+_helperIsolateMain(originalSendPort) {
+  var port = new ReceivePort();
+  originalSendPort.send(port.sendPort);
+  port.listen((args) {
+    var msg = args.first;
+    var replyTo = args.last;
+    final cmd = msg[0];
+    if (cmd == _NEW_TIMER) {
+      final duration = new Duration(milliseconds: msg[1]);
+      bool periodic = msg[2];
+      ping() {
+        replyTo.send(_TIMER_PING);
+      }
+
+      ;
+      _TIMER_REGISTRY[replyTo] = periodic
+          ? new Timer.periodic(duration, (_) {
+              ping();
+            })
+          : new Timer(duration, ping);
+    } else if (cmd == _CANCEL_TIMER) {
+      _TIMER_REGISTRY.remove(replyTo).cancel();
+    } else if (cmd == _PRINT) {
+      final message = msg[1];
+      // TODO(antonm): we need somehow identify those isolates.
+      print('[From isolate] $message');
+    }
+  });
+}
+
+final _printClosure = (s) => window.console.log(s);
+final _pureIsolatePrintClosure = (s) {
+  _sendToHelperIsolate([_PRINT, s], null);
+};
+
+final _forwardingPrintClosure = _Utils.forwardingPrint;
+
+final _uriBaseClosure = () => Uri.parse(window.location.href);
+
+final _pureIsolateUriBaseClosure = () {
+  throw new UnimplementedError("Uri.base on a background isolate "
+      "is not supported in the browser");
+};
+
+class _Timer implements Timer {
+  static const int _STATE_TIMEOUT = 0;
+  static const int _STATE_INTERVAL = 1;
+  int _state;
+
+  _Timer(int milliSeconds, void callback(Timer timer), bool repeating) {
+    if (repeating) {
+      _state = (window._setInterval(() {
+                callback(this);
+              }, milliSeconds) <<
+              1) |
+          _STATE_INTERVAL;
+    } else {
+      _state = (window._setTimeout(() {
+                _state = null;
+                callback(this);
+              }, milliSeconds) <<
+              1) |
+          _STATE_TIMEOUT;
+    }
+  }
+
+  void cancel() {
+    if (_state == null) return;
+    int id = _state >> 1;
+    if ((_state & 1) == _STATE_TIMEOUT) {
+      window._clearTimeout(id);
+    } else {
+      window._clearInterval(id);
+    }
+    _state = null;
+  }
+
+  bool get isActive => _state != null;
+}
+
+get _timerFactoryClosure =>
+    (int milliSeconds, void callback(Timer timer), bool repeating) {
+      return new _Timer(milliSeconds, callback, repeating);
+    };
+
+class _PureIsolateTimer implements Timer {
+  bool _isActive = true;
+  final ReceivePort _port = new ReceivePort();
+  SendPort _sendPort; // Effectively final.
+
+  //  static SendPort _SEND_PORT;
+
+  _PureIsolateTimer(int milliSeconds, callback, repeating) {
+    _sendPort = _port.sendPort;
+    _port.listen((msg) {
+      assert(msg == _TIMER_PING);
+      _isActive = repeating;
+      callback(this);
+      if (!repeating) _cancel();
+    });
+
+    _send([_NEW_TIMER, milliSeconds, repeating]);
+  }
+
+  void cancel() {
+    _cancel();
+    _send([_CANCEL_TIMER]);
+  }
+
+  void _cancel() {
+    _isActive = false;
+    _port.close();
+  }
+
+  _send(msg) {
+    _sendToHelperIsolate(msg, _sendPort);
+  }
+
+  bool get isActive => _isActive;
+}
+
+get _pureIsolateTimerFactoryClosure =>
+    ((int milliSeconds, void callback(Timer time), bool repeating) =>
+        new _PureIsolateTimer(milliSeconds, callback, repeating));
+
+class _ScheduleImmediateHelper {
+  MutationObserver _observer;
+  final DivElement _div = new DivElement();
+  Function _callback;
+
+  _ScheduleImmediateHelper() {
+    // Run in the root-zone as the DOM callback would otherwise execute in the
+    // current zone.
+    Zone.root.run(() {
+      // Mutation events get fired as soon as the current event stack is unwound
+      // so we just make a dummy event and listen for that.
+      _observer = new MutationObserver(_handleMutation);
+      _observer.observe(_div, attributes: true);
+    });
+  }
+
+  void _schedule(callback) {
+    if (_callback != null) {
+      throw new StateError(
+          'Only one immediate callback can be scheduled at once');
+    }
+    _callback = callback;
+    // Toggle it to trigger the mutation event.
+    _div.hidden = !_div.hidden;
+  }
+
+  _handleMutation(List<MutationRecord> mutations, MutationObserver observer) {
+    var tmp = _callback;
+    _callback = null;
+    tmp();
+  }
+}
+
+final _ScheduleImmediateHelper _scheduleImmediateHelper =
+    new _ScheduleImmediateHelper();
+
+get _scheduleImmediateClosure => (void callback()) {
+      _scheduleImmediateHelper._schedule(callback);
+    };
+
+get _pureIsolateScheduleImmediateClosure => ((void callback()) =>
+    throw new UnimplementedError("scheduleMicrotask in background isolates "
+        "are not supported in the browser"));
+
+// Class for unsupported native browser 'DOM' objects.
+class _UnsupportedBrowserObject extends DartHtmlDomObject {}
diff --git a/tools/dom/nnbd_src/shared_SVGFactoryProviders.dart b/tools/dom/nnbd_src/shared_SVGFactoryProviders.dart
new file mode 100644
index 0000000..a4aab93
--- /dev/null
+++ b/tools/dom/nnbd_src/shared_SVGFactoryProviders.dart
@@ -0,0 +1,13 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.dom.svg;
+
+class _SvgElementFactoryProvider {
+  static SvgElement createSvgElement_tag(String tag) {
+    final Element temp =
+        document.createElementNS("http://www.w3.org/2000/svg", tag);
+    return temp;
+  }
+}
diff --git a/tools/dom/nnbd_src/shared_html.dart b/tools/dom/nnbd_src/shared_html.dart
new file mode 100644
index 0000000..f2aa8a9
--- /dev/null
+++ b/tools/dom/nnbd_src/shared_html.dart
@@ -0,0 +1,66 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.dom.html;
+
+void Function(T) _wrapZone<T>(void Function(T) callback) {
+  // For performance reasons avoid wrapping if we are in the root zone.
+  if (Zone.current == Zone.root) return callback;
+  if (callback == null) return null;
+  return Zone.current.bindUnaryCallbackGuarded(callback);
+}
+
+void Function(T1, T2) _wrapBinaryZone<T1, T2>(void Function(T1, T2) callback) {
+  // For performance reasons avoid wrapping if we are in the root zone.
+  if (Zone.current == Zone.root) return callback;
+  if (callback == null) return null;
+  return Zone.current.bindBinaryCallbackGuarded(callback);
+}
+
+/**
+ * Finds the first descendant element of this document that matches the
+ * specified group of selectors.
+ *
+ * Unless your webpage contains multiple documents, the top-level
+ * [querySelector]
+ * method behaves the same as this method, so you should use it instead to
+ * save typing a few characters.
+ *
+ * [selectors] should be a string using CSS selector syntax.
+ *
+ *     var element1 = document.querySelector('.className');
+ *     var element2 = document.querySelector('#id');
+ *
+ * For details about CSS selector syntax, see the
+ * [CSS selector specification](http://www.w3.org/TR/css3-selectors/).
+ */
+Element querySelector(String selectors) => document.querySelector(selectors);
+
+/**
+ * Finds all descendant elements of this document that match the specified
+ * group of selectors.
+ *
+ * Unless your webpage contains multiple documents, the top-level
+ * [querySelectorAll]
+ * method behaves the same as this method, so you should use it instead to
+ * save typing a few characters.
+ *
+ * [selectors] should be a string using CSS selector syntax.
+ *
+ *     var items = document.querySelectorAll('.itemClassName');
+ *
+ * For details about CSS selector syntax, see the
+ * [CSS selector specification](http://www.w3.org/TR/css3-selectors/).
+ */
+ElementList<T> querySelectorAll<T extends Element>(String selectors) =>
+    document.querySelectorAll(selectors);
+
+/// A utility for changing the Dart wrapper type for elements.
+abstract class ElementUpgrader {
+  /// Upgrade the specified element to be of the Dart type this was created for.
+  ///
+  /// After upgrading the element passed in is invalid and the returned value
+  /// should be used instead.
+  Element upgrade(Element element);
+}
diff --git a/tools/dom/scripts/css_code_generator.py b/tools/dom/scripts/css_code_generator.py
index 4bf4870..19676e6 100644
--- a/tools/dom/scripts/css_code_generator.py
+++ b/tools/dom/scripts/css_code_generator.py
@@ -157,7 +157,7 @@
   }
 
   String _browserPropertyName(String propertyName) {
-    String name = _readCache(propertyName);
+    String$NULLABLE name = _readCache(propertyName);
     if (name is String) return name;
     name = _supportedBrowserPropertyName(propertyName);
     _writeCache(propertyName, name);
@@ -177,7 +177,7 @@
   }
 
   static final _propertyCache = JS('', '{}');
-  static String _readCache(String key) =>
+  static String$NULLABLE _readCache(String key) =>
     JS('String|Null', '#[#]', _propertyCache, key);
   static void _writeCache(String key, String value) {
     JS('void', '#[#] = #', _propertyCache, key, value);
@@ -192,7 +192,8 @@
         replacedMs);
   }
 
-  void _setPropertyHelper(String propertyName, String value, [String priority]) {
+  void _setPropertyHelper(String propertyName, String$NULLABLE value,
+                          [String$NULLABLE priority]) {
     if (value == null) value = '';
     if (priority == null) priority = '';
     JS('void', '#.setProperty(#, #, #)', this, propertyName, value, priority);
@@ -214,7 +215,7 @@
   String get %s => this._%s;
 
   /** Sets the value of "%s" */
-  set %s(String value) {
+  set %s(String$NULLABLE value) {
     _%s = value == null ? '' : value;
   }
   @Returns('String')
@@ -247,7 +248,7 @@
 """)
 
     class_file.write("""
-  void _setAll(String propertyName, String value) {
+  void _setAll(String propertyName, String$NULLABLE value) {
     value = value == null ? '' : value;
     for (Element element in _elementIterable) {
       JS('void', '#.style[#] = #', element, propertyName, value);
diff --git a/tools/dom/scripts/dartdomgenerator.py b/tools/dom/scripts/dartdomgenerator.py
index b255a8e..7227f3f 100755
--- a/tools/dom/scripts/dartdomgenerator.py
+++ b/tools/dom/scripts/dartdomgenerator.py
@@ -73,13 +73,14 @@
 class GeneratorOptions(object):
 
     def __init__(self, templates, database, type_registry, renamer, metadata,
-                 dart_js_interop):
+                 dart_js_interop, nnbd):
         self.templates = templates
         self.database = database
         self.type_registry = type_registry
         self.renamer = renamer
         self.metadata = metadata
         self.dart_js_interop = dart_js_interop
+        self.nnbd = nnbd
 
 
 def LoadDatabase(database_dir, use_database_cache):
@@ -95,14 +96,18 @@
                          dart2js_output_dir,
                          update_dom_metadata=False,
                          logging_level=logging.WARNING,
-                         dart_js_interop=False):
+                         dart_js_interop=False,
+                         nnbd=False):
     print '\n ----- Accessing DOM using %s -----\n' % (
         'dart:js' if dart_js_interop else 'C++')
 
     start_time = time.time()
 
     current_dir = os.path.dirname(__file__)
-    auxiliary_dir = os.path.join(current_dir, '..', 'src')
+    if nnbd:
+        auxiliary_dir = os.path.join(current_dir, '..', 'nnbd_src')
+    else:
+        auxiliary_dir = os.path.join(current_dir, '..', 'src')
     template_dir = os.path.join(current_dir, '..', 'templates')
 
     _logger.setLevel(logging_level)
@@ -137,7 +142,7 @@
                      backend_factory, dart_js_interop):
         options = GeneratorOptions(template_loader, webkit_database,
                                    type_registry, renamer, metadata,
-                                   dart_js_interop)
+                                   dart_js_interop, nnbd)
         dart_library_emitter = DartLibraryEmitter(emitters, dart_output_dir,
                                                   dart_libraries)
         event_generator = HtmlEventGenerator(webkit_database, renamer, metadata,
@@ -165,7 +170,7 @@
         })
         backend_options = GeneratorOptions(template_loader, webkit_database,
                                            type_registry, renamer, metadata,
-                                           dart_js_interop)
+                                           dart_js_interop, nnbd)
         backend_factory = lambda interface:\
             Dart2JSBackend(interface, backend_options, logging_level)
 
@@ -173,6 +178,9 @@
         dart_libraries = DartLibraries(HTML_LIBRARY_NAMES, template_loader,
                                        'dart2js', dart2js_output_dir,
                                        dart_js_interop)
+        for file in generator._auxiliary_files.values():
+            if file.endswith('darttemplate'):
+                dart_libraries._libraries['html'].AddFile(file)
 
         print '\nGenerating dart2js:\n'
         start_time = time.time()
@@ -259,6 +267,12 @@
         default=None,
         help='Directory to put the generated files')
     parser.add_option(
+        '--nnbd',
+        dest='nnbd',
+        action='store_true',
+        default=False,
+        help='Generate code with non-nullability annotations')
+    parser.add_option(
         '--use-database-cache',
         dest='use_database_cache',
         action='store_true',
@@ -333,26 +347,20 @@
 
     GenerateFromDatabase(database, dart2js_output_dir,
                          options.update_dom_metadata, logging_level,
-                         options.dart_js_interop)
+                         options.dart_js_interop, options.nnbd)
 
     file_generation_start_time = time.time()
 
     if 'htmldart2js' in systems:
         _logger.info('Generating dart2js single files.')
+        sdk_dir = 'sdk_nnbd' if options.nnbd else 'sdk'
 
         for library_name in HTML_LIBRARY_NAMES:
             source = os.path.join(dart2js_output_dir,
                                   '%s_dart2js.dart' % library_name)
             GenerateSingleFile(
-                source,
-                os.path.join('..', '..', '..', 'sdk', 'lib', library_name, 'dart2js'))
-            # TODO(Issue 38701): We won't need two copies once the NNBD SDK is
-            # unforked.
-            GenerateSingleFile(
-                source,
-                os.path.join('..', '..', '..', 'sdk_nnbd', 'lib', library_name, 'dart2js'),
-                None,
-                '// @dart = 2.5')
+                source, os.path.join('..', '..', '..', sdk_dir, 'lib',
+                                     library_name, 'dart2js'))
 
     print '\nGenerating single file %s seconds' % round(
         time.time() - file_generation_start_time, 2)
diff --git a/tools/dom/scripts/emitter.py b/tools/dom/scripts/emitter.py
index d6d1734..7d45fbe 100755
--- a/tools/dom/scripts/emitter.py
+++ b/tools/dom/scripts/emitter.py
@@ -48,6 +48,12 @@
     named hole in the template.  The holes are filled by emitting to the
     corresponding emitter.
 
+    Subtemplates can be created by using $#NAME(...), where text can be placed
+    inside of the parentheses and will conditionally expand depdending on if
+    NAME is set to True or False. The text inside the parentheses may use
+    further $#NAME and $NAME substitutions, but is not permitted to create
+    holes.
+
     Emit returns either a single Emitter if the template contains one hole or a
     tuple of emitters for several holes, in the order that the holes occur in
     the template.
@@ -60,7 +66,6 @@
     def _Emit(self, template_source, parameters):
         """Implementation of Emit, with map in place of named parameters."""
         template = self._ParseTemplate(template_source)
-
         parameter_bindings = self._bindings.Extend(parameters)
 
         hole_names = template._holes
@@ -76,7 +81,7 @@
         else:
             full_bindings = parameter_bindings
 
-        self._ApplyTemplate(template, full_bindings)
+        self._ApplyTemplate(template, full_bindings, self._items)
 
         # Return None, a singleton or tuple of the hole names.
         if not hole_names:
@@ -96,10 +101,29 @@
             elif isinstance(item, Emitter.DeferredLookup):
                 value = item._environment.Lookup(item._lookup._name,
                                                  item._lookup._value_if_missing)
-                _FlattenTo(value, output)
+                if item._lookup._subtemplate:
+                    _FlattenSubtemplate(item, value, output)
+                else:
+                    _FlattenTo(value, output)
             else:
                 output.append(str(item))
 
+        def _FlattenSubtemplate(item, value, output):
+            """Handles subtemplates created by $#NAME(...)"""
+            if value is True:
+                # Expand items in subtemplate
+                _FlattenTo(item._lookup._subitems, output)
+            elif value is not False:
+                if value != item._lookup._value_if_missing:
+                    raise RuntimeError(
+                        'Value for NAME in $#NAME(...) syntax must be a boolean'
+                    )
+                # Expand it into the string literal composed of $#NAME(,
+                # the values inside the parentheses, and ).
+                _FlattenTo(value, output)
+                _FlattenTo(item._lookup._subitems, output)
+                _FlattenTo(')', output)
+
         output = []
         _FlattenTo(self._items, output)
         return output
@@ -111,7 +135,7 @@
             raise RuntimeError('Cannot have holes in Emitter.Bind')
         bindings = self._bindings.Extend(parameters)
         value = Emitter(bindings)
-        value._ApplyTemplate(template, bindings)
+        value._ApplyTemplate(template, bindings, self._items)
         self._bindings = self._bindings.Extend({var: value._items})
         return value
 
@@ -150,6 +174,35 @@
                 items.append(item)
                 holes.append(name)
                 continue
+            name = match.group(7)                    # $#NAME(...)
+            if name:
+                # Since it's possible for this to nest, find the matching right
+                # paren for this left paren.
+                paren_count = 1
+                curr_pos = pos
+                while curr_pos < len(source):
+                    if source[curr_pos] == ')':
+                        paren_count -= 1
+                        if paren_count == 0:
+                            break
+                    elif source[curr_pos] == '(':
+                        # Account for nested parentheses
+                        paren_count += 1
+                    curr_pos += 1
+                if curr_pos == len(source):
+                    # No matching right paren, so not a lookup. Ignore and
+                    # continue.
+                    items.append(term)
+                    continue
+                matched_template = self._ParseTemplate(source[pos:curr_pos])
+                if len(matched_template._holes) > 0:
+                    raise RuntimeError(
+                        '$#NAME syntax cannot contains holes in its arguments')
+                item = Emitter.Lookup(name, term, term, matched_template)
+                items.append(item)
+                # Continue after the right paren
+                pos = curr_pos + 1
+                continue
             raise RuntimeError('Unexpected group')
 
         if len(holes) != len(set(holes)):
@@ -157,10 +210,11 @@
         return Emitter.Template(items, holes)
 
     _SUBST_RE = re.compile(
-        #  $FOO    $(FOO)      $!FOO    $(!FOO)      $?FOO     $(?FOO)
-        r'\$(\w+)|\$\((\w+)\)|\$!(\w+)|\$\(!(\w+)\)|\$\?(\w+)|\$\(\?(\w+)\)')
+        #  $FOO    $(FOO)      $!FOO    $(!FOO)      $?FOO     $(?FOO)       $#FOO(
+        r'\$(\w+)|\$\((\w+)\)|\$!(\w+)|\$\(!(\w+)\)|\$\?(\w+)|\$\(\?(\w+)\)|\$#(\w+)\('
+    )
 
-    def _ApplyTemplate(self, template, bindings):
+    def _ApplyTemplate(self, template, bindings, items_list):
         """Emits the items from the parsed template."""
         result = []
         for item in template._items:
@@ -171,19 +225,26 @@
                 # Bind lookup to the current environment (bindings)
                 # TODO(sra): More space efficient to do direct lookup.
                 result.append(Emitter.DeferredLookup(item, bindings))
+                # If the item has a subtemplate, apply the subtemplate and save
+                # the result in the item's subitems
+                if item._subtemplate:
+                    self._ApplyTemplate(item._subtemplate, bindings,
+                                        item._subitems)
             else:
                 raise RuntimeError('Unexpected template element')
         # Collected fragments are in a sublist, so self._items contains one element
         # (sublist) per template application.
-        self._items.append(result)
+        items_list.append(result)
 
     class Lookup(object):
         """An element of a parsed template."""
 
-        def __init__(self, name, original, default):
+        def __init__(self, name, original, default, subtemplate=None):
             self._name = name
             self._original = original
             self._value_if_missing = default
+            self._subtemplate = subtemplate
+            self._subitems = []
 
     class DeferredLookup(object):
         """A lookup operation that is deferred until final string generation."""
diff --git a/tools/dom/scripts/emitter_test.py b/tools/dom/scripts/emitter_test.py
index db0e219..f1d168e 100755
--- a/tools/dom/scripts/emitter_test.py
+++ b/tools/dom/scripts/emitter_test.py
@@ -88,6 +88,50 @@
         b.EmitRaw('$D$C')
         self.check(e, '[$A12$C$D][21$B$D$C]12$E  $A$B$C$D')
 
+    def testNestedTemplates(self):
+        e = emitter.Emitter()
+        e.Emit('-$#A(-)-', A=True)
+        self.check(e, '---')
+
+    def testNestedTemplates2(self):
+        e = emitter.Emitter()
+        e.Emit('-$#A( $#B(-$C-) )-', A=True, B=True, C='1')
+        self.check(e, '- -1- -')
+
+    def testNestedTemplatesWithFalse(self):
+        e = emitter.Emitter()
+        e.Emit('-$#A( $B )-', A=False, B='1')
+        self.check(e, '--')
+
+    def testNestedTemplatesWithFalse2(self):
+        e = emitter.Emitter()
+        e.Emit('-$#A( $#B(-$C-) )-', A=False, B=True, C='1')
+        self.check(e, '--')
+
+    def testNestedTemplatesWithFalse3(self):
+        e = emitter.Emitter()
+        e.Emit('-$#A( $#B(-$C-) )-', A=True, B=False, C='1')
+        self.check(e, '-  -')
+
+    def testNestedTemplateMissingBindings(self):
+        e = emitter.Emitter()
+        e.Emit('-$#A(-$#B(-$C-)-)-', C='1')
+        self.check(e, '-$#A(-$#B(-1-)-)-')
+
+    def testNestedTemplateWithNoRightParen(self):
+        e = emitter.Emitter()
+        e.Emit('-$#A(-$B-', A=True, B='1')
+        self.check(e, '-$#A(-1-')
+
+    def testNestedTemplateWithWrongBinding(self):
+        try:
+            e = emitter.Emitter()
+            e.Emit('$#A(-)', A='Invalid')
+            e.Fragments()
+        except RuntimeError, ex:
+            return
+        raise AssertionError('Expected error')
+
     def testFormat(self):
         self.assertEquals(emitter.Format('$A$B', A=1, B=2), '12')
 
diff --git a/tools/dom/scripts/generator.py b/tools/dom/scripts/generator.py
index 65e9e75..a24a711 100644
--- a/tools/dom/scripts/generator.py
+++ b/tools/dom/scripts/generator.py
@@ -13,6 +13,13 @@
 from htmlrenamer import custom_html_constructors, html_interface_renames, \
     typed_array_renames
 
+# TODO(srujzs): Pass options flag through to emitter functions.
+class GlobalOptionsHack(object):
+    nnbd = False
+
+global_options_hack = GlobalOptionsHack()
+
+
 _pure_interfaces = monitored.Set('generator._pure_interfaces', [
     'AbstractWorker',
     'CanvasPath',
@@ -404,17 +411,27 @@
     is_optional: Parameter optionality.
   """
 
-    def __init__(self, name, type_id, is_optional):
+    def __init__(self, name, type_id, is_optional, is_nullable, default_value,
+                 default_value_is_null):
         self.name = name
         self.type_id = type_id
         self.is_optional = is_optional
+        self.is_nullable = is_nullable
+        self.default_value = default_value
+        self.default_value_is_null = default_value_is_null
 
     def Copy(self):
-        return ParamInfo(self.name, self.type_id, self.is_optional)
+        return ParamInfo(self.name, self.type_id, self.is_optional,
+                         self.is_nullable, self.default_value,
+                         self.default_value_is_null)
 
     def __repr__(self):
-        content = 'name = %s, type_id = %s, is_optional = %s' % (
-            self.name, self.type_id, self.is_optional)
+        content = ('name = %s, type_id = %s, is_optional = %s, '
+                   'is_nullable = %s, default_value = %s, '
+                   'default_value_is_null %s') % (
+                        self.name, self.type_id, self.is_optional,
+                        self.is_nullable, self.default_value,
+                        self.default_value_is_null)
         return '<ParamInfo(%s)>' % content
 
 
@@ -467,21 +484,40 @@
     def OverloadedType(args):
         type_ids = sorted(set(arg.type.id for arg in args))
         if len(set(DartType(arg.type.id) for arg in args)) == 1:
-            return type_ids[0]
+            nullable = False
+            for arg in args:
+                nullable = nullable or getattr(arg.type, 'nullable', False)
+            return (type_ids[0], nullable)
         else:
-            return None
+            return (None, False)
+
+    # Given a list of overloaded default values, choose a suitable one.
+    def OverloadedDefault(args):
+        defaults = sorted(set(arg.default_value for arg in args))
+        if len(set(DartType(arg.type.id) for arg in args)) == 1:
+            null_default = False
+            for arg in args:
+                null_default = null_default or arg.default_value_is_null
+            return (defaults[0], null_default)
+        else:
+            return (None, False)
 
     result = []
 
     is_optional = False
+    # Process overloaded arguments across a set of overloaded operations.
+    # Each tuple in args corresponds to overloaded arguments with the same name.
     for arg_tuple in map(lambda *x: x, *args):
         is_optional = is_optional or any(
             arg is None or IsOptional(arg) for arg in arg_tuple)
 
         filtered = filter(None, arg_tuple)
-        type_id = OverloadedType(filtered)
+        (type_id, is_nullable) = OverloadedType(filtered)
         name = OverloadedName(filtered)
-        result.append(ParamInfo(name, type_id, is_optional))
+        default = OverloadedDefault(filtered)
+        result.append(
+            ParamInfo(name, type_id, is_optional, is_nullable, default[0],
+                      default[1]))
 
     return result
 
@@ -620,18 +656,19 @@
     return name
 
 
-def TypeOrNothing(dart_type, comment=None):
+def TypeOrNothing(dart_type, comment=None, nullable=False):
     """Returns string for declaring something with |dart_type| in a context
   where a type may be omitted.
   The string is empty or has a trailing space.
   """
+    nullability_operator = '?' if global_options_hack.nnbd and nullable else ''
     if dart_type == 'dynamic':
         if comment:
             return '/*%s*/ ' % comment  # Just a comment foo(/*T*/ x)
         else:
             return ''  # foo(x) looks nicer than foo(var|dynamic x)
     else:
-        return dart_type + ' '
+        return dart_type + nullability_operator + ' '
 
 
 def TypeOrVar(dart_type, comment=None):
@@ -692,7 +729,8 @@
             # Special handling for setlike IDL forEach operation.
             if dart_type is None and param.type_id.endswith('ForEachCallback'):
                 dart_type = param.type_id
-            return (TypeOrNothing(dart_type, param.type_id), param.name)
+            return (TypeOrNothing(dart_type, param.type_id, param.is_nullable or
+                                  param.is_optional), param.name)
 
         required = []
         optional = []
@@ -921,9 +959,12 @@
         # conversion function)
         # output_type is the type of the API output (and the result type of the
         # conversion function)
+        # nullsafe_output flags whether the output_type has been converted yet
+        # to a null-safe type i.e. <type>? if nullable and <type> if not
         self.function_name = name
         self.input_type = input_type
         self.output_type = output_type
+        self.nullsafe_output = False
 
 
 #  "TYPE DIRECTION INTERFACE.MEMBER" -> conversion
diff --git a/tools/dom/scripts/htmldartgenerator.py b/tools/dom/scripts/htmldartgenerator.py
index 824ec92..1a5387d 100644
--- a/tools/dom/scripts/htmldartgenerator.py
+++ b/tools/dom/scripts/htmldartgenerator.py
@@ -114,6 +114,7 @@
         for id in sorted(operationsByName.keys()):
             operations = operationsByName[id]
             info = AnalyzeOperation(interface, operations)
+            info.nnbd = self._nnbd
             self.AddOperation(info, declare_only, dart_js_interop)
             if ('%s.%s' % (interface.id,
                            info.declared_name) in convert_to_future_members):
@@ -898,7 +899,8 @@
     def SecureOutputType(self,
                          type_name,
                          is_dart_type=False,
-                         can_narrow_type=False):
+                         can_narrow_type=False,
+                         nullable=False):
         """ Converts the type name to the secure type name for return types.
     Arguments:
       can_narrow_type - True if the output type can be narrowed further than
@@ -918,6 +920,8 @@
         assert (dart_name != 'HistoryBase' and dart_name != 'LocationBase')
         if dart_name == 'Window':
             return _secure_base_types[dart_name]
+        if self._nnbd and nullable:
+            dart_name = dart_name + '?'
         return dart_name
 
     def SecureBaseName(self, type_name):
@@ -1002,9 +1006,9 @@
                                 'Object'
                         ]:
                             param_type = 'dynamic'
-
             target_parameters.append(
-                '%s%s' % (TypeOrNothing(param_type), param_name))
+                '%s%s' % (TypeOrNothing(param_type, nullable=arg.type.nullable),
+                          param_name))
             calling_parameters.append(',%s ' % param_name)
 
         return target_parameters, converted_arguments, calling_parameters
diff --git a/tools/dom/scripts/systemhtml.py b/tools/dom/scripts/systemhtml.py
index ac34feb..600ac3a 100644
--- a/tools/dom/scripts/systemhtml.py
+++ b/tools/dom/scripts/systemhtml.py
@@ -183,8 +183,15 @@
         info.constructor_name = self.name
         info.js_name = None
         info.type_name = interface_name
-        info.param_infos = map(lambda tXn: ParamInfo(tXn[1], tXn[0], True),
-                               self.opt_params)
+        # optional parameters are always nullable
+        info.param_infos = map(
+            lambda tXn: ParamInfo(
+                name=tXn[1],
+                type_id=tXn[0],
+                is_optional=True,
+                is_nullable=True,
+                default_value=None,
+                default_value_is_null=False), self.opt_params)
         info.requires_named_arguments = True
         info.factory_parameters = ['"%s"' % self.tag]
         info.pure_dart_constructor = True
@@ -594,6 +601,10 @@
         self._template_loader = options.templates
         self._type_registry = options.type_registry
         self._options = options
+        # TODO(srujzs): This sets the nnbd option globally inside generator.py
+        # since there is no options object there.  This should should be cleaned
+        # up and passed as an option instead.
+        global_options_hack.nnbd = options.nnbd
         self._library_emitter = library_emitter
         self._event_generator = event_generator
         self._interface = interface
@@ -805,7 +816,9 @@
             DOMNAME=self._interface.doc_js_name,
             NATIVESPEC=native_spec,
             KEYTYPE=maplikeKeyType,
-            VALUETYPE=maplikeValueType)
+            VALUETYPE=maplikeValueType,
+            NULLABLE='?' if self._options.nnbd else '',
+            NULLSAFECAST=True if self._options.nnbd else False)
         stream_getter_signatures_emitter = None
         element_stream_getters_emitter = None
         if type(implementation_members_emitter) == tuple:
@@ -1154,6 +1167,7 @@
         self._type_registry = options.type_registry
         self._renamer = options.renamer
         self._metadata = options.metadata
+        self._nnbd = options.nnbd
         self._interface_type_info = self._type_registry.TypeInfo(
             self._interface.id)
         self._current_secondary_parent = None
@@ -1229,17 +1243,22 @@
             and not ',' in arguments \
             and not self._HasUnreliableFactoryConstructor():
             return emitter.Format(
-                "JS('returns:$INTERFACE_NAME;creates:$INTERFACE_NAME;new:true',"
+                "JS$CAST("
+                "'returns:$INTERFACE_NAME;creates:$INTERFACE_NAME;new:true',"
                 " '#.$METHOD(#)', $FACTORY, $ARGUMENTS)",
+                CAST='<' + self._interface_type_info.interface_name() +
+                '>' if self._nnbd else '',
                 INTERFACE_NAME=self._interface_type_info.interface_name(),
                 FACTORY=factory,
                 METHOD=method,
                 ARGUMENTS=arguments)
         return emitter.Format(
-            '$FACTORY.$METHOD($ARGUMENTS)',
+            '$FACTORY.$METHOD($ARGUMENTS)$CAST',
             FACTORY=factory,
             METHOD=method,
-            ARGUMENTS=arguments)
+            ARGUMENTS=arguments,
+            CAST=' as ' + self._interface_type_info.interface_name() \
+            if self._nnbd else '')
 
     def _HasUnreliableFactoryConstructor(self):
         return self._interface.doc_js_name in _js_unreliable_element_factories
@@ -1413,10 +1432,19 @@
             self._AddAttributeUsingProperties(attribute, html_name, read_only)
             return
 
-        output_type = self.SecureOutputType(attribute.type.id, False, read_only)
-        input_type = self._NarrowInputType(attribute.type.id)
-        metadata = self._Metadata(attribute.type.id, attribute.id, output_type)
         rename = self._RenamingAnnotation(attribute.id, html_name)
+        output_type = self.SecureOutputType(attribute.type.id,
+                                            is_dart_type=False,
+                                            can_narrow_type=read_only,
+                                            nullable=attribute.type.nullable)
+        metadata = self._Metadata(attribute.type.id, attribute.id, output_type)
+
+        if self._nnbd and not attribute.type.nullable:
+          self._AddAttributeUsingProperties(attribute, html_name, read_only,
+                                            rename, metadata)
+          return
+
+        input_type = self._NarrowInputType(attribute.type.id)
         static_attribute = 'static' if attribute.is_static else ''
         if not read_only:
             if attribute.type.id == 'Promise':
@@ -1467,18 +1495,26 @@
                 ) and html_name == 'length':
                     template = ('\n  $RENAME$(ANNOTATIONS)$TYPE get $NAME => ' +
                                 'JS("$TYPE", "#.$NAME", this);\n')
+                output_type_without_nullability = self.SecureOutputType(
+                    attribute.type.id,
+                    is_dart_type=False,
+                    can_narrow_type=read_only,
+                    nullable=False)
                 self._members_emitter.Emit(
                     template,
                     RENAME=rename,
                     ANNOTATIONS=metadata,
                     STATIC=static_attribute,
                     NAME=html_name,
-                    TYPE=input_type if output_type == 'double' else output_type)
+                    TYPE=input_type
+                    if output_type_without_nullability == 'double' else
+                    output_type)
 
-    def _AddAttributeUsingProperties(self, attribute, html_name, read_only):
-        self._AddRenamingGetter(attribute, html_name)
+    def _AddAttributeUsingProperties(self, attribute, html_name, read_only,
+                                     rename=None, metadata=None):
+        self._AddRenamingGetter(attribute, html_name, rename, metadata)
         if not read_only:
-            self._AddRenamingSetter(attribute, html_name)
+            self._AddRenamingSetter(attribute, html_name, rename, metadata)
 
     def _AddInterfaceAttribute(self, attribute, html_name, read_only):
         self._members_emitter.Emit(
@@ -1488,33 +1524,48 @@
             NAME=html_name,
             TYPE=self.SecureOutputType(attribute.type.id))
 
-    def _AddRenamingGetter(self, attr, html_name):
+    def _AddNullSafetyToConversion(self, attr, conversion):
+        if conversion.nullsafe_output == False:
+            # Convert output type to one that recognizes nullability
+            if (self._nnbd and attr.type.nullable):
+                conversion.output_type += '?'
+            conversion.nullsafe_output = True
 
+    def _AddRenamingGetter(self, attr, html_name, rename, metadata):
         conversion = self._OutputConversion(attr.type.id, attr.id)
         if conversion:
+            self._AddNullSafetyToConversion(attr, conversion)
             return self._AddConvertingGetter(attr, html_name, conversion)
         return_type = self.SecureOutputType(attr.type.id)
         native_type = self._NarrowToImplementationType(attr.type.id)
         self._members_emitter.Emit(
             # TODO(sra): Use metadata to provide native name.
+            '\n  $RENAME'
+            '\n  $METADATA'
             '\n  $TYPE get $HTML_NAME => JS("$NATIVE_TYPE", "#.$NAME", this);'
             '\n',
+            RENAME=rename if rename else '',
+            METADATA=metadata if metadata else '',
             HTML_NAME=html_name,
             NAME=attr.id,
             TYPE=return_type,
             NATIVE_TYPE=native_type)
 
-    def _AddRenamingSetter(self, attr, html_name):
-
+    def _AddRenamingSetter(self, attr, html_name, rename, metadata):
         conversion = self._InputConversion(attr.type.id, attr.id)
         if conversion:
+            self._AddNullSafetyToConversion(attr, conversion)
             return self._AddConvertingSetter(attr, html_name, conversion)
         self._members_emitter.Emit(
             # TODO(sra): Use metadata to provide native name.
+            '\n  $RENAME'
+            '\n  $METADATA'
             '\n  set $HTML_NAME($TYPE value) {'
             '\n    JS("void", "#.$NAME = #", this, value);'
             '\n  }'
             '\n',
+            RENAME=rename if rename else '',
+            METADATA=metadata if metadata else '',
             HTML_NAME=html_name,
             NAME=attr.id,
             TYPE=self._NarrowInputType(attr.type.id))
diff --git a/tools/dom/src/EventStreamProvider.dart b/tools/dom/src/EventStreamProvider.dart
index 23fd771..83b8c07 100644
--- a/tools/dom/src/EventStreamProvider.dart
+++ b/tools/dom/src/EventStreamProvider.dart
@@ -265,7 +265,9 @@
     }
     // Remove current event listener.
     _unlisten();
-    _onData = _wrapZone<Event>(handleData);
+    _onData = handleData == null
+        ? null
+        : _wrapZone<Event>((e) => (handleData as dynamic)(e));
     _tryResume();
   }
 
diff --git a/tools/dom/templates/immutable_list_mixin.darttemplate b/tools/dom/templates/html/dart2js/immutable_list_mixin.darttemplate
similarity index 100%
rename from tools/dom/templates/immutable_list_mixin.darttemplate
rename to tools/dom/templates/html/dart2js/immutable_list_mixin.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_AudioContext.darttemplate b/tools/dom/templates/html/impl/impl_AudioContext.darttemplate
index d98519b..70ac3c7 100644
--- a/tools/dom/templates/html/impl/impl_AudioContext.darttemplate
+++ b/tools/dom/templates/html/impl/impl_AudioContext.darttemplate
@@ -17,8 +17,9 @@
     }
   }
 
-  ScriptProcessorNode createScriptProcessor([int bufferSize,
-      int numberOfInputChannels, int numberOfOutputChannels]) {
+  ScriptProcessorNode createScriptProcessor([int$NULLABLE bufferSize,
+      int$NULLABLE numberOfInputChannels,
+      int$NULLABLE numberOfOutputChannels]) {
     var function = JS(
         '=Object',
         '#.createScriptProcessor || '
@@ -46,8 +47,8 @@
       DecodeErrorCallback errorCallback]) native;
 
   Future<AudioBuffer> decodeAudioData(ByteBuffer audioData,
-      [DecodeSuccessCallback successCallback,
-      DecodeErrorCallback errorCallback]) {
+      [DecodeSuccessCallback$NULLABLE successCallback,
+      DecodeErrorCallback$NULLABLE errorCallback]) {
     if (successCallback != null &&  errorCallback != null) {
       return _decodeAudioData(audioData, successCallback, errorCallback);
     }
diff --git a/tools/dom/templates/html/impl/impl_CSSStyleDeclaration.darttemplate b/tools/dom/templates/html/impl/impl_CSSStyleDeclaration.darttemplate
index 574ef48..be015e6 100644
--- a/tools/dom/templates/html/impl/impl_CSSStyleDeclaration.darttemplate
+++ b/tools/dom/templates/html/impl/impl_CSSStyleDeclaration.darttemplate
@@ -59,7 +59,7 @@
   }
 
   String _browserPropertyName(String propertyName) {
-    String name = _readCache(propertyName);
+    String$NULLABLE name = _readCache(propertyName);
     if (name is String) return name;
     name = _supportedBrowserPropertyName(propertyName);
     _writeCache(propertyName, name);
@@ -79,7 +79,7 @@
   }
 
   static final _propertyCache = JS('', '{}');
-  static String _readCache(String key) =>
+  static String$NULLABLE _readCache(String key) =>
     JS('String|Null', '#[#]', _propertyCache, key);
   static void _writeCache(String key, String value) {
     JS('void', '#[#] = #', _propertyCache, key, value);
@@ -94,7 +94,8 @@
         replacedMs);
   }
 
-  void _setPropertyHelper(String propertyName, String value, [String priority]) {
+  void _setPropertyHelper(String propertyName, String$NULLABLE value,
+                          [String$NULLABLE priority]) {
     if (value == null) value = '';
     if (priority == null) priority = '';
     JS('void', '#.setProperty(#, #, #)', this, propertyName, value, priority);
@@ -112,7 +113,7 @@
   String get background => this._background;
 
   /** Sets the value of "background" */
-  set background(String value) {
+  set background(String$NULLABLE value) {
     _background = value == null ? '' : value;
   }
   @Returns('String')
@@ -123,7 +124,7 @@
   String get backgroundAttachment => this._backgroundAttachment;
 
   /** Sets the value of "background-attachment" */
-  set backgroundAttachment(String value) {
+  set backgroundAttachment(String$NULLABLE value) {
     _backgroundAttachment = value == null ? '' : value;
   }
   @Returns('String')
@@ -134,7 +135,7 @@
   String get backgroundColor => this._backgroundColor;
 
   /** Sets the value of "background-color" */
-  set backgroundColor(String value) {
+  set backgroundColor(String$NULLABLE value) {
     _backgroundColor = value == null ? '' : value;
   }
   @Returns('String')
@@ -145,7 +146,7 @@
   String get backgroundImage => this._backgroundImage;
 
   /** Sets the value of "background-image" */
-  set backgroundImage(String value) {
+  set backgroundImage(String$NULLABLE value) {
     _backgroundImage = value == null ? '' : value;
   }
   @Returns('String')
@@ -156,7 +157,7 @@
   String get backgroundPosition => this._backgroundPosition;
 
   /** Sets the value of "background-position" */
-  set backgroundPosition(String value) {
+  set backgroundPosition(String$NULLABLE value) {
     _backgroundPosition = value == null ? '' : value;
   }
   @Returns('String')
@@ -167,7 +168,7 @@
   String get backgroundRepeat => this._backgroundRepeat;
 
   /** Sets the value of "background-repeat" */
-  set backgroundRepeat(String value) {
+  set backgroundRepeat(String$NULLABLE value) {
     _backgroundRepeat = value == null ? '' : value;
   }
   @Returns('String')
@@ -178,7 +179,7 @@
   String get border => this._border;
 
   /** Sets the value of "border" */
-  set border(String value) {
+  set border(String$NULLABLE value) {
     _border = value == null ? '' : value;
   }
   @Returns('String')
@@ -189,7 +190,7 @@
   String get borderBottom => this._borderBottom;
 
   /** Sets the value of "border-bottom" */
-  set borderBottom(String value) {
+  set borderBottom(String$NULLABLE value) {
     _borderBottom = value == null ? '' : value;
   }
   @Returns('String')
@@ -200,7 +201,7 @@
   String get borderBottomColor => this._borderBottomColor;
 
   /** Sets the value of "border-bottom-color" */
-  set borderBottomColor(String value) {
+  set borderBottomColor(String$NULLABLE value) {
     _borderBottomColor = value == null ? '' : value;
   }
   @Returns('String')
@@ -211,7 +212,7 @@
   String get borderBottomStyle => this._borderBottomStyle;
 
   /** Sets the value of "border-bottom-style" */
-  set borderBottomStyle(String value) {
+  set borderBottomStyle(String$NULLABLE value) {
     _borderBottomStyle = value == null ? '' : value;
   }
   @Returns('String')
@@ -222,7 +223,7 @@
   String get borderBottomWidth => this._borderBottomWidth;
 
   /** Sets the value of "border-bottom-width" */
-  set borderBottomWidth(String value) {
+  set borderBottomWidth(String$NULLABLE value) {
     _borderBottomWidth = value == null ? '' : value;
   }
   @Returns('String')
@@ -233,7 +234,7 @@
   String get borderCollapse => this._borderCollapse;
 
   /** Sets the value of "border-collapse" */
-  set borderCollapse(String value) {
+  set borderCollapse(String$NULLABLE value) {
     _borderCollapse = value == null ? '' : value;
   }
   @Returns('String')
@@ -244,7 +245,7 @@
   String get borderColor => this._borderColor;
 
   /** Sets the value of "border-color" */
-  set borderColor(String value) {
+  set borderColor(String$NULLABLE value) {
     _borderColor = value == null ? '' : value;
   }
   @Returns('String')
@@ -255,7 +256,7 @@
   String get borderLeft => this._borderLeft;
 
   /** Sets the value of "border-left" */
-  set borderLeft(String value) {
+  set borderLeft(String$NULLABLE value) {
     _borderLeft = value == null ? '' : value;
   }
   @Returns('String')
@@ -266,7 +267,7 @@
   String get borderLeftColor => this._borderLeftColor;
 
   /** Sets the value of "border-left-color" */
-  set borderLeftColor(String value) {
+  set borderLeftColor(String$NULLABLE value) {
     _borderLeftColor = value == null ? '' : value;
   }
   @Returns('String')
@@ -277,7 +278,7 @@
   String get borderLeftStyle => this._borderLeftStyle;
 
   /** Sets the value of "border-left-style" */
-  set borderLeftStyle(String value) {
+  set borderLeftStyle(String$NULLABLE value) {
     _borderLeftStyle = value == null ? '' : value;
   }
   @Returns('String')
@@ -288,7 +289,7 @@
   String get borderLeftWidth => this._borderLeftWidth;
 
   /** Sets the value of "border-left-width" */
-  set borderLeftWidth(String value) {
+  set borderLeftWidth(String$NULLABLE value) {
     _borderLeftWidth = value == null ? '' : value;
   }
   @Returns('String')
@@ -299,7 +300,7 @@
   String get borderRight => this._borderRight;
 
   /** Sets the value of "border-right" */
-  set borderRight(String value) {
+  set borderRight(String$NULLABLE value) {
     _borderRight = value == null ? '' : value;
   }
   @Returns('String')
@@ -310,7 +311,7 @@
   String get borderRightColor => this._borderRightColor;
 
   /** Sets the value of "border-right-color" */
-  set borderRightColor(String value) {
+  set borderRightColor(String$NULLABLE value) {
     _borderRightColor = value == null ? '' : value;
   }
   @Returns('String')
@@ -321,7 +322,7 @@
   String get borderRightStyle => this._borderRightStyle;
 
   /** Sets the value of "border-right-style" */
-  set borderRightStyle(String value) {
+  set borderRightStyle(String$NULLABLE value) {
     _borderRightStyle = value == null ? '' : value;
   }
   @Returns('String')
@@ -332,7 +333,7 @@
   String get borderRightWidth => this._borderRightWidth;
 
   /** Sets the value of "border-right-width" */
-  set borderRightWidth(String value) {
+  set borderRightWidth(String$NULLABLE value) {
     _borderRightWidth = value == null ? '' : value;
   }
   @Returns('String')
@@ -343,7 +344,7 @@
   String get borderSpacing => this._borderSpacing;
 
   /** Sets the value of "border-spacing" */
-  set borderSpacing(String value) {
+  set borderSpacing(String$NULLABLE value) {
     _borderSpacing = value == null ? '' : value;
   }
   @Returns('String')
@@ -354,7 +355,7 @@
   String get borderStyle => this._borderStyle;
 
   /** Sets the value of "border-style" */
-  set borderStyle(String value) {
+  set borderStyle(String$NULLABLE value) {
     _borderStyle = value == null ? '' : value;
   }
   @Returns('String')
@@ -365,7 +366,7 @@
   String get borderTop => this._borderTop;
 
   /** Sets the value of "border-top" */
-  set borderTop(String value) {
+  set borderTop(String$NULLABLE value) {
     _borderTop = value == null ? '' : value;
   }
   @Returns('String')
@@ -376,7 +377,7 @@
   String get borderTopColor => this._borderTopColor;
 
   /** Sets the value of "border-top-color" */
-  set borderTopColor(String value) {
+  set borderTopColor(String$NULLABLE value) {
     _borderTopColor = value == null ? '' : value;
   }
   @Returns('String')
@@ -387,7 +388,7 @@
   String get borderTopStyle => this._borderTopStyle;
 
   /** Sets the value of "border-top-style" */
-  set borderTopStyle(String value) {
+  set borderTopStyle(String$NULLABLE value) {
     _borderTopStyle = value == null ? '' : value;
   }
   @Returns('String')
@@ -398,7 +399,7 @@
   String get borderTopWidth => this._borderTopWidth;
 
   /** Sets the value of "border-top-width" */
-  set borderTopWidth(String value) {
+  set borderTopWidth(String$NULLABLE value) {
     _borderTopWidth = value == null ? '' : value;
   }
   @Returns('String')
@@ -409,7 +410,7 @@
   String get borderWidth => this._borderWidth;
 
   /** Sets the value of "border-width" */
-  set borderWidth(String value) {
+  set borderWidth(String$NULLABLE value) {
     _borderWidth = value == null ? '' : value;
   }
   @Returns('String')
@@ -420,7 +421,7 @@
   String get bottom => this._bottom;
 
   /** Sets the value of "bottom" */
-  set bottom(String value) {
+  set bottom(String$NULLABLE value) {
     _bottom = value == null ? '' : value;
   }
   @Returns('String')
@@ -431,7 +432,7 @@
   String get captionSide => this._captionSide;
 
   /** Sets the value of "caption-side" */
-  set captionSide(String value) {
+  set captionSide(String$NULLABLE value) {
     _captionSide = value == null ? '' : value;
   }
   @Returns('String')
@@ -442,7 +443,7 @@
   String get clear => this._clear;
 
   /** Sets the value of "clear" */
-  set clear(String value) {
+  set clear(String$NULLABLE value) {
     _clear = value == null ? '' : value;
   }
   @Returns('String')
@@ -453,7 +454,7 @@
   String get clip => this._clip;
 
   /** Sets the value of "clip" */
-  set clip(String value) {
+  set clip(String$NULLABLE value) {
     _clip = value == null ? '' : value;
   }
   @Returns('String')
@@ -464,7 +465,7 @@
   String get color => this._color;
 
   /** Sets the value of "color" */
-  set color(String value) {
+  set color(String$NULLABLE value) {
     _color = value == null ? '' : value;
   }
   @Returns('String')
@@ -475,7 +476,7 @@
   String get content => this._content;
 
   /** Sets the value of "content" */
-  set content(String value) {
+  set content(String$NULLABLE value) {
     _content = value == null ? '' : value;
   }
   @Returns('String')
@@ -486,7 +487,7 @@
   String get cursor => this._cursor;
 
   /** Sets the value of "cursor" */
-  set cursor(String value) {
+  set cursor(String$NULLABLE value) {
     _cursor = value == null ? '' : value;
   }
   @Returns('String')
@@ -497,7 +498,7 @@
   String get direction => this._direction;
 
   /** Sets the value of "direction" */
-  set direction(String value) {
+  set direction(String$NULLABLE value) {
     _direction = value == null ? '' : value;
   }
   @Returns('String')
@@ -508,7 +509,7 @@
   String get display => this._display;
 
   /** Sets the value of "display" */
-  set display(String value) {
+  set display(String$NULLABLE value) {
     _display = value == null ? '' : value;
   }
   @Returns('String')
@@ -519,7 +520,7 @@
   String get emptyCells => this._emptyCells;
 
   /** Sets the value of "empty-cells" */
-  set emptyCells(String value) {
+  set emptyCells(String$NULLABLE value) {
     _emptyCells = value == null ? '' : value;
   }
   @Returns('String')
@@ -530,7 +531,7 @@
   String get font => this._font;
 
   /** Sets the value of "font" */
-  set font(String value) {
+  set font(String$NULLABLE value) {
     _font = value == null ? '' : value;
   }
   @Returns('String')
@@ -541,7 +542,7 @@
   String get fontFamily => this._fontFamily;
 
   /** Sets the value of "font-family" */
-  set fontFamily(String value) {
+  set fontFamily(String$NULLABLE value) {
     _fontFamily = value == null ? '' : value;
   }
   @Returns('String')
@@ -552,7 +553,7 @@
   String get fontSize => this._fontSize;
 
   /** Sets the value of "font-size" */
-  set fontSize(String value) {
+  set fontSize(String$NULLABLE value) {
     _fontSize = value == null ? '' : value;
   }
   @Returns('String')
@@ -563,7 +564,7 @@
   String get fontStyle => this._fontStyle;
 
   /** Sets the value of "font-style" */
-  set fontStyle(String value) {
+  set fontStyle(String$NULLABLE value) {
     _fontStyle = value == null ? '' : value;
   }
   @Returns('String')
@@ -574,7 +575,7 @@
   String get fontVariant => this._fontVariant;
 
   /** Sets the value of "font-variant" */
-  set fontVariant(String value) {
+  set fontVariant(String$NULLABLE value) {
     _fontVariant = value == null ? '' : value;
   }
   @Returns('String')
@@ -585,7 +586,7 @@
   String get fontWeight => this._fontWeight;
 
   /** Sets the value of "font-weight" */
-  set fontWeight(String value) {
+  set fontWeight(String$NULLABLE value) {
     _fontWeight = value == null ? '' : value;
   }
   @Returns('String')
@@ -596,7 +597,7 @@
   String get height => this._height;
 
   /** Sets the value of "height" */
-  set height(String value) {
+  set height(String$NULLABLE value) {
     _height = value == null ? '' : value;
   }
   @Returns('String')
@@ -607,7 +608,7 @@
   String get left => this._left;
 
   /** Sets the value of "left" */
-  set left(String value) {
+  set left(String$NULLABLE value) {
     _left = value == null ? '' : value;
   }
   @Returns('String')
@@ -618,7 +619,7 @@
   String get letterSpacing => this._letterSpacing;
 
   /** Sets the value of "letter-spacing" */
-  set letterSpacing(String value) {
+  set letterSpacing(String$NULLABLE value) {
     _letterSpacing = value == null ? '' : value;
   }
   @Returns('String')
@@ -629,7 +630,7 @@
   String get lineHeight => this._lineHeight;
 
   /** Sets the value of "line-height" */
-  set lineHeight(String value) {
+  set lineHeight(String$NULLABLE value) {
     _lineHeight = value == null ? '' : value;
   }
   @Returns('String')
@@ -640,7 +641,7 @@
   String get listStyle => this._listStyle;
 
   /** Sets the value of "list-style" */
-  set listStyle(String value) {
+  set listStyle(String$NULLABLE value) {
     _listStyle = value == null ? '' : value;
   }
   @Returns('String')
@@ -651,7 +652,7 @@
   String get listStyleImage => this._listStyleImage;
 
   /** Sets the value of "list-style-image" */
-  set listStyleImage(String value) {
+  set listStyleImage(String$NULLABLE value) {
     _listStyleImage = value == null ? '' : value;
   }
   @Returns('String')
@@ -662,7 +663,7 @@
   String get listStylePosition => this._listStylePosition;
 
   /** Sets the value of "list-style-position" */
-  set listStylePosition(String value) {
+  set listStylePosition(String$NULLABLE value) {
     _listStylePosition = value == null ? '' : value;
   }
   @Returns('String')
@@ -673,7 +674,7 @@
   String get listStyleType => this._listStyleType;
 
   /** Sets the value of "list-style-type" */
-  set listStyleType(String value) {
+  set listStyleType(String$NULLABLE value) {
     _listStyleType = value == null ? '' : value;
   }
   @Returns('String')
@@ -684,7 +685,7 @@
   String get margin => this._margin;
 
   /** Sets the value of "margin" */
-  set margin(String value) {
+  set margin(String$NULLABLE value) {
     _margin = value == null ? '' : value;
   }
   @Returns('String')
@@ -695,7 +696,7 @@
   String get marginBottom => this._marginBottom;
 
   /** Sets the value of "margin-bottom" */
-  set marginBottom(String value) {
+  set marginBottom(String$NULLABLE value) {
     _marginBottom = value == null ? '' : value;
   }
   @Returns('String')
@@ -706,7 +707,7 @@
   String get marginLeft => this._marginLeft;
 
   /** Sets the value of "margin-left" */
-  set marginLeft(String value) {
+  set marginLeft(String$NULLABLE value) {
     _marginLeft = value == null ? '' : value;
   }
   @Returns('String')
@@ -717,7 +718,7 @@
   String get marginRight => this._marginRight;
 
   /** Sets the value of "margin-right" */
-  set marginRight(String value) {
+  set marginRight(String$NULLABLE value) {
     _marginRight = value == null ? '' : value;
   }
   @Returns('String')
@@ -728,7 +729,7 @@
   String get marginTop => this._marginTop;
 
   /** Sets the value of "margin-top" */
-  set marginTop(String value) {
+  set marginTop(String$NULLABLE value) {
     _marginTop = value == null ? '' : value;
   }
   @Returns('String')
@@ -739,7 +740,7 @@
   String get maxHeight => this._maxHeight;
 
   /** Sets the value of "max-height" */
-  set maxHeight(String value) {
+  set maxHeight(String$NULLABLE value) {
     _maxHeight = value == null ? '' : value;
   }
   @Returns('String')
@@ -750,7 +751,7 @@
   String get maxWidth => this._maxWidth;
 
   /** Sets the value of "max-width" */
-  set maxWidth(String value) {
+  set maxWidth(String$NULLABLE value) {
     _maxWidth = value == null ? '' : value;
   }
   @Returns('String')
@@ -761,7 +762,7 @@
   String get minHeight => this._minHeight;
 
   /** Sets the value of "min-height" */
-  set minHeight(String value) {
+  set minHeight(String$NULLABLE value) {
     _minHeight = value == null ? '' : value;
   }
   @Returns('String')
@@ -772,7 +773,7 @@
   String get minWidth => this._minWidth;
 
   /** Sets the value of "min-width" */
-  set minWidth(String value) {
+  set minWidth(String$NULLABLE value) {
     _minWidth = value == null ? '' : value;
   }
   @Returns('String')
@@ -783,7 +784,7 @@
   String get outline => this._outline;
 
   /** Sets the value of "outline" */
-  set outline(String value) {
+  set outline(String$NULLABLE value) {
     _outline = value == null ? '' : value;
   }
   @Returns('String')
@@ -794,7 +795,7 @@
   String get outlineColor => this._outlineColor;
 
   /** Sets the value of "outline-color" */
-  set outlineColor(String value) {
+  set outlineColor(String$NULLABLE value) {
     _outlineColor = value == null ? '' : value;
   }
   @Returns('String')
@@ -805,7 +806,7 @@
   String get outlineStyle => this._outlineStyle;
 
   /** Sets the value of "outline-style" */
-  set outlineStyle(String value) {
+  set outlineStyle(String$NULLABLE value) {
     _outlineStyle = value == null ? '' : value;
   }
   @Returns('String')
@@ -816,7 +817,7 @@
   String get outlineWidth => this._outlineWidth;
 
   /** Sets the value of "outline-width" */
-  set outlineWidth(String value) {
+  set outlineWidth(String$NULLABLE value) {
     _outlineWidth = value == null ? '' : value;
   }
   @Returns('String')
@@ -827,7 +828,7 @@
   String get overflow => this._overflow;
 
   /** Sets the value of "overflow" */
-  set overflow(String value) {
+  set overflow(String$NULLABLE value) {
     _overflow = value == null ? '' : value;
   }
   @Returns('String')
@@ -838,7 +839,7 @@
   String get padding => this._padding;
 
   /** Sets the value of "padding" */
-  set padding(String value) {
+  set padding(String$NULLABLE value) {
     _padding = value == null ? '' : value;
   }
   @Returns('String')
@@ -849,7 +850,7 @@
   String get paddingBottom => this._paddingBottom;
 
   /** Sets the value of "padding-bottom" */
-  set paddingBottom(String value) {
+  set paddingBottom(String$NULLABLE value) {
     _paddingBottom = value == null ? '' : value;
   }
   @Returns('String')
@@ -860,7 +861,7 @@
   String get paddingLeft => this._paddingLeft;
 
   /** Sets the value of "padding-left" */
-  set paddingLeft(String value) {
+  set paddingLeft(String$NULLABLE value) {
     _paddingLeft = value == null ? '' : value;
   }
   @Returns('String')
@@ -871,7 +872,7 @@
   String get paddingRight => this._paddingRight;
 
   /** Sets the value of "padding-right" */
-  set paddingRight(String value) {
+  set paddingRight(String$NULLABLE value) {
     _paddingRight = value == null ? '' : value;
   }
   @Returns('String')
@@ -882,7 +883,7 @@
   String get paddingTop => this._paddingTop;
 
   /** Sets the value of "padding-top" */
-  set paddingTop(String value) {
+  set paddingTop(String$NULLABLE value) {
     _paddingTop = value == null ? '' : value;
   }
   @Returns('String')
@@ -893,7 +894,7 @@
   String get pageBreakAfter => this._pageBreakAfter;
 
   /** Sets the value of "page-break-after" */
-  set pageBreakAfter(String value) {
+  set pageBreakAfter(String$NULLABLE value) {
     _pageBreakAfter = value == null ? '' : value;
   }
   @Returns('String')
@@ -904,7 +905,7 @@
   String get pageBreakBefore => this._pageBreakBefore;
 
   /** Sets the value of "page-break-before" */
-  set pageBreakBefore(String value) {
+  set pageBreakBefore(String$NULLABLE value) {
     _pageBreakBefore = value == null ? '' : value;
   }
   @Returns('String')
@@ -915,7 +916,7 @@
   String get pageBreakInside => this._pageBreakInside;
 
   /** Sets the value of "page-break-inside" */
-  set pageBreakInside(String value) {
+  set pageBreakInside(String$NULLABLE value) {
     _pageBreakInside = value == null ? '' : value;
   }
   @Returns('String')
@@ -926,7 +927,7 @@
   String get position => this._position;
 
   /** Sets the value of "position" */
-  set position(String value) {
+  set position(String$NULLABLE value) {
     _position = value == null ? '' : value;
   }
   @Returns('String')
@@ -937,7 +938,7 @@
   String get quotes => this._quotes;
 
   /** Sets the value of "quotes" */
-  set quotes(String value) {
+  set quotes(String$NULLABLE value) {
     _quotes = value == null ? '' : value;
   }
   @Returns('String')
@@ -948,7 +949,7 @@
   String get right => this._right;
 
   /** Sets the value of "right" */
-  set right(String value) {
+  set right(String$NULLABLE value) {
     _right = value == null ? '' : value;
   }
   @Returns('String')
@@ -959,7 +960,7 @@
   String get tableLayout => this._tableLayout;
 
   /** Sets the value of "table-layout" */
-  set tableLayout(String value) {
+  set tableLayout(String$NULLABLE value) {
     _tableLayout = value == null ? '' : value;
   }
   @Returns('String')
@@ -970,7 +971,7 @@
   String get textAlign => this._textAlign;
 
   /** Sets the value of "text-align" */
-  set textAlign(String value) {
+  set textAlign(String$NULLABLE value) {
     _textAlign = value == null ? '' : value;
   }
   @Returns('String')
@@ -981,7 +982,7 @@
   String get textDecoration => this._textDecoration;
 
   /** Sets the value of "text-decoration" */
-  set textDecoration(String value) {
+  set textDecoration(String$NULLABLE value) {
     _textDecoration = value == null ? '' : value;
   }
   @Returns('String')
@@ -992,7 +993,7 @@
   String get textIndent => this._textIndent;
 
   /** Sets the value of "text-indent" */
-  set textIndent(String value) {
+  set textIndent(String$NULLABLE value) {
     _textIndent = value == null ? '' : value;
   }
   @Returns('String')
@@ -1003,7 +1004,7 @@
   String get textTransform => this._textTransform;
 
   /** Sets the value of "text-transform" */
-  set textTransform(String value) {
+  set textTransform(String$NULLABLE value) {
     _textTransform = value == null ? '' : value;
   }
   @Returns('String')
@@ -1014,7 +1015,7 @@
   String get top => this._top;
 
   /** Sets the value of "top" */
-  set top(String value) {
+  set top(String$NULLABLE value) {
     _top = value == null ? '' : value;
   }
   @Returns('String')
@@ -1025,7 +1026,7 @@
   String get unicodeBidi => this._unicodeBidi;
 
   /** Sets the value of "unicode-bidi" */
-  set unicodeBidi(String value) {
+  set unicodeBidi(String$NULLABLE value) {
     _unicodeBidi = value == null ? '' : value;
   }
   @Returns('String')
@@ -1036,7 +1037,7 @@
   String get verticalAlign => this._verticalAlign;
 
   /** Sets the value of "vertical-align" */
-  set verticalAlign(String value) {
+  set verticalAlign(String$NULLABLE value) {
     _verticalAlign = value == null ? '' : value;
   }
   @Returns('String')
@@ -1047,7 +1048,7 @@
   String get visibility => this._visibility;
 
   /** Sets the value of "visibility" */
-  set visibility(String value) {
+  set visibility(String$NULLABLE value) {
     _visibility = value == null ? '' : value;
   }
   @Returns('String')
@@ -1058,7 +1059,7 @@
   String get whiteSpace => this._whiteSpace;
 
   /** Sets the value of "white-space" */
-  set whiteSpace(String value) {
+  set whiteSpace(String$NULLABLE value) {
     _whiteSpace = value == null ? '' : value;
   }
   @Returns('String')
@@ -1069,7 +1070,7 @@
   String get width => this._width;
 
   /** Sets the value of "width" */
-  set width(String value) {
+  set width(String$NULLABLE value) {
     _width = value == null ? '' : value;
   }
   @Returns('String')
@@ -1080,7 +1081,7 @@
   String get wordSpacing => this._wordSpacing;
 
   /** Sets the value of "word-spacing" */
-  set wordSpacing(String value) {
+  set wordSpacing(String$NULLABLE value) {
     _wordSpacing = value == null ? '' : value;
   }
   @Returns('String')
@@ -1091,7 +1092,7 @@
   String get zIndex => this._zIndex;
 
   /** Sets the value of "z-index" */
-  set zIndex(String value) {
+  set zIndex(String$NULLABLE value) {
     _zIndex = value == null ? '' : value;
   }
   @Returns('String')
@@ -1119,7 +1120,7 @@
   }
 
 
-  void _setAll(String propertyName, String value) {
+  void _setAll(String propertyName, String$NULLABLE value) {
     value = value == null ? '' : value;
     for (Element element in _elementIterable) {
       JS('void', '#.style[#] = #', element, propertyName, value);
diff --git a/tools/dom/templates/html/impl/impl_Element.darttemplate b/tools/dom/templates/html/impl/impl_Element.darttemplate
index 3fd0d4e..67917c5 100644
--- a/tools/dom/templates/html/impl/impl_Element.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Element.darttemplate
@@ -14,7 +14,7 @@
     : _childElements = element._children,
       _element = element;
 
-  bool contains(Object element) => _childElements.contains(element);
+  bool contains(Object$NULLABLE element) => _childElements.contains(element);
 
 
   bool get isEmpty {
@@ -55,11 +55,11 @@
     }
   }
 
-  void sort([int compare(Element a, Element b)]) {
+  void sort([int compare(Element a, Element b)$NULLABLE]) {
     throw new UnsupportedError('Cannot sort element lists');
   }
 
-  void shuffle([Random random]) {
+  void shuffle([Random$NULLABLE random]) {
     throw new UnsupportedError('Cannot shuffle element lists');
   }
 
@@ -81,7 +81,7 @@
     for (var e in removed) e.remove();
   }
 
-  void fillRange(int start, int end, [Element fillValue]) {
+  void fillRange(int start, int end, [Element$NULLABLE fillValue]) {
     throw new UnimplementedError();
   }
 
@@ -98,7 +98,7 @@
     throw new UnimplementedError();
   }
 
-  bool remove(Object object) {
+  bool remove(Object$NULLABLE object) {
     if (object is Element) {
       Element element = object;
       if (identical(element.parentNode, _element)) {
@@ -280,11 +280,11 @@
     throw new UnsupportedError('Cannot modify list');
   }
 
-  void sort([Comparator<E> compare]) {
+  void sort([Comparator<E>$NULLABLE compare]) {
     throw new UnsupportedError('Cannot sort list');
   }
 
-  void shuffle([Random random]) {
+  void shuffle([Random$NULLABLE random]) {
     throw new UnsupportedError('Cannot shuffle list');
   }
 
@@ -764,7 +764,7 @@
    * * [Pseudo-elements](https://developer.mozilla.org/en-US/docs/Web/CSS/Pseudo-elements)
    *   from MDN.
    */
-  CssStyleDeclaration getComputedStyle([String pseudoElement]) {
+  CssStyleDeclaration getComputedStyle([String$NULLABLE pseudoElement]) {
     if (pseudoElement == null) {
       pseudoElement = '';
     }
@@ -1319,7 +1319,7 @@
 
       // Workaround for Safari bug. Was also previously Chrome bug 229142
       // - URIs are not resolved in new doc.
-      BaseElement base = _parseDocument.createElement('base');
+      BaseElement base = _parseDocument.createElement('base') $#NULLSAFECAST(as BaseElement);
       base.href = document.baseUri;
       _parseDocument.head.append(base);
     }
diff --git a/tools/dom/templates/html/impl/impl_Geolocation.darttemplate b/tools/dom/templates/html/impl/impl_Geolocation.darttemplate
index 456850e..a908f1d 100644
--- a/tools/dom/templates/html/impl/impl_Geolocation.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Geolocation.darttemplate
@@ -6,8 +6,8 @@
 
 $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
 
-  Future<Geoposition> getCurrentPosition({bool enableHighAccuracy,
-      Duration timeout, Duration maximumAge}) {
+  Future<Geoposition> getCurrentPosition({bool$NULLABLE enableHighAccuracy,
+      Duration$NULLABLE timeout, Duration$NULLABLE maximumAge}) {
     var options = {};
     if (enableHighAccuracy != null) {
       options['enableHighAccuracy'] = enableHighAccuracy;
@@ -34,8 +34,8 @@
     return completer.future;
   }
 
-  Stream<Geoposition> watchPosition({bool enableHighAccuracy,
-      Duration timeout, Duration maximumAge}) {
+  Stream<Geoposition> watchPosition({bool$NULLABLE enableHighAccuracy,
+      Duration$NULLABLE timeout, Duration$NULLABLE maximumAge}) {
 
     var options = {};
     if (enableHighAccuracy != null) {
diff --git a/tools/dom/templates/html/impl/impl_HTMLCanvasElement.darttemplate b/tools/dom/templates/html/impl/impl_HTMLCanvasElement.darttemplate
index c935546..409055d 100644
--- a/tools/dom/templates/html/impl/impl_HTMLCanvasElement.darttemplate
+++ b/tools/dom/templates/html/impl/impl_HTMLCanvasElement.darttemplate
@@ -84,9 +84,10 @@
       _toDataUrl(type, quality);
 
   @JSName('toBlob')
-  void _toBlob(BlobCallback callback, String type, [Object arguments]) native;
+  void _toBlob(BlobCallback callback, String type,
+      [Object$NULLABLE arguments]) native;
 
-  Future<Blob> toBlob(String type, [Object arguments]) {
+  Future<Blob> toBlob(String type, [Object$NULLABLE arguments]) {
     var completer = new Completer<Blob>();
       _toBlob((value) {
         completer.complete(value);
diff --git a/tools/dom/templates/html/impl/impl_HTMLInputElement.darttemplate b/tools/dom/templates/html/impl/impl_HTMLInputElement.darttemplate
index 3ee9b43..9f2cb3f 100644
--- a/tools/dom/templates/html/impl/impl_HTMLInputElement.darttemplate
+++ b/tools/dom/templates/html/impl/impl_HTMLInputElement.darttemplate
@@ -27,7 +27,7 @@
     ResetButtonInputElement,
     ButtonInputElement {
 
-  factory InputElement({String type}) {
+  factory InputElement({String$NULLABLE type}) {
     InputElement e = document.createElement("input");
     if (type != null) {
       try {
@@ -127,7 +127,7 @@
 
   String dirName;
 
-  Element get list;
+  Element$NULLABLE get list;
 
   /// Returns true if this input type is supported on the current platform.
   static bool get supported {
@@ -143,7 +143,7 @@
 
   String dirName;
 
-  Element get list;
+  Element$NULLABLE get list;
 }
 
 /**
@@ -158,7 +158,7 @@
 abstract class UrlInputElement implements TextInputElementBase {
   factory UrlInputElement() => new InputElement(type: 'url');
 
-  Element get list;
+  Element$NULLABLE get list;
 
   /// Returns true if this input type is supported on the current platform.
   static bool get supported {
@@ -181,7 +181,7 @@
 abstract class TelephoneInputElement implements TextInputElementBase {
   factory TelephoneInputElement() => new InputElement(type: 'tel');
 
-  Element get list;
+  Element$NULLABLE get list;
 
   /// Returns true if this input type is supported on the current platform.
   static bool get supported {
@@ -205,7 +205,7 @@
 
   bool autofocus;
 
-  Element get list;
+  Element$NULLABLE get list;
 
   int maxLength;
 
@@ -239,7 +239,7 @@
  */
 abstract class RangeInputElementBase implements InputElementBase {
 
-  Element get list;
+  Element$NULLABLE get list;
 
   String max;
 
diff --git a/tools/dom/templates/html/impl/impl_MutationObserver.darttemplate b/tools/dom/templates/html/impl/impl_MutationObserver.darttemplate
index d4f0203..46a1562 100644
--- a/tools/dom/templates/html/impl/impl_MutationObserver.darttemplate
+++ b/tools/dom/templates/html/impl/impl_MutationObserver.darttemplate
@@ -32,7 +32,7 @@
                 bool subtree,
                 bool attributeOldValue,
                 bool characterDataOldValue,
-                List<String> attributeFilter}) {
+                List<String>$NULLABLE attributeFilter}) {
 
     // Parse options into map of known type.
     var parsedOptions = _createDict();
diff --git a/tools/dom/templates/html/impl/impl_Node.darttemplate b/tools/dom/templates/html/impl/impl_Node.darttemplate
index fef9633..cfef9ae 100644
--- a/tools/dom/templates/html/impl/impl_Node.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Node.darttemplate
@@ -92,7 +92,7 @@
     return result;
   }
 
-  bool remove(Object object) {
+  bool remove(Object$NULLABLE object) {
     if (object is! Node) return false;
     Node node = object;
     if (!identical(_this, node.parentNode)) return false;
@@ -136,11 +136,11 @@
 
   // TODO(jacobr): this could be implemented for child node lists.
   // The exception we throw here is misleading.
-  void sort([Comparator<Node> compare]) {
+  void sort([Comparator<Node>$NULLABLE compare]) {
     throw new UnsupportedError("Cannot sort Node list");
   }
 
-  void shuffle([Random random]) {
+  void shuffle([Random$NULLABLE random]) {
     throw new UnsupportedError("Cannot shuffle Node list");
   }
 
@@ -150,7 +150,7 @@
     throw new UnsupportedError("Cannot setRange on Node list");
   }
 
-  void fillRange(int start, int end, [Node fill]) {
+  void fillRange(int start, int end, [Node$NULLABLE fill]) {
     throw new UnsupportedError("Cannot fillRange on Node list");
   }
 
diff --git a/tools/dom/templates/html/impl/impl_Storage.darttemplate b/tools/dom/templates/html/impl/impl_Storage.darttemplate
index 5cd76ee..ba1bf8b 100644
--- a/tools/dom/templates/html/impl/impl_Storage.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Storage.darttemplate
@@ -37,11 +37,11 @@
   }
 
   // TODO(nweiz): update this when maps support lazy iteration
-  bool containsValue(Object value) => values.any((e) => e == value);
+  bool containsValue(Object$NULLABLE value) => values.any((e) => e == value);
 
-  bool containsKey(Object key) => _getItem(key) != null;
+  bool containsKey(Object$NULLABLE key) => _getItem(key) != null;
 
-  String operator [](Object key) => _getItem(key);
+  String$NULLABLE operator [](Object$NULLABLE key) => _getItem(key $#NULLSAFECAST(as String));
 
   void operator []=(String key, String value) { _setItem(key, value); }
 
@@ -50,7 +50,7 @@
     return this[key];
   }
 
-  String remove(Object key) {
+  String$NULLABLE remove(Object$NULLABLE key) {
     final value = this[key];
     _removeItem(key);
     return value;
diff --git a/tools/dom/templates/html/impl/impl_XMLHttpRequest.darttemplate b/tools/dom/templates/html/impl/impl_XMLHttpRequest.darttemplate
index 36af958..97932b2 100644
--- a/tools/dom/templates/html/impl/impl_XMLHttpRequest.darttemplate
+++ b/tools/dom/templates/html/impl/impl_XMLHttpRequest.darttemplate
@@ -73,7 +73,7 @@
    * * [request]
    */
   static Future<String> getString(String url,
-      {bool withCredentials, void onProgress(ProgressEvent e)}) {
+      {bool$NULLABLE withCredentials, void onProgress(ProgressEvent e)$NULLABLE}) {
     return request(url, withCredentials: withCredentials,
         onProgress: onProgress).then((HttpRequest xhr) => xhr.responseText);
   }
@@ -132,7 +132,7 @@
    *
    * By default `request` will perform an HTTP GET request, but a different
    * method (`POST`, `PUT`, `DELETE`, etc) can be used by specifying the
-   * [method] parameter. (See also [HttpRequest.postFormData] for `POST` 
+   * [method] parameter. (See also [HttpRequest.postFormData] for `POST`
    * requests only.
    *
    * The Future is completed when the response is available.
@@ -141,8 +141,8 @@
    * [Blob], [Document], [String], or [FormData] along with the HttpRequest.
    *
    * If specified, [responseType] sets the desired response format for the
-   * request. By default it is [String], but can also be 'arraybuffer', 'blob', 
-   * 'document', 'json', or 'text'. See also [HttpRequest.responseType] 
+   * request. By default it is [String], but can also be 'arraybuffer', 'blob',
+   * 'document', 'json', or 'text'. See also [HttpRequest.responseType]
    * for more information.
    *
    * The [withCredentials] parameter specified that credentials such as a cookie
@@ -225,7 +225,7 @@
       // redirect case will be handled by the browser before it gets to us,
       // so if we see it we should pass it through to the user.
       var unknownRedirect = xhr.status > 307 && xhr.status < 400;
-      
+
       if (accepted || fileUri || notModified || unknownRedirect) {
         completer.complete(xhr);
       } else {
diff --git a/tools/test.dart b/tools/test.dart
index 1d982f7..aa8e9f6 100755
--- a/tools/test.dart
+++ b/tools/test.dart
@@ -10,6 +10,7 @@
 import 'dart:io';
 
 import 'package:args/args.dart';
+import 'package:smith/smith.dart';
 
 import 'bots/results.dart';
 
@@ -78,56 +79,6 @@
   return processResult;
 }
 
-/// Returns the operating system of a builder.
-String systemOfBuilder(String builder) {
-  return builder.split("-").firstWhere(
-      (component) => ["linux", "mac", "win"].contains(component),
-      orElse: () => null);
-}
-
-/// Returns the product mode of a builder.
-String modeOfBuilder(String builder) {
-  return builder.split("-").firstWhere(
-      (component) => ["debug", "product", "release"].contains(component),
-      orElse: () => null);
-}
-
-/// Returns the machine architecture of a builder.
-String archOfBuilder(String builder) {
-  return builder.split("-").firstWhere(
-      (component) => [
-            "arm",
-            "arm64",
-            "ia32",
-            "simarm",
-            "simarm64",
-            "x64",
-          ].contains(component),
-      orElse: () => null);
-}
-
-/// Returns the runtime environment of a builder.
-String runtimeOfBuilder(String builder) {
-  return builder.split("-").firstWhere(
-      (component) => ["chrome", "d8", "edge", "firefox", "ie11", "safari"]
-          .contains(component),
-      orElse: () => null);
-}
-
-/// Expands a variable in a test matrix step command.
-String expandVariable(String string, String variable, String value) {
-  return string.replaceAll("\${$variable}", value ?? "");
-}
-
-/// Expands all variables in a test matrix step command.
-String expandVariables(String string, String builder) {
-  string = expandVariable(string, "system", systemOfBuilder(builder));
-  string = expandVariable(string, "mode", modeOfBuilder(builder));
-  string = expandVariable(string, "arch", archOfBuilder(builder));
-  string = expandVariable(string, "runtime", runtimeOfBuilder(builder));
-  return string;
-}
-
 /// Finds the branch of a builder given the list of branches.
 String branchOfBuilder(String builder, List<String> branches) {
   return branches.where((branch) => branch != "master").firstWhere(
@@ -137,52 +88,36 @@
 
 /// Finds the named configuration to test according to the test matrix
 /// information and the command line options.
-Map<String, Set<String>> resolveNamedConfigurations(
-    List<String> branches,
-    List<dynamic> buildersConfigurations,
+Map<String, Set<Builder>> resolveNamedConfigurations(
+    TestMatrix testMatrix,
     String requestedBranch,
     List<String> requestedNamedConfigurations,
     String requestedBuilder) {
-  final testedConfigurations = <String, Set<String>>{};
+  assert(requestedBranch != null);
+  final testedConfigurations = <String, Set<Builder>>{};
   var foundBuilder = false;
-  for (final builderConfiguration in buildersConfigurations) {
-    for (final builder in builderConfiguration["builders"]) {
-      if (requestedBuilder != null && builder != requestedBuilder) {
+  for (final builder in testMatrix.builders) {
+    if (requestedBuilder != null && builder.name != requestedBuilder) {
+      continue;
+    }
+    final branch = branchOfBuilder(builder.name, testMatrix.branches);
+    if (branch != requestedBranch) {
+      if (requestedBuilder == null) {
         continue;
       }
-      final branch = branchOfBuilder(builder, branches);
-      if (branch != requestedBranch) {
-        if (requestedBuilder == null) {
-          continue;
-        }
-        stderr.writeln("error: Builder $requestedBuilder is on branch $branch "
-            "rather than $requestedBranch");
-        stderr.writeln("error: To compare with that branch, use: -B $branch");
-        return null;
-      }
-      foundBuilder = true;
-      final steps = (builderConfiguration["steps"] as List).cast<Map>();
-      final testSteps = steps
-          .where((step) =>
-              !step.containsKey("script") || step["script"] == "tools/test.py")
-          .toList();
-      for (final step in testSteps) {
-        final arguments = step["arguments"]
-            .map((argument) => expandVariables(argument, builder))
-            .toList();
-        final namedConfiguration = arguments
-            .firstWhere((argument) => (argument as String).startsWith("-n"))
-            .substring(2);
-        if (namedConfiguration.contains(",")) {
-          throw "Multiple named configurations in builder configurations: "
-              "are currently not supported: '$arguments'";
-        }
-        if (requestedNamedConfigurations.isEmpty ||
-            requestedNamedConfigurations.contains(namedConfiguration)) {
-          testedConfigurations
-              .putIfAbsent(namedConfiguration, () => {})
-              .add(builder);
-        }
+      stderr.writeln("error: Builder $requestedBuilder is on branch $branch "
+          "rather than $requestedBranch");
+      stderr.writeln("error: To compare with that branch, use: -B $branch");
+      return null;
+    }
+    foundBuilder = true;
+    for (final step in builder.steps.where((step) => step.isTestStep)) {
+      final namedConfiguration = step.testedConfiguration.name;
+      if (requestedNamedConfigurations.isEmpty ||
+          requestedNamedConfigurations.contains(namedConfiguration)) {
+        testedConfigurations
+            .putIfAbsent(namedConfiguration, () => {})
+            .add(builder);
       }
     }
   }
@@ -430,22 +365,12 @@
       Platform.script.resolve("../third_party/gsutil/gsutil.py").toFilePath();
 
   // Load the test matrix.
-  final scriptPath = Platform.script.toFilePath();
-  final testMatrixPath =
-      scriptPath.substring(0, scriptPath.length - "test.dart".length) +
-          "bots/test_matrix.json";
-  final testMatrix = jsonDecode(await new File(testMatrixPath).readAsString());
-  final branches = (testMatrix["branches"] as List).cast<String>();
-  final buildersConfigurations =
-      testMatrix["builder_configurations"] as List<dynamic>;
+  final testMatrixPath = Platform.script.resolve("bots/test_matrix.json");
+  final testMatrix = TestMatrix.fromPath(testMatrixPath.toFilePath());
   // Determine what named configuration to run and which builders to download
   // existing results from.
-  final testedConfigurations = resolveNamedConfigurations(
-      branches,
-      buildersConfigurations,
-      options["branch"],
-      requestedNamedConfigurations,
-      requestedBuilder);
+  final testedConfigurations = resolveNamedConfigurations(testMatrix,
+      options["branch"], requestedNamedConfigurations, requestedBuilder);
   if (testedConfigurations == null) {
     // No valid configuration could be found. The error has already been
     // reported by [resolveConfigurations].
@@ -459,8 +384,8 @@
   for (final namedConfiguration in namedConfigurations) {
     final testedBuilders = testedConfigurations[namedConfiguration];
     final onWhichBuilders = testedBuilders.length == 1
-        ? "builder ${testedBuilders.single}"
-        : "builders${testedBuilders.map((b) => "\n  $b").join()}";
+        ? "builder ${testedBuilders.single.name}"
+        : "builders${testedBuilders.map((b) => "\n  ${b.name}").join()}";
     if (localConfiguration != null) {
       print("Testing named configuration $localConfiguration "
           "compared with configuration ${namedConfiguration} "
@@ -487,28 +412,30 @@
     var downloadNumber = 0;
     // Download the previous results and flakiness info from cloud storage.
     for (final builder in builders) {
+      final builderName = builder.name;
       if (needsMerge) {
         previousFileName = "previous-$downloadNumber.json";
         flakyFileName = "flaky-$downloadNumber.json";
         downloadNumber++;
       }
-      print("Finding build on builder $builder to compare with...");
+      print("Finding build on builder $builderName to compare with...");
       // Use the buildbucket API to search for builds of the right commit.
       final buildSearchResult =
-          await searchForApproximateBuild(builder, commit);
+          await searchForApproximateBuild(builderName, commit);
       if (buildSearchResult.commit != commit) {
         print("Warning: Using commit ${buildSearchResult.commit} "
-            "as baseline instead of $commit for $builder");
-        inexactBuilds[builder] = buildSearchResult.commit;
+            "as baseline instead of $commit for $builderName");
+        inexactBuilds[builderName] = buildSearchResult.commit;
       }
       final buildNumber = buildSearchResult.build.toString();
-      print("Downloading results from builder $builder build $buildNumber...");
+      print("Downloading results from builder $builderName "
+          "build $buildNumber...");
       tasks.add(cpGsutil(
-          buildFileCloudPath(builder, buildNumber, "results.json"),
+          buildFileCloudPath(builderName, buildNumber, "results.json"),
           "${outDirectory.path}/$previousFileName"));
       if (!options["report-flakes"]) {
         tasks.add(cpGsutil(
-            buildFileCloudPath(builder, buildNumber, "flaky.json"),
+            buildFileCloudPath(builderName, buildNumber, "flaky.json"),
             "${outDirectory.path}/$flakyFileName"));
       }
     }
diff --git a/utils/application_snapshot.gni b/utils/application_snapshot.gni
index dd990c8..92c1921 100644
--- a/utils/application_snapshot.gni
+++ b/utils/application_snapshot.gni
@@ -115,9 +115,6 @@
       "--no-link-platform",
       "--output=" + rebase_path(output),
     ]
-    if (use_nnbd) {
-      args += [ "--enable-experiment=non-nullable" ]
-    }
     if (dart_platform_bytecode) {
       args += [
         "--gen-bytecode",
@@ -150,10 +147,6 @@
                 "--snapshot-depfile=$abs_depfile",
               ] + snapshot_vm_args
 
-    if (use_nnbd) {
-      vm_args += [ "--enable-experiment=non-nullable" ]
-    }
-
     if (dart_snapshot_kind == "kernel") {
       vm_args += [ "--snapshot-kind=kernel" ]
       assert(training_args != "", "Ignoring unused argument")
diff --git a/utils/kernel-service/BUILD.gn b/utils/kernel-service/BUILD.gn
index e25fb85..fd63749 100644
--- a/utils/kernel-service/BUILD.gn
+++ b/utils/kernel-service/BUILD.gn
@@ -115,9 +115,6 @@
           "--no-embed-sources",
           "--output=" + rebase_path(output),
         ]
-    if (use_nnbd) {
-      args += [ "--enable-experiment=non-nullable" ]
-    }
     args += [ scheme + ":///pkg/vm/bin/kernel_service.dart" ]
     if (dart_platform_bytecode) {
       args += [